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Articles 1561 - 1590 of 4566

Full-Text Articles in Engineering

Porosity Removal Of Cm247 Ni-Base Superalloy Using Thermal Heat Treatment Without Applied Pressure, Chad Heinrich Jan 2015

Porosity Removal Of Cm247 Ni-Base Superalloy Using Thermal Heat Treatment Without Applied Pressure, Chad Heinrich

Electronic Theses and Dissertations

Blade and vane components made with Ni-base superalloys play a vital role in hot section of gas turbine engines. Removal of porosity in cast Ni-base superalloys is a critical process consideration since porosity from casting process can have deleterious effects on the performance and integrity of superalloy component. Still, the cost-efficient processing of Ni-base superalloys that are technologically acceptable, or superior, can contribute significantly to the life-cycle cost of gas turbine engines. The purpose of this thesis was to explore the possibility of eliminating the hot isostatic pressing cycle in a CM247 Ni-base superalloy processing. For cast CM247, conventional processing …

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Optimization Of Glycerol And Biodiesel Waste Prefermentation To Improve Ebpr, Marzieh Ghasemi Jan 2015

Optimization Of Glycerol And Biodiesel Waste Prefermentation To Improve Ebpr, Marzieh Ghasemi

Electronic Theses and Dissertations

The enhanced biological phosphorus removal (EBPR) process efficiency relies on different operational and process conditions especially the type of carbon source available in the wastewater. Acetic acid and propionic acid are the two major volatile fatty acids (VFAs) found in domestic wastewater which can drive biological phosphorus (P) removal to the desired level. However, often domestic wastewater does not have a sufficient amount of VFAs. Due to high acetate and propionate production-cost, it is not economic to add acetate and propionate directly in full-scale wastewater treatment plants. This brought up the idea of using external carbon sources (e. g. molasses …

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Compressive Sensing And Recovery Of Structured Sparse Signals, Behzad Shahrasbi Jan 2015

Compressive Sensing And Recovery Of Structured Sparse Signals, Behzad Shahrasbi

Electronic Theses and Dissertations

In the recent years, numerous disciplines including telecommunications, medical imaging, computational biology, and neuroscience benefited from increasing applications of high dimensional datasets. This calls for efficient ways of data capturing and data processing. Compressive sensing (CS), which is introduced as an efficient sampling (data capturing) method, is addressing this need. It is well-known that the signals, which belong to an ambient high-dimensional space, have much smaller dimensionality in an appropriate domain. CS taps into this principle and dramatically reduces the number of samples that is required to be captured to avoid any distortion in the information content of the data. …

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Modeling Dense Storage Systems With Location Uncertainty, Mohamed Awwad Jan 2015

Modeling Dense Storage Systems With Location Uncertainty, Mohamed Awwad

Electronic Theses and Dissertations

This dissertation focuses on developing models to study the problem of searching and retrieving items in a dense storage environment. We consider a special storage configuration called an inverted T configuration, which has one horizontal and one vertical aisle. Inverted T configurations have fewer aisles than a traditional aisle-based storage environment. This increases the storage density; however, requires that some items to be moved out of the way to gain access to other more deeply stored items. Such movement can result in item location uncertainty. When items are requested for retrieval in a dense storage environment with item location uncertainty, …

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Characterization Of Waste-To-Energy (Wte) Bottom And Fly Ashes In Cementitious Materials, Jin Woo An Jan 2015

Characterization Of Waste-To-Energy (Wte) Bottom And Fly Ashes In Cementitious Materials, Jin Woo An

Electronic Theses and Dissertations

Waste-to-Energy (WTE) ashes (or called as municipal solid waste incineration ashes) have been recycled in the areas of road bed, asphalt paving, and concrete products in many European and Asian countries. In those countries, recycling programs (including required physical properties and environmental criteria) of ash residue management have been developed so as to encourage and enforce the reuse for WTE ashes instead of landfill disposal. However, the U.S. has shown a lack of consistent and effective management plans as well as environmental regulations for the use of WTE ashes. Many previous studies demonstrated the potential beneficial use of WTE ash …

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Modeling Social Norms In Real-World Agent-Based Simulations, Rahmatollah Beheshti Jan 2015

Modeling Social Norms In Real-World Agent-Based Simulations, Rahmatollah Beheshti

Electronic Theses and Dissertations

Studying and simulating social systems including human groups and societies can be a complex problem. In order to build a model that simulates humans' actions, it is necessary to consider the major factors that affect human behavior. Norms are one of these factors: social norms are the customary rules that govern behavior in groups and societies. Norms are everywhere around us, from the way people handshake or bow to the clothes they wear. They play a large role in determining our behaviors. Studies on norms are much older than the age of computer science, since normative studies have been a …

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Optimal Distribution Network Reconfiguration Using Meta-Heuristic Algorithms, Arash Asrari Jan 2015

Optimal Distribution Network Reconfiguration Using Meta-Heuristic Algorithms, Arash Asrari

Electronic Theses and Dissertations

Finding optimal configuration of power distribution systems topology is an NP-hard combinatorial optimization problem. It becomes more complex when time varying nature of loads in large-scale distribution systems is taken into account. In the second chapter of this dissertation, a systematic approach is proposed to tackle the computational burden of the procedure. To solve the optimization problem, a novel adaptive fuzzy based parallel genetic algorithm (GA) is proposed that employs the concept of parallel computing in identifying the optimal configuration of the network. The integration of fuzzy logic into GA enhances the efficiency of the parallel GA by adaptively modifying …

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A New Paradigm Integrating Business Process Modeling And Use Case Modeling, Barclay Brown Jan 2015

A New Paradigm Integrating Business Process Modeling And Use Case Modeling, Barclay Brown

Electronic Theses and Dissertations

The goal of this research is to develop a new paradigm integrating the practices of business process modeling and use case modeling. These two modeling approaches describe the behavior of organizations and systems, and their interactions, but rest on different paradigms and serve different needs. The base of knowledge and information required for each approach is largely common, however, so an integrated approach has advantages in efficiency, consistency and completeness of the overall behavioral model. Both modeling methods are familiar and widely used. Business process modeling is often employed as a precursor to the development of a system to be …

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Enhanced Structure And Crystallinity Of Semiconducting Polymer Films Through Electrospray Deposition, Johan Rodriguez Jan 2015

Enhanced Structure And Crystallinity Of Semiconducting Polymer Films Through Electrospray Deposition, Johan Rodriguez

Electronic Theses and Dissertations

Electrospray atomization is a method that uses electrical stresses as the means of generating charged droplets. The fundamental working principles of electrospray have previously been extensively studied and demonstrated to have monodisperse droplet size distribution, good stability and scalability. Electrospray is a bottom-up deposition method which opens up the possibility of a roll-to-roll compatible process and is functional at regular atmospheric conditions. Due to this set of positive qualities, this atomization method holds promise as a means of solution based material processing that is cost effective and scalable. Conjugated polymers are among the solution processable materials of most interest, poly(3-hexylthiophene)(P3HT) …

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Quantifying Trust And Reputation For Defense Against Adversaries In Multi-Channel Dynamic Spectrum Access Networks, Shameek Bhattacharjee Jan 2015

Quantifying Trust And Reputation For Defense Against Adversaries In Multi-Channel Dynamic Spectrum Access Networks, Shameek Bhattacharjee

Electronic Theses and Dissertations

Dynamic spectrum access enabled by cognitive radio networks are envisioned to drive the next generation wireless networks that can increase spectrum utility by opportunistically accessing unused spectrum. Due to the policy constraint that there could be no interference to the primary (licensed) users, secondary cognitive radios have to continuously sense for primary transmissions. Typically, sensing reports from multiple cognitive radios are fused as stand-alone observations are prone to errors due to wireless channel characteristics. Such dependence on cooperative spectrum sensing is vulnerable to attacks such as Secondary Spectrum Data Falsification (SSDF) attacks when multiple malicious or selfish radios falsify the …

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Determination Of Frequency-Based Switch Triggers For Optimal Vibration Reduction Via Resonance Frequency Detuning, Garrett Lopp Jan 2015

Determination Of Frequency-Based Switch Triggers For Optimal Vibration Reduction Via Resonance Frequency Detuning, Garrett Lopp

Electronic Theses and Dissertations

Resonance frequency detuning (RFD) is a piezoelectric-based vibration reduction approach that applies to systems experiencing transient excitation through the system*s resonance—for example, turbomachinery experiencing changes in rotation speed, such as on spool-up and spool-down. This technique relies on the inclusion of piezoelectric material and manipulation of its electrical boundary conditions, which control the stiffness of the piezoelectric material. Resonance frequency detuning exploits this effect by intelligently switching between the open-circuit (high stiffness) and short-circuit (low stiffness) conditions as the excitation approaches resonance, subsequently shifting the natural frequency to avoid this resonance crossing and limit the response. The peak response dynamics …

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Applied Error Related Negativity: Single Electrode Electroencephalography In Complex Visual Stimuli, Benjamin Sawyer Jan 2015

Applied Error Related Negativity: Single Electrode Electroencephalography In Complex Visual Stimuli, Benjamin Sawyer

Electronic Theses and Dissertations

Error related negativity (ERN) is a pronounced negative evoked response potential (ERP) that follows a known error. This neural pattern has the potential to communicate user awareness of incorrect actions within milliseconds. While the implications for human-machine interface and augmented cognition are exciting, the ERN has historically been evoked only in the laboratory using complex equipment while presenting simple visual stimuli such as letters and symbols. To effectively harness the applied potential of the ERN, detection must be accomplished in complex environments using simple, preferably single-electrode, EEG systems feasible for integration into field and workplace-ready equipment. The present project attempted …

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Self-Scaling Evolution Of Analog Computation Circuits, Steven Pyle Jan 2015

Self-Scaling Evolution Of Analog Computation Circuits, Steven Pyle

Electronic Theses and Dissertations

Energy and performance improvements of continuous-time analog-based computation for selected applications offer an avenue to continue improving the computational ability of tomorrow*s electronic devices at current technology scaling limits. However, analog computation is plagued by the difficulty of designing complex computational circuits, programmability, as well as the inherent lack of accuracy and precision when compared to digital implementations. In this thesis, evolutionary algorithm-based techniques are utilized within a reconfigurable analog fabric to realize an automated method of designing analog-based computational circuits while adapting the functional range to improve performance. A Self-Scaling Genetic Algorithm is proposed to adapt solutions to computationally-tractable …

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A Coupled Cfd-Lumped Parameter Model Of The Human Circulation: Elucidating The Hemodynamics Of The Hybrid Norwood Palliative Treatment And Effects Of The Reverse Blalock-Taussic Shunt Placement And Diameter, Andres Ceballos Jan 2015

A Coupled Cfd-Lumped Parameter Model Of The Human Circulation: Elucidating The Hemodynamics Of The Hybrid Norwood Palliative Treatment And Effects Of The Reverse Blalock-Taussic Shunt Placement And Diameter, Andres Ceballos

Electronic Theses and Dissertations

The Hybrid Norwood (HN) is a relatively new first stage procedure for neonates with Hypoplastic Left Heart Syndrome (HLHS), in which a sustainable univentricular circulation is established in a less invasive manner than with the standard procedure. A computational multiscale model of such HLHS circulation following the HN procedure was used to obtain detailed hemodynamics. Implementation of a reverse-BT shunt (RBTS), a synthetic bypass from the main pulmonary to the innominate artery placed to counteract aortic arch stenosis, and its effects on local and global hemodynamics were studied. A synthetic and a 3D reconstructed, patient derived anatomy after the HN …

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Resource Management In Large-Scale Systems, Ashkan Paya Jan 2015

Resource Management In Large-Scale Systems, Ashkan Paya

Electronic Theses and Dissertations

The focus of this thesis is resource management in large-scale systems. Our primary concerns are energy management and practical principles for self-organization and self-management. The main contributions of our work are: 1. Models. We proposed several models for different aspects of resource management, e.g., energy-aware load balancing and application scaling for the cloud ecosystem, hierarchical architecture model for self-organizing and self-manageable systems and a new cloud delivery model based on auction-driven self-organization approach. 2. Algorithms. We also proposed several different algorithms for the models described above. Algorithms such as coalition formation, combinatorial auctions and clustering algorithm for scale-free organizations of …

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An Integrated Framework For Automated Data Collection And Processing For Discrete Event Simulation Models, Carlos Rodriguez Jan 2015

An Integrated Framework For Automated Data Collection And Processing For Discrete Event Simulation Models, Carlos Rodriguez

Electronic Theses and Dissertations

Discrete Events Simulation (DES) is a powerful tool of modeling and analysis used in different disciplines. DES models require data in order to determine the different parameters that drive the simulations. The literature about DES input data management indicates that the preparation of necessary input data is often a highly manual process, which causes inefficiencies, significant time consumption and a negative user experience. The focus of this research investigation is addressing the manual data collection and processing (MDCAP) problem prevalent in DES projects. This research investigation presents an integrated framework to solve the MDCAP problem by classifying the data needed …

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Stability And Control In Complex Networks Of Dynamical Systems, Saeed Manaffam Jan 2015

Stability And Control In Complex Networks Of Dynamical Systems, Saeed Manaffam

Electronic Theses and Dissertations

Stability analysis of networked dynamical systems has been of interest in many disciplines such as biology and physics and chemistry with applications such as LASER cooling and plasma stability. These large networks are often modeled to have a completely random (Erdös-Rényi) or semi-random (Small-World) topologies. The former model is often used due to mathematical tractability while the latter has been shown to be a better model for most real life networks. The recent emergence of cyber physical systems, and in particular the smart grid, has given rise to a number of engineering questions regarding the control and optimization of such …

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Ultra-Wideband Spread Spectrum Communications Using Software Defined Radio And Surface Acoustic Wave Correlators, Daniel Gallagher Jan 2015

Ultra-Wideband Spread Spectrum Communications Using Software Defined Radio And Surface Acoustic Wave Correlators, Daniel Gallagher

Electronic Theses and Dissertations

Ultra-wideband (UWB) communication technology offers inherent advantages such as the ability to coexist with previously allocated Federal Communications Commission (FCC) frequencies, simple transceiver architecture, and high performance in noisy environments. Spread spectrum techniques offer additional improvements beyond the conventional pulse-based UWB communications. This dissertation implements a multiple-access UWB communication system using a surface acoustic wave (SAW) correlator receiver with orthogonal frequency coding and software defined radio (SDR) base station transmitter. Orthogonal frequency coding (OFC) and pseudorandom noise (PN) coding provide a means for spreading of the UWB data. The use of orthogonal frequency coding (OFC) increases the correlator processing gain …

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Worldwide Infrastructure For Neuroevolution: A Modular Library To Turn Any Evolutionary Domain Into An Online Interactive Platform, Paul Szerlip Jan 2015

Worldwide Infrastructure For Neuroevolution: A Modular Library To Turn Any Evolutionary Domain Into An Online Interactive Platform, Paul Szerlip

Electronic Theses and Dissertations

Across many scientific disciplines, there has emerged an open opportunity to utilize the scale and reach of the Internet to collect scientific contributions from scientists and non-scientists alike. This process, called citizen science, has already shown great promise in the fields of biology and astronomy. Within the fields of artificial life (ALife) and evolutionary computation (EC) experiments in collaborative interactive evolution (CIE) have demonstrated the ability to collect thousands of experimental contributions from hundreds of users across the glob. However, such collaborative evolutionary systems can take nearly a year to build with a small team of researchers. This dissertation introduces …

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Beam-Steerable And Reconfigurable Reflectarray Antennas For High Gain Space Applications, Kalyan Karnati Jan 2015

Beam-Steerable And Reconfigurable Reflectarray Antennas For High Gain Space Applications, Kalyan Karnati

Electronic Theses and Dissertations

Reflectarray antennas uniquely combine the advantages of parabolic reflectors and phased array antennas. Comprised of planar structures similar to phased arrays and utilizing quasi-optical excitation similar to parabolic reflectors, reflectarray antennas provide beam steering without the need of complex and lossy feed networks. Chapter 1 discusses the basic theory of reflectarray and its design. A brief summary of previous work and current research status is also presented. The inherent advantages and drawbacks of the reflectarray are discussed. In chapter 2, a novel theoretical approach to extract the reflection coefficient of reflectarray unit cells is developed. The approach is applied to …

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An Optimization Of Thermodynamic Efficiency Vs. Capacity For Communications Systems, Gregory Rawlins Jan 2015

An Optimization Of Thermodynamic Efficiency Vs. Capacity For Communications Systems, Gregory Rawlins

Electronic Theses and Dissertations

This work provides a fundamental view of the mechanisms which affect the power efficiency of communications processes along with a method for efficiency enhancement. Shannon's work is the definitive source for analyzing information capacity of a communications system but his formulation does not predict an efficiency relationship suitable for calculating the power consumption of a system, particularly for practical signals which may only approach the capacity limit. This work leverages Shannon's while providing additional insight through physical models which enable the calculation and improvement of efficiency for the encoding of signals. The proliferation of Mobile Communications platforms is challenging capacity …

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Arcpy Code, Mohammadhossein Alipour Jan 2015

Arcpy Code, Mohammadhossein Alipour

Streamflow Prediction under Extreme Data-scarcity

No abstract provided.

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Compendium Of Thermoviscoplasticity Modeling Parameters For Materials Under Non-Isothermal Fatigue, Nathan O'Nora Jan 2015

Compendium Of Thermoviscoplasticity Modeling Parameters For Materials Under Non-Isothermal Fatigue, Nathan O'Nora

HIM 1990-2015

Viscoplasticity models allow for the prediction of the inelastic behavior of materials, taking into account the rate-dependence. In order to model the response under non-isothermal conditions experienced by many components, such as those in turbomachinery, however, it is necessary to incorporate temperature-dependence. Additionally, for materials subjected to thermal shock, temperature rate-dependence is also important. The purpose of this research is to develop a method of determining Chaboche viscoplasticity parameters that allows for consistent behavior with changing temperature. A quartet of candidate materials, 304 stainless steel, IN617, DS GTD-111, and Ti6242S, were chosen for their applications in turbomachinery, such as gas …

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General Vector Explicit - Impact Time And Angle Control Guidance, Loren Robinson Jan 2015

General Vector Explicit - Impact Time And Angle Control Guidance, Loren Robinson

Electronic Theses and Dissertations

This thesis proposes and evaluates a new cooperative guidance law called General Vector Explicit - Impact Time and Angle Control Guidance (GENEX-ITACG). The motivation for GENEX-ITACG came from an explicit trajectory shaping guidance law called General Vector Explicit Guidance (GENEX). GENEX simultaneously achieves design specifications on miss distance and terminal missile approach angle while also providing a design parameter that adjusts the aggressiveness of this approach angle. Encouraged by the applicability of this user parameter, GENEX-ITACG is an extension that allows a salvo of missiles to cooperatively achieve the same objectives of GENEX against a stationary target through the incorporation …

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Enhanced Microwave Hyperthermia Using Nanoparticles, Maryory Urdaneta Jan 2015

Enhanced Microwave Hyperthermia Using Nanoparticles, Maryory Urdaneta

Electronic Theses and Dissertations

In this dissertation a study of enhanced hyperthermia for cancer treatment through the use of magnetic nanoparticles is presented. Hyperthermia has been in use for many years, as a potential alternative method in cancer treatment, and high frequency microwave radiation has been used successfully to raise the tumor temperature to around 42°C in superficial tumors without causing damage to surrounding healthy tissues. Magnetic fluid hyperthermia involves the use of magnetic nanoparticles injected into the tumor before exposure to microwave radiation. The magnetic energy in the nanoparticles is converted into heat allowing for a more rapid rise of temperature in the …

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Development Of 3d Vision Testbed For Shape Memory Polymer Structure Applications, Kenneth Thompson Jan 2015

Development Of 3d Vision Testbed For Shape Memory Polymer Structure Applications, Kenneth Thompson

Electronic Theses and Dissertations

As applications for shape memory polymers (SMPs) become more advanced, it is necessary to have the ability to monitor both the actuation and thermal properties of structures made of such materials. In this paper, a method of using three stereo pairs of webcams and a single thermal camera is studied for the purposes of both tracking three dimensional motion of shape memory polymers, as well as the temperature of points of interest within the SMP structure. The method used includes a stereo camera calibration with integrated local minimum tracking algorithms to locate points of interest on the material and measure …

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Reasoning Tradeoffs In Implicit Invocation And Aspect Oriented Languages, Jose Sanchez Salazar Jan 2015

Reasoning Tradeoffs In Implicit Invocation And Aspect Oriented Languages, Jose Sanchez Salazar

Electronic Theses and Dissertations

To reason about a program means to state or conclude, by logical means, some properties the program exhibits; like its correctness according to certain expected behavior. The continuous need for more ambitious, more complex, and more dependable software systems demands for better mechanisms to modularize them and reason about their correctness. The reasoning process is affected by the design decisions made by the developer of the program and by the features supported by the programming language used. Beyond Object Orientation, Implicit Invocation and Aspect Oriented languages pose very hard reasoning challenges. Important tradeoffs must be considered while reasoning about a …

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Cascaded Digital Refinement For Intrinsic Evolvable Hardware, Vignesh Thangavel Jan 2015

Cascaded Digital Refinement For Intrinsic Evolvable Hardware, Vignesh Thangavel

Electronic Theses and Dissertations

Intrinsic evolution of reconfigurable hardware is sought to solve computational problems using the intrinsic processing behavior of System-on-Chip (SoC) platforms. SoC devices combine capabilities of analog and digital embedded components within a reconfigurable fabric under software control. A new technique is developed for these fabrics that leverages the digital resources' enhanced accuracy and signal refinement capability to improve circuit performance of the analog resources' which are providing low power processing and high computation rates. In particular, Differential Digital Correction (DDC) is developed utilizing an error metric computed from the evolved analog circuit to reconfigure the digital fabric thereby enhancing precision …

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A Macro-Level Sustainability Assessment Framework For Optimal Distribution Of Alternative Passenger Vehicles, Nuri Onat Jan 2015

A Macro-Level Sustainability Assessment Framework For Optimal Distribution Of Alternative Passenger Vehicles, Nuri Onat

Electronic Theses and Dissertations

Although there are many studies focusing on the environmental impacts of alternative vehicle options, social and economic dimensions and trade-off relationships among all of these impacts were not investigated sufficiently. Moreover, most economic analyses are limited to life cycle cost analyses and do not consider macro-level economic impacts. Therefore, this thesis aims to advance the Life Cycle Sustainability Assessment literature and electric vehicle sustainability research by presenting a novel combined application of Multi Criteria Decision Making techniques with Life Cycle Sustainability Assessment for decision analysis. With this motivation in mind, this research will construct a compromise-programming model (multi-objective optimization method) …

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Life-Cycle Greenhouse Gas Emissions And Water Footprint Of Residential Waste Collection And Management Systems, Mousa Maimoun Jan 2015

Life-Cycle Greenhouse Gas Emissions And Water Footprint Of Residential Waste Collection And Management Systems, Mousa Maimoun

Electronic Theses and Dissertations

Three troublesome issues concerning residential curbside collection (RCC) and municipal solid waste (MSW) management systems in the United States motivated this research. First, reliance upon inefficient collection and scheduling procedures negatively affect RCC efficiency, greenhouse gas (GHG) emissions, and cost. Second, the neglected impact of MSW management practices on water resources. Third, the implications of alternative fuels on the environmental and financial performance of waste collection where fuel plays a significant rule. The goal of this study was to select the best RCC program, MSW management practice, and collection fuel. For this study, field data were collected for RCC programs …

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