Showing papers by "Indian Institute of Technology Bombay published in 1992"
19 May 1992
TL;DR: This contribution addresses the problem of detection and tracking of moving vehicles in image sequences from traffic scenes recorded by a stationary camera by using a parameterized vehicle model and a recursive estimator based on a motion model for motion estimation.
Abstract: This contribution addresses the problem of detection and tracking of moving vehicles in image sequences from traffic scenes recorded by a stationary camera. In order to exploit the a priori knowledge about the shape and the physical motion of vehicles in traffic scenes, a parameterized vehicle model is used for an intraframe matching process and a recursive estimator based on a motion model is used for motion estimation. The initial guess about the position and orientation for the models are computed with the help of a clustering approach of moving image features. Shadow edges of the models are taken into account in the matching process. This enables tracking of vehicles under complex illumination conditions and within a small effective field of view. Results on real world traffic scenes are presented and open problems are outlined.
135 citations
TL;DR: Fluorescence studies indicate the involvement of a premolten globule state in the native to molten globules state transition, which exists at pH 5.0 and has a very compact structure involving increased hydrophobic interactions in the protein interior.
74 citations
TL;DR: These methods resemble the well-known family of damped Newton and Gauss-Newton methods for solving systems of smooth equations and generalize some recent Newton-like methods for solve B-differentiable equations which arise from various mathematical programs.
Abstract: This paper presents some globally convergent descent methods for solving systems of nonlinear equations defined by locally Lipschitzian functions. These methods resemble the well-known family of damped Newton and Gauss-Newton methods for solving systems of smooth equations; they generalize some recent Newton-like methods for solving B-differentiable equations which arise from various mathematical programs.
72 citations
TL;DR: By generating external events symbolically, Statecharts can be executed, thereby turning it into a programming language for real-time concurrency (as well as enabling rapid prototyping) and well suited for compositional program verification.
60 citations
TL;DR: In this article, the effect of boat temperature and substrate temperature on the structural and electrical properties of transparent and conducting films of cadmium oxide on glass substrates by the activated reactive evaporation (ARE) technique was reported.
47 citations
TL;DR: It is concluded that Ce2Ni3Si5 is a Ce-based valence-fluctuation compound that is nearly temperature independent above 120 K unlike that of a normal metallic material.
Abstract: The results of electrical resistivity (4.2--300 K), magnetic susceptibility (5--300 K) and specific heat (2--20 K) are reported on the ternary orthorhombic rare-earth compound ${\mathrm{Ce}}_{2}$${\mathrm{Ni}}_{3}$${\mathrm{Si}}_{5}$. The resistivity of the material is nearly temperature independent above 120 K unlike that of a normal metallic material. The magnetic contribution to resistivity shows a broad maximum around 200 K. At low temperatures, the resistivity follows a ${\mathit{T}}^{2}$ behavior in the temperature range 4--13 K. The inverse magnetic susceptibility deviates from Curie-Weiss behavior below 80 K where it exhibits a broad maximum in the \ensuremath{\chi} vs T curve. Specific heat measurements (2--20 K) give a value of \ensuremath{\gamma}\ensuremath{\approxeq}62 mJ/Ce mol ${\mathrm{K}}^{2}$ which is similar in magnitude to those encountered in valence-fluctuating systems. From these observations we conclude that ${\mathrm{Ce}}_{2}$${\mathrm{Ni}}_{3}$${\mathrm{Si}}_{5}$ is a Ce-based valence-fluctuation compound.
45 citations
TL;DR: In situ measurements of mass concentration of size-distributed aerosols were made using a quartz crystal microbalance cascade impactor as mentioned in this paper, where the number concentrations were calculated for different sizes and these were subjected to factor analysis which gave four factors representing various sources of particulates.
44 citations
TL;DR: In this article, the response of thin-film SnO 2 gas sensors is studied for various operating temperatures and reducing gas ambients, and it is observed that the response follows a power-law relationship with the exponent value always remaining less than one at higher concentrations of reducing gas.
Abstract: Thin-film SnO 2 gas sensors are fabricated using an electron-beam evaporation method at pre-optimized substrate temperatures and post-deposition heat-treatment temperature. The response of these sensors is studied for various operating temperatures and reducing gas ambients. Reducing gases used for testing the response are hydrogen, carbon monoxide and methane, as they belong to three distinct chemical families. It is observed that the response of these sensors follows a power-law relationship, with the exponent value always remaining less than one at higher concentrations of reducing gas. Films deposited at 25 and 350 °C and heat treated at 650 °C in O 2 ambient for 2 h are found to be more suitable for sensor application compared to films deposited at intermediate temperatures and heat treated under identical conditions. Further, the response of the sensor is found to deteriorate with a decrease in operating temperature. It is also concluded from the results that a thin-film SnO 2 sensor can be used as a selective sensor for H 2 at either low operating temperature or under very low background concentrations of other reducing gases. Finally, the above-mentioned results are explained using existing physical models.
42 citations
TL;DR: Magnetic oxides, a major constituent of magnetic ceramic materials, are most extensively used in a variety of applications as soft, moderate and hard ferrites as mentioned in this paper, with special emphasis on some recent developments in magnetic recording materials.
Abstract: Magnetic oxides, a major constituent of magnetic ceramic materials, are most extensively used in a variety of applications as soft, moderate and hard ferrites. I review here its applications with special emphasis on some recent developments in magnetic recording materials.
39 citations
TL;DR: In this paper, a CADDS for sheet-metal blanks is described, which is implemented by interfacing AutoCAD with the higher level languages FORTRAN 77 and AutoLISP.
Abstract: This article reports on the design and implementation of a Computer-Aided Die Design System (CADDS) for sheet-metal blanks. The system is designed by considering several factors, such as the complexity of blank geometry, reduction in scrap material, production requirements, availability of press equipment and standard parts, punch profile complexity, and tool elements manufacturing method. The interaction among these parameters and how they affect designers' decision patterns is described. The system is implemented by interfacing AutoCAD with the higher level languages FORTRAN 77 and AutoLISP. A database of standard die elements is created by parametric programming, which is an enhanced feature of AutoCAD. The greatest advantage achieved by the system is the rapid generation of the most efficient strip and die layouts, including information about the tool configuration.
38 citations
TL;DR: In this article, the authors examined the effect of a shear flow on the polymerization reaction between p-phenylene diamine and terephthaloyl chloride, where the product has a rigid, rod-like structure, and they found that once the molecular weight of the reactants exceeds a critical value, shearing of the reaction mixture induces a pronounced orientation of the molecules, accompanied by a significant increase in polymerization rate.
Abstract: RIGID, rod-like polymers are of considerable technological importance in the production of high-strength and high-modulus fibres1. Polymerization reactions generally require near-parallel orientation of such molecules, and because of the slow rotational diffusion of the reacting species2, the rate of polymerization is found to decrease significantly in the later stages of the reaction; this ultimately limits the molecular weight of the polymer. It is known, however, that rod-like molecules can be readily oriented in solution by means of imposed flow fields. Here we examine the effect of a shear flow on the polymerization reaction between p-phenylene diamine and terephthaloyl chloride, where the product, poly(p-phenylene terephthalamide), has a rigid, rod-like structure1. We find that once the molecular weight of the reactants exceeds a critical value, shearing of the reaction mixture induces a pronounced orientation of the molecules, accompanied by a significant increase in the polymerization rate. The technological implications are clear: exposure of polymerizing mixtures of rod-like molecules to high shear rates can result in a dramatic enhancement in the molecular weight of the resulting polymer.
TL;DR: Four water soluble complexes of the type [M(bpy)(a-x)]NO3, where M is Pd(II) or Pt(II), bpy is 2,2-bipyridine, and a-x is anion of 2-pyridinecarboxylic acid, have been found to bind calf thymus DNA, possibly through hydrogen binding.
TL;DR: In this paper, a model reference non-linear controller with PID actions is proposed for temperature control of process fluid in a fluid-fluid heat exchanger, which is an example of a system with a relative order of two.
TL;DR: In this paper, a transient analysis of solar concrete collectors used for providing domestic hot water is presented, which involves the solution of the two-dimensional time-dependent heat conduction equation with appropriate initial and boundary conditions.
TL;DR: In this paper, an effort has been made to develop suitable process conditions for synthesizing carbon molecular sieves (CMSs) from the locally available bituminous coal, where coal was crushed, milled and agglomerated with sulfate pulp waste liquor (SPWL) or coal-tar pitch (CTP) as the binders and then carbonized in nitrogen atmosphere at 800°C for about 60 minutes.
TL;DR: In this article, the problem of incomplete carbon conversion of rice husk was investigated using thermogravimetric experiments with carbon dioxide, nitrogen, air and steam atmospheres under different temperature conditions.
TL;DR: In this article, the flow characteristics of non-Newtonian fluid obeying Casson's stress-strain relation have been investigated in the annular space between two coaxial rotating cylinders, where the inner cylinder is at rest and the outer cylinder rotating with a constant velocity.
TL;DR: Aerosol samples were collected in an industrialized region of Bombay and analyzed for twenty seven chemical species using inductively coupled plasma emission spectroscopy, energy dispersive x-ray fluorescence spectroscope and UV/VIS spectrophotometry as mentioned in this paper.
Abstract: Aerosol samples were collected in an industrialized region of Bombay. These were analyzed for twenty seven chemical species using inductively coupled plasma emission spectroscopy, energy dispersive x‐ray fluorescence spectroscopy and UV/VIS spectrophotometry. Factor analysis applied on nineteen marker elements extracted seven factors indicating seven major source types contributing to aerosol mass at the sampling sites. Multiple regression taking absolute factor scores as predictors was employed for source apportionment. Finally, source profiles were calculated as percentage of the aerosol mass and compared with the values reported in the literature.
26 Nov 1992
TL;DR: The authors suggest that the control part of the micropipeline is concurrently testable during normal operation and that test pattern generation for the data part logic can be reduced to that for combinational circuits, with a simple modification only in the test application method.
Abstract: Micropipelines, suggested by Ivan Sutherland (1989) form an elegant scheme for asynchronous implementation of pipelined circuits. The authors analyse the faulty behavior of micropipelines and propose schemes for testing. They suggest that the control part of the micropipeline is concurrently testable during normal operation and that test pattern generation for the data part logic can be reduced to that for combinational circuits, with a simple modification only in the test application method. Testing latches require a two-pattern test which can be generated using test pattern generation techniques for combinational circuits. >
TL;DR: In this paper, a six noded triangular finite element has been proposed to model variable order singularities in the first derivatives of field variables occurring at multiple locations (up to three) lying in close proximity.
Abstract: A six noded triangular finite element has been proposed to model variable order singularities in the first derivatives of field variables occurring at multiple locations (up to three) lying in close proximity The element satisfies the convergence requirements fully The element will be very useful in the analysis of neighbouring cracks, zig-zag cracks, kinked cracks, etc, involving mechanical and/or thermal loadings The first degenerate form, which is a two point variable order singularity element, can be used, for example, to cover the distance between two adjacent crack tips The second degenerate form, which is a one point variable order singularity element, can be used around a crack tip like any other crack tip elements Six case studies have been reported, three involving mechanical loadings and the other three thermal loadings These have helped to check the performance of the element and its two degenerate forms The accuracy of the results in all the examples is good
01 Jun 1992
TL;DR: In this paper, a 400 mm diameter contra-rotating fan unit was designed and tested to find ways and means of improving their design and performance, and the effect of axial gaps showed that at the design speed combination best performance was observed at an axial gap of 50% of the first fan chord.
Abstract: The design and testing of a 400 mm diameter contra-rotating fan unit was undertaken to study the flow behavior through the contra-rotating fans, and to find ways and means of improving their design and performance. The performance characteristics of the two-fan unit have shown that large overall stall margins can be achieved. Also, the effect of axial gaps showed that at the design speed combination best performance was observed at an axial gap of 50% of the 1st Fan chord.Studies on the 2nd fan exit flow field, performance characteristics of individual fans and casing boundary layer development have been made. Significant performance enhancement is observed with serration on 2nd fan rotor blade surface. When casing boundary layer suction is employed in between the two blades, the 2nd fan exit flow shows better uniformity and increased total pressure at all radii. However, to obtain a large operating range, careful optimization of the 2nd rotor blade design would be required, taking into account peculiarities shown by the present study in variation of deviation and exit flow angles of the individual fans, and casing boundary layer development with increased axial pressure gradient.Copyright © 1992 by ASME
TL;DR: In this paper, the stability of natural circulation with throughflow in a figure-of-eight loop was investigated and good agreement was found between theory and experiment, both experimental and theoretical.
TL;DR: In this article, an element for analysis of variable order one point singularities in plane problems has been proposed, which meets all the convergence requirements, viz. the rigid body mode, the constant strain condition and the interelement compatibility.
Abstract: An element for analysis of variable order one point singularities in plane problems has been proposed. The element meets all the convergence requirements, viz. the rigid body mode, the constant strain condition and the interelement compatibility. It can be easily incorporated in any package based on the displacement formulation. Four examples from fracture mechanics are presented to demonstrate its performance. The examples involve mechanical or thermal loadings. The accuracy of results in all the examples is very good.
30 Jan 1992-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, the effect of boron content on the grain growth behavior of type 316L stainless steel was investigated by annealing for 0.25-100 h at 950°C and by isochronal annesaling for 1 h between 900 and 1300 °C.
Abstract: The effect of boron content on the grain growth behaviour of type 316L stainless steel was investigated by annealing for 0.25–100 h at 950°C and by isochronal annealing for 1 h between 900 and 1300 °C. Grain growth is enhanced by boron. Activation energies for grain growth are found to be 52 and 317 kJ mol −1 in the lower and higher temperature range respectively.
TL;DR: DNA binding studies performed utilizing calf thymus DNA, indicated that vitamin K3 enhanced the intercalation potential ofADR and also altered the equilibrium between the free and bound form of ADR in a cell free system.
TL;DR: In this paper, a modified shrinking core model is proposed to correlate dynamics of acid sorption on weak base ion exchange resins in free base form, which is easy to apply and is shown to yield results which are in agreement with computationally intensive rigorous model.
Abstract: A modified shrinking core model is proposed to correlate dynamics of acid sorption on weak base ion-exchange resins in free base form. The model considers reversibility of the sorption process which is ignored in the conventional shrinking core model. The model is easy to apply and is shown to yield results which are in agreement with a computationally intensive rigorous model. The model is successfully verified using the experimental data on sorption of strong acids (HCl and HNO3) on weak base resins (Dowex WGR-2 and Amberlite IRA-93).
TL;DR: The time evolution of interface state (D/sub it/) buildup following radiation and high-field stressing in MOS capacitors was compared for 45-nm-thick conventional 'dry' oxide (SiO/sub 2/) and reoxidized nitrided oxide (RNO).
Abstract: The time evolution of interface-state (D/sub it/) buildup following radiation and high-field stressing in MOS capacitors was compared for 45-nm-thick conventional 'dry' oxide (SiO/sub 2/) and reoxidized nitrided oxide (RNO). While the oxide shows the expected postirradiation increase of D/sub it/ with time under positive bias, the RNO shows no time-dependent buildup. This indicates that hydrogen transport, widely held responsible for the slow evolution of D/sub it/ after radiation, does not play a role in D/sub it/ generation in RNO. It is suggested that this is due to a blocking effect of the nitrogen-rich oxynitride layer which is known to exist in RNO near the silicon/silicon-dioxide interface, and which inhibits the drift of hydrogen ions to the interface. Exposure of the capacitors to a hydrogen ambient after irradiation confirms that for RNO, unlike the case of oxide, there is no increase of D/sub it/ due to hydrogen effects. Postirradiation electron injection in RNO suggests that trapped-hole recombination may be responsible for the small D/sub it/ generation seen in RNO. >
TL;DR: The neutron deficient Sr and Zr nuclei are studied in the relativistic mean-field approach and the charge radii are found to increase with the removal of neutrons from the semimagic nuclei, in close agreement with the recent isotopic-shift measurements.
Abstract: The neutron deficient Sr and Zr nuclei are studied in the relativistic mean-field approach. Large deformations and shape coexistence are predicted for these nuclei in the vicinity of the proton drip line. The charge radii are found to increase with the removal of neutrons from the semimagic {sup 88}Sr and {sup 90}Zr, in close agreement with the recent isotopic-shift measurements.
TL;DR: In this article, three indicators are used to study the performance of a single purpose irrigation reservoir in Karnataka, India: reliability, resiliency and a productivity index, and three different optimal operating policies are derived, having increasing mathematical complexity, using stochastic dynamic programming.
Abstract: Three indicators are used to study the performance of a single purpose irrigation reservoir in Karnataka, India. The three indicators are reliability, resiliency and a productivity index. The performance of the reservoir is evaluated when it is operated with optimal operating policies over a sufficient long period of time. Three different optimal operating policies are derived, having increasing mathematical complexity, using stochastic dynamic programming (SDP). Two of the three policies, Policy II and Policy III, incorporate a detailed soil moisture dynamics model as an integral part of the SDP. Policy III considers, in addition, an optimal allocation of water among the irrigated crops when there is competition for water. The reservoir releases are simulated under each optimal operating policy using synthetically generated inflows, and a comparison of the system performances is made.
TL;DR: In this article, the first-order Reissner-Mindlin shear deformation theory is employed to investigate the transient response of isotropic, layered orthotropic and anisotropic composite and sandwich shells.