bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pressure Response in Supersonic Wind-Tunnel Pressure Instrumentation
Authors: Ducoffe Arnold L. 
Published: April 2005

In the development of high-speed aircraft, rockets, missles, etc., wind-tunnel pressure measurements at supersonic velocities are necessary to determine certain aerodynamic characteristics. Because of the lack of knowledge concerning the proper choice of parameters in the design of pressure instrumentation, the response time has been known to exceed the running time in the case of the intermittent tunnel. Pressure systems consisting of an orifice, a capillary tube, a length of connecting tubing, and a pressure-sensitive element connected in series are analyzed. The time required for the pressure in the pressure-sensitive element to reach within 1 percent of the equilibrium pressure is defined as the response time of the system. Experiments are conducted to determine the effect of the various geometric and dynamic parameters on the response time. Analytical solutions of the flow equations by numerical integration are carried out for the special case of a length of capillary tubing connected to the pressure-sensitive element for three different inside diameters.
The data indicate that the response time can be maintained within acceptable limits for present-day supersonic wind-tunnel installations by proper choice of the geometric and dynamic parameters. The agreement between theory and experiment, being quite satisfactory for the special case solved analytically, indicated that the approximations in the derived flow equations are justified.
On the Diffusion of Decaying Particles in a Radial Electric Field
Authors: Keilson Julian 
Published: April 2005

The diffusion of charged particles in the presence of a radial inverse-square electric field is difficult to treat in any general manner. It is possible, however, to treat steady-state radially symmetric flow in such a field. There may then be deduced, from the radial distributions obtained, a function, γ, which provides an important description of steady-state flow from a point source in the radial field. The important point is made that the function γ obeys the differential equation adjoint to that describing time-independent diffusion in the given field.
The physical problem treated is of specific interest to transistor theory, but it is hoped that some of the techniques used in treating the problem are of more general interest.
Exact Interpolation of Band-Limited Functions
Authors: Kohlenberg Arthur 
Published: April 2005

A general formula is derived for the spectrum of a multiply-periodic, amplitude modulated sequence of pulses. The result is used to show that a function which lies in a frequency band (W0, W0+W) is completely determined by its values at a properly chosen set of points of density 2W. This verifies a supposition commonly accepted in communication theory.
The well-known, exact interpolation formula for a function f(t) in a band (O, W) is f(t)=Σnf(n/2W)sinπ(2Wt−n)π(2Wt−n). The function is thus determined by its values at a set of evenly spaced points ½W apart.
For a function f(t) in a band (W0, W0+W) it is shown that an exact interpolation formula is f(t)=Σn[f(n/W)s(t−n/W)+f(n/W+k)s(n/W+k−t)]in which k is subject to weak restrictions and s(t)=cos[2π(W0+W)t−(r+1)πWk]−cos[2π(rW−W0)t−(r+1)πWK]2πWtsin(r+1)πWK+cos[2π(rW−W0)t−rπWk]−cos[2πW0t−rπWk]2πWtsinrπWk. Thus, the function is determined by its values at a set of points of density 2W, but the points consist of two similar groups with spacing 1/W, shifted with respect to each other.
Shapes of Floating Liquid Zones between Solid Rods
Authors: Keck P. H. , Green M. , Polk M. L. 
Published: April 2005

The present paper seeks to describe the shapes of liquid floating zones between solid rods of silicon and of germanium and to discuss stability conditions. The shapes were deduced from the equation given by Laplace, p=γ(1/R1+1/R2),where p indicates the pressure difference across the surface membrane of a liquid at any point, R1 and R2 are the principal radii of curvature at that point, and γ is the surface tension of the liquid.
The floating liquid zone is analyzed within a wide stability range. Its dimensions were theoretically determined and experimentally confirmed.
The Electron Microscopy of Photographic Grains. Specimen Preparation Techniques and Applications
Authors: Hamm F. A. , Comer J. J. 
Published: April 2005

Several electron microscopical specimen preparation techniques are described, including two replica techniques. The most important specimens utilize the thin film of the silver-gelatin complex which exists as a tightly fitting skin around the photographic grains. This relatively inert and insoluble complex is referred to as the combined envelope; a study of this structure is given.
Latent image centers are enlarged in several ways so as to be readily resolvable in the electron microscope. After this partial development the matrix or intergrain gelatin is removed and the grains are fixed. The final specimen consists of developed centers retained by the combined envelope.
Applications of the replica technique to grain shape, size distribution, and growth nature of photolytic silver are given. Utilization of the combined envelope in conjunction with the special development techniques to provide information which substantiates independent sensitometric data is also demonstrated.
Quasi-Degenerated Modes in High-ε Dielectric Cavities
Authors: Schlicke H. M. 
Published: April 2005

This paper deals with resonance effects in circularly cylindrical solid bodies of high-ε dielectrics such as titanates, these bodies being either not metallized or partly or fully metallized by fired-on silver. The high dielectric constant has two pronounced effects:
(a) Miniaturization, a linear reduction in size in the order of magnitude of 1/100, and
(b) Realization of boundary conditions approaching infinite wave impedance.
All four combinations of radial and axial wave impedance being zero (metallized) or infinite (interface dielectric/air) are investigated mathematically and experimentally. Special consideration is given to degenerated modes; that is, modes for which the axial dimensions of the cavity do not contribute to the resonance wavelength. Because of the inherent magnetic leakage through the dielectric, this is only conditionally true. These modes are therefore termed quasi-degenerated.
In contrast to conventional cavity theory dealing only with metallic boundaries, quasi-degenerated TE modes are realizable; namely, if the faces of the cylindrical cavities are not metallized. These cavities can be tuned by introducing magnetic rods into them or by application of conductive disks outside of them in the proper position.
A novel type of antenna can be evolved from the TE010∞∞ mode, comprising a dielectric spiral encircling a magnetic rod.
In many cases the relatively high temperature coefficient, dissipation factor, and noise level prevent for the time being the potential application of these high-ε dielectrics.
Viscoelastic Properties as Functions of the Distribution of Activation Energies
Authors: Lyons W. James 
Published: April 2005

1. Assuming that the elementary molecular deformation process conforms to the Maxwell model, and that the molecular elastic force Gi and viscous force ηi are functions (of unspecified forms) of the free energy of activation F*, the following expressions for the dynamic modulus Gd and dynamic viscosity (internal friction) ηd are obtained: Gd=1A ∫ 0∞ω2τi2Giφ(F*)ω2τi2+1dF*,and ηd=1A ∫ 0∞ηiφ(F*)ω2τi2+1dF*,where A=area of sample, τi=Gi/ηi, ω=vibration frequency, and φ(F*)dF*=the number of elementary processes having activation energies lying between F* and F*+dF*.
2. By employing an expression relating the relaxation time τi with F* for the elementary process, and adopting the so-called ``box'' distribution of relaxation times, the following explicit form for the distribution of activation energies is deduced: φ=const(1/kTF*−1/F*2),where k=Boltzmann's constant and T=absolute temperature. When the box distribution, as represented by this explicit form for φ, is introduced into the foregoing expressions for Gd and ηd, the integrated results are found to predict temperature and frequency dependencies which are in gratifying agreement with experiment.
Synthesis of Unbalanced RLC Networks
Authors: Weinberg Louis 
Published: April 2005

A method is demonstrated for synthesizing an unbalanced RLC network with lossy coils, i.e., each inductance has an associated series resistance. The network realizes a minimum phase transfer function whose numerator and denominator are of degree not higher than the third and fourth, respectively, and whose poles and zeros may lie anywhere in the left half of the complex frequency plane. It is shown that in many cases higher degree functions may be realized as one network. For a transfer function of arbitrary degree, factoring into component transfer functions is carried out, each component having the above characteristics; the components are then realized separately and isolated from each other by vacuum tubes supplying gain.
The method makes use of the following new features:
1. A breakdown of a Hurwitz polynomial into two Hurwitz polynomials so that a division by one of them yields a sum of unity plus a positive real RLC function, each of whose partial-fraction terms (complex poles taken in pairs, or course) is positive real.
2. An application of a network theorem which divides the desired network into two networks, thus simplifying the synthesis problem.
3. A method of zero shifting to any point in the left half-plane with at least one pair of complex poles.
A further advantage of the procedure is that the network may be designed to possess input and output shunt capacitances so that tube capacitances may be automatically provided for.
Internal Friction of Quartz
Authors: Alers George A. 
Published: April 2005

The internal friction of quartz was studied by measuring the logarithmic decrement of a bar vibrating in resonance at its fundamental mode at 21 kilocycles per second and at its second harmonic mode at 42 kilo-cycles per second as a function of temperature from 200°C to 440°C. The logarithmic decrement was found to rise rapidly to a maximum of 16×10−5 at about 240°C, then fall slowly to a minimum of about 8×10−5 at about 350°C, and then rise rapidly up to and beyond 460°C. The high temperature portion shows a temperature hysteresis in which the cooling curve is lower than the heating curve. Furthermore the magnitude and, to a certain extent, the position of the peak may depend upon previous history but heating in a vacuum can reduce the logarithmic decrement curve to a reproducible one, independent of room temperature handling and thermal gradients (up to 1.5°C/cm) or stress amplitudes (up to 10 g/mm2) applied at higher temperatures.
The measured curve can be considered as the sum of two relaxation peaks and an exponential curve. One peak has an activation energy of 27.2×103 calories per mole, and the other, 12.6×103 calories per mole. The exponential curve appears to be characterized by an activation energy of about 22×103 calories per mole but may vary with heat treatment.
Stability Investigation of the Nonlinear Periodic Oscillations
Authors: Hayashi Chihiro 
Published: April 2005

The stability of the nonlinear periodic oscillations is discussed by solving a variational equation which characterizes small variations from the periodic states of equilibrium. This variational equation leads to a linear equation in which the coefficient is periodic in the time. If all solutions of this equation are bounded, then the oscillation is said to be stable, otherwise it is unstable. In order to establish the stability criterion, the characteristic exponents for the unbounded solutions are calculated by Whittaker's method. Then, the generalized stability condition is derived by comparing the said characteristic exponents with the damping of the system considered. Since the solutions of the variational equation have the form: eμτ[sin (nτ−σ)+…], our stability condition is secured not only for the unbounded solutions having the fundamental frequency (n=1), but also for the unbounded solutions with higher harmonic frequencies (n=2, 3, 4, …). Hence the generalized stability condition obtained in this way is particularly effective in studying the oscillations in which the higher harmonics are excited. Finally our investigation is compared with one of the stability conditions derived by Mandelstam and Papalexi for the subharmonic oscillations.
In the Appendix, the characteristic exponents are calculated at some length for the unbounded solutions of a variational equation in which the periodic coefficient involves sine series as well as cosine series.
Attenuation in the Shock Tube
Authors: Emrich R. J. , Curtis C. W. 
Published: April 2005

By timing the successive arrivals of a shock at stations placed along the channel of a shock tube, measurements have been made of the decrease in shock velocity with travel. These measurements were carried out for shocks moving into air at atmospheric pressure.
The attenuation per unit length of travel is greater for stronger shocks and in smaller tubes. Representing distance along the tube by x and using fractional increase in pressure across the shock, (P−P0)/P0=z, as a measure of shock strength, the dimensionless quantity R(dz/dx)/z is found to lie in the interval (3.5±2) ×10−4 for shocks ranging in strength 0.1&lt;z&lt;1.0 and in tubes of hydraulic radius 0.30&lt;R&lt;3.80 cm. It is believed that this attenuation is due to wall interaction rather than to nonideal rupture of the diaphragm. However, the exact physical nature of this interaction has not as yet been determined.
Temperature Coefficients of Non-Newtonian Viscosity at Fixed Shearing Stress and at Fixed Rate of Shear
Authors: Bestul A. B. , Belcher H. V. 
Published: April 2005

Viscosity decreases with increasing shearing stress or rate of shear in the non-Newtonian flow of high polymeric systems. It is shown that it follows from this fact that the variation of viscosity with temperature is greater at fixed shearing stress than at fixed rate of shear.
For such systems, it is shown experimentally that the variation of viscosity with temperature at fixed shearing stress is independent of shearing stress. However, the variation at fixed rate of shear is always less than that at very low shearing stress, and decreases with increasing rate of shear.
This behavior is reproduced by Eyring's hyperbolic sine flow equation, which is the antecedent for most other, more adequate, non-Newtonian flow equations. However, this equation is shown to be inadequate in that it predicts incorrect values of shearing stress for the occurrence of non-Newtonian behavior.
Anomalous Viscous Flow at Very Low Rate of Shear and Small Shearing Stress
Authors: Bergen J. T. , Patterson W. 
Published: April 2005

Fluid suspensions of a solid phase in a liquid, for example, paints and printing inks, have been presumed to exhibit anomaly of flow at very low rate of shear. The consistency characteristics of such materials require an experimental shear rate and shear stress much lower than has heretofore been reported.
This paper describes a translated cylinder, or translational, viscometer of a modified Pochettino type, which possesses a shear stress sensitivity of 5×10−3 dyne/cm2, and a shear rate sensitivity of 1×10−4 sec−1. A rubber Latex of high solids content exhibited no anomaly of flow within this range of sensitivity. A rubber dissolved in organic solvent was observed to approximate a Bingham material of 0.05-dyne/cm2 yield value, while a gum tragacanth suspension in water exhibited a yield value of 0.4 dyne/cm2 with marked post-yield anomalous flow. Household paints exhibited yield value ranging from zero to 6 dyne/cm2. These yield values were related to leveling-out of brushmarks, and to sagging or ``curtain,'' except for examples exhibiting marked thixotropic behavior. Industrial organosol coatings likewise possessed yield values ranging up to 5 dyne/cm2 which were related to leveling characteristics. These yield values agree with those postulated by Waring from consideration of the forces of leveling of brushmarks. They are considerably smaller than those reported in the literature from extrapolation of flow curves from much higher rate of shear.
Nonequilibrium Thermodynamics
Authors: Hall Newman A. 
Published: April 2005

The foundations and implications of the concepts essential to the thermodynamic analysis of nonequilibrium systems are investigated. Following a review of the background developments in irreversible thermodynamics the concept of thermostatic isolation is introduced. This provides a conceptual device whereby a thermostatic state may be established for any nonequilibrium system and a means of justifying extended use of basic relations of classical thermodynamics or thermostatics.
The conventional development of the form of entropy production is outlined. This in general is the sum of extrinsic entropy production and intrinsic entropy production. The former occurs as the sum of products of generalized diffusion effects and property gradients and is the result of interactions with discrete adjacent systems. The latter occurs as the sum of products of generalized affinities and generalized reaction rates and is the result of interaction between geometrically coincident overlapping systems. Between the diffusion effect and gradients of extrinsic entropy production generally occur linear relations with phenomenological coefficients subject to the Onsager reciprocal relations. The intrinsic entropy production occurs as a relaxation phenomenon developed from the first-order relaxation between the affinity and the displacement of the reaction from equilibrium.
The relation of the ultimate limits of applicability of thermodynamics to the uncertainty in establishing thermostatic state under conditions of microscopic fluctuations is discussed.
Determination of Reflection Coefficients and Insertion Loss of a Wave-Guide Junction
Authors: Deschamps Georges A. 
Published: April 2005

Reflection and transmission coefficients are important parameters of a wave-guide junction. It is shown that these parameters in phase as well as in magnitude may be read directly from a graph. A short-circuit is moved in one of two wave guides that are connected by the junction, and the corresponding reflection coefficient is measured in the other wave guide as in a standard method. The positions of the short-circuit, however, are taken equally spaced every ⅛th of a wavelength. When plotted in the complex plane, the corresponding reflection coefficients fall on a circle and the chords joining opposite points intersect at a point that is simply related to the desired parameters.
When very accurate measurements are desired, 8 or even 16 short-circuit positions spaced at116th or132th wavelength can be used. The quality of the chord intersection then gives a control of the experiment by showing systematic or random errors. When the intersection is not perfect, because of random errors, a method of averaging is described that reduces these errors.
A Set of Principles to Interconnect the Solutions of Physical Systems
Authors: Kron Gabriel 
Published: April 2005

A set of principles and a systematic procedure are presented to establish the exact solutions of very large and complicated physical systems, without solving a large number of simultaneous equations and without finding the inverse of large matrices. The procedure consists of tearing the system apart into several smaller component systems. After establishing and solving the equations of the component systems, the component solutions themselves are interconnected to obtain outright, by a set of transformations, the exact solution of the original system. The only work remaining is the elimination or solution of the comparatively few superfluous constraints appearing at the points of interconnection.
The component and resultant solutions may be either exact or approximate and may represent either linear or, with certain precautions, nonlinear physical systems. The component solutions may be expressed in numerical form or in terms of matrices having as their elements real or complex numbers, functions of time, or differential or other operators, etc. Boundary value, characteristic value, and time-varying problems of partial differential equations, as well as problems in ordinary differential equations and algebraic equations may be solved in this manner.
The method shown may be extended and generalized so that one can tear apart and afterward reconstruct the solution of extremely large or highly intricate physical systems, often without calculating any inverse matrices at all and always without carrying along unduly large matrices. This extension and generalization of the method is analogous to building skyscrapers by erecting first a steel framework and only afterward filling the gaps between the girders as needed. Those versed in the science of tensorial analysis of interrelated physical systems on the one hand and of large electrical networks on the other, should thereby be able to solve, with the aid of already available digital computers, highly complex physical systems possessing tens of thousands and, in special cases, even hundreds of thousands of variables. The accuracy of machine calculations, of coding and even the correctness of the analytical procedure itself may be simultaneously checked by physical tests at various stages of the computation. The saving in computing time is considerable even in smaller problems; by tearing a physical system into n parts, the usual machine calculations are reduced, in matrix inversion for instance, to a fraction of about 2/n2.
The present paper develops in detail the solution of a simple boundary value problem of Poisson's equation. A numerical example of interconnecting the solutions of large electric-power transmission systems appears in reference 3. Many simpler numerical examples are worked out in reference 1.
Measurement of Elastic Constants at Low Temperatures by Means of Ultrasonic Waves–Data for Silicon and Germanium Single Crystals, and for Fused Silica
Authors: McSkimin H. J. 
Published: April 2005

Ultrasonic waves (shear or longitudinal) in the 10–30 mc range are transmitted down a fused silica rod, through a polystyrene or silicone one-quarter wavelength seal, and into the solid specimen. Measurement of reflections within the specimen yields values for velocities of propagation and elastic constants.
Data obtained over a temperature range of 78° to 300°K for silicon and germanium single crystals, and 1.6° to 300°K for fused silica are listed. For the latter, a high loss is noted, with an indicated maximum near 30°K.
First Probability Densities for Receivers with Square Law Detectors
Authors: Emerson R. C. 
Published: April 2005

The method of Kac and Siegert for finding the output probabi ity density characteristic function for receivers with square law envelope detections is discussed, and a parallel development is given for the square law rectifier. Procedures are then outlined for determining the probability density functions directly, i.e., without solving the eigenvalue problem or inverting the characteristic function. The method depends on expanding the density function in an orthonormal series, the coefficients of which are expressed in terms of cumulants, which in turn are obtained from the system kernel by straightforward quadratures.
As an example to illustrate the procedure, a receiver with Gaussian IF and Gaussian audio-frequency pass characteristics is treated in detail, and the output probability density functions are found for various sinusoidal input signal strengths and IF vs audio band-width ratios.