Classification of Metadata Categories in Data Warehousing - A Generic Approach

Using appropriate metadata is a central success factor for (re)engineering and using data warehouse systems effectively and efficiently. The approach presented in this paper aims to reduce the effort in developing and operating data warehouse systems and thus to increase the ability and acceptance of a data warehouse. To achieve these objectives identifying the appropriate metadata is an important task. To avoid processing the “wrong” object data and thus compromising the acceptance of a data warehouse system, a systematic approach to categorize and to identify the appropriate metadata is essential. This paper presents such a generic approach. After investing and structuring problem situations, that can occur in data warehousing, metadata categories are identified to solve a given problem situation. A use case illustrates the approach

Die tribologischen Eigenschaften von vergoldeten elektrischen Kontakten

Elektrische Steckkontakte sind in Kraftfahrzeugen Vibrationen und Thermohüben ausgesetzt, die zu Relativverschiebungen im tribologischen Kontakt führen. An einem AuCo/Ni vs. Au/NiP Kugel-Platte-Kontakt wurden tribologische Untersuchungen durchgeführt, um den auftretenden Schwingverschleiß und die dort wirkenden Verschleißmechanismen zu charakterisieren und den Verschleiß über ein globales Modell zu quantifizieren. Außerdem wurden anhand eines elektrischen Ausfallkriteriums Lebensdauermodelle in Abhängigkeit der Einflussgrößen Schwingweite, Goldschichtdicke und Rauheit aufgestellt. Der Ausfall des Steckkontaktes ist auf einen Verschleiß der Goldschichten und die dadurch initiierte Nickeloxidation im Verbund mit einem Anstieg des Übergangswiderstands zurückzuführen. Die dabei auftretenden Materialüberträge, Furchungsvorgänge, die Verschleißpartikelgenerierung sowie die Partikeltransportmechanismen üben einen entscheidenden Einfluss auf die Lebensdauer des elektrischen Steckkontaktes aus. Über die Verknüpfung der Lebensdauermodelle mit dem globalen Verschleißmodell kann durch Messung der Verschleißgrößen und bei bekannter Beanspruchung die Lebensdauer berechnet werden

Die tribologischen Eigenschaften von vergoldeten elektrischen Kontakten

Electrical contacts in automotive applications are exposed to thermal and vibration induced relative motion in the tribological contact. Fretting tests with an AuCo/Ni vs. Au/NiP ball to plate contact were conducted in order to describe the ongoing wear mechanisms. Furthermore, a global wear approach was chosen to quantify the overall wear. According to a predefined electrical failure criterion the connector lifetime is demonstrated in a model depending on oscillating amplitude, gold thickness and contact roughness. The electrical failure of the contact can be reduced to the wear of the gold platings leading to exposure of the nickel interlayer and consequently oxidation. Through material transfer, plowing, particle generation and the particle transport mechanisms the contact resistance increases and therefore limits the connector lifetime. The link between the lifetime models and the global wear approach allows for calculation of the lifetime when only the wear and the stress of the tribosystem are known

The Approach-Avoidance Job Crafting Scale: Development and validation of a measurement of the hierarchical structure of job crafting

The Approach-Avoidance Job Crafting Scale (AAJCS) builds on our adjusted version of a hierarchical structure of job crafting by Zhang and Parker from 2019. In developing and validating the new AAJCS, we, first, developed the German items in a stepwise procedure (pilot study). Second, we tested the factor structure and reliability (Study 1). Third, we replicated previous results and tested the construct validity (Study 2). Fourth, we ensured the criterion validity of the AAJCS (Study 3). The results suggested the existence of two independent factors, namely, approach and avoidance crafting, rather than a global job crafting factor. Furthermore, approach and avoidance crafting each consist of four job crafting dimensions, thus reflecting the hierarchical structure of job crafting. Within these dimensions, aspects of previous job crafting concepts are integrated. The distinction between approach and avoidance crafting became apparent in the comparison of their criterion validities as follows: Approach crafting was positively related to work-related outcomes, while avoidance crafting was negatively associated with work engagement and performance. Furthermore, approach and avoidance crafting exhibited incremental validity with regard to predict work engagement and performance beyond previous job crafting concepts. Approach crafting was positively associated while avoidance crafting was negatively associated with work engagement and performance.Peer Reviewe

Prävention, Detektion und Reaktion gegen drei Ausprägungsformen automotiver Malware : eine methodische Analyse im Spektrum von Manipulationen und Schutzkonzepten

Magdeburg, Univ., Fak. für Informatik, Diss., 2014von Tobias Hopp

Navigating Across Non-Navigable Ecore References via OCL

The Eclipse Modeling Framework (EMF) and its meta-meta model Ecore support uni-directional and bi-directional references. It is quite common that references are defined uni-directionally only because of saving storage space or separating meta models, which is problematic when implementing Object Constraint Language (OCL) constraints that require navigation against the direction of uni-directional references. This is essential for certain approaches, e.g., incremental evaluation of OCL constraints on models shown by Altenhofen et al. that is used in SAP's Modeling Infrastructure (MOIN). In this paper, we present an approach that overcomes the aforementioned issue by providing navigation across non-navigable Ecore references via OCL. We further discuss different alternative solutions and briefly describe the realization that was outcome of a project in cooperation with the SAP AG

Exploring the Relationship Between Social Networking Site Usage and Participation in Protest Activities

A methodological approach is developed for exploring the relationship between the use of social networking sites and participation in protest activities. Although a recent meta-analysis study demonstrated that there is a positive association between the two, little work examining this association further appears to have been published. The methodology proposed here studies the patterns of the relationship between nine social media and five types of protest activity using the techniques of multiple correspondence analysis, hierarchical cluster analysis and induction of decision rules. The results give insights into the relationship in different segments of individuals' profiles defined as non-activist, offline activist, social media user (two types) and online activist. Significantly, this last segment proves to be a small and heterogeneous group. The results also show that the proposed approach is useful for exploring the patterns of the relationship in a low-dimensional space. Limitations of the methodology and possible extensions are discussed

GraphSAW: A web-based system for graphical analysis of drug interactions and side effects using pharmaceutical and molecular data

Shoshi A, Hoppe T, Kormeier B, Ogultarhan V, Hofestädt R. GraphSAW: A web-based system for graphical analysis of drug interactions and side effects using pharmaceutical and molecular data. BMC Medical Informatics and Decision Making. 2015;15(1): 15.Background Adverse drug reactions are one of the most common causes of death in industrialized Western countries. Nowadays, empirical data from clinical studies for the approval and monitoring of drugs and molecular databases is available. Methods The integration of database information is a promising method for providing well-based knowledge to avoid adverse drug reactions. This paper presents our web-based decision support system GraphSAW which analyzes and evaluates drug interactions and side effects based on data from two commercial and two freely available molecular databases. The system is able to analyze single and combined drug-drug interactions, drug-molecule interactions as well as single and cumulative side effects. In addition, it allows exploring associative networks of drugs, molecules, metabolic pathways, and diseases in an intuitive way. The molecular medication analysis includes the capabilities of the upper features. Results A statistical evaluation of the integrated data and top 20 drugs concerning drug interactions and side effects is performed. The results of the data analysis give an overview of all theoretically possible drug interactions and side effects. The evaluation shows a mismatch between pharmaceutical and molecular databases. The concordance of drug interactions was about 12% and 9% of drug side effects. An application case with prescribed data of 11 patients is presented in order to demonstrate the functionality of the system under real conditions. For each patient at least two interactions occured in every medication and about 8% of total diseases were possibly induced by drug therapy. Conclusions GraphSAW (http://tunicata.techfak.uni-bielefeld.de/graphsaw/ webcite) is meant to be a web-based system for health professionals and researchers. GraphSAW provides comprehensive drug-related knowledge and an improved medication analysis which may support efforts to reduce the risk of medication errors and numerous drastic side effects

Der Einfluss der Länge von Beobachtungszeiträumen auf die Identifizierung von Subgruppen in Online Communities

Die Verbreitung von Social Media und damit verbunden die entstehenden und wachsenden Communities im Internet führen zu einer Zunahme von auswertbaren, digitalen Spuren, die häufig öffentlich zugänglich sind. Diese lassen sich durch verschiedene analytische Verfahren wie z.B. die Methode der Sozialen Netzwerkanalyse [1] auswerten. Insbesondere Ansätze für „Community Detection“ erfreuen sich besonderer Beliebtheit, wodurch sich unter anderem innovative Untergemeinschaften und Subgruppen beispielsweise in großen „Open Source“-Projekten identifizieren lassen [2]. Im Rahmen dieser Anwendungen ergeben sich neue methodische und grundlegende Fragen, darunter die nach der Rolle der von Zeit in solchen Analysen. Während die Darstellung dynamischer Effekte (z.B. durch Animationen) die Zeit als expliziten Parameter enthält, geht die Wahl der Zeitintervalle für die Aggregation von Daten, aus denen dann Netzwerke gewonnen werden, nur implizit in die Prämissen des Verfahrens ein. Diese Effekte wurden im Gegensatz zur Analyse von Dynamik bisher kaum untersucht. Im Fall der Sozialen Netzwerkanalyse ist die Zielrepräsentation selbst nicht mehr zeitbehaftet sondern sozusagen ein „statischer Schnappschuss“, wodurch etwa zeitabhängige Interaktionsmuster nicht erkannt werden können. (...

Community detection for access-control decisions: Analysing the role of homophily and information diffusion in Online Social Networks

Access-Control Lists (ACLs) (a.k.a. “friend lists”) are one of the most important privacy features of Online Social Networks (OSNs) as they allow users to restrict the audience of their publications. Nevertheless, creating and maintaining custom ACLs can introduce a high cognitive burden on average OSNs users since it normally requires assessing the trustworthiness of a large number of contacts. In principle, community detection algorithms can be leveraged to support the generation of ACLs by mapping a set of examples (i.e. contacts labelled as “untrusted”) to the emerging communities inside the user’s ego-network. However, unlike users’ access-control preferences, traditional community-detection algorithms do not take the homophily characteristics of such communities into account (i.e. attributes shared among members). Consequently, this strategy may lead to inaccurate ACL configurations and privacy breaches under certain homophily scenarios. This work investigates the use of community-detection algorithms for the automatic generation of ACLs in OSNs. Particularly, it analyses the performance of the aforementioned approach under different homophily conditions through a simulation model. Furthermore, since private information may reach the scope of untrusted recipients through the re-sharing affordances of OSNs, information diffusion processes are also modelled and taken explicitly into account. Altogether, the removal of gatekeeper nodes is further explored as a strategy to counteract unwanted data dissemination