Latest content added for Digital Library Partner: UNT Libraries Government Documents Departmenthttps://digital.library.unt.edu/explore/partners/UNTGD/browse/?sort=added_d&fq=untl_collection:TRAIL&display=list2017-01-27T10:19:36-06:00UNT LibrariesThis is a custom feed for browsing Digital Library Partner: UNT Libraries Government Documents DepartmentNonlinear Least Squares Regression Using STARPAC: The Standards Time Series and Regression Package2017-01-27T10:19:36-06:00https://digital.library.unt.edu/ark:/67531/metadc502573/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc502573/"><img alt="Nonlinear Least Squares Regression Using STARPAC: The Standards Time Series and Regression Package" title="Nonlinear Least Squares Regression Using STARPAC: The Standards Time Series and Regression Package" src="https://digital.library.unt.edu/ark:/67531/metadc502573/small/"/></a></p><p>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.</p>Beam-Profile Measurement of Laser Pulses Using a Spatial Filter to Sample the Hermite Modes of a String of Pulses2017-01-27T10:19:36-06:00https://digital.library.unt.edu/ark:/67531/metadc502564/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc502564/"><img alt="Beam-Profile Measurement of Laser Pulses Using a Spatial Filter to Sample the Hermite Modes of a String of Pulses" title="Beam-Profile Measurement of Laser Pulses Using a Spatial Filter to Sample the Hermite Modes of a String of Pulses" src="https://digital.library.unt.edu/ark:/67531/metadc502564/small/"/></a></p><p>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.</p>A Method to Quantify the Radiation Characteristics of an Unknown Interference Source2017-01-27T10:19:36-06:00https://digital.library.unt.edu/ark:/67531/metadc502566/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc502566/"><img alt="A Method to Quantify the Radiation Characteristics of an Unknown Interference Source" title="A Method to Quantify the Radiation Characteristics of an Unknown Interference Source" src="https://digital.library.unt.edu/ark:/67531/metadc502566/small/"/></a></p><p>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.</p>A System for Measuring Energy and Peak Power of Low-Level 1.064 [mu]m Laser Pulses2017-01-27T10:19:36-06:00https://digital.library.unt.edu/ark:/67531/metadc502565/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc502565/"><img alt="A System for Measuring Energy and Peak Power of Low-Level 1.064 [mu]m Laser Pulses" title="A System for Measuring Energy and Peak Power of Low-Level 1.064 [mu]m Laser Pulses" src="https://digital.library.unt.edu/ark:/67531/metadc502565/small/"/></a></p><p>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.</p>An Equation of State for Fluid Ethylene2017-01-27T10:19:36-06:00https://digital.library.unt.edu/ark:/67531/metadc502557/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc502557/"><img alt="An Equation of State for Fluid Ethylene" title="An Equation of State for Fluid Ethylene" src="https://digital.library.unt.edu/ark:/67531/metadc502557/small/"/></a></p><p>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.</p>WR 10 Millimeter Wave Microcalorimeter2017-01-27T10:19:36-06:00https://digital.library.unt.edu/ark:/67531/metadc502556/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc502556/"><img alt="WR 10 Millimeter Wave Microcalorimeter" title="WR 10 Millimeter Wave Microcalorimeter" src="https://digital.library.unt.edu/ark:/67531/metadc502556/small/"/></a></p><p>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.</p>Geological Survey Investigations in the U12b.01 Tunnel, Nevada Test Site2017-01-27T10:19:36-06:00https://digital.library.unt.edu/ark:/67531/metadc502304/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc502304/"><img alt="Geological Survey Investigations in the U12b.01 Tunnel, Nevada Test Site" title="Geological Survey Investigations in the U12b.01 Tunnel, Nevada Test Site" src="https://digital.library.unt.edu/ark:/67531/metadc502304/small/"/></a></p><p>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.</p>Salt at Shallow Depths in the Coastal Plain of Texas and Louisiana2017-01-27T10:19:36-06:00https://digital.library.unt.edu/ark:/67531/metadc502305/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc502305/"><img alt="Salt at Shallow Depths in the Coastal Plain of Texas and Louisiana" title="Salt at Shallow Depths in the Coastal Plain of Texas and Louisiana" src="https://digital.library.unt.edu/ark:/67531/metadc502305/small/"/></a></p><p>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.</p>Cryogenic Fluids Density Reference System: Provisional Accuracy Statement (1980)2017-01-27T10:19:36-06:00https://digital.library.unt.edu/ark:/67531/metadc502552/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc502552/"><img alt="Cryogenic Fluids Density Reference System: Provisional Accuracy Statement (1980)" title="Cryogenic Fluids Density Reference System: Provisional Accuracy Statement (1980)" src="https://digital.library.unt.edu/ark:/67531/metadc502552/small/"/></a></p><p>Abstract: The improved Density Reference System, the reference densimeter, and the method of determining sample density are described. The uncertainty of the density reference system is + 0.055%. The contribution from the estimated systema -ic error in density was + 0.022%. The estimated uncertainty caused by random error is three times the standard deviation of 0.011% and is based on sixty-three measurements of the densities of saturated liquid methane. The total density uncertainty is taken to be the sum of the systematic and random errors. This applies to the density range of 400 to 480 kg/m at pressures from 0.8 to 4 bar absolute and temperatures between 109 and 128 K. This accuracy statement is expected to apply over ranges of at least 400 to 1000 kg/m3 in density, 77 to 300 K in temperature, and 0.8 to 7 bar in pressure though the accuracy over these ranges has not been verified.</p>A Coaxial Noise Standard for the 1 GHz to 12.4 GHz Frequency Range2017-01-27T10:19:36-06:00https://digital.library.unt.edu/ark:/67531/metadc502579/<p><a href="https://digital.library.unt.edu/ark:/67531/metadc502579/"><img alt="A Coaxial Noise Standard for the 1 GHz to 12.4 GHz Frequency Range" title="A Coaxial Noise Standard for the 1 GHz to 12.4 GHz Frequency Range" src="https://digital.library.unt.edu/ark:/67531/metadc502579/small/"/></a></p><p>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.</p>