VideoAcM: a transitive and temporal access control mechanism for collaborative video database production applications

Access control models play an important role in database management systems. In general, there are three basic access control models: Discretionary Access Control (DAC), Mandatory Access Control (MAC), and Non-Discretionary Access Control (NAC). Currently, the majority of commercial DBMSs provide only DAC, and some temporal access control models have been derived based on either DAC or NAC. In the context of video database applications, since the structure of video data is complex in nature, it requires a specific and tailor-made access control mechanism which should include MAC as well as DAC and NAC. However, only few efforts have been put on access control models for video database systems. In this paper, a transitive and temporal access control mechanism for collaborative video database production applications has been proposed, which subsumes the properties of DAC, MAC, and NAC. Moreover, our proposed mechanism is integrated with the intellectual property concerns by constructing an access control hierarchy of video data with authorization rules. In particular, our mechanism can derive novel authorization rules not only on conventional client-data access control, but also on data-data access control. Besides video data, the proposed model is applicable to other data types which exhibit a hierarchical data structure

Applying Dempster–Shafer theory for developing a flexible, accurate and interpretable classifier

Two approaches have traditionally been identified for developing artificial intelligence systems supporting decision-making: Machine Learning, which applies general techniques based on statistical analysis and optimization methods to extract information from a large amount of data looking for possible relations among them, and Expert Systems, which codify experts knowledge in rules, which are then applied to a specific situation. One of the main advantages of the first approach is its greater accuracy and wider generality for the application of the methods developed which can be used in various scenarios. By contrast, expert systems are usually more restricted and often applicable only to the domain for which they were originally developed. However, the machine learning approach requires the availability of large chunks of data, and it is much more complicated to interpret the results of the statistical methods to obtain some explanation of why the system decides, classifies, or evaluates a situation in a certain way. This issue may become very important in areas such as medicine, where it is relevant to know why the system recommends a certain treatment or diagnoses a certain illness. Likewise, in the financial sector, it might be legally required to explain that a decision to reject the granting of a mortgage loan to a person is not due to discriminatory causes such as gender or race. In order to be able to have interpretability and extract knowledge of available data we developed a classification method based on Dempster-Shafer's Plausibility Theory. Mass assignment functions (MAF) must be established to apply this theory and they assign a weight or probability to all subsets of the possible outcomes, given the presence of a certain fact on a decision scenario. Thus MAF assignments encode expert knowledge. The method learns optimal values for the weights of each MAF using the Gradient Descent method. The presented method allows combination of MAF which have been generated by the method itself or defined by an expert with those that are derived from a set of available data. The developed method was first applied to controlled scenarios and traditional data sets to ensure that classifications and explanations are correct. Results show that the model can classify with an accuracy which is comparable to other statistical classification methods, being also able to extract the most important decision rules from the data.Conicyt (Chile) scholarship 2218050

Common context for decisions and their implementations

Decisions are frequently sent to implementers without the context that guided them. It should not be a surprise, then, that results are not as expected. The lack of supplementary information and a common context produces wrongly implemented or lost decisions. This paper proposes a solution to this problem based on groupware technology. In particular, a combination of tools including shared workspaces, process modeling with workflow and a discussion tool, is proposed. A case is used to illustrate the problem and its solution

Reusing groupware applications

Many groupware applications have been developed and continue being developed over white-box groupware platforms. These platforms have brought important contributions to the development of groupware systems. However, the lack of compatibility among these platforms is limiting the portability of such solutions. This paper presents a middleware, which allows to improve the portability of new and legacy groupware applications supported by white-box platforms. The middleware translates a set of functionalities provided by the groupware platforms to a set of common groupware services used by the applications. These services provide groupware support and allow to improve the portability of groupware systems. A prototype of the proposed middleware has been tested and the interim results are encouraging

Findings when converting a summative evaluation instrument to a formative one through collaborative learning activities

Although illiteracy has been in constant decline over the last decades,there are too many reports about people having problems to identify the mainideas contained in texts they read. Reading comprehension is essential for stu-dents, because it is a predictor of their academic or professional success.Researchers have developed computer supported learning activities for sup-porting students develop their reading comprehension skills with varying degreesof success. One of the various advantages of having students work on electronicdocuments is that computers can help teachers monitor students’work. One ofthe problems of these systems is poor usability due to sophisticated human-computer interaction paradigms emulating activities students perform in tradi-tional learning activities for improving reading comprehension with pen andpaper. In this paper we report on a research which implements a learning activitybased on answers with multiple choice similar to a questionnaire, which is easy toimplement in computers and easy to interact with. Although multiple choicequestionnaires are associated to summative evaluations, the implementedlearning activity uses them within a collaborative learning activity in whichstudents have to justify,first individually then collaboratively, their choice with ashort text. The developed system was used and evaluated in a real learningsituation; one of the most interestingfindings is not only that students who haveto justify their option with a text perform better than those who have not, but thatthe pertinence of the text to the question does not play a major role. This suggeststhat just asking the students to justify their answers requires them to do a thinkingprocess which otherwise they would not do

Sharing information resources in mobile ad-hoc networks

Artículo de publicaciónMany people are sharing digital resources through networks in order to facilitate, enhance or improve collaborative work. Information sharing is not only important to support collaborative work but it also represents the basis for design and implementation of solutions for typical design aspects of groupware applications, such as: floor control, group memory, shared objects replication and sessions and users management. Advances in mobile technology have extended the sharing information scenarios to Mobile Ad-hoc Networks (MANETs), which has brought new challenges. This paper presents a simple service platform to share information resources among members of a MANETsupported groupware session. People interact using notebooks and PDAs. In addition, a shared presentation tool which has been developed using the services of the platform is described. This presentation tool can be used to assist other collaborative activities, such as: technical presentations, casual interactions, meetings for decision making and software technical reviews

A bibliometric overview of the Journal of Network and Computer Applications between 1997 and 2019

A bibliometric analysis of the Journal of Network and Computer Applications (JNCA) for the 1997-2019 period is performed. This analysis uncovers the structural and hidden implications of this journal. JNCA is one of the most prestigious journals in the computer science and engineering research community. Clarivate Analytics Web of Science is used to extract the bibliometric data on which the analysis is performed. The study begins with the publication and citation structure. Analysis of the most influential papers is discussed next. Detailed information on leading authors, institutions and countries is also presented. Analysis of the co-citations, bibliographic coupling, and co-occurrence of keywords was performed with the help of VOSviewer as a visualization tool. Alongside visual analysis, temporal and global analyses are also presented for the co-citation analysis and cooccurrence analysis

Exploring collaboration in the realm of virtual museums

Virtual museums have been very popular since the early days of the World Wide Web and many scientific works have been published on this topic. Although the rich variety of possibilities for supporting collaboration among the users of virtual museums, today very few implementations offer support for such kind of activities. This paper aims at settling the value of collaboration in virtual museums by means of depicting and classifying collaborative organization and co-curation activities in establishing, designing, planning, realizing, operating, deploying and visiting a virtual exhibition applying action research. As a use case, we present ongoing work to realize a virtual museum devoted to Armenian cross stones (Khachkars)

Basis for a Methodology to Define, Validate and Apply Best Practices in a Computer-integrated Classroom

A todos los que me acompañaron en esta aventura. Especialmente a Carolina, quien estuvo junto a mi en cada paso. i Agradecimientos Este es un proyecto que no es posible emprender solo. Durante el desarrollo de mi tesis recibí ayuda de más fuentes de las que podía imaginar. No me es posible agradecer en estas líneas a todos, así que pido disculpas a quienes involuntariamente he dejado fuera. Agradezco a mis profesores guía, Nelson Baloian, Ulrich Hoppe y José Pino, con quienes pude contar no sólo en lo profesional sino también en lo personal. Al Servicio Alemán de Intercambio Académico (DAAD) que permitió dedicación exclusiva a mi trabajo durante un período importante, a través de Maria Hartmann que siempre estuvo dispuesta a ayudar. Al grupo Collide de la Universität Duisburg-Essen que me acogió en un ambiente muy propicio, especialmente a Ulrich Hoppe