Engineering Commons^™

Modeling Performance, Cost, Delivery, And Trip Distribution Of Demand Responsive Transit Systems With Zoning, Mahour Rahimi

Doctoral Dissertations

Demand responsive transit (DRT) services are expensive to operate, so it is crucial to understand the factors that drive the agency costs and be able to investigate and predict the effect of possible changes in specific operating parameters as well as demand and service coverage areas on total costs. In this research, we adopt the concept of the analytical model proposed by Daganzo (1978) to present continuum approximation (CA) models that can estimate important service related factors. As the first step, we propose three analytical models to approximate the operation related variables of DRT services; Fleet Size, Vehicle Hours Traveled …

Theory And Practice Of Supply Chain Synchronization, Michael Prokle

Doctoral Dissertations

In this dissertation, we develop strategies to synchronize component procurement in assemble-to-order (ATO) production and overhaul operations. We focus on the high-tech and mass customization industries which are not only considered to be very important to create or keep U.S. manufacturing jobs, but also suffer most from component inventory burden. In the second chapter, we address the deterministic joint replenishment inventory problem with batch size constraints (JRPB). We characterize system regeneration points, derive a closed-form expression of the average product inventory, and formulate the problem of finding the optimal joint reorder interval to minimize inventory and ordering costs per unit …

Decision Analytical Methods For Robust Water Infrastructure Planning Under Deep Uncertainty, Mehmet Umit Taner

Doctoral Dissertations

Deep uncertainties resulting from climate change, demographic pressures, and rapidly evolving socioeconomic conditions are challenging the way that water planners design and operate large-scale infrastructure systems. Conventionally, water infrastructures have been developed using stationary methods, assuming that the underlying uncertainties can be derived from historical data or experience. However, these methods are less useful under deeply uncertain climate and socioeconomic conditions, in which the future can be substantially different from the past and cannot be expressed by well-defined probability distributions. The recognition of deep uncertainties in long-term water resources planning has led to the development of “decision-analytical” frameworks that do …

Flight Risk Management And Crew Reserve Optimization, Ying Zhang

Doctoral Dissertations

There are two key concerns in the development process of aviation. One is safety, and the other is cost. An airline running with high safety and low cost must be the most competitive one in the market. This work investigates two research efforts respectively relevant to these two concerns.

When building support of a real time Flight Risk Assessment and Mitigation System (FRAMS), a sequential multi-stage approach is developed. The whole risk management process is considered in order to improve the safety of each flight by integrating AHP and FTA technique to describe the framework of all levels of risks …

An Optimization Framework For Integrating Variable Capacity And Pavement Thickness Requirements In Highway Cost Allocation, Saurav Kumar Dubey

Doctoral Dissertations

The objective of Highway Cost Allocation (HCA) is to distribute or allocate in a fair and rational manner the cost of a transportation facility (either a highway or bridge) among all vehicle classes using it. The purpose of this dissertation is to study and enhance a model, known as the least-core model, to include both pavement thickness and traffic capacity requirements for all coalitions formed with a given group of vehicle classes. Considering vehicle classes as players and groups of vehicle classes as coalitions, it is possible to quantify the thickness and width of pavement needed to accommodate the vehicle …

A Model For Sustaining New Technology Based On Government Incentives, Girish Upreti

Doctoral Dissertations

The diffusion of new technology that provides environmental benefits may require government incentives for a duration of time, especially when the technology is expensive. The Center of Systems Research and Education (CASRE) model is developed that analyzes the impact of incentives in sustaining new technologies to allow their social acceptance. The CASRE model includes both demand and supply variables associated with incentive policy to sustain new technology. The key to market dissemination and sustainability is the Investment Tax Credit (ITC) levels provided by the government. The level of ITC is based on the current cost to the customer and the …

Model For Prioritization Of High Variation Elements In Discrete Production Systems, Bharadwaj Venkatesan

Doctoral Dissertations

The complexity of the modern manufacturing enterprise has led companies to look for techniques and methodologies for improving production performance. Lean manufacturing techniques have been applied in the US with varying degrees of success, and Theory of Constraints (TOC) has been used to emphasize the flow of production and identify performance improvement projects. One aspect of manufacturing for which there has been limited academic or industrial research till date is the impact of variation on production performance and the identification of improvement projects based on variation. This thesis develops a methodology to incorporate random and simultaneous occurrence of variability in …

Sustainability Analysis For New Technologies Of Biofuels And Additive Manufacturing, Nelson A. Granda Marulanda

Doctoral Dissertations

This work is a compendium of different sustainability analysis on new technologies. The first chapter performed a Life Cycle Analysis of a biofuel process where pine woodchips are used to create SynGas. The study was done using a 10 tons gasifier, the mass balance of the reaction and an input/output analysis. All the data obtained was input into a freeware LCA software and the results were compared to the use of regular produced natural gas. The second chapter creates a benchmark of energy intensity and presents a case using binder jetting technology. Different Additive Manufacturing technologies energy intensity was reported, …

Modeling The Economic And Environmental Performance Of Offshore Wind Energy, Alexana Cranmer

Doctoral Dissertations

Offshore wind is a growing source of energy globally. Like any energy technology, it has impacts on the environment. In the case of renewable energy, we need a way to consider the environmental benefits as well as the environmental costs. This dissertation develops a set of models to examine the economic and environmental costs and benefits and the trade-offs between them. We ask how much offshore wind energy should be sited, and where should that offshore wind energy be located? The first model estimates the economic impact of wake interactions between wind farms. Wind farm sites are chosen through a …

Multi-Criteria Decision Making When Planning Sustainable Multimodal Transportation Routes In A Linear Corridor, Marie Louis

Doctoral Dissertations

In urban and suburban locations, public transit can be seen as an effective mode of daily transportation. The majority of the time, travelers would seek the cheapest, shortest, and possibly most eco-friendly means of transit. When designing public transit network systems, transportation planners and decision-makers, with input from stakeholders, should strive to optimize transportation services to meet the needs of the population most efficiently and at the lowest cost, that is, providing a transportation system that s the three E's of the sustainability concept: environment, social equity, and economic. Previous studies have focused on sustainability as the primary concern in …

Exploring A Semi-Virtual Reality System Impacting Learning Curves Of College Students, Hongbiao Yang

Doctoral Dissertations

Virtual reality (VR) is a trending technology used in a broad range of fields including education and has become one of the most promising directions for educators. In this research, the investigation focuses on how the semi-immersive VR application can be used for educational purposes by exploring the VR factors and the interactions between these factors. A theoretical learning framework is also proposed to offer an explanation for the beneficial effects of education brought by VR at a high level.

This research consists of three parts. First, this research will introduce the development of Walk-in-Place Learning System (WIPLS), a semi-immersive …

Transition To Electric Vehicles In The California Automobile Industry, Jinglu Song

Doctoral Dissertations

This dissertation presents a comprehensive study on the market adoption of electric vehicle and policy impact of the Zero Emission Vehicle (ZEV) mandate in the California automotive market. This research is primarily consisting of three parts. The author first built a technology innovation pricing model based on multi-nomial logit modelling method. This studies the dynamics among customer preferences, market acceptance and policy impact on vehicle pricing in the California automotive market. Results show that the ZEV mandate could profoundly enhance the market adoption of electric vehicles. There is a threshold on the magnitude of policy intervention. If the number of …

Electricity And Fuel Consumption In A Lean Energy Supply Chain, Mostafa Ghafoorivarzaneh

Doctoral Dissertations

Human activities are the main sources of environmental pollution. Awareness about this fact, motivated us to make changes in different paradigms of our lives including industrial or personal activities. Environmental activities assumed to have conflict with financial objectives, in this study we try to align business requirements with environmental concerns.

Among all human activities, generating energy has the most negative impact on the environment. The major part of the generated energy will be consumed in transportation and industrial demand which makes them the most effective targets for the reduction of greenhouse gas emission. In a lean environment, small batch sizes …

Methods For Incorporating Ecological Impacts With Climate Uncertainty To Support Robust Flood Management Decision-Making, Caitlin M. Spence

Doctoral Dissertations

Modern and historic flood risk management involves accommodating multiple sources of sources of uncertainty and potential impacts across a broad range of interrelated sectors. Sources of uncertainty that affect planning include internal climate variability, anthropogenic changes such as land use and system performance expectations, and more recently changes in climatology that affect the resources supporting the system. Flood management systems potentially impact human settlements within and beyond the systems’ scope of planning, local weather patterns, and associated ecological systems. Federal guidelines across nations have called for greater consideration of uncertainty and impacts of water resources planning projects, but methods for …

Multi-Objective Combinatorial Optimization Problems In Transportation And Defense Systems, Hadi Farhangi

Doctoral Dissertations

"Multi-objective Optimization problems arise in many applications; hence, solving them efficiently is important for decision makers. A common procedure to solve such problems is to generate the exact set of Pareto efficient solutions. However, if the problem is combinatorial, generating the exact set of Pareto efficient solutions can be challenging. This dissertation is dedicated to Multi-objective Combinatorial Optimization problems and their applications in system of systems architecting and railroad track inspection scheduling. In particular, multi-objective system of systems architecting problems with system flexibility and performance improvement funds have been investigated. Efficient solution methods are proposed and evaluated for not only …

Cognition-Based Approaches For High-Precision Text Mining, George John Shannon

Doctoral Dissertations

"This research improves the precision of information extraction from free-form text via the use of cognitive-based approaches to natural language processing (NLP). Cognitive-based approaches are an important, and relatively new, area of research in NLP and search, as well as linguistics. Cognitive approaches enable significant improvements in both the breadth and depth of knowledge extracted from text. This research has made contributions in the areas of a cognitive approach to automated concept recognition in.

Cognitive approaches to search, also called concept-based search, have been shown to improve search precision. Given the tremendous amount of electronic text generated in our digital …

Programming Problems On Time Scales: Theory And Computation, Rasheed Basheer Al-Salih

Doctoral Dissertations

"In this dissertation, novel formulations for several classes of programming problems are derived and proved using the time scales technique. The new formulations unify the discrete and continuous programming models and extend them to other cases "in between." Moreover, the new formulations yield the exact optimal solution for the programming problems on arbitrary isolated time scales, which solve an important open problem. Throughout this dissertation, six distinct classes of programming problems are presented as follows. First, the primal as well as the dual time scales linear programming models on arbitrary time scales are formulated. Second, separated linear programming primal and …