bluuebunny/crossref_metadata_2025_split huggingface dataset:
Some High-Pressure, High-Temperature Apparatus Design Considerations: Equipment for Use at 100 000 Atmospheres and 3000°C
Authors: Hall H. Tracy 
Published: February 2005

Three items of equipment are described in detail; (1) A simple-piston and cylinder device capable of generating pressures to 50 000 atmospheres simultaneously with temperatures of 5000°C, (2) a tetrahedral-anvil device that has been successfully tested at 100 000 atmospheres and 3000°C, and (3) a stepped-piston device capable of developing pressures to 200 000 atmospheres at room temperature.
In addition consideration is given to such problems as (a) geometrical elements of design, (b) higher strength materials, (c) use of mechanical anisotropy in design, (d) electrical leads, (e) thermal and electrical insulation, (f) solid pressure transmitting media, (g) binding rings, (h) internal generation of pressure, (i) multistaging, and (j) calibration.
Captive Balloon Refractovariometer
Authors: Crozier Albert L. 
Published: February 2005

A system is described for measuring and recording rapid (3 cps) fluctuations of refractive index, humidity (vapor pressure), and temperature using fast response thermistor beads. The system utilizes wet and dry thermistors whose changes are fed into a simple analog computer. The accuracy of the system is 1 part in 107 for refractive index, about 0.1 mbar for humidity and 0.1°C for temperature.
Measurements can be obtained to an altitude of 5000 ft above the measuring site, with an altitude accuracy of ±50 ft under optimum weather conditions.
Field Homogenizing Coils for Nuclear Spin Resonance Instrumentation
Authors: Golay Marcel J. E. 
Published: February 2005

The coils described in this paper are assembled in two relatively thin flat stacks which are placed on each pole piece of a nuclear spin resonance magnet. One coil of each coil pair is in each of the two stacks, and each coil pair is so designed that the current circulating in it produces, in the airgap center, a correcting magnetic field describable by one of a set of spherical harmonics. The orthogonal properties of the spherical harmonics render possible substantially independent adjustments of the currents in the several coil pairs, when some spin resonance parameter such as line width is utilized to determine that individual optima are reached.
Experimental coil stacks with 13 coil pairs, for the second, third, and zonal fourth harmonics, have been constructed, and preliminary results obtained by Rex Richards (Oxford) indicate that when a 4-mm spin sample is used, this method can serve to reduce field inhomogeneities to less than 1 part in 108 with few sets of 13 current adjustments.
Differential Calorimeter of the Tian-Calvet Type
Authors: Attree R. W. , Cushing R. L. , Ladd J. A. , Pieroni J. J. 
Published: February 2005

A differential microcalorimeter of the Tian-Calvet type has been designed and constructed. The galvanometers previously employed have been replaced by a dc amplifier, which materially simplified the construction and operation of the instrument. In addition, this allows an electrical analog integrator to be used which gives directly the heat of reaction.
Sensitivity of the instrument in the range from 0.01 to 2 cal is such that measurements can be made with a precision of 1% or better. Measurements have been made, under ideal conditions, of 0.002 cal with a standard deviation of 0.1%.
Development of the Calorimeter Heat Transfer Gauge for Use in Shock Tubes
Authors: Rose Peter H. 
Published: February 2005

A heat transfer gauge suitable for measuring extremely high heat transfer rates under the quasi-transient conditions occurring in shock tubes has been developed. The instrument is based on a calorimetric principle and is made possible by the short steady state times inherent in shock tubes. The technique developed extends, verifies, and supplements the shock tube heat transfer measurements made by thin film resistance thermometers.
The operating principles and experimental experiences with calorimeter heat transfer gauges are reported in some detail.
Much heat transfer data obtained with calorimeter gauges has been collected and published. Experimental measurements of laminar and turbulent heat transfer rates at velocities up to satellite speeds, approximately 26 000 ft/sec, have been reported. Heat transfer rates as high as 40 kw/cm2 have been encountered in these experiments.
Method for the Study of Deflagration to Detonation Transition
Authors: Gibson Frank C. , Bowser Merle L. , Mason Charles M. 
Published: February 2005

A method based on the variation of electrical resistance in a wire element introduced into the charge has been developed for the continuous measurement of burning and detonation rates in opaque materials. The method has been used to obtain data on nonsteady-state phenomena in high explosives, in composite propellants and in liquid fuel-solid oxidizer mixtures.
Composite propellants were found to be readily detonable when modified by the introduction of voids. Studies on liquid fuel-solid oxidizer mixtures, with bubbles of inert gas as well as voids, gave similar results.
Precision High-Velocity Detonating Cord
Authors: Abrahamson G. R. , Huber G. B. 
Published: February 2005

The accuracy of time delays which utilize detonating cord as the timing element is limited primarily by variations in detonation rate. A commercial detonating cord consisting of a small core of granular PETN explosive within a cylindrical lead sheath has an average detonation rate of 6275 m/sec with a range of 170 m/sec. By subjecting this material momentarily to a hydrostatic pressure of 55 000 psi, the detonation rate (after removal from the pressure chamber) is increased to 8140 m/sec and the range is decreased to 25 m/sec. Thus timing error due to detonation rate variation is reduced ninefold. These effects are attributed to increased density and decreased density variations of the explosive core.
The change in detonation rate of pressed detonating cord with temperature is found to be 0.16 to 0.19 m/sec per °F. This effect appears to be due primarily to density changes induced in the explosive core by the expansion and contraction of the lead sheath.
High-Power Pulse Steepening by Means of Exploding Wires
Authors: Janes G. Sargent , Koritz H. 
Published: February 2005

A circuit technique is described which reduces the rise times of high-power pulses by means of exploding wires. This circuit is a nonlinear lumped parameter transmission line. The magnetic energy is stored in the interstage lead inductances and rapidly transferred into (or more correctly, shared with) succeeding stages by the vaporization of exploding wire resistive fuse elements connected in shunt between the leads. In our case, each of three resistive fuse elements consisted of 20 to 50 parallel 0.001-in. diam copper wires held in place across a 2-in. gap with pressure sensitive tape. An empirically determined arrangement is described wherein we have increased the maximum rate of current rise from 300 000 amp/μsec to 800 000 amp/μsec. Using this technique, a magnetic field of 10 000 gauss is built up in 0.15 μsec throughout a volume 4 cm in length and 10 cm in diameter.
It will be shown that the best results are obtained with high conductivity fuse materials such as copper or aluminum. Similarity theorems are presented for the design of pulse steepening elements for use with circuits having similar pulse shapes but different energies and characteristic impedances.
Flow through Capillary Tubing with Eccentric Annular Sections
Authors: Bachman C. H. , Hottenrott H. G. 
Published: February 2005

Gas flow through capillaries obstructed by wire inserts was investigated for ratios of core to capillary diameters (B/A's) of 0.08 to 0.9. For a given core-capillary combination, laminar and turbulent as well as an intermediate region are well defined. Deviations from Poiseuille flow for the range of B/A's are presented in a working curve, which will give flow rates for laminar flow correct to from 5 to 10%.
The pressure drop vs flow curves for the intermediate and turbulent flow regions are reasonably reproducible. The use of the cored capillary for very small leak rates looks especially attractive because, with large B/A's such that the maximum crescent clearance is less than 0.25 mm, the onset of turbulence is postponed to much higher pressure drops.
Solution of Polynomials by Use of an Electromechanical Synthesizer
Authors: Schwetman Herbert D. , Burmeister Charles 
Published: February 2005

The roots of polynomials of high degree are obtained with a stated accuracy in a time of ten to thirty minutes by use of an electromechanical harmonic synthesizer. The machine consists of sine-cosine potentiometers which are driven by meshed gears to produce sinusoidal potentials of frequency f, 2f, 3f, …. The algebraic polynomial is transformed into a trigonometric polynomial in which the terms are expressed in multiple angle form and applied to the machine. As the fundamental gear is rotated through 180°, the potentials are summed in a recording high impedance voltmeter in such a manner that when the curve f(θ)=0 passes through zero values, the angles are read from a large dial and the roots x=r cos θ are obtained.
Examples of the solutions are given, and the results of some twenty-five solutions reported to show an average accuracy of 1.19% and an average time of solution of 16 minutes. For higher accuracy a time of about 7 minutes is required for each additional substitution, until an accuracy of 0.30% may be obtained. Multiple or repeated roots are obtained by use of the factor theorem and repeated differentiation.
Modification of a Cone-Plate Viscometer for Direct Recording of Flow Curves
Authors: Bauer Walter H. , Finkelstein Alfred P. , Larom Charles A. , Wiberley Stephen E. 
Published: February 2005

Using a concentric-cylinder rotational viscometer, Weltmann has shown that automatic recording of flow curves in accordance with a predetermined program is important in the study of materials whose flow properties are shear-dependent and time-dependent. When the flow of such materials as greases was studied using the Ferranti-Shirley cone-plate viscometer, advantages of small sample size, ease of loading with minimum deformation, and uniform shear rate across the sample were apparent. However, time-dependent properties of the grease could not be adequately described from data obtained in manual operation of the cone-plate viscometer.
An automatic control device for shear rate acceleration of the cone-plate viscometer has been designed so that flow curves can be obtained automatically using an X-Y recorder. Flow curves of typical greases and other materials exhibiting non-Newtonian and time-dependent properties have been successfully obtained using this automatic control device. The cone-plate viscometer as modified has distinct advantages for the study of non-Newtonian and time-dependent materials.
Current Noise and Nonlinearity in Pyrolytic Carbon Films
Authors: Williams Thomas R. , Thomas John B. 
Published: February 2005

Measurements of the current noise and nonlinearity in the pyrolytic carbon films of 322 resistors are given. The resistances and the dimensions of the films both varied over a wide range. It is demonstrated that when the dimensions of the films are taken into account their noise and nonlinearity are highly correlated: the noise in a given film can therefore be used to estimate the nonlinearity, and conversely. In many groups of resistors of the same type the resistance change with a given applied voltage varied among resistors by a factor of more than 10, and the noise power for a given current through the resistors varied by a factor of more than 100.
In the measurements of nonlinearity the resistance changes were often very small, and, consequently, were easily masked by temperature effects. A measurement method was employed in which the resistors were placed in a balanced bridge, a short high-voltage pulse was applied to the bridge, and the resistance change was determined from the bridge output voltage. With this technique it was possible to measure resistance changes of the order of 20 ppm with an accuracy of ±3 ppm.
Bearing Dynamometer
Authors: Klint R. V. , Owens R. S. 
Published: February 2005

A bearing dynamometer has been devised and built which enables ready evaluation of bearing materials. Coefficient of friction and shaft speed are presented on an X-Y recorder. By varying the load on the bearing a family of curves may be quickly obtained yielding the basic performance characteristics of the bearing materials under actual bearing conditions.
Prolonged tests can be performed during which observation of the bearing characteristics as a function of time can be studied.
At present, bearings of ½-in. diameter are being studied to speeds of 2000 rpm and coefficients of friction to 0.7. These ranges are easily extended.
The speed determination is made by a dc tachometer-generator. The essential element of the friction measuring system is a linear variable differential transformer acting as a transducer for the friction torque of the bearing.
Temperature-Regulated Ignition Source
Authors: Preston John , Ashman Leland E. 
Published: February 2005

The temperature controller described here is capable of heating a fine wire (of the order of a few mils in diam) to some temperature between 700°C and the melting temperature, and holding the temperature constant to within a few degrees.
The detector is a photomultiplier that monitors radiation from the center of the wire; changes in radiation result in compensating changes in the current. The controller responds within a millisecond to sudden changes in the environment of the wire. This rapid response is useful for detecting the onset of ignition in reactive gases and perhaps for measuring the thermal properties of nonreactive gases.
New Apparatus for Measuring Flow Birefringence
Authors: Janeschitz-Kriegl H. 
Published: February 2005

In the present paper a description is given of the design of an apparatus for measuring flow birefringence; the pertinent theory has been published previously [Physica 22, 1197 (1956); J. Polymer Sci. 23, 181 (1957)]. In this apparatus glass cylinders are used, instead of the usual metal cylinders. A slow convention stream which moves parallel to the cylinder axis, removes part of the frictional heat generated in the annular gap. In that way a rising temperature distribution throughout the cross section of the gap, as was described by Y. Björnståhl [Z. Physik 119, 245 (1942)], is prevented. This temperature distribution, as is well known, causes the divergence of the light beam and, consequently, reflection at the walls of the cylinders. However, in the apparatus described in this paper, no reflections occur and, as a consequence, the appearance of a parasitic double refraction is avoided.
Some results of measurements on solutions of cellulose nitrate in cyclohexanone are communicated.
Low Background Thin-Wall Flow Counters for Measuring Beta Activity of Solids
Authors: Lal Devendra , Schink David R. 
Published: February 2005

The construction and performance of disk-shaped thin-walled flow counters suitable for measuring very small beta activities of solids is described. The circular faces, which serve as the cathode, consist of conducting films. Either a single pear-shaped loop of wire whose plane is parallel to that of the faces, or a group of straight wires stretched across the midplane serves as the anode. The counters are operated in the Geiger region. Samples can be counted against both faces of the counter. Performance data are given for counters having active volumes ranging from 0.2 to 7 cc, and having active areas from 1.6 to 23 cm2. Counting efficiencies for natural potassium (mounted on Lucite) vary from 30% to 47%, depending on the relationship of sample area to counter dimensions. Inside a 20-cm steel shield and an anticoincidence ring the background counting rates varied approximately as 1 count/hr/cm2 of counting area. Backgrounds as low as 1 count/hr were obtained.
The disk geometry permits the use of a smaller metal and anticoincidence shield than is possible with cylindrical geometry. Counters shielded successively with 1.9-cm mercury, 5-cm steel, and 5-cm lead, and operated with a flat multiple-anode anticoincidence counter (15 cm2), actually gave lower background than with the 20-cm steel and anticoincidence ring assembly. An integral counter assembly, consisting of ∼2-cm diam disk-shaped counter and a disk-shaped guard counter (∼7-cm diam), was constructed and gave satisfactory results.
Improved Gradient Layer Animal Calorimeter
Authors: Quattrone Phillip D. 
Published: February 2005

A rapidly responding gradient layer calorimetry system for experimental animals is described. Monitoring of radiant and evaporative components of heat loss is accomplished by separate heat exchange systems that employ thermoelectric heat flowmeters.
Calibration and test results with the equipment show the following: The response to energy input is linear in both the radiant heat exchange system (radiant calorimeter thermopile) and the circulating air heat exchange system (ventilatory calorimeter thermopile); the radiant calorimeter thermopile signal is independent of the location of the heat source in the chamber, and when referenced to a cold junction temperature of 20°C, it has a response of 0.0212 mV/g·cal/min; the ventilatory calorimeter thermopile has a response of 0.0159 mV/g cal/min when referenced to a cold junction temperature of 4°C; the automatic temperature control systems for the two thermopiles provide ±0.01°C control at their respective temperatures; the noise-to-signal ratio is less than 1% for the radiant calorimeter thermopile and less than 2% for the ventilatory calorimeter thermopile at thermal input levels comparable to those expected from the experimental animal.
A Paramagnetic Oxygen Analyzer
Authors: Dyer Clarence A. 
Published: February 2005

An oxygen analyzer which makes use of the unique paramagnetic property of oxygen and a hot-wire bridge is described.
The instrument is designed to operate under rather extreme conditions of temperature and pressure, as specified by the Air Materiel Command of the Army Air Forces.
Percent oxygen is indicated in the range from 21 to 100 by a panel meter, and provisions are incorporated for using it in connection with a recording oscilloscope.
A Photoelectric Nephelometer
Authors: Underwood N. , Doermann A. H. 
Published: February 2005

A nephelometer is described that does not require a precision optical system or an electronic amplifier. It is sensitive enough to measure the growth of E. coli from a starting concentration of approximately 2×106 bacteria per ml. The readings are reliable from 107 to 109 bacteria per ml. A graph of the photo-current caused by the scattered light versus the number of E. coli per ml is given. The E. coli culture is a saturated 24-hr. nutrient broth culture in the lag phase. The bacteria were killed with 1 percent formaldehyde. In this range of bacterial concentrations the scattered light is nearly proportional to the number of scattering centers. The instrument is well adapted to the study of growth curves of bacterial cultures and the lysis phenomena that occur when the organisms are attacked by bacteriophages.
A horizontal beam of light passes through the vertical test tube containing the specimen. The light scattered downward is measured with a barrier layer photo-cell. The horizontal incident light produces a photo-current of 2.4×10−3 ampere. The light scattered by a specimen whose titer is 5×107 E. coli (growing exponentially) per ml produces a photo-current of 1.2×10−5 ampere. In this case the scattered light reaching the photo-cell is 1/200 of the incident light.
An Automatic Dewpoint Meter for the Determination of Condensable Vapors
Authors: Puck Theodore T. 
Published: February 2005

A method for determination of very small concentrations of condensable vapors by measurement of the decrease in reflectivity of a cooled surface on which the vapor has been deposited is described. The method is applicable to mixtures of 2 components, one of which may be water. Use is made of the fact that a vapor will condense at a concentration below its vapor pressure in the presence of a second vapor whose liquid is soluble in that of the first. The most volatile component of the mixture is used in the pure state as a refrigerating agent whose evaporation cools the light-reflecting surface to an accurately regulated temperature which produces condensation of the two components.
An instrument embodying these principles is described which quantitatively measures triethylene glycol vapor in concentrations as low as 10−4 mm Hg. The construction is simple and the operation continuous and automatic. The calibration of the instrument is presented. By proper adjustment, automatic compensation for changing atmospheric relative humidity can be secured so as to obtain response only to the degree of saturation of the glycol vapor in air.
This device has been used to investigate condensation of vapors on atmospheric nuclei, and as a control instrument to regulate the concentration of triethylene glycol vapor employed as an aerial germicide for prevention of airborne disease transmission.
Electrostatic Deflection of a Betatron or Synchrotron Beam
Authors: Courant E. D. , Bethe H. A. 
Published: February 2005

An electrostatic deflection scheme for removing the electron beam from a betatron or synchrotron is considered. The deflection is accomplished in two stages: The first stage is an orbit expansion achieved by a sudden decrease of the magnetic field in the orbit region. The electrons move outwards in spirals of increasing pitch; if the orbit radius is 1 meter and the rate of decrease of the magnetic field is one percent per microsecond, the pitch of the spiral is 1.26 cm at the ``neutral position'' where Hr has its maximum value. The pitch is proportional to the ⅗ power of the rate of decrease of the field.
At the neutral position the beam enters a radial electric field which deflects it outward more sharply. If this field, and the magnetic field with it, extends a distance of about a tenth of the orbit radius beyond the orbit, the electrons will be collimated into a beam whose angular divergence is approximately proportional to (H/E)¾, where H is the magnetic field at the orbit and E the electric deflecting field. With H = 10 kilogauss and E = 60 kv/cm, the angular divergence will be of the order of ten degrees. Curves showing the dependence of the angular divergence on E/H and on the distance to which the fields extend are presented.
High Voltage Pulser for 184-Inch Cyclotron Electric Deflector
Authors: Kerns Q. A. , Baker W. R. , Edwards R. F. , Farly G. M. 
Published: February 2005

This paper describes a high voltage pulse generator developed to deflect the beam of the 184-inch cyclotron at Berkeley, California. The apparatus develops a deflecting potential of 200 kilovolts that rises from 10 percent to 90 percent of peak value in 0.1 microsecond. The unit employs two similar 100 kilovolt water cooled pulse transformers connected symmetrically about ground to the electric deflector bars. Water-cooled General Electric pulse capacitors are discharged through the two turn primary windings of the pulse transformers by triggering a battery of 16 paralleled Kuthe 5C22 hydrogen thyratrons.
Output voltages are developed across the 17-turn secondary winding of the pulse transformer. The transformer is mounted in an oil-filled Lucite case that provides both insulation and compact design.