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in creator/contributor: "Defense Advanced Research Projects Agency, Arlington, VA United States"  
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open access

A zooming Web browser

Description: We are developing a prototype zooming World-Wide Web browser within Pad++, a multiscale graphical environment. Instead of having a single page visible at a time, multiple pages and the links between them are depicted on a large zoomable information surface. Pages are scaled so that the page in focus is clearly readable with connected pages shown at smaller scales to provide context. We quantitatively compared performance with the Pad++ Web browser and Netscape in several different scenarios. We… more
Date: December 31, 1996
Creator: Bederson, Benjamin B.; Hollan, James D.; Stewart, Jason; Rogers, David; Vick, David; Ring, Laura et al.
Partner: UNT Libraries Government Documents Department
open access

Rf Magnetron Sputter-Deposition of La{Sub 0.5}Coo{Sub 3}//Pt Composite Electrodes for Pb(Zr,Ti)O{Sub 3} Thin Film Capacitors

Description: La{sub 0.5}Sr{sub 0.5}CoO{sub 3} (LSCO) thin films have been deposited using RF magnetron sputter-deposition for use as an electrode material for PZT (PbZrTiO{sub 3}) thin film capacitors. Effect of O{sub 2}:Ar sputter gas ratio during deposition, on LSCO film properties was studied. It was found that the resistivity of the LSCO films deposited at ambient temperature decreases as the O{sub 2}: Ar ratio was increased for both as-deposited and annealed films. It was also found that thin overlayer… more
Date: July 1, 1996
Creator: Raymond, M. V.; Al-Shareef, H. N.; Tuttle, B. A.; DiMos, D. & Evans, J. T.
Partner: UNT Libraries Government Documents Department
open access

Barriers to creating a secure MPI

Description: This paper explores some of the many issues in developing security enhanced MPI for embedded real-time systems supporting the Department of Defense`s Multi-level Security policy (DoD MLS) are presented along with the preliminary design for such an MPI variant. In addition some of the many issues that need to be addressed in creating security enhanced versions of MPI for other domains are discussed. 19 refs.
Date: August 1, 1997
Creator: Brightwell, R.; Greenberg, D.S.; Matt, B.J. & Davida, G.I.
Partner: UNT Libraries Government Documents Department
open access

Active chatter control in a milling machine

Description: The use of active feedback compensation to mitigate cutting instabilities in an advanced milling machine is discussed in this paper. A linear structural model delineating dynamics significant to the onset of cutting instabilities was combined with a nonlinear cutting model to form a dynamic depiction of an existing milling machine. The model was validated with experimental data. Modifications made to an existing machine model were used to predict alterations in dynamics due to the integration o… more
Date: August 1, 1997
Creator: Dohner, J. L.; Hinnerichs, T. D. & Lauffer, J. P.
Partner: UNT Libraries Government Documents Department
open access

A directory service for configuring high-performance distributed computations

Description: High-performance execution in distributed computing environments often requires careful selection and configuration not only of computers, networks, and other resources but also of the protocols and algorithms used by applications. Selection and configuration in turn require access to accurate, up-to-date information on the structure and state of available resources. Unfortunately, no standard mechanism exists for organizing or accessing such information. Consequently, different tools and appli… more
Date: August 1, 1997
Creator: Fitzgerald, S.; Kesselman, C. & Foster, I.
Partner: UNT Libraries Government Documents Department
open access

Characterization of novel powder and thin film RGB phosphors for field emissions display application

Description: The spectral response, brightness and outgassing characteristics of new, low-voltage phosphors for application in field-emission flat-panel displays, are presented. The tested phosphor materials include combustion synthesized powders and thin films prepared by RF-diode or magnetron sputtering, laser ablation and molecular beam epitaxy. These cathodoluminescent materials are tested with e-beam excitation at currents up to 50 {mu}A within the 200-2000V (e.g. {open_quotes}low-voltage{close_quotes}… more
Date: December 31, 1996
Creator: Chakhovskoi, A.G.; Hunt, C.E.; Malinowski, M.E.; Felter, T.E. & Talin, A.A.
Partner: UNT Libraries Government Documents Department
open access

Voltage shifts and defect-dipoles in ferroelectric capacitors

Description: We review the processes and mechanisms by which voltage offsets occur in the hysteresis loop of ferroelectric materials. Simply stated, voltage shifts arise from near-interfacial charge trapping in the ferroelectric. We show that the impetus behind voltage shifts in ferroelectric capacitors is the net polarization, with the net polarization being determined by the perovskite and the aligned defect-dipole components. Some common defect-dipoles in the PZT system are lead vacancy-oxygen vacancy co… more
Date: December 1, 1996
Creator: Warren, W.L.; Pike, G.E. & Dimos, D.
Partner: UNT Libraries Government Documents Department
open access

Techniques for evaluation of E-beam evaporative processes

Description: High dynamic range video imaging of the molten pool surface has provided insight regarding process responses at the melt pool liquid-vapor interface. A water-cooled video camera provides continuous high resolution imaging of the pool surface from a low angle position within 20 cm of the liquid-vapor interface. From the vantage point, the e-beam footprint is clearly defined and melt pool free surface shape can be observed. Effects of changes in a beam footprint, power distribution, and sweep fre… more
Date: October 1, 1996
Creator: Meier, T.C. & Nelson, C.M.
Partner: UNT Libraries Government Documents Department
open access

Selecting tense, aspect, and connecting words in language generation

Description: Generating language that reflects the temporal organization of represented knowledge requires a language generation model that integrates contemporary theories of tense and aspect, temporal representations, and methods to plan text. This paper presents a model that produces complex sentences that reflect temporal relations present in underlying temporal concepts. The main result of this work is the successful application of constrained linguistic theories of tense and aspect to a generator whic… more
Date: December 31, 1995
Creator: Gaasterland, T. & Dorr, B.
Partner: UNT Libraries Government Documents Department
open access

Systems thinking for manufacturing: Distributed, multi-disciplinary simulations for graduate education

Description: This project summary first discusses the methodology employed, distributed interactive simulation, then describes the architecture and some of the features of the project, and finally examines potential applications in graduate education. A distributed simulation is one composed of different modules that are resident on different computers. The top-level model consists of a number of integrated sub-models which exchange data. The sub-models are part of a functional whole; they are linked to eac… more
Date: October 1, 1997
Creator: Hahn, H. & Kunsberg, P.
Partner: UNT Libraries Government Documents Department
open access

Hydrogen Diffusion and Chemistry During the Annealing-Induced Generation of Mobile Protons in the Oxide Layer of Si/SiO{Sub 2}/Si Capacitors

Description: In a number of recent studies the generation of mobile protons in the buried oxide of SOI materials and in thermal oxide buried underneath a poly-Si layer has been discussed. The protons are found to be stable and can be easily rearranged by applying an electric field. The details of the hydrogen reactions leading to the generation of the mobile H{sup +} are still under investigation. In a recent work a dynamic equilibrium model was presented. The forward reaction dominates above {approximately… more
Date: September 1, 1998
Creator: Vanhuesden, K.; Devine, R. A. B.; Fleetwood, D. M. & Warren, W. L.
Partner: UNT Libraries Government Documents Department
open access

Evolutionary dynamics on random structures

Description: In this paper the authors consider the evolutionary dynamics of populations of sequences, under a process of selection at the phenotypic level of structures. They use a simple graph-theoretic representation of structures which captures well the properties of the mapping between RNA sequences and their molecular structure. Each sequence is assigned to a structure by means of a sequence-to-structure mapping. The authors make the basic assumption that every fitness landscape can be factorized thro… more
Date: April 1, 1997
Creator: Fraser, S. M. & Reidys, C. M.
Partner: UNT Libraries Government Documents Department
open access

Investigation of Wavelet-Based Enhancements to Nuclear Quadrupole Resonance Explosives Detectors

Description: Nuclear Quadrupole Resonance (NQR) is effective for the detection and identification of certain types of explosives such as RDX, PETN and TNT. In explosive detection, the NQR response of certain 14N nuclei present in the crystalline material is probed. The 14N nuclei possess a nuclear quadrupole moment which in the presence of an electric field gradient produces an energy level splitting which may be excited by radio-frequency magnetic fields. Pulsing on the sample with a radio signal of the ap… more
Date: June 1, 1998
Creator: Kercel, Stephen W.; Dress, William B.; Hibbs, Andrew D. & Barrall, Geoffrey A.
Partner: UNT Libraries Government Documents Department
open access

Ultra-thin overcoats for the head/disk interface tribology

Description: Areal density in magnetic storage is increasing at a blistering pace of 60% annually. Recently IBM announced its mobile product with the industry highest areal density of 2.64 Gb/In{sup 2}. The areal density demonstrations have shown up to 5 Gb/In{sup 2} possible. Reaching higher areal density targets dictate that magnetic spacing between heads and disks be reduced. For the example of a 10 Gb/In{sup 2} areal density goal, the magnetic spacing should be {approx}25 nm. In budgeting this magnetic … more
Date: May 1997
Creator: Bhatia, C. S.; Anders, S. & Brown, I. G.
Partner: UNT Libraries Government Documents Department
open access

Unique interactive projection display screen

Description: Projection systems continue to be the best method to produce large (1 meter and larger) displays. However, in order to produce a large display, considerable volume is typically required. The Polyplanar Optic Display (POD) is a novel type of projection display screen, which for the first time, makes it possible to produce a large projection system that is self-contained and only inches thick. In addition, this display screen is matte black in appearance allowing it to be used in high ambient lig… more
Date: November 1, 1997
Creator: Veligdan, J.T.
Partner: UNT Libraries Government Documents Department
open access

Processing challenges for GaN-based photonic and electronic devices

Description: The wide gap materials SiC, GaN and to a lesser extent diamond are attracting great interest for high power/high temperature electronics. There are a host of device processing challenges presented by these materials because of their physical and chemical stability, including difficulty in achieving stable, low contact resistances, especially for one conductivity type, absence of convenient wet etch recipes, generally slow dry etch rates, the high temperatures needed for implant activation, cont… more
Date: September 1, 1997
Creator: Pearton, S.J.; Ren, F. & Shul, R.J.
Partner: UNT Libraries Government Documents Department
open access

On properties of boundaries and electron conductivity in mesoscopic polycrystalline silicon films for memory devices

Description: The authors present the results of MD modeling on the structural properties of grain boundaries (GB) in thin polycrystalline films. The transition from crystalline boundaries with low mismatch angle to amorphous boundaries is investigated. It is shown that the structures of the GBs satisfy a thermodynamical criterion suggested in a cited reference. The potential energy of silicon atoms is closely related with a geometrical quantity -- tetragonality of their coordination with their nearest neigh… more
Date: February 1, 1998
Creator: Berman, G. P.; Doolen, G. D.; Mainieri, R.; Rehacek, J.; Campbell, D. K.; Luchnikov, V. A. et al.
Partner: UNT Libraries Government Documents Department
open access

Resistance behavior of Cr-Si-O thin films

Description: Thin coatings of Cr-Si-O are assessed for use as a resistor. The submicron thick films are sputter deposited using a (l-x)Ar-(x)O{sub 2} working gas. Several compacts of metal and oxide powders are commercially prepared for use as the sputter targets. The deposition process yields film compositions which range from 2 to 30 at.% Cr and 20 to 45 at.% Si as measured using Rutherford backscattering. A broad range of resistivities from 10{sup 1} to 10{sup 14}{Omega} cm are found as measured through … more
Date: October 23, 1996
Creator: Jankowski, Alan Frederic; Hayes, Jeffrey P.; Musket, R.; Cosandey, F.; Gorla, Chandrasekhar E.; Besser, Ronald S. et al.
Partner: UNT Libraries Government Documents Department
open access

Scalable Networked Information Processing Environment (SNIPE)

Description: SNIPE is a metacomputing system that aims to provide a reliable, secure, fault tolerant environment for long term distributed computing applications and data stores across the global Internet. This system combines global naming and replication of both processing and data to support large scale information processing applications leading to better availability and reliability than currently available with typical cluster computing and/or distributed computer environments.
Date: November 1, 1997
Creator: Fagg, G. E.; Moore, K.; Dongarra, J. J. & Geist, A.
Partner: UNT Libraries Government Documents Department
open access

Low damage, highly anisotropic dry etching of SiC

Description: A parametric study of the etching characteristics of 6H p{sup +} and n{sup +} SiC and thin film SiC{sub 0.5}N{sub 0.5} in Inductively Coupled Plasma NF{sub 3}/O{sub 2} and NF{sub 3}/Ar discharges has been performed. The etch rates in both chemistries increase monotonically with NF{sub 3} percentage and rf chuck power. The etch rates go through a maximum with increasing ICP source power, which is explained by a trade-off between the increasing ion flux and the decreasing ion energy. The anisotro… more
Date: March 1, 1998
Creator: Wang, J. J.; Hong, J.; Lambers, E. S.; Pearton, S. J.; Ren, F.; Ostling, M. et al.
Partner: UNT Libraries Government Documents Department
open access

Parallel matrix transpose algorithms on distributed memory concurrent computers

Description: This paper describes parallel matrix transpose algorithms on distributed memory concurrent processors. We assume that the matrix is distributed over a P {times} Q processor template with a block scattered data distribution. P, Q, and the block size can be arbitrary, so the algorithms have wide applicability. The algorithms make use of non-blocking, point-to-point communication between processors. The use of nonblocking communication allows a processor to overlap the messages that it sends to di… more
Date: December 31, 1994
Creator: Choi, Jaeyoung; Dongarra, J. & Walker, D. W.
Partner: UNT Libraries Government Documents Department
open access

Current transport in W and WSI{sub x} ohmic contacts to InGaN and InN

Description: The temperature dependence of the specific contact resistance of W and WSi{sub 0.44} contacts on n{sup +} In{sub 0.65}Ga{sub 0.35}N and InN was measured in the range -50 {degrees}C to 125 {degrees}C. The results were compared to theoretical values for different conduction mechanisms, to further elucidate the conduction mechanism in these contact schemes for all but as-deposited metal to InN where thermionic emission appears to be the dominant mechanism. The contacts were found to produce low sp… more
Date: October 1, 1997
Creator: Vartuli, C. B.; Pearton, S. J. & Abernathy, C. R.
Partner: UNT Libraries Government Documents Department
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