Дисертації: "Pipelined methods"

1

Beckwith, Luke Parkhurst. "An Investigation of Methods to Improve Area and Performance of Hardware Implementations of a Lattice Based Cryptosystem." Thesis, Virginia Tech, 2020. http://hdl.handle.net/10919/100798.

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With continuing research into quantum computing, current public key cryptographic algorithms such as RSA and ECC will become insecure. These algorithms are based on the difficulty of integer factorization or discrete logarithm problems, which are difficult to solve on classical computers but become easy with quantum computers. Because of this threat, government and industry are investigating new public key standards, based on mathematical assumptions that remain secure under quantum computing. This paper investigates methods of improving the area and performance of one of the proposed algorithms for key exchanges, "NewHope." We describe a pipelined FPGA implementation of NewHope512cpa which dramatically increases the throughput for a similar design area. Our pipelined encryption implementation achieves 652.2 Mbps and a 0.088 Mbps/LUT throughput-to-area (TPA) ratio, which are the best known results to date, and achieves an energy efficiency of 0.94 nJ/bit. This represents TPA and energy efficiency improvements of 10.05× and 8.58×, respectively, over a non-pipelined approach. Additionally, we investigate replacing the large SHAKE XOF (hash) function with a lightweight Trivium based PRNG, which reduces the area by 32% and improves energy efficiency by 30% for the pipelined encryption implementation, and which could be considered for future cipher specifications.
Master of Science
Cryptography is prevalent in almost every aspect of our lives. It is used to protect communication, banking information, and online transactions. Current cryptographic protections are built specifically upon public key encryption, which allows two people who have never communicated before to setup a secure communication channel. However, due to the nature of current cryptographic algorithms, the development of quantum computers will make it possible to break the algorithms that secure our communications. Because of this threat, new algorithms based on principles that stand up to quantum computing are being investigated to find a suitable alternative to secure our systems. These algorithms will need to be efficient in order to keep up with the demands of the ever growing internet. This paper investigates four hardware implementations of a proposed quantum-secure algorithm to explore ways to make designs more efficient. The improvements are valuable for high throughput applications, such as a server which must handle a large number of connections at once.

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2

Sever, Refik. "Wave Component Sampling Method For High Performance Pipelined Circuits." Phd thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613893/index.pdf.

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In all of the previous pipelining methods such as conventional pipelining, wave pipelining, and mesochronous pipelining, a data wave propagating on the combinational circuit is sampled whenever it arrives to a synchronization stage. In this study, a new wave-pipelining methodology named as Wave Component Sampling Method (WCSM), is proposed. In this method, only the component of a wave, whose maximum and minimum delay difference exceeds the tolerable value, is sampled, and the other components continue to propagate on the circuit. Therefore, the total number of registers required for synchronization decreases significantly. For demonstrating the effectiveness of the proposed WCSM, an 8x8 bit carry save In all of the previous pipelining methods such as conventional pipelining, wave pipelining, and mesochronous pipelining, a data wave propagating on the combinational circuit is sampled whenever it arrives to a synchronization stage. In this study, a new wave-pipelining methodology named as Wave Component Sampling Method (WCSM), is proposed. In this method, only the component of a wave, whose maximum and minimum delay difference exceeds the tolerable value, is sampled, and the other components continue to propagate on the circuit. Therefore, the total number of registers required for synchronization decreases significantly. For demonstrating the effectiveness of the proposed WCSM, an 8x8 bit carry save adder (CSA) multiplier is implemented using 0.18µ
m CMOS technology. A generic transmission gate logic block with optimized output delay variation depending on the input pattern is designed and used in all of the sub blocks of the multiplier. Post layout simulation results show that, this multiplier can operate at a speed of 3GHz, using only 70 latches. Comparing with the mesochronous pipelining scheme, the number of the registers is decreased by 41% and the total power of the chip is also decreased by 9.5% without any performance loss. An ultra high speed full pipelined CSA multiplier with an operating frequency of 5GHz is also implemented with WCSM. The number of registers is decreased by 45%, and the power consumption of the circuit is decreased by 18.4% comparing with conventional or mesochronous pipelining methods. WCSM is also applied to different multiplier structures employing booth encoders, Wallace trees, and carry look-ahead adders. Comparing full pipelined 8x8 bit WCSM multiplier with the conventional pipelined multiplier, the number of registers in the implementation of booth encoder, Wallace tree, and carry look-ahead adder is decreased by 30%, 51%, and %62, respectively.

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3

Bettis, Dane Edward. "Digital production pipelines: examining structures and methods in the computer effects industry." Thesis, Texas A&M University, 2005. http://hdl.handle.net/1969.1/2406.

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Computer animated films require collaboration: blending artistic concept with technical skill, meeting budget constraints and adhering to deadlines. The path which production follows from initial idea to finished product is known as the pipeline. The purpose of this thesis is to collect, study and share information regarding production pipeline practices and to derive a conceptual definition. Research focused on selected companies in the United States which have produced at least one feature-length computer generated film and continue to produce them. The key finding of this thesis is a conceptual definition of digital production pipelines: A digital production pipeline must, by definition, utilize digital computing hardware and software to facilitate human work and collaboration for the overarching purpose of producing content for film. The digital production pipeline is not a structure, but rather a malleable set of components which can be arranged, configured, and adapted into new structures as needed. These malleable components are human groups with assigned task domains, and digital hardware and software systems. The human groups are normally referred to as departments or teams. The digital hardware and software systems are operating systems, software tools and applications, networks, processors, and storage. The digital production pipeline is the synergy of these two types of components into adaptable systems and structures.

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4

Durrani, Jawad Nadeem. "Dynamics of pipelines with a finite element method." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ65153.pdf.

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5

Laricchia, Francesco. "Study of offshore flexible pipelines with analytical and numerical methods." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.

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The work outlined presents three different analytical approaches for analyze a flexible pipelines, combined in one unified formulation. Additionally, a finite element model of an unbonded flexible riser is presented. Are reported results and discussion about a flexible pipeline subjected to a tensional load and internal pressure and focus on Axial tension-elongation curves under different lay angles of helical tendons.

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6

Wood, Stephen L. "Modeling of Pipeline Transients: Modified Method of Characteristics." FIU Digital Commons, 2011. http://digitalcommons.fiu.edu/etd/456.

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The primary purpose of this research was to improve the accuracy and robustness of pipeline transient modeling. An algorithm was developed to model the transient flow in closed tubes for thin walled pipelines. Emphasis was given to the application of this type of flow to pipelines with small radius 90° elbows. An additional loss term was developed to account for the presence of 90° elbows in a pipeline. The algorithm was integrated into an optimization routine to fit results from the improved model to experimental data. A web based interface was developed to facilitate the pre- and post- processing operations. Results showed that including a loss term that represents the effects of 90° elbows in the Method of Characteristics (MOC) [1] improves the accuracy of the predicted transients by an order of magnitude. Secondary objectives of pump optimization, blockage detection and removal were investigated with promising results.

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7

Shirazi, Nabeel. "Methods and tool for implementing run-time reconfigurable FPGA designs." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313986.

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8

Benkherouf, A. "Failure identification methods for detecting leaks in pipelines and sensor faults." Thesis, University of Manchester, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375341.

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9

Alam, Muhammad Shafiqul. "Lattice Boltzmann modelling of two and three-dimensional flow and scour around offshore pipelines." University of Western Australia. School of Civil and Resource Engineering, 2009. http://theses.library.uwa.edu.au/adt-WU2009.0161.

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[Truncated abstract] The hydrodynamic forces on a marine pipeline and the local scour around it are the most serious and important issues in designing and maintaining pipelines. This thesis explores the vortex shedding phenomena for the flow over smooth surface and rough surface isolated cylinders. This thesis also explores the two-dimensional and three-dimensional scour process beneath offshore pipelines numerically. A series of numerical models are proposed in this dissertation for the prediction of flow characteristics and the time development of local scour around pipelines. All the models presented in this thesis are deliberately developed based on novel lattice Boltzmann method (LBM), because in recent years it has been considered as a serious alternative to standard computational fluid dynamics (CFD) as it is ideally suited to massively parallel computations. The lattice Boltzmann method is described in details to reveal how it recovers the Navier- Stokes equations. Various grid refinement schemes available in literature are discussed and a slightly modified new scheme is proposed to remove oscillatory solutions at high velocity change regime. The proposed scheme is then validated against bench mark tests for low Reynolds number flow. A turbulent model based on LBM is developed in order to predict the vortex shedding flow around an isolated square smooth surface cylinder. The various local and global flow parameters and structure of vortices are validated against experimental and numerical data available in literature. The model is then extended to investigate the vortex shedding flow over an isolated rough surface cylinder as it has an engineering significance in the design process of pipelines. The model is employed to investigate the influence of pipe roughness on various local and global parameters of flow. ... Significant part of this thesis is aimed at modelling flow and local scour around pipelines employing LBM and cellular automata (CA) methods. The erosion mechanism of the CA method available in literature for sand particles is improved by defining the threshold of sediment entrainment on bed in a similar manner to that employed in the traditional scour models. The predicted scour profiles for various incoming flow conditions are found to compare well with the experimental results reported in the literature. The existence of lee wake erosion due to continuous generation of vortex shedding in the lee of the pipelines is revealed. The time development of the maximum scour depth below the pipe is also found to be in good agreement with the experimental measurements reported in literature Finally, a three-dimensional flow and scour model is developed in order to explore the scour process beneath pipelines. It is revealed that the three-dimensionality effects are more pronounced near the span shoulder. On the other hand, there exists a two-dimensional scour regime in the vicinity of the middle section of the suspended pipe. It is found that the propagation speed of the scour hole in the sapnwise direction remains almost constant at all stages of scour process.

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10

ARAMAKI, THIAGO LESSA. "DEVELOPMENT AND VALIDATION OF METHODS FOR DETECTION AND LOCALIZATION OF PIPELINE LEAKS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2016. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=27567@1.

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Empresas que operam dutos possuem como uma de suas premissas básicas a segurança operacional. Dentro desse quesito, alguns fatores podem levar a acidentes com possibilidade de danos materiais, ambientais e pessoais, tais como: corrosão interna e externa, escavações acidentais, operações indevidas levando o duto a pressões excessivas, assim como ações de terceiros cujo objetivo seria o furto de produtos refinados, gasolina, diesel, álcool, entre outros. Esta dissertação está alinhada com necessidades reais de empresas relacionadas ao transporte de produtos líquidos por dutos, desenvolvendo sistemas que possam vir a ser utilizados nestas empresas. Foram desenvolvidos sistemas de detecção e localização de vazamentos a serem utilizados em um centro de controle operacional de oleodutos, investigando métodos não convencionais, além dos mencionados pela norma API 1130. Foram desenvolvidos sistemas de detecção de vazamento por balanço de massa, balanço de volume, lógica fuzzy e redes neurais artificiais. Para localização de vazamentos, foram testados os métodos por redes neurais, pela estimativa da velocidade sônica e do gradiente hidráulico. Os produtos utilizados foram gasolina, diesel e óleo combustível. No quesito detecção de vazamento, o sistema baseado em redes neurais detectou vazamentos simulados, porém também indicou indevidamente. O sistema baseado em lógica fuzzy apresentou bons resultados, indicando vazamentos corretamente sem falsos positivos, interpretando corretamente os fenômenos inerentes à operação de dutos. O sistema de balanço de massa também apresentou bons resultados, ou seja, não gerou alarmes falsos, detectando corretamente os vazamentos simulados, inclusive para detecção de vazamento com duto parado e pressurizado. Para avaliar sistemas de detecção de vazamento é comum realizar testes de campo que podem ter um custo alto e levar muito tempo para realizar. Um método para realizar testes a um custo inferior deve ser desenvolvido e uma proposta está sendo mostrada nesta dissertação.
Companies in the business of pipeline operations have as a basic assumption, operational security. Concerning this issue, there are some factors that could lead to accidents with material, environment and personal damage possibilities such as: internal and external corrosion, accidental excavations, improper operation that could submit the pipe to high pressures and third party interventions interested in commodities theft. This dissertation is aligned with pipeline companies real demands through the development of systems that could be used by these companies. Leak detection systems provided with leak location capabilities were developed to be used in liquid pipeline control centers, exploring non-conventional methods, besides the ones mentioned by API 1130. The leak detection systems developed were: mass balance, volume balance, fuzzy logic and neural networks. For the leak location systems the systems tested were: sonic velocity, hydraulic gradient and artificial neural networks. The products used were gasoline, diesel and fuel oil. On the issue of leak detection, the system based on neural networks detected simulated leakages, although there were some false indications. The system based on fuzzy logic presented good results, giving correct leak indications without any indication of false alarms, interpreting correctly the phenomena due to pipeline usual operations. The mass balance system has also presented good results, not generating false alarms, but detecting simulated leaks even with the pipeline in shut-in condition. To evaluate leak detection systems is common to conduct field tests that can be costly and take a long time to accomplish. A method for testing at a lower cost should be developed and a proposal is being shown in this work.

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11

García, Pérez Ana E., Carlos Allende Prieto, Jon A. Holtzman, Matthew Shetrone, Szabolcs Mészáros, Dmitry Bizyaev, Ricardo Carrera, et al. "ASPCAP: THE APOGEE STELLAR PARAMETER AND CHEMICAL ABUNDANCES PIPELINE." IOP PUBLISHING LTD, 2016. http://hdl.handle.net/10150/621372.

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The Apache Point Observatory Galactic Evolution Experiment (APOGEE) has built the largest moderately high-resolution (R approximate to 22,500) spectroscopic map of the stars across the Milky Way, and including dust-obscured areas. The APOGEE Stellar Parameter and Chemical Abundances Pipeline (ASPCAP) is the software developed for the automated analysis of these spectra. ASPCAP determines atmospheric parameters and chemical abundances from observed spectra by comparing observed spectra to libraries of theoretical spectra, using. 2 minimization in a multidimensional parameter space. The package consists of a FORTRAN90 code that does the actual minimization and a wrapper IDL code for book-keeping and data handling. This paper explains in detail the ASPCAP components and functionality, and presents results from a number of tests designed to check its performance. ASPCAP provides stellar effective temperatures, surface gravities, and metallicities precise to 2%, 0.1 dex, and 0.05 dex, respectively, for most APOGEE stars, which are predominantly giants. It also provides abundances for up to 15 chemical elements with various levels of precision, typically under 0.1 dex. The final data release (DR12) of the Sloan Digital Sky Survey III contains an APOGEE database of more than 150,000 stars. ASPCAP development continues in the SDSS-IV APOGEE-2 survey.

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12

Bhimanadhuni, Sowmya. "Development of a Performance Index for Stormwater Pipeline Infrastructure." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/54936.

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With new government regulations and emerging knowledge of the risk to the environment posed by the failure of stormwater pipelines, stormwater infrastructure asset management is becoming increasingly important in the U.S. An essential aspect of asset management practice is the accurate performance assessment of one's assets. This paper presents a weighted factor framework to determine the performance of stormwater pipes. This paper prepares a list of 50 parameters affecting the performance of stormwater pipelines; the list is based on a review of the literature, existing asset management plans, and feedback from utilities. This list is broken down into essential and preferential parameters. Indeed, not all utilities necessarily possess sufficient resources to collect such a large set of parameters. This study also develops a three-level hierarchical structure of the degradation of stormwater pipeline infrastructure. The structure consists of five failure modules and the essential parameters only. On the basis of the survey results gathered from 10 utilities across the EPA regions, the study combines the essential parameters into a performance index. The index is a scale of 1 to 5, similar to the National Association of Sewer Service Companies' Pipeline Assessment and Certification Program grading system. Grade 1 implies excellent condition and Grade 5 implies collapse is imminent.
Master of Science

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13

Brown, Gregor J. "Development and modelling of ultrasonic methods for flow measurement in oil production pipelines." Thesis, Glasgow Caledonian University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.404654.

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14

Teh, Chii Jyh. "CO2 Capture by the Integrated VSA/Cryogenics method including Pipeline Transportation." Thesis, Curtin University, 2017. http://hdl.handle.net/20.500.11937/48762.

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This thesis proposes a hybrid technology of vacuum swing adsorption and cryogenic liquefaction to capture CO2 at high recovery with an energy penalty comparable with the traditional amine absorption process. After the capture, this thesis also proposes a pipeline transportation system which utilizes the ground/ambient temperature to retain its liquid phase. Significant amount of laboratory experiment and software simulation have been conducted and conclusions and recommendation have been provided for future research work.

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15

GUZMAN, OLDRICH JOEL ROMERO. "A CONSERVATIVE METHOD TO ANALYSE TRANSIENT FLOW OF GASES/LIQUIDS IN PIPELINES." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 1999. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=1796@1.

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O presente trabalho tem como principal objetivo resolver numericamente o escoamento de líquidos e gases isotérmicos ou não, no regime transiente em tubulações industriais com área variável. Pretende-se ainda, investigar os campos de velocidade,pressão e temperatura na presença de vazamentos na tubulação. O código computacional implementado resolve as equações de conservação de massa, quantidade de movimento linear e da energia na sua forma conservativa. Este enfoque permite obter resultados importantes, dentre os quais pode- se destacar a capacidade de reproduzir as perturbações nos campos de velocidade e pressão, uma vez iniciado o vazamento do fluido num determinado instante de tempo e em qualquer ponto da tubulação. Para a solução numérica do escoamento unidimensional em coordenadas retangulares utilizou-se o método de volumes finitos. A discretização espacial foi realizada baseada no método - upwind - e para a discretização temporal utilizou- se o método totalmente implícito. As equações de conservação de massa e quantidade de movimento linear são resolvidas diretamente, através da solução de uma matriz hepta-diagonal. A seguir resolvese a equação da energia por um algoritmo para matrizes tri- diagonais. Como as equações são não lineares, um processo iterativo é necessário. Para validar o metodologia empregada, são efetuados vários testes com casos registrados na literatura e resolvidos problemas que apresentam solução analítica. Uma comparação entre o enfoque conservativo e não conservativo é apresentada. Finalmente,investiga-se a resposta do campo de pressão e velocidade para a presença de vazamentos na tubulação.
The main objective of the present work is to solve numerically the flow of liquid and gases isothermal or not, in the transient regime, in industrial pipes with variable area. It also has as objective to investigate the velocity, pressure and temperature field in the presence of fluid leak in the pipe. The numerical code was implemented to solve the conservation of mass, momentum, and energy in its conservative form. This approach is very convenient to study the perturbations in the velocity and temperature fields, once a leakage is detected in some point along the point, in a certain time. The numerical solution for the one-dimensional flow in rectangular coordinates is obtained by the finite volume method. The spatial discretization is based on the upwind method and totally implicit time integration is employed. The conservation of mass and linear momentum are directly solved through an hepta-diagonal matrix algorithm, followed by the solution of the energy equation by a three-diagonal algorithm. Since the conservation equations are non- linear, an iterative procedure is necessary. To validate the methodology presented, several tests of different case tests available in the literature were solved, as well as tests with analytical solution. A comparison between the conservative and non-conservative approach is presented. Finally, some test cases with leakage are examined.
El presente trabajo tiene como principal objetivo resolver numéricamente el flujo de líquidos y gases isotérmicos o no, en régimen transitorio, en tuberías industriales con área variable. Se pretenden investigar los campos de velocidad, presión y temperatura en presencia de escape en la tubería. El código computacional implementado resuelve las ecuaciones de conservación de masa, cantidad de movimiento lineal y de la energía en su forma conservativa. Este enfoque permite obtener resultados importantes, dentro de los cuales cabe destacar la capacidad de reproducir las perturbaciones en los campos de velocidad y presión, una vez iniciado el escape del fluido en un determinado instante de tiempo y en cualquier punto de la tubería. Para la solución numérica del flujo unidimensional en coordenadas rectangulares se utilizó el método de volúmenes finitos. La discretización espacial se realizó a través del método - upwind - y para la discretización en el tiempo, se utilizó el método totalmente implícito. Las ecuaciones de conservación de masa y de cantidad de movimiento lineal se resuelven directamente, a través de la solución de una matriz heptadiagonal. A seguir se resuelve la ecuación de la energía por un algoritmo para matrizes tri-diagonales. Como las ecuaciones son no lineales, se necesita un proceso iterativo. Para evaluar la metodología utilizada, se efectúan varios experimentos con casos registrados en la literatura y se resuelven algunos problemas que presentan solución analítica. Se presenta una comparación entre el enfoque conservativo y no conservativo. Finalmente, se investiga la respuesta del campo de presión y velocidad en presencia de escapes en la tubería.

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16

Fowler, Christopher G. "Robust estimation of limit loads for cracked components." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0001/MQ42382.pdf.

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17

Pursel, Eugene Ray. "Synthetic vision : visual perception for computer generated forces using the programmable graphics pipeline /." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Sep%5FPursel.pdf.

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Thesis (M.S. in Modeling, Virtual Environments and Simulation (MOVES))--Naval Postgraduate School, Sept. 2004.
Thesis Advisor(s): Christian J. Darken. Includes bibliographical references (p. 93-95). Also available online.

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18

Koc, Gencer. "Simulation Of Flow Transients In Liquid Pipeline Systems." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/2/12609018/index.pdf.

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ABSTRACT SIMULATION OF FLOW TRANSIENTS IN LIQUID PIPELINE SYSTEMS Koç
, Genç
er M.S., Department of Mechanical Engineering Supervisor: Prof. Dr. O. Cahit Eralp November 2007, 142 pages In liquid pipeline systems, transient flow is the major cause of pipeline damages. Transient flow is a situation where the pressure and flow rate in the pipeline rapidly changes with time. Flow transients are also known as surge and Waterhammer which originates from the hammering sound of the water in the taps or valves. In liquid pipelines, preliminary design parameters are chosen for steady state operations, but a transient check is always necessary. There are various types of transient flow situations such as valve closures, pump trips and flow oscillations. During a transient flow, pressure inside the pipe may increase or decrease in an unexpected way that cannot be foreseen by a steady state analysis. Flow transients should be considered by a complete procedure that simulates possible transient flow scenarios and by the obtained results, precautions should be taken. There are different computational methods that can be used to solve and simulate flow transients in computer environment. All computational methods utilize basic v flow equations which are continuity and momentum equations. These equations are nonlinear differential equations and some mathematical tools are necessary to make these equations linear. In this thesis a computer program is coded that utilizes &ldquo
Method of Characteristics&rdquo
which is a numerical method in solving partial differential equations. In pipeline hydraulics, two partial differential equations, continuity and momentum equations are solved together, in order to obtain the pressure and flow rate values in the pipeline, during transient flow. In this thesis, MATLAB 7.1 is used as the programming language and obtained code is converted to a C# language to be able to integrate the core of the program with a user friendly Graphical User Interface (GUI). The Computer program is verified for different scenarios with the available real pipeline data and results of various reputable agencies. The output of the computer program is the tabulated pressure and flow rate values according to time indexes and graphical representations of these values. There are also prompts for users warning about possible dangerous operation modes of the pipeline components.

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19

Han, Qiang. "An Error-Tolerant Dynamic Voltage Scaling Method for Low-Power Pipeline Circuit Design." University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1326828185.

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20

Khouri, Raoul-Emil Roger. "Two-photon calcium imaging sequence Analysis Pipeline : a method for analyzing neuronal network activity." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/119748.

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Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2018.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (page 73).
Investigating the development of neuronal networks can help us to identify new therapies and treatments for conditions that affect the brain, such as autism and Alzheimer's disease. Two-photon calcium imaging has been a powerful tool for the investigation of the development of neuronal networks. However, one of the major challenges of working with two-photon calcium images is processing the large data sets, which often requires manual analysis by a skilled researcher. Here, we introduce a machine learning (ML) pipeline for the analysis of two-photon calcium image sequences. This semi-autonomous ML pipeline includes proposed methods for automatically identifying neurons, signal extraction, signal processing, event detection, feature extraction, and analysis. We run our ML pipeline on a dataset of two-photon calcium image sequences extracted by our team. This dataset includes two-photon calcium image sequences of spontaneous network activity from primary cortical cultures of Mecp2-deficient and wild-type mice. Loss-of-function mutation in the MECP2 gene, causes 95% of Rett syndrome cases and some cases of autism. We evaluate our ML pipeline using this dataset. Our ML pipeline reduces the time required to analyze two-photon calcium images from over 10 minutes to about 30 seconds per sample. Our goal is to accelerate the analysis of neuronal network function to aid in our understanding of neurological disorders and the identification of novel therapeutic targets.
by Raoul-Emil Roger Khouri.
M. Eng.

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21

Liang, Zuodong. "Three-Dimensional Model for Seabed Instability around Offshore Pipelines under Combined Wave and Current Loadings." Thesis, Griffith University, 2020. http://hdl.handle.net/10072/391522.

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Seabed stability near offshore pipelines is one of the main concerns in engineering practice, being potentially affected by waves and ocean currents. The traditional model used to analyse soil behaviour near the pipeline assumes a two-dimensional interaction between the seabed and the marine structure. In other words, it is generally believed that the waves travel in the direction of the pipe. However, the actual marine environment is three-dimensional, with waves and currents approaching the structure from all directions. Based on a wide review of the literature, it may be claimed that the simplified 2D model no longer simulates the complex layouts of environment where offshore pipelines can be built, which should be represented as an integrated system. Therefore, the main objective of this project is to study the mechanism of soil response and liquefaction caused by waves and currents in the porous seabed near the offshore pipeline from a three-dimensional perspective. A three-dimensional numerical model is developed based on the Finite Volume Method (FVM) to analyse the instantaneous soil behaviour under the combined loads from both ocean waves and currents. In this integrated model, the hydrodynamic model is governed by the VARANS (Volume-Averaged Reynods Averaged Navier-Stokes) equation for simulating the two-phase incompressible flow motion outside and inside the porous media. The Biot’s consolidation equations are then solved for the soil responses by linking the dynamic wave pressure on the interface between the wave and seabed. The seabed behaviour is considered to be linear elastic with inversely small deformations. Overall good agreement with laboratory experimental measurements validates this newly proposed 3-D model. The numerical results reveal that the flow obliquity between the incident waves and the ocean currents has a non-negligible effect on the instantaneous pore-water pressure around the submarine pipeline, a phenomenon that cannot be observed in two dimensional numerical model. Further, a parametric study is conducted to show that the instantaneous pore-water pressure around the pipeline increases with decreasing flow obliquity; such influence can significantly increase with the increasing current velocity. Moreover, the liquefaction zone is more easily observed near the inlet of the ocean currents. By adopting the established FVM model, a numerical study on the soil response caused by waves and ocean currents near the trench structure has been conducted. The numerical results show that an offshore pipeline positioned in a trench layer is more stable than one directly laid on the seafloor. The following ocean currents can increase the liquefaction depth below the pipeline, while the opposing ocean currents can reduce the liquefaction depth near the pipeline. Moreover, the lee-wake vortex can be avoided with enough backfill thickness, which also decreases the occurrence of the onset of scour around the pipeline. Also, the nonlinear wave-current-induced seabed response around a pipe-protective cover system was investigated using the 3-D integrated model developed in OpenFOAM®. It was shown that, with sufficient quantity of stone covers and protective mattresses, the stability of the system can be maintained even with large current velocities. At this point, valuable suggestions can be drawn from the numerical results and then applied to engineering applications: (i) different backfill materials can be used to maintain the stability of a trenched pipeline with critical backfill thickness;(ii) pipelines laid directly on the surface of the seabed can be protected by a full stone cover or protective mattress under the environmental loadings from both ocean waves and currents with different directions; (iii) the protective mattress can be economically constructed over the pipeline with critical spacing to avoid an increase in the engineering budget.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Eng & Built Env
Science, Environment, Engineering and Technology
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22

Papakonstantinou, Nikolaos. "Examining LUMBA UVES pipeline spectroscopy on giant and sub-giant stars of M67." Thesis, Uppsala universitet, Observationell astrofysik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-448637.

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In this work, the efficiency of the LUMBA UVES pipeline for processing of spectroscopic observations is tested by use on 23 high-resolution spectra of the open star cluster M67. An abundance trend discovered by Gavel et al. (2019) concerning iron abundances of giant and sub-giant stars of that cluster is examined. An initial run for a set of ”Gaia FGK benchmark stars”, as described in Blanco-Cuaresma et al. (2014) and Heiter et al. (2015) helps inspect the structure, method and output of the pipeline. Through Python language programming, processes are greatly automatized and the pipeline is run for a total of 460 weak and strong iron lines of our 23-star sample. The line fitting and efficiency of the pipeline is appreciated by statistically analyzing the results and looking into individual discrepant ones. The abundance trend is reproduced while using FeI lines, unlike runs using FeII lines. Trends in abundance over line strength plots also hint at bias through the Gaia-Eso Survey (GES) microturbulence relation. Using internal Data Release 6 (iDR6) and LUMBA-derived starting parameters, log(g) - Teff plots of our sample stars agree with a previously established 4.3 Gyr cluster age. An alternate run is performed for those stars, using LUMBA-derived starting parameters. The choice of starting parameters does impact abundance derivation, but is not the primary source of persistent systematic discrepancies.

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23

Johansson, Emma, and Vilborg Pétursdóttir. "Evaluation of Onshore Transportation Methods for Captured CO2 between Facility and Harbour in Stockholm." Thesis, KTH, Maskinkonstruktion (Avd.), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-297664.

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Carbon capture and storage (CCS) is a method to reduce the emission of CO2 into the atmosphere. Stockholm Exergi is a Stockholm based company with combined heat and power (CHP) plants in various places around the city and are currently investigating the possibilities to implement CCS on their CHP plant Högdalenverket. The captured CO2 is required to be transferred from the facility to a harbour for further transport to its injection site. This report investigates the optimal means of transportation from the facility to harbour. The methods considered are pipeline and trucks.From the frame of reference, it is concluded that the shortest distance possible is preferable, so the harbour alternative is set to be Värtan. For pipelines the cheapest alternative of the state of form, for the specific case, is gas. For trucks the best alternative is liquid since a larger amount can fit in each load. For the cost estimation the method from (Piessenset al., 2008) is used to calculate the price estimate of pipelines, and (Marufuzzaman, 2015) is used for the trucks. Parameters such as the diameter of the pipe, pressure drop and power requirement are of high importance for the pipeline. For truck road regulations, CO2’s density and operation time is essential. The results from the implementation shows the pipelines to be the more beneficial option in regards to price, stability and robustness. The NPV for the pipeline is calculated, with the lifetime of theproject as 25 years, to be 75 million €, which is the cheaper alternative compared to the truck, which has a NPV of 95 million €. The optimal inlet pressure for the pipes is calculated to be 3.5MPa and the temperature to be 57.5°C due to an implemented heat exchange operation before the inlet. Future work and recommendations are to continue creating a more detailed design over the pipelines and to discard the truck transport alternative.
Infångning och lagring av koldioxid (CCS) är en metod för att minska utsläppen av CO2 i atmosfären. Stockholm Exergi är ett energibolag i Stockholm med diverse kraftvärmeverk runtom i staden. En undersökning pågår där företaget forskar kring möjligheterna att implementera CCS på kraftvärmeverk Högdalenverket. Den uppfångade koldioxiden ska transporteras från anläggning till hamn, där den sedan ska vidare med skepp till sin injektionsplats. Denna rapport studerar vilken den optimala metoden för transport från anläggning till hamn är. Metoderna som berörs är rörledningar och lastbilar. Från bakgrundstudien var det möjligt att dra slutsatsen om att det kortaste möjliga avståndet är optimalt, så den valda hamnen är Värtahamnen. För rörledningarna är det billigaste alternativet på substansen gas för det behandlade fallet i rapporten. För lastbilsalternativet är den optimala formen vätska då det får plats mer volym per last. För uppskattningen av priserna används metoden från (Piessenset al., 2008) för rörledningarna och (Marufuzzaman, 2015) för lastbilarna. Parametrar såsom diametern på rören, tryckfall och effektkrav är viktiga för rörledningarna. För lastbilarna är vägkrav, CO2 s densitet och operationstid essentiella. Resultaten från implementationen visar att transport med rörledningar är det optimala alternativet i avseende av pris och stabilitet. Nuvärdet på investeringen av rörledningarna är beräknade till 75miljoner €, som är billigare jämfört med 95 miljoner € för lastbilsalternativet. Det optimala trycket för inloppet till rörledningarna är beräknat till 3.5 MPa och inloppstemperaturen till 57.5°C som resultat av en implementerad värmeväxlaroperation precis före starten på rörledningen. Framtida arbete och rekommendationer är att fortsätta utveckla en mer detaljerad design överrörledningen och att avfärda alternativet med transport av lastbilar.

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24

Macaro, Giulia. "Distinct element modelling of pipe-soil interaction for offshore pipelines on granular soils." Thesis, University of Oxford, 2015. http://ora.ox.ac.uk/objects/uuid:cf38c129-502f-4d7d-aa8c-fea5d95ad2d2.

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Offshore on-bottom pipelines are subjected to cycles of thermal and pressure-induced axial expansion, which can cause them to buckle laterally. For an elegant and cost-effective solution, lateral buckling is allowed in a controlled manner. Of the various design parameters, the soil resistance has the greatest associated uncertainty. Previous studies of lateral pipe-soil interaction have used laboratory model tests and continuum-based numerical methods. However, they are economically and computationally expensive, and have mostly been restricted to pipes on undrained clay. To overcome this limitation, this thesis introduces the distinct element method (DEM) as a novel numerical tool for the study of lateral pipe-soil interaction for partially embedded offshore pipelines on sandy seabeds. The DEM directly models the particulate nature of sandy soils, allowing large displacements of discrete bodies and providing insights into the mechanics of the soil at a particle level. Pipe{soil interaction is studied by DEM analyses through four separate research stages: (i) mechanical characterisation of the soil, (ii) specimen preparation and pipeline implementation, (iii) small displacement pipe loading tests and (iv) large displacement pipe loading tests. The soil is modelled as an assembly of spherical particles exchanging contact forces, energy and momentum when they interact. At the microscopic scale, a novel moment-relative rotation contact law is introduced to account for the irregular shape of real sand grains. At a macroscopic scale, the mechanical behaviour of the sand is calibrated using experimental triaxial test data. Additional work includes the numerical preparation of a soil assembly and the implementation of a pipeline object in the open-source DEM code Yade. A novel specimen preparation technique is developed to assemble a homogeneous sample at a desired relative density. The pipeline is implemented as a cylindrical body with a continuously curved surface and a specific mass. Small displacement loading tests are performed, with a segment of the pipeline interacting with a 3D prismatic soil domain, replicating plane strain conditions. The influence of particle size, domain thickness, loading velocity and damping are investigated. The findings provide valuable recommendations for performing DEM simulations of this problem, balancing numerical accuracy and computational effort. Large displacement loading tests are performed to validate the DEM approach and to obtain detailed insights into the nature of the pipe-soil interaction. Monotonic vertical and lateral loading simulations are quantitatively compared with laboratory results. To replicate realistic loading conditions of the pipeline on the seabed, cyclic large displacement tests are also performed. Both the monotonic and the cyclic tests show a good level of agreement with experimental results obtained in previous research. Moreover, the numerical analyses provide insights into the evolution of particle motion and the failure mechanism within the soil.

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25

BERTAGLIA, Giulia. "1D augmented fluid-structure interaction systems with viscoelasticity: from water pipelines to blood vessels." Doctoral thesis, Università degli studi di Ferrara, 2020. http://hdl.handle.net/11392/2488143.

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Nowadays, mathematical models and numerical simulations are widely used in the whole fluid dynamics research field. They represent a powerful resource to better understand phenomena and processes and to significantly reduce the costs that would otherwise be necessary for carrying out laboratory experiments (sometimes even allowing to obtain useful data that could not be collected by measurements). Currently there are many important industries of hydraulic systems which, for the correct analysis of the behavior of the designed systems, require the preventive use of an accurate mathematical model, able to describe the trend of the properties of the fluid in the pipelines. On the other hand, the availability of robust and efficient mathematical instruments, together with the engineering know-how in the fluid mechanics sector, represents an invaluable tool for a consistent support even in hemodynamics studies, providing practical approaches for the quantification of variables involved in the cardiovascular fluid dynamics. The correct characterization of the interactions occurring between the fluid and the wall that circumscribes the motion of the fluid itself, is a fundamental aspect in all the contexts involving deformable ducts, which requires the utmost attention at every stage of both the development of the computational scheme and the interpretation of the results and at their application to cases of practical interest. In this PhD Thesis, innovative mathematical models able to predict the behavior of the fluid-structure interaction mechanism that underlies the dynamics of flows in different compliant ducts is presented. Starting from the purely civil engineering sector, with the study of plastic water pipelines, the final application of the proposed tool is linked to the medical research field, to reproduce the mechanics of blood flow in both arteries and veins. With this aim, various linear viscoelastic models, from the simplest to the more sophisticated, have been applied and extended to obtain augmented fluid-structure interaction systems in which the constitutive equation of the material is directly inserted into the system as partial differential equation. These systems are solved recurring to second-order Finite Volume Methods that take into account the recent evolution in the computational literature of hyperbolic balance laws systems. The models have been extensively validated through different types of test cases, highlighting the advantages of using the augmented formulation of the system of equations. Numerical results have been compared with quasi-exact solutions of idealized time-dependent tests for situations close to reality or with reference values obtained with numerical schemes generally adopted in the specific research field investigated. Furthermore, comparisons with experimental data have been considered both for the water pipelines scenario and the blood flow modeling, recurring to ad hoc in-vivo measurements for the latter. Accuracy and efficiency analyses have been performed in different contexts, as well as a sensitivity analysis with regards to the final part of the project, related to a more applicative study on arterial hypertension.
Oggigiorno, modelli matematici e simulazioni numeriche sono ampiamente utilizzati nell’intero campo della ricerca fluidodinamica. Essi rappresentano una potente risorsa per comprendere meglio i fenomeni e i processi e per ridurre significativamente i costi che sarebbero altrimenti necessari per la realizzazione di esperimenti di laboratorio (a volte anche per ottenere utili dati che non potrebbero essere raccolti mediante misurazioni). Attualmente esistono molte importanti industrie di sistemi idraulici che, per la corretta analisi del comportamento dei sistemi progettati, richiedono l’uso preventivo di un accurato modello matematico, in grado di descrivere l’andamento delle proprietà del fluido nelle tubazioni. D’altra parte, la disponibilità di strumenti matematici robusti ed efficienti, insieme al know-how ingegneristico nel settore della fluidodinamica, rappresenta uno strumento inestimabile per un supporto costante anche negli studi emodinamici, fornendo approcci pratici per la quantificazione delle variabili coinvolte nella fluidodinamica cardiovascolare. La corretta caratterizzazione delle interazioni tra il fluido e la parete che ne circoscrive il moto, è un aspetto fondamentale in tutti i contesti di condotte deformabili, che richiede la massima attenzione in ogni fase dello sviluppo dello schema di calcolo e della interpretazione dei risultati e nella loro applicazione a casi di interesse pratico. In questa Tesi di Dottorato vengono presentati innovativi modelli matematici in grado di prevedere il comportamento del meccanismo di interazione fluido-struttura che sta alla base della dinamica dei flussi in diverse condotte deformabili. Partendo dal settore dell’ingegneria puramente civile, con lo studio di condotte idrauliche in plastica, l’applicazione finale dello strumento proposto è legata al campo della ricerca medica, per riprodurre la meccanica del flusso sanguigno sia nelle arterie che nelle vene. A tal fine, sono stati applicati ed estesi diversi modelli viscoelastici lineari, dai più semplici ai più sofisticati, per ottenere sistemi aumentati di interazione fluido-struttura in cui l’equazione costitutiva del materiale è direttamente inserita nel sistema come equazione alle derivate parziali. Questi sistemi sono risolti ricorrendo a Metodi ai Volumi Finiti al secondo ordine che tengono conto della recente evoluzione della letteratura computazionale dei sistemi iperbolici di leggi di bilancio. I modelli sono stati ampiamente validati attraverso diversi tipi di casi test, evidenziando i vantaggi dell’utilizzo del sistema di equazioni in forma aumentata. I risultati numerici sono stati confrontati con soluzioni quasi esatte di problemi ideali dipendenti dal tempo per situazioni vicine alla realtà o con valori di riferimento ottenuti con schemi numerici adottati solitamente nello specifico campo di ricerca indagato. Inoltre, sono stati presi in considerazione confronti con dati sperimentali sia per lo scenario delle condotte idriche che per la modellazione del flusso sanguigno, ricorrendo a misurazioni in-vivo ad hoc per quest’ultimo. Sono state effettuate analisi di accuratezza ed efficienza in diversi contesti, nonché un’analisi di sensitività per quanto riguarda la parte finale del progetto, relativa ad uno studio più applicativo sull’ipertensione arteriosa.

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26

Weishaupt, Hrafn N. H. "Implementing a pipeline to search for transiting exoplanets : application to the K2 survey data." Thesis, Linnéuniversitetet, Institutionen för fysik och elektroteknik (IFE), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-79207.

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The detection of exoplanets has rapidly evolved to one of the most important frontiers of astronomical and astrophysical research. The recent decades have seen the development of various techniques for detecting exoplanets. Of these approaches the transit method has received particular interest and has lead to the largest number of discoveries to date. The Kepler K2 mission is an ongoing observational survey, which has generated light curves for thousands of stars, a large fraction of which have yet to be fully explored. To discover and characterize the transiting planets hosted by the respective stars, extensive transit screens are required. However, implementing a pipeline for transit analyses is not straight forward, considering the light curve properties of different survey, the rapid changes brought by technological advancements, and the apparent lack of a golden standard with respect to the applied methodology. The project has reviewed several aspects of exoplanet detection via the transit method. Particular focus was placed on the identification of a suitable workflow covering the relevant steps to move from raw light curve files to a final prediction and characterization of transiting planetary candidates. Adhering to the identified strategy, the major part of the project then dealt with the implementation of a pipeline that integrates and executes all the different steps in a streamlined fashion. Of note, primary focus was placed on the actual selection and implementation of methods into an operational pipeline, but due to the given time constraints extensive optimizations of each individual processing step was outside the scope of this project. Nevertheless, the pipeline was employed to predict transit candidates for K2 campaigns C7, C8, C10, C11, and C12. A comparsion of the most conservative predictions from campaigns C7 and C10 with previously reported exoplanet candidates demonstrated that the pipeline was highly capable of discovering reliable transit candidates. Since campaigns C11 and C12 have not yet been fully explored, the respective candidates predicted for those campaigns in the current project might thus harbour novel planetary transit candidates that would be suitable for follow-up confirmation runs. In summary, the current project has produced a pipeline for performing transiting exoplanet searches in K2 data, which integrates the steps from raw light curve processing to transit candidate selection and characterization. The pipeline has been demonstrated to predict credible transit candidates, but future work will have to focus on additional optimizations of individual method parameters and on the analysis of transit detection efficiencies.

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27

Nam, Le Thanh. "Stochastic Optimization Methods for Infrastructure Management with Incomplete Monitoring Data." 京都大学 (Kyoto University), 2009. http://hdl.handle.net/2433/85384.

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Kyoto University (京都大学)
0048
新制・課程博士
博士(工学)
甲第14919号
工博第3146号
新制||工||1472(附属図書館)
27357
UT51-2009-M833
京都大学大学院工学研究科都市社会工学専攻
(主査)教授小林潔司, 教授大津宏康, 教授河野広隆
学位規則第4条第1項該当

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28

Kim, Danny Jinsoo. "Effects of polymerization conditions and imidization methods on performance of crosslinkable polymer membrane for CO₂/CH₄ separation." Thesis, Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/48938.

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Natural gas feeds often contain contaminants such as CO₂, H₂S, H₂O, and small hydrocarbons. Carbon dioxide is a major contaminant reducing the heating value of the gas and causing pipeline corrosion, so CO₂ level should be lowered to below 2% to meet the United States pipeline specifications. Membrane separation technology can be advantageous over cryogenic distillation and amine adsorption in terms of cost and efficiency. The key hurdle to overcome in polymeric membrane separation technology is improvement in selectivity, productivity, and durability without introducing significant additional cost. The ultimate goal of this study is to analyze effects due to polymerization conditions and imidization methods on properties of 1,3-propanediol monoesterified crosslinkable polyimide (PDMC). Hillock, Omole, Ward, and Ma did work on PDMC synthesis; however, variability of polymer properties remains a challenge that must be overcome for industrial implementation of PDMC material. First, reaction temperature and reaction time of polymerization prior to imidization were considered as key conditions to affect molecular weight, crosslinkability and transport properties of polymer. Batches with controlled reaction temperature and time were prepared, and properties of each dense film were measured and optimized in terms of permeability, selectivity, and plasticization suppression. Second, imidization methods for PDMC were also studied. There are mainly two kinds of Imidization: chemical Imidization and thermal Imidization. Surprisingly, thermally imidized PDMC showed 70% higher permeability than chemically imidized samples with minimal acrifice in selectivity. At high reaction temperature during the thermal imidization, transamidation can occur. It is believed that the transamidation led to more randomized sequence distribution in the thermally imidized samples. We thus hypothesize that the higher permeability of the thermally imidized PDMC results from greater uniformity of the sequence distribution, as compared to the chemically imidized sample that does not experience high temperature during imidization. XRD, DSC, DMA, and permeation instruments checked and supported this hypothesis. FTIR, TGA, and NMR ruled out the possibility of an alternate hypothesis related to side reaction. Finally, effects of aggressive feed conditions on both chemically imidized PDMC and thermally imidized PDMC dense film were examined. The aggressive feed conditions include high CO₂ partial pressure, operating temperatures, and exposure to high feed pressure. Testing aggressive feed conditions for dense film should be pursued before pursuing hollow fiber applications, to decouple effects on the basic material from those on the more complex asymmetric morphology. This study enables understanding of the disparity between various previous researchers’ selectivity and permeability values. The work shows clearly that polymerization conditions and imidization methods must be specified and controlled to achieve consistently desirable polymer properties. In addition, for batch scale-up and development to a hollow fiber, this fundamental study should enable production of high molecular weight PDMC with good fiber spinnability and defect-free structure.

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29

Rinehart, Adam James. "Effects of localized geometric imperfections on the stress behavior of pressurized cylindrical shells." Texas A&M University, 2003. http://hdl.handle.net/1969/37.

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30

Sudibyo, Harry. "Une methode de test des circuits integres vlsi a structure pipeline serie et la generation automatique des vecteurs de test." Paris 6, 1987. http://www.theses.fr/1987PA066633.

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Le generateur automatique de vecteurs de test genevec qui est presente dans cette these, genere les vecteurs de test destines au test exhaustif du circuit integre vlsi dont la conception est faite a l'aide des cellules precaracterisees. Un fichier de description du test du circuit est forme d'un ensemble de donnees logiques d'interconnexions entre les blocs de base extraites a partir de la description "a plat" du circuit a tester et de donnees fonctionnelles sur les blocs de base qui constituent le circuit. La generation des vecteurs de test est effectuee d'apres ces informations. Cette etude s'applique aux circuits integres a structure pipeline serie. Ces circuits sont concus a l'aide d'une bibliotheque de cellules cmos, en utilisant les outils de la chaine de conception assistee par ordinateur emilie. La chaine de cao etablit la continuite des servitudes et des chemins de test. La methode que nous presentons dans ce travail est basee sur le test exhaustif du circuit en utilisant les chemins de test et en appliquant la methode lssd. Le but final est d'arriver a tester toute la partie combinatoire de chaque cellule standard, c'est a dire approcher taux de couverture 100%

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31

Liu, Ying. "Acoustic wave propagation in radially layered cylindrical waveguides and its application in fluid energy resource exploration and transportation." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2021. https://ro.ecu.edu.au/theses/2492.

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Radially layered cylindrical acoustic waveguide is one of the most common waveguide structures, as well as a physical model prototype for many practical applications, such as boreholes and buried pipelines. Study on the wave propagation in radial-layered cylindrical waveguides can provide a theoretical basis for acoustic methods in reservoir exploration and fluid resource transportation, including acoustic well logging, underground pipeline detection and location. This PhD study is conducted from two aspects: one is the monopole acoustic well logging in determining velocities of heterogenous formation based on the borehole acoustics; and the other is research on acoustic wave propagation within buried pipeline systems based on the thin shell theory. A theoretical model is established firstly to investigate the characteristics of wavefield within a borehole surrounded by heterogeneous formation, where an additional layer with different velocities from original homogenous formation is included to simulate the radial velocity distribution in practice. The arrival time difference and P-wave amplitude variation in time domain are observed and compared against the waveforms from homogeneous formation model. In order to study the contributing factors of wave amplitude variation, the current head wave theory is employed and its applicability in heterogeneous formation model is also investigated. It is found that the velocity difference of two formation layers, Poisson's ratio difference, the thickness of the additional layer and the source frequency contribute together to determine the magnitude of the disturbance to the original homogenous formation, which is the main applicable condition of the current head wave theory. Based on our established forward mode, the simulated waveforms in time domain are found to carry the valuable information of heterogeneous formation velocities. Therefore, a stepwise inversion method is proposed to image the radial profiles of formation P- and S-wave velocities. Instead of determining the formation velocity variation and its corresponding radial position simultaneously as traditional methods do, the inversion procedure is divided into two steps: 1) the velocity array is determined by semblance processing of contiguous receiver pairs of acoustic array data; and 2) the thickness of the layer (radial position) is obtained based on ray theory. The modelling-based inversion results and the application to field data validates its efficiency and accuracy in profiling both P- and S -wave velocities of formation. Buried pipeline systems share the same category of physical model prototype with borehole, i.e. a radial-layered cylindrical waveguide. However, the thickness of pipe wall is usually very smaller or much smaller than the radius. To address this special case, various thin shell theories have been developed. In this research, an established analytical model of buried fluid-filled pipes is deployed to study the axisymmetric wave motion. The behaviour of gas dominated wave is investigated and compared against water-dominated wave. It is observed that the gas-dominated wave in gas pipes cannot radiate into surrounded soil as effectively as water-dominated wave in water pipes because of the weak coupling between gas and pipe-soil. For buried gas pipes, the soil displacements due to radiation of shell-dominated wave are stronger than gas-dominated wave, which differs from buried water pipe. Hence, exciting shell dominated wave is beneficial to generating stronger vibration signals and obtaining the location information, which would optimise the current vibro-acoustic method in locating buried gas pipes.

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32

Ковтуненко, Олександр Миколайович. "Підбір оптимального матеріалу для елементу паливної системи літака, виходячи з розрахунку на міцність". Master's thesis, КПІ ім. Ігоря Сікорського, 2020. https://ela.kpi.ua/handle/123456789/39574.

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Пояснювальна записка до ДР: 100 с., 46 рис., 11 табл., 33 джерел. Як об'єкт дослідження було використано модельне представлення елементу тонкостінної конструкції. Мета даної роботи – підбір матеріалу для виготовлення елементу паливної системи літака. Побудована СЕ модель ділянки конструкції, проведено розрахунок розподілу напружень і деформацій. Методики дослідження - розбиття на СЕ сітку методом multizone, гідродинамічний і статичний аналізи. Розробка програмного коду в системі інженерного моделювання ANSYS, який реалізує гідродинамічний та статистичний аналізи тиску i напружень для тонкостінної конструкції із заданою геометрією. Отримані результати можуть бути використані при проектуванні реальних конструкцій.
Report on the DTh: 100 p., 46 fig., 11 tabl., 33 source. A model representation was used as the object of study element of thin-walled construction. The purpose of this work - the selection of material for the manufacture of fuel cell aircraft systems. The SE model of a site of a design is constructed, it is carried out calculation of stress and strain distribution. Research methods - splitting into CE grid by multizone method, hydrodynamic and static analyzes. Development of program code in the ANSYS engineering modeling system, which implements hydrodynamic and statistical analyzes of pressure and stress for thin-walled structure with a given geometry. The obtained results can be used in the design of real structures.

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Kalombo, Jean-Jacques Ntambwe. "Centrifugal pump derating non-Newtonian slurries: analysis of the viscosity to be used in the hydraulic institute method." Thesis, Cape Peninsula University of Technology, 2013. http://hdl.handle.net/20.500.11838/905.

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Thesis (MTech (Chemical Engineering))--Cape Peninsula University of Technology, 2013
Centrifugal pumps are the most commonly used pumps in slurry transport systems. The design of pumping systems dealing with liquids more viscous than water requires a reliable method of pump performance prediction for the pump selection. For Newtonian fluids, the Hydraulic Institute method is well established, but there is no generally accepted method for non-Newtonian fluids. Many authors have fallen back on using the Hydraulic Institute method for non-Newtonian fluids. This requires a constant viscosity while non-Newtonian fluid viscosity varies with the shear rate. The question arises: What viscosity should be used in this method for non-Newtonian fluids? Two approaches have been developed: the use of a Bingham plastic viscosity made by Walker and Goulas (1984) and the use of the apparent viscosity calculated using an “equivalent hydraulic pipe” diameter, designed by Pullum et al. (2007). Previous results obtained from these two approaches are not in agreement. Therefore, the aim of this study is to explore a suitable procedure to determine a representative non-Newtonian viscosity to be used in the Hydraulic Institute method to predict the pump performance. To achieve this goal, a set of data was experimentally obtained and the existing data were reused. Test work was conducted using the pump test rig in the Flow Process Research Centre at the Cape Peninsula University of Technology. A Warman 4/3 pump was tested, using four concentrations of kaolin suspension and three concentrations of CMC solution. Five pump speeds were chosen to run these tests: 1200, 1400, 1600, 1800, and 2000 rpm. An additional data set obtained by testing two submersible centrifugal pumps with eight concentrations of sludge, in Stockholm, Sweden, was also analysed. These sets of data were analysed firstly according to the Walker and Goulas (1984) approach and secondly according to the Pullum et al. (2007) approach. The use of the apparent viscosity led to the better pump head prediction. The results of this prediction were close to those obtained in the Pullum et al. (2007) work, and even better in some cases. On the other hand, the use of the Bingham plastic viscosity showed better pump efficiency prediction, although the Walker and Goulas (1984) efficiency prediction range was achieved only for one pump out of five. The apparent viscosity reflected the non-Newtonian behaviour but it could not represent alone the non-Newtonian viscosity because of the poor efficiency predictions and the sensitivity of the Pullum et al. (2007) approach to a change in viscosity. From the results of this work, it is advisable that the pump performance prediction be done using both apparent and Bingham plastic viscosity, the apparent viscosity for the head prediction and the Bingham plastic viscosity for the efficiency prediction.

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Fischer, Robert [Verfasser], Klaus [Akademischer Betreuer] Buchenrieder, and Gabi [Akademischer Betreuer] Dreo. "Methodik für die Verlustleistungsabschätzung von Prozessoren mit Pipeline-Strukturen / Robert Fischer. Klaus Buchenrieder. Gabi Dreo Rodosek. Universität der Bundeswehr München, Fakultät für Informatik." Neubiberg : Universitätsbibliothek der Universität der Bundeswehr, 2010. http://d-nb.info/1004913877/34.

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Ghimpeteanu, Gabriela. "Several approaches to improve noise removal in photographic images." Doctoral thesis, Universitat Pompeu Fabra, 2018. http://hdl.handle.net/10803/461012.

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Noise acquisition is an unavoidable component when capturing photographs, even in the case of current state of the art cameras. This problem is even accentuated when the lighting conditions are not ideal. Therefore, removing the noise present in the captured image is still an essential task in the camera image processing pipeline. In this thesis, we analyze several approaches to improve current image denoising meth- ods. First, we propose a general framework that can improve a denoising method, moti- vated by a simple principle: for any algorithm, the smaller the noise level, the higher the quality of the denoised image. Therefore, by carefully choosing an image decomposition of the noisy image into less noisy one(s) and applying the algorithm on the latter, the performance of any denoising method can increase. Second, we accentuate the importance of using a realistic noise model for testing any denoising methods, as in the usual AWG scenario the results can be extremely di erent. The noise model can be estimated on RAW images, as the camera processing pipeline alters the noise, and denoising becomes a challenge when applied on camera output. We show how a local method applied on RAW can outperform a non-local one applied on camera output, in the realistic noise scenario. Finally, in this thesis we propose a fast, local denoising method where the Euclidean curvature of the noisy image is approximated in a regularizing manner and a clean image is reconstructed from this smoothed curvature. User preference tests show that when denoising real photographs with actual noise our method produces results with the same visual quality as the more sophisticated, non-local algorithms, but at a fraction of their computational cost. These tests also highlight the limitations of objective image quality metrics like PSNR and SSIM, which correlate poorly with user preference.
L'adquisició de soroll és un component ineludible quan capturem una fotografi a, fins i tot en el cas de les càmeres d'última generació. Aquest problema s'accentua encara més quan les condicions d'illuminació no són ideals. Per tant, l'extracció del soroll que està present a la imatge capturada continua sent una tasca essencial dintre del processament d'imatges de la càmera. En aquesta tesi, analitzem diversos enfocaments per millorar els mètodes actuals d'extracció de soroll. En primer lloc, proposem un marc general que permet millorar un mètode d'extracció. Aquest marc està motivat per un principi senzill: per a qualsevol algoritme, com més petit sigui el nivell de soroll a l'imatge original, més alta serà la qualitat de la imatge de sortida. Per tant, escollint acuradament una descomposició de la imatge sorollosa en una altra amb menys soroll i aplicant l'algoritme en aquesta última, podem augmentar el rendiment de qualsevol mètode d'extracció de soroll. En segon lloc, remarquem la importància d'utilitzar un model de soroll realista per a evaluar qualsevol mètode d'extracció de soroll, ja que els resultats en imatges realistes poden divergir enormement en comparació amb l'escenari habitual de suposar AWG. Amb aquest , estimem un model de soroll en imatges RAW, ja que el processament de l'imatge dintre de la càmera altera el soroll, i l'extracció de soroll es converteix en un desa fiament al no seguir el model AWG. Mostrem que, quan suposem un model de soroll realista, un mètode local aplicat a RAW pot superar un de no-local aplicat a la sortida de la càmera. Finalment, en aquesta tesi proposem un mètode ràpid i local d'extracció de soroll on la curvatura euclidiana de la imatge sorollosa s'aproxima de manera regularitzadora i es reconstrueix una imatge neta d'aquesta curvatura suavitzada. Les proves de preferència dels usuaris mostren que el nostre mètode produeix resultats amb la mateixa qualitat visual que els algorismes més sofi sticats i no-locals, però amb una fracció del seu cost computacional. Aquestes proves també posen de relleu les limitacions de mètriques de qualitat d'imatge objectives com PSNR i SSIM, que es correlacionen malament amb la preferència dels usuaris.

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Inclan, Eric. "The Development of a Hybrid Optimization Algorithm for the Evaluation and Optimization of the Asynchronous Pulse Unit." FIU Digital Commons, 2014. http://digitalcommons.fiu.edu/etd/1582.

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The effectiveness of an optimization algorithm can be reduced to its ability to navigate an objective function’s topology. Hybrid optimization algorithms combine various optimization algorithms using a single meta-heuristic so that the hybrid algorithm is more robust, computationally efficient, and/or accurate than the individual algorithms it is made of. This thesis proposes a novel meta-heuristic that uses search vectors to select the constituent algorithm that is appropriate for a given objective function. The hybrid is shown to perform competitively against several existing hybrid and non-hybrid optimization algorithms over a set of three hundred test cases. This thesis also proposes a general framework for evaluating the effectiveness of hybrid optimization algorithms. Finally, this thesis presents an improved Method of Characteristics Code with novel boundary conditions, which better characterizes pipelines than previous codes. This code is coupled with the hybrid optimization algorithm in order to optimize the operation of real-world piston pumps.

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He, Yiyang. "A Physically Based Pipeline for Real-Time Simulation and Rendering of Realistic Fire and Smoke." Thesis, Stockholms universitet, Numerisk analys och datalogi (NADA), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-160401.

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With the rapidly growing computational power of modern computers, physically based rendering has found its way into real world applications. Real-time simulations and renderings of fire and smoke had become one major research interest in modern video game industry, and will continue being one important research direction in computer graphics. To visually recreate realistic dynamic fire and smoke is a complicated problem. Furthermore, to solve the problem requires knowledge from various areas, ranged from computer graphics and image processing to computational physics and chemistry. Even though most of the areas are well-studied separately, when combined, new challenges will emerge. This thesis focuses on three aspects of the problem, dynamic, real-time and realism, to propose a solution in form of a GPGPU pipeline, along with its implementation. Three main areas with application in the problem are discussed in detail: fluid simulation, volumetric radiance estimation and volumetric rendering. The weights are laid upon the first two areas. The results are evaluated around the three aspects, with graphical demonstrations and performance measurements. Uniform grids are used with Finite Difference (FD) discretization scheme to simplify the computation. FD schemes are easy to implement in parallel, especially with ComputeShader, which is well supported in Unity engine. The whole implementation can easily be integrated into any real-world applications in Unity or other game engines that support DirectX 11 or higher.

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Craveiro, Marina Vendl. "Upheaval buckling of pipelines triggered by the internal pressure resulting from the transportation of oil and gas: theoretical discussions and geometrically nonlinear analysis using Finite Element Method." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/3/3144/tde-06122017-082632/.

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The pipelines used to transport oil and gas from the wellheads to the distribution and refining sites can be subjected to high levels of pressure and temperature. Under such conditions, the pipelines tend to expand, but, if the expansion is inhibited, a significant compressive axial force can arise, leading to their buckling, which can occur in the horizontal or vertical plane. In this context, the objective of the present work is to analyze the upheaval buckling of pipelines, considering the internal pressure to which they are subjected during the transportation of oil and gas as its only triggering. Using the concept of effective axial force, it aims at discussing two different approaches for considering the internal pressure in buckling problems: distributed loads dependent on pipeline curvature and equivalent compressive axial forces with follower and non-follower characteristics. It also discusses the influence of using static or dynamic analysis for such approaches. Concerning the upheaval buckling itself, the work intends to analyze and compare the influence of the soil imperfection amplitudes to the influence of the friction between the pipeline and the ground in the critical loads and in the post-buckling configurations of the pipeline. Besides theoretical research, the objectives are achieved through the development of various numerical models, since geometrically-simple models, without the consideration of the interaction between the pipeline and the ground, until more complex models, with the use of contact models to detect the ground and its imperfections. The models are developed in Giraffe (Generic Interface Readily Accessible for Finite Elements) using geometrically-exact finite element models of beams, undergoing large displacements and finite rotations. Through the research, it is concluded that there is an equivalence between the application of the internal pressure as a distributed load dependent on pipeline curvature and the application of the internal pressure as a follower compressive axial force. Besides this, it is demonstrated that the type of the analysis (static or dynamic) depends on the nature of the physical system analyzed. With the aid of results presented in terms of internal pressure, classical results about the influence of the imperfection amplitudes and of the friction between the pipeline and the ground in buckling are confirmed. It is also showed that the imperfection amplitudes analyzed play a more important role in the post-buckling configurations of the pipeline than the friction.
Os dutos utilizados para transportar petróleo e gás natural das reservas até os locais de distribuição e refino podem estar submetidos a elevados níveis de pressão e temperatura. Sob tais condições, os dutos tendem a se expandir, porém, se a expansão é inibida, uma força axial de compressão significativa pode surgir nos dutos, ocasionando a flambagem lateral ou vertical dos mesmos. Dentro desse contexto, o objetivo do presente trabalho é analisar a flambagem vertical de dutos, considerando a pressão interna à qual eles estão submetidos durante o transporte de petróleo e gás natural como o único parâmetro desencadeador da flambagem. Usando o conceito de força axial efetiva, o trabalho objetiva discutir duas abordagens diferentes para considerar a pressão interna nos problemas de flambagem: carregamentos distribuídos dependentes da curvatura do duto e forças axiais de compressão equivalentes à pressão com caráter seguidor e não seguidor. O trabalho também discute a influência de usar a análise estática ou dinâmica para analisar essas abordagens de carregamento. Com relação à flambagem vertical propriamente dita, o trabalho pretende analisar e comparar a influência das amplitudes das imperfeições presentes no solo com a influência do atrito entre o duto e o solo nas cargas críticas e nas configuração pós-críticas do duto. Além de pesquisa teórica, os objetivos são atingidos através do desenvolvimento de vários modelos numéricos, desde modelos geometricamente simples, sem a consideração da interação entre o duto e o solo, até modelos mais complexos, com o uso de modelos de contato para detectar o solo e suas imperfeições. Os modelos são desenvolvidos no Giraffe (Generic Interface Readily Accessible for Finite Elements) usando elementos finitos geometricamente exatos de viga, sujeitos a grandes deslocamentos e rotações finitas. Através da pesquisa, conclui-se que existe uma equivalência entre a aplicação da pressão interna como um carregamento distribuído dependente da curvatura do duto e a aplicação da pressão interna como uma força axial de compressão seguidora. Além disso, demonstra-se que o tipo de análise (estática e dinâmica) depende da natureza do sistema físico analisado. Com a ajuda de resultados apresentados em termos de pressão interna, os resultados clássicos sobre a influência das amplitudes das imperfeições e do atrito entre o duto e o solo são confirmados. Também é mostrado que as amplitudes das imperfeições analisadas desempenham uma maior influência nas configurações pós-críticas do duto do que o atrito.

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Rodríguez, Miguel Jaime Sandoval. "Análise elastoplástica do colapso de elementos tubulares." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/3/3132/tde-19102005-200831/.

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Este trabalho objetiva o estudo específico, teórico e numérico, da determinação dos diferentes modos de colapso, elásticos e elastoplásticos, de uma estrutura tubular sujeita a esforços: pressão externa, flexão e flexo-pressurização. Entre os mais importantes elementos estruturais básicos, analisaremos inicialmente o modelo de um anel comprimido por uma carga radial. Isso significa determinar as pressões de instabilidade, elástica e elastoplástica, e de colapso, com os correspondentes modos, para anéis com diferentes relações diâmetro-espessura, D/t , submetidos a uma série gradual de pressões externas. A Estabilidade estrutural é computada utilizando uma formulação variacional, com discretização por elementos finitos. O modelo material pressupõe comportamento elastoplástico, com pequenas deformações. A análise não linear envolve a aplicação de pressurização externa aos anéis, de forma incremental, para a obtenção da resposta, tomando em conta a falta de circularidade inicial dos mesmos. Casos específicos envolvendo anéis de paredes finas e grossas serão considerados. Será analisado depois o estudo da resposta e da estabilidade de tubos de metal de parede fina e relativamente grossa sob flexão e flexo-pressurização através do método dos elementos finitos. Durante as últimas décadas este problema tem muito sido estudado através de métodos analíticos e experimentais. A maioria das soluções, entretanto, referem-se ao comportamento destas estruturas sob condições elásticas. No entanto, uma experiência de um elemento tubular é um problema inerentemente não linear com flambagem ou colapso do cilindro tomando lugar. Ás vezes com localização. Confrontaremos no final principalmente os resultados numéricos com aqueles da literatura, Kyriakides et al (1987), (1991) e (1992).
This work looks first at the determination of instability pressures as well as elastoplastic collapse, with the corresponding modes of rings with different diameter/thickness ratios under incremental external pressure loading and . Structural stability is computed by a variational formulation with discretization by finite elements. Material modeling considers elastoplastic behaviour with small deformations. Non Linear analysis produces the response curves considering lack of initial out-of-roundness. .After the response and stability of long and relatively thick wall metal tubes under bending and combined bending and external pressure were studied through experimental and analytical methods during the last decades. Most of the solutions, however, refered to the behavior under elastic conditions. In these cases we used the Finite Element Method with several discretizations. Nonetheless these experiments of a tube element is an inherently nonlinear problem with cylinder buckling or collapse taking place. Sometimes with localization. At the end numerical results are mainly compared to experimental measurements of Kyriakides et al (1987), (1991) e (1992).

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Toliver, Yetta. "Succession Planning for Next Generation Business Leaders." ScholarWorks, 2017. https://scholarworks.waldenu.edu/dissertations/3730.

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The ability to backfill leadership positions has become a key focus of business leaders since 2005 when the baby boom workforce started to age. An aging workforce threatens the capability of business leaders to develop leadership pipelines to ensure business success. Grounded by the social exchange theory, the purpose of this qualitative single case study was to explore successful strategies that technology services managers used to align core business objectives to improve succession planning at a technology services organization located in Dallas, Texas. Data collection and triangulation included semi structured telephone interviews with 12 technology services managers, company documents, and archival information. Data analysis included the examination of rich text data, coding, and classification of themes using Yin's 5-step approach. Four themes emerged, revealing that these managers (a) created and sustained a leadership talent pipeline for high potential employees for future leadership roles; (b) sourced internal candidates with core leadership competencies; (c) remediated leadership skills gaps through developed relationships and documented processes; and (d) re-engineered the replacement planning process for the internal leadership talent pipeline. Implications for positive social change include the potential for technology services managers to implement effective succession planning strategies that could increase employee morale, enhance profitability and growth, and promote healthy community partnerships.

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Ryd, Jonatan, and Jeffrey Persson. "Development of a pipeline to allow continuous development of software onto hardware : Implementation on a Raspberry Pi to simulate a physical pedal using the Hardware In the Loop method." Thesis, KTH, Hälsoinformatik och logistik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-296952.

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Saab want to examine Hardware In the Loop method as a concept, and how an infrastructure of Hardware In the Loop would look like. Hardware In the Loop is based upon continuously testing hardware, which is simulated. The software Saab wants to use for the Hardware In the Loop method is Jenkins, which is a Continuous Integration, and Continuous Delivery tool. To simulate the hardware, they want to examine the use of an Application Programming Interface between a Raspberry Pi, and the programming language Robot Framework. The reason Saab wants this examined, is because they believe that this method can improve the rate of testing, the quality of the tests, and thereby the quality of their products.The theory behind Hardware In the Loop, Continuous Integration, and Continuous Delivery will be explained in this thesis. The Hardware In the Loop method was implemented upon the Continuous Integration and Continuous Delivery tool Jenkins. An Application Programming Interface between the General Purpose Input/Output pins on a Raspberry Pi and Robot Framework, was developed. With these implementations done, the Hardware In the Loop method was successfully integrated, where a Raspberry Pi was used to simulate the hardware.
Saab vill undersöka metoden Hardware In the Loop som ett koncept, dessutom hur en infrastruktur av Hardware In the Loop skulle se ut. Hardware In the Loop baseras på att kontinuerligt testa hårdvara som är simulerad. Mjukvaran Saab vill använda sig av för Hardware In the Loop metoden är Jenkins, vilket är ett Continuous Integration och Continuous Delivery verktyg. För attsimulera hårdvaran vill Saab undersöka användningen av ett Application Programming Interface mellan en Raspberry Pi och programmeringsspråket Robot Framework. Anledning till att Saab vill undersöka allt det här, är för att de tror att det kan förbättra frekvensen av testning och kvaliteten av testning, vilket skulle leda till en förbättring av deras produkter. Teorin bakom Hardware In the Loop, Continuous Integration och Continuous Delivery kommer att förklaras i den här rapporten. Hardware In the Loop metoden blev implementerad med Continuous Integration och Continuous Delivery verktyget Jenkins. Ett Application Programming Interface mellan General Purpose Input/output pinnarna på en Raspberry Pi och Robot Framework blev utvecklat. Med de här implementationerna utförda, så blev Hardware Inthe Loop metoden slutligen integrerat, där Raspberry Pis användes för att simulera hårdvaran.

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Гусарова, И. Г., та В. С. Рязанов. "Моделирование нестационарных режимов течения по участку негоризонтального трубопровода". Thesis, ХНЕУ, 2016. http://openarchive.nure.ua/handle/document/2288.

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В работе рассмотрена математическая модель и численный метод, позволяющие проводить моделирование нестационарных процессов течения газа в трубопроводе с учетом рельефа трассы. На их основе можно проводить управление в нештатных ситуациях и аварийных ситуациях, происходящих в газотранспортной системе, и которые позволяют вести расчет параметров газового потока с необходимой точностью и необходимым быстродействием.

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Costa, Bernardo de Pinho Martins da. "Desenvolvimento e implementação de algoritmo para análise de dutos fabricados ou reparados com material compósito carregados com pressão interna utilizando o método dos elementos finitos." Universidade do Estado do Rio de Janeiro, 2015. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=8260.

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Анотація:

A integridade de dutos ganha importância à medida em que o desenvolvimento da indústria expande a malha para transportar líquidos e gases num contexto de aumento das exigências ambientais. Um importante aliado para manutenção da integridade de dutos são reparos de materiais compósitos. Estes materiais apresentam baixa densidade, capacidade de direcionar resistência de acordo com as direções das solicitações, execução de reparo a frio sem necessidade de interromper produção ou grande maquinário. Este trabalho tem como objetivo desenvolver e implementar um algoritmo de elementos finitos que permita avaliar os esforços e a resistência das paredes de um tubos fabricados ou reparados com laminados de material compósito carregados com pressão interna. Entre as vantagens de desenvolver um programa tem-se: agilidade de avaliação, menor custo com licença, menores exigências computacionais, possibilidade de desenvolver o programa e o melhor entendimento da modelagem dos fenômenos. Utiliza-se como entrada do programa o diâmetro do duto, pressão interna e parâmetros do laminado. A modelagem em elementos finitos é realizada a partir da teoria clássica de laminados. Aplicando o carregamento resultante da pressão interna, determina-se os deslocamentos e são calculadas as tensões e aplicado o critério de falha de Tsai-Hill em cada camada. Estudos experimentais e numéricos encontrados na literatura foram simulados com o programa gerado e os resultados para propriedades do laminado, tensões nos dutos e pressão de ruptura apresentam concordância com os resultados da literatura.O programa ainda tem sua estrutura modificada para encontrar a pressão de falha a partir dos dados do laminado. O programa implementado permite uma avaliação rápida de resistência do reparo e possibilita avaliar rapidamente a resposta a mudanças nos parâmetros de projeto do laminado.
Nowadays the integrity of pipelines gets even more important as a result of the industry growth and strong enviromental requirements. An important ally in the maintenance of the integrity is the repair with composite materials. These materials have low specific gravity, repair can be done at low temperatures and they can orientate the main resistence according to the load. The goal of this work is to develop and inplement an algorithm that allows the assessment of loads and strength in the pipes loaded with internal pressure manufactured or repaired with composite laminates using the finite element method. Among the advantages of the own software development there are agility for the assessment , lower cost with software licence, lower computational demands, possibility of developing the software and a better understanding of the modeling of the fenomena. The inputs of the software are the diameter of the pipe, internal pressure and parameters of the composite laminate. The finite element analysis is constructed according to the classical laminate theory. After the loads resulting of the internal pressure are applied, the displacements are calculated and then the stresses and Tsai-Hill failure criteria are determined for each layer. Experimental and numerical studies were simulated with the developed software and the results for the laminae properties, pipe stress and the failure pressure are in agreement with the results found in the review. The software is modified in order to end the failure pressure to show the versatility of the algorithm. We conclude that the algorithm allows a fast assessment of the strenght of pipeline repair and the changes in the answer of the pipe when the repair parameters are changed.

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Silva, Felipe Nascimento da. "Análise de critérios de dimensionamento de carga em dutos de concreto instalados em vala na situação de recobrimento mínimo." Universidade do Estado do Rio de Janeiro, 2014. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=8675.

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Анотація:

Perante diversas situações da engenharia são utilizadas formulações empíricas de dimensionamento baseadas em dados de campo e experiência profissional que definem muito o caráter subjetivo da metodologia padrão de projeto. O presente trabalho de pesquisa aborda os diversos métodos de obtenção dos esforços gerados em dutos enterrados submetidos a cargas dinâmicas e estáticas e sua posterior reavaliação através de modelagem numérica com o programa Plaxis 3D. Os métodos analíticos não convencionais foram comparados com o método padrão de cálculo sendo que o mesmo demonstrou ter uma boa precisão mesmo sem considerar outros fatores importantes como a parcela de resistência devida à coesão do solo e sua deformabilidade. A modelagem numérica demonstrou o conservadorismo do método de Marston e o subdmensionamento do espraiamento em prisma devido aos efeitos locais ocasionados pela adoção do recobrimento mínimo e sobrecarga dinâmica elevada. Também se observou, através da modelagem 3D, que a utilização dos dois métodos clássicos favorecem a obtenção de resultados dentro da razoabilidade.Verificou-se também, como resultado desta pesquisa, que a proposta de um método clássico modificado permite uma melhor aproximação da carga que atinge o duto.
In various engineering situations, empirical formulations of design, based on field data and professional experience which highly define the subjective nature of the standard design methodology, are used. This paper discusses the various methods of obtaining the stresses generated in buried pipelines, which are subjected to static and dynamic loads, and their subsequent re-evaluation by numerical modeling with Plaxis 3D program. The non-conventional analytical methods were compared with the standard method of calculation and it has demonstrated good accuracy even without considering other factors such as soil cohesion and deformability. The numerical modeling demonstrated the conservatism of the Marston method and subsiding of the prism spread due to local effects caused by the adoption of minimum cover and high dynamic overload and due to how the use of two classical methods favor reasonable results. A classic modified method that would allow a closer approximation of the load was also proposed.

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Bakkali, Mohammed Marouane El. "Modélisation des contrôles non-destructifs par ondes ultrasonores guidées. Application aux contrôles de canalisations." Thesis, Valenciennes, 2015. http://www.theses.fr/2015VALE0004/document.

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La thèse s’inscrit dans les travaux du CEA LIST pour développer dans la plate-forme CIVA un module simulant le contrôle non-destructif (CND) par ondes ultrasonores guidées ; elle est dédiée au développement et à la validation de modèles simulant l’inspection de canalisations et se focalise sur le cas de canalisations comportant un ou plusieurs coudes. Pour prédire l’effet de la courbure sur les ondes guidées, une extension en coordonnées curvilignes de la méthode des éléments finis semi-analytiques est réalisée pour calculer les modes se propageant dans un coude, par résolution d’un système d’équations aux valeurs propres restreint à la section du guide. Ce développement a aidé à comprendre les effets de distorsion des champs ultrasonores et de décalage des fréquences de coupures dus à la courbure. La diffraction des ondes à la jonction entre un tube droit et un coude est ensuite calculée par raccordement modal donnant la matrice de diffraction de la jonction ; les éléments de la matrice s’obtiennent par évaluation numérique d’intégrales à la surface de la jonction. Les matrices de diffractions locales sont enfin combinées à des matrices de propagation pour rendre compte de la présence de plusieurs diffracteurs sur la canalisation, sous forme d’une matrice globale de diffraction. Le coût minimal de son calcul permet d’étudier l’influence des paramètres de contrôle et de les optimiser. Les modèles sont validés en comparant leurs prédictions avec des résultats numériques et expérimentaux de la littérature et des mesures faites au CETIM sur maquettes industrielles. Intégrés à la plate-forme CIVA, ils étendent les possibilités du module de simulation du CND par ondes guidées
The thesis is in the framework of developments made at CEA LIST of a module of the CIVA platform to simulate nondestructive testing (NDT) by ultrasonic guided waves; it is dedicated to the development and the validation of models simulating the examination of pipelines and is focussed on the case of pipeline comprising one or several elbows. To predict effects due to the curvature on guided waves, an extension in curvilinear coordinates of the semi-analytic finite element method is worked out to compute modes propagating in an elbow, by solving an eigen system restricted to the guide section. This development allows us to better understand effects due to the curvature such as displacement field distortions or cut-off frequencies splits. The scattering of waves at the junction between a straight tube and an elbow is then computed by means of the mode-matching method, leading to the modal scattering matrix of the junction; matrix elements are obtained by numerical evaluation of integrals over the junction surface. Local scattering matrices are finally combined to propagation matrices to account for the presence of several scatterers in the pipeline, to form a global scattering matrix. Its minimal computation cost allows us to study the influence of the parameters of the testing configuration and to optimize them. Models are validated by comparing their predictions to numerical and experimental results of the literature and to measurements made at CETIM on industrial mock-ups. Integrated in the platform CIVA, the developed models extend the capabilities of the guided wave NDT module

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Штаєр, Л. О. "Акустичний метод та система контролю витоків з трубопроводів". Thesis, Івано-Франківський національний технічний університет нафти і газу, 2010. http://elar.nung.edu.ua/handle/123456789/4410.

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Робота присвячена вирішенню проблеми пошуку та визначення місць витоків з трубопроводів для забезпечення надійності експлуатації трубопроводів та попередження аварійних ситуацій за рахунок оперативного виявлення місць утворення витоків. Показано, що максимальна ефективність у контролі появи витоків на трубопроводах досягається шляхом застосування дистанційних методів контролю стану трубопроводів. Для вирішення поставленого завдання було обрано акустичний метод контролю технічного стану трубопроводу. Розроблено математичну модель процесу розповсюдження акустичних коливань у середовищі транспортування трубопроводу, яка враховує вплив появи витоків на характер поширення коливань. Розроблено метод автоматизованого контролю технічного стану трубопроводу та виявлення місць витоків з використанням завадостійких сигналів. На основі проведених теоретико-експериментальних досліджень здійснена розробка системи виявлення місць витоків з трубопроводів. Проведена розробка функціональної схеми системи контролю, а також програмного забезпечення для реалізації запропонованого методу контролю трубопроводів.
Работа посвящена решению проблемы поиска и определения мест утечек из трубопроводов для обеспечения надежности эксплуатации трубопроводов и предупреждения аварийных ситуаций за счет оперативного выявления мест образования утечек. Важность поставленной задачи определяется тем, что размер потерь транспортированного сырья вследствие наличия утечек на трубопроводах определяется временем их обнаружения и точностью возможной координаты отбора. Оперативное выявление утечек на трубопроводах ведет к сокращению экономических и экологических ущербов. Проведенный анализ современных методов и средств контроля утечек на трубопроводах показал ограничения в их применении. Показано, что максимальная эффективность в контроле появления утечек на трубопроводах достигается путем применения дистанционных методов контроля состояния трубопроводов. Для решения поставленного задания был избран акустический метод контроля технического состояния трубопровода, который предусматривает создание тестовых воздействий и регистрацию их в пределах транспортируемой трубопроводом среды. Разработана математическая модель процесса распространения акустических колебаний в среде транспортирования трубопровода, которая учитывает влияние появления утечек на характер распространения колебаний. Обоснованность использования предложенной модели подтверждено проведенной процедурой параметрической идентификации для участка трубопровода с наличием и отсутствием утечек. Разработано методическое, техническое и программное обеспечение метода контроля технического состояния трубопровода для проведения комплекса экспериментальных исследований по обнаружению и определению мест утечек с целю установления закономерностей изменения параметров колебательных процессов при отражении их от неоднородностей (резких поворотов, ответвлений, отверстий в стенке трубопровода, мест установки кранов и т.д.). Анализ результатов экспериментальных исследований процесса распространения тестовых сигналов в транспортируемой среде трубопровода позволил определить параметры тестовых сигналов, которые обладают наименьшей степенью затухания для определенных условий распространения. Изменение характера распространения тестового сигнала при наличии и отсутствии утечек стало основой для разработки метода автоматизированного контроля технического состояния трубопровода и выявления мест утечек с использованием в качестве тестовых помехоустойчивые сигналы, в частности коды Баркера. Использование такого рода сигналов в качестве тестовых с применением аппарату корреляционной обработки регистрируемых сигналов позволило повысить отношение сигнал/шум и увеличить расстояние обнаружения утечек. Было принято решение в качестве диагностического признака наличия утечки использовать разностную характеристику, полученную при распространении тестового сигнала в среде транспортирования трубопровода в базовом и текущем состоянии. При определении базовой характеристики принимается гипотеза про отсутствие утечек. С учетом проведенных теоретических и экспериментальных исследований осуществлена разработка системы выявления мест утечек из трубопроводов. Погрешность измерения расстояния к утечке с доверительной вероятностью 0,98 составляет ±0,8 м. Разработано программное обеспечение для реализации предложенного метода контроля. Проведены исследования разработанных метода и системы контроля утечек в лабораторных и полевых условиях, подтвердившие работоспособность предложенного метода и технической реализации.
The work is devoted to decision of pipeline leak search and localization problem for pipeline operation reliability control and emergency situation prevention due to the real-time leak localization. It is shown that the maximal efficiency in pipeline leak appearance control is reached with the use of remote pipeline state control. For the task decision acoustic control method of pipeline technical state was selected. The mathematical model of acoustic wave’s distribution process in pipeline transporting fluid is developed, which takes into account influence of leak appearance on wave distribution pattern. The pipeline technical state automatic control and leak localization method is developed with the use of robust signals. The pipeline leak localization system is developed on the basis of the conducted theoretical and experimental researches. The system control functional scheme is developed. And also software for offered pipeline control method realization is given.

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Терефенко, Р. М. "Підвищення ефективності використання механічних очисних пристроїв в газопроводах". Thesis, Івано-Франківський національний технічний університет нафти і газу, 2009. http://elar.nung.edu.ua/handle/123456789/4341.

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Дисертаційна робота присвячена підвищенню ефективності використання механічних пристроїв у газопроводах і забезпечення оперативного ліквідування аварій у випадку їх застрягання. Запропоновано імпульсно-хвильовий метод пошуку очисного пристрою, що застряг у газопроводі, створено математичну модель газодинамічних процесів і проведено аналітичні та експериментальні дослідження, на основі яких встановлено раціональні параметри процесу та дано оцінку точності методу.
Дисертационная работа посвящена повышению эффективности использования механических очистных устройств в газопроводах и обеспечению оперативной ликвидации аварий в случае их застревания. Статистический анализ застревания очистных устройств в газопроводах, выполненный на основании информации ДК «Укртансгаз» на протяжении 1976-2002 гг., позволил оценить вероятность застревания с разбивкой по типам очисних устройств, причинам застревания и диаметрам трубопроводов. Выявлено основне причины застревания очистных устройств при очистке трубопровода перед вводом в эксплуатацию. Установлены также среднестатистические затраты времени на ликвидацию аварий в случае застревания очисного устройства в разрезе диаметров газопроводов и типа очистных устройств.. Создана математическая модель газодинамического нестационарного процесса в газопроводе, вызванного остановкой очисного устройства в процессе проведения очистки. На основе реализации предложенной математической модели и анализа результатов многовариантных расчетов сделаны выводы о взаимозависимости между параметрами процесса в случае полной и неполной закупорки трубопровода. Установлено, что в случае неполной закупорки газопровода очистным устройством газодинамические методы контроля за движением и остановкой устройства не могут удовлетворить требованиям определения места его остановки вследствие неопределенности исходной информации. Предложен импульсно-волновой метод поиска места остановки очисного устройства в газопроводе, заключающийся в воздействии на газовий стационарный поток кратковременным импульсом повышенного давления, что позволит создать волновой колебательный процесс. По времени распространения прямой и отраженной волны и скорости распространения звука в газовой бреде определяется координата места закупорки трубопровода. С целью выбора рациональных параметров реализации метода проведены его аналитические исследования с применением математической модели, созданной на основе уравнений движения газа, в котором учтены инерционные потери и потери на преодоление сил трения, и неразрывности, в которой импульсное воздействие на стационарный газовый поток иммитировалось при помощи функции источника Диракка. Реализация предложенной математической модели для многовариантной исходной информации позволила оценить влияние различных параметров процесса на окончательный результат и выбрать их рациональные значения. Для оценки точности предложенного метода проводились экспериментальные исследования на физических моделях. Опыты проводились на различных значениях геометрических размеров модели и разных параметрах режима. Результаты моделирования обрабатывались с учетом теории подобия и размерностей на основе методики рационального планирования эксперимента. В итоге получено в критериальной форме уранение для определения погрешности предложенного метода. В результате проведение исследований создана технология и разработано оборудование для практической реализации метода и проведены опытнопромысловые испытания на газопроводах-отводах УМГ Прикарпаттрансгаз, которые показали высокую эффективность метода.
Dissertation is devoted to the increase of efficiency of the use of mechanical pigs in gas pipelines and providing the operative accident elimination, in the case of its sticking. The impact-wave method of search of sticked in a gas pipeline cleansing pigs is offered, the mathematical model of gas dynamic processes is created, the analytical and experimental researches are conducted, on the basis of these researches the rational parameters of process are set and the estimation of the method accuracy is given.

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Драгілєв, А. В. "Визначення залишкових напружень і оцінка їх впливу на довговічність кільцевих зварних з'єднань трубопроводів". Thesis, Івано-Франківський національний технічний університет нафти і газу, 2006. http://elar.nung.edu.ua/handle/123456789/4100.

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Анотація:

Дисертацію присвячено розвиткові розрахунково-експериментального методу визначення залишкових напружень в зонах багатошарових кільцевих швів трубопроводів і оцінці їх впливу на довговічність зварних з’єднань за наявності гострокінцевих дефектів при дії повторно-змінних навантажень. В рамках теорії оболонок побудовано математичну модель для визначення компонентів напруженого стану з урахуванням двовимірного розподілу залишкових несумісних деформацій локалізованих біля шва, та структурно-фазових змін в зоні термічного впливу. Вона грунтується на розв’язанні обернених задач теорії оболонок з власними напруженнями і використанні експериментальної інформації, отриманої неруйнівними методами. Використавши математичну модель закриття тріщини і концепцію ефективного розмаху коефіцієнта інтенсивності напружень, отримано розрахункову модель для врахування впливу залишкових напружень на втомне руйнування при циклічному навантаженні. Оцінено вплив залишкових напружень на довговічність трубопроводу з осьовим поверхневим дефектом в зоні зварного з’єднання під дією експлуатаційного навантаження.
Диссертация посвящена развитию расчетно-экспериментального метода определения остаточных напряжений в зонах многослойных кольцевых швов трубопроводов и оценке их влияния на долговечность сварных соединений при наличии остроконечных дефектов под действием переменных нагрузок. В рамках теории оболочек разработана математическая модель для определения компонентов тензора технологических остаточных напряжений с учетом двумерного распределения несовместных остаточных деформаций, локализированных возле шва и структурно-фазовых изменений в зоне термического влияния. Модель базируется на решении обратных задач теории оболочек с остаточными деформациями и использовании экспериментальной информации об усредненных характеристиках напряженного состояния, которую можна получить физическими методами. Получены выражения для окружных и осевых напряжений в трубопроводе с учетом локальных остаточных деформаций в зоне сварного шва, распределение которых аппроксимировано тензорными полиномиальными функциями с определенным количеством произвольных параметров. На основании решения прямой задачи проанализировано влияние ширины зоны сварочных деформаций и их градиентов вдоль и по толщине трубы на напряженное состояние в зоне сварного соединения. Установлено, что увеличение перепада окружных деформаций по толщине трубы обусловливает незначительное увеличение окружных напряжений на ее внешней поверхности и приводит к существенному уменьшению растягивающих окружных и осевых напряжений на внутренней и сжимающих на внешней поверхностях трубы. С увеличением окружных остаточных деформаций и их градиентов вдоль трубы максимальные растягивающие окружные напряжения и осевые напряжения - на ее внутренней поверхности возрастают почти пропорционально приращениям максимальных деформаций. Уменьшение ширины зоны осевых деформаций, при фиксированной ширине зоны окружных, несущественно влияет на величину и распределение окружных остаточных напряжений на поверхностях трубы и может обусловить значительное возростание осевых напряжений на внутренней поверхности трубы в зоне сварного шва. Для определения неизвестных параметров построен функционал, выражающий сумму квадратов отклонений усредненных величин разности окружных и осевых напряжений, которіе определяют электромагнитным или ультразвуковым методами, от аналогичных величин, полученных расчетным способом. Электромагнитным методом, с использованием измерительного прибора ’’MESTR-411” с четырехполюсным электромагнитным преобразователем трансформаторного типа, определены значения усредненной разности главных напряжений на поверхности трубы в зоне кольцевого сварного шва магистрального газопровода (0 1420 х 22,5 мм, материал Х70). Приведены соотношения для аналогичных усредненных характеристик, полученных расчетным способом и построен соответствующий функционал, с помощью которого найдены неизвестные параметры, а затем рассчитаны кольцевые и осевые остаточные напряжения на внешней и внутренней поверхностях трубы в зоне сварного шва. С использованием математической модели закрытия трещины и концепции эффективного размаха коэффициента интенсивности напряжений разработана расчетная модель для учета влияния остаточных напряжений на скорость распространения осевой поверхностной трещины в трубе в зоне сварного соединения при циклическом нагружении. Определены характеристики циклической трещиностойкости сварного соединения. Оценено влияние остоточных напряжений на долговечность трубопровода с осевой полуэллиптической трещиной в зоне сварного шва под воздействием пульсирующего внутреннего давления.
The dissertation develops calculation-experimental method of determining residual stresses in zone of multi-layer circumferential welding beads of pipelines and estimation of their influences on the durability of welding joints with cracks under cyclic loads. Within the shell theory, a mathematic model for determining components of stress state with taking into account the two-dimensional plastic deformation distribution localized near the welding bead and structural-phases changes in the thermal influence zone is created. The model is based on solving inverse problems of shell theory with own stresses on using experimental information obtained by non-distructive method. Having used crack closure mathematical model and the concept of effective amplitude of stress intensity factor, a calculational model for taking into account the influence of residual stresses on fatigue fracture under cyclic load is obtained. The influence of residual stresses on welding joint durability of a pipeline with an axial surface defect under workload is estimated.

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49

Malá, Kateřina. "Studium proudění nemísitelných kapalin." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-416440.

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Анотація:

This thesis explores the topic of flow of two immiscible liquids in horizontal pipeline. For this purpose, the experimental apparatus has been set up, that allows to observe the flow of mixture through the transparent pipe. Moderately viscous oil and water (viscosity ratio: 52,81, density ratio: 0.86, interfacial tension: 41,64 mN/m) have been chosen for the experiment. Both fluids were introduced into the pipe through a T-junction. At the end of the apparatus, a mixture of liquids flowed into the separation tank, where both phases were separated. The separated oil was then reused for further measurements. The oil and water flow rates could be individually changed by use control valves, that led to identification of different flow regimes. These varied from stratified flows to fully dispersed ones as the mixture speed increased. All observed flow regimes were plotted in the flow map, that is a function of the inlet velocities of both fluids. For further analysis, a second type of flow map has been created that displays rates as a function of mixture velocity and phase volume fraction. Selected regime was also simulated using software ANSYS FLUENT. The VOF method was used to simulate multiphase flow. This thesis critically evaluates the results of the study and shows the direction for further research in the field of immiscible liquids flow.

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50

Цих, В. С. "Розроблення методу та засобу контролю дефектів ізоляції підземних трубопроводів". Thesis, Івано-Франківський національний технічний університет нафти і газу, 2014. http://elar.nung.edu.ua/handle/123456789/4703.

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Анотація:

Дисертація присвячена питанню контролю ізоляційного покриття підземних трубопроводів на території технологічних об’єктів нафтогазового комплексу. Проведено аналіз основних методів і засобів контролю технічного стану ізоляційного покриття підземних трубопроводів. Поділено всі існуючі дефекти ізоляції на два види: наскрізні пошкодження та відшарування. Проаналізовано особливості дефекту ізоляційного покриття типу відшарування ізоляції та його вплив на зміну електричних характеристик підземного ізольованого трубопроводу. Доведено доцільність застосування електромагнітного фазового методу контролю для виявлення таких дефектів. Одержано аналітичну модель залежностей питомого зсуву фази для ділянки підземного трубопроводу з відшаруванням ізоляції. Спроектовано та змонтовано експериментальну модель ділянки підземного трубопроводу з різними дефектами ізоляційного покриття. Розроблено методику проведення експериментальних досліджень та експериментальний взірець інформаційно-вимірювальної системи. Проведено вимірювання основних інформативних параметрів на моделі підземного трубопроводу на навчально-науковому полігоні для технічної діагностики підземних комунікацій. Розроблено комплексний метод виявлення та ідентифікації дефектів ізоляційного покриття на основі аналізу двох інформативних параметрів (амплітуди та фази струму в стінках трубопроводу). Запропоновано методику виявлення дефектів ізоляційного покриття підземних трубопроводів, на основі якої розроблено проект нормативного документу (СОУ). Проведено апробацію методики та експериментального взірця інформаційно-вимірювальної системи для виявлення та ідентифікації дефектів ізоляційного покриття підземних трубопроводів.
Диссертация посвящена вопросу контроля изоляционного покрытия подземных трубопроводов на территории технологических объектов нефтегазового комплекса, а именно - трубопроводов, размещенных на территории автомобильных газонаполнительных, компрессорных, газораспределительных и нефтеперекачивающих станций. Проведен анализ основных методов и средств контроля технического состояния изоляционных покрытий подземных трубопроводов, а также проанализированы главные проблемы, которые могут возникать во время контроля таких трубопроводов на территории технологических объектов нефтегазового комплекса. Разделены все существующие дефекты изоляционных покрытий на два вида - сквозные повреждения и отслоения изоляции. Особое внимание уделено дефектам типа отслоения, поскольку существующие подходы и методики контроля технического состояния изоляции не дают возможность определять местоположение таких дефектов с поверхности земли в виду особенности их характеристик. Проведены теоретические исследования по изменению удельного сдвига фазы измеряемого сигнала при изменении емкостей и соответственно геометрических параметров отслоений изоляционного покрытия. Доказана целесообразность применения электромагнитного фазового метода контроля для выявления таких дефектов. Получена аналитическая модель зависимостей сдвига фазы для участка подземного трубопровода с отслоением изоляции с учетом параметров грунта, в котором размещен исследуемый трубопровод. Разработана схема и создана экспериментальная модель участка подземного трубопровода с различными дефектами изоляционного покрытия (сквозными повреждениями и отслоениями изоляции) на специальном учебно-научном полигоне для технического диагностирования подземных коммуникаций. Предложена методика - проведения экспериментальных исследований, для чего создан экспериментальный образец информационно-измерительной системы. Проведены измерения основных информативных параметров (сдвига фазы и амплитуды тока в стенках) на модели подземного трубопровода на учебно-научном полигоне. На основании проведенных измерений значений тока в стенках исследуемого трубопровода получено экспериментальное подтверждение эффекта вытекания тока со свойственными изменениями в месте сквозного повреждения изоляции. Оценена возможность идентификации сквозного повреждения на основании оценки критических значений точек распределения хи-квадрат. Разработан комплексный метод обнаружения и идентификации дефектов изоляционного покрытия на основе анализа двух информативных параметров (удельного изменения значений тока в стенках трубопровода и удельного сдвига фазы измеряемого сигнала). Разработана методика определения местоположения повреждений изоляционных покрытий подземных трубопроводов на территории технологических объектов нефтегазового комплекса. Проведены полевые исследования, а также промышленная апробация методики и экспериментального образца информационно-измерительной системы для обнаружения и идентификации дефектов изоляционного покрытия подземных трубопроводов, которые подтвердили их работоспособность в условиях действующих объектов нефтегазового комплекса.
Thesis is devoted to the issue of insulated coating monitoring of buried pipeline situated at the oil and gas complex production facilities. The analysis of basic methods and equipment for technical condition of buried pipelines insulated coating monitoring is realized. All existing coating defects are divided into two types: holes and coating disbondings. Coating disbonding damage singularity and its influence on buried insolated pipeline electrical parameters variances is analyzed. The feasibility of the phase electromagnetic testing method for such damages detection is proved. An analytical model of specific phase displacement for buried pipeline section with coating disbonding is deduced. An experimental model of buried pipeline section with different coating damages is planed and constructed. The technique of experimental investigations and operative embodiment of information and measuring system are developed. The measuring of the fundamental information-bearing parameters at the model of buried pipeline situated at the special educational and scientific training range for buried utilities technical diagnostic is made. A complex method for coating damages detection and identification on the basis of two information-bearing parameters analyzes (the range and the phase of pipeline current) is developed. The technique of buried pipelines coating damages detection is suggested whereby a standardized document project has been developed. An approvement of technique and information and measuring system for buried pipeline insulated coating damages detection and identification is made.

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Дисертації з теми "Pipelined methods"

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