Technical Report Archive and Image Library (TRAIL) - 473 Matching Results

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Automatic Indexing: A State-of-the-Art Report

Description: Report presenting a state-of-the-art survey of automatic indexing systems and experiments. It was conducted by the Research Information Center and Advisory Service on Information Processing, Information Technology Division, Institute for Applied Technology, National Bureau of Standards. Consideration is first given to indexes compiled by or with the aid of machines, including citation indexes. Advantages, disadvantages, and possibilities for modification and improvement are discussed. Experiments in automatic assignment indexing are summarized. Related research efforts in such areas as automatic classification and categorization, computer use of thesauri, statistical association techniques, and linguistic data processing are described. A major question is that of evaluation, particularly in view of evidence of human inter-indexer inconsistency. It is concluded that indexes based on words extracted from text are practical for many purposes today.
Date: March 30, 1965
Creator: Stevens, Mary Elizabeth
Partner: UNT Libraries Government Documents Department

Atomic Energy Levels in Crystals

Description: Report discussing discrete energy levels observed within certain crystals which are due to perturbations of energy levels of the free ion by an electrostatic field arising from the crystal lattice. The analytic procedures for determining the field from the charge configuration are given, and the resulting fields are classified according to their symmetry. After a general survey of group-theoretical ideas, the applicable groups are analyzed in detail, and characters appropriate for both integral and half-integral angular momenta of the free ion are tabulated. Text includes tabulations, equations, and matrices using Wigner and Racah coefficients.
Date: February 24, 1961
Creator: Prather, John L.
Partner: UNT Libraries Government Documents Department

The Role of Standard Reference Materials in Measurement Systems

Description: Report is a guide to Standard Reference Materials (SRM's) and should be useful to all users of SRM's particularly those in countries developing national measurement systems. It is not intended to be an exhaustive description of the NBS-SRM program, but rather a review of the role SRM's play in the measurement system, how SRM's are certified, and what the certification means. To illustrate the use of SRM's, several selected industries are described in which SRM's have made significant contributions.
Date: January 1975
Creator: Cali, J. P.; Mears, T. W.; Michaelis, R. E.; Reed, W. P.; Seward, R. W.; Stanley, C., L. et al.
Partner: UNT Libraries Government Documents Department

Properties of Glasses in Some Ternary Systems Containing BaO and SiO2

Description: Report discussing the glass forming regions in six ternary oxide systems containing BaO, Si02, and a third oxide. The properties of the resulting glasses were measured and the results reported. The data on refractive indices, dispersions, and specific volumes were evaluated by computer methods in an attempt to identify "substructures" containing the cations present in the glasses.
Date: September 1973
Creator: Cleek, Given W. & Babcock, C. L.
Partner: UNT Libraries Government Documents Department

Oscillator Strengths and Transition Probabilities fro 3288 Lines of Fe I

Description: Report of a homogeneous set of intensity-related data calculated for 3288 spectral lines of Fe I in the region from 2100 to 9900 angstroms. The quantities tabulated in the present monograph include log (g__), log (gf), gf,f,gA, and A. Since recent investigations do not support excitations corrections in the case of Fe I and certain other spectra, the present tabulation incorporates a removal of that normalization function. This recalculation affects the values for all lines whose upper energy levels lie above 46000 cm -1 and should significantly improve the internal consistency of the present data.
Date: March 1968
Creator: Corliss, C. H. & Tech, J. L
Partner: UNT Libraries Government Documents Department

Oxidation of Polycyclic, Aromatic, Hydrocarbons: A Review of the Literature

Description: Report discussing the literature on the oxidation of polycyclic, aromatic hydrocarbons. Information has been assembled on (1) the oxidants effective in the oxidation of such hydrocarbons, (2) the relative reactivity of the hydrocarbons, (3) the conditions under which oxidation proceeds, (4) the chemical mechanisms involved when such oxidations occur, and (5) the products formed.
Date: September 17, 1965
Creator: Tipson, R. Stuart
Partner: UNT Libraries Government Documents Department

Corrected Optical Pyrometer Readings

Description: Report presenting a table of corrected optical pyrometer readings which enables optical pyrometer users to convert observed temperature immediately to the true temperature, if the effective emissivity of the material being observed is known. The table gives observed temperatures from 1,000 to 3,000ºK in increments of 5 degrees, from 3,000 to 5,000ºK in increments of 10 degrees, from 5,000 to 10,000ºK in increments of 50 degrees, and from 10,000 to 39,900ºK in increments of 100 degrees. For these, true temperatures are tabulated for 49 emissivities ranging from 0.02 to 0.98 in increments of 0.02.
Date: April 21, 1961
Creator: Poland, D. E.; Green, J. W. & Margrave, J. L.
Partner: UNT Libraries Government Documents Department

The Dynamics of Fields of Higher Spin

Description: Report presenting a relativistic theory of motion that is free of many of the difficulties common in relativistic equations of motion. This Lagrangian theory describes fields and particles with arbitrary mass and charge and having any discrete spin, integer or half integer.
Date: August 1976
Creator: Hayward, Raymond W.
Partner: UNT Libraries Government Documents Department

Curves of Input Impedance Change Due to Ground for Dipole Antennas

Description: Report presenting graphs of the change in input impedance of electrically short dipole antennas in the presence of an isotropic and homogeneous ground which considers four types of antennas: horizontal and vertical, electric and magnetic dipoles. Curves of the change in both the input resistance and reactance are shown for a wide range of values of the frequency, antenna height above the ground, and electromagnetic ground constants.
Date: January 31, 1964
Creator: Vogler, L. E. & Noble, J. L.
Partner: UNT Libraries Government Documents Department

The Effect of Time Ordering on the Lyman α Profile

Description: Report investigating the effects of time-ordering over the complete line profile using a unified theory of spectral line broadening previously developed. The behavior of the time-ordered thermal average and un-time-ordered thermal average are compared. The Fourier transform of the thermal average is obtained analytically. Calculations for the line profile of the Lyman-[functional symbol alpha] line of hydrogen are presented and are representative in that the full thermal average is replaced by the thermal average with the electron velocity distribution approximated by f(v)=[functional symbol alpha] (v-vav) where vav is the thermal velocity for the plasma in question.
Date: June 1971
Creator: Godgrey, J. T.; Vidal, C. R.; Smith, E. W. & Cooper, J.
Partner: UNT Libraries Government Documents Department

Effects of Finite Lattice Heat Capacity on Spin Lattice Relaxation: Theory and Numerical Analysis

Description: Report discussing the transient magnetic behavior of a paramagnetic substance, after an initial disturbance, considered theoretically for a variety of situations in which the lattice temperature rises as a result of energy flow from the magnetic (electron spin) system. Next, the opposite extreme is considered - that in which the resonant and remaining modes are totally uncoupled. Finally, there is a consideration of the case of spins coupled only to the resonant phonons, which in turn are coupled to a constant temperature bath, whether this be the helium or the remaining modes.
Date: August 1, 1967
Creator: Peterson, Robert L.
Partner: UNT Libraries Government Documents Department

Influence of a Sector Ground Screen on the Field of a Vertical Antenna

Description: Report show the field of a short vertical antenna on a homogeneous ground is modified by the presence of a metallic screen. The screen is taken in the form of a circular disk and a concentric sector. The modification of the field is expressed in the form of surface integrals over the disk and the sector. Extensive numerical results for these basic integrals are given and a number of applications are illustrated.
Date: April 15, 1963
Creator: Wait, James R. & Walters, Lillie C.
Partner: UNT Libraries Government Documents Department

On the Statistical Theory of Electromagnetic Waves in a Fluctuating Medium (II): Mathematical Basis of the Analogies to Quantum Field Theory

Description: Report discussing the relationship between quantum field theory and the the statistical theory of waves. Basic equations exist in the latter theory which correspond closely to the fundamental equations of the former theory; i.e., to the commutation relations and the Heisenberg equation of motion. A probability density function of waves is introduced here which corresponds to the probability amplitude function in quantum mechanics. The theory of the statistical Green's functions and their relationships to the expectation values of the physical variables is also extensively developed. It is found that there exists a one-to-one correspondence between the formalism of Green's functions presented here and that used in field theory.
Date: December 7, 1964
Creator: Furutsu, K.
Partner: UNT Libraries Government Documents Department

Energy Dissipation by Fast Electrons

Description: Report discussing the energy dissipated by fast electrons at different distances from monoenergetic electron sources, for plane perpendicular and point isotropic sources including tabulations and a summary of the theoretical methods and data utilized, and a table of spatial moments.
Date: September 10, 1959
Creator: Spencer, L. V.
Partner: UNT Libraries Government Documents Department

Evaluating the Impact of Securities Regulation on Venture Capital Markets

Description: Report providing a detailed and analytical assessment of the economic techniques used by researchers to evaluate the efficiency of capital markets. The application of these techniques to that portion of the capital market which supplies venture funds to small, technology-based firms is emphasized. The primary elements of such analysis are the "efficient market ' hypothesis" and the "capital asset pricing model." The empirical analogue of the latter is commonly referred to as the market model."
Date: June 1980
Creator: Barth, James R.; Cordes, Joseph J. & Tassey, Gregory
Partner: UNT Libraries Government Documents Department

Theory and Methods of Optical Pyrometry

Description: Report reviewing the theoretical methods of optical pyrometry and the application of these methods at the National Bureau of Standards in realizing, maintaining and distributing the International Practical Temperature Scale above 1063 ºC is presented. In the theoretical presentation, the concepts of effective and mean effective wavelengths are introduced, and various equations relating these parameters to each other and other physical quantities are derived. The methods presentation discusses important features of precision visual optical pyrometers, experimental procedures, and results of primary and secondary calibrations of optical pyrometers.
Date: March 1, 1962
Creator: Kostkowski, H. J. & Lee, R. D.
Partner: UNT Libraries Government Documents Department

The Theory of the Optical Wedge Beam Splitter

Description: Report discussing optical wedge beam splitters and the basic theory for computing the ratio of the intensity of the incident beam to the intensity of any selected emerging beam and also for computing the direction of the emerging beam, assuming that the wedge angle, index of refraction, angle of incidence, and number of reflections are known.
Date: October 1974
Creator: Beers, Yardley
Partner: UNT Libraries Government Documents Department

Thermal Expansion of Technical Solids at Low Temperatures: A Compilation From the Literature

Description: Report giving tables of the linear contraction relative to 293 ºK, (L293ºLT)/L293, and the linear expansion coefficient, dL/L293dT, of thirty elements, forty-five alloys, twenty-two other inorganic substances and twenty plastics and elastomers in the temperature range, 0 to 300 ºK.
Date: May 19, 1961
Creator: Corruccini, Robert J. & Gniewek, John J.
Partner: UNT Libraries Government Documents Department

Thermocouple Reference Tables Based on the IPTS-68: Reference Tables in Degrees Fahrenheit for Thermoelements versus Platinum (Pt-67)

Description: Report presenting tables as a supplement to those given in NBS Monograph 125. Tables were calculated from the power series expansions presented in that Monograph. They are based upon the absolute electrical units and the International Practical Temperature Scale of 1968 (IPTS-68). Reference tables for several thermoelements versus platinum (Pt-67) are given with values of the thermoelectric voltage as a function of temperature in degrees Fahrenheit. Only tables for standard letter-designated thermoelements are included.
Date: March 1975
Creator: Powell, Robert L. & Burns, George W.
Partner: UNT Libraries Government Documents Department

The NBS Standard Hygrometer

Description: Report describing a gravimetric hygrometer that serves as the NBS standard instrument for the measurement of the moisture content of gases on an absolute basis in terms of mixing ratio (mass water vapor/ unit mass of dry gas). The National Bureau of Standards and other laboratory reference and working instruments are compared and calibrated with this instrument. The measuring operation involves the absorption of the water vapor from a water vapor-gas mixture by a solid desiccant and the determination of the mass of this water vapor by precision weighing; it also involves the determination of the volume of the associated gas of known density by counting the fillings of two calibrated stainless steel cylinders. The construction and operation of the instrument is described. Discussions of the tests and calibrations of component parts, and of the sources of errors also are included. There is also an analysis of the random and systematic errors effecting the overall accuracy in the determination of mixing ratio.
Date: May 1, 1964
Creator: Wexler, Arnold & Hyland, Richard W.
Partner: UNT Libraries Government Documents Department

Photonuclear Reactions

Description: Report discussing photonuclear reactions in the approximate energy range 10 to 30 MeV. Various sum rules are discussed and applied to experimental data. Several different theories are described and their predictions compared with experiment, and as often as possible open questions and discrepancies are pointed out.
Date: August 1970
Creator: Hayward, Evans
Partner: UNT Libraries Government Documents Department

Reference Tables for Low-Temperature Thermocouples

Description: Report discussing the completed experimental program of the low-temperature reference tables for the commonly used thermocouples. Details of the experimental system, instrumentation, data analysis, error analysis, and materials tested are given in order to allow the user to better evaluate and apply the results.
Date: June 1972
Creator: Sparks, Larry L.; Powell, Robert L. & Hall, William J.
Partner: UNT Libraries Government Documents Department

Reduction of Data for Piston Gage Pressure Measurements

Description: Report discussing pressure measurements made with piston gages that are affected by gravity, temperature, pressure, and several other variables. For accurate determinations of pressure the calculations must take these variables into account. A general equation is developed and simplified procedures for calculating pressure are illustrated.
Date: June 17, 1963
Creator: Cross, J. L.
Partner: UNT Libraries Government Documents Department

Refractive Indices and Densities of Aqueous Solutions of Invert Sugar

Description: Report of the refractive indices and densities of aqueous solutions of invert sugar at temperatures of 15, 20, 25, and 30º C, for concentrations up to about 82 percent of invert sugar (by weight). From the results, equations have been derived which relate the refractive index and percent of invert sugar (weight in air) at each temperature. Other equations relate the absolute density and percent of invert sugar (weight in vacuum) at each temperature. Five-decimal tables giving the refractive indices and densities of invert sugar solutions containing 1 to 85 percent of sugar are given for each percentage of invert sugar at the four temperatures.
Date: June 7, 1963
Creator: Snyder, Carl F. & Hattenburg, Albert T.
Partner: UNT Libraries Government Documents Department