最下的

In most of the cases, producing and purify the enriched fissionable materials are the most difficult and the most expensive parts with in the nuclear weapon production program.

在大多数情况下，生产裂变材料丰富、纯洁最困难和最昂贵的零件生产核武。

Firstly, applying spectral factorization to minimize an integral square performance criterion containing tracking error and control energy, an optimal control law for the nominal model is derived on condition of control energy constraint. Then, for model uncertainty, using spectral factorization to minimize the variance of the actual system performance from the nominal performance over all frequency range, a robust controller design method is abtained, which has optimal robustness of the system nominal performance to model errors.

首先针对控制对象的标称模型应用谱分解最小化一个包含跟踪误差和控制能量在内的积分平方性能指标，导出一个控制能量约束条件下的最优控制律；然后再针对模型不确定性应用谱分解最小化实际系统性能和标称性能在整个频段上的方差，得到一个鲁棒控制器的设计方法，可使系统的标称性能对模型误差具有最优的鲁棒性。

In the conclusion, I argue that the maximin rule is the best rational strategy in the situation of the choice under uncertainty, and I also hold that the maximin rule indeed leads us to Rawls's difference principle, and to accept the difference principle as the principle of distributive justice regulating the basic structure of society.

在结论上我支持最小值极大化规则作为在不确定抉择环境下的最理性策略，并且我认为依循最小值极大化规则，我们将会选择罗尔斯的差异原则作为应用於社会基本结构上的正义原则。

Since these values are obtained according to the maximum likelihood principle, the initial phases can be located near the optimal solution values.

该初值是最大似然准则下的估计结果，可以使初始相位位于最优解附近。

In addition to the zerofederal income tax and negative fiscal gap, I find the taxation competition and service competition in different levels of governments largely influence the optimal governmental and individual choices.

首先，在Gong 和Zou（2002）的基础上，文章采用标准的财政分权框架，引入不完全人口流动和内生劳动供给选择，分析多级政府体制下的最优政府支出、最优税收和最优转移支付政策。

According to the principle of gear modification, this paper presented a new method, which determines the modification of spur gear using the dynamic system identification and optimum control theory.

摘 要：提出了一种利用动态系统辨识与最优控制理论相结合确定齿轮修形量的方法：在实际工况下，通过实验采集直齿轮传动系统实际动态信号进行系统辨识，然后求取系统的最优控制，将其转换为振动最小的修形量。

The multicast routing problem that finding the minimum cost multicast routing tree with many QoS constraints may be formalized to Steiner tree problem in network, which is a NP-complete problem that an algorithm that finds a Steiner tree can not get the best solution in polynomial time.

寻找有多个QoS约束的最小代价组播路由树可以形式化为网络中的Steiner树问题，它是一个NP完全问题，在多项式时间内不能得到最优解，因此研究者所寻求的是一种次优的、在最差情况和平均情况下的性能都接近于最优的解决方案。

Chapter four studies the chaotic responses in a system consisting of simple pendulum and harmonic oscillator under bounded noise excitation. Firstly, the Melnikov function of the two-degree-of-freedom system under Hamiltonian perturbation is derived. The essential condition of the autonomous system for the probable onset of chaos is obtained, the Poincare maps of the system under small Hamiltonian perturbation and the effect of increasing perturbation on the Poincare maps are studies. Then for the non-autonomous system under damping and harmonic or bounded noise excitation, the largest Lyapunov exponent and Poincare maps are calculated. From the analysis of the largest Lyapunov exponent, the critical criterion for the onset of chaos, and the conclusion that the threshold of bounded noise amplitude for the onset of chaos in the system increases as the intensity parameter of Wiener process increases are obtained. The result from the analysis of Poincare maps is in agreement with that obtained from the Largest Lyapunov exponent. The effect of varying damping coefficient and intensity parameter of Wiener process is also analyzed.

第四章研究了有界噪声激励下的两自由度单摆—谐振子系统的混沌运动，首先推导了该两自由度系统仅在Hamilton扰动下的Melnikov函数，得到该自治系统可能产生混沌的必要条件；研究了该系统在小的Hamilton扰动和增大摄动情形下的Poincare截面；然后对有阻尼、谐和或有界噪声激励下的非自治系统数值计算了其最大Lyapunov指数和Poincare截面；从Lyapunov指数分析得到了这个两自由度系统产生混沌运动的临界条件及产生混沌的临界激励幅值随Wiener过程强度参数值的增大而增大的结论，Poincare截面分析的结果亦符合Lyapunov指数分析的结论；研究了Wiener过程强度参数、阻尼系数变化对Poincare截面的影响。

In this paper, the line blocking situation, the exchange of optimal power flow analysis of the circuit system, each node under congestion pricing, as well as trends such as changes in the slip road was completed in the Matlab environment to the IEEE14 bus system route blockage occurs in case of simulation and data analysis and achieved good results.

本文针对线路的阻塞情况，用交流最优潮流分析了线路阻塞情况下系统各节点电价以及支路潮流等变化，完成了在Matlab环境下对IEEE14节点系统发生线路阻塞情况下的仿真和数据分析，取得了较好的效果。

This is not to suggest that we should constantly slurp soda to keep our brains functioning optimally.

但这并不是提议我们经常大声喝苏打水来保持大脑处在最理想，营养最充足的状态下。

I didn't watch TV last night, because it .

昨晚我没有看电视，因为电视机坏了。

Since this year, in a lot of villages of Beijing, TV of elevator liquid crystal was removed.

今年以来，在北京的很多小区里，电梯液晶电视被撤了下来。