Current Trends in Tactical Missile Guidance

The problem of tactical missile guidance is very challenging and has been treated using several basic metlfodologies in the past four decades. Major techniques can be grouped underclassical guidance laws, modern guidance laws, l'aws for manoeuvring targets, predictive guidance for endgame scenario, and guidance laws based on intelligent control methods. Each technique has some advantages and disadvantages while implementing in a practical system. Guidance law selection is dictated by nature of flight profile like boost, midcourse, terminal homing, etc, and also miss-distance and a single-shot kill probability. This paper presents a brief survey of the existing techniques and current trends in tactical missile guidance

A Singular Perturbation Based Midcourse Guidance Law for Realistic Air-to-Air Engagement

In this study, a singular perturbation based technique is used for synthesis and analysis of a near optimal midcourse guidance law for realistic air-to-air engagement. After designing the proposed midcourse guidance law using three dimensional point mass formulation it has been validated through detailed realistic six degrees of freedom simulation. During terminal phase only proportional navigation guidance have been used. The calculation of optimal altitude in present guidance law has been carried out using Newton’s method, which needs generally one iteration for convergence and suitable for real-time implementation. Extended Kalman filter based estimator has been used for obtaining evader kinetic information from both radar and seeker noisy measurements available during midcourse and terminal guidance. The data link look angle constraint due to hardware limitation which affects the performance of midcourse guidance has also been incorporated in guidance law design. Robustness of complete simulation has been carried out through Monte Carlo studies. Extension of launch boundary due to singular perturbation over proportional navigation guidance at a given altitude for a typical engagement has also been reported

Target Acceleration Estimation from Radar Position Data using Neural Network

This work is a preliminary investigation on target manoeuvre estimation in real-time from the available measurements of noisy position data from tracking radar using an artificial neural network (ANN). Recently, simulation study of target manoeuvre estimation in real-time from the same position alone measurement using extended Kalman filter has been carried out in a simulated environment using measurements at 100 ms interval. The results reveal that the estimated acceleration consists of substantial error and lag, which is a stumbling block for guidance accuracy in real-time. So, the target acceleration has been estimated using the ANN with less error and lag than the same using Kalman estimator

Target Acceleration Estimation from Radar Position Data using Neural Network

This work is a preliminary investigation on target manoeuvre estimation in real-time from the available measurements of noisy position data from tracking radar using an artificial neural network (ANN). Recently, simulation study of target manoeuvre estimation in real-time from the same position alone measurement using extended Kalman filter has been carried out in a simulated environment using measurements at 100 ms interval. The results reveal that the estimated acceleration consists of substantial error and lag, which is a stumbling block for guidance accuracy in real-time. So, the target acceleration has been estimated using the ANN with less error and lag than the same using Kalman estimator

Physiological parameters and yield differ in rice (Oryza sativa L.) cultivars with variable water management systems

Yield reduction of rice is a severe problem due to the advent of increasing water scarcity and efficiency is relatively low. Physiological attributes and yield performance of high yielding (HYV) rice cultivars need to be assessed by minimizing water loss. Therefore, a glasshouse experiment was conducted in Bangladesh to investigate the impact of cultivars and water management on growth dynamics, biomass production, and yield and water productivity. Ten HYV boro (dry season irrigated) rice cultivars along with fivewater management systems were included in the study. The study revealed that cultivars Binadhan-10 had higher value of leaf area index (LAI), root dry weight along with moderate panicle length. Accordingly, the cultivar Binadhan-10 had a higher yield than all other cultivars because of the highest total dry matter (TDM), number of effective tillers hill-1, and number of grains panicle-1. Growth, TDM, and yield were increased with water application up to 8 DAD after which these factors declined with increasing water stress at 10 DAD. The crop grown at CS condition did not increase the yield, rather caused the wastage of irrigation water. The water productivity was the highest (0.252 t ha-1cm-1) in 10 DAD treatments, obviously due to minimum water use but highest yield was observed in 8 DAD because of optimum use of water and non stress condition. Therefore, the present study was useful in the screening of the most efficient cultivars, which could be strongly recommended to rice growers to improve crop yield and reduce the use of water

Study of Ionospheric Variability during the Storm of January, 2005 using GPS and DEMETER Satellite Measurements

The dual frequency Global Positioning System (GPS) receiver provides an opportunity to determine Total Electron Content (TEC) over the crest of equatorial ionization anomaly region Bhopal by taking advantage of the dispersive nature of the ionospheric medium. The TEC values observed for the geomagnetic storm of the January 2005 is used in this paper to discuss the behaviour of ionospheric total electron content (TEC) during geomagnetically disturbed period. Variation of TEC is studied in correlation with the geomagnetic index Dst and southward component of interplanetary magnetic field Bz. The TEC variability is found to vary between with the maximum negative excursion of Dst index during the geomagnetic storms days. Positive phase is observed. Maximum TEC variability is observed during the recovery phase of the storms. Electron and ion density measurements from the DEMETER satellite are compared with the TEC measurements. The study of storm time TEC behaviour is very important due to recent increase in satellite-based navigation applications. Keywords: Ionosphere, geomagnetic storms, GPS, DEMETER, TE

Enhanced Singular Value Decomposition based Fusion for Super Resolution Image Reconstruction

The singular value decomposition (SVD) plays a very important role in the field of image processing for applications such as feature extraction, image compression, etc. The main objective is to enhance the resolution of the image based on Singular Value Decomposition. The original image and the subsequent sub-pixel shifted image, subjected to image registration is transferred to SVD domain. An enhanced method of choosing the singular values from the SVD domain images to reconstruct a high resolution image using fusion techniques is proposesed. This technique is called as enhanced SVD based fusion. Significant improvement in the performance is observed by applying enhanced SVD method preceding the various interpolation methods which are incorporated. The technique has high advantage and computationally fast which is most needed for satellite imaging, high definition television broadcasting, medical imaging diagnosis, military surveillance, remote sensing etc

Response of low latitude ionosphere to the space weather event of November 2012 in the Asian Sector

49-56Ionospheric response to geomagnetic storms is determined by the efficiency of the solar wind-magnetosphere-ionosphere coupling that underlies the transfer of tremendous amount of mass and energy. A study was carried out to see the response of the equatorial and low latitude ionosphere to the moderate geomagnetic storm of 14 November 2012. This study was carried out using vertical total electron content (VTEC) measured by Global Positioning System (GPS) receivers along the ~ 115°-121°E longitude. The GPS TEC observations showed pronounced positive storm effects in the Asian sector (~115°-121°E) during the main phase of the storm, for the low latitude and crest of anomaly stations. During the main phase of the storm, the interplanetary electric field (IEF) penetrated to the equatorial ionosphere and caused significant density changes in the equatorial ionization anomaly (EIA) region. The eastward prompt penetration electric field, associated with southward interplanetary magnetic field (IMF) augmented the normal daytime eastward dynamo electric field, resulting in intensification of equatorial ionization anomaly (EIA) and VTEC enhancements observed over the anomaly crest stations. Results showed that EIA region was significantly affected during geomagnetic storms in comparison to the low latitude ionosphere

Viability of Noether symmetry of F(R) theory of gravity

Canonization of F(R) theory of gravity to explore Noether symmetry is performed treating R - 6(\frac{\ddot a}{a} + \frac{\dot a^2}{a^2} + \frac{k}{a^2}) = 0 as a constraint of the theory in Robertson-Walker space-time, which implies that R is taken as an auxiliary variable. Although it yields correct field equations, Noether symmetry does not allow linear term in the action, and as such does not produce a viable cosmological model. Here, we show that this technique of exploring Noether symmetry does not allow even a non-linear form of F(R), if the configuration space is enlarged by including a scalar field in addition, or taking anisotropic models into account. Surprisingly enough, it does not reproduce the symmetry that already exists in the literature (A. K. Sanyal, B. Modak, C. Rubano and E. Piedipalumbo, Gen.Relativ.Grav.37, 407 (2005), arXiv:astro-ph/0310610) for scalar tensor theory of gravity in the presence of R^2 term. Thus, R can not be treated as an auxiliary variable and hence Noether symmetry of arbitrary form of F(R) theory of gravity remains obscure. However, there exists in general, a conserved current for F(R) theory of gravity in the presence of a non-minimally coupled scalar-tensor theory (A. K. Sanyal, Phys.Lett.B624, 81 (2005), arXiv:hep-th/0504021 and Mod.Phys.Lett.A25, 2667 (2010), arXiv:0910.2385 [astro-ph.CO]). Here, we briefly expatiate the non-Noether conserved current and cite an example to reveal its importance in finding cosmological solution for such an action, taking F(R) \propto R^{3/2}.Comment: 16 pages, 1 figure. appears in Int J Theoretical Phys (2012

Distortion Analysis of Thin-Walled Investment Castings

Dokra casting is famous for its Artistic value to the world but it is also sophisticated engineering. The technique is almost 4500 years old. It is practiced by the tribal artisans of India. It is a clay moulded wax-based thin-walled investment casting technique where liquid metal was poured into the red hot mould. Dimensional accuracy is always preferable for consumers of any product. Distortion is one of the barriers to achieving the accurate dimension for this type of casting especially for the bending parts. The cause and nature of the distortion for this type of casting must be analyzed to design a product with nominal tolerance and dimensional accuracy