bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dead Time and Non-Linearity Characteristics of the Geiger-Counter X-Ray Spectrometer
Authors: Alexander Leroy , Kummer Elizabeth , Klug Harold P. 
Published: January 2005

The satisfactory use of Geiger-counter methods for the measurement of diffracted x-ray intensities demands that the observed counting rates be corrected for the non-linear response of the counter. Both the multiple foil method of calibrating the non-linearity of response and the two-source method of Beers for measuring counter dead time have been found to be unsatisfactory approaches to this problem. The experience of this laboratory indicates that electronically controlled oscillographic techniques for the direct measurement of dead time are much more satisfactory. With a knowledge of the dead time, τ, the true counting rate, N, can be calculated from the observed counting rate, No, by employing the formula N=No/(1−Noτ).
For a pulsating x-ray source the effective counting rate is faster than the observed by a factor which is characteristic of the type of rectification employed, the target material, and the voltage applied to the x-ray tube. A sufficiently accurate value of this factor can be arrived at by oscillographic observation of the pulse pattern and in some cases by mathematical analysis.
Fields from Fluid Flow Mappers
Authors: Moore A. D. 
Published: January 2005

Fluid flow within the streamline (viscous) range, made visible by appropriate means, may be made to simulate fields occurring in electrostatic, magnetic, electric current, heat flow, chemical diffusion, and other situations. Simple, reliable, and inexpensive techniques for setting up the desired fluid flow situations have been worked out, and are described herein.
Two-dimensional fields with one, several, or many non-distributed sources (or sinks) may usually be made up and operated with ease. Techniques for the simulation of certain three-dimensional fields with axes of symmetry have also been developed.
Through the invention of the ``sandbed'' feature, the fluid flow method has been greatly extended: fields due to distributed sources can be simulated, not only outside the sources, but inside them as well.
Numerous photographs of fluid mappers in operation, illustrating all of the foregoing types of cases, are included.
High Inverse Voltage Germanium Rectifiers
Authors: Benzer S. 
Published: January 2005

Rectifying current-voltage characteristics going up to several hundred volts inverse have been observed in metal-germanium point contact rectifiers. A reproducible negative differential resistance region occurs in the inverse characteristic. Certain impurities are desirable in producing high voltage material. Surface treatment, e.g., by etching, is very important. The metal used as a whisker has little effect. Increasing the force of contact increases greatly the current of low voltages but has less effect on the high voltage curve. Pronounced improvement of rectification can be effected by treatment of the contact with large currents.
Variation with temperature is very marked, especially for crystals of large inverse resistance; the variation of the inverse peak with temperature indicates that contact heating is responsible for the negative resistance. Time lags in the inverse negative resistance region of the order of 10−5 second occur.
When contact is made between two Ge crystals, typical inverse characteristics are observed in both directions. Photoelectric effects are observed and indicate that the barrier thickness is greater the higher the inverse peak voltage.
The Aerodynamics of Golf Balls
Authors: Davies John M. 
Published: January 2005

The aerodynamic forces on golf balls were studied by dropping spinning balls through the horizontal wind stream of the B. F. Goodrich wind tunnel. The lift, L, and drag, D, were calculated from the drift of the balls, rotating at speeds, N, up to 8000 r.p.m. while falling through a wind stream having a velocity of 105 feet per second. For a standard dimple or mesh golf ball weighing 0.1 lb., the lift varied with the rotational speed as L=0.064 ×[1−exp(−0.00026N)], with a maximum observed value of 0.055 lb. or more than half the weight of the ball. The drag increased nearly linearly from about 0.06 lb. for no spin to about 0.1 lb. at 8000 r.p.m.
For a smooth ball the lift was negative at all rotational speeds below 5000 r.p.m. Above this speed, the lift was positive but was less than for the standard ball. The drag for these balls was nearly constant at about 0.08 lb. Balls with shallower dimples than standard gave intermediate results. Driving tests were consistent with the wind tunnel results.
These results explain why a golfer cannot obtain long drives with a ball having a smooth surface and why the standard dimple or mesh surface gives him greater distance and better control of the ball.
The Production Histories of Oil Producing Gas-Drive Reservoirs
Authors: Muskat Morris 
Published: January 2005

A theory has been developed for predicting the behavior of solution gas-drive oil producing reservoirs, on the basis of previously established empirical laws on the flow of heterogeneous fluids through porous media. Treatments are given both for the simple pressure depletion history without gas injection, and those for systems in which gas is injected during the course of oil production. The specific results provided by the theoretical analysis include the ultimate oil recovery, and the pressure decline, gas-oil ratio, and productivity factor histories. Two types of gas injection have been considered, namely: (1) that in which the returned gas is supposed to diffuse through and be produced continuously with the oil zone; and (2) that in which the injected gas remains locked in the gas cap, which merely expands as oil production and gas injection proceed. In the latter case the rate of growth of the gas cap is also obtained as a function of the cumulative oil recovery.
The theory is illustrated by numerical application to a hypothetical virgin oil reservoir with an original pressure of 2500 p.s.i. producing by gas-drive, and with no initial gas cap. It is so found that if no gas is injected into the system the physical ultimate oil recovery will be 14.5 percent of the pore space, or 27.1 percent of the original stock tank oil content, assuming that the formation initially has a connate water saturation of 30 percent. The gas-oil ratio first declines as production is started, then rises sharply to a maximum of 4400 cu. ft./bbl., and finally falls steeply as the pressure is depleted to atmospheric. If there is no gas segregation and 60 percent of the produced gas is returned to the formation, the ultimate oil recovery will be increased by 27.6 percent. The gas-oil ratio history will be similar to that with no gas injection, but will rise to a maximum of 10,300 cu. ft./bbl. If 80 percent of the gas is returned, the recovery increase will be 48.8 percent, the maximum in the gas-oil ratio history reaching a value of 19,450 cu. ft./bbl. If all the gas is returned, the gas-oil ratio rise will be so rapid that by the time 20,000 cu. ft./bbl. is reached only 23.5 percent additional oil will be recovered. During these operations the productive capacities of the wells will fall by factors of the order of 10, because of the increasing viscosities of the oil and decreasing permeabilities to the oil, as the pressure declines and the oil saturation decreases.
For the case where the gas remains trapped in the gas cap, the ultimate oil recovery will be 163 percent greater than by direct pressure depletion, if the residual oil after gravity drainage is 15 percent of the pore space. This recovery will be essentially independent of the amount of gas return, although the final reservoir pressure at the time of complete gas cap expansion will be greater as more gas is returned. The increased oil viscosity and decreased permeability to the oil will here reduce the specific production capacities of the wells to ¼ or ⅓ of their initial values.
Numerical Solution of Ordinary and Partial Differential Equations by Means of Equivalent Circuits
Authors: Kron Gabriel 
Published: January 2005

Numerical methods are developed to solve certain types of linear and nonlinear partial differential equations to any desired degree of accuracy with the aid of equivalent electrical networks. The methods of solution of ordinary differential equations, both linear and nonlinear, follow as special cases. Three types of problems are considered:
1. Initial-value problems. If the field quantities are known along a surface, the networks may be solved by a straight-forward step-by-step calculation. The networks may also be looked upon as supplying a ``schedule'' of operations that can be put on a digital calculating machine.
For time-varying problems new types of networks are developed in which time appears as an extra spatial variable. Examples of new networks for the elastic field and for the general nonlinear wave equation are given. Sample calculations and theoretical checks of a transient heat flow problem and of an ordinary differential equation are also included.
2. Boundary-value problems. Four methods of solution are given, the first three being cut and try processes. (a) The method of weighted averages; (b) The method of unbalanced currents and voltages; (c) The ``relaxation'' method; (d) The ``diffusion'' method, that changes the boundary-value problem into an initial-value problem by adding to the original partial differential equation a time variable of the form A∂φ/∂t, allowing the unbalanced currents to ``diffuse'' in time.
These numerical methods may also be used to improve the accuracy of the results found on the Network Analyzer. Examples of calculations are given for the electromagnetic and the elastic fields.
3. Characteristic-value problems. Their methods of solution are similar to those of boundary-value problems. An additional method of unbalanced admittances is also indicated. It is shown that by calculating the power in the network, the characteristic value of the assumed function is found.
An improved characteristic value of the linear harmonic oscillator, solved initially on a Network Analyzer, is calculated as an example.
In general the electrical networks may be used to check the consistency and correctness of solutions arrived at by other methods, approximate or exact. The unbalanced currents at the junctions (easily calculated) give a quantitative measure of the deviation from the correct solution.
Mechanics of the Metal Cutting Process. II. Plasticity Conditions in Orthogonal Cutting
Authors: Merchant M. Eugene 
Published: January 2005

The analysis of the mechanics of orthogonal cutting with a type 2 chip as presented in the first paper of this series can be extended by introducing those physical properties of the work material which control its plastic behavior. One evident plasticity condition is the equality of the shear stress on the plane of shear to the shear strength of the metal. If it is also assumed that the shear strength of the work material is a constant and is the only quantity controlling its plastic behavior, then a very simple additional plasticity condition is obtained by application of the principle of minimum energy. This condition is 2φ+τ−α=90°, where φ is the shear angle, τ the friction angle, and α the rake angle. This condition, however, is found by experiment to be a poor approximation in the case of polycrystalline metals. A very good approximation is obtained, though, if use is made of the fact that the shear strength of the polycrystalline metal is actually a function of the compressive stress on the shear plane. The resulting plasticity condition is cot (2φ+τ−α)=k, where k is the slope of the linear curve relating shear strength and compressive stress, and is thus a constant of the work material.
Such a plasticity condition establishes a relationship between the force system and the geometry of chip formation, so that, if k and the shear strength be known for a given material, all forces involved in cutting it can be calculated with reasonably good accuracy directly from measurements of chip geometry only, without use of a tool dynamometer. This is of importance in the analysis of practical machining operations.
Techniques for Evaporation of Metals
Authors: Olsen Leonard O. , Smith Charles S. , Crittenden E. C. 
Published: January 2005

Thirty-four elements have been observed for evaporation behavior, the results being summarized for each element and the best techniques then listed in Table I. Heaters studied fall into two general classes, wires and crucibles. Tungsten, iron, nickel, and chromel wires were used and these were formed into close wound conical baskets and helical coils. Each element was studied for evaporation behavior from as many of these forms as was possible. Alundum and BeO crucibles formed by painting suspensions of these materials on a tungsten conical basket followed by baking at a high temperature were exceptionally satisfactory heaters for almost all of the elements studied. These crucibles served well for the evaporation of metals whose evaporation temperatures approached 2000°C as well as for those with lower evaporation temperatures.
The 18-inch evaporation system was designed and constructed along fairly standard lines. An externally operated, four-inch vacuum valve between the diffusion pump and the bell jar allowed air to be admitted to the bell jar without cooling the diffusion pump. This valve was an especially useful feature of the equipment.
The Effect of Water on the Strength of Glass
Authors: Baker T. C. , Preston F. W. 
Published: January 2005

The strength of glass was measured in various surrounding media. It was found that glass is 20 percent stronger when dry than when wet, and two to two and a half times as strong when baked in vacuum than when tested wet (on tests of ten seconds duration). Apparently, the chief cause of the loss of strength, as compared with that in vacuum, is moisture, but gases, especially CO2, seem to have some effect. It was found that fatigue of glass disappears when the glass is tested in a vacuum.
Autoclaving tests showed that glass is rapidly etched by water at higher temperatures, and that even silica glass is considerably attacked. It appears that the attack of water on glassy surfaces produces gels, and this attack goes on inside the flaws, thus considerably complicating the problem of the strength of glass.
A New Electrolytic Selenium Photo-Cell
Authors: Von Hippel A. , Schulman J. H. , Rittner E. S. 
Published: January 2005

A new electrolytic selenium photo-cell is described and its characteristics given as a function of operating voltage, temperature, external resistance, and time. Data are included indicative of its response to unmodulated, modulated, and monochromatic light; comparison is made with cells of similar type or possessing similar characteristics; and a method of compensating for the dark current of photo-cells is shown.
An electronic circuit is also described which can greatly improve the voltage output of the photo-element. It is generally applicable to photo-conductive and photo-voltaic cells.
Plasma Frequency and Velocity Spread in Bunched Electron Beams of Finite Diameter
Authors: Mihran Theodore G. 
Published: January 2005

The velocity spread existing on a velocity-modulated electron beam of finite diameter is investigated as a function of drive, drift length, and perveance using a digital computer program based on a disk electron model. At small signal levels the velocity modulation decreases cosinusoidally to zero with drift distance in accordance with one-dimensional bunching theory. At higher signal levels, however, the velocity spread does not go to zero due to aberrations introduced by the finite diameter of the beam.
The minimum velocity spread at maximum bunching is found to be proportional to the square of the fundamental component of rf current, up to an optimum drive level. Above this drive level the velocity spread increases rapidly with no corresponding increase in rf current. Trajectories of electrons of all initial phases are found to undergo a basic transition from nonovertaking to overtaking at a new characteristic distance λpq/4, which is given approximately by the geometric mean of the infinite beam quarter-plasma wavelength λp/4 and the reduced (due to finite beam size) quarter-plasma wavelength λq/4. This characteristic distance is found to be a key parameter in the prediction of velocity spread, drift length and drive for optimally bunched electron beams for use in klystron amplifiers, harmonic generators, and in linear accelerators.
Electron Attachment-Detachment Processes in Dry Air
Authors: Ryżko Henryk , Åström Ernst 
Published: January 2005

The pulses due to electron avalanches released in dry air from a cathode of a uniform field gap (6 cm) by photoelectrons in a time interval of about 40 nsec are investigated. Using a new method of evaluation which yields simpler formulas, the attachment coefficient η for formation of unstable negative ions and the mean lifetime τ of these ions are determined. In the pressure range 4–60 Torr, η/p is independent of pressure and increases in the E/p range 33–53 V cm−1 Torr−1 from 0.006 cm−1 Torr−1 to 0.017 cm−1 Torr−1. In the same pressure range, τp is independent of pressure and decreases from 35 μsec Torr to about 2 μsec Torr.
Our results confirm the earlier assumption of one prevailing kind of unstable negative ion. The value of η/p agrees with that obtained earlier at E/p close to 40 V cm−1 Torr−1. A distinct variation of η/p with E/p, not reported earlier, is obtained.
A Moments Methods for Describing the Diffusion of Radiation from a Cavity
Authors: Pomraning G. C. 
Published: January 2005

A moments method is applied to the non-self-similar problem of the diffusion of radiation from a cavity, in the case that the transport of energy is purely radiative. The energy in the cavity is assumed to be introduced instantaneously, and the diffusion into the surrounding wall, particularly the motion of the radiation front, is followed for subsequent times. The moments method used has the characteristic that it gives, for the physical model assumed, exact results for the position of the front in both the short- and long-time limits for all geometries.
Both plane and spherical cavities are treated in detail. Series solutions which apply in the limits of short and long times are given. Equations describing the first-order departure of spherical radiation flow from plane flow are derived, and the short-time solution is given. In plane geometry all quantities of interest can be written in parametric form in terms of elementary functions, and numerical results are presented in this case. Spherical geometry yields a more complex parametric solution, which is also given.
Application of the Dynamical Theory of X-Ray Diffraction to Holography
Authors: Saccocio Edward J. 
Published: January 2005

The concepts of the dynamical theory of x-ray diffraction are applied to optical holography. A plane-grating hologram is the assumed diffraction element and its behavior is shown to be consistent with that of its x-ray counterpart, namely a thin, one-dimensionally periodic structure. Evidence is cited which corroborates the theory. In particular, an anomalous transmission of light through the plane-grating structure, at the Bragg angle, is reported-referred to as the Borrmann effect in the x-ray-crystal situation-which in x-ray optics is taken as prima facie evidence for the dynamical theory. The usually observed subsidiary maxima about the Bragg peak and their reported asymmetry are explainable in terms of the dynamical theory as effects due to a finite lattice. The minimum angle of deviation found in holograms, so familiar to prisms and line gratings, is described as a finite-lattice effect.
It is concluded that the dynamical approach in holography is a useful one for the thick emulsion, whereas the simple kinematic theory is more adequate for thin emulsions. However, attention is drawn to the use of the dynamical theory even for the case of thin emulsions to help provide some physical insight into the diffraction of light by holograms.
Mobility of Edge Dislocations in the Basal-Slip System of Zinc
Authors: Pope D. P. , Vreeland T. , Wood D. S. 
Published: January 2005

This paper presents the results of measurements of the velocities of 〈12̄10〉 (0001) edge dislocations in zinc as a function of applied shear stress. All tests were conducted at room temperature on 99.999% pure zinc monocrystals. Dislocations were revealed by means of the Berg-Barrett x-ray technique. Stress pulses of microsecond duration were applied to the test specimens by means of a torsion testing machine. Applied resolved shear stresses ranged from 0 to 17.2×106 dyn/cm2 and measured dislocation velocities ranged from 40–700 cm/sec.
The results of this study indicate that the velocity of edge dislocations in the basal slip system of zinc is linearly proportional to the applied resolved shear stress. These results are analyzed in terms of the phonondrag theory. Agreement between this theory and the results reported here is quite good.
A Dislocation Mechanism for Deformation in Polyethylene
Authors: Predecki Paul , Statton W. O. 
Published: January 2005

A mechanism is proposed for transverse slip on {100} 〈010〉 in polyethylene, in terms of the motion and multiplication of dislocations caused by chain ends. Some of these defects, the jogged dislocations, are able to move at stresses somewhat below the yield stress. However, the extent of transverse slip and of the resulting transverse textures is limited by chain folds and the requirement of chain continuity. Slip displacements parallel to the chain direction are then favored.
The mismatch requirements for dislocations with Burgers vectors having components in the chain direction are determined. The Burgers vectors are 〈0, b, nc〉 on {100} and 〈a, b, nc〉 on {110}; the latter can dissociate into two types of partials with Burgers vectors 〈a/2, b/2, nc〉 or 〈a/2, b/2, (n−½)c〉, where n=1, 2⋯. Such defects can act in pairs [u, v, w] and [ū, v̄, w] producing displacements parallel to the chain direction.
Coherence and Deformation of Lamellar Crystals after Annealing
Authors: Statton W. O. 
Published: January 2005

A striking change in coherence is obtained when single-crystal platelets of linear polyethylene are recrystallized by annealing at temperatures between 120°C and the melting point, 137°C. Instead of showing micaceous cleavage, the sintered crystal mat is ductile and malleable in shear, yet still will not flow under compression.
Annealing provides enough toughness to the crystal mat to allow a deformation which elongates it several-fold. Hot calendering allows a much greater elongation than cold rolling and produces a tough, crackly, clear film. The sintered aggregate can be easily hand drawn hot to extremely high draw ratios, often above ×40. The product has very good tensile properties when tested as a fiber. A two-way hot calendering operation produces a film with outstanding tear strength and poor puncture and impact strengths.
The coherence caused by the annealing of the platelets is analogous to the coherence developed in powder metallurgy or in sintering of ceramic bodies. In polymer crystals, annealing has been shown to cause the molecules to refold into longer fold periods, leaving holes. These holes provide the growing room for the refolding of chains from adjacent platelets; a cooperative intermeshing of chains occurs. This creates one large crystal aggregate which has a homogeneous distribution of sites of weakness. It is proposed that many annealing treatments of bulk crystalline polymers cause this intermeshing to occur, and a new interpretation is at hand for the well-known relationship of strength vs annealing temperature.