Digital Commons Network^™

Voltage Security Constrained Reactive Power Optimization Incorporating Wind Generation, L G. Meegahapola, E Vittal, A Keane, D Flynn

Dr Lasantha G Meegahapola

This paper presents a comparative analysis between conventional optimal power flow (OPF) and voltage constrained OPF strategies with wind generation. The study has been performed using the New England 39 bus system with 12 doublyfed induction generator (DFIG) based wind farms installed across the network. A voltage security assessment is carried out to determine the critical wind farms for voltage stability enhancement. The power losses and individual wind farm reactive power generation have been compared with and without voltage stability constraints imposed on the OPF simulation. It is shown that voltage constrained OPF leads to much greater active power losses …

Simulation And Optimization Modeling For Drive-Through Mass Vaccination – A Generalized Approach, Aman Gupta, Gerald W. Evans, Sunderesh S. Heragu

Aman Gupta

Proper planning and execution of mass vaccination at the onset of a pandemic outbreak is important for local health departments. Mass vaccination clinics are required to be setup and run for naturally occurring pandemic outbreaks or even in response to terrorist attacks, e.g., anthrax attack. Walk-in clinics have often been used to administer vaccines. When a large percentage of a population must be vaccinated to mitigate the ill-effects of an attack or pandemic, drive-through clinics appear to be more effective because a much higher throughput can be achieved when compared to walk-in clinics. There are other benefits as well. For …

Effects Of The Flash Welding Process On Mechanical And Microstructural Properties Of Structural Steel Joints Assessed Using Dest, Don Whaley

Master’s Theses

ASTM A529 carbon¿manganese steel angle specimens were joined by flash butt welding and the effects of varying process parameter settings on the resulting welds were investigated. The weld metal and heat affected zones were examined and tested using tensile testing, ultrasonic scanning, Rockwell hardness testing, optical microscopy, and scanning electron microscopy with energy dispersive spectroscopy in order to quantify the effect of process variables on weld quality. Statistical analysis of experimental tensile and ultrasonic scanning data highlighted the sensitivity of weld strength and the presence of weld zone inclusions and interfacial defects to the process factors of upset current, flashing …

Transmission Shift Map Optimization For Reduced Electrical Energy Consumption In A Pre-Transmission Parallel Plug-In Hybrid Electric Vehicle, Jonathan Dean Moore

Theses and Dissertations

The use of an automatic transmission in pre-transmission parallel hybrid electric vehicles provides greater potential for powertrain optimization than conventional vehicles. By modifying the shift map, the transmission’s gear selection can be adjusted to reduce the energy consumption of the vehicle. A method for determining the optimal shift map for this hybrid vehicle has been implemented using global optimization and software-in-the-loop vehicle simulation. An analysis of the optimization has been performed using software-in-the-loop and hardware-in-the-loop simulation and evaluates two vehicle modes: regenerative braking active and regenerative braking disabled. The results of these two modes illustrate the successful implementation of the …

Production Of Lignin-Based Phenolic Resins Using De-Polymerized Kraft Lignin And Process Optimization, Homaira Siddiqui

Electronic Thesis and Dissertation Repository

Commercialization of Lignin-based phenol formaldehyde resins (LPF) has been limited due to the increase in curing temperatures and decrease in adhesive strength of LPF compared to conventional phenolic resins. Lignin depolymerization can increase the reactivity of lignin; however, the effect of lignin molecular weight on curing performance of LPF resins has yet to be investigated. This research work examined the optimization of synthesis parameters including percent substitution of phenol with lignin, formaldehyde- to-phenol ratio (F/P), and Mw of lignin to reduce the curing temperature and increase the adhesive strength of LPF. DSC analysis indicated that lignin with Mw ~1200g/mol resulted …

Structural Analysis And Optimization Of Skyscrapers Connected With Skybridges And Atria, Amy Jean Taylor Mccall

Theses and Dissertations

Skybridges and atria between buildings are becoming more and more popular. Most current skybridge connections are either roller or rigid-connections. This dissertation presents an investigation of the structural analysis and optimization of skyscraper systems with hinge-connected skybridges, and compares the results to skyscraper systems with roller-connected skybridges and to skyscraper systems without skybridges altogether. Also presented is an investigation of the structural analysis and optimization of skyscrapers both with and without atria between the buildings. It was assumed that the atria envelope was constructed with cushions made from lightweight, transparent, and flexible Ethylene Tetrafluoroethylene (ETFE). A simplified skyscraper skybridge model …

10 Reasons Business Succeed, Ivan F. Rodriguez

Ivan F Rodriguez

The experience and skills of the top managers. Over half of business failures are directly related to managerial incompetence.

Optimizing The Sterilization Process Of Canned Food Using Temperature Distribution Studies, Ibrahim M. Ismail, Alaa Fahmy, Ahmed Azab, Magdy Abadir, Seif-Eddeen K. Fateen

Seif-Eddeen K Fateen

The thermal processing of canned food is the most important step in the canning procedure. Retort operating procedures must ensure that uniform processing temperature is achieved and maintained throughout the locations of the canned containers during the process. In this study, temperature distribution tests have been used as a means of verifying the temperature uniformity around the containers. These studies were carried out in two Egyptian canning plants in horizontal water-immersion and water-spray retorts under fully loaded operating conditions. Time-temperature data gathered were used as a guidance tool in improving temperature distribution and in optimizing the process schedule.

A Dea Model To Optimize Insurance Payment Plans Based On Pacs, Gagan Rajpal

Doctoral Dissertations

Healthcare industry has evolved dramatically over the time. From being a “cottage industry” to an “organized industry” has brought lot of changes. The changes have been both good and bad. Among the problems that have surfaced in past couple of decades, rising healthcare cost has been one of the most significant. The rising healthcare cost has been documented to be a symptom of several factors. Since the inception of healthcare as an organized industry several payment models for providers and hospitals have been adopted. Current healthcare reforms have proposed new payments models to curb the rising cost and provide consumer …

Techniques For Optimum Design Of Actively Controlled Structures Including Topological Considerations, Arjumand Ali

Theses and Dissertations

The design and performance of complex engineering systems often depends on several conflicting objectives which, in many cases, cannot be represented as a single measure of performance. This thesis presents a multi-objective formulation for a comprehensive treatment of the structural and topological considerations in the design of actively controlled structures.

The dissertation addresses three main problems. The first problem deals with optimum placement of actuators in actively controlled structures. The purpose of control is to reduce the vibrations when the structure is subjected to a disturbance. In order to mitigate the structural vibrations as quickly as possible, it is necessary …

Predictive Maturity Of Inexact And Uncertain Strongly Coupled Numerical Models, Ismail Farajpour

All Dissertations

The Computer simulations are commonly used to predict the response of complex systems in many branches of engineering and science. These computer simulations involve the theoretical foundation, numerical modeling and supporting experimental data, all of which contain their associated errors. Furthermore, real-world problems are generally complex in nature, in which each phenomenon is described by the respective constituent models representing different physics and/or scales. The interactions between such constituents are typically complex in nature, such that the outputs of a particular constituent may be the inputs for one or more constituents. Thus, the natural question then arises concerning the validity …

Optimization Of Porous Pavement Mixtures Based On Aggregate Structure, Andrew Neptune

All Dissertations

Porous pavements are sustainable features that are used to help manage the quantity and quality of stormwater runoff. These pavements may include porous asphalt, permeable interlocking concrete pavers and pervious concrete. Since pavements that are purposefully designed to drain water through their matrix are relatively new, contractors and engineers are faced with various challenges such as improper design and installation, poor workability, and excessive finishing which may lead to clogged pores. Therefore, this study on porous pavements examined pervious concrete mixtures to evaluate an optimization process for the preparation of porous pavement mixtures based on aggregate structure to meet desired …

Cost And Embodied Energy Optimization Of Rectangular Reinforced Concrete Beams, Alexander Kosloski

All Theses

Concrete has a large environmental footprint so it is desirable to find ways to efficiently design structural members. Engineers can exercise their abilities early on in the design phase of construction projects to reduce the environmental footprint by minimizing the amount of materials required. One way to achieve these results is to optimize the design of structural concrete. In this study, simple-span rectangular reinforced concrete (RC) beams with a range of different bending moments were analyzed. The primary goal was to combine life cycle analysis (LCA), numerical optimization, and reinforced concrete mechanics to create a framework for designing efficient RC …

Minimization Of Cost And Co2 Emissions For Rectangular Spread Footings Subjected To Biaxial Loading, Andrew Kary Mehdi Assadollahi

Electronic Theses and Dissertations

A Big Bang-Big Crunch (BB-BC) optimization algorithm was applied to the analysis and design of reinforced concrete spread footings subjected to concentric, uniaxial, and biaxial loading. For spread footings subjected to eccentric loading conditions, it is convenient to assume that the entire base of the footing remains in contact with the soil, resulting in a compressive bearing pressure distribution. However, this assumption does not accurately describe the nature of the bearing pressure distribution. Analysis procedures for spread footings subjected to eccentric loading conditions that allow uniaxial and biaxial uplift were developed. From these formulations, an analysis chart of the bearing …

Mixed-Level Response Surface Designs Via A Hybrid Genetic Algorithm, P. Angelopoulos, C. Koukouvinos, D. E. Simos, A. Skountzou

Journal of Statistics Applications & Probability

Response surface methodology is widely used for developing, improving and optimizing processes in various fields. In this paper, we present a general algorithmic method for constructing 2q14q2 mixed-level designs in order to explore and optimize response surfaces with respect to D-efficiency, where the predictor variables are at two and four equally spaced levels, by utilizing a hybrid genetic algorithm. Emphasis is given on various properties that arise from the implementation of the genetic algorithm, such as using genetic operators as local optimizers and the representation of the four levels of the design with a 2-bit Gray Code. We applied the …

Swarm Intelligence As An Optimization Technique, Alma Bregaj

UBT International Conference

Optimization techniques inspired by swarm intelligence have become increasingly popular during the last years. Swarm intelligence is based on nature-inspired behaviours and is successfully applied to optimisation problems in a variety of fields. The advantage of these approaches over traditional techniques is their robustness and flexibility. These properties make swarm intelligence a successful design paradigm for algorithms that deal with increasingly complex problems. In this paper I am focused on the comparison between different swarm-based optimisation algorithms and I have presented some examples of real practical applications of these algorithms.

Cellular Automata For The Flow Simulations On The Earth Surface, Optimization Computation Process, Juraj Cirbus, Michal Podhoranyi

Applied Mathematics & Information Sciences

The spreading of water across terrain is not a simple and isolated process. The spread of water is a part of the more general water cycle. Many commercial software exist for water modelling, but their correct use requires a considerable knowledge of water modelling, and about the study area. Using the relatively simple principle of cellular automata (CA) it is possible to obtain results which compare well with real measurements. This article describes using a CA for simulating the spreading of liquid, using comparatively simple rules and conditions which include several factors affecting the spreading of water such as slope, …

Automatically Optimizing Tree Traversal Algorithms, Youngjoon Jo

Open Access Dissertations

Many domains in computer science, from data-mining to graphics to computational astrophysics, focus heavily on irregular applications. In contrast to regular applications, which operate over dense matrices and arrays, irregular programs manipulate and traverse complex data structures like trees and graphs. As irregular applications operate on ever larger datasets, their performance suffers from poor locality and parallelism. Programmers are burdened with the arduous task of manually tuning such applications for better performance. Generally applicable techniques to optimize irregular applications are highly desired, yet scarce.

In this dissertation, we argue that, for an important subset of irregular programs which arises in …

Energy Systems Analysis For A Solar Economy, Dharik Sanchan Mallapragada

Open Access Dissertations

The use of solar energy for human needs faces challenges owing to its relatively low energy intensity and intermittent availability, coupled with the constrained availability of renewable carbon and land resources. This study uses systems analysis tools to identify carbon and energy efficient transformations of solar energy for different purposes, including transportation fuels and grid-scale energy storage. These efforts have been complemented with a feasibility analysis of existing fossil-energy and other hybrid pathways.

In an era of limited fossil resources, liquid fuels from sustainably available (SA) biomass could meet the energy needs of the transportation sector. We present a method …

Modeling And Control Of Nanoparticle Bloodstream Concentration For Cancer Therapies, Scarlett S. Bracey

Doctoral Dissertations

Currently, the most commonly used treatments for cancerous tumors (chemotherapy, radiation, etc.) have almost no method of monitoring the administration of the treatment for adverse effects in real time. Without any real time feedback or control, treatment becomes a "guess and check" method with no way of predicting the effects of the drugs based on the actual bioavailability to the patient's body. One particular drug may be effective for one patient, yet provide no benefit to another. Doctors and scientists do not routinely attempt to quantifiably explain this discrepancy. In this work, mathematical modeling and analysis techniques are joined together …

Environmental Systems Modeling And Management - University Of Virginia, Charlottesville, Teresa Culver

All ECSTATIC Materials

Grad/Undergrad course in environmental systems modeling and management offered at University of Virginia, Charlottesville in Fall 2013.

Deterministic Optimization And Design - University Of California, Davis, Jay R. Lund

All ECSTATIC Materials

Undergraduate course in deterministic optimization and design offered at U.C. Davis.

Design Synthesis And Optimization Of Permanent Magnet Synchronous Machines Based On Computationally-Efficient Finite Element Analysis, Gennadi Sizov

Dissertations (1934 -)

In this dissertation, a model-based multi-objective optimal design of permanent magnet ac machines, supplied by sine-wave current regulated drives, is developed and implemented. The design procedure uses an efficient electromagnetic finite element-based solver to accurately model nonlinear material properties and complex geometric shapes associated with magnetic circuit design. Application of an electromagnetic finite element-based solver allows for accurate computation in intricate performance parameters and characteristics. The first contribution of this dissertation is the development of a rapid computational method that allows accurate and efficient exploration of large multi-dimensional design spaces in search of optimum design(s). The computationally efficient finite element-based …

Computational Optogenetics: Empirically-Derived Voltage- And Light-Sensitive Channelrhodopsin-2 Model, John C. Williams, Jianjin Xu, Zhongju Lu, Aleksandra Klimas, Xuxin Chen, Christina M. Ambrosi, Ira S. Cohen, Emilia Entcheva

Department of Biomedical Engineering Faculty Publications

Channelrhodospin-2 (ChR2), a light-sensitive ion channel, and its variants have emerged as new excitatory optogenetic tools not only in neuroscience, but also in other areas, including cardiac electrophysiology. An accurate quantitative model of ChR2 is necessary for in silicoprediction of the response to optical stimulation in realistic tissue/organ settings. Such a model can guide the rational design of new ion channel functionality tailored to different cell types/tissues. Focusing on one of the most widely used ChR2 mutants (H134R) with enhanced current, we collected a comprehensive experimental data set of the response of this ion channel to different irradiances and voltages, …

An Improved Multi-Objective Genetic Algorithm For Solving Multi-Objective Problems, Sheng-Ta Hsieh, Shih-Yuan Chiu, Shi-Jim Yen

Applied Mathematics & Information Sciences

Multi-objective optimization (MO) has been an active area of research in the last two decades. In multi-objective genetic algorithm (MOGA), the quality of newly generated offspring of the population will directly affect the performance of finding the Pareto optimum. In this paper, an improved MOGA, named SMGA, is proposed for solving multi-objective optimization problems. To increase efficiency during solution searching, an effective mutation named sharing mutation is adopted to generate potential offspring. Experiments were conducted on CEC-09 MOP test problems. The results show that the proposed method exhibits better performance when solving these benchmark problems compared to related multi-objective evolutionary …

Optimization Of Inpatient Hemodialysis Scheduling Considering Efficiency And Treatment Delays To Minimize Length Of Stay, Manuel Tolentino Peña

Theses

Inpatient dialysis units face an uncertain daily demand of hemodialysis procedures for end-stage renal disease (ESRD) patients hospitalized for health conditions that may or may not be directly related to their renal disease. While hospitalized, these patients must receive hemodialysis in addition to any medical services needed for their primary diagnosis. As a result, when demand for inpatient dialysis is high, treatments and procedures required by these inpatients may be delayed increasing their length of stays (LOS). This research presents an optimization approach for daily scheduling of inpatient hemodialysis to maximize the efficiency of the dialysis unit while minimizing delays …

An Optimization-Based Approach For Vaccine Prioritization, Timothy Schmoke

Theses

An effective vaccine prioritization process is essential to prevent the many issues that currently weaken global vaccination efforts. Identifying challenges associated with vaccine development is important when considering which initiatives will provide immunization that is effective, affordable, and easy to administer. The process of establishing priorities for vaccine development is complicated, though, by the conflicting interests of multiple stakeholders involved in the vaccine market. Additionally, uncertainties exist regarding: (1) the resources and time required for vaccine development, (2) the expected benefits of development, and (3) the anticipated demand for vaccination, further complicating the prioritization process. This study proposes a decision-support …

Multilevel Design Optimization Of Automotive Structures Using Dummy- And Vehicle-Based Responses, Imtiaz Shareef Gandikota

Theses and Dissertations

A computationally efficient multilevel decomposition and optimization framework is developed for application to automotive structures. A full scale finite element (FE) model of a passenger car along with a dummy and occupant restraint system (ORS) is used to analyze crashworthiness and occupant safety criteria in two crash scenarios. The vehicle and ORS models are incorporated into a decomposed multilevel framework and optimized with mass and occupant injury criteria as objectives. A surrogate modeling technique is used to approximate the computationally expensive nonlinear FE responses. A multilevel target matching optimization problem is formulated to obtain a design satisfying system level performance …

Computational Design Optimization Of Arc Welding Process For Reduced Distortion In Welded Structures, Mohammad Refatul Islam

Theses and Dissertations

An effective approach to determine optimum welding process parameters is implementation of advanced computer aided engineering (CAE) tool that integrates efficient optimization techniques and numerical welding simulation. In this thesis, an automated computational methodology to determine optimum arc welding process parameters is proposed. It is a coupled Genetic Algorithms (GA) and Finite Element (FE) based optimization method where GA directly utilizes output responses of FE based welding simulations for iterative optimization. Effectiveness of the method has been demonstrated by predicting optimum parameters of a lap joint specimen of two thin steel plates and automotive structure of nonlinear welding path for …

On The Performance Of A Hybrid Genetic Algorithm In Dynamic Environments, Quan Yuan, Zhixin Yang

Mathematics Faculty Research Publications

The ability to track the optimum of dynamic environments is important in many practical applications. In this paper, the capability of a hybrid genetic algorithm (HGA) to track the optimum in some dynamic environments is investigated for different functional dimensions, update frequencies, and displacement strengths in different types of dynamic environments. Experimental results are reported by using the HGA and some other existing evolutionary algorithms in the literature. The results show that the HGA has better capability to track the dynamic optimum than some other existing algorithms.