006155   Srinivasan V S;Laha K;Bhanu Sankara Rao K; Mannan S L;Baldev Raj (Mater Dev Grp, Indira Gandhi Cent for Atom Res, Kalpakkam-603 102, Email: vssrini@igcar.ernet.in) : Prediction of long-term creep rupture strength for modified 9Cr-1Mo ferritic steel. Trans Indian Inst Metals 2005, 58(2-3), 255-9.

Creep rupture stresses at temperatures between 723-923 K have been estimated at a rupture life of 2.63X10⁵ h for mod. 9Cr-iMo steel, using short-term tests data. Larson-Miller Parameter (LMP) and artificial neural network (ANN) approaches have been employed for extrapolation. The results are compared with extrapolated RCC-MR code data.

3 illus, 4 tables, 16 ref

006154   Srinivasan R;Chellapandi P;Chetal S C;Bhoje S B (NO, Indira Grandhi Cent for Atom Res, Kalpakkam-603 102, Email: rsv@igcar.ernet.in) : Effect of weld profile on creep-fatigue damage of PFBR steam generator tubes. Trans Indian Inst Metals 2005, 58(2-3), 387-92.

In Fast Breeder Reactors, Steam Generator is a critical component as its availability decides the capacity factor of the plant. Operating experiences have shown that many sodium leak and consequent sodium water reactions have occurred at the tube to tubesheet welds. To have reliable joint, the internal bore welding of tube to spigot (machined from tubesheet) is chosen, so as to have weld away from the stress concentration zone. In the view of the unavoidable manufacturing deviations, creep-fatigue damage is evaluated as per RCC-MR for various weld profiles by detailed FEM analysis. In the analysis, loss of thickness due to corrosion is considered. For various failure modes, appropriate reduction factors from literature are applied to take into account the effects of weldments. Inspite of the assumption of a sharp corner at the junction of weld to base metal, fatigue damage is negligible and creep damage is governing for all the cases. From creep damage consideration, convexity on inside diameter (ID) with matching concavity on outside diameter (OD) is the most damaging configuration, A convexity of 0.5 mm on ID associated with weld thinning of 0.2 mm results in a creep damage of 0.88. Conservatively, maximum convexity of 0.35 mm and weld thinning of 0.2 mm are recommended which will result in a creep damage in the range of 0.5-0.6 and fatigue damage less than 0.1.

8 illus, 10 ref

006153   Srinivas K;Patvardhan C;Bhagwan Das D (Dep of Electl Engng, Dayalbagh Educ Inst, Agra-282 005) : An evolutionary algorithm for optimization of deceptive and deceptive multimodal functions. J Instn Engrs-Pt CP 2005, 86(May), 10-17.

An evolutionary algorithm for deceptive and multimodal deceptive functions (EAD) is presented. Deceptive (fully and partially) as well as multimodal deceptive functions are known to be very difficult to optimise with traditional techniques and simple evolutionary algorithms (EAs). Deceptive functions cause the EAs to get misled towards deceptive attractors. There is a difference in problems caused by multimodality and by deception. For deception to take place, it is necessary to have at least two optima in the search space (a true attractor and a deceptive attractor), but almost the entire search space favours the deceptive (non global) optimum, whereas multimodality may cause difficulty to a search algorithm, merely because of the sheer number of different local optima where it can get stuck. Both multimodality and deception can coexist in a function, thereby making these so called massively multimodal deceptive problems even harder to solve using EA Hybridisation of EA with gradient based methods is not very effective in such problems. EAD incorporates simulated annealing (SA) in the selection process improving its solution quality, speed of convergence and consistency on a variety of problems. It also facilitates the search of solution space by exploiting the desirable convergence properties of SA while maintaining the population approach and recombinative power of EA. The search procedure is made more effective by ensuring that more search is devoted to the promising regions of the feasible. search space. Additional features an incorporated to create an ability to handle deception. The computational performance of the proposed method is evaluated on well known deceptive and multimodal deceptive functions. The results indicate that EAD effectively discovers optimal solutions by examining an extremely small fraction of the feasible solution space even for these extremely difficult functions.

10 illus, 1 table, 25 ref

006152   Singhal R;Malhotra B D (Biomolecular Electron and Conducting Polym Res Grp, Natn Phys Laboratory, Dr K S Krishnan Road, New Delhi-110 012, Email: bansi@mail.nplindia.ernet.in) : Langmuir-Blodgett films of poly-N-vinyl carbazole for application to glucose biosensor. Asian J Phys 2005, 14(1-2), 151-9.

Langmuir Blodgett films of poly-N-vinyl carbazole (PNVK) and stearic acid (SA) were formed at the air-water interface of a Joyce Loebl trough at room temperature (30°C) and at pH 7.0. These PNVK/SA monolayers were transferred onto indium-tin-oxide (ITO) coated glass plates by vertical dipping method and were characterized using low angle X-ray diffraction and atomic force microscopy (AFM). The roughness of PNVK/SA LB films has been Bound to be 0.5 nm. The d-spacing obtained from XRD measurements was found to be 50.4 Angstrum. Further, enzyme glucose oxidase (GOX) was immobilized onto these PNVK/SA LB films using LB technique. These GOX immobilized PNVK/SA LB electrodes were used for glucose estimation from 100 mg/dL to 500 mg/dL glucose concentration and were found to be stable upto 40°C. These PNVK/SA/GOX LB electrodes could be repeatedly used for glucose estimation within 15 days. The shelf life and half life of these PNVK/SA/GOX LB electrodes was found to be about five months and four months, respectively.

5 illus, 1 table 43 ref

006151   Singh S P;Mohammadi Y;Kaushik S K (Civil Engng Dep, Natn Inst of technology, Jalandhar-144 011) : Flexural faigue strength and failure probability of steel fibrous concrete containing mixed fibres. J Instn Engrs-Pt CI 2005, 86(May), 12-18.

The paper presents a study on the fatigue strength of Steel Fibre Reinforced Concrete (SFRC). An experimental programme was conducted to obtain the fatigue lives of SFRC at various stress levels. One hundred and forty eight SFRC beam specimens of size 500 mm x 100 mm x 100 mm were tested under four-point flexural fatigue loading. Aboutsixty complimentary static flexural test were also conducted to obtain the static flexural strength prior to fatigue testing. All the fatigue tests were conducted 100 kNMTS close loop servo-controlled universal testing machine whereas the static tests were con ducted on a similar INSTRON machine. The specimens incorporated 1.0% volume fraction of corrugated mixed steel fibres of size 0.6 mm x 2.0 mm x 25 mm and 0.6 mm x 2.0 mm x 50 mm in different proportions. The results indicate that the distribution of fatigue life of SFRC can be modelled by two-parameter Weibull distribution. The Weibull distribution has been used to incorporate the failure probabilities into the fatigue life data of SFRC. The fatigue lives corresponding to different failure probabilities have been calculated and the data so obtained has been used to plot the Pf-S-Ndiagrams.

3 illus, 9 tables, 28 ref

006150   Singh I B;Prasad M;Amritphale S S (Regional Res Laboratory, , Bhopal-462 026) : Development of defluoridation technology for its easy adaptation in rural areas. J rur Technol 2004, 1(4), 163-7.

Various defluoridation methods have been developed to reduce fluoride content up to desirable level in the drinking water but none of them have been found suitable to the extent of wider acceptablity. Defluoridation based on ion exchange/sorption by bone char, synthetic ion exchange materials and activated alumina are somewhat successful. However, due to high installation and maintenance cost, these technologies may not be accepted. Although "Nalgonda Technique" is preferred due to the use of low cost raw materials namely alum and lime, this technology suffers from maintenance problem. A brief description about main technologies is given to point out their limitations and scope for further improvement. Intensive research efforts are underway at RRL,- Bhopal to look into the various possibility of development of alternative cost effective methods of defuoridation. A substantial level of fluoride removal by specific mineral and an agricultural waste namely rice husk derived activated carbon have been measured. The experimental results obtained are also discussed.

5 illus, 20 ref

006149   Singh B;Aggarwal K K;Kumar S (Dep of Electron and Commun Engng, Natn Inst of Technol, Kurukshetra-136 119) : Optimizing handover performance in microcellular systems. J Instn Engrs-Pt ET 2005, 86(July), 28-31.

Paper presents a handover initiation algorithm based on signal strength measurements. Handover initiation criterion uses relative signal strength with hysteresis margin approach. Average number of handovers and outage probability are used as performance measures. Performance results are obtained through computer simulation. Optimum handover design parameters are obtained using the trade off curve between the two performance measures.

3 illus, 9 ref

006148   Singh A P;Kamal T S;Kumar S (Dep of Electron and Commun Engng, Sant Longowal Inst of Engng and Technol, Longowal 148 106) : Linearizing transducer's static characteristic using ANN. J Instn Engrs-Pt ET 2005, 86(July), 21-7.

With the facility of computation now available through digital computers and microprocessors, the problem of transducer nonlinearity is being increasingly tackled by them, through software packages.However for an arbitrary non-linear transducer's static response characteristic, a software solution depends upon the proper approach through mathematical modelling of the response curve. The paper presents an artificial neural network (ANN) based least-mean-square regression method, for transducer modelling in a computer-based measurement system. An ANN-based versatile algorithm integrated in the form of a virtual-instrumentation system, around a PC-based data acquisition card, is presented. Fourth generation, object-oriented, graphical-programming language, is used to develop a high performance user-interactive interface. Experimental results of the estimation as well as self-compensation of the static-nontinearity, associated with the DAS connected transducer of a PC-based pressure measurement system are presented.

11 illus, 3 tables, 20 ref

006147   Shukla S K;Parashar G K;Trikha K C;Misra P; Shukla R K;Mishra A P;Dubey G C (USIC, Univ of Delhi, Delhi-110 007) : Electrical properties of bio-sensors. Asian J Phys 2005, 14(1-2), 85-95.

Sensors are an integral part of today's multidisciplinary approach towards the modern scientific progress and advancement. They bear a great technological significance because of their use as monitoring tool for identifying the challenging problems in the field like environment, energy conservation, bio as well as information technology etc. A few commonly used biosensors are discussed to explore the possible work mechanism specifically in the electrical domains namely conductance, impedance, pH and redox related properties.

4 illus, 67 ref

006146   Shetty M;Haldar S;Sivakumar Babu G L (M/s Byucksan Engg Co., , Taiwan) : Behaviour of laterally loaded piles. Indian Geotech J 2005, 35(2), 132-43.

9 illus, 4 tables, 9 ref

006145   Shen C Y;Shen Y T;Huang C L;Wu L (Dep of Electl Engng, I-Shou Univ, Kaohsiung, 840, R O C, Email: cyshen@isu.edu.tw) : The theoretical analysis of metal film on SH-SAW sensors. Asian J Phys 2005, 14(1-2), 111-15.

Investigate the influence of metal layer, coated on Y36°-X LiTaO₃ shear-horizontal surface acoustic wave (SH-SAW) sensors. Three different metals, i.e., gold, titanium, and aluminum, were employed and studied. This work has also simulated and studied the mass loading of metal layer before target species absorption, as well as the effects of metal layer thickness and selective sensing film thickness on SH-SAW responses after target species absorption. The influence of metal thickness on the velocity shift and sensitivity obviously saturated when metal thickness was more than 1000 Angstrum. On the other hand, aluminum showed the smallest mass loading. Accordingly, for keeping oscillation, aluminum is the most suitable metal layer employed on SH-SAW sensors.

4 illus, 11 ref

006144   Shanmuga Sundaram M;Venkatesan A;Rajasundaram P;Sundari C;Lakshmi P;Venugopal S;Purniah B (Metallurgy and Mater Grp, Indira Gandhi Cent for Atom Res, Kalpakkam-603 102) : Smart PLC based intelligent control and monitoring systems for in-sodium test facility. J Instrum Soc India 2005, 35(3), 304-13.

In-sodium testing facility (INSOT) for testing of creep and fatigue behaviour of fast breeder reactor structural materials under flowing sodium at elevated temperature is developed. The parameters monitored are sodium level, leak and the controlling parameters are sodium temperature, flow and pressure. Paper examines the experience of system architecture and special features of the smart control system comprising of programmable logic controllers (PLCs), Field Access Units (FAUs) and personal computer based software (SCADA), which are configured for instrumentation and control of creep and fatigue loops of the INSOT facility. The loops consists of main section, cold trap, oxygen meter, carbon meter, foil chamber and test sections. The paper describes the experience of various monitoring facilities, control methodology and the results obtained.

10 illus, 9 ref

006143   Shah N A;Rather M F;Iqbal S Z (Postgrad Dep of Electron and Instrumentation Technol, Univ of Kashmir, Srinagar-190 006, Email: farsgr@yahoo.co.in) : CFA-based three input and two outputs voltage-mode universal filter. Indian J pure appl Phys 2005, 43(8), 636-9.

A new voltage-mode (VM) multifunction filter based on, employing two plus type current feedback amplifiers (CFA) and as many capacitors, and three resistors with three inputs and two outputs, is presented. The proposed configuration synthesize all the generic filtering functions namely lowpass (LP), bandpass (BP), highpass (HP), notch (BS) and allpass (AP) with two functions simultaneously, without requiring the change to be induced in the passive elements and/or rotation of components. The circuit enjoys the features of: orthogonal control of the natural frequency and the quality factor, low impedance outputs suiting cascadibility for higher order transfer functions, and low active and passive sensitivities. The results of computer simulation using PSPICE are discussed.

7 illus, 11 ref

006142   Shah N A;Malik M A (Postgrad Dep of Electron & Instrumentation Technol, The Univ of Kashmir, Srinagar-190 006) : FTFN based dual inputs current-mode allpass inverse filters. Indian J Radio Space Phys 2005, 34(3), 206-9.

Four new configurations implementing first-order current-mode allpass inverse filter signals are presented. The proposed generic circuit with two inputs and a single output employs a single FTFN, three resistors and a capacitor with both the inputs supporting the first-order allpass inverse responses separately. The topologies offer high output impedance, which enable easy cascading in current-mode. The realizability condition is simple and temperature invariant, being in the ratio of two grounded resistors. The additional advantage of the circuit is that the phase can be controlled by adjusting the values of passive components without disturbing the realizability condition. The tracking error performance for the filters has also been studied. The simulation results are also included.

4 illus, 14 ref

006141   Senthilvelan S;Gnanamoorthy R (Dep of Mechanical Engng, Indian Inst of Technol Madras, Chennai-600 036, Email: gmoorthy@iitm.ac.in) : Reinforced polymer gear: fatigue and failure analysis. Trans Indian Inst Metals 2005, 58(2-3), 249-53.

Gears made of advanced polymers and polymer reinforced composites find increasing application in home, office and industrial equipments. Increasing use of polymer and reinforced polymers is mainly due to economical and technical advantages compared to metals. Polymer reinforced gears are light in weight and can be economically produced using injection molding techniques. However, the low mechanical strength and temperature resistance limits the application of polymer gears for load bearing applications. Describes the development and performance of Nylon 6 and Nylon 6 Glass Filled polymer gears manufactured using injection molding process. Gears with a module of 2 mm and 20° pressure angle were developed in the laboratory. A power absorption type polymer gear test rig has been used for evaluating the gear fatigue performance. Polymer gears were tested against metallic gears at different torque levels. Number of cycles to failure at different contact stress levels were generated. Glass filled nylon gears performed well compared to nylon gears at high stress levels. At higher stress levels, significant tooth shape distortion and crazing followed by cracking was dominant for unfilled and glass filled polymers, respectively.

4 illus, 1 table, 5 ref

006140   Schallow P;Christ H J (Institut fur Werkstofftechnik, Universitat Siegen, D-57068 Siegen, Germany, Email: christ@ifwt.mb.uni-segen.de) : Thermomechanical fatigue behaviour of a γTiAl sheet material. Trans Indian Inst Metals 2005, 58(2-3), 399-404.

Monotonic stress-strain behaviour, LCF and TMF behaviour of a Ti-46.5at.%-4at.%(Cr,Nb,Ta,B) alloy ingot metallurgically processed was investigated in the temperature range between 773 K and 1023 K. The ductile-to-brittle transition temperature (DBTT) was found to be 923 K. The cyclic stress-strain (CSS) response of LCF-tested specimens is characterized by an immediate state of cyclic saturation which continued up to failure. An increased fatigue life which is observed at elevated temperature is associated with a change of the fracture morphology from a transgranular cleavage type of fracture to a more dimple intergranular type. IP loaded specimens show the onset of dynamic recrystall isation which leads to an increased fatigue life as compared to LCF tests carried out at maximum temperature. OP loading is most detrimental with a well-reduced fatigue life, when compared to LCF tests carried out at the minimum temperature.

8 illus, 13 ref

006139   Saxena S;Ramachandra Murthy D S (Regional Res Laboratory, , Bhopal-462 003, Email: rmurthy@sercm.res.in) : Elastic-plastic fracture mechanics based prediction of fracture instablity in a circumferentially through-wall cracked pipe in bending. Trans Indian Inst Metals 2005, 58(2-3), 461-6.

Elastic-plastic fracture mechanics methods are now increasingly being used in the evaluation of structural integrity of flawed piping components. Among the several methods currently being used, the J-integral tearing modulus approach (J-T) has received much attention. Using J-T approach, the study has been carried out on 406 mm outer diameter circumferentially through-wall cracked (TWC) pipes to predict the limiting load, which will cause fracture instability. The solutions are found to have good comparison with the maximum experimental load, indicating the dominance of ductile tearing phenomenon. Hence, the tearing modulus approach can be used to predict fracture instability in piping components having a crack.

4 illus, 3 tables, 9 ref

006138   Satyanarayana Reddy C N V;Rama Moorthy N V (Dep of Civil Engng, Kakatiya Inst of Technol & Sci, Warangal-506 015) : Swell control of expansive subgrades with geotextiles and granular cushions. Indian Geotech J 2005, 35(2), 177-97.

10 illus, 10 tables, 20 ref

006137   Satya Devi A;Sivakumar S M;Bhattacharya S S (Dep of Mechanical Engng, G V P Coll of Engng, Visakhapatnam-530 041, Email: ssb@iitm.ac.in) : On the applicability of a damage mechanics based model for stress controlled very low cycle fatigue. Trans Indian Inst Metals 2005, 58(2-3), 337-41.

Very Low Cycle Fatigue (VLCF) behavior of materials assumes importance in the context of design of structures that are subjected to extreme loading conditions such as rocket components, earthquakes and accidents. During VLCF, large plastic strains are encountered and the number of cycles to failure is in the range of less than 100. In general, models based on damage mechanics approaches mimic closely the physical phenomena that occur during VLCF and, therefore, are very good candidates suitable for life prediction under such circumstances. In the study, a simple damage mechanics model based on an earlier proposed model, is considered for the description of stress controlled VLCF. In this model, the life of a material undergoing VLCF is expressed in terms of the maximum stress and the plastic strain. At present, the capability is limited to uniaxial loading but can be extended to multiaxial loading with due modifications. For the numerical validation of the model, uniaxial stress controlled very low cycle fatigue tests have been carried out on commercial steel and mild steel at different stress levels. It is shown that the life predicted by the present model is jn close agreement with the experimental results.

4 illus, 3 tables, 3 ref

006136   Sandhya R;Bhanu Sankara Rao K;Mannan S L (Mater Dev Grp, Indira Gandhi Cent for Atom Res, Kalpakkam-603 102, Email: san@igcar.ernet.in) : The effect of prior microstructure on the low cycle fatigue behaviour of A 15Cr-15Ni, Ti modified astenitic stainless steel. Trans Indian Inst Metals 2005, 58(2-3), 303-8.

Fully austenitic 15Cr-15Ni titanium modified austenitic stainless steel (Alloy D9) is being used as fuel clad and wrapper material in fast breeder reactors. As part of a larger programme of characterising the Low Cycler-TLJiatigueJLCF) and Creep-Fatigue Interaction behaviour of this alloy as a function of Ti/C ratio, the alloy with a Ti/C ratio of 8 has been tested in three microstuctural conditions:(a) solution annealed (b) 20 % cold worked and (c) aged at 1023 K/2h. LCF tests have been carried out at 823 and 923 K employing strain amplitudes in the range ±0.25% to ±1.0% at a strain rate of 3 x 10^-3 s ^-1. At both the temperatures tested the solution annealed material exhibited cyclic hardening, while the cold worked material exhibited cyclic softening. The aged material showed hardening for the first few cycles, followed by cyclic softening. While the solution annealed material exhibited superior LCF lives in terms of plastic strain resistance, the cold worked and aged materials exhibited better LCF resistance in terms of total strain resistance especially at lower strain amplitudes. The deformation substructure developed during fatigue deformation has been characterized and correlated with the cyclic stress response and LCF life.

9 illus, 4 tables, 13 ref

006135   Samanta A K;Datta P (Dep Appl Mechanics and Drawing, Natn Inst of Technol, Durgapur-713 209) : Case study on assessment of the effect of bending and transverse Shear on long right circular cylindrical stacklike structures. J Instn Engrs-Pt CI 2005, 86(May), 34-43.

The accuracy of a physical model largely depends on the mathematical model. Practicing professionals mostly prefer to employ approximate models for the design of a structure. Models based on such method ignores a designer to evaluate the deformation pattern of the structure as a whole. To avoid pitfalls a designer adopts a conservative approach in view of quick and easy solution for the purpose. Moreover, reinforcement requirement remains on much higher side, not only increasing hazards in detailing as well as construction but also overall cost of the structure. In earlier days, plate/shell structures were analysed as grid structure/wire mesh in absence of sophisticated tools like various FEM packages. Although, a wire mesh gives some idea about the deformation pattern, but it is unable to handle complicated situations. It has also been shown that the values of bending stresses are exceptionally on conservative side, when analysed using such method by modelling the same as wireframe. Hence, such approach is not potentially reliable for such domains in general. Here, a case study of transverse shear on long cylindrical structure, eg, silo, has been presented, following three different methods. The results obtained have been compared to assess their potentiality and suitability in understanding true behaviour of such a system.

10 illus, 4 tables, 6 ref

006134   Sai Srinadh K V;Singh V (Cent of Advd Study Dep of Metall Engng, Inst of Technol Banaras Hindu Univ, Varanasi-221 005, Email: vakil@banaras.ernet.in) : Low cycle fatigue behaviour of near α titanium alloy IMI 834 at room temperature and at 673 K. Trans Indian Inst Metals 2005, 58(2-3), 431-6.

Low cycle fatigue (LCF) behaviour of the near a- titanium alloy IMI 834 was studied, for the (α+β) solution treated, air cooled and stabilized condition, at room temperature (RT) and at 673 K. It had bimodal microstructure with nearly 12 vol.% of primary α in the matrix of lamellar transformed β. LCF tests were conducted at different total strain amplitudes (Δε_t/2) from ± 0.75% to ± 1.3%, with triangular waveform of loading, at a constant strain rate of 0.008 s^-1. While there was cyclic softening at room temperature, there was cyclic hardening followed by softening at 673 K. Further, while there was bi-linear behaviour in Coffin-Manson (C-M) relationship at room temperature.There was only linear behaviour at 673K, over the entire range of the total strain amplitude studied.

5 illus, 2 tables, 13 ref

006133   Sabura Banu U;Uma G;Pannerselvam M A (Crescent Engg. Coll, , Vandalur, Ghennai, Tamil Nadu) : Digital signal processor triggering converters in switched mode power supplies. J Instrum Soc India 2005, 35(3), 275-81.

In Switched Mode Power Supplies DC-DC power converters are used. Various levels of voltages are generated from a single voltage source by interrupting the power flow and controlling the duty cycle which results in pulsating currents and voltages. Power switches have to cut off the load current within the turn-on and turn-off times under the hard switching conditions. Hard switching refers to the stressful switching behavior of the power electronic devices. Typical converter switching frequency was limited to a few tens of kilo-Hertz (typically 20kHz to 50kHz) in early 1980's. Quasi Resonant Converter (QRC) eliminates the switching losses encountered in pulse width modulation (PWM) converters. Industry standard for pulse generation of Quasi Resonant converter in Switched Mode Power Supply is by analog means resulting in slower evolution. In the paper a high speed, lower cost Digital Signal Processor (DSP) is used for the same. Simulation is, performed using MATLAB followed by the implementation aided by TMS320C240F for triggering the gate pulse of the IGBT in the Power circuit.

15 illus, 3 ref

006132   Rajhans N R;Ahuja B B (Viswakarma Inst of Technol, , Pune-441 307) : Analyzing decision factors for redesigning a plant layout using analytical hierarchical processing. J Instn Engrs-Pt ID 2005, 86(May), 5-8.

The paper suggests the use of Analytic Hierarchy Process for analyzing the parameters, involved in layout and relayout decisions. The multiple criteria selected for each of the major factors, viz, flexibility, batch size, cost and accessibility for maintenance are well chosen based on the case study undertaken. Ultimate decision of the process is based on 'relative importance' effecting the output yield of the alternatives available.

3 illus, 11 tables, 2 ref

006131   Prem Navin D;Ramachandra Murthy D S (Structural Engng Res Cent, , Chennai-600 113, Email: rmurthy@sercm.csir.res.in) : Probabilistic study of fracture strength of through-wall cracked pipes. Trans Indian Inst Metals 2005, 58(2-3), 453-9.

Fracture strength of piping components used in primary heat transport system of nuclear power plant is of great importance to ensure safety against improbable accidental loads. The theoretical plastic collapse load for the net cross section is used to calculate the strength of pipes having flaws/cracks. The results of the 55 experiments conducted by several investigators on through-wall circumferentially cracked pipes were statistically analyzed for their maximum load capacity. Frequency distribution of experimental moments normalized by their theoretical plastic collapse moments was studied and a best fit was found using goodness of fit test. Based on the study, reduction factor has been suggested for net-section plastic collapse load of through-wall circumferential crack pipes for different percentages of confidence.

3 illus, 3 tables, 12 ref

006130   Praveen K V U;Singh V (Cent of Advance Study Dep of Metall Engng, Inst of Technol Banaras Hindu Univ, Varanasi-221 005, Email: vakil@banaras.ernet.in) : Effect of alloying on ductility and low cycle fatigue behaviour of Ti, Ni and Fe based aluminides. Trans Indian Inst Metals 2005, 58(2-3), 241-7.

Aluminides of Ti, Ni and Fe are ordered intermetallics and possess many attractive properties for high temperature application. Aluminides with high Al content like TiAl, NiAl and FeAl have relatively lower density, better oxidation resistance and superior mechanical properties than their counterparts with lower Al content (Ti₃Al, Ni₃Al and Fe₃Al). However, in general, aluminides display poor ductility at ambient temperature and even upto their order/disorder transformation temperature. Various attempts have been made to improve ductility of both M₃Al and MA1 type aluminides through different routes. As compared to tensile and creep properties less attention has been paid on the LCF behavior of these aluminides particularly of Ni and Fe based ones. LCF behavior of different types of aluminides is discussed.

^iia1 illus, 1 table, 60 ref

006129   Paradkar A;Nandy T K;Gogia A K;Banerjee D (Defence Metall Res Laboratory, , Kanchanbagh, Hyderabad-500 058, Email: nandy@dmrl.ernet.in) : Effect of quaternary additions on mechanical properties of an (O-B2) alloy. Trans Indian Inst Metals 2005, 58(2-3), 367-72.

Current understanding of the metallurgy of ternary alloys is adequate to attempt a systematic evaluation of quaternary alloying effects, especially in relation to improving creep resistance while retaining the current levels of tensile and fracture properties. This is particularly important since the search for new compositions with superior mechanical properties continues. An effort is therefore made for an enhancement of creep properties by quaternary additions in (O+B2) β system. Based on the previous studies, Ti-24Al-20Nb is chosen as a reference alloy for generating base-line information and studying the alloying effects. Preliminary work in DMRL and information available in the literature suggest that Mo and Zr additions result in high temperature strengthening and enhanced creep properties of conventional titanium alloys. Therefore, the effect of small additions of quaternary elements such as Mo and Zr in an (O+B2) alloy Ti-24Al-20Nb was evaluated for improvement in strength and creep resistance. It is observed that the quaternary additions improve the high temperature strength , decrease the steady state creep rate, 100 hrs strain and primary strain. The results will be discussed and compared with those of recently published literature on similar investigations.

4 illus, 1 table, 16 ref

006128   Pandey R K;Purohit G K;Parmar R S (Dep of Appl Mechanics, Indian Inst of Technol, Hauz Khas, New Delhi-110 016, Email: rkp@am.iitd.ernet.in) : Characterization of fatigue crack initiation and propagation in micro alloyed steel weldments. Trans Indian Inst Metals 2005, 58(2-3), 353-9.

Fatigue initiation and propagation behavior have been studied in a micro-alloyed steel in the parent metal as well as in the weld joint of the steel. The fatigue initiation is studied and compared in terms of a threshold parameter (ΔK/√ρ)_th where ρ is the notch tip radius and ΔK is the stress intensity range at threshold. The fatigue propagation is studied by determining da/dN vs ΔK diagrams and using Paris law. The effect of notch/ crack orientation with respect to stressing axis has been studied on the fatigue initiation and propagation characteristics for the parent metal, weld metal and the HAZ. The role of inclusions, strength properties and microstructure has been discussed.

7 illus, 2 tables, 6 ref

006127   Pandey A K;Adinarayanan K;Chakrabarty S B; Arun Kumar;Sharma S B (Antenna System Grp, Space Applics Cent, Ahmedabad-380 015) : Higher order mode analysis of circular coaxial waveguides using finite difference. Indian J Radio Space Phys 2005, 34(4), 285-8.

Presents a simple technique to evaluate the cut-off wavelengths of circular coaxial waveguides employing the method of finite difference. Curvilinear rectangular meshing has been employed to subdivide the cross-sectional region between the two conductors. Helmholtz equation in polar form is solved with the appropriate boundary condition to evaluate the cut-off wavenumbers and correspondingly the cut-off wavelengths for TE and TM modes. Plots of cut-off wavelengths of few modes for various ratios of outer-to-inner radii are depicted. The data obtained from analytical expressions are compared to justify the validity of the analysis.

3 illus, 1 table, 4 ref

006126   Palani G S;Iyer N R;Dattaguru B (Structural Engng Res Cent, , Chennai-600 112, Email: pal@sercm.csir.res.in) : Fracture analysis of cracked plate panels using NI-MVCCI technique. Trans Indian Inst Metals 2005, 58(2-3), 437-44.

Proposes a numerically integrated modified virtual crack closure integral (NI-MVCCI) technique for fracture analysis of cracked plate panels. NI-MVCCI technique is generalized one and the expressions for computing the strain energy release rate (SERR) are independent of the finite element employed. NI-MVCCI technique has been demonstrated for 4-noded, 8-noded (regular and quarter-point) and 9-noded isoparametric finite elements. Numerical studies on fracture analysis of 2-D crack (mode-I and mode-H) problems have been conducted employing these elements. SERR and stress intensity factors (SIF) have been computed for these problems and found to be in good agreement with the respective analytical solutions available in the literature. The appropriate Gauss numerical integration order to be employed for each of these elements for accurate computation of SERR and SIF has been recommended based on the studies.

5 illus, 2 tables, 10 ref

006125   Narayanan S;Bhaskan U;Jaya K P (Sch of Engng and IT, Univ Malasia Sabah, 88999 Kota Kinabalu, Sabah, Malaysia) : Strength and durability of treated Rubberwood. J Instn Engrs-Pt CI 2005, 86(May), 1-7.

Wood is used for the manufacture of a multiplicity of valuable products. The growing scarcity of wood due to the increased demand has made it prohibitively costly. The use of traditional timber from forests is also non-sustainable. Rubberwood is available from spent rubber trees in plantations in South India, Sri Lanka, Malaysia and other places, The paper presents the results of a study on the strength and durability of treated rubberwood. The durability of rubberwood treated -with different preservatives and physical properties of rubberwood were studied and the results are reported.

2 illus, 6 tables, 23 ref

006124   Nagesha A;Valsan M;Bhanu Sankara Rao K;Kannan R;Mannan S L (Mater Dev Grp, Indira Grandhi Cent for Atom Res, Kalpakkam-603 102, Email: nagesh@igcar.ernet.in) : Thermomechanical fatigue behaviour of type 316L(N) austenitic stainless steel. Trans Indian Inst Metals 2005, 58(2-3), 373-8.

In-phase (IP) and out-of-phase (OP) thermomechanical fatigue (TMF) tests were carried out on a 316L(N) austenitic stainless steel on cylindrical hollow tubular samples using different mechanical strain amplitudes in the range, ± 0.25% to ± 0.6% at a constant strain rate of 6.4 x 10^-5 s^-1. The temperature cycles employed consisted of two different categories namely (a) an identical temperature range with increasing peak temperature (573-823, 623-873 and 673-923 k) and (b) a constant peak temperature with increasing temperature range (673-873, 623-873, 673-923 and 623-923 K). In- phase and out of phase tests yielded a compressive and a tensile mean stress, respectively. The TMF life was seen to decrease with increasing peak and mean temperatures of thermal cycling. Further, lives under OP cycling were found to be lower than those under IP conditions in the low temperature regimes, while the converse holds good when the upper temperature encompassed the creep-dominant regime. Influence of creep on the TMF damage was evident in the form of extensive intergranular cracking in the 673-923 K IP test. The isothermal tests conducted at the peak temperatures of the thermal cycles displayed lower lives compared to both the IP and the OP cycling. Detailed metallographic and fractographic studies were conducted to understand the behaviour of the material under TMF conditions.

6 illus, 1 table, 13 ref

006123   Nagalakshmi R;Dhanasekaran N;Suresh S (NO, , ) : Correlation of material microstructure with ultrasonic characteristics. WRI Jl 2005, 26(1), 13-18.

Ultrasonic testing is finding increased application in various industries and is a versatile NDT method, which is applicable to most materials, metallic or non-metallic materials. Ultrasonic inspection can be used to detect flaws in cast and weld parts, during production, development, service and research. Several wave modes such as Longitudinal, Transverse, Surface and Lamb waves can be used depending on the nature of dislocation. Different techniques such as Pulse echo method, Through Transmission method and Resonance method can be employed. The investigation has been undertaken to determine the relation between ultrasonic properties of a metal and its microstructure. Study has been made on various ferrous materials namely, Carbon steel, Austenitic stainless steel, Martensitic stainless steel and Ferritic stainless steel to establish a relation between ultrasonic parameters and their microstructures. Both Longitudinal wave and Pulse Echo method were used. Experiments were carried out using Barium Titanate, B4S normal probe with 4 MHz frequency. It was observed that the velocity of CS increases when the specimen was heated to 600 deg.C. and also the effect of heat treatment on velocity of different materials is different. Similarly it was seen that there were many changes in microstructure before and after heat treatment. Correlation were made between the change in ultrasonic velocity with that of microstructural changes to predict the 8 microstructure by NDT in the most difficult environment/components.

10 illus, 12 ref

006122   Mulgaonkar M S (NO, , 9, Ameya Apartment, Shreesh Society Hajuri Road, Thane W. 400 062) : Studies on dermal anatomy of three corticolous orchids from India. Mendel int J 2005, 22(3-4), 105-6.

In investigation it has been observed that stomata are paracytic. Stomata are slightly raised in Dendrobium, transparens Wall. ex. Lindl; and Vanda tessallata (Roxb) Hook. f. ex. G. Don but flushed in Cottonia pedunulans 7 (Lindl). Reich, f. Hypostomatic condition has been observed in Dendrobium transparens Wall. ex. lindl; and Cottonia peduncularis (Lindl). Reich, f. whereas amphistomatic condition has been observed in Vanda tessallata (Roxb.)

3 illus, 9 ref

006121   Mishra R;Vaze K K;Kushwaha H S (Reactor Saf Div Hall No.7, Bhabha Atom Res Cent, Mumbai-400 085, Email: rmishra@magnum.barc.ernet.in) : Fatigue life evaluation of the piping systems for the life extension of heavy water plant, Kota. Trans Indian Inst Metals 2005, 58(2-3), 393-8.

Heavy Water Plant, Kota commissioned in 1985, is nearing completion of its originally postulated design life. Exercises have been performed to carry out fatigue life evaluation to assess the remaining fatigue life of the piping components with the aim to extend the life of the plant. Considering process parameters and past history of the plant performance, process critical piping systems connected with 25 equipment nozzle locations were identified for this task. Static analyses were carried out to find out the induced stress levels as per the design code. A few locations where results showed high stress due to the sustained loadings were suggested to keep under constant monitoring. Fatigue life evaluation has been carried out for the locations where high thermal stresses were observed. Details the strategy adopted for fatigue life evaluation and life extension of the piping systems of the plant alongwith a few typical case studies.

3 illus, 3 tables, 2 ref

006120   Mathew M D;Latha S;Bhanu Sankara Rao K;Mannan S L (Indira Gandhi Cent for Atom Res, , Kalpakkam-603 102, Email: mathew@igcar.ernet.in) : Creep strengthening of type 316 stainless steel weld metal by nitrogen. Trans Indian Inst Metals 2005, 58(2-3), 269-73.

Creep properties of type 316 stainless steel weld metal were studied using nitrogen-free and 0.07 wt% nitrogen-Dearing electrodes. Creep tests were carried out in the temperature range 823 - 923 K and rupture lives upto 20,000 hours. Nitrogen-alloyed weld metal showed lower steady state creep rate, higher rupture life and lower rupture ductility as compared to nitrogen-free weld metal. Increase in creep resistance of the nitrogen-alloyed weld metal has been attributed to strengthening of the austenite matrix by nitrogen through solid solution strengthening and decrease in stacking fault energy. Decrease in rupture ductility is mainly attributed to transformation of delta-ferrite into intermetallic phases. The role of nitrogen on creep deformation, fracture, and delta-ferrite phase transformation behaviour are rationalised on the basis of the microstructural observations.

4 illus, 1 table, 9 ref

006119   Mannan S L;Bhanu Sankara Rao K;Valsan M; Nagesha A (Mater Dev Grp, Indira Gandhi Cent for Atom Res, Kalpakkam-603 102, Email: mannan@igcar.ernet.in) : Strain controlled low cycle fatigue and creep-fatigue interaction behaviour of modified 9Cr-1Mo ferritic steel. Trans Indian Inst Metals 2005, 58(2-3), 159-68.

Influence of temperature, strain rate and hold time on the low cycle fatigue (LCF) behaviour of a modified 9Cr-1Mo ferritic steel in the normalized and tempered condition is reported. Total axial strain controlled LCF tests were conducted at strain rates in the range Sx10^-4 s^-1 to 3x10^-2 s^-1 at different strain amplitudes varying from ±0.25 to ±1.0% and hold times up to 30 min. in peak tension over temperatures in the range 300 to 873 K. The cyclic stress response behaviour, in general, showed an initial brief hardening for the first few cycles, followed by a gradual and continuous softening regime. The fatigue failure at high strain amplitudes and high strain rates of testing was marked by extensive crack branching and formation of secondary cracks. Oxidation-assisted crack initiation and propagation contributed to life reduction at high temperatures and low strain rates. Fatigue life was found to decrease with increase in the duration of hold time in tension. The data generated is compared with that from the literature and also with the best-fit and design curves from the RCC-MR code.

11 illus, 3 tables, 31 ref

006118   Maile K;Klenk A (MPA Stuttdart, , Pfaffenwaldring 32, D-70569 Stuttgart, Germany, Email: karl.maile@mpa.uni-stuttgart.de) : Experimental and numerical investigations of welt and repair weld behaviour. Trans Indian Inst Metals 2005, 58(2-3), 413-21.

To increase efficiency of fossil fired power plants, the process parameters, in particular the temperature, have been increased more and more. The newly developed 9 Cr and 10 Cr steels opened the way for this development. Subsequently there is a strong need to know the long time behaviour of weldments in components. Due to the different material properties in the different zones (heat affected zones, weld metal and base metal) stress redistribution, strain and damage behaviour and location is complicated. A change in fracture location from weld metal to fine grained heat affected zone is usually observed. Numerical simulation of weldments was used to investigate local stress state and deformation which can be correlated to damage behaviour and location. To develop engineering assessment methods for welds and repair welds reliable design and calculation tools are necessary. To enable numerical simulation of welded and repair welded components geometrical and material models were developed. Methods for geometrical modelling of partly and fully repaired welds and material have been investigated. Crossweld tests were simulated to validate the models. To determine the material behaviour of the welds a number of creep tests on laboratory specimens have been carried out. Feature tests with pipes and T-pieces with different weld and repair weld configurations will be simulated in order to support the development of lifetime assessment methods for welded and repair welded components.

13 illus, 11 ref

006117   Madheswaran C K;Thandavamoorthy T S;Natarajan K;Sundaravadivelu R;Boominathan A (Structural Engng Res Cent, , Taramani, Chennai-600 113) : Ground and structural vibrations during driving of concrete and steel piles. J Instn Engrs-Pt CI 2005, 86(May), 28-33.

The paper discusses the ground and structural vibrations during driving of concrete and steel piles. Pile driving creates vibrations and may cause damage to nearby structures and structural components. Still, there is no method of quantitative calculation of piling vibration response. Estimation of amplitudes and frequencies of vibration are based on experience and site testing. Therefore, in order to characterise the ground vibration due to piling, using different pile materials experimental investigations to measure ground vibration generated due to driving of reinforced concrete pile of 48 mm φ as well as steel pile of 45 mm φ were carried out in the laboratory. Four reinforced concrete piles of 48 mm φ were designed and cast. The length of concrete pile was 600 mm. Similarly, four steel piles of 45 mm φ and 600 mm length were also fabricated. The soil at the site was very soft clay. The effects of ground vibration due to driving of reinforced concrete and steel piles on steel frames were also measured. Paper presents the details of experimental testing, instrumentation, collection of vibration data, acquisition and processing of recorded signals using PC-based data acquisition system. The time-histories and spectra of ground and structural accelerations are presented. A comparison of the ground vibration generated by driving of both types of piles is made, appropriate inferences are drawn and pertinent conclusions are presented.

12 illus, 4 ref

006116   Madheswaran C K;Sundaravadivelu R;Boominathan A;Natarajan K (Structural Envineering Res Cent, , Taramani, Chennai-600 113) : Response of ground during pile driving. J Instn Engrs-Pt CI 2005, 86(May), 22-7.

The paper describes the details of numerical investigations on ground accelerations due to pile driving. The study of pile driving by PLAXIS software is carried out using 15 noded axisymmetric finite-element mesh to discretise the pile-soil system. The diameter of pile is 0.6 m and length 16.2 m. The behaviour of sand layer is modelled by means of the hardening soil model considering a depth of 80 times the diameter of the pile. The steel pile is modelled by means of the linear elastic model considering non-porous behaviour. The measurement of ground and structural vibrations during prototype pile driving is carried out at a site in Chennai. The time histories of vertical and longitudinal ground acceleration obtained from PLAXIS are compared with the experimental results.

11 illus, 8 ref

006115   Latha S;Mathew M D;Bhanu Sankara Rao K;Mannan S L (Mater Dev Grp, Indira Gandhi Cent for Atom Res, Kalpakkam-603 102, Email: slatha@igcar.ernet.in) : Thermal creep properties of alloy D9 fuel clad tubes of fast breeder reactor. Trans Indian Inst Metals 2005, 58(2-3), 343-6.

Uniaxial thermal creep rupture properties of 20% cold worked alloy D9 fast reactor fuel clad tubes have been evaluated at 973 K in the stress range of 125 to 250 MPa. The results are compared with existing data on 20% cold worked type 316 stainless steel cladding tubes. Alloy D9 exhibited lower minimum creep rates, higher rupture lives and lower rupture ductilities at all the stress levels.

5 illus, 1 table, 12 ref

006114   Laha K;Chandravathi K S;Bhanu Sankara Rao K; Mannan S L (Mater Dev Grp, Indira Grandhi Cent for Atom Res, Kalpakkam-603 102, Email: klaha@igcar.ernet.in) : Creep behaviour of modified 9Cr-1Mo forged steel and its weld joint. Trans Indian Inst Metals 2005, 58(2-3), 379-85.

Creep deformation and fracture behavior of modified 9Cr-1Mo (grade 91) forged steel and its fusion-welded joints have been studied at 823, 873 and 923 K over a stress range of 80 - 300 MPa. The weld joint at all the test temperatures possessed lower creep rupture strength than the base metal, except at higher applied stresses at 823 K and 873 K. The magnitude of the reduction in creep strength of the weld joint compared to the base metal increased with the increase in testing temperature and decrease in applied stress. Microstructure and micro hardness of the weld joints were evaluated in the as welded, post weld heat-treated and creep tested conditions. A hardness trough was observed in the intercritical region (ICR) of the heat-affected zone. The recovery of the substructure and coarsening of intragranular carbides and carbonitrides led to lower hardness in the intercritical heat affected zone (HAZ) of the joints contributing to lower creep strength. The creep failure in the ICR has been found to be associated with intergranular cavitation.

10 illus, 3 tables, 12 ref

006113   Kushwaha H S;Dutta B K;Samal M K (Reactor Saf Div, Bhabha Atom Res Cent, Trombay, Mumbai-400 085, Kushwaha@magnum.barc.ernet.in) : Structural integrity assessment of components operating at high temperature. Trans Indian Inst Metals 2005, 58(2-3), 221-32.

For the remaining life assessment of components in a plant that operates in the creep range under cyclic loading, creep-fatigue interaction phenomena is one of the most important considerations. Hence, a prediction method for the accumulation of damage due to creep and fatigue during the operating life of the component is necessary. The objective is to describe the conventional and fracture mechanics based methods for creep and fatigue damage assessment of high temperature components. A number of codes existing worldwide for such an assessment have been reviewed. As a case study, the hot reheat pipe bend (elbow) of a thermal power plant was selected. The operating temperature for the elbow is 813 K and it is subjected to 3.5 MPa of internal pressure for full power operation. The moments and forces acting on the elbow are calculated by taking into account all piping loads due to thermal and dead loads. Circumferential and longitudinal part-throughwall semi-elliptical cracks (internal and external) at intrados and crown are postulated. The nominal stresses of the elbow are calculated using BARC in-house FEM code MADAM. The stress intensity factors and limit loads of the corresponding cases are calculated using the RCC-MR AI6 and API procedures. The damage due to creep is evaluated using reference stress method of R5 and API codes. The crack growth rates for various crack configurations were compared. It was observed that the stress intensity factors and crack growth rates are higher for longitudinal part-through cracks and R5 provides a conservative estimate of remaining life of the component compared to API.

20 illus, 11 ref

006112   Krishnapur P P;Sagayaraj R;Khodwe A M;Padaki V C (Defence Bioengineering and Electromedical Laboratory, , C V Raman Nagar, Bangalore-560 093) : An embedded system design for use in oxygen generating system. J Instrum Soc India 2005, 35(3), 292-303.

An embedded system is designed and developed with INTEL'S 8OC196KB micro-controller for operating the Molecular Sieve Oxygen Generating System (MSOGS) which comprises of two zeolite beds pressurized and depressurized alternatively using two solenoid valves. The embedded system monitors the health of these two solenoids and also controls the temperature of the Oxygen sensor at 650°C ± 3°C in addition to sensing of temperature and monitoring the emf generated by the Oxygen sensor which is of solid state electrolyte viz. Zirconia type. It also monitors the pressure of the backup oxygen source of the total Oxygen system and issues warning signal to the pilot, if the pressure of the backup Oxygen source falls below 50 bar. The system also communicates with the master through the RS-422 interface to exchange data. The unit in addition has the provision to sense the status of sensors such as temperature & pressure and also to indicate the status of loads viz. as solenoids and heater. The provision is also made to sense high priority switch for selecting 100% Oxygen source. Paper describes 80C196 KB micro-controller based embedded system used for operating the oxygen generating system which has immense use in the hospitals also. The circuit details of analogue and digital channels employed are given. The software developed to operate the whole system is resident in the EPROM The data failure on sensors or loads is stored in EEPROM and can be downloaded for analysis.

8 illus, 8 ref

006111   Krishnamoorthy;Rao N B S;Rao N (Dep of Civil Engng, Manipal Inst of Technol, Manipal-576 104) : Analysis of group of piles subjected to lateral load. Indian Geotech J 2005, 35(2), 154-76.

8 illus, 20 ref

006110   Koul S;Adedao O (Dep of Electl and Computer Engng, Univ of Waterloo, 200 University Avenue West, Waterloo, Ont., Canada N2L3GI, Email: skoul@venus.uwaterloo.ca) : Dopant structure and sensing behaviour of conducting polyaniline : a comparative study for the design of chemical sensors. Asian J Phys 2005, 14(1-2), 71-8.

Reports about the different sensing behaviours in correlation with the presence of different dopant anionic structures. The change in resistance value for conducting polyaniline in presence of three different dopant structures on exposure to different concentrations of aqueous ammonia shows its fast selectivity and validation as a sensor material. A detailed response behaviour accompanied by a change in morphological features shows a strong correlation between the sensing mechanism and selectivity of analyte as a dopant structure at a molecular level. A significant difference in the morphology of a polyaniline in presence of different dopant moieties on exposure to similar concentrations of aqueous ammonia solution proves the difference in sensing behaviour accompanied by a well defined mechanism for each system.

5 illus, 26 ref

006109   Klenk A;Schemmel J;Maile K (MPA Stuttgart, , Pfaffenwaldring 32, D-70569 Stuttgart, Germany, Email: andreas-klenk@mpa.uni-stuttgart.de) : Modelling deformation and damage of high temperatures steels under creep-fatigue loading. Trans Indian Inst Metals 2005, 58(2-3), 481-7.

The deformation and damage under uniaxial and multiaxial testing conditions has been characterised by conducting tests at 823 K and 873 K on a 10CrMoWVNbN steel. The material behaviour was modelled using visco-plastic material models and validated with the experimental data.

10 illus, 1 table, 8 ref

006108   Khandelwal M;Singh T N;Kumar S (Earth Sci, II Technol, Bombay, Powai, Mumbai-76) : Evaluation of blast induced ground vibration in surface mine. Indian Min Engng J 2005, 44(7-8), 27.

Paper presents the application of neural network for the prediction of ground vibration by taking into consideration of maximum charge per delay and distance between blast face to monitoring point. To investigate the appropriateness of this approach, the predictions by ANN have been also compared with USBM predictor equation. Network is trained by 32 dataset with 700 epochs and tested it by 10 dataset. Field investigation has been carried out at Magnesite mine of Pithoragarh. The correlation co-efficient determined by ANN is 0.9072 and Mean Absolute Percentage Error (MAPE) is 28.68 for predicted PPV while correlation co-efficient by USBM equation is 0.6438 and MAPE is 36.27.

6 illus, 1 table, 20 ref

006107   Kashyap B P;Toppo S P;Garg A (Dep of Metall Engng and Mater Sci, Indian Inst of Technol, Bombay, Mumbai-400 076, Email: bpk@met.iitb.ac.in) : Cavitation and grain growth during superplastic deformation and their correlation with flow behaviour. Trans Indian Inst Metals 2005, 58(2-3), 169-76.

Grain growth, cavitation and flow stress data, which are available together for limited materials during superplastic deformation, were collected and analyzed to explore the interdependence in microstructural changes and its impact on flow properties. The grain size (d_g) varies with strain (∈) as d_g ∝ ε^c, c being strain exponent, whereas cavity volume (C_v) follows C_v = Aε² + Bε + C type polynomial relationship, where A, B and C are coefficients. The interrelationship between C_v and d_g can be expressed by: C_v ∝ exp (d_g). While flow hardening is attributed to grain growth in the early part of deformation, the occurrence of cavitation is found to cause flow softening at later stage of deformation.

5 illus, 2 tables, 29 ref

006106   Karthigeyan A;Gupta R P;Eisele I (Cent Electron Engng Res Inst, , Pilani-333 031, Email: karthig@ceeri.ernet.in) : Low temperature gas sensing characteristics of Pt doped nano-particulate SnO₂ film in HSGFET sensor. Asian J Phys 2005, 14(1-2), 129-38.

The purpose of investigation is to study the effect of platinum on gas sensing properties of nano-particulate SnO₂ films. Nano-particulate film of SnO₂, prepared by a simple technique, was covered by an ultra thin film (<126> 5 nm thickness) of platinum. The platinum coated SnO₂ film was then annealed at 800°C in air to obtain platinum doped SnO₂ (Pt/SnO₂) film. The gas sensing characteristics of pure SnO₂ and Pt/SnO₂ films were determined by integrating them in HSGFET (Hybrid Suspended Gate Field Effect Transistor) structure. Sensor response to different concentration of reducing (H₂, NH₃, CO) and oxidizing (NO₂, SO₂ C_l2) gases was measured at room temperature and at 100°C. The results indicate that at room temperature (30°C) the response of pure SnO₂ film to test gases was poor and did not produce useful signal. However, it produces large signal to oxidizing gases at 100°C. Pt/SnO₂ film was found to be highly sensitive to H₂ with fast reaction and recovery times at room temperature. Interestingly it exhibited poor response to both other two reducing gases i.e. CO and NH₃ at room temperature as well as at 100°C. Pt/SnO₂ film at room temperature showed no signal to oxidizing gases, but at 100°C these gases produce a significant signal. A detailed discussion on possible mechanisms is presented to understand the effect of platinum doping in nano-particulate SnO₂ film.

6 illus, 32 ref