On dynamic behavior of stochastic systems with discontinuities in parameters

In this paper an analysis and stochastic characterization of optimally controlled systems in the presence of environmental disturbances, additive input and observation noise, and subject to discontinuous-type parameter uncertainties is considered. As an illustrative example, the control of a spinning spacecraft is considered and some quantitative aspects of the stochastic behavior of the control and estimation signals following discontinuities in the controlled spacecraft parameters are discussed.     

A Branch-and-Bound Procedure to Solve a Bicriterion Scheduling Problem

Most scheduling research is done with one criterion; however, the real-world situations demand consideration of multicriterion problems because there are generally many costs associated with scheduling decisions. This paper considers the problem of minimizing a linear combination of flow times and max-mum tardiness of a given number of jobs on a single machine and presents a branch-and-bound technique to arrive at an optimal solution. The computational results are also reported.     

Potential drops inside MHD generators

This paper presents a theoretical evaluation of the potential drops in various regions taking account of ambipolar diffusion. Temperature dependence of mobility and thermal conductivity have also been taken into account. An expression has been derived for the temperature distribution near the electrodes. Theoretical values of the potential drops have been compared with the experiments and they are found to be in reasonably good agreement. Breakdown potentials have also been calculated and compared with the experiments. It is concluded that inclusion of ambipolar diffusion is essential in the theoretical calculations for the potential drops in MHD generators.     

Confined laminar jet mixing in a circular channel with arbitrary entrance velocity distribution

Summary This paper is concerned with the problem of confined laminar jet-mixing in a circular channel. The Navier-Stokes equations are linearized patterned after an approach proposed bySparrow, Lin, andLundgren in their study of laminar flow development in a channel. After linearization, the governing equation becomes an integro-differential equation. The exact solution is found for the case of two uniform streams each occupying half of a circular channel. Additionally a variational formulation of the same problem is established, completely equivalent to the differential formulation. This variational formulation is constructed based upon the use of convolutions. Approximate variational solutions are obtained. It develops that a simple two-term approximation gives excellent agreement with the exact solution.

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Abgeschlossene laminare Strahlmischung in einem Kreisrohr bei beliebiger Verteilung der Eintrittsgeschwindigkeit

Zusammenfassung Für das im Titel genannte Problem werden die Navier-Stokes-Gleichungen nach einer vonSparrow, Lin, undLundgren vorgeschlagenen Methode linearisiert, wodurch die Grundgleichungen Integral-Differentialgleichungen werden. Für den Fall zweier gleichförmiger Strahlen, von denen jeder eine Hälfte des Kreisrohres einnimmt, wird eine exakte Lösung gefunden. Weiters wird eine Variations-Formulierung desselben Problems angegeben, die der Differential-Formulierung vollkommen äquivalent ist. Näherungslösungen dieser Variationsmethode werden erhalten, und es zeigt sich, daß eine einfache zweigliedrige Näherung ausgezeichnete Übereinstimmung mit der exakten Lösung zeigt.

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With 5 Figures     

The three-dimensional isoparametric element in curvilinear coordinates

The formulation of the stiffness matrix of an isoparametric element in curvilinear coordinates is presented. The use of curvilinear coordinates eliminates the necessity of introducing intermediate nodes for conforming to curved boundaries. The application of the method to cylindrical coordinates is illustrated by comparing the results for a cylindrical pressure vessel from this formulation with those obtained from the existing solutions.     

Effect of Receiver Bandwidth on Waveforms and Time Characteristics of Atmospheric Radio Noise Bursts

Several investigators have presented the results of their experimental investigations and theoretical expectations on the effect of receiver bandwidth on the time characteristics and waveforms of atmospheric radio noise bursts. The experimental and theoretical findings do not appear to agree with each other. This communication offers a possible explanation for this "discrepancy" with support from experimental evidence, drawn from a large number of references included in this communication.     

The component fatty acids of chaulmoogra oil

The fatty acid composition of the seed oils of the species, Hydnocarpus kurzii, H. wightiana and H. odorata were determined by gas-liquid chromatographic (g.l.c.) analysis. The percentages of individual fatty acids were found to be: hydnocarpic 23.0, 33.9, -; chaulmoogric 29.6, 35.0, -; gorlic 25.1, 12.8, -; lower cyclic homologues 0.3, 4.6, -; myristic 0.6, 0.8, 0.4; palmitic 8.4, 5.6, 11.8; stearic -, 0.6, 4.7; palmitoleic 6.0, 1.3, 0.5; oleic 5.4, 3.6, 21.8; linoleic 1.6, 1.8, 29.3; linolenic -, -, 31.2; respectively.     

Solution of eigenvalue problems by sturm sequence method

A generalized eigenvalue algorithm is presented herein along with the complete listing of the associated computer program, which may be conveniently utilized for the efficient solution of certain broad classes of eigenvalue problems. Extensive applications of the procedure are envisaged in the analysis of many important engineering problems, such as stability and natural frequency analysis of practical discrete structural systems, idealized by the finite element technique. The procedure based on the Sturm sequence method is accurate and fast, possessing several significant advantages over other known methods of such analysis. Numerical results are also presented for two representative structural engineering problems.     

Thermoluminescence and triboluminescence in trioxane crystals

Polymerised trioxane crystals, irradiated at liquid nitrogen temperature show a single thermoluminescence peak on warming. Corresponding trioxane monomer crystals show a thermoluminescence spectrum of five peaks, and a series of sharp spikes at irregular intervals. On warming an unirradiated crystal, a two-peak spectrum plus spikes is obtained. The spikes are associated with strong electrical discharges and tentatively ascribed to dislocation of crystals under thermal stress.