openHSU – Research Showcase

4501
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779
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140
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109
Projects
31
Conferences
17
Journals
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  • Publication
    Metadata only
    Cross-lingual Web API classification and annotation
    (RWTH, 2011-11-03) ;
    Zilka, Lukas
    ;
    Knoth, Petr
    ;
    Pedrinaci, Carlos
    Recent developments on the Web are marked by the growing support for the Linked Data initiative, which encourages government and public organisations, as well as private institutions, to expose their data on the Web. This results in a plentitude of multi-lingual document collections where the original resources are published in the language, in which they are available. The challenges of multilingualism present on the Semantic Web are also reflected in the context of services on the Web, characterised by the rapid increase in popularity and use of Web APIs, as indicated by the growing number of available APIs and the applications built on top of them. Web APIs are commonly described in plain-text as part of Web pages, following no particular guidelines and conforming to no standards, despite some initial approaches in the area [1, 2]. Therefore, API providers publish descriptions in any language they see fit, making the service discovery and the subsequent processing of the documentation challenging tasks. In this paper, we present a cross-lingual approach that calculates semantic similarity of text to help classify and annotate Web APIs, based on their textual descriptions. Furthermore, we show how our solution can be implemented as part of SWEET [3], which is a tool that enables the semi-automated creation of semantic Web API descriptions. In addition, we demonstrate how the cross-lingual approach can be adopted to support the language-independent discovery of Web APIs.
  • Publication
    Metadata only
    Semantic annotation of web APIs with SWEET
    (RWTH, 2011-02-08) ;
    Pedrinaci, Carlos
    ;
    Domingue, John
    Recently technology developments in the area of services on the Web are marked by the proliferation of Web applications and APIs. The development and evolution of applications based on Web APIs is, however, hampered by the lack of automation that can be achieved with current technologies. In this paper we present SWEET- Semantic Web sErvices Editing Tool- A lightweight Web application for creating seman- tic descriptions of Web APIs. SWEET directly supports the creation of mashups by enabling the semantic annotation of Web APIs, thus contributing to the automation of the discovery, composition and invocation service tasks. Furthermore, it enables the development of composite SWS based applications on top of Linked Data.
  • Publication
    Metadata only
    IServe: a linked services publishing platform
    (2010-06-11)
    Pedrinaci, Carlos
    ;
    Liu, Dong
    ;
    ;
    Lambert, David
    ;
    Kopecky, Jacek
    ;
    Domingue, John
    Despite the potential of service-orientation and the efforts devoted so far, we are still to witness a significant uptake of service technologies outside of enterprise environments. A core reason for this limited uptake is the lack of appropriate publishing platforms able to deal with the existing heterogeneity in the service technologies landscape and able to provide expressive yet simple and efficient discovery mechanisms. In this paper we describe iServe, a novel and open platform for publishing services which aims to better support their discovery and use. It exposes service descriptions as linked data expressed in terms of a simple vocabulary for describing services of different kinds with annotations in diverse formalisms. In addition to describing iServe, this paper also highlights the set of principles behind iServe, which we believe are essential for other generic repositories of semantic information notably ontology repositories.
  • Publication
    Metadata only
    Investigating Web APIs on the World Wide Web
    (IEEE, 2010-12) ;
    Pedrinaci, Carlos
    ;
    Domingue, John
    The world of services on the Web, thus far limited to "classical" Web services based on WSDL and SOAP, has been increasingly marked by the domination of Web APIs, characterised by their relative simplicity and their natural suitability for the Web. Currently, the development of Web APIs is rather autonomous, guided by no established standards or rules, and Web API documentation is commonly not based on an interface description language such as WSDL, but is rather given directly in HTML as part of a webpage. As a result, the use of Web APIs requires extensive manual effort and the wealth of existing work on supporting common service tasks, including discovery, composition and invocation, can hardly be reused or adapted to APIs. Before we can achieve a higher level of automation and can make any significant improvement to current practices and technologies, we need to reach a deeper understanding of these. Therefore, in this paper we present a thorough analysis of the current landscape of Web API forms and descriptions, which has up-to-date remained unexplored. We base our findings on manually examining a body of publicly available APIs and, as a result, provide conclusions about common description forms, output types, usage of API parameters, invocation support, level of reusability, API granularity and authentication details. The collected data provides a solid basis for identifying deficiencies and realising how we can overcome existing limitations. More importantly, our analysis can be used as a basis for devising common standards and guidelines for Web API development. © 2010 IEEE.
  • Publication
    Metadata only
    Acquisition and management of Semantic Web service descriptions
    (RWTH, 2008-06-16)
    The increasing importance and use of Web services have resulted in a number of efforts targeted at automating Web service discovery and composition based on semantic descriptions of their properties. However, the progress in the automation of Web service discovery is still held back by the fact that the description of Web services in terms of semantic metadata is still mainly manually. This Ph.D. thesis addresses this problem by developing an approach for the acquisition and management of semantic Web service descriptions in order to facilitate efficient service discovery and composition. Specifically, this involves the collection of information about a Web service, the acquisition of semantic descriptions based on the collected information, and the structured storage of the generated semantic descriptions.
  • Publication
    Metadata only
    Cognitive tools pipeline for assistance of mitral valve surgery
    (Society of Photo-optical Instrumentation Engineers (SPIE), 2016)
    Schoch, Nicolai
    ;
    Philipp, Patrick
    ;
    Weller, Tobias
    ;
    Engelhardt, Sandy
    ;
    Volovyk, Mykola
    ;
    Fetzer, Andreas
    ;
    Nolden, Marco
    ;
    De Simone, Raffaele
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    Wolf, Ivo
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    Rettinger, Achim
    ;
    Studer, Rudi
    ;
    Heuveline, Vincent
    For cardiac surgeons, mitral valve reconstruction (MVR) surgery is a highly demanding procedure, where an artificial annuloplasty ring is implanted onto the mitral valve annulus to re-enable the valve's proper closing functionality. For a successful operation the surgeon has to keep track of a variety of relevant impact factors, such as patient-individual medical history records, valve geometries, or tissue properties of the surgical target, and thereon-based deduce type and size of the best-suitable ring prosthesis according to practical surgery experience. With this work, we aim at supporting the surgeon in selecting this ring prosthesis by means of a comprehensive information processing pipeline. It gathers all available patient-individual information, and mines this data according to 'surgical rules', that represent published MVR expert knowledge and recommended best practices, in order to suggest a set of potentially suitable annuloplasty rings. Subsequently, these rings are employed in biomechanical MVR simulation scenarios, which simulate the behavior of the patient-specific mitral valve subjected to the respective virtual ring implantation. We present the implementation of our deductive system for MVR ring selection and how it is integrated into a cognitive data processing pipeline architecture, which is built under consideration of Linked Data principles in order to facilitate holistic information processing of heterogeneous medical data. By the example of MVR surgery, we demonstrate the ease of use and the applicability of our development. We expect to essentially support patient-specific decision making in MVR surgery by means of this holistic information processing approach. © 2016 SPIE.
  • Publication
    Open Access
    Machine scheduling problems with position-dependent availability constraints
    (UB HSU, 2024-06-19) ; ;
    Helmut-Schmidt-Universität / Universität der Bundeswehr Hamburg
    ;
    Machine scheduling problems can be found in any practical environment from logistics to manufacturing, where tasks, called jobs, are completed by assigning them to resources, called machines. In this thesis, we assume that the execution of jobs deteriorates the machine to the point where it may not be in a state to process further jobs, or, more generally, restricts the availability of the machine. Time is often considered to be the main factor in machine deterioration, such as the time elapsed since the start of planning. However, with regard to practice, there are other important factors besides time that can have a significant impact on the machine state. In this work, we concentrate on factors based on the job positions in the scheduling sequence, summarized as position-dependent machine availability constraints. This characteristic can be found in any production or logistics environment where the assignment of the job to the machine determines the availability of the machine to process jobs, rather than the processing time. First, a definition and the existing literature of the superordinate research field of problems with position-dependent availability is given: state-dependent machine availability. In the following, single machine scheduling problems with position-dependent maintenance or with jobs that have to be sequenced at fixed positions are analyzed regarding their complexity. These assumptions represent specific characteristics of position-dependent availability in scheduling. For each assumption, complexity results are presented for single machine scheduling problems minimizing completion time or due date related objective functions. In addition, polynomial-time algorithms are formulated for specific scheduling problems. Finally, we deal with the hybrid flow shop scheduling (HFS) problem that is characterized by a flow shop layout with at least one stage of processing with parallel machines. Priority rules and constructive heuristics are tested and evaluated on 1260 instances for the two-stage no-wait HFS problem with two identical machines on the first stage and one machine on the second stage, which is known to be NP-hard. Furthermore, HFS problems with unrelated machines are assumed, considering setup times on the machines caused by different job families. Constructive heuristics are tested on 960 instances to study the influence of the number of setups on the results for completion time related objective functions.
  • Publication
    Open Access
    The role of interindividual differences in task-based approach-avoidance behavior
    (UB HSU, 2024-06-17)
    Fricke, Kim L.
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    ;
    Helmut-Schmidt-Universität / Universität der Bundeswehr Hamburg
    ;
    Vogel, Susanne
    Approach and avoidance are evolutionary highly conserved mechanisms of survival, realized by approaching rewarding and avoiding punishing stimuli in one’s environment. In the laboratory, approach-avoidance behaviors are often measured using experimental tasks. In this thesis, the relationship of interindividual differences with behavioral outcomes of those so-called approach-avoidance tasks was investigated. Firstly, the literature on approach-avoidance tasks and interindividual differences was systematically reviewed. Secondly, the influences of the stress mediators cortisol and noradrenaline as well as self-reported interindividual differences was investigated with a pharmacologically validated approach-avoidance conflict paradigm in a double-blind study with healthy participants. Lastly, the approach-avoidance conflict paradigm was compared to two more established approach-avoidance tasks, the joystick and manikin tasks, in their efficacy to relate to self-reported interindividual differences. Both, systematic review and the conducted research indicates that relationships between task-based approach-avoidance measures and interindividual differences are ambiguous in nature with few exceptions, e.g. in the case of specific phobias. The approach-avoidance conflict paradigm was not affected by the stress mediators, but related to self-reported behavioral inhibition, physical aggression and verbal aggression whereas the joystick and manikin tasks did not. Even those findings appear to be ambiguous, as while interactions of aggression were found in the comparison study, they were not in the pharmacological study, possibly due to a lack of power. Internal consistency measures of all three tasks indicated subpar consistencies for joystick and manikin task and robust consistencies of approach-avoidance conflict paradigm measures. Potential reasons such as differences in the level of abstraction between task and trait measures, particularities of the task designs as well as ideas to resolve or improve them, for example, by employing more ecologically valid designs, are discussed.
  • Publication
    Metadata only
    Comparison of two reaction-time-based and one foraging-based behavioral approach-avoidance tasks in relation to interindividual differences and their reliability
    (Springer Nature, 2023-12-16)
    Fricke, Kim
    ;
    Alexander, Nina
    ;
    ;
    Vogel,Susanne
    Approaching rewards and avoiding punishments is a fundamental aspect of behavior, yet individuals differ in the extent of these behavioral tendencies. One popular method to assess differences in approach-avoidance tendencies and even modify them, is using behavioral tasks in which spontaneous responses to differently valenced stimuli are assessed (e.g., the visual joystick and the manikin task). Understanding whether these reaction-time-based tasks map onto the same underlying constructs, how they predict interindividual differences in theoretically related constructs and how reliable they are, seems vital to make informed judgements about current findings and future studies. In this preregistered study, 168 participants (81 self-identified men, 87 women) completed emotional face versions of these tasks as well as an alternative, foraging-based paradigm, the approach-avoidance-conflict task, and answered self-report questionnaires regarding anxiety, aggression, depressive symptoms, behavioral inhibition and activation. Importantly, approach-avoidance outcome measures of the two reaction-time-based tasks were unrelated with each other, showed little relation to self-reported interindividual differences and had subpar internal consistencies. In contrast, the approach-avoidance-conflict task was related to behavioral inhibition and aggression, and had good internal consistencies. Our study highlights the need for more research into optimizing behavioral approach-avoidance measures when using task-based approach-avoidance measures to assess interindividual differences.