Open Access. Powered by Scholars. Published by Universities.®

Engineering Commons™

Open Access. Powered by Scholars. Published by Universities.®

2015

Discipline
Institution
Keyword
Publication
Publication Type
File Type

Articles 6031 - 6060 of 7525

Full-Text Articles in Engineering

Low-Order Discrete Dynamical System For H2-Air Finite-Rate Combustion Process, Wenwei Zeng Jan 2015

Low-Order Discrete Dynamical System For H2-Air Finite-Rate Combustion Process, Wenwei Zeng

Theses and Dissertations--Mechanical and Aerospace Engineering

A low-order discrete dynamical system (DDS) for finite-rate chemistry of H2-air combustion is derived in 3D. Fourier series with a single wavevector are employed to represent dependent variables of subgrid-scale (SGS) behaviors for applications to large-eddy simulation (LES). A Galerkin approximation is applied to the governing equations for comprising the DDS. Regime maps are employed to aid qualitative determination of useful values for bifurcation parameters of the DDS. Both isotropic and anisotropic assumptions are employed when constructing regime maps and studying bifurcation parameters sequences. For H2-air reactions, two reduced chemical mechanisms are studied via the DDS. …

Go to article

Development Of Multifunctional Shape Memory Polymer And Shape Memory Polymer Composites, Sesha Spandana Pulla Jan 2015

Development Of Multifunctional Shape Memory Polymer And Shape Memory Polymer Composites, Sesha Spandana Pulla

Theses and Dissertations--Mechanical and Aerospace Engineering

Shape memory polymers (SMPs) are an emerging class of active polymers that can be used on a wide range of reconfigurable structures and actuation devices. The present study comprehensively examines the unconstrained shape recovery abilities of an epoxy-based SMP. In doing so, epoxy based SMP is synthesized and thermo-mechanically characterized. Results show that the present SMP exhibits excellent shape recoveries under unconstraint conditions, for a range of fixing strains and temperatures. Additionally, the stress-strain behavior of the SMP is determined to be nonlinear, finite deformation at all regions. The strain energy based models have been used to capture the complicate …

Go to article

Lightweight Silver Ink Printed Circular Ring Microstrip Patch Antenna For Wlan Applications, Bobak Beheshti Jan 2015

Lightweight Silver Ink Printed Circular Ring Microstrip Patch Antenna For Wlan Applications, Bobak Beheshti

Electrical Engineering

No abstract provided.

Go to article

Crash Frequency Analysis Of Left-Side Merging And Diverging Areas On Urban Freeway Segments: A Case Study Of I-75 Through Downtown Dayton, Ohio, Deogratias Eustace, Aline Aylo, Worku Y. Mergia Jan 2015

Crash Frequency Analysis Of Left-Side Merging And Diverging Areas On Urban Freeway Segments: A Case Study Of I-75 Through Downtown Dayton, Ohio, Deogratias Eustace, Aline Aylo, Worku Y. Mergia

Civil and Environmental Engineering and Engineering Mechanics Faculty Publications

This paper analyzes the effect of left- and right-side merging and diverging areas and other variables such as light condition, roadway pavement condition, drivers’ age and presence of construction work zones on the occurrence frequency of crashes. A 6.5-mile (10.5-km) section of I-75 that passes through downtown Dayton, Ohio was considered. The area of interest has a high traffic volume and consists of different geometric design challenges including closely spaced merging and diverging ramps. A four-year record of crash data (2005–2008) and a statistical modeling technique that assumes a negative binomial distribution on generalized linear models (GLMs) were used to …

Go to article

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 …

Go to article

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 …

Go to article

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 …

Go to article

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 …

Go to article

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, …

Go to article

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 …

Go to article

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 …

Go to article

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 …

Go to article

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. …

Go to article

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, …

Go to article

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 …

Go to article

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 …

Go to article

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 …

Go to article

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 …

Go to article

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) …

Go to article

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 …

Go to article

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 …

Go to article

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 …

Go to article

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 …

Go to article

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 …

Go to article

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 …

Go to article

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 …

Go to article

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 …

Go to article

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 …

Go to article

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 …

Go to article

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 …

Go to article

First Prev Next Last