Добірка наукової літератури з теми "Water hammer Data processing"

Drill strings and oil production lines are examples of fluid systems for which time-dependent (dynamic) as well as steady state (static) analysis is increasingly needed. These systems are difficult and expensive to instrument and test experimentally. Developments of fluidic non-moving-part controllers to produce water-hammer pulsations stimulated a need to simulate the fluid dynamics of such drill strings to aid the design work. The method of simulation chosen was transmission line modelling (TLM). It is essentially a time-delay method, borrowing its main concepts and the fundamentals of its computational solution scheme from early work by others in the field of electrical power lines. In its elementary form, a fluid network is treated as a set of pipes (or pipe segments) where waves travel with pure time delay. Connecting the pipes are junctions of various types at which the waves are scattered (transmitted, reflected and/or attenuated). The merits and limitations expected with this methodology in comparison with the method of characteristics (MOC) and other wave-analysis methods are discussed. The first adaptations of TLM were for small perturbation analysis. The presentation here takes such work further forward to model large-scale waves in pipe networks of almost arbitrarily complex topology. The basic theory behind the method is presented and the solution schemes are formulated mathematically with comments on the type of data structure and algorithms needed to undertake computationally such solutions. With the aid of modules described elsewhere, providing comprehensive steady state modelling capability, the software provides a powerful tool for implementing static and dynamic TLM simulations of networks. One of the novel aspects of considerable benefit is the ease of implementation of time-varying junctions capable of representing the overall action of control elements such as the fluidic controllers mentioned earlier. A large experimental laboratory facility with a simple circuit containing the essential hydrodynamics of drill strings was used to gather data on water-hammer pulsations. A controlled solenoid valve with a high-resistance bypass acted as an alternating high and low resistance in the main pipe loop. A simplified version of the circuit was simulated with TLM to compare and discuss the results. The TLM time-domain results took a few seconds of computer processing time and revealed the basic features of the circuit dynamics quantifying water-hammer to a fair and useful accuracy. Such results were encouraging and confirmed the power of this computational method as an aid in the design process.

Solar irradiance models contribute to mitigating the lack of measurement data at a ground station. Conventionally, the models relied on physical calculations or empirical correlations. Recently, machine learning as a sophisticated statistical method has gained popularity due to its accuracy and potential. While some studies compared machine learning models with other models, a study has not yet been performed that compares them side-by-side to assess their performance using the same datasets in different locations. Therefore, this study aims to evaluate the accuracy of three representative models for estimating solar irradiance using atmospheric variables measurement and cloud amount derived from satellite images as the input parameters. Based on its applicability and performance, this study selected the fast all-sky radiation model for solar applications (FARMS) derived from the radiative transfer approach, the Hammer model that simplified atmospheric correlation, and the long short-term memory (LSTM) model specialized in sequential datasets. Global horizontal irradiance (GHI) data were modeled for five distinct locations in South Korea and compared with hourly measurement data of two years to yield the error metrics. When identical input parameters were used, LSTM outperformed the FARMS and the Hammer model in terms of relative root mean square difference (rRMSD) and relative mean bias difference (rMBD). Training an LSTM model using the input parameters of FARMS, such as ozone, nitrogen, and precipitable water, yielded more accurate results than using the Hammer model. The result shows unbiased and accurate estimation with an rRMSD and rMBD of 23.72% and 0.14%, respectively. Conversely, the FARMS has a faster processing speed and does not require significant data to make a fair estimation.

Compressional (P) wave and shear (S) wave seismic reflection techniques were used to delineate the sand and gravel aquifer within a highly saline clay‐filled paleochannel in the Eastern Goldfields of Western Australia. The seismic refraction and gravity methods were also used to investigate the paleochannel. The unsaturated loose fine‐grained sand up to 10 m in depth at the surface is a major factor in degrading subsurface imaging. The seismic processing needed to be precise, with accurate static corrections and normal moveout corrections. Deconvolution enhanced the aquifer and other paleochannel reflectors. P‐wave reflection and refraction layer depths had good correlation and showed a total of six boundaries: (1) water table, (2) change in velocity (compaction) in the paleochannel sediments, (3) sand and gravel aquifer, (4) red‐brown saprolite and green saprolite boundary, (5) weathered bedrock, and (6) unweathered bedrock. P‐wave explosive and hammer sources were found to have similar signal characteristics, and the aquifer and bedrock were both imaged using the hammer source. The deep shots below the water table have the most broadband frequency response for reflections, but stacking clear reflections was difficult. The S‐wave reflection results showed high lateral and vertical resolution of the basal saprolite clay, the sand and gravel aquifer, and very shallow clays above the aquifer. The S‐wave reflection stacking velocities were 10–20% of the P‐waves, increasing the resolution of the S‐wave section. The gravity data were modelled to fit the known drilling and P‐wave seismic reflection depths. The refraction results did not identify the top of bedrock, so refraction depths were not used for the gravity modeling in this highly weathered environment. The final gravity model mapped the bedrock topography beyond the lateral extent of the seismic and drilling data.

In this article, we describe in detail three seismic measurement campaigns based on refraction methods that we conducted at different sites in Bavaria, Germany. The measured data is published as an open data set. The particularity of this data set lies in its available ground truth information about each measurement site. Acquiring seismic data from sites with ground truth information is important for validation of seismic inversion algorithms. Since near-surface seismic field data with ground truth information is rather limited, we anticipate this data set to be a valuable contribution to the research community. For the measurements, three sites have been selected: (1) a gravel pit with a ground water layer, (2) a site above a highway tunnel and (3) a surface over underground tubes. The measurements have been conducted using line arrays of geophones, the Geode Seismograph from Geometrics Inc. and hammer strikes as seismic source. To obtain inversion results a travel time tomography based on first-arrivals within the software SeisImager is used. The inversion results show that we are able to image the ground water layer in the gravel pit, the highway tunnel and partly features of underground tubes. Furthermore, the results coincide with available ground truth information about the measurement sites. This paper summarizes the measurement campaigns and the respective data sets obtained through these campaigns. The data have been published by the authors as an open data set under the license CC BY 4.0 on figshare to make it available to the research community for validation of seismic data processing and inversion techniques.

The level of the environmental impact of the mining industry specifies the urgency of ecological management of the natural resources based on the satellite monitoring data. The high content of the suspended mineral particles in the industrial waters and the requirement to reduce their access to the natural water reservoirs determine the need to characterize the mininginduced pollution that can be carried out correctly with due account of the aggregate stability of dispersions. In spite of the theoretical concepts, prediction of the particles aggregation is limited by a lack of data on their interaction parameters. In order to parametrize the interactions in the mineral-water-mineral system it is proposed to use experimental data on aggregation of finely dispersed particles, obtained by the laser diffraction method in the equilibrium conditions. For this purpose the procedure of the experimental appraisal of the effective Hamaker constants has been elaborated using ores of developed deposits of the Kola mining complex as an example. The authors have studied the conditions of the surface layer of natural water reservoirs in the most industrially developed central part of the Murmansk region and defined characteristics of pollution with finely dispersed by-products of the mineral raw material treatment, according to the satellite observation data of the spatial distribution of the normalized difference turbidity index. The authors have established that the least propagation of the pollution into the natural water reservoirs is observed in the case of the apatite-nepheline ores processing by-products, which is explained by the effective aggregation of the finely dispersed nepheline particles. The proposed approach to apply data on mineral particles aggregation for interpretation of the satellite observations does not require carrying out in-situ observations and makes it possible to identify the mining-induced pollution of natural water reservoirs in industrial territories using suspended particles.

The multi-decadal Landsat data record is a unique tool for global land cover and land use change analysis. However, the large volume of the Landsat image archive and inconsistent coverage of clear-sky observations hamper land cover monitoring at large geographic extent. Here, we present a consistently processed and temporally aggregated Landsat Analysis Ready Data produced by the Global Land Analysis and Discovery team at the University of Maryland (GLAD ARD) suitable for national to global empirical land cover mapping and change detection. The GLAD ARD represent a 16-day time-series of tiled Landsat normalized surface reflectance from 1997 to present, updated annually, and designed for land cover monitoring at global to local scales. A set of tools for multi-temporal data processing and characterization using machine learning provided with GLAD ARD serves as an end-to-end solution for Landsat-based natural resource assessment and monitoring. The GLAD ARD data and tools have been implemented at the national, regional, and global extent for water, forest, and crop mapping. The GLAD ARD data and tools are available at the GLAD website for free access.

HighlightsThis study addresses two computational challenges in high-throughput phenotyping: scalability and efficiency.Specifically, we focus on extracting crop images and deriving vegetation indices using unmanned aerial systems.To this end, we outline a data processing pipeline, featuring a crop localization algorithm and trie data structure.We demonstrate the efficacy of our approach by computing large-scale and high-precision vegetation indices in a soybean breeding experiment, where we evaluate soybean growth under water inundation and temporal change.Abstract. In agronomy, high-throughput phenotyping (HTP) can provide key information for agronomists in genomic selection as well as farmers in yield prediction. Recently, HTP using unmanned aerial systems (UAS) has shown advantages in both cost and efficiency. However, scalability and efficiency have not been well studied when processing images in complex contexts, such as using multispectral cameras, and when images are collected during early and late growth stages. These challenges hamper further analysis to quantify phenotypic traits for large-scale and high-precision applications in plant breeding. To solve these challenges, our research team previously built a three-step data processing pipeline, which is highly modular. For this project, we present improvements to the previous pipeline to improve canopy segmentation and crop plot localization, leading to improved accuracy in crop image extraction. Furthermore, we propose a novel workflow based on a trie data structure to compute vegetation indices efficiently and with greater flexibility. For each of our proposed changes, we evaluate the advantages by comparison with previous models in the literature or by comparing processing results using both the original and improved pipelines. The improved pipeline is implemented as two MATLAB programs: Crop Image Extraction version 2 (CIE 2.0) and Vegetation Index Derivation version 1 (VID 1.0). Using CIE 2.0 and VID 1.0, we compute canopy coverage and normalized difference vegetation indices (NDVIs) for a soybean phenotyping experiment. We use canopy coverage to investigate excess water stress and NDVIs to evaluate temporal patterns across the soybean growth stages. Both experimental results compare favorably with previous studies, especially for approximation of soybean reproductive stage. Overall, the proposed methodology and implemented experiments provide a scalable and efficient paradigm for applying HTP with UAS to general plant breeding. Keywords: Data processing pipeline, High-throughput phenotyping, Image processing, Soybean breeding, Unmanned aerial systems, Vegetation indices.

Seismic land data are commonly plagued by nonhyperbolic distortions induced by a variable near‐surface, low‐velocity layer (LVL). First‐arrival refraction analysis is conventionally employed to estimate the LVL geometry and velocities. Then vertical static time shifts are used to replace the LVL velocities with the more uniform, faster velocities that characterize the underlying refracting layer. This methodology has earned a good reputation as a geophysical data processing tool; however, velocity replacement with static shifts assumes that no ray bending occurred at the LVL base and that waves propagated vertically through the LVL (even though conventional refraction analysis methods, which are used to derive LVL models from seismic data, are less restrictive). These assumptions often are inadequate in thick, complex LVL situations, where resulting errors may considerably hamper a statics‐based velocity replacement procedure. Wave‐equation datuming may be used to perform LVL velocity replacement when statics are inadequate. This method extrapolates the seismic data from the surface to the LVL base with the LVL velocities. Then it extrapolates the data from the LVL base to an arbitrary datum, with the replacement velocity field. The marine analog of such a procedure has been well documented in the geophysical literature, where the object is to remove distortions caused by an irregular water layer. Application of wave‐equation datuming to land data is more difficult because of certain common characteristics of land data (irregular shooting, large data gaps, and crooked line geometry, combined with lower signal/noise) and because the LVL estimation procedure is considerably more difficult. We demonstrate wave‐equation velocity replacement on land data from a western U.S. overthrust belt. The LVL in this region was particularly thick and complicated and ideal for a wave‐theoretical velocity‐replacement procedure. Standard refraction analysis techniques were employed to estimate the LVL, then wave‐equation datuming was used to perform the velocity replacement. Our derived LVL model was not perfect, so some imaging errors were expected because wave‐equation datuming is highly dependent upon the LVL model. Nevertheless, our results show that wave‐equation datuming generally allowed better shallow reflector imaging than could be achieved with conventional statics processing.

Abstract In practical engineering, the protection of FPSO water hammer is very important. Through simulation analysis, the relevant data are obtained to provide reference for relevant engineering practice. A general-purpose FPSO ballast water pipe network system was established by aft impulse software, and water hammer simulation calculation and analysis were carried out to find out the maximum pressure position of water hammer phenomenon. According to the water hammer generation mechanism, the simulation research was carried out by two-stage valve closing and adding surge tank into the pipeline. It was found that water hammer was easily caused by quick closing valve; the protection method of two-stage valve closing and installation of surge tank has a very objective protective effect, which provides a reference for related projects.

: This research sought to highlight the experiences of women in the shea industry in Kusawgu in Ghana. Recommendations to enhance and sustain the industry were also explored. A total of 60 women from four shea production groups, who lived in Kusawgu, participated in focus group discussions. The data was first analysed separately by the two researchers. Results were then compared to reconcile differences. The study demonstrates that the shea industry undoubtedly provided means of livelihood, self-dignity and respect for the women. Positive outcomes for working in groups include quick processing; sense of belonging and social capital; security and peace of mind; and skills development. However, lack of access to microfinance, travelling for longer distances, the period of time required to get water and fuel-wood, gender-based land ownership discrimination, and extinction of shea trees hamper production and income. Regardless of these challenges the women demonstrated resiliency by their continuous work in the industry. Due to the potential of the shea industry to reduce poverty among women, government should work hand-in-hand with the traditional authority to develop measures to sustain the industry. Social work practitioners could build the capability of the women in the shea industry to access existing pro-poor programmes.

All land uses affect storm water runoff However, different uses of the same site generate varying amounts of runoff Many communities have come to rely upon detention and/or retention basins for controlling the additional runoff resulting from land development. It is argued that this incremental approach to storm water management must be replaced with a more proactive long-term view.To achieve this, more user-friendly software capable of modeling the effect long-range land use plans have on the volume and behavior of storm water runoff is needed. This software, called a Spatial Decision Support System (SDSS), must be capable of guiding the user, who may not be an expert at runoff analysis, through the process and also capable of generating output in various formats understandable by lay persons. This study utilizes a systems analysis technique to develop a theoretical framework for the Storm Water SDSS.
Department of Urban Planning

[eng] The main objective proposed in this doctoral thesis was focused on the study and development of a solution for the remote sensing of the submarine topographic relief, using for this, inexpensive equipment. Here we focus in three works that altogether will improve the remote sensing process for underwater medium using sonars as the main relief data acquisition system. The problem was systematically addressed since the previous work in the master thesis, constituting three stages: 1) building a prototype data extraction platform, 2) data acquisition and 3) data processing. In the first stage was developed a prototype taking as a reference the modular structure and the software design applied in AUVI project (Acosta 2008), and besides it was used the model of autonomous navigation system developed to AutoTracker project (Acosta et al., 2005), this stage and part of the following one were developed in the master thesis. In the second stage, it was done the survey planning and the acoustic data extraction including navigational data in three different places: i) On the cove “Estancia”, located in Palma, Mallorca island/Spain, where we used the prototype developed in the first stage of this work as a platform to data extraction; ii) “Alfeite Arsenal” Port, located on the Tejo River, in Almada/Portugal into the context of robotics exercises promoted by the Navy of Portugal (REX2014). In this location, it was used the robotic vehicle ZARCO from the Oceansys Lab, through cooperative work with the Oceansys Lab. research group at the University of Porto (UP)/INESC in Portugal and finally, iii) in the “Bay of All Saints”, near the city of Salvador/Brazil, where were performed some missions to collect data using hydrographic survey boats in cooperation with the Federal University of Bahia (UFBA) and Belov Engineering - Port Engineering and Hydrographic Services Company, both located in Salvador/Bahia. Finally, the third stage, that is the main body of this thesis, was characterized by the data analysis and comparison between several datasets. In this stage, studies had been conducted to verify the feasibility of the use of spatial statistical algorithms in the process of bathymetric data interpolation without any ancillary information to support the prediction. We determined an optimized procedure for estimating the unsampled points, hence it was validated using a regular cross-validation method and a comparative validation method to compare the estimated data with a second dataset acquired in the same region and acting as a Merit Figure. The average discrepancy between the estimated data and Merit Figure data value was 25 cm, it is below the acceptable error for bathymetric data at depths below 30m (IHO 2012). In addition, an algorithm based on the Stochastic Resonance (SR) theory was developed. It consists in applying white noise in an optimal intensity level to improve the contrasts of acoustic images generated by a side Sonar Scan (SSS). The SR theory also, was used as a basis for development of a weak signals detection algorithm in sensing applications. Regarding the sensors application for measure remote sensing physical variables, we could cite the magnetic field meters (magnetometers), and inertial sensors (accelerometers and gyroscopes), in this study was performed a simulation of Chua's circuit operating in a chaotic regime as a sensor, where we could determine successfully the region of system solution into the strange attractor, using, for this, the technique of residence time, which will be defined along this thesis. The entire set of modules, techniques and processes described in this work proposed one solution to the remote sensing problem applied to the underwater environment, and give the opportunity to develop in more deep way future works in sensor integration, algorithms and data acquisition platform.
[cat] L'objectiu principal proposat en aquesta tesi doctoral es va centrar en l'estudi i desenvolupament d'una solució per a la detecció remota del relleu topogràfic submarí, utilitzant per a això un equip econòmic. Aquí ens centrem en tres treballs que en total milloraran el procés de teledetecció per al medi submarí utilitzant sonars com el principal sistema d'adquisició de dades de relleu. El problema es va abordar sistemàticament des del treball anterior a la tesi de màster, que constava de tres etapes: 1) construcció d'una plataforma d'extracció de dades prototip, 2) adquisició de dades i 3) tractament de dades. En la primera etapa es va desenvolupar un prototip prenent com a referència l'estructura modular i el disseny de programari aplicat en el projecte AUVI (Acosta 2008), a més d'utilitzar el model de sistema de navegació autònom desenvolupat per al projecte AutoTracker (Acosta et al., 2005 ), aquesta etapa i una part de la següent es van desenvolupar en la tesi de màster. En la segona etapa, es va realitzar la planificació de l'enquesta i l'extracció de dades acústiques, incloses les dades de navegació en tres llocs diferents: i) A la cala "Estancia", situada a Palma, illa de Mallorca / Espanya, on utilitzem el prototip desenvolupat a la primera etapa d'aquest treball com a plataforma d'extracció de dades; ii) Port "Alfeite Arsenal", ubicat al riu Tajo, a Almada / Portugal, en el context dels exercicis de robòtica promoguts per l'Armada de Portugal (REX2014). En aquesta ubicació, es va utilitzar el vehicle robotitzat ZARCO del laboratori Oceansys, a través del treball cooperatiu amb l'Oceansys Lab. grup d'investigació de la Universitat de Porto (UP) / INESC a Portugal i, finalment, iii) a la "Badia de Tots Sants", a prop de la ciutat de Salvador / Brasil, on es van realitzar algunes missions per recollir dades utilitzant vaixells d'enquestes hidrogràfiques en cooperació amb la Universitat Federal de Bahia (UFBA) i Belov Engineering - Port Engineering and Hydrographic Services Company, ambdós ubicats a Salvador / Bahia. Finalment, la tercera etapa, que és el cos principal d'aquesta tesi, es va caracteritzar per l'anàlisi de dades i la comparació entre diversos conjunts de dades. En aquesta etapa, s'han realitzat estudis per verificar la viabilitat de l'ús d'algoritmes estadístics espacials en el procés d'interpolació de dades batimètriques sense cap tipus d'informació auxiliar per a la predicció. Es va determinar un procediment optimitzat per estimar els punts sense mostrejar, per tant, es va validar mitjançant un mètode de validació de mètodes regular i un mètode de validació comparatiu per comparar les dades estimades amb un segon conjunt de dades adquirit a la mateixa regió i actuant com a Figura de mèrit. La discrepància mitjana entre les dades estimades i el valor de dades de Merit Figure va ser de 25 cm, per sota de l'error acceptable per a dades batimètriques a profunditats inferiors a 30 m (IHO 2012). A més, es va desenvolupar un algorisme basat en la teoria de la ressonància estocàstica (SR). Consisteix en aplicar soroll blanc en un nivell d'intensitat òptima per millorar els contrastos d'imatges acústiques generades per un costat Sonar Scan (SSS). La teoria del SR també es va utilitzar com a base per al desenvolupament d'un algoritme de detecció de senyals feble en la detecció d'aplicacions. Pel que fa a l'aplicació de sensors per a la mesura de les variables físiques de control remot, podríem citar els mesuradors de camp magnètic (magnetòmetres) i els sensors inercials (acceleròmetres i giroscopis), en aquest estudi es va realitzar una simulació del circuit de Chua que funciona en un règim caòtic com a sensor, on podríem determinar amb èxit la regió de la solució del sistema en l'estrany atractor, utilitzant, per a això, la tècnica del temps de residència, que es definirà al llarg d'aquesta tesi. Tot el conjunt de mòduls, tècniques i processos descrits en aquest treball proposen una solució al problema de teledetecció aplicat a l'entorn submarí i permeten desenvolupar de manera més profunda futurs treballs en integració de sensors, algorismes i plataforma d'adquisició de dades..
[spa] El principal objetivo propuesto en esta tesis doctoral se centró en el estudio y desarrollo de una solución para la detección remota del relieve topográfico submarino, utilizando para esto, equipos de bajo costo. Aquí nos enfocamos en tres trabajos que en conjunto mejorarán el proceso de detección remota para medios subacuáticos usando sonares como el principal sistema de adquisición de datos de alivio. El problema fue abordado sistemáticamente desde el trabajo anterior en la tesis de maestría, constituyendo tres etapas: 1) construcción de una plataforma prototipo de extracción de datos, 2) adquisición de datos y 3) procesamiento de datos. En la primera etapa se desarrolló un prototipo tomando como referencia la estructura modular y el diseño de software aplicado en el proyecto AUVI (Acosta 2008), y además se utilizó el modelo de sistema de navegación autónomo desarrollado para el proyecto AutoTracker (Acosta et al., 2005 ), esta etapa y parte de la siguiente se desarrollaron en la tesis de maestría. En la segunda etapa, se realizó la planificación de la encuesta y la extracción de datos acústicos, incluyendo datos de navegación en tres lugares diferentes: i) En la cala "Estancia", ubicada en Palma, isla de Mallorca / España, donde utilizamos el prototipo desarrollado en el primera etapa de este trabajo como una plataforma para la extracción de datos; ii) Puerto "Alfeite Arsenal", ubicado en el río Tajo, en Almada / Portugal en el contexto de ejercicios de robótica promovidos por la Armada de Portugal (REX2014). En esta ubicación, se utilizó el vehículo robótico ZARCO del Laboratorio Oceansys, a través del trabajo cooperativo con el Laboratorio Oceansys. grupo de investigación en la Universidad de Oporto (UP) / INESC en Portugal y finalmente, iii) en la "Bahía de Todos los Santos", cerca de la ciudad de Salvador / Brasil, donde se realizaron algunas misiones para recopilar datos utilizando barcos hidrográficos en cooperación con la Universidad Federal de Bahía (UFBA) y Belov Engineering - Compañía de Ingeniería Portuaria y Servicios Hidrográficos, ambas ubicadas en Salvador / Bahía. Finalmente, la tercera etapa, que es el cuerpo principal de esta tesis, se caracterizó por el análisis de datos y la comparación entre varios conjuntos de datos. En esta etapa, se realizaron estudios para verificar la viabilidad del uso de algoritmos estadísticos espaciales en el proceso de interpolación de datos batimétricos sin ninguna información auxiliar para respaldar la predicción. Determinamos un procedimiento optimizado para estimar los puntos no muestreados, por lo que se validó utilizando un método de validación cruzada regular y un método de validación comparativa para comparar los datos estimados con un segundo conjunto de datos adquiridos en la misma región y actuando como una figura de mérito. La discrepancia promedio entre los datos estimados y el valor de los datos de Merit Figure fue de 25 cm, está por debajo del error aceptable para los datos batimétricos a profundidades por debajo de 30 m (OHI 2012). Además, se desarrolló un algoritmo basado en la teoría de la Resonancia Estocástica (SR). Consiste en aplicar ruido blanco en un nivel de intensidad óptimo para mejorar los contrastes de las imágenes acústicas generadas por un Sonar Scan lateral (SSS). La teoría SR también se usó como base para el desarrollo de un algoritmo de detección de señales débiles en aplicaciones de detección. En cuanto a la aplicación de sensores para medir variables físicas de teledetección, podríamos citar los medidores de campo magnético (magnetómetros) y sensores inerciales (acelerómetros y giroscopios), en este estudio se realizó una simulación del circuito de Chua operando en un régimen caótico como sensor, donde pudimos determinar con éxito la región de la solución del sistema en el atractor extraño, utilizando, para ello, la técnica del tiempo de residencia, que se definirá a lo largo de esta tesis. El conjunto completo de módulos, técnicas y procesos descritos en este trabajo propuso una solución al problema de teledetección aplicado al entorno subacuático, y brinda la oportunidad de desarrollar de manera más profunda futuros trabajos de integración de sensores, algoritmos y plataforma de adquisición de datos.
[por] O objetivo principal proposto nesta tese de doutorado foi focado no estudo e desenvolvimento de uma solução para o sensoriamento remoto do alívio topográfico submarino, usando para isso, equipamentos baratos. Aqui nos concentramos em três trabalhos que, em conjunto, melhorarão o processo de sensoriamento remoto para o meio subaquático, utilizando os sonares como o principal sistema de aquisição de dados de alívio. O problema foi sistematicamente abordado desde o trabalho anterior na tese de mestrado, constituindo três etapas: 1) construção de um protótipo de plataforma de extração de dados, 2) aquisição de dados e 3) processamento de dados. Na primeira etapa foi desenvolvido um protótipo tomando como referência a estrutura modular e o projeto de software aplicado no projeto AUVI (Acosta 2008), e além disso, utilizou-se o modelo de sistema de navegação autônomo desenvolvido para o projeto AutoTracker (Acosta et al., 2005 ), este estágio e parte do seguinte foram desenvolvidos na tese de mestrado. Na segunda etapa, foi feito o planejamento da pesquisa e a extração de dados acústicos, incluindo dados de navegação em três lugares diferentes: i) Na enseada "Estancia", localizada em Palma, Ilha de Maiorca / Espanha, onde usamos o protótipo desenvolvido no primeira etapa deste trabalho como plataforma para a extração de dados; ii) Porto do "Alfeite Arsenal", localizado no rio Tejo, em Almada / Portugal no contexto de exercícios de robótica promovidos pela Marinha de Portugal (REX2014). Nessa localização, utilizou-se o veículo robotizado ZARCO do Laboratório Oceansys, através do trabalho cooperativo com o Oceansys Lab. grupo de pesquisa na Universidade do Porto (UP) / INESC em Portugal e, finalmente, iii) na "Baía de Todos os Santos", perto da cidade de Salvador / Brasil, onde foram realizadas algumas missões para coletar dados usando embarcações hidrográficas em cooperação com a Universidade Federal da Bahia (UFBA) e a Engenharia Belov - Empresa de Engenharia de Portos e Hidrográficos, ambos localizados em Salvador / Bahia. Finalmente, o terceiro estágio, que é o corpo principal desta tese, foi caracterizado pela análise de dados e comparação entre vários conjuntos de dados. Nesta fase, foram realizados estudos para verificar a viabilidade do uso de algoritmos estatísticos espaciais no processo de interpolação de dados batimétricos sem qualquer informação auxiliar para sustentar a predição. Determinamos um procedimento otimizado para estimar os pontos não amostrados, portanto, foi validado usando um método de validação cruzada regular e um método de validação comparativa para comparar os dados estimados com um segundo conjunto de dados adquirido na mesma região e atuando como uma Figura de mérito. A discrepância média entre os dados estimados eo valor de dados da Figura de Mérito foi de 25 cm, está abaixo do erro aceitável para dados batimétricos a profundidades abaixo de 30 m (IHO 2012). Além disso, um algoritmo baseado na teoria da Ressonância Estocástica (SR) foi desenvolvido. Consiste na aplicação de ruído branco em um nível de intensidade ótimo para melhorar os contrastes de imagens acústicas geradas por um lado de Sonar Scan (SSS). A teoria SR também foi utilizada como base para o desenvolvimento de um algoritmo de detecção de sinais fracos em aplicações de detecção. Em relação ao aplicativo de sensores para medir as variáveis físicas de sensoriamento remoto, podemos citar os medidores de campo magnético (magnetômetros) e sensores inerciais (acelerômetros e giroscópios), neste estudo realizou-se uma simulação do circuito de Chua operando em regime caótico como sensor, onde podemos determinar com sucesso a região da solução do sistema no atrativo estranho, usando, para isso, a técnica de tempo de residência, que será definida ao longo desta tese. Todo o conjunto de módulos, técnicas e processos descritos neste trabalho propôs uma solução para o problema de sensoriamento remoto aplicado ao ambiente subaquático e oferece a oportunidade de desenvolver de forma mais profunda os futuros trabalhos em integração de sensores, algoritmos e plataforma de aquisição de dados.

"August 2001." Includes bibliographical references (leaves 77-80). Examines the susceptibility of existing signal processing methods to errors and identifies other possible causes of depth error not accounted for by existing signal processing methods, by analysis of the detected laser return waveform data. Methods to improve depth accuracy are investigated.

D. Tech. (Department of Civil Engineering and Building, Faculty of Engineering and Technology), Vaal University of Technology
Growing demand for water due to increasing populations, industrialisation and water consuming lifestyles puts stress on existing water supply systems. To cater for the rising demand, water distribution networks are expanded beyond their design capacities and this creates transient “low-pressure-open-channel flow” (LPOCF) conditions. Current water supply models use “demand driven approach” (DDA) methodology which is not able to simulate transient LPOCF conditions, that poses an impediment to management/analysis of pressure-deficient networks. With a case study of the water supply network of Kampala City, LPOCF conditions were studied in this research. A “pressure/head driven approach” (PDA/HDA) was used in order to determine what demand is enabled by particular nodal pressures. Conversion of free surface to pressurised flow was analysed and modelled, with a view to clearly understanding occurrence of this phenomenon. The research demonstrated that if adequate pressures and flows are to be maintained, effectiveness of the water distribution network should be given as much attention as water production capacity. The research also indicated that when network pressures are low, the head-driven approach to water distribution modelling gives more accurate results than the traditional demand-driven methodology. Coexistence of free-surface and pressurised flow in networks prone to LPOCF conditions was confirmed and modelled. Results obtained highlighted the advantages of developing fully dynamic and transient models in the solution of transient LPOCF conditions in water distribution networks. Models developed allow application of PDA/HDA and DDA methodologies in systems that may exhibit LPOCF conditions thus enabling identification, understanding and analysis of the status of all sections of the network. These culminated in the development of a DSS to guide operational decisions that can be made to optimise network performance.

The research has entailed the formulation and coding of computer models for the design of pressurized irrigation systems. Particular emphasis has been given to the provision of routines for the evaluation of the expected performance from a designed system. Two separate sets of models have been developed, one for the block or in-field system and one for file mainline netWork. The thesis is presented in three seelions asfollows : * Basic theory, in which the general background to the research is covered. * The models, which includes detailed descriptions of both the design models and the computer programs. * Applications, in which several test casesof both sets of models are reported.

This project is focused on the goal of improving access to the Water Resources Institute (WRI) archives using a web-based GIS architecture. This project uses the newest version of ArcGIS Server as a method to support an internet-based map search environment, improved information management and data sharing.

Thesis submitted in fulfilment of the requirements for the degree Doctor of Technology: Electrical Engineering in the Faculty of Engineering at the Cape Peninsula University of Technology 2014
This thesis focuses on the design, development and real-time simulation of a robust nonlinear networked control for the dissolved oxygen concentration as part of the wastewater distributed systems. This concept differs from previous methods of wastewater control in the sense that the controller and the wastewater treatment plants are separated by a wide geographical distance and exchange data through a communication medium. The communication network introduced between the controller and the DO process creates imperfections during its operation, as time delays which are an object of investigation in the thesis. Due to the communication network imperfections, new control strategies that take cognisance of the network imperfections in the process of the controller design are needed to provide adequate robustness for the DO process control system. This thesis first investigates the effects of constant and random network induced time delays and the effects of controller parameters on the DO process behaviour with a view to using the obtained information to design an appropriate controller for the networked closed loop system. On the basis of the above information, a Smith predictor delay compensation controller is developed in the thesis to eliminate the deadtime, provide robustness and improve the performance of the DO process. Two approaches are adopted in the design of the Smith predictor compensation scheme. The first is the transfer function approach that allows a linearized model of the DO process to be described in the frequency domain. The second one is the nonlinear linearising approach in the time domain. Simulation results reveal that the developed Smith predictor controllers out-performed the nonlinear linearising controller designed for the DO process without time delays by compensating for the network imperfections and maintaining the DO concentration within a desired acceptable level. The transfer function approach of designing the Smith predictor is found to perform better under small time delays but the performance deteriorates under large time delays and disturbances. It is also found to respond faster than the nonlinear approach. The nonlinear feedback linearisig approach is slower in response time but out-performs the transfer function approach in providing robustness and performance for the DO process under large time delays and disturbances. The developed Smith predictor compensation schemes were later simulated in a real-time platform using LabVIEW. The Smith predictor controllers developed in this thesis can be applied to other process control plants apart from the wastewater plants, where distributed control is required. It can also be applied in the nuclear reactor plants where remote control is required in hazardous conditions. The developed LabVIEW real-time simulation environment would be a valuable tool for researchers and students in the field of control system engineering. Lastly, this thesis would form the basis for further research in the field of distributed wastewater control.

[EN] Over time, due to multiple operational and maintenance activities, the networks of water supply systems (WSSs) undergo interventions, modifications or even are closed. In many cases, these activities are not properly registered. Knowledge of the paths and characteristics (status and age, etc.) of the WSS pipes is obviously necessary for efficient and dynamic management of such systems. This problem is greatly augmented by considering the detection and control of leaks. Access to reliable leakage information is a complex task. In many cases, leaks are detected when the damage is already considerable, which brings high social and economic costs. In this sense, non-destructive methods (e.g., ground penetrating radar - GPR) may be a constructive response to these problems, since they allow, as evidenced in this thesis, to ascertain paths of pipes, identify component characteristics, and detect primordial water leaks. Selection of GPR in this work is justified by its characteristics as non-destructive technique that allows studying both metallic and non-metallic objects. Although the capture of information with GPR is usually successful, such aspects as the capture settings, the large volume of generated information, and the use and interpretation of such information require high level of skill and experience. This dissertation may be seen as a step forward towards the development of tools able to tackle the problem of lack of knowledge on the WSS buried assets. The main objective of this doctoral work is thus to generate tools and assess their feasibility of application to the characterization of components of WSSs from GPR images. In this work we have carried out laboratory tests specifically designed to propose, develop and evaluate methods for the characterization of the WSS buried components. Additionally, we have conducted field tests, which have enabled us to determine the feasibility of implementing such methodologies under uncontrolled conditions. The methodologies developed are based on techniques of intelligent data analysis. The basic principle of this work has involved the processing of data obtained through the GPR to look for useful information about WSS components, with special emphasis on the pipes. After performing numerous activities, one can conclude that, using GPR images, it is feasible to obtain more information than the typical identification of hyperbolae currently performed. In addition, this information can be observed directly, e.g. more simply, using the methodologies proposed in this doctoral work. These methodologies also prove that it is feasible to identify patterns (especially with the preprocessing algorithm termed Agent race) that provide fairly good approximation of the location of leaks in WSSs. Also, in the case of pipes, one can obtain such other characteristics as diameter and material. The main outcomes of this thesis consist in a series of tools we have developed to locate, identify and visualize WSS components from GPR images. Most interestingly, the data are synthesized and reduced so that the characteristics of the different components of the images recorded in GPR are preserved. The ultimate goal is that the developed tools facilitate decision-making in the technical management of WSSs, and that such tools can even be operated by personnel with limited experience in handling non-destructive methodologies, specifically GPR.
[ES] Con el paso del tiempo, y debido a múltiples actividades operacionales y de mantenimiento, las redes de los sistemas de abastecimiento de agua (SAAs) sufren intervenciones, modificaciones o incluso, son clausuradas, sin que, en muchos casos, estas actividades sean correctamente registradas. El conocimiento de los trazados y características (estado y edad, entre otros) de las tuberías en los SAAs es obviamente necesario para una gestión eficiente y dinámica de tales sistemas. A esta problemática se suma la detección y el control de las fugas de agua. El acceso a información fiable sobre las fugas es una tarea compleja. En muchos casos, las fugas son detectadas cuando los daños en la red son ya considerables, lo que trae consigo altos costes sociales y económicos. En este sentido, los métodos no destructivos (por ejemplo, ground penetrating radar - GPR), pueden ser una respuesta a estas problemáticas, ya que permiten, como se pone de manifiesto en esta tesis, localizar los trazados de las tuberías, identificar características de los componentes y detectar las fugas de agua cuando aún no son significativas. La selección del GPR, en este trabajo se justifica por sus características como técnica no destructiva, que permite estudiar tanto objetos metálicos como no metálicos. Aunque la captura de información con GPR suele ser exitosa, la configuración de la captura, el gran volumen de información, y el uso y la interpretación de la información requieren de alto nivel de habilidad y experiencia por parte del personal. Esta tesis doctoral se plantea como un avance hacia el desarrollo de herramientas que permitan responder a la problemática del desconocimiento de los activos enterrados de los SAAs. El objetivo principal de este trabajo doctoral es, pues, generar herramientas y evaluar la viabilidad de su aplicación en la caracterización de componentes de un SAA, a partir de imágenes GPR. En este trabajo hemos realizado ensayos de laboratorio específicamente diseñados para plantear, elaborar y evaluar metodologías para la caracterización de los componentes enterrados de los SAAs. Adicionalmente, hemos realizado ensayos de campo, que han permitido determinar la viabilidad de aplicación de tales metodologías bajo condiciones no controladas. Las metodologías elaboradas están basadas en técnicas de análisis inteligentes de datos. El principio básico de este trabajo ha consistido en el tratamiento adecuado de los datos obtenidos mediante el GPR, a fin de buscar información de utilidad para los SAAs respecto a sus componentes, con especial énfasis en las tuberías. Tras la realización de múltiples actividades, se puede concluir que es viable obtener más información de las imágenes de GPR que la que actualmente se obtiene con la típica identificación de hipérbolas. Esta información, además, puede ser observada directamente, de manera más sencilla, mediante las metodologías planteadas en este trabajo doctoral. Con estas metodologías se ha probado que también es viable la identificación de patrones (especialmente el pre-procesado con el algoritmo Agent race) que proporcionan aproximación bastante acertada de la localización de las fugas de agua en los SAAs. También, en el caso de las tuberías, se puede obtener otro tipo de características tales como el diámetro y el material. Como resultado de esta tesis se han desarrollado una serie de herramientas que permiten visualizar, identificar y localizar componentes de los SAAs a partir de imágenes de GPR. El resultado más interesante es que los resultados obtenidos son sintetizados y reducidos de manera que preservan las características de los diferentes componentes registrados en las imágenes de GPR. El objetivo último es que las herramientas desarrolladas faciliten la toma de decisiones en la gestión técnica de los SAAs y que tales herramientas puedan ser operadas incluso por personal con una experiencia limitada en el manejo
[CAT] Amb el temps, a causa de les múltiples activitats d'operació i manteniment, les xarxes de sistemes d'abastament d'aigua (SAAs) se sotmeten a intervencions, modificacions o fins i tot estan tancades. En molts casos, aquestes activitats no estan degudament registrats. El coneixement dels camins i característiques (estat i edat, etc.) de les canonades d'aigua i sanejament fa evident la necessitat d'una gestió eficient i dinàmica d'aquests sistemes. Aquest problema es veu augmentat en gran mesura tenint en compte la detecció i control de fuites. L'accés a informació fiable sobre les fuites és una tasca complexa. En molts casos, les fugues es detecten quan el dany ja és considerable, el que porta costos socials i econòmics. En aquest sentit, els mètodes no destructius (per exemple, ground penetrating radar - GPR) poden ser una resposta constructiva a aquests problemes, ja que permeten, com s'evidencia en aquesta tesi, per determinar rutes de canonades, identificar les característiques dels components, i detectar les fuites d'aigua quan encara no són significatives. La selecció del GPR en aquest treball es justifica per les seves característiques com a tècnica no destructiva que permet estudiar tant objectes metàl·lics i no metàl·lics. Tot i que la captura d'informació amb GPR sol ser reeixida, aspectes com ara la configuració de captura, el gran volum d'informació que es genera, i l'ús i la interpretació d'aquesta informació requereix alt nivell d'habilitat i experiència. Aquesta tesi pot ser vista com un pas endavant cap al desenvolupament d'eines capaces d'abordar el problema de la manca de coneixement sobre els actius d'aigua i sanejament enterrat. L'objectiu principal d'aquest treball doctoral és, doncs, generar eines i avaluar la seva factibilitat d'aplicació a la caracterització dels components de los SAAs, a partir d'imatges GPR. En aquest treball s'han dut a terme proves de laboratori específicament dissenyats per proposar, desenvolupar i avaluar mètodes per a la caracterització dels components d'aigua i sanejament soterrat. A més, hem dut a terme proves de camp, que ens han permès determinar la viabilitat de la implementació d'aquestes metodologies en condicions no controlades. Les metodologies desenvolupades es basen en tècniques d'anàlisi intel·ligent de dades. El principi bàsic d'aquest treball ha consistit en el tractament de dades obtingudes a través del GPR per buscar informació útil sobre els components d'SAA, amb especial èmfasi en la canonades. Després de realitzar nombroses activitats, es pot concloure que, amb l'ús d'imatges de GPR, és factible obtenir més informació que la identificació típica d'hipèrboles realitzat actualment. A més, aquesta informació pot ser observada directament, per exemple, més simplement, utilitzant les metodologies proposades en aquest treball doctoral. Aquestes metodologies també demostren que és factible per identificar patrons (especialment el pre-processat amb l'algoritme Agent race) que proporcionen bastant bona aproximació de la localització de fuites en SAAs. També, en el cas de tubs, es pot obtenir altres característiques com ara el diàmetre i el material. Els principals resultats d'aquesta tesi consisteixen en una sèrie d'eines que hem desenvolupat per localitzar, identificar i visualitzar els components dels SAAS a partir d'imatges GPR. El resultat més interessant és que els resultats obtinguts són sintetitzats i reduïts de manera que preserven les característiques dels diferents components registrats en les imatges de GPR. L'objectiu final és que les eines desenvolupades faciliten la presa de decisions en la gestió tècnica de SAA, i que tals eines poden fins i tot ser operades per personal amb poca experiència en el maneig de metodologies no destructives, específicament GPR.
Ayala Cabrera, D. (2015). Characterization of components of water supply systems from GPR images and tools of intelligent data analysis [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/59235
TESIS
Premiado

A pumped storage plant (PSP) is by far the most cost effective and mature technology for energy storage at a large-scale, and therefore, this technology is rapidly being developed and deployed. A reversible pump turbine (RPT) is the vital component of a PSP, and whether a PSP can operate safely and stably mainly depends on the characteristics of the RPT. However, the existence of S-shaped characteristics of a RPT usually leads to severe water hammer and pressure pulsations during the transient processes of load rejection. Therefore, hydraulic transient analysis in a PSP is one of the most important issues for the prevention of undesirable pressure fluctuations in waterways. Theoretically, the most accurate method is to conduct on-site measurements of all possible load cases to obtain the extreme values of pressure. However, extreme operating conditions such as 2-stage load rejection pose serious threats to the safety of the water conveyance system, making it impossible to carry out field trials under such conditions. This paper gives the numerical prediction of extreme and critical load case scenarios from the simultaneous load rejection field test on a double unit of a PSP in China. The dynamic transient numerical model for load rejection of the PSP is developed by introducing the method of characteristics. The boundary conditions, such as the real adopted wicket gate closure law and parameters of the water conveyance system, are calibrated according to the field test data. Considering the large pressure pulsations in the PSP during load rejection, a proper pressure pulsations amendment is proposed as well. Eventually, the hydraulic behavior of the critical load cases are numerically investigated by the modified model. And the results are amended by the proposed pressure pulsations processing approach to predict whether the hydraulic parameters can satisfy the design criteria, which can ensure safe operation of the PSP in the future. The achievements of the study can serve as a reference for similar PSP projects.

Abstract In hard disk drives (HDD), the head-media spacing has decreased to less than 10 nm. Across this nanoscale gap, the heat transfer between the head and media may affect the air-bearing design, lubricant transfer and contact issues. Thus, understanding the heat transfer mechanism is very important to magnetic recording, especially for Heat Assisted Magnetic Recording (HAMR). In this paper, the heat transfer between a head and a static media is studied. In particular, the effect of humidity on the nanoscale heat transfer between a head and a static media is studied experimentally. From the transient and steady data of the experiments, it is proposed that the dynamic response of head protrusion is faster than heat dissipation. Also, a layer of water is assumed to form between the head and the media under high humidity. The water-layer affects the spacing and the heat transfer coefficient across the interface. In the near-contact regime, namely when the clearance is less than 2 nm or so, the protrusion interacts with the water-layer on the media, resulting in a lower rate of change of cooling.

Abstract Direct calculations of the transient cavitating water-hammer pipe flows using the Space-Time Conservation Element and Solution Element method, or the CE/SE method for short, is reported. The principles of the CE/SE method is treating space and time as one entity, and the calculation of flow properties is based on the local and global space-time flux conservation. As a contrast to the modern upwind schemes, no Riemann solver is used, thus the logic of the present scheme for cavitating flows is much simpler. Two numerical examples are reported in this paper: (1) a hydraulic shock problem, and (2) a cavitating pipe flow. For the hydraulic shock problem, we demonstrate the capability of the CE/SE method for capturing contact discontinuities in cavitating fluids. For the pipe flows, a two-phase homogeneous equilibrium cavitation model is employed. In both cases, numerical results compared favorably with the experimental data and analytical solution.

Abstract Water hammer is oscillatory pressure behavior in a wellbore resulting from the inertial effect of flowing fluid being subjected to an abrupt change in velocity. It is commonly observed at the end of large-scale hydraulic fracturing treatments after fluid injection rate is rapidly reduced or terminated. In this paper, factors affecting treatment-related water hammer behavior are disclosed, and field studies are introduced correlating water hammer characteristics to fracture intensity and well productivity. A simulator based on fundamental fluid-mechanics concepts was developed to model water hammer responses for various wellbore configurations and treatment characteristics. Insight from the modeling work was used to develop an optimal process of terminating fluid injection to obtain a consistent, identifiable oscillatory response for evaluating water hammer periodicity, decay rate, and oscillatory patterns. A completion database was engaged in a semi-automated process to evaluate numerous treatments. A data screening method was developed and implemented for enhancing interpretation reliability. Derived water hammer components were correlated to fracture intensity, well productivity and in certain cases, loss of treatment confinement to the intended treatment interval. Using the above process, thousands of hydraulic fracturing treatments were evaluated, and the results of that work are included in this study. The treatments were performed in wells based in Texas, South America, and Canada and completed in low permeability and unconventional reservoirs. The water hammer decay rate was determined to be a reliable indication of the system friction (friction in the wellbore and hydraulic fracture network) that drains energy from the water hammer pulse. In unconventional reservoirs characterized by small differences in the minimum and maximum horizontal stresses, high system friction correlated positively with fracture intensity/complexity and well performance. Results were constrained with instantaneous shut-in pressure (ISIP) and pressure falloff measurements to identify instances of direct communication with previously treated offset wellbores. The resulting analyses provided: – identification of enhanced-permeability intervals – indications of hydraulic fracture geometry – assessment of treatment modifications intended to enhance fracture complexity – identification of loss of treatment confinement to the intended interval – location of associated points of failure in the wellbore Topics covered in the paper include: Introduction Joukowsky Equation Period and Boundary Conditions Review of Prior Work on Water Hammer Analysis Shut-In Pressure Data, Analysis, and Model Data collection frequency Data issues and requirements Water Hammer Analytical Method Water Hammer Model Effects on Water hammer signature Fluid properties Step-down rate change and duration Perforation friction Applications Identification of Boundary Condition Identification of Treatment Stage Isolation Identification of Casing Failure Depth Identification of Excess Period (Excess Length) Case Study – Water Hammer Data in an Unconventional Reservoir Interpretation of frac geometry and friction in the fracture Relationship to well productivity