Adding Value to Data

Today's rapidly changing, global, competitive business environment requires that an enterprise optimize its operations and leverage its data, information, and knowledge resources better than ever before. the result is an ever-increasing demand for data, information, and knowledge about the enterprise, its operations, and about its customers, suppliers, and business partners. the database management system is the key component of the information systems infrastructure of the modern enterprise that is focused on meeting this demand. the database management system is an organized store of the enterprise' data that provides ever-increasing capabilities for adding value to data by turning data into information; by turning this information into knowledge; and by sharing data, information, and knowledge securely throughout the enterprise.     

Study of ceramic pebble beds in Post Irradiation Examination of the Pebble Bed Assemblies irradiation experiment

The irradiation experiment Pebble Bed Assemblies (PBA) consists of four mock-up representations (test elements) of the EU Helium Cooled Pebble Bed (HCPB) concept. The four test elements contain a ceramic breeder pebble bed sandwiched between two beryllium pebble beds and are regarded as one of the first DEMO representative HCPB blanket irradiation tests, with respect to temperatures and power densities. The design value of the PBA were to irradiate pebble beds at a power density of 20–26 W/cc in the ceramic breeder, to a maximum temperature of 800 °C.Two test elements contain lithium orthosilicate pebbles (Li₄SiO₄; FZK/KIT) and were irradiated with target temperatures of 600 and 800 °C, respectively. The other test elements have lithium metatitanate (Li₂TiO₃; CEA) with different grain sizes and were both irradiated with a target temperature of 800 °C. The PBA have been irradiated for 294 Full Power Days (12 cycles) in the High Flux Reactor (HFR) in Petten to a total neutron dose of 2–3 dpa in Eurofer, and an estimated (total) lithium burnup of 2–3% in the ceramic pebbles.This work presents results of Post Irradiation Examinations (PIE) on the four HCPB test elements. Using e.g. SEM, the evolution of compressed pebble beds and pebble interactions like swelling, creep, sintering, etc., under irradiation and thermal loads are studied for the candidate pebble materials Li₂TiO₃ and Li₄SiO₄. (Chemical) interactions between ceramic pebbles and Eurofer (e.g. chrome diffusion) are observed. Looking at different sections of the pebble beds, correlations between temperatures and thermal–mechanical behaviour are clearly observed.     

Algorithmic Aspects of Proportional Symbol Maps

Proportional symbol maps visualize numerical data associated with point locations by placing a scaled symbol—typically an opaque disk or square—at the corresponding point on a map. The area of each symbol is proportional to the numerical value associated with its location. Every visually meaningful proportional symbol map will contain at least some overlapping symbols. These need to be drawn in such a way that the user can still judge their relative sizes accurately.     

A Model-based Integration and Testing Method to Reduce System Development Effort

New methods and techniques are needed to reduce the very costly integration and test effort (in terms of lead time, costs, resources) in the development of high-tech multi-disciplinary systems. To facilitate this effort reduction, we propose a method called model-based integration. This method allows to integrate formal executable models of system components that are not yet physically realized with available realizations of other components. The combination of models and realizations is then used for early analysis of the integrated system by means of validation, verification, and testing. This analysis enables early detection and prevention of problems that would otherwise occur during real integration, resulting in a significant reduction of effort invested in the the real integration and test phases. This paper illustrates how models of components, developed for model-based integration, can be used for automated model-based testing, which allows time-efficient determination of the conformance of component realizations with respect to their requirements. The combination of model-based integration and model-based testing is practically illustrated in a realistic industrial case study. Results obtained from this study encourage further research on model-based integration as a prominent method to reduce the integration and test effort.     

Cognitive task analysis and innovation of training: the case of structured troubleshooting

Troubleshooting is often a time-consuming and difficult activity. The question of how the training of novice technicians can be improved was the starting point of the research described in this article. A cognitive task analysis was carried out consisting of two preliminary observational studies on troubleshooting in naturalistic settings, combined with an interpretation of the data obtained in the context of the existing literature. On the basis of this cognitive task analysis, a new method for the training of troubleshooting was developed (structured troubleshooting), which combines a domain-independent strategy for troubleshooting with a context-dependent, multiple-level, functional decomposition of systems. This method has been systematically evaluated for its use in training. The results show that technicians trained in structured troubleshooting solve twice as many malfunctions, in less time, than those trained in the traditional way. Moreover, structured troubleshooting can be taught in less time than can traditional troubleshooting. Finally, technicians learn to troubleshoot in an explicit and uniform way. These advantages of structured troubleshooting ultimately lead to a reduction in training and troubleshooting costs.     

A novel spike distance

The discrimination between two spike trains is a fundamental problem for both experimentalists and the nervous system itself. We introduce a measure for the distance between two spike trains. The distance has a time constant as a parameter. Depending on this parameter, the distance interpolates between a coincidence detector and a rate difference counter. The dependence of the distance on noise is studied with an integrate-and-fire model. For an intermediate range of the time constants, the distance depends linearly on the noise. This property can be used to determine the intrinsic noise of a neuron.     

Identifying multiple roles of ICT coordinators

This study reports on the development and validation of measurement scales to study the different roles fulfilled by ICT coordinators. Based on a review of the literature, a 24 item questionnaire was constructed and administered to a sample of 177 Flemish ICT coordinators working in primary education. Exploratory factor analysis revealed a four-factor solution: the ICT coordinator as a planner, a budgeter, a technician, and an educationalist. Qualitative data corroborated these roles. This study provides a quantitative measure of the different roles assumed by ICT coordinators in practice. The implications of our findings for schools, researchers and policy makers are discussed.     

Analysis of Restart Mechanisms in Software Systems

Restarts or retries are a common phenomenon in computing systems, for instance, in preventive maintenance, software rejuvenation, or when a failure is suspected. Typically, one sets a time-out to trigger the restart. We analyze and optimize time-out strategies for scenarios in which the expected required remaining time of a task is not always decreasing with the time invested in it. Examples of such tasks include the download of Web pages, randomized algorithms, distributed queries, and jobs subject to network or other failures. Assuming the independence of the completion time of successive tries, we derive computationally attractive expressions for the moments of the completion time, as well as for the probability that a task is able to meet a deadline. These expressions facilitate efficient algorithms to compute optimal restart strategies and are promising candidates for pragmatic online optimization of restart timers     

Effects of constructing versus playing an educational game on student motivation and deep learning strategy use

In this study the effects of two different interactive learning tasks, in which simple games were included were described with respect to student motivation and deep strategy use. The research involved 235 students from four elementary schools in The Netherlands. One group of students (N = 128) constructed their own memory ‘drag and drop’ game, whereas the other group (N = 107) played an existing ‘drag and drop’ memory game. Analyses of covariance demonstrated a significant difference between the two conditions both on intrinsic motivation and deep strategy use. The large effect sizes for both motivation and deep strategy use were in favour of the construction condition. The results suggest that constructing a game might be a better way to enhance student motivation and deep learning than playing an existing game. Despite the promising results, the low level of complexity of the games used is a study limitation.     

Interpreting the change detection error matrix

Two different matrices are commonly reported in assessment of change detection accuracy: (1) single date error matrices and (2) binary change/no change error matrices. The third, less common form of reporting, is the transition error matrix. This paper discuses the relation between these matrices. First, it is shown that the transition error matrix implicitly measures temporal correlation in classification errors. Based on two assumptions (no correlation, maximum correlation), the single date error matrices can be used to obtain a most pessimistic and most optimistic estimate of the transition accuracy. Next, it is shown that the change/no change error matrix does not quantify certain classification errors. It is shown that change/no change error matrix can be used complementary to the full transition error matrix in efforts to improve transition detection accuracy. Despite its advantages, the transition error matrix is only very rarely reported, while it is of interest to all those interested in the accuracy of transitions (from-to) in change detection.