ParisTech

About: ParisTech is a education organization based out in Paris, France. It is known for research contribution in the topics: Finite element method & Residual stress. The organization has 1888 authors who have published 1965 publications receiving 55532 citations. The organization is also known as: Paris Institute of Technology & ParisTech Développement.

MMC Stored Energy Participation to the DC Bus Voltage Control in an HVDC Link

Abstract: The modular multilevel converter (MMC) is becoming a promising converter technology for HVDC transmission systems. Contrary to the conventional two- or three-level VSC-HVDC links, no capacitors are connected directly on the dc bus in an MMC-HVDC link. Therefore, in such an HVDC link, the dc bus voltage may be much more volatile than in a conventional VSC-HVDC link. In this paper, a connection between the dc bus voltage level and the stored energy inside the MMC is proposed in order to greatly improve the dynamic behavior in case of transients. EMT simulation results illustrate this interesting property on an HVDC link study case.

Coffee, mines and dams: conflicts over land in the Bolaven Plateau, southern Lao PDR

Abstract: During the last decades, neoliberal economic reforms aiming at facilitating trade and crossboundary investment have encouraged transnational and national economic actors to search for ‘empty’ land to grow export crops, to mine, or to develop hydroelectric dams. Mainland Southeast Asia is one of the regions where such investment has been taking place as it contains resourcehungry countries (Thailand and in particular neighbouring China), and countries with ‘empty’ land and the willingness to use such land to foster economic growth (Laos, Cambodia and Burma). This beset the question as to what happens to the people who inhabit the land that is supposed to be ‘empty’, and the relationship between the different land uses that takes over that ‘empty’ land. This paper describes the land conflicts in one area in southern Laos, the Bolaven Plateau, where national and international capital backing large-scale coffee plantation, bauxite mining and dam construction is displacing smallholding coffee farmers – the ‘traditional’ land users – within a political environment of poorly enforced property rights and endemic corruption. We describe how the smallholding coffee farmers are relocated to make way for the new economic activities supported by considerable amounts of foreign capital, and how the land grabbing results in lower standards of living for the smallholding coffee farmers, with few benefits to the country as a whole.

Porcine model of early onset scoliosis based on animal growth created with posterior mini-invasive spinal offset tethering A preliminary report

Abstract: Several models of scoliosis were developed in the past 10 years. In most of them, deformations are induced in old animals and required long time observation period and a chest wall ligation ± resection. The purpose of the study was to create a scoliosis model with a size similar to an early onset scoliosis and an important growth potential without chest wall injuring. An original offset implant was fixed posteriorly and connected with a cable in seven (6 + 1 control) one-month-old Landrace pigs. The mean initial spinal length (T1-S1) was 25 cm and the mean weight was 9 kg. After 2 months observation, spinal deformities were assessed with a three dimension stereographic analysis. In four animals, the cable was sectioned and the deformities followed-up for next 2 months. No post-operative complication was observed. Mean weight growth was 10 kg/month and mean spine lengthening (T1-S1) was 7 cm/month. In 2 months, we obtained structural scoliotic curves with vertebral and disk wedging which were maximal at the apex of the curve. Mean frontal and sagittal Cobb angles was 45°. Chest wall associated deformities were similar to those observed in scoliotic deformities and were correlated to spinal deformities (p = 0.03). The cable section resulted in a partial curve regression influenced by disk elasticity and could probably be influenced by gravity loads (Decrease of the Cobb angle of 30% in the sagittal plane and 45% in the frontal plane). According to the results, the model creates a structural scoliosis and chest wall deformity that is similar to an early onset scoliosis. The spinal deformities were obtained quickly, and were consistent between animals in term of amount and characteristic.

An automated quantification of the transmural myocardial infarct extent using cardiac DE-MR images

Abstract: Evaluating myocardial viability is an important prognostic factor in the follow-up of infarctions. Delayed Enhancement magnetic resonance (DE-MR) imaging allows precise delineation of the infarct transmural extent. Visual interpretation is the most commonly used method to assess the myocardial infarction (MI) transmural extent. This study proposes to automate the segmentation of the (DE) images prior to the estimation of the extent of infarcted tissue. Indeed the segmentation of the myocardium was performed using cine contraction images which present a high contrast between cavity and myocardium. After the segmentation, the segmental transmurality is estimated on a conventional five point scale. A head to head comparison was performed between visual and quantitative analysis of infarct transmurality on DE-MR imaging. Results on 921 sub-segments (9 patients) showed an absolute agreement of 80% and a relative agreement (with one point difference) of 97%.