Showing papers by "Rensselaer Polytechnic Institute published in 1970"
01 Jan 1970
TL;DR: Linear high polymers heat capacity measurements theory emphasizing simple mechanical systems and contribution of lattice vibrations was introduced in this article, where the authors proposed a heat capacity measurement theory based on the lattice vibration model.
Abstract: Linear high polymers heat capacity measurements theory emphasizing simple mechanical systems and contribution of lattice vibrations
274 citations
TL;DR: In this paper, a nonlinear model is used to describe an experimental situation in which solidification is controlled so that the mean position of the interface moves with constant speed, and it is found that the interface can be unstable to finite amplitude disturbances even when linear stability theory predicts stability to infinitesimal disturbances.
Abstract: An investigation is made of the stability of the shape of a moving planar interface between the liquid and solid phases in the freezing of a dilute binary alloy. A nonlinear model is used to describe an experimental situation in which solidification is controlled so that the mean position of the interface moves with constant speed. The model postulates two-dimensional diffusion of solute and heat such that: 1. Convection in the liquid is negligible. 2. Diffusion of the solute in the solid is negligible. 3. Solute concentration in the liquid is small. 4. The effects of interface attachment kinetics are negligible. 5. The extent of the liquid and solid phases is infinite. 6. c8=c1 where c8(c1) is the specific heat per unit volume of the solid (liquid). 7. (D/Dth) 1, , where D is the diffusion coefficient of the solute in the liquid and Dth is the thermal diffusivity in the liquid. 8. G= G where G is the imposed temperature gradient in the liquid and Gcis the critical value of G at which linear theory predicts the onset of instability. The analysis is expected to be asymptotically valid as G-Gc. It is found that the interface can be unstable to finite amplitude disturbances even when linear stability theory predicts stability to infinitesimal disturbances. Further, cellular structure can be anticipated for certain ranges of parameter values. These results are in accord with relevant experimental evidence.
205 citations
TL;DR: In this article, the problem of the POROUS ELASTIC LAYER of InFINITE LATERAL EXTENT, to the surface of which a UNIFORM PRESSURE is applied over an INFINITE STRIP or over a CIRCULAR AREA, is treated.
Abstract: LOADED CLAY STRATA SETTLE GRADULALLY DUE TO THE SQUEEZING OUT OF WATER FROM THE PORES OF THE SOIL. IT IS IMPORTANT FOR THE CIVIL ENGINEER TO BE ABLE TO ASSESS THE MAGNITUDE AND PROGRESS O THIS CONSOLIDATION SETTLEMENT. ANALYSIS HAS BEEN CONFINED TO CASES WHERE THE THICKNESS OF THE STRATUM IS VERY GREAT COMPARED WITH THE DIMENSIONS OF THE LOADED AREA. THE PROBLEM OF THE POROUS ELASTIC LAYER OF INFINITE LATERAL EXTENT, TO THE SURFACE OF WHICH A UNIFORM PRESSURE IS APPLIED OVER AN INFINITE STRIP OR OVER A CIRCULAR AREA, IS TREATED HERE. SOME RESULTS OF INTEREST ARE EVALUATED AND PRESENTED IN GRAPHICAL FORM. /AUTHOR/
131 citations
TL;DR: In this paper, the vibrational spectra of quinoline and isoquinoline were assigned to normal coordinate analysis using the Urey-Bradley Force Field including Kekule modification with force constants transferred from naphthalene and s -triazine.
95 citations
TL;DR: In this paper, characterizations of copositive plus matrices are given, together with relationships of these matrices with positive semidefinite matrices and their quadratic forms.
94 citations
TL;DR: Asymptotic buckling analyses of imperfect columns on nonlinear elastic foundations by perturbation expansions, equivalent linearization and truncated hierarchy approximations are presented in this article.
88 citations
01 Jun 1970
TL;DR: In this paper, the authors measured the resistance of austenite to plastic deformation (austenite flow stress) using a high temperature tensile apparatus and correlated the flow stress with the Ms temperature as determined magnetically during subsequent cooling.
Abstract: The resistance of austenite to plastic deformation (austenite flow stress) was measured using a high temperature tensile apparatus. The flow stress was then correlated with the Ms temperature as determined magnetically during subsequent cooling. In one part of the study, the flow stress of the austenite was varied only by work hardening the austenite, allowing the austenite composition, which is known to affect Ms, to be held constant. A decrease in Ms temperature with increasing austenite flow stress was observed. This observation was supported by the observation of a decrease in the amount of austenite transformed at 25°C. In the other part of the study, a series of alloy steels of different chemical compositions was tested. A decrease in Ms temperature with increasing austenite flow stress was again observed. Strengthening of austenite by plastic deformation was shown not to change the chemical driving force for transformation. The effect of deformation on Ms temperature thus results from its influence on either the nucleation or the growth process. While the effect of austenite deformation on martensite nucleation is uncertain, specific nucleation models can account for only approximately one-third of the nonchemical free energy change which accompanies transformation. A proposal, consistent with the observations, was made that the energy expended for the deformation of austenite during martensite plate growth could reasonably account for a substantial part of the nonchemical free energy change.
77 citations
TL;DR: In this article, the salt redistribution process occurring in the freezing of a NaCl solution was examined, and the factors responsible for controlling salt rejection were analyzed, and two parameters were found to control the redistribution process: (1) the liquid phase interface concentration which is controlled by constitutional supercooling, and (2) the thermal driving force imposed on the system to initiate and maintain freezing.
69 citations
TL;DR: The results indicate that the mechanisms of hydrolysis of 111, IV, and V (as that of the unsubstituted aziridine derivative, AB-100) are essentially sN2, in contrast to the much faster hy- drolysisOf the 2,2-dimethylaziridine analog,AB-132, which in- volves a carbonium-ion mechanism.
67 citations
65 citations
TL;DR: The elastic velocities in bovine dentine and enamel have been measured using ultrasonic interferometry and are in reasonable agreement with the ultrasonic velocITIES for human teeth as determined by other workers.
TL;DR: In this paper, the concepts of specific optimal control, trajectory sensitivity design, and perfect model following are integrated to develop a general design technique for the linear servo model following problem.
Abstract: The concepts of specific optimal control, trajectory sensitivity design, and perfect model following are integrated to develop a general design technique for the linear servo model following problem. Control laws designed by this procedure are characterized by partial state feedback, perfect model following when theoretically possible, relative insensitivity of the compensated plant to mathematical modeling inaccuracies, and plant-model realignment in the presence of state disturbances. The feasibility of the design technique is demonstrated by the design of a nontrivial aircraft control problem.
TL;DR: The present study of the standing gradient model shows that a relatively simple analytic treatment preserves the main features of the equations governing coupled solute and water flow in a long channel closed at one end.
TL;DR: The isomerization of s-triazolo[4,3-a]pyridines into s-Triazolo [1,5-a]-pyridine ring is greatly facilitated by electron withdrawing nitro substituents in the pyridine rings and retarded by electron donating amino groups as mentioned in this paper.
TL;DR: The authors investigated the relationship between Erikson's concept of ego identity and student attitudes toward college and found that students who were in the process of going through an identity crisis over occupational choice had the least favorable evaluations of their education while students who had never experienced a crisis but were, nevertheless, committed to a vocational goal held the most favorable attitudes.
Abstract: Two studies were conducted to investigate the relationship between Erikson's concept of ego identity and student attitudes toward college. The results of Study 1 indicated that students who were in the process of going through an identity crisis over occupational choice had the least favorable evaluations of their education while students who had never experienced a crisis but were, nevertheless, committed to a vocational goal held the most favorable attitudes. Study 2 demonstrated that students who went through crisis over choice of major field while in college showed more negative attitudes than did students not experiencing a crisis during their college years. These findings suggest that the association of crisis with college is an important factor in student dissatisfaction.
TL;DR: The MnO(2)-reductase activity of induced cells and extracts from them was no greater in the absence of oxygen than in its presence, confirming an earlier observation that MnO (2) and O(2) do not compete as terminal electron acceptors in the respiratory activity of this organism.
Abstract: Bacillus 29, isolated from a ferromanganese nodule from the Atlantic Ocean, was shown to possess an MnO(2)-reductase system which is induced in the presence of manganous ion. Maximal activity of the enzyme system was induced in about 5 hr in the presence of 4.35 mm MnSO(4) and was minimally dependent on the presence of either glucose or peptone and oxygen. Induction of optimal activity required the simultaneous presence of glucose and peptone. At least 30% of maximal activity was induced in 5 hr in the presence of 0.4 mum MnSO(4). Actinomycin D (5 mug/ml) or chloramphenicol (35 mug/ml), when added to the induction medium, inhibited approximately 90% of MnO(2)-reductase synthesis and incorporation of uracil-2-(14)C or leucine-1-(14)C. Cell-free extracts having MnO(2)-reductase activity were prepared by sonic disruption of cell suspensions of induced Bacillus 29. Such extracts used glucose metabolism as a source of electrons. They had an average specific activity of 1.15 nmoles of Mn(II) produced per mg of protein per hr at 25 C. They had a temperature optimum of 18 C for reductase activity and retained 50% of their activity at 4 C, the approximate temperature of the natural habitat of the organism. Extracts were stable for several days at 4 C but rapidly lost over 50% of their activity on freezing and thawing. Over 90% of the activity of the extract could be destroyed by heating in a boiling-water bath for 5 min. At a concentration of 1 mm, HgCl(2) and atebrine dihydrochloride inhibited MnO(2)-reductase activity by at least 50%, but sodium azide was ineffective. The MnO(2)-reductase activity of induced cells and extracts from them was no greater in the absence of oxygen than in its presence, confirming an earlier observation that MnO(2) and O(2) do not compete as terminal electron acceptors in the respiratory activity of this organism.
TL;DR: In this paper, the authors investigated the processes contributing to the anodic and cathodic off-gases in the electrolysis of the molten ternary eutectic, (Li, Na, K/CO 3 ) at 500°C. with a compartmented electrolysis cell and an on-stream gas chromatographic technique.
TL;DR: Several lines of evidence indicated that the mechanism by which Bacillus 29A carried out iron solubilization from limonite involved enzymatic reduction of the ferric iron in the mineral.
Abstract: Bacillus 29, previously isolated from a ferromanganese nodule, and a derivative strain,Bacillus 29A, were examined for their iron-solubilizing ability when reducing limonite, goethite and hematite with glucose.Bacillus 29A was the more active of the two cultures. It solubilized larger amounts of iron from limonite and goethite than from hematite. Several lines of evidence indicated that the mechanism by whichBacillus 29A carried out iron solubilization from limonite involved enzymatic reduction of the ferric iron in the mineral. Phenosafranin enhanced the reduction of the iron oxides by growing cultures, but anaerobiosis did not.
TL;DR: In this paper, a separable expansion for local potentials, called the unitary pole expansion, has real, energy-independent form factors, and satisfies the requirements of two-particle unitarity in all orders.
Abstract: We introduce a new separable expansion for local potentials. The expansion, called the unitary pole expansion, has real, energy-independent form factors, and satisfies the requirements of two-particle unitarity in all orders. The convergence of the expansion is investigated by comparing expanded and exact $T$ matrices for negative energies, and by performing three-body bound-state calculations. In the latter case, a one-term approximation gives energies accurate to within 2% for potentials containing repulsion of the magnitude indicated by two-nucleon data.
TL;DR: In this paper, an experimental investigation has been made of the flow patterns at the initiation of convection in a layer of a high Prandtl number liquid confined between rigid, horizontal surfaces and heated from below.
Abstract: An experimental investigation has been made of the flow patterns at the initiation of convection in a layer of a high Prandtl number liquid confined between rigid, horizontal surfaces and heated from below. The experiment was designed to overcome the limitations of earlier experiments and to correspond closely to the conditions of the theory. In particular, the upper and lower rigid surfaces which enclosed the layer were made of copper which has a high thermal conductivity. To aid in the analysis of the experimental results some supplementary observations of the flow patterns were made using a glass upper plate. For small fluid depths and large temperature differences between the upper and lower surface the initial flow was in the form of hexagonal cells as predicted theoretically. With increasing Rayleigh number the cellular flow appeared to transform into rolls as predicted. For large fluid depths and small temperature differences only circular plan-form rolls were observed. This is in agreement with the results of other experimenters. It is tentatively proposed that this non-appearance of an initial cellular flow is due to the shape of the test chamber having a dominating influence on the flow pattern when the temperature gradient in the fluid is small. Measurements were also made of the development time for the flow patterns and the critical Rayleigh number.
TL;DR: In this paper, an analytic proof of Young's Inequality is presented in the context of the American Mathematical Monthly: Vol 77, No. 6, pp. 603-609.
Abstract: (1970). An Analytic Proof of Young's Inequality. The American Mathematical Monthly: Vol. 77, No. 6, pp. 603-609.
TL;DR: In this article, a new geometric inequality is established and used to extend the refined duality theory for posynomial geometric programs, which is based on abstract properties shared by certain classical inequalities, such as Cauchy's arithmetic geometric mean inequality and Holder's inequality.
TL;DR: A finite difference scheme is developed in which the single governing differential-integral equation is broken up into a system of equations of the heat conduction and Euler types, and a stability theorem is proved.
Abstract: The progress of compression of a water saturated porous medium is derivable from the equation of continuity,Darcy's law, and an appropriate effective stressdilation relationship. Theories of secondary consolidation assume that the effective stress-dilatation relationship is time-dependent. One form of this type of characterization is a system of linear viscoelastic models. The system chosen consists of an elastic element in series with an arbitrary number ofKelvin units. The formulation of this system is a differential-integral equation. The integral portions of the equation are a series of convolution integrals. A finite difference scheme is developed in which the single governing differential-integral equation is broken up into a system of equations of the heat conduction andEuler types. A stability theorem is proved.
TL;DR: In this article, the authors measured the thickness of the layers in the fold noses and the amounts of shortening on the fold limbs of a phyllite with alternating mica-rich and micapoor layers.
TL;DR: Direct applications of mathematical programming techniques in numerical solutions of optimal control problems are reviewed and areas of application include aerospace trajectory optimization and rendezvous problems, computer control of processes, and nuclear reactor control problems.
Abstract: Direct applications of mathematical programming techniques in numerical solutions of optimal control problems are reviewed The types of control systems discussed include linear, nonlinear, continuous- and discrete-time, deterministic, stochastic, and distributed-parameter systems The areas of application include aerospace trajectory optimization and rendezvous problems, computer control of processes, and nuclear reactor control problems A classified bibliography is included
TL;DR: Studies in reserpinized and α-methyl tyrosinized mice suggest that the locomotor effects of amfonelic acid are dependent on the presence of stored and/ or functional norepinephrine and/or dopamine.
TL;DR: In this article, the coupling coefficient of a piezoelectric plate is analyzed for various types of anisotropy, and it is shown that the frequency equation shows that the overtone resonances are not integral multiples of the fundamental.
01 Feb 1970-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: The internal nitridation of thin sections of austenitic Fe−Cr−Ni−Ti alloys containing up to 2 pct Ti was studied over the temperature range 1600° to 2210°F in order to develop a method of strengthening the alloys through the introduction of a dispersoid of stable titanium nitrides as discussed by the authors.
Abstract: The internal nitridation of thin sections of austenitic Fe−Cr−Ni−Ti alloys containing up to 2 pct Ti was studied over the temperature range 1600° to 2210°F in order to develop a method of strengthening the alloys through the introduction of a dispersoid of stable titanium nitrides. The interparticle spacing (IPS) of the nitrides was found to increase linearly with depth from the external surface; the effects of various parameters on the rate of change of IPS vs depth are presented. The mechanical properties of these alloys at room and elevated temperatures were markedly improved by internally nitriding. Useful mechanical properties were obtained up to 2200°F, with typical properties at 2000°F of 10 to 20 ksi 0.2 pct offset yield strength and 15 to 25 ksi ultimate tensile strength, but section thickness was limited to about 10 mils because of the increase in IPS with depth and the long nitriding times needed for thicker material. In order to produce a small interparticle spacing in a heavier section, internally nitrided 5 mil strip was consolidated by hot roll bonding and evaluated at a 60 mil thickness by tensile and rupture testing at 2000°F. It is demonstrated that the approach taken in this work offers a feasible technique for making a high temperature alloy having useful engineering properties.
TL;DR: In this article, the laminar boundary-layer equations are solved asymptotically for simultaneous mass and energy transfer in a variable property binary gas mixture when one component is rapidly transferred toward the surface.
Abstract: The laminar boundary-layer equations are solved asymptotically for simultaneous mass and energy transfer in a variable property binary gas mixture when one component is rapidly transferred toward the surface. Flow is past a surface of arbitrary geometry, and both forced and free convection are studied. Advantage is taken of a mole fraction formulation of the boundary-layer equations, which considerably simplifies the final results. General results are obtained for energy and mass transfer rates when physical properties are arbitrary functions of both temperature and composition. By considering two sets of property variations, representing extremes between which many actual variations lie, it is shown that in many forced convection problems the rates of energy and mass transfer can be expressed in a particularly simple form. The results also show that property variations are generally more important for free convection than for forced convection.