New upper bounds for excited vibration systems with applications of the differential calculus of norms

In an earlier paper, the author introduced new upper bounds for free linear and nonlinear vibration systems; to compute the best upper bounds, the differential calculus of norms was applied. In the present paper, this work is continued for the corresponding excited systems. Some new techniques and ideas are involved. The results in the applications cannot be obtained by the methods used so far.     

Two-sided bounds for the asymptotic behaviour of free nonlinear vibration systems with application of the differential calculus of norms

This paper deals with the free nonlinear dynamical system [xdot](t)=A x(t)+h(t, x(t)), t≥t ₀, x(t ₀)=x ₀, where A is an n×n-matrix and h a nonlinear vector function with h(t, u)=o(∥u∥). As the first novel point, a lower bound for the asymptotic behaviour on the solution x(t) is derived. Two methods are applied to determine the optimal two-sided bounds, where one of the methods is the differential calculus of norms. In this context, the second novel point enters; it consists of a new strategy to significantly reduce the computation time for the determination of the optimal constants in the two-sided bounds. The obtained results are especially of interest in engineering and cannot be obtained by the methods used so far.     

A Maximum Principle via Malliavin calculus for combined stochastic control and impulse control of forward‐backward systems

We consider a combined stochastic control and impulse control problem of forward‐backward systems driven by Lévy processes, where both the system coefficients and the objective performance functional are allowed to be random, non‐Markovian; the information available to the controller is partial information. Applying a Malliavin calculus approach, we derive a maximum principle for this control problem, where the adjoint processes are explicitly represented by the parameters and the states of the system. Finally, we give two examples of applications. © 2015 Chinese Automatic Control Society and Wiley Publishing Asia Pty Ltd     

From event calculus to the scheduling problem. Semantics of action and temporal reasoning in aircraft maintenance

In this work we are interested in the logical and semantical aspects of reasoning about actions in a scheduling process. We present an adaptation of the event calculus of Kowalski and Sergot to the problem of determining the temporal structure of the operations that must be performed during the realization of some complex objectives. Our application domain is aircraft maintenance. We try to reason about the actions which are performed during an overhaul in order to help to schedule them. The original model reasons about changes, i.e. events which initiate or terminate propositions. The first step of this work was to improve the initial model by adding a temporal relation between events and propositions because in our field we also have to reason about events which only inform us about some propositions without affecting them. The second step of this work is to build a set of specific rules which temporally interpret the semantics of the usual specifications of the actions to be considered. This interpretation aims to associate each action with two events and some temporal relations which are usable by the general model. Temporal reasoning uses pertinent knowledge about the specific universe (here, the aircraft that we consider and the actions which may be performed on it). We outline a generative methodology to formalize this relevant knowledge efficiently. This cognitive approach brings more informational economy in temporal reasoning because only the relevant information is considered The temporal reasoning model and the methodology have been exemplified and tested on a complex part of an aircraft. In the future, adapted tools based on this approach will be developed, in order to solve several problems of aircraft maintenance scheduling.     

Tools and algorithms for the construction and analysis of systems

This special section contains the revised and expanded versions of eight of the papers from the 10th International Conference on Tools and Algorithms for the Construction and Analysis of Systems (TACAS) held in March/April 2004 in Barcelona, Spain. The conference proceedings appeared as volume 2988 in the Lecture Notes in Computer Science series published by Springer. TACAS is a forum for researchers, developers and users interested in rigorously based tools for the construction and analysis of systems. The conference serves to bridge the gaps between different communities – including but not limited to those devoted to formal methods, software and hardware verification, static analysis, programming languages, software engineering, real-time systems, and communications protocols – that share common interests in, and techniques for, tool development. Other more theoretical papers from the conference are collected in a special section of the Theoretical Computer Science journal.     

The impact of hierarchical positions on the type of communication within online Communities of Learning

Communities of Learning (CoL) have been suggested to facilitate the learning process among participants of online trainings. Yet, previous studies often detached participants from the social context in which learning took place. The present study addresses this shortcoming by providing empirical evidence from 25 CoL of a global organization, where 249 staff members from different hierarchical positions engaged into collaborative learning via asynchronous discussion forums. We conduct a longitudinal study on the type of communication within these CoL, as well as participants' network positions, in order to investigate the research question: What is the impact of individual's hierarchical positions on the type of communication within CoL? Our results indicate that the higher participants' hierarchical position, the higher their amount of social and cognitive communication, which in turn was also positively related to their network position within CoL. We also identified a sub-group of Stars that outperformed their colleagues and who were at the center of CoL, irrespective of their hierarchical positions. Consequently, we propose design and facilitation strategies to practitioners and organizers of future CoL that can foster the learning processes and outcomes of all participants. Additionally, we consider future research avenues that could be explored further.     

Computer algebra for the calculus of variations,the maximum principle,and automatic control

This paper describes how a computer-algebra system can solve variational optimization problems analytically. For a calculus-of-variations problem, users provide functional integrands and constraints. A program derives corresponding Euler-Lagrange equations, together perhaps with first integrals. Other programs attempt analytic solution of these equations. For an optimal control problem, users provide analytic expressions for the differential constraints on the state variables. A program determines the corresponding Hamiltonian and differential equations for the auxiliary variables, together with solutions to any trivial auxiliary equations. Other programs attempt analytic solution of the remaining equations while maximizing the Hamiltonian.This material is based upon work supported by the National Science Foundation under Grant No. MCS75-22983 A01.     

Predicting the type of pregnancy using artificial neural networks and multinomial logistic regression: a comparison study

Some medical and epidemiological surveys have been designed to predict a nominal response variable with several levels. With regard to the type of pregnancy there are four possible states: wanted, unwanted by wife, unwanted by husband and unwanted by couple. In this paper, we have predicted the type of pregnancy, as well as the factors influencing it using two different models and comparing them. Regarding the type of pregnancy with several levels, we developed a multinomial logistic regression and a neural network based on the data and compared their results using three statistical indices: sensitivity, specificity and kappa coefficient. Based on these three indices, neural network proved to be a better fit for prediction on data in comparison to multinomial logistic regression. When the relations among variables are complex, one can use neural networks instead of multinomial logistic regression to predict the nominal response variables with several levels in order to gain more accurate predictions.     

Function and service pattern analysis for facilitating the reconfiguration of collaboration systems

Recently, manufacturing companies have been attempting to increase competitiveness in their business collaboration with cooperative companies rather than within their own companies. In order to facilitate their collaboration, they are attempting to adopt or already using a collaboration system, which supports a number of functions and services. However, it is very difficult to apply existing systems into other organizations or industrial sections without customization or reconfiguration because functional or service requirements of users usually differ according to their domain knowledge. In order to re-apply and disseminate an existing system to other companies, therefore, the system must be reconfigured by modifying, upgrading, or newly developing some portions of the system. During the customization processes, functions or services of the system must be refined in order to satisfy user requirements. For facilitating the reconfiguration of collaboration systems, in this paper, we first define user patterns, and subsequently propose a method for investigating and analyzing patterns based on data mining approach. The proposed method validates normal versus abnormal patterns that show a drastic increase in the use of a specific function or service, and automatically makes the system recognize abnormal patterns as new normal patterns when abnormal patterns continue for a long time. We conduct experiments and comparison studies using an Apriori-like approach in order to establish the effectiveness of the proposed method. We also suggest a guideline for the reconfiguration of function modules or services with a specific collaboration system.     

变频调速系统中电动机和变频器选择及问题分析

本文分析了选用标准笼形电动机的容量计算方法、问题分析和选用变频器的型式、容量、注意事项。     

Parallel sample path generation for discrete event systems and the traffic smoothing problem

We review two approaches, the Standard Clock (SC) technique and Augmented System Analysis (ASA), that have been proposed for generating sample paths of Discrete Event Systems (DES) in parallel. These are placed in the unifying framework of the fundamentalsample path constructability problem: for a finite discrete parameter set = {₁, ..., _m }given a sample path under ₁ the problem is to simultaneously construct sample paths under all remaining parameter values. Using the ASA approach we then consider the problem of smoothing arbitrary, generally bursty, and possibly nonstationary traffic processes which are encountered in many applications, especially in the area of flow control for integrated-service, high-speed networks. We derive some basic structural properties of a smoothing scheme known as the Leaky Bucket (LB) mechanism through which it is seen that the variability of a traffic process can be monotonically decreased by decreasing an integer-valued parameter of this scheme. Finally, we show that a sample path under any value of this parameter is constructable with respect to an observed sample path under any other value. Therefore, by controlling this parameter on line, we show how simple iterative optimization schemes can be used to achieve typical design objectives such as keeping both the mean packet delay due to smoothing and the variability of the traffic process low.     

汽车ASR系统ECU开发及其硬件在环测试

主要设计和开发了 ASR 控制的核心部件——电子控制单元(ECU)并进行了测试。ECU 硬件主要包括 MCU 最小系统电路、SPI 通讯电路、轮速信号处理电路、执行机构驱动电路和 CAN 通讯电路等;设计了软件方案、编写了程序代码。把开发的 ECU 在以 dSPACE 为核心的硬件在环试验台进行了硬件在环测试。测试结果表明 ECU 能够实现驱动防滑控制功能,用硬件在环仿真方法开发电子控制单元有较大的优越性。     

Static type information to improve the IDE features of hybrid dynamically and statically typed languages

The flexibility offered by dynamically typed programming languages has been appropriately used to develop specific scenarios where dynamic adaptability is an important issue. This has made some existing statically typed languages gradually incorporate more dynamic features to their implementations. As a result, there are some programming languages considered hybrid dynamically and statically typed. However, these languages do not perform static type inference on a dynamically typed code, lacking those common features provided when a statically typed code is used. This lack is also present in the corresponding IDEs that, when a dynamically typed code is used, do not provide the services offered for static typing. We have customized an IDE for a hybrid language that statically infers type information of dynamically typed code. By using this type information, we show how the IDE can provide a set of appealing services that the existing approaches do not support, such as compile-time type error detection, code completion, transition from dynamically to statically typed code (and vice versa), and significant runtime performance optimizations. We have evaluated the programmer׳s performance improvement obtained with our IDE, and compared it with similar approaches.     

Increasing the degree of information system integration and developing an integrated information system

The structure of an information system is defined, and the structural elements are considered as factors in providing measures of the degree of integration of an information system. Absorption, exclusion, reorganization and transfer are processes considered in the role of increasing the degree of integration. Finally measures for the effectiveness of integration of two or more systems are discussed.     

Combinatorial optimization model and MIP formulation for the structural analysis of conditional differential-algebraic systems

In this paper we consider the structural analysis problem for differential-algebraic systems with conditional equations. This problem consists, given a conditional differential-algebraic system, in verifying if the system is structurally nonsingular for every state, and if not in finding a state in which the system is structurally singular. We give a formulation for this problem as an integer linear program. This is based on a transformation of the problem into a matching problem in an auxiliary graph. We also show that the linear relaxation of that formulation can be solved in polynomial time. Using this, we develop a Branch-and-Cut algorithm for solving the problem and present some experimental results.     

On the Moser- and super-reduction algorithms of systems of linear differential equations and their complexity

The notion of irreducible forms of systems of linear differential equations with formal power series coefficients as defined by Moser [Moser, J., 1960. The order of a singularity in Fuchs’ theory. Math. Z. 379–398] and its generalisation, the super-irreducible forms introduced in Hilali and Wazner [Hilali, A., Wazner, A., 1987. Formes super-irréductibles des systèmes différentiels linéaires. Numer. Math. 50, 429–449], are important concepts in the context of the symbolic resolution of systems of linear differential equations [Barkatou, M., 1997. An algorithm to compute the exponential part of a formal fundamental matrix solution of a linear differential system. Journal of App. Alg. in Eng. Comm. and Comp. 8 (1), 1–23; Pflügel, E., 1998. Résolution symbolique des systèmes différentiels linéaires. Ph.D. Thesis, LMC-IMAG; Pflügel, E., 2000. Effective formal reduction of linear differential systems. Appl. Alg. Eng. Comm. Comp., 10 (2) 153–187]. In this paper, we reduce the task of computing a super-irreducible form to that of computing one or several Moser-irreducible forms, using a block-reduction algorithm. This algorithm works on the system directly without converting it to more general types of systems as needed in our previous paper [Barkatou, M., Pflügel, E., 2007. Computing super-irreducible forms of systems of linear differential equations via Moser-reduction: A new approach. In: Proceedings of ISSAC’07. ACM Press, Waterloo, Canada, pp. 1–8]. We perform a cost analysis of our algorithm in order to give the complexity of the super-reduction in terms of the dimension and the Poincaré-rank of the input system. We compare our method with previous algorithms and show that, for systems of big size, the direct block-reduction method is more efficient.     

嵌入式系统的特征、研究概况与设计实现

介绍了嵌入式系统的特点、发展历程、体系结构，阐述了嵌入式操作系统研究现状。设计实现了基于嵌入式Linux的数字系统应用平台。