Model Order Reduction applied to a linear Finite Element model of a squirrel cage induction machine based on POD approach

The Proper Orthogonal Decomposition (POD) approach is applied to a linear Finite Element (FE) model of a squirrel cage induction machine. In order to obtain a reduced model valid on the whole operating range, snapshots are extracted from the simulation of typical tests such as at locked rotor and at the synchronous speed. Then, the reduced model of the induction machine is used to simulate different operating points with variable rotation speed and the results are compared to the full FE model to show the effectiveness of the proposed approach

Model Order Reduction for Rotating Electrical Machines

The simulation of electric rotating machines is both computationally expensive and memory intensive. To overcome these costs, model order reduction techniques can be applied. The focus of this contribution is especially on machines that contain non-symmetric components. These are usually introduced during the mass production process and are modeled by small perturbations in the geometry (e.g., eccentricity) or the material parameters. While model order reduction for symmetric machines is clear and does not need special treatment, the non-symmetric setting adds additional challenges. An adaptive strategy based on proper orthogonal decomposition is developed to overcome these difficulties. Equipped with an a posteriori error estimator the obtained solution is certified. Numerical examples are presented to demonstrate the effectiveness of the proposed method

Matrix Interpolation-Based Reduced-Order Modeling of a Levitation Device With Eddy Current Effects

EU In this paper, reduced order modeling (ROM) based on the proper orthogonal decomposition (POD) are applied to an eddy-current problem with movement. A classical magnetodynamic finite-element formulation based on the magnetic vector potential is used as reference and starting point to build up the reduced models. Two approaches are proposed to construct the ROMs: 1) the so-called classical POD-ROM and 2) the parametric POD-ROM by the matrix interpolation method. The latter is found to be highly computationally efficient (time and memory) when dealing with repetitive computations, such as design, control, and optimization procedures. The Team Workshop Problem 28 is chosen as a test case for validation. The results are compared in terms of accuracy and computational cost.status: publishe

Corrigendum to “Application of oil palm empty fruit bunch effects on soil biota and functions: A case study in Sumatra, Indonesia” [Agric. Ecosyst. Environ. 256 (2018) 105–113]

The authors regret that the first sentence in Section 3.2 “A total of 168 earthworms were collected, with a mean density of 1344 ind m−2”, should be corrected to “A total of 168 earthworms were collected, with a mean density of 13.44 ind m−2”. The authors would like to apologise for any inconvenience cause

Application of oil palm empty fruit bunch effects on soil biota and functions:A case study in Sumatra, Indonesia

Oil palm (Elaeis guineensis) is an important tropical crop which provides one-fifth of the world’s vegetable oil, yet its rapid expansion can negatively influence the soil ecosystem. Identifying suitable agronomic management such as crop residue application is important for the sustainable development of oil palm. We examined the effects of adding empty fruit bunches (EFB), a major oil palm residue, on multiple soil abiotic properties, soil biota, and indicators of soil functions. We compared treatments of EFB applications with three application rates, and a chemical fertilizer treatment in a 15–year trial in Central Sumatra, Indonesia. EFB application increased pH and aggregate stability in 0–10 cm soils and decreased the soil bulk density. EFB application increased the abundance of soil detritivore mites, soil fauna feeding activity, and soil microbial activity. EFB application decreased the biomass of a dominant invasive earthworm species, Pontoscolex corethrurus (Müller, 1857). Results from structural equation modelling suggested that EFB directly affected soil biota and functions, rather than through altering soil abiotic properties. The effects of EFB application on most soil abiotic properties, soil biota and function indicators were independent of the application rate. Our results revealed that EFB application has a high potential to enhance soil biota and functions in oil palm plantations

Outbreak of urogenital schistosomiasis in Corsica (France): an epidemiological case study

International audienceBackground: Schistosomiasis is a snail-borne parasitic disease endemic in several tropical and subtropical countries. However, in the summer of 2013, an unexpected outbreak of urogenital schistosomiasis occurred in Corsica, with more than 120 local people or tourists infected. We used a multidisciplinary approach to investigate the epidemiology of urogenital schistosomiasis in Corsica, aiming to elucidate the origin of the outbreak.Methods: We did parasitological and malacological surveys at nine potential sites of infection. With the snails found, we carried out snail–parasite compatibility experiments by exposing snails to schistosome larvae recovered from the urine of a locally infected Corsican patient. Genetic analysis of both mitochondrial (cox1) and nuclear (internal transcribed spacer) DNA data from the Schistosoma eggs or miracidia recovered from the infected patients was conducted to elucidate the epidemiology of this outbreak.Findings: We identified two main infection foci along the Cavu River, with many Bulinus truncatus snails found in both locations. Of the 3544 snails recovered across all sites, none were naturally infected, but laboratory-based experimental infections confirmed their compatibility with the schistosomes isolated from patients. Molecular characterisation of 73 eggs or miracidia isolated from 12 patients showed infection with Schistosoma haematobium, S haematobium–Schistosoma bovis hybrids, and S bovis. Further sequence data analysis also showed that the Corsican schistosomes were closely related to those from Senegal in west Africa.Interpretation: The freshwater swimming pools of the Cavu River harbour many B truncatus snails, which are capable of transmitting S haematobium-group schistosomes. Our molecular data suggest that the parasites were imported into Corsica by individuals infected in west Africa, specifically Senegal. Hybridisation between S haematobium and the cattle schistosome S bovis had a putative role in this outbreak, showing how easily and rapidly urogenital schistosomiasis can be introduced and spread into novel areas where Bulinus snails are endemic, and how hybridisation could increase the colonisation potential of schistosomes. Furthermore our results show the potential risk of schistosomiasis outbreaks in other European areas, warranting close monitoring and surveillance of all potential transmission foci