水平束方法子问题的求解研究

非光滑优化问题是最优化理论与方法中一个重要分支,相应的各种求解方法一直以来都是优化理论研究的重点.首先对解决非光滑优化问题的一种有效方法-束方法,进行了简单阐述,又对其中一种典型方法-水平束方法进行了详细研究.该方法利用水平集作为约束构造产生下一个迭代点的子问题,通过构建子问题的Lagrangian函数以及求解其对偶规划,得出原子问题最优解的显式表达.最后根据子问题的最优性条件和对偶问题得出两个在整体算法的收敛性分析中占有重要地位的结论.     

基于水平集接触算法的任意形态颗粒材料球谐离散元方法

为对自然环境或工业领域中非规则颗粒材料的力学特性进行精确计算,本文采用球谐函数发展了可描述任意几何颗粒形态的球谐离散元方法.考虑球谐单元的凹凸形态及多点接触特性,发展了基于水平集方法的任意形态接触算法,以准确计算单元间的接触方向和重叠量.该算法将不同形态的球谐单元离散为由一系列点组成的零水平集函数和空间离散水平集函数,并将单元间的接触问题转化为两个水平集函数间的求解问题.通过将一系列零水平集点代入邻居单元的空间离散水平集函数中进行三线性插值,可确定两个接触单元间的多接触点及作用力.为检验基于水平集算法的球谐离散元方法的可靠性,对单颗粒与刚性壁面的弹性碰撞、单颗粒自由下落和多颗粒动力堆积过程进行了离散元模拟,研究了颗粒的平动和转动动能随时间的变化规律.计算结果表明,基于水平集算法的球谐离散元方法可准确地计算单元间的接触碰撞作用,并可保证弹性碰撞时颗粒系统的能量守恒及非弹性碰撞时颗粒系统的能量衰减直至动能为零.在此基础之上进一步分析了不同表面凹凸特性对颗粒堆积中体积分数和平均配位数的影响,为任意形态颗粒材料的数值模拟提供了一种有效的离散元方法.     

参数多目标规划αk-较多有效性的稳定性

把Rm空间的αk-较多锥分解成有限个内部非空的尖凸锥之并,用2个集合的差的形式给出了Pareto有效点集和αk-较多有效点集的新的表达式,由此得到了αk-较多有效性与Pareto有效性之间的关系;进而讨论并得到了当目标函数为集值映射时参数多目标最优化问题αk-较多有效点集和有效解集在半连续意义下的稳定性结果.     

一种求有约束总极值的新途径

对有约束的全局最优化问题,通常的做法是用罚函数将有约束总极值问题转化为无约束总极值问题进行解决.该文采用一种新的思路,结合积分-水平集的优点,通过构造一个简单的新函数实现从有约束向无约束的转化,这种方法相比罚函数方法显得更为简洁,文中给出了相应的算法并证明了算法的收敛性.     

一个与Powell搜索相结合的混合免疫进化算法

提出一个求解无约束最优化问题的新的混合算法——Powell搜索法和免疫进化算法的混合算法.该算法不需要计算梯度,容易应用于实际问题中.通过对免疫进化算法的修正,使混合算法具有更加精确和快速的收敛性.利用4个基准测试函数进行仿真计算比较,结果表明新混合算法在解的搜索质量、效率和关于初始点的鲁棒性都远优于免疫进化算法,仿真结果表明了新算法是求解无约束最优化问题的一个高效的算法.     

粒子群算法在求解优化问题中的应用

粒子群优化(PSO:Particle Swarm Optimization)算法是一种新兴的优化技术,其思想来源于人工生命和进化计算理论.PSO算法通过粒子追随自己找到的最好解和整个群体的最好解完成优化.为了避免PSO算法在求解最优化问题时陷入在局部最优及提高PSO算法的收敛速度,提出了对PSO算法增加更新概率.对无约束和有约束最优化问题分别设计了基于PSO算法的不同的求解方法和测试函数,并对PSO算法求解多目标优化问题进行了研究.仿真实验表明了改进的PSO算法求解最优化问题时的有效性.     

确定性退火技术及其在点匹配中的应用

证明了当自由能函数满足一定条件时确定性退火算法收敛到能量函数的全局最优解·在此基础上,利用确定性退火技术给出了一个点匹配算法·该算法首先确定点匹配问题的自由能函数,通过使该自由能函数最小化得到点集之间的映射参数,然后用该参数对两个点集进行校准,最后将校准后的点集进行匹配得出点的对应关系·实验结果说明了该算法的有效性及其对旋转、平移、噪声等的鲁棒性·     

求解k(<10)-中心问题的快速算法

提出求解3-中心问题、4-中心问题、5-中心问题及k(<10)-中心问题的算法.设计该算法的依据是覆盖点集的凸壳必覆盖点集.算法首先判定点集凸壳的形状,然后确定k个圆的排列方式,最后以确定方式计算圆心位置.证明了算法的正确性并且分析了算法的复杂性.     

基于多表观模型的鲁棒跟踪算法

针对传统的均值漂移算法中目标表观模型单一且缺乏必要的更新策略的问题,提出了一种基于多表观模型的多尺度均值漂移跟踪算法.该算法通过对模板集进行稀疏主成分分析获得多个表观模型,并分别在每个模型下以多个尺度并行运行均值漂移算法得到多个收敛点.利用前面求得的多个收敛点求取加权中心,并以此为依据寻找当前时刻的目标状态.实验结果表明,与其他跟踪算法相比,本文提出的算法在应对目标姿态变化、背景干扰及遮挡等复杂情况时具有更好的稳定性和鲁棒性.     

约束条件下一个拓广的梯度投影法

对于约束最优化问题,传统的梯度投影法在每步迭代时均需跟踪活动约束集,这样在实际运算时很容易引起数值上的不稳定。特别对于非线性的约束条件下的梯度投影法,为保证其算法具有全局收敛性,传统的方法都使用了ε-主动约束集的方法,这样,算法在每步迭代开始,都要进行转轴运算,以便确定ε-主动约束集,从而大大增加了每步迭代的计算量。1986年,J.Hevskowits在[1]中首先提出了一个每步迭代时无需跟踪活动约束集的梯度投影类算法,这是一个严格内点法。实际运算表明,[1]中的算法非常稳定。但遗憾的是,此算法所需的假设条件较强(如要求约束域有严格内点集及约束函数是二次连续可微的     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

橡胶颗粒沥青混合料低温抗裂性试验研究

以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.     

Jane Eyre——A Feminist In The 19th Century

In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-