查询词典 existence conditions

We study the existence of one solution and two solutions of problem(0.0.8)under sign conditions and sublinear growth conditions.

在允许非线性项无界，但是次线性增长的前提下，该章获得了符号条件下问题(0.0.4)的一个解和多个解的存在性。

The ventilation and air-conditions system of building supplies comfortable environment for work and life, however, because of the existence of sediment in ventilation tubes, the air-conditions system can become an importance approach of fire spread and diffusion in buildings.

建筑物的通风空调系统给人们的工作和生活创造了舒适的环境条件，但由于空调系统的管道中聚积物的存在，空调系统将成为火灾在建筑物内蔓延传播的重要途径。

The following exciting results are revealed: 1 When considering the influence of some nonlinear elements such as hard-limit of exciters, the effects of some devices such as Power System Stabilizer and Static Var Compensator which can introduce positive damping in power system, the reasonability of system parameter values in simulation, the SNB surface and HB surface on the boundary of SSSR will turn close to each other and even coalesce together; 2 Under some conditions, coupling between slow exciters and shunt capacitors will bring negative damping in power system dynamics, which increases the possibility of oscillatory instability. So the power system with mass shunt compensators is easily subjected to the oscillatory instability. In recent years, chaotic phenomena of power system have been reported many times. Some simulation studies even found chaos existing inside the power system SSSR. In this dissertation, chaotic phenomena in power systems are thoroughly studied in order to make clear the relation of chaos and SSSR. The following results are derived: 1 Based on Li-Yorke Theorem and their definition on the chaos, the existence of chaos in power system is verified; 2 Three possible routes of causing chaos in power system are found and deeply investigated. They are route of cascading period doubling, route of directly initial energizing and route of torus bifurcation (or quasi-periodicity). The latter two routes are investigated for the first time in power system stability studies; 3 When the stability conditions of chaos are broken, it is found they can lead to voltage collapse, angle divergence, or voltage collapse with angle divergence simultaneously.

针对在电力系统小扰动稳定区域内可能存在混沌吸引域的有关报道，本文深入研究了电力系统混沌现象的出现途径和与系统失稳模式之间的关系：1利用Li-Yorke定理和Li-Yorke的混沌定义，从理论上证明了电力系统混沌现象的存在性；2发现了电力系统中导致混沌出现的三种可能途径：倍周期分岔导致混沌、初始能量直接激发混沌和经由环面分岔导致混沌，并对后两种新发现的途径进行了较为细致的研究；3发现了混沌极限环破裂导致电压崩溃、角度失稳以及电压崩溃和角度失稳同时出现的现象，其中混沌极限环破裂导致系统角度失稳和电压崩溃及角度失稳同时出现的现象均属首次报道；4证明由微分-代数方程描述的系统模型，其小扰动稳定域的边界只包含HB、SNB和SIB三种分岔界面，在SSSR的内部和边界上，均不可能存在会导致混沌的点，从而将混沌现象排除在小扰动稳定域的研究之外，简化了后者的研究工作。

Based on the upper and lower solutions method,under suitable conditions,existence of solution of a three-point boundary value problem forthird-order ordinary differential equation with nonlinear mixed boundary conditions is obtained.

基于上下解方法，在一定条件下，得到了一类带有非线性混合边界条件的三阶常微分方程的非线性三点边值问题解的存在性，作为上述存在性结果的应用，在推论中给出了一类三阶非线性微分方程三点边值问题解的存在性。

In this paper, We study the spectral counting function for one dimensional p-Laplace operator. We prove the existence of a two term Weyl-type asymptotic with mixed and periodic boundary-value conditions. This is the generalization of Laplace operator with mixed and periodic boundary-value conditions.

本文研究一维p-Laplace算子谱点的计数函数，在混合边值及周期边值条件下得到一个精确到第二项的Weyl型渐近式，它是Laplace算子在这两种边值条件下的推广。

Paper studies the practical stability of electricity market models by tools, for example, the appropriate structure Lyapunov functions, Cauchy matrix, the matrix measure, constant variation. Judging practical stability sufficient conditions and estimating formula of ultimate convergence boundary are provided. Conditions are descriptive by coefficients of models. At the same time, paper studies the Lyapunov stability of the electricity market. As well as the sufficient conditions of judging electricity market Lyapunov stability are provided. Some of conclusions improved the results of Alvarado and others. The conclusion of Lyapunov stability has made a comparative with practical results.

首次将实用稳定性理论和方法应用于电力市场稳定性的研究中，借助于构造合适的Lyapunov函数、柯西矩阵、矩阵测度、常数变易法等工具，系统研究了所建电力市场模型的实用稳定性，得到了用模型的系数来描述其实用稳定性的一系列判定条件和最终收敛边界的估计公式；同时对电力市场的Lyapunov稳定性进行了研究，得到了电力市场稳定性的若干判据，部分结论改进了Alvarado等人的结果；随后将Lyapunov稳定的结果与实用稳定进行了比较。

Spectral element methods for partial differencial equation is introduced in this study from viewpoint of the collocation approximation of Chebyshev polynomial. Wave Equation and its space discretization are deduced. Two time integral methods, central difference method and implicit Newmark method, are introduced, and their stability and applicability are also discussed in some details. The significance of absorbing boundary conditions in spectral element methods for Aeroacoustics is explained, and Clayton-Engquist-Majda absorbing boundary conditions is emphasized and introduced, then the discrete scheme of this boundary conditions is deduced and applied to spectral element methods for wave equation.

本文从Chebyshev多项式逼近理论出发，详细介绍了谱元方法求解偏微分方程的过程；推导了流体中的声波动方程并在空间上对其进行了谱元离散；详细讨论了两种时间积分方法──中心差分法和Newmark方法，分析了它们的稳定性条件，并从理论上对比了两种方法的优缺点和适用范围；将吸收边界条件推广应用于谱元方法求解气动声学问题中，重点介绍了Clayton-Engquist-Majda吸收边界条件的原理和公式，推导了该吸收边界条件的变分形式，并将其引入波动方程的离散形式中。

Pragmatically, If-conditionals in English can be used to indirectly express such speech acts as promises, threats, requests, suggestions, etc.; the antecedents can be genuine conditions or non-genuine conditions, and can also express hypothetical and concessive meanings. When they express non-genuine conditions, they are in fact on a higher speech act level than the consequents.

英语中的"if"条件句在语用上还可以间接地表示承诺，威胁，请求，建议等言语行为；其前件既可以是真正条件，也可以是非真正条件，还可以表达假设，让步等意义；从语用学的角度分析，当"if"条件句的前件表达非真正条件时，它与后件处于不同的言语行为层次上。

Suppose C is a Graph with k loops andf: G 梸- G is a continuous map with at least a peri- odic point. We prove the following three conditions are equivalent:(1) f is equicontinuous;(2) One of the following End + 2k + 1 conditions holds: in FJm.~0(E~+2L!= flJ1,m = l,2,挃,End J=1 + 2k; 1 0 = flf is a ioop on Gandf I~:0?- 0 is conjugate j=1 to a rational rotation;(3) One of the following End + 2k + 1 conditions holds: k m Lfl.m/~oE~(G+2i!~ is uniformly convergent, m = 1,2,,End+2k; n There is a poistive integer number n,~~~ is uniformly convergent.

假设G是含有k个圈的图，f是G到自身上的连续映射，并且至少有一个周期点，我们证明了下列三条陈述是等价的：（1）f是等度连续的；（2）下列End+2k+1个条件之一成立： m）F l）O=是G的一个圈，且fl_o：O→O共轭于一个有理旋转；（3）下列End+2k+1个条件之一成立： m）是一致收敛的，m=1，2，…，End+2k； l）存在某个正整数n，是一致收敛的。

The thesis can be divided into five parts as follows: First, the structural characteristics of finned-pipe evaporator are analyzed. After selecting suitable microelement controller, the heat-transfer and mass-transfer processes are analyzed for every microelement under the conditions of dryness, wetness and frostiness. Based on previous equations, some parameters of frostiness are confirmed and the frost-growing model is set up under frost condition. Some hypotheses are postulated and with the help of the equation of mass-conservation, energy-conservation and momentum-conservation, the evaporation model which fits in the dynamic simulation is built, which set a solid foundation for system simulation. Second, the starting and stopping behaviors under disturbed condition are analyzed and calculated by using the dynamic concentrative parameter model, which gives some advice to better prescribe refrigeration system and set theoretic foundation for carrying out automatic control of refrigeration system. Third, the normal running process is analyzed and calculated by means of rational matching theory, which gives some advice on how to better understand the parameter change under steady state and the affection of inlet-parameter on evaporator. Fourth, the simulation software with dynamic characteristic is designed, which can be applied to calculate thernio-parameter of cryogen, air humidity and frost thickness under different initial and boundary conditions, and to carry out dynamic simulation under conditions of dryness, wetness and frostiness, at the same time, to achieve detection and simulation at any stage from starting to stopping.

本文的主要内容如下：1对翅片管蒸发器结构特点进行分析，选取适当的微元控制体，就干、湿和霜工况下对每个微元分别进行传热传质分析，基于经验关系式确定霜的有关参数，对于霜工况下的霜生长建立模型，经适当假设，运用质量守恒、能量守恒和动量守恒方程建立适合动态仿真的蒸发器数学模型，为系统仿真奠定基础； 2对蒸发在大扰动下的开、停机过程，运用动态集中参数模型进行分析和计算，为更好地描述制冷系统运行的全过程奠定基础，同时也为制冷系统实现自动控制提供一定的理论基础； 3对蒸发器正常运行过程，运用动态分布参数和参数间定量耦合的观点来分析和计算，为更好地了解稳态工况下各点参数的变化情况及各入口参数对蒸发器动态特性的影响即蒸发器性能对各参数变化的敏感性； 4编写翅片管蒸发器动态特性仿真计算程序，可以计算不同边界条件和初始条件下的制冷剂热力参数、空气温湿度和霜厚度分布场，实现对翅片管蒸发器在干、湿和霜工况下的动态仿真。

In the days of sailing vessels the crew were afraid they would be becalmed on the ocean.

在使用帆船的时代，船员们担心他们会因为无风而无法在海洋上航行。

As long as foreign donors pay the PA's salary bill, few expect a new intifada.

只要外国继续为巴权力机构的薪水买单，希望发动新暴动的人便寥寥无几。