Choice of Interceptor Aerodynamic Lifting Surface Location based on Autopilot Design Considerations

Interceptors operate at wide range of operating conditions in terms of Mach number, altitude and angle of attack. The aerodynamic design caters for such wide operating envelope by appropriate sizing of lifting and control surfaces for meeting the normal acceleration capability requirements. The wide range of operating conditions leads to an inevitable spread in center of pressure location and hence spread in static stability. The performance of control design is a strong function of the aerodynamic static stability. The total operating envelope can be bifurcated into statically stable and unstable zones and the aerodynamic lifting surface location can be used as a control parameter to identify the neutral stability point. During the homing phase lesser static stability is desirable for good speed of response, hence the lifting surface location needs to be chosen based on the capability of control to handle instability. This paper analyses the limitations of autopilot design for the control of an unstable interceptor and brings out a method to identify the optimum aerodynamic lifting surface location for efficiently managing static margin while satisfying the control limitations and homing phase performance. This provides an input on the most appropriate lifting surface location to the aerodynamic designer during the initial CFD based aerodynamic characterisation stage itself, before commencing the rigorous wind tunnel based characterisation

Location Privacy Context Information Effects Using Bayesian Inference Framework

ABSTRACT -. Smartphones, among other increasingly powerful mobile computing devices, offer various methods of localization. Integrated GPS receivers, or positioning services based on nearby communication infrastructure (Wi-Fi access points or base stations of cellular networks), enable users to position themselves fairly accurately, which has led to a wide offering of Location-based Services (LBSs). Such services can be queried by users to provide real-time information related to the current position and surroundings of the device, e.g., contextual data about points of interest such as petrol stations, or more dynamic information such as traffic conditions. The value of LBSs is in their ability to obtain on the fly up-to-date information. Although LBSs are convenient, disclosing location information can be dangerous. Each time an LBS query is submitted private information is revealed. Users can be linked to their locations, and multiple pieces of such information can be linked together. They can then be profiled, which leads to unsolicited targeted advertisements or price discrimination. Even worse, the habits, personal and private preferences, religious beliefs, and political affiliations, for example, can be inferred from a user's whereabouts. This could make her the target of blackmail or harassment. Finally, real-time location disclosure leaves a person vulnerable to absence disclosure attacks: learning that someone is away from home could enable someone to break into her house or blackmail he

EULER ANGLE ERROR COMPUTATION AND THRUST VECTOR CONTROL SCHEME FOR INITIAL TURNING PHASE OF A VERTICAL LAUNCH SURFACE TO AIR MISSILE

A vertical launch missile requires to be turned towards the Predicted Interception Point (PIP) with the target within few seconds from the launch. The autopilot used for the same requires the error in Euler Angles between the missile and the target to be supplied, which is generally computed using Error Quaternions approach [1]. For some kinds of engagement scenarios, say a Near Boundary Low Altitude target, the turn angle required in the pitch plane during the initial phase can become more than 90 degrees. In such cases, the conventional 3-2-1 frame transformation method fails to compute the Euler Angle errors correctly. As an alternative approach the Euler Angle error computation using 2-3-1 frame transformation is proposed in this paper. After computing the Euler Angle Errors, the desired turning is achieved by Thrust Vector Control [2] using jet vanes or thrusters. The initial turning using Aerodynamic control is not desirable because of low dynamic pressure, where as the usage of jet vanes brings more hardware complications for small tactical missiles. The possibility of using thrusters for initial turning phase in a short range tactical missile is studied in this paper with the help of simulation results

A Study on Corrosion Behavior of Vacuum Brazed OFE Copper Joints of Industrial Accelerator

Abstract The paper describes an experimental study involving investigation of corrosion possibilities in cooling circuit of an in-house developed 10 MeV, 6 kW S-band industrial electron linear accelerator, comprising of vacuum brazed multiple OFE copper cavities. The study was performed on vacuum brazed OFE copper specimens in process water used in the cooling circuit of the accelerator structure. The results of the study has demonstrated that surface of the brazed OFE copper specimens, exposed to stagnant process water, develops passive oxide layer in the initial period of specimen's exposure. This oxide layer protects underlying substrate from further corrosion. In contrast, specimens exposed to flowing process water displays relatively higher rate of corrosion. On the basis of short term immersion tests (for 45 days) in flowing conditions the estimated rate of general corrosion was found to be about 0.18 mils/year (equivalent to 4.5 µm/year) which is quite low. However, a long term corrosion study in simulated process loop would provide more useful information regarding corrosion behaviour of the brazed joints of the accelerating structure

Genetic, Physiological, and Gene Expression Analyses Reveal That Multiple QTL Enhance Yield of Rice Mega-Variety IR64 under Drought

<div><p>Background</p><p>Rice (<i>Oryza sativa</i> L.) is a highly drought sensitive crop, and most semi dwarf rice varieties suffer severe yield losses from reproductive stage drought stress. The genetic complexity of drought tolerance has deterred the identification of agronomically relevant quantitative trait loci (QTL) that can be deployed to improve rice yield under drought in rice. Convergent evidence from physiological characterization, genetic mapping, and multi-location field evaluation was used to address this challenge.</p><p>Methodology/Principal Findings</p><p>Two pairs of backcross inbred lines (BILs) from a cross between drought-tolerant donor Aday Sel and high-yielding but drought-susceptible rice variety IR64 were produced. From six BC₄F₃ mapping populations produced by crossing the +QTL BILs with the −QTL BILs and IR64, four major-effect QTL - one each on chromosomes 2, 4, 9, and 10 - were identified. Meta-analysis of transcriptome data from the +QTL/−QTL BILs identified differentially expressed genes (DEGs) significantly associated with QTL on chromosomes 2, 4, 9, and 10. Physiological characterization of BILs showed increased water uptake ability under drought. The enrichment of DEGs associated with root traits points to differential regulation of root development and function as contributing to drought tolerance in these BILs. BC₄F₃-derived lines with the QTL conferred yield advantages of 528 to 1875 kg ha⁻¹ over IR64 under reproductive-stage drought stress in the targeted ecosystems of South Asia.</p><p>Conclusions/Significance</p><p>Given the importance of rice in daily food consumption and the popularity of IR64, the BC₄F₃ lines with multiple QTL could provide higher livelihood security to farmers in drought-prone environments. Candidate genes were shortlisted for further characterization to confirm their role in drought tolerance. Differential yield advantages of different combinations of the four QTL reported here indicate that future research should include optimizing QTL combinations in different genetic backgrounds to maximize yield advantage under drought.</p></div

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Not AvailableDirect selection for yield under drought has resulted in the release of a number of drought-tolerant rice varieties across Asia. In this study, we characterized the physiological traits that have been affected by this strategy in breeding trials across sites in Bangladesh, India, and Nepal. Drought- breeding lines and drought-tolerant varieties showed consistently longer flag leaves and lower stomatal density than our drought-susceptible check variety, IR64. The influence of environmental parameters other than drought treatments on leaf traits was evidenced by close grouping of treatments within a site. Flag-leaf length and width appeared to be regulated by different environmental parameters. In separate trials in the Philippines, the same breeding lines studied in South Asia showed that canopy temperature under drought and harvest index across treatments were most correlated with grain yield. Both atmospheric and soil stress strengthened the relationships between leaf traits and yield. The stable expression of leaf traits among genotypes and the identification of the environmental conditions in which they contribute to yield, as well as the observation that some breeding lines showed longer time to flowering and higher canopy temperature than IR64, suggest that selection for additional physiological traits may result in further improvements of this breeding pool.Not Availabl