查询词典 difficult problem

Firstly, urban space's development course and actuality of space's patterns are reviewed contrastly in the paper abroad and home. Then, existing problems of urban space at present in our country are discussed stressly:"Ten Faulty Expressions in Writing" of urban construction;"the Movement of Beautifying City" in china; the problem of urban characteristic; the problem of reforming of old city; the problem of residential segregation. The above problems' formed reasons and countermeasures are put forward. Then, the example of Xi'an and its existing problems of urban space and several countermeasures are analyzed in the paper. The transformation of three sections realized in the planning thought of urban space is put forward: from "elitism" to "plebeianism"; from mega-urban project design to "daily living space" and from "technology first" to "human-oriented".

论文首先从中西方城市空间形态的演变历程入手，对比分析了国内外的空间形态现状，重点论述了当前我国存在的城市空间问题：城市建设"十大败笔"；中国"城市美化"运动；城市特色问题；旧城改造问题以及空间分异问题，分析了其形成原因并得出了解决途径，然后对西安进行了实例分析，总结出其城市空间存在问题并提出几点对策，接下来提出了城市空间规划理念应实现的三个方向的转变：从"精英主义"向"平民主义"理念转变、从大尺度城市设计向"日常生活空间"营造转变以及从"技术至上"向"以人为本"理念转变。

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。

The event-tree based modeling and optimization algorithms are adopted and the whole problem is divided into two sub problems (the portside sub problem and the refinery sub problem).Thus, the algorithm is proposed by analyzing the solving sequence of the two sub problems.

该方法把原油混输调度问题分解为码头调度子问题和厂区调度子问题，采用基于事件树的建模方法，并根据两个子问题的求解顺序提出了原油混输调度问题的分布式并行算法。

Arrival of information age require people learn study of independence, on the basis of to is it is it set up on a complicated one , meaningful problem among the situation learning to mean to learn independently issue, is it on positive angle of person who solves problem , is it is it reflect student true world situation bad to construct the question to face to go directly to put, through solving the complicated practical problem , train students' question to ask the tactics of solving , develop the basic discipline knowledge foundation and basic skill at the same time .

信息时代的到来要求人们学会自主性的学习，基于问题的学习是自主学习的一种，它是把学习设置于复杂的、有意义的问题情境中，将学生置于积极的问题解决者的角度，直接去面对反映真实世界情境的劣构问题，通过解决复杂的实际问题，培养学生的问题求解策略，同时发展基本的学科知识基础和基本技能。

In this paper we discuss the applications of weighted graph from three aspects including the shortest path problem,Chinese postmen problem,and match problem .

本文选取了赋权图应用的三个方面进行讨论，分别是最短路问题、中国邮递员问题和匹配问题的应用。

The primal problem is split into two parts: a master problem and several subproblems. With the information communication between these two parts, we can finally get the optimal solution of the primal problem.

利用Kuhn-Tuck条件，我们把原问题分解为一个高级问题和若干个相互独立的低级子问题，通过高级问题和低级子问题之间的信息传递，最终可以得到原问题的最优解。

Then the global optimal solution of the primal programming problem can be obtained by solving the converted D.C.programming problem or concave minimization problem via using the existing algorithms.

再利用已有的关于D.C。规划和凹极小的算法，可以求得原问题的全局最优解。

Based on stratification theory, begin with the barotropic primitive equation, some theoretical problems of atmospheric equations are discussed, including the well posedness of their initial value problem, boundary value problem and mixed problem.

摘要从正压原始方程开始，运用分层理论研究大气环流方程组定解问题的适定性，以及适定的定解问题(包括初值问题、边值问题和混合问题)在解析函数类空间准确解的求解方法。

Until recently, the convergence of the Rosen"s arithmetic has been proved. The projection gradient method is the generalization of Steepest decent method to constraint problem. So it does have a faster convergence speed that the fastest decent method . To solve the problem, many researchers have generalizat the well-developed optimization with unconstraint to the Rosen"s gradient method. The conjugate gradient method is one of success to solve the problem.

投影梯度法是最速下降法对约束问题的推广，因此没有较快的收敛速度，为了解决这个问题很多中外学者把发展得比较成熟的无约束最优化算法作类似的推广，其中共轭梯度方法是近年发展的很成熟的方法，它具有计算简单，算法结构好，计算量少，具有良好的收敛性等优点，而Rosen投影梯度法的提出使寻找下降方向变得简单。

The main aim of this thesis is to study some boundary value problems for complex Monge-Ampere equations ,which contain the semilinear oblique boundary problem,infinite boundary value problem and Dirichlet boundary problem in some special domain that is not strictly pseudoconvex.

近20年来，对于复Monge-Ampere方程的研究已经取得了丰硕的成果。

Pachomius manual labour was organized as an essential part of the monastic life; and since it is a principle of the monks as distinguished from the mendicants, that the body shall be self-supporting, external work of one sort or another has been an inevitable part of the life ever since.

根据圣pachomius体力劳动组织作为一个重要组成部分寺院生活；以来，这是一个原则的和尚，作为有别于乞丐，该机构应自支撑，对外工作的这种或那种已一个必然的一部分，生活至今。

In order to study the effects of parametrical rolling on the ship movement and tilts, in allusion to ship's navigating in regular following waves, the equation of ship rolling motion is transformed into normal Mathieu equation by proper variable replacement when strong parametrical excitation in restoring moment varied according to sine or cosine wave.

为研究参数横摇对船舶运动和倾覆的影响，通过对船在规则波上随浪航行时，恢复力矩中出现的1个以正余弦规律变化的强参数激励项进行适当的变量置换，将船舶的横摇运动方程转换成标准形式的Mathieu方程。