bluuebunny/crossref_metadata_2025_split huggingface dataset:
Geometrical Factors Affecting the Contours of X-Ray Spectrometer Maxima. II. Factors Causing Broadening
Authors: Alexander Leroy 
Published: April 2005

By applying Stokes' Fourier transform method for the analysis of diffraction maxima it is shown that the pure diffraction contour generated by a crystallite size distribution is apt to be approximated rather closely by the function 1/(1+k2φ2). In the case of the x-ray spectrometer this pure diffraction contour is broadened significantly by the action of the following five geometrical factors: (I) the x-ray source width, (II) flat rather than curved sample surface, (III) vertical divergence of the x-ray beam, (IV) penetration of the sample by the beam, and (V) the receiving slit width.
The broadening of the pure diffraction contour due to the action of each of the five factors and the breadth of the final contour generated by the instrument can be deduced by employing the convolution approach suggested by Spencer. The effect of each instrumental factor is expressed by a convolution equation of the form fi(φ)= ∫ −∞+∞Wi(ζ)fi−1(φ−ζ)dζ,in which φ is the angular displacement from twice the ideal Bragg angle, 2θ, fi−1 is the contour before the action of the ith geometrical factor, Wi is the form of the ith geometrical factor, and fi is the contour after the action of Wi on fi−1. Starting with a pure diffraction contour of the form 1/(1+k2φ2), generalized broadening curves are derived for the effect of each of the five geometrical factors. Using these curves it is possible to predict the breadth of the final diffraction contour generated by the spectrometer from an initial contour of any breadth.
A Three-Stage Electron Microscope with Stereographic Dark Field, and Electron Diffraction Capabilities
Authors: Haine M. E. , Page R. S. , Garfitt R. G. 
Published: April 2005

An electron microscope is described in which a range of magnifications between 1000 and 100,000 times can be covered continuously. This is achieved through the use of an intermediate projector lens.
The principles of design are briefly discussed and the construction of the microscope and the high frequency-operated 100-kv power unit is dealt with in some detail. The instrument is provided with objective apertures to enhance image contrast and to permit operation with dark field illumination.
Data is given relating to the electron optical system and it is shown how the instrument can be used to obtain electron diffraction patterns characteristic of small areas of a specimen under microscopic observation. The alignment procedure is briefly described and some typical micrographs are shown.
The Theory ofNCoupled Parallel Antennas
Authors: King Ronold 
Published: April 2005

The integral-equation theory of coupled antennas developed by King and Harrison, Tai and Bouwkamp for two- and three-coupled antennas is generalized to any number of units symmetrically arranged around a circle. The case of four antennas at the corners of a square is discussed in detail. Application to cage and corner-reflector antennas is indicated.The analysis of N parallel antennas arranged in line is carried out to determine the driving voltages required to maintain specified currents. It is shown that the inverse problem cannot be carried out in general except as a problem in simultaneous integral equations, but that the special conditions obtaining for half-wave dipoles permit an approximate analysis for the currents with given voltages. This is carried through.
Complex Stressing of Polyethylene
Authors: Hopkins I. L. , Baker W. O. , Howard J. B. 
Published: April 2005

Polyethylene of such molecular weight and structure that it readily fibers or cold draws to 300–600 percent elongation by usual uniaxial, tensile stressing may react quite differently under biaxial tension. When biaxial tension in 1:1 ratio is applied to a diaphragm, some polymers show brittle fracture with &lt;20 percent elongation at break. However, if the average molecular weight of such polyethylenes is shifted upward by crude fractionation, or an initially higher average is used, the polymers orient under complex stresses. Then, they usually elongate several hundred percent before rupture. Variations in crystallinity are also significant, although most technical polyethylene soon attains at room temperature enough crystallinity so that this factor does not cause big differences.
Although the whole study is so far preliminary, x-ray scattering of stressed samples suggests that preferred glide on certain crystallite planes tends to occur as the yield point approaches. These are such as to inhibit smooth alignment of the long chain axis in the direction of stressing. This could lead to brittleness.
Apparatus for complex stressing of sheets and tubes is described. Strains are taken from coordinates printed on the sample by the silk screen process. High speed stressing was also observed. The speed of retraction of amorphous polyethylene chains approaches that of rubber.
Wettability, a Function of the Polarizability of the Surface Ions
Authors: Sonders L. R. , Enright D. P. , Weyl W. A. 
Published: April 2005

The wettability of crystals, glasses, and even of water itself can be temporarily decreased by bringing ions of high polarizability into their surfaces. Base exchange experiments are described where the hydrogen ions present in the surface layers of bentonite (a clay mineral of high exchange capacity) and of a soda-lime glass are replaced by different cations. This substitution seems to have no particular effect on the hydrophilic and rheological properties of the carriers as long as their surfaces are kept in contact with water. After drying, however, the surfaces which contain ions of high polarizability become hydrophobic, at least temporarily. A porous clay film will no longer absorb water instantaneously after having been treated with Ni2+, Mn2+, Hg2+, or similar ions with incomplete outer electron shells. Contact angles with water up to 70° could be observed for a short period for Hg2+ and Pb2+ clays.
Glass capillary tubes which have been treated with non-noble gas-type ions show a capillary rise which is much smaller than that observed with the tubes which have been treated with HCl and water only. This depression of the capillary rise, too, is temporary and can be observed only if the glass wall has been thoroughly dried previous to the experiment and if the capillary rise is measured in the upward direction.
An explanation is presented for these and allied phenomena on the basis of the polarization of ions in the strongly asymmetrical forcefields of interfaces. The experiments are correlated with the hysteresis of the contact angle and with observations concerning adhesion phenomena and catalytic activities of heavy metal ions at interfaces.
Emulsion Polymerization with Ultrasonic Vibration
Authors: Ostroski A. S. , Stambaugh R. B. 
Published: April 2005

Emulsion-type polymerization reactions have been accelerated by irradiation with ultrasonic energy.
A magnetostriction oscillator at 15 kc gave essentially the same results as a piezoelectric oscillator at 500 kc. The rate of formation of polystyrene was doubled and higher final yields obtained using about 0.03 watt of vibrational power per cc of latex. Experiments were made to separate local heating effects from those due to vibrational energy.
A thermostatted stainless steel cell was developed for irradiating butadiene emulsions under pressures up to 60 p.s.i. About ½ watt of vibrational power per cc of latex doubled the rate of reaction for GR-S, Redox, and Redsol formulas.
The ultrasonic intensity apparently must exceed a critical value before any appreciable accelerative effect is observed. Above the critical intensity, the time to reach a given yield of polymer is approximately inversely proportional to the power used.
A Non-Destructive Mechanical Test for Animal Fibers
Authors: Burte Harris M. 
Published: April 2005

The slope of the force-extension curve in the Hooke's law region can be measured non-destructively, for animal fibers, at three to fifteen minute intervals. The change of this Hookean slope with time is used to follow the course of the heterogeneous reaction between wool and a reagent.
Data are presented on the interaction between concentrated neutral salt solutions and wool fibers. These results indicate that wo processes occur: (a) Relatively rapid hydration or dehydration of the fiber until equilibrium with the activity of water in the salt solution is attained; (b) Relatively slow absorption of salt ions by the fiber. Very concentrated salt solutions dehydrate the fiber so completely that absorption of salt ions is not possible. Swelling experiments and experiments involving other mechanical properties confirm these hypotheses. The interaction between wool fibers and aqueous solutions of large organic molecules follows a similar pattern.
Some Theoretical Considerations of Dynamic-Property Data on Textile Specimens
Authors: Lyons W. James 
Published: April 2005

1. Early stretch-vibrometer data, of quite extensive character, on the frequency dependence of the internal friction μ of a Nylon monofil, has been found to conform to the relation μ=[μ2/(1+ω2τ22)]+μ3which was deduced independently by Tobolsky and Eyring from considerations of molecular structure. Among other constants evaluated was the relaxation time for the secondary-bond network τ2, which was found to have the value 9.3 sec.
2. By more sensitive graphing methods than had been used heretofore, it was confirmed by the Nylon data that the hyperbolic relationship between resonant frequency ω0 and internal friction μ holds equally as well as the foregoing equation. The two relationships are shown to be nearly equivalent in the present experimental range. On evaluation of graphical parameters, the equation μω0=2.47×109 ergs/cm3 was obtained.
3. Using the same graphical method with a set of data on 11/4/2 cotton cord the relation (μ+0.9)ω0=7.05 ×109 ergs/cm3 was established.
Equation of State for High Polymers
Authors: Spencer R. S. , Gilmore G. D. 
Published: April 2005

In a former paper the authors suggested the following equation of state, (P+π)(V−ω)=RT, where π is the internal pressure (or cohesive energy density) and ω is the volume at absolute zero. It was found that this equation was in good agreement with data on the thermal expansivity and isothermal compressibility of polystyrene.
The present paper reports isothermal compression measurements on polymethyl methacrylate, polyethylene, cellulose acetate-butyrate, and ethyl cellulose at temperatures within the fabrication range. The above equation of state is shown to apply equally as well to these thermoplastics as to polystyrene and values are given for the constants. The usefulness of this relationship is illustrated in a brief discussion of some phases of the injection molding process.
A Graphical Analysis of the Interference Patterns of an Elevated Ultra-High Frequency Antenna under Conditions of Atmospheric Stratification
Authors: Abbott F. R. , Fisher C. J. 
Published: April 2005

Analytical computation of the detailed lobe structure of an elevated meter or centimeter band antenna for a standard atmosphere is quite tedious. In case there are discontinuities in the gradient of refractive index the analysis becomes hopelessly involved.This paper presents a straightforward method of graphical analysis for the optical region, equally applicable to a standard or stratified atmosphere.
An Extension of Wiener's Theory of Prediction
Authors: Zadeh Lotfi A. , Ragazzini John R. 
Published: April 2005

The theory of prediction described in this paper is essentially an extension of Wiener's theory. It differs from the latter in the following respects.
1. The signal (message) component of the given time series is assumed to consist of two parts, (a) a non-random function of time which is representable as a polynomial of degree not greater than a specified number n and about which no information other than n is available; and (b) a stationary random function of time which is described statistically by a given correlation function. (In Wiener's theory, the signal may not contain a non-random part except when such a part is a known function of time.)
2. The impulsive response of the predictor or, in other words, the weighting function used in the process of prediction is required to vanish outside of a specified time interval 0≤t≤T. (In Wiener's theory T is assumed to be infinite.)
The theory developed in this paper is applicable to a broader and more practical class of problems than that covered in Wiener's theory. As in Wiener's theory, the determination of the optimum predictor reduces to the solution of an integral equation which, however, is a modified form of the Wiener-Hopf equation. A simple method of solution of the equation is developed. This method can also be applied with advantage to the solution of the particular case considered by Wiener. The use of the theory is illustrated by several examples of practical interest.
The Role of Cathode Temperature in the Glow Discharge
Authors: Jacobs Harold , Martin Jack 
Published: April 2005

Experiments were conducted to study the role of the temperature of oxide-coated cathodes in the glow discharge of argon, neon, and mixtures of neon and argon, and mercury vapor and argon.
It was found that for tubes without mercury present, in the region of cathode temperature between 300°K and 750°K: (1) The sparking potential falls with increasing cathode temperature. (2) The regulation voltage rises with increasing cathode temperature. For argon and mercury vapor, the regulation voltage falls with increasing cathode temperature. The action here is attributed to metastable states of inert gas. (3) The current density in the glow discharge decreases with increasing cathode temperature. This, too, is attributed to the action of metastable states. (4) The minimum sustaining current in a glow discharge is found to decrease with increasing cathode temperature and rise with increasing pressure. (5) The current density in the glow discharge varies roughly linearly with pressure, or at a slightly higher rate, in contrast with the space-charge derivations which claim a variation with pressure squared. (6) The regulation voltage tends to rise very slightly at lower pressures.
Microwave Measurements of the Dielectric Properties of Gases
Authors: Birnbaum George , Kryder S. J. , Lyons Harold 
Published: April 2005

An accurate and sensitive method for measuring the complex dielectric constant (ε′-iε″) of gases in the microwave region is described and critically investigated for sources of error. A resonant-cavity method is used in which the cavity response curve is displayed on a cathode-ray tube. The variation of resonance frequency and Q of the cavity when filled with gas are determined from measurements with two frequency markers. The equipment is operated at 9000 Mc, and cavities with Q's of 1×104 are used. In the determination of ε′-1 (dimensionless) of very low loss gases, an accuracy of 0.4 percent and a sensitivity of 4×10−7 can be obtained. In the determination of the loss factor ε″, an accuracy of 2 percent and a sensitivity of 5×10−7 can be obtained. This method is useful for measuring dispersion and absorption in solids and liquids as well as gases.
Experimental results are given and briefly discussed for ε′-1 of O2, N2, CO2, He, and air, and for ε″ of NH3 as a function of pressure up to 20 cm Hg.
Numerical Computation of Neutron Distribution and Critical Size
Authors: Thompson A. S. 
Published: April 2005

A numerical procedure is presented for the calculation, by diffusion theory, of the critical size of a nuclear reactor, and of the time-dependent distribution of neutrons in the reactor as a function of position (one-dimensional space) and neutron energy. The partial differential equations for diffusion theory are approximated by a system of ordinary differential equations, for which a stepwise convergent solution for neutron distribution is obtained. The critical size of the reactor is found from a comparison of the magnitude of the slowing down densities of the thermal and fission energy limits. The procedure is applied, by way of example, to a reflected sphere.
This method for calculating neutron distribution is thought to be new in that an integration technique is developed and used for the solution instead of differentiation. Primarily because of this, the convergence to the correct solution is rapid. In a one-dimensional space all physical quantities can be considered as either continuous or discontinuous functions of both position and energy. Such items as fission and nonproductive capture in the slowing down range can be included as part of a standardized procedure. Certain transient and steady-state perturbation like motion of control rods can be studied.
Volta Potentials of the Copper-Nickel Alloys and Several Metals in Air
Authors: Uhlig Herbert H. 
Published: April 2005

Volta potentials of various metals approximately parallel the emf series. Metals abraded wet are more noble than when abraded dry, the transition metals changing an average of 0.28 volt compared with 0.07 volt for the nontransition metals. This owes possibly to the greater tendency of the transition metals to chemisorb oxygen, especially in the presence of moisture. All metals change in the noble direction upon aging in air, the average value being 0.3 volt after six days.
Potentials for copper-nickel alloys, plotted with composition, fall on a sigmoid curve, whereas potentials for composite electrodes made up of separate nickel and copper areas are linear with percent area of nickel exposed. Commercial nickel-copper alloys above 50 percent nickel age more rapidly than laboratory alloys. The cause may lie in deoxidizers like magnesium or aluminum, present in commercial alloys, but absent in the laboratory alloys. This suggests a nondestructive method for detecting impurities of this kind in metals.
Ultrasonic Propagation in Liquids under High Pressures: Velocity Measurements on Water
Authors: Holton Gerald 
Published: April 2005

The problem under discussion is the velocity of ultrasonics in liquids, specifically water, at various temperatures and high pressures. This report deals with the apparatus, and with some representative results obtainable with it.
The electrical apparatus makes use of a presentation unit (Dumont 256 or A/R 'scope) which synchronizes the sequence of operations by internally generated trigger signals at low repetition rates. Three- to five-microsecond pulses at controllable amplitude and approximately 15 Mc/sec carrier frequency are imposed on an X-cut quartz crystal which has been placed inside a pressure-supporting vessel containing the test sample. The resulting ultrasonic pulses in the liquid are reflected back and forth over a definite path length between the transducer and a mirror. After amplification in a receiver strip the complete echo-pattern becomes available for visual comparison on the presentation screen. The timed relative delay (and the measurable amplitude differences) between successive pulses furnish data for velocity (and attenuation) measurements when certain corrections are attended to.
Representative data are given for the velocity in water (to 0.1 percent) as a function of pressure to about 6000 atmospheres. From the data on water, information is derived on the temperature coefficient of sound velocity and on the ratio of specific heats at increasing pressures. The latter results are compared with those obtained directly from purely static experiments, and the advantages of the ultrasonic measurement technique for the derivation of some of the thermodynamic coefficients are cited.
Evaporation Rate of Liquid Helium. I
Authors: Wexler Aaron 
Published: April 2005

In connection with a study of the emissivity of metals at low temperatures, a quantitative analysis has been made of the factors involved in the design of storage containers for liquid helium. Experiments confirm the analysis, which has resulted in an exceedingly simple liquid-nitrogen-protected liquid helium container having a helium evaporation rate of 1 percent per day.
The hemispherical emissivity of mechanically polished copper at 4.23°K was determined for blackbody radiation. For radiation corresponding to that emitted by a blackbody at 77.1°K and 297.1°K, the measured emissivities are 6.9×10−3 and 1.29×10−2, respectively. These data are discussed in relation to the recent theoretical work of Reuter and Sondheimer.
The heat of vaporization of helium at 4.228°K was determined to be 4.93 cal g−1, in substantial agreement with the data of Dana and Kamerlingh Onnes. Kistemaker's thermodynamic considerations questioning the accuracy of these data are evaluated in terms of the new determination.
Latex Particle Size from X-Ray Diffraction Peaks
Authors: Yudowitch K. L. 
Published: April 2005

A high resolution camera was constructed for small angle x-ray scattering. Measurements with this camera on Dow latex 580G exhibit a number of concentric rings. Each ring is associated with a theoretical maximum of scattered intensity predicted by the spherical x-ray form factor corrected for packing.
The particle diameter is then computed from the position of each ring. Twenty measurements yield a diameter of 2780A with a probable error of less than ±1 percent.
Internal Friction of Ferromagnetic Materials
Authors: Ferro A. , Montalenti G. 
Published: April 2005

It is common knowledge that in cyclically stressed ferromagnetic materials an energy loss due to internal friction is observed; this part of loss disappears when the material is brought to saturation or above the Curie temperature. It is also known that a stress, applied to a ferromagnetic material, produces a motion of Weiss domains from their rest position.
The scope of this paper is to verify experimentally the following hypothesis: in cyclically stressed ferromagnetic materials, energy loss because of magneto-elastic internal friction is induced by a domain motion due to the applied stress itself.
The ratio Ir/Is (where Ir=residual induction, and Is=saturation intrinsic induction) has been chosen as an index of the domain position; its measure has been carried out by normal ballistic method on a permeameter rigged with a torsion applying device.
Energy loss was measured by means of a torsion pendulum; a coil allowed the saturation of specimen in order to separate magneto-elastic from purely mechanical losses. Plotting curves of Ir/Is and of magneto-elastic losses as a function of applied stress and comparing them for each tested material, it has been found that they, besides having the same shape, show abrupt slope variations at practically the identical value of stress. It has further been observed that a specimen presenting only a low percent variation of Ir/Is ratio (i.e., in which domains had slightly moved from their rest position) showed also moderate magneto-elastic losses. These results appear to confirm assumptions made about the magneto-elastic internal friction in ferromagnetic materials. The reason why motion of domains takes place in an essentially irreversible way still remains unknown.