Digital Commons Network^™

Modeling Of Magnetic Field Driven Simultaneous Assembly, Rene David Rivero

Dissertations

The Magnetic Field Driven Simultaneous Assembly (MFDSA) is a method that offers a non-statistical and deterministic solution to the problem of assembly via batch processing; a hybrid of serial and parallel processing. The technique requires the use of electromagnets as well as soft and hard magnetic materials that are applied to devices and recesses respectively. The MFDSA approach offers the ability to check and correct errors in real-time and is capable of scalable, versatile, and high-yield integration.

Devices, coated with a layer of soft magnetic material, are moved from initial to final positions along predetermined pathways through the action of …

Face Recognition Using Multiple Features In Different Color Spaces, Zhiming Liu

Dissertations

Face recognition as a particular problem of pattern recognition has been attracting substantial attention from researchers in computer vision, pattern recognition, and machine learning. The recent Face Recognition Grand Challenge (FRGC) program reveals that uncontrolled illumination conditions pose grand challenges to face recognition performance. Most of the existing face recognition methods use gray-scale face images, which have been shown insufficient to tackle these challenges. To overcome this challenging problem in face recognition, this dissertation applies multiple features derived from the color images instead of the intensity images only.

First, this dissertation presents two face recognition methods, which operate in different …

Underwater Communication Via Particle Velocity Channels : Principles, Channel Models, And System Design, Huaihai Guo

Dissertations

A vector sensor is capable of measuring important non-scalar components of the acoustic field such as the particle velocity, which cannot be obtained by a single scalar pressure sensor. In the past few decades, extensive research has been conducted on the theory and design of vector sensors. On the other hand, underwater acoustic communication systems have been relying on scalar sensors only, which measure the pressure of the acoustic field. By taking advantage of the vector components of the acoustic field, such as the particle velocity, the vector sensor can be used for detecting the transmitted data. In this dissertation, …

Design Of Single-Carrier Frequency Domain Equalization (Sc-Fde) With Transmit Diversity For Wireless And Optical Communications, Kodzovi Acolatse

Dissertations

As the demand of wireless service is rising, there is a need to transmit high-speed packets over the wireless communication channel. Broadband data transmission over wireless channels commonly faces the challenges of multipath fading channels, which are both time and frequency selective. There is then a need to design transmission techniques that can combat the adverse effects of the channel, and enable reliable high data rate wireless services. Orthogonal frequency division multiplexing (OFDM) has become widely accepted primarily because of its robustness against frequency selective fading channels, but it suffers a number of drawbacks such as high peak-to-average power ratio …

Pattern Formation In Oscillatory Systems, Hui Wu

Dissertations

Synchronization is a kind of ordinary phenomenon in nature, the study of it includes many mathematical branches. Phase space is one of the most powerful inventions of modern mathematical science. There are two variables, the position and velocity, that can describe the 2-dimensional phase space system. For example, the state of pendulum may be specified by its position and its velocity, so its phase space is 2-dimensional. The state of the system at a given time has a unique corresponding point in the phase space. In order to describe the motion of an oscillator, we can talk about its motion …

Application Of Mass/Stiffness Eccentricity To Control Response Of Structures Subjected To Earthquake Ground Motion, Bakhtiar Feizi

Dissertations

This dissertation is driven by the concept that engaging more modes in the response of structures can be used to mitigate its translational dynamic response. One such an approach is to engage torsional modes through engineered eccentricity (mass/stiffness eccentricity), thus, introducing coupled translation-rotation response. This idea was first introduced in a paper published by MacBain and Spillers in 2004. As a follow up to the same idea this dissertation was an attempt to investigate and develop the theory concerning the application of mass/stiffness eccentricity to control the translational motion of structures subjected to earthquake ground motion.

Different discrete and continuous …

Radio-Derived Three-Dimensional Structure Of A Solar Active Region, Samuel D. Tun

Dissertations

Solar active regions are the source of the most violent events observed on the Sun, some of which have a direct impact to modern civilization. Efforts to understand and predict such events require determination of the three-dimensional distributions of density, temperature, and magnetic fields above such active regions. This thesis presents the structure of the solar atmosphere above active region AR 10923, observed on 2006 Nov 10, as deduced from multi-wavelength studies including combined microwave observations from the Very Large Array (VLA) and the Owens Valley Solar Array (OVSA). The VLA observations provide excellent image quality at a few widely …

Distributed Synchronization Algorithms For Wireless Sensor Networks, Nicola Varanese

Dissertations

The ability to distribute time and frequency among a large population of interacting agents is of interest for diverse disciplines, inasmuch as it enables to carry out complex cooperative tasks. In a wireless sensor network (WSN), time/frequency synchronization allows the implementation of distributed signal processing and coding techniques, and the realization of coordinated access to the shared wireless medium. Large multi-hop WSN's constitute a new regime for network synchronization, as they call for the development of scalable, fully distributed synchronization algorithms. While most of previous research focused on synchronization at the application layer, this thesis considers synchronization at the lowest …

Model Reference Control For Ultra-High Precision Positioning Systems, Lan Yu

Dissertations

Due to the increasing demands of high-density semiconductors, molecular biology, optoelectronics, and MEMS/NEMS in the past decades, control of ultra-high precision positioning using piezoelectricity has become an important area because of its high displacement resolution, wide bandwidth, low power consumption, and potential low cost. However, the relatively small displacement range limits its application. This work proposed a practical ultra-high precision piezoelectric positioning system with a complementary high displacement range actuation technology. Solenoids are low cost, high speed electromagnetic actuators which are commonly used in on-off mode only because of the inherent high nonlinear force-stroke characteristics and unipolar forces (push/pull) generated …

Non-Invasive Interventions Top Reduce Low Back Dysfunction, Nadi Atalla

Theses

This study aims to quantitatively evaluate the low back condition so that low back dysfunction can be identified and classified when measurements show a variance from the normal. The evaluation is done by using the hysteresis concept. In this study, subjects received two different types of treatment: massaging using a mechanical massager for ten minutes and manual massaging by a professional physician. Using the Automated Anatomic Torsion Monitor (A-ATM), the low back of the subject was evaluated before and after treatment. The change in Hysteresis Loop Area (HLA) was -12.5% for mechanical massaging and -15.7% for manual massaging. The negative …

Aminormotiffinder - A Graph Grammar Based Tool To Effectively Search A Minor Motifs In 3d Rna Molecules, Ankur Malhotra

Theses

RNA Motifs are three dimensional folds that play important role in RNA folding and its interaction with other molecules. They basically have modular structure and are composed of conserved building blocks dependent upon the sequence. Their automated in silico identification remains a challenging task. Existing motif identification tools does not correctly identify motifs with large structure variations. Here a “graph rewriting” based method is proposed to identify motifs in real three dimensional structures. The unique encoding of A Minor Searcher takes into consideration the non canonical base pairs and also multipairing of RNA structural motifs. The accuracy is demonstrated by …

Modeling Next Generation Air Traffic Control System With Petri Net, Hang Wu

Theses

The Federal Aviation Administration (FAA) is one of the largest Air Navigation Service Providers, managing air traffic for more than 15% of the world's airspace. Today's Air Traffic Control (ATC) system cannot meet the growth of the air traffic activities, which brings with more unprecedented delays. At the same time, Air Traffic Controllers are facing higher workload than ever before. The FAA has declared that the existing ATC system will transition to a new system known as “Free Flight”. “Free Flight” will change today's ATC system by giving pilots increased flexibility to choose and modify their routes in real time, …

Natural Selection On Mrna Secondary Structure And Its Correlation With Protein Functional Groups, Suresh Solaimuthu

Dissertations

Natural selection may occur at multiple levels of the biological hierarchy, including at the molecular level. It may occur on any phenotypic trait that evidences variation and that is heritable. This research uses computational methods to investigate whether the stability of the secondary structures of mRNAs has been the subject of natural selection.

The DNA sequence that codes for a particular target protein is only partially determined by that protein, since the redundancy of the genetic code permits multiple possible synonymous codons for each peptide. An RNA transcript of a DNA protein template (gene) folds back on itself through complementary …

Design Of Novel Drug Delivery System And Optimal Dosage Regimens, Kwang Seok Kim

Dissertations

Three representative drug delivery systems were analyzed to emphasize the roles of mathematical models and computer-aided simulations in pharmaceutical research. In the first project, a protocol was developed so that the optimal regimen, consisting of the intravenous boluses and subsequent infusion of theophylline, could be obtained once information on the pharmacokinetics became available. The method was based on a two-compartment model of the human body. A module was created and posted on a website for free access. The second project dealt with the transdermal heat-assisted delivery of corticosterone. Heat conduction and drug diffusion through the patch and the skin were …

Study Of Magnetic Helicity In Solar Active Regions And Its Relationship With Solar Eruptions, Sung-Hong Park

Dissertations

It is generally believed that eruptive phenomena in the solar atmosphere such as solar flares and coronal mass ejections (CMEs) occur in solar active regions with complex magnetic structures. The magnetic complexity is quantified in terms of twists, kinks, and interlinkages of magnetic field lines. Magnetic helicity has been recognized as a useful measure for these properties of a given magnetic field system. Magnetic helicity studies have been naturally directed to the energy buildup and instability leading to solar eruptions. However, in spite of many years of study, detailed aspects of initiation mechanisms of eruptive events are still not well …

Synoptic Variability Of A Cir-Driven Open-Closed Boundary During Solar Minimum, Kevin Urban

Theses

The year 2008 marked a historically quiet period of solar activity during the declining phase of solar cycle 23. Such quiet time has permitted researchers to clearly distinguish the spectral signature of a corotating interaction region’s (CIR) impact on the open-closed boundary (OCB) of the magnetosphere in the southern hemisphere’s auroral zone. By using the PENGUIn AGOs network of ground-based magnetometers on the Antarctic continent, the synoptic behavior of the OCB during a CIR-driven magnetic storm has been studied. Observations were compared with results provided by the BATSRUS space weather model. It is shown that such synoptic magnetometer data sets …

A Numerical Study On The Propagation And Interaction Of Strongly Nonlinear Solitary Waves, Qiyi Zhou

Dissertations

We study numerically a strongly nonlinear long wave model for surface gravity waves propagating in both one and two horizontal dimensions. This model often referred to as the Su-Gardner or Green-Naghdi equations can be derived from the Euler equations under the assumption that the ratio between the characteristic wavelength and water depth is small, but no assumption on the wave amplitude is required. We first generalize the model to describe large amplitude one-dimensional solitary waves in the presence of background shear of constant vorticity. After computing the solitary wave solution of the strongly nonlinear model, the interaction between two solitary …

Computational Methods For Two-Phase Flow With Soluble Surfactant, Kuan Xu

Dissertations

A mathematical model is formulated and solved for the two-phase flow of a viscous drop or inviscid bubble in an immiscible, viscous surrounding fluid in the zero Reynold's number or Stokes flow limit. A surfactant that is present on the interface is also soluble in the exterior fluid, and the drop is deformed by an imposed linear flow. The geometry is two-dimensional and Cartesian.

The dissolved surfactant is considered in the physically realistic limit of large bulk Péclet number. That is, it convects and diffuses as a passive scalar in the bulk flow where the ratio of its convection to …

Atomic And Electronic Structure Studies Of Nano-Structured Systems : Carbon And Related Materials, Sumit Saxena

Dissertations

Modeling in the framework of density functional theory has been conducted on carbon nanotubes and graphene nano-structures. The results have been extended to non-carbon systems such as boron nanostructures. Computational studies are complemented by experimental methods to refine the structural models and obtain a better understanding of the electronic structure.

It is observed that the zigzag edged bilayered graphene nanoribbons are highly unstable as compared to their armchair counterparts. A novel approach has been proposed for the patterning of chirality/diameter controlled single walled carbon nanotubes. Nanotube formation is found to be assisted by edge ripples along with the intrinsic edge …

The Public Understanding Of Climate Change : A Case Study Of Taiwanese Youth, Shih-Yun Kuo

Dissertations

Global climate change is likely to be the most challenging environmental dilemma of the 21st century because its impacts on ecosystems and human society are transnational in scale and long term in scope. Due to its high scientific complexity and uncertainty and high political and economic sensitivity, mitigating the problem will require interdisciplinary cooperation and collective and sustained efforts on the part of all nations. Sufficient domestic support from both government and the lay public will not only be significant to the success of an international climate regime, but also crucial to the effectiveness of potential domestic climate policies.

Such …

The Floating Contract Between Risk-Averse Supply Chain Partners In A Volatile Commodity Price Environment, Mojisola Kike Otegbeye

Dissertations

In this dissertation, two separate but closely related decision making problems in environments of volatile commodity prices are addressed. In the first problem, a risk-averse commodity user's purchasing policy and his risk-neutral supplier's pricing decision, where the user can purchase his needs through contract with his supplier as well as directly from the spot market, are analyzed. The commodity user is assumed to be the supplier's sole client, and the supplier can always expand capacity, at a cost to the user, to accommodate the user's demand in excess of initially reserved capacity.

In the more generalized second problem, both parties …

New Data Structures, Models, And Algorithms For Real-Time Resource Management, Xinfa Hu

Dissertations

Real-time resource management is the core and critical task in real-time systems. This dissertation explores new data structures, models, and algorithms for real-time resource management.

At first, novel data structures, i.e., a class of Testing Interval Trees (TITs), are proposed to help build efficient scheduling modules in real-time systems. With a general data structure, i.e., the TIT* tree, the average costs of the schedulability tests in a wide variety of real-time systems can be reduced. With the Testing Interval Tree for Vacancy analysis (TIT-V), the complexities of the schedulability tests in a class of parallel/distributed real-time systems can be effectively …

Constitutive Modeling Of Glassy Memory Polymers, Mahesh Khanolkar

Dissertations

The aim of this research is to develop constitutive models for non-linear materials. Here, issues related for developing constitutive model for glassy shape memory polymers are addressed in detail. Shape memory polymers are novel material that can be easily formed into complex shapes, retaining memory of their original shape even after undergoing large deformations. The temporary shape is stable and return to the original shape is triggered by a suitable mechanism such heating the polymer above a transition temperature. Glassy shape memory polymers are called glassy because the temporary shape is fixed by the formation of a glassy solid, while …

Transport Mechanisms And Modeling Of Riser Reactor, Dawei Wang

Dissertations

Riser reactors are extensively employed in various industrial applications. In a riser reactor, the hydrodynamics is closely interacted with kinetic reactions. Common models for the performance prediction of riser reactors overlook this vital coupling effect, which not only miss the important reaction characteristics in the dense-phase transport regime of riser reactors but also misinterpret the kinetic properties via ad hoc adjustments. It is noted that the modeling of hydrodynamics in riser flows has major flaws in its predictability of phase transport in both dense-phase and accelerating regimes where most reactions occur. In addition, with the spray feeding of reactants at …

Optimizing Integrated Service For A Transit Route With Heterogeneous Demand, Yavuz Yusuf Ulusoy

Dissertations

The methodology developed in this dissertation attempts to optimize integrated service that minimizes the total cost, including user and supplier costs, of a transit route with heterogeneous demand. While minimizing total cost, a set of practical constraints, such as capacity, operable fleet size and frequency conservation, are considered.

The research problem is presented in three scenarios, consisting of various service patterns (e.g., all-stop, short-turn and express) under heterogeneous demand. A logit-based model was used to estimate passenger transfer demand. An exhaustive search method was developed to find the optimal solutions for a simplified transit route with six stops, and a …

Coupled Simulation Of Loading And Response Of Columns Under Extreme Events, Navid H. Allahverdi

Dissertations

Forces imparted to structural columns during blast-induced loading depends on the shape and size of columns as well as on the intensity of the blast. Column's geometry - i.e., shape and size - influences the flow field around the column and consequently the flow field determines forces experienced by the column The main objective of this research is to estimate the forces imparted to columns in a blast event through studying the air flow field around columns

In this study, the physics of shock wave reflection and rarefaction waves are reviewed with application to describing the air flow around columns …

Variance Reduction Techniques For Estimating Quantiles And Value-At-Risk, Fang Chu

Dissertations

Quantiles, as a performance measure, arise in many practical contexts. In finance, quantiles are called values-at-risk (VARs), and they are widely used in the financial industry to measure portfolio risk. When the cumulative distribution function is unknown, the quantile can not be computed exactly and must be estimated. In addition to computing a point estimate for the quantile, it is important to also provide a confidence interval for the quantile as a way of indicating the error in the estimate. A problem with crude Monte Carlo is that the resulting confidence interval may be large, which is often the case …

Modeling With Bivariate Geometric Distributions, Jing Li

Dissertations

This dissertation studied systems with several components which were subject to different types of failures. Systems with two components having frequency counts in the domain of positive integers, and the survival time of each component following geometric or mixture geometric distribution can be classified into this category. Examples of such systems include twin engines of an airplane and the paired organs in a human body. It was found that such a system, using conditional arguments, can be characterized as multivariate geometric distributions. It was proved that these characterizations of the geometric models can be achieved using conditional probabilities, conditional failure …

Exploiting The Concept Of Hysteresis In Ankle Dysfunction And Ankle Strengthening, Akshay Narendra Pujara

Theses

The ankle joint is an important part of the body which is responsible for normal gait cycle. Dorsiflexion, plantar flexion, inversion and eversion are four types of movements controlled by the ankle joint. All these movements are controlled by the ligaments and the muscles associated with the ankle. Disorders of these ligaments and muscles leads to ankle dysfunction.

The hysteresis concept was employed to determine if there is any ankle dysfunction. A recently developed device, the Ankle Torsion Monitor (AnTm) was employed to evaluate the viscoelasticity and stiffness of the ankle joint. The greater the hysteresis loop area (HLA) the …

Air Piston Approach To Wave Power Generation, Arun Ramadass

Theses

Scientists have calculated that, by tapping just 0.2% of the energy produced by the world's oceans we can provide for all the worlds current energy needs. It is generally accepted that a combination of traditional energy production methods, (oil, coal, gas, nuclear) mixed with a combination of renewable energy production approaches is the future in providing for an increasingly energy hungry world. Wind, solar and biomass have moved into the public arena only in the last few years.

The proposed patented device (US Patent No.: 7,468,563) Ocean Wave Energy Converter harnesses the energy of ocean waves by continually raising and …