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Nonlinear Least Squares Regression Using STARPAC: The Standards Time Series and Regression Package

Description: from Preface: This Note documents 16 subroutines for nonlinear least squares regression. Twelve of these compute the least squares estimates, performing either weighted or unweighted analysis with either numerically approximated or user-supplied (analytic) derivatives. The other four are user-callable subroutines for two procedures used within the estimation code: the first selects optimum step sizes for approximating the partial derviatives of the model; and the second checks the validity of a user-supplied derivative subroutine.
Date: October 1983
Creator: Donaldson, Janet R. & Tryon, Peter V.
Item Type: Report
Partner: UNT Libraries Government Documents Department

Beam-Profile Measurement of Laser Pulses Using a Spatial Filter to Sample the Hermite Modes of a String of Pulses

Description: Abstract: As a first step in the development of a beam-profile measuring instrument for laser sources that is capable of determining the distribution of low-order (less than 25) Hermitian modes in a series of laser pulses, I designed and evaluated the three key parts of such an instrument. First, there is the telescope system which allows the incident laser beam to be phase, beamwidth, and beam center matched to the optical spatial filter. Second, there is a brief error analysis of the structure of the mismatch function between the beam out of the telescope and that expected by the filter. Finally, there is the detailed analysis and design of the computer-generated spatial filter that will cause the incident-laser beam to be cross correlated with the low-order Hermite modes and will create an array of light spots in the detector (Fourier transform) plane each of which can be uniquely related to a particular Hermite mode of the original laser pulse. The principal conclusion is that the Hermite mode analysis can be done with better than 99 percent separation between modes, provided the phase between modes is uncorrelated from pulse to pulse when the filter has been fabricated with a two-level, gray-scale structure which samples the profile with either 0 percent, or 100 percent transmission.
Date: September 1982
Creator: Johnson, Eric Gunnar, Jr.
Item Type: Report
Partner: UNT Libraries Government Documents Department

A Method to Quantify the Radiation Characteristics of an Unknown Interference Source

Description: from Introduction: A new method for determining the radiation characteristics of leakage from electronic equipment for interference studies is described in this report. Basically, an unintentional leakage source is considered to be electrically small, and may be characterized by three equivalent orthogonal electric dipole moments and three equivalent orthogonal magnetic dipole moments. When an unknown source object is placed at the center of a transverse electromagnetic (TEM) cell, its radiated energy couples into the fundamental transmission mode and propagates toward the two output ports of the TEM cell. With a hybrid junction inserted into a loop connecting the cell output ports, one is able to measure the sum and difference powers and the relative phase between the sum and difference outputs. Systematic measurements of these powers and phases at six different source object positions, based on a well-developed theory, are sufficient to determine the amplitudes and phases of the unknown component dipole moments, from which the detailed free-space radiation pattern of the unknown source and the total radiated power can be determined. Results of simulated theoretical examples and an experiment using a spherical dipole radiator are given to illustrate the theory and measurement procedure.
Date: October 1982
Creator: Ma, Mark T. & Koepke, Galen H.
Item Type: Report
Partner: UNT Libraries Government Documents Department

A System for Measuring Energy and Peak Power of Low-Level 1.064 [mu]m Laser Pulses

Description: from Introduction: For the first time, transfer standards have been developed for measuring 1.064 Pm laser pulses of duration about 10-100 ns, peak irradiance of about 10-8-10-4 W/cm2, and fluences of about 10-16-10-11 J/cm2 . These energy and power measurement devices use PIN and APD silicon detectors, respectively, and can be used as stable transfer standards with total uncertainties (random errors computed at the 95 percent confidence level) of 10 to 15 percent. The system for calibrating these transfer standards is also described and consists of a cw Nd:YAG laser beam acousto-optically modulated to provide low-level laser pulses of known peak power and energy. A detailed evaluation of systematic and random errors is also shown.
Date: October 1982
Creator: Sanders, A. A. & Rasmussen, A. L.
Item Type: Report
Partner: UNT Libraries Government Documents Department

An Equation of State for Fluid Ethylene

Description: Abstract: A thermodynamic property formulation for ethylene, developed as a part of a joint industry-government project, is presented. The formulation includes an equation of state, vapor pressure equation, and equation for the ideal gas heat capacity. The coefficients were determined by a least squares fit of selected experimental data. Comparisons of property values calculated using the equation of state with measured values are given. The equation of state is not valid in the critical region (pc + 0.3 pc for temperatures of Tc + 0.05 Tc). Errors on the order of 20 percent for derived properties and 10 percent for density may be encountered near the critical point. Tables of the thermodynamic properties of ethylene for the liquid and vapor phases for temperatures from the freezing line to 450 K with pressures to 40 MPa are presented. The equation of state and its derivative and integral functions for calculating thermodynamic properties are included. Estimates of the accuracy of calculated properties are given. A guide for use of computer programs for the calculation of thermodynamic properties of ethylene with listings of subprograms and a sample program to illustrate the use and results of the program are included.
Date: July 1981
Creator: McCarty, Robert D. & Jacobsen, Richard T.
Item Type: Report
Partner: UNT Libraries Government Documents Department

WR 10 Millimeter Wave Microcalorimeter

Description: Abstract: A microcalorimeter has been built in WR 10 waveguide, 75-110 GHz, to serve as a power standard at the National Bureau of Standards (NBS). Included here is an evaluation of the errors in using the microcalorimeter for the measurement of effective efficiency of bolometer mounts. The error analysis shows a systematic uncertainty of +/- .83 percent and a random uncertainty of .37 percent.
Date: June 1981
Creator: Weidman, Manly P. & Hudson, Paul A.
Item Type: Report
Partner: UNT Libraries Government Documents Department

Geological Survey Investigations in the U12b.01 Tunnel, Nevada Test Site

Description: from Introduction: This report includes a brief description of the stratigraphy and structure, and data on petrology, mineralogy, and chemical and physical properties of the rocks that are exposed in the U12b.01 tunnel of the U12b (Rainier) tunnel system.
Date: March 1959
Creator: Diment, William H.; Wilmarth, V. R.; McKeown, F. A.; Dickey, D. D.; Botinelly, Theodore; Hinrichs, E. Neal. et al.
Item Type: Report
Partner: UNT Libraries Government Documents Department

Salt at Shallow Depths in the Coastal Plain of Texas and Louisiana

Description: from Introduction: Salt occurs at depths less than 500 feet in six salt domes in Texas and Louisiana (fig. 1). Underground mining operations are being carried out in each of these domes. The following notes have been prepared in an effort to furnish data regarding chemical composition and structure of the rock salt in the shallow deposits.
Date: April 1959
Creator: Read, Charles B.
Item Type: Report
Partner: UNT Libraries Government Documents Department

A Coaxial Noise Standard for the 1 GHz to 12.4 GHz Frequency Range

Description: from Introduction: This note describes the design and construction of a coaxial thermal noise standard. The standard is designed to operate at the boiling point of liquid nitrogen with a noise temperature accurate to t 1 K in the frequency range from 1 GHz to 12.4 GHz.
Date: 1984
Creator: Daywitt, William C.
Item Type: Report
Partner: UNT Libraries Government Documents Department

A Review of Supercritical Fluid Extraction

Description: Forward: The purpose of this report is to summarize the results obtained from a brief investigation of supercritical fluid extraction principles and applications. This study was one portion of a project funded by the U.S. Department of Energy, Office of Fossil Energy, contract nuriber DE-AI01076PR06010, in response to a preliminary proposal submitted by the authors. This report sometimes uses company trade naries to identify processes and patent holders. This usage implies no endorsement by HBS. Note also that some figures reproduced from other sources do not conform with NBS policy concerning SI units.
Date: December 1983
Creator: Ely, James F. & Baker, Jolene K.
Item Type: Report
Partner: UNT Libraries Government Documents Department

Phase Equilibria: an Informal Symposium

Description: from Introduction: The accurate prediction of phase equilibria plays an important. role in the chemical process industries. A grief overview of final phase equilibria predictive techniques is presented with special emphasis on methods in current use in industry. Areas were better fundamental understanding will lead to improved models are discussed whenever possible.
Date: January 1983
Creator: Eaton, B. E.; Ely, James F.; Hanley, H. J. M.; McCarty, Robert D. & Rainwater, James C.
Item Type: Report
Partner: UNT Libraries Government Documents Department

Small Aperture Analysis of the Dual TEM Cell and an Investigation of Test Object Scattering in a Single TEM Cell

Description: Introduction: Small aperture theory is used to investigate the dual TEM cell. Analyzing coupling through an empty versus a loaded aperture leads to a model of dual TEM cell shielding effectiveness measurements. Small obstacle scattering yields results for both the field perturbation and the change in a cell's transmission line characteristics due to the presence of a test object in a TEM cell. In each case, theoretical values are compared to experimental data.
Date: 1984
Creator: Wilson, Perry F. & Ma, Mark T.
Item Type: Report
Partner: UNT Libraries Government Documents Department

Reference Flat Pulse Generator

Description: Introduction: A reference step-like pulse generator is described which has been developed at NBS. This generator can be used for accurately characterizing the step response of various kinds of trap ient recording equipment (oscilloscopes, waveform recorders, transient digitizers, etc.). Basic design principles are given as well as complete circuit diagrams and descriptions. An analysis of the output stage of the generator is presented together with the circuit models for developing a time-domain computer simulation program using extended- SCEPTRE. Preliminary specifications indicate that the NBS Reference Flat Pulse Generator provides a negative-going reference transition duration (90 to 10 percent) of 600 ps, *20 percent with baseline perturbations of less than *2 percent for less than 5 ns.
Date: October 1983
Creator: Andrews, J. R.; Bell, B. A. & Baldwin, E. E.
Item Type: Report
Partner: UNT Libraries Government Documents Department

Optical Time-Domain Reflectometer Performance and Calibration Studies

Description: from Introduction: The measurement accuracy of the optical time-domain reflectometer (OTDR) is restricted in some applications by a limited operational dynamic range and by a lack of standardized test procedures. In an effort to better understand these restrictions, we have measured the range of linearity of some avalanche photodiodes used as backscatter detectors. Also, the effect of input launch conditions is examined and a possible standardized OTDR test procedure is proposed. Using these suggestions, we have made comparisons between attenuation values determined by cutback and backscatter methods and found that good agreement is possible. Finally, some methods are described for checking the response. linearity of OTDR systems.
Date: June 1983
Creator: Danielson, B. L.
Item Type: Report
Partner: UNT Libraries Government Documents Department

Electrical Properties of Materials and Their Measurement at Low Temperatures

Description: Abstract: A review is given of the electrical resistance of materials at cryogenic temperatures. Measurement techniques, the data base, and uses of the data are presented. The emphasis is on metals and alloys of technological importance; a toxic which covers a large range of materials. Similarly, the treatment of theory and of measurement techniques is primarily for the user interested in the more practical aspects of the subject. In every instance, however, references are given which allow the reader to pursue the subject at any level.
Date: March 1982
Creator: Fickett, F. R.
Item Type: Report
Partner: UNT Libraries Government Documents Department

Input Impedance of a Probe Antenna Exciting a TEM Cell

Description: Abstract: The input impedance of a probe antenna exciting a transverse electromagnetic (TEM) transmission line cell is formulated by a variational approach. The formulation also utilizes the results from a previous work on the field distribution inside a TEM cell excited by a vertical electrical Hertzian dipole. The final result of imoedance is shown to consist of two distinct terms, which are respectively contributed by the ordinary rectangular waveguide and the gap perturbation. Numerical results for both the real and imaginary parts of the impedance are given. The resistive part is found to be proportional to the square of the probe length, and the reactive part largely capacitive.
Date: April 1982
Creator: Wilson, Perry F.; Chang, David C. & Ma, Mark T.
Item Type: Report
Partner: UNT Libraries Government Documents Department

Measurement of Optical Fiber Bandwidth in the Frequency Domain

Description: Abstract: The design, evaluation, and performance of a system for determining the magnitude of the transfer function (hence, the bandwidth) of a multimode optical fiber are presented. The system operates to about 1450 MHz using a tracking generator/spectrum analyzer combination for narrowband detection. It is constructed, almost entirely, from commercially available components. The system is less complex and easier to use than an equivalent time domain system and the measurement precision is comparable. Background information on time and frequency domain specifications, fiber bandwidth limitations, and alternate frequency domain techniques is also presented.
Date: September 1981
Creator: Day, G. W.
Item Type: Report
Partner: UNT Libraries Government Documents Department

Electromagnetic-Acoustic-Transducer/Synthetic-Aperture System for Thick-Weld Inspection

Description: Abstract: This report describes a system based on electromagnetic-acoustic transducers (EMATs) as an approach to automated nondestructive evaluation of thick weldments (>25 mm). Good signal-to-noise ratios, often a problem with EMATs, were possibTe through careful design of the transducers and associated electronic circuits and the use of signal averaging. At 454 kHz, the transducers produce shear-horizontal waves of approximately 7-mm wavelength in steel. The long wavelength permits determination of through-thickness flaw depth from the amplitudes of scattered ultrasonic waves. A minicomputer controlled transducer positioning and acquired the digitized ultrasonic waveforms for synthetic aperture processing. The synthetic aperture technique further improved signal quality and yielded flaw localization through the weld thickness. Measurements on artificial flaws demonstrated a detectability threshold of 0.5 mm (through thickness) and sizing ability up to 2.5 mm, in agreement with theoretical predictions. Details include the design of the transducers and electronics, as well as the mechanical positioner, signal processing algorithms, and complete computer program listing.
Date: 1984
Creator: Fortunko, C. M.; Schramm, R. E.; Moulder, J. C. & McColskey, J. D.
Item Type: Report
Partner: UNT Libraries Government Documents Department

Theory of Near-Field Phased Arrays for Electromagnetic Susceptibility Testing

Description: from Introduction: The feasibility of using a near-field array for electromagnetic susceptibility testing is studied. The basic objective is to control the element weightings such that a plane wave is generated within the test volume. The basic theory is developed for arbitrary array geometries, and numerical results are obtained for finite planar arrays. A general near-field array synthesis technique is developed, and the technique minimizes the mean square error in the test volume while constraining the array excitations. The constraint prevents large excitations and is useful in minimizing the fields outside the test volume. The basic idea looks promising, but some practical considerations, such as bandwidth and angular scanning limitations, require further theoretical and experimental investigation.
Date: February 1984
Creator: Hill, D. A.
Item Type: Report
Partner: UNT Libraries Government Documents Department

Design and Error Analysis for the WR10 Thermal Noise Standard

Description: from Introduction: This note describes the design and error analysis of a WR10 thermal noise power standard. The standard is designed to operate at the boiling point of liquid nitrogen with a noise temperature accurate to 1 K.
Date: December 1983
Creator: Daywitt, William C.
Item Type: Report
Partner: UNT Libraries Government Documents Department

The Characteristics of Iris-Fed Millimeterwave Rectangular Microstrip Patch Antennas

Description: from Introduction: The fabrication of various iris-fed millimeterwave rectangular microstrip patch antennas is described. A model is proposed to describe the iris-fed antenna. Irises ranging in size from 15 percent of the area of the patch to the fully open waveguide are used to couple energy into the antenna. Resonance of the antenna is observed to be insensitive to the size of the iris for irises up to 115 percent of the size of the patch. A study is also made of th? relationship of coupling to the antenna as a function of position of the iris with respect to the transverse plane of the waveguide, the iris always being centered with respect to the patch. In general, the antenna has a VSWR in the waveguide feed on the order of 5:1 at resonance, except for the fully open waveguide which gives rise to a VSWR of 2.9:1 at resonance. Far-field antenna power patterns are observed to be quite broad with H-plane beamwidths on the order of 1300. Maximum antenna gain is seen to be 4.5 dBi with 3 dBi typical. An initial study is made of the microstrip patch antenna fed from a longitudinal waveguide wall. Results indicate that this feed structure is likely to prove valuable for microstrip patch antennas with coupling at least as good as for the transverse-fed patch added to the possibility of feeding of multiple patches from a single waveguide.
Date: October 1983
Creator: Greenlee, D. H.; Kanda, Motohisa & Chang, David C.
Item Type: Report
Partner: UNT Libraries Government Documents Department

Possible Test Sites in Granitic Rocks in the United States

Description: Introduction: This report describes areas of granitic rocks suitable for underground nuclear tests within Federally-controlled land in the continental limits of the United States. This information was requested of the U. S. Geological Survey by the Albuquerque Operations Office of the U. S. Atomic Energy Commission, and was compiled during March 1959 by D. C. Alvord, W. J. Carr, P. M. Hanshaw, S. P. Kanizay, C. S. Robinson, R. W. Schnabel, J. A. Sharps, and C. T. Wrucke.
Date: July 1959
Creator: Alvord, Donald C.; Carr, Wilfred James; Hanshaw, Penelope M.; Kanizay, Stephen P.; Robinson, Charles Sherwood; Schnabel, Robert W. et al.
Item Type: Report
Partner: UNT Libraries Government Documents Department

Geology of the Marble Exploration Hole 4, Nevada Test Site, Nye County, Nevada

Description: from Introduction: This report summarizes the information obtained during preparation of the lithologic log of the core and presents results of chemical analyses of marble samples collected from surface near the drill hole. The report was prepared by the U.S. Geological Survey on behalf of the Albuquerque Operations Office, U.S. Atomic Energy Commission.
Date: October 1959
Creator: McKeown, F. A. & Wilmarth, V. R.
Item Type: Report
Partner: UNT Libraries Government Documents Department

Mineralogical Classification of Uranium-Vanadium Deposits of the Colorado Plateau

Description: Abstract: The uranium deposits of the Colorado Plateau contain suites of minerals that are the result of different stages of oxidation of deposits with different elemental composition. A classification based on composition and stage of oxidation is presented.
Date: January 1957
Creator: Botinelly, Theodore & Weeks, Alice D.
Item Type: Report
Partner: UNT Libraries Government Documents Department