Physical Sciences and Mathematics Commons^™

Seedling Emergence And Growth Of Mangrove Avicennia Marina (Forssk.) Vierh. Under Different Environmental Conditions In The United Arab Emirates, Abdulrazzaq Abdulla Abdulla Anwahi

Theses

Seedling emergence, survival and growth of gray mangrove Avicennia marina (Forssk.) vierh. were studied in relation to different environmental factors through a series of experiments conducted at indoor low temperature, outdoor shaded and field areas at the Marine Resources Research Center, Umm Al Qaiwain. No emergence occurred when seeds were sowed in salinities equal to or higher than 60 ppt. Seedling survival rate decreased with increasing salinity at both indoor and outdoor experimental sites . Faster seedling growth rates were observed under outdoor shaded conditions than under indoor low temperatures. Results of field studies on a sloping beach indicated that …

Subthreshold Channel Leakage Current In Gaas Mesfet's, Wei Long

Theses

In this thesis, a physical model including the subthreshold conpensation properties is presented. The Poisson equation is solved analytically in one dimension for GaAs MESFET's with undoped substrates in the subthreshold region. The solution is then used to derive expressions for subthreshold drain current and subshreshold swing in MESFET's with undoped substrates. Very good agreement between experimental and analytical results is achieved.

Two key parameters (Nilo and Iso) that determine the subthreshold Characteristics have been analyzed as a function of residual acceptor concentration Na, deep level EL2 concentration Nt, channel doping concentration Nd and threshold voltage Vt. It is shown …

Measurement Of The Hall Coefficient And Electron Mobility Using Van Der Pauw Type Hall Effect Measurements, Hong-Sheng Luo

Theses

Hall effect measurement in the electrical characterization of semiconductor materials is very important. We set up the Hall effect measurement system and examined the system with a standard sample. The experimental results show that this Hall measurement system worked as well as expected. We also used this system to study the GaAs/GaAs and InGaAs/GaAs which grown by MBE. Finally, we disscussed and consided some common problems of Hall measurement. Some useful formulas and plots are presented.

Continuous Monitoring Of Volatile Organic Compounds In Air Emission Using Membrane Extraction Microtrap Gc System, Xin Zhang

Theses

A novel method for continuous monitoring volatile organic compounds (VOCs) in air at trace level is presented. A membrane module and a microtrap were used along with gas chromatographic analysis. The membrane module consisted of a bundle of silicone rubber hollow fibers and separated the VOCs from the gaseous stream. The microtrap which is a very small adsorbent trap played the roles of preconcentrator and injector. The VOCs selectively permeate across the membrane into a strip gas in the membrane module. Before entering the GC column, the VOCs are trapped and concentrated by the microtrap. Desorption of the VOCs is …

Mbe Growth Of Inxga1-Xas/Gaas/Si Heterostructure System, Jun Liu

Theses

In this work, we grew the In_xGa_1-xAs/GaAs/Si (GaAs as buffer layer) by MBE technique. The surface of the buffer layer became microscopically rough as the thickness of the buffer layer increased and the growth mode of GaAs on Si underwent a change from three-dimensional to two-dimensional during the initial growth stage as indicated on the Reflection High Energy Electron Diffraction (RHEED) screen. The Scattering Electron Microscopy (SEM) observation of the etched surface of GaAs on Si showed that the structure of the buffer layer tended to be poly-crystalline and it was possible that a predominant orientation …

Modelling Of Groundwater Flow And Pollutants Affecting Concrete Foundations, Jamil A. Gharsan Moqbil

Theses

This thesis presents a finite difference model and its associated computer program. The model has been developed for simulating the pumpage and predicting the water table fluctuations corresponding to different boundary conditions. The mathematical model solves the partial differential equation of groundwater flow by using the finite different techniques.

The model has been verified against known field measurements taken from existing wells in Al-Ain area. Water samples from these existing wells have been collected and tested in the UAE university laboratories to determine their chemical characteristics. All field data have given close results to those predicted by the model and …

Collective Interpretation Of Seismic Reflection, Gravity, Magnetic, And Resistivity Data In The Salalah Plain, Oman, For Hydrogeologic Purposes, Slyam Bin Saeed Bin Salim Ba-Awain

Theses

An interpretive geophysical study in the growing Salalah Plain, Dhofar Governate, Sultanate of Oman, was made during 1993 and part of 1994.

This investigation stems from the need to develop the main and the only water resource in this region. It is aimed to make use of the combined geophysical tools (seismic rflection, gravity, magnetics and resistivity) and available surface and borehole data to assess the environmental impact of the geophysical results.

Several seismic reflection lines were picked and interpreted; one on a horizon near the Taqah limestone (main aquifer), and the other on a horizon near the Mesozoic- Cenozoic …

Human Fetal Hemoglobin Expression And Erythrocytic Indices In Different Groups Among U.A.E Population, Fawzia Salah Ali Issa

Theses

Molecular analysis has revealed that a variety of hemoglobin molecules are produced in humans. All are tetramers consisting of numerous combinations of seven distinct polypeptide chains, each encoded by a separate gene.

Fetal hemoglobin is one of these tetramers that by eight weeks of gestation replace the embryonic hemoglobin forms. Fetal hemoglobin is the major hemoglobin in fetal life. it's concentration in blood decreases after birth to less than 2 per cent of the total hemoglobin by 6 months of age. However, in some cases fetal hemoglobin persist to synthesize in adult life in abnormal concentrations.

Our study concerned the …

A Study On The Atmospheric Quality And Control In The Emirate Of Abu Dhabi, Sukaina Faisal Al-Wasity

Theses

Limited data are available on air pollution levels in Abu Dhabi Emirate in general. Therefore, the present study was designed to investigate the level of atmospheric contaminants in the environment of Abu Dhabi Emirate. This includes measurement of suspended particulate matter less than 10 micron (SPM₁₀) in Al Ain City during normal and stormy conditions and measurement of the same air solids besides the gaseous pollutants: ozone, sulphur dioxide, carbon monoxide, nitrogen oxides and methane and non-methane hydrocarbons in Abu Dhabi City and follow up of hourly variation in their concentration. The study further includes collecting sufficient data …

The Application Of Stereolithography To The Creation Of Molecular Models Of Amiloride And Its Analogues, Thomas John Busanic

Theses

Stereolithography, a process by which a computer-guided Ultraviolet (UV) laser is applied onto a liquid monomer resin to form a solid polymer, was used to create solid models of amiloride and two of its analogues. The Cartesian coordinates used as input for the orientation of each atom in a molecule were calculated using ab initio molecular orbital theory. Since the structures of the molecules are calculated in this fashion, they represent a more accurate representation of the molecules than that provided by standard molecular modeling kits.

The original purpose of this work was to assist a blind chemist in appreciating …

Measurement Of Oxygenated Volatile Organic Compounds Using The Thermionic Ionization Detector, Wanfang Li

Theses

A thermionic ionization detector (TID) consists of a catalytically active, low work function heated source. It responds to molecules with high electron affinity which can extract electrons from the surface of the source to form negative ions. TID has been used as selective detectors for nitrogen and phosphorous compounds (NPD). In this research, a TID has been used for selective detection of oxygenated volatile organic compounds (VOCs). The response of the TID to different oxygenated and chlorinated VOCs compounds was studied. To evaluated its performance, the analysis was done using a FID in parallel with the TID. For most of …

Parallel Exact Enumeration Of Self-Avoiding Walk On Cubic Lattices And Its Applications To Protein Folding Studies, Anek Vorapanya

Theses

Exact enumeration of self-avoiding walk on many lattices have been studied extensively recently. Even a short chain polymer (about 30 monomers) represented as a chain of cubic lattice sites requires a considerable amount of computer time to exhaustively search for all unique conformations. However, self-avoiding walk process can be modified such that it exhibits a high degree of independence among subprocesses. Parallel implementation of such subprocesses can reduce a great amount of enumeration time. Parallel enumeration makes longer chain enumeration possible.

Enumerating only unique conformations requires that all rotation and mirror conformations be removed. An algorithm to avoid generating such …

Nmr Computer Simulation Of Glassy And Powdered Samples : Application To Studies Of Sodium Borovanadate Glasses, Xian-Quan Zhang

Theses

A computer program is devised to simulate the nuclear magnetic resonance (NMR) spectra observed in powdered and glassy samples in the presence of both nuclear quadrupole and anisotropic chemical shift interactions. This method is performed for the central transition of NMR spectra of nuclei with half-integral spin I. Typical theoretical behavior of the powder pattern is discussed and the "noise" and "error" in the simulated spectra are analyzed. The computer simulation method is applied to the studies of 11B NMR spectra of the sodium borovanadate glass system for which a structural model is presented in the range for which glasses …

Extracting Parallelism At Compile-Time Through Dependence Analysis & Cloning Techniques In An Object-Based Paradigm, Binoy Ravindran

Theses

The construct of Abstract Data Type (ADT) modules and Abstract Data Object (ADO) modules supported by most object-based languages are a great source for developing reusable code. To improve the run time performance of such object-based programs, we consider the asynchronous remote procedure call (ARPC) model of parallel execution, in which concurrency is achieved by having the caller and the callee (which are module instances) running on different processors. Frequently, an ADT module is needed simultaneously by other modules, thus causing contention. To resolve this, we clone the module instance in demand and distribute the copies across different processors, so …

Low Temperature Performance Of Field Effect Transistors, Wei Zhu

Theses

The low temperature static characteristics of silicon junction field-effecttransistors (JFETs) have been investigated and analysed. The followingchanges were observed after cooling down the transistors: pinch-offvoltage and transconductance increases; and drain current is changedas a function of the drain-source voltage. It was found that there wasan increase in the amplifying properties and a reduction in noise voltageof cooled transistors. In addition, the temperature and voltage dependenceof leakage current have been studied. Temperatures below 77K are ofinterest in evaluating effects of impurity freezeout and temperatureabove 77K are important since actual device temperature will be aboutthe ambient. Operation of FET circuits at liquid …

Applications Of Binary Sequence Of Order K, Xulun Jiang

Theses

The cumulative distribution of the finite sum of the binary sequence of order k is studied and some of its applications discussed. Certain properties of this sequence are studied and uniformly superior bounds for the cumulative distribution under minimal information on the "success" probabilities are derived.

As an application, an optimal randomized response model to collect sensitive information with dependence in the sample is proposed. This dependence is caused by untruthful response to stigmatizing questions and has been ignored in the past procedures.

The proposed method is useful in collecting reliable information in situations where the response is difficult to …

Solvent Sublation Of Toluene From Aqueous Phase, Mei Chen

Theses

Solvent sublation, a surface chemical technique, was used to remove toluene from aqueous solution into a layer of paraffin oil.

Analytical methods for GC determination of toluene in both gas and aqueous phase were set up. The comparison of solvent sublation and conventional air stripping on toluene removal was carried out. It was found that solvent sublation provides significant improvement over air stripping in removing toluene from water, and reduces toluene emission to the atmosphere. The toluene emissions reduction by solvent sublation are 30%-70% under different conditions. The effects of air flowrates and thickness of organic layer were studied. Increased …

Implementation Of An Automatic Mapping Tool For Massively Parallel Computing, Ajitha Gadangi

Theses

In this thesis, an implementation of a generic technique for fine grain mapping of portable parallel algorithms onto multiprocessor architectures is presented. The implemented mapping algorithm is a component of Cluster-M. Cluster-M is a novel parallel programming tool which facilitates the design and mapping of portable softwares onto various parallel systems. The other components of Cluster-M are the Specifications and the Representations. Using the Specifications, machine independent parallel algorithms are presented in a "clustered" fashion specifying the concurrent computations and communications at every step of the overall execution. The Representations, on the other hand, are a form of clustering the …

Calibration Of Photoluminescence Experiment, Chihchuan Daniel Lee

Theses

Photoluminescence in a semiconductor at room temperature is quite difficult to distinguish from the many nonlasing optical lines from the laser, therefore, a blank test is very important. In so doing, the noises of the detector has to be taken into account. The calibration, however, mainly depends on the detector and is less dependent on other components. Instead of using black-body radiation light source and pyroelectric detector, we use globar lamp and PbS detector; because of the difficulty in the former case in doing alignment of optical path (invisible) and operating at a lower signal level from the detector. The …

Graphical Oodb Modeling For Medical Information Standards (Gommis), Jiping Liu

Theses

The graphical representation of database schemata has been a useful tool for the designer and users of database systems. Such a tool for OODB schemata should incorporate a wide variety of symbols which cover most concepts of existing Object-Oriented Database (OODB), so it is sufficient to support a diverse group of object-oriented data models.

In this paper we created a. graphical representation, using the OOdini system and language, of the European Prestandard for Medical Informatics on Message Exchange of Laboratory Information. This European Prestandard describes a standardized format for messages to be exchanged between a. health care provider and a …

Graphical Oodb Modeling For Medical Information Standards (Gommis), Nagesh K. Puppala

Theses

Our task is to create a graphical representation of the European Prestandard for Medical Informatics on Message Exchange of Laboratory Information. This document, made available to us through Columbia Presbyterian, describes a standardized format for messages to be exchanged between a healthcare provider and a medical laboratory. The prestandard represents important information in a very disconnected way.

We have used OODINI system and language to develop our GOMMIS system. OODINI is a graphical editor for object-oriented database schemas that was developed at NJIT during the past three years. OODINI features a poweful set of icons that cover most concepts of …

Authentication For Mobile Computing, Andreas Keppler

Theses

Host mobility is becoming an increasingly important feature with the recent arrival of laptop and palmtop computers, the development of wireless network interfaces and the implementation of global networks. Unfortunately, this mobile environment is also much more vulnerable to penetration by intruders. A possible means of protection can be authentication. This guarantees the identity of a communication peer.

This thesis studies the constraints imposed on the mobile environment with respect to authentication. It compares the two prevailing authentication mechanisms, Kerberos and SPX, and tries to make suggestions of how a mechanism can be adapted to the mobile environment.

Pyrolysis And Oxidation Reaction Of 1,2, Dichloroethylene In Ar; Ar And Ch4; Ar, Ch4 And O2 Mixtures, Byung Ik Park

Theses

The thermal reaction of trans-1,2-dichloroethylene (DCEE) in methane and oxygen mixtures in Ar bath gas has been studied in 10.5 mm I.D. tubular flow quartz reactors at I atmosphere pressure, isothermal temperature between 575°C and 1000°C, and times of 0.3 to 2.0 seconds.

The thermal reaction of trans-1,2-dichloroethylene in the gas phase proceeds via unimolecular HCI elimination under the reaction condition of the present experiments. The chain branching C-Cl bond fission reaction is expected to become important at the higher temperature, competing With the HCI elimination.

The decay trans- 1,2- dichloroethylene, intermediates and final product distributions varied in the absence …

Bio-Oxidation Of A Model Voc In Air, Jeong Seop Shim

Theses

This study was performed to find a satisfactory regime of operation for the vapor phase bio-oxidation of ethyl alcohol, a model volatile organic compound (VOC), in a specially designed bioreactor. Ethanol was selected as a model compound representing bakery oven gas pollution. A spirally wound bioreactor module was used within which was immobilized a mixed bacterial culture from aerobic sludge. The activated sludge from municipal wastewater treatment plants readily attached with no pretreatment on the surface of the spiral biosupport which is a polymeric sheet.

The parameters studied were air flow rate and inlet concentrations of ethanol. Ethanol was injected, …

Design And Implementation Of Ipis : An X-Window Based Image Processing Interactive System, Eduardo Morales

Theses

Most of image processing systems are based on command line functions or can only display one image at a time. This is a serious inconvenience for those who need an interactive system session or want to compare two images processed by different techniques at the same time.

The system was designed with these problems in mind. It is able to display the processed image right after an operation and to display several images simultaneously, making it simple to compare techniques. The system was also created with the purpose to be used in an academic environment. Its structured design makes it …

Concurrent Use Of Two Programming Tools For Heterogeneous Supercomputers, Javier G. Vasquez

Theses

In this thesis, a demostration of the heterogeneous use of two programming paradigms for heterogeneous computing called Cluster-M and HAsC is presented. Both paradigms can efficiently support heterogeneous networks by preserving a level of abstraction which does not include any architecture mapping details. Furthermore, they are both machine independent and hence are scalable. Unlike, almost all existing heterogeneous orchestration tools which are MIMD based, HAsC is based on the fundamental concepts of SIMD associative computing. HAsC models a heterogeneous network as a coarse grained associative computer and is designed to optimize the execution of problems with large ratios of computations …

Photoluminescence Study Of Gallium Arsenide, Aluminum Gallium Arsenide, And Gallium Antimonide Thin Films Grown By Metalorganic Chemical Vapor Deposition, John Mark Koons

Theses

The photoluminescence produced by four MOCVD grown epitaxial thin film samples was studied to give insight into sample quality. The four samples under this study were GaAs on a GaAs substrate, Al_.25Ga_.75As on a GaAs substrate, Al_.30Ga_.7OAs on a GaAs substrate, and GaSb on a GaSb substrate. Excitation was achieved through the use of the 514.0 nm line of an argon ion laser, and sample cooling was attained by use of a cryostat cooler using helium gas to attain a low temperature limit of 10°K. The GaAs and Al_.30Ga_{.7O …}

External Cavity Laser Power Stabilizer, Jie Ding

Theses

In this thesis, we want to design a stabilizer which does not depend on laser source--with external cavity.

In the first part of the thesis ( Chapter 2 and 3 ), we discuss the wave propagation in crystals and the modulation of optical radiation. From the main two types electro-optic modulations, Phase Modulation and Transverse Modulation, we know that the transverse modulation shows an increase in the frequency limit or useful crystal length of (1-c0/ncm)^-1, and we will use this type modulation in this thesis.

The second part of the thesis is the procedure of design and experiment. …

Study Of The Leaching Of Pentachlorophenol From Treated Utility Poles, Jingyi Zhang

Theses

Pentachlorophenol ( PCP ) has been used as a preservative in wood industry over 40 years. If new regulations are passed, the disposal of used treated utility poles in landfills could be restricted because of the toxic properties of PCP. This study was undertaken to provide a better understanding of the rates and mechanisms of leaching of PCP from these poles.

Following the initial analytical method development for PCP determination, a study was done to apply and validate the method in a leaching characteristics study of PCP from Douglas Fir and Southern Pine.

The major factors which influence the leaching …

Study On The Remediation Of Organic Soil Contaminated With Polychlorinated Biphenyls Using A Variable Frequency Microwave Furnace, Lili Zou

Theses

The development of new and innovative remediation technologies for soil contaminated with Polychlorinated Biphenyl (PCB) is necessary to fulfill the need of cleanup of contaminated sites. In the past eight years the Laboratory for Microwave treatment as Hazardous Substance Management Research Center has investigated the use of Microwave energy to remediate contaminated soils. A major drawback of using single frequencies of the microwave range is the non-uniformity of the electromagnetic field. In this thesis a Variable Frequency Microwave Furnace (operating between 2.40 and 7.50 GHz) is used to improve the uniformity of the field. A new method is used to …