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Showing papers by "Stevens Institute of Technology published in 1969"



Journal ArticleDOI
TL;DR: In this article, the effect of fluctuating Cooper pairs on the diamagnetic susceptibility of superconductor above the critical temperature was investigated and it was shown that the effect is greatest in a clean metal where the extra susceptibility is about 1/2$ in a bulk sample.
Abstract: Fluctuating Cooper pairs contribute to the diamagnetic susceptibility in a superconductor above the critical temperature. The effect is the greatest in a clean metal where the extra susceptibility is about ${10}^{\ensuremath{-}7}\ifmmode\times\else\texttimes\fi{}{[\frac{{T}_{c}}{(T\ensuremath{-}{T}_{c})}]}^{\frac{1}{2}}$ in a bulk sample.

172 citations


Journal ArticleDOI
TL;DR: In this article, a general covariant set of electromagnetic field equations and associated constitutive relations is developed to deal with electromagnetic radiation in arbitrarily moving media, which is sufficiently general to include dispersive as well as nonisotropic media.
Abstract: A generally covariant set of electromagnetic field equations and associated constitutive relations is developed to deal with electromagnetic radiation in arbitrarily moving media. The equations are sufficiently general to include dispersive as well as nonisotropic media. Several special cases are investigated to illustrate the method and to demonstrate the consistency of the formulation.

83 citations


Journal ArticleDOI
01 Jan 1969
TL;DR: In this article, an experimental and theoretical investigation of the fundamental mechanism by which a flame spreads over the surface of a condensed-phase materials in a quiescent gaseous environment containing a component with which it can react chemically is described.
Abstract: This paper describes an experimental and theoretical investigation of the fundamental mechanism by which a flame spreads over the surface of a condensed-phase materials in a quiescent gaseous environment containing a component with which it can react chemically. It is postulated that the advancing flame vaporizes the surface material lying before it. As these vapors diffuse away from the surface, they undergo an exothermic reaction with the chemically active component in the gaseous environment, and ignite; thus, flame spreading is viewed as continuous diffusive, gas-phase ignition. Flame-spreading velocities have been measured for a variety of solid materials in O2/inert environments between 4 and 415 psia. Well-defined experimental, conditions yielded reproducible results, and thus suggest that flame-spreading, velocity is an intrinsic combustion quantity. All data can be correlated by a power-law relationship between the flame-spreading velocity (V) and two gas-phase parameters-pressure (P) and reactive component mole fraction (Yox)—in the form V ∞ ( P Y m ) Φ . It is concluded that V is controlled by a gas-phase physical process—probably either heat or mass transfer—which supports the mechanism proposed. Temperature distributions ahead of the propagating flame were obtained from surface-mounted, fine-wire thermocouples. The temperature level as the flame passes over the thermo-couple bead is independent of P, Yox, and inert diluent, and about 120°C below that measured previously during steady-state vaporization. Thus, it is concluded that direct surface attack by oxygen is unimportant during flame spreading and that the transient vaporization phenomenon is probably quite different than that of steady pyrolysis. The mathematical statement of the postulated flame-spreading mechanism is sufficiently complex that a complete analytical solution is currently impossible. Postponing numerical solutions, simplistic analyses were conducted that resulted in predicted flame-spreading characteristics that were well supported by the data obtained over the entire range of experimentation. Based on the evidence presented, the authors conclude that the postulated theory is probably valid, and engineering design of systems involving flame-spread control now can be put on a rational basis.

52 citations


Journal ArticleDOI
TL;DR: In this article, a detailed analysis of magnetic field effects on the static shielding of a point Coulomb impurity charge by a quantum plasma is presented, and the results show that the strong anisotropy induced by the magnetic field in this limit destroys the long-range character of the Friedel-Kohn (FK) wiggle.

35 citations


Journal ArticleDOI
TL;DR: A series of spiro-β-lactams have been prepared by the reaction of various acid chlorides with the anils of cyclohexanone, cycloheptanone and N-methylpiperidone in presence of a tertiary amine as mentioned in this paper.

25 citations



Journal ArticleDOI
TL;DR: In this article, the scattering matrix for an ideal (2/sup n/1) port combiner, formed by interconnecting magic-tee hybrids, is developed, which is then used to describe a coherent power-summing technique for injection-locked oscillators for n = 3.
Abstract: The scattering matrix for an ideal (2/sup n/+1) port combiner, formed by interconnecting (2/sup n/-1) magic-tee hybrids, is developed. This matrix is then used to describe a coherent power-summing technique for 2/sup n/ injection-locked oscillators for n=3. The losses that arise from combining oscillators with different injection-locking characteristics are evaluated by two methods: 1) expressions for the output power and loss of the combiner as functions of the input signals are obtained with amplitude and phase as parameters; 2) a semigraphical solution for the combined output and loss is obtained by means of a flow chart and computer-generated gain, loss, and phase characteristics of a single-hybrid junction. The amplitude and phase balance required between individual oscillators for efficient power addition is described, giving the engineer a quantitative measure of the multiple-oscillator design requirements.

19 citations



Journal ArticleDOI
TL;DR: In this paper, the effect of room temperature first order transition on the plastic yield behavior of polytetrafluoroethylene (PTFE) has been investigated, and the experimental observations suggest a model of the solid-state structure of PTFE which could be described as an "elastic-plastic network", in which crystalline domains are connected by elastic amorphous regions, and in which the crystaline domains can flow plastically at sufficiently high stress or temperature.
Abstract: : The effect of the room temperature first order transition on the plastic yield behavior of polytetrafluoroethylene (PTFE) has been investigated. Stress-strain curves were measured at different strain rates and temperatures. Tensile creep under constant dead load was also measured as a function of temperature and stress level. The effect of degree of crystallinity was investigated by using both a rapidly quenched and slow cooled polymer. The curve of yield stress vs temperature in the temperature range from -50 to +68C was found to be almost identical with the curve of elastic modulus vs temperature: the yield stress shows a marked local decrease at the first order transition. The experimental observations suggest a model of the solid-state structure of PTFE which could be described as an 'elastic-plastic network', in which crystalline domains are connected by elastic amorphous regions, and in which the crystalline domains can flow plastically at sufficiently high stress or temperature. (Author)

14 citations


Journal ArticleDOI
TL;DR: In this paper, a superconductor in a state of supercurrent flow and near the transition temperature is exposed to an alternating electric field, and the induced alternating current is shown to exhibit a frequency dependence.
Abstract: The situation is investigated in which a superconductor in a state of supercurrent flow and near the transition temperature is exposed to an alternating electric field. The induced alternating current is shown to exhibit a frequency dependence ${(1\ensuremath{-}i\ensuremath{\Omega}{\ensuremath{\tau}}_{\mathrm{R}})}^{\ensuremath{-}1}$, which is due to a relaxation process in the Cooper-pair density. The relaxation time ${\ensuremath{\tau}}_{\mathrm{R}}$ is determined by electron-phonon collisions (collision time ${\ensuremath{\tau}}_{c}$), in which case ${\ensuremath{\tau}}_{\mathrm{R}}\ensuremath{\simeq}{\ensuremath{\tau}}_{c}{[\frac{{T}_{c}}{({T}_{c}\ensuremath{-}T)}]}^{\frac{1}{2}}$; impurity scattering is important only under certain conditions, in which case ${\ensuremath{\tau}}_{\mathrm{R}}\ensuremath{\simeq}{10}^{\ensuremath{-}11}{[\frac{{T}_{c}}{({T}_{c}\ensuremath{-}T)}]}^{\ensuremath{-}5}$ sec.

Journal ArticleDOI
TL;DR: The model mentioned in the title is derived from the Ginzburg-Landau free energy expression without quantisation of the order parameter as discussed by the authors, and it is shown that the model can be expressed as
Abstract: The model mentioned in the title is derived from the Ginzburg-Landau free energy expression without quantisation of the order parameter.

Journal ArticleDOI
TL;DR: In this paper, the autoxidation of a film of isotactic polybutene-1 (IPB) containing a large amount of metallic ash (about 0.2%) was studied by means of infrared spectroscopy.
Abstract: : The autoxidation of a film of isotactic polybutene-1 (IPB) containing a large amount of metallic ash (about 0.2%) was studied by means of infrared spectroscopy. Reaction temperatures were varied from 105 to 120C and oxygen concentrations from 25 to 100% by volume. A reaction scheme previously reported for the autoxidation of atactic polybutene-1 (APB) was utilized for the IPB. Various results obtained for IPB were compared with those previously reported for APB. (Author)

Journal ArticleDOI
TL;DR: In this article, a relatively simple and a more general kinetic scheme with corresponding rate expressions were used for the autoxidation of poly(ethylene glycol) (PEG) and polypropylene glycol (PPG) in solution at relatively long reaction times.
Abstract: : Data reported for the autoxidation of poly(ethylene glycol) (PEG) and poly(propylene glycol) (PPG) in solution at relatively long reaction times were analyzed. A relatively simple and a more general kinetic scheme with corresponding rate expressions were used. It was found that the more general scheme gave somewhat more satisfactory agreement between calculated and observed values of several reaction variables. Limitations in the applications of both schemes to PEG and PPG autoxidations are mentioned.

Journal ArticleDOI
TL;DR: In this paper, the stereochemistry of lyratol and the structure of its reduction products were deduced from a study of their NMR spectra, which confirmed the modified isoprenoid structure.

Journal ArticleDOI
TL;DR: A significant violation of the $\ensuremath{\Delta}I=\frac{1}{2}$ rule has been detected in the decay of the squared matrix elements of the Euclidean space as mentioned in this paper.
Abstract: A significant violation of the $\ensuremath{\Delta}I=\frac{1}{2}$ rule has been detected in ${K}^{+}\ensuremath{\rightarrow}3\ensuremath{\pi}$ decay. The ratio of the coefficients of the linear terms in the squared matrix elements of ${\ensuremath{\tau}}^{\ensuremath{'}+} ({K}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}+2{\ensuremath{\pi}}^{0})$ and ${\ensuremath{\tau}}^{+} ({K}^{+}\ensuremath{\rightarrow}2{\ensuremath{\pi}}^{+}+{\ensuremath{\pi}}^{\ensuremath{-}})$ is found to be -2.63 \ifmmode\pm\else\textpm\fi{} 0.18 (as compared with the $\ensuremath{\Delta}I=\frac{1}{2}$ rule prediction of -2), when the results of the Riverside ${\ensuremath{\tau}}^{\ensuremath{'}+}$ experiment are used together with the results of the present ${\ensuremath{\tau}}^{+}$ experiment.

Journal ArticleDOI
TL;DR: Asymmetric spinning sidebands appear in the NMR spectrum of material contained in the annular region of a coaxial cell as mentioned in this paper, caused by linear gradients in the magnetic field.

Journal ArticleDOI
TL;DR: In this paper, a deformation calorimeter based on differential thermometry and using a flowing gas stream as a heat transfer medium is described, which allows it to operate under near-isothermal conditions.
Abstract: : The purpose of the paper is to describe a new deformation calorimeter, which is based on differential thermometry and uses a flowing gas stream as a heat transfer medium which allows it to operate under near-isothermal conditions. Also presented are some preliminary test measurements with a crosslinked polyurethane elastomer and crystalline polybutene-1. (Author)


Journal ArticleDOI
TL;DR: In this paper, the rate constants for the autoxidation of isotactic polypropylene based upon a postulated relatively simple scheme were calculated using electron spin resonance, volumetric and chemical techniques.
Abstract: : Recently the rate constants for the autoxidation of isotactic polypropylene based upon a postulated relatively simple scheme were calculated. Electron spin resonance, volumetric and chemical techniques were employed. This paper demonstrates that similar values of these rate constants could also be calculated from a more general scheme. From this general scheme, expressions were derived which involved the rate constants of interest and other constants which had been previously calculated from experimental data based upon the use of infrared absorption techniques. The values of the calculated rate constants at various temperatures agreed well with those reported earlier where comparison was possible. (Author)

Proceedings ArticleDOI
05 May 1969
TL;DR: An outline is presented that informally describes some research areas that have been under investigation and some of the results uncovered to date are described.
Abstract: A mathematical framework is defined in which many questions concerning uniform arrays of finite-state machines can be formulated and studied. An outline is then presented that informally describes some research areas that have been under investigation. Some of the results uncovered to date are described and many open problems are stated.

Journal ArticleDOI
TL;DR: In this article, a new approach based on the fact that the assumed Birnbaum chordwise modes are not linearly independent has achieved stability for the chordwise distribution, which had otherwise shown no sign of convergence with increasing number of modes.
Abstract: Improvements are reported in the numerical procedure for evaluating propeller loading distributions which has been developed at Davidson Laboratory by adaptation of the unsteady-lifting-surface theory. A new approach, based on the fact that the assumed Birnbaum chordwise modes are not linearly independent has achieved stability for the chordwise distribution, which had otherwise shown no sign of convergence with increasing number of modes. Other refinements of the numerical program, including provision for arbitrary blade camber variation and overlapping of blade wakes have improved the accuracy of both chordwise and spanwise loading distribution and brought the theoretical results closer to experiment.

Journal ArticleDOI
TL;DR: In this article, the influence of the nonlinearity of the free surface condition on the wave-induced forces acting on a submerged sphere in a steady translation is investigated, and it is shown that the second-order forces derived from the linearized homogeneous freesurface condition are quite discernible.
Abstract: Nonlinear effects on the wave-induced forces acting on a submerged sphere in a steady translation are investigated. A recent endeavor by Tuck indicates that in the case of a submerged cylinder the forces due to the nonlinearity of the free surface are quite discernible in comparison with the second-order forces derived from the linearized homogeneous freesurface condition. The purpose of the present work is to assess the influence of the nonlinearity upon a three-dimensional water-wave problem.

Journal ArticleDOI
TL;DR: A new method for determining the steady and unsteady pressure distributions on lifting surfaces is presented which is found to be a more accurate, versatile, and rapid procedure for inverting the downwash integral equation than the presently used "mode-collocation" method.
Abstract: A new method for determining the steady and unsteady pressure distributions on lifting surfaces is presented. The method employs a "generalized lift-operator" technique which is found to be a more accurate, versatile, and rapid procedure (requiring less computer time) for inverting the downwash integral equation than the presently used "mode-collocation" method. The generalized lift-operator technique allows the chordwise integration to be carried out analytically, thereby avoiding the difficulties in the presently used method. This new approach has been applied to several two-dimensional, unsteady airfoil problems to demonstrate compatibility with known explicit solutions. Numerical solutions for two rectangular foils of aspect ratio 1 and 2 are also presented. The values show good agreement with experiment and fit in with known trends.

Journal ArticleDOI
TL;DR: In this paper, the stability of supercurrents in the critical depairing regime was investigated and it was shown that the supercurrent decreases with increasing momentum of the Cooper pairs.
Abstract: Considering the proposal of Fulde and Ferrell on electron depairing in super-conductors, we investigate the stability of the supercurrents in the critical depairing regime where the supercurrent decreases with increasing momentum of the Cooper pairs. We find that this region is unstable and that disturbances (due to fluctuations) grow exponentially in time.

Journal ArticleDOI
TL;DR: In this article, it was shown that the theoretical value in 0 \ensuremath{\rightarrow} 0 Fermi transitions is independent of model-dependent effects induced by the axial current.
Abstract: We show that to first order in $\ensuremath{\alpha}$, and with neglect of effects which vanish in the limit of zero lepton momenta, the theoretical $\mathrm{ft}$ value in 0 \ensuremath{\rightarrow} 0 Fermi transitions is independent of $Z$. The only model-dependent feature of this argument is in the treatment of effects induced by the axial current. It is further shown that in higher order radiative corrections the power of $Z$ cannot exceed the power of $\ensuremath{\alpha}$; the leading term in the radiative correction to the $\mathrm{ft}$ value is therefore of order ${Z}^{2}{\ensuremath{\alpha}}^{2}$.

Journal ArticleDOI
TL;DR: In this article, the properties of a series of polymers based upon various aromatic diamines and several isomeric diketones were investigated and compared in air and under a nitrogen atmosphere.
Abstract: This investigation was undertaken to determine the properties of a series of polymers based upon various aromatic diamines and several isomeric diketones. Consequently, six isomeric polymers were synthesized by the acid-catalyzed polycondensation of p- and m-dibenzoylbenzene with o-, p-, and m-phenylenediamine. Two fluorine-containing, isomeric polymers were also synthesized by condensing m-dibenzoylbenzene with tetrafluoro-m-phenylenediamine and tetrafluoro-p-phenylenediamine. Comparative thermal stabilities of the products both in air and under a nitrogen atmosphere were investigated by thermogravimetric analysis. Several of the polymers exhibited a high degree of thermal stability and all of the polymers exhibited essentially the same resistance to initial thermal decomposition in the oxidative as well as the nonoxidative atmosphere. A correlation of molecular structure and geometry with thermal stability and solubility is discussed and a mechanism for initial thermal decomposition of some of ...

Journal ArticleDOI
TL;DR: In this paper, a device to selectively introduce gases into a melt of KCl from which single crystals or oriented bicrystals are being pulled is described, and the insoluble gases (e.g. Ar, Cl2, N2, and CO2) are incorporated into the growing crystals in the form of bulk and grain boundary bubbles having a decided crystallographic appearance.
Abstract: A device to selectively introduce gases into a melt of KCl from which single crystals or oriented bicrystals are being pulled is described. The insoluble gases (e.g. Ar, Cl2, N2, and CO2) were incorporated into the growing crystals in the form of bulk and grain boundary bubbles having a decided crystallographic appearance. The as-grown bubbles of Ar and Cl2 were extended along the growth axis, whereas those of N2 and CO2 were compressed in this direction. The bubble shapes are expected to depend on surface energy considerations and on the way in which the gas interacts with the solid; the bubble geometries were qualitatively consistent with available data on the theoretical adsorption behavior of these gases on (100) crystal faces of KCl. On annealing under load, the bubbles became highly faceted. Only the very stable (100) plane developed; this indicates the extreme anisotropy of the surface energy even at temperatures approaching the melting point. The failure of bubbles to evolve completely into cubes is probably due to the difficulty of establishing growth habits normal to the (100) plane.

Journal ArticleDOI
TL;DR: In this paper, the authors trace and analyze the evolution of the main stream of the theory of the economy in the United States and propose three main streams of the thought of the economic system.
Abstract: THE PURPOSE OF THIS PAPER IS TO TRACE AND ANALYZE THE EVOLUTION OF THE MAIN STREAMS OF THOUGHT OF ENGINEERING ECONOMY IN THE UNITED STATES. ENGINEERING ECONOMY, OR ECONOMICS, IS TO BE DEFINED AS A GUIDE FOR THE ECONOMIC SELECTION AMONG TECHNICALLY FEASIBLE ALTERNATIVES FOR THE PURPOSE OF A RATIONAL ALLOCATION OF SCARCE RESOURCES. IT IS IMPORTANT TO ADD THAT THE ULTIMATE SELECTION AS TO THE PREFERRED ALTERNATIVE MAY BE MADE ON GROUNDS OTHER THAN ECONOMIC, BUT THIS IS NOT WITHIN THE SCOPE OF THIS PAPER. THERE ARE THREE SEPARATE BUT DISCERNIBLE HISTORICAL STREAMS OF THOUGHT HAVING VARIOUS POINTS OF TANGENCY WHICH FIT WITHIN THE CONFINES OF THIS DEFINITION. THESE ARE: CLASSICAL ENGINEERING ECONOMY, AND RESOURCES DEVELOPMENT WHICH IN TURN IS DIVIDED INTO BENEFIT-COST ANALYSIS AND ECONOMIC ANALYSIS --WHICH ARE NOT MUTUALLY EXCLUSIVE. EACH IS DESCRIBED. /AUTHOR/

Journal ArticleDOI
TL;DR: In this article, Bawn and Chaudhri reported a general scheme with corresponding kinetic expressions for the uncatalyzed thermal autoxidation of polyolefins such as atactic polybutene-1 (APB) in the bulk phase.
Abstract: The authors had previously reported a general scheme with corresponding kinetic expressions for the uncatalyzed thermal autoxidation of polyolefins, such as atactic polybutene-1 (APB), in the bulk phase. Recently, Bawn and Chaudhri reported that similar kinetic expressions and scheme were also applicable to autoxidation of atactic polypropylene (APP) in solution. These workers did not attempt to correlate their results for the effect of oxidation on the molecular weight of APP as evidenced by intrinsic viscosity. In this paper, we have applied expressions, previously reported for changes in intrinsic viscosity as a function of time during the autoxidation of APB in the bulk phase, to the data provided by Bawn and Chaudhri for the autoxidation of APP in solution. The quantitative evidence obtained indicates that the intrinsic viscosity relationships which were found to be valid for the autoxidation of APB in the bulk phase are also valid for the autoxidation of APP in solution (at polymer concentrations of ca. 1.5M and above).