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Genetic Algorithm Optimisation of a TNT Solidification Model
Get PDFThe control of the solidification process of energetic materials is important to prevent manufacturing defects in high explosive ammunitions. The present work aims to propose an optimisation procedure to determine the value of the model parameter, avoiding the traditional trial and error approach. In this work, the solidification of TNT has been numerically modelled employing apparent heat capacity method and the model parameter was optimised using genetic algorithm. One dimensional numerical model has been solved in Comsol Multiphysics Modeling Software and the genetic algorithm code was written in Matlab. The Neumann’s analytical solution of the solidification front was used as a reference to build the fitness function, following the inverse problems concepts. The optimum model parameter has been predicted after 20 generations and among 30 candidate solutions for each generation. The numerical solution performed with the optimised model parameter has agreed with the analytical solution, indicating the feasibility of the proposed procedure. The discrepancy was 3.8 per cent when maximum difference between analytical and numerical solutions was observed
A Modulation Technique for Sensorless Control of Switched Reluctance Motor
Get PDFThe switched reluctance motor (SRM) uniquely bears several merits with respect to other motor configurations. Especially, the construction of the rotor is simple in the sense that it neither contains copper not contains permanent magnets. Because of this construction, likelihood of rotor’s failure is less than the other motor configurations. This makes this motor more suitable for harsh environments. On the flip side, this motor cannot directly operate with AC or DC power source and needs electronic commutation. For commutation, the information on instantaneous orientation of the rotor is essential. Since inclusion of appropriate sensor adds to the cost and complexity of the system, sensor-less commutation of SRM gained interest among the researchers and has been studied extensively in literature. The techniques for sensorless control of SRM can be broadly classified into Active phase and Idle phase techniques. Idle phase techniques are generally believed to be not suitable for high speed operation beause of tail current in a phase, i.e., because of inductive nature of the phase, it takes time for flow of current to stop. This paper proposes a novel idle phase technique that is conducive for high speed operation of switched reluctance motor
Vetronics Architecture with in vehicle Networking
Get PDF The effectiveness of combat and combat support vehicles platforms can be improved significantly by incorporating Vetronics concept at the platform design stage itself which allows on-board systems to be interconnected as networks and enables them not only to share the information with-in the platform but also with the neighbouring platforms. The Vetronics concept not only optimises the on-board computing resources and other electronic sub-systems, also aids in easier platform integration. The Vetronics architecture with in-vehicle networking can be conceived and optimised based for vehicle type, requirement of types of systems envisaged for integration and having a balance between standard and customised components. The conceptual architecture proposed in this paper brings out the benefits offered by Vetronics approach for integration of on-board sub-systems thereby enhancing the platform effectiveness and Battlefield Management System for in-service and futuristic platforms considering the space as one of the major constraints. The proposed concept is adaptable, flexible and scalable enabling integration of the various electronic sub-systems
An Analytical Approach to Design Camouflage Net for Microwave Absorption
Get PDFMicrowave absorption has been the key for reduction of radar cross section in the field of stealth technology. In this field, hiding troop details from reconnaissance systems is taken care by enhancing absorption properties of the material. The demand of masking detectable equipment can be met with the help of a flexible net type structure called camouflage net. Optimising and measuring the absorption of the net, comprising of cloth and coating of the radar absorbing materials over the cloth is very challenging task. The task is being accomplished by using trial and error method, which is very cumbersome process and leads to tremendous waste of potential, material and manpower. Therefore, an attempt to develop an analytical methodology using the permittivity and permeability of the fabric material, to minimise this limitation, has been presented in this paper by critically analysing simulated results for various composites. The approach seems to have good potential for developing the camouflage net, especially in the microwave regime
Substrate Integrated Waveguide fed Wideband Circularly Polarised Antenna with Parasitic Patches
Get PDFIn this study, a wideband circularly polarised (CP) antenna is developed and demonstrated. The antenna comprises of two-layered substrates, the top layer holds a driven patch and eight surrounding parasitic patches of similar dimensions, and substrate integrated waveguide (SIW) based feeding topology is designed at the bottom layer. The driven patch is excited through coupling mechanism using a cross-slot carved on the upper clad of the SIW. The corners of the driven patch are curtailed and arms of the coupling slot made unequal, which constructively generates the CP wave. Moreover, the proposed antenna is prototyped, and experimentally verified. The antenna shows measured impedance and axial-ratio (AR) bandwidths of 1.29 GHz (21 per cent) and 460 MHz (7.35 per cent), respectively, while maintaining the high gain of ~8 dBic over the operating CP region. This design aids the favorable characteristics such as light weight, wide impedance and (AR) bandwidths, high-gain as well as lenience of production, and integration
Assessing the Performance of Nano Lubricant on Zinc Aluminium Alloy
Get PDFIn the field of tribology, Zinc Aluminium (ZA) alloys have been widely investigated for their superior wear characteristics. They were found to be suitable alternatives for bearing bronzes for the operating conditions of high mechanical load and moderate sliding speeds. Addition of nano-particles in the lubricating oil (base oil) to enhance the characteristics of the base oil is known as nano lubrication. In this study, sliding wear behaviour of ZA27 was investigated under dry, base oil and nano oil lubrication conditions, by varying load, sliding distance and sliding speed. With the base oil as SAE 40, nano graphite was added in two step method which was further used to identify the lubrication regime under different lubrication conditions. From the limited study of single melt samples, the results appear that the wear behaviour of ZA27 alloy improved under nano lubrication conditions with reduction in operating temperature. It could be observed from SEM images that the presence of nano-particles reduced scarring and wear, leading to enhancement in the tribological performance of ZA27 alloy
Device Free Localisation Techniques in Indoor Environments
Get PDFThe location estimation of a target for a long period was performed only by device based localisation technique which is difficult in applications where target especially human is non-cooperative. A target was detected by equipping a device using global positioning systems, radio frequency systems, ultrasonic frequency systems, etc. Device free localisation (DFL) is an upcoming technology in automated localisation in which target need not equip any device for identifying its position by the user. For achieving this objective, the wireless sensor network is a better choice due to its growing popularity. This paper describes the possible categorisation of recently developed DFL techniques using wireless sensor network. The scope of each category of techniques is analysed by comparing their potential benefits and drawbacks. Finally, future scope and research directions in this field are also summarised
Cellular Automata with Synthetic Image A Secure Image Communication with Transform Domain
Get PDF Image encryption has attained a great attention due to the necessity to safeguard confidential images. Digital documents, site images, battlefield photographs, etc. need a secure approach for sharing in an open channel. Hardware – software co-design is a better option for exploiting unique features to cipher the confidential images. Cellular automata (CA) and synthetic image influenced transform domain approach for image encryption is proposed in this paper. The digital image is initially divided into four subsections by applying integer wavelet transform. Confusion is accomplished on low – low section of the transformed image using CA rules 90 and 150. The first level of diffusion with consecutive XORing operation of image pixels is initiated by CA rule 42. A synthetic random key image is developed by extracting true random bits generated by Cyclone V field programmable gate array 5CSEMA5F31C6. This random image plays an important role in second level of diffusion. The proposed confusion and two level diffusion assisted image encryption approach has been validated through the entropy, correlation, histogram, number of pixels change rate, unified average change intensity, contrast and encryption quality analyses
Development of Optimal Thresholding Technique for Shape and Size Detection for Through the wall Radar Imaging System
Get PDFThrough-the-wall radar (TWR) images of stationary target behind a wall are subject to strong stationary and non-stationary clutter which obscures the target position and size in the image. Stationary clutters are present due to strong reflection from the wall and non-stationary clutter occurs due to multipath, noise, etc. A lot of work has been reported for mitigating stationary clutter successfully for various real scenarios. However, for mitigating nonstationary clutter various authors have reported their work in this field but any concrete result has not been reported so far. Hence, there is a need for an optimal methodology to mitigate non-stationary clutter in TWR images for achieving a high-quality image representing the target position, shape and its size. Till now it is difficult to achieve shape detection of the target from the TWR system. Therefore, in this paper, a novel optimal thresholding technique is proposed to mitigating non-stationary clutter for further enhancement on shape detection of a target using curve fitting and genetic algorithm. The proposed methodology gives a satisfactory result and can prove to be a powerful technique for minimising clutter
Total Radiated Power Measurement in an Uncalibrated Reverberation Chamber
Get PDFWith the increased use of wireless communication in recent years, the use of reverberation chamber (RC) has increased to a great extent. Reverberation chambers have been eminently used for EMC testing and shielding effectiveness. The environment it provides is very similar to the reverberant surroundings that antenna undergoes in real life use. An experiment to measure total radiated power of antenna, antenna efficiency and quality factor of chamber in indoor environment is proposed. This will make the measurement very simple and inexpensive as designing and calibration of chamber will not be needed. In this paper, we have used three different techniques to compare total radiated power, quality factor, Rician K factor and efficiency of a patch antenna measured in indoor environment with RC data. The three method used include plate stirring method and two time domain methods. The time domain methods use modulated pulse and Gaussian pulse respectively for the measurement. The antenna and chamber parameters are measured in the real time and the data matched well with the RC data for different techniques