A Two-Pronged Approach to Security of Discrete-Event Systems

This paper investigates a security problem of simultaneously addressing two types of attacks: Eavesdropping and infiltration. The authors model the target system as a discrete-event system(DES) with subsets of concealable events and protectable events, in order to make the proposed methodology applicable to various practical systems and employ two existing works of DES security: Degree of opacity and state protection. Specifically, the authors consider that all protectable events are observable, and some observable events are concealable. In addition, protectable events cannot be protected once they are concealed. Given such a constraint, the goal is to figure out which events to conceal and which transitions to protect so that the prescribed requirements of degree of opacity and state protection are satisfied. In this work the authors decide which events to conceal as all transitions of a given event label are concealed or not concealed. The proposed problem formulation also requires a solution to only involve absolutely necessary protectable events in order for the system to avoid superfluous protection costs. The authors first examine a general version of our security problem with an intuitive algorithm to compute acceptable solutions, and then present a special version which results in a reduced computation time compared to the general version.     

A Systems Science Approach to Inter-Organisational Complementarity in Tourism SMEs

Systemic Practice and Action Research - This article proposes a model based on the integration of systemic mechanisms such as the soft systems methodology, partial least squares path modelling and...     

A Critical Systems Approach to Elicit User-Centric Business Intelligence Business Requirements

This paper describes an action research study where the researcher developed and tested an alternative business requirements elicitation approach that enables reflection on business intelligence business requirements from a social/organisational perspective and, accordingly, surfaces user-centric requirements that support development of systems that are technically good and effectuate organisational improvement. It is based on critical systems heuristics, a framework that facilitates participative discourse to surface contributing and consequential factors of a planned social system, i.e. relevant sources of motivation; expertise; inflicting and controlling boundaries; and sources of moral and political justification acting as guardians for all that will be impacted upon by the adjusted social reality caused by the new system. Such an approach is valuable to developers of business intelligence systems; it complements traditional requirements gathering approaches. Present-day organisations require efficacious decision-making capabilities to succeed—business intelligence systems enable efficacious decisions. However, business intelligence systems often fail, at great expenses to organisations. They fail due to social/organisational infeasibility, rather than technical insufficiency; they fail when developers lack adequate understanding of users’ business requirements. Appropriate business requirement specifications entail more than definitions of functional, non-functional and technical attributes of new systems. Business requirements must also capture the social/organisational context of a system, i.e. the impact that it will inevitably have on users and the organisational environment, so as to ensure that it ultimately bring about improvement. The approach developed in this study enables elicitation of user-centric business requirements.

     

EXTENDED CASIMIR APPROACH TO CONTROLLED HAMILTONIAN SYSTEMS

In this paper,we first propose an extended Casimir method for energy-shaping.Then itis used to solve some control problems of Hamiltonian systems.To solve the H_x control problem,theenergy function of a Hamiltonian system is shaped to such a form that could be a candidate solution ofHJI inequality.Next,the energy function is shaped as a candidate of control ISS-Lyapunov function,and then the input-to-state stabilization of port-controlled Hamiltonian systems is achieved.Someeasily verifiable sufficient conditions are presented.     

一种基于多主体仿真的制度有效性分析方法研究

分析了仿真技术在制度有效性分析方面的研究现状。介绍了复杂适应系统理论由来及特性。指出了复杂适应系统及其仿真模型在制度有效性分析方面的优势。提出了基于复杂适应系统模型的制度有效性仿真分析方法。最后展示了一个实际应用。     

A Holistic Approach for Designing Human-Centric Trust Systems

Online trust systems, albeit existing as technical implementations, aim to translate the role that trust has in the traditional world onto the virtual platforms. Establishing the inter-dependence between these systems and the human-factor is essential for reducing, but more importantly for understanding the inherent complexity of the open social platforms, and for improving the user-experience and system-performance. This work determines the systemic features of trust and introduces a novel framework of design-properties based on the principles of General Systems Theory. We determine the systemic properties which lack in the current technical solutions, and incorporate social factors into the design-guidelines of trust systems. We introduce four influence-factors and demonstrate that accounting for those factors leads to compliance with the generic system-principles. Finally, we employ case study analysis following the premises of case study research established in the social science literature. By performing semantic analysis of the state of the art on trust systems, we are able to identify two semantic clusters to which trust research belongs, and to choose in a non-random manner the representative case studies for evaluation upon our framework. To our knowledge, this is the first study applying fundamental social science principles from General Systems Theory and case-study research for the purpose of theory-building and evaluation of technical human-centric solutions.     

A GMRP Approach for Reliability Analysis of Repairable Systems

We propose here a mathematical approach for the study of repairable systems with arbitrary distributions. The idea is to define a new type of stochastic process, called a generalized Markov renewal process (GMRP). which may describe the transition behavior of the stochastic process at non-regenerative points. In the paper an analytical method for the GMRP is put forward and the formulas are then presented for reliability analysis of repairable systems which can be described by a GMRP with finite states. A signal flow graph technique for system modeling is also summarized here. Finally- an analytical model to evaluate the reliability of a m-out-of- n.G system with general repair-time distribution is developed by means of the GMRP approach.     

一类典型非线性-线性系统数学模型建立方法

对于典型的Hammerstein模型,如“死区一线性”和“空回一线性”系统模型,在非线性和线性部分之间的任何信息都不知道的情况下,只根据系统输入和输出信息,利用频谱分析方法,可以识别出非线性和线性部分的全部参数,并对非线性特性进行确认性检验。本文给出了识别系统全部参数的方法和步骤,最后以例题说明。     

管理信息系统的最优k分解方法

本文提出一种从管理信息系统的基本元素——过程和数据类的分析入手,建立信息系统的有向图模型,并运用最优k分解方法进行模型的分解与优化的形式化方法,文中还给出了一个企业管理信息系统的例子来说明方法的应用.     

Elaborating a Critical Realist Approach to Soft Systems Methodology

Systemic Practice and Action Research - This paper explores the implications of adopting a critical realist approach to soft systems methodology (SSM) both to address local problematic situations...     

Normative Evaluation of Community Projects: A Multimodal Systems Approach

This paper introduces an evaluation method for community projects based on the multimodal systems approach. The method differs from the common mechanistic approach to evaluation in four ways. Firstly, it uses the long-term life (viability) of a community as the ultimate criteria of evaluation. Secondly, it is normative; that is, it focuses on the responsibility of people to their own community and for managing their own lives. Thirdly, it is dynamic; it identifies factors that threaten a community and examines their dynamic link and long-term impact on the community. Fourthly, it evaluates the adequacy of a community activity (good practice) to help ensure its long-term viability. The method is illustrated with a European Union sponsored project.     

A Systems Thinking Approach to Investigating Complex Sugarcane Supply and Processing Systems: Integrating Rich Pictures and Bayesian Networks

Diagnosing problems in complex systems such as integrated sugarcane supply and processing systems (ISSPS) calls for a systematic approach. This is vital given the numerous stakeholders and their various (sometimes conflicting) objectives. Since ISSPS are socially constructed, most diagnostic interventions in the system should consider participatory approaches; developing a shared understanding of the issues and decision-making processes. Failure to source and simultaneously accommodate stakeholder perspectives often leads to interventions on wrong issues and subsequently, policy resistance. Given the context, a diagnostic study was undertaken at a sugarcane milling area in Swaziland to identify problems affecting the ISSPS. Interviews were conducted with relevant stakeholders and issues affecting the area were modelled as a rich picture and communicated back to the stakeholders in a report-back meeting held at the milling area. Excessive rainfall, harvest-to-crush delays, sugarcane quality, harvesting and haulage schedules, and machine breakdown were some of the issues identified to affect the milling area. It was recommended in the report-back meeting that machine breakdown be considered for further analysis hence, a Bayesian model for a shredder breakdown was developed. The Bayesian model estimated the probability of shredder breakdown to be to be 0.124. Furthermore, the months of April and May appeared more susceptible than the other months. It was recommended that further analysis of shredder breakdown be conducted, especially alongside rainfall, preventative maintenance and skills of the maintenance personnel. It was also recommended that further research be conducted towards developing strategies that could be used to ensure reliable sugarcane supply at the factory, especially during periods of extreme rainfall. A stockpile feasibility study that considers factors that contributed to the termination of the previous stockpile system could provide some direction.     

A Periodic Event-Based Approach to Leader-Following Consensus for Linear Multi-Agent Systems with Time-Varying Delays

In this paper, the authors address the bounded leader-following consensus problem for linear multi-agent systems connected via undirected graphs, specifically in the presence of non-consistent time-varying communication delays. The periodic event-triggered scheme is proposed to mitigate the adverse effects of these delays, which ensures discrete data transmission only occurs at specific event instants. By leveraging the nature of periodic event-triggered schemes, Zeno-freeness can be guaranteed by discretely event-checking. Additionally, the appropriate design of the threshold range prevents the event-triggered consensus from degrading into sampled-data consensus. The numerical simulation is presented in the end to show the effectiveness of the provided approach.     

General Systems Thinking and Community-Based Rehabilitation: A Theoretical Exploration

Systemic Practice and Action Research -     

Management Information Systems Education from A Systemic Viewpoint

As a proponent of systems thinking and as an MIS educator, I am interested in assuring that systems thinking is (and remains) incorporated into MIS education, not nominally but truly in spirit. This paper reviews some of the highlights of the history of MIS education, with a view toward the identification and preservation of its systemic spirit.     

Dynamic Event-Triggered Control for Nonlinear Systems: A Small-Gain Approach

An event-triggered control(ETC) system transmits data packages and updates control inputs only when the predefined criterion is satisfied. In this way, network communication and computing resources are scheduled more reasonably in contrast to the traditional periodic sampling strategy.Small-gain approach proposed in recent literatures is a new modeling method to deal with nonlinear ETC systems. Different from traditional ETC models, stability criteria are proposed in the form of input to state stability(ISS) gain to design the triggering mechanisms. This paper introduces additional dynamic variables in this model and proposes a small-gain based dynamic event-triggered strategy.Sufficient conditions to guarantee the stability of the system are derived with the help of cyclic-smallgain theorem and Zeno behaviors are avoided to ensure the feasibility of this method in practical applications. Numerical simulations are given to demonstrate the effectiveness of our approach.     

A Guaranteed Cost Approach to Dynamic Output Feedback Control for Neutral-Type Markovian Jumping Stochastic Systems

This paper is devoted to investigating the dynamic output feedback(DOF) control problem of Markovian jump neutral-type stochastic systems with a guaranteed cost function. Both of the state and measurement equations contain time delays. Mode-dependent DOF controllers are first designed such that the closed-loop system is asymptotically stable in mean-square and an adequate performance level of this system is guaranteed. Then, sufficient conditions for the solvability of this problem are derived in the form of linear matrix inequalities(LMIs). A numerical example is presented to reveal the effectiveness of our findings.     

A Non-Convex Optimization Approach to Dynamic Coverage Problem of Multi-agent Systems in an Environment with Obstacles

In this paper, a cooperative region reconnaissance problem is investigated where a group of agents are required to fly across and detect events occur in an environment with static obstacles until an effective coverage is achieved. First, the region reconnaissance is formulated as a non-convex optimization problem. A coverage performance index with additional collision and obstacle avoidance constraints is given. Since the optimization index is an implicit function of state variables and cannot be used to compute gradients on state variables directly, an approximate optimization index is selected.Then, a non-convex optimization-based coverage algorithm is proposed to find the optimal reconnaissance location for each agent and guarantee no collisions trajectories among agents and obstacles.Finally, simulation experiments are performed to verify the effectiveness of the proposed approach.     

一般Lur''e混沌系统指数同步的M-矩阵方法

由于许多混沌系统是Lure系统,因此近年来开始对基于Lure混沌系统的同步问题的研究。采用M-矩阵方法和Lyapunov函数方法以及时滞反馈控制技术研究了一般Lure混沌系统的指数同步问题,得到了易于检验的指数同步的代数判据,而且对其Lyapunov指数进行了估计。由此可设计出这种混沌同步方案的反馈控制器。最后,给出了例子加以说明。