Showing papers by "Indian Institute of Technology Kharagpur published in 1968"

An integral equation formulation of plate bending problems

Abstract: The mathematical theory of thin elastic plates loaded by transverse forces leads to biharmonic boundary value problems. These may be formulated in terms of singular integral equations, which can be solved numerically to a tolerable accuracy for any shape of boundary by digital computer programs. Particular attention is devoted to clamped and simply-supported rectangular plates. Our results indicate support for the generally accepted treatment of such plates and for the intuitive picture of deflection behaviour at a corner.

Note on the stability of a visco-elastic liquid film flowing down an inclined plane

Abstract: An analysis is presented for the stability of a viscoelastic liquid film flowing down an inclined plane with respect to three-dimensional disturbances. It is shown that under certain circumstances, these disturbances are more unstable than the two-dimensional ones, contrary to Squire's theorem.

Dielectric dispersion and its temperature variation in calcite single crystals

Abstract: The variation of dielectric constant and loss of calcite single crystals with frequency and temperature over wide ranges (102 to 2.4×1010c/s and −193 to 450 °C) in two orientations of the crystal, namely, the electric field (i) parallel to the optic axis and (ii) perpendicular to the optic axis, has been studied and the results reported. The dielectric constant at 25 °C in both orientations (E‖, 7.8 andE⊥, 8.2) is frequency-independent. The dielectric loss shows a minimum in the 105 to 108 c/s region. Dielectric constant as a function of temperature exhibits two distinct regions: frequency-independent (−193 to 50 °C) and frequency-dependent (50 to 450 °C). The temperature variation of specific conductivity can be represented by a sum of two exponentials, e.g.,\(\sigma = Ae^{ - E_1 /kT} + Be^{ - E_2 /kT}\) with the usual notation; the constants have different values in the two orientations. The intrinsic conductivity with larger activation energy (E‖ 0.91 eV andE⊥ 1.05 eV) is attributed to the movement of lattice vacancies in the crystal. The 15% larger value for the intrinsic activation energy alongE⊥ optic axis over the other orientation may be due to a probably large electrostatic interaction between the charge carriers and the lattice ions in this orientation.

Inertia effects in hydromagnetic lubrication

Abstract: A theoretical investigation of inertia effects in a squeeze film bearing with an electrically conducting lubricant in the presence of a uniform transverse magnetic field is presented. The two cases of infinitely long rectangular plates and circular plates as bearing surfaces are considered. It is shown that the load supporting capacity of the bearing increases and the squeeze decreases if the lubricant inertia effects are taken into account. However, the inertia effect becomes smaller when the strength of the magnetic field increases.

Upright folding of varying intensity on isoclinal folds of diverse orientation: A study from the early Precambrians of Western India

Abstract: In the Early Precambrian Banded Gneissic Complex between Amet and Lawa Sardargarh in central Rajasthan, India, open to isoclinal upright folds with NNE-striking axial planes have affected westerly plunging isoclinal folds of reclined, inclined and rare upright attitudes. Interference patterns of diverse shapes ranging in scale from inches to miles have been caused by variable angle between the axes and axial planes of the early folds, angular variation in the attitudes of the two fold systems, and spatial variation in the tightness of the later folding.

Effect of lubricant inertia in bearings with a non-Newtonian lubricant

Abstract: The inertia effects in externally pressurized and squeeze film bearings with lubricants obeying a power law are considered. It is found that the inertia forces decrease the load capacity of the externally pressurized bearing with a given flow rate and the inertia effect increases with the flow behaviour index. At a given feeding pressure, on the other hand, the inertia increases or decreases the load capacity when the flow behaviour index is smaller than or greater than 3, respectively. For squeeze films between circular plates and rectangular plates, the rate of squeeze is slowed down by the inertia and the inertia effect is larger in dilatant lubricants than in pseudoplastic lubricants.

Multiple Scattering of High-Energy Electrons from Beryllium

Abstract: The multiple-scattering distribution function for high-energy electrons scattered from a beryllium foil has been calculated, following a method discussed in an earlier paper. Calculations were done with Thomas-Fermi as well as Hartree-Fock potentials for the beryllium atom. The results obtained with the Hartree-Fock potential were found to be in better agreement with the experimental results.

Twin-T feedback filters†

Abstract: Amplifiers with a single twin-T in the feeback path are analysed using root locus methods. A design approach has been suggested for realizing high-Q transistorised active filters resulting in a three-transistor configuration with a stable Q of 200. The behaviour of parallel and cascade configurations of two twin-Ts are studied with a view to realizing stagger tuned band-pass characteristics. It is found that frequencies of selection of the system are much different from the null frequencies of the two twin-Ts. This behaviour is explained using root locus techniques. The difference frequencies for various separations and loop gains have been tabulated. Finally it is concluded that stagger tuning can be realized only by connecting separate high-Q filters in cascade.

Kinetics of polymerization of benzyl acrylate in bulk

Abstract: The kinetics of polymerization of benzyl acrylate has been studied at 55, 60, and 65°C with azobisisobutyronitrile as initiator. The overall rate of polymerization, degree of polymerization, chain transfer due to monomer, and the ratio of propagation and termination constant were calculated. The overall activation energy, the difference between the activation energy of propagation and termination, and the frequency factor are also reported. Die Reaktionskinetik der Polymerisation von Benzylacrylat bei 55, 60 und 65°C mit Azoisobuttersauredinitril als Initiator wurde untersucht. Die Bruttopolymerisationsgeschwindigkeit, der Polymerisationsgrad, die Kettenubertragung durch das Monomere, das Verhaltnis der Geschwindigkeitskonstanten fu Wachstum und Abbruch wurden berechnet. Die Bruttoaktivierungsenergie, die Differenz der Aktivierungsenergien fur die Wachstums- und Abbruchsreaktion und der Frequenzfaktor wurden ebenfalls bestimmt.

Investigations on Waveguide-fed Slot Antenna: Equivalent Network Representation

Abstract: The paper presents investigations on equivalent network representation of displaced narrow longitudinal slot as the length of the slot is varied over the range 0·44–1·5 λ. It is shown that the scattering coefficients (symmetrical, antisymmetrical and unsymmetrical) as also the discontinuities in terminal voltages and currents corresponding to the equivalent network depend upon the nature of the field distribution (odd, even or general) in the slot. The equivalent network is realizable in the form of a T or a π. The T and π-networks may be approximated by shunt and series elements respectively. From the elements of the T and π-equivalent networks, the important parameters such as scattering coefficients and scattering metrix and hence the effect of the slot on the wave propagating down the waveguide have been found. Further, a knowledge of the above parameters provides information regarding the change in the nature of field distribution in the slot with change in its length.

Magnetohydrodynamic flow through a rectangular duct due to a periodic pressure gradient-II

Abstract: The flow of an incompressible, viscous, electrically conducting fluid in a long channel of rectangular cross section due to a periodic pressure gradient, in the presence of a uniform transverse magnetic field is investigated. Exact solutions are obtained and asymptotic forms valid for large Hartmann numbers are discussed.

Oblique regular reflection of a plane shock in presence of a transverse magnetic field

Abstract: In this paper the problem of oblique reflection of a plane incident shock from a rigid wall has been considered in conducting gases. The magnetic field is taken in the direction normal to the plane of flow. The properties behind the reflected shock at the point where the curvature first begins have been discussed. We assume that a first order allowable discontinuity exists at this point. Under this assumption the difference in gradients of different quantities at the point across the slip stream through the point have been obtained. Some other properties at this point have also been discussed. The phenomenon is assumed to be pseudostationary. The effect of magnetic field is also discussed. In der Arbeit wird die Bewegung eines leitenden Gases untersucht, die bei der schragen Reflexion einer ebenen Stoswelle an einer starren Wand auftritt; das Magnetfeld steht dabei senkrecht auf der Ebene der Stosfront. Es wird das Verhalten in dem Punkt des reflektierten Stoses untersucht, in dem die Krummung einsetzt. Vorausgesetzt wird, daβ in diesem Punkt eine zulassige Unstetigkeit erster Ordnung besteht. Unter dieser Voraussetzung wird der Sprung im Gradienten verschiedener Groβen berechnet, der im fraglichen Punkt quer zum Nebenstrom (slip stream) auftritt. Einige andere Effekte, die sich in diesem Punkt ergeben, werden auch diskutiert. Der Vorgang wird als pseudostationar angesehen. Die Wirkung des Magnetfeldes wird gleichfalls untersucht.

Some results for an r.f.- and p.l.-modulated incoherent carrier

Abstract: Possibilities of using incoherent carriers, amplitude-modulated by the message-modulated p.f.m., r.f.m. and p.l.m. have been investigated. It has been shown that, for noise bandwidths much smaller than the transmission bandwidth, efficient communication is possible, and s.n.r.s of 50?60dB are obtained for practical p.f.m.-a.m. and r.f.m.-a.m. systems. Some comparisons are also given.

Kinetics of accelerated vulcanization. Sulfur vulcanization accelerated with 2‐mercaptobenzothiazole and its zinc salt in presence of zinc oxide and zinc oxide and stearic acid

Abstract: Sulfur vulcanization of natural rubber (NR) and styrene-butadiene rubber (SBR) accelerated with 2-mercaptobenzothiazole and zinc oxide with or without stearic acid has been studied and the results compared with those obtained by replacing the thiazole with its zinc salt The order of the rate of vulcanization as measured from free sulfur decrease or crosslink formation is observed to be unity with respect to time and less than one with respect to accelerator concentration In absence of stearic acid, the zinc salt is much less efficient than the thiazole in promoting vulcanization, and the efficiency of the latter shows a noticeable improvement over what is attained in absence of zinc oxide Addition of stearic acid not only raises the efficiency of both the systems to the same level but also leads to a faster rate of vulcanization, a much higher degree of crosslinking, avoidance of reversion, and production of vulcanizates with considerably improved mechanical properties The formation of zinc sulfide also reveals interesting variation Attempts have been made to interprete these results in terms of complex formation between zinc salt of thiazole and zinc stearate Die mit 2-Mercaptobenzthiazol und Zinkoxid mit und ohne Stearinsare beschleunigte Vulkanisation von Naturkautschuk und Styrol-Butadienkautschuk wurde untersucht; die Ergebnisse wurden mit den Untersuchungen verglichen, in denen anstelle des Thiazols dessen Zinksalz verwendet wurde Fur die Geschwindigkeit der Vulkanisation, die aus der Abnahme an freiem Schwefel oder aus der Vernetzung bestimmt wurde, ergab sich eine Reaktionsordnug von 1, wahrend in Bezug auf die Beschleunigerkonzentration eine Ordnung kleiner 1 gefunden wurde Ohne Zusatz von Stearinsaure ist das Zinksalz wesentlich weniger wirksam fur die Beschleunigung der Vulkanisation als das Thiazol und das Thiazol merklich wirksamer mit Zinkoxid als ohne Der Zusatz von Stearinsiiure hebt nicht nur die Wirksamkeit beider Systeme auf das gleiche Niveau, sondern bewirkt auch eine Erhohung der Vulkanisationsgeschwindigkeit und des Vernetzungsgrades sowie die Vermeidung einer Reversion und fuhrt zu erheblich verbesserten mechanischen Eigenschaften des Vulkanisats Es wurde versucht, die Ergebnisse uber die Annahme einer Komplexbildung zwischen dem Zinksalz des Thiazols und Zinkstearat zu deuten

A general method of solving the field equations inside ferromagnetic sheets subjected to alternating magnetization

Abstract: The paper deals with the problem of the internal distribution of eddy current and magnetic flux and the waveforms of these quantities in ferromagnetic laminations under application of an alternating field and with particular surface conditions. The problem discussed is inherently intractable on account of its nonlinear character, and many attempts have been made at an approximate solution. Such solutions, however, have failed to bring out the importance of the surface conditions of magnetization-a factor of considerable significance in thin laminations. The present mode of attack is based on the assumption that, apart from the fundamental, the third harmonic components of the alternating quantities are also significant. The solution of the non-linear equation based on this assumption brings out several features of the complex phenomena which occur and the comparison given between theoretical and experimental results go far to justify the method of solution and the assumption made. The method has the advantage of lending itself to digital computation.

Solitary waves in a two-fluid system in a channel of arbitrary cross section

Abstract: The problem of solitary wave at the interface of two immiscible ideal fluids in a channel of arbitrary cross section and infinite length is investigated, and expressions for wave profile and speed are obtained. It is shown that when the two fluids are of nearly equal density, then the wave is of elevation (or depression) when the lower (or upper) layer is shallower of the two. The particular case of a rectangular channel is discussed in detail, and the results correspond to those of Long [1956] and Benjamin [1966]. DOI: 10.1111/j.2153-3490.1968.tb00408.x

Simultaneous extension, inflation, and shear of a cylindrical tube

Abstract: Rivlin's solution [1] of the title problem for Mooney materials is generalized by dropping the assumption that the hydrostatic pressure is a function of the radial distance only. Due to this generalization the normal tractions over the cylindrical surfaces are not constant as in the previous solution but vary linearly along the axis of the tube. Further, the longitudinal forces per unit length of the deformed tube, over the cylindrical surfaces, are no longer equal. Solutions for a solid cylinder are then deduced from the general solution. The effect of self-weight on the solutions is briefly dealt with.

Effect of velocity-dependent nuclear forces on (γ, p) disintegration of the alpha particle

Abstract: We calculate the total cross section ?(?, p) for the two-particle photodisintegration of the alpha particle. We describe the ground states of the alpha particle and the triton by modified Irving wave functions, the parameters of which have been determined from variational calculations of the binding energies of these systems, using a central velocity-dependent potential. We neglect the final-state interaction. We compare our results with the recent experiments of Gorbunov and with other similar calculations of Gunn and Irving and Bransden et al. We find that, though the velocity-dependent forces cause the total cross section ?(?, p) to change in the right direction, the discrepancy of fitting simultaneously the binding energy, r.m.s. radius and the maximum cross section at the correct energy is not removed altogether.

Bending of a partially clamped rectangular plate

Abstract: The present study deals with the bending of a rectangular plate with two opposite simply-supported edges and other two free edges having any portion, clamped in such a way that the slope is zero. The solution is obtained by means of a superposition proposed by Kurata and Hatano [3]. The case of a square plate under a uniform load or a point load has been studied in detail.

Autoradiographic studies on collagen in plant nuclei

Abstract: Mit Hilfe von radioaktiv markiertem Prolin wird autoradiographisch das Vorkommen von Collagen im Matrixeiweiss pflanzlicher Zellkerne festgestellt.