Showing papers in "Defence Science Journal in 2010"

Defence Applications of Polymer Nanocomposites

Abstract: The potential opportunities promised by nanotechnology for enabling advances in defence technologies are staggering. Although these opportunities are likely to be realised over a few decades, many advantages are currently being explored, particularly for defence applications. This review provides an insight into the capabilities offered by nanocomposites which include smart materials, harder/lighter platforms, new fuel sources and storage as well as novel medical applications. It discusses polymer-based nanocomposite materials, nanoscale fillers and provides examples of the actual and potential uses of nanocomposite materials in defence with practical examples.Defence Science Journal, 2010, 60(5), pp.551-563, DOI:http://dx.doi.org/10.14429/dsj.60.578

Advances in High Energy Materials (Review Paper)

Abstract: Research and development efforts for realizing higher performance levels of high energy materials (HEMs) are continued unabated all over the globe. Of late, it is becoming increasingly necessary to ensure that such materials are also eco-friendly. This has provided thrust to research in the area of force multiplying HEMs and compounds free from pollution causing components. Enhancement of the performance necessitates introduction of strained structure or increase in oxygen balance to achieve near stoichiometry. The search for environment friendly molecules is focused on chlorine free propellant compositions and lead free primary explosives. Energetic polymers offer added advantage of partitioning of energy and thus not necessitating the concentration of only solid components (HEMs and metal fuels) in the formulations, to achieve higher performance, thereby leading to improvement in energetics without adversely affecting the processability and mechanical properties. During recent times, research in the area of insensitive explosives has received impetus particularly with the signature of STANAG. This paper gives a review of the all-round advances in the areas of HEMs encompassing oxidizers, high-energy dense materials, insensitive high-energy materials, polymers and plasticizers. Selected formulations based on these materials are also included. Defence Science Journal, 2010, 60(2), pp.137-151 , DOI:http://dx.doi.org/10.14429/dsj.60.327

Controlling a mobile robot with a biological brain

Abstract: The intelligent controlling mechanism of a typical mobile robot is usually a computer system. Some recent research is ongoing in which biological neurons are being cultured and trained to act as the brain of an interactive real world robot�thereby either completely replacing, or operating in a cooperative fashion with, a computer system. Studying such hybrid systems can provide distinct insights into the operation of biological neural structures, and therefore, such research has immediate medical implications as well as enormous potential in robotics. The main aim of the research is to assess the computational and learning capacity of dissociated cultured neuronal networks. A hybrid system incorporating closed-loop control of a mobile robot by a dissociated culture of neurons has been created. The system is flexible and allows for closed-loop operation, either with hardware robot or its software simulation. The paper provides an overview of the problem area, gives an idea of the breadth of present ongoing research, establises a new system architecture and, as an example, reports on the results of conducted experiments with real-life robots.

Machine Learning and Pattern Recognition

Abstract: Learning is needed when there is no human expertise existing or when human beings are unable to explain their expertise. In such a situation, one simply collects all the possible previous information, analyse it and then make a rule for future prediction or taking meaningful decision. When we plan to conclude such a work with the help of a computer by providing it ample amount of data and our past experience with tools and techniques, then the whole process becomes machine learning. Hence, machine learning can be defined as programming computers to optimise a performance criterion using example data and past experience. For example, recognition of spoken speech is being done by human beings seemingly without any difficulty, but cannot explain how they do it. Defence Science Journal, 2010, 60(4), pp.345-347 , DOI:http://dx.doi.org/10.14429/dsj.60.502

Discrete Cosine Transform-based Image Fusion

Abstract: Image fusion by multi-resolution discrete cosine transform (MDCT) algorithm has been implemented and evaluated. The performance of this algorithm is compared with that of well known image fusion technique using wavelets. It is observed that image fusion by MDCT perform almost similar to that of wavelets. It is computationally very simple and it could be well suited for real time applications. Defence Science Journal, 2010, 60(1), pp.48-54 , DOI:http://dx.doi.org/10.14429/dsj.60.105

Radar Cross-section Measurement Techniques

Abstract: Radar cross-section (RCS) is an important study parameter for defence applications specially dealing with airborne weapon system. The RCS parameter guides the detection range for a target and is therefore studied to understand the effectiveness of a weapon system. It is not only important to understand the RCS characteristics of a target but also to look into the diagnostic mode of study where factors contributing to a particular RCS values are studied. This further opens up subject like RCS suppression and stealth. The paper discusses the RCS principle, control, and need of measurements. Classification of RCS in terms of popular usage is explained with detailed theory of RF imaging and inverse synthetic aperture radar (ISAR). The various types of RCS measurement ranges are explained with brief discussion on outdoor RCS measurement range. The RCS calibration plays a critical role in referencing the measurement to absolute values and has been described.The RCS facility at Reseach Centre Imarat, Hyderabad, is explained with some details of different activities that are carried out including RAM evaluation, scale model testing, and diagnostic imaging.Defence Science Journal, 2010, 60(2), pp.204-212, DOI:http://dx.doi.org/10.14429/dsj.60.341

Decontamination of Chemical Warfare Agents (Review Article)

Abstract: Chemical warfare agents (CWA) pose inevitable threat, both to soldiers and civilians. Risk on contact with these deadly agents can be avoided by neutralisation of their toxic effects. A suitable media with essential physico-chemical properties is required for this purpose. Considerable efforts have been made to develop several decontamination media suitable for neutralisation of highly toxic CWAs. This paper reviews history and details of recent technological advancements in the development of versatile, broad spectrum decontamination formulations against CWAs, as also nanosized metal oxides as CWA decontaminants. Defence Science Journal, 2010, 60(4), pp.428-441 , DOI:http://dx.doi.org/10.14429/dsj.60.487

Target Recognition Based on Fuzzy Dempster Data Fusion Method

Abstract: Data fusion technology is widely used in automatic target recognition system. Problems in data fusion system are complex by nature and can often be characterised by not only randomness but also by fuzziness. To accommodate complex natural problems with both types of uncertainties, it is profitable to construct a data fusion structure based on fuzzy set theory and Dempster Shafer evidence theory. In this paper, after representing both, the individual attribute of target in the model database and the sensor observation or report as fuzzy membership function, a likelihood function was constructed to deal with fuzzy data collected by each sensor. The method to determine basic probability assignments of each sensor report is proposed. Sensor reports are fused through classical Dempster combination rule. A numerical example is illustrated to show the target recognition application of the fuzzy-Dempster approach. Defence Science Journal, 2010, 60(5), pp.525-530 , DOI:http://dx.doi.org/10.14429/dsj.60.576

Split-and-merge Procedure for Image Segmentation using Bimodality Detection Approach

Abstract: Image segmentation, the division of a multi-dimensional image into groups of associated pixels, is an essential step for many advanced imaging applications. Image segmentation can be performed by recursively splitting the whole image or by merging together a large number of minute regions until a specified condition is satisfied. The split-and-merge procedure of image segmentation takes an intermediate level in an image description as the starting cutest, and thereby achieves a compromise between merging small primitive regions and recursively splitting the whole images to reach the desired final cutest. The proposed segmentation approach is a split-andmerge technique. The conventional split-and-merge algorithm is lacking in adaptability to the image semantics because of its stiff quadtree-based structure. In this paper, an automatic thresholding technique based on bimodality detection approach with non-homogeneity criterion is employed in the splitting phase of the split-and-merge segmentation scheme to directly reflect the image semantics to the image segmentation results. Since the proposed splitting technique depends upon homogeneity factor, some of the split regions may or may not split properly. There should be rechecking through merging technique between the two adjacent regions to overcome the drawback of the splitting technique. A sequential-arrange-based or a minimal spanning-tree based approach, that depends on data dimensionality of the weighted centroids of all split regions for finding the pair wise adjacent regions, is introduced. Finally, to overcome the problems caused by the splitting technique, a novel merging technique based on the density ratio of the adjacent pair regions is proposed. The algorithm has been tested on several synthetic as well as real life data and the results show the efficiency of the segmentation technique. Defence Science Journal, 2010, 60(3), pp.290-301 , DOI:http://dx.doi.org/10.14429/dsj.60.356

Protected Cultivation for Food and Nutritional Security at Ladakh (Review Paper)

Abstract: Ladakh, being cold, arid, high altitude region of India has a very harsh climate and a short agriculture season. Due to extreme long winter, the agriculture season is short, which extends from May-September in general, and in case of particular location, it depends upon altitude. Although the greenhouse technology is more than 200 years old but with the advent of plastics during the World War-II, a new phase in the greenhouse technology has emerged. The Defence Institute of High Altitude Research (DIHAR), one of the DRDO laboratories, is providing adequate support and technological help to set various types of green houses, both for the Army Units deployed in the far-flung areas and for the local farmers in the Ladakh. Till date, there were 65 greenhouses being established by DIHAR in most of the Army Units deployed in the eLi sector with the average vegetable production of around 2000 kg/greenhouse/year. At present, the much needed vegetables are being grown throughout the year in these hostile climates under protective cultivation, which not only gives them the fresh food but also the nutritional security of the troops deployed.

Developments in Pyrotechnics (Review Paper)

Abstract: The application of smoke and various types of smoke bombs/ devices developed are narrated. The light output of 51 mm, 81 mm, 120 mm and 120 mm LRM illuminating bombs developed is 2.6, 9.0, 10.8 and 15 lakhs candela, respectively. The IR flares developed for first and second generation anti-tank missile are in regular production. An IR decoy flare is developed for CMDS. Feasibility study on multi-spectral smoke and IR flare compositions is completed. 1W-1A No fire capability EED is developed. Gas generators 1200 cc, 2400 cc, 6000 cc are developed. Accuracy of pyro delay is improved. Laser initiated pyrocartridge is developed. Nanoscale Fe2O3 is synthesised and studied. A few toxic ingredients are replaced to march towards green pyrotechnics. Objectives for improved pyrotechnics are included. Defence Science Journal, 2010, 60(2), pp.152-158 , DOI:http://dx.doi.org/10.14429/dsj.60.333

Attributes of Seabuckthorn (Hippophae rhamnoides L.) to Meet Nutritional Requirements in High Altitude

Abstract: The diet of humans living in different geographical and climatic regions of the earth varies greatly in both quantity and composition of foods. Evidence is accumulating that indicates that there is a high risk of malnutrition at high altitude because of the usual lack of fresh food and environmental factors. Lack of nutritious diet in the difficult terrain is a potential stressor that elicits oxidative stress. The excretion of minerals from the body is higher in high altitude condition. The altered nutritional requirement can be met to a large extend by regular consumption of locally grown fruits and vegetables. Results of analysis of Seabuckthorn growing in Leh valley of Trans-Himalaya showed the presence of high content of multivitamins including vitamin C (275 mg/100g), vitamin A (432.4 IU/100g), vitamin E (3.54 mg/100g), Riboflavin (1.45 mg/100g), Niacin (68.4 mg/100g), Pantothenic acid (0.85 mcg/100g), vitamin B-6 (1.12 mg/100g), and vitamin B-2 (5.4 mcg/100g). Similarly, mineral elements composition revealed high amount of minerals including potassium (647.2 mg/l), calcium (176.6 mg/l), iron (30.9 mg/l), magnesium (22.5 mg/l), phosphorous (84.2 mg/l), sodium (414.2 mg/l), zinc (1.4 mg/l), copper (0.7 mg/l), manganese (1.06 mg/l) and selenium (0.53 mg/l). Defence Science Journal, 2010, 60(2), pp.226-230 , DOI:http://dx.doi.org/10.14429/dsj.60.344

Synthesis of Cobalt Oxide Nanoparticles/Fibres in Alcoholic Medium using y-ray Technique

Abstract: Nanoparticles of cobalt oxides were synthesised by steady state g irradiation technique using various alcoholic salt solutions of cobalt ions with aniline acting as a stabiliser. Preliminary results were investigated using UV-vis and Fourier transform infra red analysis. The X-ray diffractograms revealed major peaks at 2q values of ~ 36.4°, 39.1°, 44.2°, and 65.7° corresponding to the Co3O4 phase and one peak at ~30.7° (100 per cent intensity) for Co2O3 phase. Lower alcohols yielded particles while fibres were formed in higher alcohols as observed from transmission electron microscopic analysis. Iso-propanol was observed to yield cobalt oxide nanoparticles with highest stability, conversion yield and homogeneity in size. The average measured diameter and length of these fibres were ~29 nm and 130 nm respectively. Energy dispersive spectroscopy supports the formation of cobalt oxide. The X-ray photoelectron spectroscopic results for iso-propanol sample show a peak at 781.6 eV confirming the formation of Co3O4. Defence Science Journal, 2010, 60(5), pp.507-513 , DOI:http://dx.doi.org/10.14429/dsj.60.574

Expert Knowledge Base to Support Maintenance of a Radar System

Abstract: This paper presents the method for the creation of an expert knowledge base of a military object, for example a radar system. Such a knowldge base can be widely used to support the process of the maintenance of a complex technical object. The first step is a maintenance evaluation of the object. During this kind of analysis, it is necessary to perform the grouping and classification of the functional elements of the object.It is realised using the functional scheme of the object presented. Further, diagnostic information is combined with specialised experts' knowledge and transformed it into a set of servicing information. The participation of experts in the process of expert knowledge base preparation is significant. The purpose is to capture information that will be a fundamental for the design of a maintenance system dedicated to the particulartechnical object. The methods proposed were verified with appropriate examples, in which the set of specialised diagnostic information of the object was determined.Defence Science Journal, 2010, 60(5), pp.531-540, DOI:http://dx.doi.org/10.14429/dsj.60.84

Impact Analysis of Concrete Structural Components (Review Paper)

Abstract: This paper presents an overview on the concrete structural components subjected to impact loading. The review includes empirical formulae, analytical models, and numerical simulations. Various empirical formulae on penetration depth, perforation, and scabbing limits as well as their ranges of application have been provided. It has been observed that the information available on the validation of these models is limited. There is wider scope to study the performance of well known empirical formulae. Penetration resistance function play an important role in any analytical model. It has been observed that the major limitation is rigid projectile assumption. There is scope to develop new/improved analytical models to represent projectile characteristics. The numerical simulation of concrete structural components subjected to impact loads is a complex phenomenon. From the review, it is observed that employing appropriate material model for concrete, equation-of-state, contact algorithm and definition of yield surface plays significant role in the accurate simulation of concrete structural components. There is ample scope to develop improved methodologies in terms of development of material models and contact algorithms, which can be employed in nonlinear explicit finite element analysis of concrete structural components subjected to impact loading. Defence Science Journal, 2010, 60(3), pp.307-319 , DOI:http://dx.doi.org/10.14429/dsj.60.358

Military Malaria in Northeast Region of India (Review Paper)

Abstract: Malaria has always been a pernicious problem of serious health hazard in the northeast region of India. The problem is worst for military and paramilitary forces deputed in all the states of this part of country. The forces are deployed for a short time generally from non malarious regions and thus become highly vulnerable to acquire the malaria infection. Several potential malaria vectors with very high vectorial capacity and high slide positivity rate in civil population manifold the chances of infection. In the present review, the incidence of malaria in the armed forces and paramilitary forces are discussed in detail and minimal measures for the control of malaria in northeastern region have been suggested. Defence Science Journal, 2010, 60(2), pp.213-218 , DOI:http://dx.doi.org/10.14429/dsj.60.342

Adhesively-bonded Patch Repair with Composites

Abstract: Adhesively-bonded composite patch repairs over cracked or corrosion-damaged metallic aircraft structures have shown great promise for extending life of ageing structures. This study presents the numerical investigation into the interface behaviour of adhesively-bonded cracked aluminum alloy substrate patched with fibre-reinforced composite material. The adhesive is modelled as an elasto-plastic bilinear material to characterise the debond behaviour, while the defective substrate is regarded as linear elastic continuum. Two typical patch shapes were selected based on information available in the literature. Geometric and material nonlinear analyses for square and octagonal patches were performed to capture peel and shear stresses developed between the substrate and the patch to examine the possibility of interface delamination/debonding. Parametric studies on adhesive thickness and patch thickness were carried out to predict their infuence on damage tolerance of repaired structures.

The Evolution of AUSM Schemes

Abstract: This paper focuses on the evolution of advection upstream splitting method (AUSM) schemes. The main ingredients that have led to the development of modern computational fluid dynamics (CFD) methods have been reviewed, thus the ideas behind AUSM. First and foremost is the concept of upwinding. Second, the use of Riemann problem in constructing the numerical flux in the finite-volume setting. Third, the necessity of including all physical processes, as characterised by the linear (convection) and nonlinear (acoustic) fields. Fourth, the realisation of separating the flux into convection and pressure fluxes. The rest of this review briefly outlines the technical evolution of AUSM and more details can be found in the cited references.Defence Science Journal, 2010, 60(6), pp.606-613, DOI:http://dx.doi.org/10.14429/dsj.60.580

Development of Surface Acoustic Wave Electronic Nose

Abstract: The paper proposes an effective method to design and develop surface acoustic wave (SAW) sensor array-based electronic nose systems for specific target applications. The paper suggests that before undertaking full hardware development empirically through hit and trial for sensor selection, it is prudent to develop accurate sensor array simulator for generating synthetic data and optimising sensor array design and pattern recognition system. The latter aspects are most time-consuming and cost-intensive parts in the development of an electronic nose system. This is because most of the electronic sensor platforms, circuit components, and electromechanical parts are available commercially-off-the-shelve (COTS), whereas knowledge about specific polymers and data analysis software are often guarded due to commercial or strategic interests. In this study, an 11-element SAW sensor array is modelled to detect and identify trinitrotoluene (TNT) and dinitrotoluene (DNT) explosive vapours in the presence of toluene, benzene, di-methyl methyl phosphonate (DMMP) and humidity as interferents. Additive noise sources and outliers were included in the model for data generation. The pattern recognition system consists of: (i) a preprocessor based on logarithmic data scaling, dimensional autoscaling, and singular value decomposition-based denoising, (ii) principal component analysis (PCA)-based feature extractor, and (iii) an artificial neural network (ANN) classifier. The efficacy of this approach is illustrated by presenting detailed PCA analysis and classification results under varied conditions of noise and outlier, and by analysing comparative performance of four classifiers (neural network, k-nearest neighbour, naive Bayes, and support vector machine). Defence Science Journal, 2010, 60(4), pp.364-376 , DOI:http://dx.doi.org/10.14429/dsj.60.493

Thermal Stability of Zirconia-coated Multiwalled Carbon Nanotubes

Abstract: Sol-gel method has been used to coat multiwalled carbon nanotubes (MWCNTs) with zirconia at room temperature and the coated tubes were sintered at high temperature. The samples were characterised by Raman spectroscopy, x-ray diffraction, environmental scanning electron microscope, transmission electron microscopy, and energy-dispersive x-ray analyses. The performance of the coated-MWCNTs was investigated as a function of temperature. The TGA studies indicated that sintering of coated-MWCNTs has improved its oxidation resistance and this improvement is related to the proper selection of sintering temperature. Defence Science Journal, 2010, 60(3), pp.337-342 , DOI:http://dx.doi.org/10.14429/dsj.60.362

Wishbone Structure for Front Independent Suspension of a Military Truck

Abstract: Wishbone structure for double wishbone front-independent Suspension for a military truck application is presented. At present, the vehicle is equipped with rigid axle with leaf springs. There are two aspects that dictate the design of wishbone structure, viz. the path of relative motion between the constituents of the suspension system and the forces transmitted between them. Also, enhancement of mobility was made possible by maintaining the live axle in the system. A double wishbone, double coil spring with twin damper configuration was employed for this application. MBD Analysis was carried out using MSC ADAMS. A double wishboneindependent suspension has been designed for the front axle and has been successfully integrated with the vehicle. Defence Science Journal, 2010, 60(2), pp.178-183 , DOI:http://dx.doi.org/10.14429/dsj.60.337

Influence of Terrain on Modern Tactical Combat: Trust-based Recommender System

Abstract: In Army Services, there are a number of valuable decisions that have to be taken for mission accomplishment. These decisions are very important and the choice of a weapon may be able to alter the outcome of a battle decisively. Among several such decisions one is to decide which weapons to deploy/assign over a given terrain. Recommender systems are intelligent applications to assist users in a decision-making process where they want to choose one item amongst a potentially overwhelming set of alternative products or services. This paper proposes the design of recommender system that automates the process of finding the appropriate type of weapon(s) that can be deployed over a terrain having certain characteristics. The user agent seeks recommendations, which are in the form of intuitionistic fuzzy set (IFS), from trustworthy peers and produces aggregated order of recommendations taking degree of trust on recommenders into consideration. Trust on recommender is also updated based on importance of recommendation given to the user. A prototype of the trust-based recommender system for modern tactical combat system has been designed and developed through which the user can get the recommendation to use a specific kind of weapon or a set of weapons that would be best-suited in a given type of terrain. Defence Science Journal, 2010, 60(4), pp.405-411 , DOI:http://dx.doi.org/10.14429/dsj.60.498

Future armoured troop carrying vehicles

Abstract: Present-day reliance on wheeled and tracked armour personnel carriers (APCs) and infantry fighting vehicles (IFVs), may be changed in the future. Shaped charge grenades and impovised explosive devices (IEDs)represent a considerable threat, even to well protected main battle tanks (MBTs). Paradoxically, the crew of wheeled and tracked troop-carrying vehicles is numerically three to four times larger than that of MBTs, however, their protection in all aspects is significantly lower. Therefore, heavier vehicles may get more attention in the future, where sharing the chassis and a number of components with MBTs could provide significant reductions in procurement costs and maintenance, as well as a simplified logistics in relation to the latest tracked. Obviously, the IFVs mobility of heavy vehicles would be lower than that of lighter vehicles. However, by applying various degrees of modular armour protection, a significant rise in strategic, operational, and tactical mobility could be achieved. Such heavy tracked vehicles, built on a common chassis as MBTs, may equip the future heavy brigades, which will be in contrast to the lighter wheeled vehicles included in rapid deployment brigades. As a result, tracked personnel carrying vehicles may extinct in the future. Defence Science Journal, 2010, 60(5), pp.483-490 , DOI:http://dx.doi.org/10.14429/dsj.60.550

Development of Three-dimensional Grid-free Solver and its Applications to Multi-body Aerospace Vehicles

Abstract: Grid-free solver has the ability to solve complex multi-body industrial problems with minimal effort. Grid-free Euler solver has been applied to number of multi-body aerospace vehicles using Chimera clouds of points including flight vehicle with fin deflection, nose fairing separation of hypersonic launch vehicle. A preprocessor has been developed to generate connectivity for multi-bodies using overlapped grids. Surface transpiration boundary condition has been implemented to model aerodynamic damping and to impose the relative velocity of moving components. Dynamic derivatives are estimated with reasonable accuracy and less effort using the grid-free Euler solver with the transpiration boundary condition. Further, the grid-free Euler solver has been integrated with six-degrees of freedom (6-DOF) equations of motion to form store separation dynamics suite which has been applied to obtain the trajectory of a rail launch air-to-air-missile from a complex fighter aircraft. Defence Science Journal, 2010, 60(6), pp.653-662 , DOI:http://dx.doi.org/10.14429/dsj.60.583

Electrochemical Analysis of Natural Chemopreventive Agent (Curcumin) in Extracted Sample and Pharmaceutical Formulation (Short Communication)

Abstract: Curcumin has anti-oxidative and anticarcinogenic activities. This study shows the electrochemical behaviour of curcumin using polarography, i.e., DC polarography and differential pulse polarography (DPP) methods. In ammonium tartrate as supporting electrolyte, the differential pulse polarogram of curcumin shows two conjugated peaks with peak potential ( Ep ) -1125 mV and -1275 mV vs SCE. However, the direct current polarogram shows only one polarographic wave with E1/2 which was -1275 mV. The developed electrochemical methods have been standardised for the determination of curcumin in extracted sample of natural origin and its pharmaceutical formulation. The electrochemical analysis has been supplemented by ultraviolet and infrared spectral analyses of the samples. Defence Science Journal, 2010, 60(3), pp.255-258 , DOI:http://dx.doi.org/10.14429/dsj.60.351

Least squares Kinetic Upwind Mesh-free Method

Abstract: Least squares kinetic upwind mesh-free (LSKUM) method has been the subject of research over twenty years in our research group. LSKUM method requires a cloud (W) of points or nodes and connectivity N(P 0 ) for every 0 P ˛W. The connectivity of P 0 is a set of neighbours 0 () i PN P ˛ of P 0 . The cloud can be a simple cloud, Cartesian cloud or chimera cloud or can be obtained rapidly using advancing front method. The discrete approximation to spatial derivatives was obtained using of least squares and it can be made accurate using defect correction method. The LSKUM first operates on the Boltzmann level and then passes on to Euler or Navier-Stokes level by taking suitable moments (so called y moments) of the Boltzmann equation of kinetic theory of gases. The upwinding in LSKUM method is enforced by stencil or connectivity splitting based on the signs of v 1 , v 2 in 2-D and v 1 , v 2 , v 3 in 3-D. This leads to split fluxes encountered in Kinetic Flux Vector Splitting (KFVS) method. The higher-order accurate LSKUM method can be made more efficient using entropy variables, thus leading to q-LSKUM method. Lastly, boundary conditions are implemented using specular reflection model on the wall (KCBC method) and by using kinetic outer boundary condition (KOBC) method for a point on the outer boundary.

Feature Extraction by Wavelet Decomposition of Surface

Abstract: The paper presents a new approach to surface acoustic wave (SAW) chemical sensor array design and data processing for recognition of volatile organic compounds (VOCs) based on transient responses. The array is constructed of variable thickness single polymer-coated SAW oscillator sensors. The thickness of polymer coatings are selected such that during the sensing period, different sensors are loaded with varied levels of diffusive inflow of vapour species due to different stages of termination of equilibration process. Using a single polymer for coating the individual sensors with different thickness introduces vapour-specific kinetics variability in transient responses. The transient shapes are analysed by wavelet decomposition based on Daubechies mother wavelets. The set of discrete wavelet transform (DWT) approximation coefficients across the array transients is taken to represent the vapour sample in two alternate ways. In one, the sets generated by all the transients are combined into a single set to give a single representation to the vapour. In the other, the set of approximation coefficients at each data point generated by all transients is taken to represent the vapour. The latter results in as many alternate representations as there are approximation coefficients. The alternate representations of a vapour sample are treated as different instances or realisations for further processing. The wavelet analysis is then followed by the principal component analysis (PCA) to create new feature space. A comparative analysis of the feature spaces created by both the methods leads to the conclusion that both methods yield complimentary information: the one reveals intrinsic data variables, and the other enhances class separability. The present approach is validated by generating synthetic transient response data based on a prototype polyisobutylene (PIB) coated 3-element SAW sensor array exposed to 7 VOC vapours: chloroform, chlorobenzene o-dichlorobenzene, n-heptane, toluene, n-hexane and n-octane. Defence Science Journal, 2010, 60(4), pp.377-386 , DOI:http://dx.doi.org/10.14429/dsj.60.494

Modelling and Simulation of Pseudolite-based Navigation: A GPS-independent Radio Navigation System

Abstract: The use of global positioning system (GPS) for precision guidance of weapons is being questioned due to its vulnerability of jamming and spoofing for non-military code users. In this paper a novel approach is proposed for guidance of weapons where use of GPS or other civilian Satellite-based navigation system is threatened. The proposed approach is modelled and simulated using SIMULINK for realistic trajectories and scenario. The results of simulation are validated with the actual GPS data.

Battlefield Lasers and Opto-electronics Systems (Review Paper)

Abstract: During the last four decades or so, there has been an explosive growth in commercial, industrial, medical, scientific, technological, and above all, military usage of laser devices and systems. In fact, lasers have influenced every conceivable area of application during this period. While the expansion of non-military application spectrum of lasers is primarily driven by emergence of a large number of laser wavelengths followed by ever increasing power levels and reducing price tags at which those wavelengths could be generated, the military applications of lasers and related electro-optic devices have grown mainly because of technological maturity of the lasers that were born in the late 1960's and the early 1970's. Lasers have been used in various military applications since the early days of development that followed the invention of this magical device. There has been large scale proliferation of lasers and opto-electronic devices and systems for applications like range finding, target designation, target acquisition and tracking, precision guided munitions, etc. during 1970's and 1980's. These devices continue to improve in performance and find increased acceptance and usage in the contemporary battlefield scenario. Technological advances in optics, opto-electronics, and electronics, leading to more rugged, reliable, compact and efficient laser devices are largely responsible for making these indispensable in modern warfare. Past one decade or so has seen emergence of some new potential areas of usage. Some of these areas include rapid growth in the usage of lasers and opto-electronics devices and systems for electrooptic countermeasure (EOCM) applications, test and evaluation systems that can perform online functionality checks on military opto-electronics systems and also their interoperability. In this paper, an overview of the current and emerging military applications of lasers and opto-electronics systems has been given with an outline on the likely trends leading to performance enhancement of the existing systems and emergence of new application areas. Also, a brief on the developmental activity in the field of laser and opto-electronics devices and systems at Laser Science and Technology Centre (LASTEC), Delhi has been given. Defence Science Journal, 2010, 60(2), pp.189-196 , DOI:http://dx.doi.org/10.14429/dsj.60.339

Computational Fluid Dynamics in Hypersonic Aerothermodynamics

Abstract: Hypersonic flows are characterised by high Mach number and high total enthalpy. An elevated temperature often results in thermo-chemical reactions in the gas, which p lay a major role in aerothermodynamic characterisation of high-speed aerospace vehicles. Hypersonic flows in propulsion components are usually turbulent, resulting in additional effects. Computational simulation of such flows, therefore, need to account for a range of physical phenomena. Further, the numerical challenges involved in resolving strong gradients and discontinuities add to the complexity of computational fluid dynamics (CFD) simulation. In this article, physical modelling and numerical methodology-related issues involved in hypersonic flow simulation are highlighted. State-of-the-art CFD challenges are discussed in the context of two prominent applications-the flow in a scramjet inlet and the flow field around a re-entry capsule. Defence Science Journal, 2010, 60(6), pp.663-671 , DOI:http://dx.doi.org/10.14429/dsj.60.604