临界的
- 与 临界的 相关的网络例句 [注:此内容来源于网络,仅供参考]
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In chapter five, the results of the experiments are analysed, we draw a conclusion that the thickness of ablator should try to reach the critical thickness.
第五章是实验结果和分析,最终得出了烧蚀层厚度应当尽量达到临界厚度的结论。
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In this thesis, we study the relation between the critical accretion rate and the metallicity via AGB stars approach.
在本文中我们通过AGB星研究了此临界吸积率和金属丰度之间的关系。
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At the same time a new method for calculating activation energy was devised and applied to the new model.
同时还提出一种计算局部临界扩散势能的新方法,并应用于新模型。
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The finite element analysis software ALGOR is used to verify the results.
本文从正交各向异性假设出发,推导了肋骨具有斜度时环加肋圆柱壳总体失稳的临界水压公式,并且用有限元分析软件ALGOR进行了验证。
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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。
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After analysizing the results of SSRFEM and centrifugal model test, someconclusions are drawn that, the depth of slip surface implies that the Bishopssimplied method cannot indicate the true failure mechanism for the slopes reinforcedwith piles. The rate of safety factors decreases with the pile spacing decreasing, andthe salty factor of the slopes is the largest when the reinforced piles are installed in themiddle of the slopes, regardless of pile head confining conditions, and the deflection,maximum bending moment and shear force in the reinforced piles in the criticalcollapse are the biggest meantime. The fixed and hinged head condition of the pilesresults in smaller bending moment in the piles than that in unrotated and free headcondition, therefore the restrained pile head condition is recommended in the design.
3不同特性与工况下抗滑桩与土体相互作用的数值分析与离心模型试验研究表明:采用简化Bishop法计算得到的滑动面不能反映抗滑桩加固边坡的破坏机理,抗滑桩设置在边坡中部和减小桩间距有利于提高边坡稳定安全系数,而此时抗滑桩在边坡临界破坏时的挠度、最大弯矩和最大剪力相对较大;桩头固定、铰接与桩头自由、平移相比,所加固边坡的整体水平位移及边坡临界破坏时抗滑桩的最大弯矩相对较小,而稳定安全系数则较大,因此在进行抗滑桩设计时应尽量选择桩头固定与铰接的型式,或对桩头进行锚固以改善抗滑桩的受力特性,提高边坡的稳定安全性状。
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heological properties at a low shear rate range(10-2-10s-1) and the glass transition temperatures for PEK-C with different moleCular weithts have been studied by using a cone/plate rheometer and DSC' The activation energy for melt flow increases with Mw The dependence of Tg on molecular weight exhibits two linear range and the value of nitersect agrees with the critical molecular weight , Mc' which is first reported for PEK-C' Mc value obtained according to η0 is about 8× 104 g/mol and the relation between Mc and temperature was dis-cussed.
用锥权流变仪及DSC的方法研究了5种不同分子量的酞侧基聚芳醚酮在低剪切速率区(10-2-10s-1)的流变行为及其分子量与玻璃化转变温度的关系。结果表明,样品的粘流活化能随分子量的增加而增大,Tg随分子量的变化是二个线性区,其交点值与所求的样品的临界分子量值相对应。利用测得的零剪切粘度值(η0)首次求得了PEK—C的临界分子量值。同时也讨论了Mc与温度及η0和Tg与分子量的关系。
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Only with such characteristics, the movement equations can be expressed as matrices, and the idea of transforming the movement equations to the simplest form through a nonlinear transformation can be realized;(2) The form of Zi =Yi + YTH2i Y + Y7H3i Y(2)+ Y(2)T H4i Y(2)+ YTH5i Y(3) is adhibited in the nonlinear transformation, so that the multivalued problem caused by the nonlinear transformation is avoided, and the higher order transformation can be taken next;(3) The fourth order nonlinear transformation matrices H21,H31,H41 and H51 are derived, by which the original movement equations of electric power system is transformed to Jodan form in Z space;(4) By use of the fourth order nonlinear transformation, the approximate expression of the stability boundary is obtained, in Z space it is Z1= 0,in Y space it is Y1 + YTH21 Y + YTH31 Y(2)-i- Y(2) TH41 Y(2)+YTH51 Y(3)= 0;(5) The criterion used in this paper to judge whether the system critical unstable is simple and quick;(6) The method used in this paper is a direct method, and no need to construct an energy function.
正是由 于电力系统的运动方程具有这样的特性,才能写成矩阵的形式,通过非线性变换将电力系统的运动方程变换为最简单的线性形式的思想才能得以实现;(2)将通常运用于电力系统暂态稳定性分析的Normal Form变换的形式由 Yi= Zi+ ZTh2riZ变形为 Zi= Yi+YTH2iY+YTH3iY(2)+Y(2)TH4iY(2)+YTH5iY(3),从而使得在对持续故障轨线实施同样的非线性变换以确定临界切除时间时,避免了非线性变换带来的多值性的问题,而只有在没有多值性问题的困扰下,才能采用较高阶的变换:(3)推导出了将原始电力系统系统的运动方程变换到Z空间的约当形式的非线性变换矩阵H21、H31、H41、HS1:(4)在运用四阶了「线性变换的情况下,给出了受扰动后系统的稳定边界的近似的解析表达,在Z空间为Z1=0,在y空间为: Y1+YTH21Y+YTH31Y(2)+Y(2)TH41Y(2)+YTH51Y(3)=0 (5)确定临界失稳的判据简单、快捷:对于一个复杂的电力系统,其稳定边界是相当复杂的一个高维曲面,即便是已知系统稳定边界的解析表达,要求出系统持续故障轨线何时与这一高维曲面相交,在数学上几乎是不可能实现的。
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By employing the Jordan-Wigner transformation and a modified mean field method, we are able to determine its ground-state quantum phase diagram approximately. The chapter IV is the main part of this Thesis. It contains the main innovations in our work. We propose and study in detail a S=1 Ising chain with the interplay of single-ion anisotropy and dimerization. The main results and innovations are the following: We show that the total number of the zero-component of spins at each site is a conserved quantity. This quantity, which may intuitively called as hole's quantum number, is hidden in the system. We show further that the hole's number in the ground-state is zero; By using the Jordan-Wigner transformation, we map this model onto a series of subsystems described by the spin 1/2 dimerized transverse Ising model. We solve the subsystems exactly, by presenting the exact wave functions and spectra;We show that this system exhibits a series of quantum phase transitions by varying the dimerization strength. We determine the quantum critical points exactly. We also show that the criticality is the same as that of the uniform S = 1/2 transverse Ising chain.
第四章是本文的重点及主要创新内容,我们具体研究了自旋为1的在横向单离子晶格场中的一维二聚化Ising链,我们得到的主要结果和创新之处是:(1)证明了这一模型具有一种隐藏的对称性,即自旋第三分量为零的格点数目是一个守恒量,并证明基态出现在空穴数目为零的子空间中;(2)利用Jordan-Wigner 变换将此模型变换到一系列自旋为1/2的横磁场中的二聚化Ising 模型,并给出了相应严格的波函数及能谱;(3)我们发现系统的基态随着二聚化强度的变化将呈现出一系列量子相变,我们得到了量子临界点的精确位置,并证明其临界性质与自旋为1/2的横磁场中的均匀Ising 链中的临界行为属于同一普适类。
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In addition, the blank holding force that is required to avoid wrinkle and rupture during conical part deep drawing is researched. The necessity of reasonable blank holding force in pressing is expounded. From the view of mechanical analysis, the wrinkle critical condition of side-wall is derived for the first time by the stress state of side-wall, the main deformation region on blank. According to the critical condition of plastic instability for flange, side--wall, corner of punch on blank, The blank holding force in conical part deep drawing is divided into four different regions within its forming figure. The basic principle of reasonable blank holding force during stamping is summarized and provided. The mathematical model of reasonable blank holding force that avoids the wrinkle and rupture is established and verified by the finite element numerical simulation and the grid experiment method. The result shows that it is accurate and reliable.
此外,本文还研究了圆锥形件拉深成形过程中,随着拉深变形过程的进行,毛坯为避免产生起皱、破坏缺陷而对压边力的需求情况,阐明了圆锥形件拉深成形过程中压边力合理变化的必要性;由毛坯主要变形区悬空锥壁部分的受力变形情况,从力学分析的角度,首次推导得出了圆锥形零件悬空锥壁起皱失稳的临界条件;并根据主要变形区法兰、悬空锥壁及凸模圆角部分的塑性失稳临界条件,在其成形范围图中,将圆锥形件成形过程中的压边力划分为四个区域;总结并提出了圆锥形件成形过程中压边力合理变化的基本原则;建立了防止起皱、破坏缺陷产生的压边力合理变化的数学模式,并得到了有限元数值模拟及网格实验法的验证,证实了理论分析结果的正确性和可靠性。
- 推荐网络例句
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The split between the two groups can hardly be papered over.
这两个团体间的分歧难以掩饰。
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This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.
这种做法不仅鼓励了更多的反应,而且减少跟风的可能性。
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The new PS20 solar power tower collected sunlight through mirrors known as "heliostats" to produce steam that is converted into electricity by a turbine in Sanlucar la Mayor, Spain, Wednesday.
聚光:照片上是建在西班牙桑路卡拉马尤城的一座新型PS20塔式太阳能电站。被称为&日光反射装置&的镜子将太阳光反射到主塔,然后用聚集的热量产生蒸汽进而通过涡轮机转化为电力