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Displaying 40676 - 40700 of 73963

Machining Cracks Revealed by Fractography

August 28, 2003
Author(s)
George D. Quinn, L K. Ives, S Jahanmir
Fractography detected and characterized the nature and size of strength limiting rods and bars in a sintered reaction bonder silicon nitride that was ground by a variety of procedures.

Moving Object Prediction for Off-Road Autonomous Navigation

August 25, 2003
Author(s)
Rajmohan Madhavan, Craig I. Schlenoff
The realization of on- and o.-road autonomous navigation of Unmanned Ground Vehicles (UGVs) requiresreal-time motion planning in the presence of dynamic objects with unknown trajectories. To successfully planpaths and to navigate in an unstructured

A Bridge for Scaling to Higher Resistance from the QHR

August 21, 2003
Author(s)
Randolph Elmquist, Dean G. Jarrett
A two-terminal bridge for resistance scaling directly from the quantum Hall resistance (QHR) to higher-resistance values now provides a secondary starting point in decade scaling at NIST, beginning at the 1 M(Ohm) resistance level. This cryogenic bridge

Changes and Improvements in the 10 k-ohm Special Calibration Service

August 21, 2003
Author(s)
George R. Jones Jr., Marlin E. Kraft, Randolph Elmquist
The 1(ohm) level of resistance has been the source of the lowest standard uncertainties for d.c. resistance calibrations. At the 10 k(ohm) level, equally good transport standards are available and many laboratories also rely on these standards. NIST uses

Expanding the Role of Finite State Machine Technology in Open Architecture Control

August 21, 2003
Author(s)
John L. Michaloski, Frederick M. Proctor, William G. Rippey, S Kolla
Modern machine control systems rely heavily on software to achieve system functionality. Until recently, control software?s primary purpose was to provide logic and sequencing of machine execution. With computer hardware now providing power and memory to

Temperature Scales Using Radiation Thermometers Calibratied From Absolute Irradiance and Radiance Responsivity

August 21, 2003
Author(s)
Howard W. Yoon, David W. Allen, Charles E. Gibson, Robert D. Saunders, Bettye C. Johnson, Steven W. Brown, Keith R. Lykke
In the International Temperature Scale of 1990 (ITS-90), temperatures above the freezing temperature of silver are defined with radiation thermometers calibrated using spectral radiance ratios to one of the silver-, gold- or copper-freezing temperature

User's Manual for Version 1.0 of the NIST DME Interface Test Suite for Facilitating Implementations of Version 1.1 of the I++ DME Interface Specification

August 21, 2003
Author(s)
John A. Horst, Thomas R. Kramer, Joseph A. Falco, Keith A. Stouffer, Hui-Min Huang, Frederick M. Proctor, Albert J. Wavering, Chengying Liu
This user's manual describes version 1.0 of the NIST Dimensional Measuring Equipment (DME) interface test suite intended to support implementations of version 1.1 of the I++ DME specification.

Induced Currents on an EUT in a Free-Space and a Modified TEM Cell Environment

August 19, 2003
Author(s)
Per E. Fornberg, Christopher L. Holloway, Perry F. Wilson
The finite-difference time-domain method is used to investigate whether the currents induced on an equipment under test (EUT) in a TEM cell are similar to those induced in an ideal free-space environment. The approach is to simulate an identical EUT in

Assessing A Loaded Reverberation Chamber: Calculating Threshold Metrics

August 18, 2003
Author(s)
Christopher L. Holloway, David A. Hill, John M. Ladbury, Todd M. Lammers
In this paper we present an expression for two threshold metrics of a loaded reverberation chamber. One metric is based on the chamber quality factor (Q) and the other is based on a useable volume of a loaded reverberation chamber. These metrics are

Evolution of a Performance Metric for Urban Search and Rescue Robots (2003)

August 18, 2003
Author(s)
Adam S. Jacoff, Brian Weiss, Elena R. Messina
This paper discusses the advancement and proliferation of the Reference Test Arenas for Urban Search and Rescue Robots as representative search and rescue environments, which allow objective performance evaluation of mobile robot capabilities. These arenas

NOT (Faster Implementation ==> Better Algorithm), A Case Study

August 18, 2003
Author(s)
Stephen B. Balakirsky, Thomas R. Kramer
Given two algorithms that perform the same task, one may ask which is better. One simple answer is that the algorithm that delivers the ?best? answer is the better algorithm. But what if both algorithms deliver results of similar quality? In this case, a

Quantifying Uncertainty Towards Information-Centric Unmanned Navigation

August 18, 2003
Author(s)
Rajmohan (. Madhavan, Elena R. Messina
Highly imperfect, inconsistent information and incomplete a priori knowledge introduce uncertainty in sensor-centric unmanned navigation systems. Understanding and quantifying uncertainty yields a measure of useful information that plays a critical role in

Total Radiated Power Limits for Emission Measurements in a Reverberation Chamber

August 18, 2003
Author(s)
Christopher L. Holloway, Perry F. Wilson, Galen H. Koepke, Marco Candidi
In this paper we present a total radiated power limit for emission measurements in reverberation chambers. This total radiation power limit is intended to be equivalent to the FCC maximum E-field limit for emission testing over a ground plane.

Toward a Generic Model for Autonomy Levels for Unmanned Systems (ALFUS)

August 18, 2003
Author(s)
Hui-Min Huang, Elena R. Messina, James S. Albus
Unmanned systems (UMSs) have been deployed to military and civilian operations. UMSs vary widely in their capabilities andcivilian operations. UMSs vary widely in their capabilities and purposes. It would be beneficial to have a set of widely recognized

A Study of In-Tube Evaporation Heat Transfer of Carbon Dioxide

August 17, 2003
Author(s)
N N. Sawant, M Kim, William V. Payne, Piotr A. Domanski, Y W. Hwang
The evaporative heat transfer characteristics of carbon dioxide (CO 2) were measured in a fluid-heated, 8.0 mm ID smooth stainless steel tube. The test apparatus was a concentric tube heat exchanger heated by water in the annulus with CO 2 in the central

Operating Margin Measurements for an AC Josephson Voltage Standard

August 17, 2003
Author(s)
Charles J. Burroughs, Samuel Benz, Paul Dresselhaus
For a number of years, NIST has been developing a Josephson arbitrary waveform synthesizer as an ac Josephson Voltage Standard (ACJVS). The effort has primarily focused on increasing the output voltage to practical levels. Recent advances in circuit design
Displaying 40676 - 40700 of 73963
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