查看更多>>摘要：Declassification and endorsement can efficiently improve the usability of mobile applications.However,both declassify and endorse operations in practice are often ad-hoc and nondeterministic,thus,being insecure.From a new perspective of threat assessments,we propose the Threat-based typed security π-calculus (πTBTS) to model declassification and endorsement in mobile computing.Intuitively,when relaxing confidentiality policies and/or integrity policies,we respectively assess threats brought by performing these two relaxes.If these threats are acceptable,the declassification and/or endorsement operations are permitted;Otherwise,they are denied.The proposed assessments have explicit security conditions,results and less open parameters,so our approach solves the problem of the ad-hoc and nondeterministic semantics and builds a bridge between threat assessments and declassification/endorsement.
查看更多>>摘要：This paper proposes and studies a novel M-ary chirp modulation scheme adopting quasi-orthogonal waveforms.The Symbol error probability (SEP) of M-ary modulation over Additive white Gaussian noise (AWGN)channel is derived based on coherent detection,which is a function of modulation factor and waveform period.Moreover,the SEP is investigated over a channel limited by a nominal bandwidth.Both theoretical analysis and simulations prove that the SEP performance of the proposed 8-ary chirp modulation outperforms that of conventional 8 Phase shift keying (8PSK) with the same bandwidth efficiency.
查看更多>>摘要：Accurate parasitic parameter extraction of high-frequency transformers is one of the key techniques to efficiently design a Switched-mode power supply(SMPS).An approach to accurately and efficiently extract the parasitic parameters of high-frequency transformers is proposed.The high-frequency transformer is first decomposed into first-order RL and second-order RLC circuits according to inherent step response characteristics.Through the measured discharging pulse and damped oscillation responses of the high-frequency transformer excited by a square wave,we can extract the equivalent circuit parameters through fitting the responses with Particle swarm optimization(PSO).The equivalent circuits of the high-frequency transformer with the desired parameters are obtained for the SMPS design.We validate the effectiveness and accuracy of the proposed method with simulations and measurements.
查看更多>>摘要：A staggered grid scheme is proposed to reduce both the total memory requirement and the CPU time of generating the corrected near matrix in the FFT-based methods.Two sets of Cartesian grids are used to project the source points and the field points,respectively.The proposed method does not lower the efficiency of computing far matrix-vector products,compared with the traditional uniform Cartesian grid scheme.Some numerical experiments are provided to demonstrate both the correctness and the efficiency of the proposed method.
查看更多>>摘要：Synthetic aperture radar Tomography (TomoSAR) provides scene reflectivity estimation of vegetation along elevation coordinates.However,the more multi-baselines acquisition,the longer the time span of acquisition,which will result in serious temporal decorrelation in forested area.In this way,we expect to use as smaller number of baselines as possible to obtain high estimation accuracy in elevation direction.We thus investigate the performance of Polarimetric SAR tomography (Pol-TomoSAR) with small number of baselines in forested areas.The results show that compressive sensing-based Pol-TomoSAR has higher estimation accuracy in elevation direction than conventional Pol-TomoSAR with small number of baselines.
查看更多>>摘要：The Cat's eye effect target recognition method based on visual attention (CTRVA) is proposed.The difference image can be processed by a designed second-directional derivative filter at eight directional channels.Morphological method is employed to deal with the filtered image in all directions,which ensures that target can be easily distinguished from background.The salient maps for each channel where the potential targets exist are calculated through the spectral residual approach,and the "target-saliency" map is computed by a designed saliency fusing method.The coarse detection is performed by the adaptive threshold to extract candidate targets from the "target-saliency" map.The real target region is identified by the characteristics of the cat's eye effect target.Experimental results show that the proposed method is efficient and has an outstanding performance for cat's eye effect target detection.
NETL
NSTL
万方数据
维普