Total visitors:2,150 since 01-07-04

Indian Journal of  Engineering & Materials Sciences

 

 

 

ISSN : 0971-4588

 

CODEN : IEMSEW

VOLUME 11

NUMBER 3

JUNE 2004

 

 

 

CONTENTS

    

 

Engineering  

Determination of optimum switching angles for speed control of switched reluctance motor drive system

151

Hamid Ehsan Akhter, Virendra K Sharma, A Chandra & Kamal Al Haddad

[IPC Code: Int. Cl.7 H 02P 5/05]

 

 

 

Coupled-admissible functions for simple solutions to unsymmetrically laminated shear flexible beams

169

Gajbir Singh, P S Nair & G Venkateswara Rao

[IPC Code: Int. Cl.7 B 66C 17/04; B 66C 23/00]

 

 

 

A new predictor for ground vibration prediction and its comparison with other predictors

178

Rajesh Rai & T N Singh

[IPC Code: Int. Cl.7 E 21C 41/00]

 

 

 

Design and fabrication of few devices for dynamic measurement of magneto-electric effect

185

G S Bhattacharya, S Mazumder & S Baisnab

[IPC Code: Int. Cl.7 G 01R]

 

 

 

Reverse engineering of a hot ring compression test using FEM

189

K K Pathak, C P Kotwal, S P Narayan & N Ramakrishnan

[IPC Code: Int. Cl.7 G 12B 3/06]

 

 

 

Materials Science
 

 

 

Machinability study on FRP composites¾A neural network analysis

193

D Abdul Budan

[IPC Code: Int. Cl.7 G 06N 3/02]

 

 

 

Durability of mineral admixtured lightweight aggregate concrete

201

Ramazan Demirboğa & Rüstem Gül

[IPC Code: Int. Cl.7 C 04B 14/00]

 

 

 

Second-order nonlinear optical properties of some organic compounds in powder

207

Hamzeh M Abdel-Halim

[IPC Code: Int. Cl.7 C 07B]

 

 

 

Preparation and characterization of mixed halide systems as solid electrolyte base

212

Archana Gupta, Anjan Sil & N K Verma

[IPC Code: Int. Cl.7 C 01B 9/02]

 

 

 

Photoconductivity in vacuum deposited cadmium selenide thin films

217

V Rajendra, V B Kasturi & G K Shivakumar

[IPC Code: Int. Cl.7 H 01L 31/0296]

 

 

 

Optical band gap of Bi2Te2.8Se0.2 thin films

221

P H Soni, J R Otia & C F Desai

[IPC Code: Int. Cl.7 H 01L 29/18]

 

 

 

An electrolytic method for studying the microstructure and grain size of

Al-1.25% Mn alloy

224

V Venkateswara Rao

[IPC Code: Int. Cl.7 C 25C 3/06]

 

 

 

  

Indian Journal of Engineering & Materials Sciences

 Vol. 11, June 2004, pp. 151-168

 

Determination of optimum switching angles for speed control of switched reluctance motor drive system

Hamid Ehsan Akhter, Virendra K Sharma, A Chandra & Kamal Al Haddad

 

Turn-on angle and turn-off angle are the two switching angles that play a major role in deciding whether a switched reluctance motor (SRM) develops positive or negative, high or low electromagnetic torque. Switching angles are function of speed and change with acceleration, but this requires sophisticated and complex digital controllers for real time variation of switching angles as a function of rotor speed. This paper presents a methodology on the determination of fixed turn-on and turn-off angles that are optimum and provide satisfactory performance of the SRM drive during full-load operation. Experimental magnetization and static torque data are used for realistic simulation of dynamic response of a 4 kW, 4-phase, 8-pole stator, and 6-pole rotor configuration SR motor. The simulated performance of SRM drive system is presented to analyze the effect of different switching angles on full-load (25 Nm) starting performance of the drive in terms of speed, current and torque response. An optimum pair of turn-on and turn-off angle that ensures stable and satisfactory full-load operation is recommended.

 

IPC Code : Int. Cl.7 H 02P 5/05

 

 

 

Indian Journal of Engineering & Materials Sciences

Vol. 11, June 2004, pp. 169-177

 

Coupled-admissible functions for simple solutions to unsymmetrically laminated shear flexible beams

Gajbir Singh, P S Nair & G Venkateswara Rao

 

Coupled-admissible functions are derived to obtain simple solutions for unsymmetrically laminated beams. A kinematically admissible variation, as allowed by Rayleigh-Ritz energy method, is assumed for the section rotation. Compatible admissible variations for transverse and axial displacements are derived by making use of equilibrium and boundary conditions. The proposed approach reduces the number of independent unknowns by a factor of three compared to traditional Rayleigh-Ritz method. Expressions for the axial and transverse displacements, section rotation, fundamental frequency and buckling loads for simply-supported, clamped-free and clamped-clamped beams are derived.

 

IPC Code: Int. Cl.7 B66C 17/04; B66C 23/00

 

 

 

Indian Journal of Engineering & Materials Sciences

Vol. 11, June 2004, pp. 178-184

  

A new predictor for ground vibration prediction and its comparison with other predictors

Rajesh Rai & T N Singh

 

In surface mining, explosives in huge quantity are being used for fragmenting  the  rock mass but only a part of the explosive energy is used in doing the useful work, the rest is spent in redundant phenomena such as ground vibrations, noises and air blasts. The elastic energy which is at a level less than the energy required to break the rock, gives rise to ground vibration. Airblast occurs when the gases produced during blasting escape to the atmosphere through existing weakness planes or rock displacement. Ground vibration and airblast both are matter of great concern as it causes damage to the existing surface structures and nuisance to the residents in the closer vicinity of the mine. It attracts more attention as the mines are approaching near exceedingly populated areas. A number of vibration predictors have been proposed which can be used to calculate the safe charge that can be initiated per delay, with minimum spoil to environmental. An attempt has been made to propose a new vibration predictor to calculate the safe charge per delay more precisely.   Its results are compared with other predictors also. A program has been developed for analyzing the data from the field observations. A large number of blast data with wide variation in physico-mechanical properties were collected and analyzed to perceive the accuracy and applicability of the proposed predictor equation.

 

IPC Code: Int. Cl.7 E 21C 41/00

 

 

 

Indian Journal of Engineering & Materials Sciences

Vol. 11, June 2004, pp. 185-188

  

Design and fabrication of few devices for dynamic measurement of magneto-electric effect

G S Bhattacharya, S Mazumder & S Baisnab

 

Measurement of dynamic behaviour of magneto-electric (ME) effect for sintered ceramics has been done by an experimental set-up involving several devices, designed and fabricated in our laboratory. In dynamic method ME signal is registered by measuring the electric potential across the sample under variable dc magnetic field in presence of an ac magnetic field. The relevant devices are dedicated for such measurements only with due consideration to their cost effectiveness. The primary devices begin with the poling system both (a) electric and (b) magnetic, to pole the magneto-electric ceramics. Because of the smallness of ME signal precaution against the noise catch-up is also considered with proper shielding. A lock-in device is used to detect and measure small signals accurately with proper choice of frequency tuned to the frequency of the signal as provided by the frequency generator. The performance of the fabricated devices has been found satisfactory in conducting the dynamic measurement of ME effect for ceramic magneto-electric materials.

 

IPC Code: Int. Cl.7 G01R

 

 

 

Indian Journal of Engineering & Materials Sciences

 Vol. 11, June 2004, pp. 189-192

 

Reverse engineering of a hot ring compression
test using FEM

K K Pathak, C P Kotwal, S P Narayan & N Ramakrishnan

 

This study is related to reverse engineering solution of friction and yield stress in a hot ring compression test using finite element method (FEM). Ring material is steel and test temperature is 800°C. Load deflection curve and the deformed geometry, obtained from the test, are considered as the benchmark parameters for the reverse engineering. The numerical experimentation has been carried out in an iterative manner. The values of friction are varied to find the final geometry matching with the actual deformed shape. Having established the friction, yields stress is varied to match the tonnage employed in the test. It is observed that FEM can be very helpful in such kind of reverse engineering problems.

 

IPC Code: Int. Cl.7 G12B 3/06

 

 

 

Indian Journal of Engineering & Materials Sciences

Vol. 11, June 2004, pp. 193-200

 

Machinability study on FRP composites – A neural network analysis

D Abdul Budan

 

Cutting force is one among the basic factors, which measures the machinability of any material. The determination of cutting forces by experimental means is more common as there is no general mathematical model is available to predict the cutting forces developed as a function of machining and material parameter. However conducting experiment to measure these forces every time is highly expensive and time-consuming. In some cases particularly in machining composites, availability of specimens with the required specifications is extremely difficult. In this work, a multi-layer perception feed forward neural network is constructed to evaluate and compare the cutting forces developed during the machining of glass/epoxy, graphite/epoxy and kevlar/epoxy composites. The fibre orientation, volume fraction and depth of cut were chosen as input parameters for this purpose. The cutting force values evaluated by finite element analysis have been used for training the network. The neural network outputs are compared with the desired output values. Maximum error reduction is possible. Further, the comparison of the neural network output results with the results obtained from experiments and empirical relationship has shown good agreement. Results revealed that kevlar/epoxy has shown good machinable characteristic.

 

IPC Code: Int. Cl.7 G 06 N 3/02

 

 

 

Indian Journal of Engineering & Materials Sciences

 Vol. 11, June 2004, pp. 201-206

 

 Durability of mineral admixtured lightweight aggregate concrete

 Ramazan Demirboğa & Rüstem Gül

 

In this study, the freeze-thaw resistance of concretes made up of different mixtures of expanded perlite and pumice aggregates was determined. The effect of silica fume and fly ash on the freeze-thaw resistance of lightweight concrete was carried out. Silica fume and fly ash were added into the mixture in the replacement of cement, separately, (10%, 20% and 30% respectively). It was observed that increasing perlite ratio in the mixture increased the freeze-thaw resistance of the lightweight aggregate concrete up to 130%. Silica fume and fly ash, replacement of portland cement, also increased the freeze-thaw resistance of the samples up to 83% and 18% respectively. However, with the increasing expanded perlite aggregate for replacement of pumice aggregate in the mixture, the effect of mineral admixtures decreased drastically and for some replacements of silica fume and fly ash reductions occurred up to 23% and 27% respectively. The expanded perlite aggregate, silica fume and fly ash can be used in construction industry to improve freeze-thaw resistance; and therefore to decrease environmental pollution caused by silica fume and fly ash.

 

IPC Code: Int. Cl.7 C04B 14/00

 

 

 

Indian Journal of Engineering & Materials Sciences

 Vol. 11, June 2004, pp. 207-211

 

Second-order non-linear optical properties of some organic compounds in powder

Hamzeh M Abdel-Halim

 

The efficiency of some organic compounds as frequency-doubling materials was determined using Kurtz-Perry powder technique. Compounds were sieve graded to desired particle size before testing their second-harmonic generation (SHG) efficiency. A pulse from a Nd:YAG laser at 1.064 mm was used to examine the efficiency of the material. Effect of particle size on SHG efficiency was studied and showed that the crystalline materials were phase-matchable at certain wavelengths. The intensity of the frequency-doubled output at 532 nm was measured and the second harmonic generation efficiencies obtained were compared with those of standard SHG materials, and other compounds. Comparison showed that the SHG efficiencies of some of the compounds studied here are several orders of magnitude greater than those of known standard materials and substantially higher than other reported compounds.

 

IPC Code: Int. Cl.7 C07 B

 

 

 

Indian Journal of Engineering & Materials Sciences

 Vol. 11, June 2004, pp. 212-216

 

Preparation and characterization of mixed halide systems as solid electrolyte base

Archana Gupta, Anjan Sil & N K Verma

 

The preparations of mixed halide matrices KCl:NaCl and BaCl2:KCl and the effect of ionic size and valency difference of cations on the ionic conductivity of mixed halides are reported in this paper. The ionic conductivities of mixed halide matrices [(KCl)(1 - x):(NaCl)x ; 0£x£0.4] and [(BaCl2)(1 - y):(KCl)y; 0£y£0.5]  have been investigated by impedance spectroscopy method. The compositions (KCl)0.9:(NaCl)0.1 and (BaCl2)0.9:(KCl)0.1  are found to be highly conducting. The thermal characterizations by TG and DTA of the samples of highly conducting compositions have shown no evidence of new compound formation.  A simple model based on the wrong size substitution has been applied to understand conductivity enhancement in the mixed matrices. In the case of (BaCl2)0.9:(KCl)0.1, the conductivity enhancement could be attributed to the net charge transfer across the interface of the biphasic mixture. However, for the (KCl)0.9:(NaCl)0.1 system, the wrong ionic size  plays a significant role in the conductivity enhancement.

 

IPC Code: Int. Cl.7 C 01 B 9/02

 

 

 

Indian Journal of Engineering & Materials Sciences

 Vol. 11, June 2004, pp. 217-220

 

Photoconductivity in vacuum deposited cadmium selenide thin films

B V Rajendra, V B Kasturi & G K Shivakumar

 

Photoconductivity has been studied in cadmium selenide thin films prepared by thermal evaporation in vacuum. Attempts have been made to correlate the photoresponse with the deposition conditions. It has been observed that as-grown films, irrespective of the cadmium content, are not photosensitive and that baking in air, especially above 723 K, leads to considerable improvement in the photoconducting properties of cadmium selenide films.

 

IPC Code: Int. Cl.7 H01L 31/0296

 

 

 

Indian Journal of Engineering & Materials Sciences

Vol. 11, June 2004, pp. 221-223

 

 Optical band gap of Bi2Te2.8Se0.2 thin films

P H Soni, J R Otia & C F Desai

 

Bi2Te2.8Se0.2 thin films were grown using the thermal evaporation technique on a (001) face of NaCl crystal as a substrate at room temperature. The optical absorption was measured in the wave number range 500-4000 cm-1. From the optical absorption data the band gap has been evaluated and studied as a function of the film thickness and deposition temperature. The data indicate absorption through direct interband transition with a band gap of around 0.24 eV.

 

IPC Code: Int. Cl.7 H01 L 29/18

 

 

 

Indian Journal of Engineering & Materials Sciences

 Vol. 11, June 2004, pp.224-226

  

An electrolytic method for studying the microstructure and grain size of Al-1.25% Mn alloy

V Venkateswara Rao

 

An electrolytic polishing and anodizing technique for studying the microstructure and grain structure of Al and Al-1.25% Mn alloy samples is described. The same electrolyte, based on phosphoric acid, can be used for both the applications under slightly different experimental conditions.

 

IPC Code: Int. Cl.7 C 25 C 3/06