Defence Science Journal
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DRDO and Expectations of Stakeholders
Get PDFDRDO is India’s major credible research and development organization that enables self-reliance and indigenisation of defence technologies and weapon systems to empower India in the emerging geo-political balance. The Organisation has its genesis in a technical inspection agency which over the years have transformed into a highly professional R&D organization with strong design and technology capabilities and skilled entrepreneurship to undertake development of state-of-the-art defence systems. DRDO driven R&D efforts have catalysed the growth of domestic defence and civilian industries in the country as well. The overarching endeavours of DRDO encompassing academia, private industry and Defence PSUs have helped in establishing a self-reliant defence industrial eco-system and collectively all have contributed in the Hon’ble Prime Minister’s vision of “skill development” and “Make-in-India”. Yet, DRDO’s struggle at the national level continues since Armed Forces continue to depend on imports for major acquisitions. Indigenous options have not always established themselves as the preferred options even when they are available. The acceptability of DRDO developed products remains at a low ebb. The question is what more DRDO should do to ensure the acceptability of the users? This study examines the evolution of the DRDO and whether over the years DRDO has done enough or should do more to increase its visibility, acceptability, credibility and respectability? And how DRDO should reposition itself beyond MoD/Armed Forces in the national and international context to fulfill the ambitions of the country to play global roles? This paper also discusses how building the brand “DRDO” may possibly help DRDO. 
Optimal Operating Depth Search for Active Towed Array Sonar using Simulated Annealing
Get PDFIn an active towed array sonar, it is important to find the optimal operation depth. Generally, the optimal depth can be chosen via numerical simulations for all sonar depths and this imposes great burdens of time and cost.In this paper, an efficient approach is proposed to find the optimal depth using the optimisation technique. First, the sonar performance function is newly defined as a measure of how well the active sonar might perform. This function depends on the properties of the ocean environment and the positions of sonar and underwater target. Then, the simulated annealing to find an optimal solution for maximising sonar performance is used. The optimised depth agrees well with the depth obtained from direct searching for all depths of source and receiver combinations, but its computational time is largely reduced
Low Frequency Broad Band Acoustic Propagation in Andaman Sea
Get PDFDuring November 2017, an active source seismic survey was performed in Andaman sea to study the acoustic propagation characteristics. High power low frequency acoustic signals generated by 20-air gun array onboard ORV Samudra Ratnagar were recorded from INS Sagardhwani at four different depths within 8 km ranges in shallow and deep waters. Low frequency sound levels were estimated using root mean square and power spectral values. Amplitude levels were analysed with respect to arrival time variation with frequency and is presented
Dimensions Selection Criteria of Stair shaped Slot for Obtaining the Wideband Response of CPDRA
Get PDFThe analysis of a circularly polarised (CP) dielectric resonator antenna (DRA) with the aperture coupled feeding technique is presented in this paper. Until now, the random techniques have been developed for obtaining the CP response in DRA. It is glaringly required to develop a fixed mathematical criterion for the selection of dimensions of the antenna structure. The criterion for selection of the stair-shaped slot dimensions, which is utilised for obtaining the CP response, is defined in this paper. The ranges of slot length ratios are investigated so that a wide CP bandwidth can be obtained. The antenna offers the 10-dB impedance of 58.62% (4.1 GHz - 7.5 GHz) and 3-dB axial ratio bandwidth of 40.86 per cent (4.26GHz - 6.385 GHz)
An Intelligent Reconnaissance Framework for Homeland Security
Get PDFThe cross border terrorism and internal terrorist attacks are critical issues for any country to deal with. In India, such types of incidents that breach homeland security are increasing now a day. Tracking and combating such incidents depends only on the radio communications and manual operations of security agencies. These security agencies face various challenges to get the real-time location of the targeted vehicles, their direction of fleeing, etc. This paper proposes a novel application for automatic tracking of suspicious vehicles in real-time. The proposed application tracks the vehicle based on their registration number, type, colour and RFID tag. The proposed approach for vehicle recognition based on image processing achieves 92.45 per cent accuracy. The RFID-based vehicle identification technique achieves 100 per cent accuracy. This paper also proposes an approach for vehicle classification. The average classification accuracy obtained by the proposed approach is 93.3 per cent. An integrated framework for tracking of any vehicle at the request of security agencies is also proposed. Security agencies can track any vehicles in a specific time period by using the user interface of the application
Novel Dual band SIW Filter Using Quad mode Cavity
Get PDFA dual-band bandpass substrate integrated waveguide (SIW) filter is proposed using a quad-mode cavity in this paper. First two degenerative modes (TE102 and TE201) with via perturbation give the first passband. The second passband is realised by using higher modes (side and diagonal modes of TE202) which are obtained by putting square slot at the center of the cavity. The square slot increases the frequency ratio of the center frequencies of first and second passbands. Moreover, orthogonal feed-lines are used in the proposed design to increase transmission zeros (TZs) which helps to improve the selectivity and out-of-band rejection of the filter. Designed and fabricated a dualband filter prototype using a single layer printed circuit board (PCB) technology, size is only 19 mm × 19 mm. The insertion losses are 2.1 dB and 2.4 dB, and fractional bandwidths of 3.40 per cent and 2.00 per cent at 11.00 and 15.58 GHz, respectively. The measurement results show close agreement with the simulation results
Effect of Fuel Distribution on the Onset of Detonation in Gaseous Octane Air Mixture
Get PDFFormation of detonation waves in a tube is a complex phenomenon and depends upon many factors like ignition energy, presence of a deflagration to detonation transition (DDT) enhancement device and spatial distribution of fuel, etc. In present study, gaseous octane-air mixtures have been examined by varying the equivalence ratio linearly along the axial direction of the detonation tube though the overall stoichiometry was maintained in the tube. Three different conditions have been modelled and studied, which includes small, moderate and large, fuel density gradient in axial direction with equivalence ratio ranging from 1 to 2 near the ignition zone. A series of simulation study have been conducted and the analysis of simulation results reveal that the DDT onset is significantly affected by the initial fuel distribution at the ignition zone as well as on fuel density gradient in a detonation tube. It has been observed thata moderate gradient in the fuel density distribution is favorable for onset of detonations. From the study of pressure plots for above mentioned conditions it has been found that the presence of large gradients in fuel density has adverse effect on the stability of detonation wave
Blast Wave Characteristics and TNT Equivalent of Improvised Explosive Device at Small scaled Distances
Get PDFA significant number of airblast test have been carried out with the purpose to characterise and analyse the properties of improvised explosive device (IED) with non-conventional explosives in terms of knowing the effects on people and/or structures. Small devices with 1.5 kg of explosive, initiated with a detonating cord have been studied. Seven different mixtures have been tested with two types of ammonium nitrate AN (technical and fertilizer) in different forms like prills or powder. In some cases, the ammonium nitrate has been mixed with fuel oil while in others, it has been mixed with aluminum. The TNT equivalent based on pressure, impulse, arrival time, positive phase duration and shock front velocity have been calculated and analysed for each mixture. Comparing the field test data obtained with respect to the representation of the UFC 3-340-02 values, it can be seen that the parameters measured are consistent. The IEDs with fertilizer ammonium nitrate do not detonate with the present charge conditions so the shockwave generated is only due to the detonating cord. When using the technical ammonium nitrate, ANFO can partially detonate and generate a potentially dangerous shockwave. Finally, the IED with AN and aluminum produces a TNT equivalent close to one when the technical AN is used
Chemical Protection Studies of Activated Carbon Spheres based Permeable Protective Clothing Against Sulfur Mustard, a Chemical Warfare Agent
Get PDFTechnological advancements in the field of chemical threat have made it possible to create extremely dangerous chemical warfare agents (CWA). Hence, the effective protection of personnel is very important in a chemical warfare scenario amidst the current climate of terrorism awareness. In particular, body protection plays a substantial role in the chemical defence considering the urgency of situation in the nuclear, biological and chemical environment. Activated carbon spheres (ACS) based permeable chemical protective clothing (coverall) was developed for protection against CWA. The adsorbent material i.e, ACS used in this protective clothing provided higher adsorption capacity (1029 mg/g in terms of iodine) and low thermal burden (34 °C WBGT index) compared to earlier indigenously developed NBC suit. This article focuses on the extensive evaluation of chemical protective clothing against sulfur mustard (HD), a CWA. The results revealed that the developed protective clothing provided more than 24 h protection against HD. This chemical protective suit is light weight (< 2.75 kg for XL size). It also has higher air permeability (> 30 cm3/s/cm2) as well as less water vapour resistance (< 9.6 m2Pa/W). With continued innovations in materials and attention to key challenges it is expected that advanced, multifunction chemical protective suit will play a pivotal role in the CWA protection scenario
Reliable Integrated Satellite Terrestrial Communications using MIMO for Mitigation of Microwave Absorption by Earths Oxygen
Get PDFMicrowaves are used to communicate with satellite and terrestrial communication networks. But as microwaves pass through the Earth’s atmosphere, the oxygen gas absorbs microwave. In this 5G era, when the whole world is moving towards high data-rates and reliable communications, this absorption affects the data transmission in Integrated Satellite/Terrestrial Communication (ISTC) systems, which leads to degradation of the system performance. The multiple-input-multiple-output (MIMO) technology has become a boon for modern wireless communication systems to achieve the necessities of higher data-rates and communication reliability. The paper analyses the MIMO effect on block error rate (BLER), error vector magnitude (EVM) and throughput performance of the data transmission with different MIMO configurations. The paper establishes that better data-rates as well as reliable data communication is achieved with higher order MIMO configurations. MIMO 8×1 provides 5, 20 and 42.5 times improved performance to BLER; 5.26%, 25% and 81.82% in throughput; and 10.34%, 23.07% and 28% in EVM calculations as comparable to MIMO 4×1, MIMO 2×1 and SISO 1×1, respectively at 15 dB signal-to-noise ratio (SNR). The authors also give a new concept of multi-cellular layers based mobile communication network, useful for future smart cities