Determining a Function for the Damping Coefficient of a laminated Stack

The design of electrical machines is determined by electrical as well as mechanical requirements. Possible lossesdue to eddy currents in the stator or the rotor are commonly reduced by using stacks of laminated sheet metal. On the other hand, the design of the stator and the rotor has a significant influence on the mechanical properties: Vibrations depend on the stiffness and the damping of the laminated stack. There are different methods to determine the stiffness coefficient of a stack, but it is much more difficult to obtain suitable values for the damping as there are more influencing factors. This paper describes an experimental procedure, which determines the influence of different parameters on the damping of a stack. The stack used during the experiments consists of 200 quadratic steel sheets with a side length of 80 mm and a thickness of 0.5 mm. In accordance with the measurement data, a functional dependance based on three variables is derived. The first one is the surface pressure between the steel sheets, the second one is the frequency of the applied lateral force, and the third one is the displacement between the steel sheets. It is the aim of this investigation to determine the influence of variations of these parameter values on the damping. The forces are applied onto the stack with hydraulic cylinders. The mechanical deformation of the stacked metal sheets is measured by a laser-speckle-based measurement system. This system detects the displacement of single steel sheets. The displacement is measured on two steel sheets, but they are not side by side. The difference between the two measurement points is equal to the displacement of the stack. Through the synchronization of the time signal of the lateral force and the displacement of the stack, a hysteresis loop can be calculated. This hysteresis depends on the lateral force and the displacement of the stack. The area of the hysteresis corresponds to the dissipation energy between the two measurement points on the stack, 140 sheets apart from each other. This area is calculated by numerical integration based on the trapezoidal rule. Through the conservation of energy for this system, it is possible to calculate an effective damping coefficient for the stack. Considering different influencing parameters, a function for the damping coefficient can be identified by the least square method. This function can be used for the parameters in a numerical simulation of an electrical machine

Production of exotic atoms at energies available at the CERN Large Hadron Collider

We study in details the space-time dependence of the production of muonic, pionic, and other exotic atoms by the coherent photon exchange between nuclei at the Large Hadron Collider at CERN. We show that a multipole expansion of the electromagnetic interaction yields an useful insight of the bound-free production mechanism which has not been explored in the literature. Predictions for the spatial, temporal, and angular distribution, as well as the total cross sections, for the production of exotic atoms are also included.Comment: 8 pages, 5 figures, version published in the Physical Review

Spatial, Temporal and Vertical Distribution of Ammonia Concentrations Over Europe – Comparing a Static and Dynamic Approach With WRF-Chem

The study focuses on the application of a dynamic ammonia emission into the Weather Research and Forecasting Chemistry model (WRF-Chem) and the influence on the simulated ammonia concentrations and the overall model performance. We have focused on agricultural ammonia sources and have analysed both hourly and daily patterns of ammonia emissions and concentrations at measurement sites located in agricultural areas or influenced by this activity. For selected episodes, we have also investigated the 3-D patterns of the ammonia concentrations in the atmosphere. The application of the dynamic ammonia emission into the WRF-Chem model (the “DYNAMIC” simulation) results in an improvement of the modelled daily ammonia concentrations in comparison to a static approach (the “BASE” simulation), which is currently widely used in chemical transport models. In the case of hourly resolution, we have observed an improvement for the DYNAMIC approach for the winter and autumn seasons, but for the entire year the modelled hourly ammonia peaks are shifted toward the afternoon hours if compared with measurements. This study indicates that the current description of the diurnal cycle of the ammonia concentration from fields is not accurate and more research is needed in order to improve the processes that describe the emission from fertilised fields. The results suggest that the governing processes in relation to the diurnal cycle are the atmospheric mixing and the emission strength. Therefore,an improved description of the diurnal profile of ammonia concentrations within atmospheric models requires a better description of the planetary boundary layer height and a stronger daily pattern of ammonia emission, e.g. through increased evaporation or increased fluxes from the surface

Ammonia Concentrations Over Europe – Application of the WRF-Chem Model Supported With Dynamic Emission

The study focuses on the application of a static and dynamic ammonia emission based on a Europe-wide default setting into the Weather Research and Forecasting Chemistry model (WRF-Chem) and the influence on the simulated ammonia concentrations and the overall model performance. The WRF-Chem model was run twice for the entire Europe at a spatial resolution of 36 x 36 km for the year 2012. In the first simulation we used a static emission approach (the “BASE” simulation), whereas in the second simulation, dynamic ammonia emissions were used (the “DYNAMIC” simulation). Both simulations underestimate measured concentrations of NH3 for all seasons, have similar NMGE (about 0.7 μg m-3) and modelled hourly ammonia peaks are shifted towards the afternoon hours if compared with measurements. However, for all temporal resolutions, normalised mean gross error in winter and summer is lower for DYNAMIC than for BASE. The DYNAMIC simulation also generally gives worse performance in spring for each temporal resolution. For further improvement of the modelled ammonia concentrations with WRF-Chem we suggest to use a nested approach with higher spatial resolution, which will lead to better separation of the ammonia source regions from surrounding areas, and take into account national practice and regulations in the emission model, eventually only in the nested model domain

Effect of IL-4 and IL-13 on IFN-γ-induced production of nitric oxide in mouse macrophages infected with herpes simplex virus type 2

AbstractInterleukin (IL)-4 and IL-13 share a wide range of activities. Prominent among these is the ability to antagonize many interferon (IFN)-γ-induced activities. Here we demonstrate that IL-4 and IL-13 totally abrogate IFN-γ-induced nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) mRNA and protein synthesis in a murine macrophage cell line. IFN-γ-treated cells infected with herpes simplex virus type 2 (HSV-2) or costimulated with tumor necrosis factor (TNF)-α showed an enhanced reactivity, which was only partially reduced by IL-4/13. The results indicate that IL-4 and IL-13 function by intervening with a step prior to iNOS transcription by antagonizing IFN-γ-induced signal(s) without counteracting synergistic virus- or TNF-α-induced signals. The beneficial effect of a sustained NO production in foci of virus infection is suggested

Identifying content to improve risk assessment communications within the Risk Profile: Literature reviews and focus groups with expert and non-expert stakeholders

Objective: To improve consumer decision making, the results of risk assessments on food, feed, consumer products or chemicals need to be communicated not only to experts but also to non-expert audiences. The present study draws on evidence from literature reviews and focus groups with diverse stakeholders to identify content to integrate into an existing risk assessment communication (Risk Profile). Methods: A combination of rapid literature reviews and focus groups with experts (risk assessors (n = 15), risk managers (n = 8)), and non-experts (general public (n = 18)) were used to identify content and strategies for including information about risk assessment results in the “Risk Profile” from the German Federal Institute for Risk Assessment. Feedback from initial focus groups was used to develop communication prototypes that informed subsequent feedback rounds in an iterative process. A final prototype was validated in usability tests with experts. Results: Focus group feedback and suggestions from risk assessors were largely in line with findings from the literature. Risk managers and lay persons offered similar suggestions on how to improve the existing communication of risk assessment results (e.g., including more explanatory detail, reporting probabilities for individual health impairments, and specifying risks for subgroups in additional sections). Risk managers found information about quality of evidence important to communicate, whereas people from the general public found this information less relevant. Participants from lower educational backgrounds had difficulties understanding the purpose of risk assessments. User tests found that the final prototype was appropriate and feasible to implement by risk assessors. Conclusion: An iterative and evidence-based process was used to develop content to improve the communication of risk assessments to the general public while being feasible to use by risk assessors. Remaining challenges include how to communicate dose-response relationships and standardise quality of evidence ratings across disciplines.Peer Reviewe

Spatial and temporal variations in ammonia emissions – a freely accessible model code for Europe

Deriving a parameterisation of ammonia emissions for use in chemistry-transport models (CTMs) is a complex problem as the emission varies locally as a result of local climate and local agricultural management. In current CTMs such factors are generally not taken into account. This paper demonstrates how local climate and local management can be accounted for in CTMs by applying a modular approach for deriving data as input to a dynamic ammonia emission model for Europe. Default data are obtained from information in the RAINS system, and it is demonstrated how this dynamic emission model based on these input data improves the NH<sub>3</sub> calculations in a CTM model when the results are compared with calculations obtained by traditional methods in emission handling. It is also shown how input data can be modified over a specific target region resulting in even further improvement in performance over this domain. The model code and the obtained default values for the modelling experiments are available as supplementary information to this article for use by the modelling community on similar terms as the EMEP CTM model: the GPL licencse v3