bluuebunny/crossref_metadata_2025 huggingface dataset:
The Properties of Carbon Contacts
Authors: Grisdale R. O.
Published: April 2005

Microphone carbon has been produced by deposition of pyrolytic carbon films over the surfaces of small spherules of silica. The properties of contacts between these spherules are shown to be dependent on the structure and geometry of the carbon surface as determined by electron diffraction and microscopic studies. The graphite-like crystallites in pyrolytic carbon surfaces are more or less preferentially oriented with their basal planes parallel to the surface, and the contact properties depend systematically on the degree of orientation. This is explained in terms of the anisotropy in properties of these crystallites which are closely approximated by those of single crystal graphite which were determined. The contact resistance and its temperature coefficient and the ``burning voltage'' for carbon contacts are explicable on this basis. However, the microphonic sensitivity of carbon contacts is independent of the surface structure and depends only on the surface geometry.
Characteristics of an Elliptical Electromagnetic Resonant Cavity Operating in the TE111 Mode
Authors: Higgins T. P. , Straiton A. W.
Published: April 2005

Equations and graphs are presented of the resonant wavelength and quality factor of elliptical resonant cavities operating in the TE111 mode. Both components of this mode are treated and distinctive characteristics of each are shown as a function of eccentricity of the cavity.
A Note on the Analysis of First-Order Glow Curves
Authors: Grossweiner Leonard I.
Published: April 2005

Simple equations are developed which permit the calculation of the trap depth and frequency factor of first-order glow curves from the temperatures of the peak and the half-height. The equation for the trap depth does not depend explicitly on the frequency factor or the heating rate and is accurate to 5 percent over a wide range. Application is made to theoretical glow curves and to an experimental glow curve obtained from the thermoluminescence of ice.
On the Propagation Constant in Gentle Circular Bends in Rectangular Wave Guides—Matrix Theory
Authors: De Hoop A. T.
Published: April 2005

The propagation constant γmn of the m,nth mode in a gentle circular bend in a rectangular wave guide is derived with the use of matrix theory.
``Brillouin Flow'' with Thermal Velocities
Authors: Pierce J. R. , Walker L. R.
Published: April 2005

A type of electron flow in a constant magnetic field is described. The beam of electrons is supposed to be everywhere in thermal equilibrium and the usual Brillouin flow is found when the equilibrium temperature tends to zero. Some considerations are put forward bearing on the choice of a suitable beam temperature in specific problems.
Traveling Wave Slot Antennas
Authors: Rumsey V. H.
Published: April 2005

Approximate formulas for the complex propagation constant and characteristic field configuration for dielectric-filled traveling wave slot antennas are obtained by a variational procedure. To set up the variational method, the generalized reciprocity theorem for traveling wave line sources is deduced; it differs considerably from the reciprocity theorem for point sources. A perturbation technique for solving the variational equations is given. Formulas are worked out for rectangular wave guides and good agreement with available measurements is obtained.
Graphical Analysis of Nonlinear Circuits Using Impedance Concepts
Authors: Thomsen John S.
Published: April 2005

Equivalent reactances of inductors and capacitors with moderate nonlinearity may be approximated by the usual linear expressions plus terms which depend on the square of the current. With the help of this approximation, the total impedance of an LRC circuit is obtained and plotted in the I-Z plane with frequency as a parameter. The current for any given frequency and voltage may be easily obtained from this plot by graphical means. This method gives an interpretation of the triple-valued frequency response curve in terms of circuit concepts.
Observation of Shock Formation and Growth
Authors: Laponsky Alfred B. , Emrich Raymond J.
Published: April 2005

Transient one-dimensional flows have been produced by accelerating a piston in a gas-filled tube. Accelerations of the order of 2.5×104 m/sec2 produced shocks within 5 m of the initial piston position. The piston was propelled pneumatically. Shocks formed at the head and in the interior of the compression waves. By optically detecting the piston and shock positions and recording the corresponding times on a rotating drum chronograph with microsecond accuracy, the properties of the compression wave and resulting shock were determined. The formation and growth of shocks were calculated from the compression wave measurements using the method of characteristics and the assumptions employed by Chandrasekhar and Friedrichs. The observed and calculated shock properties were in reasonably good numerical agreement. Consistent lagging of the observed behind the calculated shock positions (order of 0.05 m at 5 m from initial piston position) is attributed to the interaction of the flow with the tube walls.
Thermal Contraction of a Split Hollow Cylinder
Authors: Karush W. , Martin A. V.
Published: April 2005

Consider a long hollow cylinder which is radially split along its entire length. When such a cylinder is heated, its inner radius undergoes a change δa. The cylinder is called stable if δa≤0. An approximate solution for δa is derived and is used to determine conditions for stability. The pressure against the inner surface required to prevent the contraction δa is also derived.
Attenuation of Gamma Rays. II. Transmission Values for Various Materials and Geometries
Authors: Peebles Glenn H.
Published: April 2005

A discussion of the effect of variation of the total absorption coefficient on gamma-ray transmission probabilities is given, which leads to estimates of the build-up factors for a material of arbitrary atomic number Z.

Estimates are made of the photon and energy densities arising from a plane of sources, a line of sources, and a point source in an infinite homogeneous medium, where the material of the medium is (1) iron and (2) lead.
Microwave Diffraction Measurements in a Parallel-Plate Region
Authors: Row Ronald V.
Published: April 2005

Many infinite two-dimensional electromagnetic-scattering problems are strictly equivalent to the configuration obtained from the image principle by placing a finite-scattering obstacle between two parallel, infinite, and perfectly conducting planes and illuminating it with a plane or cylindrical incident wave confined to the parallel-plate region.

An experimental approximation to this arrangement is described for use in the 3-centimeter wavelength region. Finite rectangular parallel metal plates support a transverse incident electromagnetic wave with the electric field oriented perpendicular to the plates. Absorbing wedges at the boundary of the region reduce reflections from this discontinuity. The electromagnetic field scattered from any particular obstacle may be investigated by means of a dipole probe introduced into the region through a moveable section of one of the plates.

The success of this technique is demonstrated by comparing measurements of the total field scattered by infinite conducting wedges of included angle 0, 45, and 90 degrees with the known theoretical expressions, for perpendicular incidence. Agreement with theory is good.

The effect of finite thickness of the diffracting screen (case of 0° wedge) in increasing the amplitude of the scattered wave is noted and compared to theoretical results derived for scattering from a thin conducting half-plane with a cylinder superimposed on the edge.
Theory of the Formation of Bubbles
Authors: Takagi Shunsuke
Published: April 2005

We have not yet obtained a perfect theory of bubble formation. In this paper the perfect theory of the formation of bubbles in the case where the bubbles of vapor are nucleated spontaneously in pure liquid is presented. This is done by the systematization of the classical theory of M. Volmer (Kinetik der Phasenbildung, 1939) and the theory of D. Turnbull and J. C. Fisher [J. Chem. Phys. 17, 71 (1949)] and it coincides satisfactorily with the experiment of K. L. Wismer [J. Phys. Chem. 26, 301 (1922)].

Theory must be advanced further so as to afford a perfect explanation of the processes of boiling, cavitation and the critical phenomena of the movement of soil moisture [S. Takagi, Monographs on Theoretical Soil Physics; Theoretical Considerations on the Thermodynamical and Kinematic Properties of Soil Moisture (not yet published)]. To effect this object, the author has calculated the rate of formation of bubbles at a surface. The theoretical value, however, of the negative pressure at which the liquid fractures does not coincide by any means with the atmospheric pressure in the process of boiling. This is true also in the process of cavitation and in the process of critical phenomena of the movement of soil moisture. Some other factors must be introduced in order to bring the theory to a state of practical value.
Variational Methods for Problems in Resistance
Authors: Carlson J. F. , Hendrickson T. J.
Published: April 2005

Schwinger's variational methods are applied to a resistance problem with mixed boundary conditions. By the use of two formulations, both upper and lower bounds to the resistance are obtained. Results are given for a cylinder subject to given boundary conditions for a number of values of the relevant parameters.
Approximate Solutions of the Space-Charge Problem for Some Unusual Electrode Geometries
Authors: Ivey Henry F.
Published: April 2005

An approximation technique for computing the space charge limited current between electrodes of unusual and complicated geometry that cannot be treated rigorously is discussed and applied to several electrode systems involving both cylindrical and sphreical emitters. This method was originally suggested by Matricon and Trouvé and by O'Neill. All that is required is a knowledge of the electrostatic capacitance of the system concerned. Many electrode systems of practical importance which were heretofore not susceptible of calculation are amenable to this technique.
Response of Two-Material Laminated Cylinder to Simple Harmonic Environment Temperature Change
Authors: Lowell Herman H.
Published: April 2005

In current aeronautical research, rapidly-responding thermocouples and hot-wire anemometers are required. The use of oxide cylinders coated with more or less thin layers of metal effects substantial improvements in rates of instrument response. The theory and results of numerical calculations for six typical situations are given. It is shown that for ratios of metal thickness to over-all radius of 0.1, response amplitude gains of the order of 4 or 5 are to be expected as compared with typical gains of the order of 10 or more for infinitesimal shells (surface layers).
Direct Determination of the Flow Curves of Non-Newtonian Fluids. II. Shearing Rate in the Concentric Cylinder Viscometer
Authors: Krieger Irvin M. , Elrod Harold
Published: April 2005

Another method has been developed for obtaining the rate of shear vs shearing stress curves of non-Newtonian fluids from concentric cylinder viscometer data. The mathematical expression developed is a rapidly converging power series in lns, where s is the cup to bob radius ratio. An estimate of error shows that under favorable conditions only two terms of the series are significant, and that terms past the third will hardly ever be needed.
The Motion of a Sphere Moving Parallel to a Plane Boundary
Authors: Karal F. C.
Published: April 2005

The motion of a rigid sphere moving through an incompressible, homogeneous, nonviscous fluid in the presence of a rigid, infinite plane boundary is examined. The direction of motion of the sphere is assumed to be parallel to the plane boundary. It is assumed that the motion is irrotational and that the sphere velocity is small. An exact treatment is presented. Several curves of the pressure variation on the plane boundary are plotted for different values of the ratio of sphere radius to the perpendicular distance from the center of the sphere to the plane boundary.
The Effect of the Rate of Cooling on the Allotropic Transformation Temperatures of Uranium
Authors: Duwez Pol
Published: April 2005

Allotropic transformation in uranium has been studied over a range of cooling rates from 5 to about 8000°C/sec. The transformation temperatures of both gamma-to-beta and beta-to-alpha were found to decrease continuously with increasing rates of cooling. The extent of the beta-range increased with increasing cooling rates. For rates of cooling up to 1000°C/sec, recalescence was observed in both transformations. For higher cooling rates, there was usually no recalescence.

In most of the recorded cooling curves, a small but definite thermal arrest was observed, between the two main arrests which correspond to the two known phase transformations. This additional thermal arrest was also present in a heating curve, where it occurred at about 740°C, compared with 666 and 771°C for the two known phase transformations. Possible explanations of the additional arrest are discussed.
Plastic Electrets
Authors: Wieder H. H. , Kaufman Sol
Published: April 2005

A brief discussion of proposed explanations for the electret effect is presented. Plexiglas, Lucite, and Nylon electrets were prepared under fields ranging from 19 to 36 kv/cm and observed for as long as 2000 hours. The surface charge densities were measured by electrostatic induction using a commercial electronic electrometer and a shunt capacitance to reduce the readings to a maximum of 20 volts. The initial state was a heterocharge or a homocharge depending on the strength of the forming field. The steady state was a homocharge in every case. Charge densities as high as 5.5×10−9 coulomb/cm2 (16.5 esu) were observed. A Plexiglas disk was charged at room temperature under a strong field and its subsequent decaying homocharge recorded. The experimental results support the ideas of Mikola and Gross, i.e., the existence of two decaying polarizations of opposite sense due to ionic migration, one occurring within the dielectric, the other, across the electrode-dielectric interface.
A Thermoelectric Study of the Electrical Forming of Germanium Rectifiers
Authors: Kikuchi Makoto , Onishi Tomio
Published: April 2005

The electrical forming phenomena on the etched surfaces of n-type Ge crystals by ac voltages were studied thermoelectrically. Remarkable improvements in the i-v characteristics were obtained by applying appropriate forming voltages. The thermoelectric current observed on the etched surface showed n-type direction but it was converted to p-type by the forming. It has also been found out that the thermo-emf depends sensitively on the pressure of the whisker contact after the forming (and on the polished surface), while the dependence is small before the forming on the etched surface.

Experimental results seem to show that some substance of relatively high resistivity and of p-type thermo-emf is produced by the forming between the whisker metal and the Ge surface.
Solution of Nonlinear Differential Equations by the Reversion Method
Authors: Cohn George I. , Saltzberg Bernard
Published: April 2005

By the use of the reversion method certain types of ordinary nonlinear differential equations can be reduced to a set of ordinary linear differential equations which may conveniently be solved by the Laplace transform. The expression for the general member of the linear set is developed and written out in detail for certain illustrative terms. The method is applied to two simple problems for which the answers are exactly known so that some idea may be obtained as to the excellence of the approximations supplied by this method.
Forced Oscillations with Nonlinear Restoring Force
Authors: Hayashi Chihiro
Published: April 2005

Forced oscillations with nonlinear restoring force are studied in transient states as well as in steady states. The original differential equation characterized by a nonlinear term is transformed under certain restrictions to the following differential equation of the first order: dy/dx=Y(x,y)/X(x,y).

Following Poincaré and Bendixson, the singularities and the integral curves of the above equation are discussed, the former being correlated with the periodic states of oscillations, the latter with the transient states of oscillations. The stability of the periodic solutions is determined in accordance with that of the singular points, viz., according to the roots of the characteristic equation. The integral curves yield the relationship between the given initial conditions and the periodic solutions. Thus, once the initial conditions are prescribed, we can foresee the final periodic states which are started with those conditions.

With this method of investigation, we have first studied the harmonic oscillations presented in Part I and then the subharmonic oscillation of order ⅓ given in Part II. In both cases the theoretical results are compared with the experimental measurements carried out for an electric circuit containing a saturable iron core, and the satisfactory agreement is found between them.
The Use of Large Scale Computing in Physics
Authors: Sheldon John , Thomas L. H.
Published: April 2005

A number of methods of numerical solution of systems of partial differential equations are surveyed. The size and speed of computing machines required to solve problems of varying complexity is discussed. Finally, a number of typical problems which have been solved numerically by various authors are described.
Wave-Guide Measurements in the Microwave Region on Metal Powders Suspended in Paraffin Wax
Authors: Kelly Joseph M. , Stenoien Joseph O. , Isbell Dwight E.
Published: April 2005

Artificial dielectrics have been constructed with indices of refraction as high as 7.2 at a frequency of 9364 mc/sec by imbedding microscopic conducting flakes in paraffin wax. When good conductors such as Cu and Al are used, the resulting permeability is observed to be complex while the permittivity is substantially real. This phenomenon is in agreement with the theoretical results of Lewin. It is indicated that a low loss, high refractive index, artificial dielectric can be constructed by using powdered conductors if the particles are very small and possess a high electric polarizability.
Numerical Method for Porous Heat Sources
Authors: Schneider P. J.
Published: April 2005

An extension of the Emmons numerical method for temperature fields is developed for application in cases of solid-fluid heat transfer in which a gas or fluid passes through a porous wall generating nonuniform heat. The numerical approach is first presented in general form and then applied to the two specific cases of a porous power-producing cylindrical pipe and porous power-producing plain wall.
An Operational Analysis of Traffic Dynamics
Authors: Pipes Louis A.
Published: April 2005

The dynamics of a line of traffic composed of n vehicles is studied mathematically. It is postulated that the movements of the several vehicles are controlled by an idealized ``law of separation.'' The law considered in the analysis specifies that each vehicle must maintain a certain prescribed ``following distance'' from the preceding vehicle. This distance is the sum of a distance proportional to the velocity of the following vehicle and a certain given minimum distance of separation when the vehicles are at rest. By the application of this postulated law to the motion of the column of vehicles, the differential equations governing the dynamic state of the system are obtained.

The solution of the dynamical equations for several assumed types of motion of the leading vehicle is effected by the operational or Laplace transform method and the velocities and accelerations of the various vehicles are thus obtained. Consideration is given to the use of an electrical analog computer for studying the dynamical equations of the system.
Surface Effects and the Creep of Zinc Single Crystals: I. Creep Characteristics of Clean and Oxide-Coated Crystals
Authors: Coffin Frances Dunkle , Weiman Andrew L.
Published: April 2005

Quantitative studies of the influence of the surface composition on the creep of zinc single crystals under constant loads have been carried out. The creep curves of crystals with clean and oxidized surfaces were obtained in air and in acid. It is shown that a continuous layer of oxide strengthens the crystal only at low loads, and that the presence of cracks in this layer allows the metal to creep at its normal rate. These facts support the theory that the oxide film acts to relieve the metal of part of the load. An increase in creep rate is observed when the pure metal surface is treated with dilute mineral acids. The heat liberated by the reaction is considered as a possible explanation of the sudden increase in creep rate when the surface layer of the crystal is removed. The normal creep curves of unoxidized crystals in air may be described by an empirical equation of a new form, and its application to other types of curves obtained is discussed.
Temperature Gradients in Inductively Heated Cylinders
Authors: Thorn R. J. , Simpson O. C.
Published: April 2005

An exact expression for the temperature difference between the inside and outside of an infinitely long cylinder heated inductively has been derived in terms of Bessel functions. A numerical comparison shows that for small cylinders (radius about 0.3 cm) an assumed parabolic distribution of the magnetic intensity agrees with the exact solution within two percent.
Interesting Nonlinear Effects
Authors: Mackay R. Stuart
Published: April 2005

Series circuits of ordinary light bulbs and iron-core transformer coils are found to have properties of the different types of multivibrators and ring circuits. Besides their intrinsic interest value these circuits have application to a diversity of processes, e.g, switching, counting, and time delaying. They can all indicate their action and immediate state by switching on or off large incandescent lamps.
Elasticity and Thermal Expansion of Germanium Between −195 and 275°C
Authors: Fine Morris E.
Published: April 2005

Young's moduli (E) of the directions 〈100〉 and 〈111〉 and the shear modulus (G) for 〈100〉 were determined in germanium from −195 to 255, 275, and 140°C, respectively. From these moduli, the elastic parameters, the compressibility, and Poissons's ratio were calculated.

The thermal expansion was measured from −196 to 275°C.
A Transient Magnetic Dipole Source in a Dissipative Medium
Authors: Wait James R.
Published: April 2005

The solution is given for the electric field of a small current-carrying loop which is immersed in a dissipative medium and is energized by a step-function current. Approximate expressions for the magnetic fields are also derived. The propagation of an electromagnetic pulse in sea water is then discussed.
Limiting Conditions for Jet Formation in High Velocity Collisions
Authors: Walsh J. M. , Shreffler R. G. , Willig F. J.
Published: April 2005

The high velocity collision of two solids is discussed as a problem in compressible fluid hydrodynamics. Such collisions may conveniently be divided into jetless and jet-forming categories. A theory is presented which describes flow in the collision region for the jetless case and determines a critical collision angle (as a function of material velocities and equation-of-state properties of the materials) above which a jet must arise from the collision.

The experimental study of solid collisions utilizes metal plates driven by high explosives, the impact of the plates being recorded with a high speed smear camera. Two experimental arrangements are used, and data for collisions employing Dural, mild steel, brass and lead are presented. Jetless and jet-forming collisions are observed, and critical angles separating the two types are compared with theoretical predictions. Agreement seems sufficiently good to indicate that the theory is valid.
Statistical Criteria for the Detection of Pulsed Carriers in Noise. I
Authors: Middleton David
Published: April 2005

A theory for the detection of pulsed carriers (of constant amplitude) in narrow-band random noise is described, based on several types of optimum tests of a statistical hypothesis against an alternative (i.e., signal and noise vs noise). Siegert's concept of the betting curve is introduced, whereby, for a finite integration time, the minimum detectable signal is uniquely defined. Three types of observer are next considered: the Neyman-Pearson, the Ideal, and the Sequential observer, whose properties are determined by the manner in which the test is carried out. For each observer it is verified that the best second detector is a logI0-rectifier, which in practice is closely approximated by the usual half-wave linear envelope-tracer. In Part II specific betting curves are calculated and the performance of the three observers is analyzed for both the weak (threshold) and strong-signal cases.
Use of Tschebyscheff-Polynomial Operators in the Numerical Solution of Boundary-Value Problems
Authors: Shortley George
Published: April 2005

This paper concerns the numerical solution, in two or more dimensions, of boundary-value problems arising from linear partial differential equations, of which Laplace's and Poisson's equations furnish simple examples. Only techniques suitable for automatic computing machines are considered. The only method previously applicable to automatic machines is a straightforward iteration of an appropriate difference operator applied to an assumed trial solution on a network of points; as has been repeatedly pointed out, the rate of convergence of this iterative procedure is inordinately slow when the number of net points is large. The present paper shows how the employment of a Tschebyscheff polynomial of this same difference operator can cut the amount of work required in obtaining a solution by a very large factor—a factor of the order of magnitude of √N in the two-dimensional case, 3N in the three-dimensional case, where N is the number of net points. This method is an outgrowth of that developed by Flanders and Shortley [J. Appl. Phys. 21, 1326 (1950)] for employment of such Tschebyscheff-polynomial operators in the numerical solution of eigenvalue problems. The method is illustrated by a simple example involving Poisson's equation.
Effects of Very High Pressures on Glass
Authors: Bridgman P. W. , Šimon I.
Published: April 2005

In contrast to other inorganic solids, glasses may be permanently compacted by application of pressures of the order of 104 to 105 atmospheres. This effect was studied on two simple oxide glasses (SiO2 and B2O3) and several silicate glasses. The effect of compacting was studied by measuring the densities, dimensions, and x-ray diffraction patterns. A definite threshold pressure is observed in vitreous silica and silicate glasses, under which no effect takes place and above which the collapse takes place readily. Vitreous boric oxide behaves in a different manner, collapsing gradually, starting at the lowest pressures. Vitreous boric oxide exhibits also plastic flow with subsequent strain hardening. X-ray diffraction measurements performed on vitreous silica and boric oxide indicate that the compacting proceeds on the atomic scale, leaving, however, the short-range order of the basic structural units unchanged. The density of compacted glass can be restored to the original value by annealing to sufficiently high temperatures. Activation energy of this process was determined in the case of vitreous boric oxide.
Positive and Negative Ions in Cathode-Ray Tubes
Authors: Bachman C. H. , Hall G. L. , Silberg P. A.
Published: April 2005

The positive and negative ions accompanying the operation of a cathode-ray tube contribute in a number of ways to tube failure. These ions have been studied in standard sealed-off tubes. The identities of the most persistent ions have been determined and ion currents measured. Some attempts to limit or control the ions at their sources have been made.

The greatest offender is hydrogen which is present as both negative and positive ions. It is shown that aluminized screens offer little protection to the ion bombarded phosphor. Uncertainty in the literature as to whether negative m/e, 26 is C2H2 or CN seems resolved in favor of C2H2.
The Effect of Turbulence on Heat Transfer in a Pile with a Liquid Reactant
Authors: Parker E. N.
Published: April 2005

The spacing of cooling surfaces in a liquid reactant pile is considered in an elementary fashion. The resulting physical picture is that the eddy diffusion of thermal energy, which is enhanced by large free volumes of fluid, does not increase as fast as linearly with the spacing of cooling surfaces. Thus, for a given temperature difference between reactant and coolant, the total heat transfer decreases with increased spacing of the cooling surfaces. This disadvantage of large spacings is to be set off against the advantage of decreased parasitic neutron losses to the coolant.
Engravement of Transient Stress Wave Particle Velocities
Authors: Rinehart John S. , Pearson John
Published: April 2005

Quantitative information on the high intensity transient waves set up by impulsive loading is usually required in order to design rationally against failure under such loads. To obtain reliable data is often difficult when the loads last only a few microseconds and reach magnitudes of several hundred thousand pounds per square inch. A technique is described which enables quantitative determinations to be made either of particle velocity within the transient wave or of velocity of propagation of the wave. The scheme consists basically of measuring the depth of the permanent impression or engravement that is left on a surface when a pellet that has been previously affixed to that surface flies off. The engravement is a direct consequence of the impingement of a transient wave against the surface. Considerable numerical data are presented which establish the validity of the scheme. The simplicity of the technique suggests that it may find extensive application in impulsive loading investigations.
Photoelastic Studies of Quenched Cylinders and Spheres
Authors: Parsons K. A.
Published: April 2005

A mathematical theory of residual stresses of quenching origin based on an idealized model of the quenching process is investigated. Photoelastic curves are computed from the theory and compared with those determined with a Babinet Compensator. Ten glass cylinders and spheres quenched in molten lead are employed. Although the qualitative agreement between theory and experiment is good, a quantitative comparison shows that the theory needs improvement. Major factors in the disagreement are probably the neglect of the effects of plastic flow and the temperature dependence of the physical constants.
Work Functions of Gas-Coated Tungsten and Silver Surfaces
Authors: Weissler G. L. , Wilson T. N.
Published: April 2005

The average electronic work functions of tungsten and silver surfaces, subjected to glow discharges in various gases (He, A, H2, N2, O2, freon-12) and to water vapor, have been determined by Oatley's magnetron contact potential method. Oxygen and freon-12 produced increases in work functions in excess of 1 ev, whereas nitrogen and particularly hydrogen caused decreases of the order of 0.5 ev. The inert gases and water vapor produced relatively little changes. The history and treatment of the surfaces is described, and the data presented have been found to be reproducible.
Approximate Elastic Spectrum of Acoustic Waves in AgCl from X-Ray Scattering
Authors: Cole H.
Published: April 2005

The temperature diffuse scattering of x-rays from a large single crystal of AgCl has been measured at room temperature using a Geiger counter spectrometer and crystal monochromated CuK-α radiation. Measurements were made throughout the hk0 plane in reciprocal space, and in certain other regions. The data are analyzed on the basis of the theory developed by Laval and James, in which temperature vibrations are expressed in terms of traveling elastic waves. An assumed set of vibrational frequencies is used for the optical branch. Dispersion curves for waves in the acoustical branch traveling in the [100], [110], and [111] directions are obtained. The velocities at infinite wavelength are shown to agree fairly well with those given by the static elastic constants. An approximate frequency spectrum is then calculated, and suggestions are made as to how the effects of the optical and acoustical branches may be separated.
The Limiting Negative Pressure of Mercury in Pyrex Glass
Authors: Briggs Lyman J.
Published: April 2005

It is generally considered that mercury does not ``wet'' glass, as evidenced by the convex surface of the mercury meniscus in a manometer. If this were true under all conditions, the development of a negative pressure in a mercury column would be impossible. But pure mercury in a clean evacuated degassed tube shows a flat meniscus. In other words, when the tube is degassed, mercury does adhere to the glass wall.

A U-tube manometer of 5-mm bore with one leg sealed off was evacuated and degassed at 500°C with a mercury-vapor pump, and then filled with pure mercury by distillation. The vertical height of the mercury column from the meniscus in the open tube to the top of the closed leg was 52 cm. When the manometer was again evacuated, the mercury column remained suspended from the top of the tube, withstanding a negative pressure of two-thirds of an atmosphere.

In extending the measurements, short mercurial thermometers were first used. Each thermometer was cemented to the spinner of a variable-speed motor, with the spin axis bisecting the distance from the end of the bulb to the meniscus. The maximum centrifugal stress on the free capillary column was consequently at the spin axis. Measurement of nine thermometers gave negative pressures ranging from 2 to 17 bars.

Finally, freshly drawn capillary tubes with fine bores were evacuated, degassed by heating, sealed off and filled by breaking one end under pure mercury. The negative pressure which these mercury columns could withstand under centrifugal stress increased rapidly as the degassing improved. The highest negative pressure observed for mercury was 425 bars at 28°C. In this case, the furnace temperature during degassing was raised to the point where the capillary tube started to deform.
On Unsteady Flow of Compressible Viscous Fluids
Authors: Ludford G. , Polachek H. , Seeger R. J.
Published: April 2005

In order to solve the nonlinear equations of fluid dynamics, classical hydrodynamics introduced the concept of perfect incompressible fluids, viz., the perfect inviscid fluid and the perfect viscous fluid. The practical importance of considering compressibility nowadays has resulted in two new approaches from two distinct points of view. In the one case, compressibility is included in the discussion of a perfect inviscid fluid. As is well known, however, compressibile effects include shock-wave phenomena, which are regarded in this instance as mathematical discontinuities. The goal then is to study the basic equations, allowing discontinuous solutions. The other approach retains the viscous terms together with the compressible ones. It is based upon the possibility of small coefficients producing large changes in the behavior of the solutions. The present paper is written from this point of view. The consequent mathematical difficulties of solving the equations are avoided by the use of a particle model of the continuum; the authors are indebted to Professor R. von Mises of Harvard University for this idea. The resulting equations are put into finite difference form for solution on a digital calculator.
Pore Distribution in Porous Media
Authors: Meyer H. I.
Published: April 2005

An attempt is made to determine the actual distribution of the pore sizes in a porous rock from the cumulative distribution of mercury injected into the rock with increasing pressure against capillary forces. The aim is to correct for those pores which could fill at a given pressure but which do not, because they are connected to the mercury source only by smaller pores. The presented correction is based on probability concepts.
Propagation of Acoustic Waves in a Liquid-Filled Cylindrical Hole, Surrounded by an Elastic Solid
Authors: Somers Edward V.
Published: April 2005

The theory of elastic wave propagation in systems where discontinuities in the physical properties occur along concentric cylindrical surfaces is developed for an impulsive ring-shaped source. This source is mathematically similar to the point source discussed by Lamb and Pekeris. The field problem is solved for a liquid-filled column, surrounded by an elastic solid, representing a basic model applicable to well-logging problems.
Radiation Field of a Conical Helix
Authors: Chatterjee J. S.
Published: April 2005

It is now well known that a cylindrical helix, when excited at frequencies corresponding to wavelengths comparable to the length of one turn of the helix, can radiate a sharp beam along the axis over a wide frequency range (about one octave). It is shown in the present communication that if the helix be conical instead of cylindrical (the diameter varying along the length of helix), then the axial mode of radiation can be maintained over a much wider band of frequencies. The radiation pattern of a conical helix, 60 cm diameter at the base, tapering linearly to 20 cm at the top in 10 turns within a height of 112 cm (with the ``ground'' provided by brass disk of 100 cm in diameter) has been studied experimentally. It is found that the axial mode of radiation is maintained from 150 Mc/sec to 450 Mc/sec. By increasing the number of turns, the band width can be considerably increased. Assuming a linear current distribution, theoretical expressions have also been deduced for Eφ and Eθ for a conical helix. Some modifications of the simple conical helix, such as may have special applications, are indicated.
Elasto-Plastic Stress-Optical Effect in Silver Chloride Single Crystals
Authors: Goodman L. E. , Sutherland J. G.
Published: April 2005

The use of silver chloride as a material for ``photoelastic'' stress analysis offers the possibilities of studying both elastic and plastic states of stress in a crystalline material on either a micro- or macroscale. It is necessary, however, to relate quantitatively the stress state and the observed relative retardation and extinction angle. In this paper these relationships are developed from a general theory of stress birefringence, according to a stress-dependent hypothesis. This hypothesis and the resulting analytical relationships are experimentally vindicated by measurements made on a variety of single crystal specimens of silver chloride tested in simple tension in the elastic and plastic stress ranges.
The Gas Flow Past Slender Bodies
Authors: Munk Max M.
Published: April 2005

The following relates to moving objects immersed in a perfect gas otherwise at rest. The momentum of the resulting gas flow is defined. It is shown that it ultimately approaches a definite magnitude as the object assumes a steady motion, said magnitude being independent of the history of the previous motion.

This result is applied to the two-dimensional flows of airship theory, and thus the airship theory is extended to include compressibility effects to a limited extent.
Metal Capillary Cathodes
Authors: Katz H.
Published: April 2005

Since 1941 we have been working on the development of new types of cathodes, using elements such as barium or thorium as emitters. If provided with a suitable base, these elements are able to migrate and, acting as an atomic layer, reduce the work function of the base material. By introducing a separate supply source below the emitting surface, a work-function-reducing substance will be caused to migrate to the cathode surface through small capillaries. Evidently a wide range of new types of cathodes is feasible, since the independently stored emitter of a metal capillary cathode can be held at a temperature different from that of the cathode surface. The subject of this paper is the description of some of these cathodes.
The X-Ray Shadow Microscope
Authors: Cosslett V. E. , Nixon W. C.
Published: April 2005

Shadow projection permits higher resolution and simpler operation than other methods of x-ray microscopy. A point source, less than 1μ in diameter, is obtained by the use of magnetic electron lenses and used for projecting shadow images at a primary magnification up to 100× with an exposure time in the order of minutes. The use of a metal foil as target and tube window insures high intensity at the specimen, which is in air. A resolving power little short of the best optical performance has been obtained with an accelerating voltage of 10 kv. The practical limitations to resolution, contrast, and exposure time are discussed in detail. A resolution of 100A should be practicable, but only with longer x-rays and an exposure of the order of 1 hour.
Internal Friction and Young's Modulus of Cold-Worked Copper Single Crystals
Authors: Weertman J. , Koehler J. S.
Published: April 2005

The internal friction and Young's modulus of single crystals of copper were measured as a function of strain amplitude after they were subjected to various amounts of cold work and different annealing treatments. It was found that the position of the peak in the internal friction versus cold-work curve was dependent upon the strain amplitude of the measurement. No minimum in the Young's modulus versus cold-work curve was found as contrasted with Lawson's result for polycrystalline copper. A minimum was found in the internal friction versus annealing time curve, and a maximum was found in the corresponding Young's modulus curve. The results are semiquantitatively explained using a dislocation model.
Double Activators in Oxide Cathode Base Alloys
Authors: Eisenstein A. , John H. , Affleck J. H.
Published: April 2005

The presence of tungsten as a major impurity in the base metal of an oxide-coated cathode leads to the formation of the interface Ba3WO6. If silicon is also present, but as a minor impurity, this element gradually replaces tungsten in the interface to form Ba2SiO4. Similar reactions between titanium and aluminum with other known interface compounds were examined.
Axial Motion of Electrons in a Linear Accelerator with β=1
Authors: Swihart James , Akeley Edward
Published: April 2005

Complete integrated solutions have been found in terms of elementary functions for the motion of an electron on the axis of a progressive wave linear accelerator with a constant wave speed, β=1. The character of the solutions has been discussed and asymptotic relations found.

Calculations have been made for the third section of the Purdue linear accelerator, in which the curves for the first two sections where β<1 have been extended. The energy distribution of the emergent beam was computed. It was found possible to design a linear accelerator with constant wave speed sections which, without preliminary bunching, would produce a beam of greater homogeneity in energy than might have been expected.
Radiation Resistance of a Small Circular Loop in the Presence of a Conducting Ground
Authors: Wait James R.
Published: April 2005

The solution is given for the total power flow from an oscillating magnetic dipole, situated above a flat homogeneous conducting ground and oriented in the vertical direction. The result is employed to derive an expression for the radiation resistance of a small wire loop whose axis is perpendicular to the ground. It is pointed out that for a finitely conducting ground that the radiation resistance is very large when the height of the small loop or dipole is a small fraction of a wavelength.
A Test of the Theory of Secondary Viscoelastic Stress
Authors: Mooney M.
Published: April 2005

Experimental data published by Garner, Nissan, and Wood on secondary stresses in a viscoelastic liquid have been analyzed in terms of the superelasticity theory of secondary stresses as developed by Mooney. The theory was slightly modified to be consistent with the reported viscosity rate of shear behavior of the test liquid. With this modification the theory agreed within experimental error with observed normal stresses at various radii on a stationary circular plate mounted parallel to a rotating plate.

One reported qualitative experimental result is in disagreement with the theory, but this particular result is questioned. Other theories of secondary stress are briefly discussed.
Viscoelastic Properties of Dilute Polymer Solutions
Authors: Rouse P. E. , Sittel K.
Published: April 2005

The viscoelastic properties of dilute solutions of chain polymers have been measured at frequencies in the range from 200 cps to 60 kc. The data are compared with theoretical curves calculated from the steady-flow viscosities of the solution and solvent, the molecular weight and concentration of the polymer, and the absolute temperature; this calculation made use of equations obtained from a recently developed theory. The equations contain no adjustable constants. The theory is shown to be at least a good first approximation to the viscoelastic properties of the solutions studied.

The agreement of the data and the theory implies that, up to 60 kc at least, the viscoelastic properties of dilute solutions of polystyrene and polyisobutylene are the result of the thermal motions of the segments of the polymer molecules. These segmental motions coordinate with one another to produce changes in the configurations of the molecules. The configurational changes have associated with them a series of relaxation times. These relaxation times are shown to depend upon molecular weight of the polymer, concentration, type of solvent, and viscosity of solvent.
An Investigation of Boron Carbide
Authors: Glaser Frank W. , Moskowitz David , Post Benjamin
Published: April 2005

Mixtures of boron and carbon were heated at approximately 2000°C; the reaction products have been studied by x-ray diffraction and by density and electrical measurements. The existance of a wide range of homogeneity of ``boron carbide'' has been established. No evidence of compound formation corresponding to B4C could be detected. Similarities between the structures of boron and ``boron carbides'' indicate that the latter may best be described as solutions of varying amounts of carbon in a slightly distorted boron lattice.
The Creep of Zinc Single Crystals under Direct Shear
Authors: Weinberg Elliot H.
Published: April 2005

Room temperature measurements on very pure specimens verify the Tyndall law, s=atm, which was determined by tensile measurements. The value of m is approximately 0.6. Discrepancies in tensile creep tests reported by other observers are shown experimentally to be caused most probably by bending of the specimen during the creep process. The Bauschinger effect has also been investigated and creep at the very small stresses needed appears to follow the same creep law.
Mutual Impedance of Rhombic Antennas Spaced in Tandem
Authors: Chaney Jesse Gerald
Published: April 2005

Upon examining the formulas for self- and mutual impedances of antennas, it is found that while the mutual impedance formula for separately driven collinear standing wave antennas may be used directly in determining the radiation impedance when such antennas are connected in cascade, certain modifications must be made in the case of traveling wave antennas under similar circumstances. Accordingly, formulas are derived for rhombic antennas spaced in tandem and are modified to permit the determining of the radiation impedance of two identical rhombic antennas connected in cascade.
Determination of the Drag on a Cylinder at Low Reynolds Numbers
Authors: Finn R. K.
Published: April 2005

Drag coefficients for a cylinder were measured at Reynolds numbers from 0.06 to 6.0 by observing the deflections of thin wires suspended in an air stream. The results confirm a theoretical equation proposed by Lamb and are consistent with experimental data of other investigators.