查询词典 critical

This project studies the scale-dependent deformation behavior of the metal matrix composite, the void nucleation and void growth mechanisms at the micron/submicron scale. The main results are:(1) In prophase, growth and coalescence of the void embedded in the graded matrix are analyzed in detailed;(2) Based on the infinite solid model containing a micro-void, coupling effects of the void shape and the void size on the void growth are studied carefully, the results show that it seems to exist a critical equivalent void radius, which is associated with the material length. When radius of a microvoid is close to or smaller than the critical void radius, the micro-void growth rate is essentially eliminated;(3) The coupling effects of the particle shape and size on the mesoscopic stress fields within the particle and matrix are also investigated by introducing the conception of inclusion/matrix interfacial energy. The results show that the stress concentration factors within the particle and on the matrix/particle interface are also strongly size-dependent,so the void nucleation mechanism is size-dependent.(4) By employing a specific orthogonal curve coordinate frame and a 'kernel function' conception, a 'unified method'solving the spheriodal and spherical void problems is suggested; by this unified method, size-dependent plastic potentials of the porous materials containing the spheriodal or spherical voids are obtained, which extend the traditional Gurson model for the spherical void and GLD model for the spheriodal voids to the micron scale.(5) Based on the RVE model containing the spheriodal or spherical particles, the influences of the particle shape and size on the size-dependent mechanical behavior of metal matrix composite are studied.

中文摘要：本项目对金属基复合材料在微细观尺度下的尺度相关变形行为、孔洞形核及长大的机理和模型进行了研究，取得了如下主要结果：1）在前期研究中，探讨了基体的梯度分布对孔洞长大和聚合的影响；2）基于含孔洞的无限大体模型，探讨了孔洞形状和孔洞尺寸对其长大的耦合作用，结果表明：可能存在一个与材料特征长度相关的临界孔洞尺寸，当椭球孔洞的等效半径小于临界孔洞半径时，孔洞的长大受到明显抑制；3）通过引入基体/夹杂界面能的概念，分析了夹杂尺寸、夹杂形状对材料细观应力场的耦合影响，结果表明：颗粒内部和界面上的应力集中因子强烈地依赖于夹杂的尺寸和形状，因此，孔洞的形核机理是尺寸相关的；4）采用一种特殊的正交曲线坐标系和引入"核函数"的概念，"统一"地得到了含椭球和球形孔洞的材料的尺寸相关塑性势，它将传统的Gurson球形孔洞模型和GLD椭球孔洞模型推广到微尺度范围；5）基于含椭球和球形夹杂的体胞模型，初步研究了夹杂形状、夹杂尺寸对金属基复合材料尺寸相关力学行为的影响。

This article studies the conception of safe oxygen content by theoretical and experimental researches, and discusses the simple method to decide minimum oxygen density and critical value of oxygen density by chemical calculation and graphing method, and elementarily analyses the connection between minimum oxygen density and critical value of oxygen density.

理论上分别通过化学计算法和作图法探讨了最小氧浓度和临界氧浓度的简单确定，并初步分析了最小氧浓度与临界氧浓度的关系。

The basic idea was to discrete the structure and find the load function according to the energy criterion of buckling and the principle of random displacement method. As the critical load is the minimum of the load function, a problem of frame buckling can be transformed into an optimization problem. Therefore, the critical load can be found through solving the optimization problem.

先将结构离散为一个有限自由度系统；然后根据有限自由度系统平衡稳定性的能量准则和随机位移法的基本原理，建立符合能量准则的载荷函数，该函数不为零的最小值即为临界载荷，由此将稳定问题转化为无约束的多维优化问题；最后应用遗传算法求出相应于最优解的目标函数值。

The instrument used for this study was Molter's Critical Care Family Needs Inventory. The samples included 50 family members of critical ill patients.

结果显示ICU病人亲属认为能够保证病人的安全，了解病人的治疗与预后，了解病人护理的需要最重要，而与病人亲属身心相关的需求重要性得分则较低。

The results indicate that, in general, the critical temperature of the system becomes lower, compared with the 3D fluids, and is sensitive to the strength of the dipole moment, whereas the critical density shows an insignificant shift.

此外还考察了降低色散作用对系统汽液平衡性质的影响，发现降低色散作用会导致临界点下降，同时分子的偶极矩更加倾向处于分子所在的平面。

Given a mesh, we first solve a Poisson equation to construct a scalar field and use it to generate some critical points. The cutting paths between the critical points and the boundaries are solved in the Poisson scalar field using the deepest descent method. For meshes with nonzero-genus, we construct a Harmonic scalar field, and connect the saddle points with the boundaries based on the Morse theory.

对于给定的任意网格，通过求解泊松方程构造标量场来选取临界点，并采用最速下降法给出临界点到边界或者初始点的切割路径；对于亏格不为零的网格，基于Morse理论，通过构造一个调和标量场来得到鞍点，并将它们连接到边界。

We cosider a class of semilinear elliptic systems with the Neumann boundary value condition by using variational methods, two existences theorem are proved for under critical exponents and critical exponents.

利用变分法讨论了一类带Neumann边界条件的半线性椭圆方程正解的存在性，并得到了在下临界指标时的两个存在性定理。

Considering the average critical gap of pedestrians walking through the vehicle flow and analyzing on large scale of data, it can reach the practical conclusion that the acceptable gap follows the normal distribution function N（4.86,1.72）. In order to make further analysis of the pedestrian delay,capacity and the conflicts with the vehicles,the average critical gaps are evaluated by three different ways.

通过研究行人穿越机动车流的平均临界间隙，对所观测的行人穿越间隙数据进行归纳分析，得出可接受穿越间隙的正态分布函数N（4.86，1.72），并通过三种不同的方法逐一计算出平均临界间隙，可为今后的行人延误时间、通行能力以及与车辆之间的冲突分析研究提供解决方案。

The uniform of nonlinear incremental equation at critical points or non-critical points are deduced, and the relations between incremental solutions and nullspace basis of incremental matrix are put forward. So the incremental solutions can be obtained directly by nullspace basis, and can be expressed nullspace basis of matrix.

推导了非线性增量平衡方程在极值临界点与非临界点解的统一形式，指出增量解与增广矩阵零空间基的关系，从而可直接由零空间基获得增量解，并直接表示为增广矩阵零空间基的形式。

The main works include: 1. successfully observed the opalescence of critical methanol and the phase variation of PET degradation in methanol, studied the internal construction of PET in different stages of degradation, provided the conception of critical region and noncritical region of system in which PET and methanol participated.

主要内容如下： 1 实验观测了甲醇的临界乳光现象及PET在甲醇中降解的相态变化，同时研究了不同降解反应阶段PET内部结构特征，在本实验研究的范围内提出了PET在甲醇中的系统临界区域和非临界区域的概念。

Objective To investigate the effects of interleukin-1 β converting enzyme gene on the biologic characteristics of ovarian cancer cells.

目的 探讨白细胞介素-1 β转换酶的表达，对卵巢癌细胞生物学特性的影响。

Campylobacter: This illness is the most commonly identified cause of diarrheal illness in the world.

弯曲：这种病是最常见的原因查明腹泻病，在世界上。