Using the locally conformal technique and the high-order symplectic integrators, the high- order conformal symplectic FDTD scheme is accurate and efficient for modeling the scattering from three-dimensional curved per...
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Using the locally conformal technique and the high-order symplectic integrators, the high- order conformal symplectic FDTD scheme is accurate and efficient for modeling the scattering from three-dimensional curved perfectly conducting objects. In addition, the decreased time step caused by the conformal model can be offset by using coarse grids.
While direct association rules are dedicated to describe the direct correlations among the items in a frequent itemset, indirect association rules are dedicated to describe the indirect correlations between the two it...
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While direct association rules are dedicated to describe the direct correlations among the items in a frequent itemset, indirect association rules are dedicated to describe the indirect correlations between the two items in a infrequent itemset. All the existing research works about indirect association rules are focused on improving the efficiency of mining algorithm for indirect association rules. Like incremental updating algorithm is important for mining association rules, incremental updating algorithm is also important for mining indirect association rules. In this paper, we put forward an incremental updating algorithm for mining indirect association rules to deal with the maintenance of discovered indirect association rules resulted from the change of the minimum support. The main idea is to re-utilize the results acquired in process with the old minimum support.
The traditional DCT-based real-valued discrete Gabor transform (RGDT) was limited to the critical sampling case. The biorthogonality relationship between the analysis window and the synthesis window for the transform ...
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The traditional DCT-based real-valued discrete Gabor transform (RGDT) was limited to the critical sampling case. The biorthogonality relationship between the analysis window and the synthesis window for the transform has not been unveiled. To overcome those drawbacks, this paper proposes a novel DCT-based real-valued discrete Gabor transform, which can be applied under both the critical sampling condition and the over-sampling condition. And the biorthogonality relationship between the analysis window and the synthesis window for the transform is also proved in this paper. Because it only involves real operations and can utilize fast DCT and DDCT algorithms for fast computation, it facilitates computation and implementation by hardware and/or software compared to the traditional complex-valued discrete Gabor transform.
The expectation-maximization (EM) algorithm is a popular approach for parameter estimation of finite mixture model (FMM). A drawback of this approach is that the number of components of the finite mixture model is not...
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ISBN:
(纸本)9781424423101
The expectation-maximization (EM) algorithm is a popular approach for parameter estimation of finite mixture model (FMM). A drawback of this approach is that the number of components of the finite mixture model is not known in advance, nevertheless, it is a key issue for EM algorithms. In this paper, a penalized minimum matching distance-guided EM algorithm is discussed. Under the framework of Greedy EM, a fast and accurate algorithm for estimating the number of components of the Gaussian mixture model (GMM) is proposed. The performance of this algorithm is validated via simulative experiments of univariate and bivariate Gaussian mixture models.
The connections between Maxwell's equations and symplectic matrix are ***,we analyze the continuoustime Maxwell's difierentia I equationsInfree space and verify its time evolution matrix(TEMA)is symplectic-uni...
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The connections between Maxwell's equations and symplectic matrix are ***,we analyze the continuoustime Maxwell's difierentia I equationsInfree space and verify its time evolution matrix(TEMA)is symplectic-unitary matrix for complex space or symplectic-orthogonal matrix for real *** spatial differential operators are discrefized by pseudo-spectral(PS)approach with collocated grid and by finitedifrerenee(FD)method with staggered *** the PS approach,the TEMA conserves *** *** the FD method,the TEMA conserves symplectic-orthogonal *** integration scheme is usedInthe time *** particular,we find the symplectiness of the TEMA also can be *** mathematicaI proofs presented are helpful for deep researching the symplectic PSTD approach and the symplectic FDTD method.
In this paper, a similar but novel method presented in [3, 4], lifting wavelet-like transform (LWLT), is applied to the FMM method to sparsify the aggregation and disaggregation matrix. By compressing the elements in ...
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In this paper, a similar but novel method presented in [3, 4], lifting wavelet-like transform (LWLT), is applied to the FMM method to sparsify the aggregation and disaggregation matrix. By compressing the elements in those two matrices in time, the method proposed can further speed up the MVM and save much memory when the FMM is used. Numerical results for different shaped three-dimensional objects are considered. Compared with the FMM technique, the application of the LWLT to the FMM can accelerate the MVM by factor of two with lower memory consumed.
Classical finite-difference time-domain (FDTD) method has been widely used in computational electromagnetics, but for electrically large domains and for late-time analysis, FDTD method begins to show its limitations d...
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Classical finite-difference time-domain (FDTD) method has been widely used in computational electromagnetics, but for electrically large domains and for late-time analysis, FDTD method begins to show its limitations due to the accumulation of phase errors. To solve this problem, several methods have been proposed such as high-order schemes and four-stage Runge-Kutta integrator. Recently, the symplectic methods have been adopted for using in computational electromagnetics. In this paper, the concentration is on the derivation of an optimized fourth-order symplectic scheme in electromagnetic simulations.
Short-term forecasting of travel time is essential for the success of intelligent transportation system. In this paper, we review the state-of-art of short-term traffic forecasting models and outline their basic ideas...
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Short-term forecasting of travel time is essential for the success of intelligent transportation system. In this paper, we review the state-of-art of short-term traffic forecasting models and outline their basic ideas, related works, advantages and disadvantages of each model. An improved adaptive exponential smoothing (IAES) model is also proposed to overcome the drawbacks of the previous adaptive exponential smoothing model. Then, comparing experiments are carried out under normal traffic condition and abnormal traffic condition to evaluate the performance of four main branches of forecasting models on direct travel time data obtained by license plate matching (LPM). The results of experiments show each model seems to have its own strength and weakness. The forecasting performance of IASE is superior to other models in shorter forecasting horizon (one and two step forecasting) and the IASE is capable of dealing with all kind of traffic conditions.
Target detection by non-cooperative illuminator is a study hotspot in electronic warfare field, with'four countering' potential advantages for passive radar. One of the major problems in continuous wave bistat...
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Target detection by non-cooperative illuminator is a study hotspot in electronic warfare field, with'four countering' potential advantages for passive radar. One of the major problems in continuous wave bistatic radar is Direct path interference (DPI). Conventional solutions to this problem is the use of an adaptive antenna, steering null towards the interference. Unfortunately the null depth obtained by this technology is not enough for surveillance radar. First of all, DPI appeared in passive radar based on non-cooperative FM broadcast transmitter is analyzed in this paper. Secondly, a DPI cancellation based on Adaptive fractional delay estimation (AFDE) is in detail introduced how to deal with this problem. Finally, a passive radar experimental system based on non-cooperative FM broadcast transmitter is provided, simulation results by real collected data show applying the method proposed in this paper is effective in suppression DPI.
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