LARGE－TIME BEHMIOR OF SOLUTIONS FOR THE SYSTEM OF COMPRESSIBLE ADIABATIC FLOW THROUGHPOROUS MEDIA

ＬＡＲＧＥ－ＴＩＭＥＢＥＨＭＩＯＲＯＦＳＯＬＵＴＩＯＮＳＦＯＲＴＨＥＳＹＳＴＥＭＯＦＣＯＭＰＲＥＳＳＩＢＬＥＡＤＩＡＢＡＴＩＣＦＬＯＷＴＨＲＯＵＧＨＰＯＲＯＵＳＭＥＤＩＡ￥ＸＩＡＯＬＩＮＧ（Ｌ．ＨＳＩＡＯ）Ｄ．ＳＥＲＲＥ（ＩｎｓｔｉｔｕｔｅｏｆＭａｔ...     

MIXED BOUNDARY VALUE PROBLEM FOR SECOND－ORDER SYSTEM OF DIFFERENTIAL EQUATIONS OF THE ELLIPTIC TYPE

（陈庆祥）ＭＩＸＥＤＢＯＵＮＤＡＲＹＶＡＬＵＥＰＲＯＢＬＥＭＦＯＲＳＥＣＯＮＤ－ＯＲＤＥＲＳＹＳＴＥＭＯＦＤＩＦＦＥＲＥＮＴＩＡＬＥＱＵＡＴＩＯＮＳＯＦＴＨＥＥＬＬＩＰＴＩＣＴＹＰＥ￥ＣｈｅｎＱｉｎｇｘｉａｎｇ（Ｄｅｐｔ．ｏｆＭａｔｈ．，Ｚｈｏｎｇｓ...     

SOME RESULTS RELATED TO THE SEPARABLE QUOTIENT PROBLEM

ＳＯＭＥＲＥＳＵＬＴＳＲＥＬＡＴＥＤＴＯＴＨＥＳＥＰＡＲＡＢＬＥＱＵＯＴＩＥＮＴＰＲＯＢＬＥＭ￥（钟怀杰）ＺｈｏｎｇＨｕａｉｊｉｅ（Ｄｅｐｔ．ｏｆＭａｔｈ．，ＦｕｊｉａｎＮｏｒｍａｌＵｎｉｖｅｒｓｉｔｙ，Ｆｕｚｈｏｕ３５０００７，Ｃｈｉｎａ．）Ａｂｓ...     

CAUCHY PROBLEM FOR SEMILINEAR HYPERBOLIC EQUATION OF HIGHER ORDER WITH DISCONTINUOUS INITIAL DATA

ＣＡＵＣＨＹＰＲＯＢＬＥＭＦＯＲＳＥＭＩＬＩＮＥＡＲＨＹＰＥＲＢＯＬＩＣＥＱＵＡＴＩＯＮＯＦＨＩＧＨＥＲＯＲＤＥＲＷＩＴＨＤＩＳＣＯＮＴＩＮＵＯＵＳＩＮＩＴＩＡＬ　ＤＡＴＡＣｈｅｎＳｈｕｘｉｎｇ（陈恕行）（Ｉｎｓｔ．ｏｆＭａｔｈ．，ＦｕｄａｎＵｎｉｖ...     

SYMMETRIES， BāCKLUND TRANSFORMATIONS AND BOUNDARY－INITIAL VALUE PROBLEMS FOR NONLINEAR CHROMATOGRAPH

ＳＹＭＭＥＴＲＩＥＳ，Ｂ■ＣＫＬＵＮＤＴＲＡＮＳＦＯＲＭＡＴＩＯＮＳＡＮＤＢＯＵＮＤＡＲＹ－ＩＮＩＴＩＡＬＶＡＬＵＥＰＲＯＢＬＥＭＳＦＯＲＮＯＮＬＩＮＥＡＲＣＨＲＯＭＡＴＯＧＲＡＰＨＹＥＱＵＡＴＩＯＮＷａｎｇＭｉｎｇｌｉａｎｇ（王明亮）（Ｄｅｐｔ．ｏ...     

WORD PROBLEMS AND THE CENTERS OF ABEL DIFFERENTIAL EQUATIONS

ＷＯＲＤ　ＰＲＯＢＬＥＭＳ　ＡＮＤ　ＴＨＥ　ＣＥＮＴＥＲＳ　ＯＦ　ＡＢＥＬ　ＤＩＦＦＥＲＥＮＴＩＡＬ　ＥＱＵＡＴＩＯＮＳＷＯＲＤＰＲＯＢＬＥＭＳＡＮＤＴＨＥＣＥＮＴＥＲＳＯＦＡＢＥＬＤＩＦＦＥＲＥＮＴＩＡＬＥＱＵＡＴＩＯＮＳ￥Ｍ．Ａ．Ｍ．Ａｌｗａｓｈ...     

FREE BOUNDARY PROBLEM ARISING FROM EVAPORATION FROM POROUS MEDIUM

ＦＲＥＥＢＯＵＮＤＡＲＹＰＲＯＢＬＥＭＡＲＩＳＩＮＧＦＲＯＭＥＶＡＰＯＲＡＴＩＯＮＦＲＯＭＰＯＲＯＵＳＭＥＤＩＵＭＹＡＮＧＬＩＰＩＮＧ（杨力平）（ＤｅｐａｒｔｍｅｎｔｏｆＡｐｐｌｉｅｄＭａｔｈｅｍａｔｉｃｓ，ＴｓｉｎｇｈｕａＵｎｉｖｅｒｓｉｔｙ，Ｂｅ...     

EXISTENCE AND UNIQUENESS OF GLOBAL SOLUTION FOR CERTAIN NONLINEAR DEGENERATE PARABOLIC SYSTEMS

ＥＸＩＳＴＥＮＣＥＡＮＤＵＮＩＱＵＥＮＥＳＳＯＦＧＬＯＢＡＬＳＯＬＵＴＩＯＮＦＯＲＣＥＲＴＡＩＮＮＯＮＬＩＮＥＡＲＤＥＧＥＮＥＲＡＴＥＰＡＲＡＢＯＬＩＣ　ＳＹＳＴＥＭＳＬＵＧＵＯＦＵ（卢国富）（ＤｅｐａｒｔｍｅｎｔｏｆＭａｔｈｅｍａｔｉｃｓ，Ｐｕｔｉ...     

A CLASS OF SECOND ORDER NEUTRAL DIFFERENTIAL INEQUALITIES WITH DISTRIBUTED TYPE DEVIATING ARGUMENTS

ＡＣＬＡＳＳＯＦＳＥＣＯＮＤＯＲＤＥＲＮＥＵＴＲＡＬＤＩＦＦＥＲＥＮＴＩＡＬＩＮＥＱＵＡＬＩＴＩＥＳＷＩＴＨＤＩＳＴＲＩＢＵＴＥＤＴＹＰＥＤＥＶＩＡＴＩＮＧＡＲＧＵＭＥＮＴＳ（傅希林）￥ＦｕＸｉｌｉｎ（Ｄｅｐｔ．ｏｆＭａｔｈ．，ＳｈａｎｄｏｎｇＮｏｒ...     

THERMODYNAMIQUE DES ENSEMBLES DE CANTOR AUTOSIMILAIRES（THERMODYNAMICS OF SELF-SIMILAR CANTOR SETS）

ＴＨＥＲＭＯＤＹＮＡＭＩＱＵＥＤＥＳＥＮＳＥＭＢＬＥＳＤＥＣＡＮＴＯＲＡＵＴＯＳＩＭＩＬＡＩＲＥＳ（ＴＨＥＲＭＯＤＹＮＡＭＩＣＳＯＦＳＥＬＦ－ＳＩＭＩＬＡＲＣＡＮＴＯＲＳＥＴＳ）￥Ｇ．ＭＩＣＨＯＮ;Ｊ．ＰＥＹＲＩＥＲＥ（ＵｎｉｖｅｒｓｉｔｙｄｅＢｏｕ...     

The Optimal Control of a Train

We consider the problem of determining an optimal driving strategy in a train control problem with a generalised equation of motion. We assume that the journey must be completed within a given time and seek a strategy that minimises fuel consumption. On the one hand we consider the case where continuous control can be used and on the other hand we consider the case where only discrete control is available. We pay particular attention to a unified development of the two cases. For the continuous control problem we use the Pontryagin principle to find necessary conditions on an optimal strategy and show that these conditions yield key equations that determine the optimal switching points. In the discrete control problem, which is the typical situation with diesel-electric locomotives, we show that for each fixed control sequence the cost of fuel can be minimised by finding the optimal switching times. The corresponding strategies are called strategies of optimal type and in this case we use the Kuhn–Tucker equations to find key equations that determine the optimal switching times. We note that the strategies of optimal type can be used to approximate as closely as we please the optimal strategy obtained using continuous control and we present two new derivations of the key equations. We illustrate our general remarks by reference to a typical train control problem.     

具有点态控制约束热方程的时间与范数最优控制问题的等价性

本文研究了具有点态控制热方程的等价性问题.利用变分法分析时间最优控制的唯一性,能控性以及范数最优控制的特征,获得了具有点态控制约束热方程的时间与范数最优控制问题之间的等价性,推广了现有文献的结果.     

从树型集上最优停止问题到一般偏序集上最优停止问题

本文讨论了树型集上与偏序集上最优停止问题两者间的关系，证明了最优策略与最优控制变量的一一对应关系，从而导出最优策略．可在最优控制变量中取到．     

OPTIMAL HARVESTING AND SPATIAL PATTERNS IN A SEMIARID VEGETATION SYSTEM

We consider an infinite time horizon spatially distributed optimal harvesting problem for a vegetation and soil water reaction diffusion system, with rainfall as the main external parameter. By Pontryagin's maximum principle, we derive the associated four‐component canonical system (CS), and numerically analyze this and hence the optimal control problem in two steps. First, we numerically compute a rather rich bifurcation structure of flat (spatially homogeneous) canonical steady states and patterned canonical steady states (FCSS and PCSS, respectively), in 1D and 2D. Then, we compute time‐dependent solutions of the CS that connect to some FCSS or PCSS. The method is efficient in dealing with nonunique canonical steady states, and thus also with multiple local maxima of the objective function. It turns out that over wide parameter regimes the FCSS, i.e., spatially uniform harvesting, are not optimal. Instead, controlling the system to a PCSS yields a higher profit. Moreover, compared to (a simple model of) private optimization, the social control gives a higher yield, and vegetation survives for much lower rainfall. In addition, the computation of the optimal (social) control gives an optimal tax to incorporate into the private optimization.     

An inverse optimal problem in discrete-time stochastic control

In this paper, we study an inverse optimal problem in discrete-time stochastic control. We give necessary and sufficient conditions for a solution to a system of stochastic difference equations to be the solution of a certain optimal control problem. Our results extend to the stochastic case the work of Dechert. In particular, we present a stochastic version of an important principle in welfare economics.     

Solutions for a class of optimal control problems with time delay,part 1

The optimal control of a system whose state is governed by a nonlinear autonomous Volterra integrodifferential equation with unbounded time interval is considered. Specifically, it is assumed that the delay occurs only in the state variable. We are concerned with the existence of an overtaking optimal trajectory over an infinite horizon. The existence result that we obtain extends the result of Carlson (Ref. 1) to a situation where the trajectories are not necessary bounded. Also, we study the structure of approximate solutions for the problem on a finite interval.The author thanks A. Leizarowitz for fruitful discussions.     

A penalty function method for solving inverse optimal value problem

In order to consider the inverse optimal value problem under more general conditions, we transform the inverse optimal value problem into a corresponding nonlinear bilevel programming problem equivalently. Using the Kuhn–Tucker optimality condition of the lower level problem, we transform the nonlinear bilevel programming into a normal nonlinear programming. The complementary and slackness condition of the lower level problem is appended to the upper level objective with a penalty. Then we give via an exact penalty method an existence theorem of solutions and propose an algorithm for the inverse optimal value problem, also analysis the convergence of the proposed algorithm. The numerical result shows that the algorithm can solve a wider class of inverse optimal value problem.     

Existence and explicit determination of optimal stopping times

We consider large classes of continuous time optimal stopping problems for which we establish the existence and form of the optimal stopping times. These optimal times are then used to find approximate optimal solutions for a class of discrete time problems.     

关于运输问题最优解的进一步讨论

首先给出了运输问题最优解的相关概念,将最优解扩展到广义范畴,提出狭义多重最优解和广义多重最优解的概念及其区别.然后给出了惟一最优解、多重最优解、广义有限多重最优解、广义无限多重最优解的判定定理及其证明过程.最后推导出了狭义有限多重最优解个数下限和广义有限多重最优解个数上限的计算公式,并举例验证了结论的正确性.     

Optimal Enforcement on a Pure Seller's Market of Illicit Drugs

An optimal control problem for the dynamic enforcement (crackdown) of dealers on a pure seller's market for illicit drugs is explored. Theorems on existence and uniqueness of the optimal synthesis are proved. Using a technique of resolution of singularities for degenerate differential equations, we design analytically an optimal enforcement policy.