|
|
|
题名
|
作者
|
年代
|
出处
|
被引量
|
| 1 | Survey on normal distributions,central limit theorem,Brownian motion and the related stochastic calculus under sublinear expectations显示文摘This is a survey on normal distributions and the related central limit theorem under sublinear expectation.We also present Brownian motion under sublinear expectations and the related stochastic calculus of It's type.The results provide new and robust tools for the problem of probability model uncertainty arising in financial risk,statistics and other industrial problems. | PENG ShiGe Institute of Mathematics,Shandong University,Jinan 250100,China | 2009 | Science China Mathematics2009，52，7： | 54 |
| 2 | 固溶温度对激光立体成形GH4169高温合金组织和性能的影响(英文)显示文摘研究激光立体成形GH4169高温合金固溶处理后的组织,分析了固溶过程中合金元素的均匀化,并对材料显微硬度的变化做了讨论。结果表明,随固溶温度的升高,材料的晶界越来越清晰,经1000-1170°C固溶处理1h后材料发生再结晶,当固溶处理温度高于1100°C,有大量孪晶出现,晶粒相比沉积态显著细化,晶粒尺寸约200μm。合金元素的均匀化在1100°C保温1h后基本完成。显微硬度测试结果显示,材料的显微硬度值随固溶温度的升高而降低,在固溶温度低于1100°C时减小趋势较快,高于1100°C时减小趋势减缓。显微硬度的变化与材料中γ′和γ'相及δ相的形态和数量有关。1100°C是激光立体成形GH4169合金比较合适的固溶处理温度下限。 | 刘奋成 林鑫 赵卫卫 赵晓明 陈静 黄卫东 | 2010 | 稀有金属材料与工程2010，39，9： | 29 |
| 3 | Forming limits under multi-index constraints in NC bending of aluminum alloy thin-walled tubes with large diameters显示文摘With increasing diameters of aluminum alloy thin-walled tubes (AATTs), the tube forming limits, i.e. the minimum bending factors, and their predictions under multi-index constraints including wrinkling, thinning and flattening have been being a key problem to be urgently solved for improving tube forming potential in numerical control (NC) bending processes of AATTs with large diameters. Thus in this paper, a search algorithm of the forming limits is put forward based on a 3D elastic-plastic finite element (FE) model and a wrinkling energy prediction model for the bending processes under axial compression loading (ACL) or not. This algorithm enables to be considered the effects of process parameter combinations including die, friction parameters on the multi-indices. Based on this algorithm, the forming limits of the different size tubes are obtained, and the roles of the process parameter combinations in enabling the limit bending processes are also revealed. The followings are found: the first, within the appropriate ranges of friction and clearances between the different dies and the tubes enabling the bending processes with smaller bending factors, the ACL enables the tube limit bending processes after a decrease of the mandrel ball thickness and diameters; then, without considering the effects of the tube geometry sizes on the tube constitutive equations, the forming limits will be decided by the limit thinning values for the tubes with diameters smaller than 80 mm, while the wrinkling for the tubes with diameters no less than 80 mm. The forming limits obtained from this algorithm are smaller than the analytical results, and reduced by 57.39%; the last, the roles of the process parameter combinations in enabling the limit bending processes are verified by experimental results. | YAN Jing, YANG He, ZHAN Mei & LI Heng College of Materials Science and Engineering, State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China | 2010 | Science China(Technological Sciences)2010，53，2： | 21 |
| 4 | Bifurcations of limit cycles in a Z_6-equivariant planar vector field of degree 5显示文摘A concrete numerical example of Z6-equivariant planar perturbed Hamiltonian polynomial vector fields of degree 5 having at least 24 limit cycles and the configurations of compound eyes are given by using the bifurcation theory of planar dynamical systems and the method of detection functions. There is reason to conjecture that the Hilbert number H(2k + 1) ≥ (2k + 1)2 - 1 for the perturbed Hamiltonian systems. | 李继彬 H.S.Y.Chan K.W.Chung | 2002 | Science China Mathematics2002，45，7： | 19 |
| 5 | Seismic fragility analysis of highway bridges considering multi-dimensional performance limit state显示文摘Fragility analysis for highway bridges has become increasingly important in the risk assessment of highway transportation networks exposed to seismic hazards. This study introduces a methodology to calculate fragility that considers multi-dimensional performance limit state parameters and makes a first attempt to develop fragility curves for a multi-span continuous (MSC) concrete girder bridge considering two performance limit state parameters: column ductility and transverse deformation in the abutments. The main purpose of this paper is to show that the performance limit states, which are compared with the seismic response parameters in the calculation of fragility, should be properly modeled as randomly interdependent variables instead of deterministic quantities. The sensitivity of fragility curves is also investigated when the dependency between the limit states is different. The results indicate that the proposed method can be used to describe the vulnerable behavior of bridges which are sensitive to multiple response parameters and that the fragility information generated by this method will be more reliable and likely to be implemented into transportation network loss estimation. | Wang, Qi'ang Wu, Ziyan Liu, Shukui | 2012 | Earthquake Engineering and Engineering Vibration2012，11，2： | 16 |
| 6 | On the number of limit cycles in double homoclinic bifurcations显示文摘Let L be a double homoclinic loop of a Hamiltonian system on the plane. We obtain a condition under which L generates at most two large limit cycles by perturbations. We also give conditions for the existence of at most five or six limit cycles which appear near L under perturbations. | 韩茂安 陈健 | 2000 | Science China Mathematics2000，43，9： | 16 |
| 7 | A general central limit theorem under sublinear expectations显示文摘Under some weaker conditions,we give a central limit theorem under sublinear expectations,which extends Peng's central limit theorem. | LI Min & SHI YuFeng School of Mathematics,Shandong University,Jinan 250100,China | 2010 | Science China Mathematics2010，53，8： | 15 |
| 8 | Review of coal and gas outburst in Australian underground coal mines显示文摘Outburst of coal and gas represents a significant risk to the health and safety of mine personnel working in development and longwall production face areas.There have been over 878 outburst events recorded in twenty-two Australian underground coal mines.Most outburst incidents have been associated with abnormal geological conditions.Details of Australian outburst incidents and mining experience in conditions where gas content was above current threshold levels are presented and discussed.Mining experience suggests that for gas con-tent below 9.0 m^3/t,mining in carbon dioxide(CO2)rich seam gas conditions does not pose a greater risk of outburst than mining in CH4 rich seam gas conditions.Mining experience also suggests that where no abnormal geological structures are present that mining in areas with gas content greater than the current accepted threshold levels can be undertaken with no discernible increase in outburst risk.The current approach to determining gas content threshold limits in Australian mines has been effective in prevent-ing injury from outburst,however operational experience suggests the current method is overly conser-vative and in some cases the threshold limits are low to the point that they provide no significant reduction in outburst risk.Other factors that affect outburst risk,such as gas pressure,coal toughness and stress and geological structures are presently not incorporated into outburst threshold limits adopted in Australian mines.These factors and the development of an outburst risk index applicable to Australian underground coal mining conditions are the subject of ongoing research. | Dennis J.Black | 2019 | International Journal of Mining Science and Technology2019，29，6： | 14 |
| 9 | Cyclicity of planar homoclinic loops and quadratic integrable systems显示文摘A general method for a homoclinic loop of planar Hamiltonian systems to bifurcate two or three limit cycles under perturbations is established.Certain conditions are given under which the cyclicity of a homoclinic loop equals 1 or 2.As an application to quadratic systems,it is proved that the cyclicity of homoclinic loops of quadratic in-tegrable and non-Hamiltonian systems equals 2 except for one case. | 韩茂安 | 1997 | Science China Mathematics1997，40，12： | 13 |
| 10 | 基于改进蝗虫优化算法的特征选择方法显示文摘针对传统蝗虫优化算法寻优精度低和收敛速度慢的问题,提出一种基于非线性调整策略的改进蝗虫优化算法.首先,利用非线性参数代替传统蝗虫算法中的递减系数,协调算法全局探索和局部开发能力,加快算法收敛速度;其次,引入自适应权重系数改变蝗虫位置更新方式,提高算法寻优精度;然后,结合limit阈值思想,利用非线性参数对种群中部分个体进行扰动,避免算法陷入局部最优.通过六个基准测试函数的仿真结果表明,改进算法的收敛速度和寻优精度均有明显提高.最后将改进算法应用于特征选择问题中,通过在七个数据集上的实验结果表明,基于改进算法的特征选择方法能够有效地进行特征选择,提高分类准确率. | 刘亮 何庆 | 2020 | 南京大学学报(自然科学版)2020，56，1： | 12 |
| 11 | Targeting immunometabolism as an anti-inflammatory strategy显示文摘The growing field of immunometabolism has taught us how metabolic cellular reactions and processes not only provide a means to generate ATP and biosynthetic precursors,but are also a way of controlling immunity and inflammation.Metabolic reprogramming of immune cells is essential for both inflammatory as well as anti-inflammatory responses.Four anti-inflammatory therapies,DMF,Metformin,Methotrexate and Rapamycin all work by affecting metabolism and/or regulating or mimicking endogenous metabolites with anti-inflammatory effects.Evidence is emerging for the targeting of specific metabolic events as a strategy to limit inflammation in different contexts.Here we discuss these recent developments and speculate on the prospect of targeting immunometabolism in the effort to develop novel anti-inflammatory therapeutics.As accumulating evidence for roles of an intricate and elaborate network of metabolic processes,including lipid,amino acid and nucleotide metabolism provides key focal points for developing new therapies,we here turn our attention to glycolysis and the TCA cycle to provide examples of how metabolic intermediates and enzymes can provide potential novel therapeutic targets. | Eva M.Palsson-McDermott Luke A.J.O'Neill | 2020 | Cell Research2020，30，4： | 12 |
| 12 | A class of strong deviation theorems and an approach of Laplace transformation显示文摘The limit properties of the dependent sequence of absolutely continuous random variables are investigated by using the notion of likelihood ratio, and a class of strong limit theorems, represented by inequalities, i.e. the strong deviation theorems, are obtained. In the proof an approach of applying the Laplace transformation to the investigation of the strong limit theorems is proposed. | LIU Wen Hebei University of Technology, Tianjin 300130, China | 1998 | Chinese Science Bulletin1998，43，19： | 12 |
| 13 | Predicting excavation damage zone depths in brittle rocks显示文摘During the construction of an underground excavation, damage occurs in the surrounding rock mass due in large part to stress changes. While the predicted damage extent impacts profile selection and support design, the depth of damage is a critical aspect for the design of permeability sensitive excavations, such as a deep geological repository(DGR) for nuclear waste. Review of literature regarding the depth of excavation damage zones(EDZs) indicates three zones are common and typically related to stress induced damage. Based on past developments related to brittle damage prediction using continuum modelling, the depth of the EDZs has been examined numerically. One method to capture stress induced damage in conventional engineering software is the damage initiation and spalling limit(DISL) approach. The variability of depths predicted using the DISL approach has been evaluated and guidelines are suggested for determining the depth of the EDZs around circular excavations in brittle rock masses. Of the inputs evaluated, it was found that the tensile strength produces the greatest variation in the depth of the EDZs. The results were evaluated statistically to determine the best fit relation between the model inputs and the depth of the EDZs. The best correlation and least variation were found for the outer EDZ and the highly damaged zone(HDZ) showed the greatest variation. Predictive equations for different EDZs have been suggested and the maximum numerical EDZ depths, represented by the 68% prediction interval, agreed well with the empirical evidence. This suggests that the numerical limits can be used for preliminary depth prediction of the EDZs in brittle rock for circular excavations. | Matthew A.Perras Mark S.Diederichs | 2016 | Journal of Rock Mechanics and Geotechnical Engineering2016，8，1： | 12 |
| 14 | On the mechanism and control for the ultra-low frequency oscillation in NY Power Grid with large-scale hydropower显示文摘The power grid with large proportion of hydropower may engage the ultra-low frequency oscillation (ULFO),which threatening the operation of system.To the NY Power Grid system,whose dimension is over thousands,this paper reveals the cause of ULFO with the phase portrait method,i.e.,lies in the saturation of the different limits of the governor system of the generators,in other words,the occurrence of limit cycle is due to the non-smooth bifurcation.And furthermore,it proposes two methods to suppress ULFO with the philosophy of destroying the condition of non-smooth bifurcation.In detail,first,the phenomenon of ULFO in NY Power Grid,the damping characteristics and the limits in the governor system of the hydropower units are presented.Second,based on the non-smooth bifurcation theory,the mathematical basis of the oscillation in the non-smooth system caused by the saturation of limits is introduced.And then,the non-oscillation and oscillation dynamic of the system corresponding to without/with limits in the governor system are analyzed.Furthermore,it discusses the influence of the saturation of single limit on the characteristics of ULFO with the phase portraits.Moreover,the phase portraits of the ULFO under different faults is analyzed,and it shows that the limiting saturation occurs with a large enough disturbance.Thus,the ULFO is resulting from the negative damping of generation and the saturation of multiple limits under a large enough disturbance.In addition,according to the above mechanism,two strategies to suppress the ULFO,i.e.,the governor parameters tuning and the fault strength relief are designed.The simulation shows the effectiveness of proposed strategies. | Ancheng XUE Jiawei WANG Chao ZHENG Joe H.CHOW Tianshu BI | 2019 | Control Theory and Technology2019，17，3： | 11 |
| 15 | Boundary Layer Theory and the Zero-Viscosity Limit of the Navier-Stokes Equation | Weinan E Department of Mathematics and Program in Applied and Computational Mathematics,Princeton University,USA | 2000 | Acta Mathematica Sinica,English Series2000，16，2： | 10 |
| 16 | Functional Limit Theorems for C-R Increments of k-Dimensional Brownian Motion in Holder Norm | Qicai Wei School fo Economics, Zhejiang University. Hangzhou 310028. P. R. China | 2000 | Acta Mathematica Sinica,English Series2000，16，4： | 9 |
| 17 | Single-cell biomagnifier for optical nanoscopes and nanotweezers显示文摘Optical microscopes and optical tweezers,which were invented to image and manipulate microscale objects,have revolutionized cellular and molecular biology.However,the optical resolution is hampered by the diffraction limit;thus,optical microscopes and optical tweezers cannot be directly used to image and manipulate nano-objects.The emerging plasmonic/photonic nanoscopes and nanotweezers can achieve nanometer resolution,but the high-index material structures will easily cause mechanical and photothermal damage to biospecimens.Here,we demonstrate subdiffraction-limit imaging and manipulation of nano-objects by a noninvasive device that was constructed by trapping a cell on a fiber tip.The trapped cell,acting as a biomagnifier,could magnify nanostructures with a resolution of 100 nm(λ/5.5)under white-light microscopy.The focus of the biomagnifier formed a nano-optical trap that allowed precise manipulation of an individual nanoparticle with a radius of 50 nm.This biomagnifier provides a high-precision tool for optical imaging,sensing,and assembly of bionanomaterials. | Yuchao Li Xiaoshuai Liu Baojun Li | 2019 | Light(Science & Applications)2019，8，1： | 9 |
| 18 | TOC changes in the process of thermal evolution of source rock and its controls显示文摘Through geological observation, simulation in laboratory and numerical modeling, the factors that control the changes in total organic content (TOC) of source rock have been studied. When the formula DTOC=(TOC0-TOC)/TOC0 (original organic carbon content in the rock) is used to measure the TOC (total organic carbon content) changes in the source rock through geological time, the degrees and directions of such changes are determined by losses and relative amounts both of organic and inorganic matter in the source rock. The DTOC equa-tion, which is used to calculate the loss rate in the process of maturation for the source rock, is therefore obtained by analyzing the mass balance relations. For a certain type of source rock with a certain maturation history, the changes of its TOC respond only to the rates of hydrocarbon generation and expulsion. In actual cases of geological entities, DTOC generally ranges from -0.05 to 0.2, while the calculated reconversion coefficient (k) for organic carbon content remains between 0.90 and 1.25. Only in an ideal situation where there are extremely high rates of hydrocarbon generation and expulsion can the DTOC value experience significant changes, with k reaching up to 2.5. It is concluded, therefore, that the cri-terion for carbonates source rock assessment, based on reconverting the TOC to the value of its original state, may have overestimated the course of the carbon-reduction, which is likely in many cases to make a poor source rock sound better. | ZHONG Ningning1, LU Shuangfang2, HUANG Zhilong1, ZHANG Yousheng1, XUE Haitao2 & PAN Changchun3 1. The Key Lab of Petroleum Accumulation Mechanism of State Educational Ministry at University of Petroleum, Beijing 102249, China 2. Exploration Geoscience Department of Daqing Petroleum Institute, Daqing 163000, China 3. Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China | 2004 | Science China Earth Sciences2004，47，z2： | 9 |
| 19 | 基于DVS1612准则的焊接结构疲劳评估方法显示文摘详细阐述了应用DVS1612准则进行疲劳评估的方法和如何提取疲劳评估的三种应力.以铁路车辆结构中最常见的T型焊接接头为例,通过有限元计算,并对比手算与商业软件LIMIT的计算结果,最后提出一种准确可行的应用该准则对复杂焊接结构进行疲劳评估的方法. | 胡忠安 张晓艳 程亚军 | 2019 | 大连交通大学学报2019，40，2： | 9 |
| 20 | THE COMPLEXITY OF LIMIT LANGUAGES OF CELLULAR AUTOMATA: AN EXAMPLE显示文摘The limit inguages of cellular automata are defined and their complexity are discussed. New tools, which include skew evolution, skew periodic string, trace string, some algebraic calculation method, and restricted membership problem, are developed through a discussion focusing on the limit language of an elementary cellular automata of rule 94. It is proved that this language is non-regular. | XIE Huimin (Department of Mathematics, Suzhou University, Suzhou 215006, China) | 2001 | Journal of Systems Science & Complexity2001，14，1： | 8 |
您所在的机构暂未开通此部分的功能，请联系管理员