A reference model for team-enabled workflow management systems

Today's workflow systems assume that each work item is executed by a single worker. From the viewpoint of the system, a worker with the proper qualifications selects a work item, executes the associated work, and reports the result. There is usually no support for teams, i.e., groups of people collaborating by jointly executing work items (e.g., the program committee of a conference, the management team of a company, a working group, and the board of directors). In this paper, we propose the addition of a team concept to today's workflow management systems. Clearly, this involves a marriage of workflow and groupware technology. To shed light on the introduction of teams, we extend the traditional organizational meta model with teams and propose a team-enabled workflow reference model. For this reference model and to express constraints with respect to the distribution of work to teams, we use object constraint language (OCL).     

A model reference adaptive control scheme for pure-feedbacknonlinear systems

A model reference adaptive control (MRAC) scheme is presented for nonlinear systems in a pure-feedback canonical form with unknown parameters. The present of parameter uncertainty in the system causes imperfect linearization, i.e. it introduces nonlinear additive terms in the transformed coordinates. Under some mild technical assumptions, global convergence of the output error is established for all initial estimates of the parameter vector lying in an open neighborhood of the true parameters in the parameter space     

A standard reference model for intelligent multimedia presentation systems

This article summarizes the main results of a joint endeavor towards a standard reference model (SRM) for intelligent multimedia presentation systems (IMMPSs). After a brief motivation, we give basic definitions for media terms and presentation systems. The core of this contribution is a generic reference architecture that reflects an implementation-independent view of the processes required for the generation of multimedia presentations. The reference architecture is described in terms of layers, components, and knowledge servers. Our SRM focuses on the functions assigned to the layers and components, rather than on the methods or communication protocols that may be employed to realize this functionality. Finally, we point to some possible extensions of the reference model.     

A condition for decentralization in model reference adaptive systems

It is shown that when the interconnection pattern within a system conforms to certain prescribed symmetry requirements, decentralized adaptive algorithms for identification and control can be developed within a decomposition-decentralization framework. This is useful in the presence of constraints on the available information structure of the system.     

A hyperstability criterion for model reference adaptive control systems

This paper considers the stability problem of the model reference adaptive control systems by means of the properties of hyperstable systems. A theorem concerning the hyperstability of model reference adaptive control systems is presented. This theorem directly gives a structure of the adaption mechanism. The results presented here include all the results obtained by Butchart, Shackcloth, Parks, Winsor, Roy, and Dressler. The hyperstability approach presented in this paper also allows for other solutions to the adaption mechanism and represents a general method for studying this type of adaptive systems. The results are directly applicable to the design of model reference adaptive control systems and they were verified for some particular cases by analogical simulation.     

A holistic roadmap for survivable infrastructure systems

The role of a holistic risk assessment and management process in information technology (IT), information assurance (IA), and survivable dependable systems is the subject of this paper. To address the multiple dimensions and perspectives of the risks of terrorism to cyber and interconnected physical infrastructures, hierarchical holographic modeling is introduced and is related to the risk assessment and management process. The definition of information assurance as the trust that information presented by the system is accurate and is properly represented necessitates that trust, knowledge management, organizational behavior, and other nontechnology-based considerations be addressed in the protection of IA against terrorist attacks.     

A model reference adaptive technique of identification for discrete systems

A rapidly convergent algorithm based on a model reference adaptive technique for the identification of the unknown parameters of a noise free discrete dynamical system is presented. This algorithm is based on a geometric interpretation of the Kudva-Narendra scheme. The algorithm does not require any a priori information about the system. An example is included to demonstrate the strength of the algorithm.     

A secure fog-based platform for SCADA-based IoT critical infrastructure

The rapid proliferation of Internet of things (IoT) devices, such as smart meters and water valves, into industrial critical infrastructures and control systems has put stringent performance and scalability requirements on modern Supervisory Control and Data Acquisition (SCADA) systems. While cloud computing has enabled modern SCADA systems to cope with the increasing amount of data generated by sensors, actuators, and control devices, there has been a growing interest recently to deploy edge data centers in fog architectures to secure low-latency and enhanced security for mission-critical data. However, fog security and privacy for SCADA-based IoT critical infrastructures remains an under-researched area. To address this challenge, this contribution proposes a novel security “toolbox” to reinforce the integrity, security, and privacy of SCADA-based IoT critical infrastructure at the fog layer. The toolbox incorporates a key feature: a cryptographic-based access approach to the cloud services using identity-based cryptography and signature schemes at the fog layer. We present the implementation details of a prototype for our proposed secure fog-based platform and provide performance evaluation results to demonstrate the appropriateness of the proposed platform in a real-world scenario. These results can pave the way toward the development of a more secure and trusted SCADA-based IoT critical infrastructure, which is essential to counter cyber threats against next-generation critical infrastructure and industrial control systems. The results from the experiments demonstrate a superior performance of the secure fog-based platform, which is around 2.8 seconds when adding five virtual machines (VMs), 3.2 seconds when adding 10 VMs, and 112 seconds when adding 1000 VMs, compared to the multilevel user access control platform.     

A bilevel mixed-integer program for critical infrastructure protection planning

Vulnerability to sudden service disruptions due to deliberate sabotage and terrorist attacks is one of the major threats of today. In this paper, we present a bilevel formulation of the r-interdiction median problem with fortification (RIMF). RIMF identifies the most cost-effective way of allocating protective resources among the facilities of an existing but vulnerable system so that the impact of the most disruptive attack to r unprotected facilities is minimized. The model is based upon the classical p-median location model and assumes that the efficiency of the system is measured in terms of accessibility or service provision costs. In the bilevel formulation, the top level problem involves the decisions about which facilities to fortify in order to minimize the worst-case efficiency reduction due to the loss of unprotected facilities. Worst-case scenario losses are modeled in the lower-level interdiction problem. We solve the bilevel problem through an implicit enumeration (IE) algorithm, which relies on the efficient solution of the lower-level interdiction problem. Extensive computational results are reported, including comparisons with earlier results obtained by a single-level approach to the problem.     

U-biofeedback: a multimedia-based reference model for ubiquitous biofeedback systems

Biofeedback is a well-accepted approach in preventative and alternative healthcare. It is known to promote wellbeing and help prevent and treat a wide variety of disorders related to the human physiology and psychology. With the exceptional growth of wearable sensor technologies, the potential for devising biofeedback systems that blend into everyday living is immense. Therefore, we present our vision for U-Biofeedback, a reference model for systems designed to continuously monitor our physiology and convey to us important messages regarding our status. Also, we present a case study for an application that implements our reference model. The application is designed to monitor the stress of individuals working in an office setting and provide an assistive response whenever stress reaches elevated levels. By devising an algorithm for stress detection that makes use of Heart Rate Variability (HRV) measures, we were able to identify negative stress situations with an accuracy of 89.63 % and a false positive detection rate of 5.55 % during our evaluation.     

A generalization of the hyperstability conditions for model reference adaptive systems

A generalization of the hyperstability criterion given in the literature is discussed. The new hyperstability conditions were obtained by utilizing the properties of the positive definite kernels. The results presented here are directly applicable for the synthesis of hyperstable adaptation algorithms for various applications.     

A complex event routing infrastructure for distributed systems

With the growing number of mega services and cloud computing platforms, industrial organizations are utilizing distributed data centers at increasing rates. Rather than the request/reply model, these centers use an event-based communication model. Traditionally, the event-based middleware and the Complex Event Processing (CEP) engine are viewed as two distinct components within a distributed system’s architecture. This division adds additional system complexity and reduces the ability for consuming applications to fully utilize the CEP toolset. This article will address these issues by proposing a novel event-based middleware solution. We introduce Complex Event Routing Infrastructure (CERI), a single event-based infrastructure that serves as an event bus and provides first class integration of CEP. An unstructured peer-to-peer network is exploited to allow for efficient event transmission. To reduce network flooding, superpeers and overlay network partitioning are introduced. Additionally, CERI provides each client node the capability of local complex query evaluation. As a result, applications can offload internal logic to the query evaluation engine in an efficient manner. Finally, as more client nodes and event types are added to the system, the CERI can scale up. Because of these favorable scaling properties, CERI serves as a foundational step in bringing event-based middleware and CEP closer together into a single unified infrastructure component.     

A general knowledge mediation infrastructure for multi-agent systems

Intelligent decision making needs to be equipped with broader knowledge in order to enhance the decision quality. Knowledge for decision making can be categorized as domain specific and general. Applying domain knowledge in intelligent systems is not new, but applying general knowledge to support business decision making is a possible way to obtain an edge over competitors. For this reason, the paper focuses primarily on designing a general knowledge mediation infrastructure (GKMI) which supports the use of general knowledge from multiple heterogeneous sources, and provides an unified access point for typical multi-agent systems (MAS) to access that knowledge. The finite state automaton (FSA) is used to model and analyze the commonsense inference ability of GKMI. By carrying out two use cases of GKMI for MAS development and operation the effectiveness of this infrastructure is examined.     

On reference model tracking for Markov jump systems

This article deals with the tracking problem for the Markov Jump systems with external finite energy disturbance. A state feedback controller that makes the state vector of the system track precisely a given state vector of a reference model is proposed. The tracking problem is formulated as an ?_∞ control problem and an approach to synthesise the state feedback controller that quadratically stabilises the augmented dynamics and at the same time rejects the external disturbance that is developed. This approach is based on the solution of some linear matrix inequalities. A numerical example is provided to show the usefulness of the developed results.     

Extended Lyapunov adaptation law for model reference systems

An extension of the adaptation methods presented previously by Ten Cate are presented. Proof of asymptotic stability of the error is effected using Lyapunov theory. This method completes the triplet of a group of previously published adaptation rules for a variation suggested by Shahein et al. using a plant-model parameter misalignment function.     

A hardwired NoC infrastructure for embedded systems on FPGAs

A hardwired network-on-chip based on a modified Fat Tree (MFT) topology is proposed as a communication infrastructure for future FPGAs. With extremely simple routing, such an infra structure would greatly enhance the ongoing trend of embedded systems implementation using multi-cores on FPGAs. An efficient H-tree based floor plan that naturally follows the MFT construction methodology was developed. Several instances of the proposed NoC were implemented with various inter-routers links progression schemes combined with very simple router architecture and efficient client network interface (CNI). The performance of all these implementations was evaluated using a cycle-accurate simulator for various combinations of NoC sizes and traffic models. Also a new data transfer circuit for transferring data between clients and NoC operating at different (unrelated) clock frequencies has been developed. Allowing data transfer at one data per cycle, the operation of this circuit has been verified using gate-level simulations for several ratios of NoC/client clock frequencies.     

Of critical importance: Toward a quantitative probabilistic risk assessment framework for critical infrastructure

Critical comments can be made to the current risk assessment framework for critical infrastructure used in The Netherlands: the Dutch National Risk Assessment (DNRA). The DNRA uses a qualitative approach to risk assessment, based on, for example, ordinal risk scoring and the risk matrix. Even though qualitative risk assessment methods are internationally popular, there is no scientific evidence that a qualitative approach to risk assessment actually works. In the case of the DNRA, the main points of criticisms relate to the usage of a subjective concept of risk, dependency on subjective risk experts, the use of risk matrices and the absence of decision rules. To combat these criticisms, this article proposes a quantitative probabilistic risk assessment framework for critical infrastructure based upon four design principles, that a methodologically justified risk assessment method for critical infrastructure should meet. The proposal made for the quantitative risk assessment framework uses a Bayesian approach, a standardized measure for negligible risk in the form of a yearly mortality probability of 10⁻⁶, and Disability Adjusted Life Years to quantify human life years for social cost–benefit analysis. Finally, the proposed quantitative method is demonstrated in a case study.     

Multi-agent systems for protecting critical infrastructures: A survey

Multi-agent systems have emerged as a very significant platform in provisioning distributed and collaborative services to critical applications. Such applications require ubiquitous agent presence in the environment for monitoring, collecting data, communication, and subsequent data analysis, where the sensitivity of the application's nature cannot be understated. Recent advances in the field of autonomous, ubiquitous, intelligent and distributed computing have led to corresponding developments in the use of collaborating multi-agents to protect critical infrastructures. Such systems have witnessed crucial demand for deployment in diverse application scenarios such as E-commerce, E-health, Network Intrusion Detection, Telematics and Transport Systems, Environmental Monitoring, as well as for distributed information processing in general. Critical infrastructures have longed for a distributed system in place for their uninterrupted and accurate operations. Multi-agents have provided one such approach towards addressing the issue of protecting such infrastructures through collaborative and distributed information processing. In this paper, a state-of-the-art on the use of multi-agent based systems for protecting five most common critical infrastructures, is presented.     

A decentralized model reference adaptive variable structure controller for large-scale time-varying delay systems

In this note, the problem of decentralized model reference adaptive variable structure control for a class of perturbed large-scale systems with varying time-delay interconnections is investigated. Based on the Lyapunov stability theorem, an adaptive variable structure control strategy for solving the robust tracking problem without the knowledge of upper bound of perturbations is developed. The use of adaptive technique is to adapt the unknown upper bound of perturbations so that the objective of globally asymptotical stability is achieved. Once the system enters the sliding manifold, the dynamics of controlled systems are insensitive to matching perturbations. Finally, an example is given to demonstrate the feasibility of the proposed control scheme.