Digital Commons Network^™

Solids Suspension And Power Dissipation In Stirred Tanks Agitated By An Impeller Near The Tank Bottom, Ernesto Uehara-Nagamine

Theses

In this work, the effect of very small impeller clearances off the tank bottom, C, on complete solid off-bottom suspension, Njs, was investigated. Four types of impellers were used six-blade flat-disk turbine, six-blade flat-blade turbine, six-blade flat (45 degreees) pitched-blade turbine, and the high efficiency impeller Chemineer HE-3. The effects of the impeller diameter, D, tank diameter, T, and solids loading, X, were quantified. The presence of two impellers was analyzed using impellers of the same type and size.

Typically, Njs and the power consumption were found to decrease with the impeller clearance. However, for lower C/T values, a slight …

Surface Phenomena On The Tin-Dioxide Polycrystalline Layers, Andrei A. Fluerasu

Theses

Polycrystalline tin-dioxide is widely used in the detection of reducing gases (such as H₂, CO, CH₄, C₂H₅OH,...) in air by measuring its conductivity changes. The advantage of gas sensors based on such sensing devices is low cost and high sensitivity. In contrast to their widespread applications and to their successful empirical research and development work, the present understanding of the chemical sensing mechanisms is still immature.

In this thesis, for gas sensors based on thick and porous tin-dioxide layers, a study of the response function upon variation of the partial pressure of …

Modeling Of Cardiovascular System To Simulate Ventricular Septal Defect, Adarsh Kumar Gupta

Theses

The hemodynamics of the ventricular septa] defect is studied using a mathematical modeling technique. A twelve-compartment windkessel model of cardiovascular system is used to study the hemodynamics of the ventricular septal defect. The VSD is incorporated into the model via a parallel flow from the left to right ventricles (left-to-right shunt). The resistance to flow through the shunt is used to characterize the severity of the defect. Changes in the severity of the shunt flow produces changes in the ratio of pulmonary to systemic flow in the circulation. When the pulmonary to systemic flow ratio is more than 2:1, the …

Oodini 2.1 : An Enhanced Graphical Schema Representation For Object-Oriented Database, Rajashekar Rao

Theses

The graphical representation of an object-oriented database (OODB) schema is useful for the designers and users of a database system. The purpose of my thesis was to enhance the existing version of OOdini, an interactive graphical tool for editing an OODB schema. The new features include interactive modification and description of objects in the schema. Data structures for representing classes and attributes have been altered to incorporate object/data types as well as a descriptive string. The software has been implemented using the ObjectMaker toolkit to design our own methodology using the ObjectMaker Extension Language.

Removal Of Gasoline-Based Hydrocarbons By Vapor Permeation Membranes, Shivashanker Bagavandoss

Theses

Removal and recovery of evaporated lighter gasoline fractions can be effectively implemented by selectively permeating the hydrocarbons (HCs) and other volatile organic compounds (VOCs) from the vented air streams through nonporous hydrophobic polymeric membranes subjected to vacuum on the permeate side and then condensing these organics from the permeate. Such a vapor permeation process employing spiral-wound membranes has already been commercialized for VOCs. In this study, attention has been focused on removal of hydrocarbons from nitrogen flowing through the bore of microporous hydrophobic hollow fibers with a specially engineered nonporous silicone coating on the outside surface with a view to …

Implementation Of Fortran Finite Element Analysis Source Code With Application : Particle Deposition In A 90 Degree Duct Bend, Pantaleo Loiacono

Theses

Two FORTRAN 77 finite element analysis source codes, by 1.N. Reddy, were input into a PC, debugged, executed, and tested successfully. These programs are available to students interested in implementing a good finite element analysis source code on a PC or on a workstation in one or two dimensions. The programs can solve problems relating to heat transfer, stresses, beam analysis, frames, trusses, plane elasticity, plate bending, and laminar viscous incompressible fluids with various node and element combinations.

The two-dimensional program was used to obtain the velocity distributions in a 90 degree duct bend with incoming and exiting fully developed …

The Effect Of Deposition Of H2s On The Catalyst Activity Of 1.5 % Pt On [Gamma]-Al2o3, Ping Zhu

Theses

The impact of hydrogen sulfide (H₂S) pretreatment on the oxidation activity of powdered 1.5% Pt/γ-AL₂O₃ catalyst was investigated in this study. Fresh 1.5% Pt/γ-Al₂O₃ catalyst was aged with different concentrations of H₂S in air at 400 °C for 24 hours. Then, the aged and fresh catalysts were tested to determine the oxidation activity with diagnostic gases which contained either 1% propane or 1% carbon monoxide in dry air. The test results indicated that the catalysts were deactivated for carbon monoxide oxidation and promoted for propane oxidation as a function of …

Factors That Influence Changes In Temporal And Spatial Accumulation Of Debris On An Estuarine Shoreline, Cliftwood Beach, New Jersey, Usa, Laura Pace

Theses

A field investigation was conducted on an estuarine shoreline in Raritan Bay, New Jersey to identify the temporal and spatial distribution changes in accumulation of marine debris, and the factors that influence these changes. Methodology consists of 12-monthly collections of debris and profile data, and collection of local climatological and tide data. Debris was classified by type, length, weight, fragmentation, and probable function and weathering noted for each collected item. Wind roses were constructed to determine dominant wind speed and direction and wind characteristics for time intervals between field sampling.

Plastics are the primary component of debris; glass and styrofoam …

Empirical And Theoretical Analysis Of Foreign Exchange Markets : A Case Of Belgium, Germany, And The Netherlands, Ozan Akyureklier

Theses

The paper uses an efficiency specification model of the spot and forward foreign exchange markets and tests the random walk, the general efficiency, and the unbiasedness hypotheses by utilizing a regression estimation and many different specification and diagnostic tests for the series and the error terms.

The paper discusses the important aspects of efficiency, expectations, and risk in the foreign exchange market. First a brief presentation of the existing single-equation structural models of exchange-rate determination is given. An efficiency specification model of the spot and forward foreign exchange markets applied to test the random walk, the general efficiency, and the …

Study Of Stress In Microelectronic Materials By Photoelasticity, Hancheng Liang

Dissertations

The study of stress is playing an important role in microelectronic technology. In comparison with other techniques, the photoelasticity technique has the advantages of having high spatial resolution and high sensitivity. It can be used in qualitative observation in real-time and quantitative determination of stress distribution in the microelectronic materials and devices.

This dissertation presents a systematic study of photoelastic stress analysis in microelectronic materials and devices, ranged from theoretical study to practical system setup, from measurement methods to their applications. At first, based on the detailed survey on the piezo-optic properties of the crystals used in microelectronics, we apply …

Reaction Kinetics Of Methanol And Mtbe Oxidation And Pyrolysis, Wen-Chiun Ing

Dissertations

This study presents experimental data on the decomposition of methanol in several different reaction environments - fuel lean to stoichiometric at a temperature range of 873 and 1073 K and a pressure range of I and 5 atm. Methane fuel is also added in several of the systems studied in order to provide experimental data to understand the methanol addition effect on the methane oxidation.

Computer codes: ThermCal, ThermSrt and ThermCvt have been developed for the thermal property calculations of stable molecules by the Benson group additivity method and of radicals by the NJIT hydrogen bond increment method.

Pressure dependent …

Experimental And Analytical Investigation Of Waterjet Cleaning Process, Ping Meng

Dissertations

This doctoral dissertation is concerned with the development of water based cleaning technology required by industry which may substitute the traditional approach based upon the use of various chemical cleansers.

The experimental study involves the waterjet removal of various coatings (rust, oil and epoxy based paints, etc.). Cleaning was carried out under a wide range of operational and geometrical conditions (standoff distance, travel speed, water pressure, diameters of sapphire nozzle and focusing tube, nozzle body type). A new designed spiral nozzle body was tested in this work. The use of surfactant was also investigated. Microscope and SEM surface were used …

Characterization And Fabrication Of A (6h)-Sic As A Piezoresistive Pressure Sensor For High Temperature Applications, Robert Sylvester Okojie

Dissertations

A prototype monolithic 6H-SiC pressure sensor operational up to 350°C, with potential to operate up to 600°C, was batch fabricated and tested. At temperatures higher than 450°C, silicon diaphragms creep under minimal load. To operate beyond 450°C, therefore, the use of 6H-SiC was proposed. However, three key technological issues - fabrication, high temperature metallization, and gage factor characterization - had to be resolved. Since conventional fabrication technology is not applicable to SiC due to its near inert chemistry, photoconductive selectivity techniques to etch the piezoresistors were developed. Techniques to wet etch the cavities in a dark current mode were developed, …

Experimental And Numerical Investigation Of Abrasive Waterjet Polishing Technology, Fenggang Li

Dissertations

The objective of this investigation is the development of the abrasive waterjet (AWJ) based polishing technology. The result of the investigation will assist the implementation of AWJ polishing for manufacturing processes and procedures.

Experimental exploration of AWl polishing involving processing of difficultmachine materials such as Alumina ceramic and stainless steel. Surface improvement due to this processing is evaluated by measuring the roughness of the generated surfaces and examining the microhardness and micro-topography of the surfaces using Scanning Electronic Microscopy (SEM). The surface roughness of 0.3 micron was obtained at samples of ceramic and metal alloys at a reasonable rate using …

The Constant Fracture Angle Model For Cementitious Materials, Suk Ki Kim

Dissertations

Fracture mechanics of concrete has been investigated for the past two decades using linear elastic and nonlinear fracture mechanics concepts. The models proposed so far remain questionable largely due to specimen dependency of the proposed fracture parameters.

In this study, a new approach for modeling the fracture characteristics of concrete and fiber reinforced concrete is proposed. The model depends on the load CMOD relationship rather than the traditional load-deflection principle. Although energy consumed during fracture is definitely a direct function of the load displacement response, it was observed that traditional displacement measurement included an extraneous and erratic portion due to …

Towards Designing A Knowledge-Based Tutoring System : Sql-Tutor As An Example, Gang Zhou

Dissertations

A Knowledge-Based Tutoring System, also sometimes called an Intelligent Tutoring System, is a computer based instructional system that uses artificial intelligence techniques to help people learn some subject. The goal of the system is to provide private tutoring to its students based on their different backgrounds, requests, and interests. The system knows what subject materials it should teach, when and how to teach them, and can diagnose the mistakes made by the students and help them correct the mistakes.

The major objective of this dissertation is to investigate and develop a generic framework upon which we can build a Knowledge-Based …

Emulsion Liquid Membrane Removal Of Arsenic And Strontium From Wastewater : An Experimental And Theoretical Study, Ding-Wei Zhou

Dissertations

The emulsion liquid membrane (ELM) technique has been successfully applied on the removal of arsenic (As) from metallurgical wastewater and the removal of strontium (Sr) horn radioactive wastewater. This study consisted of experimental work and mathematical modeling.

Extraction of arsenic by an emulsion liquid membrane was firstly investigated. The liquid membrane used was composed of 2-ethylhexyl alcohol (2EHA) as the extractant, ECA436OJ as the surfactant, and Exxsol D-8O solvent (or heptane) the diluent. The sulfuric acid and sodium hydroxide solutions were use I as the external and internal phases, respectively. The arsenic removal efficiency reached 92% within 15 minutes in …

Explicit Congestion Control Algorithms For Available Bit Rate Services In Asynchronous Transfer Mode Networks, Ambalavanar Arulambalam

Dissertations

Congestion control of available bit rate (ABR) services in asynchronous transfer mode (ATM) networks has been the recent focus of the ATM Forum. The focus of this dissertation is to study the impact of queueing disciplines on ABR service congestion control, and to develop an explicit rate control algorithm.

Two queueing disciplines, namely, First-In-First-Out (FIFO) and per-VC (virtual connection) queueing, are examined. Performance in terms of fairness, throughput, cell loss rate, buffer size and network utilization are benchmarked via extensive simulations. Implementation complexity analysis and trade-offs associated with each queueing implementation are addressed. Contrary to the common belief, our investigation …

Pattern Discovery In Sequence Databases : Algorithms And Applications To Dna/Protein Classification, Gung-Wei Chirn

Dissertations

Sequence databases comprise sequence data, which are linear structural descriptions of many natural entities. Approximate pattern discovery in a sequence database can lead to important conclusions or prediction of new phenomena. Traditional database technology is not suitable for accomplishing the task, and new techniques need to be developed.

In this dissertation, we propose several new techniques for discovering patterns in sequence databases. Our techniques incorporate pattern matching algorithms and novel heuristics for discovery and optimization. Experimental results of applying the techniques to both generated data and DNA/proteins show the effectiveness of the proposed techniques.

We then develop several classifiers using …

Global Fuzzy Control Based On Cell Mapping, Tea-Quin Kim

Dissertations

Cell mapping methods can generate global optimal controls for nonlinear dynamic systems. However, the implementation of this approach for on-line control is difficult due to its use of a table-based controller which requires a large amount of memory.

In this dissertation, a cell mapping based systematic method is developed to construct a fuzzy controller to replace the table-based controller for global optimal control of dynamic systems. The method consists of four steps: 1) An optimal control table is generated using a cell mapping algorithm. 2) The cells are linked into trajectories to characterize the optimal dynamic evolution of various cell. …

Knowledge Discovering For Document Classification Using Tree Matching In Texpros, Ching-Song Wei

Dissertations

This dissertation describes a knowledge-based system for classifying documents based upon the layout structure and conceptual information extracted from the content of the document. The spatial elements in a document are laid out in rectangular blocks which are represented by nodes in an ordered labelled tree, called the "layout structure tree" (L-S Tree). Each leaf node of a L-S Tree points to its corresponding block content. A knowledge Acquisition Tool (KAT) is devised to create a Document Sample Tree from L-S Tree, in which each of its leaves contains a node content conceptually describing its corresponding block content. Then, applying …

Integrating Hypertext With Information Systems Through Dynamic Mapping, Jiangling Wan

Dissertations

This dissertation presents a general hypertext model (GHMI) supporting integration of hypertext and information systems through dynamic mapping. Information systems integrated based on this model benefit from hypertext function-alities (such as linking, backtracking, history, guided tours, annotations, etc.) while preserving their own computation capabilities. Although systems supporting integration of hypertext and interface-oriented information systems do exist in hypertext literature, there is no existing model or system effectively supporting integration of hypertext and computation-oriented information systems. GHMI makes its major contributions by both extending and specifying the well-known Dexter Hypertext Reference Model. GHMI extends the Dexter model to overcome its limitations. …

Theory And Design Of Portable Parallel Programs For Heterogeneous Computing Systems And Networks, Ying-Chieh Wu

Dissertations

A recurring problem with high-performance computing is that advanced architectures generally achieve only a small fraction of their peak performance on many portions of real applications sets. The Amdahl's law corollary of this is that such architectures often spend most of their time on tasks (codes/algorithms and the data sets upon which they operate) for which they are unsuited. Heterogeneous Computing (HC) is needed in the mid 90's and beyond due to ever increasing super-speed requirements and the number of projects with these requirements. HC is defined as a special form of parallel and distributed computing that performs computations using …

Development Of A Multivariate Qsar Model To Predict Desorption Of Halogenated Aliphatic Hydrocarbons From Activated Sludge Solids, Sudhi Ranjan Mukherjee

Dissertations

Data collected from different wastewater treatment processes have provided statistically significant evidence that many toxic organic contaminants on EPA's list of priority pollutants concentrate several orders of magnitude greater than influent concentrations in industrial and municipal wastewater sludges. Because of the reversibility of sorption processes, it is possible for sorbed organic compounds to desorb at a later time, hence making disposal of these sludges a potential problem. Although a number of models have been developed to predict sorption parameters, they have all been based on empirically derived descriptors whose validity is seriously compromised by the variation in available data for …

Continuous Monitoring Of Volatile Organic Compounds Using Microtrap Based Gas Chromatographic Systems, Yonghua Xu

Dissertations

Continuous analysis allows a representative portion of a sample to flow continuously through an analytical instrument, which gives analytical information with little or no delay in time. A microtrap is a small diameter tube packed with adsorbents in series. When a gaseous sample containing volatile organic compounds (VOCs) flows through the microtrap, the VOCs can be trapped selectively by adsorbents. Then a pulse of electrical current is applied to the microtrap. This rapid heating results in a desorption that can act as a sharp injection for GC separation. Thus the microtrapped sample is the total amount of VOC present in …

A Full Wave Method For Rough Surface Scattering Using Fictitious Current Distributions, Anthony A. Triolo

Dissertations

Rough surface scattering is a current topic of interest in many diverse fields. But, despite its importance, the two most widely used solution methods, the Kirchhoff and first order perturbation methods, are valid only for a restricted range of surface types. There is a large range of surface statistics for which neither of these theories is valid. There are purely numerical solutions to the problem, i.e., the integral equation technique and FDTD method, but these methods require a prohibitively large amount of computer time and storage space for use in practical applications. A full wave method has been introduced by …

Reduction Of Inertia-Induced Forces In A General Spatial Mechanism, Sahidur Rahman

Dissertations

A computer-aided design procedure has been developed for minimizing the adverse effects of the inertia-induced forces by optimum mass redistribution amongst the links of high speed general spatial linkages. The evaluation of an optimality criterion for the mass redistribution of the mechanism will be carried out with the aid of a quadratic programming technique. This has been found to be successful in minimizing inertia induced forces and torques. The validity of the optimization procedure will be demonstrated by application to one kind of spatial linkage.

No literature has been found on the balancing of a general spatial mechanism, since its …

Oxidation Of Isobutane And Isobutene Reaction Pathways And Detailed Mechanism, Chiung-Ju Chen

Theses

A reaction mechanism consisting of 248 elementary reactions and 138 species has been developed to model experimental systems - decomposition of 2,2,3,3 tetramethylbutane in the presence of oxygen and oxidation of isobutene. This elementary reaction mechanism based on two important reaction systems: tert-butyl radical with O₂ and allylic isobutenyl radical with O₂, plus their subsystems, such as isobutene + HO₂, isobutene + OH and allylic isobuteny1hydroxy + O₂. Thermochernical kinetic parameters are developed for each elementary reaction and a chemical activation kinetic analysis using quantum RiceRamsperger-Kassel (QRRK) theory for k(E) and modified strong …

Measurement Of The Electroencephalogram (Eeg) Coherence, Atmospheric Noise, And Schumann Resonances In Group Meditation, Douglas A. Newandee

Theses

Electrical activity in the human body was investigated using EEG and ECG measurements while subjects remained with eyes open, eyes closed and in a meditation state. During these measurements, additional antennas were attached to the equipment to record atmospheric noise and signal activity simultaneously. The obtained data was analyzed and various observations were made. Processed data based on antenna signals clearly showed the presence of man-made signals, having narrow spectral widths that could be treated as atmospheric noise in the frequency range up to 50 Hz. In addition, signals clustered around 7.8, 14.1, 20.3, 26.4, and 32.5 Hz were observed …

Comparison Of Different Signal Processing Algorithms To Extract The Respiration Waveform From The Ecg, David J. Caggiano

Theses

Power spectral analysis of heart rate variability is a powerful tool to measure the activity of the parasympathetic division of the autonomic nervous system noninvasively. To determine the parasympathetic activity, the frequency of respiration must be known. However, during ambulatory studies, the frequency of respiration is not acquired. To alleviate this problem, methods have been proposed in the past to derive the respiration from the ECG. Unfortunately, these previous methods are unreliable if the subject's breathing rate is uncontrolled. In this study, four methods to derive the respiration waveform from the electrocardiogram (ECG) were developed. Two leads of ECG and …