检索结果-南通市图书馆

Acta Mechanica Sinica 2012年第6期28卷 1602-1616页

作者： jun Liu Zheng Nan Ping yi School of Hydraulic Engineering Dalian University of Technology School of Civil Engineering Dalian University of Technology

In the last decade, three dimensional discontin- uous deformation analyses （3D DDA） has attracted more and more attention of researchers and geotechnical engineers worldwide. The original DDA formulation utilizes a linear displacement function to describe the block movement and deformation, which would cause block expansion under rigid body rotation and thus limit its capability to model block de- formation. In this paper, 3D DDA is coupled with tetrahe- dron finite elements to tackle these two problems. Tetrahe- dron is the simplest in the 3D domain and makes it easy to implement automatic discretization, even for complex topol- ogy shape. Furthermore, element faces will remain planar and element edges will remain straight after deformation for tetrahedron finite elements and polyhedral contact detection schemes can be used directly. The matrices of equilibrium equations for this coupled method are given in detail and an effective contact searching algorithm is suggested. Valida- tion is conducted by comparing the results of the proposed coupled method with that of physical model tests using one of the most common failure modes, i.e., wedge failure. Most of the failure modes predicted by the coupled method agree with the physical model results except for 4 cases out of the total 65 cases. Finally, a complex rockslide example demon- strates the robustness and versatility of the coupled method.

关键词： Three-dimensional discontinuous deformation analysis Finite element method Coupled method Valida-tion

Analysis of 3D curve expansion of conical cam with oscillating tapered roller follower

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第11期8卷 1789-1794页

作者： CHEN jun-hua WU yi-jie Ningbo Institute of Technology Zhejiang University Ningbo 315010 China Institute of Modern Manufacture Engineering Zhejiang University Hangzhou 310027 China

This paper focuses on the analysis of running conditions and machining processes of conical cam with oscillating follower. We point out the common errors existing in the design and machining of the widely used plane expansion method of conical cam trough-out line. We show that the motion can be divided into two parts, i.e. the oscillating motion of oscillating bar and the rotary motion of oscillating bar relative to the conical cam. By increasing the rotary motion of oscillating bar, the motion path of tapered roller on oscillating bar (i.e. contour surface of conical cam) can be expanded on the cylinder. Based on these analyses, we present a creative and effective designing and machining method for 3D curve expansion of conical cam with oscillating follower.

关键词： Oscillating follower Conical cam Tapered roller plane expansion 3D curve expansion

Research in non-equalization machining method for spatial cam

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第9期9卷 1258-1263页

作者： jun-hua CHEN yi-jie WU Institute of Mechanical and Electrical Engineering Ningbo Institute of Technology Zhefiang University Ningbo 315010 China Institute of Modern Manufacture Engineering Zhejiang University Hangzhou 310027 China

Many kinds of devices with cam have been widely used in various mechanical equipments. However, non-equalization machining for spatial cam trough remains to be a difficult problem. This paper focuses on the analysis of running conditions and machining processes of spatial cam with oscillating follower. We point out the common errors in the biased distance cutting. By analyzing the motion of oscillating follower of spatial cam, we present a new 3D curve expansion model of spatial cam trough-outline. Based on this model, we have proposed a machining method for trochoidal milling with non-equalization diameter cutter. This new method has led to a creative and effective way for non-equalization diameter machining for spatial cam with oscillating follower.

关键词： Oscillating follower Spatial cam 3D curve exoansion Trochoidal milling Non-eaualization diameter

Use of various MgO resources for high-purity Mg metal production through molten salt electrolysis and vacuum distillation

在线全文

学校读者我要写书评

暂无评论

Journal of Magnesium and Alloys 2023年第2期11卷 562-579页

作者： Hyeong-jun Jeoung Tae-Hyuk Lee Youngjae kim Jin-Young Lee Young Min kim Toru HOkabe Kyung-Woo yi jungshin Kang Korea Institute of Geoscience and Mineral Resources 124 Gwahak-ro Yuseong-guDaejeon 34132South Korea Department of Materials Science and Engineering Seoul National University1 Gwanak-roGwanak-guSeoul 08826South Korea Department of Resources Engineering University of Science and Technology217 Gajeong-ro Yuseong-guDaejeon 34113South Korea Korea Institute of Materials Science 797 Changwondae-roSeongsan-guChangwonGyeongnam 51508South Korea Institute of Industrial Science The University of Tokyo4-6-1 KomabaMeguro-kuTokyo 153-8505Japan School of Materials Science and Engineering Pusan National University2 Busandaehak-roGeumjeong-guBusan 44241South Korea

A green and effective electrolytic process was developed to produce high-purity Mg metal using primary and secondary resources containing Mg O as a feedstock. The electrolysis of various Mg O resources was conducted using a Cu cathode in MgF2– LiF – KCl molten salt at 1043 K by applying an average current of 1.44 A for 12.5 h. The electrolysis of calcined North Korean magnesite and seawater Mg O clinker yielded Mg alloys of MgCu2and(Cu) phases with current efficiencies of 89.6–92.4%. The electrolysis of oxidized Mg O-C refractory brick, aged ferronickel slag, and ferronickel slag yielded Mg alloys of MgCu2and(Cu) phases with current efficiencies of 59.3–92.3%. The vacuum distillation of Mg alloys obtained was conducted at 1300 K for 10 h to produce high-purity Mg metal. After vacuum distillation, Mg metal with a purity of above 99.994% was obtained. Therefore, this study demonstrates the feasibility of the production of high-purity Mg metal from various Mg O resources using a novel electrolytic process with a Cu cathode, followed by vacuum distillation.

关键词： High-purity magnesium Magnesium oxide resources Electrolytic process Metal cathode Vacuum distillation

Improvement of the Bayesian neural network to study the photoneutron yield cross sections

在线全文

学校读者我要写书评

暂无评论

Nuclear Science and Techniques 2022年第11期33卷 1-9页

作者： Yong-yi Li Fan Zhang jun Su Department of Computing Changzhi UniversityChangzhi 046011China Department of Physics Changzhi UniversityChangzhi 046011China Sino-French Institute of Nuclear Engineering and Technology Sun Yat-sen UniversityZhuhai 519082China

This work is an attempt to improve the Bayesian neural network (BNN) for studying photoneutron yield cross sections as a function of the charge number Z, mass number A, and incident energy ε. The BNN was improved in terms of three aspects:numerical parameters, input layer, and network structure. First, by minimizing the deviations between the predictions and data, the numerical parameters, including the hidden layer number, hidden node number, and activation function, were selected. It was found that the BNN with three hidden layers, 10 hidden nodes, and sigmoid activation function provided the smallest deviations. Second, based on known knowledge,such as the isospin dependence and shape effect, the optimal ground-state properties were selected as input neurons. Third, the Lorentzian function was applied to map the hidden nodes to the output cross sections, and the empirical formula of the Lorentzian parameters was applied to link some of the input nodes to the output cross sections. It was found that the last two aspects improved the predictions and avoided overfitting, especially for the axially deformed nucleus.

关键词： Bayesian neural network Photoneutron cross sections Giant dipole resonance

Solving Two Kinds of JC Models Relating to Two-Photon Process by Supersymmetric Transformation

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2004年第2X期42卷 193-196页

作者： FANHong-yi GUIWei-jun DepartmentofMaterialScienceandEngineering UniversityofScienceandTechnologyofChinaHefei230026China

We propose two kinds of new Jaynes Cummings models relating to two-photon process by using the supersymmetric unitary transformation. The corresponding energy eigenvalues and eigenvectors are obtained.

关键词：超对称转换 Jaynes-Cummings模型双光子处理本征矢量原子-光子相互作用哈密顿算符

One-Sided Squeezing for Two Special Kinds of Tripartite Entangled States

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2004年第4X期42卷 505-508页

作者： FANHong-yi GUIWei-jun DepartmentofMaterialScienceandEngineering UniversityofScienceandTechnologyofChinaHefei230026China

Based on two mutual conjugate tripartite entangled states |η, σ〉θ and |ζ, τ〉θ we generalize the two-mode one-sided squeezing operators to three-mode case. We derive how the tripartite entangled states transform under the three-mode squeezing operators. We conclude that the entangled state representations provide a convenient basis for deriving various three-mode squeezing operators.

关键词：三模压缩算子三模纠缠态量子光学量子探测单边压缩量子纠缠

Optimal proportional reinsurance and dividend payments with transaction costs and internal competition

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics(A Journal of Chinese Universities) 2016年第1期31卷 89-102页

作者： LIU Wei HU yi-jun School of Mathematics and System Sciences Xinjiang University School of Mathematics and Statistics Wuhan University

We study the dividend optimization problem for an insurance company under the consideration of internal competition between different units inside company and transaction costs when dividends occur. The management of the company controls the reinsurance rate, the timing and the amount of dividends paid out to maximize the expected total dividends paid out to the shareholders until ruin time. By solving the corresponding quasi-variational inequality, we obtain the optimal return function and the optimal strategy.

关键词： Dividend proportional reinsurance transaction costs internal competition quasi-variational inequality.

On Consistency of the Nearest Neighbor Estimator of the Density Function and Its Applications

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2019年第5期35卷 703-720页

作者： yi WU Xue jun WANG School of Mathematical Sciences Anhui University

In this paper, we mainly study the consistency of the nearest neighbor estimator of the density function based on asymptotically almost negatively associated samples. The weak consistency,strong consistency, uniformly strong consistency and the convergence rates are established under some mild conditions. As applications, we further investigate the strong consistency and the rate of strong consistency for hazard rate function estimator.

关键词： Nearest neighbor estimator weak consistency strong consistency uniform consistency hazard rate function estimator

Relativistic transformation between τ and TCG for Mars missions under IAU Resolutions

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2014年第2期14卷 233-240页

作者： jun-Yang Pan yi Xie Department of Astronomy Nanjing University Key Laboratory of Modern Astronomy and Astrophysics Nanjing UniversityMinistry of Education

Considering the fact that the general theory of relativity has become an in- extricable part of deep space missions, we investigate the relativistic transformation between the proper time of an onboard clock τ and the Geocentric Coordinate Time （TCG） for Mars missions. By connecting τ with this local timescale associated with the Earth, we extend previous works which focus on the transformation between τ and the Barycentric Coordinate Time （TCB）. （TCB is the global coordinate time for the whole solar system.） For practical convenience, the relation between τ and TCG is recast to directly depend on quantities which can be read from ephemerides. We find that the difference between τ and TCG can reach the level of about 0.2 seconds in a year. To distinguish various sources in the transformation, we numerically calculate the contributions caused by the Sun, eight planets, three large asteroids and the space- craft. It is found that if the threshold of 1 microsecond is adopted, this transformation must include effects due to the Sun, Venus, the Moon, Mars, Jupiter, Saturn and the velocities of the spacecraft and Earth.

关键词： reference systems -- time -- method: numerical -- space vehicles