The Swiss Federal Laboratories for Materials Science and Technology is an interdisciplinary Swiss research and service institution for applied materials science and technology. As part of the Swiss Federal Institutes of Technology Domain, it is an institution of the Swiss federation. For most of the period since its foundation in 1880, it concentrated on classical materials testing. Since the late 1980s it has developed into a modern research and development institute. Wikipedia.
Weber F.,Empa - Swiss Federal Laboratories for Materials Science and Technology
Smart Materials and Structures | Year: 2013
A Bouc-Wen model-based control scheme is presented which allows tracking the desired control force in real-time with magnetorheological (MR) dampers without feedback from a force sensor. The control scheme estimates the MR damper force by parallel computing of several Bouc-Wen models with different constant currents as inputs and for the actual MR damper displacement and velocity, respectively. Based on the estimated forces and the desired control force the MR damper current is determined by a piecewise linear interpolation scheme. The model-based feed-forward control scheme is numerically and experimentally validated. If the desired control force is not constrained by the pre-yield region, residual force at 0 A and force at maximum current, the very small force tracking error ≤0.0015 in the simulation is caused by the control-oriented simplification of the linear interpolation scheme. The tests reveal that the real-time control scheme is numerically stable and the force tracking error of ≤0.078 represents an acceptable accuracy. © 2013 IOP Publishing Ltd. Source
Weber F.,Empa - Swiss Federal Laboratories for Materials Science and Technology
Mechanical Systems and Signal Processing | Year: 2014
A semi-active vibration absorber with real-time controlled magnetorheological damper (MR-SVA) for the mitigation of harmonic structural vibrations is presented. The MR damper force targets to realize the frequency and damping adaptations to the actual structural frequency according to the principle of the undamped vibration absorber. The relative motion constraint of the MR-SVA is taken into account by an adaptive nonlinear control of the internal damping of the MR-SVA. The MR-SVA is numerically and experimentally validated for harmonic excitation of the primary structure when the natural frequency of the passive mass spring system of the MR-SVA is correctly tuned to the targeted structural resonance frequency and when de-tuning is present. The results demonstrate that the MR-SVA outperforms the passive TMD at structural resonance frequency by at least 12.4% and up to 60.0%. © 2014 Elsevier Ltd. Source
Westerhoff P.,Arizona State University |
Nowack B.,Empa - Swiss Federal Laboratories for Materials Science and Technology
Accounts of Chemical Research | Year: 2013
Engineered nanomaterials (ENMs) are a new class of environmental pollutants. Researchers are beginning to debate whether new modeling paradigms and experimental tests to obtain model parameters are required for ENMs or if approaches for existing pollutants are robust enough to predict ENM distribution between environmental compartments.This Account outlines how experimental research can yield quantitative data for use in ENM fate and exposure models. We first review experimental testing approaches that are employed with ENMs. Then we compare and contrast ENMs against other pollutants. Finally, we summarize the findings and identify research needs that may yield global descriptors for ENMs that are suitable for use in fate and transport modeling.Over the past decade, researchers have made significant progress in understanding factors that influence the fate and transport of ENMs. In some cases, researchers have developed approaches toward global descriptor models (experimental, conceptual, and quantitative). We suggest the following global descriptors for ENMs: octanol-water partition coefficients, solid-water partition coefficients, attachment coefficients, and rate constants describing reactions such as dissolution, sedimentation, and degradation. ENMs appear to accumulate at the octanol-water interface and readily interact with other interfaces, such as lipid-water interfaces. Batch experiments to investigate factors that influence retention of ENMs on solid phases are very promising. However, ENMs probably do not behave in the same way as dissolved chemicals, and therefore, researchers need to use measurement techniques and concepts more commonly associated with colloids. Despite several years of research with ENMs in column studies, available summaries tend to discuss the effects of ionic strength, pH, organic matter, ENM type, packing media, or other parameters qualitatively rather than reporting quantitative values, such as attachment efficiencies, that would facilitate comparison across studies. Only a few structure-activity relationships have been developed for ENMs so far, but such evaluations will facilitate the understanding of the reactivities of different forms of a single ENM.The establishment of predictive capabilities for ENMs in the environment would enable accurate exposure assessments that would assist in ENM risk management. Such information is also critical for understanding the ultimate disposition of ENMs and may provide a framework for improved engineering of nanomaterials that are more environmentally benign. © 2012 American Chemical Society. Source
Agency: Cordis | Branch: H2020 | Program: RIA | Phase: PHC-04-2015 | Award Amount: 6.83M | Year: 2016
Environmental heating is a growing challenge for our community and problems are already experienced by millions of Europeans during the summertime and aggravated during heat waves or occupational settings. In addition to the well-known health risks related to severe heat stress, a number of studies have confirmed significant loss of productivity due to hyperthermia. Even if countries adopt the EU proposal for limiting global CO2 emissions, climate change and its associated threat to public health will continue for many decades. Thus, it is crucial to develop strategies to mitigate the detrimental health and societal effects of these environmental changes. Stakeholders such as policy makers and the private sector usually lack the technical capabilities or facilities to conduct R&D activities at the level of excellence required for such development. European research institutes have the capacity to conduct the R&D necessary to develop solutions. However, they often lack the capacity to transform these solutions into policies and assess their health, economic and social benefits. The HEAT-SHIELD project will create a sustainable inter-sector framework that will promote health as well as productivity for European citizens in the context of global warming. The project will produce a series of state-of-the-art innovative outcomes including: (i) appropriate technical and biophysical research-based solutions to be implemented when the ambient temperature poses a health threat or impairs productivity (ii) a weather-based warning system with online open access service that anticipates the events that may pose a threat to workers health; (iii) scenario-specific policies and solutions aimed at health promotion and preventing loss of productivity (iv) implementation of the formulated policies and evaluation of their health, economic and social benefits. Consequently, the HEAT-SHIELD project provides a multi-sector approach to address the serious environmental challenge.
Agency: Cordis | Branch: H2020 | Program: IA | Phase: GV-3-2014 | Award Amount: 23.39M | Year: 2015
In order to realize sustainable mobility in Europe, both urban and long distance vehicles for road transport will have to be significantly more efficient by 2020\ and a considerable contribution will have to come from the energy efficiency improvement of the powertrain. Moreover, together with the progressive efficiency increase coming from the engine technology evolution, the use of Low-Carbon Alternative Fuels, such as Natural Gas, will play a fundamental role to accelerate the process of decarbonization of the transportation sector that in Europe is targeted for the 2050 time horizon. In this context, being well-known the benefits of the Natural Gas Vehicles adoption in Europe, this proposal aims to exploit the main benefits of gas-powered engines developing CNG-only, mono-fuel-engines able to comply with: post Euro 6 noxious emissions 2020\ CO2 emissions targets new homologation cycle and Real Driving conditions and simultaneously improving engine efficiency and vehicle performance also with regard to its CNG range capability. These engines, based on new combustion processes, require also dedicated technological solutions for: Innovative injection, ignition and boosting system concepts Advanced exhaust gas aftertreatment system Detecting the gas-quality and its composition The results obtained from the experimental activities on the demonstration vehicles and engines will be harmonized and analysed throughout a final overall assessment of the different approaches. The demonstrator vehicles will be assessed in terms of performance and emissions with regard to NEDC, WLTP and under real driving conditions. Moreover, the final assessment of the vehicles will be certified, as independent testing, by JRC (Joint Research Centre) which will carry out additional measurements in their own testing facilities both on chassis dyno and by means of PEMS (Portable Emissions Measurement System).