查询词典 boundary condition

Based on varying process of generator terminal parameters after excitation fault, shortages of excitation protective principle of static stability boundary and asynchronous impedance boundary are analyzed. It proposed that excitation fault research relates to large-disturbance stability. Because dynamic power-angle character of generator after excitation fault is non-sinusoidal, there are differences between dynamic power-angle character and static state power-angle character. So it isn't ideal to protective operation result based on small-disturbance stability and static stability boundary criterion. At the same time, it proposed that asynchronous boundary impedance criterion is a constant reactive power circle moving adown j Xd′. It can ensure complete loss-of-excitation generator measuring impedance enter into the circle, but can't ensure the other condition measuring impedance including impossible losing synchronism enter. So loss-of-excitation protection would be maloperation when system voltage drops short and recovers or generator rejects load.③Based on stability principle, it puts forward setting conditions and calculation method of generator loss-of-excitation protection by direct measuring power-angle.

以励磁故障后发电机端的相关参数的变化为基础，通过对以静稳定边界和异步阻抗边界作判据的两类三种现行励磁保护在原理上存在的缺陷分析，发现：励磁故障是一个大干扰稳定性问题，励磁故障后的发电机的动态功角特性与静态功角特性有很大的差异，已远非正弦曲线，因此基于小干扰稳定性原理、以静稳定边界作判据的保护必然动作不理想；异步边界阻抗判据是一个下移j Xd′的等无功阻抗圆，它可以保证完全失磁后的发电机测量阻抗能进入该阻抗圆，但不能保证完全失磁之外的其它状态不会进入该阻抗圆，因此在系统电压短时下降或发电机突然甩负荷等情况下可能启动该保护使之误动。

In order to decrease the reflection of wave on the boundary, spongy condition was used on top boundary.

为了减少波在边界上的反射，顶部边界采用了海绵边界条件。

The results show that proper RRA heat treatment can improve SCC properties with retention of the high strength of T6 level. After preaging at 100℃for 24 h, retrogression at 200℃for 7 min, and reaging at 100℃for 24 h, the ultimate tensile strength, yield strength and elongation of the alloy are 795 MPa, 767 MPa and 9.1%, respectively. Meanwhile the failure time of the alloy applied to tensile strength of 210MPa in 3.0%NaCl+0.5%H2O2corrosion condition is longer than 720 h. The corresponding TEM observation shows that after retrogression for 7 min and re-aging treatment, the microstructure of grain boundary is similar to that treated in the T73 condition with coarsen and isolated distribution, and the microstructure inside grain is similar to that treated in the T6 condition with small and homogeneous distribution.

研究结果表明：在峰值时效T6状态下合金强度高，但抗应力腐蚀性能差；采用合适的RRA热处理工艺既能使合金保持T6状态下的高强度的同时，又能显著改善合金的抗应力腐蚀性能；经回归7 min RRA处理后合金的晶界类似T73态析出相聚集粗化，而晶内类似T6态析出相细小弥散分布，在拉伸应力为210 MPa和3.0%NaCl+0.5%H2O2腐蚀液中，其断裂时间大于720 h，相应的抗拉强度、屈服强度和延伸率分别为795 MPa， 767 MPa和9.1%，显示优越的综合性能。

The results show that proper RRA heat treatment can improve SCC properties with retention of the high strength of T6 level. After pre-aging at 100 ℃ for 24 h, retrogression at 200 ℃ for 7 min, and reaging at 100 ℃ for 24 h, the ultimate tensile strength, yield strength and elongation of the alloy are 795 MPa, 767 MPa and 9.1%, respectively. Meanwhile the failure time of the alloy applied to tensile strength of 210 MPa in 3.0%NaCl+0.5%H2O2 corrosion condition is longer than 720 h. The corresponding TEM observation shows that after retrogression for 7 min and re-aging treatment, the microstructure of grain boundary is similar to that treated in the T73 condition with coarsen and isolated distribution, and the microstructure inside grain is similar to that treated in the T6 condition with small and homogeneous distribution.

研究结果表明：在峰值时效T6状态下合金强度高，但抗应力腐蚀性能差；采用合适的RRA热处理工艺既能使合金保持T6状态下的高强度的同时，又能显著改善合金的抗应力腐蚀性能；经回归7 min RRA处理后合金的晶界类似T73态析出相聚集粗化，而晶内类似T6态析出相细小弥散分布，在拉伸应力为210 MPa和3.0%NaCl+0.5%H2O2腐蚀液中，其断裂时间大于720 h，相应的抗拉强度、屈服强度和延伸率分别为795 MPa， 767 MPa和9.1%，显示优越的综合性能。

The results show that proper RRA heat treatment can improve SCC properties with retention of the high strength of T6 level. After pre-aging at 100℃ for 24 h, retrogression at 200℃ for 7 min, and reaging at 100℃ for 24 h, the ultimate tensile strength, yield strength and elongation of the alloy are 795 MPa, 767 MPa and 9.1%, respectively. Meanwhile the failure time of the alloy applied to tensile strength of 210 MPa in 3.0%NaCl+0.5% H2O2 corrosion condition is longer than 720 h. The corresponding TEM observation shows that after retrogression for 7 min and re-aging treatment, the micro- structure of grain boundary is similar to that treated in the T73 condition with coarsen and isolated distribution, and the microstructure inside grain is similar to that treated in the T6 condition with small and homogeneous distribution.

研究结果表明：在峰值时效T6状态下合金强度高，但抗应力腐蚀性能差；采用合适的RRA热处理工艺既能使合金保持T6状态下的高强度的同时，又能显著改善合金的抗应力腐蚀性能；经回归7min RRA处理后合金的晶界类似T73态析出相聚集粗化，而晶内类似T6态析出相细小弥散分布，在拉伸应力为210 MPa和3.0%NaCl+0.5%H2O2腐蚀液中，其断裂时间大于720h，相应的抗拉强度、屈服强度和延伸率分别为795 MPa，767 MPa和9.1%，显示优越的综合性能。

The difference schema of the initial boundary value problem was converted to the step-by-step form,which was similar to the difference schema of the initial value problem.It is concluded that the difference schema satisfying the Von Neumann condition is a stable schema,and that,under the consistency condition,such stable schema is convergent.Moreover,with error estimate expression for the difference approximation to the classical solution,the linearity condition is unnecessary.

引入反投影算子将发展方程初边值问题的差分格式转化为与初值问题差分格式类似的逐步推进的形式，从而得出：满足Von Neumann条件的差分格式是稳定的格式；在相容条件下，差分格式若稳定(或满足VonNeumann条件)则格式收敛，且对古典解的差分逼近有误差估计式，不再需要线性的条件。

Based on Pontryagin maximum principle, the lunar soft landing problem is transformed into a two-point boundary value problem in mathematics. In consideration of the bound condition and transversality condition, the resulted two-point boundary value problem is converted into a parameter optimization problem aiming at the initial values of conjugate variables and the terminal time, then it is solved by the nonlinear programming.

首先，从庞德里亚金极大值原理出发，将有限推力作用下月球软着陆问题转化为数学上的两点边值问题；在考虑边界条件及横截条件的前提下，将该两点边值问题转化为针对共轭变量初值和末时刻的优化问题；然后应用非线性规划方法求解所形成的参数优化问题。

In Chapter two, it is given of the three-dimensional boundary element and the boundary element space, Sobolev space for the contact boundary element problem with friction; it is proved of existence and uniqueness of the solution by variation inequality for the contact Boundary Element Method matrix equation under two kinds of condition that the contact zone is fixed and the contact zone is increasing along with the load; it is given of the expressionfor the error of the exact solution and the boundary element solution.

第2章，给出三维边界单元及边界元空间、有摩擦接触边界元问题的Sobolev空间，利用变分不等式证明了不变接触区和随载荷可变接触区两种情况下的接触边界元法矩阵方程解的存在唯一性，给出了准确解与边界元解的误差表达式，还证明了三维弹塑性摩擦接触问题凝缩矩阵解的存在唯一性，为三维弹塑性摩擦接触边界元法奠定数学基础。

It is proved by using the function approximation theory and martrix theory that for a degenerate elliptic equation of the first class, if the third boundary value condition is satisfied at its nondegenerate boundary and the given derivative values are satisfied at its degenerate boundary, then its solution is existent and unique.

摘 要 运用逼近理论及矩阵理论证明：如果一类退化椭圆型方程在非退化边界上满足第三边界条件，在退化边界上满足给定微商值，那么它的解是存在且唯一的。

In this project, we study the theory of higher order differential equations in Banach spaces and related topics. We solve an open problem put forward by two American Mathematicians and two Italian Mathematicians concerning wave equations with generalized Weztzell boundary conditions, introduce an existence family of operators from a Banach space $Y$ to $X$ for the Cauchy problem for higher order differential equations in a Banach space $X$, establish a sufficient and necessary condition ensuring $ACP_n$ possesses an exponentially bounded existence family, as well as some basic results in a quite general setting about the existence and continuous dependence on initial data of the solutions of $ACP_n$ and $IACP_n$. We set up quite a few multiplicative and additive perturbation theorems for existence families governing a wide class of higher order differential equations, regularized cosine operator families, regularized semigroups, and solution operators of Volterra integral equations, obtain classical and strict solutions having optimal regularity for the inhomogeneous nonautonomous heat equations with generalized Wentzell boundary conditions, gain novel existence and uniqueness theorems,which extend essentially the existing results, for mild and classical solutions of nonlocal Cauchy problems for semilinear evolution equations, present a new theorem with regard to the boundary feedback stabilization of a hybrid system composed of a viscoelastic thin plate with one part of its edge clamped and the rest-free part attached to a visocelastic rigid body. Also we obtain many other research results.

在本研究中，我们对Banach空间中的高阶算子微分方程的理论以及相关理论进行了深入研究，解决了由美国和意大利的四位数学家联合提出的一个关于广义Wentzell边界条件下的波动方程适定性的公开问题，恰当地定义了Banach空间中的高阶算子微分方程Cauchy问题的算子存在族及唯一族，建立了齐次和非齐次高阶算子微分方程Cauchy问题适定性的判别定理，获得了关于高阶退化算子微分方程的算子存在族、正则余弦算子族、正则算子半群、Volterra积分方程解算子族的乘积扰动和混合扰动定理，得到了关于以依赖于时间的二阶微分算子为系数的一大类非自治热方程非齐次情形下的时变广义Wentzell动力边值问题的古典解、严格解的最大正则性结果，获得了半线性发展方程非局部Cauchy问题广义解和经典解存在唯一的判别条件，从实质上推广了现有的相关结果；得到了一部分边缘固定而另一部分附在一粘弹性刚体上的薄板构成的混合粘弹性系统的边界反馈稳定化的新稳定化定理，还建立了一系列其他研究结果。

Neither the killing of Mr Zarqawi nor any breakthrough on the political front will stop the insurgency and the fratricidal murders in their tracks.

在对危险的南部地区访问时，他斥责什叶派民兵领导人对中央集权的挑衅行为。

In fact,I've got him on the satellite mobile right now.

实际上 我们已接通卫星可视电话了