Дисертації з теми "Multi Stage Design"
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1
Stampfli, John J. "Design of a two-stage multi-state experimental biogas reactor." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/127871.
Повний текст джерелаАнотація:
Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, May, 2020Cataloged from the official PDF of thesis.
Includes bibliographical references (pages 23-25).
Anaerobic digestion is a process that breaks down waste and other feed materials and produces biogas. A biogas reactor, or anaerobic digester, is designed to conduct anaerobic digestion in a closed environment and to collect the produced biogas. This is an important field of study because biogas is a renewable energy source. If it can be produced more efficiently, it may become a feasible alternative source of green energy. This thesis outlines the design of a lab-scale experimental reactor with a large range of functionality. The design permits many different environmental conditions, allowing anaerobic digestion to be thoroughly studied with one setup.
by John J. Stampfli.
S.B.
S.B. Massachusetts Institute of Technology, Department of Mechanical Engineering
2
Magirr, Dominic. "Design, conduct and analysis of multi-arm multi-stage clinical trials." Thesis, Lancaster University, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.664454.
Повний текст джерелаАнотація:
In this thesis, contributions are made towards improving the design, conduct and analysis of multi-arm multi-stage clinical trials. First, we generalize the Dunnett (1955) test to derive efficacy and futility boundaries for a multi-arm multi-stage clinical trial. We show the boundaries control the familywise error rate in the strong sense. The method is applicable for any number of treatment arms, number of stages and number of patients per treatment per stage. It can be used for a wide variety of boundary types or rules derived from a-spending functions. Additionally, we show how sample size can be computed under a least favourable configuration power requirement and derive formulae for expected sample sizes. Next, we describe a general method for finding a confidence region for a vector of K unknown parameters that is compatible with the decisions of a two-stage closed testing procedure in an adaptive experiment. The closed test procedure is characterized by the fact that rejection or nonrejection of a null hypothesis may depend on the decisions for other hypotheses and the compatible confidence region will, in general, have a complex, nonrectangular shape. We find the smallest Cartesian product of simultaneous confidence intervals containing the region and provide computational shortcuts for calculating the lower bounds for parameters corresponding to the rejected null hypotheses. We illustrate the methodology with a detailed example of an adaptive Phase II/III clinical trial. Finally, using the combination test principle and the conditional error principle, we develop flexible sequential designs for multi-arm clinical trials with early stopping for efficacy and futility. Such designs have the flexibility to cope with a large range of exigencies that may occur in practice. They also have the advantage that test decisions are based on sufficient statistics if the trial proceeds as originally planned.
3
Bratton, D. J. "Design issues and extensions of multi-arm multi-stage clinical trials." Thesis, University College London (University of London), 2015. http://discovery.ucl.ac.uk/1459437/.
Повний текст джерелаАнотація:
The increasing cost of randomised controlled trials is hindering the rate at which new, effective therapies reach patients. To accelerate drug development, more efficient clinical trial designs are needed. One such design which has had success in speeding up the evaluation of therapies in cancer is the multi-arm multi-stage (MAMS) design. This particular design compares multiple new treatments against a control in a single trial, obviating the need for multiple two-arm studies, and ceases recruitment to poorly performing arms during the study. To further increase efficiency, interim assessments can be based on an intermediate outcome which is on the causal pathway to the primary outcome of the trial, thus allowing phases 2 and 3 of evaluation to be incorporated into a single, seamless design. The MAMS design was initially developed for trials in cancer where time to event outcomes are commonly used. To make it more widely applicable to other disease areas, we first extend the design to other types of outcome measure such as binary. The new designs are then applied to trials in tuberculosis --- a disease area with many new treatments currently in the clinical pipeline and which may therefore benefit from using more efficient trial designs. We then consider more general design issues such as familywise error rate and expected sample size and present calculations of both measures using simulation. Methods are developed for finding designs which have the desired overall operating characteristics and which are the most efficient under particular optimality criteria, known as admissible designs. Guidance is provided for choosing the number of stages and allocation ratio for a particular number of arms and we apply the methods developed in the thesis to existing and hypothetical MAMS trials. Throughout, Stata programs are created and updated to accommodate the use of the methods in practice.
4
Despain, Dillon J. "Design Validation of a Multi-Stage Gradually Deploying Stent." BYU ScholarsArchive, 2021. https://scholarsarchive.byu.edu/etd/9163.
Повний текст джерелаАнотація:
Angioplasty, or the use of rapidly deploying stents, is a common treatment for reopening narrowed vasculature often caused by atherosclerotic plaque. However, in-stent restenosis (ISR) induced by intimal hyperplasia is a common challenge to angioplasty. High impact stresses from current stent deployment processes have been linked to intimal hyperplasia; thus a stent that is gradually deployed over a longer period of time holds potential to mitigate these stresses. This work hypothesizes that resorbable polymeric links can be used as a triggering mechanism to enable repeatably controlled deployment of a compliant nitinol stent design with the eventual goal of reducing intimal hyperplasia. The aims of this work include the structured design process and design validation of a stent intended to meet this challenge. A structured design process was used to develop a multi-stage, gradually deploying nitinol stent in which PDLG (DL-lactide/Glycolide copolymer) bioresorbable links constrained specific mechanical cells within the stent geometry, thus limiting initial deployment to an intermediate diameter and allowing for secondary gradual deployment as the PDLG degraded via a combination of bioresorption and creep. A finite element analysis was carried out to design the link geometry to hold the stent at an intermediate stage (90% of final diameter) upon initial deployment, and enable a gradual secondary deployment phase lasting several minutes. Prototypes were then manufactured and the design was validated in a flow chamber mimicking the conditions of human blood flow and temperature. Using a camera and image processing methods, the diameter increase of the stents was tracked over time to characterize the secondary gradual deployment process of the stents. Results showed the links constrained the stents to an initial ~90% diameter upon initial deployment, followed by a gradual, secondary deployment with an average 63.2% rise time of 16.2 minutes. Creep was observed to be the primary driver of the gradual deployment, followed by subsequent bioresorption of the material. All prototypes exhibited gradual secondary deployment without any visible delamination of the bioresorbable links from the stent struts. Based on these findings it can be concluded our hypothesis has been demonstrated, and that a feasible gradually deploying stent design has been mechanically validated, preparatory to pre-clinical studies of its efficacy. Prior to clinical application, future in vivo work is needed to compare actual ISR rates with this stent design to other commonly used stent designs in preclinical trials. In addition, further preclinical work is needed to compare ISR rates through several stent design parameters such as initial deployment diameter, gradual deployment rate, final deployment diameter, and stent sizes to give insights into the optimal stent design. We anticipate that this gradually expanding stent design could reduce in-stent restenosis and improve clinical outcomes.
5
Agarwal, Pranab. "Conceptual design of long-span trusses using multi-stage heuristics." Thesis, Texas A&M University, 2003. http://hdl.handle.net/1969.1/3863.
Повний текст джерелаАнотація:
A hybrid method that addresses the design and optimization of long-span steel trusses is presented. By utilizing advancements in present day computing and biologically inspired analysis and design, an effort has been made to automate the process of evolving optimal trusses in an unstructured problem domain. Topology, geometry and sizing optimization of trusses are simultaneously addressed using a three stage methodology. Multi-objective genetic algorithms are used to optimize the member section sizes of truss topologies and geometries. Converting constraints into additional objectives provides a robust algorithm that results in improved convergence to the pareto-optimal set of solutions. In addition, the pareto-curve plotted based on how well the different objectives are satisfied helps in identifying the trade-offs that exist between these objectives, while also providing an efficient way to rank the population of solutions during the search process. A comparison study between multi-objective genetic algorithms, simulated annealing, and reactive taboo search is conducted to evaluate the efficiency of each method with relation to its overall performance, computational expense, sensitivity to initial parameter settings, and repeatability of finding near-global optimal designs. The benefit of using a three stage approach, and also implementing the entire model on parallel computers, is the high level of computational efficiency that is obtained for the entire process and the near-optimal solutions obtained. The overall efficiency and effectiveness of this method has been established by comparing the truss design results obtained using this method on bridge and roof truss benchmark problems with truss designs obtained by other researchers. One of the salient features of thisresearch is the large number of optimal trusses that are produced as the final result. The range of designs available provides the user with the flexibility to select the truss design that best matches their design requirements. By supporting human-computer interactions between these stages, the program also incorporates subjective aesthetic criteria, which assist in producing final designs in consonance with the user's requirements.
6
Sigvant, John. "Conceptual Design of an Air- launched Multi-stage Launch Vehicle." Thesis, KTH, Fysik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-284355.
Повний текст джерелаАнотація:
In the present thesis, the objective was to find the maximum amount of payload mass that can be put into a 500 km polar orbit by a 1400 kg air-launched multi-stage rocket launched from a fighter jet platform. To fulfill the objective an algorithm incorporating several modules was developed. The modules performed calculations based on theoretical models and literature values to arrive at optimal design variables. From the design the maximum payload mass was able to be derived and it was concluded that a three-stage launch vehicle was able to deliver a 22.0 kg payload to the desired orbit.I den här avhandlingen var syftet att hitta den maximala mängden nyttolastmassa som kan transporteras av en 1400 kg flerstegsraket uppskjuten från luften till en 500 km polär bana. För att uppfylla målet utvecklades en algoritm med flera moduler. Modulerna utförde beräkningar baserade på teoretiska modeller och litteraturvärden för att komma fram till optimala designvariabler. Från konstruktionen kunde den maximala nyttolastmassan härledas och det konstaterades att en trestegsraket kunde leverera en nyttolast på 22.0 kg till den önskade omloppsbanan.
7
Bert, Jérôme. "Application of a design optimization strategy to multi-stage compressor matching." Thesis, Massachusetts Institute of Technology, 2006. http://hdl.handle.net/1721.1/36171.
Повний текст джерелаАнотація:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2006.Includes bibliographical references (p. 96-97).
A major challenge in the design of multi-stage compressors is the matching of stages to enable stable operation over a large range of mass flows and operating conditions. Particularly in turbofan low-pressure compressors, where a variable geometry cannot be implemented, design strategies for maximum efficiency at high speed can compromise the surge margin at low speed. In this thesis, a design optimization framework has been implemented to an industry-strength compressor-matching problem. The optimization framework combines a mean-line flow solver and a dynamic stability analysis of a six-stage low-pressure compressor of a modern turbofan engine to optimize the blade row geometry for enhanced stability at flight idle conditions. To assess the potential improvements in compressor stability at low speed, a number of optimization strategies are employed using different objective functions and stability metrics. To estimate the performance and stability of the six-stage compressor, a mean-line flow solver is developed and coupled with a previously developed dynamic compressor-stability analysis. A fan-root flow model and an endwall loss correlation are developed using performance data provided by industry.
(cont.) The analysis reveals that the models enable an adequate estimation of the datum compressor performance. This methodology is then used in an optimization effort searching for the optimum compressor design. A compressor blade parametrization based on Bezier splines is developed to explore a range of possible blade geometries. A CFD-based blade-row performance database is established using the blade-to-blade solver MISES. This facilitates an effective means to predict the blade performance for various geometries defined by the optimizer. To find the best solution for the compressor-matching problem, a number of optimization strategies are applied to the datum compressor. The best result is obtained using an optimization strategy based on industry surge margin. An improvement of 14.8% in flight idle surge margin is achieved while maintaining the design pressure ratio and efficiency at climb speed within 1% and 0.3 points of the design values respectively. A compressor design optimization based on a dynamic-stability metric is also employed. Due to time constraints, this strategy could not be fully explored and the preliminary results suggest that further work is required.
(cont.) The best results is a 14.8% improvement in the flight idle surge margin, but the re-matching of the compressor and the associated increase in the rotor loading of the second stage entail high-risk design modifications. This suggests that, given these design limitations, the best matching is achieved by the datum configuration. In summary, the thesis demonstrates that the developed compressor design optimization methodology is applicable to industry-strength design problems, and the framework is shown to have the potential to investigate compressor designs for optimum matching.
by Jérôme Bert.
S.M.
8
Almasarwah, Najat E. MASARWAH. "Multi-Stage Cellular Manufacturing System Design under Certain and Uncertain Conditions." Ohio University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1605028865095297.
Повний текст джерела
9
Neverov, Gregory Michael. "Design and implementation of a multi-stage, object-oriented programming language." Thesis, Queensland University of Technology, 2007. https://eprints.qut.edu.au/16559/1/Gregory_Michael_Neverov_Thesis.pdf.
Повний текст джерелаАнотація:
Multi-stage programming is a valuable technique for improving the performance of computer programs through run-time optimization. Current implementations of multi-stage programming do not support run-time type introspection, which is a significant feature of modern object-oriented platforms such as Java and C#. This is unfortunate because many programs that use type introspection in these languages could be improved with multi-staging programming.
The aim of this research is to investigate the interaction between multi-stage programming and object-oriented type introspection. This is done by the invention of a new programming language that is a multi-stage extension to C#. The language is capable of expressing traditional multi-stage programs as well as a new style of multi-stage programs that incorporate type introspection, most notably polytypic algorithms such as object serialization. A compiler for the language is implemented and freely available. The language is significant because it is the first object-oriented, multi-stage language; the first attempt to combine type introspection with multi-stage programming; and the first exploration of polytypic programming in a multi-stage context.
10
Neverov, Gregory Michael. "Design and implementation of a multi-stage, object-oriented programming language." Queensland University of Technology, 2007. http://eprints.qut.edu.au/16559/.
Повний текст джерелаАнотація:
Multi-stage programming is a valuable technique for improving the performance of computer programs through run-time optimization. Current implementations of multi-stage programming do not support run-time type introspection, which is a significant feature of modern object-oriented platforms such as Java and C#. This is unfortunate because many programs that use type introspection in these languages could be improved with multi-staging programming. The aim of this research is to investigate the interaction between multi-stage programming and object-oriented type introspection. This is done by the invention of a new programming language that is a multi-stage extension to C#. The language is capable of expressing traditional multi-stage programs as well as a new style of multi-stage programs that incorporate type introspection, most notably polytypic algorithms such as object serialization. A compiler for the language is implemented and freely available. The language is significant because it is the first object-oriented, multi-stage language; the first attempt to combine type introspection with multi-stage programming; and the first exploration of polytypic programming in a multi-stage context.
11
Voellmy, Andreas. "Multi agent room simulation for early stage building layout design Diploma thesis /." Zürich : ETH, Eidgenössische Technische Hochschule Zürich, [Department of Computer Science], 2003. http://e-collection.ethbib.ethz.ch/show?type=dipl&nr=133.
Повний текст джерела
12
Blanvillain, Emmanuel 1979. "Dynamic stability analysis of a multi-stage axial compressor with design implications." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/82255.
Повний текст джерела
13
Zhou, Xiaoyu M. Eng Massachusetts Institute of Technology. "Design of a demand driven multi-item-multi-stage manufacturing system : production scheduling, WIP control and Kanban implementation." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/55251.
Повний текст джерелаАнотація:
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 93).
The project is conducted in a multi-item-multi-stage manufacturing system with high volume products. The objectives are to optimize the inventory structure and improve production scheduling process. The stock building plan is studied carefully to understand the demand seasonality characteristics and the planning guidelines that the factory is currently following. A new base stock policy is introduced to the 5 focused production stages to establish a demand driven system with controlled inventory and new rules to guide the daily production. The line coupling concept is also added to further refine the inventory structure. After that, the production leveling method is employed to help reduce the variation of daily production targets. Finally, a Kanban system is designed to facilitate the demand driven manufacturing under the operation of the new base stock policy. With the appropriate inventory control and production scheduling policy, the overall inventory level in the factory is reduced by 61% based on calculation, leading to a savings of 70% of the total inventory cost. Moreover, the establishment of Kanban system has simplified the daily manufacturing activity on the operation level and helped the factory become a lean manufacturer.
by Xiaoyu Zhou.
M.Eng.
14
Montoya, Mario 1978. "On developing business architectures : a multi-framework evaluation of an early-stage enterprise." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/59261.
Повний текст джерелаАнотація:
Thesis (S.M. in System Design and Management)--Massachusetts Institute of Technology, Engineering Systems Division, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 193-196).
Early-stage enterprises are characterized by leveraging limited resources during periods of accelerating industry growth and relatively high uncertainty. This thesis is an examination of an early-stage enterprise within the medical technology industry using multiple frameworks. In addition to the standard Lean Advancement Initiative (LAI) suite of tools, the enterprise will be evaluated using Nightingale and Rhodes' eight Enterprise Architecture (EA) views, Kaplan's Balanced Scorecard (BSC), McKinsey's 7S framework, and Grave's Spiral Dynamics. Moreover, this thesis includes a practical examination of the current state using the framework developed by Piepenbrock's doctoral thesis that introduced the notion of modular versus integral enterprise architectures. A transformation plan is proposed based on the firm's current state and preferred future state based on insights from the various self-assessments and prevailing corporate strategy. The transformation plan is also informed by the author's perceived receptivity, commitment and need for change of the organization. The case organization's current state is described in general terms to protect the company's identity since the material presented includes portions of their corporate strategy and source of competitive advantage. Recognizing that all competitive advantage is temporary, considerable care has been exercised to balance the relevance of the research with the privacy needs of the organization.
by Mario Montoya, Jr..
S.M.in System Design and Management
15
Suri, Ramaa Saket. "Design of Voltage Boosting Rectifiers for Wireless Power Transfer Systems." Thesis, University of North Texas, 2019. https://digital.library.unt.edu/ark:/67531/metadc1505212/.
Повний текст джерелаАнотація:
This thesis presents a multi-stage rectifier for wireless power transfer in biomedical implant systems. The rectifier is built using Schottky diodes. The design has been simulated in 0.5µm and 130nm CMOS processes. The challenges for a rectifier in a wireless power transfer systems are observed to be the efficiency, output voltage yield, operating frequency range and the minimum input voltage the rectifier can convert. The rectifier outperformed the contemporary works in the mentioned criteria.
16
Metta, Haritha. "A MULTI-STAGE DECISION SUPPORT MODEL FOR COORDINATED SUSTAINABLE PRODUCT AND SUPPLY CHAIN DESIGN." UKnowledge, 2011. http://uknowledge.uky.edu/gradschool_diss/137.
Повний текст джерелаАнотація:
In this research, a decision support model for coordinating sustainable product and supply chain design decisions is developed using a multi-stage hierarchical approach. The model evaluates alternate product designs and their corresponding supply chain configurations to identify the best product design and the corresponding supply chain configuration that maximizes the economic, environmental and societal benefits. The model considers a total life-cycle approach and incorporates closed-loop flow among multiple product lifecycles. In the first stage, a mixed integer linear programming model is developed to select for each product design an optimal supply chain configuration that maximizes the profit. In the subsequent stages, the economic, environmental and societal multiple life-cycle analysis models are developed which assess the economic, environment and the societal performance of each product design and its optimal supply chain configuration to identify the best product design with highest sustainability benefits.
The decision support model is applied for an example problem to illustrate the procedure for identifying the best sustainable design. Later, the model is applied for a real-time refrigerator case to identify the best refrigerator design that maximizes economic, environmental and societal benefits. Further, sensitivity analysis is performed on the optimization model to study the closed-loop supply chain behavior under various situations. The results indicated that both product and supply chain design criteria significantly influence the performance of the supply chain. The results provided insights into closed-loop supply chain models and their behavior under various situations. Decision support models such as above can help a company identify the best designs that bring highest sustainability benefits, can provide a manager with holistic view and the impact of their design decisions on the supply chain performance and also provide areas for improvement.
17
Sarjito. "An investigation of the design and performance of a multi-stage downdraught evaporative cooler." Thesis, Kingston University, 2012. http://eprints.kingston.ac.uk/23728/.
Повний текст джерелаАнотація:
The aims of the research work described in this thesis were to use computational fluid dynamics (CFD) to investigate the factors affecting the performance of a multi-stage downdraught evaporative cooling device for low-energy cooling of buildings developed from a novel prototype device described by Erell et al. (2008) and Pearlmutter et al. (2008); and to model and explore the performance of the device when integrated within a hypothetical, but representative, building in a hot dry climate. The research work was carried out with initial objectives of: understanding and modelling water spray evaporation using CFD methods; verifying the CFD model of water spray evaporation using published experimental data; modelling and examining the spray characteristics of the nozzles used in the work by Erell et al. and Pearlmutter et al.; creating a detail model of the prototype multi-stage downdraught evaporative cooling device described by Erell et al. and Pearlmutter et al.; carrying out a series of CFD simulations of the prototype device under wind-driven operation with and without water sprays and comparing the results obtained with available experimental data. Following completion of these initial studies, a detailed investigation of the factors affecting the performance of a multi-stage cooling device derived from the prototype device was carried out. This involved carrying out simulations: to select the most effective wind catcher geometry; to optimize the number and arrangement of water spray nozzles; and to select a range of geometrical parameters. Following completion of these additional studies a model of a two-floor hypothetical building with an integrated multi-stage downdraught evaporative cooling device of optimum geometry and a wind catcher was created, and simulations to investigate the performance under varying wind speeds and environmental conditions were carried out. All simulations were carried out using ANSYS CFX, versions 12.0, or 12.1 or 13.0. The results obtained indicated that comfortable conditions within the cooled space could be achieved over almost all of the range the wind speeds and environmental conditions studied. Some recommendations for future work are given.
18
Eichas, Kyle R. "Promoting self-construction and self-discovery processes : a multi-stage longitudinal comparative design stage II evaluation of the changing lives program." FIU Digital Commons, 2008. http://digitalcommons.fiu.edu/etd/3121.
Повний текст джерелаАнотація:
This study evaluated the Changing Lives Program intervention in promoting emotion-focused identity exploration (i.e. feelings of personal expressiveness; PE), cognitively-focused identity exploration (i.e. informational identity processing style; INFO), and identity resolution (IDR). Using structural equation modeling techniques, this study found that participation in the CLP was associated with statistically significant positive change in PE (path = .482, p < .043), marginally significant change in INFO (path = .132, p < .083), and significantly moderated change in IDR (IDR X ETHNICITY path = .344, p < .053). Increase in PE scores were also found to be significantly associated with increases in INFO scores (path =.748, p < .001) and marginally significantly associated with increases in IDR scores (path = .379, p < .068). Findings suggest that the CLP intervention may promote increases in cognitively-focused identity exploration and protect against declines in emotion-focused identity exploration.
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Rizvi, Syed Zia Abbas. "Production and inventory control of a multi-item multi-stage manufacturing system : simulation modeling, capacitated shipment planning and Kanban design." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/55232.
Повний текст джерелаАнотація:
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2009.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 101).
The project work presented in this thesis has proposed solutions related to the control of production and work-in-process inventory in a multi-item multi-stage manufacturing system. A suitable base-stock inventory control policy is recommended to ensure that the desired service levels are maintained between production stages and for the final customers. Concept of coupling the production lines though coupling-stock under suitable assumptions is then introduced to reduce the stock levels at certain consecutive production stages. A framework for demand seasonality and characteristic analysis is also established to enable the inventory control policy to respond to seasonal variations. Monte Carlo simulation was performed on a model of chain of production stages controlled under base-stock policy for the verification of results and to study the effects of stock-outs on base-stock levels. The results of simulation study showed that overall system performance is satisfactory and desired service levels were achieved. Simulation work was also carried out to validate the line coupling concept and its performance under certain conditions. A novel Kanban based visual management system design, which is aligned with the requirements of inventory control policy, along with the material transfer batch sizes between production stages is proposed to facilitate the implementation of inventory control policy. Furthermore, capacitated shipment planning approach is proposed and implemented in form of a spreadsheet-based interface to aid planning personnel in shipment planning under the constraints provided by the inventory control policy.
by Syed Zia Abbas Rizvi.
M.Eng.
20
Roy, Subir. "An approach to optimal design of multi-stage metal forming processes by micro genetic algorithms /." The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487861396022891.
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Li, Beidi. "Use of Building Energy Simulation Software in Early-Stage of Design Process." Thesis, KTH, Byggvetenskap, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-217902.
Повний текст джерелаАнотація:
In traditional planning process, energy analysts work on finalized architectural designs and have limited capability to amend inefficient energy features such as high aspect ratio. Energy efficiency being a major part of sustainable design, the need for performance-oriented design tools has become imminent. There is a wide range of energy simulation tools across the world. Crawley et al. (2005) proposes a plain comparison of the most common ones based on vendor-supplied information. The present report aims to identify simulation tools that can help architects making energy-efficient design decisions in early stage of building process and the most suitable programs will be tested on a standard case in Stockholm area with respect to their architecture, functionalities, usability and limitations.
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Zapalo, Peter P. "Design and validation of a multi-stage skating-specific test to predict aerobic power in competitive figure skaters." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0018/MQ48056.pdf.
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Dadan-Garba, Aliyu. "Investigation of anthropogenic water contamination and the design of a multi-stage filtration system for point of use application." Thesis, University of Surrey, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.658627.
Повний текст джерелаАнотація:
This research study investigated the anthropogenic contamination of water sources (surface, groundwater and tap water) in Kaduna metropolis, Nigeria. The water sources were identified and delineated on the basis of land use; domestic, commercial, agricultural, industrial and refinery areas. The water sampling programme was undertaken from 2009 to 2011 in accordance with the Standard Methods (APHA, 2005) covering hand dug wells, streams and rivers. Water samples were analysed for various water quality parameters, including pH, temperature, electrical conductivity, total dissolved solids, dissolved oxygen, biochemical oxygen demand and faecal coliforms. Also analysed were trace element levels by inductively coupled plasma mass spectrometry (lCP-MS). The results were compared with drinking water guideline legislations of relevant agencies and governments. Groundwater samples were found to be most contaminated with microbiological coliforms from the improper disposal of domestic sewage and the proximity of these water wells to the sewage points. Surface water (streams and rivers) were found to be more chemically contaminated than groundwater due to urban run-off and the discharge of solid wastes. In general, trace elements (As, Mo, Se, Cd, Sb & Pb) levels were found to be generally below the guideline limits of the regulatory bodies with the exception of Mn near textile industries; Ni near vehicle assembly plant and Cu & Zn were higher in tap water. The detennination of anthropogenic water contamination led to the selection and design of a multi stage filtration system to treat water at point of use for residents without access to potable water. Experiments at pilot scale were undertaken using raw and chemically modified lake water. The results showed that this basic filtration system was capable of reducing the turbidity and faecal coliform levels of the lake water. Furthermore, AI, Mn and Fe levels were reduced. The pilot filtration system was scaled-up for field application in Kaduna, Nigeria (December 2012 to March 2013). Five filtration plants were established to treat raw water from domestic and commercial ground/surface waters, and industrial surface water of the Nigerian study area. The results showed that it is not capable of providing water that is completely potable but can produce water that is, to a great extent treated for turbidity and bacterial contamination better than the water available for domestic use by people in low income bracket and those in emergency situations such as aftermath of natural disasters e.g. Typhoon Haiyan.
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Taslim, Cenny. "Multi-Stage Experimental Planning and Analysis for Forward-Inverse Regression Applied to Genetic Network Modeling." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1213286112.
Повний текст джерела
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Zhang, Christina Yan. "The use of massively multiplayer online games to augment early-stage design process in construction." Thesis, Loughborough University, 2012. https://dspace.lboro.ac.uk/2134/9924.
Повний текст джерелаАнотація:
Traditional 2-D contour models, Physical Models, Computer-Aided Architectural Design (CAD), Virtual Reality models, Google SketchUp, and Building Information Modelling (BIM) have all greatly enhanced the design process by enabling designers to visualise buildings and the space within them prior to their construction. A recent development is Massively Multiplayer Online Games (MMOG) such as Second Life (SL). These offer users the opportunity to interact with other participants in real time, and so offer an excellent opportunity to experience the environment, layout and form of virtual buildings. However, the effectiveness of such applications to some extent depends upon how realistic the interactions of those using virtual spaces are in relation to interactions within the real world. This research examines the potential of this technology for enhancing and informing the early stage building design process. Initially, the tools currently used by architects at early stages of the RIBA Plan of Work were evaluated through interviewing architects. Then, the advantages of using MMOG over current tools at early-stage design were evaluated through interviews in SL. A virtual model was developed to examine how realistic the visualisation and interaction between end-users in an MMOG was. This was used to propose and validate guidance to incorporating MMOG into the early stages of the RIBA Plan of Work. It revealed that the virtual model created, the validated guidance and a successful example combining 2D sketches, Google SketchUp and MMOG at early-stage design can be used to guide architects to manage the complex decision making process in a simple, easy, cost-effective way, while effectively engaging both professional and non-professional stakeholders.
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Müller, Patrik. "Vícestupňové čerpadlo s protiběžnými koly." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-318819.
Повний текст джерелаАнотація:
The main objective of this thesis is to design blades for the axial pump with two counter-rotating rotors for design point. Then compare results with the standard concept with one runner and guide blades.
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Cheung, Kai Tak (Franco). "Development and Testing of a Method for Forecasting Prices of Multi-Storey Buildings during the Early Design Stage: the Storey Enclosure Method Revisited." Thesis, Queensland University of Technology, 2005. https://eprints.qut.edu.au/16046/1/Franko_Cheung_Thesis.pdf.
Повний текст джерелаАнотація:
Although design decisions that are made in the preliminary design stages of a building are more cost sensitive than those that are made at later stages, previous research suggests that they result in only a slight improvement in the accuracy of building price forecasts as the design develops. However, established conventional forecasting methods lack measures of their own performance, which has inhibited the development of simpler early-stage techniques.
One early-stage price forecasting model, the Storey Enclosure Method, which was developed by James in 1954, uses the basic physical measurements of buildings to estimate building prices. Although James' Storey Enclosure Model (JSEM) is not widely used in practice, it has been proved empirically, if rather crudely, to be a better model than other commonly used models. This research aims firstly to advance JSEM by using regression techniques and secondly to develop an objective approach for the assessment of model performance.
To accomplish the first research aim, this research uses data from 148 completed Hong Kong projects for four types of building: offices, private housing, nursing homes, and primary and secondary schools. Sophisticated features of the modelling exercise include the use of leave-one-out cross validation to simulate the way in which forecasts are produced in practice and a dual stepwise selection strategy that enhances the chance of identifying the best model. Two types ofregressed models from different candidate sets, the Regressed Model for James' Storey Enclosure Method (RJSEM) and Regressed Model for Advanced Storey Enclosure Method (RASEM), are developed accordingly.
In considering the RJSEM, RASEM, and the most commonly used alternative early stage floor area and cube models, all of the models except JSEM are found to be unbiased. The RJSEM and RASEM models are also examined for their consistency using a structured approach that involves the use of both parametric and non-parametric inference tests. This shows that although the RASEMs for different building types are generally more consistent, they are not significantly better than the other models. Finally, the combination of the forecasts that are generated from different models to capture the different aspects of information from the models is suggested as an alternative strategy for improving forecasting performance.
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Cheung, Kai Tak (Franco). "Development and Testing of a Method for Forecasting Prices of Multi-Storey Buildings during the Early Design Stage: the Storey Enclosure Method Revisited." Queensland University of Technology, 2005. http://eprints.qut.edu.au/16046/.
Повний текст джерелаАнотація:
Although design decisions that are made in the preliminary design stages of a building are more cost sensitive than those that are made at later stages, previous research suggests that they result in only a slight improvement in the accuracy of building price forecasts as the design develops. However, established conventional forecasting methods lack measures of their own performance, which has inhibited the development of simpler early-stage techniques. One early-stage price forecasting model, the Storey Enclosure Method, which was developed by James in 1954, uses the basic physical measurements of buildings to estimate building prices. Although James' Storey Enclosure Model (JSEM) is not widely used in practice, it has been proved empirically, if rather crudely, to be a better model than other commonly used models. This research aims firstly to advance JSEM by using regression techniques and secondly to develop an objective approach for the assessment of model performance. To accomplish the first research aim, this research uses data from 148 completed Hong Kong projects for four types of building: offices, private housing, nursing homes, and primary and secondary schools. Sophisticated features of the modelling exercise include the use of leave-one-out cross validation to simulate the way in which forecasts are produced in practice and a dual stepwise selection strategy that enhances the chance of identifying the best model. Two types ofregressed models from different candidate sets, the Regressed Model for James' Storey Enclosure Method (RJSEM) and Regressed Model for Advanced Storey Enclosure Method (RASEM), are developed accordingly. In considering the RJSEM, RASEM, and the most commonly used alternative early stage floor area and cube models, all of the models except JSEM are found to be unbiased. The RJSEM and RASEM models are also examined for their consistency using a structured approach that involves the use of both parametric and non-parametric inference tests. This shows that although the RASEMs for different building types are generally more consistent, they are not significantly better than the other models. Finally, the combination of the forecasts that are generated from different models to capture the different aspects of information from the models is suggested as an alternative strategy for improving forecasting performance.
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Wen, Hao. "High-Efficiency and High-Frequency Resonant Converter Based Single-Stage Soft-Switching Isolated Inverter Design and Optimization with Gallium-Nitride (GaN)." Diss., Virginia Tech, 2021. http://hdl.handle.net/10919/105134.
Повний текст джерелаАнотація:
Isolated inverter can provide galvanic isolation which is necessary for some applications with safety regulations. Traditionally, a two-stage configuration is widely applied with isolated dc-dc stage and a sinusoidal pulse-width-modulated (SPWM) dc-ac stage. However, this two-stage configuration suffers from more components count, more complex control and tend to have lower efficiency and lower power density. Meanwhile, a large dc bus capacitor is needed to attenuate the double line frequency from SPWM for two-stage configuration. Therefore, the single-stage approach including an isolated dc-rectified sine stage and a line frequency unfolder is preferable. Since the unfolder circuit is at line frequency being almost lossless, the isolated dc-rectified sine stage becomes critical.
However, the relevant research for the single-stage isolated inverter is limited. People either utilize PWM based converter as dc-rectified sine stage with duty cycle adjustment or apply SRC or LLC resonant converter for better soft switching characteristics. For PWM based converter, hard switching restricts the overall inverter efficiency, while for SRC/LLC, enough wide voltage gain range and full range ZVS are the major issues.
This dissertation aims to provide solutions for a high-efficiency, high-frequency resonant converter based single-stage soft-switching isolated inverter design. The LLC and LCLCL resonant converters are applied as the isolated dc-rectified sine stage with variable frequency modulation (VFM). Therefore, the rectified sine wave generation consists of many dc-dc conversion with different switching frequencies and an efficient dc-rectified sine stage design needs each dc-dc conversion to be with high efficiency.
This dissertation will first propose the optimization methods for LLC converter dc-dc conversion. ZVS models are derived to ensure fully ZVS performance for primary side GaN devices. As a large part in loss breakdown, the optimization for transformer is essential. The LLC converter can achieve above 99% efficiency with proposed optimization approach. Moreover, the channel turn-off energy model is presented for a more accurate loss analysis.
With all the design and optimization considerations, a MHz LLC converter based isolated inverter is designed and a hybrid modulation method is proposed, which includes full bridge (FB) VFM for output high line region and half bridge (HB) VFM for output low line region. By changing from FB to HB, the output voltage gain is reduced to half to have a wider voltage gain range. However, the total harmonic distortion (THD) of output voltage at light load will be impacted since the voltage gain will be higher with lighter load at the maximum switching frequency.
A MHz LCLCL converter based isolated inverter is proposed for a better output voltage THD at light load conditions. The paralleled LC inside the LCLCL resonant tank can naturally create a zero voltage gain point at their resonant frequency, which shows superior performance for rectified sine wave generation. Besides the better THD performance, the LCLCL converter based isolated inverter also features for easier control, better ZVS performance and narrower switching frequency range.
Meanwhile, the LCLCL based inverter topology has bi-directional power flow capability as well. With variable frequency modulation for ac-dc, this topology is still a single-stage solution compared to the traditional two-stage solution including PFC + LLC configuration.Doctor of Philosophy
Inverters can convert dc voltage to ac voltage and typically people use two-stage approach with isolated dc-dc stage and dc-ac stage. However, this two-stage configuration suffers from more components count, more complex control and tend to have lower efficiency and lower power density. Therefore, the single-stage solution with dc-rectified sine wave stage and a line frequency unfolder becomes appealing. The unfolder circuit is to unfold the rectifier sine wave to an ac sine wave at the output. Since the unfolder is at line frequency and can be considered lossless, the key design is for the dc-rectified sine stage. The resonant converter featured for soft switching seems to be a good candidate. However, the inverter needs soft switching for the whole range and an enough wide voltage gain, which makes the design difficult, especially the target is high efficiency for the overall inverter. This dissertation aims to provide solutions for a high-efficiency, high-frequency resonant converter based single-stage soft-switching isolated inverter design. The LLC and LCLCL resonant converters are applied as the isolated dc-rectified sine stage with variable frequency modulation (VFM). Therefore, the rectified sine wave generation consists of many dc-dc conversion with different switching frequencies and an efficient dc-rectified sine stage design needs each dc-dc conversion to be with high efficiency. The design considerations and optimization methods for the LLC dc-dc conversion are firstly investigated. Based on these approaches, a MHz LLC converter based isolated inverter is designed with proposed hybrid modulation method. To further improve the light load performance, a MHz LCLCL converter based isolated inverter topology is proposed. The paralleled LC inside the LCLCL resonant tank can naturally create a zero voltage gain point which shows superior characteristics for rectified sine wave generation. Moreover, the LCLCL resonant converter based topology has bi-directional capability as well so it can work well for ac voltage to dc voltage conversion.
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Prueter, Phillip Edward. "A Study of the Mechanical Design and Gear Tooth Root Strains in Flexible Pin, Multi-Stage, Planetary Wind Turbine Gear Trains Using Three Dimensional Finite Element/Contact Mechanics Models and Experiments." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1313372765.
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Havlásek, Martin. "Zvyšování účinnosti vakuového odpařování." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-232144.
Повний текст джерелаАнотація:
This thesis is focused on experimental work in the domain of vacuum evaporation efficiency improvement. The first part introduces theory of liquids evaporation and its influencing factors, then multi-stage flash distillation technology. The next part of theory is an overview of other technologies used for desalination of sea water and introduction to the design of experiments. In the practical part are selected factors affecting efficiency of device and experiment plan is designed for them. When the experiment is done, optimal operating conditions of technology are designed on basis of analysis.
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Ostiguy, Matthew James. "Experiment and Simulation of the Acoustic Signature of Fatigued-Cracked Gears in a Two-Stage Gearbox." DigitalCommons@CalPoly, 2014. https://digitalcommons.calpoly.edu/theses/1328.
Повний текст джерелаАнотація:
This thesis focuses on the development of a health monitoring system for gearbox transmissions. This was accomplished by developing and understanding a two-stage gearbox computer model that emulates an actual gearbox test rig. The computer model contains actual gearbox geometry, flexible shafts, bearings, gear contact forces, input motor torque, output brake torque, and realistic gearbox imbalance. The gear contact force of each gear stage and the input bearing translational acceleration were the main outputs compared between a healthy gearbox and damaged gearbox computer model. The damage of focus was a fatigue crack on the input pinion gear. A sideband energy ratio comparison yielded the computer simulation accurately modeled the difference between a healthy and damaged gearbox. The next step in this study involved the development of a repeatable procedure to initiate and propagate a fatigue crack at the tooth root in an actual spur gear. A damaged spur gear allows for a future comparison of an actual healthy and damaged gearbox system in the lab. A custom fatigue fixture was designed and manufactured for a Martin S1224BS 1 spur gear. The fatigue crack was initiated by position control fatigue testing which deflects the gear tooth a set amplitude for a number of cycles. Over the length of the test, the load that the tooth can withstand in bending decreases as damage begins to occur. Once the max load on the gear has dropped by a significant percentage (5-15%) a crack has initiated and begun to propagate across the tooth face. The use of a scanning electron microscope confirmed the presence a fatigue crack.
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Sommer, Andrew Patrick. "VIBRATION-BASED HEALTH MONITORING OF MULTIPLE-STAGE GEAR TRAIN AND DIFFERENTIAL PLANETARY TRANSMISSION INVOLVING TEETH DAMAGE AND BACKLASH NONLINEARITY." DigitalCommons@CalPoly, 2011. https://digitalcommons.calpoly.edu/theses/631.
Повний текст джерелаАнотація:
The objective of this thesis is to develop vibration-based fault detection strategies for on-line condition monitoring of gear transmission systems. The study divides the thesis into three sections. First of all, the local stresses created by a root fatigue crack on a pinion spur gear are analyzed using a quasi-static finite element model and non-linear contact mechanics simulation. Backlash between gear teeth which is essential to provide better lubrication on tooth surfaces and to eliminate interference is included as a defect and a necessary part of transmission design. The second section is dedicated to fixed axis power trains. Torsional vibration is shown to cause teeth separation and double-sided impacts in unloaded and lightly loaded gearing drives. The transient and steady-state dynamic loading on teeth within a two stage crank-slider mechanism arising from backlash and geometric manufacturing errors is investigated by utilizing a non-linear multi-body dynamics software model. The multi-body model drastically reduces the computation time required by finite element methods to simulate realistic operation. The gears are considered rigid with elastic contact surfaces defined by a penalty based non-linear contact formulation. The third section examines a practical differential planetary transmission which combines two inputs and one output. Planetary gears with only backlash errors are compared to those containing both backlash and tooth defects under different kinematic and loading conditions. Fast Fourier Transform (FFT) analysis shows the appearance of side band modulations and harmonics of the gear mesh frequency. A joint time-frequency analysis (JTFA) during start-up reveals the unique vibration patterns for fixed axis gear train and differential planetary gear, respectively, when the contact forces increase during acceleration.
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Vondra, Marek. "Zařízení pro zahušťování odpadní vody z bioplynových stanic." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-295728.
Повний текст джерелаАнотація:
This dissertation thesis deals with the development of technology which could tackle two major issues related to biogas plants. These issues concern the insufficient use of waste heat from biogas combustion and its subsequent processing. It also concerns the use of the fermentation residues which are formed in large quantities and whose use is restricted by law. Based on a literary search of separation methods, a vacuum evaporator was selected as the most suitable technology. Its advantages include its simple construction, operational reliability and robustness, low costs of thickening medium pre-treatment, potential for a quick commercial application and, especially, the chance to use a low-potential waste heat. A primary purpose of this technological unit is the reduction in the volume of fermentation residues. Other benefits include the efficient use of waste heat from a biogas plant, which would otherwise be wasted. Evaporators with a low consumption of electrical energy (which is a main product of a biogas plant) seem to be the best option for applications in the biogas plants. Three of these technologies were subjected to a more thorough analysis, which included the development of computational models and their quantification for conditions in a sample biogas plant. A one-stage evaporator with a forced circulation (680 – 712 kWhth/m3, 25.9 – 30.5 kWhel/m3) was evaluated as the least suitable option in terms of energy demands. The energy intensity of a three-stage evaporator with a falling film (241 – 319 kWhth/m3, 12.0 – 23.6 kWhel/m3) and a nine-stage flash evaporator (236 – 268 kWhth/m3, 13.6 – 18.4 kWhel/m3) is significantly lower. A multi-stage flash evaporator (MSF) was then chosen for development and will form the central focus of this thesis. The reasons for the choice are as follows: the low requirements on the heat transfer surface, good operational experience in the field of desalination, its simple construction, modularity and evaporation outside the heat transfer surface. A thorough technical-economic evaluation was also performed on the integration of the evaporator into the biogas plant. The main part of the work included the experimental development of a MSF evaporator prototype. The main objective of this development was to achieve a stable flow rate of the thickening liquid digestate fraction and the continuous formation of the distillate. This was not an easy objective to achieve, especially due to the properties of the liquid digestate, which has a non-newtonian characteristic and increased density and viscosity compared to water. The tendency of the liquid digestate to form foam was also the subject of analysis. The development of the evaporator and first successful operational test are described in the thesis in detail. This required the use of an anti-foaming product. A fully-developed prototype of the MSF evaporator allowed us to achieve continuous operation with a distillate production, reaching from 5 to 10 kg/h at a liquid digestate flow rate of 0.4–0.5 m3/h. The main drawback of this technology is the pollution of the distillate with ammonia nitrogen, and it is for this reason that the basic procedures of its subsequent elimination was selected for further analysis.
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Pascual, Iserte Antonio. "Channel state Information and joint transmitter-receiver design in multi-antenna systems." Doctoral thesis, Universitat Politècnica de Catalunya, 2005. http://hdl.handle.net/10803/6890.
Повний текст джерелаАнотація:
Esta tesis aborda el problema del diseño de sistemas multiantena, donde el caso más general corresponde a un canal multi-input-multi-output (MIMO) con un transmisor y un receptor con más de una antena. La ventaja de estos sistemas es que ofrecen un rendimiento mucho mejor que los de una única antena, tanto en términos de calidad en la transmisión como en capacidad entendida como número de usuarios a los que se les puede prestar servicio simultáneamente.El objetivo es diseñar conjuntamente el transmisor y el receptor, lo que depende directamente de la calidad y la cantidad de información del canal de la que se dispone. En esta tesis se analiza el impacto de dicha información en el diseño.
Primero se ha estudiado un sistema MIMO de un único usuario usando la modulación orthogonal frequency division multiplexing (OFDM) y asumiendo un conocimiento perfecto del canal en ambos extremos. La arquitectura propuesta se basa en conformación conjunta por portadora, calculándose los conformadores óptimos y proponiéndose diversas estrategias de distribución de potencia entre las portadoras con una baja complejidad. Se han analizado también las relaciones asintóticas de estas distribuciones de potencia con otras soluciones clásicas con mayor coste.
El diseño anterior se ha extendido a sistemas MIMO multiusuario, donde todos los terminales en el escenario tienen más de una antena y la información del canal es perfecta. El objetivo es la minimización de la potencia total transmitida sujeto a restricciones de tasa de error máxima para cada enlace. El problema matemático obtenido es no convexo, por lo que estrategias clásicas basadas en algoritmos de gradiente o de optimización sucesiva pueden llevar a soluciones subóptimas. Como posible alternativa se ha propuesto la aplicación de simulated annealing, una potente herramienta heurística y estocástica que permite hallar el diseño global óptimo incluso cuando el problema es no convexo.
Los errores en la información de canal disponible pueden empeorar el rendimiento del sistema si éstos no se tienen en cuenta explícitamente durante el diseño. La degradación del sistema MIMO-OFDM de un único usuario se ha estudiado en esta situación, obteniendo una expresión analítica de una cota superior de la máxima degradación relativa de la relación señal a ruido más interferencia.
El rendimiento se puede mejorar usando técnicas robustas que tengan en cuenta la presencia de dichos errores. Existen dos aproximaciones clásicas: las Bayesianas y las maximin. En las soluciones Bayesianas el problema se formula estadísticamente, donde el objetivo es optimizar el valor medio de una función de rendimiento promediada sobre la estadística del canal real condicionado a su estimación. Por otro lado, los diseños maximin se caracterizan por optimizar el peor rendimiento para cualquier posible error en la información del canal dentro de una cierta región de incertidumbre que modela el conocimiento imperfecto del mismo.
Se han mostrado dos ejemplos de diseños Bayesianos. Primero, una distribución de potencia en un sistema OFDM de una única antena que minimiza el valor medio de una cota superior de la tasa de error, y después un diseño de un transmisor multiantena con un banco de filtros que maximiza la relación señal a ruido media (SNR) o minimiza el error cuadrático medio.
Finalmente, se ha obtenido el diseño robusto maximin de un sistema MIMO de un único usuario donde en el transmisor se combinan un código bloque ortogonal espacio-tiempo, una distribución de potencia y un banco de conformadores correspondientes a los modos espaciales del canal estimado. La distribución de potencia se ha diseñado acorde a una región de incertidumbre para el error en la estimación de canal de manera que se maximiza la peor SNR en dicha región. Posteriormente, este diseño se ha extendido al caso de modulaciones adaptativas y multiportadora, mostrando que el rendimiento es mejor que para los códigos bloque otrogonales y la conformación no robusta.
This Ph.D. dissertation addresses the design of multi-antenna systems, where the most general case corresponds to a transmitter and a receiver with more than one antenna, i.e., a multiple-input-multiple-output (MIMO) channel. The main advantage is that they can provide a much better performance than single-antenna systems, both in terms of transmission quality and system capacity, i.e., number of users that can be served simultaneously.
The objective is to carry out a joint transmitter-receiver design, which depends directly on the quantity and the quality of the available channel state information (CSI). In this dissertation, the impact of the CSI on the design has been analyzed.
First, a single-user MIMO communication system has been designed assuming the use of the orthogonal frequency division multiplexing (OFDM) modulation and according to a perfect CSI at both sides. The proposed architecture is based on a joint beamforming approach per carrier. The optimum beamvectors have been calculated and several power allocation strategies among the subcarriers have been derived. These power allocation solutions have been shown to be asymptotically related to other classical designs but with a much lower computational load.
The previous design has been extended to multi-user communications, where the multi-antenna terminals in the scenario have a perfect CSI. The objective is the minimization of the total transmit power subject to maximum bit error rate (BER) constraints for each link. The mathematical optimization problem is non-convex and, therefore, classical solutions based on gradient search or alternate & maximize schemes may find a local suboptimum design. As a possible solution, the application of the simulated annealing technique has been proposed, a powerful stochastic optimization tool able to find the global optimum design even when the problem is non-convex.
The errors in the available CSI may decrease importantly the system performance if they are not taken into account explicitly in the design. This degradation has been studied for the single-user MIMO-OFDM system. An analytical expression of an upper-bound on the maximum relative signal to noise plus interference ratio degradation has been found.
The system performance can be improved when exploiting an imperfect CSI by using adequate robustness strategies. Two robust approaches have been proposed: the Bayesian and the maximin solutions. The Bayesian approach is a full statistical solution that optimizes the mean value of the performance function averaged over the statistics of the actual channel and the errors in the CSI. On the other hand, the maximin approach provides a design that optimizes the worst system performance for any possible error in a predefined uncertainty region.
Two simple examples of Bayesian designs have been provided. First, a power allocation has been derived for an OFDM system with one transmit and one receive antenna minimizing the mean value of an upper-bound on the BER. Afterwards, a design of a multi-antenna transmitter with a bank of filters and a single-antenna receiver has been proposed, whose objective is either the maximization of the mean signal to noise ratio (SNR) or the minimization of the mean square error.
Finally, a robust maximin design has been proposed for a single-user MIMO system, in which the transmitter is based on the combination of an orthogonal space time block code (OSTBC), a power allocation stage, and a set of beamformers coupling the transmission through the estimated channel eigenmodes. The power allocation has been found according to a channel estimate and an uncertainty region for the error in this estimate, so that the worst SNR for any error in the uncertainty region is maximized. This design has been then extended and applied to adaptive modulation schemes and multicarrier modulations, showing that the performance is much better than that achieved by a pure OSTBC solution or a non-robust beamforming scheme.
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Payaró, Llisterri Miquel. "IMPACT OF CHANNEL STATE INFORMATION ON THE ANALYSIS AND DESIGN OF MULTIANTENNA COMMUNICATION SYSTEMS." Doctoral thesis, Universitat Politècnica de Catalunya, 2007. http://hdl.handle.net/10803/6900.
Повний текст джерелаАнотація:
Al llarg d'aquesta última dècada, s'ha produit un creixement constant en la demanda d'elevades taxes de transmissió de dades que han de suportar les aplicacions sobre comunicacions sense fils. Entre les diferents solucions ideades per la comunitat recercaire per tal de fer front a aquesta nova demanda, la utilització de múltiples antenes s'erigeix com una de les millors candidates degut al fet que proporciona simultàniament una millora en les taxes de transmissió i en la fiabilitat en la recepció de les dades. L'ús d'antenes múltiples en un dels extrems de la comunicació data de la dècada dels seixanta, nogensmenys ha estat en aquests últims anys quan s'ha pogut provar, tant en els camps teòric com pràctic, tot el potencial que possibilita la presència de múltiples antenes en ambdós extrems de la comunicació.El disseny adequat de sistemes de comunicació amb múltiples antenes per satisfer aquesta demanda no només depèn de la funció de mèrit (o de la mètrica de rendiment) escollida, sinó que també es veu afectat per la quantitat i la qualitat de la informació de l'estat del canal que es troba disponible als extrems de la comunicació. Aquesta tesi tracta sobre l'anàlisi i el disseny d'arquitectures per sistemes de comunicació amb múltiples antenes i amb diferents nivells de quantitat i qualitat de la informació de l'estat del canal. La secció d'anàlisi es centra en l'estudi de la capacitat i les taxes de transmissió assolibles per aquests tipus de sistemes de comunicació i la part de disseny queda més encarada a la síntesi de sistemes de comunicació pràctics amb l'objectiu de maximitzar el rendiment d'acord amb la mètrica de rendiment escollida.
Primerament, l'atenció es centra en sistemes de comunicació amb múltiples antenes per a un únic usuari amb informació perfecte de l'estat del canal, que suposa una idealització dels sistemes pràctics que s'empren en la realitat. En aquest context, es revisen resultats de capacitat que són ben coneguts, i es caracteritza, a més, un transmissor lineal dissenyat per tal de maximitzar la fiabilitat de l'enllaç sense fils amb múltiples antenes. Addicionalment, s'apunten una sèrie d'analogies entre el disseny del transmissor lineal òptim i la teoria de construcció de constel.lacions de símbols.
En segon lloc, es roman en un escenari de comunicacions amb un únic usuari i es considera el cas on la informació sobre l'estat del canal és incompleta. En aquest cas, es presenta un anàlisi detallat sobre la capacitat a través de les formulacions ergòdica i composta (compound), les quals prenen significat depenent del model utilitzat per caracteritzar el canal. Mentres que en canals ràpidament variants la capacitat ergòdica és la mesura clau de les taxes de transmissió assolibles per qualsevol sistema de comunicació, en canals fixos o de variació lenta, és la capacitat composta, la que mesura la mínima taxa de transmissió assolible de forma sostinguda durant la transmissió del missatge.
Seguidament, es considera el cas on la informació disponible sobre l'estat del canal és imperfecta. Precisament, es discorre sobre un sistema de comunicació pràctic anomentat Precodificador Espacial de Tomlinson i Harashima i s'estudien les seves potencialitats en termes de taxes de transmissió assolibles. Gràcies a l'arquitectura versàtil del Precodificador Espacial de Tomlinson i Harashima l'esmentat estudi es duu a terme tant per escenaris amb un únic usuari com per escenaris amb múltiples usuaris. Per aquests dos casos, es presenta així doncs un disseny que és robust a les incerteses de la informació de l'estat del canal i que té per objectiu minimitzar les pèrdues de taxa de transmissió d'informació.
Finalment, restant en un escenari amb múltiples usuaris amb coneixement imperfecte de l'estat del canal, es presenta una arquitectura de transmissió que és robusta a les incerteses de la informació sobre l'estat del canal disponible tant en el transmisor com en el receptor. La variable per al disseny robust és la distribució de potència entre els símbols d'informació destinats a cada usuari, i el criteri d'optimització és minimitzar la potència total transmesa, tot garantint una determinada qualitat de servei per cada usuari i per qualsevol possible realització del canal que sigui compatible amb la informació disponible sobre l'estat del canal.
During the last decade, there has been a steady increase in the demand of high data rates that are to be supported by wireless communication applications. Among the different solutions that have been proposed by the research community to cope with this new demand, the utilization of multiple antennas arises as one of the best candidates due to the fact that it provides both an increase in reliability and also in information transmission rate. Although the use of multiple antennas at the receiver side dates back from the sixties, the full potential of multiple antennas at both communication ends has been both theoretically and practically recognized in the last few years.
The design of proper multi-antenna communication systems to satisfy the high data rates demand depends not only on the chosen figure of merit or performance metric, but also on the quantity and the quality of the channel state information that is available at the communication ends. In this dissertation we deal with the analysis and design of different architectures for multiple-antenna communication systems for various degrees of quality and quantity of channel state information. The analysis section is devoted to the study of capacity and achievable rates and the part that deals with design is aimed at the synthesis of practical communication systems that maximize a certain performance measure.
Firstly, we focus our attention on multiple antenna single-user communication systems with perfect channel state information, which is an idealization of actual practical systems. In this context, we review well known capacity results and deal with the practical characterization of a linear transmitter that is designed to maximize the reliability of the wireless multi-antenna link. Some analogies between the optimal linear transmitter design and the theory of constellation construction are also pointed out.
Secondly, we stay in a single-user scenario and we move onto the case where the channel state information is incomplete. In this case, a detailed capacity analysis is presented dealing with the ergodic and compound capacity formulations, which arise depending on the model utilized to characterize the channel. While in rapidly varying channels the ergodic capacity is a key measure of the rates that can be achieved by any communication system, in slow varying or fixed channels the compound capacity measures the minimum transmission rate that can be sustained during the transmission of the message.
Next, we shift to the case where the available channel state information is imperfect. Precisely, we deal with a practical communication system called spatial Tomlinson-Harashima precoder and study its achievable rate capabilities. Due to the versatile architecture of the spatial Tomlinson-Harashima precoder we are able to perform the study for the single and multi-user scenarios. For both cases, a design is presented which is robust to the uncertainties of the channel state information and which is aimed at maximizing the transmission rate.
Finally, staying in the multi-user scenario with imperfect channel state information, we present a transmission architecture that is robust to the uncertainties of the side information that is available at both the transmitter and the receiver. The robustness criterion is to minimize the transmitted power while guaranteeing a certain quality of service per user for every possible realization of the channel that is compatible with the available channel state information.
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Brister, Kenneth Eugene. "Multi-objective design optimization using metamodelling techniques and a damage material model." Master's thesis, Mississippi State : Mississippi State University, 2007. http://library.msstate.edu/etd/show.asp?etd=etd-07032007-121410.
Повний текст джерела
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Ghosh, Pranab Kumar. "Design of adaptive multi-arm multi-stage clinical trials." Thesis, 2018. https://hdl.handle.net/2144/27546.
Повний текст джерелаАнотація:
Two-arm group sequential designs have been widely used for over forty years, especially for studies with mortality endpoints. The natural generalization of such designs to trials with multiple treatment arms and a common control (MAMS designs) has, however, been implemented rarely. While the statistical methodology for this extension is clear, the main limitation has been an efficient way to perform the computations. Past efforts were hampered by algorithms that were computationally explosive. With the increasing interest in adaptive designs, platform designs, and other innovative designs that involve multiple comparisons over multiple stages, the importance of MAMS designs is growing rapidly. This dissertation proposes a group sequential approach to design MAMS trial where the test statistic is the maximum of the cumulative score statistics for each
pair-wise comparison, and is evaluated at each analysis time point with respect to efficacy and futility stopping boundaries while maintaining strong control of the family wise error rate (FWER).
In this dissertation we start with a break-through algorithm that will enable us to compute MAMS boundaries rapidly. This algorithm will make MAMS design a practical reality. For designs with efficacy-only boundaries, the computational effort increases linearly with number of arms and number of stages. For designs with both efficacy and futility boundaries the computational effort doubles with successive increases in number of stages. Previous attempts to obtain MAMS boundaries were confined to smaller problems because their computational effort grew exponentially with number of arms and number of stages.
We will next extend our proposed group sequential MAMS design to permit adaptive changes such as dropping treatment arms and increasing the sample size at each interim analysis time point. In order to control the FWER in the presence of these adaptations the early stopping boundaries must be re-computed by invoking the conditional error rate principle and the closed testing principle. This adaptive MAMS design is immensely useful in phase~2 and phase~3 settings.
An alternative to the group sequential approach for MAMS design is the p-value combination approach. This approach has been in place for the last fifteen years.This alternative MAMS approach is based on combining independent p-values from the incremental data of each stage. Strong control of the FWER for this alternative approach is achieved by closed testing. We will compare the operating characteristics of the two approaches both analytically and empirically via simulation. In this dissertation we will demonstrate that the MAMS group sequential approach dominates the traditional p-value combination approach in terms of statistical power.
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Hsu, Wei-Min, and 徐維旻. "Metastability characterization and multi-stage synchronizer design." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/52671516379715739218.
Повний текст джерелаАнотація:
碩士國立清華大學
電機工程學系
102
As the semiconductor technology continue to evolve, large number of transistors can be placed onto a single chip, and thus more complex functions can be implemented. A trend in implementing these complex systems on a chip is to divide the system into subsystems that each subsystem can have different power supply values and different clock frequencies to save power while maintaining the performance. Therefore, data transfer between different clock domains is becoming a norm in today’s large digital IC’s. When the asynchronous data (from different clock domain) arrives within the register’s setup-hold window, the data cannot be reliability received. And thus, it would cause a reliability issue. Synchronizers are usually added in between different domains to minimize data transfer errors. We investigate the synchronizer circuits, which usually consist of multi-stage registers, and characterize the mean-time-between-failure (MTBF) as a function of register’s parameters. We find that the MTBF is dominated by the resolution time constant of the last stage register, no matter how many stages in the synchronizer. Extensive simulations that include corner conditions, post-layout simulation and different technology generations, all confirm this finding. With this finding, we can optimize the synchronizer design to increase MTBF while reducing power consumptions or area. Using TSMC 65LP technology, we have observed 20% power reduction while maintaining similar MTBF or 12% area reduction in a three stage mixed type synchronizer. This principle can be applied to any future synchronizer design.
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CELLAMARE, MATTEO. "Bayesian adaptive designs in multi-arm multi-stage clinical trials." Doctoral thesis, 2016. http://hdl.handle.net/11573/926665.
Повний текст джерелаАнотація:
Clinical trial seek to investigate novel treatments, asses the relative benefits of competing therapies, and establish optimal treatment combinations. Statistical models provide an explicit way to models patients response to a treatment, and make inference about the clinical utility of therapies which guides clinical decision making.
Statistical designs for clinical trials are a formal procedure the aim to maximize the the quality of generated information on the performance of experimental treatment. We explore a particular class of clinical trial design called adaptive design, which allows modifications of one or more specified aspects of the design based on the analysis of information (usually interim data) collected from subjects in the study.
The interest in adaptive design studies arises from the belief that these methods provide a promising new venue in the task of improving drug development compared to conventional non-adaptive statistical methods for the design of clinical experiments. In particular, the approach of adaptive design may increase the likelihood of a patient to be treated with a successful drug and may reduce the uncertainty on the treatment effect. The class of adaptive designs includes adaptive randomization procedures, sample size re-estimations, and sequential or group-sequential interim analysis.
The Bayesian approach is ideally suited to dynamically adapt the design as information arises during a trial. Accumulated data can be used at any time to modify the design of the trial, for instance, by stopping treatment assignments to ineffective arms or unbalancing randomization towards arms with strong evidence of treatment superiority.
In this thesis we focus on two particular sub-classes of Bayesian adaptive designs:Two-stage designs for phase II clinical trials and Response-adaptive randomization designs for multi arm (multi-stage) clinical trial.
A bayesian approach for randomized two-stage designs: Two-stage designs are commonly used in phase II clinical trials, especially in cancer clinical trials. Standard two-stage designs, introduced in Chapter 1, involve one single experimental arm that is compared to a pre-fixed desired level. However, the rate of failure in phase III oncology trials is surprisingly high, partly owing to inadequate phase II studies. Recently, the use of randomized designs in phase II has been increasingly recommended to avoid such limitations.
With the supervision of Prof. Valeria Sambucini, we proposed a randomized version of a Bayesian two-stage design due to Tan and Machin [120] (see Chapter 2 of the thesis). The design selects the two-stage sample sizes by ensuring a large posterior probability that the true response rate of the experimental treatment exceeds that of the standard agent, assuming that the experimental treatment is actually more effective (see Cellamare et al. [35]). This optimistic assumption is realized by fixing virtual outcomes in favor of the experimental arm. However, the design does not account for the uncertainty about future data. Therefore, in Chapter 3 we propose a two-arm two-stage design based on a Bayesian predictive approach (see Cellamare and Sambucini [34]). The idea is to ensure a large probability, expressed in terms of the prior predictive probability of the data, of obtaining a substantial posterior evidence in favour of the experimental treatment under the assumption that it is actually more effective than the standard agent. This design is a randomized version of the two-stage design that has been proposed for single-arm phase II trials by Sambucini [104]. We examine the main features of our novel design as all the parameters involved vary and compare our approach with Jung’s minimax and optimal designs [76]. A potential limitation of the proposed design is that the second stage sample size is determined before observing the first stage data. It can produce some paradoxical situations in which a second stage analysis is performed and additional patients recruited, despite the first stage results were already sufficient to make a final decision. As also suggested by Sambucini[105], we solve this potential problem by using an adaptive version of the Bayesian predictive two-arm two-stage design, in which the
second stage sample size is selected after the first stage results have been observed.
Bayesian response-adaptive design for multi-arm clinical trials: In the planning of a clinical trial, the randomization of patients to either the experimental or control groups is among the most important advances in the history of medical research. Randomization prevents confounding due to latents factors that are correlated with the health outcome and control potential bias of the treatment effect estimates by balancing patients among the treatment arms . However, this property could be sometimes in conflict with ethical assumptions. As experiments on human subjects, clinical trials are characterized by the necessity of finding a balance between collective ethics and individual ethics. When the observation of a failure represents an extreme outcome (i.e. death), the traditional balanced randomization becomes ethically infeasible because of unjustifiable sacrifice of individual ethics. In this context, response-adaptive randomization designs represent a class of designs in which the probability of treatment assignment changes according to patient’s outcome and treating more patients with effective arms compared to fixed randomization. Response-adaptive designs have been widely studied in literature and we provide a review of them in either frequentist or Bayesian framework in Chapter 4. Under the supervision of Prof. Lorenzo Trippa and Prof. Steffen Ventz at the Harvard School of Public Health (and Dana Farber Cancer Institute), we studied the use of Bayesian adaptive randomization (BAR) design in the context of multi-arm clinical trials, in which multiple experimental arms are compared to a common control arm (see Chapter 5). In collaboration with Dr. Carole D. Mitnick and motivated by a multi-arm randomized clinical trial for fluoroquinolone-susceptible multi-drug resistant tuberculosis (MDR-TB)5 called endTb, we build a response-adaptive clinical trial in which the randomization procedure is updated using two preliminary outcomes. The primary study outcome is treatment success after 72 weeks from treatment and two preliminary responses are measured after 8 and 39 weeks (see Cellamare et al. [36]). We compared the proposed design with a standard multi-arm multi-stage design through hypothetical scenarios based on historical data.
Our simulations show how BAR may be more efficient than standard multi-arm multi-stage designs. In particular, when we compare the statistical power of BAR to that of non-adaptive designs under a variety of realistic hypothetical scenarios, we observe that our design requires less patients than non-adaptive designs to ensure a fixed predefine power. Moreover, BAR consistently allocates more participants to effective arm(s). In conclusion, given the objective of evaluating several new therapeutic regimens in a timely fashion, Bayesian response adaptive designs seem more appealing for MDR-TB trials. This approach offers the resource benefit of requiring fewer participants and tends to increase allocation to the effective regimens. Despite the attractive operating characteristics of response adaptive design in the multi arm settings, as shown in the case of the endTb trial, multi-arm clinical trials design presented in literature are generally based on the assumption that all experimental treatments are available at the enrollment of the first patient.
In several real situations, new drugs are rarely at the same stage of development and multi-arm designs may delay in the clinical evaluation of new treatments. These limitations motivate our study of statistical methods for adding new experimental arms after a clinical trial started enrolling patients (see Chapter 6). We consider both balanced and response-adaptive randomization for experimental designs that allow
investigators to add new arms during the course of the trial (see Ventz, Cellamare et al [134]). We discuss their application in the endTb context and we evaluate the proposed experimental designs using a set of realistic simulation scenarios. Our results showed that adding treatments to an ongoing trial yield substantial gain in efficacy compared to multiple independent two-arms trials. The use of standard response-adaptive algorithms can behave poorly in this setting and adjustments of the procedures are required. Moreover, we found that, despite the complexity and the computational burden, response-adaptive algorithms can potentially outperform the balanced algorithm.
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Chen, Chih-Ching, and 陳志清. "Design of Multi-Stage Computing Engine for DSP Applications." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/je3ust.
Повний текст джерелаАнотація:
碩士國立交通大學
電子工程學系 電子研究所
102
In the history of processor development, we observe that Reduced Instruction Set Computer (RISC) processors have already become mainstream for several years. It has a simple and regular datapath and thus facilitates pipelining for high performance. But its hardware utilization is low because it executes one operation in single instruction issued. Then, VLIW processor is presented, that takes advantage of the Instruction Level Parallelism (ILP) to improve hardware utilization. But the register file (RF) area of VLIW processor grows dramatically with the increase of the functional unit number. The cost is considerably high. In recent years, Application-Specific Instruction-set Processor (ASIP) is widely used. It cascades several functional units in costumed order to execute consecutive multiple primitive operations in single cycle to enhance hardware utilization. With limited ports to the centralized register file, the area of the ASIP would not increase exaggeratedly as more additional functional units being allocated. In addition, the cascaded datapath can perform several operations after fetching operands and then write the result back to the register file. It reduces the register file access times, thus achieving the benefit of low-power. However, cascaded functional units increase critical path, it cannot satisfy the requirements of the high clock rate and the fixed cascading order is not suitable for some applications. In this thesis, we propose a multi-stage architecture, which inserts a Stream Interface Unit (SIU) between register file and functional units. The immediate output of functional units can be stored in SIU. The SIU also provides forwarding paths among functional units to modify the execution order within the computing datapath to ensure the hardware utilization for different applications. It also reduces more centralized register file access and implies lower power consumption. For several classical DSP kernels analysis, the hardware utilization of multi-stage is 1.57 times in average higher than 1.00 of RISC. We use the UMC 90nm process to synthesis these architecture. Under same performance, the area of multi-stage is 22% less than VLIW; with higher performance requirement, the area is less than RISC and ASIP. The multi-stage saves about 7%~25% power consumption compared with RISC, VLIW, and ASIP.
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Kuan-HuaChen and 陳冠華. "Preform Design and Analysis of Multi-Stage Tube Hydroforming." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/94945370345581569988.
Повний текст джерелаАнотація:
碩士國立成功大學
機械工程學系碩博士班
101
In this sttuy, an energy criterion was used for evaluating the forming limit of the components with variable cross-section shape in multi-stage tube hydroforming. A preform design rule was developing for assessing the tube with variable cross-section rule. The material fracture data were obtained through material test. The experimental results were compared with forming limit diagram by theoretical analysis. The material fracture conditions agrees well with the prediction by fracture energy criterion. The finite element software LS-DYNA was applied to the cobalt-based superalloy HA-188 for tube hydroforming simulation analysis. By the post-processing analysis, the strain path obtained was nearly linear. With variable cross-section shape as the goal, according to the constant volume, the concept of controlling the section of tube was proposed to design initial tube shape. Then, the formability of different cross-sectional tube shape was assessed. For the die geometry design, first perform the stage planning. Then, the initial result was obtained by the finite element simulation. According to the initial results, the geometrical parameter combination was planned, and then multi-stage simulation result was performed. The tube shapes with the forming limit were observed. The least number of stages was obtained in this study. It effectively reduced number of stages compared with original design in the industry.
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Sun, Li, and 孫立. "Design Procedures of a Multi-Stage Turbo Molecular Pump." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/35548208563072399829.
Повний текст джерелаАнотація:
碩士國立屏東科技大學
機械工程系
93
Turbo molecular pump can provide good air-removal effect in free molecular flow to the ultra high vacuum status. The blade geometries and arrangement have a great influence on pump speed and compression ratio. In this research, direct simulation of Monte Carlo method is adopted to check specific parameters influence on the pump speed and compression ratio. Parameters includes: blade geometries, blade angle, blade thickness, tip of blade diameter, root of blade diameter, blade chord (s/b ratio) and rotational speed. According to the result, the first stage of blade geometries is the most important factor to pump speed. And we can draw curve to select blade geometries. One time we decide the pump speed we also can select the blade geometries we need. The more stage we have, the better compression ratio can reach. The pump rotation speed is very important to pump speed and compression ratio. Increasing rotation speed we can get better pump speed and compression ratio.
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Lin, Yung-Fu, and 林永福. "Design of Multi-Stage Noise Shaping Sigma-Delta Modulator." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/59139793793995169355.
Повний текст джерелаАнотація:
碩士國立成功大學
電機工程學系碩博士班
93
In this thesis, the design methodology of sigma-delta modulator with a novel noise shaping technique is proposed. A fractional-order noise shaping function instead of the commonly used integer-order noise shaping is presented and analyzed. The proposed fractional function is proven to acquire a more efficient noise shaping ability than its integer counterpart. For practical implementation consideration, the order of the noise-shaping function still has to be converted from fractional number to integer. Therefore two numerical approximation functions, Padé approximation and trigonometric approximation, are adopted and proposed respectively. In order to verify the proposed noise-shaping algorithm, a sigma-delta modulator with 2-to-2 MASH architecture is constructed and verified with MATLAB�� simulation tool. At an oversampling ratio of 40, simulation results reveal that a peak SNDR of 95 dB can be achieved with a signal bandwidth of 120 kHz for the sampling frequency of 9.6 MHz.
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許齊麟. "Design and Implementation of Multi-Stage Delta-Sigma Modulators." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/25746314038468982714.
Повний текст джерелаАнотація:
碩士國立臺灣科技大學
電子工程系
90
Oversampled analog-to-digital converters based on delta-sigma ( ) modulation are attractive for VLSI implementation because they are especially tolerant of circuit nonidealities and component mismatch. This thesis presents the design and implementation of a 4th order cascade of lowpass and bandpass multi-stage noise shaping (MASH) modulators. The modulator components include the discrete-time integrator, the 1-bit quantizer, and the clock generator. We employ correlated double sampling (CDS) in the integrator to suppress flicker noise, thermal noise and offset voltages. The operational amplifier of the integrator has very high dc gain in order to suppress leakage quantization noise. Experimental results are presented for a 0.35um CMOS implementation. The experimental prototype modulator achieves a pick signal-to-noise plus distortion ratio (SNDR) of 71dB at a clock rate of 0.8MHz for a 25-kHz signal bandwidth (OSR=16). The noise floor has been suppressed about 80dB below the peak fundamental signal.
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Bandaru, Nishant. "Map based visual design process for multi-stage gear drives." Thesis, 2011. http://hdl.handle.net/2152/ETD-UT-2011-05-3562.
Повний текст джерелаАнотація:
The primary objective of this research is to develop a visual design process for gear trains with multiple stages of reduction and varying configurational architectures. One of the main challenges in the design of such gear trains is in the sizing of the individual gears such that high levels of performance are obtained in spite of constraints due to different gear configurations. Formal design procedures that successfully meet this challenge are developed. A key contribution of this research is the utilization of these design procedures to create sets of three-dimensional design maps. The design procedures help a designer manage more than 20 design parameters in designing for a broad range of gear train requirements (Rated torque capacity, Volume, Weight, Inertia, Responsiveness, Torque Density etc.) while accounting for assembly constraints. Each set of design maps corresponds to a given set of design parameters, some of which are held fixed and some of which are put in the hands of the designer. The latter set of design parameters are termed in this research as design knobs. They can be ‘tuned’ by a designer in order to generate new sets of design maps. The idea is that a designer, using the design information conveyed to him/her graphically through a given set of design maps, is able to then tune the design knobs to generate an updated set of design maps which reflect design solutions that are more desirable in terms of the application requirements. By adjusting the design knobs and looking at updated design maps, a designer is able to quickly assess the effect of his/her design decisions. The end result is that a single designer is empowered with the ability to quickly arrive at a preliminary design of a gear train that satisfies the design requirements. This preliminary design would be a good starting point for more detailed design development.text
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"High-resolution multi-stage time-to-digital converters." 2013. http://library.cuhk.edu.hk/record=b5549748.
Повний текст джерелаАнотація:
在大量的實驗和應用系統中，精確的時間間隔測量是非常重要的。時間-數字轉換器 (TDC) 是一種將兩個輸入脈衝之間的到達時間差轉換成數字編碼的系統。TDC廣泛應用於高能粒子探測器、激光測距儀、數字存儲示波器與及全數字鎖相環中。由於一個TDC的性能對整個系統的性能有極大影響，它吸引了大量的相關研究。現在，基於設計較為簡單，以及分辨率可自然隨工藝而進步，以時延元件方式實現的TDC大大多於以密集模擬電路方式實現的TDC。不過，設計基於時延線的高分辨率TDC時也面對一定挑戰。首先，當TDC的動態範圍增加，時延單元(基本時間測量單元)的數目將呈指數增長，這大大增加了功耗。更糟的是，當時延單元增加時，每個單元中電路噪聲和不匹配引起的線性誤差會沿時延線積累，使TDC的分辨率變差和線性誤差變大。此外，因為制程限制了時延單元最低時延，所以TDC可達到的最低步長亦受此限制。雖然先前有其他研究提出一系列方法超越制程限制以提高時間分辨率，但是它們也有一些不足，例如時延單元數量需要大大增加。
在這篇論文中，我們專注於設計高分辨率的TDC。首先，為了減小在TDC中時延元件的數目，我們提出一個基於威尼爾-並行時延線 (Vernier Parallel Delay Line) 的兩段TDC。我們提出通過串聯兩組分辨率略有差異的平行時延線，以致整個TDC的分辨率比當中任何一組的更好。在這樣的配置下，因為首級時延線同時成為第一級TDC，所以時延元件的數目，相比單級TDC所需的大大降低。此外，VPDL令致兩組時延線的延遲步長接近，從而降低時延單元的時延要求，而同一個時延元件設計也可用在兩級的TDC中，以簡化電路設計。
第二，為了改善VPDL TDC中的線性誤差和偏移問題，我們提出了一個校準方案。這個校準方案是通過改變時延單元成為可調步長單元，以形成一個數字反饋迴路以調整時延/測量TDC中每步的步長，然後根據該信息調整作校準。這個方案中，時延單元既用作調整時延，也作為校準的參考，所以沒有需要從外部輸入/內部產生準確的定時信號。這簡化了校準過程。
第三，我們提出了一個建模方法，以提供一個加快系統設計和功能驗證的方法。這個建模方法把每個時鐘週期輸入的時間差轉換成實數，使在直接建模方法中存在的精度和仿真步長間權衡問題、建模問題和校準邏輯的瞬態仿真問題得以緩解。
最後，我們以UMC 0.13μm CMOS工藝製造了一個6位元的VPDL TDC原型。實驗結果證明這原型實現了5ps的分辨率， 0.6LSB的DNL和0.4LSB的單次測量精度。
Precise time interval measurement is very important in many experimental and applied systems. Time-to-digital converters (TDC) are one type of such measurement systems, which convert the arrival time difference between two input pulses into digital codes. TDCs find various applications in high energy particle detectors, laser range finders, digital storage oscilloscopes, also in all-digital phase lock loops. Since the performance of a TDC greatly affects the performance of the overall system, it attracts a great deal of research efforts.
TDCs based on delay elements are currently dominant compared to other analog-circuit-intensive implementations, because of their design simplicity and that their resolution is inherently enhanced by technology advancement. However, there are challenges on designing high-resolution delay-line-based TDCs. First, when the full scale of the TDC is increased, the number of delay cells (basic time measurement units) have to be increased exponentially, which greatly increases the power consumption. Even worse, when the number of delay cells increases, circuit noises and mismatch-induced nonlinearity from each cell accumulate along the chain and worsen the resolution and linearity of the TDC. Besides, the achievable finest resolution (i.e., the least significant bit, LSB) of the delay-line-based TDCs is limited by the minimum delay of the delay cells, which is process-dependent. Although a number of methods are proposed previously to improve the time resolution beyond the process restriction, there are shortcomings on those architectures, for example, the increase of delay elements needed for generating refined time reference.
In this thesis, we focus on the design of high resolution TDCs. First, to decrease the number of delay elements in the TDC, a two-stage Vernier Parallel Delay Line (VPDL) based TDC is proposed. By cascading two sets of parallel delay lines with slightly difference in resolution, the overall resolution of the TDC is much finer than that of the two sets. By using the first stage delay line as the time reference of the coarse TDC, the number of delay elements is greatly reduced when compared to single stage ones. Besides that, the VPDL makes the delay step sizes similar between stages utilizing Vernier principle, which relaxes the step size requirement of the delay elements, also facilitating design re-use of delay cells among two stages.
Second, to improve the linearity and offset problems in the proposed TDC architecture, a foreground calibration scheme is proposed. By making the delay cells discretely-tunable with equal step, a digital feedback loop can be formed to tune the delay/ measure the step size of each step, then tune the delay of each cell according to the information. The proposed scheme uses the discretely-tunable delay steps to tune the delay, also as the reference of calibration, so no accurate timing signal is needed from internal/external of the TDC. This simplifies the calibration process.
Third, a behavioral modeling approach is proposed to provide a quick way for system design and functional verification. The proposed modeling approach transforms the input time difference at each clock cycle into amplitude, so that the tradeoff between accuracy and simulation step size, problems on modeling and transient simulation of calibration logic that exist in direct modeling approach are alleviated.
To prove the proposed techniques, a 6-bit prototype TDC is fabricated in a 0.13μm CMOS technology, achieving a LSB of 5ps, DNL of 0.6LSB and single-shot precision of 0.4LSB in measurement.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Detailed summary in vernacular field only.
Ko, Chi Tung.
Thesis (Ph.D.)--Chinese University of Hong Kong, 2013.
Includes bibliographical references.
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstracts in also in Chinese.
Abstract --- p.i
摘要 --- p.iv
Acknowledgements --- p.vi
Table of Contents --- p.viii
List of Figures --- p.xii
List of Tables --- p.xvii
Chapter Chapter 1 --- Introduction --- p.1
Chapter 1.1 --- What is TDC and Applications of TDCs --- p.1
Chapter 1.2 --- Objectives of This Research --- p.4
Chapter 1.3 --- Original Contributions --- p.4
Chapter 1.4 --- Organization of Thesis --- p.5
REFERENCES --- p.6
Chapter Chapter 2 --- Fundamentals of TDCs --- p.8
Chapter 2.1 --- Performance Measures --- p.8
Chapter 2.1.1 --- Step Size --- p.8
Chapter 2.1.2 --- Single-shot Precision --- p.9
Chapter 2.1.3 --- Dynamic Range (DR) --- p.9
Chapter 2.1.4 --- Linearity --- p.9
Chapter 2.1.4.1 --- Differential Non-linearity (DNL) --- p.9
Chapter 2.1.4.2 --- Integral Non-linearity (INL) --- p.10
Chapter 2.2 --- Types of TDCs --- p.11
Chapter 2.2.1 --- Analog Method --- p.12
Chapter 2.2.1.1 --- Time-to-amplitude Converter and ADC [2-6], [2-8] --- p.12
Chapter 2.2.2 --- Digital Methods --- p.13
Chapter 2.2.2.1 --- Counters --- p.13
Chapter 2.2.2.2 --- Delay Line --- p.15
Chapter 2.2.2.3 --- Vernier Delay Line --- p.16
Chapter 2.2.2.4 --- Parallel Delay Line --- p.18
Chapter 2.2.2.5 --- Gated-ring Oscillator (GRO) --- p.20
Chapter 2.2.2.6 --- Time Amplifier --- p.21
Chapter 2.3 --- TDC Architecture: Multi-stage vs Single stage TDC --- p.23
Chapter 2.4 --- Summary --- p.25
REFERENCES --- p.26
Chapter Chapter 3 --- Two-stage Vernier Parallel Delay Line (VPDL) TDC with DNL and Offset Calibration --- p.28
Chapter 3.1 --- Proposed TDC Architecture - Vernier Parallel Delay Line (VPDL) --- p.28
Chapter 3.2 --- Advantages and Limitation of VPDL TDC --- p.32
Chapter 3.3 --- Latch buffer --- p.33
Chapter 3.4 --- Offset and DNL Problems of VPDL TDC --- p.34
Chapter 3.4.1 --- Latch Buffer Offset --- p.35
Chapter 3.4.2 --- Latch Offset --- p.37
Chapter 3.4.3 --- Delay Element Offset --- p.39
Chapter 3.5 --- Proposed Offset and DNL Calibration Scheme --- p.42
Chapter 3.5.1 --- Offset Calibration --- p.42
Chapter 3.5.2 --- DNL Calibration --- p.45
Chapter 3.5.3 --- Digital Error Correction --- p.51
REFERENCES --- p.56
Chapter Chapter 4 --- Behavioral Modeling and System Design of TDC --- p.57
Chapter 4.1 --- TDC Behavioral Modeling --- p.57
Chapter 4.1.1 --- Direct Modeling Approach --- p.57
Chapter 4.1.1.1 --- Modeling of Circuit Blocks --- p.58
Chapter 4.1.1.2 --- Limitations of Direct Modeling Approach --- p.60
Chapter 4.1.2 --- Proposed Modeling Approach --- p.61
Chapter 4.1.2.1 --- Transformation of Time Delay --- p.62
Chapter 4.1.2.2 --- Modeling of Different Circuit Blocks --- p.64
Chapter 4.1.2.2.1 --- Delay Cells --- p.64
Chapter 4.1.2.2.2 --- Sampling Latches --- p.66
Chapter 4.1.2.2.3 --- DTC --- p.68
Chapter 4.1.2.2.4 --- Calibration Logic --- p.69
Chapter 4.1.2.3 --- Limitation on the Proposed Approach --- p.72
Chapter 4.2 --- System Overview of TDC --- p.73
Chapter 4.2.1 --- Circuit Block Specifications --- p.77
Chapter 4.2.1.1 --- Calibration Step Sizes --- p.77
Chapter 4.2.1.2 --- Effect of Latch Offset Mismatch --- p.80
Chapter 4.2.1.3 --- Effect of Calibration Step Size Mismatches --- p.86
Chapter 4.3 --- Summary --- p.89
REFERENCES --- p.89
Chapter Chapter 5 --- Circuit Implementation and Simulation Results of the TDC --- p.91
Chapter 5.1.1 --- Sampling Latch --- p.91
Chapter 5.1.2 --- Delay Cells --- p.95
Chapter 5.1.2.1 --- Comparison of Jitter between Differential Pair and Single-ended Delay Line --- p.95
Chapter 5.1.2.2 --- Circuit Design --- p.103
Chapter 5.1.3 --- Residue Routing Switch --- p.107
Chapter 5.2 --- Transistor-level Simulation Results --- p.109
Chapter 5.3 --- Summary --- p.114
REFERENCES --- p.114
Chapter Chapter 6 --- Physical Design and Experimental Results of the TDC --- p.117
Chapter 6.1 --- Physical Design of TDC --- p.117
Chapter 6.1.1 --- Floor Planning --- p.117
Chapter 6.1.2 --- Delay Cell --- p.120
Chapter 6.2 --- Experimental Results --- p.123
Chapter 6.2.1 --- Measurement Setup --- p.123
Chapter 6.2.2 --- Calibration Procedure --- p.126
Chapter 6.2.3 --- Measurement Procedure --- p.130
Chapter 6.2.4 --- Measurement Results --- p.130
Chapter 6.2.4.1 --- TDC1 Measurement --- p.131
Chapter 6.2.4.2 --- Overall TDC Measurement --- p.133
Chapter 6.3 --- Summary --- p.141
REFERENCES --- p.144
Chapter Chapter 7 --- Conclusions and Future Works --- p.146
Chapter 7.1 --- Conclusions --- p.146
Chapter 7.2 --- Future Works --- p.147
48
TSAI, SHENG-DA, and 蔡昇達. "High Gain-Bandwidth and High Slew Rate Multi-Stage Amplifier Design." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/g456p7.
Повний текст джерелаАнотація:
碩士國立雲林科技大學
電子工程系
105
This study presented a High Gain-Bandwidth and High Slew Rate Multi-Stage Amplifier and it significantly improves the DC gain, gain bandwidth and slew rate of traditional recycling folded cascode amplifier. By applying the high-gain and high-speed circuit, high-speed current loop, and shunt current sources, the dc gain, gain bandwidth, and slew rate of the proposed amplifier can be enhanced. The proposed circuit has been implemented and verified using TSMC 0.18um 1P6M CMOS process with 1.8V power supply and 5pF capacitor load. From the simulation results, the proposed amplifier can achieve 105.5dB DC gain, 66.996V⁄μs slew rate, 206.36MHz gain-bandwidth and 53° phase margin. The simulation results also show that the proposed circuit achieve better DC gain, gain-bandwidth, and slew rate comping with the folded cascade amplifier and related works.
49
Hsieh, Chen-Feng, and 謝振豐. "Design and Implement of Integerated Multi-Stage Dynamic Cellular Manufacturing System." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/30880983230621102943.
Повний текст джерелаАнотація:
碩士東海大學
工業工程學系
87
This research will construct four modules to integrate the important factors that influence the grouping of cellular manufacturing system in four stages. According to the importance, dynamics, influence and the characteristics of the factors, this research considers approperiate factors and provides approperiate mechanism and method. Moreover, this research also provides dynamic mechanism and method when manufacturing environments changes. The first module use the genetic algorithm(GA) to integrated the main grouping factors. The multi-fitness functions will be proposed to the genetic operators and replacement strategy of genetic algorithm. The module also proposes the fuzzy matrices for chromosomal representation to enhance reality and flexibility. This module will be divided into three parts, the solution process of one objective, the solution process of two objectives, the solution process of multi-objectives. The second module uses fuzzy c-means(FCM) to plan the routing of parts. In addition, some fuzzy membership functions are defined for many design and manufacturing attributes of parts. Then, combine with the routing mentioned above and the part families formation based on these factors. The third module assigns part families and cutting tools, fixtures that parts use to approperiate manufacturing cell. Then, this research defines machine capacity and setup time as revised factors of revised algoriyhm. Finally, fuzzy c-means will be utilized to revise the planned outcome of the first module and the second module. Through the three modules mentioned above, the planning of manufacturing cell is finished through machine cells formation, part fanilies formation, and the revised outcome. Finally, the fourth module considers the factors that may change in short term or dynamic factors when manufacturing environment changes, this module proposed the manufacturing cell dynamic adaptation method. This module proposed the mechanism and method of dynamic adaptation to respond the changes of environment when new parts and new machines arrive the planning system, machine broken and exchange mold, the change of products’ demand, management factors and so on.
50
Lu, Cheng-Yen, and 呂政諺. "Design and manufacturing of high rejection rate multi-stage microwave amplifier." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/92406152868030963256.
Повний текст джерелаАнотація:
碩士華梵大學
電子工程學系碩士班
102
In this thesis, using the three segments coupled lines to design as much as the high-band rejection rate microwave amplifier design and production, using the coupled line filter of VSAT system architecture to improve the traditional multi-stage amplifier design, this filter has a DC Block and alternative amplifier matching effect, there will be very good at 13GHz isolation. In order to avoid interference with LO to RF signals. Firstly amplifier implementations to measure parameters and measurement parameters via the amplifier conjugate match with stability theory, filter design as a reference impedance. Second, the use of admittance converter is designed for the complete coupled line filter, then solve the coupled line parity mode impedance of each segment, and verify the location of the filter transmission zero. Design a transmission zero at 13 GHz and DC Block effect, the simulation results of the filter and amplifier integration, making multi-stage amplifier circuit further explore multi-stage amplifier frequency response.