006305   Lin-Quan L;Qi-Long Y;Zheng Y;Zhen-Wei S; Jun-Qiang L;Liu P (College of Astronautics, Northwestern Polytechnical Univ, Xi'an, China-710 002, Email: terry.well@163.com) : Thermal decomposition mechanism of particulate core-shell KC1O₃-HMX composite energetic material. Indian J Engng Mater Sci 2011, 18(5), 393-8.

Thermal decomposition mechanism of a newly designed composite material KC1O₃-HMX (KC-HMX) is investigated by combined TG-DSC-FTIR technique and T/Jump in-situ thermolysis cell/FTIR (T/Jump FTIR) technique. It is shown that KC-HMX began to decompose at about 266°C without melting, and the fast stage of mass loss at the temperature range of 268.4-290.1 °C is considered to be the result of the thermolysis and complex reactions of KC1O₃ and HMX with energy release of 1859 J.g^-1, which exceeded that of pure HMX about 40%. It is also shown that CO, CO₂, NO₂ and H₂O were the main gaseous products. The T/Jump FTIR analysis showed that the competing reactions of N-N and C-N bonds cleavage occurred in initial stage of HMX decomposition are greatly affected by KC1O₃. In contrast of pure HMX. there is no CH₂O and HCN detected in its thermolysis products. In presence of electronegative oxygen radical produced by thermolysis of KC1O₃ oxidized CH₂O and HCN through gas-phase reaction "(NO₂+4O₂) + (2N₂O+5CH₂O) → 5NO+3CO+2CO₂+5H₂O", which is probably the dominating reaction, being immediately followed by the decomposition reaction of HMX.

7 illus, 13 ref

006304   Khot S A;Sane N K;Gawali B S (NO, Latthe Education Society's Polytechnic, P-41, M.I.D.C. Kupwad, Sabgli-416 436, Email: sakhot_2000@yahoo.com) : Thermal energy storage using PCM for solar domestic hot water systems. J Instn Engrs: Ser C 2012, 93(2), 171-6.

Thermal energy storage using phase chase materials (PCM) has received considerable attention in the past two decades for time dependent energy source such as solar energy. From several experimental and theoretical analyses that have been made to assess the performance of thermal energy storage systems, it has been demonstrated that PCM-based systems are reliable and viable options. This paper covers such information on PCMs and PCM-based systems developed for the application of solar domestic hot water system. In addition, economic analysis of thermal storage system using PCM in comparison with conventional storage system helps to validate its commercial possibility. From the economic analysis, it is found that, PCM based solar domestic hot water system (SWHS) provides 23% more cumulative and life cycle savings than conventional SWHS and will continue to perform efficiently even after 15 years due to application of non-metallic tank. Payback period of PCM-based system is also less compared to conventional system. In conclusion, PCM based solar water heating systems can meet the requirements of Indian climatic situation in a cost effective and reliable manner.

^iia6 illus, 1 table, 13 ref

006303   Khedle R;Mondal D P;Verma S N;Panthi S (Mechanical Engineering Dep, Rajiv Gandhi Prodyogiki Vishwavidyalaya, Air Port Road, Bhopal-462 003, Email: raghvendra056@yahoo.com) : FEM modeling of compressive deformation behaviour of aluminum cenosphere syntactic foam (ACSF) under constrained condition. Indian J Engng Mater Sci 2012, 19(2), 135-43.

The deformation behavior of aluminum cenosphere syntactic foam (ACSF) as a function of porosity, shell thickness, shell volume fraction and cenosphere volume fraction has been studied using finite element modeling of a representative unit cell of the respective material under both constrained and unconstrained conditions. The volume fraction of cenosphere and its shell thickness varies from 5% to 65% and 1 μm to 4 μm, respectively. It has been noted that as cenosphere volume fraction decreases, the plateau stress and Young's modulus of these materials increases. While these values increase with increase in the shell thickness, i.e., shell volume fraction. The modulus and plateau stress increase considerably under constrained condition especially at low cenosphere volume fraction. The FEM predicted values are validated with experimental results and it is noted that the FEM predicted values are within the 12% variation of the experimental values. The proposed study thus shows that unit representative shell techniques are reasonably ideal and rapid method for predicting compressive deformation behavior of ACSF.

9 illus, 2 tables, 14 ref

006302   Kehra B S;Pharwaha A P S (CSE Dep, BBSB Engineering College, Fatehgarh Sahib-140 407, Email: baljitkhehra@rediffmail.com) : Integration of fuzzy and wavelet approaches towards mammogram contrast enhancement. Res Rev : J Oncol Hematol 2012, 93(2), 101-10.

Mammography is the most reliable, effective, low cost and high sensitive method for early detection of breast cancer. In breast cancer diagnosis, it is difficult for radiologists to detect the typical diagnostic signs because mammograms are low contrast and noisy images. In order to improve diagnosis accuracy, mammogram contrast enhancement technique is often used to enhance the contrast of mammogram and aid the radiologists. In this paper, a combined approach with fuzzy and wavelet towards improved enhancement of details and subtle features in digital mammogram images. The proposed contrast enhancement approach utilizes wavelet transform to decompose the mammogram, and then approximation coefficients are modified by fuzzy contrast enhancement approach and detail coefficients are by non-linear transformation. After that, inverse wavelet transform is applied on modified coefficients to obtain the enhanced mammogram. The proposed algorithm has been tested on a number of images in Digital Database for Screening Mammography (DDSM), comparing the results with histogram equalization which is a well-established image enhancement technique and Cheng's enhancement algorithm based on wavelet transform. In order to accurately assess the proposed approach, enhanced mammogram images are evaluated through objective image quality assessment parameters: information entropy, contrast and peak signal-to-noise ratio (PSNR). Experimental results of the proposed approach are quite promising.

5 illus, 3 tables, 27 ref

006301   Kamanli M;Yasar Kaltakci M;Bahadir F;Balik F S;Husnu Korkmaz H;Sami Donduren M;Tolga Cogurcu M (Civil Engineering Dep, Selcuk Univ, Konya, Turkey, Email: sdonduren@selcuk.edu.tr) : Predicting the flexural behaviour of reinforced concrete and lightweight concrete beams by ANN. Indian J Engng Mater Sci 2012, 19(2), 87-94.

In this study, artificial neural network (ANN) method is used to predict the deflection values of beams and compared with the experimental results of a testing series. For this purpose six reinforced concrete beams with constant rectangular cross-section are prepared and tested under pure bending. The concrete of the test specimens is casted using the lightweight aggregates obtained from volcanic sediments. The lightweight concrete has some advantages comparing the traditional concrete, such as less self weight, less earthquake forces due to decreased mass, good sound and thermal insulation. The use of lightweight concrete in the construction industry is popular due to various advantages. The neural network procedure is applied to determine or predict the deflection values of 1/1 scaled model beams. The analytical results are compared with the test results and further predictions, including different mix designs can be possible at the end of the study. As a result, while the statistical values RMSE, R² and MAE from training in ANN model are found as 0.266, 99.2% and 0.216, respectively, these values are found in testing as 0.370, 96.47% and 0.419, respectively.

14 illus, 5 tables, 41 ref

006300   Kalanad A;Rao B N (Structural Engineering Div, Indian Institute of Technology, Madras, Chennai-600 036, Email: bnrao@iitm.ac.in) : Two-dimensional elastic-plastic cracked finite element for fracture applications. Indian J Engng Mater Sci 2012, 19(2), 95-16.

In this paper a novel two-dimensional finite element with a single, non-propagating, open embedded edge crack is developed based on elastic-plastic fracture mechanics. The influence of crack on the local flexibility of the structure is accounted for by the reduction of the element stiffness as a function of the crack length, instead of physically modeling the crack within the element. The proposed element accounts the influence of crack tip plasticity, at the cracked cross-section. The components of the stiffness matrix for the proposed cracked element are derived based on the Castigliano's first principle. The element is implemented as a user element (UEL) subroutine in ABAQUS. The proposed element can be applied in a wide range of fatigue and fracture applications in order to determine changes in static, dynamic, and stability characteristics of cracked structures.

16 illus, 18 ref

006299   Jain M;Sharma G C;Ram Singh (NO, Indian Institute of Technology, Roorkee, Email: singh_ram2008@hotmail.com) : Mathematical and computational modeling of plasma concentration after oral drug administration with chemical reactions. Int J Inf Comput Sci 2011, 14(1), 22-30.

Flux averaged concentration associated with convection-dispersion equation has been mostly used for the mass or solute transport problems. In this investigation, a pharmacokinetic model has been developed to study the transport of drug in body after oral administration. To analyze the drag concentration and flux averaged concentration in blood plasma convection-dispersion equation has been solved by using analytical solution method which includes Laplace transform. Chemical reactions play an important role in the transport of drug in GI tract. To explore the effects of chemical reactions in the transport of drag, chemical reaction coefficient has been incorporated. Sensitivity analysis has also been performed to validate the analytical results by taking numerical illustration.

2 illus, 20 ref

006298   Jacob K T;Rajitha G;Dasgupta N (Materials Engineering Dep, Indian Institute of Science, Bangalore-560 012, Email: katob@materials.iisc.ernet.in) : Electrical conductivity of Ca-doped YFeO₃. Indian J Engng Mater Sci 2012, 19(1), 47-53.

Electrical conductivity and Seebeck coefficient of calcium-doped. YFeO₃, a potential cathode material in solid oxide fuel cells (SOFC), are measured as function of temperature and composition in air to resolve conflicts in the literature both on the nature of conduction (n- or p-type) and the types of defects (majority and the minority) present. Compositions of Y_1- Ca_x FeO_3-δ with x = 0.0, 0.025, 0.05 and 0.1 are studied in the temperature range from 625 to 1250 K. All Y_1-x Ca_xFeO_3-δ samples show p-type semiconducting behaviour. Addition of Ca up to 5% dramatically increases the conductivity of YFeO₃; increase is mere gradual up to 10%. A second phase Ca₂Fe₂O₅ appears in the microstructure for Ca concentrations in excess of 11%.

8 illus, 7 ref

006297   Ismail A E;Ariffin A K;Abdullah S;Ghazali M J (Engineering Mechanics Dep, Faculty of Mechanical & Manufacturing Engineering, Tun Hussein Onn Mal, 86400 Batu Pahat, Johor, Malaysia, Email: emran@uthm.edu.my) : Stress intensity factors under combined tension and torsion loadings. Indian J Engng Mater Sci 2012, 19(1), 5-16.

This paper numerically discusses the stress intensity factor (SIF) calculations for surface cracks in round bars subjected to combined loadings. Different crack aspect ratios, a/b ranged from 0.0 to 1.2 and the relative crack depth, a/D in the range of 0.1 to 0.6 are considered. Since the loading is non-symmetrical, the whole finite element model is constructed. Then, both tension and torsion loadings are remotely applied to the finite element model and the SIFs are determined along the crack front of various crack geometries. An equivalent SIF method is then explicitly used to combine the individual SIF obtained using different loadings. A comparison is made between the combined SIFs obtained using the equivalent SIF method and finite element analysis (FEA) under similar loadings. It is found that the equivalent SIF method successfully predicted the combined SIF for Mode I. However, discrepancies between the results, which have been determined from the different approaches, occurred when F_III is involved. Meanwhile, it is also noted that the predicted SIF using FEA is higher than the predicted through the equivalent SIF method due to the crack face interactions.

16 illus, 4 tables, 30 ref

006296   Gao G L;Shi D Q;Li D Y;Dong J W;Shi X D (Material Science and Engineering Dep, Communications Engineering, Harbin Science and Technology Univ, Harbin-150 040, China, Email: gaoguili99@yahoo.com.cn) : Experimental study on fatigue crack identification of 7075 aluminium alloy plate using combination NEWMS and TRA. Indian J Engng Mater Sci 2011, 18(5), 377-80.

According to nonlinear elastic wave modulation spectroscopy (NEWMS) and time reversal acoustic (TRA), a system is constructed to study the fatigue crack in 7075 aluminium alloy plate. Using different frequency excitation source (f₁=270 kHz and f₂=70 kHz), two types of samples, one is with the crack and the other is without the crack, are comparatively experimented. Intermodulation components (f₊=f₁ +f₂, f_-= f₁-f₂) around the fatigue crack are analyzed. The experimental results show f_± can be used to indicate the presence of the crack. The two-dimensional contour plot of the energy from the sample surface amplitude can be used to locate the crack position.

4 illus, 13 ref

006295   Ergun E;Tasgetiren S;Topcu M (Mechanical Engineering Dep, Pamukkale Univ, Denizli, Turkey, Email: eminergun@pau.edu.tr) : Stress intensity factor estimation of repaired aluminium plate with bonded composite patch by combined genetic algorithms and FEM under temperature effects. Indian J Engng Mater Sci 2012, 19(1), 17-23.

The finite element method (FEM) is used to analyze the behavior of repaired cracks in 2024-T3 aluminum with bonded patches made of unidirectional composite plates. Different plate thicknesses, number of patch layers, temperatures and crack lengths are considered in the analyses. Firstly, the K_I stress intensity factor (SIF) is calculated by the finite element method using displacement correlation technique. Secondly, non-linear estimation models are developed using genetic algorithms (GA). The developed models are validated with experimental and numerical data. A genetic algorithm patch design (GAPD) is developed to estimate the stress intensity factor without any further finite element analysis.

8 illus, 5 tables, 26 ref

006294   Edwin Raja Dhas J;Kumanan S (Automobile Engineering Dep, Noorul Islam Univ, Nagercoil-629 180, Email: edwinrajadhas@rediffmail.com) : Weld residual stress prediction using artificial neural network and fuzzy logic modeling. Indian J Engng Mater Sci 2011, 18(5), 351-60.

Artificial intelligent tools such as expert systems, artificial neural network and fuzzy logic support decision-making are being used in intelligent manufacturing systems. Success of intelligent manufacturing systems depends on effective and efficient utilization of intelligent tools. Weld residual stress depends on different process parameters and its prediction and control is a challenge to the researchers. In this paper, intelligent predictive techniques artificial neural network (ANN) and fuzzy logic models are developed for weld residual stress prediction. The models are developed using Matlab toolbox functions. Data set required to train the models are obtained through finite element simulation. Results from the fuzzy model are compared with the developed artificial neural network model, and these models are also validated.

11 illus, 3 tables, 28 ref

006293   Chieh-Jen C;Tseng L;Ta-Sen L;Wei-Jer W; Tzen-Chin L (Civil and Disaster Prevention Engineering Dep, National United Univ, Miaoli, Taiwan, Email: ltc6@nuu.edu.tw) : Recycling of modified MSWI ash-mix slag and CMP sludge as a cement substitute and its optimal composition. Indian J Engng Mater Sci 2012, 19(1), 31-40.

Modified municipal solid waste incinerator (MSWI) ash-mix slag and chemical mechanical polishing (CMP) sludge are recycled together to partly replace cement in cement mortars. The main objective of this study is to fully reuse scrubber ash and fly ash from an MSWI, improve their compressive strengths, and then acquire their optimal composition through the design of experiments (DOE) and analysis of variance (ANOVA). Four control factors, including (i) cementitious usage, (ii) modified ash-mix slag substitute, (iii) water-to-cementitious ratio and (iv) CMP sludge, each of which are substituted with three levels, are considered to investigate the optimal parameter settings. The ANOVA analysis indicates that the first three factors are significant and strongly affect the compressive strength of the mortar samples. The reliability of the experiments and the rationality of the variances fall within a confidence level of 95%, indicating that the design for the composite cement mortars is robust. The reconfirmation test demonstrates that the compressive strength of the mortar can reach 52.85 MPa (152% of that of plain cement mortar) under the optimal composition (34 wt% of cement replacement). This study reveals that we can fully utilize the fly and scrubber ashes, and the test results confirm the feasibility of substantial cement -replacement with modified MSWI ash-mix slag and CMP sludge.

8 illus, 5 tables, 41 ref

006292   Chand M;Arvind Kumar;Annveer;Sandeep Kumar; Shankar A;Pant R P (NO, CSIR- National Physical Laboratory, DR K S Krishnan Marg, New Delhi-110 012, Email: rppant@nplindia.org) : Investigations on Mn_xZn_1-xFe₂O₄(x=0.1, 0.3 and 03.5) nanoparticles synthesized by sol-gel and co-precipitation methods. Indian J Engng Mater Sci 2011, 18(5), 385-9.

Mn²⁺ substituted Zn ferrite nanoparticles have been synthesized using two different wet methods, sol-gel and co-precipitation. The doping effect of Mn²⁺ ion concentration on physical properties like structural and magnetic properties is investigated. The crystallite size and lattice parameter increases with increasing Mn²⁺ concentration. EPR study reveals that the line width and g-factor increases with increasing Mn²⁺ concentration for co-precipitated particles whereas the reverse trend for sol-gel technique is observed. However, in both the processes the saturation magnetization (M_s) and coercivity (H_c) increase with increasing Mn²⁺ concentration. In a comparative study, the nanoparticles synthesized by sol-gel are more crystalline in nature as compared to co-precipitated particles.

4 illsu, 3 tables, 18 ref

006291   Bhusbur S;Ray S (Electrical Engineering Dep, Bhilai Institute of Technology, Drug, Chandigarh, Email: sbhusnur@yahoo.co.in) : Robust performance of a stable and an unstable interval plant in the two loop model following control structure. Res Rev : J Oncol Hematol 2012, 93(2), 81-90.

The two loop model following control is one of the robust control strategies used in control system design. In this paper the vital features of the two loop control structure are focused that lead to an improved system performance as compared to that of single loop control structure in terms of model output tracking, disturbance rejection and robustness in the presence of plant parameter variations. Also, the conditions that provide robustness to the system are established mathematically. Two examples including an unstable plant are illustrated to give a clear insight to the behavior of the controlled plant in both the control structures and the simulation results support the derived mathematical analysis. The parametric stability margins for the unstable plant using bounded phase condition are also determined. The controller configuration used in this paper can be realized using a four parameter proportional plus derivative plus integral controller.

12 illus, 2 tables, 24 ref

006290   Bhattacharya A;Batish A;Kumar P (Mechanical Engineering Dep, Thapar Univ, Patiala-147 004, Email: abhattacharya@thapar.edu) : Experimental investigation for multi-response optimization of bead geometry in submerged arc welding using grey analysis. J Instn Engrs: Ser C 2012, 93(2), 123-32.

The study was aimed at studying the effect of type and composition of flux, welding current, arc voltage, and travel speed on depth of penetration, bead height and bead width (bead geometry responses) and to optimize the process considering multi-response criteria in a submerged arc welding process. Using the grey relational analysis technique three responses were combined into a single grey relational grade and was analyzed using Analysis of Variance. Since the three responses had conflicting requirements, optimization of the complicated multiple performance characteristics was greatly simplified through this approach. The emperical relationship between the multi-response grey relational grade and the input parameters was developed using regression analysis which was used to predict the value of the grey relational grade using the optimal parameter levels.

5 illus, 10 tables, 20 ref

006289   Barnabas J K;Tamizharasan T (Mechanical Engineering Dep, Anjalai Ammal Mahalingam Engineering College, Kovilvenni, Email: kingstonmech@gmail.com) : Optimization of MQL parameters during turning for the minimization of flank wear using DoE, PSO and SAA. J Instn Engrs: Ser C 2012, 93(2), 133-9.

The concept of minimum quantity lubrication (MQL) has come into practice since a decade ago in order to overcome the disadvantages of flood cooling. This experimental investigation deals with the effects of MQL parameters during turning for the minimization of flank wear with surface roughness as constraint. The parameters of MQL selected are density of coolant, mass flow rate of coolant and pressure of air. The selected MQL parameters are varied through four levels. The flank wear values of the cutting inserts after machining are observed and recorded. The best levels of MQL parameters are identified by using Taguchi's design of experiments. A validation experiment is conducted with the identified best levels of parameters and the corresponding flank wear value is recorded. This analysis further inter-relates the performances of particle swarm optimization and simulated annealing algorithm (SAA). The result obtained from SAA is comparatively better than that of the results obtained from other techniques.

5 illus, 6 tables, 15 ref

006288   Barman S;Sen R (Central Mechanical Engineering Research Institute, Council of Scientific and Industrial Research (CSIR), Durgapur-713 209, Email: sbarman@cmeri.res.in) : Performance evaluation of multi-axis CNC machine tools by interferometry principle using laser calibration system. J Instn Engrs: Ser C 2012, 93(2), 151-5.

Advancement in digital electronics and microprocessors has made the manufacturing sector capable to generate complex components within small tolerance zone in nanometre range at one machining center. All motion control systems have some form of position feed back system fitted with the machine. But the systems are not perfectly accurate due to the errors in the positioning performance of the machine tools which will change over time to time due to wear, damage and environmental effect. The complex structure of multi-axis CNC machine tools produces an inaccuracy at the tool tip caused by kinematic parameter deviations resulting in manufacturing errors, assembly error and quasi-static errors. Analysis of these errors using a laser measurement system provides the user with a way to achieve better accuracy, and hence higher quality output from these processes. In this paper, characteristic of the positioning errors of the axes of multi-axis CNC machine tools and the technique to measure the errors by a laser interferometer calibration system have been discussed and the positioning accuracy of the machine each axis has been verified.

5 illus, 3 tables, 9 ref

006287   Banerjee S;Bhaduri R (Electrical Engineering Dep, National Institute of Technology, QTR No.-DS-8C, N.I.T. Campus, Durgapur-713 219, Email: bansub2004@yahoo.com) : Performance of classical controllers for an electromagnetic levitation system: a comparative study. Res Rev : J Oncol Hematol 2012, 93(2), 91-9.

The electromagnetic levitation system (EMLS) is inherently unstable and strongly non-linear in nature. A linearized model has been developed for the proposed levitated system and different classical controllers have been designed for providing overall closed loop stability as well as satisfactory performance for such an unstable system. The main aim of this part of work is to compare with the different designed controllers for the proposed designed EMLS at different operating points and to suggest a suitable classical controller that will provide fast response without any overshoot and steady-state error which is generally required for such type of critical systems. Experimental comparison of different simulated controllers with the existing prototype has been highlighted.

16 illus, 6 tables, 19 ref

006286   Baby Gayathri S;Kamaraj P (Chemistry Dep, Faculty of Engineering and Technology, SRM Univ, Kattankulathur, Tamil Nadu-603 203, Email: kamaraj97@yahoo.co.in) : Macrophage and osteoblast response to micro and nano hydroxyapatite. Nano Vision 2011, 1(1), 1-13.

Bone is a connective tissue formed by the precipitation of hydroxyapatite crystals on organic matrix. One of the most common illnesses associated with the bone is bone fracture. The use of implant at the affected bone region is found to be associated with several difficulties especially due to the activity of macrophage and osteoblast at the implanted site. Osteoblasts are specialized fibroblast-like cells associated with the formation of bone and macrophages, members of host immune system. Orthopedic surgery is known to trigger a wound healing response at the implanted site by activation of numerous immune cells long before osteoblasts arrive. Unique higher surface area, surface roughnesses, altered electron distribution and energetics of nano-hydroxyapatite have altered the activity of macrophage and osteoblast when coated over a substrate. An overview of macrophage and osteoblast response to micro and nano-hydroxyapatite that is involved in achieving maximal bone response is discussed.

1 illus, 74 ref

006285   Allahbakhsh H R;Saemi J (Mechanical Dep, Islamic Azad Univ, Shahrood Branch, Shahrrod, Iran, Email: allahbakhshy@gmail.com) : Design optimization of square and circular aluminium extrusion damage columns with crashworthiness criteria. Indian J Engng Mater Sci 2011, 18(5), 341-50.

There exists considerable motivation to reduce vehicle weight through the adoption of lightweight materials, such as aluminum alloys, while maintaining energy absorption and component integrity under crash conditions. This paper reports the deformation and damage behaviors of under crushing loadings with circular and square cross-sections so that, circular and square columns have used same material. The numerical analysis is carried out by Abaqus software. Subsequently, the collapse behavior of aluminum extrusion damage is validated by comparing against solution published in literature. Finally in order to find more efficient and lighter crush absorber and achieving minimum peak crushing force, response surface methodology (RSM) has been applied for optimizing the aluminum extrusion column. After obtaining the optimal designs, parametric studies are performed to investigate the influences of the design variables on the crash performance of such thin-walled columns.

11 illus, 4 tables, 24 ref

006284   Abdullah A B;Sapuan S M;Samad Z;Khaleed H M T;Aziz N A (School of Mechanical Engineering, Sains Malaysia Univ, Engineering Campus 14300 Nibong Tebal, Penang, Malaysia, Email: mebaha@eng.usm.my) : Investigation of geometrical defect of cold embossing part utilizing FEM and image processing technique. Indian J Engng Mater Sci 2012, 19(1), 41-6.

Accuracy of the forging parts becomes critical as the process depends on many factors. Defect may harm the assembly and tends to affect the performance of the parts. Therefore, it must be understood and detected as soon as the manufacturing begins. The size and complexity of the part limit the defect to be assessed. This study intent to investigate the defect of the cold embossing pin located at the head of a propeller blade. This is to ensure accurate assembly of the blade. In this work, the effects of design and process parameters on the formation of defect are studied using 2-D finite element analysis. The defect can be measured based on the incomplete filling of the region using the captured images from the FE result. The results seem to show that there is less effect from the diameter of punch and internal cavity, but more obvious due to the distance to the edge. The FE results are in good agreement with the experimental results.

13 illus, 3 tables, 17 ref

005091   Venugopal S;Ramanujachari V;Rajesh K K (NO, Defence Research and Development Lab, Hyderabad-500 058, Email: sankaran.venugopal@gmail.com) : Design and testing of lab-scale red fuming nitric acid/hydroxyl-terminated polybutadiene hybrid rocket motor for studying regression rate. Def Sci J 2011, 61(6), 515-22.

Presents the design of a hybrid rocket motor and the experiments carried out for investigation of hybrid combustion and regression rates for a combination of liquid oxidiser red fuming nitric acid with solid fuel hydroxyl-terminated Polybutadiene. The regression rate is enhanced with the addition of small quantity of solid oxidiser ammonium perchlorate in the fuel. The characteristics of the combustion products were calculated using the NASA CEA Code and were used in a ballistic code developed for predicting the performance of the hybrid rocket motor. A lab-scale motor was designed and the oxidiser mass flow requirements of the hybrid motor for the above combination of fuel and oxidiser have been calculated using the developed ballistic code. A static rocket motor testing facility has been realised for conducting the hybrid experiments. A series of tests were conducted and proper ignition with stable combustion in the hybrid mode has been established. The regression rate correlations were obtained as a function of the oxidiser mass flux and chamber pressure from the experiments for the various combinations.

17 illus, 8 tables, 7 ref

005090   Venugopal S;Rajesh K K;Ramanujachari V (Defence Research and Development Lab, Kanchanbagh, Hyderabad-500 058, Email: sankaran.venugopal@gmail.com) : Hybrid rocket technology. Def Sci J 2011, 61(3), 193-200.

With their unique operational characteristics, hybrid rockets can potentially provide safer, lower-cost avenues for spacecraft and missiles than the current solid propellant and liquid propellant systems. Classical hybrids can be throttled for thrust tailoring, perform in-flight motor shutdown and restart. In classical hybrids, the fuel is stored in the form of a solid grain, requiring only half the feed system hardware of liquid bipropellant engines. The commonly used fuels are benign, nontoxic, and not hazardous to store and transport. Solid fuel grains are not highly susceptible to cracks, imperfections, and environmental temperature and are therefore safer to manufacture, store, transport, and use for launch. The status of development based on the experience of the last few decades indicating the maturity of the hybrid rocket technology is given in brief.

^iia3 illus, 44 ref

005089   Veerabuthiran S;Razdan A K (NO, Laser Science and Technolgoy Centre, Delhi-110 054, Email: vrs_74@rediffmail.com ) : LIDAR for detection of chemical and biological warfare agents. Def Sci J 2011, 61(3), 241-50.

Remote detection of chemical and biological warfare agents and toxic gases in the atmosphere is of current interest to both the military and civilian agencies. Out of all currently available techniques, no single technique provides efficient detection against such threats at significant standoff distances. Light detection and ranging (LIDAR) technologies, based on the transmission of laser pulses and analysis of the return signals, have demonstrated impressive capabilities in remote detection of such toxic chemicals. LIDAR is a highly sensitive tool to detect the extremely low concentrations of various toxic agents present in the form of thin clouds at distances of few kilometer. The detection of these toxic clouds is based on the approach of first detecting and measuring the range of the clouds using the scattering phenomena and subsequently identifying the composition of toxic clouds using absorption and fluorescence phenomena. Laser Science and Technology Centre (LASTEC), Delhi has been working on the design and development of LIDAR systems for detection of chemical and biological warfare (CBW) agents. In this paper, theoretical analysis of differential absorption LIDAR (DIAL) for detection of chemical agents and fluorescence LIDAR for detection of biological agents has been discussed. For some typical parametric conditions, the received power levels from different ranges to detect specific concentrations of chemical or biological clouds have been computed and discussed. The technical details of the indigenously developed backscattering LIDAR, which detects and measures the distance of cloud layers up to 5 km is also presented.

5 illus, 1 table, 24 ref

005088   Twala B (NO, University of Johannesburg, Johannesburg, South Africa, Email: btwala@uj.ac.za) : Predicting software faults in large space systems using machine learning techniques. Def Sci J 2011, 61(4), 306-16.

Recently, the use of machine learning (ML) algorithms has proven to be of great practical value in solving a variety of engineering problems including the prediction of failure, fault, and defect-proneness as the space system software becomes complex. One of the most active areas of recent research in ML has been the use of ensemble classifiers. How ML techniques (or classifiers) could be used to predict software faults in space systems, including many aerospace systems is shown, and further use ensemble individual classifiers by having them vote for the most popular class to improve system software fault-proneness prediction. Benchmarking results on four NASA public datasets show the Naive Bayes classifier as more robust software fault prediction while most ensembles with a decision tree classifier as one of its components achieve higher accuracy rates.

9 illus, 1 table, 39 ref

005087   Tiwary K;Sharada G;Amarjit Singh (NO, Defence Research and Development Lab, Hyderabad-500 005, Email: tiwaryk1@rediffmail.com) : Underwater navigation using pseudolite. Def Sci J 2011, 61(4), 331-6.

Using pseudolite or pseudo satellite, a proven technology for ground and space applications for the augmentation of GPS, is proposed for underwater navigation. Global positioning systems (GPS) like positioning for underwater system, needs minimum of four pseudolite-ranging signals for pseudo-range and accumulated delta range measurements. Using four such measurements and using the models of underwater attenuation and delays, the navigation solution can be found. However, for application where the one-way ranging does not give good accuracy, alternative algorithms based upon the bi-directional and self-difference ranging is proposed using self-calibrated pseudolite array algorithm. The hardware configuration is proposed for pseudolite transceiver for making the self-calibrated array. The pseudolite array, fixed or moored under the sea, can give position fixing similar to GPS for underwater applications.

3 illus, 2 tables, 13 ref

005086   Tamilselvan G M;Shanmugam A (ECE Dep, Bannari Amman Institute of Technology, Sathyamangalam-638 401, Email: tamiltamil@rediffmail.com) : Cluster based interference mitigation scheme for performance enhancement in IEEE 802.15.4. J scient ind Res 2011, 70(9), 756-61.

Study proposed an adaptive transmission power aware cluster scheduling algorithm using multiple channels in a wireless personal area network (WPAN) in the presence of wireless local area network (WLAN) interference. Algorithm includes node identification, channel allocation, clustering and time scheduling. In proposed algorithm, performance metrics [bit error rate (BER), packet error rate (PER), throughput, average end-end delay and average jitter] were measured through Qualnet simulation and it is found effective in an IEEE 802.15.4 cluster-tree network in the presence of multiple IEEE 802.11 interferers.

7 illus, 10 ref

005085   Sun Y;Zhu B;Li S (NO, Anhui University of Technolgoy, Maanshan, Anhui-243002, Email: yunlan@mail.ustc.edu.cn) : Effect of nitrate ester on the combustion characteristics of PET/HMX -based propellants. Def Sci J 2011, 61(3), 206-13.

Effect of nitrate ester NG/TEGDN on the combustion characteristics of PET/HMX-based propellants has been experimentally investigated using of high-speed photography technique and scanning electron microscopy. It is indicated that the increase of NG/TEGDN content has little impact on the propellant burning rates at the same pressure. Furthermore, propellant can not be self-sustaining combustion at low pressure (≥ 1MPa). The increase of NG/TEGDN content does not affect the flame structure of propellant, but it plays an important role in condensed phase reaction zone. The flame structure of propellant is estimated. The thermal decomposition products in different combustion zones are also discussed. Scanning electron microscopy examination of quenched sample indicates that a liquified layer forms during combustion of these propellants. Numerous gas bubbles are present. Especially, the burning surface of propellant with low NG/TEGDN content shows signs of crystallization. The thickness of condensed phase reaction zone, by cross-section examination of propellant burning surface, has also been investigated. The results show that the thickness of condensed phase reaction zone increases with NG/TEGDN content increasing. These observations suggest that the condensed phase zone plays significant role in propellant combustion.

7 illus, 22 ref

005084   Srivastava H B;Vinod Kumar;Verma H K;Sundaram S S (NO, Instruments Research and Development Establishment, Dehradun-248 008, Email: hbs@irde.drdo.in) : Performance assessment of pre-processing filters for infrared search and track applications. Def Sci J 2011, 61(3), 251-6.

Enhance detection probability and to reduce false alarms, infrared imagery is pre-processed before subjecting it to detection algorithms in infrared search and track systems. Pre-processing algorithms are used to predict the complex background and then to subtract the predicted background from the original image. The difference image is passed to the detection algorithm to further distinguish between the target and the background and/ or noise more accurately. A number of pre-processing algorithms have been reported in literature, with their relative advantages and disadvantages. Brings out the computational complexities and simulation results of various algorithms for assessing their relative performances. Based on these parameters, statistical algorithms in general and max-min algorithms in particular, are recommended to be used for infrared search and track systems.

9 illus, 2 tables, 11 ref

005083   Singh S P;Mondal S;Hussain K;Datta P K (NO, Indian Institute of Technology, Kharagpur-721 302, Email: pkdatta@phy.iitkgp.ernet.in) : Development of optical parametric oscillator tunable in the range 970-1460 nm. Def Sci J 2011, 61(4), 377-82.

Optical parametric oscillator (OPO) tunable in the range 970-1460 nm has been developed using bet barium borate (BBO) crystal as the gain medium and second harmonic of Nd:YAG laser as pump source. Two sets of resonators were used to cover the range; first was nearly-degenerate (970-1180 nm) and the second was nondegenerate (1240-1460 nm). The measured threshold pump pulse energy was nearly 8 mJ. Maximum signal pulse energy of about 14 mJ was obtained for pump pulse energy of nearly 31 mJ. Power scaling efficiency was about 70 per cent. The signal pulse width was ˜ 5 ns corresponding to the pump pulse width of ˜ 9 ns. OPO signal beam quality was Gaussian, although the pump beam was top-hat multimode.

8 illus, 9 ref

005082   Shekhar H (NO, High Energy Materials Research Lab, Pune-411 021, Email: himanshudrdo@rediffmail.com) : Effect of termperature on mechanical properties of solid rocket propellants. Def Sci J 2011, 61(6), 529-33.

Mechanical properties of solid rocket propellants are dependent on temperature. Any change in temperature brings significant change in the tensile strength, percentage elongation, and elastic modulus of the propellant. Different classes of operational solid rocket propellants namely extruded double-base propellants, composite, extruded composite and nitrarte ester polyester propellants were evaluated at different temperatures in the operating range of the rockets and missiles preferably in the range of -50°C to +55°C. It was observed that for each class of propellant, as temperature reduces, propellant becomes hard. This is depicted by increase in elastic modulus and tensile strength of the material. However, trend of percentage elongation is not very uniform. Extruded double-base propellants show less percentage elongation (around 1 per cent) at reduced temperature (-50 °C) probably due to brittleness. So is the trend with case-bonded composite propellants. However, reverse trend is exhibited by cartridge-loaded composite propellants and nitrate ester polyester propellants. Such propellants show higher percentage elongation (6 per cent for CLCP and 35 per cent for NEPE) at reduced temperature (-50°C). This makes such propellants tough and more area under stress-strain curve at reduced temperature is observed.

7 illus, 12 ref

005081   Sankarasubramanian R (NO, Defence Metallurgical Research Lab, Hyderabad-500 058, Email: sankara@dmrl.drdo.in ) : Microstructural evolution in elastically-stressed solids: a phase-field simulation. Def Sci J 2011, 61(4), 383-93.

Simulation of microstructures under different processing conditions is important for fine-tuning the processing window as well as to understand the mechanisms. Phase field simulation has gained importance for problems with diffuse interfaces. Since in this simulation, thermodynamic driving forces (chemical as well as non-chemical) and kinetic constraints have been naturally incorporated, it has the potential to simulate microstructures under different processing and service conditions. In this paper, DMRL's initiatives on using phase field simulations to understand microstructural evolution in both the phase separating and precipitating model systems have been presented. The influence of misfit stresses on the morphology of microstructures has been described. Output from actual thermodynamic calculations can be combined with these simulations to study systems of technological importance.

^iia14 illus, 26 ref

005080   Ravindra Kumar;Misra M K;Rohitash Kumar;Gupta D;Sharma P K;Tak B B;Meena S R (Defence Lab, , Jodhpur-342 011, Email: rka_dlj@rediffmail.com) : Phase chagne materials: technology status and potential defence applications. Def Sci J 2011, 61(6), 576-82.

Phase change materials (PCM) are being utilised world over for energy storage and temperature smoothening applications. Defence Laboratory Jodhpur (DLJ) has initiated a R&D programme to apply PCM in solving many heat related problems being faced by Indian forces during desert operations specially failure of mission-critical components. Under the programme, special organic PCM (Patent application no. 2258/DEL/2007 and low melting metal alloys have been developed well tuned to desert diurnal cycle. The PCM panels, when applied as an internal lining in buildings, structures and vehicles can moderate the extreme temperature within human tolerable range (below 40°C) without the use of any external power for cooling. The panels can also act as power saver in air conditioned buildings. A cool vest has also been developed with chargeable PCM packs to provide comfortable microenvironment to a soldier on field duty (below 30°C) for 2-3 hrs. To improve reliability of mission critical electronic instruments during desert operation, technology of absorptive PCM heat sinks is under development at DLJ. The special heat sink will absorb heat generated by component for critical mission (up to 1 hr) independent of environment temperature and thus ensure smooth functioning of critical components even in extreme hot conditions. In the study status of PCM technology world over has been reviewed along with the brief account of research on PCM at DLJ.

^iia6 illus, 2 tables, 52 ref

005079   Ram Mohan C V;Ramanathan J;Satish Kumar;Gupta A V S S K S (NO, Advanced Systems Lab, Hyderabad, Email: rammohanchv66123@rediffmail.com) : Characterisation of materials used in flex bearings of large solid rocket motors. Def Sci J 2011, 61(3), 264-9.

Solid rocket motors are propulsion devices for both satellite launchers and missiles, which require guidance and steering to fly along a programmed trajectory and to compensate for flight disturbances. A typical solid rocket motor consists of motor case, solid propellant grain, motor insulation, igniter and nozzle. In most solid rocket motors, thrust vector control (TVC) is required. One of the most efficient methods of TVC is by flex nozzle system. The flex nozzle consists of a flexible bearing made of an elastomeric material alternating with reinforcement rings of metallic or composite material. The material characterisation of AFNOR 15CDV6 steel and the natural rubber-based elastomer developed for use in flex nozzle are discussed. This includes testing, modelling of the material, selection of a material model suitable for analysis, and the validation of material model.

13 illus, 13 ref

005078   Rakesh Kumar;Misra A;Ghosh A K (NO, Indian Institute of Technology, Kanpur, Uttar Pradesh, Email: rakpec@iitk.ac.in) : Modelling of cascade fin aerodynamics near stall using Kirchhoff's steady-state stall model. Def Sci J 2011, 61(2), 157-64.

Nonlinear longitudinal aerodynamics associated with cascade fins at high angles of attack near stall has been modelled using Kirchhoff's formulation. Grid fins are a relatively recent development in guided missile technology. A new category of grid fins, nomenclatured as cascade fins, has been proposed. In cascade fin design, an appropriate selection of gap-to-chord ratio and the number of planar members lead to desired stall angle and acceptable overall lift coefficient, respectively. Kirchhoff's steady-state stall model has been validated on wind tunnel data generated for Cascade fins having rectangular airfoil cross-section. National Wind Tunnel Facility (NWTF) of IIT, Kanpur, was used to generate the wind tunnel data consisting of the variation of lift coefficient with angle of attack. The cascade fins were tested to generate the data by varying gap-to-chord ratio and number of planar fins. The cascade fins with rectangular cross-section were tested with and without end plates. Kirchhoff's steady-state stall model was applied to wind tunnel data of cascade fins for modelling flow separation point and maximum likelihood method was used to estimate the parameters characterising stall characteristics. The effects of end plates, variation of number of fins and gap-to-chord ratio on parameter estimation were also studied. It has been observed that Kirchhoff's steady-state stall model could advantageously be applied to model nonlinear aerodynamics associated with cascade fins at high angle of attack.

17 illus, 5 tables, 15 ref

005077   Raghunath C R;Punya Prabha V;Yeshaswini H S; Sushma T N;Rashmi H (NO, M.S. Ramaiah Institute of Technology, Bangalore-560 054, Email: raghunath_Irde@yahoo.co.in) : High performance interconnection technology in avionics. Def Sci J 2011, 61(4), 354-63.

Avionics sub-systems continue to get smaller and more functional, driving the total circuit package itself to become denser, causing the printed wiring board (PWB) to evolve new laminates to meet these needs. There is a continuous scope for improvement to match the requirement of wireability demand from high density and high speed integrated circuits. Development of control processing units and rapid expansion of memory device capabilities were realised by the development of large-scale integrated circuits and other electronic devices with higher integration and with new functionalities. Enormous efforts have been put on the development of the system-on-chip (SOC), where a single semiconductor chip constituting complete system is bonded on substrate. These innovations in packaging technology made a big impact on laminates used in printed circuit boards. Aircraft systems are expected to withstand disturbances due to unexpected threats. Under such situations, passengers' safety, emergency landing and timely information to pilot become of paramount importance, hence, new innovative laminate systems are being developed. Various aspects of laminates and the current developments that are taking place are facilitating scientists and engineers in selecting appropriate laminate systems, have been discussed.

11 illus, 4 tables, 20 ref

005076   Pawar S S;Sunnapwar V K;Mujawar B A (NO, Lokmanya Tilak College of Engineering, Navi Mumbai-400 709, Email: sspawar_ltcoe@yahoo.co.in) : Critical review of heat transfer through helical coils of circular cross section. J scient ind Res 2011, 70(10), 835-43.

Heat transfer enhancement techniques [active techniques (electric field, acoustic or surface vibration, etc.) and passive techniques (fluid additives or special surface geometries)] can improve performance of heat exchangers to perform a certain heat transfer duty. Curved tubes have been used as one of the passive heat transfer enhancement techniques and are most widely used tubes in several heat transfer applications. Reviews heat transfer through helical coil of circular cross sections in terms of different dimensionless numbers, their validity, and effect of geometry, friction factors, different coil curvature ratios, fluid types, laminar and turbulent flow on heat transfer rate.

2 tables, 63 ref

005075   Patil S S;Bhaskar P;Shrimanth Sudheer L (NO, HKES SLN College of Engineering, Raichur-584 135, Email: p_bhaskar68@yahoo.com) : Design and implementation of an integrated fuzzy logic controller for a multi-input multi-output system. Def Sci J 2011, 61(3), 219-27.

Design and real time implementation of an integrated fuzzy logic controller (IFLC) for a multiple-input multiple-output (MIMO) system is presented. The design of IFLC for an uncoupled MIMO system has been discussed. This study develops a combination of fuzzy and PID controllers (PIDC) to improve the control performance of a two-input-two-output (TITO: angular position, and rotational speed) system. These parameters play a vital role in radar-tracking system for military applications. To verify the applicability of proposed controller, two-motor unit plant along with indigenously designed multi-channel analog interface board of 16-bit precision is used. The proposed MIMO control system is interfaced to a PC through its parallel port. The performance of the system is studied by subjecting it to various standard test signals. The IFLC performs better than the other two controllers in tracking the input command for linear as well as nonlinear inputs such as step, square, triangular, and sine waves is observed.

7 illus, 2 tables, 16 ref

005074   Panigrahi N;Mohan B K;Athithan G (NO, Centre for Artificial Intelligence and Robotics, Bengaluru-560 093, Email: npanigrahi7@gmail.com) : Pre-processing algorithm for rectification of geometric distortions in satellite images. Def Sci J 2011, 61(2), 174-9.

Number of algorithms have been reported to process and remove geometric distortions in satellite images. Ortho-correction, geometric error correction, radiometric error removal, etc are a few important examples. These algorithm require supplementary meta-information of the satellite images such as ground control points and correspondence, sensor orientation details, elevation profile of the terrain, etc to establish corresponding transformations. A pre-processing algorithm has been proposed which removes systematic distortions of a satellite image and thereby removes the blank portion of the image. It is an input-to-output mapping of image pixels, where the transformation computes the coordinate of each output pixel corresponding to the input pixel of an image. The transformation is established by the exact amount of scaling, rotation and translation needed for each pixel in the input image so that the distortion induced during the recording stage is corrected.

3 illus, 11 ref

005073   Pandey U;Bajpeyi A;Mishra M;Sharma A;Singh B (Electronics and Communication Engineering Dep, R B S College, Bichpuri, Agra-283 105, Email: bbsagra@gmail.com) : Unusual sferics observed at Agra. Indian J Radio Space Phys 2011, 40(4), 183-90.

Employing the experimental setup intended for whistler observations, a large number of unusual sferics have been recorded at the low latitude ground station Agra (geomagnetic latitude 18.09°N, longitude 152.21°E) during six months of observations between 01 November 2009 and 30 April 2010. The data include banded and narrow band sferics whose occurrences are found to be enhanced occasionally. The results have been examined as possible effects of lightning, solar flare, magnetic storms, and earthquake. The unusual enhancement of all types and those of banded structures have been found to correlate positively with X-ray events and magnetic storms, respectively. The banded and unusual structures of sferics have been interpreted in terms of specular reflection from a slab of enhanced ionization existing at the base of the ionosphere.

8 illus, 34 ref

005072   Nirmal D;Vijaya Kumar P (NO, Karunya University, Coimbatore-641 114, Email: nirmal@karunya.edu) : Fin field effect transistors performance in analog and RF for high-k dielectrics. Def Sci J 2011, 61(3), 235-40.

High-k is needed to replace SiO² as the gate dielectric to reduce the gate leakage current. The impact of a high-k gate dielectric on the device short channel performance and scalability of nanoscale double gate Fin Field Effect Transistors (FinFET) CMOS is examined by 2-D device simulations. DG FinFETs are designed with high-k at the high performance node of the 2008 Semiconductor Industry Association International Technology Roadmap for Semiconductors (ITRS). DG FinFET CMOS can be optimally designed to yield outstanding performance with good trade-offs between speed and power consumption as the gate length is scaled to <60> 10 nm. Using technology computer aided design (TCAD) tools a 2-D FinFET device is created and the simulations are performed on it. The optimum value of threshold voltage is identified as V_T=0.653V with ε=23(ZrO₂) for the 2-D device structure. For the 2-D device structure, the leakage current has been reduced to 9.47x10^-14 A. High-k improves the I_on/I_off ratio of transistors for future high-speed logic applications and also improves the storage capability.

10 illus, 19 ref

005071   Narender S (NO, Defence Research and Development Lab, Hyderabad-500 058, Email: nanduslns07@gmail.com) : Mathematical modelling of rotating single-walled carbon nanotubes used in nanoscale rotational actuators. Def Sci J 2011, 61(4), 317-24.

Rotating single-walled carbon nanotube (SWCNT) is modelled as an Euler-Bernoulli beam using the non-local/non-classical continuum mechanics. These rotating SWCNTs are used in nanoscale rotational actuators. The mathematical model has been used to study the wave behaviour in rotating SWCNTs. The governing partial differential equation for a uniform rotating beam is derived incorporating the non-local scale effects. The spatial variation in centrifugal force has been modelled in an average sense. Even though this averaging seems to be a crude approximation, one can use this as a powerful model in analysing the wave dispersion characteristics ofthe rotating CNTs. Spectrum and dispersion curves as a function of rotating speed and non-local scaling parameter were obtained. It has been shown that the dispersive ?exural wave tends to behave non-dispersively at very high rotation speeds. The numerical results have been simulated for a rotating SWCNT as a waveguide.

6 illus, 29 ref

005070   Nair B M;Arunkumar K P;Menon S B (NO, Naval Physical and Oceanographic Lab, Kochi-682 021, Email: baiju_nair1@yahoo.com) : Broadband passive sonar signal simulation in a shallow ocean. Def Sci J 2011, 61(4), 370-6.

Broadband plane-wave model is valid only in the far-field of a point source under free-field propagating conditions. However the acoustics in ocean is characterised by multi-modal acoustic propagation due to its topbottom limited boundary conditions. The effect of multi-modal field is to alter the source spectrum while the effect of dispersion is to modify the pulse shape. Moreover, using a plane-wave beam former in a multi-modal field leads to bias in the bearing estimates. These effects are highly dependant on the environment parameters and have important ramification for target localisation and classification in an ocean waveguide. A more realistic simulator has been proposed which essentially models these effects and therefore serves to provide test signals for first-hand verification of signal processing algorithms to be developed for such scenarios. This model is to be understood as a better model than the na‹ve plane-wave model which is entirely oblivious of even the gross features such as wave propagation in an oceanic waveguide. The channel parameter so estimated from the present simulation can be convolved with the radiated noise spectra of the source to generate passive sonar signal.

11 illus, 13 ref

005069   Mohanty C R;Swar A K;Meikap B C;Sahu J N (Chemical Engineering Dep, Indian Institute of Technology, Khargpur-721 302, Email: jnsahu@um.edu.my) : Factors influencing fly ash resistivity from electrostatic precipitator with reference to India. J scient ind Res 2011, 70(9), 795-803.

Electrostatic precipitator (ESP) performance is a function of electrical resistivity of particles in flue gas. This study presents basic factors that influence fly ash resistivity and ultimately ESP performance. Factors that influence electrical resistivity are coal, sulfur, flue gas moisture, flue gas temperature, and ash chemistry etc. From maintenance perspective of ESP used in thermal power plants in India, analysis could be considered enough for predicting the performance of ESP.

4 illus, 1 table, 67 ref

005068   Meshram S;Mohandas T (NO, Defence Metallurgical Research Lab, Hyderabad-500 058, Email: suresh_uor@yahoo.co.in) : Welding studies on a near-alpha titanium alloy. Def Sci J 2011, 61(6), 590-6.

Mechanical properties and microstructures of electron beam and friction welds of a near-alpha titanium alloy IMI 834 (presently TIMET 834) have been evaluated. Electron beam welds that contain micro pores and friction welds are free from such solidification-related defects. Porosity index in electron beam welds shows a decreasing trend with an increase in the welding speed. Electron beam welds contain coarse prior β grains and fine transformed β microstructure while, friction welds contain fine prior β grains and coarse transformed β microstructure. Electron beam welds with fine transformed β microstructure exhibited higher strength as compared to friction welds with coarse transformed β microstructure. The impact toughness of both the welds is comparable. Drastic reduction in impact toughness was observed when the welds were subjected to post-weld ageing as a result of inter-lath precipitation. Coarse-grained electron beam welds exhibited better creep and stress rupture properties as compared to friction welds.

6 illus, 5 tables, 21 ref

005067   Mathur R P;Singh R K;Ray S;Manivel Raja M; Ghosal P;Chandrasekaran V (NO, Defence Metallurgical Lab, Hyderabad-500 058, Email: mathur@dmrl.drdo.in) : Structural and magnetic studies in Ni-Mn-Ga based ferromagnetic shape memory alloys. Def Sci J 2011, 61(3), 275-84.

Quaternary Ni₅₀Fe_xMn_30-xGa₂₀ (x = 2.5, 5, and 15) and Ni₄₅Fe₅Mn₃₀Ga₂₀ alloys based on modification of ferromagnetic shape memory alloy ternary Ni₅₀Mn₃₀ Ga₂₀ composition prepared by vacuum arc melting and subsequent heat-treatment were investigated to understand the effect of varying Fe-content in Ni-Fe-Mn-Ga alloys. With increasing Fe-content, saturation magnetisation and Curie temperature increased, however martensite transformation temperature did not show a systematic variation. The ⁵⁷Fe Mossbauer spectra showed three distinct sub-spectra depending upon the site occupancy by Fe-atoms. The results are explained with site selection by Fe-atom in parent L2₁ lattice.

6 illus, 3 tables, 29 ref

005066   Majumdar J;Nandi M;Nagabhushan P (NO, Nitte Meenakshi Institute of Technology, Bengaluru-560 064, Email: jharna.majumdar@gmail.com) : Retinex algorithm with reduced halo artifacts. Def Sci J 2011, 61(6), 559-66.

Retinex image enhancement technique is an attempt to model human vision system. Scope of this nonlinear enhancement algorithm is immense which makes it a powerful algorithm. The most important application of Retinex algorithm is the development of visibility improvement system for helping drivers with poor vision at night and bad weather condition^1-9. The algorithm is extensively used in Langley Research Centre, NASA, and DLR, Germany for their technology demonstrator projects of development of enhanced vision system for NASA 757 aircraft. The algorithm is also extensively used in medical image processing area in the TruView Imaging Company formed by the scientists of NASA who worked extensively for the development of this algorithm^10-11. Presents the work done on Retinex so far and proposes a method to reduce the halo artifacts for better performance of human vision system.

10 illus, 2 tables, 28 ref

005065   Mahdavi M;Mahdavi M (NO, Young Researchers Club, Islamic Azad Univerisity of Najafabad Branch, Isfahan, Iran, Email: mahdavi277@yahoo.com) : Reliability based improving model for complicated systems lifetime distribution. J scient ind Res 2011, 70(9), 751-5.

Explores a new method to find the most reliable lifetime distribution function of systems, via an applied heuristic model. In most operating systems, complicity of system obligates high degree of reliability. This model proposes a more appropriate reliability function between the one based on lifetime distribution and another based on relevant extreme value distribution.

5 illus, 2 tables, 20 ref

005064   Madhu V;Balakrishna Bhat T (NO, Defence Metallurigal Research Lab, Hyderabd-500 058, Email: madhu.vemuri@dmrl.drdo.in) : Armour protection and affordable protection for futuristic combat vehicles. Def Sci J 2011, 61(4), 394-402.

Protection creates a shift in the internal paradigm of the soldier and leads to multiplied psychological stamina for moving fearlessly in the battlefield which generates a major force-multiplier effect. Hence, the mechanized forces are still likely to be one of the dominant forces on the futuristic battlefield and would be the primary target of enemy forces capable of engaging from tank guns up to 4-5 km in a direct fire mode and up to 8-10 km in an indirect fire modes. Increased protection is possible only using advanced armour technology. Throughout the history of warfare, materials technologies have had a significant impact on land-combat force capabilities. Armour materials have progressed through improvements in metallic systems and development of advanced, lightweight (low areal density) composite materials. The advancements in ceramic systems have further improved the performance. Similarly, the advances in development of explosive reactive armour has generated efficient armour system against all contemporary high explosive antitank (HEAT) ammunition and missile threats for armoured vehicles. Yet, to achieve armour performance exceeding that of the current light combat vehicles and main battle tanks for new vehicular systems, weighing significantly less than the present combat vehicles, advances in new armour materials, systems, and survivability technologies are required. This paper describes various approaches and advancements in the metallic, ceramic, and composite armour materials and new dynamic armour systems that are essential to improve the survivability of armoured vehicles in the futurisitic multi-spectral battlefied scenarios.

10 illus, 2 tables, 33 ref