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Electronic Theses and Dissertations

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Articles 1951 - 1980 of 4180

Full-Text Articles in Engineering

Thermodynamic Analysis And Optimization Of Supercritical Carbon Dioxide Brayton Cycles, Mahmood Mohagheghi Jan 2015

Thermodynamic Analysis And Optimization Of Supercritical Carbon Dioxide Brayton Cycles, Mahmood Mohagheghi

Electronic Theses and Dissertations

The power generation industry is facing new challenging issues regarding accelerating growth of electricity demand, fuel cost and environmental pollution. These challenges accompanied by concerns of energy resources becoming scarce necessitate searching for sustainable and economically competitive solutions to supply the future electricity demand. To this end, supercritical carbon dioxide (S-CO2) Brayton cycles present great promise particularly in high temperature concentrated solar power (CSP) and waste heat recovery (WHR) applications. With this regard, this dissertation is intended to perform thorough thermodynamic analyses and optimization of S-CO2 Brayton cycles for both of these applications. A modeling tool has been developed, which …

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Cyclic And Impact Resistance Of Frp Repaired Poles, Zainab Mohsin Jan 2015

Cyclic And Impact Resistance Of Frp Repaired Poles, Zainab Mohsin

Electronic Theses and Dissertations

Sign and signal structures involved in vehicular accidents are often partially damaged, and it is possible to repair them instead of replacing them, even when the extent and severity of the damage are substantial. The replacement of these poles is costly and involves interruption for pedestrians and traffic. Therefore, some trials were performed to retrofit these poles in-situ with low cost and short time. Previous research has substantiated that the damage can decrease the strength of the these structures with increasing the dent depth and the use of externally-bonded fiber-reinforced polymer (FRP) composites are beneficial to repair them. The composite …

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Post Conversion Correction Of Non-Linear Mismatches For Time Interleaved Analog-To-Digital Converters, Charna Parkey Jan 2015

Post Conversion Correction Of Non-Linear Mismatches For Time Interleaved Analog-To-Digital Converters, Charna Parkey

Electronic Theses and Dissertations

Time Interleaved Analog-to-Digital Converters (TI-ADCs) utilize an architecture which enables conversion rates well beyond the capabilities of a single converter while preserving most or all of the other performance characteristics of the converters on which said architecture is based. Most of the approaches discussed here are independent of architecture; some solutions take advantage of specific architectures. Chapter 1 provides the problem formulation and reviews the errors found in ADCs as well as a brief literature review of available TI-ADC error correction solutions. Chapter 2 presents the methods and materials used in implementation as well as extend the state of the …

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Inverse-Consistent Determination Of Young's Modulus Of Human Lung, Behnaz Seyfi Noferest Jan 2015

Inverse-Consistent Determination Of Young's Modulus Of Human Lung, Behnaz Seyfi Noferest

Electronic Theses and Dissertations

Human lung undergoes respiration-induced deformation due to sequential inhalation and exhalation. Accurate determination of lung deformation is crucial for tumor localization and targeted radiotherapy in patients with lung cancer. Numerical modeling of human lung dynamics based on underlying physics and physiology enables simulation and virtual visualization of lung deformation. Dynamical modeling is numerically complicated by the lack of information on lung elastic behavior, structural heterogeneity as well as boundary constrains. This study integrates physics-based modeling and image-based data acquisition to develop the patient-specific biomechanical model and consequently establish the first consistent Young's modulus (YM) of human lung. This dissertation has …

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Agent-Based And System Dynamics Hybrid Modeling And Simulation Approach Using Systems Modeling Language, Asli Soyler Akbas Jan 2015

Agent-Based And System Dynamics Hybrid Modeling And Simulation Approach Using Systems Modeling Language, Asli Soyler Akbas

Electronic Theses and Dissertations

Agent-based (AB) and system dynamics (SD) modeling and simulation techniques have been studied and used by various research fields. After the new hybrid modeling field emerged, the combination of these techniques started getting attention in the late 1990's. Applications of using agent-based (AB) and system dynamics (SD) hybrid models for simulating systems have been demonstrated in the literature. However, majority of the work on the domain includes system specific approaches where the models from two techniques are integrated after being independently developed. Existing work on creating an implicit and universal approach is limited to conceptual modeling and structure design. This …

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Catalytic Role Of Boron Nitride In The Thermal Decomposition Of Ammonium Perchlorate, Kevin Grossman Jan 2015

Catalytic Role Of Boron Nitride In The Thermal Decomposition Of Ammonium Perchlorate, Kevin Grossman

Electronic Theses and Dissertations

The decomposition of Ammonium Perchlorate (AP), a strong oxidizer used in solid rocket propellant, is widely studied in an attempt to increase the burn characteristics of propellants. Many materials have been shown to catalyze its decomposition, but little is known about the mechanism by which AP decomposition becomes catalyzed. In this study, Boron Nitride (BN) nanostructures, a material previously unknown to act as a catalyst, is studied. The decomposition reaction is studied by thermo-gravimetric analysis / differential scanning calorimetry, X-ray photoelectron spectroscopy, fourier transform infrared spectroscopy, transmission electron microscopy and scanning electron microscopy. The goal of this study is to …

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Low Absorption Liquid Crystal Materials For Midwave Infrared, Amy Creekmore Jan 2015

Low Absorption Liquid Crystal Materials For Midwave Infrared, Amy Creekmore

Electronic Theses and Dissertations

Liquid crystal is an amazing class of soft matters with applications spanning from visible, infrared, millimeter wave, to terahertz. In addition to direct-view displays and projection displays, liquid crystal is also widely used in adaptive optics, tunable-focus lens, and laser beam steering. Although the visible region has well developed materials and mixtures for the vast variety of applications, the midwave infrared (MWIR) region of the electromagnetic spectrum invites much development as only a few materials have been developed with these applications in mind. Unlike visible region, the major challenge for mid-wave infrared liquid crystal is inherently large absorption loss. To …

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Towards Closed-Loop Deep Brain Stimulation: Behavior Recognition From Human Stn, Soroush Niketeghad Jan 2015

Towards Closed-Loop Deep Brain Stimulation: Behavior Recognition From Human Stn, Soroush Niketeghad

Electronic Theses and Dissertations

Deep brain stimulation (DBS) provides significant therapeutic benefit for movement disorders such as Parkinson’s disease (PD). Current DBS devices lack real-time feedback (thus are open loop) and stimulation parameters are adjusted during scheduled visits with a clinician. A closed-loop DBS system may reduce power consumption and side effects by adjusting stimulation parameters based on patient’s behavior. Thus behavior detection is a major step in designing such systems. Various physiological signals can be used to recognize the behaviors. Subthalamic Nucleus (STN) Local field Potential (LFP) is a great candidate signal for the neural feedback, because it can be recorded from the …

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Finding Consensus Energy Folding Landscapes Between Rna Sequences, Joshua Burbridge Jan 2015

Finding Consensus Energy Folding Landscapes Between Rna Sequences, Joshua Burbridge

Electronic Theses and Dissertations

In molecular biology, the secondary structure of a ribonucleic acid (RNA) molecule is closely related to its biological function. One problem in structural bioinformatics is to determine the two- and three-dimensional structure of RNA using only sequencing information, which can be obtained at low cost. This entails designing sophisticated algorithms to simulate the process of RNA folding using detailed sets of thermodynamic parameters. The set of all chemically feasible structures an RNA molecule can assume, as well as the energy associated with each structure, is called its energy folding landscape. This research focuses on defining and solving the problem of …

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Research On Improving Reliability, Energy Efficiency And Scalability In Distributed And Parallel File Systems, Junyao Zhang Jan 2015

Research On Improving Reliability, Energy Efficiency And Scalability In Distributed And Parallel File Systems, Junyao Zhang

Electronic Theses and Dissertations

With the increasing popularity of cloud computing and "Big data" applications, current data centers are often required to manage petabytes or exabytes of data. To store this huge amount of data, thousands or tens of thousands storage nodes are required at a single site. This imposes three major challenges for storage system designers: (1) Reliability---node failure in these datacenters is a normal occurrence rather than a rare situation. This makes data reliability a great concern. (2) Energy efficiency---a data center can consume up to 100 times more energy than a standard office building. More than 10% of this energy consumption …

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Adaptive Architectural Strategies For Resilient Energy-Aware Computing, Rizwan Arshad Ashraf Jan 2015

Adaptive Architectural Strategies For Resilient Energy-Aware Computing, Rizwan Arshad Ashraf

Electronic Theses and Dissertations

Reconfigurable logic or Field-Programmable Gate Array (FPGA) devices have the ability to dynamically adapt the computational circuit based on user-specified or operating-condition requirements. Such hardware platforms are utilized in this dissertation to develop adaptive techniques for achieving reliable and sustainable operation while autonomously meeting these requirements. In particular, the properties of resource uniformity and in-field reconfiguration via on-chip processors are exploited to implement Evolvable Hardware (EHW). EHW utilize genetic algorithms to realize logic circuits at runtime, as directed by the objective function. However, the size of problems solved using EHW as compared with traditional approaches has been limited to relatively …

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Droplet Impact On Liquid Pools: Secondary Droplets Formation From Rayleigh Jet Break-Up And Crown Splash, Eduardo Castillo Orozco Jan 2015

Droplet Impact On Liquid Pools: Secondary Droplets Formation From Rayleigh Jet Break-Up And Crown Splash, Eduardo Castillo Orozco

Electronic Theses and Dissertations

This work aims to study the impact of a droplet on liquid pools of the same fluid to understand the formation of secondary drops from the central jet and crown splash that occur after the impact. The impact of droplets on a deep pool has applications in cleaning up oil spill, spray cooling, painting, inkjet printing and forensic analysis, relying on the changes in properties such as viscosity, interfacial tension and density. Despite the exhaustive research on different aspects of droplet impact, it is not clear how liquid properties can affect the instabilities leading to the Rayleigh jet breakup and …

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Adsorption Behaviour Of Polyacrylic Acid On Cerium Oxide Nanostructures: Experimental And Predictive Model, Ali Haghighat Mesbahi Jan 2015

Adsorption Behaviour Of Polyacrylic Acid On Cerium Oxide Nanostructures: Experimental And Predictive Model, Ali Haghighat Mesbahi

Electronic Theses and Dissertations

Cerium oxide-based slurries are crucial for chemical mechanical polishing (CMP) in electronic industry. For these slurry systems, poly(acrylic acid) (PAA) is heavily utilized to provide colloidal stability. Some of the important parameters in the colloid stability are molecular weight (MW) and concentration of stabilizer, size of the nanoparticle in the slurry and the pH of system. By determining the colloidal stability of a discrete number of slurry formulations and relating these to certain slurry component parameters, a possible model can be produced to predict the influence of these parameters on the particle stability. Direct quantification of colloidal stability is difficult, …

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Examining Multiple Approaches For The Transferability Of Safety Performance Functions, Ahmed Tarek Ahmed Farid Jan 2015

Examining Multiple Approaches For The Transferability Of Safety Performance Functions, Ahmed Tarek Ahmed Farid

Electronic Theses and Dissertations

Safety performance functions (SPFs) are essential in road safety since they are used to predict crash frequencies. They are commonly applied for detecting hot spots in network screening and assessing whether road safety countermeasures are effective. In the Highway Safety Manual (HSM), SPFs are provided for several crash classifications for several types of roadway facilities. The SPFs of the HSM are developed using data from multiple states. In regions where jurisdiction specific SPFs are not available, it is custom to adopt nationwide SPFs for crash predictions then apply a calibration factor. Yet, the research is limited regarding the application of …

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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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