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Modelling and Analysis of Emitter Geolocation using Satellite Tool Kit
Get PDFThis paper considers geolocation of a stationary radio frequency emitter which is being steered by multiple antennas installed on a geostationary satellite using received signal strength metric. The difference in the signal strengths is measured by the antennas and subsequently plotted as lines of position on the surface of the earth. Intersection of these two or more lines of position indicates the location of the terrestrial radio frequency transmitters. This problem is appropriately modelled using a satellite tool kit that simulates the space environment involving satellites, antennas, emitters, etc in a realistic and integrated manner. Accuracy and size of the geolocation area depend on the distance between emitters and the receiver and also on the contour widths geometry. Results of geolocation accuracy are compared by installing the radio frequency emitter at increasing latitudes and at varying contour widths. It is observed that the emitters placed at lower latitudes and having smaller contour widths provided higher accuracy in geolocation that validates the proposed formulation
Analysis and Prediction of Alerts in Perimeter Intrusion Detection System
Get PDFPerimeter surveillance systems play an important role in the safety and security of the armed forces. These systems tend to generate alerts in advent of anomalous situations, which require human intervention. The challenge is the generation of false alerts or alert flooding which makes these systems inefficient. In this paper, we focus on short-term as well as long-term prediction of alerts in the perimeter intrusion detection system. We have explored the dependent and independent aspects of the alert data generated over a period of time. Short-term prediction is realized by exploiting the independent aspect of data by narrowing it down to a time-series problem. Time-series analysis is performed by extracting the statistical information from the historical alert data. A dual-stage approach is employed for analyzing the time-series data and support vector regression is used as the regression technique. It is helpful to predict the number of alerts for the nth hour. Additionally, to understand the dependent aspect, we have investigated that the deployment environment has an impact on the alerts generated. Long-term predictions are made by extracting the features based on the deployment environment and training the dataset using different regression models. Also, we have compared the predicted and expected alerts to recognize anomalous behaviour. This will help in realizing the situations of alert flooding over the potential threat
Utilisation of Ram Air Turbine on a Fighter Platform for Energy Extraction Failure Mode Study
Get PDFAircraft electrical system needs to be robust enough to cater for electrical power requirements of all the systems of the aircraft and all the safety/degraded mission critical systems in failure modes. Designing such a robust electrical system for a developmental aircraft program is a challenge. A developmental aircraft during its various phases would involve integration of additional systems and new weapons (in case of fighter aircraft). Integration of newer systems imposes fresh challenges in managing the electrical system architecture especially in failure modes. Weapon integration in a prototype fighter program is dynamic as newer contemporary weapons are developed at faster pace and ever evolving. Power crisis through existing on-board power generation systems in failure mode was felt during an indigenous aircraft development program. A novel idea of introducing a Ram Air Turbine and utilize the power generated during main alternator failure for critical systems was studied. The intention of this paper is to cover the details of the study carried out towards utlisation of such a Ram Air Turbine in landing phase for extraction of energy in case of main alternator failure
Approximate Solution of Riccati Differential Equation via Modified Greens Decomposition Method
Get PDFRiccati differential equations (RDEs) plays important role in the various fields of defence, physics, engineering, medical science, and mathematics. A new approach to find the numerical solution of a class of RDEs with quadratic nonlinearity is presented in this paper. In the process of solving the pre-mentioned class of RDEs, we used an ordered combination of Green’s function, Adomian’s polynomials, and Pade` approximation. This technique is named as green decomposition method with Pade` approximation (GDMP). Since, the most contemporary definition of Adomian polynomials has been used in GDMP. Therefore, a specific class of Adomian polynomials is used to advance GDMP to modified green decomposition method with Pade` approximation (MGDMP). Further, MGDMP is applied to solve some special RDEs, belonging to the considered class of RDEs, absolute error of the obtained solution is compared with Adomian decomposition method (ADM) and Laplace decomposition method with Pade` approximation (LADM-Pade`). As well, the impedance of the method emphasised with the comparative error tables of the exact solution and the associated solutions with respect to ADM, LADM-Pade`, and MGDMP. The observation from this comparative study exhibits that MGDMP provides an improved numerical solution in the given interval. In spite of this, generally, some of the particular RDEs (with variable coefficients) cannot be easily solved by some of the existing methods, such as LADM-Pade` or Homotopy perturbation methods. However, under some limitations, MGDMP can be successfully applied to solve such type of RDEs
Effect of Nanographite on Electrical Mechanical and Wear Characteristics of Graphite Epoxy Composites
Get PDFEffect of weight fraction (WF) of nanographite (NG, 400 nm) on electrical, mechanical and wear and characteristics of graphite epoxy composites (GECs) were investigated. For this purpose, a series of GECs was prepared through dispersion of various WF of NG into epoxy resin, followed by curing with polyamine. Dispersion of NG into epoxy matrix and onward formation of GECs and was revealed through UV, Fourier transformed spectra and atomic force microscopy (AFM). Photoelastic analysis in combination with AFM reveals the presence of uniformly dispersed domain of NG into stress free GECs with fringe order ranging 0.23 - 0.61 under compression of 8 - 20 kgf. GECs have rendered a rising trend in DC conductance ranging 98.32 - 0.54 μS/cm with electrical percolation threshold at 175 WF of NG. GECs have shown enhanced compressive, impact, tensile, strength, Rockwell hardness and wear resistance at 200 WF of NG. In general, GECs has shown a marginal modification in their compressive strength by 5.30 % over cured epoxy. However, their impact and tensile strengths were largely improved to 31.78% and 43.98% over cured epoxy. The present manuscript provides a novel method of modification in electrical, mechanical and wear behaviour epoxy through introducing NG as a novel alternative to traditionally used graphite as filler for development of GECs
Femtosecond Filaments for Standoff Detection of Explosives
Get PDFIn this report, we present our results from various studies to qualitatively discriminate the common military explosives viz. RDX, TNT and HMX in their pure form at a distance of ~6.5 m in standoff mode using femtosecond (fs) filament induced breakdown spectroscopy technique (fs FIBS) together with principal component analysis. A ~30 cm length fs filament obtained by a two-lens configuration was used to interrogate those energetic molecules in the form of pressed pellets (150 mg each). The plasma emissions were collected by a Schmidt-Cassegrain telescope (SCT) from a distance of ~8 m away from the investigation zone. Additionally, a few significant results obtained from the LIBS-based investigations of nitroimidazoles with respect to the standoff distance (~2 m) are discussed. Furthermore, we have also summarised a few important results from our recent investigations of bulk energetic materials in various configurations (including those with fs filaments). The results obtained from various fs FIBS configurations corroborate that the filament generation and its properties, the size and f-number of collection optics influence signal strength in the FIBS technique. These results project the fs FIBS technique as a potential technique for investigations aimed at hazardous materials and harsh environments in the standoff mode
Power Spectral Density Computation and Dominant Frequencies Identification from the Vibration Sensor Output under Random Vibration Environment
Get PDFThe objective of the modal and spectral analysis is to determine the vibration characteristics of structures such as natural frequencies, dominant frequencies and mode shapes. Such modal and spectral analyses have major relevance to the study of the dynamic properties of the structures undergoing dynamic vibration. Methods for the estimation of the power spectral density and identification of the dominant frequencies from the sensor responses under random vibrating environment are presented in this paper. Periodogram using FFT, Welch Method and MUSIC algorithm are used to analyse the known frequency sinusoids with additive white noise and output of the vibration sensor mounted on the test object. The resultant spectra obtained using the methods and their corresponding errors with the reference spectrum are analysed. The Welch method is further studied with three different windows, namely, Hann, Hamming and Blackman-Harris and with three different overlapping criteria viz. 0%, 25% and 50%. The same algorithm and methodology were adopted and compared in two different platforms: Mathematical Model Simulation and Hardware-In-Loop-Simulation. It is observed from the results that Welch Method with 25% overlap used in combination either with Hann or Blackman-Harris window yields more accurate results, compared to other combinations. Also, 25% overlap provides better execution time trade-off compared to 50% overlap
Study on High Energy Propellant Waste in the Processing of Fired Clay Bricks
Get PDFUtilisation of propellant waste in fabrication of bricks is not only used as efficient waste disposal method but also to get better functional properties. In the present study, high energy propellant (HEP) waste additive mixed with soil and fly ash in different proportions during manufacturing of bricks has been investigated experimentally. X-ray diffraction (XRD) studies were carried out to confirm the brick formation and the effect of HEP waste. Ceramic bricks were fabricated with HEP waste additive in proper proportions i.e. 0.5 wt %, 1.0 wt %, 1.5 wt %, 2.0 wt %, 2.5 wt %, 3 wt %, 3.5 wt %, and 4 wt % and then evaluated for water absorption capability and compressive strength. Compressive strength of 6.7 N/mm2, and Water absorption of 22 % have been observed from modified fired bricks impregnated with HEM waste additive. Scanning electron microscopy (SEM) studies were carried out to analyze the effect of HEP waste additive on pore formation and distribution in the bricks. Further, the heat resulting from decomposition of propellants can cause a decrease in the energy required of baking process. The process of manufacturing of bricks with HEP waste additive is first of its kind till date
Model Driven Combat Effectiveness Simulation Systems Engineering
Get PDFModel-driven engineering has become popular in the combat effectiveness simulation systems engineering during these last years. It allows to systematically develop a simulation model in a composable way. However, implementing a conceptual model is really a complex and costly job if this is not guided under a well-established framework. Hence this study attempts to explore methodologies for engineering the development of simulation models. For this purpose, we define an ontological metamodelling framework. This framework starts with ontology-aware system conceptual descriptions, and then refines and transforms them toward system models until they reach final executable implementations. As a proof of concept, we identify a set of ontology-aware modelling frameworks in combat systems specification, then an underwater targets search scenario is presented as a motivating example for running simulations and results can be used as a reference for decision-making behaviors