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An Algorithm for Exchanging Target Asset Pairs using the Kidney Exchange Model
Get PDFSince chemical, biological, radiological, nuclear, and high yield explosive (CBRNE) attacks can cause catastrophic damage, it is important to detect and eliminate the means of attack at the origin. In surveillance operations, efficient allocation of friendly intelligence assets and enemy targets is critical for continuous and reliablemonitoring. In this research, we investigate a mathematical model for exchanging target–asset pairs when there are sudden changes in various operational environments. For this task, we refer to the kidney exchange model as a benchmark. In particular, the methods for constructing and solving the target–asset exchange problem in near realtime are presented. Additionally, we introduce the methodology and results for obtaining a feasible solution of the weapon target assignment problem using the exchange model. Our method can facilitate decisions in reconnaissance operations, especially when countless targets and assets are intricately intertwined in future battlefield scenarios
A Effect of Radial Clearance, Corner Radius and Micro Lateralization on Contact Stress of Metallic and Ceramic Hip Prosthesis
No full textEdge loading leads to high contact stress at the rim of the contact. This is due to less radial clearance and excessive lateral head displacement which potentially causes implant failure. The ceramic implants have a high possibility of fracture compared with metallic implants because of above-said reasons. The present study focuses on the investigation of contact stress for the combined effect of radial clearance (0.05-0.75 mm) and micro-lateralisation conditions (1-2.5 mm) for Metal-on-Metal (M-o-M) and Ceramic-on-Ceramic (C-o-C) pairs. The contact stresses are analysed for round corners of the acetabulum cup geometry for the above-said combinations with four different arc radii (1- 4mm). Finite element modeling (FEM) of femur head with half of the acetabulum cup is considered for the current study. Contact stress values obtained for 2 mm and 4 mm round corner geometry are quite low when compared with 1 and 3 mm round corners even for larger radial clearances and high lateral head displacements. The study also showed von Mises stress value obtained for M-o-M pair is quite low for 4 mm round corner for larger radial clearance and high lateral head displacements. Similarly, in C-o-C pair the compressive stress values are minimum for 4 mm round corner. Since the stress values were minimum for 4 mm round corner geometry, it clearly indicates that even edge loading occurs and the round corner geometry would be very helpful in reducing the stress for both M-o-M and C-o-C pairs
Error Estimation of Measured Exhaust Gas Temperature in Afterburner Mode in an Aero Gas Turbine Engine
Get PDFIn a turbofan engine, thrust is a key parameter which is measured or estimated from various parameters acquired during engine testing in an engine testbed. Exhaust Gas Temperature (EGT) is the most critical parameter used for thrust calculation. This work presents a novel way to measure and correct the errors in EGT measurement. A temperature probe is designed to measure EGT in the engine jet pipe using thermocouples. The temperature probe is designed to withstand the mechanical and temperature loads during the operation. Structural analysis at the design stage provided a strength margin of 90% and eigenfrequency margin of more than 20%. Thermal analysis is carried out to evaluate maximum metal temperature. Errors are quite high in high-temperature measurements which are corrected using the available methodologies. The velocity error, conduction error, and radiation error are estimated for the measured temperature. The difference of 97 K between the measured gas temperature and calculated gas temperature from measured thrust is explained. The estimated velocity error is 1 K, conduction error is 3 K, and radiation error is 69 K. Based on the error estimation, the measurement error is brought down to 24 K. After applying the above corrections, the further difference of 24 K between measured and estimated value can be attributed to thermocouple error of +/-0.4% of the reading for class 1 accuracy thermocouple, other parameter measurement errors, and analysis uncertainties. The present work enables the designer to calculate the errors in high-temperature measurement in a turbofan engine
High Speed Machining for Enhancing the AZ91 Magnesium Alloy Surface Characteristics Influence and Optimisation of Machining Parameters
Get PDFIn this study, optimum machining parameters are evaluated for enhancing the surface roughness and hardness of AZ91 alloy using Taguchi design of experiments with Grey Relational Analysis. Dry face milling is performed using cutting conditions determined using Taguchi L9 design and Grey Relational Analysis has been used for the optimization of multiple objectives. Taguchi’s signal-to-noise ratio analysis is also performed individually for both characteristics and grey relational grade to identify the most influential machining parameter affecting them. Further, Analysis of Variance is carried to see the contribution of factors on both surface roughness and hardness. Finally, the predicted trends obtained from the signal-to-noise ratio are validated using confirmation experiments. The study showed the effectiveness of Taguchi design combined with Grey Relational Analysis for the multi-objective problems such as surface characteristics studies
A Distance Vector Hop and Differential Evolution based Interception Strategy for detecting Cross Border Infiltration in Underground Tunnel
No full textSecuring the external border of a nation through potential surveillance is considered to be highly essential for safeguarding them from terrorists and other national armies that intentionally try to conquer regions. The infiltration of trespassers and terrorists into a territory is considered to greatly influence the harmony and peace of a nation. In this context, conventional border surveillance systems safeguard the border regions based on the pre-determined routes at various time intervals. However, the intensive involvement of human in patrolling is determined as the major challenge in the process of safeguarding longer border areas. Moreover, detecting the infiltration of terrorists through the underground tunnel is considered to be the other challenge. At this juncture, wireless sensor networks are considered to be the best suitable candidate for safeguarding the external borders through real-time monitoring to attain maximized accuracy, efficiency in the detection and least human intervention. In this paper, Distance Vector-Hop (DV-Hop) and Differential Evolution (DE)-based Interception Strategy (DV-Hop-DE-IS) is proposed for accurate detection of cross border infiltration in the underground tunnel. This proposed DV-Hop-DE-IS includes the merits of converting the discrete values of hop count into a highly accurate continuous value depending on the information received from the number of shared one-hop nodes that exists between neighbouring nodes. This problem of intruder detection is formulated as the minimum optimization problem that could be optimally solved through the utilization of the Differential Evolution algorithm with maximized efficiency. The simulation results of the DV-Hop-DE-IS confirmed better detection rate, accuracy with a reduced false positive rate compared to the benchmarked intruder detection approaches
Common Bulkhead Tank Design for Cryogenic Stage of an Indian Launch Vehicle
Get PDFIndian Space Research Organization (ISRO) has been advancing in space technology with its cost-effective techniques. Currently, ISRO, in its cryogenic stages, uses truss type intertank structure, which induces large concentrated loads at the truss interfaces. As a remedial measure, works on closed intertank are being carried out by them, but this configuration will considerably increase the launch vehicle mass compared to truss type. Therefore, after a thorough literature survey, a Common bulkhead (CBH) tank seemed to be the best solution to the aforementioned problem. Detailed research on sandwich-type CBH has been carried out in this paper with the motivation of saving mass and height in launch vehicles. Suitable core and facesheet material were selected. A novel foam-filled honeycomb core is suggested in this work. Several comparisons in various CBH dome designs were carried out to reach for the best possible configuration and composition that can be used. MATLAB®, SolidWorks®, and ANSYS® were used in parallel for all computations dealing with design and analysis. A mass saving of approximately upto 490 kgs and a height reduction of upto 1.755 m was obtained with the final selected configuration with respect to the current GSLV configuration. These savings can add extra payload capacity to ISRO launch vehicles in their future missions
A Tool for Supporting Conceptual Design of Multiple State Mechanical Devices
Get PDFResearch into conceptual design of mechanical systems has evolved as an area of interest since last few decades. Conceptual design plays a significant role as an early stage of design to produce designs with higher quality by economically exploring a larger solution space. Several attempts have been made by researchers to automate the conceptual design synthesis process using computer support. However, most of that work has been focused on single state design problems. This paper deals with multiple state mechanical design problems and proposes a systematic method for synthesizing a larger solution space. A web-based tool is developed to guide designers through the step-by-step synthesis process by providing automated retrieval of initial solution proposals and modification rules
Flight Planning Tool an Aid for Efficient Flight Evaluation
Get PDFAirborne surveillance systems have multiple sensors and communication links on board a suitable platform. They work in a cohesive manner to provide effective surveillance over the region of interest. The performance proving of such a system is challenging and requires flight trails extending over years. The test results often have to be interpreted using statistical analysis of the flight test data. An efficient way is to carefully design the flight test profiles such that enough samples can be collected during the test and multiple requirements can be tested in a single sortie. Such meticulous test strategies where both own ship platform and test targets are moving with high dynamics call for software based tool for planning of test sorties and the test points. Flight Planning Tool (FPT) plays an important role in pre-flight stage during developmental trials for analysis of the MOEs and MOPs of overall system and of various on-board sensors of an airborne multi-sensor system. The FPT provides statistical & graphical analysis for sensor behaviour for various scenarios (flight trials) before actual flight test is conducted. It provides prior information on number of valid samples for sensor testing during flight trials. In addition, the tool aids in assessing number of profiles to be flown for proving each MOE. The profiles can also be optimised such that valid samples are collected for evaluation
The Complete Analytical Solution of the TDOA Localization Method
Get PDFThis article is focused on the analytical solution of a TDOA (Time Difference of Arrival) localization method, including analysis of accuracy and unambiguity of a target position estimation in 2D space. The method is processed under two conditions - sufficiently determined localization system and an overdetermined localization system. It is assumed that the TDOA localization system operates in a LOS (Line of Sight) situation and several time-synchronized sensors are placed arbitrarily across the area. The main contribution of the article is the complete description of the TDOA localization method in analytical form only. It means, this paper shows a geometric representation and an analytical solution of the TDOA localization technique model. In addition, analyses of unambiguity and solvability of the method algorithm are presented, together with accuracy analysis of this TDOA technique in analytical form. Finally, the description of this TDOA method is extended to an overdetermined TDOA system. This makes it possible to determine and subsequently optimize its computational complexity, for example increase its computational speed. It seems that such a description of the TDOA localization technique creates a simple and effective tool for technological implementation of this method into military localization systems