Indian Journal of
Engineering & Materials Sciences

http://www.niscair.res.in

 

VOLUME 10

NUMBER 1

FEBRUARY 2003

CODEN : IEMSEW

ISSN : 0971-4588

 

CONTENTS

 

Engineering

 

Optimum diffusion geometry for the automotive catalytic converter

5

        G S Kulkarni, S N Singh, V Seshadri & Ratan Mohan

 

 

Performance of primary holes in presence of dilution and cooling holes in a reverse-flow combustor model

14

        M D Agrawal & Sanjeev Bharani

 

 

New crossover operators for GA-based synchronous sequential circuit testing

21

        M C Bhuvaneswari & S N Sivanandam

 

 

Er-concentration/minimum pump power optimization technique for design of broadband single link using Er-droped dispersion compensating optical amplifiers

27

        Promod R Watekar, M L N Goswami, J C Biswas & H N Acharya

 

 

Development of an apparatus for determining thermal conductance of building and insulating materials

33

        B M Suman & V V Verma

 

 

MHD viscous flow through a porous medium past an oscillating plate in a rotating system

37

        R N Jat & Anuj K Jhankal

 

 

Generalized Reynolds equation for non-Newtonian ferrofluids

41

        Dinesh Kumar Verma, B V Rathish Kumar & Prawal Sinha

 

 

 

 

Materials Science

 

Combustion synthesis of nanosized γ-Fe2O3: Structural, electrical, dielectric and magnetic studies

50

        N N Mallikarjuna & A Venkataraman

 

 

Microhardness and X-ray studies of single crystals of Bi doped with group IV elements, Pb and Ge

59

        Sanjeeta Rani & G K Chadha

 

 

 

Structural relaxation of hybrid composite of phenol formaldehyde

65

        Kedar Singh, N S Saxena, S Thomas & M S Sreekala

 

 

Solar photocatalytic degradation of metal complex azo dyes and treatment of dye house waste

69

        Amit Kumar Saha & Malay Chaudhari

 

 

Preparation of inorganic microfiltration membranes and their characterization

75

        K S Seshadri, K B Lal, R Kesavamoorthy, Pushpa Muthiah, M Selvaraj & V Krishnasamy

 

 

Spectro-structural and microscopic studies on solution-grown CdS1-xTex thin films

82

        V B Patil, G S Shahane & L P Deshmukh

 

 

Notes

 

Large amplitude vibrations of slender, uniform beams on elastic foundation

87

        G Venkateswara Rao

 

 

Transition foundation modulus for the vibration problem of uniform initially stressed simply supported beams on Winkler foundation

92

        G Venkateswara Rao

 

 

 

 

 

                                                                            


 

Indian Journal of Engineering & Materials Sciences

Vol. 10, February 2003, pp. 5-13

 

Optimum diffuser geometry for the automotive catalytic converter

G S Kulkarnia, S N Singha, V Seshadria & Ratan Mohanb

 

Catalytic converters have become an integral part of modern cars as they provide excellent control on pollutants but also lead to reduction in the overall efficiency of the engine. In the present study, the geometry of the inlet header, which is primarily a diffuser, has been optimized using Computational Fluid Dynamics (CFD) for minimizing the pressure loss. It has been found that the optimum design of the diffuser is the one having moderate diffuser half angle for most part of its length and then gradual but steeper diffusion in the later part along with a smooth wall curvature.

 

Indian Journal of Engineering & Materials Sciences

Vol. 10, February 2003, pp. 14-20

 

Performance of primary holes in presence of dilution and cooling holes in a reverse-flow combustor model

M D Agrawal & Sanjeev Bharani*

 

Experimental investigations on discharge coefficient of row of primary holes of a reverse-flow gas turbine combustor have been carried out using a plane annulus model. The studies have been carried out in a wide range of Reynolds number (0.1×104 to 1.65×104) on the individual row of primary holes as well as in combination with the other rows of liner holes. It is observed that presence of other rows of liner holes significantly affect static pressure distribution at the primary holes.

Static pressure at all the four rows of liner holes, when operating together, increased up to a magnitude till Re = 1.35×104 and decreased thereafter with further increase in Re. The values of discharge coefficient of row of primary holes when operating alone remained in the range of 0.74-0.69. These magnitudes reduced in the presence of individual row of dilution (by »18%) and cooling holes (by »6%) while they improved to the extent of »0.77 to 0.72 (K=1510 to 1750) when all the four rows operating together.

 

Indian Journal of Engineering & Materials Sciences

Vol. 10, February 2003, pp. 21-26

 

New crossover operators for GA-based synchronous sequential circuit testing

M C Bhuvaneswari & S N Sivanandam

 

Testing is an essential part of any VLSI manufacturing system as it is necessary to separate bad circuits from the good ones. The testing process detects the physical defects produced during fabrication. Test generation for sequential circuits is a search problem over large vector space, proportional to the number of inputs and number of states. Genetic Algorithm (GA) has been effectively used for Automatic Test Pattern Generation. In this paper, two new crossover operators, the sequence-based and the weight-based, are proposed. The proposed operators significantly improve the performance of a GA-based test pattern generator for stuck-at-faults in synchronous sequential circuits. The effectiveness of the approach is demonstrated on the ISCAS89 sequential benchmark circuits. Experimental results on the ISCAS89 sequential benchmark circuits demonstrate that the weight-based crossover operator is effective for GA-based test generation. The weight-based crossover provides high fault coverage and compact test vectors for most of the benchmark circuits.

 

Indian Journal of Engineering & Materials Sciences

Vol. 10, February 2003, pp. 27-32

 

Er-concentration/minimum pump power optimization technique for design of broadband single link using Er-doped dispersion compensating optical amplifiers

Pramod R Watekara*, M L N Goswamia, J C Biswasb & H N Acharyaa

 

A design of broadband (C-band and L-band) link for dense wavelength division multiplexing (DWDM) system employing Er-doped dispersion compensating optical fiber amplifier is presented using a procedure based on the optimization of Er-concentration with minimum pump power requirement in the optical fiber. The design has been done using simple step index fiber at a pump wavelength of 980 nm. For 45 km of link-length only one pumping scheme has been used. With the channel separation of 50 GHz, a wide band has been obtained for bit rate above 10 Gb/sec. The procedure and results are useful for designing dispersion-less communication fiber link along with amplification.

 

Indian Journal of Engineering & Materials Sciences

Vol. 10, February 2003, pp. 33-36

 

Development of an apparatus for determining thermal conductance of building and insulating materials

B M Suman & V V Verma

 

A new apparatus for determining thermal conductance (C)-value of building and insulating materials has been designed and fabricated at the Central Building Research Institute, Roorkee. Constructional details, working principle and special features of the apparatus are reported. Values of thermal conductance for various indigenous materials agree within ± 5% range with those determined by standard methods. This method needs a pre-calibrated standard sample so it is a relative method for evaluating thermal conductance.

 

Indian Journal of Engineering & Materials Science

Vol. 10, February 2003, pp. 37-40

 

MHD viscous flow through a porous medium past an oscillating plate
in a rotating system

R N Jat & Anuj K Jhankal

 

Three-dimensional unsteady flow of an incompressible viscous fluid in presence of transverse magnetic field through a porous medium past an oscillating porous plate subject to uniform suction/injection (blowing) in a rotating system, whole system being in state of solid body rotation with constant angular velocity about z-axis normal to the plate, is discussed here. The effect of porous medium, the suction/injection (blowing) parameter on the velocity distribution, has been graphically shown for different values of magnetic parameter, M, and suction parameter, S.

 

Indian Journal of Engineering & Materials Sciences

Vol. 10, February 2003, pp. 41-49

 

Generalized Reynolds equation for non-Newtonian ferrofluids

Dinesh Kumar Vermaa, B V Rathish Kumarb & Prawal Sinhab

 

In this paper, a generalized form of Reynolds equation is derived for viscoelastic ferrofluid lubrication in the presence of a constant magnetic field applied transversely to the flow. As a particular case, one-dimensional form of it is used to study the characteristics of a squeeze film. It is observed that the effect of viscoelastic parameter is to reduce the load capacity of the bearing even in the case of magnetic fluid.

 

Indian Journal of Engineering & Materials Sciences

Vol. 10, February 2003, pp. 50-58

 

Combustion synthesis of nanosized g-Fe2O3: Structural, electrical, dielectric and magnetic studies

N N Mallikarjuna & A Venkataraman*

 

Combustion synthesis of nanosized g-Fe2O3 using polyethylene glycol as a fuel has been reported. Four different precursors were taken to see the feasibility of conversion to g-Fe2O3 in a single step. The as synthesised g-Fe2O3 samples were characterised by X-ray diffraction (XRD), infrared (IR), transmission electron microscopy (TEM), electrical, dielectric, magnetic and Mössbauer techniques. The g-Fe2O3 samples were found to crystallise in a cubic system. Unit cell parameters were obtained by least square refinement of the X-ray powder data using PROZSKI program. The crystallite sizes were calculated using X-ray line broadening. TEM studies showed that particles are in the range of 20-50 nm. X-ray, tap and apparent densities were determined and compared with the g-Fe2O3 prepared by conventional methods. All the g-Fe2O3 samples showed semiconducting behaviour. From dielectric studies it was observed that dielectric constant vary from 100 to 2000 depending upon the precursor used to prepare g-Fe2O3 and number of Fe2+ and Fe3+ ions present in that sample. The saturation magnetisation of these samples are in the range of 40-50 emu/g.

 

Indian Journal of Engineering & Materials Sciences

Vol. 10, February 2003, pp. 59-64

 

Microhardness and X-ray studies of single crystals of Bi doped with group IV elements, Pb and Ge

Sanjeeta Rania & G K Chadhab

 

Microhardness tests and X-ray studies performed on single crystals of pure Bi, Bi-Pb (3at.%) and Bi-Ge (2at.%) in trigonal direction [111] at room temperature reveal quite contrasting features for Pb and Ge as dopants, despite the fact that both of these belong to group IV of periodic table of elements. It is reported that Pb has a hardening effect on the bismuth lattice, whereas Ge has softening effect on bismuth lattice. This result may find many metallurgical and industrial applications. The Vicker’s hardness number increased to a value of 13.9 for Bi-Pb system, whereas it decreased to a value of 11.8 for Bi-Ge system, compared to a value of 12.4 for pure Bi. Microhardness tests and X-ray studies indicate Pb and Ge make predominantly a solid solution with bismuth by substituting for Bi atoms at various lattice sites with small discontinuous traces of second phase scattered over a uniform main phase. In Bi-Pb system this second phase is identified to be the e phase comprising of Bi dissolved in Pb and in Bi-Ge system the second phase is identified to be the segregated Ge, rejected by the Bi lattice on account of limited solubility of Ge in Bi. XRD patterns reveal that the lattices of the doped systems are largely those of bismuth and volume fraction of second phase is negligibly small in both the systems. Cohen’s method of least squares refinement for cubic system is modified for Bi lattice, indexed on hexagonal axis and a system of normal equations is set up for pure Bi and both the doped systems. These equations are subjected to least squares treatment to obtain lattice parameters, a and c, of pure Bi, Bi-Pb and Bi-Ge systems. It is reported while the unit cell of pure Bi expands, when Pb is added to it, it contracts when Ge is added to it. Laue back-reflection photographs taken along trigonal [111] direction show that 3-fold symmetry of pure bismuth lattice is retained after doping also.

 

 

Indian Journal of Engineering & Materials Sciences

Vol. 10, February 2003, pp. 65-68

 

Structural relaxation of hybrid composite of phenol formaldehyde

Kedar Singha, N S Saxenaa, S Thomasb & M S Sreekalac

 

 

Glass-palm fibre reinforced hybrid phenol formaldehyde (PF) composites have been studied at constant heating rate by using differential scanning calorimetry (DSC). Sample under investigation is annealed for different times and temperatures. Glass transition temperature (Tg), crystallization temperature (Tc) and heat absorbed (ΔH) in glass transition region have been calculated for glass-palm fibre reinforced hybrid phenol formaldehyde composite. It is found that Tc-Tg and ΔH are maximum at annealing time of 60 min and temperature of 60ºC. This composite is found to be more thermally stable at these annealing time and temperature due to structural relaxation.

 

 

Indian Journal of Engineering & Materials Sciences

Vol. 10, February 2003, pp. 69-74

 

Solar photocatalytic degradation of metal complex azo dyes and treatment of
dye house waste

Amit Kumar Saha & Malay Chaudhuri

 

In a laboratory study, the effectiveness of zinc oxide-mediated solar photocatalytic degradation of three metal complex azo dyes (Acidol Yellow, Acidol Grey and Acidol Scarlet) and treatment of a woollen textile dye house waste were examined. A 53-86% degradation of the dyes was achieved by 15 min illumination with a sunlight intensity of 0.5-0.8 kW/m2 and zinc oxide dose of 1.5 g/L. A 67-93% decrease in degradation rate was observed for degradation of the dyes in mixture (simultaneous degradation). It was, however, observed that pre-adsorption was not a necessary prerequisite for degradation. Treatment of the dye house waste containing the three dyes, with zinc oxide (3.0 g/L), reduced colour (89%) and COD (63%) in 2.75 h illumination. BOD5/COD ratio increased from 0.43 to 0.66. The study has demonstrated that zinc oxide-mediated solar photocatalytic degradation is a potentially useful method of treatment of dye house waste containing metal complex azo dyes.

 

Indian Journal of Engineering & Materials Sciences

Vol. 10, February 2003, pp. 75-81

 

Preparation of inorganic microfiltration membranes and their characterization

K S Seshadria, K B Lal a, R Kesavamoorthyb, Pushpa Muthiaha , M Selvarajc & V Krishnasamyc

 

A study on the dynamic growth of titania and zirconia layers on microporous alumina was carried out. The porosity of the membrane layers was estimated from the amount of water content in the pores. The thicknesses of the membrane layers were estimated from the membrane volume, membrane pore volume and the coated area of the support. Results indicated that the porosity of the titania and zirconia membranes were 0.31 and 0.38 respectively and the thickness of the layers as 3 micron in a period of 60 min. The membranes were found to be very good to retain suspended particles.

 

Indian Journal of Engineering & Materials Sciences

Vol. 10,February 2003, pp. 82-86

 

 

Spectro-structural and microscopic studies on solution-grown
CdS1-xTex thin films

V B Patil­a*, G S Shahaneb & L P Deshmukha

 

Compositional, structural, microstructural and optical properties of thin films of CdS1-x Tex (0£ x £ 1) prepared by the solution-growth technique are reported as a function of x. The film composition has been determined and compared with the bath composition. A non-linear relation has been found between them. The composites are crystalline in nature and pure CdS and CdTe existed in both hexagonal wurtzite and cubic zinc blende structures. Only wurtzite structure undergoes solid solution in the region 0 £ x £ 0.1 and 0.9 £ x £ 1. For 0.1 < x < 0.9 the films have been composed of the mixed phases of CdS and CdTe. The lattice parameters a and c vary with x following Vegard’s law in the solid solution region. The surface topography showed polycrystalline texture with a rough surface and diffused grain structure. Optical studies revealed a high absorption coefficient (104-105 cm-1) with direct type of transition.

 

Indian Journal of Engineering & Materials Sciences

Vol. 10, February 2003, pp. 87-91

 

Large amplitude vibrations of slender, uniform beams on elastic foundation

G Venkateswara Rao

 

The large amplitude vibrations of slender, uniform beams, with axially immovable ends, on an elastic foundation are described in this paper. The governing differential equation given by Woinowsky-Krieger is generalised to include the effect of the elastic foundation. The space variable in the differential equation is eliminated, by assuming suitable admissible functions in space to represent the simply supported or clamped boundary conditions at the ends, using the standard Galerkin method. The resulting temporal equation is solved by a numerical integration scheme to obtain the linear and nonlinear frequencies for a specific maximum amplitude. The results obtained, in terms of the ratio of the nonlinear frequency to the linear frequency, when the foundation stiffness is zero, agree well with those available in literature. It is observed from the numerical results that the effect of the elastic foundation reduces the nonlinearity for both the simply supported and the clamped beams.

 

 

Indian Journal of Engineering & Materials Sciences

Vol. 10, February 2003, pp. 92-94

 

Transition foundation modulus for the vibration problem of uniform initially stressed simply supported beams on Winkler foundation

G Venkateswara Rao

 

The phenomenon of the existence of a transition foundation stiffness for the buckling problem of a simply supported column on Winkler foundation is well-known. It is also shown that such a phenomenon does not exist for a simply supported beam for the vibration problem. This paper presents a study of the aforementioned phenomenon with respect to a simply supported beam, subjected to an initial axial load, resting on a Winkler foundation.