bluuebunny/crossref_metadata_2025 huggingface dataset:
pH Determinations on Sludge of Particulate Carbonaceous Materials and Ash Discharged in the Atmosphere by Fuel Burning Sources
Authors: Bloomenthal S. , Deutch I. A.
Published: January 2005

pH measurements on sludge of particulate carbonaceous materials and ash were made with a vacuum tube potentiometer amplifier. Dust, precipitated out of flue gas of industrial fuel burning plants through the use of the series impinger, gives pH values of sludge in the range 2.5 to 5. Sludge of ash of coal used in these tests gives pH values in the range 7 to 11.5, depending upon the seam and locality in which the coal is mined. The results of this study may aid the ``fingerprinting'' of dust, responsible, in part, for atmospheric pollution in American cities.
Some Useful X-Ray Data
Authors: Pike Eugene W.
Published: January 2005

The measured mass absorption coefficients of Allen and Wrede for H, Be, C, N, O, F, Na, Al, Si, Cl and Br have been fitted to the ``universal law''μ/ρ=aλn+c/(1+0.048/λ),by least squares, and the values of a, n, and c tabulated. The energy distribution in the continuous x-ray spectrum in the range from 20 to 70 kv, as measured by Kirkpatrick and by Ulrey, has been recomputed, and presented graphically in a form which permits easy interpolation. The recomputation of Ulrey's data is described in some detail.
Cathode Spot Initiation on a Mercury Pool by Means of an External Grid
Authors: Townsend Mark A.
Published: January 2005

Experiments relating to mercury-pool stroboscope tubes with external starting bands are described. Of particular interest is the unidirectional current that is found to flow in the plate circuit when grounded and its relationship to the formation of a cathode spot on the mercury cathode. Cathode-ray oscillograms are exhibited showing the periodic nature of this current. The potential of a disconnected electrode is negative with respect to the cathode and has a value of several thousand volts. Curves of the volt-ampere characteristics of an anode are given as a function of tube dimensions, gas pressure and other factors.
The Effect of X-Rays on the Breakdown Strength and Flashover Voltage of Certain Dielectrics
Authors: Walker Eric A.
Published: January 2005

Qualitative measurements are made on the reduction of breakdown strength of certain solid, liquid, and gaseous insulations. The observed reduction in breakdown strength is influenced by the gap length as well as the quantity of the x-rays. Exposing a solid to air boundary to x-rays increases the flashover voltage. A theory for this effect is offered.
Electromagnetic Waves in Transformer Coils Treated by Maxwell's Equations
Authors: Rüdenberg Reinhold
Published: January 2005

A rigorous solution of Maxwell's equations is derived for waves in a thin single-layer coil, a concentric ground electrode being at a short distance from the coil. Simple transformer coils resemble such an ideal to a considerable degree. Any electromagnetic state of the coil propagates slowly in axial direction with such a velocity that the phase velocity along the helical conductor equals the velocity of light. The surge impedance of the coil is constant for low frequency, but decreases with higher frequency, the boundary wave-length being determined by the insulating distances.
Steady-State Solutions of Electromagnetic Field Problems. I. Forced Oscillations of a Cylindrical Conductor
Authors: Stratton J. A. , Chu L. J.
Published: January 2005

The object of this investigation is a study of the current distribution in or on the surface of a conductor and its associated field under the influence of a localized e.m.f. Steady-state solutions of the field equations are found for conductors of simple geometric form. The results clarify many electromagnetic problems involving localized sources, especially in the u-h-f region, for which ordinary circuit theory fails to give a satisfactory quantitative explanation. Part I treats the problem of a straight cylindrical conductor and shows the relation of the principal and complementary waves to the nature of the exciting field. A driving point impedance is calculated for the case of an external field applied over a vanishingly short section of conductor. The driving point impedance is infinite for a conductor of infinite length and perfect conductivity. Likewise the case of a conductor of finite length bounded at either end by an infinite, perfectly conducting plane is discussed. This problem bears a direct relation to that of a hollow pipe excited by a linear antenna.
Steady-State Solutions of Electromagnetic Field Problems. II. Forced Oscillations of a Conducting Sphere
Authors: Stratton J. A. , Chu L. J.
Published: January 2005

The method discussed in Part I for the determination of steady-state solutions of electromagnetic problems is applied to a finitely conducting sphere as the simplest illustration involving a body of finite dimensions. The external e.m.f. is applied across an infinitesimal strip at the equator. The induced field appears as the sum of an infinite number of partials or modes. As the frequency is increased these modes become successively dominant. There are a series of resonance points. The real part of the driving-point admittance rises step-wise with increasing frequency and the behavior of the system is notably different from that of a normal circuit. Expressions are given for the power dissipated in heat and in radiation and it is shown that the complex power input at the driving point is equal to the integral of the complex Poynting vector over the surface of the sphere.
Steady-State Solutions of Electromagnetic Field Problems. III. Forced Oscillations of a Prolate Spheroid
Authors: Chu L. J. , Stratton J. A.
Published: January 2005

The method discussed in Parts I and II for the determination of steady-state solutions of electromagnetic problems is applied to a prolate conducting spheroid. An external e.m.f. is applied across the central section of the spheroid and the resultant field is represented as an infinite sum of wave modes expressed in terms of spheroidal functions. To each mode there corresponds a definite resonant frequency. As the applied frequency passes through the resonance point of a given mode, the corresponding term in the driving-point admittance changes from capacitive through a pure conductance to inductive. The sharpness of resonance increases with the eccentricity. Curves are drawn showing the behavior of the real and imaginary parts of the admittance for several values of eccentricity. The solution goes over, in the limit of zero eccentricity, to that discussed in II. When the eccentricity approaches unity one obtains a linear antenna of finite length and the driving-point impedance at the resonance frequency of the first mode is shown to be about 72 ohms.
Relaxation of Metals at High Temperatures
Authors: Trumpler W. E.
Published: January 2005

Much experimental work has been done on the creep of metals and the long-time creep test is the standard means of rating resistance to slow deformation of metals under tensile stress. In engineering practice, frequently, cases are found in which the total strain and not the stress remains constant. In what has become known as relaxation, an initially pure elastic strain gradually is transformed into a permanent strain while the length of the bar remains unchanged. Several years ago some new apparatus was designed and built primarily to duplicate the above conditions in connection with the study of bolt materials for steam turbines. The unusual accuracy and exceptionally good test results obtained from the automatic relaxation machine during more than two years of operation indicate that the type of test may well become a means of comparison as standard as a creep test and at a great reduction of testing time.
Applied Nuclear Physics
Authors: Evans Robley D.
Published: January 2005

Following the discovery of artificial radioactivity and the rarer stable isotopes of the light elements, the forty-year-old field of applied nuclear physics has found a greatly increased domain of usefulness in chemistry, metallurgy, radiology, geology, physiology and medicine. Isotopic tracer atoms, whether stable or radioactive, provide a powerful method for observing the behavior of complicated biological, chemical or physical systems under equilibrium conditions. Atom smashing machines, when slightly modified, are useful in metallurgical and clinical radiology, while other techniques and results from the field of nuclear physics find important applications in geology and astrophysics.
X-Ray Physics and X-Ray Tubes
Authors: Hicks Victor
Published: January 2005

A fast moving electron strikes a target—an x-ray is born. This paper leads one from this simple fact to the most advanced sealed-off tubes with air or liquid cooling, rotating targets, as well as demountable tubes of both vacuum and gas-filled types.
X-Ray Diffraction Methods
Authors: Warren B. E.
Published: January 2005

To learn more about the identification of crystalline materials, preferred orientations, particle sizes, strains, and structure randomness, x-ray diffraction is used. Here both basic principles and working techniques are described.
Determination of Constitution Diagrams with X-Rays
Authors: Barrett Charles S.
Published: January 2005

Constitution diagrams give in a small amount of space a great deal of information—the solid solutions and components present in an alloy—the ranges of temperature and compositions over which they are stable—information of very practical value to the metallurgist. The part played by x-rays in ferreting out this information is described herein.
Consolidation Settlement Under a Rectangular Load Distribution
Authors: Biot M. A.
Published: January 2005

The author's general theory is applied to the calculation of the settlement through consolidation of a soil loaded uniformly on an infinite strip of constant width with particular reference to the nature of the settlement at the edge of the loaded area. The solution is obtained by first calculating the settlement produced by a suddenly applied load with sinusoidal distribution. The use of a Dirichlet integral and the principle of superposition leads then directly to the solution for the discontinuous loading.
Cathode Drop of an Arc
Authors: Fett G. H.
Published: January 2005

By use of the method of Betz and Karrer the cathode drop of an arc has been measured for a number of electrodes, including copper, silver, iron and arc welding electrodes with and without coatings. The time for an arc to establish the cathode drop voltage measured from the time the ``last'' contact causes an appreciable voltage drop is found to be less than 40 microseconds. The cathode drop for copper is found to decrease with air pressure from 13 volts at atmospheric pressure to 8 volts at 0.1 mm of Hg pressure.
A Method of Measuring the Thermal Conductivity of Rock Cores
Authors: Hersey J. B.
Published: January 2005

A method of measuring the thermal conductivity of long rock core samples is described. It is an adaptation of Bidwell's method of measuring the thermal conductivity of metals. The core is packed in Silocel in a cylindrical container. Heat is supplied by a flat electric heater on one end of the core sample, and measurements of temperature are made along the core and at several radial distances in the insulator. Isothermal surfaces in the insulator are determined and found to be conical surfaces within several centimeters of the core. These are parallel for some distance along the core. Using this fact the conductivity of the core is computed relative to that of the Silocel. A value 5.92 × 10−3 cal./cm deg. sec. was obtained for a sample of Norite and 2.59 × 10−3 for a Pyrex rod at room temperature.
A Preliminary X-Ray Study of Binary Alloys of Platinum with Cobalt, Molybdenum and Tungsten
Authors: Hultgren Ralph , Jaffee Robert I.
Published: January 2005

At the composition PtCo there exists a tetragonal superlattice with the AuCu structure. It is stable at 600°C, but forms a face-centered-cubic disordered phase at 1000°C. It is the incipient formation of this superlattice which is responsible for the superlative remanence and coercivity reported by Jellinghaus. At 400°C a body-centered-cubic phase begins to form. More than 50 atomic percent molybdenum and more than 35 atomic percent tungsten are soluble in platinum at 1000°C.
Further Study of the Flow of Air Through Porous Media
Authors: Sullivan R. R.
Published: January 2005

The streamline flow of air through highly porous wads of textile fibers is studied. The rate of flow is found to be twice as great for fibers parallel to flow as for fibers perpendicular to flow. Shape factors for the channels through which the flow takes place are determined and compared with those for the ideal case of Emersleben. The problem of measuring specific surface of high porosity wads is discussed.
Temperature Correction Methods in Calorimetry
Authors: King Allen , Grover Horace
Published: January 2005

There are two fundamentally different methods of correcting calorimetric data for heat losses to surroundings. The first method, applicable only to experiments in which the supply of heat to the calorimeter can be neglected after a certain time, uses the afterperiod cooling curve, together with a similar curve from data taken before the heat supply started, to evaluate appropriate correction terms. This problem is discussed from a general point of view and correction formulas previously reported by Regnault and Pfaundler, Schultes and Nübel, Roth, and others are shown to be variations of a general scheme. A second method is needed in such experiments as the measurement of specific heat when it is not safe to neglect the heat supplied by the hot body even after a very long time. In this case, there is no afterperiod cooling curve and additional assumptions concerning the heat exchange between the calorimeter and the hot body within it must afford the needed information. The assumptions originally suggested by Rowland are re-examined. It is shown that previous investigators (Rowland and Hoare) deduced inadequate correction methods from these assumptions. A better method is developed and a simple approximation of it is suggested. Application of the new method to a set of data gives results different from those obtained by the Rowland-Hoare methods, from those obtained by the Regnault-Pfaundler method (which, despite previous use, should not be applied to such data), and from those obtained by the method of Dickinson (which is recommended by the ASTM standards). The differences are significant in precision work. A brief critical review of graphical methods of obtaining the temperature correction concludes the paper. This review includes a graphical analog of the new method mentioned above.
Kinetics of Degradation and Size Distribution of Long Chain Polymers
Authors: Simha Robert
Published: January 2005

The rate equations for the depolymerization process of linear chain molecules are formulated and a general solution is given. Three special cases are considered: (a) Equal disintegration probability for all linkages independently of their position in the chain. The results confirm and extend the ones previously found from statistical considerations. (b) Preferred breaking at the ends. (c) Equal disintegration probability for all chains independently of their size. Equations for the decrease of number and weight average molecular weight with time are given in each case.
Consolidation Settlement of a Soil with an Impervious Top Surface
Authors: Biot M. A. , Clingan F. M.
Published: January 2005

An investigation is made of the consolidation settlement for a soil whose top surface is impervious and loaded uniformly on an infinite strip of constant width. The settlement under the load is accompanied by considerable swelling of the unloaded area on both sides of the load.
On Similarities Between Stress and Flow Patterns
Authors: Hetényi Miklós
Published: January 2005

The purpose of this paper is to review established relationships between stress and flow problems. Two-dimensional plane stress systems were found to have features analogous to non-viscous potential flow fields on one hand, and to viscous flow on the other hand. Accordingly, this discussion is divided into two parts. In each case the fluid is assumed to be continuous, homogeneous, and incompressible.
Three-Dimensional Photoelasticity Using Scattered Light
Authors: Weller R.
Published: January 2005

It is possible to use the polarization caused by the scattering of light within a photoelastic model in place of the usual analyzer in a photoelastic polariscope. This enables one, in effect, to use an analyzer which lies within the interior of the model, and so make analyses of three-dimensional stress systems very conveniently. This is accomplished in practice by projecting into the model a beam of polarized light which has been collimated and passed through a slit, thus confining the beam to a thin sheet of light. Such a sheet will illuminate any desired plane section of the model, and in this section will appear interference fringes from which the stresses in the section may be determined. By successive examination of plane sections one may completely investigate the model. In this method the spacing of the fringes is the significant feature, rather than their order, as in previous methods. It is possible, in many cases, to determine the directions of the principal stresses at interior points as well as the maximum shear at such points. Boundary stresses are evaluated both as to direction and magnitude. Equipment for this method differs in constructional details from that employed in plane stress studies in that a source of light of higher intensity must be provided and a slit is used to restrict the beam.
Velocity Measurement of Transient Mechanical Motions
Authors: Keilien S.
Published: January 2005

Measurements of velocity of rapid non-recurrent mechanical motions by means of an oscillograph are described. Two methods of measurement are given: One by modifying the optical system of the oscillograph, and the other by employing a slotted disk mounted on mechanism under test. These methods offer practical means of time-distance relation measurements of small devices, such as spring-actuated levers, cam mechanisms, triggers, etc., whose performance would be affected due to the additional load required to operate auxiliary measuring instruments.
Effects of Heat Treatment on Field Emission from Metals
Authors: Daniel J. H.
Published: January 2005

The cylindrical electron projector tube affords a convenient means of investigating the effects of heat treatment on field emission from metals. It is found that large, unstable field currents, designated as ``anomalous'' field emission, are due to the presence of surface electro-positive impurities. As evidenced by the ``blackout'' of the twinkling projector tube patterns, these impurities may be removed from tungsten, tantalum, or molybdenum by temperatures of 2200°K or greater, but it was found impossible to remove them from nickel. While the effect of gas adsorption on anomalous field emission is relatively minor, tube pressures even as low as 10−7 mm Hg increase the frequency of ``breakdown.'' This phenomenon is probably caused by rearrangement or disruption of impurity layers, or even of the metal itself, due to positive ion bombardment. Making surfaces microscopically smooth greatly decreases the magnitude of anomalous field emission currents, and therefore the likelihood of breakdown, but cannot take the place of sufficiently severe heat treatment in removing the anomalous type of emission completely. In the course of these experiments, calculations were made which make possible the prediction of the tension on the projection tube filament necessary to prevent violent vibration of the filament as high voltages are applied to the tube. Since such cylindrical tube geometry is of common use in experimental work, the results of these calculations are given.
Ignitor Characteristics
Authors: Arnott E. G. F.
Published: January 2005

This article reports an investigation of the current and voltage characteristics of ``ignitor'' electrodes in a mercury pool rectifier (ignitron). Experiments were made on square rods of smooth homogeneous materials of various sizes and resistivities with the following results: (1) A frequency distribution curve is found for the voltage required by the ignitor which is approximately a Normal or Gaussian distribution. (2) The total current required for the ignition of an arc, divided by the perimeter is a constant, for a given material. (3) The total current required per unit length of perimeter times the square root of the resistivity is a constant. (4) For identical ignitors operated in parallel, the total current required is equal to the square root of the number of ignitors times the current required for one ignitor. (5) An expression is derived for the fraction of the total current which is useful in starting the arc and this is found to be inversely proportional to the square root of the width. This derivation is verified by the behavior of ignitors operated in parallel.
The Solution of A.C. Circuit Problems
Authors: Pipes Louis A.
Published: January 2005

Starting with the set of linear equations that determine the complex currents of a general n-mesh circuit, a method is presented for the numerical solution of the equations to determine the various mesh currents of the system.

The method presented has computational advantages over the conventional methods usually used in that only real numbers are involved in the various numerical operations and only the evaluation of second-order determinants is involved. The operations required are those of matrix multiplication and are most conveniently performed with a calculating machine. The paper is concluded by the solution of a general Y-Y circuit with a neutral return as an example of the method presented.
Glass-to-Metal Seals. II
Authors: Hull A. W. , Burger E. E. , Navias L.
Published: January 2005

This is a continuation of the work reported in 1934. The greater part of the paper is devoted to a discussion of the properties of iron-nickel-cobalt alloys, especially the composition Fe 54 percent, Ni 31 percent, Co 15 percent—called fernico—including sensitiveness to impurities and polymorphism. Three new glass-metal combinations are described, the metals being 42 percent nickel-iron, 26 percent chromium-iron, and pure iron, respectively. The strength of the glass-metal bond is discussed briefly.
Diffusion Calculations: Interrelation Between Two Solutions of the Fourier Equation
Authors: Liebhafsky Herman A.
Published: January 2005

An examination of the interrelation between the sine series solution (for a slab with sealed periphery) and the error function solution (for a semi-infinite body) of the fundamental Fourier equation has yielded the following results: (1) Distribution functions according to the two solutions begin to diverge soon after diffusion has begun. (2) The error function yields an excellent simple approximation, valid until half the material initially present has been lost, for the loss of material from a slab with sealed periphery. (3) A simple, but extremely good, approximation is given for an infinite exponential series in the region of slow convergence. (4) Two simplifications in the calculation of diffusion constants have been given. (5) While the discussion has been restricted to diffusion it is applicable, with obvious modifications, to other cases of flow governed by the fundamental Fourier equation.
Bending Settlement of a Slab Resting on a Consolidating Foundation
Authors: Biot M. A. , Clingan F. M.
Published: January 2005

The calculation of the settlement and bending of an elastic slab resting on a consolidating foundation under the action of a load concentrated on a line. Two cases are considered: first, when the slab is perfectly pervious to water, and second, when it is impervious. The problem is two-dimensional.
Emissivities and Temperature Scales of the Iron Group
Authors: Wahlin H. B. , Wright Rufus
Published: January 2005

The temperature scales have been determined for well-degassed specimens of the iron group and from these the emissivity for λ = 0.667μ is calculated. Over the range of temperatures covered the emissivity is nearly a constant except at the A3 point in iron where there is a sudden change.
D.C.—A.C. Correlation in Dielectrics
Authors: Whitehead J. B. , Eager G. S.
Published: January 2005

It has been proposed by P. Böning that the curve of the rise of continuous voltage due to the residual charge of a capacitor may be used for computation of the dielectric loss under alternating potential. The proposal has been examined in experiments on two types of capacitor, one with impregnated paper and the other with glass as dielectric. A reasonable agreement between measured and computed values was found for the glass capacitor. A wide divergence was found for each of the two impregnated paper capacitors and grounds are offered for the conclusion that the Böning proposal is not sufficient for certain types of dielectrics.
Electrostatic Electron Lenses with a Minimum of Spherical Aberration
Authors: Plass Gilbert N.
Published: January 2005

A method is suggested for the construction of electrostatic electron lenses by building equipotential surfaces whose position in space is calculated from an assumed axial potential. The calculations are carried through for examples of symmetrical and immersion lenses. The symmetrical lens chosen is the well-known one with minimum spherical aberration represented by an axial potential V(z) = V0+A exp (−Bz2) and it is shown that this lens can actually be constructed. An axial potential formed by a sum of two exponential terms is found, for suitable values of the constants, to reduce the spherical aberration to less than one-half that of the above symmetrical lens. An expression is proposed for the immersion lens with minimum spherical aberration. The aberration for this lens is approximately one-half that of the above symmetrical lens. It is shown that the usual formula for the focal length of a strong lens is merely the first term in an infinite series and that serious inaccuracies occur by not considering further terms.
Virtual Masses and Moments of Inertia of Disks and Cylinders in Various Liquids
Authors: Yu Yee-Tak
Published: January 2005

The effective mass or moment of inertia of an object in a liquid may be considerably greater than the corresponding value in vacuum. Hence many applied dynamical problems require the use of effective rather than actual values. Herein is reported an experimental method, making use of a torsion pendulum, for determining the increase or ``virtual'' moment of inertia or mass of an object due to a surrounding liquid. Actual data on disks and cylinders in water, gasoline and carbon tetrachloride are given. Experimental and theoretical results are compared where possible.
Rate of Crystal Growth in Drawn Tungsten Wires as a Function of Temperature
Authors: Robinson C. S.
Published: January 2005

Large single crystals can be grown in ``218'' and similar tungsten wires by vacuum heating at a constant temperature in the range 1900°K to 2200°K. The growth can be followed by observation of the thermionic emission pattern, using a cylindrical electron-projection tube with a fluorescent screen. The rate of growth is found to increase with temperature according to an exponential law. Crystal growth is slower in wires drawn to smaller diameter; this can be explained by the small grain hypothesis. The perfection of crystals is discussed.
The Vibration Characteristics of Nearly-Complete, ``Free-Free'' Circular Rings
Authors: Bundy F. P. , Bankes C. W.
Published: January 2005

The frequencies, frequency ratios, amplitudes of vibration, and mechanical constants of nearly-complete circular rings of various diameters and cross sections were measured and analyzed. The first six modes of vibration parallel to the plane of the ring, and the first five modes transverse to the plane of the ring, were obtained for several rings. The positions of the nodal points are tabulated. For the parallel vibration the frequency ratio fn/f1 is found to be independent of the cross section of the ring and for modes higher than the second are given accurately by the equation fn/f1=0.628(n−0.200)2 where n is the mode. The frequencies of parallel vibration are found to be given by the equation, fn = (Kn/D2) (B/m)½, where K1=0.285, K2=0.630, Kn=0.1795(n−0.200)2 (for n>2), D is the mean diameter, B the bending stiffness, and m the mass per unit length. For the transverse vibration the frequency ratios depend upon the type of cross section, but are of the general form, fn/f1=K2(A/C) [n+k(A/C)]2, for n>2. The values of K2(A/C) and k(A/C) are given in graphical form. A/C is the ratio of bending to twisting stiffness of the cross section of the ring. The frequency of transverse vibration is given by the equation, fn = [ψn(A/C)/D2] (A/M)½. The values of ψn(A/C) for a wide range of A/C values are given graphically for the first six modes. The distributions of amplitude of vibration around the rings for the first three modes of both parallel and transverse vibration are shown graphically.
Frictional Phenomena. XI: C-Solids
Authors: Gemant Andrew
Published: January 2005

THIS chapter deals with (a) the general features of plastic phenomena in solids, (b) the so-called Prandtl model, giving a basic and pictorial explanation of plastic processes, (c) the physical theories of R. Becker and G. I. Taylor, bearing a closer relation to physically measurable quantities, and (d) some experimental results illustrating the chief features of plastic flow in solids.
Steady State Currents of Electrical Networks
Authors: Waidelich D. L.
Published: January 2005

It is shown that the methods of operational circuit analysis may be extended to give the steady state current of a circuit not only in the well-known Fourier series form but also in the form of the sum function of this Fourier series. This sum function is very useful in determining the wave form of the current. Three methods of obtaining the steady state current are given along with their restrictions, and these methods involve a real integral, a finite series, and a complex integral. An example of the use of these methods is also given.
Formulas for the Inductance of Rectangular Tubular Conductors
Authors: Higgins Thomas James
Published: January 2005

Utilizing a function H(x) defined by G. Stein, formulas are derived for the inductance per unit length of rectangular tubular conductors. An example illustrates use of these formulas. A table of Stein's function is given for values of the argument x between 0 and 1 at intervals of 0.01.
Fatigue of Fabrics
Authors: Busse W. F. , Lessig E. T. , Loughborough D. L. , Larrick L.
Published: January 2005

The effect of temperature and time of application of load on the growth and the apparent ``tensile strength'' of fabrics was studied with a number of new tests. The results gave considerable information about the mechanism of failure of mechanical fabrics at low loads in service which could not be obtained with standard textile tests.

A ``fatigue'' test was developed which measured the lives of samples at elevated temperatures when subjected to a constant average load and a superimposed cyclic stress. The change in life with temperature on this test is enormously greater than the change of tensile strength with temperature. Over a considerable range the logarithm of the life under a given load is a linear function of the reciprocal of the absolute temperature, showing that the failure depends on a viscous or plastic flow within the fibers. Calculated activation energies for this flow process increase for different fibers in the order rayon, cotton, Nylon. The construction of the fabric affects the absolute life, but not the calculated activation energy. When creep is negligible, a loaded cord contracts when the temperature is raised, analogous to the Joule effect in rubber.
Specific Surface Measurements on Compact Bundles of Parallel Fibers
Authors: Sullivan R. R.
Published: January 2005

The flow of air through compact bundles of parallel textile fibers has been studied in order to obtain values of the shape factor k0 for the channels through which the flow takes place. When the fibers are cylinders and the flow is parallel to their axes, k0 is an increasing function of the porosity ε. Tables and curves showing this relationship are given. For fibers such as cotton, where the shape and size of cross section changes along the fiber length, k0 changes less rapidly with ε. Data are given for this relationship.
Frictional Phenomena. XII
Authors: Gemant Andrew
Published: January 2005

IN this chapter the following subjects are dealt with: (a) synthetic plastics, the plastic properties of which are of interest from the standpoint of molding and of permanence; (b) glasses, the plastic flow of which in the range from 400 to 600°C is important because this is the annealing range of glasses; (c) lead, in particular in connection with its use as sheath of high voltage cables; (d) electrical ionic conductivity of solid insulating materials in relation to their plastic flow resistance.
An Electron Microscope Study of Some Structural Colors of Insects
Authors: Anderson Thomas F. , Richards A. Glenn
Published: January 2005

The electron microscope has been used to study two types of structures responsible for the physical colors of insects. The iridescence of the beetle Serica sericea is due to a line grating on its wing-covers, 0.8μ between lines. The structure giving rise to the brilliant blue color of the tropical butterfly Morpho cypris is quite elaborate, consisting essentially of hundreds of vanes on each wing scale, the vanes possessing linear thickenings 0.2μ apart which reinforce the reflection of blue light. Numerous exceedingly fine markings on parts of the wing scales go down in dimensions to 60A, and some of them may be related to the chemical structure of the scales. Chemical tests show that the scales are not composed of chitin, the principal component of the external parts of most insects. It is interesting that bombardment of the scales with an intense electron beam (1000 electrons per square angstrom per second) for a matter of minutes does not appreciably affect the swelling properties of the scales in organic liquids.
Production, Concentration, and Decomposition of Ozone by Ultraviolet Lamps
Authors: Ewell Arthur W.
Published: January 2005

With the increasing use of bactericidal ultraviolet lamps it has become very desirable to have more information about the accompanying production of ozone which is the only feasible agent for protecting surfaces not exposed to direct or scattered radiation. Very little published information is available and practically all the data given in this article are new. A low pressure mercury arc lamp of the type of the Westinghouse Sterilamp gives an amount of ozone of the order of 1/100th gram per hour, corresponding to a rate of emission of energy of at least 1/100th of a watt. A gentle air motion increases the yield. All the ozone is produced within a few feet of the lamp. The rate of decomposition of the ozone after the lamps are turned off is faster the greater the surfaces compared with the volume, the higher the temperature, the higher the humidity, and the more 2537 radiation present. The most important factor, the equilibrium ozone concentration, in an enclosure of several cubic meters is proportional to the ozone produced, inversely proportional to the volume, and is reduced to about one-third when the relative humidity changes from a few percent to near saturation and to about one-half when the temperature is raised from 7° to 32°C. It is very roughly 25 percent lower if the 2537 radiation of the present Sterilamp, accompanying the short wave-length ozone radiation, is doubled.
Performance Curves for m-Derived Filters
Authors: Cunningham W. J.
Published: January 2005

For a composite filter made up of several m-derived sections, the greatest discrimination will be obtained if the values of the design parameter m for the various parts of the filter are chosen so that successive minima of insertion loss in the attenuation band are all the same. Many different low pass structures were set up and adjusted experimentally to show this type of performance. The necessary values of m and the resulting discrimination for each network have been plotted on curves, which give information also about the sharpness of cut-off. These curves are useful for the most economical design of low pass, or high pass, composite filters to meet definite requirements.
The Electrostatic Focusing of High Speed Ion and Electron Beams
Authors: Craggs J. D.
Published: January 2005

The paper gives a description of some tests carried out in preparation for the construction and development of an apparatus for artificial atomic disintegrations. The problems involved are (i) the focusing of a beam of 10–30 kv hydrogen ions from a canal-ray ion source (glow discharge type) and (ii) the behavior of a cascade acceleration tube of the Coolidge type. In particular it was necessary to know the efficiency of the latter, i.e., the ratio of output to input currents. The general properties of electrostatic focusing systems are first treated briefly, and adequate references are given to enable those interested in the problem to pursue the matter further. It is pointed out that in view of the aberrations present, the constants of our lenses cannot be accurately calculated and we have therefore concentrated our attention on presenting the results in a concise form. Several lens systems were used to focus the canal-ray beams and details are given in tables. It was found possible to focus at least 50 percent of the ion beam emerging from the canal into an area 1–2 cm in diameter at distances of 20–50 cm. Point foci could be obtained but the focused currents were low, i.e., spherical aberration was large. Similar performances could be obtained with a 6′ acceleration tube.
Analysis of Longitudinal Motions of Trains by the Electrical Analog
Authors: Pipes Louis A.
Published: January 2005

The relative motion of a train of n uniform cars and a locomotive is considered. If slack and rolling resistance are neglected, the system may be idealized to that of (n+1) masses connected by springs. To generalize the analysis it is assumed that identical shock absorbers of the dash-pot or viscous friction type are placed between the units. By considering the electrical analog of this dynamical system, its natural frequencies are determined. It is found that if the shock absorbers have a certain critical strength, no free oscillatory motion between the cars is possible. Expressions are obtained for the velocities of the several cars when the locomotive exerts an oscillatory tractive effort. By the use of the operational calculus, the response of the system when the tractive effort is impulsive is also determined.
Anisotropy of Ferromagnetic Powder Particles
Authors: Benedikt Elliot T.
Published: January 2005

Measurements of the magnetic moment of sediments of ferromagnetic particles deposited in a magnetic field show that the particles are magnetically anisotropic. The dependence of this anisotropy on the magnetic field is investigated for sediments prepared under different conditions, and its probable origin discussed.
Indexing Powder Diffraction Patterns of Isomorphous Substances
Authors: Frevel Ludo K.
Published: January 2005

Two methods of indexing powder diffraction patterns of isomorphous substances are presented: the first method depends on matching the log d values of two or more isomorphs (d being the interplanar spacing of a given reflection); the second method relates the spacing shifts Δd/d of two isomorphs to the symmetry of the particular crystal system. These methods are made practical by the publication of tabulated powder diffraction data.
Arc Cathodes of Low Current Density at High Amperage
Authors: Slepian J. , Berkey W. E. , Kofoid M. J.
Published: January 2005

From photographs, and from the marking on the electrodes, Slepian and Haverstick found that short duration arcs of 25 amperes in gases at a pressure of a few centimeters had apparent current densities at the cathode of less than 100 amperes per cm2. This is in sharp contradiction to the density of several thousand amperes per cm2 which seems to be required by generally accepted theories of the cold cathode arc. Similar results have been found up to currents of 5000 amperes, burning for 1/120 sec. with electrodes of various metals in air at less than 10-cm pressure. Apparent cathode current densities calculated from the observed marking on the electrodes were less than 1000 amperes per cm2. The markings on the electrodes were apparently produced by oxidation only, the energy density developed at the electrodes being insufficient to bring the electrode surface to the melting point in the 1/120 second duration of the arc. The circuit interrupting capacity of these short low current density arcs are found to be not less than that of short arcs at atmospheric pressure.
Operational Analysis of Non-Linear Dynamical Systems
Authors: Pipes Louis A.
Published: January 2005

An operational method of determining the free and forced vibrations of non-linear dynamical systems is presented. The method is an operational adaptation of the one developed by Lindsted and Liapounoff. The advantage of the operational procedure is that by using a table of operational equivalents, one may write the various successive approximations almost at a glance. The procedure is illustrated by applications to non-linear problems in mechanics and electricity.
Frictional Phenomena. VII
Authors: Gemant Andrew
Published: January 2005

COLLOIDAL particles present in solutions and suspensions increase the effective viscosity of the solvent. Einstein has presented the theory of this effect valid for spherical particles, and given an equation, deviation between which and experiments being due to either solvation or electric charge of the particles. Elongated particles require a further modification of the formula. The theory is being successfully applied to the study of synthetic fiber molecules, and valuable information as to the shape of the latter can be derived by viscometric measurements on colloidal solutions of such polymers.
A Theoretical Approach to the Problem of Yarn Strength
Authors: Sullivan R. R.
Published: January 2005

An idealized yarn composed of fibers with specified properties is treated analytically with the aim of determining the yarn strength at any degree of twist. The results are presented in the form of equations and curves which relate the yarn strength to the fiber properties and the degree of twist. Two cases are studied: (1) All fibers alike; (2) fiber properties variable from fiber to fiber. In the latter case the mathematical expectation of the yarn strength at any yarn cross section is obtained. It is found that the optimum twist multiplier is largely determined by the fiber length, fiber fineness, and coefficient of friction, whereas the maximum yarn strength (corresponding to the optimum twist multiplier) is more strongly dependent upon the intrinsic fiber strength than upon the other fiber properties studied.
The Phase of Arcback
Authors: Hull Albert W. , Elder Frank R.
Published: January 2005

Thyratrons of FG-41 type were tested at over-voltage for arcback in a circuit which simulates operating conditions very closely. Memory oscillograms showed the time in the cycle at which the arcbacks occurred. At a mercury-control temperature of 45°C, the distribution was nearly random, with a maximum at the time of highest negative anode voltage, and depending on voltage in the same manner as the average arcback rate, taken over a long period. When the mercury-control temperature was raised to 64°C, all the arcbacks occurred at the beginning of negative voltage application. These results are interpreted on the theory recently advanced by Kingdon and Lawton, which attributes arcback to charging up of small non-conducting particles on the surface of the anode. At low vapor pressure, where the ions remaining from the discharge have time to diffuse to the electrodes before negative voltage is applied, the charging is produced by processes such as glow discharge and field emission, which depend on voltage; hence arcback is correlated with voltage. At higher pressure, diffusion is interfered with by molecular collision, so that ions are present when negative voltage is applied. In this condition arcback occurs at the beginning of the negative cycle.
The Depth Dependence of Earth Conductivity Upon Surface Potential Data
Authors: Keck W. G. , Colby W. F.
Published: January 2005

The problem of determining electrical earth conductivity from the surface, in the case where it is a function of the depth only, is solved by a perturbation method, which formally at least, allows the unperturbed functions to be perfectly arbitrary. Numerical work, however, is restricted to those functions which are available as solutions of the so-called ``inverse'' problem, a group of which is given. Of this group the case in which the unperturbed conductivity varies exponentially is treated in detail and two examples showing the success of the method are presented. A numerical method of solving integral equations of the Laplace type, which occur in the above, is also submitted.
Large Scale Extraction of Polonium from Active Lead and Formation of Radioactive Electrode Alloys
Authors: Dillon J. H. , Street J. N.
Published: January 2005

Various possible sources of Po for industrial use are discussed and reasons for selection of active lead salts for this purpose are given. Methods of measurement of the amounts of Po present on plated metal foils and in electrode alloy are described. The RaD/Pb ratio was found to vary from 1.2×10−8 to 1.9×10−8 for various samples of active lead from the Great Bear Lake region. Methods for extraction of Po from active lead salts are discussed and a large scale plating method is described. Results of experiments on the rate of Po-plating from boiling solutions of active lead salts as related to the acid concentration, exposed foil area, foil composition, etc., are presented. Chemical methods for producing soluble active lead salts are described.

A method of introducing Po into electrode alloy is described. In a typical experiment, it was found that 94 percent of the Po introduced into the melt was retained in the final alloy. Contact radiographs of electrode alloy samples showing the affect of various heat treatments and surface condition are presented.
Streamering in Negative Corona
Authors: Bennett Willard H.
Published: January 2005

Corona from sharp points in air can be divided into two ranges, a diffuse range and a streamering range, this division being applicable for each polarity of discharge although the details are different for the two polarities.
Magnetization Near Boundaries
Authors: Wakelin James H.
Published: January 2005

Magnetic measurements on ring samples of silicon iron, commercially pure nickel, and low carbon steel, in the thickness range 3.8×10−3 to 38.1×10−3 cm, indicate that it is possible to detect surface stray flux contributions to the total magnetization by comparing hysteresis loops obtained at a maximum applied field of 4 oersteds. The magnetic quality appears to be insensitive to changes of specific surface though a progression of properties with sample thickness suggests the presence of a low permeability surface layer.