Showing papers by "Stevens Institute of Technology published in 1970"

Gravitational collapse of magnetic neutron stars

Abstract: Pulsars are presently believed to be rotating neutron stars with frozen-in magnetic fields. Because of the high density of neutron stars, general relativistic effects are important since they effect both the structure and stability of such stars. Besides this, the magnetic field outside the star is also affected. Instead of falling of asr (2+l) as in flat space, it is shown that each magnetic multipole varies as a hypergeometric function of radius. A closed form of these hypergeometric functions is given in terms of Legendre functions of the second kind. If the mass of a neutron star exceeds about 2.4m ⊙, the star becomes unstable and coliapses. For a quasistatically collapsing body, it is shown that the magnetic field seen by a distant observer vanishes as the radius approaches the gravitational radius.

Multilayer adsorption of 3 He and 4 He on zeolite from 4 K to 80 K

Abstract: The adsorption isotherms of4He, N2, and argon have been measured on synthetic zeolite (Linde Molecular Sieve 13X) at 78 K, and of3He and4He, also on zeolite 13X, in the temperature range 4 K to 20 K. The results are presented in tabular and graphical form. The N2 isotherms, which showed characteristic step-like behavior, served to assess the specific surface area, which was 527 m2 g−1 based on a “standard” N2 molecular area of 16.2 A2. It also provided a value ofE 1 equal to 2530 cal mole−1. The argon isotherm at 78 K yielded a specific surface area for the zeolite 13X in fair agreement with that from the N2 data. Nine isotherms were taken for4He between 4 K and 20 K and four for3He in the same temperature range. These isotherms permitted good evaluations of the isosteric heats of adsorption to be made and plotted as a function of coverage, yielding, for4He,Q st =1580 j mole−1 at zero coverage,Q st =1030 j mole−1 at monolayer coverage andE 2=480 j mole−1 at two-layer coverage. For3He, which showed everywhere smaller Q st values. Q st =1420 at zero coverage. By use of the Steele equation applied to4He, we found that the monolayer coverageV m1 ≈ 0.29 cm3 (STP) m−2, and the second-layer coverage,V m2 ≈ 0.10 cm3 (STP) m−2.

Does a superconductor without long-range order have an energy gap?

Abstract: Marcelja's theory of a superconductor without long-range order is cast in a microscopic form. As a consequence, it is found that such a superconductor is gapless. Therefore, measurements of the tunneling density of states should provide a test of this theory.

Flux flow velocity in superconducting films by measurement of passage time

Abstract: The velocity of flux tubes in thin superconducting films has been determined by measuring the time for their passing across the film. A legion of flux tubes has been pulsed in on the left side of a film carrying a current large enough to break the pinning. The arrival of the flux tubes on the right side is observed with a pick-up coil. Flow velocities of 3 to 50×104 cm/sec have been observed with current densities up to 105 A/cm2.

Magnetic Bundles in Reacting Flowing Plasma

Abstract: An exact theory of plasma filaments observed in coaxial accelerators is derived from a steady-state ($\frac{\ensuremath{\partial}}{\ensuremath{\partial}t}=0$) description of the three-dimensional flow of deuterium plasma. Ionization and recombination reactions are considered. Magnetic structure of the filaments (bundles of helical field lines), density distributions, and flow field fit the experimental evidence.

Extraparticle diffusional effects in gel permeation chromatography. II. Experimental results

Abstract: Experiments coupled with a systems analysis were conducted on chromatogram dispersion, or zone broadening, in gel permeation chromatography (GPC). Three components of a Waters Associates Model 200 chromatograph, each of which is a potential cause of dispersion, were considered; these are: the packed column, with extraparticle dispersion only; the empty tubing, between pump and columns, columns and detector, etc.; and the detection system, viz., the differential refractometer cell. Toluene solvent was used and the solutes whose dispersion was studied included orthodichlorobenzene (ODCB) and narrow-molecular-weight polystyrene standards having molecular weights of 900, 20,400, 51,000, 97,200, and 160,000. Nonporous glass beads, 50 μ in diameter, were used as column packing. Two diameters, 1 mm and 0.5 mm, of stainless steel tubing were studied. In addition to the usual rectangular pulse sample injection, a step input mode for solute introduction was also used. The empty tubing was found to contribute significantly to the degree of dispersion and to skewness of elution curves. Anomalous bimodal characteristics of the elution curves were also observed which could only be ascribed to the empty tubing. These phenomena depended markedly on parameters such as tube diameter and length, and solute concentration and molecular weight. Dispersion in the packed column, although important, was found to be symmetrical (Gaussian) and less sensitive to these parameters than in the empty tubing, especially with respect to molecular weight. Dispersion in the cell was believed to be insignificant relative to the packed column and empty tubing.

Dimensions of Currents and Current Commutators

Abstract: We study the scale dimensions of current components and Schwinger terms. We state and prove necessary and sufficient conditions for the spatial and temporal components of hadronic currents to have the same dimension. The incompatibility of well-defined $c$-number Schwinger terms with universal dimensionality of current components is demonstrated. Experimental implications are discussed.

Kinetics of autoxidation of atactic polypropylene by infrared spectroscopy.

Abstract: : The autoxidation of a film of atactic polypropylene was studied by means of infrared spectroscopy. Reaction temperatures varied from 110 to 135C and oxygen concentrations from 5 to 100% by volume. A general reaction scheme previously reported for the autoxidation of polyolefins was utilized for atactic polypropylene. Various results obtained for this polymer were compared with those previously reported for isotactic polypropylene. (Author)

Extraparticle diffusional effects in gel permeation chromatography. I. Theory

Abstract: A systems approach is applied to the analysis of chromatogram resolution dispersion, or zone broadening, in gel permeation chromatography (GPC). Three possible sources of dispersion are considered; these are: the packed columns; the empty tubing between pump and columns, columns and detector, etc.; and the detection system, viz., the differential refractometer cell. It is shown that empty tubing can contribute significantly to the degree of dispersion and to skewness of elution curves and that this dispersion should depend on molecular weight of solute (polymer) and diameter and length of the tubing. The importance of dispersion in the empty tubing is compared with that in the packed columns and refractometer cell.

Relativistic Boltzmann Theory and the Grad Method of Moments

Abstract: It has been the custom, when writing on relativistic Boltzmann theory, to justify such studies by recounting the various physical systems to which they can apply. By now one is sufficiently acquainted with relativistic plasmas, massive stellar systems and the like to make such justifications unnecessary. While applicability is of course the final justification for any physical theory, there is one other that I would like to mention briefly. It is the aesthetic appeal, so often emphasized by Dirac. The relativistic Boltzmann equation is both simple and elegant. From it one can obtain many beautiful results, such as those of Ehlers, Gerun and Sachs. It brings into play virtually the whole of relativity theory in one way or another and is amenable to analysis by such modern mathematical techniques as fiber bundle theory. It also affords a unifying view that is lacking in the classical theory, One need only compare the classical and relativistic treatments of radiative transfer theory, which is a special application of the Boltzmann equation to zero rest-mass particles to appreciate this fact. Finally I would mention that, even in the more mundane matter of finding approximate solutions, there are decided advantages to a relativistic treatment over the corresponding classical treatment.

Several circuit applications of amorphous semiconductors

Abstract: The incorporation of amorphous semiconductor devices in several circuit applications is presented considering such aspects as linear amplification, ternary threshold logic, and clocked binary gates. The circuit descriptions are brief in favor of presenting the principles of operation. Detail design data are available from laboratory reports and published papers appropriately cited in the paper. Working laboratory models were “breadboarded” for each of the circuits, however, it is cautioned that a hand selection of devices was required. Furthermore, no attempt in optimization was made. It is believed that with modification, while retaining basic principles considerable improvement in circuit performance can be achieved. It may be that crystalline semiconductor devices would avail circuits usually simpler in concept and design than those which are described here. However, the virtues of the circuits discussed herein, lie in their novelty as an application of new circuit elements that may yield ideas for improving their methods of application or give insight into new methods of employing these devices.

Allport-Vernon-Lindzey Study of Values: 1. Factor Structure for a Combined Sample of Male and Female College Students

Abstract: A principal components analysis was performed on the self-ratings (for a combined sample) obtained from the Allport-Vernon-Lindzey Study of Values (N = 150 combined sample of 102 male and 48 female...

Rho-dominance and a new family of sum rules for pion-baryon scattering

Abstract: A family of sum rules for the scattering of pions from spin-one-half baryon targets is presented. The derivation of the sum rules is based on the assumptions of i) unsubtracted dispersion relations for both the forward and the backward amplitudes (nonflip, flip and theA amplitudes) corresponding to unit isospin in thet-channel, and ii) rho-dominance (near direct-channel threshold) of thet-channel contributions in the dispersion relations for the backward amplitudes. In the πN sector, where a direct verification of our sum rules is possible, they are in satisfactory agreement with the available experimental data. Resonance saturation of our sum rules in the πΣ sector together with the assumption of universal rho-hadron coupling yields the isovector magnetic moment of Σ in good agreement with theSU3 prediction. As for pion-baryon coupling our sum rules in both the πΣ and πΞ sectors are consistent withSU3 symmetry withF/D ratio ∼ 2/3. Our analysis of the πΞ sum rules further suggestes the spin-parity assignmentJP=5/2− for Ξ* (1930).

A method for computing float platform motions in waves

Abstract: A new procedure is presented for the prediction of the longitudinal motions, in regular head seas, of ocean platforms supported by slender vertical floats Experimental information describing the hydrodynamic forces acting on the floats is used to solve the equations of motion for harmonic oscillation in heave, surge, and pitch These hydrodynamic forces are obtained from tests conducted on a single isolated float They are expressed as two separable parts, one due to the disturbance imposed by the waves acting as though the vehicle were completely restrained and one due to the motion of the vehicle as though there were no wave disturbance When the measured motions of a free four-float vehicle are compared with the motions as computed under the new procedure, reasonably good agreement is found The approach should be useful in design development and in structural load evaluation not only for multifloat vehicles but for other types of marine structures as well

Stability of supercurrents in cylindrical films of tin

Abstract: Using pulsed currents of 80-nsec duration the stability of supercurrents in cylindrical films with current return through the center has been investigated. It is found that the voltage along the film rises with timet approximately asV = a[1 − erf(t′/2(t − c))1/2] where the time constantt′ is an exponentially decreasing function ofi(1 + 420/d)/(1 −(T/Tc)4). Herei is the current through the sample,d the thickness of the film in angstroms, andT/Tc the reduced temperature. Comparison with older data by Mydosh and Meissner and by Hagedorn indicates that it is indeed the currenti, rather than the current densityJ, which determinest′. It is suggested that the instability is of the nature of those investigated by Kramer and by Fink and Presson for currents in a superconducting surface sheath.

Separation of gaseous mixtures by permeation through polyethylene film

Abstract: The permeation of polyethylene film by carbon dioxide, ethane, and propane at elevated pressures was investigated. In addition, the separation of mixtues of ethane and propane by permeation was studied. Both hydrocarbon vapors' permeation exhibited pressure dependence, with propane showing the greatest variation over the same range. In the case of the mixture separation study, the achieved degree of separation was lower than would be predicted on the basis of the pure component permeation constants. Moreover, the total flow of vapor through the film was greater than would be expected on the basis of the individual gas flows. This was attributed to an anomalous diffusion phenomenon of ethane in the presence of dissolved propane due to a plasticization of the polymer network.

Thermomechanical studies of polymer deformation. ii. a thermodynamic analysis of a viscoelastic material in sinusoidal deformation.

Abstract: In this study, a linearly viscoelastic polyurethane film was subjected to continuous, sinusoidal deformation in a new isothermal deformation calorimeter, whose design details were recently reported (1). Internal energy and entropy of the polymer at each state in the deformation cycle were computed from heat rate and work rate data. This was made possible by using linear viscoelasticity theory to predict the irreversible entropy production. Thermal data were corrected for instrument time lag.