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Recent advances in catalytic combustion of AP-based composite solid propellants

Defence Technology（防务技术） 2021年第3期17卷 1013-1031页

作者： Narendra Yadav prem kumar srivastava Mohan Varma Department of Space Engineering&Rocketry India Department of Chemistry Birla Institute of TechnologyMesraRanchiIndia

Composite solid propellants(CSPs) have widely been used as main energy source for propelling the rockets in both space and military applications. Internal ballistic parameters of rockets like characteristic exhaust velocity, specific impulse, thrust, burning rate etc., are measured to assess and control the performance of rocket motors. The burn rate of solid propellants has been considered as most vital parameter for design of solid rocket motors to meet specific mission requirements. The burning rate of solid propellants can be tailored by using different constituents, extent of oxidizer loading and its particle size and more commonly by incorporating suitable combustion catalysts. Various metal oxides(MOs),complexes, metal powders and metal alloys have shown positive catalytic behaviour during the combustion of CSPs. These are usually solid-state catalysts that play multiple roles in combustion of CSPs such as reduction in activation energy, enhancement of rate of reaction, modification of sequences in reaction-phase, influence on condensed-phase combustion and participation in combustion process in gas-phase reactions. The application of nanoscale catalysts in CSPs has increased considerably in recent past due to their superior catalytic properties as compared to their bulk-sized counterparts. A large surface-to-volume ratio and quantum size effect of nanocatalysts are considered to be plausible reasons for improving the combustion characteristics of propellants. Several efforts have been made to produce nanoscale combustion catalysts for advanced propellant formulations to improve their energetics. The work done so far is largely scattered. In this review, an effort has been made to introduce various combustion catalysts having at least a metallic entity. Recent developments of nanoscale combustion catalysts with their specific merits are discussed. The combustion chemistry of a typical CSP is briefly discussed for providing a better understanding on role of co

关键词： Composite solid propellants Burn rate modifier Metallic nano-catalysts Catalytic combustion Thermal decomposition

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Numerical Algorithm Based on Quintic Nonpolynomial Spline for Solving Third-Order Boundary Value Problems Associated with Draining and Coating Flows

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Chinese Annals of Mathematics,Series B 2012年第6期33卷 831-840页

作者： Pankaj kumar srivastava Manoj kumar Department of Mathematics Jaypee Institute of Information Technology Department of Mathematics Motilal Nehru National Institute of Technology

A numerical algorithm is developed for the approximation of the solution to certain boundary value problems involving the third-order ordinary differential equation associated with draining and coating flows. The authors show that the approximate so- lutions obtained by the numerical algorithm developed by using uonpolynomial quintic spline functions ave better than those produced by other spline and domain decomposition methods. The algorithm is tested on two problems associated with draining and coating flows to demonstrate the practical usefulness of the approach.

关键词： Third-order boundary value problem Spline functions Nonpolynomial quartic spline Nonpolynomial quintic spline Draining and coating flows

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Proximate Composition,Mineral Content and Fatty Acids Analyses of Aromatic and Non-Aromatic Indian Rice

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Rice science 2017年第1期24卷 21-31页

作者： Deepak kumar VERMA prem Prakash SRIVASTAV Agricultural and Food Engineering Department Indian Institute of TechnologyKharagpur 721302India

Awareness on nutritive value and health benefits of rice is of vital importance in order to increase the consumption of rice in daily diet of the human beings. In this study, a total of six aromatic and two non-aromatic rice accessions grown in India were analysed for their nutritional quality attributes including proximate composition, mineral contents and fatty acids. Data with three replications were used to measure Pearson＇s simple correlation co-efficient in order to establish the relationship among various nutritional quality attributes. The result on proximate composition showed that Govind Bhog had the highest moisture（13.57%） and fat（0.92%） content, which signifies its tasty attribute. Badshah Bhog exhibited the highest fibre content（0.85%）, carbohydrate content（82.70%） and food energy（365.23 k Cal per 100 g）. Among the minerals, the higher Ca（98.75 mg/kg）, Zn（17.00 mg/kg） and Fe（31.50 mg/kg） were in Gopal Bhog, whereas the highest Na（68.85 mg/kg） was in Badshah Bhog, the highest K（500.00 mg/kg） was in Swetganga, Khushboo and Sarbati. The highest contents of unsaturated fatty acids viz. oleic acid（49.14%）, linoleic acid（46.99%） and linolenic acid（1.27%） were found in Sarbati, whereas the highest content of saturated fatty acids viz. myristic acid（4.60%） and palmitic acid（31.91%） were found in Govind Bhog and stearic acid（6.47%） in Todal. The identified aromatic rice accessions Gopal Bhog, Govind Bhog and Badshah Bhog and non-aromatic rice accession Sarbati were found nutritionally superior among all eight tested accessions. The nutritional quality oriented attributes in this study were competent with recognized prominent aromatic and non-aromatic rice accessions as an index of their nutritional worth and recommend to farmers and consumers which may be graded as export quality rice with good unique nutritional values in international market.

关键词： aromatic unsaturated nutritional proximate accession carbohydrate oleic vital competent attribute

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Efficient Single-Stage Bridgeless AC to DC Converter Using Grey Wolf Optimization

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Computer Systems Science & Engineering 2022年第11期43卷 487-499页

作者： prema Kandasamy K.prem kumar Department of Electrical and Electronics Engineering Thangavelu Engineering CollegeChennai-600097India Department of Electrical and Electronics Engineering Rajalakshmi Engineering CollegeChennai-602105India

Bridgeless single-stage converters are used for efficient(alternative current)AC-(direct current)DC *** converters control generators,likeelectromagnetic meso-and micro-scale generators with low *** factorcorrection helps increase the factor of the power *** main advantage ofthe power factor is it shapes the input current for increasing the real power of theAC *** this paper,a two-switch bridgeless rectifier topology is designedwith a power factor correction *** the proposed converter topologyto have good power quality parameters,the closed loop scheme,which uses thegrey wolf optimization(GWO)algorithm,is *** successes ofGWO encourage this research to implement GWO in the *** performanceof the proposed topology is analyzed under different load *** is carried out using the MATLAB/Simulink environment,and theresults are compared with those of conventional(proportional integral derivative)PID and(particle swarm optimization)PSO *** validate the simulation results,a 350-W hardware prototype is implemented,and the voltage ripple,efficiency,and power factor under different load conditions are analyzed and *** comparative study clearly indicates that the proposed convertertopology with a closed loop control scheme using the GWO algorithm improves the power factor to 0.9732 and reduces the voltage ripple to 0.12%with a conversion efficiency of 98.25%.

关键词： Bridgeless AC converter DC converter GWO controller power factor

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A 2000 Year Multi-Proxy Evidence of Natural/Anthropogenic Influence on Climate from the Southwest Coast of India

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Journal of Earth Science 2020年第5期31卷 1029-1044页

作者： M.C.Manoj Jyoti srivastava prem Raj Uddandam Biswajeet Thakur Birbal Sahni Institute of Paleosciences 53 University RoadL ucknowUttar Pradesh 226007India Banaras Hindu University VaranasiUttar PradeshIndia

The last millennium climate reconstructions are complex and limit our understanding of the mechanisms behind environmental and climate variability. We present multi-proxy centennial-scale records from the Cherai, southwest India. The last 2000 cal yr AD record suggests a complex environmental condition that prevailed at the depositional site augmenting the role of natural as well as anthropogenic agents. Increased elemental variations and indices values indicate stronger weathering, presumably wetter conditions and intense precipitation. Provenance studies suggest diverse sources and the main composition fall close to the Charnockite and Gneissic composition. Multi-proxy data suggests that a shift towards wetter climatic conditions, which occurred from 910 to 1230 cal yr AD. The core also records a shift towards the drier conditions that started around 1230 cal yr AD with a loss in vegetation diversity. The pollution load index values suggest that the overall study area falls in moderate contamination levels, which are also substantiated with the diatom data indicating human influence in the natural habitat during the deposition time. The present study reveals that the enhanced Cd and As concentration is due to strong anthropogenic influence. We compared the multi-proxy record with other continental and marine palaeoclimatic records to explore global and/or regional trends in climate variability during the last 2000 years.

关键词： estuaries monsoon provenance vegetation clmate contamination

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