bluuebunny/crossref_metadata_2025 huggingface dataset:
Theory of the Cyclotron
Authors: Wilson Robert R.
Published: January 2005

The processes of formation of the initial ions in the cyclotron are reviewed, after which the various processes by which the ions are lost from resonance are considered. A theory of the loss of ions by collision or by electron capture is given and is compared with measurements made on the variation of the high energy beam current with gas pressure: satisfactory agreement is found. The inhomogeneity of the magnetic field of the 60-inch Berkeley cyclotron has been measured, and an analysis of the electric and magnetic focusing in that cyclotron is made. Rose's work on the loss of ions resulting from their getting out of phase with the radiofrequency voltage is applied to the calculation of V0, the voltage necessary to apply to the dees just to get a beam. As an example, the value of V0 is computed for the 60-inch cyclotron, and is found to be in good agreement with the directly measured value. The wandering of the ion paths is reviewed and is applied to the calculation of the inhomogeneity of the energy of emergent beam. Measurements made on the homogeneity of the energy of the protons from the 37-inch cyclotron are compared to the calculations. Finally, the question of shimming the magnetic field of a cyclotron is considered. It is suggested that the magnetic field be made to decrease from the center with a constant dH/dr. For this shape of magnetic field, analytic expressions are derived for the magnitudes of dH/dr and V0, and methods for attaining such a field are suggested.
Introduction to the Problem of the Isochronous Hairspring
Authors: Goudsmit S. , Wang Ming-chen
Published: January 2005

Deviations from isochronism for the system of hairspring and balance wheel are treated by a method due to Haag. The results are given a geometrical interpretation. It is shown that the deviations are related to the displacement of the end point of the hairspring in a set-up in which this end point is free to move keeping its tangent constant in direction. Such an arrangement can be realized with Bouasse's pendulum. For the so-called ``helical'' spring a more accurate solution than Phillips' has been found for the shape of the terminals. Extensive numerical calculations have been made for flat spiral springs, and a new simple terminal has been designed.
Stresses in Freely Falling Chimneys and Columns
Authors: Bundy Francis P.
Published: January 2005

A chimney or column is considered as a rigid rod, initially in a vertical position, and hinged at its base. The internal forces and stresses which are developed as the rod falls freely from the vertical position are calculated. It is shown that the inertial reaction forces produce a bending moment which results in a tension on the leading side and a compression in the trailing side of the rod. This tension in the leading side has its maximum value at roughly 0.3 to 0.5 the height of the rod, depending upon its shape and the angle of inclination from the vertical. This tension usually produces a transverse rupture in large falling chimneys or columns, though not always. These transverse ruptures should occur at the point of maximum tension.

It is shown that in very tall columns or chimneys the vertical shear stress near the base is sufficient to produce a tension rupture there—and usually does. The positions of these latter ruptures cannot be predicted accurately in actual cases because of the greatly variable conditions which may exist at the point of support after dynamiting.

Calculations are given for the cases of solid columns of uniform cross section, solid columns of uniformly tapered cross section, and uniformly tapered chimneys of constant wall thickness. Photographs of actual falling chimneys are presented to check the theory.
The Infra-Red Transmission of Thin Films of Various Organic Materials
Authors: Wells A. J.
Published: January 2005

The transmission of thin films of the following materials has been measured between 400 cm−1 and 3000 cm−1: Cellophane, ethyl cellulose, cellulose acetate, Duco household cement, polystyrene, glyptal, Pliofilm, rubber, Plexiglas, methyl methacrylate polymer, XYSG Vinylite, and Shawinigan V-15 resin. The possibility of using these materials for windows in spectroscopic experiments is discussed.
The Behavior of Willemite Under Electron Bombardment
Authors: Piore E. R. , Morton G. A.
Published: January 2005

Under scanning conditions in a specially designed tube, it was found that a willemite screen not only deviates from the potential of the accelerating electrode, but also shows potential variations on the surface. These potential variations are functions of scanning frequency and current density and may become of the order of several thousand volts. Light measurements were also taken. The dependence of the light intensity on voltage can be represented by a power law.
Ferromagnetic Domains and the Magnetization Curve
Authors: Brown William Fuller
Published: January 2005

The magnetization curve and hysteresis loop of a ferromagnetic material used to be explained qualitatively through the interaction of ``molecular magnets.'' It is now known that interaction of the atoms produces, directly, only magnetic saturation, and that the ``magnets'' whose interaction is responsible for the details of the hysteresis curve are much larger things-magnetically saturated regions big enough to be seen under a microscope. These ``spontaneously'' magnetized regions are known as ``domains,'' and with them progress is being made toward a quantitative theory of the magnetization process. The basic ideas of the domain theory are described in this article.
Studies in Lubrication. VII. The Lubrication of Plane Sliders of Finite Width
Authors: Muskat M. , Morgan F. , Meres M. W.
Published: January 2005

The theory of the lubrication of plane sliders of finite width-thrust block bearings-has been developed by a method that is more convenient for numerical calculations than that of Michell and Boswall. Whereas previously all the derived properties of such systems have had to be obtained by direct graphical and numerical procedures, explicit analytical expressions have been obtained in the present theory for the friction coefficients, the inclination of the wedges, the load-carrying capacities, the minimum film thickness, and the lubricant flow. The theory has been applied numerically to a much wider range of conditions than has been done before. In particular, with respect to self-aligning thrust bearings or sliders, numerical results have been obtained so as to cover both the range where the pivot is very near the center of the slider and where it is set within short distances of the trailing edge. With such extended ranges it has been possible to construct complete curves for the variation of the important derived properties of the slider system as functions of the pivot position.
The Formation and Maintenance of Electron and Ion Beams
Authors: Smith Lloyd P. , Hartman Paul L.
Published: January 2005

The radial potential distribution in an ionic beam of circular cross section is calculated and the maximum beam current which can be obtained in a beam of given radius and boundary conditions is computed. In the case of ions the maximum beam currents may be quite small. The ions in such beams have a considerable velocity distribution which in turn leads to a greater beam divergence than former calculations indicate. In Section 3 a method is worked out for holding the beam together during the initial accelerations. A disadvantage of cylindrical lenses is pointed out in this connection. The use of electrostatic lenses for holding together a beam composed of high energy particles is discussed in some detail. Calculations show the special arrangements of the lenses necessary for producing convergence of the beam. A few other arrangements to prevent divergence which were tried experimentally are described.
Some Relations Between Molecular Structure and Plasticizing Effect
Authors: Kirkpatrick Arnold
Published: January 2005

The inter-relation between the chemical constitution and structure of plasticizers and plastics is discussed. The results obtained with sulfonamide, phthalate and phosphate plasticizers in cellulose acetate compositions are used as examples and the author speculates on the possibility of formulating general rules from such data.
Preferential and Initial Ionic Recombination in Gases
Authors: Bradbury N. E.
Published: January 2005

In an attempt to determine the fraction of ions lost by recombination in an x-ray ionization chamber, a theory has been developed for the processes involved in preferential and initial ionic and electronic recombination. The theory considers the change of the energy distribution of the electrons as they diffuse away from the parent atom. From this, together with a knowledge of the electron capture process, the space distribution of negative ions formed may be obtained. The probability of the initial electron recombining preferentially with the parent positive ion is considered as well as the preferential process for the negative ion. Knowing the initial spacing of the ions, it is possible to calculate the recombination occurring during the diffusion process until random distribution is reached. The final volume recombination may then be calculated in the usual manner. The theory may be employed in both electronegative and free electron gases and to ions formed in the presence or absence of an electric field.
Tension and Birefringence in a Vinylite Plastic
Authors: Farwell H. W.
Published: January 2005

This paper describes experiments on the birefringence of a strip of plastic material, first when the stretched strip is maintained at constant length and second when it carries a constant load. The results indicate that in neither case is the birefringence proportional to the tension. The data are further examined, and the argument is presented to show that in the constant length experiment the ratio of tension T at any time after the initial tension, T1, is established should be the same function of the time as is the expression [1−2μlogeLL1] for the constant load experiment. Finally it is shown that the tension ratio data can be represented by a curve of the type, T′T1=Ae−at+Be−bt+Ce−ct.
The Analysis of Symmetrical Vibrating Systems
Authors: Pipes Louis A.
Published: January 2005

The Lagrangian equations of motion of a general mechanical system of n degrees of freedom that is executing small motions about a position of equilibrium are subjected to a Laplacian transformation. The transformed equations are then subjected to a similarity transformation. By means of this transformation, a separation of the transformed equations is effected provided the system has the special type of symmetry under consideration. The solution of the usual determinantal equation is avoided. The methods of the Laplacian transformation and matrix algebra as presented in (1) and (2) are assumed in the discussion.
Polonium Alloy for Spark Plug Electrodes
Authors: Dillon J. H.
Published: January 2005

A method of improving the starting characteristics of spark plugs involving the use of polonium is described. Results of experiments concerned with the measurement of the apparent breakdown voltage under laboratory conditions and the starting characteristics of spark plugs in internal combustion motors at low temperatures are given. These results indicate that the use of polonium in commercially practical concentrations in standard electrode alloys definitely improves the starting performance of spark plugs. Large scale methods of extraction of polonium from residues of a radium refinery and the method of introducing polonium into the electrode alloy are to be discussed in a subsequent article.
Wave Propagation in Shearing Quartz Oscillators of High Frequency
Authors: Sanders Edward W.
Published: January 2005

Experimental verification of a theory of edge grinding is given by demonstrating the presence of elastic waves along the X axis of a low frequency-temperature coefficient quartz plate.
Pendulum Analysis in the Scale Industry
Authors: Carley Glenn R.
Published: January 2005

Forces created when loads are applied to the platforms of automatic weighing mechanisms are frequently balanced by the rotation of pendulums. In certain types of pendulum-controlled scales it is desired that the relationship between the load applied and the angle turned by the pendulums be essentially linear. Even though the cams used for pendulum rotation are sectors of circles, it has been found experimentally that by the proper adjustment of various pendulum parameters, linear performance can be approximated to within less than 0.025 percent of scale capacity. An analysis of the forces involved in such systems leads to a mathematical statement of pendulum performance. Furthermore, experimental results confirm quantitatively the operation predicted by analysis. A method of selecting parameters for optimum performance is presented.
The Development of Water-Cooled Quartz Mercury Lamps
Authors: Noel Edward B.
Published: January 2005

From the Cooper-Hewitt mercury lamp of 1902, operating at a pressure of 0.0003 atmosphere and an efficiency of 18 lumens per watt, there have been developed lamps in hard glass and in fused quartz with pressures up to 200 atmospheres and efficiencies of 40 lumens per watt and above. At the highest pressures water-cooling is required, and a careful coordination of the designs of lamp, jacket, and ballast is required for successful operation. Brightness-distribution and spectral-energy data are given for the A-H6 and two experimental water-cooled lamps. Photoengraving, television, and searchlight applications of the A-H6 water-cooled lamp are discussed.
Computation of Some Physical Properties of Lubricating Oils at High Pressures I. Density
Authors: Dow R. B. , Fink C. E.
Published: January 2005

From a survey of available data on the density of fluid lubricants as a function of pressure and temperature, the following empirical equation has been derived: ρ=ρ0(1+ap−bp2)t.ρ is the density at a given pressure (gage) p and temperature t; ρ0 is the corresponding density at atmospheric pressure. The constants a and b are evaluated over a temperature range extending from 20° to 220°F and the density equation is valid over a pressure range of 50,000 lb./in.2. While the equation was derived from data on mineral oils it has been found to hold equally well for animal, vegetable, and fish oils. The variation of density with pressure is independent of the nature of the oil.
The Use of Radioactive Phosphorus in Soil Studies
Authors: Ballard Stanley S. , Dean L. A.
Published: January 2005

Some uses of radioactive phosphorus in soil and fertilizer studies have been investigated. The necessary apparatus, the technique, and the accuracy of determining radioactive phosphorus in soils, solutions and plant ashes are described and discussed, and several examples of its application in agricultural problems are given. These include measurements of the rate of sorption of phosphorus by soils, fertilizer-placement studies, and measurements of the movement of applied phosphorus through a soil.
Temperature and Temperature Scales
Authors: Wensel H. T.
Published: January 2005

An attempt has been made here to cover the general subject of temperature and methods of expressing temperature. The fundamental concepts involved are developed, the basis and significance of a thermodynamic scale are discussed, and the relation of various practical scales, in particular the International Temperature Scale, to the thermodynamic scale is explained.
Thermoelectric Thermometry
Authors: Roeser Wm. F.
Published: January 2005

The fundamental laws and theories of thermoelectric phenomena and their historical development as well as the application of these phenomena to the measurement of temperature are discussed in this paper in considerable detail. Thermoelectric thermometry, with particular regard to types of thermocouples, protection of thermocouples, fundamental considerations in temperature measurements, etc. are treated primarily from the practical standpoint.
The Mechanism of Spark Discharge in Air at Atmospheric Pressure. I
Authors: Loeb Leonard B. , Meek John M.
Published: January 2005

The Townsend equation for the passage of a spark is analyzed and its inadequacy for explaining sparks in air at near atmospheric pressures is demonstrated. The mechanisms active in air at higher pressures, viz., the electron avalanche and its tip field, photo-ionization in the gas and positive streamer formation are presented. A quantitative criterion for streamer formation is applied to give a quantitative theory for spark breakdown in air at atmospheric pressures. The theory gives quantitative agreement with experiment and predicts departures from Paschen's law. At values of the product, pressure times gap length less than 200 mm×cm in air, the new mechanism is unimportant. The theory is applied to longer sparks at atmospheric pressures and the effect of the decrease in density of photo-ionization in longer avalanches considered. This leads to a modification of the Meek mechanism by which the electron avalanche slows down while a retrograde positive streamer moves at high speed to the cathode and then advances again. This mechanism enables one to discuss the breakdown potentials of unsymmetrical gaps showing the difference in sparking potential between positive and negative points. The mechanism is correlated with the passage of lightning discharges. Alterations of Meek's theory of the stepped leader are indicated. Part I describes the classical theory of spark discharge and the nature of the mechanism which must be active at higher pressures. Part II will consider streamer formation and spark breakdown in short and long gaps.
Growth Conditions for Single and Optically Mosaic Crystals of Zinc
Authors: Cinnamon C. A. , Martin Albert B.
Published: January 2005

A modified Kapitza method used in the study of conditions favorable to the growth of single crystals of zinc (99.99+ percent pure), shows that the ratio of the temperature gradient (across the interfacial boundary between the liquid and solid phases) to the rate of growth of the crystal must be maintained within an optimum range of values, depending on the angle of orientation. Optically mosaic crystals give no indication of a preferred region of growth and can be obtained over a much wider range of conditions.
An Experimental Study of Heat Interchangers
Authors: Jacobs R. B. , Collins S. C.
Published: January 2005

Recent developments of engines and turbines for producing low temperatures have emphasized the necessity of improved heat interchangers for further progress in the field. The present report covers an experimental investigation of heat interchanger design and operation intended primarily to cover those applications most likely to occur in the experimental rather than in the commercial laboratory.
Flow of a Gas Through Porous Media
Authors: Fowler J. L. , Hertel K. L.
Published: January 2005

Kozeny's approximate solution to the problem of fluid flow through porous media is developed and the result is checked by experimental data on air flow through plugs of cotton, wool, rayon, and glass wool fibers. The solution gives WA=kγ02μ(τσ)(1−c)32c2(−δp2δx)for the isothermal linear flow of a gas. W/A is the macroscopic flux density; μ, the viscosity; γ0, the density of the gas at unit pressure; τ/σ, the volume of fibers divided by their surface area; c, the fraction of space occupied by fibers; δp2/δx, the macroscopic gradient of the square of the pressure; and k is a numerical constant which depends on the shape and orientations of the fluid passages. k was found experimentally to be 0.18, which is in approximate agreement with the value found for flow through media made up of spherical particles. The dependence of the flow on the factor c was checked over the approximate range from c=0.1 to c=more than 0.5. τ/σ and c have values for fineness and density of samples of fibers in fair agreement with independent determinations.
Electronic Generation of Electromagnetic Oscillations
Authors: Condon E. U.
Published: January 2005

A general formulation of the problem of transfer of power from the electron beam to an oscillating circuit by moving charged particles is given. The method is applied specifically to calculation of the behavior of the klystron oscillator in making approximations analogous to those made by Webster in his treatment of the same problem.
A Graphical Method for Selecting Suitable Targets for Precision Determination of Cubic Lattice Constants and for Solving Cubic Powder Patterns
Authors: Carapella Louis A.
Published: January 2005

Graphical charts from which the angles of diffraction lines may be obtained as a function of lattice constant and radiation have been prepared for cubic powder patterns. The charts are especially useful in predicting positions of back-reflection lines in order that suitable targets for precision determinations of lattice constants may be chosen. Moreover, cubic powder patterns may be quickly indexed, beta-lines identified, and lattice constants read to better than one percent. No calculations are necessary after the angles of diffraction have been measured.
The Initial Stage of Plastic Deformation in Lead Under Compression
Authors: Lyons W. James
Published: January 2005

In the steady-creep stage in metals, stress (or resistance to deformation) is related to the velocity of deformation, in accordance with the hyperbolic-sine law, or the exponential law. These laws, however, fail completely to describe the initial stage of plastic deformation in lead. The present series of tests is an investigation of this initial stage in compression. An optical lever system and high speed kymograph have been employed. The photographic records obtained show the progress of deformation with time. The duration of the initial stage increases with the compressing load. For a load of 120.0 kg the duration is about 0.16 sec. It is found that a unique, initial deformation, independent of time, is associated with each load. From measurements on the deformation curves, resistances as functions of time have been calculated. These data indicate a linear relationship between the resistance R and time t: R=l+mt,where l=a parameter of small value, evidently a correction term, and m=rate of increase of resistance. Using this equation and the dynamic constants of the apparatus, deformation curves in good agreement with experiment have been derived. Resistance in the initial stage appears to be only approximately a function of deformation alone
The Influence of Initial Stress on Elastic Waves
Authors: Biot Maurice A.
Published: January 2005

A rigorous treatment is given of the problem of wave propagation in an elastic continuum when the influence of the initial stress is taken into account. After a short review of the theory various cases of initial stress are considered. It is shown that a uniform hydrostatic pressure does not change the laws of propagation. A hydrostatic pressure gradient produces a buoyancy effect which causes coupling between rotational and dilatational waves. Bromwich's equations for the effect of gravity on Rayleigh waves are derived from the general theory and the physical transition from Rayleigh waves in a very rigid medium to pure gravity waves in a liquid is discussed. The case of the vertical uniform stress is also considered and it is shown that the effect of the initial stress on the waves in this case cannot be accounted for by elastic anisotropy alone. Reflections may be produced by a discontinuity in stress without discontinuity of elastic properties.
Theory of Frequency Controlled Oscillators
Authors: Sabaroff Samuel
Published: January 2005

A solution of the oscillator equation is obtained in which is indicated the basic mechanism involved in the frequency control of oscillators. The well-known fact that control of an oscillator is possible when the ratio of controlling frequency to oscillator frequency is m/n, where m and n are integral, is theoretically demonstrated.
Rectilinear Electron Flow in Beams
Authors: Pierce J. R.
Published: January 2005

Electrodes are devised by means of which rectilinear electron flow according to well-known space charge equations can be realized in beams surrounded by charge-free space. It is shown how these electrodes can be used in the design of electron guns having desirable characteristics.
On the Flow of Suspensions Through Narrow Tubes
Authors: Dix F. Johnson , Blair G. W. Scott
Published: January 2005

The anomalous flow of certain suspensions through narrow tubes, known as the ``sigma'' phenomena, for which no fully satisfactory explanation has yet been given, is discussed. If it be assumed that the streamlining layers are not infinitely thin, so that a summation treatment takes the place of an integration, a series of equations can be derived depending on the relation assumed to exist between velocity gradient and shearing stress and on the nature of the friction between the layers. These equations reduce, in the limiting case of infinitely thin layers to the well-known forms of Poiseuille, Buckingham-Reiner, etc., and the general equation of Schofield-Scott Blair can also be derived. For finite thicknesses of layer, the equation derived adequately explains the sigma-phenomenon, and this is shown quantitatively by applying it to the data given in the original paper.
A Theory of Large Elastic Deformation
Authors: Mooney M.
Published: January 2005

It is postulated that (A) the material is isotropic, (B) the volume change and hysteresis are negligible, and (C) the shear is proportional to the traction in simple shear in a plane previously deformed, if at all, only by uniform dilatation or contraction. It is deduced that the general strain-energy function, W, has the form W=G4 ∑ i=13(λi−1λi)2+H4 ∑ t=13(λi2−1λi2),where the λi's are the principal stretches (1+principal extension), G is the modulus of rigidity, and H is a new elastic constant not found in previous theories. The differences between the principal stresses are σi[minus]σi=λi∂ W/∂λi[minus]λi∂ W/∂λi.

Calculated forces agree closely with experimental data on soft rubber from 400 percent elongation to 50 percent compression.
Calculation of the Radiation Properties of Hollow Pipes and Horns
Authors: Chu L. J.
Published: January 2005

The radiation properties of hollow pipes and horns are analyzed. The vector Kirchhoff formula is employed. The radiation fields from the transverse electric wave in hollow pipes of circular and rectangular cross sections are derived. For the TE1, 1 wave in circular pipe and the TE0, 1 wave in the rectangular pipe, the directivities are analytically expressed in terms of beam angle and power gain. It is found that the two waves have substantially equal power gains on the basis of equal areas of openings. The formulae for the radiation fields of TE0, 1 and TE1, 0 waves in a sectoral horn are given, of which, curves illustrating the radiation properties have been published previously.
Lubrication in Vacuum by Vaporized Thin Metallic Films
Authors: Atlee Z. J. , Wilson J. T. , Filmer J. C.
Published: January 2005

Rotating anode x-ray tubes for medical roentgenography require bearing operation in high vacuum. A method of lubricating such bearings by vaporizing a thin film of low vapor pressure material, such as pure barium metal, onto them in the final vacuum is described. The results of tests with a great many different metals as the vaporizing films and combination films, as well as different base materials, are given. Experimental evidence is presented that indicates the lubricating film to be a liquid alloy of barium and metals such as cobalt, chromium, or aluminum.
Parasitic Electronic Oscillations and Coupling Frequencies in a Power Tube
Authors: King Ronald
Published: January 2005

The frequency spectrum of electronic oscillations in a large power triode having cylindrical plate and grid, and a filament consisting of four wires arranged at the corners of a square has been investigated. Experimental curves are displayed showing that two distinct primary frequencies may be generated at the same time, and that each of these may be replaced by two coupling frequencies, which also may be observed simultaneously, when the secondary circuit is near resonance with the primary clouds of electrons. The curves are interpreted in terms of a doubly resonant space-charge region, and in terms of coupled-circuit theory. Wave-lengths extending from 50 to 250 cm have been recorded.
An X-Ray Study of the Proportion of Crystalline and Amorphous Components in Stretched Rubber
Authors: Field J. E.
Published: January 2005

A method is described for obtaining a quantitative measure of crystalline hydrocarbon present in stretched rubber samples by comparing the intensities of the diffraction spots and the amorphous halo appearing in the x-ray diagrams. This method has been applied in studying the crystallinity of stretched vulcanized rubber as it is affected by different vulcanization accelerators, and variations in extension, temperature and cure. To illustrate a connection between the physical performance of a rubber vulcanizate and its degree of crystallization, measurements were made on the relation of crystallinity to creep when the rubber was stretched to different initial elongations under constant loads. The creep as a function of the elongation has a maximum value at the same intermediate elongation for which crystallization becomes appreciable. At higher elongations, the increased crystallinity results in a diminution of the creep. The ultimate strength and extensibility generally associated with stretched vulcanized rubber is the result of the combined effect of the primary valence cross-linkages formed by vulcanization and the formation of crystallites caused by stretching. Crystallization is an important factor in maintaining the relatively high strengths of vulcanizates having a greater range of extensibilities. In general, the physical properties and performance of vulcanized rubber is related to the amount of crystalline material formed upon stretching, which of course depends upon the structural characteristics of the vulcanizate.
Infra-Red Spectra of Rubber and High Polymers
Authors: Sears W. C.
Published: January 2005

The transmission spectra of thin films of the following materials have been measured between 2.2μ and 14.8μ: crude rubber, soft and hard vulcanized rubber, thermoprene, polyvinylchloride, Neoprene and Pliofilm. The spectrum of rubber resembles that of the long chain paraffins more closely than do those of the polymers, polyvinylchloride, Neoprene and Pliofilm, all of which contain chlorine and have distinctive spectra. Vulcanization of rubber with 2.3 percent sulfur gives rise to no new bands in the region 2.2μ to 12.5μ characteristic of molecular cross bonding. Some of the bands in these materials are identified with valence vibrations.
Physical Characteristics of Synthetic Rubbers
Authors: Street J. N. , Dillon J. H.
Published: January 2005

A summary of the nature and special applications of the more important types of synthetic rubbers is given. Two series of rubber and synthetic rubber stocks, compounded on the basis of comparable pigmentation, were selected for study. In addition to the conventional physical properties (tensile strength and elongation at rupture, modulus, aging, etc.), a number of other mechanical properties such as dynamic rigidity, hysteresis loss, ``blowout resistance,'' ``running temperature,'' and tensile strength at elevated temperature were measured. Swelling tests in various solvents were also made. Results are plotted in the form of correlation charts in an effort to select proper methods of measurement. Some observations on comparative service tests in tires in the case of three synthetic rubbers indicate them to be satisfactory, on a quality basis, for use in time of emergency. The importance of care in selecting the proper physical tests and methods of analysis is emphasized in the light of the results given. It is concluded that rubber testing techniques and interpretation must be modified in certain instances in evaluating synthetic rubber stocks.
Sputtering and Secondary Electron Emission of Metals Bombarded by Argon Ions
Authors: Timoshenko Gregory
Published: January 2005

A method has been devised for accurate determination of the absolute rate of sputtering, i.e., the measurement of the number of atoms liberated from a metallic target under the impact of a single ion of known energy. The accuracy of this measurement was 6 to 7 percent—a precision hereto unattainable by other methods. The apparatus producing argon ions consisted of a strong ion-source of capillary-arc type. The ions were accelerated within a high vacuum chamber through a potential, which was varied from 2000 to 7000 volts, and then allowed to strike a metallic target. The sputtering rate was determined by measuring the positive ion current to the target and the loss of target material. Results are given on sputtering of silver by argon, and on the secondary electron emission from aluminum and molybdenum.
Frictional Phenomena. III
Authors: Gemant Andrew
Published: January 2005

THE extent to which viscous processes can account for the absorption of freely traveling acoustical waves in gases is shown. Considerable divergence between theory and experimental data is found for polyatomic gases, and an explanation of this divergence on the basis of intramolecular vibrations is presented.
Frictional Phenomena. IV
Authors: Gemant Andrew
Published: January 2005

IN this chapter a technical application of gaseous viscosity in the field of room acoustics is given. After a brief introduction into room acoustics, the absorbing property of sound-absorbing materials is explained on the basis of viscous processes in the pores of the material. Experimental data are in fair agreement with this explanation. It is even possible to derive the characteristics required for the most efficient absorbent, important from the standpoint of their manufacture.
A Preliminary Report on the Development of a 300-Kilovolt Magnetic Electron Microscope
Authors: Zworykin V. K. , Hillier J. , Vance A. W.
Published: January 2005

Electron microscopes using accelerating potentials of from 30 to 100 kilovolts cannot be employed satisfactorily for the examination of specimens whose thickness is greater than one-half micron (in the case of organic material). In order to investigate the possibility of applying the high resolving power of the electron microscope to problems involving somewhat thicker specimens, an instrument has been constructed which uses electrons accelerated by voltages up to 300 kilovolts. A commercial electron microscope has been adapted for the purpose by the modification of the electron gun and projection lens, and by the addition of a new high voltage generator. The essential features of the new design and some of the problems encountered in the testing of the equipment are described. Comparison micrographs of test objects taken with 50- to 250-kilovolt electrons demonstrate the increase in penetrating power obtained at the higher potentials. An electron micrograph of a biological section, one to two microns thick, taken with 200-kilovolt electrons shows a promising amount of the internal structure.
Studies in Lubrication: X. Friction Phenomena and the Stick-Slip Process
Authors: Morgan F. , Muskat M. , Reed D. W.
Published: January 2005

Studies have been made of the stick-slip behavior recently investigated by Bowden and collaborators. The friction apparatus consists essentially of a table which can be made to rotate at a very low velocity and a slider elastically supported at the center of rotation of the moving surface. Examples are shown of the stick-slip process with several combinations of metals at various speeds and loads. Motion pictures of the slider and table have been made in order to study possible slipping during the stick phase. Temperature records of the stick-slip cycle indicate that the temperature flash is confined exclusively to the slip period and in no case studied exceeds 50°C above ambient. Traces made of the slip phase with very high camera speeds permit an analysis of the variation of kinetic friction with velocity. Thus both static and kinetic friction data can be obtained from a single stick-slip cycle.
Matrices, Tensors, or Dyadics for Studying Electrical Networks?
Authors: Reed Myril B.
Published: January 2005

Dyadic algebra, because it has been designed for three-dimensional systems, must undergo further development to be effective for more than three-mesh networks. There is little point in carrying out such a development, since the much used cross product and the symbolism of dyadics both lose their simplicity for more than three dimensions. Of the outstanding properties of tensor analysis, only the special technique of linear transformations has been used in electrical network studies. But linear transformations are basic to the theory and manipulations of matrix algebra. Therefore, the simplest and most effective approach to network transformations is through matrix algebra. The primitive-network impedance matrix of tensor treatments is in reality nothing more than the matrix of the branch impedances of a network, and the linear transformation employed to formulate the mesh-current impedance matrix is simply the transformation which relates mesh and branch currents. Furthermore, the ``interconnection of networks'' transformation is merely a transformation from more than the minimum number of mesh currents to the minimum number. Matrix transformations may be used to establish networks which are equivalent.
Steady-State Analysis of Multiconductor Transmission Lines
Authors: Pipes Louis A.
Published: January 2005

Starting with the fundamental field equations of Maxwell, the various approximations involved in the usual engineering formulation of the multiconductor problem are examined. Subject to these approximations, the set of differential equations which is taken as the starting point of the classical transmission theory in the steady state are derived and the character of the various parameters involved in these equations is studied. By the use of the Laplacian transformation and certain theorems of matrix algebra these equations are solved for the case of general terminal conditions. Certain special cases where the system exhibits symmetry are discussed.
Temperature Dependence of Young's Modulus and Internal Friction of Lucite and Karolith
Authors: Rinehart John S.
Published: January 2005

The Young's modulus and specific energy loss of Lucite and Karolith were measured at different frequencies in the neighborhood of 50 kc/sec. as a function of temperature. The temperature range for Lucite was from −55°C to 65°C, and for Karolith, 25°C to 110°C. It was found that the reciprocal of Young's modulus versus temperature curves showed positive curvatures at higher temperatures for both materials. At room temperature the Young's moduli of Lucite and Karolith were 4.72 and 6.14×1010 dynes/cm2, respectively. The specific loss was found to vary with frequency for both materials and varied in a linear fashion for Lucite at room temperature. Absorbed water seemed to have a pronounced effect on the Young's modulus of Karolith.
Precipitation Hardening in the Fe-W System
Authors: Smith Charles S.
Published: January 2005

An x-ray study has been made of precipitation-hardened, 7.16 percent tungsten, iron-tungsten alloys. It is concluded that the precipitation reaction is of the discontinuous type. On the basis of diffraction evidence a mechanism for the formation and growth of the precipitate is proposed and a picture of the crystallographic form of the precipitate deduced.
Frictional Phenomena. V: B. Liquids
Authors: Gemant Andrew
Published: January 2005

THIS chapter presents theories of liquid viscosity, particularly those of van der Waals, Andrade, Prandtl, and Eyring. Whereas the viscosity of gases is based on the collisions of molecules, that of liquids is dominated chiefly by molecular attraction forces. Experimental material is presented on the effect of chemical constitution, temperature, pressure, and mixture ratio on viscosity, which effect is explained on the basis of existing theories. A brief outline of turbulent flow closes the chapter.
Propagation of Electromagnetic Waves in a Space Charge Rotating in a Magnetic Field
Authors: Blewett John P. , Ramo Simon
Published: January 2005

A theoretical discussion is presented of the transmission of electromagnetic waves of the symmetrical, transverse magnetic type by a space charge of uniform density, rotating under the influence of a uniform magnetic field. It is shown that the space charge presents to the wave an effective dielectric constant less than unity. By appropriate choices of magnetic field, the dielectric constant can be reduced to zero and can even become negative, so that the wave undergoes attenuation as it passes through the space charge. Experiments are described on the control of the propagation constants of 470-megacycle waves by variation of the dielectric constant of the rotating space charge medium. The results obtained are in agreement with the theoretical predictions.
Hysteresis Torque in Elliptically Polarized Fields
Authors: Beck F. J. , Clarke J. G.
Published: January 2005

In ferromagnetic materials if the magnitude and direction of the magnetic field intensity are changed hysteresis occurs. This, in general, is of two types: the usual alternating hysteresis, and the torque component of hysteresis which gives rise to the rotational loss when the direction of the magnetic field intensity is changed and the magnitude is held fixed. By means of a torque magnetometer, the time average of the torque has been observed as a function of the applied magnetic field intensity for elliptical fields of different eccentricity. For the silicon iron disk investigated, and with the field along one axis (the first axis) as a parameter, the time average of the torque increases with applied field along the mutually perpendicular axis, reaching a maximum value at the bend in the magnetization curve and then decreases as saturation is approached. The torque curves first increase, go through a limiting curve, and then decrease as the field along the first axis is increased. A qualitative explanation of the shape and variation of the torque curves with field strength is suggested.
Determination of the Static and Dynamic Constants by Means of Response Curves
Authors: Bernhard R. K.
Published: January 2005

The general characteristics of response curves of one degree of freedom systems excited by constant force amplitudes and amplitudes increasing with the square of the exciting frequency are discussed. Relations between displacement, velocity, power-input and phase angle versus discord are compared for various damping values. Simple formulae are derived to determine by means of these response curves the static and dynamic constants of mechanical systems with one degree of freedom. A numerical example demonstrates the practical application.
The Optical Properties of Rubber
Authors: Wood Lawrence A.
Published: January 2005

The optical properties of rubber are discussed under four main headings: absorption, scattering, refractive index, and double refraction. A general survey of the results of previous work in each of these fields is given. Some of the possibilities for future investigation are indicated. New experimental data are presented for the transmission values of milled pale crepe and a soft vulcanized rubber compound at wave-lengths from 400 to 750 mμ. The results of some measurements on scattering are also included. The variation of refractive index with wave-length is given, as calculated from unpublished measurements of the angles of minimum deviation of prisms of unvulcanized and of vulcanized rubber.
Forced Oscillations in Cavity Resonators
Authors: Condon E. U.
Published: January 2005

Formulas are developed for calculation of the impedance of a cavity resonator when excited by a coupling loop or by a capacitative coupling.
Sparking of Oxide-Coated Cathodes in Mercury Vapor
Authors: Knowles D. D. , McNall J. W.
Published: January 2005

When an oxide-coated cathode tube of the gas or vapor type passes more than a certain amount of current a spark or cathode spot occurs on the cathode and the tube is damaged. A peak current rating is, therefore, essential for any tube of that type and it becomes necessary to take data on how the sparking current is influenced by cathode temperature, vapor or gas pressure and other factors. By ordinary test methods each spark is so destructive that only one reading can be taken on one tube and the effect of the above factors is confused by the variation in quality of tubes used to obtain the data. The authors have developed a test procedure that so limits the duration of the spark that very little damage to the cathode results. This makes it possible to obtain a large number of readings on each tube and thereby observe effects otherwise obscured. The experimental procedure appears to be a good one for investigations in this field and the results obtained shed some light on the mechanism of sparking.
General Theory of Three-Dimensional Consolidation
Authors: Biot Maurice A.
Published: January 2005

The settlement of soils under load is caused by a phenomenon called consolidation, whose mechanism is known to be in many cases identical with the process of squeezing water out of an elastic porous medium. The mathematical physical consequences of this viewpoint are established in the present paper. The number of physical constants necessary to determine the properties of the soil is derived along with the general equations for the prediction of settlements and stresses in three-dimensional problems. Simple applications are treated as examples. The operational calculus is shown to be a powerful method of solution of consolidation problems.
Field Emission X-Ray Tube
Authors: Slack Charles M. , Ehrke Louis F.
Published: January 2005

It has been found possible to draw currents of the order of several thousand amperes from cold metals by field emission in vacuum. This principle has been put to use in the design of a condenser discharge x-ray tube for high speed radiography. An auxiliary electrode spaced close to the cathode and connected to the anode through a high resistance serves to initiate the discharge which is then transferred to the anode. This auxiliary electrode is made in the form of a focusing electrode. Radiographs of bullets and the internal workings of other high speed objects are now made possible.
An X-Ray Study of the Changes That Occur in Aluminum During the Process of Fatiguing
Authors: Spencer Raymond G. , Marshall J. Wallance
Published: January 2005

Carefully prepared test bars of 17S-T aluminum alloy have been fatigued; x-ray diffraction patterns of each specimen were taken at intervals as fatiguing progressed. Approximately thirty different test bars have been studied. Seven series of diffraction patterns, corresponding to seven different specimens, are reproduced and discussed in this paper. This study shows that (1) fatigue failure of 17S-T aluminum is always preceded by fatigue damage which is detectable by the use of x-ray diffraction patterns; (2) nearly all of the detectable changes occur in the last stages of fatiguing and consist of rotation of grains, introduction of strains in some of the crystallites, and fragmentation of some of the crystallites; (3) these changes do not occur when the specimen is fatigued below its endurance limit, but always occur prior to failure when it is fatigued above the endurance limit; (4) failure is probably intercrystalline rather than intracrystalline in character.