WTR: A Reputation Metric for Distributed Hash Tables Based on a Risk and Credibility Factor

The growing number of popular peer to peer applications during the last five years has implied for researchers to focus on how to build trust in such very large scale distributed systems. Reputation systems have shown to be a very good solution to build trust in presence of malicious nodes. We propose in this paper a new metric for reputation systems on top of a Distributed Hash Table that uses a notion of risk to make the applications aware of certain behaviours of malicious nodes. We show that our metric is able to significantly reduce the number of malicious transactions, and that it also provides very strong resistance to several traditional attacks of reputations systems. We also show that our solution can easily scale, and can be adapted to various Distributed Hash Tables.     

A system approach to information system: Design for a city planning agency

Information system design forms the most vital element in designing an organization. An information system for a city planning agency is a combination of people, computer hardware and software, a dynamic data base and a set of generalized interactive algorithms.City planning agencies require complete and current information in order to provide input into municipal government decision process. This paper presents a model for an information system based on the operational functions of various city departments. The emphasis of this paper is on system engineering considerations and there is no attempt to provide a detailed programming solution. Basic considerations include: operational requirements, planning requirements, political environment and level of computer expertise. The basic components of the model are an on-line interactive system with a data-base shared by the participating departments.     

A disaster for everyone to see: An interpretive analysis of a failed is project

The New Zealand Education Department attempted to implement a centralized payroll system in 1989. The difficulties that the department experienced were broadcast on national radio and television and publicised on the front page of The New Zealand Herald. In the end, the centralized payroll system was scrapped by the government.This paper examines this case study using the critical hermeneutics of Gadamer and Ricoeuer. Critical hermeneutics, as an integrative theoretical framework, combines both framework, combines both interpretive and critical element, and addresses those social and organizational issues, which are key to the successful implementation of information systems. This paper suggests critical hermeneutics as a conceptual foundation for information systems implementation research.     

Design for test and time to market: a personal perspective

This article explores design for test implementation alternatives and electronic design for test automation's effects on overall time to market     

A Geometric Approach to Solving Problems of Control Constraints: Theory and a DAE Framework

The paper deals with controlled mechanical systems in which the number of control inputs is equal to the number of desired system outputs, and is smaller than the number of degrees of freedom of the system. The determination of control input strategy that force the underactuated system to complete the partly specified motion is a challenging problem. In the present formulation, the outputs (performance goals), expressed in terms of system states, are treated as constraints on the system—called control or program constraints as distinct from contact constraints in the classical sense, and a mathematical resemblance of the inverse control problem to the constrained system dynamics is exploited. However, while the reactions of contact constraints act in the directions orthogonal to the respective constraint manifold, the available control reactions may have arbitrary directions with respect to the program constraint manifold, and in the extreme may be tangent. A specific methodology must then be developed to find the solution of such singular problems, related to a class of control tracking problems such as position control of elastic joint robots, control of cranes, and aircraft control in prescribed trajectory flight. The governing equations of the problem arise as a set of differential-algebraic equations (DAEs), and an effective method for solving the DAEs, based on backward Euler method, is proposed. The open-loop control formulation obtained this way is then extended by a closed-loop control law to provide stable tracking of the required reference trajectories in the presence of perturbations. Some examples of applications of the theory and results of numerical simulations are reported.     

ACTAS : A System Design for Associative and Commutative Tree Automata Theory

ACTAS is an integrated system for manipulating associative and commutative tree automata (AC-tree automata for short), that has various functions such as for Boolean operations of AC-tree automata, computing rewrite descendants, and solving emptiness and membership problems. In order to deal with high-complexity problems in reasonable time, over- and under-approximation algorithms are also equipped. Such functionality enables us automated verification of safety property in infinite state models, that is helpful in the domain of, e.g. network security, in particular, for security problems of cryptographic protocols allowing an equational property. In runtime of model construction, a tool support for analysis of state space expansion is provided. The intermediate status of the computation is displayed in numerical data table, and also the line graphs are generated. Besides, a graphical user interface of the system provides us a user-friendly environment for handy use.     

A simple algorithm for the mapping of TIN data onto a static grid: Applied to the stratigraphic simulation of river meander deposits

Triangulated irregular networks (TIN) in landscape evolution models have the advantage of representing geologic processes that involve a horizontal component, such as faulting and river meandering, due to their adaptive remeshing capability of moving, adding and deleting nodes. However, the moving node feature is difficult to integrate with the accumulation of a three-dimensional (3D) subsurface stratigraphy, because it requires 3D subsurface interpolation, which results in stratigraphic data loss due to heterogeneity of the subsurface and averaging effects. We present a simple algorithm that maps any changes in the configuration of TIN landscape nodes onto a static grid, facilitating the creation of a fixed stratigraphic record of TIN surface change. The algorithm provides a practical solution not only for the stratigraphic problem, but also for other problems that involve linking of models that use TIN and raster discretization schemes. An example application is presented using the river meandering module incorporated in the CHILD landscape evolution model. Examples are shown of cross-sections, and voxel distributions and geo-archaeological depth–age maps. These illustrate the type of insights that can be obtained from process-based modeling of subsurface fluvial architecture, and highlight potential applications of stratigraphic simulation.     

It is best to point for young children: a comparison of children's pointing and dragging

A mouse is the input device children principally use to control a computer in schools. However, somewhat surprisingly, there has been very little research investigating the appropriate mouse control strategies for children. In this paper we report two studies which compared children's performance with two basic mouse operations; pointing and dragging. In Study 1 we investigated 7-year-old children (n=24) who were inexperienced with a computer mouse and found that they were quicker and more accurate with pointing compared to dragging. In Study 2 we examined the performance of children (n=90) from three different age groups: young (5–6 years), medium (8–9 years), and older (11–12 years). These children were more experienced with using a mouse. We found that older children were quicker and made fewer errors than younger children regardless of the mouse operation. We also found that younger children were slower and made more errors with dragging than with pointing. There were no differences in performance between pointing and dragging for the other two age groups. The implications of these findings for the design of interfaces for children are discussed.     

Adaptive PD-controller for positioning of a remotely operated vehicle close to an underwater structure: Theory and experiments

The requirement for high accuracy in dynamic positioning of remotely operated vehicles (ROV), especially when tasks close to underwater structures have to be performed, demands high precision of sensor systems. Taut-wire and passive arm systems can satisfy this demand in measuring ROVs positions and orientations relative to a structure. However, the main drawback of these sensor systems is that additional forces act on ROVs due to the mechanical connection. In order to solve this problem, an adaptive PD controller is proposed and designed for dynamic positioning of ROVs working in close proximity of structures. Invoking the adaptation law, these additional forces caused by the passive arm and umbilical, and even by the uncertainties in gravity and buoyancy can be identified and compensated. By choosing an adequate Lyapunov candidate function, the system's stability is proven. The effectiveness of this design control method is demonstrated by means of numerical simulations and experiments.     

A Reference Architecture for provisioning of Tools as a Service: Meta-model,Ontologies and Design Elements

Software Architecture (SA) plays a critical role in designing, developing and evolving cloud-based platforms that can be used to provision different types of services for consumers on demand. In this paper, we present a Reference Architecture (RA) for designing cloud-based Tools as a service SPACE (TSPACE), which can provision a bundled suite of tools following the Software as a Service (SaaS) model. The reference architecture has been designed by leveraging information structuring approaches and by using well-known architecture design principles and patterns. The RA has been documented using view-based approach and has been presented in terms of its context, goals, the RA meta-model, information structuring and relationship models using ontologies and components of the RA. We have demonstrated the feasibility and applicability of the RA with the help of a prototype and have used the prototype to provision software architecting tools. We have also evaluated the RA in terms of effectiveness of the design decisions and the RA’s completeness and feasibility using scenario-based architecture evaluation method. The proposed TSPACE RA can provide valuable insights to information structure approaches and guidelines for designing and implementing TSPACE for various domains.     

Contouring Control for Multi‐Axis Motion Systems With Holonomic Constraints: Theory and Application to a Parallel System

In this paper, the contouring control problem for the constrained multi‐axis motion system is studied. The method of equivalent errors, previously proposed for unconstrained motion systems, is generalized to the system with holonomic constraints. It is shown that the method can be applied to the constrained system provided that the constraints satisfy a proper condition. Because of the constraints, the states in the control law are not completely independent. The unavailable states can be estimated using linear approximation from the constraint equations. As an illustrative example, the proposed method is applied to a parallel motion system with complicated dynamics. A contouring controller is designed using the method of equivalent errors incorporated with integral sliding mode control. Simulation results for contouring circular, elliptic, and square paths verify the effectiveness of the proposed method.     

A Resource Sharing System for Personal Computers in a LAN: Concepts, Design, and Experience

RM is an experimental prototype that supports the use of distributed services by personal computers in a LAN. Using a service request model, RM allows any PC on the LAN to offer and use services, which can be user-written or off-the-shelf applications. A user can start several activities that proceed concurrently and that use services offered by different machines. Program interfaces are provided for the development of distributed applications. Remote execution is supported within the service-request framework. The paper considers issues in resource sharing and discusses the choices that were made for RM. It provides an overview of RM concepts, design, and implementation, and reviews experience using the system.     

There is no such thing as a crisis: A critique of and alterative to the dominant crisis management model

In this Forum piece, I propose an alternative conceptual model, one that replaces the crisis event with the claim of urgency made by a leader as the focal unit of analysis. The proposed crisis‐as‐claim model insists that no claim of urgency is legitimate per se. From the perspective of the researcher, the crisis‐asclaim model reverses cause‐and effect from the event to the claim as independent variable. Finally, the crisis‐as‐claim model elides the consideration of heroic leadership so common in the crisis‐as‐event model, positioning instead leaders as claims makers always intent on advancing interests and enhancing power.     

A New Adaptive Explicit Nonlinear Model Predictive Control Design for a Nonlinear MIMO System: An Application to Twin Rotor MIMO System

This paper proposed an adaptive explicit nonlinear model predictive control (AENMPC) technique using multiple estimation models with a convex combination framework [18] for a class of nonlinear MIMO systems. Here, the explicit solution for the control signal is obtained from an optimal performance index which can be formulated without online optimization. In this work, a closed-form control law is developed by approximating the tracking error in the receding horizon by its Taylor series expansion. The control performance of any model-based control technologies explicitly depends on the quality of the unknown system parameters hence an adaptive parameter estimator is used to estimate the system parameter online [16,17]. To ensure the boundedness of the estimated parameter within a predefined compact region, a projection based adaptive law is used [43]. Using an aerodynamic laboratory set-up, known as the twin-rotor multi-input multi-output system (TRMS), the effectiveness of the proposed control algorithm has been verified. The complete state information of the system to the proposed adaptive controller is given from an extended Kalman filter based state observer. The performance of the proposed adaptive control algorithm has been verified successfully in simulations as well as real-time experimental setup of the TRMS model and compared with an existing control approach.

     

A Modular Platform for In-plane Ground Reaction Forces Detection in a Mouse Model: Design,Development and Verification

Movement and behavior analysis is a key research area in the domain of biomedical engineering and in many other medical research domains aiming at the understanding of physiological motor and cognitive basic mechanisms. The systematic application of robotic and mechatronic technologies to realize new tools and measurement methods for quantitatively assessing motor and cognitive functions in humans, as well as in animal models is gaining increasing popularity. This work represents a first step towards the development of a sensorized environment for behavioral phenotyping of animal models. In particular, this paper focuses on tremor analysis in Reeler mice, an emerging potential animal model for anatomical and behavioral traits observed in autism. Ground reaction force (GRF) sensing is indeed the most direct means of measuring tremor. Although force platforms have extensively been used for large-size animals, only a few attempts have been made to measure GRFs at a single paw for animals as small as mice or rats. Under the hypothesis that in-plane GRF components are directly connected to tremor, a small-size, modular, mechanically simple, two-axis force sensor for measuring the in-plane components of GRFs was designed and developed. Special care was paid to design a structure that allowed self-aligned assembly, for repeatability and modularity for combining multiple platforms for a sensorized floor. Preliminary testing was performed with both Reeler and wild-type mice. Fourier analysis validated the hypothesis of a direct connection between tremor and in-plane GRFs. Data analyzed and filtered highlight a peculiar spectrum frequency in Reeler mice tremor, centered around 21 Hz. This tremor, which was never quantitatively observed and measured before, is completely absent in wild-type mice.     

A cloudification methodology for multidimensional analysis: Implementation and application to a railway power simulator

Many scientific areas make extensive use of computer simulations to study complex real-world processes. These computations are typically very resource-intensive and present scalability issues as experiments get larger even in dedicated clusters, since these are limited by their own hardware resources. Cloud computing raises as an option to move forward into the ideal unlimited scalability by providing virtually infinite resources, yet applications must be adapted to this new paradigm. This process of converting and/or migrating an application and its data in order to make use of cloud computing is sometimes known as cloudifying the application. We propose a generalist cloudification method based in the MapReduce paradigm to migrate scientific simulations into the cloud to provide greater scalability. We analysed its viability by applying it to a real-world railway power consumption simulatior and running the resulting implementation on Hadoop YARN over Amazon EC2. Our tests show that the cloudified application is highly scalable and there is still a large margin to improve the theoretical model and its implementations, and also to extend it to a wider range of simulations. We also propose and evaluate a multidimensional analysis tool based on the cloudified application. It generates, executes and evaluates several experiments in parallel, for the same simulation kernel. The results we obtained indicate that out methodology is suitable for resource intensive simulations and multidimensional analysis, as it improves infrastructure’s utilization, efficiency and scalability when running many complex experiments.     

A fuzzy inference system for fault detection and isolation: Application to a fluid system

This work focuses on the design and implementation of a fuzzy inference system for fault detection and isolation (FDI) which can learn from example fault data, and the determination of a suitable optimisation strategy for the membership functions. A FDI system was developed which is based on adaptive fuzzy rules. A number of optimisation strategies were then applied; it was found that an evolutionary algorithm not only produced the best results but did so with relatively little processing effort and with excellent consistency.The adaptive fuzzy system, thus optimised, was tested against a neural network, which was trained to produce analogue outputs as an indication of fault magnitude. The fuzzy solution produced the best accuracy.We can conclude that an adaptive fuzzy inference system for FDI, using an evolutionary algorithm to learn from examples, can provide an accurate and readily comprehensible solution to diagnosing and evaluating fluid process plant faults.