Engineering Commons^™

Underwater Concrete, Dina Adel Nakhla

Archived Theses and Dissertations

Underwater structures represent a significant portion of concrete works worldwide. The utilization of various underwater concrete techniques has indeed minimized the use of costly dewatering processes. Such techniques include the use of special· equipment such as trernie concrete and preplaced aggregate technique. The incorporation of antiwashout admixtures has evolved as a method to minimize the washout of cement and fine particles. As for today, there exists relatively limited information regarding different underwater concreting techniques to facilitate feasible and adequate selection of appropriate methods. This work comprises a survey study and an experimental work to evaluate the impact of using the …

The Modified Hash Chain Sealed Bid Auction Protocol, Riham Hassan Abdel-Moneim

Archived Theses and Dissertations

No abstract provided.

Small Construction Firms, Samih Wahid Adly

Archived Theses and Dissertations

No abstract provided.

Integrated Construction Project Planning, Umar Farouk Dolleh

Archived Theses and Dissertations

No abstract provided.

Bs News

Building Services Engineering

No abstract provided.

Characterization Of Crbn Films Deposited By Ion Beam Assisted Deposition, S.M. Aouadi, F. Namavar, E. Tobin, N. Finnegan, R.T. Haasch, R. Nilchiani, Joseph A. Turner, S. L. Rohde

Nebraska Center for Materials and Nanoscience: Faculty Publications

This article reports on the growth and analysis of CrBN nanocrystalline materials using an ion beam assisted deposition process. In addition, this article addresses the utilization of spectroscopic ellipsometry for in situ analysis of ternary nitrides. Coatings, with a total thickness of 1.5 ±0.2 μm, were deposited at low temperatures (<200 °C) on silicon substrates using ion beam assisted deposition. These coatings were characterized postdeposition using x-ray diffraction (XRD), atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), visible-light spectroscopic ellipsometry (VIS-SE), infrared spectroscopic ellipsometry (IR-SE), and nanoindentation. The primary phases in the films were investigated using XRD. The surface morphology and nanocrystalline nature of the coatings (grain size of 5–7 nm) were deduced using AFM. The elemental composition and phase composition of the samples were determined from XPS and AES measurements and were subsequently deduced from the analysis of the VIS-SE data, and these correlated well. XPS, AES, and IR-SE revealed the crystal structure of the BN phase in the ternary compounds. The correlation of the results from these various techniques indicates that in situ SE may be a potential technique to control the growth of ternary nitride coatings in the future. The mechanical properties of the coatings were evaluated using nanohardness testing. The hardness and elastic modulus were measured to be 19–22 GPa and 250–270 GPa, respectively.

Microbiological, Limnological, And Nutrient Evaluations Of The Las Vegas Wash/Bay System, Thomas Piechota, David James, Jacimaria Batista, Penny Amy

Civil and Environmental Engineering and Construction Faculty Research

Presented here is a summary of an interdisciplinary study covering the various aspects of changes in water quality due to rapid urbanization in the Las Vegas Valley.

Forces On Permeable Conductors In Magnetic Fields, Lee W. Casperson

Electrical and Computer Engineering Faculty Publications and Presentations

It is often implied that the force density formula dF/dV = JXB is all that is required to calculate the force that would be experienced by any stationary current-carrying medium in a region of space containing a magnetic field. However, representations of this formula are not all compatible, and the methods of applying such formulas when the conductor or surrounding medium have permeabilities different from vacuum are not widely known. The simplest case that one might consider is that of a current-carrying wire in an otherwise uniform field. It appears that the experimental measurements corresponding to such a situation have …

Numerical Simulation Of Mechanofusion System For Dry Particle Coating Process, Wenliang Chen

Dissertations

A numerical simulation of the Meclianofusion device for dry particle coating is carried out using Discrete Element Method (DEM) technique. In dry particle coating, tiny sub-micron guest particles are coated onto larger micron sized host particles by using mechanical forces, which the Mechanofusion device provides. It consists of a rotating cylindrical chamber that contains the powder mixture, a stationary inner piece (which has a cylindrical surface at the end), and a fixed scraper blade, which prevents powder from caking against the chamber wall. The simulation studies are performed on two scales: system scale to investigate the particle-particle and particle system …

Application Of Chemical Kinetic Modeling To Improve Design And Performance Criteria For A Practical Incineration System, Charles A. Bass Jr.

Dissertations

In this study, detailed thermo-chemical kinetics with networked ideal reactor model were applied to simulate a practical combustion system -the Secondary Combustion Chamber (SCC) of the Rotary Kiln incineration Simulator (RKIS) at the EPA facility at Research Triangle Park, NC. The networked ideal model was developed using analysis of reactor geometry, temperature profile measurements, and SO₂ tracer data provided by EPA. A computer simulation of the networked model was developed using the CHEMKIN H library. A parallel effort considered the effects of non-ideal mixing on detailed thermo-kinetic, simulations. Specifically, an alternate approach was developed to solve the Partially Stirred …

Seismic Response Of Transformer Bushing Systems And Their Rehabilitation Using Frictional Pendulum System, Selahattin Ersoy

Dissertations

This thesis is concerned with the performance of electric power transformers and their attachments under earthquake loading. It begins with the description of the transformers, attached bushings, and some typical examples of substation failures in earthquake loading. This is followed by the development of finite element model of three different sizes of transformers. Finite element models consist of several thousand degrees of freedom and they are basic to this thesis. Some of the major findings from these models are utilized to derive a simplified model of a portion of a substation, The frictional pendulum system (a base isolation method) is …

On Performance Analysis And Implementation Issues Of Iterative Decoding For Graph Based Codes, Xuefei Wei

Dissertations

There is no doubt that long random-like code has the potential to achieve good performance because of its excellent distance spectrum. However, these codes remain useless in practical applications due to the lack of decoders rendering good performance at an acceptable complexity. The invention of turbo code marks a milestone progress in channel coding theory in that it achieves near Shannon limit performance by using an elegant iterative decoding algorithm. This great success stimulated intensive research oil long compound codes sharing the same decoding mechanism. Among these long codes are low-density parity-check (LDPC) code and product code, which render brilliant …

Experimental And Numerical Study Of Flow Characteristics And Segregation In Flow Enhanced Systems, Gregory James

Dissertations

In the study of granular materials, two major topics of importance are powder flow enhancement mechanisms and the flow characterization. This dissertation is involved with both of these topics. With respect to the powder flow enhancement, this study involves investigation of two types of flow enhancement methods. The first flow enhancement method examined is a novel method called the Magnetically Assisted Powder Flow (MAPF) method. In the MAPF, small magnetic particles and powders are placed in a test hopper. A mesh is placed at the bottom of the hopper to hold the magnetic particles while the powder is discharged through …

On The Data Hiding Theory And Multimedia Content Security Applications, Litao Gang

Dissertations

This dissertation is a comprehensive study of digital steganography for multimedia content protection. With the increasing development of Internet technology, protection and enforcement of multimedia property rights has become a great concern to multimedia authors and distributors. Watermarking technologies provide a possible solution for this problem.

The dissertation first briefly introduces the current watermarking schemes, including their applications in video,, image and audio. Most available embedding schemes are based on direct Spread Sequence (SS) modulation. A small value pseudo random signature sequence is embedded into the host signal and the information is extracted via correlation. The correlation detection problem is …

Inelastic Seismic Behavior Of Stiffening Systems : Multi-Span Simply-Supported (Msss) Bridges, Alireza Yazdani-Motlagh

Dissertations

Stiffening behavior can result from interaction between a structure (base system) and its surrounding environment as in the MSSS bridge soil-structure interaction. In this study, three MSSS bridge cases are parametrically analyzed and their dynamic characteristics and behavior are presented and discussed. Later, for investigating stiffening behavior, a simplified stiffening model is introduced and an extensive parametric study with more than 367,000 analyzed cases is performed. In the parametric study, different stiffening parameters (i.e., stiffness, strength, gap size, and mass), 41 strong motion records, and several damage criteria are considered and effects of the stiffening parameters variations on the dynamic …

Computation And Control Of Flow-Induced Noise Behind A Circular Cylinder Using An Acoustic Analogy Approach, Sirivit Taechajedcadarungsri

Dissertations

The computational aeroacoustics (CAA) research, which focuses on predicting acoustics by means of advanced numerical techniques, has recently gained a great deal of progress. In most applications, the prediction of both the sound source and its far-field propagation is necessary as required by regulations. Recently, powerful computers and reliable algorithms have allowed the prediction of far-field noise through the use of Computational Fluid Dynamics (CFD) data as near-field sound sources. One of the most useful analytical methods, used for the computation of noise, is Lighthill's acoustic analogy. The latter will be used in the present study.

Lighthill's acoustic analogy, combined …

Renegotiation Based Dynamic Bandwidth Allocation For Selfsimilar Vbr Traffic, Zafer Sahinoglu

Dissertations

The provision of QoS to applications traffic depends heavily on how different traffic types are categorized and classified, and how the prioritization of these applications are managed. Bandwidth is the most scarce network resource. Therefore, there is a need for a method or system that distributes an available bandwidth in a network among different applications in such a way that each class or type of traffic receives their constraint QoS requirements.

In this dissertation, a new renegotiation based dynamic resource allocation method for variable bit rate (VBR) traffic is presented. First, pros and cons of available off-line methods that are …

Elementary, Pressure Dependent Model For Combustion Of C1, C2 And Nitrogen Containing Hydrocarbons : Operation Of A Pilot Scale Incinerator And Model Comparison, Chad Sheng

Dissertations

A 140000 BTU/hr pilot scale incinerator has been constructed, tested and run; and an online sampling train capable of taking in situ data has been established. The continuous on-line analytical instruments include a CO analyzer, an NO/NOx analyzer and an 02 analyzer. In addition, two gas chromatographs with flame ionization detector are used to determine CH4, C2H2 + C2H4 and total hydrocarbon concentrations. Typical operating conditions are at an average 02 concentration of 6 - 8 %. The NO concentration ranged from 100 - 200 ppm. Approximately I ppm of CH.4 is also present at steady state operations.

The kinetic …

Mechanical Properties And Stress-Strain Behavior Of High Performance Concrete Under Uniaxial Compression, Pornchai Jiratatprasot

Theses

Many recent innovations in advanced concrete materials technology have made it possible to produce concrete with exceptional performance characteristics. High performance concrete (HPQ is defined as concrete that meets special performance and uniformity requirements that cannot always be achieved routinely by using conventional materials and normal mixing, placing, and curing practices. The importance of HPC to structural engineering is unquestionable. However, HPC is a relatively new material. Some results of research on conventional concrete are not entirely applicable. In this experiment, the main mechanical properties of HPC including compressive strength, modulus of elasticity, and Poisson's ratio were investigated and compared …

Qos Routing Source Routing Problems And Solutions, Ye Tian

Theses

The notion of Quality-of-Service has been proposed to capture qualitatively or quantitatively defined performance contracts between the service provider and the user applications. Integrated network services are designed to support Quality-of-Service (QoS). One of the primary goals for the integrated network services is to find the paths that satisfy given QoS requirements, namely QoS routing. The challenging issue in this area is to route packets subjected to multiple uncorrelated constraints because the problem is inherently NP-complete. This thesis studies the source routing heuristic approaches that bring the time complexity down to the polynomial-time for the multi-constrained path (MCP) problem. A …

Study Of The Trajectories Of Visually Guided Movement Of Unimanual And Bimanual Tasks, Deepthi Anand

Theses

Restitution of upper limb mobility following stroke is one of the major challenges facing clinicians in the country today. The complexity of performing skilled tasks with fine movements makes restitution of mobility all the more complex for rehabilitation specialists. Although several techniques have been evolved for, limited success with transfer of training from the clinical environment to functional performance clearly indicates a need for research and development in the area of upper extremity rehabilitation.

Bimanual coordination has recently surfaced as a novel and effective way to fast and lasting recovery. The success of bimanually coordinated training encourages a better understanding …

Thermochemistry Of Vinyl Alcohol And Vinyl Ether Radical And Kinetic Analysis Of Neopentyl Radical Reaction With Molecular Oxygen, Chol-Han Kim

Theses

Vinyl alcohols and ethers are important intermediates in low-temperature combustion processes, such as in the initial stages of combustion and in the atmospheric photochemical oxidation of hydrocarbons. Knowledge of the thermodynamic parameters for these species is central to understanding and predicting their reaction pathways, rate constants, and equilibrium constants. The rapid interconversion of conformers and the instability of vinyl alcohols and ethers lead to complexities in studies of these species.

In this work, enthalpy,ΔH°f 298, entropy, S°298, and heat capacities, Cp(T), are determined for vinyl alcohol and vinyl methyl ether and the radicals corresponding to loss of a H atom …

Introduction On Intrusion Detection Systems : Focus On Hierarchical Analysis, Ratna Bajaj

Theses

In today's fast paced computing world security is a main concern. Intrusion detection systems are an important component of defensive measures protecting computer systems and networks from abuse. This paper will examine various intrusion detection systems. The task of intrusion detection is to monitor usage of a system and detect and malicious activity, therefore, the architecture is a key component when studying intrusion detection systems. This thesis will also analyze various neural networks for statistical anomaly intrusion detection systems. The thesis will focus on the Hierarchical Intrusion Detection system (HIDE) architecture. The HIDE system detects network based attack as anomalies …

Attack Visualization For Intrusion Detection System, Mohammad A. Rabie

Theses

Attacks detection and visualization is the process of attempting to identify instances of network misuse by comparing current activity against the expected actions of an intruder. Most current approaches to attack detection involve the use of rule-based expert systems to identify indications of known attacks. However, these techniques are less successful in identifying attacks, which vary from expected patterns. Artificial neural networks provide the potential to identify and classify network activity based on limited, incomplete, and nonlinear data sources. Presenting an approach to the process of Attack visualization that utilizes the analytical strengths of neural networks, and providing the results …

A Real Time Frequency Analysis Of The Electroencephalogram Using Labview, Rupal Patel

Theses

The use of the Electroencephalogram (EEG) for diagnosis of brain related diseases is becoming a popular technique in the clinical and research environment. To achieve accurate reading of EEG, signal representation and classification becomes extremely important. The goal of this project was to develop a basic software program for acquiring and online processing of the electrical activity recorded from the brain. A program was developed using the LabVIEW programming software by National Instruments. Basic hardware components recorded the EEG signal and a software component divided the data into delta, theta, alpha and beta bands in the frequency domain. Emphasis was …

An Infrared Device To Measure The Eyeblink For The Study Of Classical Conditioning, Alka Patel

Theses

The classically conditioned eyeblink response is studied by various groups to study neurological functions. This is a form of associative leaming that has many features to help diagnose and learn about neurological diseases. Electromyogram traditionally is used to detect eyeblinks for this experimentation in human. However, EMG can be expensive and difficult to use. It involves the utilization of electrodes and produces only an indirect measure of eyelid closure. The goal of the project was to develop an infrared device to detect eyeblinks and replace the EMG. The project involved two major components, a hardware and a software component. The …

Hyperbolic Position Location Estimator With Tdoas From Four Stations, Sreeram Potluri

Theses

This thesis presents a detailed derivation of a set of equations needed to locate the three dimensional position of a mobile given the locations of four fixed stations (like a global positioning system (GPS) satellite or a base station in a cell) and the signal time of arrival (TOA) from the mobile to each station. From these derived equations, a synthesizable VHDL model was developed and simulated using IEEE numen*c_std package. All the inputs and outputs were described by 32 bit vectors. From the simulations, it was observed that in the best case the mobile position was off by I …

Shear Behavior Of Reinforced Concrete Deep Beams Strengthened With Cfrp Laminates, Jon Erik Moren

Theses

Considerable research has been performed using CFRP plates bonded to normal reinforced concrete beams, the objective being to improve shear and flexural strength. However, very few tests have been performed on reinforced concrete deep beams with CFRP as shear reinforcement. The purpose of this experiment is to investigate the behavior of the deep beam in shear with various arrangements of Sika CarboDur laminates bonded to the sides. The beams were designed to be shear deficient with stirrups omitted, except at the supports and directly under the load. In total eight beams were tested, four with one-point loading and four with …

Corrosion Resistant Nickel-Based Alloy, Joseph William Newkirk, Sanhong Zhang

Materials Science and Engineering Faculty Research & Creative Works

A nickel based, high silicon alloy exhibits very high corrosion resistance in high temperature sulfuric acid environments. The alloy may be cast and is sufficiently ductile to be fabricated and machined. The alloy is ductile and has sufficient resistance to mechanical and thermal shock to be reliable in service when used as rotating parts.

Formation Of 2-Chlorobenzylidenemalononitrile (Cs Riot Control Agent) Thermal Degradation Products At Elevated Temperatures, Timothy A. Kluchinsky, Michael Sheely, Paul B B. Savage, Philip A. Smith

United States Army: Publications

2-Chlorobenzylidenemalononitrile (CS riot control agent) has been shown to produce a number of thermal degradation products when dispersed at high temperature.We hypothesized that these CS-derived compounds are formed by energy input from heating during the dispersion process. Here we identified organic CS-derived compounds formed from purified CS subjected to temperatures ranging from 300 to 900 degrees C in an inert atmosphere with analysis of tube furnace effluent by gas chromatography and mass spectrometry. We conclude that the production of many CS-derived compounds previously observed during high-temperature dispersion is likely to be heat related.