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Budapest, Hungary

Twenty-one different commercial-grade engineering polymers, including virgin and composite types, were selected for testing, based on mechanical engineering practices. Three groups were formed according to typical applications: 1) Sliding machine element materials; 2) Mechanically load-carrying machine element materials that are often subjected to friction and wear effects; and 3) Additional two amorphous materials used as chemically resistant materials that have rare sliding load properties. The friction running-in state was tested using a dynamic pin-on-plate test rig. During steady-state friction tests, two pv regimes (0.8 and 2 MPa ms-1) were analysed by a pin-on-disc test system. Based on the measured forces on ground structural steel, surface friction coefficients were calculated and analysed with respect to the mechanical effects of friction. The friction results were evaluated by the measured mechanical properties: yield stress, Shore D hardness, Young's modulus and elongation at the break. The three material groups exhibited different trends in friction with respect to changing mechanical properties. Linear (with varying positive and negative slopes), logarithmic and exponential relationships were observed, and occasionally there were no effects observed. At steady-state friction, the elongation at the break had less effect on the friction coefficients. The dynamic sliding model, which correlates better to real machine element applications, showed that increasing hardness and yield stress decreases friction. During steady-state friction, an increase in pv regime often changed the sign of the linear relationship between the material property and the friction, which agrees with the frictional theory of polymer/steel sliding pairs. © BME-PT.


Hajdu M.,Szent Istvan University
Automation in Construction | Year: 2013

The Program Evaluation and Review Technique (PERT) has been criticized for the proposed (beta) distribution of the activities, the three-point estimation method, the assumption of task independence and the assumed distribution of the project duration since its birth. Developments and generalizations of the succeeding years and decades were mostly aimed at resolving these issues. However, there are still pending questions that have not been examined in detail, if at all. One of these issues is the effect of activity calendars on the distribution of the project duration. Using a simple artificially created project we prove that the application of activity calendars has a greater influence on the distribution of the project duration than any of the above-mentioned criticisms. In the absence of analytic solutions, a robust tool performing Monte Carlo simulations has been used for calculations. © 2013 The Author.


Zachar A.,Szent Istvan University
International Journal of Heat and Mass Transfer | Year: 2010

Steady heat transfer enhancement has been studied in helically coiled-tube heat exchangers. The outer side of the wall of the heat exchanger contains a helical corrugation which makes a helical rib on the inner side of the tube wall to induce additional swirling motion of fluid particles. Numerical calculations have been carried out to examine different geometrical parameters and the impact of flow and thermal boundary conditions for the heat transfer rate in laminar and transitional flow regimes. Calculated results have been compared to existing empirical formulas and experimental tests to investigate the validity of the numerical results in case of common helical tube heat exchanger and additionally results of the numerical computation of corrugated straight tubes for laminar and transition flow have been validated with experimental tests available in the literature. Comparison of the flow and temperature fields in case of common helical tube and the coil with spirally corrugated wall configuration are discussed. Heat exchanger coils with helically corrugated wall configuration show 80-100% increase for the inner side heat transfer rate due to the additionally developed swirling motion while the relative pressure drop is 10-600% larger compared to the common helically coiled heat exchangers. New empirical correlation has been proposed for the fully developed inner side heat transfer prediction in case of helically corrugated wall configuration. © 2010 Elsevier Ltd.


Grant
Agency: Cordis | Branch: FP7 | Program: CP | Phase: ICT-2013.8.2 | Award Amount: 3.34M | Year: 2014

Continuing education at the workplace has seen increasing demand as a crucial means of acquiring the requisite professional knowledge and skills. Electronic Portfolios (e-portfolios) for workplace training provide a global view of each trainees progress but offer no dynamic feedback to exploit the rich learning assessment data that could be analysed to support responsive adaptation for more efficient and rewarding training.\n\nWATCHME effectively deploys Learning Analytics (LA) tools to deliver personalised learning; supporting learner empowerment, enhanced Quality-of-Experience, flexibility and mobility plus efficiency gains through workplace-based feedback and assessment. This is achieved by developing, implementing and evaluating a mobile, electronic portfolio-based system that utilises LA and student models to provide data-driven and model-based tailored feedback via a visualisation dashboard. The multi-sourced integrated deployment of authentic workplace data including self-reporting, narratives, qualitative and quantitative data e.g. videos and serious educational games enables the WATCHME trainees to exercise and thereby sharpen their learnt skills by responding to realistically situated judgment calls in a motivational and safe environment.\n\nA Multi-entity Bayesian Network will be used for the student models, enabling an aggregation of data and tailored Just-in-Time feedback, visualised via intuitive interfaces. The close cooperation of educational researchers and ICT developers will deliver a tool to map critical professional tasks linked to their requisite competencies and markers for feedback and assessment in the workplace integrated with an easy access electronic portfolio system for data collection and LA-driven tools to inform trainees, teachers and supervisors about the trainees progress and deliver personalised Just-in-Time feedback with intuitive visualisation tools.\n\nThe WATCHME platform will be empirically validated for its quality and contribution to trainees learning. The overall system shall be evaluated formatively and summatively in three professional environments (human medicine, veterinary medicine and teacher training) including benchmarking against control sets.


Grant
Agency: Cordis | Branch: H2020 | Program: RIA | Phase: SFS-11b-2015 | Award Amount: 6.92M | Year: 2016

Aquaculture is one of five sectors in the EUs Blue Growth Strategy, aimed at harnessing untapped potential for food production and jobs whilst focusing on environmental sustainability. TAPAS addresses this challenge by supporting member states to establish a coherent and efficient regulatory framework aimed at sustainable growth. TAPAS will use a requirements analysis to evaluate existing regulatory and licensing frameworks across the EU, taking account of the range of production environments and specificities and emerging approaches such as offshore technologies, integrated multi-trophic aquaculture, and integration with other sectors. We will propose new, flexible approaches to open methods of coordination, working to unified, common standards. TAPAS will also evaluate existing tools for economic assessment of aquaculture sustainability affecting sectoral growth. TAPAS will critically evaluate the capabilities and verification level of existing ecosystem planning tools and will develop new approaches for evaluation of carrying capacities, environmental impact and future risk. TAPAS will improve existing and develop new models for far- and near-field environmental assessment providing better monitoring, observation, forecasting and early warning technologies. The innovative methodologies and components emerging from TAPAS will be integrated in an Aquaculture Sustainability Toolbox complemented by a decision support system to support the development and implementation of coastal and marine spatial planning enabling less costly, more transparent and more efficient licensing. TAPAS partners will collaborate with key industry regulators and certifiers through case studies to ensure the acceptability and utility of project approach and outcomes. Training, dissemination and outreach activities will specifically target improvement of the image of European aquaculture and uptake of outputs by regulators, while promoting an integrated sustainable strategy for development.

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