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Displaying 52601 - 52625 of 74192

USAXS Studies of Silica Fume Additives in Cements and Concrete

April 1, 1998
Author(s)
Andrew J. Allen, Richard A. Livingston
Supplementary cementitious materials like silica fume, which are added to the cement mix and react with calcium ions in the pore solution, enhance the production of calcium-silicate-hydrate gel and modify the microstructure in other ways. By combining

Wavelengths and Oscillator Strengths for Space Astronomy

April 1, 1998
Author(s)
Craig J. Sansonetti, Joseph Reader
Over a period of more than a decade the Atomic Spectroscopy Group at NIST has carried out laboratory research to support the observing program of the Hubble Space Telescope (HST). Our Initial effort concerned the wavelength calibration of GHRS by means of

X-Ray Diffraction Topography of Sapphire for Windows and Domes

March 30, 1998
Author(s)
David R. Black
X-ray diffraction topography has been used as a nondestructive characterization tool to investigate single-crystal sapphire for window and dome applications. A variety of examples are shown that demonstrate the utility of x-ray diffraction imaging as a

Network Security Testing Using Mobile Agents

March 25, 1998
Author(s)
Athanasios T. Karygiannis
This paper describes a prototype security testing tool that is currently under development at NIST. This prototype tool uses autonomous mobile agents to perform distributed, fault-tolerant, and adaptive network security testing. The security testing

Pb-Distribution in a Five-Phase (Bi, Pd)-Sr-Ca-Cu-O Assemblage

March 12, 1998
Author(s)
Lawrence P. Cook, Winnie K. Wong-Ng
The partitioning of lead between phases in the nominal five-phase assemblage: (Pb,Bi) 3Sr 2Ca 2CuO x + (Ca,Sr) 2PbO 4 + (Bi,Pb) 2Sr 2CaCu 2O x + (Ca,Sr)O + Liquid has been investigated in an atmosphere of 7.5% O 2925% Ar. Samples were studied using a

Damage Modes in Dental Layer Structures

March 7, 1998
Author(s)
Yeon-Gil G. Jung, S Wuttiphan, I M. Peterson, Brian R. Lawn
A study is made of crack patterns in two model coating/substrate bilayer systems conceived to simulate crown and tooth structures, at opposite extremes of elastic/plastic mismatch: porcelain on glass-infiltrated alumina (soft/hard); and glass-ceramic on

Cement Hydration in the Presence of Municipal Solid Waste Incineration Fly Ash.

March 5, 1998
Author(s)
Dale P. Bentz, S Remond, P Pimienta, J P. Bournazel
Incorporating wastes into concrete on an appropriately selective basis could help to solve some of the problems encountered in waste management. Some industrial by-products (fly ash and slag for example) have been used in the manufacture of cement and

Dual wavelength, 980 nm-pumped, Er/Yb-codoped waveguide laser in Ti:LiNbO 3

March 5, 1998
Author(s)
J. Amin, J. A. Aust, D. L. Veasey, Norman Sanford
The authors demonstrate the first Er/Yb codoped waveguide laser in Ti:LiNbO 3. The device was fabricated on x-cut LiNbO 3 with the guides parallel to the x-axis resulting in reduced photorefractive damage and allowing 980nm pumping. Laser operation is

Modeling of Multi-Step Nonlinear Stress Relaxation in DGEBA/M-PDA Epoxy Resins

March 4, 1998
Author(s)
Gale A. Holmes, R C. Peterson, Donald L. Hunston
Multi-step stress relaxation data from a DGEBA/m-PDA epoxy resin is modeled using a nonseparable nonlinear constitutive equation. The form of the equation is based on nonlinear concepts and ideas developed in melt rheology. Although time-strain

On the Bifurcation from Continuous to Segmented Chip Formation in Metal Cutting

March 4, 1998
Author(s)
Timothy J. Burns, Christopher J. Evans, Matthew A. Davies
We describe a new approach to modeling chip formation in orthogonal machining. Metal cutting is interpreted as a nonlinear dynamical process with thermomechanical feedback, which is similar in many ways to an open chemical reactor. As the cutting speed is

Interconnection Continuity Test for Packaged Functional Modules

March 3, 1998
Author(s)
Jan Obrzut
We developed an electrical test to evaluate interconnections in packaged, electrostatic-discharge (ESD) protected modules. The ESD protection circuit, which in modern integrated circuits is present at every I/O as an inherent part of the chip structure
Displaying 52601 - 52625 of 74192
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