bluuebunny/crossref_metadata_2025 huggingface dataset:
PPI Light Spot Brightness Probability Distributions
Authors: Sponsler George C. , Shader Fern L.
Published: April 2005

A mathematical study utilizing the statistics of noise theory is presented which derives light spot brightness probabilities for PPI target returns of various signal-to-noise ratios. An idealized model is employed which differs from similar previous ones by taking account of the cathode-ray tube's highlight brightness vs intensifier electrode voltage characteristic. For the 10KP7 cathode-ray tube this characteristic obeys an approximate 2.5 power law in typical operation. This law, together with a square law second detector, combine to form an over-all fifth power detector. The light spot brightness of the display is assumed to be formed by linear superposition of individual target returns resulting from the radar antenna scan. In the model, seven identical returns are so integrated.

Various mathematical methods of handling the problem are considered. The Edgeworth series approximation is found to give poor results compared with the Laguerre polynomial approximation. By the latter method the light brightness probabilities are found to be obtainable by interpolation from a table of the incomplete gamma function. Ancillary tables of statistical moments and selected values of the confluent hypergeometric function, 1F1(−5n/2; 1; −x), are included in the text.
Direct Cellular Evaluation of the Density of States in Phase Space and the Accurate Calculation of Fermi Levels
Authors: Gold Louis
Published: April 2005

A new procedure for rigorously deducing the energy distribution of states, formulated upon a direct summing of cells in k space, provides a sound basis for assessing the classical approximation so familiar in statistical mechanics. It is thus established that the latter approach underestimates the density of states to the extent that the conventional Fermi energy calculation for electrons in metals is a few percent too high.
Compression Wave Velocity Experiments with Copper
Authors: Savitt Jacob , Stresau R. H. , Starr L. E.
Published: April 2005

A method for obtaining experimental compression wave velocities in metals is described. Measurements of the compression wave velocity in copper were made and found to be in good agreement with theoretical predictions. It is suggested that the discrepancy between the velocity (4730 m/sec) reported herein and that reported by Rinehart and Pearson (3600 m/sec) is associated with the different geometries of the two sets of experiments.
Stationary Temperature Distribution in an Electrically Heated Conductor
Authors: Domenicali Charles A.
Published: April 2005

The thermodynamic theory of irreversible processes as developed by Onsager, de Groot, and Callen is used to derive in a straightforward way the partial differential equation for the stationary temperature distribution in an electrically heated, chemically inhomogeneous conductor. It is shown that the form of this differential equation given in 1900 by Diesselhorst (for homogeneous media) in terms of the electrical potential gradient ∇·κ∇T+στ∇T·∇φ+σ(∇φ)2=0, is incorrect. Diesselhorst's equation reads ∇φ in which κ is the thermal conductivity (for zero electrical current), T the temperature, σ the isothermal electrical conductivity, and τ the Thomson coefficient. The correct form of the equation, for the special case of a chemically homogeneous conductor, is ∇·κ∇T+(1/σ)J2−τJ·∇T=0, where J is the electrical current density. The correct form can be obtained from Diesselhorst's equation by substitution of the ``isothermal Ohm's law'' J=−σ∇φ, which, however, is not valid in a nonisothermal medium. The apparent difficulty is resolved by the method of Onsager-de Groot-Callen, and it is shown that the correct differential equation expressed in terms of electrical potential is much more complicated than the form given by Diesselhorst.
Torsion of a Shaft with a Toroidal Cavity
Authors: Weiss G. , Payne L. E.
Published: April 2005

This paper gives the solution to the torsion problem for a near-cylindrical shaft of circular section having a toroidal cavity. Since the interpretation of the axially symmetric problem as a flow problem in 5 dimensions is well known, the first part of the paper is devoted to developing a method for handling the flow problem about an n dimensional ring-shaped body of general cross section. In the second part of the paper this method is applied to the case of an n dimensional torus ring. The case n=3 then yields the solution to the classical flow problem, and n=5 gives the solution to the torsion problem under consideration.
Scattering from Dielectric Coated Spheres in the Region of the First Resonance
Authors: Scharfman H.
Published: April 2005

Formulas for the backscattering and total scattering cross sections for dielectric coating spheres of arbitrary size were developed following the methods of Hansen and of Aden and Kerker. Calculations based on the resultant formulas were made in the region of the first resonance (outside dimension of the concentric spheres is approximately 0.4 wavelength). It was found that certain choices of coating thickness and dielectric constant can lead to increases in the scattering cross sections of more than 100 percent relative to a solid metal sphere of the same outside diameter. A number of calculated and measured curves are presented, and they show the variation of the backscattering and total scattering cross sections as functions of coating thickness, coating permittivity, and outside diameter of the coating. Where both calculations and measurements were made for the same conditions, the values agree to ±2 percent.
Spectral Response of a Quadratic Device to Non-Gaussian Noise
Authors: Magness T. A.
Published: April 2005

In order to compute the spectral response of a quadratic device to noise, a fourth-order moment P of the input noise is sufficient, P being a function of three independent time delays. The function P1 by which this fourth moment for a non-Gaussian noise differs from the corresponding moment for a Gaussian noise having the same spectrum is examined. The Fourier transform of this function is Q1, a function of three frequencies. Q1 is capable of an interpretation in terms of nonlinear correlations between noise components at different frequencies. A specialization of Q1 leads to E, a function of two frequencies which is a measure of the correlation between the squares of the envelopes associated with those frequencies.

Several networks involving quadratic nonlinear elements are examined to illustrate the theory. It is shown that while the function P makes it possible to compute the complete spectral response of the network, the function E (together with the spectrum of the input) is sufficient in order to find the spectral density at zero frequency. Finally, for three examples of non-Gaussian processes, the corresponding P1, Q1 and E functions are computed.
Conditions for Porosity Formation during Diffusion
Authors: Balluffi R. W. , Seigle L. L.
Published: April 2005

Formal relationships defining the regions of the diffusion zone where porosity tends to form during the Kirkendall effect are developed. The surfaces at which the intrinsic diffusional flux of each component reaches a maximum are also considered. The results are applicable to diffusion systems subject to the usual boundary conditions where the solution N1=N(x/√t) holds. The results are discussed in relation to presently available experimental findings.
Calibration of a Nickel-Molybdenum Thermocouple
Authors: Potter Richard D.
Published: April 2005

A report is made of a calibration of a nickel (A) versus molybdenum thermocouple up to 2242°F (50 mv).
Forming Point-Contact Silicon Transistors
Authors: Jacobs Harold , Brand Frank A. , Matthei Wesley , Ramsa Alexander P.
Published: April 2005

A new technique is reported in which silicon can be formed to provide transistor action. A suitable impurity is arced at the surface of the silicon causing the impurity to be diffused into a small region. Tests have been carried out using n-type and p-type silicon with various impurities. Initial results indicated voltage gains as high as 75 and power gains between 15 and 60. Other characteristics, such as variations in current multiplication with emitter current, were examined and the mechanism of alpha was compared with the theories developed by Sittner.
Ferrite Phase Shifters in Rectangular Wave Guide
Authors: Lax Benjamin , Button Kenneth J. , Roth Laura M.
Published: April 2005

The problem of the propagation of electromagnetic energy down an infinitely long rectangular wave guide partially filled by a ferrite slab is solved. The solution is expressed in the form of a transcendental equation involving the propagation constant. Calculations are carried out for a lossless ferrite, and the phase constant is evaluated as a function of the appropriate parameters, namely, the ferrite slab thickness, the lateral position of the slab in the guide, and the applied transverse static magnetic field intensity. The results are plotted in graphic form for values of the static magnetic field in the region of ferrite saturation both above and below ferromagnetic resonance. The electromagnetic field configurations within the wave guide are plotted in detail for values of the parameters of practical interest. Two versions of the nonreciprocal phase shifter are discussed. The first consists of a single slab placed asymmetrically in the wave guide, while the second consists of two symmetrically placed slabs with antiparallel static magnetic fields imposed. The nonreciprocal nature is summarized in terms of the differential phase shift β+-β− which is pertinent in applications of this phase shifter.
A Transient-Flow Method for Determination of Thermal Constants of Insulating Materials in Bulk Part I—Theory
Authors: Blackwell J. H.
Published: April 2005

This is the first of two papers concerning an improved transient-flow method for determining the thermal conductivity and diffusivity of insulating materials in bulk. The work was first suggested by the geophysical problem of determining the thermal constants of natural rock in situ. A cylindrical ``thermal probe,'' containing heat-source and thermometer, is inserted in the medium and constants deduced from a record of probe temperature versus elapsed time; this method has been used before but the work described here is an attempt to eliminate, or evaluate the effect of, physical idealizations inherent in previous applications. The first paper is concerned with development of a new approximate mathematical treatment, using methods of the operational calculus first suggested by S. Goldstein, in 1932. A subsequent paper will deal with the experimental results obtained with the new theory.
Ferrites for Microwave Circuits and Digital Computers
Authors: Albers-Schoenberg E.
Published: April 2005

Ferrites of the system MgO–MnO–Fe2O3 have been investigated, and two new classes of magnetic materials have been developed. One class of ferrite has low losses and shows the Faraday rotation effect at microwave frequencies, which makes it useful in new types of microwave components. A second class of ferrite has a rectangular hysteresis loop and inherent high resistivity which allows digital computer magnetic memories to be operated at much greater speeds than was possible with the familiar magnetic metal alloys. Both classes of ferrites are now commercially available.
The Synthesis of X-Ray Spectrometer Line Profiles with Application to Crystallite Size Measurements
Authors: Alexander Leroy
Published: April 2005

An improved convolutional method is used to synthesize theoretical line profiles generated by the joint action of seven instrumental weight functions characteristic of the x-ray spectrometer. These include in addition to the five geometrical factors described in a previous publication: (VI) a so-called misalignment function and (VII) a spectral impurity function. The method is applied to the new spectrometer design incorporating a narrow x-ray source, Soller slits, and an angular range 2θ=0 to 165° or higher. Good agreement between theoretical and experimental line profiles is achieved for quartz reflections at 2θ=24.0 and 90.7°. The improved treatment is used to define new curves for correcting experimental spectrometer line breadths for instrumental broadening effects. It is demonstrated that spectrometers of the new design are capable of measuring crystallite dimensions as large as 3000A.
Penetration of an Electromagnetic Wave into a Ferromagnetic Material
Authors: Papoulis A.
Published: April 2005

When a magnetic field is applied to the surface of a lamination of a metallic ferromagnetic core, it does not instantly penetrate into the interior because of the induced eddy currents. If the B-H curve of the core material is a straight line, the computation of the field within the material can be performed with known methods. For a general B-H curve the resulting equation for H is nonlinear, and only a numerical solution is possible. The purpose of this paper is to give an approximate solution for the case of a rectangular hysteresis loop material. The theoretical results that are developed are in close agreement with the experimental measurements described in this paper.
Ferromagnetic Spinels with Rectangular Hysteresis Loops
Authors: Hegyi I. J.
Published: April 2005

The ferromagnetic spinel MgO·3MnFe2O4, ``magnesium manganese ferrite'' is satisfactory for magnetic memory devices. Small rings of about 55-mil diameter which have proved practical for memory matrix use have a coercive force of about 3 oersteds and switch-over time of 0.3 microsecond, and a nearly rectangular hysteresis loop. Rings of about 0.5-cm diameter which were used to study composition variables showed a lower coercive force of 1.6 oersteds for the same composition and processing. Resistivities are in the order of 45×103 ohm cm.
Electron Diffraction Study of the Structures of Antimony Electrodeposited on Antimony Cleavage Face
Authors: Yang Ling
Published: April 2005

Thin layers of antimony of average thickness about one hundred angstroms, electrodeposited at 90°C and 2 ma/cm2 on the (111) cleavage face (referred to pseudo-cubic axes) of an antimony single crystal, yield abnormal electron diffraction patterns. Analysis of these patterns shows that the deposit crystals are arranged in three azimuthal equivalent orientations, with their (111̄) instead of the (111) lattice planes parallel to the (111) antimony substrate. This is confirmed by comparing the patterns obtained experimentally with those constructed from the Laue zones of reinforcement of the electron beam scattered from three nonparallel atom rows. This observation is discussed in connection with the various factors controlling the crystal orientation in electrodeposited metals.
The Analysis and Purification of Rare Gases by Means of Electric Discharges
Authors: Riesz R. , Dieke G. H.
Published: April 2005

Through the phenomenon of cataphoresis in gas discharges, impurities are carried toward the cathode and concentrated there. This can be used for the purification of rare gases, in particular, for the removal of traces of one rare gas from another rare gas. The technique is simple and completely automatic. The same technique can be used for the analysis of rare gases. The high concentration of the impurities near the cathode increases the sensitivity by a large factor. One part of neon in 200-million parts of helium has been detected without difficulties.
Design and Calibration of Stagnation Temperature Probes for Use at High Supersonic Speeds and Elevated Temperatures
Authors: Winkler Eva M.
Published: April 2005

A stagnation temperature probe with a single platinum-coated silica shield was built for use at high supersonic speeds and elevated temperatures. For large Reynolds numbers the temperature recovery factor of the probe reaches 0.998. It decreases with decreasing Reynolds number and increasing temperature. At temperatures up to 700° K the major thermometric losses of the probe are conduction losses. One single calibration curve is obtained for any one probe by relating the calibration data to the flow conditions inside the probe.
Symmetry as a Factor in Finite Difference Approximations
Authors: Fowler C. M.
Published: April 2005

The effect of symmetry of the solutions to the finite difference diffusion equation upon the stability criterion is discussed. A simple example is included to illustrate the discussion.
A Resonant Cavity Study of Semiconductors
Authors: Hsieh Hsi-Teh , Goldey James M. , Brown Sanborn C.
Published: April 2005

A solution of Maxwell's equations is obtained in a resonant cavity with a center post of arbitrary electrical properties. The solution gives the dielectric coefficient and the conductivity of the center post in terms of the natural frequency and Q of the cavity. The theory is of particular use in the study of semiconductors where perturbation theories are of little value. It is shown that a transition from a cylindrical mode to a coaxial mode occurs as the conductivity of the center post is varied. This transition occurs for a relatively small change in conductivity. The present results are compared with those of perturbation theory, and it is shown that the latter are valid over a greater range than the conditions imposed in their derivation indicate.
Diode Theory in the Light of Hole Injection
Authors: Swanson John A.
Published: April 2005

Classical diode theory, as applied to metal point contacts made to an n-type semiconductor, is adequate only for small forward voltages at which, under certain conditions, hole current may be negligible. The shape of the theoretically predicted diode characteristic is not affected by the hole injection process at low voltages, no matter what the composition of the current. However, for voltages in excess of a certain value, dependent only on the resistivity of the material (on the order of 0.1 volt for 5 ohm-centimeter germanium), the spreading resistance is comparable to the barrier resistance, and it is the hole injection process which accounts for continued rectification. The extent to which the spreading resistance is decreased by hole injection depends on the ratio, γ, of hole current to total current. The present paper includes a theory of the effect of this ratio on the diode characteristic at higher forward voltages. A method of measuring γ from V-I characteristics alone is indicated.
Boundary Disturbances in High-Explosive Shock Tubes
Authors: Shreffler R. G. , Christian R. H.
Published: April 2005

High-velocity disturbances are observed to propagate along the walls of a high-explosive operated shock tube in advance of the plane shock. Experiments are presented which determine the dependence of the geometry, energy, and velocity of the disturbance on such variables as the gas contained in the shock tube, the shock strength, and the roughness and composition of the supporting boundary. A model is constructed to explain the flow within the disturbance. Arguments are presented which show the disturbance to result from radiation originating in the luminous plane shock.
Use of Restricted Variational Principles for the Solution of Differential Equations
Authors: Rosen Philip
Published: April 2005

A technique is given by which nonlinear differential equations may be solved approximately, using variational principles for which certain restrictions are made. Ordinary first- and second-order equations are discussed in detail. The method is extended to encompass partial differential equations and applied to the Boltzmann transport equation.
Radiation Damage Effects on Order-Disorder in Nickel-Manganese Alloys
Authors: Aronin Lewis R.
Published: April 2005

Effects of fast neutron irradiation in a nuclear reactor on order-disorder in a series of nickel-manganese alloys ranging from 16.5 to 31.9 atomic percent manganese have been studied by resistivity and magnetic induction measurements. Attainment of an ``irradiated state'' differing from either cold work or thermal disordering is suggested by comparison of exposure results on initially cold work disordered and initially thermally disordered Ni3Mn. In a region from 16.5 to approximately 22 percent manganese, thermally disordered alloys are markedly affected by irradiation. These effects also appear to be superposed on the disordering produced by irradiation of initially ordered alloys.

From theoretical exponential dependence on period of irradiation, fast neutron disordering of Ni3Mn is determined by relating the Bragg and Williams order parameter quadratically with resistivity and linearly with magnetic induction. This leads to an estimate of 5000 for the ratio of the number of atomic replacements to primary collisions with neutrons of energy in excess of 0.5 Mev.
Estimation of Correlation Coefficients from Scatter Diagrams
Authors: Sugar George R.
Published: April 2005

Theoretical relations between statistical scatter diagrams of two random variables and their joint probability density functions are used to derive a simple method of estimating correlation coefficients. The cases considered are those of variables with Gaussian and Rayleigh distributions. Theoretical curves and experimental scatter diagrams are given for each case. Some factors which may influence the accuracy of the proposed method are discussed, and it is concluded that the errors in estimating correlation coefficient will be of the order ±0.1.
Fast Time Analysis of Intermittent Point-to-Plane Corona in Air. II. The Positive Pre-Onset Streamer Corona
Authors: Amin M. R.
Published: April 2005

Analysis has been made of pre-onset streamers in room air at 760 mm with fast oscilloscope using both photomultiplier and electrical registration. The shape of the photon pulse observed by W. N. English is confirmed, and is interpreted. Current and luminosity roughly parallel each other in the streamer. Tip velocities ranged from 6×107 cm/sec to 2×107 cm/sec being highest near the point. The luminosity is constant over the path except at the very beginning and at the end of the path suggesting that ionization is also constant. The net number of positive ions left behind per cm length of streamer in consequence of the electron flow into the point is constant, and has been measured to be about 8×109 ions per cm in general agreement with earlier work. Lateral deflection of the ends of streamer tracks by space charge left behind from previous streamers was directly observed.
Diffusion of Gold into Copper
Authors: Martin A. B. , Johnson R. D. , Asaro Frank
Published: April 2005

Radioactive tracer techniques have been utilized to measure the rate of diffusion of gold into polycrystal-line copper over the temperature range from 1000° to 375°C. These experiments have yielded the values Q=44 900±1300 cal/mole and D0=0.10±0.06 cm2/sec for the volume diffusion process in the temperature range from 1000°C to 750°C. Diffusion measurements at 550°C and 375°C indicated that the measured rates at these temperatures had been enhanced by grain-boundary diffusion. Considerable attention was directed toward the variation of the diffusion coefficient with (1) the purity of the copper, (2) the grain size of the copper, (3) the thickness of the plating, and (4) the time of anneal. Variations of these parameters showed no significant effect on the diffusion coefficient, with the exception of the time of anneal. The measured diffusion rate at 1000°C was observed to decrease with increasing time of anneal.
General Theory of Plane-Wave Scattering from Finite, Conducting Obstacles with Application to the Two-Antenna Problems
Authors: Storer J. E. , Sevick J.
Published: April 2005

In this paper the variational techniques of Levine and Schwinger are used to obtain an approximate solution for the free-space scattering by a number of finite, perfectly conducting obstacles in which the mutual interactions or coupling are taken into account. The far-zone scattered field is found in terms of the obstacle currents. Variational principles for the total and backscattering cross sections are included. The special case of two parallel wires of finite length is worked out, and the results agree well with experiment.
On a Nonlinear Diffusion Equation Applied to the Magnetization of Saturable Reactors
Authors: Chow Shou-Hsien
Published: April 2005

The penetration of the magnetic field intensity into the interior of an infinite slab of ferromagnetic material having a nonlinear B — H relationship is governed by a nonlinear diffusion equation. For finite thickness of the slab, the problem is solved by an approximate method. A rigorous solution of the same problem when the thickness of the slab approaches infinity is given to justify the approximate method used. In the paper, one term only is used to represent an infinite series in order to give a readily calculable result in ``switching time.'' The result is then compared with that of the graphical solution of the same problem.
Normal Reflection of Shock Waves from Moving Boundaries
Authors: Alpher Ralph A. , Rubin Robert J.
Published: April 2005

The problem of the reflection of a shock wave from a moving boundary is examined in an idealized one-dimensional treatment. We consider in detail the head-on collision of an incident step shock wave and a piston moving at constant velocity into a gas at rest. The calculation involves the head-on collision of two shock waves and the subsequent reflection of an altered transmitted wave from the piston. The reflected pressure is calculated for a range of incident shock strengths and piston speeds. For a stationary piston both the absolute and excess reflected pressures are at most eight times the absolute or excess pressure of the incident shock wave (with γ=7/5). With a moving piston, however, this limiting factor is greater than eight, but finite for finite piston speed and infinite incident shock strength, and is infinite for infinite piston speed and finite incident shock strength. This last result holds even in the limit of the incident wave being an acoustic pulse. The method of solution for shock-wave interaction with a piston receding at constant velocity is also indicated. Although the shock is strengthened on passing through the piston rarefaction wave, the reflected overpressure is less than that resulting from the same initial shock wave reflecting from a stationary piston.
Low-Temperature Internal Friction and Elasticity Effects in Vitreous Silica
Authors: Fine M. E. , Van Duyne H. , Kenney Nancy T.
Published: April 2005

Near 35°K the internal friction of vitreous silica reaches a peak value which increases with frequency. The temperature curves of the torsion and Young's moduli are concave upward with minima near 65°K and are independent of frequency. These effects are reversible with temperature. Their cause cannot be the usual type of relaxation process or anything involving diffusion or large amounts of shear.
Switching in Bistable Circuits
Authors: Mackay R. Stuart
Published: April 2005

Switching or triggering in certain nonlinear circuits having two stable states is studied in graphic detail. The minimum and maximum pulse requirements are discussed and some of the general ideas of bistability considered. A convenient technique for studying the response of circuits, apparently in slow motion, is described.
Germanium Diodes from Spherical Pellets
Authors: Dunlap W. C.
Published: April 2005

A method is described for constructing germanium high-voltage diodes, utilizing 15-mil germanium spheres instead of the usual flat wafer. The spheres are produced within a few minutes in quantities of several hundred thousand or more by blowing molten high-purity germanium from a graphite crucible. The spherical pellets can be annealed, ground, etched, and assembled into diodes by techniques easily adaptable to automatic mass production. The assembled diode uses a sphere-plane contact rather than the conventional whisker contact. Peak back-voltages in the range 50–100 volts are easily obtainable. Series-assembled units for higher voltages are easily made.
Motion of Small Particles in Skew Shape Suspended in a Viscous Liquid
Authors: Tchen Chan-Mou
Published: April 2005

The resistance experienced by a curved and elongated small particle is studied by the method of velocity perturbations. The fundamental equations determining the perturbations are derived from the equations of Oseen. The particle is curved in such a way that the axis of the particle is formed by an arc of circle. The opening angle may vary to exhibit various shapes from a straight ellipsoid to a closed ring. Results illustrate the circumstances under which manifests the cooperation between the different parts of the particle. Apart from this pure hydrodynamical interest, the problem has applications to long chain molecules in solution and to suspensions of swimming organisms. It demonstrates the effect of skew shape by taking for the chain molecule a model in the form of a variable-curved ellipsoid instead of a sphere or a cluster of spherical symmetry, as the coordination of the chain links, even in the case of free rotation, leads initially to configurations of variable skewness generally obscured under the averaging processes by current theories.
Magnetic Switching Circuits
Authors: Minnick Robert C.
Published: April 2005

Rectangular hysteresis-loop magnetic materials are widely used at present for the storage of digital information. The principles involved in static magnetic storage are generalized in this paper so that magnetic cores may be used for the purpose of switching. Magnetic circuits to produce the logical operations of ``and'' and ``or'' are described. The ``and'' and ``or'' circuits are combined into a class of circuits capable of producing any switching function of any number of input binary variables. All of the magnetic switching circuits described are devoid of rectifiers, vacuum tubes, transistors, and the like. Furthermore, these circuits are essentially independent of pulse amplitudes and durations.
The Growth of Vapor Bubbles in Superheated Liquids
Authors: Plesset M. S. , Zwick S. A.
Published: April 2005

The growth of a vapor bubble in a superheated liquid is controlled by three factors: the inertia of the liquid, the surface tension, and the vapor pressure. As the bubble grows, evaporation takes place at the bubble boundary, and the temperature and vapor pressure in the bubble are thereby decreased. The heat inflow requirement of evaporation, however, depends on the rate of bubble growth, so that the dynamic problem is linked with a heat diffusion problem. Since the heat diffusion problem has been solved, a quantitative formulation of the dynamic problem can be given. A solution for the radius of the vapor bubble as a function of time is obtained which is valid for sufficiently large radius. This asymptotic solution covers the range of physical interest since the radius at which it becomes valid is near the lower limit of experimental observation. It shows the strong effect of heat diffusion on the rate of bubble growth. Comparison of the predicted radius-time behavior is made with experimental observations in superheated water, and very good agreement is found.
Interpretation of Photoelastic Transmission Patterns for a Three-Dimensional Model
Authors: Drucker D. C. , Woodward W. B.
Published: April 2005

The work of O'Rourke and Saenz on the photoelastic determination of quenching stresses is re-examined and extended. A brief general discussion is given on the determination of shear stresses or stress differences in the interior of a photoelastic model from retardation patterns obtained by passing light through the entire model. A method is proposed for the cylindrical case, with no variation in stress along the axis, which is feasible at present, while the proposal for the general axi-symmetric problem is feasible in principle. The fundamental difficulty of the general three-dimensional model is brought out but no solution is advanced.
A Point Emitter-Junction Collector Transistor
Authors: Kingston Robert H.
Published: April 2005

A transistor structure utilizing a planar p-n junction as a collector, and a point contact as an emitter has been analyzed theoretically and experimentally. The theory indicates that for maximum frequency cutoff the plane containing the emitter point should be nearly parallel to the collector junction. Also it is found that the base resistance is a critical function of the spacing between the emitter point and the collector junction. Results for experimental models are discussed.
Propagation of Longitudinal Deformation Waves in a Prestressed Rod of Material Exhibiting a Strain-Rate Effect
Authors: Rubin Robert J.
Published: April 2005

We consider the longitudinal propagation of stresses above the yield stress in a material exhibiting a strain-rate effect. The system consists of a semi-infinite rod subjected to end impact. If the rod is prestressed above the yield point and if the impact stress is not too large, the equations of motion are linear. Integral representations of the solutions can be obtained by the method of Laplace transforms. It is shown in general that the strain-rate solutions approach asymptotically the solutions obtained by von Kármán and Taylor in a treatment which neglects the strain-rate effect.

The propagation of the unloading wave is considered for the case in which the initial wave is a shock wave. The condition which defines the regions in the x—t plane, where the loading and unloading equations apply, is given. It is shown that an unloading shock wave will be absorbed except for the case of a material which does not work-harden. In this case the complete solution of the unloading problem is obtained.
Plastic Deformation in Beams under Distributed Dynamic Loads
Authors: Seiler J. A. , Symonds P. S.
Published: April 2005

Plastic deformations in beams caused by symmetric dynamic loads distributed over finite lengths are considered in this paper. The analysis is based on the assumption of ``plastic-rigid'' behavior, so that the results should be valid when plastic deformations are sufficiently large. The final deformations for distributed loads are found not to differ much qualitatively from those to be expected for concentrated loads. However, the magnitude of the deformation decreases rapidly as the length of the loaded area increases from zero, for given load pulses. Thus the simplifying assumption of a mathematically concentrated load may cause a considerable overestimate of the final deformation.
Some Phenomena Associated with Supersonic Liquid Jets
Authors: Dunne Brian , Cassen Benedict
Published: April 2005

Supersonic liquid jets were produced in air by means of a spring-loaded injector. At high jet velocities another type of breakup seems to occur besides the classical Rayleigh surface tension breakup, and the sinuous aerodynamic breakup. Rotationally symmetric waves are formed, and appear to ``break'' analogous to wind-produced waves on a body of water. The rate of cavitation of jets in water was studied for several jet velocities above the speed of sound in air.
Friction of Clean Metals and Oxides with Special Reference to Titanium
Authors: Machlin E. S. , Yankee W. R.
Published: April 2005

The friction coefficients of freshly cut surfaces in inert atmosphere are compared with values on the same surfaces later exposed to air. The kind of metal or oxide comprising the friction couple was also varied. From experimental data it was concluded that: (1) Solid phase welding accounts for almost the entire magnitude of the static friction coefficient for metal-metal couples. (2) Fe-Ag does not solid phase weld, other insoluble couples examined do weld. (3) A measure of solid phase weldability appears to be the quotient of the work of adhesion and the shear strength of the weaker couple. (4) Titanium does not solid phase weld to crystalline oxides to any greater extent than copper. (5) Freshly cut titanium solid phase welds to other metals in frictional contact. The degree of welding is independent of the atmosphere (air, nitrogen, or argon) or the time (less than 24 hours) at room temperature in such atmospheres. This behavior is contrary to that experienced with iron or copper With the latter couples less than five minutes exposure of a freshly cut surface to air is sufficient to markedly reduce the degree of solid phase welding. (6) The seizability of titanium is probably due to the lack of resistance, of the contaminant film formed on it in air, to penetration or wear in frictional contact.
On the Band Width of Cavity Antennas
Authors: Cohen Marshall H.
Published: April 2005

The objective of this work is to determine the orders of magnitude of the band width available from a cavity antenna. Fcr simplicity of calculation a piece of shorted square wave guide of side a, opening into a half-space, is considered, and the resonance frequency and band width (1/Q) are calculated from transmission-line theory. The analysis depends on an equivalent aperture admittance which is defined for the lowest-order wave guide mode.

This type of antenna has a minimum Q which is equal to 0.424(a/λ)−3 when (a/λ)<0.35. The cavity depth required for the minimum Q is of the order of 0.4a. The required dielectric constant increases rapidly as a/λ decreases. The effect of dielectric loss is considered. Some experimental results which agree well with theory are presented.
Multiple Shock Reflection in Corners
Authors: Keller Joseph B.
Published: April 2005

When a shock is incident upon a corner from either the concave or convex side it is reflected by the walls forming the corner and diffracted at the edge. The mathematical problem corresponding to this phenomenon has not been solved analytically except in the following limiting two-dimensional cases: a weak (acoustic) shock incident on any corner (Keller and Blank) and a finite shock incident either normal or parallel to a nearly flat wall (Bargmann, Lighthill, Ting, and Ludloff). In this article it is pointed out that there are certain special cases of a finite shock entering a corner from the concave side in which no diffraction occurs. In these cases it is therefore possible to solve the entire problem by using the theory of regular reflection, which yields an explicit solution by algebraic means alone.
Measurement of the Effect of Chlorine Treatment on the Work Function of Titanium and Zirconium
Authors: Malamud Herbert , Krumbein Aaron D.
Published: April 2005

This paper describes work function measurements of titanium and zirconium carried out by the conventional photoelectric method. Two samples of each metal were investigated before and after treatment with chlorine. The changes in work function due to chlorine absorption were of the same order of magnitude as those reported for other halogens on other metals.
Delayed Yield and Strain Rate and Temperature Dependence of Yield Point in Iron
Authors: Yokobori Takeo
Published: April 2005

A unified explanation of delayed yield and of strain rate and temperature dependence of yield point in iron was attempted on the basis of the Cottrell locking theory, taking internal stress into account. The energy of a dislocation required to fit existing data is small by an order of magnitude compared with the value theoretically estimated by Mott and Nabarro. The distance, calculated from the value of internal stress, between dislocations assembled at a grain boundary is of a reasonable order of magnitude. It is suggested that the mechanism of yielding may change from Cottrell type to Mott-Nabarro or Frank-Read type when applied stress falls below some limiting value.
Information Theory and Knowledge
Authors: MacDonald D. K. C.
Published: April 2005

Distinction between data transmission from one person (or point) to another and the inception of new knowledge is analyzed in relation to information theory. The customary measure H = −∑ipi logpi applies essentially to the former case, and after discussing the requirements appropriate to a yardstick for new knowledge an elementary measure for this concept is tentatively proposed. The intuitive requirements, however, are not all mutually compatible and the present measure can only be regarded as provisional; in particular some ``memory'' characteristics appear mandatory for future development.
Errors in Power Spectra Due to Finite Sample
Authors: Spetner Lee M.
Published: April 2005

An estimate is made of the accuracy with which the ``spectrum'' of a finite sample of Gaussian noise approximates the spectrum of the original noise from which the sample was taken. The sample is considered to be spliced to form an endless loop, thereby making it a periodic function. The effect of this splice is also discussed.
Some New Magneto-Mechanical Torsion Experiments
Authors: Cochardt A. W.
Published: April 2005

The internal damping of ferromagnetic wires was measured as a function of either a superimposed static stress or an alternating magnetic field. Similar to a static magnetic field, a static stress affects the damping considerably. For example, the logarithmic decrement of a Fe-40 percent Co wire in torsional vibration is reduced by a factor of 33 when a heavy weight is suspended on the wire. The effect of an alternating magnetic field on the damping was studied by varying the frequency of the field. It is found that the damping reaches a strong minimum at a field frequency of the order of magnitude of 20 cycles/sec. Magnetic hysteresis loss measurements were made which explain this phenomenon in terms of magneto-mechanical hysteresis.
On the Nature of the Transcendental Curves Associated with the Relativistic Trajectories of Charged Particles
Authors: Gold Louis
Published: April 2005

A detailed examination of the relativistic trajectories in the intermediate high-energy range is made for charged particles in crossed magnetic and electric fields for generalized injection states with explicit solutions given in parametric form. The particle path relation is generally formulated, but explicit calculation is offered for the zero velocity injection only.
On the Conductivity of Oxide Cathode Coatings
Authors: Tomlinson T. B.
Published: April 2005

Experiments are described which supply evidence on the manner of electrical conduction through the oxide cathode coating. In the first experiment, I–V characteristics were obtained using special diodes with embedded probes. Contrary to the Loosjes-Vink theory, the characteristics for temperatures above 700°K are generally linear at high positive and negative potentials but curved at lower potentials. Other experiments would appear to confirm the presence of space change in the pores of the coating at temperatures above 700°K, and so support the Loosjes-Vink theory for higher-temperature conductivity. A modified conduction theory is put forward, and it is shown to fit in with all the known facts.
New Method of Measuring the Cathode Temperature of Indirectly Heated Vacuum Tubes
Authors: Ikehara Suketoshi
Published: April 2005

A new method of determining the cathode temperature of the diode, triode, and multigrid tube, using high harmonic component of initial current which flows to the anode when an ac voltage is applied to the anode, is presented. The principle and apparatus of this method are described, and the causes of error in measurement are discussed. The advantage of this new method is that the temperature may be read directly; the time for measuring is extremely short; the error due to the leakage current is reduced; and it has a high accuracy (within ±0.05 percent) and good reproducibility. Results on diode 6AL5, 6H6, triode 6J6, and pentode 6SH7 taken by this method, and results taken by other method, are compared.
Solution of the Field Problem of the Germanium Gyrator
Authors: Wick R. F.
Published: April 2005

A mathematical solution is obtained of a two-dimensional boundary-value problem involving flow of electricity in a solid when Hall effect is present, it being assumed that only one type of carrier is involved and that there is no surface recombination. The solution is used to calculate the efficiency of a Hall-effect ``gyrator,'' a four-terminal circuit element which violates the reciprocity law, as function of relative electrode size, shape of boundary, and magnetic field strength. It is also shown how corrections must be applied in measurements of Hall voltage and magnetoresistance in short samples.

Some of the results have been checked experimentally with fields up to 22 000 gauss. The calculations have been carried out for much higher fields as well and should prove useful in studies of materials such as indium antimonide which have higher mobilities than germanium.
Solar Thermoelectric Generators
Authors: Telkes Maria
Published: April 2005

The physical characteristics, thermoelectric power, resistivity, specific heat conductivity, and the temperature difference between hot and cold junctions determine the efficiency of thermocouple materials. These data have been determined for Chromel P-constantan, bismuth alloys, and the intermetallic compound ZnSb, containing small amounts of added metals.

The optimum characteristics of flat-plate type solar energy collectors have been evaluated in combination with thermocouples, designed for maximum energy conversion. Using flat-plate collectors with 2 glass panes, an efficiency of 0.63 percent was obtained with the ZnSb-type alloys in combination with a negative Bi-alloy. The commercially available ductile alloys Chromel P-constantan, produced ten times lower efficiency. Calculations indicate that the efficiency may be increased to 1.05 percent by using 4 panes of low-reflection characteristics.

With solar energy concentrating means (lenses), the efficiency was increased to 3.35 percent, using the above mentioned best alloy combination.

The maximum allowable cost of thermoelectric generators has been evaluated, by comparison with present methods of electric power generation.

Solar thermoelectric generators may find useful application in the tropics, as they do not contain moving parts and require very little attention. Further development is needed to determine their economical value.
Generalization of the Wiener-Khintchine Theorem to Nonstationary Processes
Authors: Lampard D. G.
Published: April 2005

The Wiener-Khintchine theorem which connects the autocorrelation function and the power spectrum of a stationary time series by means of a Fourier cosine transform is well known. It is the purpose of this paper to generalize the theorem to deal with nonstationary time series.
Modified Luneberg Lens
Authors: Gutman A. S.
Published: April 2005

Spherically symmetric optical instruments, and their desirability for microwaves, are discussed. Application of Hamiltonian optics in analyzing the rays in the Luneberg lens has led to formula of a new lens that has spherical symmetry and a focus near its center. A cylindrical version of this new lens has been designed for operation in the TE10 mode.
Steady-State Solution of the Two-Dimensional Diffusion Equation for Transistors
Authors: Schaffner J. S. , Suran J. J.
Published: April 2005

The diffusion equation is solved for transistors for (a) linear flow of minority carriers and (b) non-uniform flow of minority carriers due to a metal contact applied to the base region. The current transport ratio β is calculated for both of these cases as a function of frequency.

Frequency response characteristics of a transistor, as predicted by the one-dimensional diffusion equation, give excellent results for junction transistors having base length-to-base width ratios greater than ten and having negligible surface recombination rates. For transistors where these conditions are not applicable, the two-dimensional diffusion equation must be used in the calculation of β.
Secondary Emission from Nichrome V, CuBe, and AgMg Alloy Targets Due to Positive Ion Bombardment
Authors: Higatsberger Michael J. , Demorest H. L. , Nier Alfred O.
Published: April 2005

A mass spectrometer ion collector system has been devised for the investigation of secondary electron emission by impact of ions on surfaces. Results are reported for various ions incident on clean, baked (but not atomically clean) surfaces of AgMg, CuBe, and Nichrome V targets. For rare gas isotopic ions it is found that for a given energy ion the value of γ varies approximately inversely with the square root of the mass.