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open access

HCCI Combustion: Analysis and Experiments

Description: Homogeneous charge compression ignition (HCCI) is a new combustion technology that may develop as an alternative to diesel engines with high efficiency and low NOx and particulate matter emissions. This paper describes the HCCI research activities being currently pursued at Lawrence Livermore National Laboratory and at the University of California Berkeley. Current activities include analysis as well as experimental work. On analysis, we have developed two powerful tools: a single zone model an… more
Date: May 14, 2001
Creator: Aceves, Salvador M.; Flowers, Daniel L.; Martinez-Frias, Joel; Smith, J. Ray; Dibble, Robert; Au, Michael et al.
Partner: UNT Libraries Government Documents Department
open access

An integrated solution for secure group communication in wide-area networks

Description: Many distributed applications require a secure reliable group communication system to provide coordination among the application components. This paper describes a secure group layer (SGL) which bundles a reliable group communication system, a group authorization and access control mechanism, and a group key agreement protocol to provide a comprehensive and practical secure group communication platform. SGL also encapsulates the standard message security services (i.e, confidentiality, authenti… more
Date: April 1, 2001
Creator: Agarwal, Deborah A.; Chevassut, Olivier; Thompson, Mary & Tsudik, Gene
Partner: UNT Libraries Government Documents Department
open access

Network aware distributed applications

Description: Most distributed applications today manage to utilize only a small percentage of the needed and available network bandwidth. Often application developers are not aware of the potential bandwidth of the network, and therefore do not know what to expect. Even when application developers are aware of the specifications of the machines and network links, they have few resources that can help determine why the expected performance was not achieved. What is needed is a ubiquitous and easy-to-use serv… more
Date: February 4, 2001
Creator: Agarwal, Deborah; Tierney, Brian L.; Gunter, Dan; Lee, Jason & Johnston, William
Partner: UNT Libraries Government Documents Department
open access

GEM-type detectors using LIGA and etchable glass technologies

Description: Gas electron multipliers (GEMS) have been made by a deep X-ray lithography technique (LIGA process) using synchrotron radiation on polymethylmethacrylate (PMMA) and by UV processes using a UV etchable glass. Gain, stability and rate capability for these detectors are described.The LIGA detectors described consist of PMMA sheets of various thicknesses, 125mm to 350mm, and have 150mm x 150mm square holes spaced with a pitch of 300mm. Thin copper electrodes are plated on the top and bottom surface… more
Date: November 2, 2001
Creator: Ahn, S. K.; Kim, J. G.; Perez-Mendez, V.; Chang, S.; Jackson, K. H.; Kadyk, J. A. et al.
Partner: UNT Libraries Government Documents Department
open access

Characterizing the fabric of the urban environment: A case study of Salt Lake City, Utah

Description: Urban fabric data are needed in order to estimate the impact of light-colored surfaces (roofs and pavements) and urban vegetation (trees, grass, shrubs) on the meteorology and air quality of a city, and to design effective implementation programs. In this report, we discuss the result of a semi-automatic Monte-Carlo statistical approach used to develop data on surface-type distribution and city-fabric makeup (percentage of various surface-types) using aerial color orthophotography. The digital … more
Date: February 28, 2001
Creator: Akbari, Hashem & Rose, L. Shea
Partner: UNT Libraries Government Documents Department
open access

Characterizing the fabric of the urban environment: A case studyof Metropolitan Chicago, Illinois and Executive Summary

Description: Urban fabric data are needed in order to estimate the impactof light-colored surfaces (roofs and pavements) and urban vegetation(trees, grass, shrubs) on the meteorology and air quality of a city, andto design effective implementation programs. In this report, we discussthe result of a semi-automatic Monte-Carlo statistical approach used todevelop data on surface-type distribution and city-fabric makeup(percentage of various surface-types) using aerial colororthophotography. The digital aerial … more
Date: October 30, 2001
Creator: Akbari, Hashem & Rose, Leanna Shea
Partner: UNT Libraries Government Documents Department
open access

Wear and friction behavior of Zr implanted D3 steel

Description: Multicharged, pure, high current and pulsed ion beams of Zr have been extracted from a metal vapor vacuum arc (MEVVA) source and implanted into AISI D3 (C: 2-2,35%, Mn: 0,60%, Si: 0,60%, Cr: 11-13,50%, Ni: 0,30%, W: 1%, V: 1%) tool steel samples at the 3,6.1016, 5.1016 and 1.1017 ions/cm2 doses. The wear resistance and friction coefficient have been estimated using pin-on-disc wear tests. Implantation of Zr decreased the wear loss and friction coefficient. RBS, AES and SEM Microprobe analyses w… more
Date: August 23, 2001
Creator: Akbas, N.; Saklakoglu, I.E.; Monteiro, O.R. & Brown, I.G.
Partner: UNT Libraries Government Documents Department
open access

Impact of the implementation of MPI point-to-point communications on the performance of two general sparse solvers

Description: We examine the mechanics of the send and receive mechanism of MPI and in particular how we can implement message passing in a robust way so that our performance is not significantly affected by changes to the MPI system. This leads us to using the Isend/Irecv protocol which will entail sometimes significant algorithmic changes. We discuss this within the context of two different algorithms for sparse Gaussian elimination that we have parallelized. One is a multifrontal solver called MUMPS, the … more
Date: October 10, 2001
Creator: Amestoy, Patrick R.; Duff, Iain S.; L'Excellent, Jean-Yves & Li, Xiaoye S.
Partner: UNT Libraries Government Documents Department
open access

Three-Dimensional Position-Sensitive Germanium Detectors

Description: Critical to the DOE effort to deactivate and decommission the weapons complex facilities is the characterization of contaminated equipment and building structures. This characterization includes the isotopic identification of radioactive contaminants and the spatial mapping of these deposits. The penetrating nature of the gamma rays emitted by the radioactive contaminants provides a means to accomplish this task in a passive, non-destructive and non-intrusive manner. Through conventional gamma-… more
Date: September 30, 2001
Creator: Amman, Mark & Luke, Paul
Partner: UNT Libraries Government Documents Department
open access

EMSP Project Number 65015 Final Report: Three-dimensional position-sensitive germanium detectors

Description: Critical to the DOE effort to deactivate and decommission the weapons complex facilities is the characterization of contaminated equipment and building structures. This characterization includes the isotopic identification of radioactive contaminants and the spatial mapping of these deposits. The penetrating nature of the gamma rays emitted by the radioactive contaminants provides a means to accomplish this task in a passive, non-destructive and non-intrusive manner. Through conventional gamma-… more
Date: December 7, 2001
Creator: Amman, Mark & Luke, Paul N.
Partner: UNT Libraries Government Documents Department
open access

Alpha particle response characterization of CdZnTe

Description: The coplanar-grid as well as other electron-only detection techniques are effective in overcoming some of the material problems of CdZnTe and, consequently, have led to efficient gamma-ray detectors with good energy resolution while operating at room temperature. The performance of these detectors is limited by the degree of uniformity in both electron generation and transport. Despite recent progress in the growth of CdZnTe material, small variations in these properties remain a barrier to the… more
Date: June 28, 2001
Creator: Amman, Mark; Lee, Julie S. & Luke, Paul N.
Partner: UNT Libraries Government Documents Department
open access

Atomic scale heating in energetic plasma deposition

Description: Energetic deposition using filtered cathodic arc plasma is known to lead to well adherent and dense films. Interface mixing, subplantation depth, texture, and stress of the growing film are often studied as a function of the kinetic energy of condensing ions. Ions have also potential energy contributing to atomic scale heating, secondary electron emission and potential sputtering, thereby affecting all film properties. A table is presented showing kinetic and potential energies of ions in catho… more
Date: September 28, 2001
Creator: Anders, Andre
Partner: UNT Libraries Government Documents Department
open access

From plasma immersion ion implantation to deposition: A historical perspective on principles and trends

Description: Plasma immersion techniques of surface modification are known under a myriad of names. The family of techniques reaches from pure plasma ion implantation, to ion implantation and deposition hybrid modes, to modes that are essentially plasma film deposition with substrate bias. In the most general sense, all plasma immersion techniques have in common that the surface of a substrate (target) is exposed to plasma and that relatively high substrate bias is applied. The bias is usually pulsed. In th… more
Date: June 14, 2001
Creator: Anders, Andre
Partner: UNT Libraries Government Documents Department
open access

Reducing ion beam noise of vacuum arc ion sources

Description: Vacuum arc ion sources are known for delivering high currents of metal ion beams. By Langmuir probe and Faraday cup measurements it is shown that fluctuations of the ion beam current are due to the fluctuations of plasma density which in turn are due to the explosive nature of plasma production at cathode spots. Humphries and co-workers and later Oks and co-workers have shown that beam fluctuations can be reduced by inserting biased meshes in the plasma. Here, the idea of ion extraction at kV-l… more
Date: August 29, 2001
Creator: Anders, Andre & Hollinger, Ralph
Partner: UNT Libraries Government Documents Department
open access

Ion flux from vacuum arc cathode spots in the absence and presence of a magnetic field

Description: Because plasma production at vacuum cathode spots is approximately proportional to the arc current, arc current modulation can be used to generate ion current modulation that can be detected far from the spot using a negatively biased ion collector. The drift time to the ion detector can used to determine kinetic ion energies. A very wide range of cathode materials have been used. It has been found that the kinetic ion energy is higher at the beginning of each discharge and approximately consta… more
Date: October 2, 2001
Creator: Anders, Andre & Yushkov, George Yu.
Partner: UNT Libraries Government Documents Department
open access

Ultrathin diamond-like carbon films deposited by filtered carbon vacuum arcs

Description: Ultrathin (< 5 nm) hard carbon films are of great interest to the magnetic storage industry as the areal density approaches 100 Gbit/in{sup 2}. These films are used as overcoats to protect the magnetic layers on disk media and the active elements of the read-write slider. Tetrahedral amorphous carbon films can be produced by filtered cathodic arc deposition, but the films will only be accepted by the storage industry only if the ''macroparticle'' issue has been solved. Better plasma filters … more
Date: July 13, 2001
Creator: Anders, Andre; Fong, Walton; Kulkarni, Ashok; Ryan, Francis W. & Bhatia, C. Singh
Partner: UNT Libraries Government Documents Department
open access

Interactions of proteins in aqueous ammonium-sulfate solutions:Mixtures of lysozyme and ovalbumin

Description: We present a three-dimensional, time-dependent simulation of a laboratory-scale rod-stabilized premixed turbulent V-flame. The simulations are performed using an adaptive time-dependent low Mach number model with detailed chemical kinetics and a mixture model for differential species diffusion. The algorithm is based on a second-order projection formulation and does not require an explicit sub grid model for turbulence or turbulence chemistry interaction. Adaptive mesh refinement is used to dyn… more
Date: November 10, 2001
Creator: Anderson, Camille O.; Prausnitz, John M. & Blanch, Harvey W.
Partner: UNT Libraries Government Documents Department
open access

Effect of secondary structure on the interactions of peptide T4 LYS (11-36) in mixtures of aqueous sodium chloride and 2,2,2,-Trifluoroethanol

Description: The potential of mean force for protein-protein interactions is key to the development of a statistical-mechanical model for salt-induced protein precipitation and crystallization, and for understanding certain disease states, including cataract formation and {beta}-amyloid pathology in Alzheimer's disease. Fluorescence anisotropy provides a method for quantitative characterization of intermolecular interactions due to reversible association. Monomer-dimer equilibria for the peptide T4 LYS(11-3… more
Date: October 1, 2001
Creator: Anderson, Camille O.; Spiegelberg, Susanne; Prausnitz, John M. & Blanch, Harvey W.
Partner: UNT Libraries Government Documents Department
open access

Report on HVAC Option Selections for a Relocatable Classroom Energy and Indoor Environmental Quality Field Study

Description: It is commonly assumed that efforts to simultaneously develop energy efficient building technologies and to improve indoor environmental quality (IEQ) are unfeasible. The primary reason for this is that IEQ improvements often require additional ventilation that is costly from an energy standpoint. It is currently thought that health and productivity in work and learning environments requires adequate, if not superior, IEQ. Despite common assumptions, opportunities do exist to design building sy… more
Date: October 11, 2001
Creator: Apte, Michael G.; Delp, Woody W.; Diamond, Richard C.; Hodgson, Alfred T.; Kumar, Satish; Rainer, Leo I. et al.
Partner: UNT Libraries Government Documents Department
open access

Improving Information Technology to Maximize Fenestration Energy Efficiency

Description: Improving software for the analysis of fenestration product energy efficiency and developing related information technology products that aid in optimizing the use of fenestration products for energy efficiency are essential steps toward ensuring that more efficient products are developed and that existing and emerging products are utilized in the applications where they will produce the greatest energy savings. Given the diversity of building types and designs and the climates in the U.S., no … more
Date: June 6, 2001
Creator: Arasteh, Dariush; Mitchell, Robin; Kohler, Christian; Huizenga,Charlie & Curcija, Dragan
Partner: UNT Libraries Government Documents Department
open access

Effect of catalyst structure on oxidative dehydrogenation of ethane and propane on alumina-supported vanadia

Description: The catalytic properties of Al2O3-supported vanadia with a wide range of VOx surface density (1.4-34.2 V/nm2) and structure were examined for the oxidative dehydrogenation of ethane and propane. UV-visible and Raman spectra showed that vanadia is dispersed predominantly as isolated monovanadate species below {approx}2.3 V/nm2. As surface densities increase, two-dimensional polyvanadates appear (2.3-7.0 V/nm2) along with increasing amounts of V2O5 crystallites at surface densities above 7.0 V/nm… more
Date: September 11, 2001
Creator: Argyle, Morris D.; Chen, Kaidong; Bell, Alexis T. & Iglesia, Enrique
Partner: UNT Libraries Government Documents Department
open access

Anomalies on orbifolds

Description: We discuss the form of the chiral anomaly on an S1/Z2 orbifold with chiral boundary conditions. We find that the 4-divergence of the higher-dimensional current evaluated at a given point in the extra dimension is proportional to the probability of finding the chiral zero mode there. Nevertheless the anomaly, appropriately defined as the five dimensional divergence of the current, lives entirely on the orbifold fixed planes and is independent of the shape of the zero mode. Therefore long distanc… more
Date: March 16, 2001
Creator: Arkani-Hamed, Nima; Cohen, Andrew G. & Georgi, Howard
Partner: UNT Libraries Government Documents Department
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