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Van Dessel M.,Campus de Nayer | Van Ham G.,KH Kempen | Deconinck G.,Catholic University of Leuven | Nobels T.,Groep T Leuven Hogeschool | And 3 more authors.
Proceedings - ICELIE 2010, 4th IEEE International Conference on E-Learning in Industrial Electronics | Year: 2010

Ever more students start their master programme with a bachelor degree which does not provide the ideal background for their study. Such students benefit from dedicated help when they have to master advanced topics in automation, control and electrical engineering. Because individual help is adequate but too labour-intensive, a self-study package has been developed by which individual students can select an optimal path to update their required knowledge -depending on their foregoing trajectory- and acquire the required competencies. Topics cover electrical systems (medium and high voltage, power protection, power quality), power electronics (prototyping, electromagnetic compatibility), automation (drive control, drive efficiency, industrial networks and diagnosis). The guided self-study approach consists of a handbook and a digital learning platform; practical hands-on laboratories take place, distributed over several university colleges. A final assessment checks whether students obtained the required competencies. Approximately 12 groups of students, from 9 programmes in 7 institutions, cover 25 topics and laboratory visits yearly. ©2010 IEEE.

Karg C.,KHBO | Karg C.,Ghent University | Francois S.,Catholic University of Leuven | Haegeman W.,KHBO | And 3 more authors.
Soil Dynamics and Earthquake Engineering | Year: 2010

Repeated small amplitude dynamic loading of the soil in the vicinity of buildings, as arising from traffic or construction activities, may cause differential foundation settlements and structural damage. In this paper, an accumulation model for settlements due to vibrations at small strain levels in granular non-cohesive soils is proposed. It is assumed that the dynamic part of the stresses is small with respect to the static part. As plastic deformation in the soil is only observed after a considerable amount of dynamic loading cycles, only the accumulation of the average plastic deformation is considered. The model accounts for the dependency of the deformation on the stress state, the void ratio, and the dynamic loading amplitude. The model is calibrated for homogeneous fine grained sands with the aid of cyclic triaxial test results. © 2010 Elsevier Ltd.

Deschrijver D.,Ghent University | Pissoort D.,KHBO | Pissoort D.,Agilent Technologies | Dhaene T.,Ghent University
2010 IEEE 14th Workshop on Signal Propagation on Interconnects, SPI 2010 - Proceedings | Year: 2010

In this paper, a novel adaptive stopping criterion for FDTD simulations of microwave components is applied to a package example. The new stopping criterion relies on the Vector Fitting algorithm to successively build an updated macromodel for the frequency response of the device under study based on increasing time-limited transient responses. In this way, it aims at minimizing the number of timesteps and, hence, the overall simulation time to capture the device's frequency response within a given frequency band up to a predefined accuracy level. © 2010 IEEE.

Hubacek A.,Brno University of Technology | Boehme L.,KHBO | Novakova I.,Brno University of Technology
Advanced Materials Research | Year: 2014

This paper presents some test-results of using fine recycled concrete as a partial replacement of natural aggregates in cement-based flowscreed. Special attention is given to describing and studying rheological characteristics and mechanical properties of cement-based flowscreed. Experimental results indicate that it is possible to prepare flowscreed with partial replacement of natural aggregates by recycled aggregates and obtain a quality that meets the requirements. This study was partially connected to the research-project RecyFlowscreed [1]. © (2014) Trans Tech Publications, Switzerland.

Van Den Bossche J.,Catholic University of Leuven | Vermeyen A.,Catholic University of Leuven | Schyvinck E.,Catholic University of Leuven | Danckaert E.,Catholic University of Leuven | And 5 more authors.
Proceedings of the 40th SEFI Annual Conference 2012 - Engineering Education 2020: Meet the Future | Year: 2012

Research in Flanders shows that only 40% of the 47.000 students who started higher education acquired all of the 60 credits during the academic year 2007-2008 [1]. This tendency even seems to continue. This is partly due to a wrong choice of study [2]. Better support for making the right choice before the start and/or re-orientation a few weeks after the start of the term seems to be more necessary than ever. But is it possible to predict the chances of success? A lot of research on the prediction of study results is found in literature [3], [4], [5], [6]. Most of these studies were USA studies based on the SAT (Scholastic Aptitude Test) test. We examined three possible (cognitive) tests that could be used for making a better choice before start or for re-orientation after a few weeks. We focused on industrial engineering students in Flanders (Belgium). The first and second test are non-obligatory tests for students before the start of the study. These tests examine elementary scientific and math skills. During this pilot test phase, these tests were offered at the start of the academic year. In Ref. [7] these tests can be found.The third test was a test that took place a few weeks after the start of the semester. The study material is part of the curriculum. This test can be used for re-orientation a few weeks after the start of the academic year. The relationship between exam result and score on the different tests was investigated using Spearman's Rank-Order Correlation coefficient (rs). There is a small correlation in case of test 1 (rs=0,175), a medium correlation in test 2 (rs=0,472) and a large correlation in test 3 (rs=0,675). Using test 1, we can not advise students to start the engineering study or not. In case of test 2, we get a much higher correlation coefficient, but even then, we can not advise students. The only test which we slightly can rely on to advise students is test 3. What's the reason for the low correlation in case of test 1? And why is the correlation higher in test 2 and test 3? In this paper we will give some possible explanations. Further research is certainly needed.

Boehme L.,Catholic University College of Bruges-Ostend | Joseph M.,KHBO | Anseele T.,KHBO | Verstraete S.,KHBO
CESB 2013 PRAGUE - Central Europe Towards Sustainable Building 2013: Sustainable Building and Refurbishment for Next Generations | Year: 2013

The research-program 'ValReCon20' proved the possibility to replace 100 % of the coarse original aggregates with recycled concrete aggregates (RCA) in concrete mixtures in the strength class C25/30. An important consideration is that the W/C-ratio must be limited by use of water-reducing admixtures: superplasticisers. This article discusses the findings of a study on the impact on the workability of recycling concrete using a polycarboxylate based superplasticiser. The research is mainly focused on the time of addition of the superplasticiser and the soaking condition of RCA. It is concluded that not soaking the RCA results initially in more free water, coming from the extra water added to compensate the absorption, so that the superplasticiser is activated more slowly. The rate of activation of the superplasticiser and the amount of water are linked to each other.

Boehme L.,Catholic University College of Bruges-Ostend | Joseph M.,KHBO | Simons M.,KHBO | Verduyn J.,KHBO
CESB 2013 PRAGUE - Central Europe Towards Sustainable Building 2013: Sustainable Building and Refurbishment for Next Generations | Year: 2013

During the production of precast concrete rubble arises from production residues, form errors and damages. Usually this concrete rubble is being collected throughout the year and stockpiled on the manufacturer's site. Only when there is a sufficiently large amount of concrete debris is present, a mobile crusher hired to crush the hardened concrete rubble into recycled concrete aggregates. Such crushing campaign is organized once or twice a year. At that moment the concrete rubble has already fully cured and the cement has largely hydrated. This paper shows that it can be beneficial to use the residual binding present in recycled concrete aggregates, derived from concrete residues crushed at early age, and recycle the RCA in fresh concrete. The compressive strength of the recycled concrete increased with 10 % at a replacement rate of 30 %. Since crushing young concrete, which is weaker, requires less energy and aiming at the same required compressive strength as the original concrete could lead to a small reduction of the cement needed in the recycled concrete mixture, these finding contribute to finding solutions for a more sustainable concrete production industry.

Sabuncuoglu B.,IMEC | Sabuncuoglu B.,Catholic University of Leuven | Vanhee F.,KHBO | Willems G.,IMEC | And 4 more authors.
2012 13th International Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems, EuroSimE 2012 | Year: 2012

In this study, the fatigue performance of solder joints in four point bending test was evaluated by a novel finite-element modeling method. A simplified modeling technique was implemented in order to focus on the behavior of the critical solder joint. The fatigue life was estimated by taking into account the creep behavior of solder joints. Morrow's fatigue model was utilized to determine the fatigue life. The results were compared with the ongoing test results. Some additional studies were performed in order to observe the reliability of the modeling method and the effect test parameters. © 2012 IEEE.

Cordemans P.,KHBO | Van Landschoot S.,KHBO | Boydens J.,KHBO | Steegmans E.,Catholic University of Leuven
Studies in Computational Intelligence | Year: 2014

Due to embedded co-design considerations, testing embedded software is typically deferred after the integration phase. Contrasting with the current embedded engineering practices, Test-Driven Development (TDD) promotes testing software during its development, even before the target hardware becomes available. Principally, TDD promotes a fast feedback cycle in which a test is written before the implementation. Moreover, each test is added to a test suite, which runs at every step in the TDD cycle. As a consequence, test-driven code is well tested and maintainable. Still, embedded software has some typical properties which impose challenges to apply the TDD cycle. Essentially, uploading software to target is generally too time-consuming to frequently run tests on target. Secondary issues are hardware dependencies and limited resources, such as memory footprint or processing power. In order to deal with these limitations, four methods have been identified and evaluated. Furthermore, a number of relevant design patterns are discussed to apply TDD in an embedded environment. © 2014 Springer-Verlag Berlin Heidelberg.

PubMed | KHBO
Type: Journal Article | Journal: Journal of agricultural and food chemistry | Year: 2012

As steviol glycosides are now allowed as a food additive in the European market, it is important to assess the stability of these steviol glycosides after they have been added to different food matrices. We analyzed and tested the stability of steviol glycosides in semiskimmed milk, soy drink, fermented milk drink, ice cream, full-fat and skimmed set yogurt, dry biscuits, and jam. The fat was removed by centrifugation from the dairy and soy drink samples. Proteins were precipitated by the addition of acetonitrile and also removed by centrifugation. Samples of jam were extracted with water. Dry biscuits were extracted with ethanol. The resulting samples were concentrated with solid-phase extraction and analyzed by high-performance liquid chromatography on a C18 stationary phase and a gradient of acetonitrile/aqueous 25 mM phosphoric acid. The accuracy was checked using a standard addition on some samples. For assessing the stability of the steviol glycosides, samples were stored in conditions relevant to each food matrix and analyzed periodically. The results indicate that steviol glycosides can be analyzed with good precision and accuracy in these food categories. The recovery was between 96 and 103%. The method was also validated by standard addition, which showed excellent agreement with the external calibration curve. No sign of decomposition of steviol glycosides was found in any of the samples.

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