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W. Johnson A.K. Sengupta S.K. Ghosh 《International Journal of Mechanical Sciences》1982,24(7):425-436
A review of the literature on high velocity oblique impact and the ricochet of projectiles of various shapes is given, with emphasis on long rod projectiles. Aspects of cratering and penetration in oblique impact are highlighted and the mechanics of ricochet off solid, fluid and granular media are also discussed. 相似文献
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Sujoy Saha Subrata Nandi Rohit Verma Satadal Sengupta Kartikeya Singh Vivek Sinha Sajal K. Das 《Wireless Networks》2018,24(1):173-194
Delay tolerant networks (DTNs) are characterized by delay and intermittent connectivity. Satisfactory network functioning in a DTN relies heavily on co-ordination among participating nodes. However, in practice, such co-ordination cannot be taken for granted due to possible misbehaviour by relay nodes. Routing in a DTN is, therefore, vulnerable to various attacks, which adversely affect network performance. Several strategies have been proposed in the literature to alleviate such vulnerabilities—they vary widely in terms of throughput, detection time, overhead etc. One key challenge is to arrive at a tradeoff between detection time and overhead. We observe that the existing table-based reactive strategies to combat Denial-of-service (DoS) attacks in DTN suffer from two major drawbacks: high overhead and slow detection. In this paper, we propose three secure, light-weight and time-efficient routing algorithms for detecting DoS attacks (Blackhole and Grey-hole attacks) in the Spray & Focus routing protocol. The proposed algorithms are based on use of a small fraction of privileged (trusted) nodes. The first strategy, called TN, outperforms the existing table-based strategy with 20–30 % lesser detection time, 20–25 % higher malicious node detection and negligible overhead. The other two strategies, CTN_MI and CTN_RF explore the novel idea that trusted nodes are able to utilize each others’ information/experience using their long range connectivity as and when available. Simulations performed using an enhanced ONE simulator reveals that investing in enabling connectivity among trusted nodes (as in CTN_RF) can have significant performance benefits. 相似文献
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S. Bandyopadhyay A. Sengupta S. P. Dutta 《The International Journal of Advanced Manufacturing Technology》1987,2(3):37-48
The objective of this paper is to describe a knowledge-based system to assist engineers to generate optimum process plans.
The knowledge base is defined using a PASCAL-like language and is maintained in the form of PROLOG sentences. The knowledge
base may be readily modified by process planners to meet their specific requirements. An inferece engine systematically tries
to apply the rules to generate basic process plans. These plans are then optimised by repeated applications of user difined
rules. The system is being written in PROLOG. 相似文献
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Sengupta D. Jandhyala V. Sangsig Kim Weich Fang Malin J. Apostolakis P. Kwong-Chi Hseih Yia-Chung Chang Shun Lien Chuang Bandara S. Gunapala S. Feng M. Michielssen E. Stillman G. 《IEEE journal of selected topics in quantum electronics》1998,4(4):746-757
The partial intermixing of the well and barrier materials offers unique opportunities to shift locally the bandgap of quantum-well (QW) structures. We have demonstrated redshifting and broadening of the wavelength responses of bound-to-continuum GaAs and InP based quantum-well infrared photodetectors (QWIP's) after growth via impurity-free vacancy disordering (IFVD). A comprehensive set of experiments is conducted on QWIP's fabricated from both as-grown and multiple-quantum-well (MQW) structures. Compared to the as-grown detector, the peak spectral responses of the disordered detectors were shifted to longer wavelengths. The peak absolute response of the disordered GaAs based QWIP is lower by almost a factor of four. However, the responsivity characteristics of the disordered InP based QWIP show no major degradation. In general, with the spectral broadening taken into account, the overall performance of the disordered QWIP's has not dropped significantly. Thus, the postgrowth control of the QW composition profiles by impurity-free vacancy disordering offers unique opportunities to fine tune various aspects of a photodetector's response. Theoretical calculations of the absorption coefficient spectrum are in excellent agreement with the experimental data 相似文献
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