查询词典 given to

Properties of efficient portfolios and the efficient frontier to the model are systematically analyzed. Our main results concerning the properties are: every efficient portfolio can be solved by minimizing portfolio risk under a given level of portfolio return or by maximizing portfolio return under a given level of portfolio risk; on the efficient frontier, the risk is a convex and strictly increasing function of the return and the return is a concave and strictly increasing function of the risk; the utility function on the efficient frontier can be expressed as a quasi-concave function of the risk or the return if the investor's utility function is quasi-concave.

从理论上系统地对该模型下的有效投资组合和有效前沿的性质进行了分析，结果表明：每一个有效投资组合可通过在给定期望收益水平的条件下最小化投资组合风险来获得，或者在给定风险水平的条件下最大化期望投资组合收益来获得；在有效前沿上，风险是收益的严格单调递增凸函数，收益是风险的严格单调递增凹函数；当投资者的效用函数是拟凹函数时，则有效前沿上的效用可表达成风险或收益的拟凹函数。

The optimization methods of database SQL query were studied and some available query optimization Methods were given out as follows: The incompatible data type should avoid to be used; More redundancy search parameters should be given as join condition in join query; In some condition, the number of note hitted to target was estimated by optimizing implement using the average density; Some other maths operating symbol should avoid to be used as condition parameters in WHERE clause; Some operating symbol and its sentence should avoid to be used also; When the cluster function was used,the WHERE clause should be paied attention to more,and so on.

作者单位：（重庆工学院商贸信息学院，重庆 400050）摘要：数据库SQL查询语句的优化，须注意：避免使用不兼容数据类型；连接查询中应多给连接条件提供一些冗余的搜索参数；某种条件下优化器只能使用其平均密度以估计命中的记录数；避免对WHERE子句中条件参数使用其它数学操作符；避免使用某些操作符及相应语句；聚簇函数的使用应注意WHERE子句。

Based on the conditional rough entropy theory, the definition of the conditional rough entropy of set is given and it can measure the uncertainty of set. The properties and the related theorems are given.

基于知识的条件粗糙熵理论，提出了集合的条件粗糙熵概念，用来刻画和度量集合的不确定性。

However, via intensive numerical computation, the author finds that actually some characteristic of this confidence intervals, for example, confidence coefficient, expectation width and coverage efficiency fluctuate intensely when the sample size varies given the parameter, or when the parameter varies given the sample size.

但是我们通过精细的数值计算发现，由于总体分布的离散性，这些置信区间的特性(置信系数、期望长度、覆盖效率)实际表现为当参数固定随着观测次数变化或当观测次数固定随着参数变化而发生强烈震动。

It takesthe weighted average of the L2 norm of the difference of the observation and thesolution of the system and the L2 norm of the difference of conormal derivativeat the different sides of the interface for every subdomain as cost functional andthe smooth coefficients of the subproblem and the value of solution of the originalproblem at interface as identification parameters;Using the property of continu-ous functional defined on compact set,the existence of the optimal solution of theidentification problem is proved;The necessary conditions of optimality charac-terized by the system equation,the adjoit equation and the variational inequalitysimultaneously are given by introducing the conception ofdifferential andadjoit variable;An algorithm is devised and its flow graph is given.

其次，针对分片光滑动力系统的特征，结合正演过程的区域分解算法，建立了分片光滑系统的分解区域参数辨识模型，该模型以子区域上解的实测值与计算值之差的L2范数和界面两侧的通量差的L2范数的加权平均作目标泛函，各子问题的光滑系数及界面上真解的值为待辨识参量；利用紧致集上连续泛函的性质，证明了子区域上参数辨识问题最优辨识参量的存在性；引入微分的概念，借助伴随变量，给出了由系统方程，伴随方程和变分不等式共同表征的最优性必要条件；根据此必要条件设计了算法，给出了算法的程序框图。

Based on the equilibrium equation of an arch element the cubic nonlinear dynamic model with second order is established and the nonlinear differential dynamic system without constant term is obtained through a transfer process of T=U+b. Hence three fixed points and the homoclinic orbits are found. The critical condition of the chaotic vibration of the elastic arch is given by using the method of Melnikov function. The numerical results of the stationary and chaotic motion are given and discussed.

首先利用拱的单元平衡方程建立了拱的二阶三次非线性动力学模型；然后通过变换使方程转化为不含常数项的非线性微分动力系统，并由此得到无扰动系统的3个不动点与同宿轨道；再用Melnikov函数法给出了发生混沌的临界条件；最后给出了该系统出现定常运动和混沌运动的数值结果。

A class of uncertainty T-S dynamical fuzzy systems is given using the Lyapunov function method.The non-fragile controller design of continuous uncertain dynamical fuzzy system is given.

首先给出不确定T-S动态模糊系统的模型；然后利用Lyapunov函数方法，研究连续不确定动态模糊系统的非脆弱控制器设计，得到基于LMI的不确定动态模糊系统的全局渐近稳定性条件。

The properties of the new method are that (1) the equations that the quartic Bézier curve has to satisfy for being C 2 continuous are strictly row diagonally dominant;(2) the discontinuous points of the curve are at the given data points;(3) the curve is locally adjustable;(4) if the given data points are convex, the constructed quartic Bézier curve is convex.

用样条函数方法构造插值样条曲线曲面，曲线曲面的精度和形状是由给定的数据点和端点条件唯一确定的。在有些情况下，例如，对文献 [7～ 9]中的数据点集，由样条函数方法构造的C2 插值曲线是不可接受的，但由于没有额外自由度，无法调整曲线的形状。

Generously and copiously given.He was given 20 for expenses, but pocketed most of it.

他得到20英镑的公款，但大部分都进了自己的口袋了。

The cross product is given by solving the matrix given by fig.

跨产品给予解决的无花果给予矩阵。

Diabetes is a social disease that affects several million people worldwide.

糖尿病是一个社会性疾病，全世界有数百万人罹患此病。

I'll call you on Friday to see if we can reschedule our luncheon meeting at your convenience.

我星期五会给您打电话在您方便的时候我们重新安排我们的午餐约会。