再论运输问题的多重最优解

在对运输问题研究成果综述的基础之上,归纳出了多重最优解、有限多重最优解、无限多重最优解、狭义多重最优解以及广义多重最优解等概念.讨论了运输问题多重最优解的进一步分类及判定问题,得到了有限多重最优解和无限多重最优解的判定定理.指正了有关文献中关于多重最优解个数下限的计算公式,给出了有限多狭义多重最优解个数下限的计算公式.最后,举例验证了结论的正确性.     

一类两参数奇异摄动拟线性微分方程组的边值问题渐近解

为了研究一类含三个因变量的两参数奇异摄动拟线性微分方程组边值问题的渐近解,首先在一定的条件下构造了问题的包含外层解、中间层解与内部层解的幂级数形式合成解;然后利用原问题的退化形式先求出外部解;再利用不同的伸长变量,依据中间层与内部层特有的性质,分别计算出该边值问题的中间层解和内部层解,从而得到原问题渐近解.     

双曲型时滞偏微分方程解振动的充要条件

讨论了一类多滞量双曲型时滞偏微分方程解的振动性质，获得了其一切解振动的充要条件；所得充要条件将时滞偏微分方程解的振动判别问题转化为时滞微分方程解的振动判别问题；揭示了与普通双曲型偏微分方程解的质的差异。     

一类双变量Riccati矩阵方程组对称解的迭代算法

基于求线性矩阵方程组约束解的修正共轭梯度法,讨论了由Nash均衡对策导出的一类双矩阵变量Riccati矩阵方程组(R-MEs)对称解的数值计算问题.提出用牛顿算法将R-MEs的对称解问题转化为双矩阵变量线性矩阵方程组的对称解或者对称最小二乘解问题,并采用修正共轭梯度法解决后一计算问题,建立了求R-MEs对称解的新型迭代算法.新型迭代算法仅要求R-MEs有对称解,不要求它的对称解唯一,也不对它的系数矩阵做附加限定.数值算例表明,新型迭代算法是有效的.     

子矩阵约束下矩阵方程ATXA=B的实矩阵解及其最佳逼近

本文讨论了子矩阵约束下一类矩阵方程的实矩阵解问题。基于矩阵的奇异值分解和广义奇异值分解方法,给出了该问题有解的充要条件和解的一般表达式。并证明了对任一给定的实矩阵,在上述解集合中必存在唯一的最佳逼近解,给出了最佳逼近解的形式。     

自反矩阵和反自反矩阵反问题的最小二乘解

研究了自反矩阵和反自反矩阵反问题的最小二乘解及最佳逼近,给出了最小二乘解和最佳逼近解,并得到丁反问题有解的充要条件及解的表达式。     

双中心矩阵反问题及其在电网络理论中的应用

本文研究双中心矩阵反问题。建立了双中心矩阵反问题的最小二乘解,得到了解的具体表达式。讨论了用双中心矩阵反问题的解构造给定矩阵的最佳逼近问题,给出该问题有解的充分必要条件和解的表达式。设计了相应的算法并给出了其在电网络理论中的应用。     

各向异性板平面应力问题的一般解析解

根据各向异性矩形板平面应力问题的基本方程精确地求得了位移函数的一般解.一般解包括三角函数和双曲线函数组成的解,还有代数多项式解.前者能满足四个边为任意边界条件问题;后者能满足四个角为任意边界条件等问题.这些边界条件用以决定一般解中的积分常数.因此一般解可用以求解任意边界条件下的平面应力问题.以四边为均匀分布和非均匀分布位移的对称角铺设复合材料板为例进行了计算和分析     

广义二阶不变凸向量变分类不等式

研究了广义二阶不变凸向量变分类不等式问题解的存在性，并讨论其与多目标优化问题解之间的关系。引入了两种广义二阶不变凸函数和一种广义二阶单调函数，并给出具体实例说明了它们的存在性。在广义二阶不变凸性假设下，利用分析的方法给出了向量变分类不等式与多目标优化问题解之间的关系。利用KKM定理，在广义二阶单调性假设下得到了向量变分类不等式问题解的存在性定理。研究表明在广义二阶单调性假设下，向量变分类不等式存在解，并且在适当的广义二阶凸性条件下，其解与多目标优化问题解之间相互等价。     

各向异性材料平面问题基本解析解的特征方程解法

该文提出了一种利用特征方程解法构造基本解析解的新方法,并将其应用到各向异性材料平面问题,成功构造了完备且独立的系列基本解析解.构造各向异性材料平面问题控制微分方程的算子矩阵,通过其行列式计算可得到问题特征通解所需满足的特征方程,将所求得特征通解代入到微分方程算子矩阵所对应的伴随矩阵,可推导得出各向异性材料平面问题的基本解析解.根据基本解析解独立性的论证,可得到系列独立且完备各向异性材料平面问题基本解析解.利用特征方程解法求解基本解析解思路简单、并且容易找到独立且完备的解析解,其结果可以成为相关数值计算方法的基础.     

Strength, Durability, and Safety of Engineering Systems

The evolution of approaches to the solution of machine dynamics and strength problems on the basis of determining static and dynamic nominal and local stresses of the operating load is discussed. It is shown how the material strength and plasticity characteristics, the cyclic strength characteristics in the high-cycle and low-cycle fatigue regions, the high-temperature long-term strength and creep characteristics, and the linear and nonlinear characteristics of fracture mechanics were sequentially used as the basic criterial parameters of the deformability and strength of structural materials. Particular emphasis was given to the results of studies on machine safety and catastrophe mechanics. Integrated approaches to the solution of strength and safety problems of potentially dangerous facilities (nuclear power stations, spacecraft complexes, aircraft, chemical plants, etc.) by analysis of all stages of their life cycle, including design, manufacture, testing, and operation, are discussed.     

再论标准和标准化的基本概念

本文是作者再次对标准和标准化的概念进行讨论。首先讨论的是标准化的目的、主体和对象。作者认为标准化的目的是控制、有序化和统一化;标准化的主体是人/机构;标准化对象可以是具体的或抽象的事物,也可以是它们的组合;任何事物都可以抽象地表达为实体(entity)。第二,作者讨论了标准和标准化的本质以及它们的作用;认为从内容角度看,标准是匹配问题解决方案,也是为标准化对象规定需要满足的要求;从实施角度看,标准是规则;标准化则是制定、实施、传播标准的过程;标准的作用是能够创建并组织现实世界,并能够为相关方建立互相交流和共同理解的基础;标准化的作用是对创新方案进行选择和简化,阻止现实世界过度无序化发展,形成复杂化和简化之间的平衡。第三,作者讨论了标准的记录形式、自愿/强制属性和时空范围,认为标准的记录形式有文件、样品、图形符号、物理表达等多种形式;标准具有选择的自愿性和实施的强制性;标准在时空范围内是有限的。文章的结尾给出了理解标准化概念的框架。     

鼓式制动器制动不稳定时变特性分析

由于工作环境复杂多变,制动器工作不稳定而导致振动和噪声,鼓式制动器制动时的温度变化对制动不稳定性影响较大,研究制动不稳定性影响因素及其制动不稳定时变特性具有实际工程意义。基于鼓式制动器四自由度接触模型,分别在Hypermesh和ABAQUS中建立鼓式制动器制动鼓和制动蹄总成模型与摩擦制动接触模型并进行试验验证;通过热机耦合动态分析,研究制动鼓温度对制动应力的影响;分析弹性模量和热膨胀系数对鼓式制动器制动不稳定时变特性的影响。分析表明：制动不稳定性是摩擦力耦合所致;制动过程中制动鼓温度与应力相互作用且均先快速上升后缓慢下降;鼓式制动器制动不稳定时变特性主要体现在不稳定模态个数及不稳定倾向系数（tendency of instability, TOI）值的变化,制动温度变化导致弹性模量变化,引起不稳定模态个数和TOI值略有变化,弹性模量对鼓式制动器制动不稳定时变特性影响较小;制动温度变化导致热膨胀系数变化,引起不稳定模态个数和TOI值先大幅降低后略有升高,热膨胀系数对鼓式制动器制动不稳定时变特性影响较大。研究结果对改善汽车制动声品质具有一定指导意义。     

Numerical Analysis of Powder Properties in Low Power Plasma Torch

A mathematical model was presented to describe the particle trajectory, velocity and temperature properties in the low power plasma spraying torch (3.6 kW)in which powder particles were directly injected into the region between the cathode and anode. The results show that the characteristics of the particles by low power plasma spraying are similar to that by traditional APS( Atmosphere plasma spraying) in 40 kW. The velocities of the particles increase with the increase of inlet gas flow rate, current and percentage of nitrogen and hydrogen, while the temperature of the powder increase with the decrease of the gas flow rate and with the increase of current and percentage of nitrogen and hydrogen.     

Micromechanical modeling for behavior of silty sand with influence of fine content

The numerical simulation program of PFC2D (Particle Flow Code in 2 Dimension) particle flow based on the flow-solid coupling principle and, on its built-in FISHTANK function library and FISH language, defines the flow equation and pressure equation of fluid domain respectively, and carries out numerical simulation calculations on the diffusion process and, on the morphology and particle displacement of slurry during the slurry injection process. By adjusting the parameters of hist, n_bond, s_bond and measure in the PFC command flow, the tracking of granular body displacement changes is achieved, and the mesoscopic mechanism such as the diffusion law of soil slurry at different depths and the change of formation porosity is revealed. The numerical calculations show that: the grouting pressure has a significant effect on the alteration and destruction of the formation structure, and the fracturing effect becomes gradually worse with increasing adhesive strength, while the porosity increases significantly with increasing grouting pressure. Based on the elastic-plastic theory of the Mohr-Colomb criterion to theoretically derive the stress field of the soil around the borehole, it is pointed out that the mechanical mechanism of annular tension and radial compression is the fundamental reason for the appearance of fracturing grouting action mode. The increase of slurry viscosity is beneficial to improve the grouting effect of fracturing-compacting grouting, while the increase of friction coefficient has little effect on the grouting effect. The comparative analysis of the laboratory tests shows that the PFC2D simulation of the grouting process is feasible.     

基于贝叶斯-GO综合法的快递配送系统可靠性研究

提出用贝叶斯-GO综合方法分析快递配送系统可靠性。首先综合考虑配送系统对时间、品质、服务可靠性的要求,详细分析配送工作流程及其影响因素,建立GO图;然后根据映射规则转换为贝叶斯网络,最后通过案例分析,利用贝叶斯网络正反向推理和敏感度分析,得到系统的薄弱环节及其主要影响因素。研究结果表明：贝叶斯-GO综合法克服了单独使用GO法逻辑运算复杂繁琐的缺点,能够快速找到快递配送系统的薄弱环节及其主要影响因素,其中收件子系统故障率最高,快递员的配送不及时、寄件损坏、丢失是主要影响因素。     

文字符号在视觉传达设计中的双重构建

目的分析文字在视觉传达设计中形意构建的双重性问题。方法以文字设计应用为线索,通过设计实践的符号学分析,从语义与形式两个层面进行文字内在属性、结构与功能的探讨。结论文字在视觉信息构建与媒体传播中具有语言和图形表达的双重身份,这是由文字语言符号形式与语义的双重属性决定的,同时也是语言性文字透过图形化视觉表现的必然结果。这决定了文字在视觉信息传播中形意相生的基本结构,并呈现出语言的文字与艺术的图像之间的共生关系。它既可以是传播本体的语言表述方式,也担负着喻体象征的视觉艺术功能,极大地拓展了视觉传达设计的创造空间与可能。     

Untersuchung von Schmelz‐ und Rekristallisationsprozessen sowie Riss‐, Oxid‐ und Porenbildung beim Schweißen

Investigation of melting and re‐crystallization processes and of crack, oxide and pore formation during welding In the paper some known investigation methods of the primary re‐crystallization and of the structure of the crystallization front are discussed. All these methods have disadvantages, in some cases they cause a limited validity or are expensive. The presented new method is based on the micrographic recording of the melting and solidifying metal surfaces. The method overcomes the above‐mentioned disadvantages. It is able to investigate in the welding seams not only the primary re‐crystallization processes but also the secondary ones including the formation of cracks and pores and the appearance of non‐metallic inclusions like oxides. The facilities of the method are demonstrated on some examples of use.     

江澳两地高校文创设计的协同研究与商业实践

目的 探索江门世遗文化的传承、发展和转化的新思路,践行国家在《粤港澳大湾区发展规划》纲要中要求江门承担与港澳地区文化创意合作与开发任务的分工。方法 与澳门高校紧密合作,开展专业培训课程,以开平碉楼为例,从人文视角开展设计研究,梳理开平碉楼的文化脉络,把世遗文化的元素和其背后的文化融入文创产品中,提升文创产品的附加值,推动当地文创产业结构的变革。结果 两地高校构建了稳定的科研团队,开设长期有效的设计培训课程,与景区建立了研究协作关系,帮助景区构建了一套产销研的商业模式。结论 以跨区域高校合作为平台,以文创产品为抓手,依托江澳两地的资源优势,可以构建江门世遗文化全新的品牌形象,最终推动开平世遗文化的活化。     

Damage production, accumulation and materials performance in radiation environment

Collisions of energetic projectile particles with host atoms produce atomic displacements in the target materials. Subsequently, some of these displacements are transformed into lattice defects and survive in the form of single defects and defect clusters. Depending on the ambient temperature, these defects and their clusters diffuse, interact, annihilate, segregate and accumulate in various forms and are responsible for the evolution of the irradiation-induced microstructure. Naturally, both physical and mechanical properties and thereby the performance and lifetime of target materials are likely to be determined by the nature and the magnitude of the accumulated defects and their spatial dispositions. A multitude of processes covering a variety of temporal and spatial scales contribute to the evolution of the global microstructure. Results of computer simulations as well as theoretical modelling describing some of these processes will be reviewed and discussed. The framework within which the influence of irradiation on void swelling, radiation hardening and loss of ductility can be treated will be discussed. It will be emphasized that the nature of displacement damage production plays an important role in the evolution of the global microstructure. Finally, a brief summary of the current status in the fields of computer simulations and theoretical modelling is presented in the form of concluding remarks. This revised version was published online in July 2006 with corrections to the Cover Date.