Special issue on ��SCADA and control system security��

Call For Papers

Special issue on “SCADA and control system security”     

Study on robust H �� filtering in networked environments

 This paper is concerned with the robust H_∞ filter problem for networked environments, which are subject to both transmission delay and packet dropouts randomly. By employing random series which have Bernoulli distributions taking value of 0 or 1, the data transmission model is obtained. Based on state augmentation and stochastic theory, the sufficient condition for robust stability with H_∞ constraints is derived for the filtering error system. The robust filter is designed in terms of feasibility of one certain linear matrix inequality (LMI), which is formed by adopting matrix congruence transformations. A numerical example is given to show the effectiveness of the proposed filtering method.     

Magnetic trap effects on nanowire��s dynamics within micro-capillary vessels

The concept of using magnetic nanowires (NWs) as carriers in magnetic drug targeting was largely developed in the last decade. Magnetically controlled and manipulated nanoparticles are gaining more and more ground in various biomedical applications: drug delivery, cancer therapy by magnetic fluid hyperthermia, radiotherapy. In this study, a 2-D mathematical model was developed and implemented to examine the capture of magnetic drug carrier particles within a magnetic trap represented by high magnetic field gradients. The transient dynamics of magnetic NWs under the effect of the blood velocity (v _B) varied from 0.05 up to 1.0 cm/s, magnetic field strength and their initial position within the fluid channel have been analyzed using COMSOL Multiphysics module. The parameters related to the NW with strong influence on the magnetic trap output were systematically modified: magnetic material, cylindrical particle geometry characterized by diameter and length, its initial position related to both fluid flow direction and distance from the channel center. Considering the influence of both hydrodynamic, magnetic forces and torques the magnetic trap’s efficiency was evaluated and phase diagrams were determined for different parameters involved. A considerable number of simulations were made to obtain statistically significant results. These results are commented and discussed in detail.     

The Concept of ��Work�� in CSCW

The scope of CSCW, its focus on work, has been a topic of sporadic debate for many years ?? indeed, from the very beginning in the late 1980s. But in recent years the issue has become one of general concern. Most of this debate has been taking place in closed fora such as program committees, editorial boards, and email discussion groups, but over the last few years the debate has been brought out in the open in a few publications, in particular in a programmatic article from 2005 by three esteemed CSCW researchers: Andy Crabtree, Tom Rodden, and Steve Benford. They argue that CSCW should ??move its focus away from work??. Other researchers argue along the same lines. Taking this open challenge as a welcome cue, the present article addresses CSCW??s scope: the rationale for its focus on ordinary work. After an initial discussion of the arguments put forward by Crabtree et al. and by others, the article focuses on an analysis of the concept of ??work??, drawing on the methods and insights of ??ordinary language philosophy??, and, flowing from this, a critique of the notion of ??work?? in conversation analysis. After a critical appraisal of prevailing myths about the realities of work in the contemporary world, the article ends in an attempt to position CSCW in the context of technological development more broadly. The underlying premise of the article is that it is time to reconsider CSCW: to rethink what it is and why it might be important.     

Effect of the skimming layer on electro-osmotic��Poiseuille flows of viscoelastic fluids

An analytical solution is derived for the micro-channel flow of viscoelastic fluids by combined electro-osmosis and pressure gradient forcing. The viscoelastic fluid is described by the Phan-Thien–Tanner model with due account for the near-wall layer depleted of macromolecules. This skimming layer is wider than the electric double layer (EDL) and leads to an enhanced flow rate relative to that of the corresponding uniform concentration flow case. The derived solution allows a detailed investigation of the flow characteristics due to the combined effects of fluid rheology, forcing strengths ratio, skimming layer thickness and relative rheology of the two fluids. In particular, when the EDL is much thinner than the skimming layer and simultaneously the viscosity of the Newtonian fluid inside this layer is much lower than that of the fluid outside, the flow is dominated by the characteristics of the Newtonian fluid. Outside these conditions, proper account of the various fluid layers and their properties must be considered for an accurate prediction of the flow characteristics. The analytical solution remains valid for the flow driven by a pressure gradient and its streaming potential, which is determined in the appendix.     

Uncovering ITIL claims: IT executives�� perception on benefits and Business-IT alignment

Over 45% of companies are estimated to use IT Service Management (ITSM) frameworks, yet, these frameworks can be imitated and hence the competitive advantage gained from these will quickly become obsolete. Therefore, research on the benefits of ITSM must focus on both operational and strategic benefits. An international survey of 441 firms was conducted to examine the benefits that IT Infrastructure Library (ITIL), the de-facto ITSM framework, provided to the IT organizations. The research focused on how (1) operational benefits, and, (2) strategic positioning of the IT organizations, specifically how the perceived level of Business-IT alignment maturity evolved as the adoption of ITIL increased. Results indicate that as the adoption of ITIL increased, the number of realized operational benefits increased, as well as the levels of maturity of the Business-IT alignment. This indicates that the further the implementation of ITIL the greater the operational and strategic benefits to the organization. Implications for practitioners and researchers are also discussed.     

On �� 2 ? �� 2-products of automata

Two equivalent sufficient conditions are given for the completeness of classes of finite automata with respect to the isomorphic simulation under the ?? ₂ ? ?? ₂-product. It is conjectured that these conditions are also necessary with respect to the isomorphic or homomorphic simulation too.     

Searle��s wager

Nicholas Agar has recently argued that it would be irrational for future human beings to choose to radically enhance themselves by uploading their minds onto computers. Utilizing Searle’s argument that machines cannot think, he claims that uploading might entail death. He grants that Searle’s argument is controversial, but he claims, so long as there is a non-zero probability that uploading entails death, uploading is irrational. I argue that Agar’s argument, like Pascal’s wager on which it is modelled, fails, because the principle that we (or future agents) ought to avoid actions that might entail death is not action guiding. Too many actions fall under its scope for the principle to be plausible. I also argue that the probability that uploading entails death is likely to be lower than Agar recognizes.     

Neural network training based on FPGA with floating point number format and it��s performance

In this paper, two-layered feed forward artificial neural network’s (ANN) training by back propagation and its implementation on FPGA (field programmable gate array) using floating point number format with different bit lengths are remarked based on EX-OR problem. In the study, being suitable with the parallel data-processing specification on ANN’s nature, it is especially ensured to realize ANN training operations parallel over FPGA. On the training, Virtex2vp30 chip of Xilinx FPGA family is used. The network created on FPGA is coded by using VHDL. By comparing the results to available literature, the technique developed here proved to consume less space for the subjected ANN training which has the same structure and bit length, it is shown to have better performance.     

Phasen der SOA-Einf��hrung

The paper argues that attitudes to SOA follow a typical hype cycle from Technological Trigger, Peak of Inflated Expectations, and a Trough of Disillusionment to the more recent realization that SOA is a concept that may offer certain benefits but has several limitations. The main research question studies how the attitude to SOA changes in various phases of the hype cycle, how the SOA implementation cycle and an increase in business process maturity (BPMa) are interconnected and which factors influence the transition between the hype cycle phases. The paper shows that an organization??s success with implementing SOA depends on its ability to match the SOA implementation with an increase in BPMa. The dual purpose of implementing SOA is shown in the first framework: to assure the coherence of IT assets and to assure business/IT alignment. In the second framework, the interconnection of SOA and BPMa and its role in transiting through the hype cycle phases is outlined. The findings are analyzed using a longitudinal case study of a large Slovenian company.     

Interpolation in Valiant��s Theory

We investigate the following question: if a polynomial can be evaluated at rational points by a polynomial-time boolean algorithm, does it have a polynomial-size arithmetic circuit? We argue that this question is certainly difficult. Answering it negatively would indeed imply that the constant-free versions of the algebraic complexity classes VP and VNP defined by Valiant are different. Answering this question positively would imply a transfer theorem from boolean to algebraic complexity.     

Thomas Jefferson��s Poplar Forest

A unique geometric construction known to Thomas Jefferson reveals a rich interplay of root-two geometric elements when applied to Jefferson’s octagonal plan of Poplar Forest, his eighteenth-century villa retreat.     

Produktdifferenzierung f��r?Software-as-a-Service-Anbieter

The market for the new provisioning type Software-as-a-Service (SaaS) has reached a significant size and still shows enormous growth rates. By varying size of SaaS products, providers can improve their market position and profits by successfully acting in the tension area of customer acquisition, pricing and costs. We first elaborate differences concerning product differentiation between classic software provisioning models and SaaS. Then, we introduce a micro-economic based decision model to maximize the return of a provider by finding an optimal granularity, i.e. by varying the size of services. This paper makes two contributions in this context: (1) it provides a conceptual foundation for product differentiation within the scope of SaaS and (2) it presents the first implementation of variable reproduction costs for web based software offers. The model is illustrated by a real world case with data from a SaaS provider.     

Are two heads always better than one? Differential effects of collaboration on students�� computer-supported learning in mathematics

While some studies found positive effects of collaboration on student learning in mathematics, others found none or even negative effects. This study evaluates whether the varying impact of collaboration can be explained by differences in the type of knowledge that is promoted by the instruction. If the instructional material requires students to reason with mathematical concepts, collaboration may increase students’ learning outcome as it promotes mutual elaboration. If, however, the instructional material is focused on practicing procedures, collaboration may result in task distribution and thus reduce practice opportunities necessary for procedural skill fluency. To evaluate differential influences of collaboration, we compared four conditions: individual vs. collaborative learning with conceptual instructional material, and individual vs. collaborative learning with procedural instructional material. The instruction was computer-supported and provided adaptive feedback. We analyzed the effect of the conditions on several levels: Logfiles of students’ problem-solving actions and video-recordings enabled a detailed analysis of performance and learning processes during instruction. In addition, a post-test assessed individual knowledge acquisition. We found that collaboration improved performance during the learning phase in both the conceptual and the procedural condition; however, conceptual and procedural material had a differential effect on the quality of student collaboration: Conceptual material promoted mutual elaboration; procedural material promoted task distribution and ineffective learning behaviors. Consequently, collaboration positively influenced conceptual knowledge acquisition, while no positive effect on procedural knowledge acquisition was found. We discuss limitations of our study, address methodological implications, and suggest practical implications for the school context.     

Influence of surface condition on wear behavior of ��PIM mould inserts made of tool steel and cemented carbide

Mould inserts made of low alloyed tool steel and cemented carbide were tested using a laboratory tribometer simulating micro powder injection moulding (μPIM) to characterize the influence of surface condition due to different machining (micro milling or electrical discharge machining) and finishing (ultrasonic wet peening or abrasive micro peening) processes on wear in contact with ceramic feedstocks of different composition. Results show that abrasive micro peening is a suitable finishing process to ensure an excellent wear resistance of EDM processed mould inserts made from ultrafine cemented carbide even in contact with alumina feedstock of high abrasiveness. Ultrasonic wet peening on the other hand allows effective deburring and smoothing of relatively soft steel surfaces after micro milling.     

A study on key strategies in P2P file sharing systems and ISPs�� P2P traffic management

The flourish of P2P systems draws a lot of attention of networking researchers. Some research efforts focus on P2P systems, trying to understand the mechanism of various implementations and the behavior pattern of P2P users, and then improve the systems?? performance. Others look at the issue from the angle of ISPs, trying to help ISPs solve various issues brought by P2P applications. In this article, we conduct a review study on recent research efforts in these two areas. The first part of this article focuses on several key strategies that have significant influence on the performance of P2P systems. In the second part, we review some important techniques for ISPs to manage P2P traffic, i.e., blocking, caching and localization, and compare their advantages and disadvantages.     

Requirements Engineering f��r Product Service Systems

In recent years, manufacturing companies and service providers have moved towards offering customer-specific problem solutions. These integrated bundles usually consist of hardware, software, and service components and are called product service systems (PSS) or hybrid products. Since the success of the resulting solution depends on the understanding of all requirements, requirements engineering (RE) has become a key factor. The article analyzes the state of the art of RE for PSS based on an extensive literature review in the domains of product-, software-, and service engineering. For this, criteria are derived from the characteristics of PSS and from the task area of RE in the life cycle of PSS. Based on these criteria we analyze the most established RE approaches for their suitability for PSS. An important finding is that integrated/interdisciplinary approaches for RE are missing. Moreover, the maturity of RE approaches in the three domains varies significantly. All analyzed approaches heavily rely on concepts and solution characteristics of their own domain so that a transfer to other domains is hardly possible. This literature review lays the foundation for successful RE for PSS and especially for future research aiming at combining and integrating RE approaches and models of product-, software-, and service engineering. Such requirement models could connect concepts of single domains and enable an integrated and seamless RE for PSS.     

Kritische Erfolgsfaktoren f��r die Gestaltung serviceorientierter Informationssysteme

Service orientation has been a major buzz-word in recent years. While the buzz is on a decline, organizations are slowly, but steadily moving towards service oriented designs. However, service orientation turns out to be as much of a managerial challenge as of a technical one. The most important complexity drivers in the service oriented design of information systems seem to be (a) inconsistent design goals of stakeholders and (b) the pursuit of exhaustive service orientation coverage. This research focuses on the following two questions: (1) What are the characteristics of successful implementations of service oriented information systems, and (2) what are the critical success factors influencing, driving and/or determining these characteristics? Data of an empirical analysis is used to test a set of cause-effect relationship hypotheses based on nine latent variables. In the core of this model we differentiate the variables ??overall service orientation infrastructure success?? and ??service orientation project success??. The hypothesized interrelationships between the nine variables lead to a causal model which is proven to hold.