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| 1 | Multistage decomposition algorithm for blind source separation显示文摘A new algorithm for blind source separation is proposed, which only extracts the single independent component at each stage. The single independent component is acquired by an iterative algorithm for searching for the optimal solution of the defined cost function. Moreover, all the independent components are obtained by systematic multistage decomposition and multistage reconstruction. When there is spatially colored noise, the performance of this algorithm is advantageous over jointly approximated diagonalization of eigen-matrices (JADE). Simulated results show that if the number of source signals is more than 25, its computational complexity is lower than that of JADE. | FENG Dazheng, BAO Zheng and ZHANG Xianda(Key Laboratory for Radar Signal Processing, Xidian University, Xi’an 710071, China) | 2002 | Progress in Natural Science:Materials International2002，12，5： | 5 |
| 2 | Adaptive selective ES-FEM limit analysis of cracked plane-strain structures显示文摘This paper presents a simple and efficient approach for predicting the plastic limit loads in cracked plane- strain structures. We use two levels of mesh repartitioning for the finite element limit analysis. The master level handles an adaptive primal-mesh process through a dissipation-based indicator. The slave level performs the subdivision of each triangle into three sub-triangles and constitutes a dual mesh from a pair of two adjacent sub-triangles shared by common edges of the primal mesh. Applying a strain smoothing projection to the strain rates on the dual mesh, the incompressibility constraint and the flow rule constraint are imposed over the edge-based smoothing domains and everywhere in the problem domain. The limit analysis problem is recast into the compact form of a second-order cone programming (SOCP) for the purpose of exploiting interior-point solvers. The present method retains a low number of optimization variables. It offers a convenient way for designing and solving the large-scale optimization problems effectively. Several benchmark examples are given to show the simplicity and effectiveness of the present method. | H. NGUYEN-XUAN T. RABCZUK | 2015 | Frontiers of Structural and Civil Engineering2015，9，4： | 3 |
| 3 | A New Ductile Fracture Criterion and Its Application to the Prediction of Forming Limit in Deep Drawing显示文摘With considering the influence of equivalent plastic strain on void-damage and taking Lemaitre damage equivalent stress as plastic potential, based on continuous damage mechanics theory, a new criterion for ductile fracture is derived. The two key material constants in the criterion are determined by the combination of tension tests with FE (finite element) simulation. On the basis of the values of stress and strain calculated from commercial finite element software, the forming limit in cylindrical deep drawing of annealed aluminum alloy LY12(M) is predicted by means of the new ductile fracture criterion. Experiments verify that the predicted results are in agreement with the experimental ones. Hence, it is reliable to predict the forming limit in deep drawing by means of the new ductile fracture criterion. | Yuying YANG Zhongqi YU Xuechun LI Zhenzhong SUN | 2003 | Journal of Materials Science & Technology2003，19，z1： | 3 |
| 4 | Optimal models with maximizing probability of first achieving target value in the preceding stages显示文摘Decision makers often face the need of performance guarantee with some sufficiently high proba-bility. Such problems can be modelled using a discrete time Markov decision process (MDP) with a probabilitycriterion for the first achieving target value. The objective is to find a policy that maximizes the probabilityof the total discounted reward exceeding a target value in the preceding stages. We show that our formula-tion cannot be described by former models with standard criteria. We provide the properties of the objectivefunctions, optimal value functions and optimal policies. An algorithm for computing the optimal policies forthe finite horizon case is given. In this stochastic stopping model, we prove that there exists an optimal deter-ministic and stationary policy and the optimality equation has a unique solution. Using perturbation analysis,we approximate general models and prove the existence of ε-optimal policy for finite state space. We give anexample for the reliability of the satellite systems using the above theory. Finally, we extend these results tomore general cases. | 林元烈 伍从斌 康波大 | 2003 | Science China Mathematics2003，46，3： | 1 |
| 5 | Elasto-plastic fatigue crack growth analysis of plane problems in the presence of flaws using XFEM显示文摘ABSTRACT In this paper, elasto-plastic XFEM simulations have been perfonaaed to evaluate the fatigue life of plane crack problems in the presence of various defects. The stress-strain response of the material is modeled by Ramberg- Osgood equation. The von-Mises failure criterion has been used with isotropic hardening. The J-integral for two fracture modes (mode-I and mode-If) is obtained by decomposing the displacement and stress fields into their symmetric and antisymmetric parts, then individual stress intensity factors are extracted from J-integral. The fatigue life obtained by EPFM is found quite close to that obtained by LEFM. | Sachin KUMAR A.S. SHEDBALE I. V. SINGH B.K. MISHRA | 2015 | Frontiers of Structural and Civil Engineering2015，9，4： | 0 |
| 6 | Optimizing Non-Decomposable Evaluation Metrics for NeuralMachine Translation显示文摘While optimizing model parameters with respect to evaluation metrics has recently proven to benefit end-to-end neural machine translation (NMT), the evaluation metrics used in the training are restricted to be defined at. thesentence level to facilitate online learning algorithms. This is undesirable because the final evaluation metrics used in tiletesting phase are usually non-decomposable (i.e., they are defined at the corpus level and cannot be expressed as the sumof sentence-level metrics). To minimize the discrepancy between the training and the testing, we propose to extend thenfinimum risk training (MRT) algorithm to take non-decomposable corpus-level evaluation metrics into consideration whilestill keeping; the advantages of online training. This can be done by calculating corpus-level evaluation metrics on a subsetof training data at each step in online training. Experiments on Chinese-English and English-French translation show thatour approach improves the correlation between training and testing and significantly outperforms the MRT algorithm usingdecomposable evaluation metrics. | Shi-Qi Shen Yang Liu Mao-Song Sun | 2017 | Journal of Computer Science & Technology2017，32，4： | 0 |
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