Liquid metal embrittlement mechanism

Liquid metal embrittlement was studied in the following two aspects. First the first principle and ChenNanxian three-dimensional lattice reverse method were employed to obtain the effective potentials for Al-Ga and GaGa. Then with the molecular dynamics simulation, the influence of liquid metal adsorption on dislocation emission was studied. The simulated result shows that after Ga atoms are adsorbed on the crack plane in Al crystal, the critical stress intensity factor decreases, which changes from 0.5 MPam~(1/2) (without adsorption) to 0.4 MPam~(1/2) (with adsorption). The reason for the reduction in the critical intensity stress factor is that Ga adsorption reduces the surface energy of the crack plane. Moreover, 7075 Al alloy adsorbing liquid metal (Hg 3atm％Ga) was in-situ studied in TEM by using a special constant deflection device. The experimental result showed that liquid metal adsorption could facilitate emission, multiplication and motion of dislocations. When this process reached a critical     

光子系统有序结构的研究

光子简并度是描述光子系统基本特性及动力学行为的重要物理量，应用光子简并度描述光子系统的有序结构是光子系统研究的重要课题．以热力学和量子统计理论为基础，推导出光子简并度的统计表达式，得出了光子简并度的统计意义，揭示了光子简并度的微观本质，即光子简并度是光子群有序程度的量度，激光系统的有序结构导致了激光系统的高光子简并度．进一步研究表明，处在混沌状态的激光系统中的不同模式处于竞争更激烈、协同作用更强的“等权耦合”状态，在宏观上表现出高强度、大涨落的特性．     

订单处理过程的响应性分析

订单处理过程越来越被视为企业达到和维持竞争力的关键业务过程，设计具有优越响应性的订单处理过程的价值已经得到肯定，但响应性的概念和内涵却没有明确界定．研究讨论了订单处理过程响应性的内涵，建立了订单处理过程的响应性分析模型，提出了以过程流向为导向和以目标为导向的订单处理过程干扰因素识别方法，从影响范围、持续时间、发生频率和对目标的影响等方面对干扰影响程度进行分析评价的方法、订单处理过程响应能力分析评价的方法以及企业应对的策略．     

关于经济订购量模型中有关成本的正确定界与计算

分析了经济订购量模型中用平均成本法确定订购成本和存贮成本存在的问题,对订购成本和存贮成本的成本参数进行了正确界定,并提出了合理的计算方法———边际成本法．     

关于任意层状介质中运动裂纹问题的研究

本文讨论了裂纹在任意层状介质中快速扩展的平面直变问题。应用积分变换方法建立了问题的控制积分方程。采用路径积分技术给出了层状介质平面弹性动力学问题的时间—空间域基本解,以封闭形式给出了层状介质中运动裂纹问题的第二类奇异积分方程组。得到了快速扩展裂纹的动态应力强度因子。     

抛物问题各向异性非协调元的收敛分析

讨论了各向异性非协调矩形元对二阶抛物方程的逼近,利用该单元的特殊性质及新的技巧,在各向异性网格下得到了与传统有限元方法完全相同的最优的误差估计。     

Study on undercooling of metal droplet in rapid solidification

In 1950, Turnbull et al.[1] dispersed 18 kinds of metals including Cu, Ni, etc. into droplets with diameters of 10-100 μm and obtained a large undercooling of 0.18 TL. Volkmann et al.[2] have successfully obtained the undercooling of 0.3 TL in the Co-Pd alloy by means of the molten glass purified technique. As yet, the maximum undercool-ing in liquid metals is acquired by Perepezko et al.[3], who makes the Ga with a diameter of 20 μm reach an undercooling of about 0.58 TL by use of the …     

一类二阶微分方程解的有界性与渐近性

利用微分不等式技巧讨论了二阶微分方程 (a(t)x′)′ +f(t,x ,x′) =0的解的有界性与渐近性 ,给出了几个重要定理 ,所得结果包含和推广了前人的一些结果 .其中a(t)为定义于R+ =[0 ,+∞ ) 上的正值函数 ,且∫∞01a(t) dt<∞ ,f(t,x ,y)是定义于R+ ×R×R 上的连续函数 .     

英语突降格及其语序意义的再现

突降法是英汉两种语言都十分常见的修辞格。它的最大特点是句子的前后语序不可颠倒。突降辞格的翻译不能套用一般的语序翻译原则。否则,辞格修辞效果就不可能再现出来。     

Chemical short-range order domain in bulk amorphous alloy and the prediction of glass forming ability

Since the discovery of bulk Zr-Ti-Cu-Ni-Be[1] and Pd-Ni-Cu-P[2] metallic glasses with ex-traordinary high glass forming (GFA) ability and critical cooling rate lower than 100 K/s, great attention has been paid to the structure of BMG alloys. Experimental results of X-ray and neutron diffraction or scattering have provided ample evidence that there is a short-range order in BMG alloys. Metallic glasses always exhibit strong compound forming tendency and the corresponding anomalies of t…     

Tween-80/n-C8H17OH/H2O体系层状液晶的有序性及层状结构研究

用偏振光显微镜法和核磁共振氢谱法(^2H-NMR)确定了Tween-80／n-C8H170H／H2O体系25℃时层状液晶的区域，用自旋标记电子自旋共振法(ESR)测定了层状液晶分子排列的有序参数。研究表明：有序参数随着Tween-80含量的增加而增加，随着层状液晶中水含量的增加而减少。并用小角度X射线衍射方法测定了层状液晶的层间距离，其层间距离小于4nm。     

次序统计量的分布及其在均匀分布中的应用

讨论最大和最小次序统计量的分布以及它们在均匀分布中的应用,并讨论基于均匀分布U(θ,θ+1)中的参数估计及优效性,得出ξ₍₁₎,ξ_(n)-1是θ的均方相合估计和强相合估计的结论.     

金属纤维材料的吸声特性

本文用驻波管法测试了多种规格的碳钢、黄铜、铝纤维等吸声材料的垂直入射吸声系数,频率范围为100～4000Hz;分析讨论了材料的流阻率、厚度、容量、孔隙率、纤维直径及背后空气层对其吸声性能的影响;并对模压金属纤维材料的结构因子作了探讨。     

Two-echelon inventory model with service level constraint and controllable lead time sensitive to order quantity

The decision-making and optimization of two-echelon inventory coordination were analyzed with service level constraint and controllable lead time sensitive to order quantity. First, the basic model of this problem was established and based on relevant analysis, the original model could be transformed by minimax method. Then, the optimal order quantity and production quantity influenced by service level constraint were analyzed and the boundary of optimal order quantity and production quantity was given. According to this boundary, the effective method and tactics were put forward to solve the transformed model. In case analysis, the optimal expected total cost of two-echelon inventory can be obtained and it was analyzed how service level constraint and safety factor influence the optimal expected total cost of two-echelon inventory. The results show that the optimal expected total cost of two-echelon inventory is constrained by the higher constraint between service level constraint and safety factor.     

规划中的功能秩序与自然生态环境

以湖北京山县第一中学规划设计为例 ,探讨在设计中利用自然环境的优势解决人工环境机械的非人性化问题 ,阐明了以人为本追求秩序与自然同一和谐的生态观念及可持续发展的规划理念     

三级非线性变时滞差分方程振动准则

研究了一类三阶非线性变时滞差分方程解的振动性，给出了类方程所有有界解振动和方程振动的几个充分条件。     

素数2在广义Lucas数中的次数

设a是正奇数．对于非负整数n,设Ln（a）=a^n＋β″,其中a=（1／2）（a＋、√a^2＋4）,β=（1／2）（a-√a^2＋4）．本文运用Pell方程的性质讨论2在Ln（a）中的次数ord2Ln（a）,证明了当n≠0（mod3）n≡0（rood6）,或者,n≡3（mod6）时,ord2Ln（a）分别等于0,1或者2．     

最小二乘自适应滤波旋转机械阶比跟踪研究

为克服等角度重采样的计算阶比跟踪方法不能在时域提取阶比的不足，提出了直接在时域进行自适应滤波的阶比跟踪方法.通过研究周期性负载机械系统振动信号的特点，构造了包括状态方程和观测方程的振动信号模型.状态方程表示了阶比幅值的平滑变化，观测方程表示了测量误差和噪声.通过构造加权最小二乘自适应滤波器，实现了各阶比成分在时域中提取.并根据滤波矩阵的特殊性，采用共轭梯度法求解滤波方程.实验结果表明，该方法能够在时域中准确地提取幅值和频率变化的阶比，适合于旋转机械振动响应特征提取.     

Electronic structures and physical properties of pure aluminum metal

By one-atom theory, the electronic structure of pure Al metal with f.c.c, structure has been determined to be [Ne](3s_c)~(1.8790)(3p_c)~(0.4982)(3s_f 3p_f)~(0.6228). According to this electronic structure, the potential curve, lattice constant, cohesive energy, elastisity, and the temperature dependence of the linear thermal expansion coefficients have been calculated. The electronic structures and characteristic properties of Al metals with b. c. c., h.c.p. structures and liquid have been studied. It is argued that the pure Al metal with f. c.c. structure can exist naturally, but with b. c. c.and h. c.p. structures cannot.##属性不符     

Order parameters of liquid crystal on the rubbing surfaces of alignment layers

Liquid crystal (LC) alignment is most important in LC devices. In this paper, we quantitatively analyze the LC scalar order parameters on the rubbed surface of an alignment layer. Careful measurement of dichroic infrared absorbance is performed. The result gives the evidence that the order parameter of LC just on the rubbed alignment film is only 1/3-1/2 that in the LC bulk.