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Articles 1 - 11 of 11
Full-Text Articles in Engineering
Modeling Of Capacitor Impedance In Switching Converters, Jonathan W. Kimball, Philip T. Krein, Kevin R. Cahill
Modeling Of Capacitor Impedance In Switching Converters, Jonathan W. Kimball, Philip T. Krein, Kevin R. Cahill
Electrical and Computer Engineering Faculty Research & Creative Works
Switched capacitor (SC) converters are gaining acceptance as alternatives to traditional, inductor-based switching power converters. Proper design of SC converters requires an understanding of all loss sources and their impacts on circuit operation. In the present work, an equivalent resistance method is developed for analysis, and equivalent resistance formulae are presented for various modes of operation. Quasiresonant converters are explored and compared to standard SC converters. Comparisons to inductor-based switching power converters are made. A number of capacitor technologies are evaluated and compared for applications to both SC converters and inductor-based converters. The resulting model can be used to accurately …
Percolation In Two-Dimensional Grain Boundary Structures And Polycrystal Property Closures, David T. Fullwood
Percolation In Two-Dimensional Grain Boundary Structures And Polycrystal Property Closures, David T. Fullwood
Theses and Dissertations
The thesis addresses two topics in the study of material properties as determined by the microstructure. The first topic involves percolation as a tool in relating the grain boundary structure to global properties such as fracture and corrosion resistance. The second investigates optimization techniques in order to find the space of values that properties of a material can take, from consideration of the microstructure. In part I, the applicability of standard lattice percolation models to a random 2-D grain structure is explored. A random network based on the triangle lattice is proposed as a more appropriate model, and results in …
H-Infinity Estimation For Fuzzy Membership Function Optimization, Daniel J. Simon
H-Infinity Estimation For Fuzzy Membership Function Optimization, Daniel J. Simon
Electrical and Computer Engineering Faculty Publications
Given a fuzzy logic system, how can we determine the membership functions that will result in the best performance? If we constrain the membership functions to a specific shape (e.g., triangles or trapezoids) then each membership function can be parameterized by a few variables and the membership optimization problem can be reduced to a parameter optimization problem. The parameter optimization problem can then be formulated as a nonlinear filtering problem. In this paper we solve the nonlinear filtering problem using H∞ state estimation theory. However, the membership functions that result from this approach are not (in general) sum normal. …
Developing A Design Space Model Using A Multidisciplinary Design Optimization Schema In A Product Lifecycle Management System To Capture Knowledge For Reuse, Nathaniel Luke Fife
Developing A Design Space Model Using A Multidisciplinary Design Optimization Schema In A Product Lifecycle Management System To Capture Knowledge For Reuse, Nathaniel Luke Fife
Theses and Dissertations
Parametric strategies for design automation and optimization can have a big impact on engineering design. When parametric tasks and optimization frameworks and methods are combined, theses strategies can be used to make up what is known as a multidisciplinary design optimization (MDO) schema. Knowledge of a design space can be modeled by using a MDO schema to represent the design process. However, current MDO frameworks used to create this schema lack the scope to capture enterprise wide knowledge for reuse and collaboration. Concurrent with the development of MDO, many companies are moving toward increased use of product lifecycle management (PLM). …
Developing New Multidimensional Knapsack Heuristics Based On Empirical Analysis Of Legacy Heuristics, Yong Kun Cho
Developing New Multidimensional Knapsack Heuristics Based On Empirical Analysis Of Legacy Heuristics, Yong Kun Cho
Theses and Dissertations
The multidimensional knapsack problem (MKP) has been used to model a variety of practical optimization and decision-making applications. Due to its combinatorial nature, heuristics are often employed to quickly find good solutions to MKPs. While there have been a variety of heuristics proposed for the MKP, and a plethora of empirical studies comparing the performance of these heuristics, little has been done to garner a deeper understanding of heuristic performance as a function of problem structure. This dissertation presents a research methodology, empirical and theoretical results explicitly aimed at gaining a deeper understanding of heuristic procedural performance as a function …
Multi-Criteria Decision Analysis For The Optimal Management Of Nitrate Contamination Of Aquifers, Mohammad N. Almasri, Jagath J. Kaluarachchi
Multi-Criteria Decision Analysis For The Optimal Management Of Nitrate Contamination Of Aquifers, Mohammad N. Almasri, Jagath J. Kaluarachchi
Civil and Environmental Engineering Faculty Publications
We present an integrated methodology for the optimal management of nitrate contamination of ground water combining environmental assessment and economic cost evaluation through multi-criteria decision analysis. The proposed methodology incorporates an integrated physical modeling framework accounting for on-ground nitrogen loading and losses, soil nitrogen dynamics, and fate and transport of nitrate in ground water to compute the sustainable on-ground nitrogen loading such that the maximum contaminant level is not violated. A number of protection alternatives to stipulate the predicted sustainable on-ground nitrogen loading are evaluated using the decision analysis that employs the importance order of criteria approach for ranking and …
Optimization Of Shape, Size, And Topology Design Variables In Trusses With A Genetic Algorithm, Kevin M. Gillman
Optimization Of Shape, Size, And Topology Design Variables In Trusses With A Genetic Algorithm, Kevin M. Gillman
Theses and Dissertations
Briggs' genetic algorithm was extended in the Gillman algorithm to include shape optimization of trusses. Other contributions include value representation, different member linking, alternate genes, automatic k-factor evaluation for buckling, and the option to prevent overlapping members. The purpose of these contributions was to make optimization using a genetic algorithm more accessible to design engineers. The Gillman algorithm was demonstrated in two original examples as well as an example from a published work. The Gillman algorithm was effective in finding lighter designs.
Optimization Of An Unstructured Finite Element Mesh For Tide And Storm Surge Modeling Applications In The Western North Atlantic Ocean, Satoshi Kojima
Optimization Of An Unstructured Finite Element Mesh For Tide And Storm Surge Modeling Applications In The Western North Atlantic Ocean, Satoshi Kojima
Electronic Theses and Dissertations
Recently, a highly resolved, finite element mesh was developed for the purpose of performing hydrodynamic calculations in the Western North Atlantic Tidal (WNAT) model domain. The WNAT model domain consists of the Gulf of Mexico, the Caribbean Sea, and the entire portion of the North Atlantic Ocean found west of the 60° W meridian. This high resolution mesh (333K) employs 332,582 computational nodes and 647,018 triangular elements to provide approximately 1.0 to 25 km node spacing. In the previous work, the 333K mesh was applied in a Localized Truncation Error Analysis (LTEA) to produce nodal density requirements for the WNAT …
On-Line Job-Shop Scheduling Of A Manufacturing System Based On A Virtual Supervisor Concept, Jesús Trujillo, Zbigniew Pasek, Enrique Baeyens
On-Line Job-Shop Scheduling Of A Manufacturing System Based On A Virtual Supervisor Concept, Jesús Trujillo, Zbigniew Pasek, Enrique Baeyens
Industrial and Manufacturing Systems Engineering Publications
The controls for reconfigurable manufacturing systems have to be capable not only of identifying exceptions on-line, but also simultaneously developing on-line strategies for unpredictable customer orders or inaccurate estimates of processing times. This paper presents an approach for job-shop scheduling with uncertain arrival times. The approach exploits Virtual Supervisor (VS) concept, which provides access to all system information during program execution and thus can readily monitor the overall system performance. The goal is to minimize expected part tardiness and earliness cost. A solution methodology based on a combined Lagrangian relaxation, VS-Patterns, Maxwell equations and temporal difference is developed to obtain …
A Methodology For Minimizing The Oscillations In Supply Chains Using System Dynamics And Genetic Algorithms, Ramamoorthy C.V.V. Lakkoju
A Methodology For Minimizing The Oscillations In Supply Chains Using System Dynamics And Genetic Algorithms, Ramamoorthy C.V.V. Lakkoju
Electronic Theses and Dissertations
Supply Chain Management (SCM) is a critically significant strategy that enterprises depend on to meet challenges that they face because of highly competitive and dynamic business environments of today. Supply chain management involves the entire network of processes from procurement of raw materials/services/technologies to manufacturing or servicing intermediate products/services to converting them into final products or services and then distributing and retailing them till they reach final customers. A supply chain network by nature is a large and complex, engineering and management system. Oscillations occurring in a supply chain because of internal and/or external influences and measures to be taken …
Optimal Operating Strategy For Wells With Downhole Water Sink Completions To Control Water Production And Improve Performance, Ozan Arslan
LSU Doctoral Dissertations
Downhole water sink (DWS) technology is an alternative to conventional limited-entry completions to control water production in wells with bottom water drive. DWS wells comprise two completions: the bottom completion produces water and keeps the top completion open to oil inflow. The system performance depends on careful manipulation of the top and bottom rates to maximize oil productivity and produce oil-free water from the bottom completion. Conventional nodal analysis cannot provide a solution for DWS wells because the critical rates for water coning change with water drainage rate. A reservoir simulator is used to model two-phase flow to the dual …