The theory of the concept lattice is an efficient tool for knowledge representation and knowledge discovery, and is applied to many fields successfully. One focus of knowledge discovery is knowledge reduction. This pa...The theory of the concept lattice is an efficient tool for knowledge representation and knowledge discovery, and is applied to many fields successfully. One focus of knowledge discovery is knowledge reduction. This paper proposes the theory of attribute reduction in the concept lattice, which extends the theory of the concept lattice. In this paper, the judgment theorems of consistent sets are examined, and the discernibility matrix of a formal context is introduced, by which we present an approach to attribute reduction in the concept lattice. The characteristics of three types of attributes are analyzed.展开更多
The theory of concept lattices is an efficient tool for knowledge representation and knowledge discovery, and is applied to many fields successfully. One focus of knowledge discovery is knowledge reduction. Based on t...The theory of concept lattices is an efficient tool for knowledge representation and knowledge discovery, and is applied to many fields successfully. One focus of knowledge discovery is knowledge reduction. Based on the reduction theory of classical formal context, this paper proposes the definition of decision formal context and its reduction theory, which extends the reduction theory of concept lattices. In this paper, strong consistence and weak consistence of decision formal context are defined respectively. For strongly consistent decision formal context, the judgment theorems of consistent sets are examined, and approaches to reduction are given. For weakly consistent decision formal context, implication mapping is defined, and its reduction is studied. Finally, the relation between reducts of weakly consistent decision formal context and reducts of implication mapping is discussed.展开更多
In this mini-review we summarize the progress of Lattice Boltzmann （LB） modeling and simulating compressible flows in our group in recent years. Main contents include （i） Single-Relaxation-Time （SRT） LB model su...In this mini-review we summarize the progress of Lattice Boltzmann （LB） modeling and simulating compressible flows in our group in recent years. Main contents include （i） Single-Relaxation-Time （SRT） LB model supplemented by additional viscosity, （ii） Multiple-Relaxation-Time （MRT） LB model, and （iii） LB study on hydrodynamic instabilities. The former two belong to improvements of physical modeling and the third belongs to simulation or application. The SRT-LB model sup- plemented by additional viscosity keeps the original framework of Lattice Bhatnagar-Gross Krook （LBGK）. So, it is easier and more convenient for previous SRT-LB users. The MRT-LB is a com- pletely new framework for physical modeling. It significantly extends the range of LB applications. The cost is longer computational time. The developed SRT-LB and MRT-LB are complementary from the sides of convenience and applicability.展开更多
This article deals with the solute transport in a single fracture with the combination of the Lattice Boltzmann Method （LBM） and Modified Moment Propagation （MMP） method, and this mixed method is proved to have se...This article deals with the solute transport in a single fracture with the combination of the Lattice Boltzmann Method （LBM） and Modified Moment Propagation （MMP） method, and this mixed method is proved to have several advantages over the LBM and Moment Propagation （MP） mixed method which leads to negative concentrations under some conditions in computation. The disadvantage of LBM/MP has been overcome to a certain extent. Also, this work presents an LBM solution of modeling single fractures with uniformly or randomly distributed grains, which can provide a new path of applying the LBM in solute transport simulation in fractures.展开更多
该文提出了一种基于LWE(Learning With Errors)算法的密文域可逆隐写方案,利用LWE公钥密码算法对数据加密,用户在密文中嵌入隐藏信息,对于嵌入信息后的密文,用户使用隐写密钥可以有效提取隐藏信息,使用解密密钥可以无差错恢复出加密前...该文提出了一种基于LWE(Learning With Errors)算法的密文域可逆隐写方案,利用LWE公钥密码算法对数据加密,用户在密文中嵌入隐藏信息,对于嵌入信息后的密文,用户使用隐写密钥可以有效提取隐藏信息,使用解密密钥可以无差错恢复出加密前数据实现了提取过程与解密过程的可分离。通过推导方案在解密与提取信息过程中出错的概率,得到直接影响方案正确性的参数为所选噪声的标准差,实验获得并验证了标准差的合理取值区间;通过推导嵌入后密文的分布函数,分析密文统计特征的变化情况,论证了嵌入密文的隐藏信息的不可感知性。该方案是在密文域进行的可逆隐写,与原始载体无关,适用于文本、图片、音频等各类载体。实验仿真结果表明该方案不仅能够保证可逆隐写的可靠性与安全性,而且1 bit明文在密文域最大可负载1 bit隐藏信息。展开更多
There exist interactions among pedestrians and between pedestrian and environment in evacuation. These interactions include attraction, repulsion and friction that play key roles in human evacuation behaviors, speed a...There exist interactions among pedestrians and between pedestrian and environment in evacuation. These interactions include attraction, repulsion and friction that play key roles in human evacuation behaviors, speed and efficiency. Most former evacuation models focus on the attraction force, while repulsion and friction are not well modeled. As a kind of multi-particle self-driven model, the social force model introduced in recent years can represent those three forces but with low simulation efficiency because it is a continuous model with complex rules. Discrete models such as the cellular automata model and the lattice gas model have simple rules and high simulation efficiency, but are not quite suitable for interactions’ simulation. In this paper, a new cellular automata model based on traditional models is introduced in which repulsion and friction are modeled quantitatively. It is indicated that the model can simulate some basic behaviors, e.g. arching and the “faster-is-slower” phenomenon, in evacuation as multi-particle self-driven models, but with high efficiency as the normal cellular automata model and the lattice gas model.展开更多
Thermal controllers equipped with phase-change materials are widely used for maintaining the moderate temperatures of various electric devices used in spacecraft. Yet, the structures of amounts of thermal controllers ...Thermal controllers equipped with phase-change materials are widely used for maintaining the moderate temperatures of various electric devices used in spacecraft. Yet, the structures of amounts of thermal controllers add up to such a large value that restricts the employment of scientific devices due to the limit of rocket capacity. A lightweight structure of phase-change thermal controllers has been one of the main focuses of spacecraft design engineering. In this work, we design a lightweight phase-change thermal controller structure based on lattice cells. The structure is manufactured entirely with AlSi10 Mg by direct metal laser melting. The dimensions of the structure are 230 mm × 170 mm × 15 mm, and the mass is 190 g, which is 60% lighter than most traditional structures(500–600 g) with the same dimensions. The 3 D-printed structure can reduce the risk of leakage at soldering manufacture by a welding process. Whether the strength of the designed structure is sufficient is determined through mechanical analysis and experiments. Thermal test results show that the thermal capacity of the lattice-based thermal controller is increased by50% compared to that of traditional controllers with the same volume.展开更多
A supercomputer with 1.0 Petaflops peak performance in single precision, designed and established by Institute of Process Engineering, Chinese Academy of Sciences, is introduced in this brief communication. A designin...A supercomputer with 1.0 Petaflops peak performance in single precision, designed and established by Institute of Process Engineering, Chinese Academy of Sciences, is introduced in this brief communication. A designing philosophy utilizing the similarity between hardware, software and the problems to be solved is embodied, based on the multi-scale method and discrete simulation approaches developed at Institute of Process Engineering （IPE） and implemented in a graphic processing unit （GPU）-based hybrid computing mode. The preliminary applications of this machine in areas of multi-phase flow, molecular dynamics and so on are reported, demonstrating the supercomputer as a paradigm of green computation in new architecture.展开更多
The concept of locally strong compactness on domains is generalized to general topological spaces. It is proved that for each distributive hypercontinuous lattice L, the space SpecL of nonunit prime elements endowed w...The concept of locally strong compactness on domains is generalized to general topological spaces. It is proved that for each distributive hypercontinuous lattice L, the space SpecL of nonunit prime elements endowed with the hull-kernel topology is locally strongly compact, and for each locally strongly compact space X, the complete lattice of all open sets O(X) is distributive hypercontinuous. For the case of distributive hyperalgebraic lattices, the similar result is given. For a sober space X, it is shown that there is an order reversing isomorphism between the set of upper-open filters of the lattice O(X) of open subsets of X and the set of strongly compact saturated subsets of X, which is analogous to the well-known Hofmann-Mislove Theorem.展开更多
基金This work was supported by the National 973 Program of China(Grant No．2002CB3 1 2200)the National Natural Science Foundation of China(Grant No．60373038) the Natural Scientific Research Project ofthe Education Department ofShaanxi Province in China(Grant No．04JK131)．
文摘The theory of the concept lattice is an efficient tool for knowledge representation and knowledge discovery, and is applied to many fields successfully. One focus of knowledge discovery is knowledge reduction. This paper proposes the theory of attribute reduction in the concept lattice, which extends the theory of the concept lattice. In this paper, the judgment theorems of consistent sets are examined, and the discernibility matrix of a formal context is introduced, by which we present an approach to attribute reduction in the concept lattice. The characteristics of three types of attributes are analyzed.
基金the National 973 Program of China (Grant No.2002CB312200)the National Natural Science Foundation of China (Grant Nos.60703117, 60433010 and 60673096)the Doctor Research Fund of Northwest University in China
文摘The theory of concept lattices is an efficient tool for knowledge representation and knowledge discovery, and is applied to many fields successfully. One focus of knowledge discovery is knowledge reduction. Based on the reduction theory of classical formal context, this paper proposes the definition of decision formal context and its reduction theory, which extends the reduction theory of concept lattices. In this paper, strong consistence and weak consistence of decision formal context are defined respectively. For strongly consistent decision formal context, the judgment theorems of consistent sets are examined, and approaches to reduction are given. For weakly consistent decision formal context, implication mapping is defined, and its reduction is studied. Finally, the relation between reducts of weakly consistent decision formal context and reducts of implication mapping is discussed.
文摘In this mini-review we summarize the progress of Lattice Boltzmann （LB） modeling and simulating compressible flows in our group in recent years. Main contents include （i） Single-Relaxation-Time （SRT） LB model supplemented by additional viscosity, （ii） Multiple-Relaxation-Time （MRT） LB model, and （iii） LB study on hydrodynamic instabilities. The former two belong to improvements of physical modeling and the third belongs to simulation or application. The SRT-LB model sup- plemented by additional viscosity keeps the original framework of Lattice Bhatnagar-Gross Krook （LBGK）. So, it is easier and more convenient for previous SRT-LB users. The MRT-LB is a com- pletely new framework for physical modeling. It significantly extends the range of LB applications. The cost is longer computational time. The developed SRT-LB and MRT-LB are complementary from the sides of convenience and applicability.
文摘引入了一种二元Lattice Boltzmann Model(LBM),实现了两种液体组成的混合流的模拟.不同于其它的类似模型,它区分考虑了流体的粘性和扩散特性,可以很容易地模拟各种互溶或者不互溶的混合流现象.此外,由于LBM的运算大都是线性的局部运算,这使得它很容易在可编程图形处理器(Graphics Process Unit,GPU)上进行加速,从而进行实时模拟.给出了若干二元混合流的模拟结果.
基金the National Natural Science Foundation of China (Grant No. 50579012)
文摘This article deals with the solute transport in a single fracture with the combination of the Lattice Boltzmann Method （LBM） and Modified Moment Propagation （MMP） method, and this mixed method is proved to have several advantages over the LBM and Moment Propagation （MP） mixed method which leads to negative concentrations under some conditions in computation. The disadvantage of LBM/MP has been overcome to a certain extent. Also, this work presents an LBM solution of modeling single fractures with uniformly or randomly distributed grains, which can provide a new path of applying the LBM in solute transport simulation in fractures.
文摘该文提出了一种基于LWE(Learning With Errors)算法的密文域可逆隐写方案,利用LWE公钥密码算法对数据加密,用户在密文中嵌入隐藏信息,对于嵌入信息后的密文,用户使用隐写密钥可以有效提取隐藏信息,使用解密密钥可以无差错恢复出加密前数据实现了提取过程与解密过程的可分离。通过推导方案在解密与提取信息过程中出错的概率,得到直接影响方案正确性的参数为所选噪声的标准差,实验获得并验证了标准差的合理取值区间;通过推导嵌入后密文的分布函数,分析密文统计特征的变化情况,论证了嵌入密文的隐藏信息的不可感知性。该方案是在密文域进行的可逆隐写,与原始载体无关,适用于文本、图片、音频等各类载体。实验仿真结果表明该方案不仅能够保证可逆隐写的可靠性与安全性,而且1 bit明文在密文域最大可负载1 bit隐藏信息。
文摘There exist interactions among pedestrians and between pedestrian and environment in evacuation. These interactions include attraction, repulsion and friction that play key roles in human evacuation behaviors, speed and efficiency. Most former evacuation models focus on the attraction force, while repulsion and friction are not well modeled. As a kind of multi-particle self-driven model, the social force model introduced in recent years can represent those three forces but with low simulation efficiency because it is a continuous model with complex rules. Discrete models such as the cellular automata model and the lattice gas model have simple rules and high simulation efficiency, but are not quite suitable for interactions’ simulation. In this paper, a new cellular automata model based on traditional models is introduced in which repulsion and friction are modeled quantitatively. It is indicated that the model can simulate some basic behaviors, e.g. arching and the “faster-is-slower” phenomenon, in evacuation as multi-particle self-driven models, but with high efficiency as the normal cellular automata model and the lattice gas model.
基金supports from Beijing Institute of Spacecraft System Engineering and the Young Elite Scientists Sponsorship Program by China Association for Science and Technology(Nos.2017QNRC001,2016QNRC001)
文摘Thermal controllers equipped with phase-change materials are widely used for maintaining the moderate temperatures of various electric devices used in spacecraft. Yet, the structures of amounts of thermal controllers add up to such a large value that restricts the employment of scientific devices due to the limit of rocket capacity. A lightweight structure of phase-change thermal controllers has been one of the main focuses of spacecraft design engineering. In this work, we design a lightweight phase-change thermal controller structure based on lattice cells. The structure is manufactured entirely with AlSi10 Mg by direct metal laser melting. The dimensions of the structure are 230 mm × 170 mm × 15 mm, and the mass is 190 g, which is 60% lighter than most traditional structures(500–600 g) with the same dimensions. The 3 D-printed structure can reduce the risk of leakage at soldering manufacture by a welding process. Whether the strength of the designed structure is sufficient is determined through mechanical analysis and experiments. Thermal test results show that the thermal capacity of the lattice-based thermal controller is increased by50% compared to that of traditional controllers with the same volume.
文摘A supercomputer with 1.0 Petaflops peak performance in single precision, designed and established by Institute of Process Engineering, Chinese Academy of Sciences, is introduced in this brief communication. A designing philosophy utilizing the similarity between hardware, software and the problems to be solved is embodied, based on the multi-scale method and discrete simulation approaches developed at Institute of Process Engineering （IPE） and implemented in a graphic processing unit （GPU）-based hybrid computing mode. The preliminary applications of this machine in areas of multi-phase flow, molecular dynamics and so on are reported, demonstrating the supercomputer as a paradigm of green computation in new architecture.
基金Project supported by the National Natural Science Foundation of China (Nos. 10331010, 10861007)the Foundation for the Author of National Excellent Doctoral Dissertation of China (No. 2007B14)+2 种基金the Jiangxi Provincial Natural Science Foundation of China (Nos. 0411025, 2007GZS0179)the Foundation of the Education Department of Jiangxi Province (No. GJJ08162)the Doctoral Fund of Jiangxi Normal University
文摘The concept of locally strong compactness on domains is generalized to general topological spaces. It is proved that for each distributive hypercontinuous lattice L, the space SpecL of nonunit prime elements endowed with the hull-kernel topology is locally strongly compact, and for each locally strongly compact space X, the complete lattice of all open sets O(X) is distributive hypercontinuous. For the case of distributive hyperalgebraic lattices, the similar result is given. For a sober space X, it is shown that there is an order reversing isomorphism between the set of upper-open filters of the lattice O(X) of open subsets of X and the set of strongly compact saturated subsets of X, which is analogous to the well-known Hofmann-Mislove Theorem.
