Engineering Commons^™

Semi-Open Space And Micro-Environmental Control For Improving Thermal Comfort, Indoor Air Quality, And Building Energy Efficiency, Meng Kong

Dissertations - ALL

Local air delivery, heating, and cooling combined with local space partition and confinement (called semi-open space or SOS) have the potential to provide micro-environment that is tailored to the individual preference of the occupants, and hence increase the percentage of satisfied occupancy from currently 80% to near 100%. This research investigates the use of a micro-environmental control system (µX) and semi-open space (SOS) to efficiently provide the desired thermal comfort and air quality conditions for individual occupants while the ambient air temperature set-points were relaxed for reducing the overall energy consumption of the building. A computational fluid dynamics (CFD) model …

Online Learning With Bandits For Coverage, Mahmuda Rahman

Dissertations - ALL

With the rapid growth in velocity and volume, streaming data compels decision support systems to predict a small number of unique data points in due time that can represent a massive amount of correlated data without much loss of precision. In this work, we formulate this problem as the {\it online set coverage problem} and propose its solution for recommendation systems and the patrol assignment problem.

We propose a novel online reinforcement learning algorithm inspired by the Multi-Armed Bandit problem to solve the online recommendation system problem. We introduce a graph-based mechanism to improve the user coverage by recommended items …

Investigating The Interaction Of A Supersonic Single Expansion Ramp Nozzle And Sonic Wall Jet, Matthew Berry

Dissertations - ALL

For nearly 80 years, the jet engine has set the pace for aviation technology around the world. Complexity of design has compounded upon each iteration of nozzle development, while the rate of fundamental fluids knowledge struggles to keep up. The increase in velocities associated with supersonic jets, have exacerbated the need for flow physics research. Supersonic flight remains the standard for military aircraft and is being rediscovered for commercial use. With the addition of multiple streams, complex nozzle geometries, and airframe integration in modern aircraft, the flow physics rapidly become more difficult. As performance capabilities increase, so do the noise …

Detection, Diagnosis And Mitigation Of Malicious Javascript With Enriched Javascript Executions, Xunchao Hu

Dissertations - ALL

Malicious JavaScript has become an important attack vector for software exploitation attacks and imposes a severe threat to computer security. In particular, three major class of problems, malware detection, exploit diagnosis, and exploits mitigation, bring considerable challenges to security researchers. Although a lot of research efforts have been made to address these threats, they have fundamental limitations and thus cannot solve the problems.

Existing analysis techniques fall into two general categories: static analysis and dynamic analysis. Static analysis tends to produce inaccurate results (both false positive and false negative) and is vulnerable to a wide series of obfuscation techniques. Thus, …

Gas Phase Oxidation Of Levulinic Acid For The Production Of Maleic Anhydride Over Supported Vanadium Oxide Catalysts, Anargyros Chatzidimitriou

Dissertations - ALL

With continued depletion of fossil carbon, there is a need to utilize renewable sources of energy and consumer end products. In this context, we examine the aerobic oxidation of levulinic acid, a bio-based platform chemical derived from lignocellulosic biomass, to produce maleic anhydride, a valuable commodity chemical. This process is carried out over supported vanadium oxide catalysts. Yields as high as 71% of the theoretical maximum were achieved at 573 K over a vanadium oxide catalyst supported on SiO2. The exact mechanism underlying this transformation is complex, but our results suggest that maleic anhydride forms by the oxidative cleavage of …

Catalytic Synthesis Of Biodiesel Fuel Under Sub/Supercritical Conditions: Kinetics And Phase Behavior, Jiuxu Liu

Dissertations - ALL

In this thesis, transesterification of triglycerides and esterification of free fatty acids were executed under subcritical and supercritical alcohol conditions, and discussed in Chapter 2-5. The project was initiated by studying the phase behavior and kinetics of transesterification reactions under severe reaction conditions (T: 300-400 oC, P=200 bar), since those conditions were suggested and commonly used in the literature. At these conditions, triglycerides reacted with alcohol within minutes, and the oil-alcohol mixture formed a homogeneous phase which minimized the boundary mass transfer resistance. The composition change of the reaction mixture made the critical point of the system approach supercritical region …

A Life-Cycle Benefit/Cost Analysis Framework For Its Deployments, Xifan Chen

Dissertations - ALL

The primary objective of Transportation Systems Management and Operation (TSM&O) strategies, or Intelligent Transportation Systems (ITS) is to optimize the capacity of existing transportation infrastructure by reducing congestion. Over past decades, agencies and researchers investigated the use of various strategies such as deployment of adaptive traffic control systems (ATCS), ramp metering systems (RMS), surveillance through closed circuit TV (CCTV) cameras, and information sharing systems to achieve this objective. Life Cycle Agency Cost Agency Analysis (LCCA) of various alternative intelligent transportation strategies has received particular attention to identify the strategy with the lowest cost. However, increasing concerns over the impacts of …

Ensemble Methods For Anomaly Detection, Zhiruo Zhao

Dissertations - ALL

Anomaly detection has many applications in numerous areas such as intrusion detection, fraud detection, and medical diagnosis. Most current techniques are specialized for detecting one type of anomaly, and work well on specific domains and when the data satisfies specific assumptions.

We address this problem, proposing ensemble anomaly detection techniques that perform well in many applications, with four major contributions: using bootstrapping to better detect anomalies on multiple subsamples, sequential application of diverse detection

algorithms, a novel adaptive sampling and learning algorithm in which the anomalies are iteratively examined, and improving the random forest algorithms for detecting anomalies in streaming …

Vortex Detection And Tracking In Massively Separated And Turbulent Flows, Yangzi Huang

Dissertations - ALL

The vortex produced at the leading edge of the wing, known as the leading edge vortex (LEV), plays an important role in enhancing or destroying aerodynamic force, especially lift, upon its formation or shedding during the flapping flight of birds and insects. In this thesis, we integrate multiple new and traditional vortex identification approaches to visualize and track the LEV dynamics during its shedding process. The study is carried out using a 2D simulation of a flat plate undergoing a 45 degree pitch-up maneuver. The Eulerian 𝛤1 function and 𝑄 criterion are used along with the Lagrangian coherent structures (LCS) …

Oxygen Transport Membrane Reactors For Oxy-Fuel Combustion And Carbon Capture Purposes, Ryan Falkenstein-Smith

Dissertations - ALL

This thesis investigates oxygen transport membrane reactors (OTMs) for the application of oxy-fuel combustion. This is done by evaluating the material properties and oxygen permeability of different OTM compositions subjected to a variety of operating conditions. The scope of this work consists of three components: (1) evaluate the oxygen permeation capabilities of perovskite-type materials for the application of oxy-fuel combustion; (2) determine the effects of dual-phase membrane compositions on the oxygen permeation performance and membrane characteristics; and (3) develop a new method for estimating the oxygen permeation performance of OTMs utilized for the application of oxy-fuel combustion.

SrSc0.1Co0.9O3-δ (SSC) is …

Design Of Tribologically Enhanced Polymeric Materials For Biomedical Applications, Allen Osaheni

Dissertations - ALL

Anytime two surfaces are in normal contact, accompanied by tangential motion, there is potential for deterioration of one or both surfaces. Gradual wear, or the removal of surface material, is typically an undesirable event. Therefore, the need for lubrication arises to minimize the amount of shear stress that develops between opposing surfaces. This reduction in shear stress is characterized by the coefficient of friction (COF). Friction is one of the primary subjects of interest in tribology, the science of the friction and wear of articulating surfaces.

A number of fascinating tribological systems can be found in nature. One example which …

Associative Pattern Recognition For Biological Regulation Data, Yiou Xiao

Dissertations - ALL

In the last decade, bioinformatics data has been accumulated at an unprecedented rate, thanks to the advancement in sequencing technologies. Such rapid development poses both challenges and promising research topics. In this dissertation, we propose a series of associative pattern recognition algorithms in biological regulation studies. In particular, we emphasize efficiently recognizing associative patterns between genes, transcription factors, histone modifications and functional labels using heterogeneous data sources (numeric, sequences, time series data and textual labels).

In protein-DNA associative pattern recognition, we introduce an efficient algorithm for affinity test by searching for over-represented DNA sequences using a hash function and modulo …

Design, Synthesis And Study Of Thermomechanically Active Polymer Networks Based On Latent Crosslinking Of Semicrystalline Polymers, Wenbin Kuang

Dissertations - ALL

Demand has arisen rapidly for smart materials in the world of the need to develop and understand new functional products like plastics, rubber, adhesives, fibers, and coatings. Such products are essentially composed of polymers, large molecules of high molecular weight with homogeneous or various repeating units, which researchers term “macromolecules” that engender specific structural, morphological, and physical and mechanical properties. Those polymers with the capacity to change their configuration in accordance with environmental alteration are specifically referred to as shape memory polymers (SMPs), attracting much interest of study both academically and industrially. Herein, this dissertation aims at design, fabrication, and …

Accelerated Construction Of Roadways: Life Cycle Assessment And Environmental Impacts, Sudipta Ghorai

Dissertations - ALL

Sustainability refers to a long-term perspective of economic, social, and environmental progress, which not only addresses the present conditions but also includes the needs of future generations. The massive network of roadways in United States has the potential to contribute considerably towards achieving sustainability in the infrastructure sector. The “triple bottom line” of sustainability, if incorporated in roadway development projects, can address issues like climate change, environmental protection, funds optimization, and social equity. This study focuses on the life cycle assessment (LCA) of arterial improvement projects. Preservation treatments help in extending the remaining service life of roads; but at the …

Adsorption Of Iodine And Water On Silver-Exchanged Mordenite, Yue Nan

Dissertations - ALL

The reprocessing of used nuclear fuel to recover the fissile materials generates off gases including radioactive nuclides namely 3H (tritiated water, H3HO), 129I, 85Kr, 135Xe, and 14C. Due to its high quantity in off-gas streams and long half-life (1.59 million years), 129I removal from the off-gas streams is a significant objective of off-gas treatment.

129I retention by solid adsorbents was recognized a better strategy in comparison to liquid scrubbers due to the simplicity of system design and low cost. Among the studied adsorbents, reduced silver-exchanged mordenite (Ag0Z) was widely recognized as the state-of-art adsorbent for iodine removal. It has been …

Rectangular Waveguide Filled With Uniaxial Medium And Negative Resistance Enhanced Composite Right/Left-Handed Transmission Line, Kepei Sun

Dissertations - ALL

Two wave-guiding problems are treated in this work. The first part addresses the problem of a rectangular waveguide filled with a uniaxially anisotropic or uniaxial medium. Different orientations of the optic axis of the uniaxial medium are considered and the wave transmission and modal behaviors are investigated. When the optic axis is aligned with one of the coordinate axes, i. e., x, y, or z axis, the method of wave decomposition with respect to the optic axis orientation is proposed and the complete analytic solutions are presented and compared with conventional transverse-to-z solutions. When the optic axis is tilted but …

A Novel Approach To Near-Real Time Monitoring Of Ventilation Rate And Indoor Air Quality In Residential Houses, Achalu Kuma Tirfe

Dissertations - ALL

Physics-based infiltration models, like Lawrence Berkeley Laboratory (LBL) and Alberta Infiltration Model (AIM-2), have been used to predict infiltration rate in near real time. These models are constructed from the driving forces of wind and temperature difference across the building enclosure system, both of which cause pressure differences across the enclosure system for infiltration. The models incorporate other major factors like building leakage characteristics, distributions of openings, microenvironment conditions around the building enclosure as affected by building shields, topography and building shape. The accuracy of the models dependents on getting these factors right. However, these factors are specific for individual …

Algorithms And Theory For Robust Pca And Phase Retrieval, Huishuai Zhang

Dissertations - ALL

In this dissertation, we investigate two problems, both of which require the recovery of unknowns from measurements that are potentially corrupted by outliers. The first part focuses on the problem of \emph{robust principal component analysis} (PCA), which aims to recover an unknown low-rank matrix from a corrupted and partially-observed matrix.

The robust PCA problem, originally nonconvex itself, has been solved via a convex relaxation based approach \emph{principal component pursuit} (PCP) in the literature.

However, previous works assume that the sparse errors uniformly spread over the entire matrix and characterize the condition under which PCP guarantees exact recovery. We generalize these …

Information Theoretic Limits Of State-Dependent Networks, Yunhao Sun

Dissertations - ALL

We investigate the information theoretic limits of two types of state-dependent models in this dissertation. These models capture a wide range of wireless communication scenarios where there are interference cognition among transmitters. Hence, information theoretic studies of these models provide useful guidelines for designing new interference cancellation schemes in practical wireless networks.

In particular, we first study the two-user state-dependent Gaussian multiple access channel (MAC) with a helper. The channel is corrupted by an additive Gaussian state sequence known to neither the transmitters nor the receiver, but to a helper noncausally, which assists state cancellation at the receiver. Inner and …

Efficient Implementation Of Stochastic Inference On Heterogeneous Clusters And Spiking Neural Networks, Khadeer Ahmed

Dissertations - ALL

Neuromorphic computing refers to brain inspired algorithms and architectures. This paradigm of computing can solve complex problems which were not possible with traditional computing methods. This is because such implementations learn to identify the required features and classify them based on its training, akin to how brains function. This task involves performing computation on large quantities of data. With this inspiration, a comprehensive multi-pronged approach is employed to study and efficiently implement neuromorphic inference model using heterogeneous clusters to address the problem using traditional Von Neumann architectures and by developing spiking neural networks (SNN) for native and ultra-low power implementation. …

Wireless Throughput And Energy Efficiency Under Qos Constraints, Mustafa Ozmen

Dissertations - ALL

Mobile data traffic has experienced unprecedented growth recently and is predicted to grow even further over the coming years. As one of the main driving forces behind this growth, wireless transmission of multimedia content has significantly increased in volume and is expected to be the dominant traffic in data communications. Such wireless multimedia traffic requires certain quality-of-service (QoS) guarantees.

With these motivations, in the first part of the thesis, throughput and energy efficiency in fading channels are studied in the presence of randomly arriving data and statistical queueing constraints. In particular, Markovian arrival models including discrete-time Markov, Markov fluid, and …

Wireless Information And Power Transfer In Communication Networks: Performance Analysis And Optimal Resource Allocation, Tewodros Aklilu Zewde

Dissertations - ALL

Energy harvesting is considered as a prominent solution to supply the energy demand for low-power consuming devices and sensor nodes. This approach relinquishes the requirements of wired connections and regular battery replacements. This thesis analyzes the performance of energy harvesting communication networks under various operation protocols and multiple access schemes. Furthermore, since the radio frequency signal has energy, in addition to conveying information, it is also possible to power energy harvesting component while establishing data connectivity with information-decoding component. This leads to the concept of simultaneous wireless information and power transfer. The central goal of this thesis is to conduct …

Quantized Consensus By The Alternating Direction Method Of Multipliers: Algorithms And Applications, Shengyu Zhu

Dissertations - ALL

Collaborative in-network processing is a major tenet in the fields of control, signal processing, information theory, and computer science. Agents operating in a coordinated fashion can gain greater efficiency and operational capability than those perform solo missions. In many such applications the central task is to compute the global average of agents' data in a distributed manner. Much recent attention has been devoted to quantized consensus, where, due to practical constraints, only quantized communications are allowed between neighboring nodes in order to achieve the average consensus. This dissertation aims to develop efficient quantized consensus algorithms based on the alternating direction …

Risk-Aware Navigation For Uav Digital Data Collection, Zhi Xing

Dissertations - ALL

This thesis studies the navigation task for autonomous UAVs to collect digital data in a risky environment. Three problem formulations are proposed according to different real-world situations. First, we focus on uniform probabilistic risk and assume UAV has unlimited amount of energy. With these assumptions, we provide the graph-based Data-collecting Robot Problem (DRP) model, and propose heuristic planning solutions that consist of a clustering step and a tour building step. Experiments show our methods provide high-quality solutions with high expected reward. Second, we investigate non-uniform probabilistic risk and limited energy capacity of UAV. We present the Data-collection Problem (DCP) to …

Design, Material And Surgical Assembly Effects On Fretting Corrosion Behavior Of Modular Tapers In Orthopedic Implants, David Pierre

Dissertations - ALL

Mechanically assisted crevice corrosion (MACC) has become a significant problem in the orthopedic device industry, particularly in modular devices with metal-on-metal (MoM) tapered interfaces. Oxide film abrasion, leading to fretting corrosion in the presence of a crevice, accelerates the corrosion process and in some instances may lead to failure of the implant. Failure is defined as the need for revision surgery. The basic processes of oxide film abrasion and repassivation, and the associated effects (chemical, transport, mechanical and electrical) of these processes have been well described and studied over time.

Despite these advancements, there is much that is still not …

Transitioning To Sustainable Civil Infrastructure Systems: Green Stormwater Management And Engineering Design Thinking, Carli Denyse Flynn

Dissertations - ALL

Green infrastructure has been endorsed by many practitioners and organizations as a more sustainable approach to stormwater management. Decisions on how to best design municipal green infrastructure systems can be complicated by factors such as uncertainties about the performance and public acceptance of particular technologies. Thus, deciding how to design sustainable stormwater management systems requires engineers not only to reflect upon the fundamental principles used to conceptualize their designs, but also to consider how a broad array of social, economic, and environmental factors both influence and are influenced by their work.

This thesis examines factors that influence the design and …

Computer Vision Algorithms For Mobile Camera Applications, Koray Ozcan

Dissertations - ALL

Wearable and mobile sensors have found widespread use in recent years due to their ever-decreasing cost, ease of deployment and use, and ability to provide continuous monitoring as opposed to sensors installed at fixed locations. Since many smart phones are now equipped with a variety of sensors, including accelerometer, gyroscope, magnetometer, microphone and camera, it has become more feasible to develop algorithms for activity monitoring, guidance and navigation of unmanned vehicles, autonomous driving and driver assistance, by using data from one or more of these sensors. In this thesis, we focus on multiple mobile camera applications, and present lightweight algorithms …

The Scalable And Accountable Binary Code Search And Its Applications, Qian Feng

Dissertations - ALL

The past decade has been witnessing an explosion of various applications and devices.

This big-data era challenges the existing security technologies: new analysis techniques

should be scalable to handle “big data” scale codebase; They should be become smart

and proactive by using the data to understand what the vulnerable points are and where

they locate; effective protection will be provided for dissemination and analysis of the data

involving sensitive information on an unprecedented scale.

In this dissertation, I argue that the code search techniques can boost existing security

analysis techniques (vulnerability identification and memory analysis) in terms of scalability and …

The Effects Of Simulated Inflammatory Conditions On The Corrosion And Fretting Corrosion Of Cocrmo Alloy, Yangping Liu

Dissertations - ALL

In vivo corrosion of CoCrMo alloy and its potential adverse effects on the body have been recognized as major concerns in recent years. While the underlying concepts of general and mechanically-assisted corrosion have been well documented, recent report of inflammatory cell-induced corrosion (ICIC) of CoCrMo alloy challenged traditional understanding of the relationship between biology and corrosion of hip implants. To better understand the role biology may play in the corrosion of CoCrMo-based implants, this study explored the mechanism of ICIC on CoCrMo alloy and investigated how simulated inflammatory (SI) conditions affected the electrochemistry, oxide film and fretting corrosion behavior of …

The Interacting Hydrologic Responses To Changing Climate, Watershed Physical Characteristics, River Regulation, And Land Development In The Northeastern United States, Rouzbeh Berton

Dissertations - ALL

In this dissertation, the scale-dependency of hydrologic responses due to changing climate and regime shifts of large-scale circulation patterns and their teleconnection patterns were evaluated using long-term precipitation and discharge records in sub-basins with no development, and extensive development and riverine impoundments of the Merrimack River watershed. The Merrimack (New Hampshire-Massachusetts) is a 13,000 km2 forested (67%) watershed located in the northeastern United States. The overarching goal of this dissertation was to assess hydrologic responses to the potential effects of changing climate in sub-basins experiencing a range of development in order to help guide sustainable water management in the Merrimack …