l2-l∞ Control for Sampled-data Systems with Packet Dropout: Switched System Method

International Journal of Control, Automation and Systems - In this paper, the problem of l2-l∞ control is investigated for the sampled-data systems including packet dropout. The sampled-data...     

Fast Finite-time H∞ Control for a Class of p-normal Form Nonlinear Systems with Output Constraint and Its Application

International Journal of Control, Automation and Systems - In this paper, the fast finite-time H∞, stabilization problem with output constraint is studied for a class of p-normal form...     

The Local Discontinuous Galerkin Method for the Fourth-Order Euler–Bernoulli Partial Differential Equation in One Space Dimension. Part II: A Posteriori Error Estimation

In this paper new a posteriori error estimates for the local discontinuous Galerkin (LDG) method for one-dimensional fourth-order Euler–Bernoulli partial differential equation are presented and analyzed. These error estimates are computationally simple and are obtained by solving a local steady problem with no boundary condition on each element. We use the optimal error estimates and the superconvergence results proved in Part I to show that the significant parts of the discretization errors for the LDG solution and its spatial derivatives (up to third order) are proportional to \((k+1)\) -degree Radau polynomials, when polynomials of total degree not exceeding \(k\) are used. These results allow us to prove that the \(k\) -degree LDG solution and its derivatives are \(\mathcal O (h^{k+3/2})\) superconvergent at the roots of \((k+1)\) -degree Radau polynomials. We use these results to construct asymptotically exact a posteriori error estimates. We further apply the results proved in Part I to prove that, for smooth solutions, these a posteriori LDG error estimates for the solution and its spatial derivatives at a fixed time \(t\) converge to the true errors at \(\mathcal O (h^{k+5/4})\) rate. We also prove that the global effectivity indices, for the solution and its derivatives up to third order, in the \(L^2\) -norm converge to unity at \(\mathcal O (h^{1/2})\) rate. Our proofs are valid for arbitrary regular meshes and for \(P^k\) polynomials with \(k\ge 1\) , and for periodic and other classical mixed boundary conditions. Our computational results indicate that the observed numerical convergence rates are higher than the theoretical rates. Finally, we present a local adaptive procedure that makes use of our local a posteriori error estimate.     

An Online Algorithm for a Problem in Scheduling with?Set-ups?and Release Times

We address the problem of sequential single machine scheduling of jobs with release times, where jobs are classified into types, and the machine must be properly configured to handle jobs of a given type. The objective is to minimize the maximum flow time (time from release until completion) of any job. We consider this problem under the assumptions of sequence independent set-up times and item availability with the objective of minimizing the maximum flow time. We present an online algorithm that is O(1)-competitive, that is, always gets within a constant factor of optimal. We also show that exact offline optimization of maximum flow time is NP-hard.     

Robust Mixed H2/H∞ Control for An Uncertain Wireless Sensor Network Systems with Time Delay and Packet Loss

In this paper, the problem of robust mixed H₂/H_∞ control is studied for an uncertain wireless sensor network (WSN) systems with random time delay, packet loss and sensor faults. A system model is established based on the characteristics of uncertain time delay and packet loss in WSN. In this model, system uncertainties are represented by random time delay and stochastic packet loss, which are described by a Markov chain. By using a Lyapunov-Krasovskii function, a mode-dependent mixed H₂/H_∞ controller is designed to guarantee both the stochastic stability of the closed-loop system and the prescribed H₂, H_∞ control performances. The sufficient conditions for the existence of the controller are proved by a series of Linear Matrix Inequalities (LMIs). If these LMIs are feasible, the mode-dependent mixed H₂/H_∞ controller can be obtained. Matlab LMI toolbox is used to calculate the control law. Finally, a numerical example and its simulation results demonstrated the effectiveness of the proposed method.

     

Selecting users for participation in IT projects: Trading a representative sample for advocates and champions?

The selection of users for participation in IT projects involves trade-offs between multiple criteria, one of which is selecting a representative cross-section of users. This criterion is basic because trading it for other criteria means basing designs on information biased toward some user groups at the expense of others. Based on interviews in development and customer organizations we find that their criteria for user selection favor persons who can contribute to the progress of the IT project over persons who are representative of the full range of users. A highly valued contribution from participating users is the ability to advocate a vision for the system and champion its organizational implementation. A survey in one customer organization shows that respondents’ personal traits explain up to 31% of the variation in their experience of aspects of the usability of a recently introduced system. Thus, unless participating users are representative as to these personal traits, IT projects may, inadvertently, bring about systems that will fail to satisfy many users.     

Can ICT enhance workplace inclusion? ICT-enabled workplace inclusion practices and a new agenda for inclusion research in Information Systems

Workplace inclusion is a strategic concern for organizations, yet challenging to achieve. We investigate how Information and Communications Technology (ICT) use can enhance workplace inclusion. Based on qualitative data collected from a leading UK organization, we conceptualize four ICT-enabled workplace inclusion practices – Expanding, Orienting, Enculturating, and Reflecting. Each practice entails the use of multiple ICT applications to enhance workplace inclusion through a distinct set of organizational activities. We also highlight the Reflecting practice as key in enhancing other practices. Drawing from our findings, we develop a framework for ICT-enabled workplace inclusion that constitutes inter-related ICT-enabled practices focused on multiple organizational activities. We contribute to the literature on the strategic role of ICT for organizational/social good, a current area of research priority for the information systems discipline.     

Adaptive χ2 Test for Discriminating between Close Hypotheses with a Large Number of Classes and Its Application to Some Cryptography Problems

The main problem considered consists in testing the hypothesis H ₀ that letters of an alphabet A = a ₁, a ₂, . . ., a _k are generated with equal probabilities 1/k against the alternative complex hypothesis H ₁, the negation of H ₀. In many applications, in particular, those connected with cryptography, k is large, but possible deviations from the uniform distribution are small. Therefore, application of Pearson's ² test, which is one of the most wide-spread and efficient tests, requires samples of a very large size, certainly exceeding k. We propose a so-called adaptive ² test, whose power can be considerably higher than that of the traditional method in the case described. This conclusion is based on the theoretical analysis of the proposed criterion for some classes of alternatives as well as on experimental results related to discriminating between enciphered Russian texts and random sequences.     

Workplace assessment: a tool for occupational health and safety management in small firms?

This paper discusses the capability of small firms to comply with legislative demands on risk assessment. The results of a national survey show that only a minor fraction of small firms comply. Two case studies demonstrate that small firms are able to meet the demands. An analysis of these cases leads to some hypotheses on the preconditions for compliance. Many firms need a person to mediate legislative demands. The demands for qualifications to fulfil this role are discussed. The conclusion is that it is possible to qualify persons as mediators. Therefore, to stimulate ergonomic activities in small firms resources for such mediators are required. The occupational health services are able to train a staff to undertake the task.     

Mobile computers in a community NHS trust: Is this a relevant context and environment for their use?

This paper describes a case study in which mobile computers were used by a UK National Health Service (NHS) Trust. The intention was to give clinicians access to up-to-date patient data, enabling them to be more clinically effective in their jobs. Since the majority of their work was performed in the community, it was perceived that the use of hand-held computers would give the flexibility needed to allow this clinical effectiveness to occur. This paper will attempt to demonstrate what happened in reality and point to various factors that had not been considered prior to the introduction of the system. Had these factors been considered, a different system would have been designed with a better fit between the organisation, the needs of the user and their work environment.     

Drivers' and non-drivers' performance in a change detection task with static driving scenes: is there a benefit of experience?

The ‘looked-but-failed-to-see’ phenomenon is crucial to driving safety. Previous research utilising change detection tasks related to driving has reported inconsistent effects of driver experience on the ability to detect changes in static driving scenes. Reviewing these conflicting results, we suggest that drivers' increased ability to detect changes will only appear when the task requires a pattern of visual attention distribution typical of actual driving. By adding a distant fixation point on the road image, we developed a modified change blindness paradigm and measured detection performance of drivers and non-drivers. Drivers performed better than non-drivers only in scenes with a fixation point. Furthermore, experience effect interacted with the location of the change and the relevance of the change to driving. These results suggest that learning associated with driving experience reflects increased skill in the efficient distribution of visual attention across both the central focus area and peripheral objects.     

Concept maps: A useful and usable tool for computer-based knowledge assessment? A literature review with a focus on usability

The concept map is now widely accepted as an instrument for the assessment of conceptual knowledge and is increasingly being embedded into technology-based environments. Usability addresses how appropriate (for a particular use) or how user-friendly a computer-based assessment instrument is. As we know from human-computer interaction research, if the interface is not user-friendly, a computer-based assessment can result in decreased test performance and reduced validity. This means that the usability of the interface affects the assessment in such a way that if the test is not user-friendly, then the test taker will not be able to fully demonstrate his/her level of proficiency and will instead be scored according to his/her information and communication technology (ICT) literacy skills. The guidelines of the International Test Commission (2006) require usability testing for such instruments and suggest that design standards be implemented. However, we do not know whether computer-conducted concept map assessments fulfill these standards. The present paper addresses this aspect. We conducted a systematic research review to examine whether and how researchers have studied and considered usability when conducting computer-based concept map assessments. Only 24 out of 119 journal articles that assessed computer-based concept maps discussed the usability issue in some way. Nevertheless, our review brings to light the idea that the impact of usability on computer-based concept map assessments is an issue that has received insufficient attention. In addition, usability ensures a suitable interaction between test taker and test device; thus, the training effort required for test use can be reduced if a test's usability is straight forward. Our literature review, however, illustrates that the interplay between usability and test use training has mostly been neglected in current studies.     

Can we predict success from log data in VLEs? Classification of interactions for learning analytics and their relation with performance in VLE-supported F2F and online learning

Learning analytics is the analysis of electronic learning data which allows teachers, course designers and administrators of virtual learning environments to search for unobserved patterns and underlying information in learning processes. The main aim of learning analytics is to improve learning outcomes and the overall learning process in electronic learning virtual classrooms and computer-supported education. The most basic unit of learning data in virtual learning environments for learning analytics is the interaction, but there is no consensus yet on which interactions are relevant for effective learning. Drawing upon extant literature, this research defines three system-independent classifications of interactions and evaluates the relation of their components with academic performance across two different learning modalities: virtual learning environment (VLE) supported face-to-face (F2F) and online learning. In order to do so, we performed an empirical study with data from six online and two VLE-supported F2F courses. Data extraction and analysis required the development of an ad hoc tool based on the proposed interaction classification. The main finding from this research is that, for each classification, there is a relation between some type of interactions and academic performance in online courses, whereas this relation is non-significant in the case of VLE-supported F2F courses. Implications for theory and practice are discussed next.     

Industrial Designers: Are You Ready for Foreign Markets? Assessing Designer Confidence and Prediction Accuracy in a Transnational Marketing Context

In order to boost sales in foreign markets and compete with emerging local competitors, global companies from developed countries are realizing that they need to develop products specifically for the local markets. Meanwhile, companies in developing nations are building up their design staff and seeking to establish their own global brands. This recent growth in design activity targeting overseas markets suggests the need for academic research to better understand the phenomenon of design expertise transfer across national borders. The present research explores industrial designers' expertise transfer across cultures with respect to knowledge calibration. Based on the literature on expertise and Shanteau's theory of expert competence, several hypotheses are developed regarding the main effect of culture, and the interaction between culture and expertise level, on design confidence and prediction accuracy. A three‐phase experimental study is conducted to test the hypotheses. Results suggest that both expert designers and non‐expert designers are poorly calibrated and overconfident. Nonetheless, expert designers are better calibrated when designing products for a foreign market than for their home market. Theoretical and managerial implications are discussed.     

Robotic assistants in therapy and education of children with autism: can a small humanoid robot help encourage social interaction skills?

This article presents a longitudinal study with four children with autism, who were exposed to a humanoid robot over a period of several months. The longitudinal approach allowed the children time to explore the space of robot–human, as well as human–human interaction. Based on the video material documenting the interactions, a quantitative and qualitative analysis was conducted. The quantitative analysis showed an increase in duration of pre-defined behaviours towards the later trials. A qualitative analysis of the video data, observing the childrens activities in their interactional context, revealed further aspects of social interaction skills (imitation, turn-taking and role-switch) and communicative competence that the children showed. The results clearly demonstrate the need for, and benefits of, long-term studies in order to reveal the full potential of robots in the therapy and education of children with autism.

Integrating cluster and sequential analysis to explore learners’ flow and behavioral patterns in a simulation game with situated-learning context for science courses: A video-based process exploration

Much emphasis has been placed on the research on applying digital games in science education. Among the studies, the advantages and limitations of role-playing simulation games deserve further exploration. However, existing analyses of the behavioral patterns of role-playing simulation games in science education remain substantially lacking, particularly the integration of diverse behavioral pattern analysis methods. This study thus seeks to analyze the videotaped learning process of 86 college students in game-based learning activities that utilize a role-playing simulation game. This study used the integrated method of sequential analysis and cluster analysis and explored the learners’ flow state and learning behavioral patterns. The results show that the use of integrated behavioral pattern analysis helps to explore the traits and limitations of role-playing simulation games in science education as well as learners’ reflective behavior patterns.This study identifies a wide variety of learning behavior patterns from three potential clusters of learners and then discusses the learning process of each cluster. The different levels of flow experienced by the learners affected their learning behavior patterns; learners with higher levels of flow demonstrated a more in-depth reflective process. The study further discusses the results of these analyses and makes relevant recommendations for the systems development of the games, its educational applications, and evaluation methods.