Refine
Year of publication
- 2008 (18) (remove)
Document Type
- Part of Periodical (6)
- Doctoral Thesis (5)
- Master's Thesis (3)
- Diploma Thesis (2)
- Study Thesis (2)
Language
- English (18) (remove)
Keywords
- Abduktion <Logik> (1)
- Bayes-Netz (1)
- Bayesian Networks (1)
- Beruflicher Kontakt (1)
- Beschaffung (1)
- Bluetooth (1)
- Bürgerbeiteiligung (1)
- CodeBlue (1)
- Computer Security (1)
- Computersicherheit (1)
Institute
- Fachbereich 4 (8)
- Institut für Informatik (7)
- Institut für Wirtschafts- und Verwaltungsinformatik (3)
- Fachbereich 6 (1)
- Fachbereich 8 (1)
- Institut für Computervisualistik (1)
- Institut für Integrierte Naturwissenschaften, Abt. Biologie (1)
- Institut für Management (1)
- Institut für Softwaretechnik (1)
- Institut für fremdsprachliche Philologien (1)
This dissertation introduces a methodology for formal specification and verification of user interfaces under security aspects. The methodology allows to use formal methods pervasively in the specification and verification of human-computer interaction. This work consists of three parts. In the first part, a formal methodology for the description of human-computer interaction is developed. In the second part, existing definitions of computer security are adapted for human-computer interaction and formalized. A generic formal model of human-computer interaction is developed. In the third part, the methodology is applied to the specification and verification of a secure email client.
CAMPUS NEWS - artificial intelligence methods combined for an intelligent information network
(2008)
In this paper we describe a network for distributing personalised information with the usage of artificial intelligence methods. Reception of this information should be possible with everyday mobile equipment. Intelligent filtering and spam protection aim at integrating this technology into our environment. Information on the system architecture and usage of the installation are also presented.
Semantic desktop environments aim at improving the effectiveness and efficiency of users carrying out daily tasks within their personal information management infrastructure (PIM). They support the user by transferring and exploiting the explicit semantics of data items across different PIM applications. Whether such an approach does indeed reach its aim of facilitating users" life and—if so—to which extent, however, remains an open question that we address in this paper with the first summative evaluation of a semantic desktop approach. We approach the research question exploiting our own semantic desktop infrastructure, X-COSIM. As data corpus, we have used over 100 emails and 50 documents extracted from the organizers of a conference-like event at our university. The evaluation has been carried out with 18 subjects. We have developed a test environment to evaluate COSIMail and COSIFile, two semantic PIM applications based on X-COSIM. As result, we have found a significant improvement for typical PIM tasks compared to a standard desktop environment.
The internet is becoming more and more important in daily life. Fundamental changes can be observed in the private sector as well as in the public sector. In the course of this, active involvement of citizens in planning political procedures is more and more supported electronically. The expectations culminate in the assumption that information and communication technology (ICT) can enhance civic participation and reduce disenchantment with politics. Out of these expectations, a lot of eparticipation projects were initiated in Germany. Initiatives were established, e.g. the "Initiative eParticipation", which gave many incentives of electronic participation for policy and administration in order to strengthen decision-making processes with internet supported participation practices. This thesis consists of two major parts. In the first part, definitions of the essential terms are presented. The position of e-participation within the dimension of ebusiness is pointed out. In order to explain e-participation, basics of the classical offline participation are delivered. It will be shown that a change is in progress, not only because of the deployment of ICT. Subsequently, a framework to characterize eparticipation is presented. The European Union is encouraging the implementation of e-participation. So, the city of Koblenz should be no exception. But what is the current situation in Koblenz? To provide an answer to this question, the status quo was examined with the help of a survey among the citizens of Koblenz, which was developed, conducted and evaluated. This is the second major part of this thesis.
Foliicolous lichens are one of the most abundant epiphytes in tropical rainforests and one of the few groups of organisms that characterize these forests. Tropical rainforests are increasingly affected by anthropogenic disturbance resulting in forest destruction and degradation. However, not much is known on the effects of anthropogenic disturbance on the diversity of foliicolous lichens. Understanding such effects is crucial for the development of appropriate measures for the conservation of such organisms. In this study, foliicolous lichens diversity was investigated in three tropical rainforests in East Africa. Godere Forest in Southwest Ethiopia is a transitional rainforest with a mixture of Afromontane and Guineo-Congolian species. The forest is secondary and has been affected by shifting cultivation, semi-forest coffee management and commercial coffee plantation. Budongo Forest in West Uganda is a Guineo-Congolian rainforest consisting of primary and secondary forests. Kakamega Forest in western Kenya is a transitional rainforest with a mixture of Guineo-Congolian and Afromontane species. The forest is a mosaic of near-primary forest, secondary forests of different seral stages, grasslands, plantations, and natural glades.
Computers and especially computer networks have become an important part of our everyday life. Almost every device we use is equipped with a computer or microcontroller. Recent technology has even boosted this development by miniaturization of the size of microcontrollers. These are used to either process or collect data. Miniature senors may sense and collect huge amounts of information coming from nature, either from environment or from our own bodies. To process and distribute the data of these sensors, wireless sensor networks (WSN) have been developed in the last couple of years. Several microcontrollers are connected over a wireless connection and are able to collect, transmit and process data for various applications. Today, there are several WSN applications available, such as environment monitoring, rescue operations, habitat monitoring and smart home applications. The research group of Prof. Elaine Lawrence at the University of Technology, Sydney (UTS) is focusing on mobile health care with WSN. Small sensors are used to collect vital data. This data is sent over the network to be processed at a central device such as computer, laptop or handheld device. The research group has developed several prototypes of mobile health care. This thesis will deal with enhancing and improving the latest prototype based on CodeBlue, a hardware and software framework for medical care.
Probability propagation nets
(2008)
This work introduces a Petri net representation for the propagation of probabilities and likelihoods, which can be applied to probabilistic Horn abduction, fault trees, and Bayesian networks. These so-called "probability propagation nets" increase the transparency of propagation processes by integrating structural and dynamical aspects into one homogeneous representation. It is shown by means of popular examples that probability propagation nets improve the understanding of propagation processes - especially with respect to the Bayesian propagation algorithms - and thus are well suited for the analysis and diagnosis of probabilistic models. Representing fault trees with probability propagation nets transfers these possibilities to the modeling of technical systems.
Querying for meta knowledge
(2008)
The Semantic Web is based on accessing and reusing RDF data from many different sources, which one may assign different levels of authority and credibility. Existing Semantic Web query languages, like SPARQL, have targeted the retrieval, combination and reuse of facts, but have so far ignored all aspects of meta knowledge, such as origins, authorship, recency or certainty of data, to name but a few. In this paper, we present an original, generic, formalized and implemented approach for managing many dimensions of meta knowledge, like source, authorship, certainty and others. The approach re-uses existing RDF modeling possibilities in order to represent meta knowledge. Then, it extends SPARQL query processing in such a way that given a SPARQL query for data, one may request meta knowledge without modifying the query proper. Thus, our approach achieves highly flexible and automatically coordinated querying for data and meta knowledge, while completely separating the two areas of concern.
Public electronic procurement (eProcurement), here electronic sourcing (eSourcing) in particular, is almost certainly on the agenda when eGovernment experts meet. Not surprisingly is eProcurement the first high-impact service to be addressed in the European Union- recent Action Plan. This is mainly dedicated to the fact that public procurement makes out almost 20% of Europe- GDP and therefore holds a huge saving potential. To some extent this potential lies in the common European market, since effective cross-boarder eSourcing solutions can open many doors, both for buyers and suppliers. To achieve this, systems and processes and tools, need to be adoptable, transferable as well as be able to communicate with each other. In one word, they need to be interoperable. In many relevant domains, interoperability has reached a very positive level, standards have been established, workflows been put in place. In other domains however, there is still a long road ahead. As a consequence it is crucial to define requirements for such interoperable eSourcing systems and to identify the progress in research and practice.
The University of Koblenz-Landau would like to apply for participation in the RoboCup Mixed Reality League in Suzhou, China 2008. Our team is composed of ten team members and two supervisors. All members are graduate students of Computational Visualistics. Our supervisors are Ph.D. candidates currently researching in the working groups of artificial intelligence and computer graphics.
Social networking platforms as creativity fostering systems: research model and exploratory study
(2008)
Social networking platforms are enabling users to create their own content, share this content with anyone they invite and organize connections with existing or new online contacts. Within these electronic environments users voluntarily add comments on virtual boards, distribute their search results or add information about their expertise areas to their social networking profiles and thereby share it with acquaintances, friends and increasingly even with colleagues in the corporate world. As a result, it is most likely that the underlying knowledge sharing processes result in many new and creative ideas. The objective of our research therefore is to understand if and how social social networking platforms can enforce creativity. In addition, we look at how these processes could be embedded within the organizational structures that influence innovative knowledge sharing behavior. The basis for our research is a framework which focuses on the relations between intrinsic motivation, creativity and social networking platforms. First results of our empirical investigation of a social software platform called "StudiVZ.net" proved that our two propositions are valid.
This volume contains those research papers presented at the Second International Conference on Tests and Proofs (TAP 2008) that were not included in the main conference proceedings. TAP was the second conference devoted to the convergence of proofs and tests. It combines ideas from both areas for the advancement of software quality. To prove the correctness of a program is to demonstrate, through impeccable mathematical techniques, that it has no bugs; to test a program is to run it with the expectation of discovering bugs. On the surface, the two techniques seem contradictory: if you have proved your program, it is fruitless to comb it for bugs; and if you are testing it, that is surely a sign that you have given up on any hope of proving its correctness. Accordingly, proofs and tests have, since the onset of software engineering research, been pursued by distinct communities using rather different techniques and tools. And yet the development of both approaches leads to the discovery of common issues and to the realization that each may need the other. The emergence of model checking has been one of the first signs that contradiction may yield to complementarity, but in the past few years an increasing number of research efforts have encountered the need for combining proofs and tests, dropping earlier dogmatic views of their incompatibility and taking instead the best of what each of these software engineering domains has to offer. The first TAP conference (held at ETH Zurich in February 2007) was an attempt to provide a forum for the cross-fertilization of ideas and approaches from the testing and proving communities. For the 2008 edition we found the Monash University Prato Centre near Florence to be an ideal place providing a stimulating environment. We wish to sincerely thank all the authors who submitted their work for consideration. And we would like to thank the Program Committee members as well as additional referees for their great effort and professional work in the review and selection process. Their names are listed on the following pages. In addition to the contributed papers, the program included three excellent keynote talks. We are grateful to Michael Hennell (LDRA Ltd., Cheshire, UK), Orna Kupferman (Hebrew University, Israel), and Elaine Weyuker (AT&T Labs Inc., USA) for accepting the invitation to address the conference. Two very interesting tutorials were part of TAP 2008: "Parameterized Unit Testing with Pex" (J. de Halleux, N. Tillmann) and "Integrating Verification and Testing of Object-Oriented Software" (C. Engel, C. Gladisch, V. Klebanov, and P. Rümmer). We would like to express our thanks to the tutorial presenters for their contribution. It was a team effort that made the conference so successful. We are grateful to the Conference Chair and the Steering Committee members for their support. And we particularly thank Christoph Gladisch, Beate Körner, and Philipp Rümmer for their hard work and help in making the conference a success. In addition, we gratefully acknowledge the generous support of Microsoft Research Redmond, who financed an invited speaker.
The present thesis investigates attitudes and prosocial behavior between workgroups from a social identity and intergroup contact perspective. Based on the Common In-group Identity Model (CIIM; Gaertner & Dvoidio, 2000), it is hypothesized that "optimal" conditions for contact (Allport, 1954) create a common identity at the organizational level which motivates workgroups to cooperate and show organizational citizenship behavior (OCB) rather than intergroup bias. Predictions based on the CIIM are extended with hypotheses derived from the In-group Projection Model (IPM; Mummendey & Wenzel, 1999) and the Self-Categorization Model of Group Norms (Terry & Hogg, 1996). Hypotheses are tested with data from N1 = 281 employees of N2 = 49 different workgroups and their workgroup managers of a German mail-order company (Study 1). Results indicate that group- and individual-level contact conditions are predictive of lower levels of intergroup bias and higher levels of cooperation and helping behavior. A common in-group representation mediates the effect on out-group attitudes and intergroup cooperation. In addition, the effect of a common in-group representation on intergroup bias is moderated by relative prototypicality, as predicted by the IPM, and the effect of prosocial group norms on helping behavior is moderated by workgroup identification, as predicted by the Self-Categorization Model of Group Norms. A longitudinal study with Ntotal = 57 members of different student project groups replicates the finding that contact under "optimal" conditions reduces intergroup bias and increases prosocial behavior between organizational groups. However, a common in-group representation is not found to mediate this effect in Study 2. Initial findings also indicate that individual-level variables, such as helping behavior toward members of another workgroup, may be better accounted for by variables at the same level of categorization (cf. Haslam, 2004). Thus, contact in a context that makes personal identities of workgroup members salient (i.e., decategorization) may be more predictive of interpersonal prosocial behavior, while contact in a context that makes workgroup identities salient (i.e., categorization) may be more predictive of intergroup prosocial behavior (cf. Tajfel, 1978). Further data from Study 1 support such a context-specific effect of contact between workgroups on interpersonal and intergroup prosocial behavior, respectively. In the last step, a temporal integration of the contact contexts that either lead to decategorization, categorization, or recategorization are examined based on the Longitudinal Contact Model (Pettigrew, 1998). A first indication that a temporal sequence from decategorization via categorization to recategorization may be particularly effective in fostering intergroup cooperation is obtained with data from Study 2. In order to provide a heuristic model for research on prosocial behavior between workgroups, findings are integrated into a Context-Specific Contact Model. The model proposes specific effects of contact in different contexts on prosocial behavior at different levels of categorization. Possible mediator and moderator processes are suggested. A number of implications for theory, future research and the management of relations between workgroups are discussed.
The automatic detection of position and orientation of subsea cables and pipelines in camera images enables underwater vehicles to make autonomous inspections. Plants like algae growing on top and nearby cables and pipelines however complicate their visual detection: the determination of the position via border detection followed by line extraction often fails. Probabilistic approaches are here superior to deterministic approaches. Through modeling probabilities it is possible to make assumptions on the state of the system even if the number of extracted features is small. This work introduces a new tracking system for cable/pipeline following in image sequences which is based on particle filters. Extensive experiments on realistic underwater videos show robustness and performance of this approach and demonstrate advantages over previous works.
This thesis is concerned with an issue of considerable importance to the development of revision skills: the role of teacher feedback. Prompted by the concern to develop a model of instruction which will help students write to the best of their capacities, the present study forms a proposal: an interactive model of revision. The study researches whether the kind of feedback proposed in this model is indeed a helpful tool for revision and whether the kind of negotiated revision that occurs is a vehicle for learning. The first section of the thesis reviews different areas of literature which are relevant to the study. More specifically, Chapter 2 presents the historical and theoretical foundations of different writing instructional practices and sheds light on issues concerning the use of the process approach. It also reviews research based on sociocognitive theoretical perspectives in an attempt to delineate the impact of interpersonal or social activity on individual performance and progress. Chapter 3 examines issues associated with the process approach in particular and illustrates how theory and method come together in a process writing classroom. Chapter 4 presents the differences in revising behaviours between experienced and inexperienced writers in both L1 and L2 contexts and the various ways these differences have been justified. It also highlights a number of issues which have been identified as contributing to effective revision. Particular attention is paid to the role that teacher feedback has to play as a means of promoting substantive student revision with an instructional emphasis on fluency, organisation and language. Chapter 5 presents an interactive model of revision, which envisions a communicative exchange between two partners, the student-writer and the teacher-reader, collaborating in order to develop awareness of revision strategies and establish criteria for effective writing. Chapter 6 investigates the epistemological basis of the research and presents a set of research questions and hypotheses, which guided the investigation. Chapter 7 frames the context of the research and details the methods used to collect the data from the study. The study involved 100 Year 7 students in two gymnasia in Koblenz, Germany. During the time of the investigation, the students wrote and revised five tasks. Three of these tasks were revised after receiving teacher feedback, which focused on aspects such as appropriacy and sufficiency of information, organization, coherence and grammatical accuracy. The study investigates the effects of this kind of focused feedback on the students" revisions and explores the relationship between revision and text improvement. Large quantitative and qualitative data sets were generated during the research. The quantitative data was based on the student documents (1000 original and revised drafts) whereas the qualitative data emerged from student questionnaires and seven case studies. Chapter 8 presents descriptions of the data analyses. More specifically, it describes the initial and final coding of the revisions traced in the student documents. Then it focuses on the type of qualitative analysis employed in the case studies in order to investigate the relationship between revision and text improvement. The final section of the chapter describes the questionnaire analysis, which was carried out to investigate attitudes, benefits and constraints from the implementation of the model. Chapter 9 examines the statistical results from the analysis of the students" revisions. More specifically, it explores the revisions made by the students across tasks and the relationships between the features of the teacher feedback and these revisions. The analysis highlights patterns in the development of revision skills and positive correlations of student revisions with features of the teacher feedback. Chapter 10 looks at the descriptive data from the case studies of seven individual student writers. The analysis of this data illustrates how the specific students negotiated the revisions and sheds more light on the relationship between feedback, revision and text improvement. Chapter 11 contains the analysis of the students" answers to the questionnaire, which provide illuminative information about the feedback-related attitudes. In Chapter 12, the thesis reaches its final destination. The journey over the paths of literature exploration, data gathering and data analysis ends with reflections on the messages that emerge from the data analysis. The conclusion reached is that young students can learn how to revise their writing and focused feedback is a viable pedagogic option for teaching revision. In addition to discussing the findings, this final section considers the pedagogical implications for the teaching of writing and suggests possible avenues for further work.