An algorithm for integrating the constitutive equations in thermal framework is presented, in which the plastic deformation gradient is chosen as the integration variable. Compared with the classic algorithm, a key fe...An algorithm for integrating the constitutive equations in thermal framework is presented, in which the plastic deformation gradient is chosen as the integration variable. Compared with the classic algorithm, a key feature of this new approach is that it can describe the finite deformation of crystals under thermal conditions. The obtained plastic deformation gradient contains not only plastic defor- mation but also thermal effects. The governing equation for the plastic deformation gradient is obtained based on ther- mal multiplicative decomposition of the total deformation gradient. An implicit method is used to integrate this evo- lution equation to ensure stability. Single crystal 1 100 aluminum is investigated to demonstrate practical applications of the model. The effects of anisotropic properties, time step, strain rate and temperature are calculated using this integration model.展开更多
The single ion channel signal is an ionic current that can be recorded by the patch clamp technique. Hidden Markov model (HMM) algorithm has been used to convert the low signal noise ratio (SNR) noisy recording into a...The single ion channel signal is an ionic current that can be recorded by the patch clamp technique. Hidden Markov model (HMM) algorithm has been used to convert the low signal noise ratio (SNR) noisy recording into an idealized quantal one in the case of white background noise. The traditional HMM algorithm is extended and adapted to the colored background noise. A new algorithm called EHMM (Extended HMM) algorithm is proposed, and mainly validated by simulation. Results show that it’s effective.展开更多
Many kinds of channel currents are especially weak and the background noise dominates in the patch clamp recordings. This makes the threshold detection fail during estimating of the transition probabilities. So direct...Many kinds of channel currents are especially weak and the background noise dominates in the patch clamp recordings. This makes the threshold detection fail during estimating of the transition probabilities. So direct fitting of the patch clamp recording, not of the histogram coming from the recordings, is a desirable way to estimate the transition probabilities. Iterative batch EM algorithm based on hidden markov model has been used in this field but which has the "curse of dimensionality" and besides cant keep tracking the varying of the parameters. A new on line sequential iterative one is proposed here, which needs fewer computational efforts and can adaptively keep tracking the varying of parameters. Simulations suggest its robust, effective and convenient.展开更多
利用AMSR-E观测的土壤表层亮温资料,采用简化修正的单通道算法模型(Single Channel Algorithm,SCA),反演青藏高原地区夏季2011年6-8月的表层土壤湿度。为对比验证反演结果,利用高原东部和中部的玛曲观测网和那曲观测网CTP-SMTMN(Soil Mo...利用AMSR-E观测的土壤表层亮温资料,采用简化修正的单通道算法模型(Single Channel Algorithm,SCA),反演青藏高原地区夏季2011年6-8月的表层土壤湿度。为对比验证反演结果,利用高原东部和中部的玛曲观测网和那曲观测网CTP-SMTMN(Soil Moisture and Temperature Monitoring Netw ork on the central Tibetan Plateau)的土壤湿度观测数据,以及NASA和VUA-NASA两种均基于AM SR-E的反演土壤湿度产品进行验证。结果表明:(1)与VUA-NASA产品和修改后的SCA模型反演结果相比,NASA产品在像元和区域尺度上相关系数较低,MAE(Mean Absolute Error)和RMSE(Root M ean Square Error)较高,明显低估了两个地区的土壤湿度。(2)VUA-NASA产品在玛曲地区表现良好,在那曲地区虽然相关系数较高,但MAE和RMSE同样较高,导致精度较差。(3)对比其他两种产品,修改后的SCA模型反演结果在两个地区表现出较高的相关系数(接近0.800)、较低的MAE(接近0.050m^3·m^(-3))和RMSE(接近0.060 m^3·m^(-3)),有着较高的精度。因此,可以认为修改后的SCA模型可以应用于青藏高原地区土壤湿度动态监测,为研究青藏高原地区的天气和气候变化影响及水循环过程提供了参考和借鉴。展开更多
针对在地空频率选择性衰落信道中,信道冲激响应具有时域稀疏特性的情况,提出了基于贪婪算法的单载波频域均衡（SC-FDE）系统稀疏信道估计方法。Chu序列是SC-FDE中常用的导频序列,对其进行分析并证明了将Chu序列进行循环移位所构造的导...针对在地空频率选择性衰落信道中,信道冲激响应具有时域稀疏特性的情况,提出了基于贪婪算法的单载波频域均衡（SC-FDE）系统稀疏信道估计方法。Chu序列是SC-FDE中常用的导频序列,对其进行分析并证明了将Chu序列进行循环移位所构造的导频矩阵满足RIP条件,将导频矩阵作为测量矩阵,把地空信道估计问题建模为稀疏重构模型,采用贪婪算法中的OMP和Co Sa MP算法对信道进行稀疏重构,仿真验证了所得信道估计较传统最小二乘（LS）信道估计方法更加准确。在相同的训练序列长度和信道环境下,利用所得信道估计对接收信号进行最小均方误差（MMSE）均衡,蒙特卡罗仿真结果表明,所提方法与传统LS信道估计方法相比,系统误码性能提高2~3 d B。展开更多
基金supported by the Key Project of the National Natural Science Foundation of China(10932003)Project of Chinese National Programs for Fundamental Research and Development(2012CB619603 and 2010CB832700)"04" Great Project of Ministry of Industrialization and Information of China (2011ZX04001-21)
文摘An algorithm for integrating the constitutive equations in thermal framework is presented, in which the plastic deformation gradient is chosen as the integration variable. Compared with the classic algorithm, a key feature of this new approach is that it can describe the finite deformation of crystals under thermal conditions. The obtained plastic deformation gradient contains not only plastic defor- mation but also thermal effects. The governing equation for the plastic deformation gradient is obtained based on ther- mal multiplicative decomposition of the total deformation gradient. An implicit method is used to integrate this evo- lution equation to ensure stability. Single crystal 1 100 aluminum is investigated to demonstrate practical applications of the model. The effects of anisotropic properties, time step, strain rate and temperature are calculated using this integration model.
文摘The single ion channel signal is an ionic current that can be recorded by the patch clamp technique. Hidden Markov model (HMM) algorithm has been used to convert the low signal noise ratio (SNR) noisy recording into an idealized quantal one in the case of white background noise. The traditional HMM algorithm is extended and adapted to the colored background noise. A new algorithm called EHMM (Extended HMM) algorithm is proposed, and mainly validated by simulation. Results show that it’s effective.
文摘Many kinds of channel currents are especially weak and the background noise dominates in the patch clamp recordings. This makes the threshold detection fail during estimating of the transition probabilities. So direct fitting of the patch clamp recording, not of the histogram coming from the recordings, is a desirable way to estimate the transition probabilities. Iterative batch EM algorithm based on hidden markov model has been used in this field but which has the "curse of dimensionality" and besides cant keep tracking the varying of the parameters. A new on line sequential iterative one is proposed here, which needs fewer computational efforts and can adaptively keep tracking the varying of parameters. Simulations suggest its robust, effective and convenient.
文摘利用AMSR-E观测的土壤表层亮温资料,采用简化修正的单通道算法模型(Single Channel Algorithm,SCA),反演青藏高原地区夏季2011年6-8月的表层土壤湿度。为对比验证反演结果,利用高原东部和中部的玛曲观测网和那曲观测网CTP-SMTMN(Soil Moisture and Temperature Monitoring Netw ork on the central Tibetan Plateau)的土壤湿度观测数据,以及NASA和VUA-NASA两种均基于AM SR-E的反演土壤湿度产品进行验证。结果表明:(1)与VUA-NASA产品和修改后的SCA模型反演结果相比,NASA产品在像元和区域尺度上相关系数较低,MAE(Mean Absolute Error)和RMSE(Root M ean Square Error)较高,明显低估了两个地区的土壤湿度。(2)VUA-NASA产品在玛曲地区表现良好,在那曲地区虽然相关系数较高,但MAE和RMSE同样较高,导致精度较差。(3)对比其他两种产品,修改后的SCA模型反演结果在两个地区表现出较高的相关系数(接近0.800)、较低的MAE(接近0.050m^3·m^(-3))和RMSE(接近0.060 m^3·m^(-3)),有着较高的精度。因此,可以认为修改后的SCA模型可以应用于青藏高原地区土壤湿度动态监测,为研究青藏高原地区的天气和气候变化影响及水循环过程提供了参考和借鉴。
文摘针对在地空频率选择性衰落信道中,信道冲激响应具有时域稀疏特性的情况,提出了基于贪婪算法的单载波频域均衡（SC-FDE）系统稀疏信道估计方法。Chu序列是SC-FDE中常用的导频序列,对其进行分析并证明了将Chu序列进行循环移位所构造的导频矩阵满足RIP条件,将导频矩阵作为测量矩阵,把地空信道估计问题建模为稀疏重构模型,采用贪婪算法中的OMP和Co Sa MP算法对信道进行稀疏重构,仿真验证了所得信道估计较传统最小二乘（LS）信道估计方法更加准确。在相同的训练序列长度和信道环境下,利用所得信道估计对接收信号进行最小均方误差（MMSE）均衡,蒙特卡罗仿真结果表明,所提方法与传统LS信道估计方法相比,系统误码性能提高2~3 d B。
