bluuebunny/crossref_metadata_2025 huggingface dataset:
Further Investigation of Laminar Flow in Channels with Porous Walls
Authors: Yuan S. W.
Published: April 2005

The problem of two-dimensional steady-state laminar flow in channels with porous walls has been extended to the case of moderate to high suction or injection velocity at the walls. An exact solution of the Navier-Stokes equations, reduced to a third-order nonlinear differential equation with appropriate boundary conditions, is obtained. The velocity components, the pressure, and the coefficient of wall friction are expressed as functions of velocity through the porous walls, the average axial velocity of Poiseuille's flow, the coordinates and dimensions of the channel, and the physical properties of the fluid.
Detonation Wave Fronts in Ideal and Nonideal Detonation
Authors: Cook Melvin A. , Horsley G. Smoot , Keyes Robert T. , Partridge William S. , Ursenbach Wayne O.
Published: April 2005

Extensive wave shape data are presented for various (effectively) unconfined explosives over wide ranges of diameter d, length L, density ρ1, and physical conditions. Observed wave fronts were invariably spherical segments with radii of curvature R increasing at first directly with L(R=L), but eventually becoming steady at a constant value Rm/d between 0.5 and 4 depending on the charge diameter primarily through the ratio a0/d (a0=reaction zone length). At the critical diameter of propagation (large a0/d) Rm/d approached 0.5, and at large diameter (small a0/d) it approached or leveled off at the upper limit of about four. The upper limit (Rm/d∼4) is apparently a restriction imposed by the fundamental nature of detonation of solid explosives with free boundaries.
Cross Section of Colinear Arrays at Normal Incidence
Authors: Minkowski Jan M. , Cassedy Edward S.
Published: April 2005

The backscattering cross section of colinear arrays of thin dipoles at normal incidence has been derived using the variational method. It was found advantageous to use the variational principle in its scale-dependent form, since the extremum of the variational functional does not depend on the scales of the currents. The special case of the two dipole array is computed using the derived formula. The interaction integral of two dipoles is integrated giving a result is closed form. In spite of the crudeness of the trial functions used, the results appear in good agreement with the experimental data. These were taken on a Doppler modulated synchronous detection system at 3000 Mc/sec.
Physical Theory for Capillary Flow Phenomena
Authors: Miller E. E. , Miller R. D.
Published: April 2005

From the assumption that the microscopic behavior of the liquid in an unsaturated porous medium is controlled by the physical laws of surface tension and viscous flow, differential equations governing the macroscopic flow in such a medium are deduced. No special pore-shape assumptions are required, but one topological approximation is needed; i.e., that neither isolated drops nor isolated bubbles occur. Several nonessential simplifying assumptions are used; i.e., that the macroscopic properties of the medium, the character of the liquid, and the pressure of the gas are independent of position, time, and direction. The macroscopic equations are obtained in a fully reduced form, permitting comparison between two media— or between two flow systems—that differ only by scaling factors.

A novel feature of this calculation is its prediction that the liquid-transmission and liquid-capacity properties of an unsaturated medium will exhibit hysteresis in their dependences upon the liquid-gas pressure differential, p. The properties of the medium depend upon the pressure history but are invariant to monotonic time-scale distortions of that history. Such time-invariant functionals have been termed by the authors ``hysteresis functions,'' symbolized by the subscript, H, e.g. FH(p). Although methods for measuring and describing the characteristics of specific ``hysteresis functions'' have not yet been developed, the general validity of this analysis can be studied experimentally by testing predictions that are contained in the reduced variables.
On the Use of Gram-Charlier Series to Represent Noise
Authors: Horton C. W.
Published: April 2005

The stochastic time series produced by the arrival at random times of identical individual events is considered. It is shown that if the shape of the individual events and of the resulting autocorrelation function and power spectrum are each represented by a Gram-Charlier series, relatively simple relationships exist between the different sequences of coefficients. These relationships are most serviceable when the coefficients of the autocorrelation function are used as the primary quantities. If the band width of the noise is ``moderate,'' the series has a small number of terms and consequently is practical from a computational viewpoint. The formulas are applied to the experimental data of noise produced when current is forced backwards through a silicon crystal. The shape of the individual noise events is determined from a knowledge of the experimental autocorrelation function. As a check on the analysis the power spectrum and the expected number of zeros per second are computed from the Gram-Charlier series and compared with the experimental data.
Method of Representing Preferred Orientation Data
Authors: Jetter L. K. , McHargue C. J. , Williams R. O.
Published: April 2005

For the fiber-texture type of preferred orientation, a method is developed for determining the ``fiber axis density'' from the ``pole density'' given by x-ray diffraction data. The fiber axis distribution so deduced gives directly and quantitatively the type and degree of preferred orientation—the more preferred crystallographic directions of the fiber axis, the symmetries of the orientation distribution about the preferred directions, and the relative volumes of material associated with the various components. The procedure is demonstrated for extruded aluminum rod. The method is adapted to the study of the sheet-texture type of preferred orientation and applied in determining the textures in cold-rolled 65–35 brass and 2S aluminum sheet.
Excitation of Space Charge Waves in Drift Tubes
Authors: Scotto M. , Parzen P.
Published: April 2005

An analysis has been made of the effect of initial conditions on the excitation of electromagnetic waves in a drift tube. The method employs the Laplace transform which directly includes the initial quantities. Field quantities which have been transformed with respect to the longitudinal coordinate are solved for and the results then inverted. Explicit expressions are then obtained for the velocity, charge density, and current density modulations as a series of modes.
Bridge and Short Arc Erosion of Copper, Silver, and Palladium Contacts on Break
Authors: Ittner W. B.
Published: April 2005

The bridge and short arc erosion of copper, silver, and palladium contacts and a number of alloys of these materials has been measured as a function of the break current in a circuit containing only a small amount of inductance. A theory is presented for calculating the arc duration, the charge passed by the arc, and the arc energy. Under the described conditions the total charge passed in the arc as well as the arc energy is proportional to the square of the rupture current. Short arc erosion in such a circuit will show, therefore, the same current dependence as bridge transfer. While it is possible to effectively separate the two types of erosion by controlling the circuit inductance evidence is presented to indicate that the two processes may not be completely independent.
Apparatus for the Direct Determination of the Dynamic Bulk Modulus
Authors: McKinney John E. , Edelman Seymour , Marvin Robert S.
Published: April 2005

An apparatus has been developed for the direct measurement of the real and imaginary parts of the dynamic bulk modulus of solid and liquid materials over the frequency range of 50 to 10 000 cps. Piezoelectric crystals serving as driver and detector, together with the sample and a confining liquid, are contained in a cavity small compared with the wavelength of sound at these frequencies. Static pressure is superposed to eliminate the effect of small air bubbles. The complex compliances of the sample, confining liquid, and the cavity, are additive in this region, where the compliance is pure dilatation. The dynamic compliances of several natural rubber-sulfur mixtures were obtained in a preliminary evaluation of the behavior of the apparatus.
Flow Patterns in Glacier Ice
Authors: Nielsen Lawrence E. , Stockton F. D.
Published: April 2005

The mass of ice varies along the length of a glacier because of the accumulation of snow in its upper regions and the ablation of ice in the lower regions. This mass change brings about variable speeds of flow and complex streamlines. General equations are derived using a type of plug flow for ice for the following: (1) glaciers of constant arbitrarily shaped cross sections, arbitrary rates of ablation and accumulation, and arbitrary variations of the longitudinal velocity across the glacier; and (2) glaciers of rectangular cross section with varying widths and depths, arbitrary velocity profiles, and arbitrary rates of ablation and accumulation. Streamlines are calculated for five typical cases by using these general equations. The calculated flow behavior is in agreement with the known behavior of glaciers.
Theory of Deformation of a Porous Viscoelastic Anisotropic Solid
Authors: Biot M. A.
Published: April 2005

Equations are established for the deformation of a viscoelastic porous solid containing a viscous fluid under the most general assumptions of anisotropy. The particular cases of transverse and complete isotropy are discussed. General solutions are also developed for the equations in the isotropic case. As an example the problem of the settlement of a loaded column is treated. The second–order effect of the change of permeability with deformation is also discussed.
Resolution of the Atomic Structure of a Metal Surface by the Field Ion Microscope
Authors: Müller Erwin W.
Published: April 2005

A formula for the resolution of the field ion microscope is derived by considering that most of the ions originate from rebounding molecules after random elastic collision with the surface. Cooling the tip with solid N2 or liquid H2 in order to obtain a large accommodation coefficient drastically reduces the lateral velocity of the ions in a helium operated microscope. As a result the potential resolution for a tip of radius 1000 A is improved to 1.5 A. Photographs show the individual atoms of a tungsten surface. The actual resolution is sufficient to resolve neighboring atoms with 2.74 A separation.
Problem of Intense Surface Heating of a Slab Accompanied by Change of Phase
Authors: Masters Joseph I.
Published: April 2005

In an attempt to bound the problem, steady-state solutions are obtained for the speed of surface recession (melting) and the internal temperature history of a slab which uniformly absorbs heat on one face at a large caloric rate. The solutions are found to be sensitive to assumptions that must be made regarding both the thickness attained by the layer of molten matter produced during the heat pulse and the mechanisms (e.g., air drag, evaporation) that control this thickness.
Effect of Dispersion and Geometric Intensity Factors on X-Ray Back-Reflection Line Profiles
Authors: Lang A. R.
Published: April 2005

At high diffraction angles the rapid variation of dispersion causes the center of gravity of the observed diffraction-line distribution of intensity versus 2τ to be displaced away from the Bragg angle τm corresponding to the mean value ρ̄λ̄ of the convolution of the distribution of lengths ρ of reciprocal-lattice vectors hkl with the distribution of x-ray wavelengths λ. The displacement has been calculated for the case of measurements both on individual Kα components and on unresolved Kα doublets. In a probable example of the latter case, with CuKα radiation, the displacement at 2τ=160° corresponds to a relative error in spacing measurement of 1 part in 104 and increases rapidly with increasing 2τ. The simple procedure is recommended of replotting the observed intensities against a scale of sine τ. The mean of the replotted distribution corresponds very closely to τm.
Diffusion of Donor and Acceptor Elements in Silicon
Authors: Fuller C. S. , Ditzenberger J. A.
Published: April 2005

The diffusion of the Group III (B, Al, Ga, In, and Tl) and Group V (P, As, Sb, and Bi) elements in silicon has been measured in the temperature range 1050–1350°C. A method based on change in conductivity through the penetration layer has been used for B and P. The p-n junction method has been used for the other elements. Aside from B and P, which have similar diffusional properties, the acceptor elements diffuse more rapidly than the donor elements. Diffusion coefficients are given by DB, P=10.5 exp − (85 000/RT), DA1=8.0 exp − (80 000/RT), DGa=3.6 exp − (81 000/RT), DIn, T1=16.5 exp − (90 000/RT), DAs=0.32 ×exp − (82 000/RT), DSb=5.6 exp − (91 000/RT), DBi=1030 exp − (107 000/RT) with an average estimated error of about ±40%. This corresponds to an error in the activation energies of about ±5 kcal. Sources of error including the effects of impurities in the oxides are discussed. D0 values in most cases conform to the predictions of Zener for substitutional diffusion.
Velocity Discontinuity Instability of a Liquid Jet
Authors: Dunne B. , Cassen B.
Published: April 2005

The instability of a high-speed liquid jet with a velocity which has a transient rise followed by a linear decay with time is studied experimentally and theoretically. The jet is produced experimentally by subjecting a liquid reservoir to a shock-wave pressure. Using a shadowgraph technique, in an interval of thirty microseconds four successive quarter-microsecond exposures were taken using jets of water and ethanol in external atmospheres of air and helium. It is found theoretically that a velocity discontinuity is advanced through the jet at a velocity which is the mean of the instantaneous particle velocities immediately in front of and behind the discontinuity. The discontinuity consists of a thin disk of liquid normal to the jet axis. Nodules previously observed on high-speed liquid jets [J. Appl. Phys. 25, 569 (1954)] can be explained by this mechanism.
Effect of Strain on the Work Function of Polycrystalline Silver
Authors: Wallis George , Farnsworth H. E.
Published: April 2005

Contact potential difference measurements in a pressure range from one atmosphere to about 10−8 mm Hg have indicated that mechanically induced strain of the order of 1% (beyond elastic limit) in polycrystalline strips of silver produces an increase in work function of between 0.01 and 0.03 ev. Annealing at about 400°C for a period of ten minutes approximately restores the original value of work function. Possible explanations of the effect are discussed.
Experiments on the Displacement of the Ultraviolet Absorption Edge of Olivine at High Pressures
Authors: Runcorn S. K.
Published: April 2005

The effect of pressure on the fundamental excitation energy of valence electrons in the ferromagnesium orthosilicate, the mineral olivine, is of interest in the theory of the electrical conductivity of the earth's mantle. The experimental determination of this by observation of the displacement of the ultraviolet absorption threshold of olivine up to pressures of about 30 000 bars is described.
Tuned Circuits Containing Negative Resistance
Authors: Gross Josef
Published: April 2005

A negative resistance connected to a ``suitable'' resonant circuit (a current-controlled negative resistance connected to a series-tuned circuit, or a voltage-controlled negative conductance connected to a parallel-tuned circuit) constitutes an almost-harmonic oscillator. In this paper the ``unsuitable'' connections (a current-controlled negative resistance connected to a parallel-tuned circuit, or a voltage-controlled negative conductance connected to a series-tuned circuit) are analyzed qualitatively in terms of variables leading to a single-valued phase plane. Physical considerations, expressed in a jump condition, serve to connect different regions of analyticity of the differential equations of the circuit in this plane. The ``unsuitable'' connections cannot sustain almost-harmonic oscillations, and their theoretically possible relaxation oscillations are unstable; they yield bistable circuits.
Hardness Plateaus and Twinning in Steel by Explosives with Lined Cavities
Authors: Singh Sampooran , Krishnaswamy N. R. , Soundraraj A.
Published: April 2005

This paper describes the changes in hardness and microstructure in annealed low carbon steel by jets squirted from high explosives with steel-lined conical cavities. Hardness measurements and photomicrographs were taken along different radii in a plane normal to the axis of the crater in the steel. Each hardness versus distance curve exhibited a series of plateaus along which the hardness remained constant. The plateaus appear to be related to Neumann bands which are present in the steel. It appears that the impact of an element of the jet on the steel initiates a transient compressional stress wave in the body of the steel which results in the hardness plateaus and the increase in the number of twin directions with hardness.
Čerenkov Radiation from Extended Electron Beams Near a Medium of Complex Index of Refraction
Authors: Lashinsky Herbert
Published: April 2005

An earlier theoretical treatment of the Čerenkov radiation excited by the passage of a bunched electron beam moving parallel to a dielectric medium at a small distance is extended to the case of a medium with a complex index of refraction. It is found that under suitable conditions, the use of a ferrite material as a medium can in principle enhance the radiated power. This effect is analyzed in terms of the work done by the beam on the field and the coupling between the beam and the medium.
Irradiation-Induced Phase Transformation in Zirconia
Authors: Wittels M. C. , Sherrill F. A.
Published: April 2005

As a result of fast neutron bombardment, monoclinic ZrO2 is transformed into the cubic phase normally stable only above 1900°C. It is suggested that the unique temperature-structure behavior in the zirconia system lends itself to this transition in a manner whereby two possible mechanisms may be operative. Stresses acting about trapped interstitial atoms and thermal spike effects are presented as the possible mechanisms.
Stress Relaxation in Concentrated Solutions of Polymethyl Methacrylate: Molecular Weight Dependence
Authors: Watkins J. M. , Spangler R. D. , McKannan E. C.
Published: April 2005

The measurement of stress relaxation in concentrated solutions of polymethyl methacrylate has revealed a relation between the spectrum of relaxation times, the weight average molecular weight, and the molecular weight distribution. The spectrum of relaxation times and the essentially identical theories developed by Rouse, Bueche, and Zimm are used to calculate an average relaxation time which is directly proportional to the weight average molecular weight. It is then shown that a first approximation to the distribution of molecular weights may be calculated if one assumes that the friction factor increases with the 1.5 power of the molecular weight. This distribution for selected samples of polymethyl methacrylate is compared with the Schulz distribution in which the parameters were obtained from light scattering and osmotic pressure experiments. The ratios Mz/Mw calculated from the theory and stress relaxation data on a rough fraction, a whole polymer, and a blend of two whole polymers are found to be 1.3, 1.7, and 1.9, respectively.
Effects of Neutron Irradiation upon the Young's Modulus and Internal Friction of Copper Single Crystals
Authors: Thompson Donald O. , Holmes David K.
Published: April 2005

Measurements of neutron irradiation effects upon the Young's modulus and logarithmic decrement of a set of copper single crystals of 99.999% purity have been made at room temperature. Interpretations of the results can best be given in terms of an oscillating dislocation line mechanism in which the oscillations are suppressed by the presence of interstitial atoms, vacancies, or some combination thereof. Comparisons of the results with the predictions of impurity line pinning are given. It is shown that an interpretation in this sense leads to generally accepted values for the dislocation densities and average segment lengths.
Strain-Amplitude Dependent Internal Friction Studies of Dilute Alloys of Copper
Authors: Weinig S. , Machlin E. S.
Published: April 2005

This paper presents an investigation of the room temperature decrement in dilute polycrystalline alloys of copper as a function of strain amplitude and annealing at a frequency of about 1 cps. The characteristics of the internal friction measured are:

(1) The internal friction and strain amplitude dependence of the internal friction decreases with increasing solute content.

(2) The internal friction is reversibly dependent upon the preanneal temperature.

(3) The internal friction is hysteretic with strain amplitude.

From the effect of the solute concentration and annealing temperature on the decrement, values for the binding energy for Al and Si solute atoms to dislocations in copper were calculated. These values are compared to theoretical values calculated on the basis of strain and electrical interaction energies. The experimental binding energy is in good enough agreement with the theoretical values to conclude that the onset of a strain amplitude dependence of the internal friction is caused by the freeing of sufficient dislocations from their pinning solute atoms.
Technique for Approximate Measurement of Correlation Coefficients
Authors: Goodman Thomas P.
Published: April 2005

A new method is described for approximate measurement of the coefficient of correlation between two random variables which can be represented by time-varying electrical voltages. This method makes use of simple analog-computing elements to obtain the coefficient of linear regression of one variable on the other. Its use in connection with an oscilloscope display of the two variables is described, and the relation between these displays and the Lissajous figure formed by two sinusoids is discussed. A possible design for a directreading correlation meter is suggested.
Theory of Nonlinear Coupling in a Novel Ferroelectric Device
Authors: Higa Walter H.
Published: April 2005

A novel dielectric modulator consisting of two pairs of mutually orthogonal plates on a block of ferroelectric material is described. Interaction between the orthogonal fields due to the nonlinear properties of the dielectric is shown to exist. The differential equation of performance is linearized to the Mathieu-Hill type and applied to the analysis of the device when used as a frequency multiplier.
Influence of Molecular Structure upon the Electric Strengths of Liquid Hydrocarbons
Authors: Sharbaugh A. H. , Crowe R. W. , Cox E. B.
Published: April 2005

The electric strengths of straight-chain liquid alkanes are known to increase with increasing molecular chain length. The introduction of branches in the hydrocarbon chain, on the other hand, results in a reduction in strength. In an effort to gain a clearer understanding of this behavior, we have extended our investigations to include hydrocarbons of more complex molecular structure. In the present paper we present the results of a study of the influence of molecular structure upon the electric strengths of benzene and a series of alkyl benzenes. The strengths of those members in which the alkyl group is unbranched bear a nearly linear relationship to the molecular weight, not unlike that observed for the n alkanes. Furthermore, branching of the alkyl side chain again results in a decrease of electric strength. An attempt is made to interpret the results in terms of a simple model.
Investigation of Nonrotationally Symmetrical Electrostatic Electron Optical Lenses
Authors: Whitmer Romayne F.
Published: April 2005

Electrostatic lenses which are nonrotationally symmetric, constant in time, free of space charge, and in which the electrostatic potential along the axis of the lens does not fall to the cathode potential are investigated. In general nonrotationally symmetric lenses suffer from first-order distortion and astigmatism. A method is given for determining lenses of the assumed symmetry which are free of these first-order aberrations. This is accomplished by deriving an imaging relationship between φ2(z), an arbitrary field parameter introduced from the assumed field symmetry, and φ(z), the rotationally symmetric component of the axial potential distribution, from the paraxial ray equations. The equations for the spherical aberration of such a lens are derived by standard methods. A method is given for finding lenses of reduced aberration and specific examples are discussed.
Effective Dielectric Constant of Heterogeneous Media
Authors: Smith Robert S.
Published: April 2005

A method for measuring the dielectric constant and conductivity of powders is described. Numerous formulas of earlier workers pertaining to the dielectric constant of porous media of low density are discussed. It is then shown that these relations incorrectly predict a value of the intrinsic dielectric constant which is a function of density. In an effort to develop a formula which would predict correctly the density dependence to at least a medium range of densities, a calculation is presented which expresses the effective dielectric constant of a given system as a function of particle shape, intrinsic dielectric constant, powdered density, and packing properties of powders composed of ellipsoidal particles. The formula involves the demagnetization coefficient and intrinsic dielectric constant of the powder particles. Data obtained from measurements of dielectric constant of magnetism oxide, silica, polystyrene, zinc oxide, etc., were applied to this formula and the intrinsic dielectric constants inferred agreed with bulk measurements by other workers, and the particle shapes derived from dielectric measurements agreed with other physical properties of the powder.
Creep of Aluminum Single Crystals
Authors: Weertman J.
Published: April 2005

High-temperature creep measurements were made on aluminum specimens cut from one single crystal. The stress range covered was from 2.5×106 to 1.9×108 dynes/cm2. The temperature range was from 157° to 616°C. The creep rate is proportional to (stress)4.6 exp(−Q/kT) where Q is the activation energy of creep (36 000 cal/mole) and kT has its usual meaning.
Adhesion and Contact Error in Length Metrology
Authors: Bruce C. F. , Thornton B. S.
Published: April 2005

An account is given of experimental studies of the nature of the strong adhesive contact between finely finished steel and glass surfaces when a trace of liquid exists between them. These surfaces are of the kind that are of practical use in length metrology where this adhesive action or ``wringing'' is of considerable importance.

The dimensional effects of the thin film between the surfaces have been measured by multiple-beam interferometry and the nature of the adhesive contact has been further studied by measuring tangential forces and electrical characteristics.

The experimental evidence suggests that there is no liquid film effectively separating the surfaces but that the strong adhesive action induced by the presence of the liquid introduces a dimensional contact error. This error is likely to be positive or negative, depending on the degree of contact between the surfaces. Provided the adhesion is good the contact error is not greater than ±0.01μ. Where such an error is undesirable in high precision length metrology it is better to avoid the use of this adhesive contact.
Time Dependence of Mechanical Breakdown Phenomena
Authors: Coleman Bernard D.
Published: April 2005

A phenomenological theory of the time dependence of mechanical breakdown phenomena is presented which is applicable to creep failure of oriented polymeric filaments under tensile stresses. In using the theory, one makes assumptions about the distribution of breaking times in ensembles of filaments which are bearing constant loads and then proceeds to calculate the distribution of lifetimes under other stress histories, e.g., loads increasing linearly with time and sinusoidal loads. The a priori assumptions used here permit a calculation of the dependence of observed tensile strengths on both the sample size and the rate of loading. Experiments involving drawn 66 nylon monofilament yarn are cited to illustrate how the parameters which describe the average lifetime under dead load behavior of a yarn may be used to calculate its tensile strength distribution when measured with a constant rate of loading apparatus.
Flow of Immiscible Fluids in Porous Media: Exact Solution of a Free Boundary Problem
Authors: Kidder Ray E.
Published: April 2005

A mathematically exact solution is obtained of a two-dimensional free boundary problem arising in the flow of two immiscible fluids in porous media. The particular problem dealt with concerns the ``fingering'' of water toward a line of equally-spaced oil wells that penetrate a thin, dipping sand. The solution is obtained by use of the hodograph plane and complex variable theory.
Motion of Electrons and Holes in Photographic Emulsion Grains
Authors: Hamilton J. F. , Hamm F. A. , Brady L. E.
Published: April 2005

The use of simultaneous pulses of light and voltage to study the motion of electrons and holes in photographic grains and the role played by these charge carriers in the formation of the latent image is discussed. The electric field displacement of conduction electrons forming print-out as well as latent-image silver is shown by electron micrographs of the grains. Also, results on the motion of positive holes are presented. It is possible to show at the print-out level that this carrier is mobile; although it may be that the hole is displaced at the latent-image level, this behavior has not been demonstrated. The light and voltage pulses used for the exposures are analyzed and related to electron displacement. Indications are that when electrons are forced to the grain surface by an electric field, they are trapped in a time less than 1 μsec.
Charged Right Circular Cylinder
Authors: Smythe W. R.
Published: April 2005

A new method permits the calculation of the electric field surrounding a charged conducting surface of revolution without the use of orthogonal functions. Detailed formulas show how to find the charge density on a right circular cylinder with any desired precision. The numerical examples worked out give the maximum deviation of the actual surface from that of a true cylinder of diameter d to be −0.0015d, −0.00037d, −0.00017d, +0.0016d, and +0.014d for length to diameter ratios ¼, ½, 1, 2, and 4, respectively. The capacitance calculation gives an accuracy of one part in 30 000 for the ratios ½, 1, and 2. A capacitance formula is worked out which is accurate to one part in 1000 over the ratio range 0 to 4. Additional formulas indicate the method of solution for the bodies in longitudinal and transverse electric fields and the extension of two-body problems such as the thick plate parallel plate capacitor. A way to calculate the flow about bodies of revolution is indicated. Digital computers are well suited to this method as no function tables are needed.
Controlled Field Emission in Hexane
Authors: Green W. B.
Published: April 2005

The current-voltage relationship for dielectric liquids consists of two portions, usually in superposition: at lower voltages a current of ions flows; at higher voltages, field emission sets in. The field-emission current depends on the material of the cathode, but not simply on its work function. The current may be altered by changing the thickness of the cathode surface layer or the gas adsorbed upon the surface. When the ion content of the liquid is raised, not only the ionic current, but also the field-emission portion of the current increases.

Controlled field-emission currents have been produced.
Excitation and Separation of Pure High-Order Modes in Large High-Q Cavities
Authors: Zahn C. T. , Schweitzer W. G.
Published: April 2005

In order to extend the range of cavity resonance techniques a successful method has been developed for the suppression of undesired modes of a densely populated cavity spectrum. It is based on the nodal properties of the usual simple solutions of the wave equation. The analytic continuation of any such solution may be regarded as a master mode pattern which defines an infinite variety of elementary cavities or cells all having one frequency in common. These properties provide the basis for a novel principle in the design of cavity-coupling systems. By suitable choice of a ``complex'' of these elementary cells, devices can be obtained with remarkable transducing, filtering, or suppressing properties. An experimental test of the foregoing ideas has been made in which it was possible to excite a well-separated very high order TE0mν mode in a large cylindrical cavity, at a frequency of 20 000 Mc. The observed Q for this preferred mode was of the order of one million. As an additional test quantitative experiments have been performed on a special type of complex cavity in which the number of elementary cells could be varied.
Switching Time in Ferroelectric BaTiO3 and Its Dependence on Crystal Thickness
Authors: Merz Walter J.
Published: April 2005

The switching time ts and the switching current imax have been measured as a function of applied field E and of the size of the sample. It has been observed that the ``activation field'' α for the nucleation of new domains is inversely proportional to the thickness of the sample. This behavior can be explained by assuming a surface layer. The thickness of this layer has been calculated to be of the order of 10−4 cm. The same way we can explain the thickness dependence of the 60-cycle coercive field strength. Furthermore, it has been found that the switching time depends to a first approximation linearly on the thickness of the sample if the field E is kept constant. This can be explained by assuming a domain wall motion primarily in the forward direction or by assuming a nucleation mechanism. The maximum velocity of the domain growth was found to be of the order of the velocity of sound. The switching time does not depend on electrode area.
Optimum Rocket Trajectories
Authors: Fried Burton D. , Richardson John M.
Published: April 2005

Some general considerations regarding maximum range missile trajectories are presented. It is shown that under certain simplifying assumptions maximum range is achieved if the thrust attitude angle is held constant during the entire powered flight. This result is exact for a constant gravitational force field if aerodynamic forces and altitude dependence of rocket thrust are neglected. For motion in the earth's inverse square, central force field, constant thrust attitude is a good approximation to the optimum program, provided the distance covered during powered flight is small compared to the radius of the earth. Equations for the value of the optimum attitude angle are presented for both constant and Kepler force fields. The results provide a convenient means of estimating an upper limit for the range which could be achieved with a given missile.
Detailed Structure of Copolymers from Dielectric Measurements
Authors: Work Richard N. , Tréhu Yves M.
Published: April 2005

The effective dipole moment of each polar group in polar-polar or polar-nonpolar copolymers is expressed in terms of the moment of an equivalent isolated polar group and the average of the vector sum of the moments of all of the polar groups surrounding it. If effects of short-range forces leading to angular correlations of dipole pairs are neglected except for interactions between nearest neighbors along the chain, an expression for the average of the effective moments of the two types of polar groups present can be written as a function of the composition of the copolymer in the form 〈μ2〉Av=x1(μ12)eff+(1−x1)(μ22)eff=L+Mx1+Nx1P11(x1). Here, x1 is the mole fraction of one of the monomers in the copolymer, (μ12)eff and (μ22)eff are the squares of the effective moments of the two polar groups. L, M, and N are constants involving the dipole-moments of the equivalent isolated groups and the average cosines of the angles between nearest-neighboring dipole pairs of types 1 − 1, 1 − 2, and 2 − 2. The quantity P11(x1) is the probability of a monomer of type 1 adding to a free radical of its own kind at the end of a growing chain in the polymerization mixture. It can be calculated from r1 and r2, the reactivity ratios of the two monomers, and the composition of the monomer feed mixture. Interactions extending farther along the chain than nearest neighbors introduce terms in higher powers of P11(x1).

Onsager's equation for the dipole moments of molecules in mixtures of polar liquids has been modified to express the average of the effective moments of the polar groups present in terms of the dipolar contribution to the dielectric constant, εs−ε∞. Using this equation, values of 〈μ2〉Av have been calculated from measurements of εs−ε∞ for several copolymers of poly-(p-chlorostyrenestyrene) representing the whole range of copolymer composition. Measurements were made on bulk copolymers at temperatures above the glass-transition temperature. A curve of the form L+Mx1+Nx1P11(x) has been fit within experimental error to the calculated values of 〈μ2〉Av over the whole range of copolymer composition. This indicates that within the limits of error of this work only nearest-neighbors on the polymer chain contribute to the effective moments of the polar groups. The average cosines have been calculated for the angles between each of the three kinds of dipole pairs in the copolymer.
Radiation Induced Conductivity in Polyethylene and Teflon
Authors: Meyer R. A. , Bouquet F. L. , Alger R. S.
Published: April 2005

The conductivity induced in polyethylene and Teflon by bombardment with x-rays from a 2-Mev Van de Graaff and gamma rays from Co60 has been investigated as a function of time, temperature, geometry, exposure rate, and applied electric field. Within the range of the variables studied, the observed photocurrents were directly proportional to the exposure rate and the applied electric field. The photocurrent could be divided into three components, the current due to the action of monodirectional photons, the increase in this current due to the influence of the electric field, and a component of less than 10% made up of all other possible charge carriers. During irradiation, the conductivity increased by a factor of about 103. Between 78°K and 273°K the photocurrent was nearly independent of temperature. In general, the conductivity of Teflon was greater than that of polyethylene.
Transit Time Transistor
Authors: Weinreich Gabriel
Published: April 2005

It is shown that, by utilizing transit-time effects, an appropriately designed transistor can be operated as a three-terminal amplifier in certain special frequency bands which lie far above the α-cutoff frequency. The criteria for the existence of such frequency bands are similar to those for the existence of a negative-resistance band when the structure is operated as a diffusion delay diode; if such a negative-resistance band exists, there are also two narrow bands, one on each side of it, where transit-time transistor action is available. The existence of these bands is in general independent of the magnitude of the base resistance, but their width decreases with increasing base resistance.
Instability in Hollow and Strip Electron Beams
Authors: Cutler C. C.
Published: April 2005

A thin strip or hollow electron beam drifting in a magnetic field directed parallel to the direction of motion is in an unstable condition. As a result of initial nonuniformities the beam breaks up into a series of ``spiral nebulae.'' This paper is written to describe some experimental observations which are of help in understanding the phenomenon, and to show that it can be applied to give useful amplification.
Surface Film Formation and Metallic Wear
Authors: Hirst W. , Lancaster J. K.
Published: April 2005

The interactions between surface asperities which occur during sliding are of primary importance in both friction and wear. In consequence, many of the phenomena observed during investigations into the nature of friction should have their counterpart in wear. An experimental study is described of the way in which wear is affected by factors already known to influence friction. It is shown that when a relatively soft metal slides on a harder one, the relationship between the wear and the sliding distance may be one of three general types. Each type is associated with the formation of a surface film during sliding. The extent to which these films (oxide, adsorbed boundary lubricant, etc.) prevent intermetallic contact influences the relationship between the wear rate and the applied load. With several metals there is a discontinuity in the wear rate-load relationship, and two distinct regimes of wear are obtained. The transition between these two regimes is associated with the breakdown of a protecting surface film. Finally, it is suggested that the generation of protective surface films during sliding comprises an essential part of the ``running-in'' process of machinery.
Effect of Strain Rate on the Propagation of a Plastic Strain Pulse Along a Lead Bar
Authors: Alter B. E. K. , Curtis C. W.
Published: April 2005

Tests have been carried out to determine how pulses of plastic deformation disperse during propagation along a lead bar. Step function loading was employed in order to avoid complications resulting from the presence of relief stresses. By using a double pressure step technique, it was shown that the dispersion cannot be due solely to the nonlinearity of a time-independent stress-strain relation. On the other hand even a very simple model of a metal exhibiting a strain-rate effect serves to predict qualitatively all of the main features of the experimental observations. It is therefore concluded that in the case of lead a strain-rate effect plays an important part in controlling the behavior of a plastic strain pulse.
Scattering of a Plane Longitudinal Wave by a Spherical Obstacle in an Isotropically Elastic Solid
Authors: Ying C. F. , Truell Rohn
Published: April 2005

Scattering by a spherical obstacle of a plane longitudinal wave propagating in an isotropically elastic solid is computed. Expressions for the scattered wave and the total scattered energy are given. Three special types of obstacle—an isotropically elastic sphere, a spherical cavity, and a rigid sphere—are discussed in detail, especially for Rayleigh scattering. The result for the isotropically elastic sphere is compared with the well-known result of scattering of a plane wave propagating in an ideal fluid by a sphere of another ideal fluid.
Birefringence Changes During Retraction of Oriented Polystyrene Monofilaments. II. Changes in Radial Distribution of Birefringence
Authors: Rudd J. F. , Andrews R. D.
Published: April 2005

The radial distribution of birefringence, Δ(r), has been measured in Filament # 16 at a series of time values up to 600 hrs, during retraction at 85°C. The birefringence distribution was obtained by cutting wedges on the end of the filament samples and analyzing the optical interference pattern down the center line of the wedges, under a polarizing microscope. The rates of birefringence decay at different points along the radius are not the same, or even proportional; the interrelationship is apparently fairly complex. Birefringence values near the center of the filament change from negative to positive sign in the long-time region, while values near the exterior surface remain negative throughout. Values of the diameter average birefringence calculated from Δ(r) are in close agreement with values obtained from direct experimental measurement. A cross-sectional-area average birefringence was also calculated from Δ(r); this quantity decreases monotonically toward zero, with no transition to positive values in the long-time region, and therefore corresponds more closely than the diameter average birefringence with the observed length changes. The area average is nearly proportional to the diameter average, however, except for values near zero.
Study of Atomic Structure of Metal Surfaces in the Field Ion Microscope
Authors: Müller Erwin W.
Published: April 2005

Details of the image formation in the low temperature field ion microscope are discussed. The hopping height of the rebounding gas atom, which depends on the atom's polarizability, the tip temperature, tip radius, and field, is significant for the resolution. Photographs of tungsten and rhenium surfaces with the atomic lattice resolved and in different states of disorder are presented. A color printing technique, which permits finding quickly a few displaced atoms among the many thousand that are visible, is described.
Note on Cavity Perturbation Theory
Authors: Spencer E. G. , LeCraw R. C. , Ault L. A.
Published: April 2005

A criterion is presented for the applicability of cavity perturbation theory for measuring permeabilities and dielectric constants of materials. In the literature, the perturbation criterion is usually stated as: the rf fields in the cavity with and without the sample are approximately equal. This is the same as stating that changes in the stored energy in the cavity, upon introduction of the sample, are small. This criterion is shown to be too strong, and usually violated in experiments. A weaker but sufficient criterion, for all commonly encountered Q values, is that changes in the over-all geometrical configuration of the rf fields must be small upon introduction of the sample. Experimentally, this means that for small sample measurements only the percentage change in the real part of the frequency must be small. Data are presented to demonstrate the above ideas.
Excess Surface Currents on Germanium and Silicon Diodes
Authors: Eriksen W. T. , Statz H. , DeMars G. A.
Published: April 2005

The investigation of excess currents on silicon and germanium diodes has shown that inversion layers give an approximate logarithmic increase of excess current with applied voltage. Approximately ohmic excess currents are observed not only in the presence of water vapor but also in the presence of vapors of certain organic liquids. These excess currents can be shown to be due to a surface conductance which has a different bias voltage dependence from that exhibited by inversion layers. Evidence is presented which indicates that the holes induced in the liquid film (outer surface states) move in an applied field much like holes in a molten semiconductor, provided the liquid film is coherent. This added conductance is responsible for the ohmic behavior in the presence of condensable vapors.