This paper presents a Markov random field （MRP） approach to estimating and sampling the probability distribution in populations of solutions. The approach is used to define a class of algorithms under the general he...This paper presents a Markov random field （MRP） approach to estimating and sampling the probability distribution in populations of solutions. The approach is used to define a class of algorithms under the general heading distribution estimation using Markov random fields （DEUM）. DEUM is a subclass of estimation of distribution algorithms （EDAs） where interaction between solution variables is represented as an undirected graph and the joint probability of a solution is factorized as a Gibbs distribution derived from the structure of the graph. The focus of this paper will be on describing the three main characteristics of DEUM framework, which distinguishes it from the traditional EDA. They are： 1） use of MRF models, 2） fitness modeling approach to estimating the parameter of the model and 3） Monte Carlo approach to sampling from the model.展开更多
【目的】预测番茄褐色皱纹果病毒(Tomato brown rugose fruit virus,ToBRFV)在中国的潜在地理分布,为其分布、扩散、监测、检疫与防控提供重要数据参考。【方法】基于ToBRFV在全球的分布位点与环境变量数据,经Pearson相关性分析筛选后,...【目的】预测番茄褐色皱纹果病毒(Tomato brown rugose fruit virus,ToBRFV)在中国的潜在地理分布,为其分布、扩散、监测、检疫与防控提供重要数据参考。【方法】基于ToBRFV在全球的分布位点与环境变量数据,经Pearson相关性分析筛选后,运用优化的MaxEnt物种分布模型预测当前环境条件下ToBRFV在中国的潜在地理分布,并结合刀切检验法(Jackknife)分析影响ToBRFV发生与分布的关键环境变量。【结果】ToBRFV在中国七大地理区域均有分布,高适生区主要分布于西南、西北东部和华北南部地区;中适生区主要分布于华东、华中和华南地区。月平均昼夜温差(Bio2)、温度季节性变化标准差(Bio4)、最湿季平均气温(Bio8)和最干季平均气温(Bio9)是影响ToBRFV发生与分布的关键环境变量,累计贡献率和置换重要性分别高达84.8%和89.1%。【结论】ToBRFV在中国的潜在地理分布区域较广,中高适生区主要集中在中国南部、中部和东部地区,应加强早期预测预警,防止ToBRFV进一步传播与扩散。展开更多
Based on the remote sensing images of algae, the present work analyzes the horizontal distribution characteristics of algal blooms in Chaohu Lake, China, which also reveals the frequency of algal blooms under differen...Based on the remote sensing images of algae, the present work analyzes the horizontal distribution characteristics of algal blooms in Chaohu Lake, China, which also reveals the frequency of algal blooms under different wind directions. Further, an unstructured-grid, three-dimensional finite-volume coastal ocean model （FVCOM） is applied to investigate the wind-induced currents and the transport pro- cess to explain the reason why algal blooms occur at the detected places. We first deduce the primary distribution of biomass from overlaid satellite images, and explain the formation mechanism by analyzing the pollution sources, and simulating the flow field and transportation process under prevailing wind over Chaohu Lake. And then, we consider the adjustment action of the wind on the corresponding day and develop a two-time scale approach to describe the whole formation process of algae horizontal distribution in Chaohu Lake. That is, on the longer time scale, i.e., during bloom season, prevailing wind determines the primary distribution of biomass by inducing the characteristic flow field; on the shorter time scale, i.e., on the day when bloom occurs, the wind force adjusts the primary distribution of biomass to form the final distribution of algal bloom.展开更多
We use the strong field approximation with a time window function controlling the release time of electrons to study the intra-cycle and inter-cycle interferences in few-cycle intense laser pulses impinging on He. The...We use the strong field approximation with a time window function controlling the release time of electrons to study the intra-cycle and inter-cycle interferences in few-cycle intense laser pulses impinging on He. The diffraction fringes, i.e., the vertical stripe-like structure, observed in the experimental two-dimensional photoelectron momentum distributions of Gopal et al. （2009 Phys. Rev. Lett. 103 053001） have been attributed to the interplay of the intra- and inter-cycle interferences. The pure numerical calculations by solving the time-dependent Schrrdinger equation are also performed and the results are compared with the experimental measurements directly. It has been found that the position of the stripe-like structure can be used to determine the duration of the laser pulses used in experiments.展开更多
Grain boundary engineering（GBE） is a practice of improving resistance to grain boundary failure of the material through increasing the proportion of low Σ coincidence site lattice（CSL） grain boundaries（special g...Grain boundary engineering（GBE） is a practice of improving resistance to grain boundary failure of the material through increasing the proportion of low Σ coincidence site lattice（CSL） grain boundaries（special grain boundaries） in the grain boundary character distribution（GBCD）. The GBCD in a cold rolled and annealed Fe-18Cr-18Mn-0.63N high-nitrogen austenitic stainless steel was analyzed by electron back scatter difraction（EBSD）. The results show that the optimization process of GBE in the conventional austenitic stainless steel cannot be well applied to this high-nitrogen austenitic stainless steel. The percentage of low ΣCSL grain boundaries could increase from 47.3% for the solid solution treated high-nitrogen austenitic stainless steel specimen to 82.0% for the specimen after 5% cold rolling reduction and then annealing at 1423 K for 10 min.These special boundaries of high proportion efectively interrupt the connectivity of conventional high angle grain boundary network and thus achieve the GBCD optimization for the high-nitrogen austenitic stainless steel.展开更多
In this paper, we consider the location model Y = θ + 6, where θ is an unknown parameter, and e is the error belonging to the interval [a,b]. We assume that θhas the following density function: Then we give the lim...In this paper, we consider the location model Y = θ + 6, where θ is an unknown parameter, and e is the error belonging to the interval [a,b]. We assume that θhas the following density function: Then we give the limiting distribution of MLE θn for 1 < min(α,β) < 2 and consider the Bahadur asymptotic estimator. Since the results depend only on α,β,C1,C2 and are independent of the concrete form of f(x), they have adaptability.展开更多
文摘This paper presents a Markov random field （MRP） approach to estimating and sampling the probability distribution in populations of solutions. The approach is used to define a class of algorithms under the general heading distribution estimation using Markov random fields （DEUM）. DEUM is a subclass of estimation of distribution algorithms （EDAs） where interaction between solution variables is represented as an undirected graph and the joint probability of a solution is factorized as a Gibbs distribution derived from the structure of the graph. The focus of this paper will be on describing the three main characteristics of DEUM framework, which distinguishes it from the traditional EDA. They are： 1） use of MRF models, 2） fitness modeling approach to estimating the parameter of the model and 3） Monte Carlo approach to sampling from the model.
文摘【目的】预测番茄褐色皱纹果病毒(Tomato brown rugose fruit virus,ToBRFV)在中国的潜在地理分布,为其分布、扩散、监测、检疫与防控提供重要数据参考。【方法】基于ToBRFV在全球的分布位点与环境变量数据,经Pearson相关性分析筛选后,运用优化的MaxEnt物种分布模型预测当前环境条件下ToBRFV在中国的潜在地理分布,并结合刀切检验法(Jackknife)分析影响ToBRFV发生与分布的关键环境变量。【结果】ToBRFV在中国七大地理区域均有分布,高适生区主要分布于西南、西北东部和华北南部地区;中适生区主要分布于华东、华中和华南地区。月平均昼夜温差(Bio2)、温度季节性变化标准差(Bio4)、最湿季平均气温(Bio8)和最干季平均气温(Bio9)是影响ToBRFV发生与分布的关键环境变量,累计贡献率和置换重要性分别高达84.8%和89.1%。【结论】ToBRFV在中国的潜在地理分布区域较广,中高适生区主要集中在中国南部、中部和东部地区,应加强早期预测预警,防止ToBRFV进一步传播与扩散。
基金supported by the Hundred Talents Program of Chinese Academy of Sciencesthe National Natural Science Fundation of China for Distinguished Young Scholar(10825211)
文摘Based on the remote sensing images of algae, the present work analyzes the horizontal distribution characteristics of algal blooms in Chaohu Lake, China, which also reveals the frequency of algal blooms under different wind directions. Further, an unstructured-grid, three-dimensional finite-volume coastal ocean model （FVCOM） is applied to investigate the wind-induced currents and the transport pro- cess to explain the reason why algal blooms occur at the detected places. We first deduce the primary distribution of biomass from overlaid satellite images, and explain the formation mechanism by analyzing the pollution sources, and simulating the flow field and transportation process under prevailing wind over Chaohu Lake. And then, we consider the adjustment action of the wind on the corresponding day and develop a two-time scale approach to describe the whole formation process of algae horizontal distribution in Chaohu Lake. That is, on the longer time scale, i.e., during bloom season, prevailing wind determines the primary distribution of biomass by inducing the characteristic flow field; on the shorter time scale, i.e., on the day when bloom occurs, the wind force adjusts the primary distribution of biomass to form the final distribution of algal bloom.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11274219 and 11264036)the STU Scientific Research Foundation forTalentsthe Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry,China
文摘We use the strong field approximation with a time window function controlling the release time of electrons to study the intra-cycle and inter-cycle interferences in few-cycle intense laser pulses impinging on He. The diffraction fringes, i.e., the vertical stripe-like structure, observed in the experimental two-dimensional photoelectron momentum distributions of Gopal et al. （2009 Phys. Rev. Lett. 103 053001） have been attributed to the interplay of the intra- and inter-cycle interferences. The pure numerical calculations by solving the time-dependent Schrrdinger equation are also performed and the results are compared with the experimental measurements directly. It has been found that the position of the stripe-like structure can be used to determine the duration of the laser pulses used in experiments.
基金supported by National Natural Science Foundation of China(Nos.51201027 and 51271054)Fundamental Research Funds for the Central Universities of China(Nos.N110105001,N120405001 and N120505001)
文摘Grain boundary engineering（GBE） is a practice of improving resistance to grain boundary failure of the material through increasing the proportion of low Σ coincidence site lattice（CSL） grain boundaries（special grain boundaries） in the grain boundary character distribution（GBCD）. The GBCD in a cold rolled and annealed Fe-18Cr-18Mn-0.63N high-nitrogen austenitic stainless steel was analyzed by electron back scatter difraction（EBSD）. The results show that the optimization process of GBE in the conventional austenitic stainless steel cannot be well applied to this high-nitrogen austenitic stainless steel. The percentage of low ΣCSL grain boundaries could increase from 47.3% for the solid solution treated high-nitrogen austenitic stainless steel specimen to 82.0% for the specimen after 5% cold rolling reduction and then annealing at 1423 K for 10 min.These special boundaries of high proportion efectively interrupt the connectivity of conventional high angle grain boundary network and thus achieve the GBCD optimization for the high-nitrogen austenitic stainless steel.
文摘In this paper, we consider the location model Y = θ + 6, where θ is an unknown parameter, and e is the error belonging to the interval [a,b]. We assume that θhas the following density function: Then we give the limiting distribution of MLE θn for 1 < min(α,β) < 2 and consider the Bahadur asymptotic estimator. Since the results depend only on α,β,C1,C2 and are independent of the concrete form of f(x), they have adaptability.
