A new approach to adaptive control: no nonlinearities

In adaptive control the goal is to design a controller to control an uncertain system whose parameters may be changing with time. Typically the controller consists of an identifier (or tuner) which is used to adjust the parameters of a linear time-invariant (LTI) compensator, and under suitable assumptions on the plant model uncertainty it is proven that good asymptotic behaviour is achieved, such as model matching (for minimum phase systems) or stability. However, a typical adaptive controller does not track time-varying parameters very well, and it is often highly nonlinear, which can result in undesirable behaviour, such as large transients or a large control signal. Furthermore, most adaptive controllers provide only asymptotic tracking, with no ability to design for a pre-specified settling time.Here we propose an alternative approach, which yields a linear periodic controller. Rather than estimating the plant or compensator parameters, instead we estimate what the control signal would be if the plant parameters were known. In this paper we argue the utility of this approach and then examine the first order case in detail, including a simulation. We also explore the benefits and limitations of the approach.     

SATCHMOREBID: SATCHMO(RE) with BIDirectional relevancy

SATCHMORE was introduced as a mechanism to integrate relevancy testing with the model-generation theorem prover SATCHMO. This made it possible to avoid invoking some clauses that appear in no refutation, which was a major drawback of the SATCHMO approach. SATCHMORE relevancy, however, is driven by the entire set of negative clauses and no distinction is accorded to the query negation. Under unfavorable circumstances, such as in the presence of large amounts of negative data, this can reduce the efficiency of SATCHMORE. In this paper we introduce a further refinement of SATCHMO called SATCHMOREBID: SATCHMORE with BIDirectional relevancy. SATCHMOREBID uses only the negation of the query for relevancy determination at the start. Other negative clauses are introduced on demand and only if a refutation is not possible using the current set of negative clauses. The search for the relevant negative clauses is performed in a forward chaining mode as opposed to relevancy propagation in SATCHMORE which is based on backward chaining. SATCHMOREBID is shown to be refutationally sound and complete. Experiments on a prototype SATCHMOREBID implementation point to its potential to enhance the efficiency of the query answering process in disjunctive databases. Donald Loveland, Ph.D.: He is Emeritus Professor of Computer Science at Duke University. He received his Ph.D. in mathematics from New York University and taught at NYU and CMU prior to joining Duke in 1973. His research in automated deduction includes defining the model elimination proof procedure and the notion of linear resolution. He is author of one book and editor/co-editor of two other books on automated theorem proving. He has done research in the areas of algorithms, complexity, expert systems and logic programming. He is an AAAI Fellow, ACM Fellow and winner of the Herbrand Award in Automated Reasoning. Adnan H. Yahya, Ph.D.: He is an associate professor at the Department of Electrical Engineering, Birzeit University, Palestine. He received his Diploma and PhD degrees from St. Petersburg Electrotechnical University and Nothwestern University in 1979 and 1984 respectively. His research interests are in Artificial Intelligence in general and in the areas of Deductive Databases, Logic Programming and Nonmonotonic Reasoning in particular. He had several visiting appointments at universities and research labs in the US, Germany, France and the UK. Adnan Yahya is a member of the ACM, IEEE and IEEE Computer Society.     

基於稳态映照记忆模型的自学习控制

本文介绍了基於系统集的通用智能控制器的设计思想。作为示例，我们对一类具有相同特征与约束的系统集给出了基於稳态映照记忆模型的自学习算法，证明了它的可学习性与收敛性，在不同的对象上验证了它的通用性。     

JAVA新类库中Swing的事件传送机制

ＳＵＮ公司最新发布的一套ＡＰＩ中的Ｓｗｉｎｇ组件集采用了ＭＶＣ结构，其中Ｍ、Ｖ、Ｃ三者间的事件传送及与外界的通信机制相当重要。本文从Ｓｗｉｎｇ的组件如何响应外部事件、如何处理自身的变化及如何把自身变化传递给外界三个方面详细阐述Ｓｗｉｎｇ的事件传送机制。     

基于马尔可夫链组合预测模型的程序设计

用 Fortran语言设计了马尔可夫链组合预测模型中的计算程序 ;并计算出股票价格涨落的概率。     

尾水管高度和宽度对水轮机水力性能的影响

针对不同高度和宽度的尾水管,通过分析其内部水流的流动情况,论述了高度和宽度对尾水管设计的重要性,同时采用CFD分析和模型试验的方法来确定尾水管高度和宽度对水轮机水力性能的影响。     

基于软构件的动态企业建模技术

动态企业建模是企业信息化工程中的一次重大变革.本文在分析动态企业建模理论的基础上,提出了一种基于软构件的动态企业建模技术:在企业建模过程中引入软构件,通过对模型构件的动态重构,快速建立同时具备柔性和扩展性的企业模型.文中详细说明了企业模型的构件化过程和基于软构件的动态建模体系.     

A review of modeling approaches for oriented semi-crystalline polymers

Modeling changes in the physical properties of oriented semi-crystalline polymer films is beneficial for understanding the fundamentals associated with structure property relationships and could be used for developing new polymer films with significantly enhanced physical properties. Relating the molecular changes observed in oriented polymer films to inherent polymer characteristics provides valuable insight for the development of new polymers which exhibit enhanced physical properties upon orientation. Modeling efforts will be reviewed that have attempted to use fiber composite theory to explain the transitions seen during the orientation process.     

Numerical investigation on the heat transfer characteristics of a liquid-metal pool subjected to a partial solidification process

The main purpose of this paper is to investigate numerically the effects of solidification on the heat transfer characteristics of the liquid metal layer, for use in accident analyses. The situation is very similar to an overlying liquid melt pool that could be fooned in the reactor lower head during the late phase of a severe nuclear accident. Based on a computational model, MPCOOL, the numerical predictions were then assessed through a comparison with the experimental data that was obtained with various boundary temperature conditions and geometrical aspect ratios, especially for the Ra-Nu relationship. For the cases with solidification, the results of the comparison show that(a) the computational model does show a good agreement with heat transter rates inferred from the experimental data, with a few exceptions at the Ra numbers which suggest a turbulent transport; and also (b) the computational model underpredicts the heat transfer rates by about 6% than that inferred from the experimental data when it is integrally evaluated with the Ra-Nu correlation. The foregoing results are mainly due to the currently limited applicability of the computational model up to the laminar-to-turbulence transition flows and its application to the turbulence flows because it is always subjected to a model uncertainty between the laminar and turbulence. Next, an additional comparison for the cases with and without solidification was made to examine the effects of the solidification on the energy partition within the liquid metal layer and its effects on the directional heat transfer rates. The results of the comparison show that the computational model for the case without solidification predicts higher heat transfer rates by about 15% than when solidification is included, but there isn't any experimental data that directly supports this trend.     

Nonlinear averaging theorems, and the determination of parameter convergence rates in adaptive control

The paper presents nonlinear averaging theorems for two-time scale systems, where the dynamics of the fast system are allowed to vary with the slow system. The results are applied to the Narendra-Valavani adaptive control algorithm, and estimates of the parameter convergence rates are obtained which do not rely on a linearization of the system around the equilibrium, and therefore are valid in a larger region in the parameter space.