bluuebunny/crossref_metadata_2025 huggingface dataset:
Stability of the Low Pressure Mercury Arc as a Function of Area at the Cathode Pool
Authors: Lufcy Carroll W. , Copeland Paul L.
Published: January 2005

Using the method of Copeland and Sparing, the duration of an arc has been observed under fixed operating conditions a sufficient number of times to give a satisfactory estimate of the average life. The results show that the average life increases as the area of the cathode pool is reduced, and that the rate of change is particularly rapid for low arc currents.
The Production and Decomposition of Ozone by Low Pressure Mercury Vapor Lamps
Authors: Koller L. R.
Published: January 2005

A photo-tube method for measuring the concentration of ozone is described. Measurements were made of the rate of production and rate of decomposition of ozone in oxygen and in air by low pressure mercury vapor lamps. The production in oxygen is enhanced by the presence of nitrogen. Increasing the moisture content of the gas decreases the rate of production and increases the rate of decomposition. A new germicidal lamp enclosed in a 10-liter glass tube will form an equilibrium concentration of 145 parts per million by volume. A quartz lamp under the same conditions will form 640 parts per million. With oxygen flowing through the tube the yield for the quartz lamp is 2.5×10−3 g ozone/min. or 10 g kw hr.
Flexural Vibration of Unrestrained Cylinders and Disks
Authors: Pickett Gerald
Published: January 2005

Solutions are given for the free flexural vibration of a cylinder vibrating as a rod would vibrate and for the free flexural vibration of a disk vibrating as a circular plate would vibrate. The solutions are based upon the mathematical theory of elasticity. Curves are given showing the correction factors which, when applied to the elementary solutions, will give results in agreement with those obtained by means of the more rigorous solutions given here.
Strain Hardening Under Combined Stresses
Authors: Prager W.
Published: January 2005

Experimental investigations of the strain hardening of metals under combined stresses are usually conducted so that the directions of the principal stresses as well as the ratios of their magnitudes remain constant during any one test. The paper is concerned with incompressible isotropic materials which are stressed in this manner and deform in accordance with certain postulates. The most general stress-strain relation which can arise under these circumstances is established, and some special cases of this relation are discussed.
Data on Rate of Capillary Rise
Authors: LeGrand Elmo J. , Rense William A.
Published: January 2005

General aspects of the dynamics of capillary rise are considered with references to extant theories. A stroboscopic method used to study the rise of a liquid in a capillary tube is discussed. Tables are presented showing the observed heights at various times during the rise for the liquids—water, ethyl alcohol, and glycol in each of three capillaries of different diameters.
Sustained Subharmonic Response in Non-Linear Series Circuits
Authors: Spitzer Charles F.
Published: January 2005

This paper presents an experimental analysis of oscillatory current responses peculiar to certain types of non-linear series circuits containing resistance, inductance, and capacitance. Methods of initiating the oscillations, and the effect of the boundary conditions necessary to sustain them, are summarized. This is followed by a discussion reviewing the effect of resistance and capacitance variation on sustained subharmonic response. For several values of capacitance, the effect of varying the inductor turns is presented in the form of curves. These curves are correlated in a plot of effective value of impressed voltage versus the product N2C1.5 (N is the number of turns on the inductor core, and C is the capacitance). The voltage across the inductor appears to consist of only two sinusoidal components, when the circuit undergoes subharmonic oscillations.
The General Theory of Stresses and Displacements in Layered Systems. I
Authors: Burmister D. M.
Published: January 2005

The problems of airport and foundation engineering have become increasingly important in the war construction program. These problems frequently involve the consideration of stresses and settlements in layered soil deposits. The well-known Boussinesq equations apply strictly only to homogeneous soil deposits. The general theory of stresses and displacements in a twolayer system is developed in order to provide the engineer with a useful tool which is more directly applicable to the analysis of actual conditions encountered in soil deposits. The basic equations of stresses and settlements are derived. The numerical evaluation of the surface settlement equation for the simplest case of Poisson's ratio equal to one-half has been completed as the first of a series, and is presented in the form of influence curves for the analysis of practical problems.
The Use of the Electron Diffraction Camera to Detect Insulating Films
Authors: Alessandrini Eileen I.
Published: January 2005

Electron diffraction offers a solution to the problem of distinguishing between conducting and insulating surface films on conducting objects. An electron beam striking an insulating surface behaves in a different manner than with a conducting surface because of a charging up of the insulating surface. This enables the observer to recognize an insulating film on the surface of a sample.
A 100-kv Electron Microscope
Authors: Marton L.
Published: January 2005

In this paper a transmission type electron microscope with magnetic lenses is described. The electron speed can be varied between 30 ekv and 100 ekv. The magnification of the instrument is produced in three stages. The instrument has improved air locks, hydraulically operated stage movement, and a stage tilting device up to ±15½°. It is also provided with means for bright and dark field illumination and for conversion into a diffraction camera. Improved electrical circuits provide the necessary stability of the power supplies.
Solution of the Diffusion Equation Applicable to the Edgewise Growth of Pearlite
Authors: Brandt W. H.
Published: January 2005

The diffusion equation is transformed to a set of coordinates moving with the pearlite interface and a solution applicable to the problem obtained in the form of an infinite series of terms. Using the first three terms, the edgewise velocity of pearlite growth is calculated for a plain carbon eutectoid steel using data most of which are obtained by extrapolation. The values obtained show reasonable agreement with values for the rate of pearlite nodule growth determined by Hull, Colton, and Mehl. The velocity increases with decreasing temperature, as expected, and it is shown that this is caused by the change in the solubilities of ferrite and cementite in austenite with temperature. The theory predicts curved ferrite-austenite and cementite-austenite interfaces and the carbon concentration in austenite is shown to vary across each of these interfaces.
The Production Histories of Oil Producing Gas-Drive Reservoirs
Authors: Muskat Morris
Published: January 2005

A theory has been developed for predicting the behavior of solution gas-drive oil producing reservoirs, on the basis of previously established empirical laws on the flow of heterogeneous fluids through porous media. Treatments are given both for the simple pressure depletion history without gas injection, and those for systems in which gas is injected during the course of oil production. The specific results provided by the theoretical analysis include the ultimate oil recovery, and the pressure decline, gas-oil ratio, and productivity factor histories. Two types of gas injection have been considered, namely: (1) that in which the returned gas is supposed to diffuse through and be produced continuously with the oil zone; and (2) that in which the injected gas remains locked in the gas cap, which merely expands as oil production and gas injection proceed. In the latter case the rate of growth of the gas cap is also obtained as a function of the cumulative oil recovery.

The theory is illustrated by numerical application to a hypothetical virgin oil reservoir with an original pressure of 2500 p.s.i. producing by gas-drive, and with no initial gas cap. It is so found that if no gas is injected into the system the physical ultimate oil recovery will be 14.5 percent of the pore space, or 27.1 percent of the original stock tank oil content, assuming that the formation initially has a connate water saturation of 30 percent. The gas-oil ratio first declines as production is started, then rises sharply to a maximum of 4400 cu. ft./bbl., and finally falls steeply as the pressure is depleted to atmospheric. If there is no gas segregation and 60 percent of the produced gas is returned to the formation, the ultimate oil recovery will be increased by 27.6 percent. The gas-oil ratio history will be similar to that with no gas injection, but will rise to a maximum of 10,300 cu. ft./bbl. If 80 percent of the gas is returned, the recovery increase will be 48.8 percent, the maximum in the gas-oil ratio history reaching a value of 19,450 cu. ft./bbl. If all the gas is returned, the gas-oil ratio rise will be so rapid that by the time 20,000 cu. ft./bbl. is reached only 23.5 percent additional oil will be recovered. During these operations the productive capacities of the wells will fall by factors of the order of 10, because of the increasing viscosities of the oil and decreasing permeabilities to the oil, as the pressure declines and the oil saturation decreases.

For the case where the gas remains trapped in the gas cap, the ultimate oil recovery will be 163 percent greater than by direct pressure depletion, if the residual oil after gravity drainage is 15 percent of the pore space. This recovery will be essentially independent of the amount of gas return, although the final reservoir pressure at the time of complete gas cap expansion will be greater as more gas is returned. The increased oil viscosity and decreased permeability to the oil will here reduce the specific production capacities of the wells to ¼ or ⅓ of their initial values.
The Effects of Temperature and Humidity on the Physical Properties of Tire Cords
Authors: Dillon J. H. , Prettyman I. B.
Published: January 2005

Apparatus by means of which tire cords may be conditioned and tested at elevated humidities (1.6–65 percent R. H.) and temperatures (20–165°C) is described. The apparatus consists of a portable conditioning unit which is used with a standard tensile testing machine. Equipment for measuring creep of tire cords under dead load at elevated temperatures is also described. Five representative types of tire cord were employed in the experiments, medium stretch cotton, low stretch cotton, viscose rayon, Fortisan, and Nylon. Tenacity, ``10 pound-stretch,'' and ultimate stretch are studied as functions of relative humidity, temperature, and moisture regain. It is shown that the tensile properties are best represented as functions of temperature at constant regain. The tenacity of viscose rayon cords decreases with increasing temperature at constant regain in the range of regains 0–5 percent. The tenacity of the medium stretch cotton cords at constant regain falls off with increasing temperature in the range of 20–100°C and then changes very little up to 165°C. That of the low stretch cotton cords, however, decreases in a manner similar to that found for rayon. The Fortisan cords show a decrease of tenacity in the range 20–100°C and then a slight increase for higher temperatures. The cotton, rayon, and Fortisan cords give nearly linear creep curves (elongation vs. log time) in the range of creep times 0.002 to 20 hours. The creep curves for Nylon show a tendency to increase in slope at extended creep times. The creep data are analyzed in terms of two arbitrarily defined indices, ``initial compliance'' and ``weighted creep.'' Both the tensile and creep characteristics are discussed from the viewpoint of current theories of structure and also in the light of their relations to serviceability in tires.
Numerical Solution of Ordinary and Partial Differential Equations by Means of Equivalent Circuits
Authors: Kron Gabriel
Published: January 2005

Numerical methods are developed to solve certain types of linear and nonlinear partial differential equations to any desired degree of accuracy with the aid of equivalent electrical networks. The methods of solution of ordinary differential equations, both linear and nonlinear, follow as special cases. Three types of problems are considered:

1. Initial-value problems. If the field quantities are known along a surface, the networks may be solved by a straight-forward step-by-step calculation. The networks may also be looked upon as supplying a ``schedule'' of operations that can be put on a digital calculating machine.

For time-varying problems new types of networks are developed in which time appears as an extra spatial variable. Examples of new networks for the elastic field and for the general nonlinear wave equation are given. Sample calculations and theoretical checks of a transient heat flow problem and of an ordinary differential equation are also included.

2. Boundary-value problems. Four methods of solution are given, the first three being cut and try processes. (a) The method of weighted averages; (b) The method of unbalanced currents and voltages; (c) The ``relaxation'' method; (d) The ``diffusion'' method, that changes the boundary-value problem into an initial-value problem by adding to the original partial differential equation a time variable of the form A∂φ/∂t, allowing the unbalanced currents to ``diffuse'' in time.

These numerical methods may also be used to improve the accuracy of the results found on the Network Analyzer. Examples of calculations are given for the electromagnetic and the elastic fields.

3. Characteristic-value problems. Their methods of solution are similar to those of boundary-value problems. An additional method of unbalanced admittances is also indicated. It is shown that by calculating the power in the network, the characteristic value of the assumed function is found.

An improved characteristic value of the linear harmonic oscillator, solved initially on a Network Analyzer, is calculated as an example.

In general the electrical networks may be used to check the consistency and correctness of solutions arrived at by other methods, approximate or exact. The unbalanced currents at the junctions (easily calculated) give a quantitative measure of the deviation from the correct solution.
Research in the Corps of Engineers
Authors: Schulz John W. N.
Published: January 2005

The highly mechanized character of World War II, its global nature, the extended lines of communication, the great destruction created in our path by demolition, artillery, and air bombardment, and the sweep and speed of movement of our forces, have imposed equipment demands on the Army Engineers unheard of in any previous war. The principal field agency of the Chief of Engineers for carrying out the work of research and development pertaining to this equipment is the Engineer Board, located at Fort Belvoir, Virginia. In presenting the following article, the President of the Engineer Board desires to acknowledge the assistance given by various members of the Board staff, as well as by the Office of the Chief of Engineers, in preparing this story of Corps of Engineers research and development.
Mechanics of the Metal Cutting Process. I. Orthogonal Cutting and a Type 2 Chip
Authors: Merchant M. Eugene
Published: January 2005

An analysis of the chip geometry and the force system found in the case of orthogonal cutting accompanied by a type 2 chip has yielded a collection of useful equations which make possible the study of actual machining operations in terms of basic mechanical quantities. The shearing strain undergone by the metal during chip formation, and the velocities of shear and of chip flow are among the geometrical quantities which can be quantitatively determined. The force relationships permit calculation of such quantities as the various significant force components, stresses, the coefficient of friction between chip and cutting tool, and the work done in shearing the metal and in overcoming friction on the tool face. The experimental methods by which such analyses can be readily made are described. Observed and calculated values from typical tests are presented.
Optimum Height of Flight of Winged Rocket- or Jet-Bomb
Authors: Krzywoblocki M. Zbigniew L.
Published: January 2005

The purpose of this note is to present the formulae for calculation of optimum height of horizontal flight of winged rocket- or jet-bomb in an elementary way. First, the elementary principles of rocket-propulsion are given, i.e., the momentary coefficient of external efficiency, which represents the part of the total energy of the propulsive material imparted to the rocket, the mass of the rocket after a certain time, the actual acceleration and the average acceleration of the rocket, and the average coefficient of external efficiency over a certain period of time. Next, the horizontal flight of a rocket in atmosphere at a certain height is considered and the formulae for the optimum height of flight are derived in two cases: (a) constant velocity of flight, (b) constant mass of the outflowing gases. The calculations refer to the case of adiabatic flow in the nozzle but may be applied easily to the case of any polytropic flow. The considerations are repeated in the same order for jet-propulsion. The formulae are derived under the simplifying assumption that the difference in pressures in the wake behind the bomb in flight-in which the pressure is smaller than in the free air-and in the free air may be disregarded, since it is assumed that at the mouth of the nozzle the pressure equals the pressure in the free air. The difference between rocket- and jet-propulsion is presumed to be known. In the former type of propulsion the propulsive material contains in itself the oxygen necessary for the combustion process, while in the latter the oxygen is taken from the outside air. The type of propulsion in which oxygen is contained, separately from the fuel, within the rocket in a compressed or liquid state, should be included in the rocket group.
Deflection Sensitivity of Parallel-Wire Lines in Cathode-Ray Oscillographs
Authors: Rudenberg H. Gunther
Published: January 2005

The deflection angle θ of a cathode-ray beam accelerated by a potential V is shown to be proportional to the linear charge density ρ transverse to the beam on the interior of the electrostatic deflection system, θ=ρ/2Vε0. The voltage deflection sensitivity depends on the plate-to-plate capacitance c per unit width, θ/E=c/2Vε0. This includes edge effects and permits a determination of the sensitivity from capacitance measurements or a simple graphical evaluation from the dimensions of the deflection system. The use of parallel-wire lines as a deflection system is suggested, and its deflection sensitivity evaluated. Such lines have low transit time error and are either easily tuned, or can be operated non-resonant with resistive termination.
A Novel Form of Refrigerator
Authors: Roebuck J. R.
Published: January 2005

When a gas is allowed to flow out along the radius in a rapidly rotating enclosure, it is compressed and therefore heated. The enclosure may be supplied with a coil of pipe carrying a cooling liquid to remove the heat of compression as formed in the gas. On guiding the gas back to the axis, it is cooled by its own expansion, and a maximum ΔT of about 150°C occurs. The work of expansion is determined by the rotor demand, not by the gas temperature or by the gas volume change. Both warm and cold fluids enter and leave the enclosure axially. Analysis shows that the cooling, ΔT, is given by ω2r2/2Cp. The rotational energy of the enclosure is not drawn upon by the steady fluid flows. The cooling liquid moves convectively through its circuit but the gas must enter the enclosure at a pressure somewhat above that at exit. A possible mechanical design is sketched. Maximum peripheral speeds allow 19 cal./gram to be extracted from the gas flow giving for air a drop of 77°C from room temperature. This is more than sufficient for most commercial refrigeration. Use of a favorable gas in the rotor gives sufficient ΔT to be very effective in gas liquefaction. Rotors may have their flows in series to increase the ΔT, and the gas may be at a supercritical pressure to keep it homogenous till released from the pressure. The device is expected to have high efficiency as a refrigerator. By utilizing the rejected heat, as Kelvin suggested, the device may be used for domestic heating.
The General Theory of Stresses and Displacements in Layered Soil Systems. III
Authors: Burmister D. M.
Published: January 2005

The theory of stresses and displacements for layered soil systems is extended in this paper to cover the more general case of three layers with full continuity across the interfaces between the layers. The three-layer system gives a closer approximation to the actual soil conditions encountered. Only the settlement equation at the surface of the ground is derived at this time, because it has a more direct application to the practical problems of foundation and airport engineering.
Stability of Low Pressure Mercury Arcs as a Function of Current
Authors: Copeland Paul , Sparing W. H.
Published: January 2005

The persistence of an arc in an experimental tube with a pool type cathode has been studied. The mean life under carefully controlled operating conditions is determined by statistical analysis of a hundred or more observed lives and is taken as a measure of the stability. The dependence of mean life upon both the ambient temperature of the cathode pool and the current is determined. The arc is found to be most stable at an optimum ambient temperature. In the first observations the cathode spot was free; later observations were made with the cathode spot anchored in contact with a tungsten film. In both cases the results indicate that the mean life rises exponentially with the arc current in the ranges used. If I represents the arc current and L represents its average duration, the results suggest a relationship of the form L=F(p,x,y,z,…)exp (kI),where F stands for some functional relationship depending on the mercury vapor pressure p calculated from the ambient temperature, and upon other parameters such as x, y, and z, at present undetermined. For the proportionality constant k, the data give (2.46±0.06) ampere−1 when the cathode spot is free and (19.92±0.47) ampere−1 when the cathode spot is anchored. F(p, x, y, z, …) appears to be smaller with the cathode spot anchored than with it free, but the probable error in the function is relatively large.
Mechanics of the Metal Cutting Process. II. Plasticity Conditions in Orthogonal Cutting
Authors: Merchant M. Eugene
Published: January 2005

The analysis of the mechanics of orthogonal cutting with a type 2 chip as presented in the first paper of this series can be extended by introducing those physical properties of the work material which control its plastic behavior. One evident plasticity condition is the equality of the shear stress on the plane of shear to the shear strength of the metal. If it is also assumed that the shear strength of the work material is a constant and is the only quantity controlling its plastic behavior, then a very simple additional plasticity condition is obtained by application of the principle of minimum energy. This condition is 2φ+τ−α=90°, where φ is the shear angle, τ the friction angle, and α the rake angle. This condition, however, is found by experiment to be a poor approximation in the case of polycrystalline metals. A very good approximation is obtained, though, if use is made of the fact that the shear strength of the polycrystalline metal is actually a function of the compressive stress on the shear plane. The resulting plasticity condition is cot (2φ+τ−α)=k, where k is the slope of the linear curve relating shear strength and compressive stress, and is thus a constant of the work material.

Such a plasticity condition establishes a relationship between the force system and the geometry of chip formation, so that, if k and the shear strength be known for a given material, all forces involved in cutting it can be calculated with reasonably good accuracy directly from measurements of chip geometry only, without use of a tool dynamometer. This is of importance in the analysis of practical machining operations.
The Frictional Properties of Some White Metal Bearing Alloys: The Role of the Matrix and the Hard Particles
Authors: Tabor D.
Published: January 2005

A previous paper has described an investigation of the frictional properties of alloys of the copper-lead type which consist of a hard matrix (copper) in which are dispersed particles of a soft material (lead). It was shown that these alloys function by the extrusion and smearing of the soft phase over the hard matrix, so providing metallic-film lubrication. This paper describes experiments on a typical lead-base bearing alloy which consists of a soft matrix in which are dispersed numerous hard crystallites. Measurements of the friction were made at room temperature and at elevated temperatures for clean and for lubricated surfaces. Comparison with a special alloy consisting of the matrix material alone, showed that the hard particles played no appreciable part in the basic frictional and wear properties of the bearing alloy. It is suggested that the frictional behaviour of the bearing alloy is determined essentially by the properties of the matrix material itself although in practical running operations there may be other properties which determine the suitability of the alloy for use in bearings. Similar experiments are described on a typical tin-base bearing alloy and a corresponding tin-base ``matrix'' alloy.
A High Temperature, High Pressure Rheometer for Plastics
Authors: Nason H. K.
Published: January 2005

A modified Bingham-type rheometer, designed for operation at temperatures up to 500°F and at pressures up to 2000 p.s.i. is described. Interchangeable orifice plates permit wide variation of shear conditions. With this instrument flow properties may be studied under conditions approximating those encountered in the actual processing of thermoplastics, e.g., by molding or extrusion. Typical results are presented for cellulose acetate, polystyrene, and polyvinyl resin plastics, and correlation with practical experience is pointed out. The instrument is slow, and this limits its usefulness for other than research investigations.
The Relationship Between the Rheological Properties and Working Properties of Printing Inks
Authors: Buchdahl Rolf , Thimm Joan E.
Published: January 2005

It is shown that the working properties of a printing ink, i.e., its performance during the printing operation, can be interpreted in terms of the rheological properties as measured in a rotational viscosimeter. The instrument used in this investigation is a viscosimeter of the Stormer type. Data are presented to show that it is necessary to distinguish between time-dependent and time-independent flow phenomena. Various theories suggested to explain the time-independent flow phenomena are discussed briefly. The flow of a printing ink over the main mechanical elements of a typographic printing press is analyzed and correlated with simple flow phenomena which can be measured in a rotational viscosimeter.
Electromagnetic Field Inside a Cylinder with a Gap
Authors: Wang C. C.
Published: January 2005

Complete equations below the lowest cut-off frequency of transverse magnetic type relating the high frequency electric field and magnetic field inside a metallic cylinder excited through a gap and an assumed field at the gap are developed. Curves are calculated based on the equations which can be used to estimate the relative field strength at different points inside the cylinder. Equivalent capacitance due to the energy storage in the cylinder can be calculated and used for estimating the resonant frequency of the associated cavity. The equations can be degenerated to an electrostatic form and used for electron optical calculations.
Convection Currents in a Porous Medium
Authors: Horton C. W. , Rogers F. T.
Published: January 2005

The problem is considered of the convection of a fluid through a permeable medium as the result of a vertical temperature-gradient, the medium being in the shape of a flat layer bounded above and below by perfectly conducting media. It appears that the minimum temperature-gradient for which convection can occur is approximately 4π2h2μ/kgρ0α D2, where h2 is the thermal diffusivity, g is the acceleration of gravity, μ is the viscosity, k is the permeability, α is the coefficient of cubical expansion, ρ0 is the density at zero temperature, and D is the thickness of the layer; this exceeds the limiting gradient found by Rayleigh for a simple fluid by a factor of 16D2/27π2kρ0. A numerical computation of this gradient, based upon the data now available, indicates that convection currents should not occur in such a geological formation as the Woodbine sand of East Texas (west of the Mexia Fault zone); in view of the fact, however, that the distribution of NaCl in this formation seems to require the existence of convection currents, and in view of the approximations involved in applying the present theory, it seems safe tentatively, to conclude that convection currents do exist in this formation and that the expression given above predicts excessive minimum gradients when applied to such a formation.
Pigment Dispersion Methods for Electron Microscopy
Authors: O'Brien H. C.
Published: January 2005

A method of preparing a pigment dispersion for electron microscopy is described, wherein the pigment, such as zinc oxide, is first wet with water and is then dispersed in a solution of cellulose acetate. Another method is described in which mechanical or chemical damage of the particles is avoided by the use of an electrostatic dispersion apparatus.
A Comparison of Some Elastic Properties of Tire Cords
Authors: Wakeham Helmut , Honold Edith , Skau Evald L.
Published: January 2005

Additional information concerning the elastic properties of tire cords is needed since the present criteria involving breaking strength and elongation are considered insufficient to enable prediction of tire cord performance. The elastic behavior of Nylon, of rayon, and of unstretched and stretched cotton tire cords are compared with respect to their rates of elongation during measurement of the stress-strain curves and their elongation under static loads at various temperatures between 25° and 200°C. Elongations under the influence of cyclic loads are shown for cotton and rayon cords, and an apparatus for determining mechanical hysteresis of tire cords during cyclic loading is described. The temperature and moisture content of the cord are shown to have considerable effect upon its elastic properties.
On the Distribution of Current along Asymmetrical Antennas
Authors: Harrison Charles W.
Published: January 2005

In Part I a theoretical discussion is presented concerning the distribution of current along a grounded vertical antenna which is driven at an arbitrary point. In Part II the problem of the asymmetrical dipole is formulated.
Correction of X-Ray Diffraction Intensities for Lorentz and Polarization Factors
Authors: Buerger M. J. , Klein Gilbert E.
Published: January 2005

In crystal structure determination, it is necessary to apply corrections for Lorentz and polarization factors to the intensities of the x-ray diffraction spectra. Such corrections usually appear to take complicated form. It is shown that Lorentz factors can all be reduced to the comparatively simple form, L=(1/S)·(1/sin Υ), where S is a scale factor, constant for a particular recorded level of the reciprocal lattice, but differing in form depending on the method of recording. The factor can be eliminated from subsequent computation of corrections by proper timing of the photographs of the levels of the reciprocal lattice, and then all photographs have the same simple Lorentz correction, namely sin Υ. The polarization factor, on the other hand, depends only on the reciprocal lattice coordinate, σ, and is independent of method of recording. Six tables are provided for simplifying the routine computation of Lorentz and polarization corrections, and the methods advocated for correction are illustrated by examples.
Techniques for Evaporation of Metals
Authors: Olsen Leonard O. , Smith Charles S. , Crittenden E. C.
Published: January 2005

Thirty-four elements have been observed for evaporation behavior, the results being summarized for each element and the best techniques then listed in Table I. Heaters studied fall into two general classes, wires and crucibles. Tungsten, iron, nickel, and chromel wires were used and these were formed into close wound conical baskets and helical coils. Each element was studied for evaporation behavior from as many of these forms as was possible. Alundum and BeO crucibles formed by painting suspensions of these materials on a tungsten conical basket followed by baking at a high temperature were exceptionally satisfactory heaters for almost all of the elements studied. These crucibles served well for the evaporation of metals whose evaporation temperatures approached 2000°C as well as for those with lower evaporation temperatures.

The 18-inch evaporation system was designed and constructed along fairly standard lines. An externally operated, four-inch vacuum valve between the diffusion pump and the bell jar allowed air to be admitted to the bell jar without cooling the diffusion pump. This valve was an especially useful feature of the equipment.
Microwave Impedance Measurements with Application to Antennas. I
Authors: King D. D.
Published: January 2005

The problem of impedance measurement at centimeter wave-lengths is discussed with special reference to the practical aspects. The description of the various transmission-line methods available is supplemented by a detailed account of the apparatus and procedure used to determine the input impedance of a symmetrical antenna.
Wave Guides and the Special Theory of Relativity
Authors: Hershberger W. D.
Published: January 2005

The Lorentz transformation is applied to the H01 solution of Maxwell's equations used to describe wave propagation in conducting pipes of rectangular cross section. When group velocity for the wave is employed in the transformation, the solution obtained is that one characterizing wave-guide operation at cut-off frequency, thus demonstrating that the speed associated with power or signal transmission is group velocity. When phase velocity for the wave is employed in the transformation, and we treat all quantities appearing in the new solution as real, we find that the problem has been reduced to one in magnetostatics and the significance of this solution is pointed out. The use of the inverse Lorentz transformation to find wave guide solutions from known solutions of problems in statics is indicated.
A Discussion of the Illuminating System of the Electron Microscope
Authors: Hillier James , Baker R. F.
Published: January 2005

A practical means for estimating the average performance of an electron microscope is proposed. Some first-order theory of the operation of an electron-microscope objective is given to demonstrate the extreme sensitivity of the instrument to the adjustment of the illuminating system. It is shown that by considering the illumination as being produced by a two-lens system it is possible to explain qualitatively all the effects observed in practice in connection with the illumination of the specimen. Practical information regarding the exact adjustment of the illuminating system is also given. The cause and elimination of multiple images is discussed. Changes in the design of the electron source and the use of an interchangeable aperture in the condenser lens are shown to improve the average performance of the instrument considerably.
The Design of X-Ray Powder Cameras
Authors: Buerger M. J.
Published: January 2005

The x-ray diffraction tool in most common use is the powder camera, yet it is usually ill-designed. This paper presents constructive criticisms of current powder camera design, and describes briefly a series of instruments having desirable features. Among the issues discussed are: adjustments, recovery of adjustments, desirable diameters, important recording ranges, film arrangements, fitting the film to cylindrical form, design of direct beam systems, elimination of air-scatter, specimen attachment and adjustment, and scanning. The following special instruments are also discussed: high temperature cameras, large spacing cameras, and film cutters and punches.
Extension of the Beam Theory to Tapered Beams and Conical Shells
Authors: Beskin Leon
Published: January 2005

The object of this paper is to extend to tapered beams and conical shells (membranes) the conventional formulas of the beam theory. This extension is made for two conditions: the plane tapered beam and the thin conical shell. The method of solution and the results obtained in the two cases are essentially different. The general analysis of the conical shell leads to solutions which are more complex than the corresponding solutions for cylindrical shells. However, in the case of applied stress analysis, simplifications are possible, which lead to solutions of the same type as for cylindrical shells.
On Maximum Gain-Band Width Product in Amplifiers
Authors: Hansen W. W.
Published: January 2005

By introducing an electrostatic problem analogous to the impedance function problem it is found possible to prove that, under simple and quite broad assumptions, the maximum possible gain-band width products for two-terminal coupling, four-terminal low-pass coupling and four-terminal band-pass coupling are, respectively, 1, 2.47, and 2.53 times g/πC. The first result was conjectured by Wheeler long ago, and it and the second have recently been proved by Bode. The last result covers a case more general than those considered by Bode.
A ``Power Function'' for the Determination of Lagrangian Generalized Forces
Authors: Wells D. A.
Published: January 2005

The purpose of this paper is to present the development of a ``power function,'' P, such that Lagrangian generalized forces, Fqr, which stem from a wide variety of forces (as, externally applied, conservative, dissipative forces proportional to the nth power of speed, etc.) can be obtained from the simple relation: Fqr=∂P/∂q̇rThe value of this easily obtained function lies in the fact that it places the task of determining almost all generalized forces which occur in practice on the same basis as that of determining conservative forces from a potential-energy function. Moreover, it is equally applicable to mechanical, electrical, and electro-mechanical systems. Since it is believed that the function has wide applications, several of its most useful forms are listed. Two specific examples are given.
Three-Dimensional Fourier Transforms and Their Application to Maxwell's Equations
Authors: Adler F. T.
Published: January 2005

Boundary value problems in regions with rectangular symmetry can be treated by means of the finite Fourier Transform. Transforms of vector point functions and their divergence and curl are obtained. The transforms of Maxwell's equations take a particularly simple form; the resonator problem is discussed as an example.
On the Improvement of Resolution in Electron Diffraction Cameras
Authors: Hillier James , Baker R. F.
Published: January 2005

An electron optical system is described in which it is possible to obtain (1) high resolution electron diffraction patterns, (2) shadow electron microscope images, and (3) electron diffraction patterns of selected variable areas of the specimen. The change in mode of operation of the system is accomplished by electrical adjustments without changing the specimen position in any way. A number of phenomena related to the attainment of high resolution diffraction patterns are described. Pertinent details of the experimental apparatus are discussed and some representative results are shown.
Applications of Metallic Shadow-Casting to Microscopy
Authors: Williams Robley C. , Wyckoff Ralph W. G.
Published: January 2005

The factors which determine image contrast in optical and electron micrographs are discussed in relation to a new metal shadow-casting technique whereby the contrast of images is greatly increased by depositing obliquely a thin film of metal on the microscope preparations. Further advantages of the use of shadow-casting are described, and an estimate is made of the lower limit of size of objects which should be observable by shadow-casting. Examples are given and illustrations are shown of the applications of this technique to the electron micrography of particles of macromolecular dimensions, of replicas of such particles, and of surface replicas prepared in several ways.
The Electrical Resistance of Iron Wires and Permalloy Strips at Radiofrequencies
Authors: Smith Alva W. , Gregory J. H. , Lynn J. T.
Published: January 2005

The ratio of a.c. to d.c. resistances of iron wires and permalloy strips has been measured in the frequency range 1.5–6.0 megacycles per sec. Empirical equations obtained are compared with existing theoretical equations derived on the assumption of constant permeability.
Liquid Rise in a Capillary Tube
Authors: Brittin Wesley E.
Published: January 2005

A theory of the dynamics of capillary rise is developed by making certain assumptions as to the nature of the motion of the liquid in the tube. The most important assumptions are that the same forces act on the liquid when it is in an accelerated state of motion as when it is in a steady state, that the surface tension is constant, that the angle of contact between the meniscus of the liquid and the tube wall is constant, and that the wetting of the tube is not a rate-determining factor of the motion. This theory leads to a second-order non-linear differential equation, the solution of which represents the motion of the liquid in the tube. A formal solution of the differential equation is obtained in the form of a double Dirichlet series. Approximations to the series are compared with experimental data, and it is concluded that the agreement between theory and experiment is satisfactory.
Shunt and Series Sections of Transmission Line for Impedance Matching
Authors: Tai C. T.
Published: January 2005

The problem of using shunt and series sections of transmission line as matching devices is here investigated mathematically. By making use of hyperbolic functions the condition of match for both cases can be expressed in a very simple way. Both devices when used alone have a limited range with regard to the impedance to be matched. The exact range within which matching is possible is shown graphically. By using one additional matching network each device can be designed to match impedance of any value. The complete systems still preserve their simplicity in structure.
Interchange of Energy between an Electron Beam and an Oscillating Electric Field
Authors: Marcum Jess
Published: January 2005

Relations between various parameters are obtained which describe the behavior of an accelerated electron beam which is caused to traverse an alternating electric field. In particular, a mechanicographical means for obtaining the gain or loss of energy is described. It is shown that under the most favorable conditions a maximum of 17 percent of the energy in the accelerated beam may be transferred to the alternating field. Application of these principles to a type of ultra-high frequency oscillator is treated.
On the Proportion of Crystalline and Amorphous Components in Stretched Vulcanized Rubber
Authors: Wildschut A. J.
Published: January 2005

Determinations of the tension-temperature relation of stretched vulcanized rubber can provide us with data about the proportion of crystalline and amorphous components. The amount of crystalline material appears to be 30–32 percent at 600 percent elongation and at 20°C. An expression is derived relating percentage crystalline material and temperature. The results are in close agreement to those of x-ray measurements carried out by Goppel but diverge largely from those obtained by Field. The cause of this difference is not yet quite clear. Stretched vulcanized rubber consists of a predominating amorphous phase with crystallites embedded in it. On stretching orientation occurs and a systematical addition of secondary valency forces is possible. This is the main cause of the existence of a certain tensile strength. Crystallization, though important as an indication on orientation, is more or less an incidental phenomenon. The distance function of the secondary forces may be of equal importance with the orientation.
Electronic Spectroscopy
Authors: Sziklai George C. , Schroeder Alfred C.
Published: January 2005

According to Einstein, the electrons leave a photo-electric surface with an initial velocity proportional to the frequency of the impinging radiation. Consequently, when a sawtooth potential is applied to a photoelectric cell, illuminated by a monochromatic light, the current flow starts at a threshold potential corresponding to the wave-length of the light, and then gradually increases more or less linearly toward a saturation value. When light of assorted wave-lengths is applied, the total current is the summation of the currents for the individual wave-lengths, each of which currents has its threshold at a different potential. By double differentiation an indication of the spectral distribution can be observed directly on an oscilloscope which is deflected synchronously with the potential applied to the photoelectric cell. The accuracy of the indication is limited by the indefiniteness of the threshold values and non-linearity of the currents above the threshold potentials in available photoelectric cells. With S4 commercial surfaces, filters of the three primary colors can be easily differentiated, but with improved surfaces considerably better resolutions may be obtained and further improvement may be had by lowering the temperature of the photoelectric surface. The method lends itself readily to color matching, since two similar devices supplying their signal with opposite polarity will give zero output when the two colors match, while it provides a direct indication of the color and magnitude of mismatch when a signal is obtained. The output signal can be utilized for relays or other control devices in industrial processes.