Showing papers by "Indian Institute of Technology Bombay published in 1972"
39 citations
TL;DR: In this article, it was shown that the open-circuit adsorption of formaldehyde from moderately concentrated solution is accompanied by hydrogenation of the organic molecule and that the anodic oxidation of chemisorbed formaldehyde has been determined and are shown to be analogous to those for chemisored methanol, formic acid, and reduced carbon dioxide.
18 citations
TL;DR: This note presents a straightforward method for system reliability evaluation where probability is treated as a point in a Cartesian frame and formulas are derived to evaluate the reliability of series, parallel, series-parallel, and bridge networks.
Abstract: The evaluation of system reliability becomes very diffilcult when the number of components in a system is large or the system configuration is complex. This note presents a straightforward method for system reliability evaluation. Probability is treated as a point in a Cartesian frame and formulas are derived to evaluate the reliability of series, parallel, series-parallel, and bridge networks. The values obtained by the classical method agree closely with those obtained by this parametric method.
18 citations
TL;DR: In this article, self-similar solutions for one dimensional unsteady flow of a perfect gas driven out by an expanding piston are investigated, where the shock ahead of the piston is assumed to be strong and propagating into a medium at rest with non-uniform density.
15 citations
TL;DR: In this article, an easy alternative proof for the upper bound relation (∂ 2 E /∂λ 2 )aψ|ψ« ⩽ aψ |∆ 2 H /∆λ 2 |ψ « is provided.
15 citations
TL;DR: In this article, self-similar solutions for isothermal flows driven by an expanding piston are investigated, where the total energy of the flow between the shock and the piston is taken to be dependent on the shock radius obeying power law.
11 citations
TL;DR: In this paper, the effect of temperature on the anodic oxidation of chemisorbed methanol and formaldehyde layers on platinized platinum has been studied in 0.5 M H2SO4 and 0.1 M HCl+0.45 M HSO4.
10 citations
TL;DR: In this paper, a transfer admittance function between the line current and the line voltage of an induction machine with star- or delta-connected stator windings is defined, which can be used to predetermine the performance of induction machine supplied with balanced nonsinusoidal voltages without obtaining the harmonic components of the supply voltage waveform as in classical approach.
Abstract: An equivalent circuit of an induction machine in complex frequency domain is presented. This can be used to predetermine the performance of induction machine supplied with balanced nonsinusoidal voltages without obtaining the harmonic components of the supply voltage waveform as in classical approach. Moreover, a transfer admittance function has been defined between the line current and the line voltage of an induction machine with star- or delta-connected stator windings. The speed of the machine has been assumed to be constant to ``linearize'' the system. The admittance function has been used to obtain the waveform of stator line current for a given line voltage waveform using fast Fourier transforms. The waveforms obtained using this method have been compared with the waveforms obtained in experimental investigations reported earlier. The two are in excellent agreement.
7 citations
6 citations
TL;DR: In this paper, a novel electrochemical cell is described and HCHO is identified as a product of the destructive adsorption of ethanol on platinum, and a mechanism is proposed for the formation of formaldehyde invoking electron shift during the dehydrogenation of the fragment CH 2 OH.
6 citations
TL;DR: In this paper, the eigenfunction expansion method is suggested for the bending of a clamped skew plate under uniform loading and still it continues to attract the attention of investigators, however, the results are very approximate.
Abstract: Introduction I recent years a number of authors have analyzed the bending of a clamped skew plate under uniform loading and still it continues to attract the attention of investigators. Many of the solutions are very approximate. Based on generalized method postulated by Lardy, Mirsky presented the solution which involves considerable algebraic and numerical work. Otta and Hamada presented the solution for a clamped rhombic plate using strain energy method. Warren used a point matching method satisfying the symmetry conditions along the diagonal "exactly" at N discrete points. Morley derived the solution by reducing the problem to the single membrane boundary value problem. Kennedy used a simple polynomial form having polar symmetry with a set of three undetermined parameters. He used Galerkin's technique to evaluate those parameters, lyengar and Srinivas used a double infinite series of beam functions satisfying the boundary conditions. The unknown constants were determined by satisfying the governing equation. Although the governing fourth-order differential equation remains the same for a skew plate and a rectangular plate, the solution for the skew plate becomes much more complicated due to its geometry (Fig. 1). The mathematical model of the problem is relatively difficult and explicit solutions are uncommon. In this Note, the eigenfunction expansion method is suggested for the problem. The method owes its originality to Gaydon and Shephard. The effectiveness of the method over other methods is also indicated.
TL;DR: In this paper, the authors derived the voltage and current equations for the commutation period of the main and auxiliary SCRs, and the circuit turn-off time was computed as a function of x, where x is the ratio of the maximum load current to be commutated to the peak discharge current of the commutating capacitor.
Abstract: Commutating capacitor voltage and current equations are derived for the commutation period of the main and auxiliary SCRs. The circuit turn-off time is computed as a function of x, where x is the ratio of the maximum load current to be commutated to the peak discharge current of the commutating capacitor. A suitable choice of x is suggested. In addition to the worst case design for L1, L2, and C, a nomograph for the selection of L1, L2, and C is given as a function of x.
TL;DR: In this article, a systematic study on the cation exchange behavior of nickel and zinc on Dowex 50W-X16 was presented, where various eluting agents were evaluated in terms of elution constant and volume distribution coefficient.
Abstract: Systematic studies are presented on cation exchange behaviour of nickel and zinc on Dowex 50W-X16. Hydrocnloric, nitric, sulphuric, perchloric acids and ammonium chloride, sulphate and acetate and sodium chloride and nitrate were tested as eluting agents. Their efficiency was evaluated in terms of elution constant and volume distribution coefficient. Nickel and zinc can be separated from a large variety of other elements by process of selective elution, or selective sorption. It is possible to separate nickel or zinc from many common ions such as copper (II), iron (III), bismuth (III), manganese (II), lead (II), cadmium etc. associated with them in alloys. Also methods are developed for their separation from Thorium (IV), Uranium (VI), Zirconium (IV), Cerium (IV), Silver, Barium etc. in fission product analysis. The overall operation requires about three hours. The results are reproducible to ¯1.5%.
01 Oct 1972
TL;DR: Nickel can be quantitatively extracted with 0.001 M thiothenoyltrifluoro-acetone in carbon tetrachloride at pH 6.5 as mentioned in this paper.
Abstract: Nickel can be quantitatively extracted with 0.001 M thiothenoyltrifluoro-acetone in carbon tetrachloride at pH 6.5. The yellow-orange colored complex is measured spectrophotometrically at 480 nm. The system conforms to Beer's law in the concentration range of 0.5–5 μg/ml of nickel. The complex is stable for 96 hr. Nickel can be separated from several cations and anions.
TL;DR: In this paper, the concept of phase plane analysis is extended to a class of third-order non-linear systems, having a thirdorder linear memory system and a single-valued zero-memory system in cascade combination in the forward path.
Abstract: In this paper the concept of phase plane analysis, which is well developed for second-order systems, is extended to a class of third-order non-linear systems. The method of analysis presented is applicable to the unity feedback closed-loop systems, having a third-order linear memory system and a single-valued zero-memory system in cascade combination in the forward path. The technique involves plotting a (x2, x3) master plane having all possible trajectories for x1 = 0. The variation and the initial condition of variable x1 are incorporated by adding an origin shift scale on to the master plane. Using this master plane, the required (x1, x2) and (x1, x3) trajectories can be obtained for any set of initial conditions, following a simple procedure illustrated by typical examples. This technique is also applicable for the analysis of such systems for step inputs.
Journal Article•
TL;DR: In the course of study of the Precambrian sedimentary iron ore deposits of Noamundi in Singhbhum district of Bihar and of Goa, extensive occurrences of powdery iron ores known as Blue Dust have been observed and examined.
Abstract: In the course of study of the Precambrian sedimentary iron ore deposits of Noamundi in Singhbhum district of Bihar and of Goa, extensive occurrences of powdery iron ores known as Blue Dust have been observed and examined. Field features like the nature of occurrence, textural, structural, and mineralogical character of the Blue Dust have been observed in detail. Shape and size analysis of the mineral grains of the powdery ore have been made and their chemical, X-ray and DTA data presented to explain the mineralogy and chemistry. Etch tests and dissolution experiments have been carried out on standard ore pieces at different pH and temperature for different lengths of time to produce material equivalent to the powdery iron ore. From the above data and experiments, and with the theory of anisotropic dissolution of hematite, the mechanism of formation of the Blue Dust has been explained.
TL;DR: In this paper, the problems of current sensing and line-to-line short circuit protection are discussed in greater detail, and the principle of three-phase low frequency waveform generation and the sinusoidal modulation technique are analysed.
Abstract: The papers published so far on modern cycloconvertors hardly give any details of the control circuitry. In this paper, the various requirements of the control circuitry are discussed and the schematic arrangements are given. The problems of current sensing and line to line short circuit protection are discussed in greater detail. The principle of three-phase low frequency waveform generation and the sinusoidal modulation technique are analysed. Finally, the performance of the cycloconvertor system so designed is illustrated with oscillograms.
TL;DR: In this article, the authors considered the expansion of the biharmonic deflection function in a series of non-orthogonal functions satisfying the condition of clamped edges and obtained numerical results for the deflection of the central line when the semi-sector angle is 15 degrees.
Abstract: The paper involves the expansion of the biharmonic deflection function in a series of non-orthogonal functions satisfying the condition of clamped edges. Each of these non-orthogonal functions is expanded in a series of orthogonal functions which satisfy a certain fourth order differential equation and the boundary conditions implied by the fact that the edges are clamped. This reduces the bending of a uniformly loaded clamped sector plate to the solution of a linear algebraic system of equations. Numerical results for the deflection of the central line are obtained when the semi-sector angle is 15 degrees.
TL;DR: It is shown that the nth-order linear system is completely identified by a polynomial input of degree 2n, and the scheme suggested here uses any arbitrary stable differential equation set-up on the analogue computer.
Abstract: The problem of evaluation of the coefficients of the transfer function of a system, usually referred to as the parameter estimation problem, assumes the main importance in any general adaptive control system. If the input to the system is a polynomial in t, then the steady-state response of a linear system is also a polynomial in t. It is shown that the nth-order linear system is completely identified by a polynomial input of degree 2n. The algebraic formulation given for evaluation of the system parameters needs the measurement of the derivatives of the input and output under the steady state. The scheme suggested here uses any arbitrary stable differential equation set-up on the analogue computer. The derivatives of the input and output are then computed by using a matrix transformation and are used in the given formulation to evaluate the system parameters. The use of the scheme is illustrated for tracking of time-varying parameters of a linear system.
TL;DR: In this paper, a Lee-like non-polynomial Lagrangian is discussed and it is shown that the model has no ghosts, but does not satisfy the theorem of Lehmann, Symanzik and Zimmermann.
TL;DR: In this paper, a large signal analysis of frequency multiplication using non-linear capacitance has been made, where the only restriction imposed is the requirement of ideal filters at the input and output.
Abstract: A large signal analysis of frequency multiplication using non-linear capacitance has been made. No restriction on the non-linearity of the dynamic capacitance has been imposed. The amplitude of the nth harmonic voltage has been taken into consideration. Hence a general large signal formula for the optimized efficiency has been derived. The only restriction imposed is the requirement of ideal filters at the input and output establishing the existence of only the fundamental and the required harmonic voltage across the non-linear capacitance. To relate to practical cases of varactor diodes, computation of Fourier generator component of charge coefficients of abrupt and graded junction varactor diodes has been made. Since only the non-linear capacitance mode of harmonic generation is postulated, for numerical calculation the total composite a.c. voltage consisting of the fundamental and the nth harmonic voltage has been assumed to be 90% of the total d.c. voltage inclusive of the applied bias and th...
TL;DR: In this article, the authors report the second phase of their program to indigenously develop hybrid integrated circuits based on tantalum thin films, which are increasingly incorporated in recent versions of communication and radar equipment.
Abstract: This paper reports the second phase of our programme to indigenously develop hybrid integrated circuits based on tantalum thin films. (Report on the first phase, viz. development of resistors, has appeared in the September 1971 issue.) These IC's provide quality performance for linear applications right from audio/radio to microwave frequencies and are increasingly incorporated in recent versions of communication and radar equipment.A tantalum film capacitor is fabricated by anodizing the upper portion of the film to serve as a dielectric, the lower portion serving as a bottom electrode. Gold layer deposited on the dielectric constitutes the top electrode. The presence of pinholes, however, does not permit one to adopt such a simple approach. The problem has been successfully solved by adopting ‘a double layer approach’. It consists in once again depositing tantalum on the anodized film and anodizing it completely. Since the probability of pinholes in the two layers coinciding is very rare, this approach ...