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| 1 |
ID:
141879
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| Summary/Abstract |
Simulation and experimental results at 35 GHz, for a single target of unit reflectivity, a concrete pillar and a gun shaped object placed in the central region of 2-D scene , have been presented using circularly co-located transmit and receive co-arrays. Simulation program has been written in MATLAB to reconstruct the raw image using an improvised algorithm. Simulation and experimental results confirm the method of reconstruction of image. Reconstruction of a Gun-shaped object has also been shown with help of simulation and experimental results. Reconstruction of image has been performed using post data acquisition processing on the received scattered data. Experimental results confirm that the method can be used to reconstruct quality image for detection of concealed metallic objects using MM wave frequencies.
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| 2 |
ID:
141878
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| Summary/Abstract |
Standoff detection of concealed threat, using millimeter wave radiometer, is being experimented worldwide for enhancing the frame rate and detection probability, as an alternative to personnel frisking, for enhancing passenger service rate and avoiding exposure to harmful radiations. The development of 94 GHz Dicke radiometer and experimentation to bench mark its operational parameters like spatial sampling rate, scan rate and dwell time for the detection of concealed threat, under the fabrics of a human is described. The experimentation provided operational methodology and imaging phenomenology in a given background for the detection of metallic threats. The experimental results have established that radiometer can be considered as an alternate to frisking of personnel and celebrities at public places for security reasons.
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| 3 |
ID:
141887
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| Summary/Abstract |
In a global positioning system receiver, the tracking algorithm plays a dominant role since the code delay and Doppler frequency shift need to be accurately estimated as well as their variation over time need to be continuously updated. Combine unscented Kalman filter (UKF) with CM/CL signal to improve the signal tracking precision is proposed. It allow weighting assignment between CM code and CL code incoming signal, masked by a mass of noise, and to describe a UKF tracking loop aiming at decreasing numerical errors. UKF here involves state and measuring equations which calculate absolute offsets to adjust initial code and carrier phase then dramatically decrease the tracking error. In particular, the algorithm is implemented in both open space and jammed environment to highlight the advantages of tracking approach, by comparing single code and combined code, UKF and EKF tracking loop. It proves that signal tracking based on UKF, with low energy dissipation as well as high precision, is particularly appealing for a software receiver implementation.
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| 4 |
ID:
141888
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| Summary/Abstract |
An analog phase shifter based on distributed MEMS transmission line (DMTL) is designed for Ku band applications. Traditional RF MEMS phase shifter comprising 6 switches has limited phase shift of 37.75° due to instability region. A new concept of stopper is incorporated to achieve high phase shift. In the present paper, optimisation of the analog phase shifter is done to increase its phase shift upto 88.63°. Phase shift is a strong function of capacitance ratio which is increased from 1.75 to 2.95. The maximum operating voltage and mechanical resonant frequency for the phase shifter are 16 V and 8.3 KHz, respectively. The switching time is calculated to 56 μs. The simulated insertion loss of the phase shifter is -1.75 dB with return loss of -20.49 dB at 17 GHz. The simulated results are verified with analytical modelling which are in close match.
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| 5 |
ID:
141886
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| Summary/Abstract |
Map projections are mathematical methods for projecting spherical coordinates in the form of (φ, λ) to the map coordinates in the form of (X,Y) in Cartesian reference frame. Numerous methods for map projection have been derived and are being used for preparation of cartographic products. These map projections take into account specific position of the viewer on the datum surface for derivation of the map projections. A generic method for azimuthal map projection where the position of the viewer can be taken at an arbitrary point on the datum surface is derived. Using this generic method all the specific azimuthal map projections can be derived.
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| 6 |
ID:
141889
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| Summary/Abstract |
The efforts were made to improve the hot-pressing method of carbon/carbon (C/C) composite fabrication. The C/C composite was fabricated by hot-pressing the slurry moulded compact followed by carbonisation. The temperature and time shifts during hot-pressing were made in order to see their effect on the densification. Their effect was checked through visual inspection, density measurement, scanning electron microscope (SEM) analysis, and mechanical properties evaluation. The results showed that the temperature shift yielded in significant increase in the density after hot-pressing. Further, the density pick up instead of fall after carbonisation was noticed. The results further showed that the time shift too yielded in significant enhancement of density after hot-pressing and showed the pattern after carbonisation similar to the temperature shift. And also showed that the shifts of both temperature and time yielded in significant increase in density and moderate increase in mechanical properties.
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| 7 |
ID:
141874
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| Summary/Abstract |
Main battle tanks (MBTs) have always been in the heart of all military campaigns and have enabled armies to fight across the full spectrum of war. Countries need to consider the complex interactions between subsystems of MBTs in the decision phase of a design process or MBT acquisition. In order to define the interaction among the subsystems of ‘system of systems’, which is MBT system for this case, this study aims to determine the criteria and their sub criteria affecting MBT selection problem and to analyse the cause and effect relations among these criteria. The criteria and the complex interaction among them have been determined by consulting a group of experts. Because of multiple complex criteria interactions in MBT selection problem, decision making trial and evaluation laboratory (DEMATEL) method is used as a multiple criteria decision making method. DEMATEL method is applied on the main and the sub criteria separately to understand the cause and effect relations. The results show that Survivability main criterion has the strongest central role among the main criteria for MBT selection, while the followers are firepower, mobility and command and control (C2). It is also shown that, in terms of sub criteria for MBT selection, ballistic protection, a sub criterion of survivability main criterion, has the highest degree of influence over most of the other sub criteria. However, physical dimensions/silhouette, another sub criterion of survivability, is the most affected sub criteria. The top five sub criteria in terms of central role are determined as physical dimensions/silhouette, ballistic protection, power/weight ratio, ground pressure and suspension system.
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| 8 |
ID:
141881
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| Summary/Abstract |
The design of circularly polarised multiband poly fractal boundary microstrip antenna is proposed and experimentally studied. Initially the two orthogonal sides of the square patch are replaced with different fractal curves for circular polarisation (CP) radiation. Along the x and y axes, Minkowski and Koch fractal curves are employed. A 45° rotated poly fractal slot is embedded at the center of the fractal patch for triband CP operation. The indentation depths and indentation angles of the Minkowski and Koch fractal curves are optimised for better CP emission. The inserted fractal slot redistributes the current elements on the patch for tri band CP radiation. The measured 3-dB axial ratio bandwidths of the proposed antenna at 2.4 GHz, 3.4 GHz, and 5.8 GHz are 1.53 per cent, 0.81 per cent, and 1.62 per cent respectively, making it an able candidate for WLAN and Wi-MAX wireless applications.
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| 9 |
ID:
141885
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| Summary/Abstract |
Thermocouples have been extensively used for the measurement of temperature since the advent of seebeck effect. Numerous sensors have been developed for temperature measurement, yet measurement of high temperature flowing fluid has been a challenging task. For the measurement of static temperature the measuring device should travel with the fluid at the same speed without disturbing the flow, which is quite unrealistic. So indirect determination of static temperature of flowing fluid is done by using thermocouple exposed into the flowing fluid. Other sensors available for high temperature measurement may lead to problems like resistance in the flow path of fluid which changes the structural dynamics. Thin film thermocouple (TFTC) based on W-W26Re for super high temperature measurement has been investigated which can be used in missiles for surface temperature measurement of nozzle and rocket interior surface. TFTC does not cause disruption in the flow path with maintaining structural integrity. The W-W26Re thermocouple offers advantage of higher seebeck coefficient at high temperature i.e. above 750 K, and usability in vacuum, inert and hydrogen atmosphere. Zirconia Fiber has been proposed as insulation protection material over thermocouple. Modelling and simulation of the TFTC for the temperature range 300 K - 2900 K has been presented. FEA model using PDE has been presented to implement heat equation, current balance quation, Gauss theorem and Neumann boundary condition. The expected voltage production on exposed temperature gradient has been studied.
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| 10 |
ID:
141890
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| Summary/Abstract |
Citrate nitrate sol freeze dry synthesis of 2 atomic % neodymium ion doped Yttrium Aluminium Oxide (Nd:YAG) nanopowders was explored for the first time. Sol was prepared by dissolving nitrates of Al3+, Y3+ and Nd3+ keeping molar ratio to be 5: 2.94: 0.06. Total metal ion to citric acid ratio was optimised at 1 is to 0.25. Sol was freeze dried at -80 °C for 48 h. Dried mass thus obtained was calcined at 1000 °C for 2 h to give phase pure Nd:YAG as characterised by FTIR and XRD. Particles were in the size range of 35 nm - 50 nm with close to spherical morphology as observed by TEM. Nanopowder was compacted and sintered at 1700 °C for 5 h under 10-6 mbar followed by hot isostatic press at 1750 °C for 4 h under 200 MPa, to give 71 per cent transmission at 1064 nm indicating synthesis of well sinterable Nd:YAG nanopowders.
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| 11 |
ID:
141875
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| Summary/Abstract |
The technical diagnostics of 125 mm tank cannon 2A46 smooth barrel and ramming devices are discussed respectively. Focuses on barrel diagnostics and suggests new procedures based on reconstructed BG20 Gun Barrel Bore Gauge System, measuring internal diameter of the barrel bore. The new system measures throughout the whole barrel bore the inner diameter not only at the beginning of barrel bore as it was usually measured before. Different nature of barrel wear was revealed between barrels firing sub-calibre and high explosive projectiles. A method for ramming device diagnostics is presented. An accurate method was proposed, determining projectile extraction force from barrel, as one of the main ramming device parameters for weapons that are used in all areas of armed forces. Results are based on experimental methods assessing the extraction forces from barrel after projectile loading. These tests were performed as a series of tests with consequent technical diagnostics according to the new Czech Defence Standards (derived from NATO standards). The results are presented as the new methodologies for diagnostics of 125 mm barrel 2A46 and ramming devices of tank T-72 for use by technical logistic units in the Czech Republic Armed Forces.
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| 12 |
ID:
141876
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| Summary/Abstract |
On the basis of an analysis of terrorist attacks carried out worldwide, where in recent years a preference for the use of bulk explosives placed in vehicles prevails, effective protection against these malicious explosive-containing systems that have a single goal - to cause death and significant material damage in a large radius is dealt. These improvised explosive devices are, in pyrotechnical terms, ranked as one of the most effective weapons, with a highly destructive character of explosive effect. A special water shaped charge that is able to destructively disassemble a bomb without initiation has been developed as an effective invasive means of eliminating similarly designed terrorist explosives hidden in cars, a condition which allows for considerable variation in location.
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