bluuebunny/crossref_metadata_2025 huggingface dataset:
Tolerance Coefficients for R-C Networks
Authors: Belove Charles
Published: April 2005

A method is presented for the calculation of the departure of actual network behavior from design characteristics attributable to the use of nonideal components. The method yields a set of tolerance coefficients relating percentage changes in the positions of the zeros and poles of the network function to percentage changes in the network components. Once this information is available, changes in gain or phase are easily determined.
The Darlington Problem
Authors: Weinberg Louis
Published: April 2005

Any RLC transfer function with an even or odd numerator is realized as the transfer voltage ratio of a Darlington network, where such a network is defined as one containing lossless elements plus only one resistance. The single resistance appears within the network, and the termination is thus lossless. An unbalanced network that contains no mutual inductance is achieved by the procedure. The method makes use of Norton's theorem, zero shifting, and the paralleling of ladder networks. The number of ladders and elements required in the realization is kept small by a technique demonstrated in the paper.
The Output Signal-to-Noise Ratio of a Power-Law Device
Authors: Blachman Nelson M.
Published: April 2005

An nth law device is fed by a sinusoidal signal and narrow band random noise whose spectrum lies close to the signal frequency. Its output spectrum is different from zero only in the vicinity of harmonics of this frequency. The ratio R′ of output signal power to output noise power in the vicinity of the mth harmonic is computed in terms of the input signal-to-noise power ratio R. In general, R′(R) involves a couple of hypergeometric functions, but for small R we have R′≅Γ2[(m+n)/2+1]Rm/(m!)2Γ(n+1) for m≠0, R′≅Γ2(12n+1)/[Γ(n+1)−Γ2(12n+1)] for m=0. For large R we have R′≅2R/(m2+n2).
Nonequilibrium Thermodynamics
Authors: Hall Newman A.
Published: April 2005

The foundations and implications of the concepts essential to the thermodynamic analysis of nonequilibrium systems are investigated. Following a review of the background developments in irreversible thermodynamics the concept of thermostatic isolation is introduced. This provides a conceptual device whereby a thermostatic state may be established for any nonequilibrium system and a means of justifying extended use of basic relations of classical thermodynamics or thermostatics.

The conventional development of the form of entropy production is outlined. This in general is the sum of extrinsic entropy production and intrinsic entropy production. The former occurs as the sum of products of generalized diffusion effects and property gradients and is the result of interactions with discrete adjacent systems. The latter occurs as the sum of products of generalized affinities and generalized reaction rates and is the result of interaction between geometrically coincident overlapping systems. Between the diffusion effect and gradients of extrinsic entropy production generally occur linear relations with phenomenological coefficients subject to the Onsager reciprocal relations. The intrinsic entropy production occurs as a relaxation phenomenon developed from the first-order relaxation between the affinity and the displacement of the reaction from equilibrium.

The relation of the ultimate limits of applicability of thermodynamics to the uncertainty in establishing thermostatic state under conditions of microscopic fluctuations is discussed.
Starting Currents in the Backward-Wave Oscillator
Authors: Walker L. R.
Published: April 2005

The starting current of a simple model of the backward-wave oscillator described by Kompfner and Williams has been calculated. The effect of space charge is included. The starting current I0 may be written in the form I0=4V0Z0[a0(4QC)2πN]3,where V0 is the beam voltage, Z0 is the impedance of the circuit, N is the length of the oscillator in wave-lengths measured on the circuit and a0(4QC) is a dimensionless quantity which has been evaluated as a function of the space-charge parameter 4QC.
Potential Analog Network Synthesis for Arbitrary Loss Functions
Authors: Kuh Ernest Shiu-jen
Published: April 2005

A general method is developed for designing networks with arbitrary loss functions based on the potential analogy. An appropriate potential problem is formed on the basis of the given loss function by introducing continuous charge distribution on the complex frequency plane. After the potential problem is solved, the technique of quantization of charge is used to find the natural modes of the network function.
Matrix Solution of Equations of the Mathieu-Hill Type
Authors: Pipes Louis A.
Published: April 2005

This paper presents a method for the solution of a class of linear, second-order differential equations with periodic coefficients of the Mathieu-Hill type. The method is based on a procedure involving powers of matrices and is adequate for the study of a large class of physical problems. The stability of the solution is considered and the general method is illustrated by its application to typical special cases.
Helix Impedance Measurements Using an Electron Beam
Authors: Watkins D. A. , Siegman A. E.
Published: April 2005

Impedance measurements made on a tape helix with an electron beam are described. Curves showing the measured impedances of the fundamental and first backward space-harmonic components of the mode commonly used in traveling-wave tubes are presented for values of ka (circumference to free-space wave-length ratio) ranging from 0.15 to 0.6. The impedance of the fundamental is found to be less than that calculated from the sheath model by a factor ranging from 0.8 to 0.3. Phase velocities of other modes and components were observed for ka from 0.1 to 1.1; these agree with an analysis by Sensiper which predicts that certain values of the phase constant are not allowed for a single wire helix. A relationship for the impedance of one space-harmonic component in terms of the impedance of its fundamental is presented in approximate agreement with the experimental data. In addition to providing impedance data over a wide frequency range, the helix tester performed as a continuously voltage tunable backward-wave oscillator from 1500 to 4300 mc at a beam current of 1 ma.
A New Method for Continuous Viscosity Measurement. General Theory of the Ultra-Viscoson
Authors: Roth Wilfred , Rich Stanley R.
Published: April 2005

A new continuous ultrasonic viscometer employing a pulsed resonant exponentially damped magnetostrictive strip is described and treated theoretically. Properties of viscoelastic materials affecting the propagation of transverse elastic waves are derived and are related to the response of the viscometer. Typical applications of the use of the ultrasonic viscometer are presented.
Beta-Ray Spectrometer Line Shapes with Tilted Sources
Authors: Kruse H. W. , Mellor G. P. , Fowler C. M.
Published: April 2005

Experimental line shapes arising from tilted beta-ray spectrometer sources are compared with analytically derived line shapes. Although the increased scattering in the source at higher tilting angles considerably alters the experimental line shape, the sharp leading edges predicted for the larger angles are largely retained. This is true for electron energies at least as low as 400 kev, even for quite dense sources (5 mg/cm2). An application of the increased resolution resulting from this feature is given.
Determination of Reflection Coefficients and Insertion Loss of a Wave-Guide Junction
Authors: Deschamps Georges A.
Published: April 2005

Reflection and transmission coefficients are important parameters of a wave-guide junction. It is shown that these parameters in phase as well as in magnitude may be read directly from a graph. A short-circuit is moved in one of two wave guides that are connected by the junction, and the corresponding reflection coefficient is measured in the other wave guide as in a standard method. The positions of the short-circuit, however, are taken equally spaced every ⅛th of a wavelength. When plotted in the complex plane, the corresponding reflection coefficients fall on a circle and the chords joining opposite points intersect at a point that is simply related to the desired parameters.

When very accurate measurements are desired, 8 or even 16 short-circuit positions spaced at116th or132th wavelength can be used. The quality of the chord intersection then gives a control of the experiment by showing systematic or random errors. When the intersection is not perfect, because of random errors, a method of averaging is described that reduces these errors.
A Set of Principles to Interconnect the Solutions of Physical Systems
Authors: Kron Gabriel
Published: April 2005

A set of principles and a systematic procedure are presented to establish the exact solutions of very large and complicated physical systems, without solving a large number of simultaneous equations and without finding the inverse of large matrices. The procedure consists of tearing the system apart into several smaller component systems. After establishing and solving the equations of the component systems, the component solutions themselves are interconnected to obtain outright, by a set of transformations, the exact solution of the original system. The only work remaining is the elimination or solution of the comparatively few superfluous constraints appearing at the points of interconnection.

The component and resultant solutions may be either exact or approximate and may represent either linear or, with certain precautions, nonlinear physical systems. The component solutions may be expressed in numerical form or in terms of matrices having as their elements real or complex numbers, functions of time, or differential or other operators, etc. Boundary value, characteristic value, and time-varying problems of partial differential equations, as well as problems in ordinary differential equations and algebraic equations may be solved in this manner.

The method shown may be extended and generalized so that one can tear apart and afterward reconstruct the solution of extremely large or highly intricate physical systems, often without calculating any inverse matrices at all and always without carrying along unduly large matrices. This extension and generalization of the method is analogous to building skyscrapers by erecting first a steel framework and only afterward filling the gaps between the girders as needed. Those versed in the science of tensorial analysis of interrelated physical systems on the one hand and of large electrical networks on the other, should thereby be able to solve, with the aid of already available digital computers, highly complex physical systems possessing tens of thousands and, in special cases, even hundreds of thousands of variables. The accuracy of machine calculations, of coding and even the correctness of the analytical procedure itself may be simultaneously checked by physical tests at various stages of the computation. The saving in computing time is considerable even in smaller problems; by tearing a physical system into n parts, the usual machine calculations are reduced, in matrix inversion for instance, to a fraction of about 2/n2.

The present paper develops in detail the solution of a simple boundary value problem of Poisson's equation. A numerical example of interconnecting the solutions of large electric-power transmission systems appears in reference 3. Many simpler numerical examples are worked out in reference 1.
Measurement of Elastic Constants at Low Temperatures by Means of Ultrasonic Waves–Data for Silicon and Germanium Single Crystals, and for Fused Silica
Authors: McSkimin H. J.
Published: April 2005

Ultrasonic waves (shear or longitudinal) in the 10–30 mc range are transmitted down a fused silica rod, through a polystyrene or silicone one-quarter wavelength seal, and into the solid specimen. Measurement of reflections within the specimen yields values for velocities of propagation and elastic constants.

Data obtained over a temperature range of 78° to 300°K for silicon and germanium single crystals, and 1.6° to 300°K for fused silica are listed. For the latter, a high loss is noted, with an indicated maximum near 30°K.
The Identification of Individual Hygroscopic Particles in the Atmosphere by a Phase-Transition Method
Authors: Twomey S.
Published: April 2005

It is shown that in many cases the measurement of the relative humidity at which a hygroscopic particle becomes liquid can be used to establish the chemical composition of the particle. An apparatus is described which produces a stream of air of constant temperature and variable humidity. Using this apparatus the phase-transition point was determined for particles collected on spider webs. These particles were sampled in the Sydney area on the ground and from an aircraft, and it is shown that the measured values of relative humidity for the solid-liquid phase transition agreed with the hypothesis that the hygroscopic particles were composed of sea salt. Direct microscopic observation was used to follow the behavior of the particles; the technique was capable of dealing with particles down to 10−12g.
The Summation of Series Involving Roots of Transcendental Equations and Related Applications
Authors: Speigel M. R.
Published: April 2005

The summation of series involving the roots of certain transcendental equations having real roots is achieved by elementary considerations. The method is illustrated by several examples representative of those which may arise in applications. In addition to summing series, the method can be used to obtain the least positive root of the transcendental equation to any desired accuracy with but little computation.
Metallic Grating Replicas as Internal Standards for Calibrating Electron Microscopes
Authors: Rouze S. R. , Watson John H. L.
Published: April 2005

It was shown earlier that plastic grating-replicas mounted upon eighth-inch specimen screens were practical internal standards and that they could be accurately calibrated independently by spectroscopic means. Metallic replicas of diffraction gratings have been made by a direct-stripped method. These can still be direct-stripped easily and without damage to the original grating, and the optical quality of these pre-shadowed all-metal replicas is better than that of the plastic replicas. Because of their superior optical properties, the spacing can be determined spectroscopically more conveniently and with greater accuracy. In addition, the metal-gratings are more stable than the plastic ones. The electron microscopy of the metallic replicas and the accuracy and constancy of their magnification measurement is discussed.
The Negentropy Principle of Information
Authors: Brillouin L.
Published: April 2005

The statistical definition of information is compared with Boltzmann's formula for entropy. The immediate result is that information I corresponds to a negative term in the total entropy S of a system. S=S0−I. A generalized second principle states that S must always increase. If an experiment yields an increase ΔI of the information concerning a physical system, it must be paid for by a larger increase ΔS0 in the entropy of the system and its surrounding laboratory. The efficiency ε of the experiment is defined as ε = ΔI/ΔS0≤1. Moreover, there is a lower limit k ln2 (k, Boltzmann's constant) for the ΔS0 required in an observation. Some specific examples are discussed: length or distance measurements, time measurements, observations under a microscope. In all cases it is found that higher accuracy always means lower efficiency. The information ΔI increases as the logarithm of the accuracy, while ΔS0 goes up faster than the accuracy itself. Exceptional circumstances arise when extremely small distances (of the order of nuclear dimensions) have to be measured, in which case the efficiency drops to exceedingly low values. This stupendous increase in the cost of observation is a new factor that should probably be included in the quantum theory.
First Probability Densities for Receivers with Square Law Detectors
Authors: Emerson R. C.
Published: April 2005

The method of Kac and Siegert for finding the output probabi ity density characteristic function for receivers with square law envelope detections is discussed, and a parallel development is given for the square law rectifier. Procedures are then outlined for determining the probability density functions directly, i.e., without solving the eigenvalue problem or inverting the characteristic function. The method depends on expanding the density function in an orthonormal series, the coefficients of which are expressed in terms of cumulants, which in turn are obtained from the system kernel by straightforward quadratures.

As an example to illustrate the procedure, a receiver with Gaussian IF and Gaussian audio-frequency pass characteristics is treated in detail, and the output probability density functions are found for various sinusoidal input signal strengths and IF vs audio band-width ratios.
Epicentral Displacement Caused by Elastic Waves in an Infinite Slab
Authors: Mencher Alan G.
Published: April 2005

The displacement is determined at the epicenter of a homogeneous isotropic infinitely long elastic slab containing a point source of pressure waves. The source is centrally located between the slab surfaces and is taken to have a step function time dependence.

The formal solution for the Laplace transform of the displacement is obtained as an infinite integral. The integration and the inversion are simultaneously accomplished by an infinite series expansion of the integrand and transformation of variables for each term of the expansion. The resultant integrated series consists of terms having the mathematical form of reflected waves which diverge individually but combine to give a finite resultant.

In view of the fact that the expansion of the integrand is not valid at the upper limit of integration, a justification of the method and of the results is given.
Thickness-Shear and Flexural Vibrations of Contoured Crystal Plates
Authors: Mindlin R. D. , Forray M.
Published: April 2005

An approximate method is devised for calculating frequencies of thickness-shear and flexural vibrations of crystal plates of varying thickness. Applications are made to plates having the shape of a double wedge and to plates with beveled edges.
Space Charge Waves in Inhomogeneous Electron Beams
Authors: Kent Gordon
Published: April 2005

A magnetically confined sheet electron beam filling the space between two plane parallel electrodes is discussed. It is assumed that the average electron space charge is not neutralized by positive ions so that the potential at the center is depressed, and the beam is inhomogeneous in velocity and charge density. The objective of this theoretical treatment is to determine whether or not exponentially growing space charge waves can be supported by such a beam.

For small inhomogeneity and continuous behavior of all quantities as functions of the inhomogeneity, it is shown that growing waves are not possible. This conclusion is supported by discussion of the analogous adjacent beam problem and the analogous velocity distributed filamentary beam. Although the adjacent beams can support growing waves, it is argued that the analogy is not valid because the adjacent beams cannot be obtained by a continuous perturbation of a single homogeneous beam. The analogy of the velocity distributed beam does not suffer from this deficiency. In this case it is shown that growing space charge waves cannot exist unless the distribution function has more than one relative maximum.
On a Property of a Family of Equiangular Spirals and its Application to Some Problems of Wave Propagation
Authors: Landecker K.
Published: April 2005

It is shown that all the normals drawn from any point in the plane to the members of a family of equiangular spirals may be simply located geometrically. The locus of all the end points of the normals is a circle. It is also shown that the standing wave pattern in a uniformly attenuating medium may in simple cases (as with an attenuating transmission line) be represented by a vector diagram using a symmetrical pair of spirals. Then the foregoing theorem makes it possible to determine the voltage and current maxima and minima by constructing the locus circle referred to. This is illustrated by several examples. Finally it is pointed out that the locus circle may also be projected into the ``Smith Chart.''
Thermal Diffusivity of Metals at High Temperatures
Authors: Sidles P. H. , Danielson G. C.
Published: April 2005

A modified Ångström method for measuring thermal diffusivity and hence thermal conductivity of metals has been developed. Like previously reported dynamic methods, this method uses a heat source, whose temperature varies sinusoidally with time, located at one end of an effectively infinite rod. Unlike these methods, only one period of the heat pulse is required to eliminate the unknown coefficient determining the heat lost by radiation since both velocity and amplitude decrement of the heat pulse are measured. In addition to providing greater reliability at high temperatures by using only one period, the new method is faster in taking data and simpler in computation. The thermoelectric potentials from two thermojunctions are amplified and plotted on a Brown electronic recorder in order to obtain a permanent record of all necessary data for computing the thermal diffusivity. Results for copper, nickel, and thorium over the temperature range 0–500°C are given.
Some Problems in the Diffusion of Minority Carriers in a Semiconductor
Authors: Visvanathan S. , Battey J. F.
Published: April 2005

The exact solutions to the problems of the diffusion of minority carriers involved in the measurement of surface-recombination velocity in a semiconductor with a sample geometry bounded by two infinite planes are presented. The reduction of the exact solutions to simple forms used in the analysis of experimental data is shown.
Measurement of Orientation in Polystyrene Monofilaments by Means of Double Refraction
Authors: Andrews R. D.
Published: April 2005

The molecular orientation in polystyrene monofilaments can be determined by measuring the optical double refraction, or birefringence, which the orientation produces. When the oriented filaments are observed with monochromatic light under a polarizing microscope, a pattern of interference fringes is seen which can be analyzed. The general theory of this interference pattern is discussed, including consideration of the molecular basis of optical birefringence in polystyrene. Reversals of fringe order in the interference pattern can occur, but this complication can be handled by suitable methods. A number of experimental techniques useful in these studies are described. It is found that the birefringence is greater near the outside surface of the filaments than in the center, and this can be understood in terms of the rate of cooling during the orientation process.
Effect of Uniform Displacement on the Stress Distribution of a Wood Plate
Authors: Walters Kenneth C. , Smith C. Bassel
Published: April 2005

The principle of virtual work was employed to determine the stress distribution in a wood plate subjected to a load distribution such as to effect a uniform displacement in the y direction.

The displacement u along x=±a developed an unexpected contour. The average value of u appears to occur near the ends. This cautions against the common practice of placing the instruments for measuring Poisson's ratio near the middle. In the case of isotropic material the unexpected contours still prevail but are barely perceptible.

The work was carried out for a fourth approximation (not presented) with sufficient accuracy to assure that the same contour was developing. These unexpected results were first observed in the laboratory of the U. S. Forest Products Laboratory, Madison, Wisconsin—an experience which prompted this theoretical confirmation.
Method of Averages and Its Comparison with the Method of Least Squares
Authors: Morduchow Morris
Published: April 2005

It is shown, under fairly general conditions, that the standard deviation of the residuals of the straight line fitting a set of points with uniformly spaced abscissas by the method of averages is at most 2/3 times as great as the standard deviation of the least-squares line. Theorems of significance in the practical use of the method of averages are proven in the course of the analysis.
Theory of Strong Electromagnetic Waves in Massive Iron
Authors: MacLean William
Published: April 2005

A rigorous solution of Maxwell's equations is carried through for the case of a rectangular magnetization curve. Formulas for the depth of penetration and the wave impedance are derived yielding a theoretical power input formula which relates to the popular quasi-theoretical formula of Rosenberg by just the factor 4/π.
The Effect of a Transverse Electric Field on Carrier Diffusion in the Base Region of a Transistor
Authors: Kerr J. S. S. , Schaffner J. S. , Suran J. J.
Published: April 2005

A solution for the density of minority carriers is obtained for a semiconductor device having a two-dimensional rectangular geometry and a transverse field. The solution is developed for a variety of boundary conditions and the current-gain factor α of the corresponding semiconductor devices is obtained from this solution.
Method for Determining the Viscoelastic Properties of Dilute Polymer Solutions at Audio-Frequencies
Authors: Sittel Karl , Rouse Prince E. , Bailey Emerson D.
Published: April 2005

A sensitive instrument for the measurement of the viscoelastic properties of dilute polymer solutions is described. It makes use of torsion pendulums with resonant frequencies in the range between 200 cps and 2300 cps. The test liquid is contained in a hollow oscillating disk. The shearing stress which is exerted at the liquid-metal interface alters the frequency and rate of decay of the free oscillations of the pendulum. By means of an optical system, the oscillations of the pendulum are caused to modulate the light striking the cathode of a phototube. The frequency and the rate of decay of the resulting alternating voltage are measured electronically.

The operation of the instrument and the factors affecting the precision of measurement are analyzed.
Influence of Deuteron Bombardment and Strain Hardening on Notch Sensitivity of Mild Steel
Authors: Meyer Robert A.
Published: April 2005

Schnadt-type impact specimens of SAE 1019 steel were irradiated with 18.6-Mev deuterons for the purpose of studying the influence of radiation on the brittle property as measured by the change in transition temperature. The effect was compared with that of two, five, and ten percent strain hardening. Microhardness studies were made to determine the extent and location of the radiation effect. An integrated flux of 29.6 microampere-hr per cm2 shifted the transition temperature from −1°C to 18°C. The embrittling action was not a linear function of dose. Hardness was increased from 180 to 380 Knoop numbers. It was found to depend on the depth of penetration as well as the integrated flux. While radiation caused an effect similar to strain hardening, the nature of this effect was different. Annealing studies showed recovery of the irradiated material occurred between 260°C and 480°C. An interstitial vacancy diffusion process was indicated. Activation energies increased as recovery progressed. Recovery of the five percent strain hardened material occurred between 315°C and 371°C and would appear to be relaxation of internal stresses by the movement of dislocations.
Effect of Velocity Distribution on Traveling-Wave Tube Gain
Authors: Watkins D. A. , Rynn N.
Published: April 2005

The density-function method is applied to the one-dimensional model of the traveling-wave tube to determine the effect of velocity distribution on traveling-wave tube performance. For narrow velocity spreads, a term is introduced into the root equation for the incremental propagation constants which is like the space charge term 4QC and directly added thereto. This term is proportional to the ratio of the variance of the distribution to the square of the gain parameter C. For a typical tube, thermal velocities are found to reduce the gain by less than one part in 104. In a tube employing confined magnetic focusing, and employing a high perveance beam, the velocity spread resulting from space charge lowers the gain by about 1 percent.
Electrical Noise Pulses from Polarized Dielectrics
Authors: Baumann N. P. , Wiseman G. G.
Published: April 2005

Electrical noise pulses have been observed at elevated temperatures in polarized dielectrics (electrets) made of carnauba wax and of a vinyl acetate polymer. Pulse rate versus time was observed for electrets heated at a uniform rate and the results differ from those previously reported by others. Experiments devised to determine the origin of the pulses indicate that they are associated with the decay of volume polarization rather than with real surface charge. The total charge associated with the pulses from carnauba wax electrets is at least 5 percent of the maximum electret charge.
Kinetics of Piles with Reflectors
Authors: Rumsey V. H.
Published: April 2005

An integral equation for the time-dependent reaction is derived on the basis of the two-group model of neutron multiplication. When the effective multiplication constant is given, the solution reduces to a determination of the mean time T between consecutive generations, which is largely controlled by the circulation of neutrons in the reflector. If the steady distribution is known, T can be calculated from a simple formula.

To illustrate the orders of magnitude which are involved, T was calculated for a small pile surrounded by an infinite reflector. A value of T=450 microseconds was obtained assuming a mean lifetime in the core of 50 microseconds and a mean lifetime in the reflector of 14 000 microseconds.
Radioactive and Photoelectric p-n Junction Power Sources
Authors: Pfann W. G. , Van Roosbroeck W.
Published: April 2005

An electrical power source can be made by exposing a p-n junction to radioactivity or light, so that the junction field separates electron-hole pairs produced by the radiation. Expressions for maximum power, optimum load resistance, and efficiency are derived from an equivalent circuit and rectification theory. Power and efficiency increase with source current Ig of separated charges and zero-bias junction resistance. Ig increases with energy and intensity of radiation, but is limited by self-absorption in the radioactive isotopes. Estimates of attainable power and efficiency for silicon cells are 3·10−3 watt cm−2 and 15 percent for solar radiation, averaged, allowing for night, weather, and varying angle of incidence; and 3·10−4 watt cm−2 and 8 percent, for beta radiation from Sr90–Y90 of activity 32 Curie/g. However, lattice defects produced by Sr90–Y90 beta radiation impair cell performance by increasing electron-hole recombination. A theoretical estimate of threshold energy for radiation damage in silicon is about 0.3 Mev, about half the experimental value reported for germanium. Avoiding radiation damage by annealing, by absorbers, and by use of less energetic isotopes is discussed. The Y90 beta spectrum is given; it is used in estimating damage rates in germanium, which are high, and efficiencies obtainable with absorbers, which are low. Theory and experiment are compared for Sr90–Y90 cells of silicon and of germanium.
Relation between Stress-Relaxation Studies and Dynamic Properties of Polyisobutylene
Authors: Catsiff E. , Tobolsky A. V.
Published: April 2005

Experimental results on stress-relaxation modulus Er(t) and complex dynamic modulus E′(ω)+iE″(ω) of polyisobutylene are now available in the literature. To cover the entire time scale, the effect of changing the temperature of measurement is assumed to be equivalent to a linear change of the time scale. According to the general theory of linear viscoelastic behavior, the functions Er, E′, and E″ can each be computed from any one of them. This is qualitatively correct. The data on E′ in the transition region can be represented by the Gauss Error Integral form of equation used by Bischoff, Catsiff, and Tobolsky for Er of several polymers. The ``wedge-box'' distribution function proposed by Tobolsky is also compared with the experimental data and shows a reasonably good agreement with experimental results over the entire time scale.
Fast Time Analysis of Intermittent Point-to-Plane Corona in Air I. The Positive Point Burst Pulse Corona
Authors: Amin M. R.
Published: April 2005

Techniques for fast oscilloscopic analysis of intermittent point-to-plane coronas in air are described. Such analysis shows the positive point burst pulse corona to consist of an initial pulse followed by secondary pulses at varying time intervals. The duration of both pulses is less than 10−7 second, the initial pulses having from 1 to 2×107 ions and the secondaries from 1 to 5×106 ions depending on the voltage. Time intervals between pulses range from the clearing time of ions across the gap (milliseconds) to random intervals as short as 2 microseconds for secondary pulses well above threshold. Thus, in analogy to Geiger counter terminology dead times run from 2 microseconds up, and clearing times are in the order of milliseconds corresponding to local clearing of space charge near the point for secondaries, and removal of massive space charge from the low field region of the gap. A complete sequence of events from threshold to steady corona is analyzed, and indicates the predominance of self-counting through negative ion formation in air.
Parallel-Connected Magnetic Amplifiers
Authors: Chow S. H.
Published: April 2005

A complete analysis of parallel-connected magnetic amplifiers, based on a single-valued B-H relationship, is given. Three different types of loads: resistive, inductive, and capacitive are considered. Transient response is studied. Analysis of feedback amplifiers clearly indicates the presence of the ``jump'' phenomenon.
Current Noise in Thermistor Bolometer Flakes
Authors: Brophy James J.
Published: April 2005

The characteristics of the additional electrical noise generated by iron oxide thermistor bolometer flakes due to direct current passing through the units is investigated. It is found that the noise is similar to the current noise observed in other semiconductors. The current noise power density is observed to depend inversely upon frequency, to be approximately proportional to the direct current, and to be independent of temperature. It is indicated that the major source of the noise is at the electrodes which make electrical contact to the semiconductor. Electrodes produced by evaporated gold applied through a potential difference are found to yield relatively low noise flakes.
The Effect of Organic Vapor on the Secondary Emission of Phosphors
Authors: Dowling P. H. , Sewell J. R.
Published: April 2005

Experiments are described to show that, when a phosphor surface contaminated with organic vapor is bombarded with electrons, the secondary emission ratio is rapidly reduced. If the bombarding voltage is sufficiently high, this will result in a progressive decrease in potential of the phosphor surface and a corresponding decrease in apparent fluroescent efficiency. The relation between this effect and true ``phosphor burn'' is discussed as well as its possible connection with the phenomenon of ``cross burn'' encountered in the cathode-ray tube industry.
The Analysis of Quantitative Pole-Figure Data
Authors: Dunn C. G.
Published: April 2005

An analysis of isolated concentrations of poles in a pole-figure plot has been made in terms of a normal bivariate frequency distribution. A definition of pole density is given, and absolute units for measuring pole density are introduced. Simple procedures for determining the standard deviation of the pole-density distribution and for calculating the fraction of crystals in one preferred orientation in a texture consisting of several preferred orientations are given. A method of constructing a quantitative pole figure from a number of single Laue patterns and crystal sizes in coarse-grained material also is given.
The Plastic Deformation of Ammonium Dihydrogen Phosphate
Authors: Smith Paul L. , Salkovitz Edward I.
Published: April 2005

Plastic deformation was produced at about 100°C in single crystals of ADP which is normally considered to be brittle. The following four specimen orientations were studied by loading as a simple beam at temperatures from 90° to 115°C: (a) loaded along [110] axis normal to the (001) face (this orientation being the one of practical importance for all piezoelectric applications); (b) loaded along [100] axis normal to (001) face; (c) loaded along [010] axis normal to (100) face; (d) loaded along [001] axis normal to (100) face. Specimen (a) deformed more readily than the others. X-ray studies were made before and after deformation. Back reflection Laue patterns revealed no difference before and after deformation (i.e., no asterism was detected). A modification of the Berg-Barrett grazing angle technique proved very satisfactory and revealed that structural fragmentation had occurred in these crystals.
An Approximate Method of Evaluating Integral Transforms
Authors: Zemanian Armen H.
Published: April 2005

A new approximate means of evaluating integral transforms is developed. The process, which is very simple and quite general, has been applied to the Fourier, Laplace, Mellin, and Hankel transforms. The method may also be successful as a numerical means of evaluating an integral which has a highly oscillatory term in its integrand.
The Period and Amplitude of the Van Der Pol Limit Cycle
Authors: Fisher Edward
Published: April 2005

The amplitude and period of the limit cycle of the Van Der Pol equation, ÿ+y=vẏ(1−y2), are found for all values of v by joining graphically the results of solutions about v=0 and v=∞.
Response of a Pulsed Geiger Tube
Authors: Rosenstock Herbert B.
Published: April 2005

For the purpose of extending the usefulness of a Geiger counter to higher radiation intensities, it has been suggested that the voltage applied to its electrodes be a periodically repeated pulse rather than the usual dc. If the duration of the pulse is of the order of the spread time of the discharge in the tube, the output current vs radiation intensity relation will differ from the usual linear one, largely because the resulting current surge may not reach its maximum before the end of the applied pulse. This relation will therefore depend, among other factors, on the not fully understood mechanism by which the discharge spreads. Using probability considerations, we here calculate this relation as a function of the response of the tube under ordinary operation. If the discharge spreads rapidly (e.g., exponentially) initially, an approximate general relationship not involving the detailed spread mechanism may be established. The response to be expected in two types of tubes is discussed in detail, using models for the spread mechanism which are mathematically simplified though probably physically adequate.
Methods of Processing Silver-Magnesium Secondary Emitters for Electron Tubes
Authors: Rappaport Paul
Published: April 2005

In order to prepare a good secondary electron emitting surface from a silver-magnesium alloy, it was found that baking in dry oxygen would not form the desired surface as originally believed, whereas baking in the presence of water vapor did yield a good secondary emitter. Subsequent experiments showed that, because of the rapid diffusion of oxygen through heated silver, the magnesium in the alloy was oxidized in situ without diffusing to the surface to form the required magnesium oxide layer. With water vapor as an oxidizing medium, the diffusion rate of magnesium through the silver greatly exceeded that of the water vapor, and a satisfactory surface layer was formed. A new technique was then devised in which an original water-vapor process formed the desired surface, followed by an oxygen process to oxidize the remanent magnesium throughout the volume of the alloy. With the new technique, good secondary emitters are possible which will withstand severe overheating without the evaporation of magnesium found with earlier techniques.
RLC Canonic Forms
Authors: Reza F. M.
Published: April 2005

Foster's reactance theorem synthesizes the class of lossless networks in a so-called canonic form. This idea is here generalized in order to show that there is a distinct class of RLC networks possessing a canonic form. It will be shown that when an RLC driving-point impedance or admittance possesses a canonic form, its poles and zeros must alternate on each and every ``separate part'' of an algebraic curve (c) of a special nature located in the left half of the frequency plane s=σ+jω, belonging to one of the following two families: a0+ ∑ 1nak(σ+αk)(σ+αk)2+ω2=0;  a0   ∑ 1nak(σ2+ω2+αkσ)(σ+αk)2+ω2=0. A corollary of this theorem, in the case (c) is a straight line or circle, symmetrically placed with respect to the real axis, unifies the three known cases of LC networks, RL-RC networks, and networks with slight dissipation.

Analysis and synthesis of RLC networks possessing a canonic form is introduced in the light of a more general approach to the problem based on the class consideration. The problem of the driving-point impedances which contain mutual coupling in their Brune configuration has been clarified by outlining their generating functions and their network structure. (The latter part is omitted here and shall be presented in another article.)
Arcing at Electrical Contacts on Closure. Part IV. Activation of Contacts by Organic Vapor
Authors: Germer L. H.
Published: April 2005

The activation of electrical contacts by decomposition products from organic vapors depends upon an adequate surface layer of adsorbed molecules. In earlier work minimum vapor pressures were given for activation by a number of organic compounds. From new experiments reported here the time available for adsorption between successive arcs is equally important, so that the minimum vapor pressure for activation to occur is inversely proportional to the time available for adsorption, or directly proportional to the rate of operation. The effective contact area and the energy are important also and, although quantitative data have not been obtained, it is reasonable to guess that these variables are connected by a relation not far from p/n=KE/A, where n is the minimum rate for activation to occur for the pressure p on the effective contact area A with the available energy E. Quantitative experiments have been made only upon the activation of palladium contacts by vapor of the organic compound known as fluorene, and only the proportionality between p and n has been established.
Cathode Effects in the Dielectric Breakdown of Liquids
Authors: Bragg J. K. , Sharbaugh A. H. , Crowe R. W.
Published: April 2005

The apparent (measured) electric strength of a liquid dielectric depends on the nature of the cathode used. The field emission of electrons from the metallic cathode is assumed to be responsible for this effect; it may provide space charge which distorts the electric field in the dielectric. The nature of the cathode determines the range of electric fields over which the emission becomes appreciable.

In this paper we discuss in detail the emission of charge and the formation of space charge. Because of theoretical and experimental uncertainties connected with supposedly uniform metallic surfaces, an electrode consisting of an electrolyte solution is also considered. Although the experimental results demonstrate that ions are emitted from such cathodes under the influence of strong electric fields, the role in providing space charge is similar to that of metal electrodes which emit electrons.

For the former electrode, the considerations regarding space-charge formation predict a definite dependence of apparent electric strength on electrolyte concentration and provide a way of testing the basis of the theory. Certain experiments reported here confirm the predictions of the theory.
Heat Transfer Measurements at Sodium—Stainless Steel Interface
Authors: Moyer James W. , Riemen William A.
Published: April 2005

Experiments to measure the heat-transfer coefficient at a sodium type-347 stainless steel interface are described. The temperature range is 100–500°C. It is concluded that wetting does not play a significant role in the heat transfer.
Focusing of an Electron Beam by Periodic Fields
Authors: Clogston A. M. , Heffner H.
Published: April 2005

The problem of focusing long electron beams by means of magnetic or electric fields which vary periodically along the beam is considered. Four specific cases are discussed: periodic fields of the axially symmetric and quadrupole type with either electric or magnetic fields employed. The equations of motion are written and solutions obtained which show beam trajectories corresponding to essentially parallel flow. Under certain specified conditions only small ripples are present. Actual trajectories as plotted by the analog computer are shown and charts and equations are presented to aid in the design of practical periodic focusing systems.
Resistivity Striations in Germanium Crystals
Authors: Camp Paul R.
Published: April 2005

Germanium metal, both single crystalline and polycrystalline, is frequently found to contain sharp fluctuations in impurity concentration. These are superimposed on the gradual variations expected as the result of ordinary segregation processes.

A rather simple technique for detecting fluctuations of this kind has been developed. It is more sensitive than resistivity scanning and does not involve the use of radioactive tracers. This technique has been applied to a number of samples. The origin, value, and elimination of these fluctuations are discussed briefly.
A Graphical Method of Evaluating Trigonometric Functions Used in Crystal Structure Analysis. Parts I and II
Authors: Grenville-Wells H. J.
Published: April 2005

A graphical method is described for evaluating structure factors of the form F(hk0)= ∑ 0nfr(hk0) cossin2π(hxr+kyr)and electron density expressions of the form ρ(X,Y)=Σ Σ F(hk0) cossin2π(hX+kY). The method depends upon the fact that if, in a [001] projection of a unit cell the normal to the planes (hk0) is graduated with the appropriate sine or cosine function giving the phases of points along the normal, then a circle with its center at (½x,½y), passing through the origin, will cut the normal to F(hk0) at the value of 2π(hx+ky)cossin. Part I contains the basic principles and a standard chart, and Part II cites examples of the use of the method and the accuracy to be expected in structure factor calculations, and of its application to least-squares refinements.
Estimating Differential Scattering Cross Sections in Gases
Authors: Ahrens Tino
Published: April 2005

A simple method of estimating differential angular scattering cross sections in an infinite medium is presented. It assumes that single scattering theory approximates the radiation flux at a detector which is separated from the source by much less than a mean free path.
The Backscattering of the Co60 Gamma Rays from Infinite Media
Authors: Hayward Evans , Hubbell John H.
Published: April 2005

The radiation backscattered by semi-infinite slabs of wood and steel wool, when irradiated by the Co60 gamma rays, has been investigated by means of a sodium iodide scintillation spectrometer. The main contributions to the scattered radiation are produced in one or two Compton collisions. However, the radiation that has suffered so many collisions as to have an isotropic angular distribution has also been observed.