Engineering Commons^™

Design And Stability Analysis Of High Performance Packet Switches, Zhen Guo

Dissertations

With the rapid development of optical interconnection technology, high-performance packet switches are required to resolve contentions in a fast manner to satisfy the demand for high throughput and high speed rates. Combined input-crosspoint buffered (CICB) switches are an alternative to input-buffered (IB) packet switches to provide high-performance switching and to relax arbitration timing for packet switches with high-speed ports.

A maximum weight matching (MWM) scheme can provide 100% throughput under admissible traffic for lB switches. However, the high complexity of MWM prohibits its implementation in high-speed switches. In this dissertation, a feedback-based arbitration scheme for CICB switches is studied, where …

Probabilistic Approaches To The Design Of Wireless Ad Hoc And Sensor Networks, Zhen Guo

Dissertations

The emerging wireless technologies has made ubiquitous wireless access a reality and enabled wireless systems to support a large variety of applications. Since the wireless self-configuring networks do not require infrastructure and promise greater flexibility and better coverage, wireless ad hoc and sensor networks have been under intensive research. It is believed that wireless ad hoc and sensor networks can become as important as the Internet. Just as the Internet allows access to digital information anywhere, ad hoc and sensor networks will provide remote interaction with the physical world.

Dynamics of the object distribution is one of the most important …

Dynamic Simulations Of Particle Suspensions Subjected To An External Electric-Field, Xianjin Jiang

Dissertations

A numerical method is performed to study the suspension of polarizable particles in nonconductive solvents subjected to external electric fields. Such particles experience both hydrodynamic and electrostatic interactions. The hydrodynamic force acting on the particles is determined using the Stokesian dynamics method under the assumption that the Reynolds number is much smaller than 1, while the electrostatic force is determined by differentiating the electrostatic energy of the suspension, which is computed from the induced particle dipoles. In addition, the multiple image method is used to compensate for the electrostatic force when two particles are close to each other. Because the …

Multilevel Adaptive Security System, Hongwei Li

Dissertations

Recent trends show increased demand for content-rich media such as images, videos and text in ad-hoc communication. Since such content often tends to be private, sensitive, or paid for, there exists a requirement for securing such information over resource constrained ad hoc networks. In this work, traditional data security mechanisms, existing ad hoc secure routing protocols and multilevel security are first reviewed. Then a new system, called the Multilevel Adaptive Security System, which incorporates the multilevel security concept at both the application layer and the network layer, is proposed to provide adaptive security services for data and routing processes.

MLASS …

Modeling, Design, And Fabrication Of Pulsed Fluidic Micro-Actuators, Max Roman

Dissertations

The forced vibration of a thin flexible plate or membrane in a sealed cavity with a small opening can cause fluid to be pumped into and out-of the cavity. At particular frequencies and amplitudes of vibration, a streaming of vortex rings can occur near the orifice. These vortex rings move under their own self-induced momentum. Downstream of the opening the rings ultimately break up and can form a fully developed jet. This work is dedicated to the analysis, design, and fabrication of electrostatic micro fluidic actuators, which use the pulsing mechanism described above to generate a fluid flow. Particle Image …

The Effects Of Aging On Cardiac Mechanics, Samuel C. Lieber

Dissertations

It is well established that the aging heart exhibits left ventricular (LV) diastolic dysfunction and changes in mechanical properties, which have been attributed to alterations in the extracellular matrix (ECM). The investigators tested the hypothesis that the mechanical properties of cardiac myocytes significantly change with aging thereby contributing to the LV diastolic dysfunction. Cellular mechanical properties were determined by indenting cells with an atomic force microscope (AFM). The indentation results were interpreted by modeling the AFM probe as a blunted cone and determining an apparent elastic modulus (B) with classical infinitesimal strain theory (CIST). A commercially available finite element software …

Mobile Ad Hoc Networks For Intelligent Systems, Zhigang Wang

Dissertations

Advances in wireless technology and portable computing along with demands for high user mobility have provided a major promotion toward the development of ad hoc networks. Mobile ad hoc networks feature dynamic topology, self-organization, limited bandwidth and battery power of a node. They do not rely on specialized routers for path discovery and traffic routing. Research on ad hoc networks has been extensively investigated in the past few years and related work has focused on many of the layers of the communications architecture.

This research intends to investigate applications of MANET for intelligent systems, including intelligent transportation system (ITS), sensor …

Design And Resource Management Of Reconfigurable Multiprocessors For Data-Parallel Applications, Xiaofang Wang

Dissertations

FPGA (Field-Programmable Gate Array)-based custom reconfigurable computing machines have established themselves as low-cost and low-risk alternatives to ASIC (Application-Specific Integrated Circuit) implementations and general-purpose microprocessors in accelerating a wide range of computation-intensive applications. Most often they are Application Specific Programmable Circuiits (ASPCs), which are developer programmable instead of user programmable. The major disadvantages of ASPCs are minimal programmability, and significant time and energy overheads caused by required hardware reconfiguration when the problem size outnumbers the available reconfigurable resources; these problems are expected to become more serious with increases in the FPGA chip size. On the other hand, dominant high-performance computing …

Flow-Oriented Anomaly-Based Detection Of Denial Of Service Attacks With Flow-Control-Assisted Mitigation, Sui Song

Dissertations

Flooding-based distributed denial-of-service (DDoS) attacks present a serious and major threat to the targeted enterprises and hosts. Current protection technologies are still largely inadequate in mitigating such attacks, especially if they are large-scale. In this doctoral dissertation, the Computer Network Management and Control System (CNMCS) is proposed and investigated; it consists of the Flow-based Network Intrusion Detection System (FNIDS), the Flow-based Congestion Control (FCC) System, and the Server Bandwidth Management System (SBMS). These components form a composite defense system intended to protect against DDoS flooding attacks. The system as a whole adopts a flow-oriented and anomaly-based approach to the detection …

Network Level Performance Of Differentiated Services (Diffserv) Networks, Li Zhu

Dissertations

The Differentiated Services (DiffServ) architecture is a promising means of providing Quality of Service (QoS) in Internet. In DiffServ networks, three service classes, or Per-hop Behaviors (PHBs), have been defined: Expedited Forwarding (EF), Assured Forwarding (AF) and Best Effort (BE).

In this dissertation, the performance of DiffServ networks at the network level, such as end-to-end QoS, network stability, and fairness of bandwidth allocation over the entire network have been extensively investigated.

It has been shown in literature that the end-to-end delay of EF traffic can go to infinity even in an over-provisioned network. In this dissertation, a simple scalable aggregate …

Phase Transitions Of Poly (L-Lactic Acid) In Bulk And In Solution, Jing Zhang

Dissertations

Poly(L-lactic acid) (PLLA) has been subject to intensive research in recent years because of its biodegradability. Applications of PLLA, such as porous tissue engineering scaffolds and excipients for controlled release, have been developed in the biomedical and pharmaceutical fields. The crystal structures and morphologies of this semicrystalline polyester are the underlying factors that determine the mechanical and degradation properties of PLLA.

A fundamental understanding of the development of crystal structures and morphologies during the phase transitions of PLLA in bulk and in solution is pursued in this dissertation. Synchrotron wide- and small-angle x-ray scattering (WAXS and SAXS) are adopted as …

Hfo2 As Gate Dielectric On Si And Ge Substrate, Reenu Garg

Dissertations

Hafnium oxide HfO₂ has been considered as an alternative to silicon dioxide SiO₂ in future nano-scale complementary metal-oxide-semiconductor (CMOS) devices since it provides the required capacitance at the reduced device size because of its high dielectric constant. HfO₂ films are currently deposited by various techniques. Many of them require high temperature annealing that can impact device performance and reliability.

In this research, electrical characteristics of capacitors with HfO₂ as gate dielectric deposited by standard thermal evaporation and e-beam evaporation on Si and Ge substrates were investigated. The dielectric constant of HfO₂ deposited by thermal evaporation …

Prediction Of Service Load Of Concrete Structures After Cracking Using Ultrasonic Technique, Xuezeng Wu

Dissertations

The objective of this study is to investigate the cracking behavior of fractured concrete structures and to introduce a new approach to assess their remaining service lives. A novel ultrasonic technique is utilized to detect crack propagation in notched beams of mortar, plain concrete and reinforced concrete. The study showed that crack growth and microcrack zone in cementitious composites can be quantitatively detected by the ultrasound technique.

To predict crack propagation during the fracture process in plain concrete, an effective compliance fracture model is proposed. A large fracture process zone is incorporated in the analytical model by means of an …

Experimental Study On Two-Dimensional Propagating Edge Flames: Cold Flow Modeling And Flame Spread Rate Measurements, Marcos Villa-Gonzalez

Theses and Dissertations

This thesis presents the results of an experimental study on two-dimensional, planar propagating edge flames. The results were generated using a new apparatus in which a thin stream of gaseous fuel is injected into a low-speed laminar wind tunnel thereby forming a flammable layer along the centerline. The fuel injector consists of aluminum airfoil with a thin slot in its trailing edge, from which fuel is injected. After the initial stratified fuel/air layer is developed, a flame is ignited near the tunnel outlet, and the flame spreads against the incoming air, toward the fuel source. Experiments were conducted with methane …

Settling-Time Improvements In Positioning Machines Subject To Nonlinear Friction Using Adaptive Impulse Control, Tim Hakala

Theses and Dissertations

A new method of adaptive impulse control is developed to precisely and quickly control the position of machine components subject to friction. Friction dominates the forces affecting fine positioning dynamics. Friction can depend on payload, velocity, step size, path, initial position, temperature, and other variables. Control problems such as steady-state error and limit cycles often arise when applying conventional control techniques to the position control problem. Studies in the last few decades have shown that impulsive control can produce repeatable displacements as small as ten nanometers without limit cycles or steady-state error in machines subject to dry sliding friction. These …

Direct Application Of The Least Action Principle To Solve (Human) Movement Dynamics Without Using Differential Equations Of Motion, Amitha Kumar

Theses

This thesis explores the numerical feasibility of solving motion 2-point boundary value problems (BVPs) by direct numerical minimization of the action without using the equations of motion (EOM) as an intermediate step. The proposed direct least action (DLA) approach using the downhill simplex method (DSM) is applied to both the single and double pendulum systems as beginning test problems. The solutions so obtained are compared to numerical solutions of the corresponding Lagrange BOM solved using a first order Euler algorithm for the same mechanical problems. The output path obtained by both of the methods essentially superimpose on each other.

Future …

Medical Equipment Planning And Construction Of A Interventional Neuroradiology Suite, Furqan Elahi

Theses

New York-Presbyterian Hospital is one of the most comprehensive university hospitals in the world, with leading specialists in every field of medicine. It is composed of two renowned medical centers, New York-Presbyterian Hospital/Columbia University Medical Center and New York-Presbyterian Hospital/Weill Cornell Medical Center. The hospital's strategic planning group identified the need to expand the Interventional Neuroradiology service that the hospital provides. This brought upon the need to form a committee to plan the construction of an Interventional Neuroradiology. The problem statement of this thesis is to prepare a best practices guideline from a clinical engineering perspective on constructing the three …

Doppler Ultrasound Technique Used To Determine The Blood Flow Viscosity In The Middle Cerebral Artery Of A Canine Animal Model, Raj P. Ganpath

Theses

The cerebral blood flow velocity in the middle cerebral artery of an canine animal model was measured using the Doppler Ultrasound technique. A transducer was designed with a 20 MHz piezoelectric crystal and used for the application. An in vitro calibration system was designed and machined for the purpose of testing and calibrating every transducer before using it in vivo. Preliminary tests included experiments on the in vitro system and measurement of blood flow velocity in the human wrist artery (metacarpal artery). The effect of using different transmission media (agarose and gelatin) was determined through the many in vitro and …

Online Clustering With Single-Pass Topology Based Fuzzy Clustering Algorithm, Abhishek Jaiantilal

Theses

Online clustering is of significant interest for real-time data analysis. Generic offline clustering methods such as K-Means, C-Means and others are computationally expensive. The computational burden of these methods increases non-linearly with the size of the data set. In addition these methods usually require a good amount of supervised knowledge yielding a non-unique solution. For real-time data analysis, there is an important tradeoff between accuracy and computational efficiency. An unsupervised one-pass clustering method that efficiently adapts to data distribution and evaluation is proposed. This method, Topology-Based Fuzzy Clustering (TFC), uses the topology of data to discover clusters. TFC uses the …

Modification Of Clays With Ionic Liquids For Polymer Nanocomponents, Neung Hyun Kim

Theses

In attempts to prepare nanofillers with enhanced compatibility with a polymer matrix, cationic and anionic clays susceptible to exchange of their interlamellar ions with a variety of other cations or anions, were selected.

In order to treat cationic clay, montmorillonite, which contains sodium ions as interlayer ions, reagents having cations differing in size and structure included three ionic liquids ([EMIM]⁺ [Br]^-, [HXMIM]⁺ [Cl]^-, and [Epty]⁺ [BF4]^-). Results indicated that cationic exchange did occur from aqueous solution as confirmed by FTIR, EDX, WAXS, TGA, and elemental analysis. WAXS indicated a significant increase …

Non-Invasive Monitoring Of Bone Health Using Ultrasound, Nashit Jahan Meem

Theses

Bone fractures are estimated to afflict everyone at least once in his/her lifetime. Monitoring this becomes crucial especially when it comes to athletes in order for them to safely resume their regular activities as soon as possible. Technologies currently employed are either very expensive or use harmful radiation.

Ultrasound can monitor bone fractures in a non-invasive manner, as discussed in United States Patent # 5143069. Three transducers are mounted over the test specimen. A pulse generator excites the transmitting receiver. The second receiver is mounted next to the transmitter and acts as a reference receiver that displays the response across …

A Study Of Steganography And Steganalysis, Nisant Nalla

Theses

Steganography is the art of hiding the fact that communication is taking place, by hiding information in other information. Steganalysis is the study of methods to detect the presence of hidden messages. The Steganography and Steganalysis are very much interdependent. The people in the Steganography domain try to develop stronger methods to hide data in different media. This spurs the discovery of new steganalysis methods which can break these Steganography methods. This is vital for the development of these fields. The internet has been growing by leaps and bounds. There is an increasing need for information security. It has been …

Qt Variability Calculation Using A Template Matching Algorithm And Power Spectral Analysis, Theodore Sami Rizkalla

Theses

ECG interval measurement and variability analysis has proven to be a useful tool in investigating autonomic nervous system function. Traditionally, the R to R interval has been the thrust of research conducted in this field. QT variability is another topic on which little research has been done.

This thesis uses an algorithm proposed by Dr. Berger, published in 2003. The algorithm stretches the template in the time domain, and composes a sum-squared error function, which is minimized to find the scaling factor for that beat. These scaling factors are compiled into an array, and an interpolated signal is generated of …

Demarcation Of Coding And Non-Coding Regions Of Dna Using Linear Transforms, Krithika Venkat

Theses

Deoxyribonucleic Acid (DNA) strand carries genetic information in the cell. A strand of DNA consists of nitrogenous molecules called nucleotides. Nucleotides triplets, or the codons, code for amino acids. There are two distinct regions in DNA, the gene and the intergenic DNA, or the junk DNA. Two regions can be distinguished in the gene- the exons, or the regions that code for amino acid, and the introns, or the regions that do not code for amino acid. The main aim of the thesis is to study signal processing techniques that help distinguish between the regions of the exons and the …

Impact Of Missed Beats On Heart Rate Variability Using Time-Frequency Analysis, Kilbrom T. Hailu

Theses

ECG recordings, especially during an exercise stress test, are exposed to artifacts. The source of artifacts can be due to technical problems, biological events and errors in the automatic detection. As a result missed beats, extra beats and ectopic beats can occur. In this study analysis of missed beats is performed using time-frequency analysis. Some of the patient's data had missed beats.

Fourier spectral analysis was first applied to the missed beats during the resting state. The impact of missed beats using Fourier spectral analysis is significant, especially, when the missed beats are in a row. The Fourier spectral analysis …

New Hybrid Automatic Repeat Request (Harq) Combining With Space Time Block Coding (Stbc) In Invariant And Variant Fading Channel, Guillem Ernest Malagarriga Vilella

Theses

Hybrid Automatic Repeat reQuest (HARQ) combining for space time block coding Multiple Input Multiple Output (MIMO) system consisting of N transmit antennas and M receive antennas (NxM) in a time invariant channel and in a time varying channel is proposed and its performance is analyzed. Based on the measured channel matrix, the receiver chooses the best retransmission order and communicated it to the transmitter.

The scheme, where this algorithm is performed, is a combination of a precombining HARQ scheme and the Multiple Alamouti Space-Time Block Coding (MASTBC), which is suitable for more than 2 transmit antennas. The combination of this …

Electrochemical Corrosion Testing Of Boronized And Unboronized Steels, Kranthi K. Pallegar

Theses

Boronizing is a thermo-chemical surface coating technique with which surface properties of materials are enhanced substantially. One of these properties is corrosion resistance. Corrosion resistance testing has been performed in many ways right from the traditional weight loss methods to the latest electrochemical techniques. These electrochemical techniques are more reliable and less time consuming and hence are widely accepted for corrosion testing in the industry.

In the present work, direct current (D.C) corrosion testing studies of both boronized and unboronized steels have been discussed. Three types of steels, AISI 1018, AISI 4340 and AISI 304 stainless steel, were considered for …

Boron Induced Surface Modification Of Transition Metals, Raghasudha Vangaveti

Theses

Boronizing is a thermo-chemical surface treatment of metals in which boron atoms diffuse into the metal substrate and form hard metallic borides. As a result of boronizing, several properties such as hardness, wear resistance, corrosion resistance, and high temperature oxidation resistance improve which make the metal substrate more suitable for industrial applications. These boronized parts are used in many industrial applications like ingot moulds, crucibles, biomedical implants, die-casting moulds, magnetic head applications, drawing dies etc.

The objective of this work was to investigate the influence of boronizing on the properties of transition metals. Three transition metals, tantalum, niobium and tungsten …

Indentation Fracture Of Bovine Cortical Bone: Acoustic Emission Technique, Ashkan Safari, Ger Reilly, Brendan Mccormack

Conference Papers

Indentation cutting may result in microcracking and main crack growth which was previously reported. In this study, we recorded the AE signals produced by cracking processes during cutting on cortical bone, measuring the cutting force and correlating between load-displacement curves and AE activities.

Cutting Rate Effect On Temperature During Cortical Bone Sawing, Hamid Khalili Parsa, Ger Reilly, Brendan Mccormack

Conference Papers

When bone is cut the occurrence of thermal damage to the bone is of major concern to the surgeon. If the temperature exceeds 44°C for longer than 1 min, bone repair is impaired (Eriksson et al, 1984) and necrosis may occur. Repeated use of cutting blades may reduce the cutting efficiency (Wevers et al, 1987; Toksvig-Larsen et al, 1992). Wevers et al also found that there is a greater force required to cut cortical bone using a blunt saw compared to new one.