近年来,多用户多输入多输出(Multiple-User Multiple-Input Multiple-Output,MU-MIMO)下行链路的预编码算法设计吸引了越来越多研究者的兴趣。然而目前并没有对基站端已知信道误差概率分布且约束条件为单天线功率约束(Per-Antenna Power...近年来,多用户多输入多输出(Multiple-User Multiple-Input Multiple-Output,MU-MIMO)下行链路的预编码算法设计吸引了越来越多研究者的兴趣。然而目前并没有对基站端已知信道误差概率分布且约束条件为单天线功率约束(Per-Antenna Power Constraints,PAPCS)的情况下的线性预编码算法的研究。针对上述情况,以遍历和速率(Expected Sum Rate)最大化为优化准则,主要基于约束随机逐次凸近似(Constrained Stochastic Successive Convex Approximation,CSSCA)、二阶对偶法、交替方向乘子法(Alternating Direction Method of Multipliers,ADMM)及高斯随机化(Gaussian Randomization)设计了线性预编码算法。所提算法的适用场景更符合实际情况,而且实验仿真结果证明,算法的性能较好。展开更多
针对贝叶斯网络参数的近似等式约束,提出采用正态分布构建该类约束的数学模型;然后用Dirichlet分布逼近正态分布,并通过目标优化计算Dirichlet分布的超参数;最后采用贝叶斯最大后验概率(maximum a posterior,MAP)估计方法计算网络参数...针对贝叶斯网络参数的近似等式约束,提出采用正态分布构建该类约束的数学模型;然后用Dirichlet分布逼近正态分布,并通过目标优化计算Dirichlet分布的超参数;最后采用贝叶斯最大后验概率(maximum a posterior,MAP)估计方法计算网络参数值。在不同样本量的数据集下进行实验测试,将本文方法与其他4种主要方法进行比较,结果表明:该方法的参数学习精度都好于其他4种方法,尤其是在样本量较小的情况下。该方法的运行时间高于其他4种方法,但相同样本量的数据集下,学习精度的提高倍数要高于时间增加的倍数。展开更多
How to get the rapid and stable inversion results and reconstruct the clear subsurface resistivity structures is a focus problem in current magnetotelluric inversion. A stable solution of an ill-posed inverse problem ...How to get the rapid and stable inversion results and reconstruct the clear subsurface resistivity structures is a focus problem in current magnetotelluric inversion. A stable solution of an ill-posed inverse problem was obtained by the regularization methods in which some desired structures were imposed to stabilize the inverse problem. By the smoothness-constrained model and approximate sensitivity method, the stable subsurface resistivity structures were reconstructed. The synthetic examples show that the smoothness-constrained regularized inversion method is effective and can be reasonable to reconstruct three-dimensional subsurface resistivity structures.展开更多
This paper investigates L∞--estimates for the general optimal control problems governed by two-dimensional nonlinear elliptic equations with pointwise control constraints using mixed finite element methods. The state...This paper investigates L∞--estimates for the general optimal control problems governed by two-dimensional nonlinear elliptic equations with pointwise control constraints using mixed finite element methods. The state and the co-state are approximated by the lowest order Raviart-Thomas mixed finite element spaces and the control is approximated by piecewise constant functions. The authors derive L∞--estimates for the mixed finite element approximation of nonlinear optimal control problems. Finally, the numerical examples are given.展开更多
文摘近年来,多用户多输入多输出(Multiple-User Multiple-Input Multiple-Output,MU-MIMO)下行链路的预编码算法设计吸引了越来越多研究者的兴趣。然而目前并没有对基站端已知信道误差概率分布且约束条件为单天线功率约束(Per-Antenna Power Constraints,PAPCS)的情况下的线性预编码算法的研究。针对上述情况,以遍历和速率(Expected Sum Rate)最大化为优化准则,主要基于约束随机逐次凸近似(Constrained Stochastic Successive Convex Approximation,CSSCA)、二阶对偶法、交替方向乘子法(Alternating Direction Method of Multipliers,ADMM)及高斯随机化(Gaussian Randomization)设计了线性预编码算法。所提算法的适用场景更符合实际情况,而且实验仿真结果证明,算法的性能较好。
文摘针对贝叶斯网络参数的近似等式约束,提出采用正态分布构建该类约束的数学模型;然后用Dirichlet分布逼近正态分布,并通过目标优化计算Dirichlet分布的超参数;最后采用贝叶斯最大后验概率(maximum a posterior,MAP)估计方法计算网络参数值。在不同样本量的数据集下进行实验测试,将本文方法与其他4种主要方法进行比较,结果表明:该方法的参数学习精度都好于其他4种方法,尤其是在样本量较小的情况下。该方法的运行时间高于其他4种方法,但相同样本量的数据集下,学习精度的提高倍数要高于时间增加的倍数。
基金Project(20110162120064)supported by Higher School Doctor Subject Special Scientific Research Foundation of ChinaProject(10JJ6059)supported by the Natural Science Foundation of Hunan Province,China
文摘How to get the rapid and stable inversion results and reconstruct the clear subsurface resistivity structures is a focus problem in current magnetotelluric inversion. A stable solution of an ill-posed inverse problem was obtained by the regularization methods in which some desired structures were imposed to stabilize the inverse problem. By the smoothness-constrained model and approximate sensitivity method, the stable subsurface resistivity structures were reconstructed. The synthetic examples show that the smoothness-constrained regularized inversion method is effective and can be reasonable to reconstruct three-dimensional subsurface resistivity structures.
基金supported by the Foundation for Talent Introduction of Guangdong Provincial University,Guangdong Province Universities and Colleges Pearl River Scholar Funded Scheme(2008)National Science Foundation of China under Grant No.10971074China Postdoctoral Science Foundation under Grant No.2011M500968
文摘This paper investigates L∞--estimates for the general optimal control problems governed by two-dimensional nonlinear elliptic equations with pointwise control constraints using mixed finite element methods. The state and the co-state are approximated by the lowest order Raviart-Thomas mixed finite element spaces and the control is approximated by piecewise constant functions. The authors derive L∞--estimates for the mixed finite element approximation of nonlinear optimal control problems. Finally, the numerical examples are given.
