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Richter A.,University of Federal Defense Munich | Stocker A.,Virtual Vehicle Research Center | Muller S.,University of Federal Defense Munich | Avram G.,University of Limerick
VINE | Year: 2013

Purpose: The purpose of this paper is to provide both practice-oriented researchers and practitioners with detailed insights into the social software goals and implementation strategies for corporate environments. Also, to illustrate the novelty and specificity of corporate social software (CSS) compared to other groupware or knowledge management systems. Design/methodology/approach: The paper is grounded in the ongoing discussion on differences and commonalities of knowledge management and Enterprise 2.0 applications and motivated by the lack of scientific studies on this topic. The authors have therefore made a comprehensive study of social software adoption in corporate environments, performing a cross-case analysis of 23 enterprises. The study was meant to enable researchers and practitioners to acquire a better understanding and appropriate related explanations of the relatively new phenomenon of CSS appropriation and use. Findings: From the cross-case analysis, six main goals of CSS adoption were derived and compared with the goals of knowledge management projects and initiatives. While some of the goals set for the introduction of CSS seem to coincide with those resulting from knowledge management studies (e.g. establishing networks of experts), others appear to be novel and specific for CSS (e.g. improving employee-to-employee communication). Originality/value: By investigating 23 different cases (most of these case studies being documented by the authors), this paper presents one of the most comprehensive cross-case analyses systematically exploring pursued goals and implementation approaches adopted for CSS. The contribution of the study is relevant for both research and practice and it is aimed to contribute to the ongoing scientific debate on social software in knowledge management and information systems research. © Emerald Group Publishing Limited. Source


Steiner A.,Virtual Vehicle Research Center | Rieberer R.,University of Graz
International Journal of Refrigeration | Year: 2015

Resistance heating with PTC elements to cover the heat demand of electric vehicles reduces significantly the cruising range at low outside temperatures. Reversible heat pump systems are one of the most promising solutions for this problem. However, in heat pump mode the frost formation on the exterior heat exchanger reduces the performance and efficiency of the system. Therefore, an efficient defrost method is crucial to benefit from the heat pump also under frosting conditions. In the present paper, a transient Modelica simulation model of a reversible CO2-heat pump system with hot gas defrost was set up in order to assess the impact of different defrost start times. The model is able to handle frost growth on the exterior heat exchanger as well as defrosting. The simulation results showed an optimal point of time to conduct defrost at chosen operating conditions in order to maximize the average COP including the frosting and defrost period. © 2015 Elsevier Ltd and IIR. © 2015 Elsevier Ltd and IIR. All rights reserved. Source


Steiner A.,Virtual Vehicle Research Center | Rieberer R.,University of Graz
Applied Thermal Engineering | Year: 2013

The use of resistance heaters with PTC elements to cover the heat demand of electric vehicles reduces significantly the cruising range. Reversible cooling and heating systems are one of the most promising solutions for this problem. However, in heat pump mode the frost formation on the exterior heat exchanger reduces the performance and efficiency of the system. Therefore, an efficient defrosting method is crucial to benefit from the heat pump also under frosting conditions. In the present paper, measurement results of a reverse cycle defrosting process on a reversible cooling and heating system using CO 2 as working fluid for an electric city car at chosen operating condition are discussed. Further, a transient Modelica simulation model was set up in order to assess the impact of different parameters during defrosting and to optimize the process. The simulation results showed the effect of different throttle valve openings on the defrosting process and a best performing valve-opening, where the defrost efficiency was higher and the defrost time was shorter compared to the other cases. © 2013 Elsevier Ltd. All rights reserved. Source


Allmaier H.,Virtual Vehicle Research Center | Offner G.,AVL List GmbH
SAE Technical Papers | Year: 2016

Elastohydrodynamic (EHD)-simulation is a widely applied simulation technique that is used in a very diverse field of applications ranging from the study of vibroacoustics to the calculation of friction power losses in lubricated contacts. In particular, but not limited to, the automotive industry, technical advances and new requirements put current EHD simulation methodology under test. Ongoing trends like downsizing, downspeeding, start-stop and the continuing demand for increasing fuel efficiency impose new demands and challenges also on the simulation methodology. Increasing computational capabilities enable new simulation opportunities on the other hand. In the following, an overview is given on the current state of the art and today's challenges for the elastohydrodynamic simulation of journal bearings and their wide range of applications from highly loaded main bearings supporting the crank shaft in the ICE to high speed turbocharger bearings. The topics addressed in this work span a wide range from mixed lubrication, low viscosity lubricants, polymer coatings, microstructured surfaces to the simulation of the thermal behavior and the simulation of hydraulically coupled journal bearings as they are commonly present in internal combustion engines. Copyright © 2016 SAE International. Source


Kracalik M.,Materials Center Leoben Forschung | Trummer G.,Virtual Vehicle Research Center | Daves W.,Materials Center Leoben Forschung | Daves W.,University of Leoben
Wear | Year: 2016

This paper compares the stress and strain state simulated in a twin-disc test and a full scale wheel/rail experiment. The simulation is done by two-dimensional finite element models. The simulations regard the scaling factor between these experiments. This factor includes the contact patch size and the deformation depth. Same stresses and strains are calculated for both experiments considering this scale factor. For the investigation of cracks in these experiments, initiated short cracks or manually produced initial cracks are needed. The transferability of the crack growth predictions from twin-disc tests to the full scale wheel/rail experiments affords a scaling of the initial crack size to the size of the contact patches. Out of practical reasons usually the initial crack tips are located in both experiments in another depth as the scaling would afford and therefore, the tips are located in another zone of the plastic deformation. Very short cracks in the twin-disc tests are removed by wear or are influenced by the always existing surface roughness. It is shown that stresses and strains scale with the experiments but this will be not the case for wear and surface roughness. © 2015 Elsevier B.V. Source

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