Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons

Open Access. Powered by Scholars. Published by Universities.®

1998

Discipline
Institution
Keyword
Publication
Publication Type
File Type

Articles 421 - 450 of 2574

Full-Text Articles in Physical Sciences and Mathematics

A Feedback-Driven Proportion Allocator For Real-Rate Scheduling, David Steere, Ashvin Goel, Joshua Gruenberg, Dylan Mcnamee, Calton Pu, Jonathan Walpole Sep 1998

A Feedback-Driven Proportion Allocator For Real-Rate Scheduling, David Steere, Ashvin Goel, Joshua Gruenberg, Dylan Mcnamee, Calton Pu, Jonathan Walpole

Computer Science Faculty Publications and Presentations

In this paper we propose changing the decades-old practice of allocating CPU to threads based on priority to a scheme based on proportion and period. Our scheme allocates to each thread a percentage of CPU cycles over a period of time, and uses a feedback-based adaptive scheduler to assign automatically both proportion and period. Applications with known requirements, such as isochronous software devices, can bypass the adaptive scheduler by specifying their desired proportion and/or period. As a result, our scheme provides reservations to applications that need them, and the benefits of proportion and period to those that do not. Adaptive …


Sequence-Specific Photomodification Of Dna By An Oligonucleotide-Phenanthrodihydrodioxin Conjugate, Kestutis G. Bendinskas, Andreas Harsch, R. Marshall Wilson, W. Robert Midden Sep 1998

Sequence-Specific Photomodification Of Dna By An Oligonucleotide-Phenanthrodihydrodioxin Conjugate, Kestutis G. Bendinskas, Andreas Harsch, R. Marshall Wilson, W. Robert Midden

Chemistry Faculty Publications

We introduce a new member of a family of photochemically active oligonucleotide conjugates. A Phenanthrodihydrodioxin (PDHD)-based agent was synthesized and covalently linked to a 5'-end of the 9-mer oligonucleotide via a hexamethylene linker. The conjugate hybridized to a complementary 30-nucleotide-long target and efficiently cleaved it in a sequence specific manner. Up to 67% of target was specifically damaged (51% cross-links and 16% direct cleavage). While the photosensitizer alone nonspecifically damaged only Gs in a single-stranded target, its conjugate cross-linked to and damaged also A, T, and C sites in a target in agreement with duplex and tripler formation.


Application Of Mathematical Modeling And Computer Simulation For Solving Water Quality Problems, Jacek Makinia, Scott A. Wells, David Crawford, Marian Kulbik Sep 1998

Application Of Mathematical Modeling And Computer Simulation For Solving Water Quality Problems, Jacek Makinia, Scott A. Wells, David Crawford, Marian Kulbik

Civil and Environmental Engineering Faculty Publications and Presentations

Deteriorated water resources in Central and Eastern Europe call for actions that should be undertaken to improve current conditions and to protect human and environmental health. Mathematical modeling and computer simulation is often an integral part of the decision-making process. Models and simulations allow rapid and varied evaluation of causes and effects and the principal advantage is that they enable an analysis of even long-term actions with limited investment costs. This paper provides an overview of popular models used for simulation of major elements of a water quality system: surface water quality (QUAL2E), wastewater treatment (Activated Sludge Model No.1), sewer …


‘Race, Gender And Justice’: New Technologies And Student Empowerment, Ron Buckmire, Donna Maeda, Gabrielle Foreman Aug 1998

‘Race, Gender And Justice’: New Technologies And Student Empowerment, Ron Buckmire, Donna Maeda, Gabrielle Foreman

Ron Buckmire

No abstract provided.


Emission Line Profile Shapes From Anisotropic Scattering In Planar Equatorial Disks., R. Ignace Aug 1998

Emission Line Profile Shapes From Anisotropic Scattering In Planar Equatorial Disks., R. Ignace

Richard Ignace

The consequences of anisotropic resonance line scattering for the emission profiles of equatorial disks are considered. In particular the opportunity to infer the disk velocity field owing to the anisotropic scattering is discussed. Analytic expressions for the profile shapes are derived for the cases of constant expansion and rotation, and numerical results are given for more realistic disk velocity fields of linear expansion and Keplerian rotation. The essential result is that the anisotropic line scattering produces a different profile signature in expanding disks as compared to rotating disks, owing to the difference in the isovelocity pattern of the two cases …


Inference Of Steady Stellar Wind V(R) Laws From Optically Thin Emission Lines Iii. Inversion Of Total Line Intensity Distributions., R. Ignace, J. C. Brown, J. E. Milne, J. P. Cassinelli Aug 1998

Inference Of Steady Stellar Wind V(R) Laws From Optically Thin Emission Lines Iii. Inversion Of Total Line Intensity Distributions., R. Ignace, J. C. Brown, J. E. Milne, J. P. Cassinelli

Richard Ignace

The variation with wavelength for a sequence of total intensities of stellar wind lines is considered as a basis for deriving the wind velocity law v(r). In particular, we focus on the case where the continuum formation in the wind is dominated by the free-free opacity so that the inner radius increases with wavelength, as is realized in some massive winds like those of the Wolf-Rayet stars. The line emission in the wind occurs exterior to the continuum photosphere, hence lines observed at different wavelengths probe different regions of the wind acceleration. A major consequence of these physical conditions is …


A Resource Allocation Mechanism Based On Cost Function Synthesis In Complex Systems, Carlos C. Amaro Aug 1998

A Resource Allocation Mechanism Based On Cost Function Synthesis In Complex Systems, Carlos C. Amaro

Dissertations

While the management of resources in computer systems can greatly impact the usefulness and integrity of the system, finding an optimal solution to the management problem is unfortunately NP hard. Adding to the complexity, today's 'modern' systems - such as in multimedia, medical, and military systems - may be, and often are, comprised of interacting real and non-real-time components. In addition, these systems can be driven by a host of non-functional objectives – often differing not only in nature, importance, and form, but also in dimensional units and range, and themselves interacting in complex ways. We refer to systems exhibiting …


Microwave Heating Of Fluid/Solid Layers : A Study Of Hydrodynamic Stability And Melting Front Propagation, John Gilchrist Aug 1998

Microwave Heating Of Fluid/Solid Layers : A Study Of Hydrodynamic Stability And Melting Front Propagation, John Gilchrist

Dissertations

In this work we study the effects of externally induced heating on the dynamics of fluid layers, and materials composed of two phases separated by a thermally driven moving front. One novel aspect of our study is in the nature of the external source, which is provided by the action of microwaves acting on dielectric materials. The main challenge is to model and solve systems of differential equations, which couple fluid dynamical motions (the Navie- Stokes equations for nonisothermal flows) and electromagnetic wave propagation (governed by Maxwell's equations).

When an electromagnetic wave impinges on a material, energy is generated within …


Emissivity Measurements And Modeling Of Silicon Related Materials And Structures, Sufian Abedrabbo Aug 1998

Emissivity Measurements And Modeling Of Silicon Related Materials And Structures, Sufian Abedrabbo

Dissertations

The objective of this dissertation is to investigate the major issues concerning applications of pyrometry for applications in rapid thermal processing (RTP) of silicon related materials. The research highlights of this work are:

Establishment of spectral ernissometry as a novel, reliable and reproducible technique for:

Determination of wavelength and temperature dependent reflectivity, transmissivity, emissivity and temperature, simultaneously, of silicon related materials and structures. The emissometer operates in the wavelength range of 1-20mm and temperature range of 300-1200K. The analysis of the influence of morphological effects on the radiative properties by measurement of (a) front-smooth incidence versus backside-rough incidence of singleside …


A Folder Organization Model For Information Systems : Exploring Its Architectural Expressive Power And Predicate-Based Filing, Simon Doong Aug 1998

A Folder Organization Model For Information Systems : Exploring Its Architectural Expressive Power And Predicate-Based Filing, Simon Doong

Dissertations

This dissertation presents an Internal Folder Organization (I-ORG) which supplements the architectural deficiencies of the existing model - the User Folder Organization (U-ORG), to electronically model a person's filing system in the modern office environment. An I-ORG folder organization gives a logical representation of how documents of the same or different kinds are related and grouped into folders based on predefined premises. Our model is represented by a Rooted Direct Acyclic Graph (RDAG). Each node in the graph represents a folder; and folders are related by "subfolder relationship" (for capturing the "and" relation) and "virtual-folder relationship" (for capturing the "or" …


A Graph Based Process Model Measurement Framework Using Scheduling Theory, Gary Guang-Li Mou Aug 1998

A Graph Based Process Model Measurement Framework Using Scheduling Theory, Gary Guang-Li Mou

Dissertations

Software development processes, as a means of ensuring software quality and productivity, have been widely accepted within the software development community; software process modeling, on the other hand, continues to be a subject of interest in the research community. Even with organizations that have achieved higher SEI maturity levels, processes are by and large described in documents and reinforced as guidelines or laws governing software development activities. The lack of industry-wide adaptation of software process modeling as part of development activities can be attributed to two major reasons: lack of forecast power in the (software) process modeling and lack of …


Supercritical Fluid Extraction (Sfe) And High Performance Liquid Chromotography (Hplc) Analysis Of Polycyclic Aromatic Hydrocarbon (Pah) Contaminated Soil, Marie Renee Gargas Aug 1998

Supercritical Fluid Extraction (Sfe) And High Performance Liquid Chromotography (Hplc) Analysis Of Polycyclic Aromatic Hydrocarbon (Pah) Contaminated Soil, Marie Renee Gargas

Theses

Methods for the extraction and analysis of polycyclic aromatic hydrocarbons (PAHs) from contaminated soil were evaluated for use in a treatability study. Candidate procedures were selected from EPA SW-846 (Third Edition) methods. Soxhlet extraction (3540B) was selected to determine initial PAH concentrations. Supercritical fluid extraction with carbon dioxide (SFE: 3561) and high performance liquid chromatography (HPLC: 8310) were evaluated for use as the extraction and analysis methods. Experimental soil was obtained from a petroleum product refinery site; a Certified Reference Material (CRM) was also studied.

Experiments focused on determining concentrations of anthracene, chrysene, fluoranthene, phenanthrene, and pyrene in untreated experimental …


Observation Of High Momentum Η′ Production In B Decays, T. E. Browder, Kenneth A. Bloom, Cleo Collaboration Aug 1998

Observation Of High Momentum Η′ Production In B Decays, T. E. Browder, Kenneth A. Bloom, Cleo Collaboration

Kenneth Bloom Publications

We report the first observation of Bη′X transitions with high momentum η′ mesons. We observe 39.0 ± 11.6 B decay events with 2.0 < Pη′ < 2.7 GeV/c, the high momentum region where background from bc processes is suppressed. We discuss the physical interpretation of the signal, including the possibility that it is due to bsg* transitions. Given that interpretation, we find Ɓ(Bη′Xs) = [6.2 ± 1.6(stat) ± 1.3(syst) -1.5+0.0(bkg)] X 10-4 for 2.0 < Pη′ < 2.7 GeV/c.


Requirement Elicitation And Knowledge Management Utilizing Relational Database, Client Server And Internet Technologies, Umang J. Dave Aug 1998

Requirement Elicitation And Knowledge Management Utilizing Relational Database, Client Server And Internet Technologies, Umang J. Dave

Theses

The first step in any project is a statement of requirements. Requirements specification is an inevitable part of any successful project. However, the "rush" to convert concepts to products often proves as a big hindrance in the development process of any requirements set. This, in turn, hampers the ability to produce the concept and manage knowledge as originally envisioned.

The goal of the thesis is to foster understanding among the different communities affected by the development of the given system. The thesis is based on the principle that the requirements elicitation process for complex system is fundamentally a conversation among …


The Feasibility Of Transferring Clean Technology From The United States To China : A Case Study From The Paper Industry, He Ning Aug 1998

The Feasibility Of Transferring Clean Technology From The United States To China : A Case Study From The Paper Industry, He Ning

Theses

In their pursuit of economic development, many developing countries are causing pollution at an alarming rate. One solution to the problem is the use of clean technology. Some developed countries have created various manufacture technologies which result in pollution prevention. There is a need for the transfer of clean technology from the developed countries to developing countries. It is beneficial to study the feasibility of such transfer.

The manufacturing processes of the paper industry are selected for this study. An investigation and comparison was conducted in order to evaluate the feasibility of clean technology transfer from the United States to …


Development And Field Testing Of Pulse Introduction Membrane Extraction (Pime) For Measurement Of Ground Water Contamination, Anthony San Juan Aug 1998

Development And Field Testing Of Pulse Introduction Membrane Extraction (Pime) For Measurement Of Ground Water Contamination, Anthony San Juan

Theses

VOCs are a class of aromatic and aliphatic compounds with a variety of functional groups, and are in general detrimental to human health even at trace levels. Conventional analysis of VOCs in groundwater usually involves sampling at site followed by laboratory analysis. This results in long turn around times, high cost and also errors associated with sample preservation during transportation and storage. In order to address these problems, a field portable instrument referred to as Pulse Introduction Membrane Extraction (PIME) has been developed for monitoring trace level halogenated organic contaminants in ground water. A membrane extraction approach has been used, …


Process Modeling Using Proslcse On Web-Enabled Platform, Orcan Ali Enunlu Aug 1998

Process Modeling Using Proslcse On Web-Enabled Platform, Orcan Ali Enunlu

Theses

Process modeling is a relatively complex task that needs to be addressed from a different point of view. The classical approach would be to design the model, to send it for evaluation, then to return feedback to the developing team, and to reevaluate the model with the feedback received from the parties involved.

However, it is our understanding that the steps taken during the process modeling could benefit from the advantages that the Internet offers. To demonstrate the usefulness of Internet in process modeling, I have taken an existing tool, ProSLCSE, and implemented it with Java so that it can …


Determination Of Electron Donors In The Reductive Dechlorination Of Tetrachloroethene, Samantha L. Marasigan-Bernal Aug 1998

Determination Of Electron Donors In The Reductive Dechlorination Of Tetrachloroethene, Samantha L. Marasigan-Bernal

Theses

Several substrates, namely fatty acids and alcohols, were used to enhance the reductive microbial dechlorination of PCE to ethene. All of the microcosms amended with the volatile fatty acids (butyrate, succinate, lactate, formate, butyrate/formate mixture and butyrate/succinate mixture) demonstrated complete reductive dechlorination of PCE to ethane. The cultures amended with the butyrate/succinate mixture was the quickest to completely dechlorinate PCE to ethene (49 days). Those amended with butyrate, succinate, formate and the butyrate/formate mixture exhibited complete reductive, dechlorination at 77 days. Microcosms amended with lactate exhibited complete reductive dechlorination at 160 days.

The microcosms amended with the alcohols (ethanol, propanol, …


Competition Of Copper, Lead, And Cadmium Adsorption To Goethite, Chris A. Christophi Aug 1998

Competition Of Copper, Lead, And Cadmium Adsorption To Goethite, Chris A. Christophi

Theses

Competition of copper, lead, and cadmium adsorption on goethite depends on metal ion and oxide surface characteristics. Goethite was characterized via X-ray diffraction, potentiometric titrations, site density determination, particle size analysis, and optical microscopy. In this thesis, a hypothesis was tested that electronegativity is the most important factor in metal affinities and adsorption competition to goethite.

Metal affinity and site density for the goethite surface were assessed by performing adsorption edges and isotherms. Based on the results of these experiments, competition studies were designed to observe adsorption and displacement of the competing metals by limiting the number of available sites …


Electrochemical Behavior Of Chemically Prepared Ring-Substituted Polyanilines, Lizong Dai, Huihuang Wu Aug 1998

Electrochemical Behavior Of Chemically Prepared Ring-Substituted Polyanilines, Lizong Dai, Huihuang Wu

Journal of Electrochemistry

No abstract provided.


Direct Electrochemical Reaction Of Cytochrome C At The Poly (Ethylene Oxide) Film Modified Gold Electrodes, Xiaogang Qu, Gongquan Sun Aug 1998

Direct Electrochemical Reaction Of Cytochrome C At The Poly (Ethylene Oxide) Film Modified Gold Electrodes, Xiaogang Qu, Gongquan Sun

Journal of Electrochemistry

In this paper, the direct electrochemical reaction of cytochrome c was sudied at the poly (ethylene oxide) film modified gold electrodes. It was found the PEO is a good promoter for the electrochemical reaction of cytochrome c, and the reversibility of reaction of cytochrome c was found to depend on the molecular weight of PEO and the morphology of the PEO films.


Modification Of Carbon Anode Materials Of Lithium Ion Secondary Battery, Yuping Wan Chunrong Wu, Changyin Jiang, Jiangiun Li Aug 1998

Modification Of Carbon Anode Materials Of Lithium Ion Secondary Battery, Yuping Wan Chunrong Wu, Changyin Jiang, Jiangiun Li

Journal of Electrochemistry

In this paper, the latest research work on modification of carbon anode materials of lithium ion secondary battery is reviewed. Modification methods include: incorporation of nonmetal elements such as boron, silicon, nitrogen, phosphorus and sulfur, metal elements such as potassium, aluminum, gallium and transitional metal elements such as vanadium, nickel, cobalt, copper and iron and surface treatment such as oxidation and formation of surface layer. Since these methods can affect the carbon materials' electronics state, crystal structure and surface structure, the electrochemical properties of the carbon materials could probably be improved. Besides, mechanisms for lithium storage in carbonaceous materials are …


External Transducing Measurement Of The Internal Pressure In Sealed Battery By Resistance Strain Gauge, Hanxi Yang, Ronghui Hu, Xinping Ai, Congzhi Yang, Shengxian Li Aug 1998

External Transducing Measurement Of The Internal Pressure In Sealed Battery By Resistance Strain Gauge, Hanxi Yang, Ronghui Hu, Xinping Ai, Congzhi Yang, Shengxian Li

Journal of Electrochemistry

A novel method to monitor dynamically the internal pressure of sealed battery with no damage of the battery by using of resistance strain measurement technique is presented. This technique employs the resistence strain gauges in touch of the battery case and to detect the minimal change in the battery deformation due to the increasing internal pressure, electrode expantion or intrenal temperature rise. Application of the technique for the study of the effects of the battery processing factors on the battery performance is described taking Ni MH battery as example.


Lithiun Insertion In Carbon Nanotubes, Guotao Wu, Chunsheng Wang, Zhongfu Qi, Wenzhu Li Aug 1998

Lithiun Insertion In Carbon Nanotubes, Guotao Wu, Chunsheng Wang, Zhongfu Qi, Wenzhu Li

Journal of Electrochemistry

Carbon nanotubes were produced by chemical vapour deposition(CVD) of acetylene under hydrogen gas.The reversible specific capacity of carbon nanotubes is up to 700 mAh/g, much higher than the theoretical specific capacity of graphite(372 mAh/g).After twenty charge/discharge cycles,the discharge capacity of carbon nanotube anode still maintains 65.3% of its original discharge capacity . Besides, the charge/discharge efficiency of carbon nanotube in the first charge/discharge cycle was found to improve from 42.6% up to 55.9% by coating carbon nanotubes with copper.


Electrooxidation Of Benzene To Benzoquinone In A Packed Bed Reactor, Xinsheng Zhang, Ping Ding, Yingchun Dai, Weikang Yuan Aug 1998

Electrooxidation Of Benzene To Benzoquinone In A Packed Bed Reactor, Xinsheng Zhang, Ping Ding, Yingchun Dai, Weikang Yuan

Journal of Electrochemistry

A packed electrode reactor was used to oxidize to benzoquinone. Anode bed of the reactor has a size of 10~30 mm×450 mm×50 mm(thickness×length×width),and was packed porous lead alloy. A dispersion of benzene in 1 mol/L aqueous sulfuric acid was passed through the reactor. Current efficiency for benzoquinone generation is 62.9% at optimal operating condition: velocity of electrolyte flow, 0.19 ms -1 ;current, 10 A; thickness of anode bed, 10 mm, and percentage of benzene, 24%.


Study Of Electrocrystallized N(N≥40) Multilayers In Boric Acid Solution, Renhe Yin, Wenguang Shi, Weimin Cao Aug 1998

Study Of Electrocrystallized N(N≥40) Multilayers In Boric Acid Solution, Renhe Yin, Wenguang Shi, Weimin Cao

Journal of Electrochemistry

Co(0.5 nm~2.2 nm)/Pt(2.0 nm)] n(n>40) multilayers were prepared by electrocrystallization on copper and glass carbon with a dual cell technique under potential control.The periodical modulated structure of the multilayers was demonstrated by the low angle X ray diffraction. Potential shift negative to the deposition potential of the Co layer and positive to the deposition potential of the Pt layer decreased the value of the full width at half maximum(FWHM) of first Bragg Peak.CoPt 3 alloy was found as the interface of the multilayers by the middle angle X ray diffraction.The hysteresis loops show that the easy magnetization of these …


Studies On The Electrode Kinetics Of Electrooxidation Of Mn 2+, Wanli Hu, Tong Su, Wei Guo, Ding Zhou Aug 1998

Studies On The Electrode Kinetics Of Electrooxidation Of Mn 2+, Wanli Hu, Tong Su, Wei Guo, Ding Zhou

Journal of Electrochemistry

The mechanism of electrooxidation of MnSO 4 on Pb Sb As alloy anode was investigated by using rotating disc electrode technique. The results shown that the conditional standard potential of Mn(Ⅲ)/Mn(Ⅱ)in 40% H 2SO 4 is 0.886 4 V.The rate controlling step of electrode process is mixed controlled by charge transfer and diffusion.


Study Of Proton Exchange Membrane Fuel Cells(Pemfc), Shanhai Ge, Baolian Yi, Hongfen Xu, Ming Han, Zhigang Shao Aug 1998

Study Of Proton Exchange Membrane Fuel Cells(Pemfc), Shanhai Ge, Baolian Yi, Hongfen Xu, Ming Han, Zhigang Shao

Journal of Electrochemistry

The electrode kinetic parameters for proton exchange membrane fuel cells(PEMFC) were investigated by measuring the relations of cell potential and current density. An experimental stack of PEMFC which can be operated at E cell =0.7V, I =0.55A/cm 2 steadily is presented, and the effects of electrode structure and operation conditions such as temperature, pressure, humidification, flow rate on the performance of PEMFC are discussed.


Influence Of Electrolytes To The Interfacial Electroc Characteristics Of The Porous Membrane Of Anodized Aluminum, Yafe Kuang, Ling Wang, Meiyuan Wang Aug 1998

Influence Of Electrolytes To The Interfacial Electroc Characteristics Of The Porous Membrane Of Anodized Aluminum, Yafe Kuang, Ling Wang, Meiyuan Wang

Journal of Electrochemistry

The influence of electrolytic composition on the interfacial electric Characteristic of the porous membrane membrance of anodized aluminum was investigated with a electrodialytic method. Results indicated that, when the porous membrane was pretreated with F -, PO 3- 4,SiO 2- 3 and tannic acid, the isoelectric point in 0.01 mol/L KCI, were shifted from normal 9.20 to 3.40, 4.30, 3.30 and 4.50, respectively, and responsive characteristics of ζ potential to pH was changed. Furthermore, after pretreatment of porous membrance with fuchsine basic and fuchsine acid solution,there was no isoelectric point at 2.0


The Hydrogen Evolution Reaction On The Hydrogen Storage Alloy Electrode, Shigang Lu, Qun Li, Qingguo Liu, Chun Lu, Bing Dang Aug 1998

The Hydrogen Evolution Reaction On The Hydrogen Storage Alloy Electrode, Shigang Lu, Qun Li, Qingguo Liu, Chun Lu, Bing Dang

Journal of Electrochemistry

The hydrogen evolution reaction was studied in 1 mol/L KOH solution on the hydrogen storage alloy Mm(NiCoMnAl) 5 electrode using open circuit potential decay and ac impedance technique. The reaction was found to proceed by the Volmer(discharge)-Tafel(recombination)mechanism. The measured overpotential η can be subdivided into two components η 1 and η 2 corresponding to the elementary Volmer and Tafel reaction. The Faradaic impedance was analyzed and characterized by the Volmer reaction. Then the exchange current density was evaluated . It was founded that the activity of hydrogen storage alloy electrode for the hydrogen evolution reaction was similar to that of …