Study of ITER equatorial port plug handling system and vacuum sealing interface

In the field of the ITER port plug engineering and integration task, CEA has contributed to define proposals concerning the port plugs vacuum sealing interface with the vessel flange and the equatorial plug handling.The 2001 baseline vacuum flange sealing consisted of TIG welding of a 316L strip plate on to U shapes. This arrangement presented some issues like welding access, implementation of tools, lip consumption, complex local leak test, continuous leak checking. Therefore, an alternate sealing solution based on the use of metallic gaskets is proposed. The different technical aspects are discussed to explain how this design can simplify the maintenance and deal with safety and vacuum requirements.The design of the mechanical attachment and vacuum sealing of the plug has constantly evolved, but the associated remote handling equipment was not systematically reviewed. An update of the cask and maintenance procedure was studied in order to design it in accordance with the last generic plug flange design. This includes a concept of a gripping system that uses the plug flange bolting area and, to help the remote handling process, a cantilever assisting system is suggested to increase the reliability of the transfer operation between vacuum vessel and cask.     

Fourier transform infra-red study of uniaxially-oriented isotactic polystyrene

Fourier transform infra-red measurements have been made of the orientation in isotactic polystyrene as a function of draw ratio. Based on these results, new band assignments are made and orientation functions calculated.     

Anisotropic mechanical behavior of magnetically oriented iron particle reinforced foams

Reinforced foams were prepared by exposing a polyurethane matrix filled with iron particles to a magnetic field during the foaming process. The magnetic field induced an alignment of the iron particles along the field direction, giving rise to columnar structures similar to fibrils, as observed by SEM and microtomographic 3D reconstructions. The anisotropic reinforcement induced by the fibrils improved the mechanical performances, yielding a threefold increase of both elastic modulus and yield stress in the alignment direction, whereas minor effects were observed in the transversal direction. In this case, the mechanical properties were comparable with those of randomly filled foams or, in some cases, of unfilled foam. The reinforcing efficiency of fibrils was evaluated through a theoretical model, based on the combination of the mechanics of foams with two micromechanical models for aligned short fibers composites (Halpin‐Tsai and Cox‐Krenchel). The theoretical predictions based on the Halpin‐Tsai equations showed a good agreement with the experimental data, whereas the model derived from Cox‐Krenchel equations overestimated data. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Interaction diagrams for carbon nanotubes under combined shortening-twisting

A theoretical investigation on the strength and stiffness of carbon nanotubes (CNTs) under combined shortening and twisting strains is presented. CNTs with similar length-to-diameter aspect ratios, L/D, but different atomic structures (zig-zag, armchair and chiral) have been selected. Molecular dynamics (MD) simulations have been performed to study the critical buckling behaviour and the pre-critical and post-critical stiffness of CNTs under combined shortening-twisting conditions. The main results are presented in the form of interaction diagrams between the critical strain and the critical angle of twist per unit of length. An interaction equation is proposed and validated by comparison with the MD results. If shortening is more dominant than twisting, the strain energy at the onset of buckling drops considerably with the increase of the twisting-shortening rate. If twisting is more influential than shortening, the energy at the onset of buckling decreases very slowly with the twisting-shortening rate. We also found an interaction factor of 1.5 for CNTs under combined shortening-twisting, which is much lower than the value 2.0 commonly adopted for circular tubes at macro-scale. We conclude that CNTs are much more sensitive to buckling under shortening-twisting interaction than macro-scale tubes.     

Numerical model of a planar jet wiping system for continuous strip lines

Journal of Mechanical Science and Technology - The present study focuses on the numerical modelling of gas-jet wiping process. Many processes involving liquids are necessary during steel...     

Examination of the Aging Effects of Silicone Molds During Vacuum Casting Processes via Scanning Electron Microscopy

We present an in-depth investigation of contaminated silicone molds by use of scanning electron microscopy, that provides additional insight into the aging process of the molds. The molds lifetime in vacuum casting processes of polyurethane is limited due to contamination with the diisocyanate compound of the PUR resin. SEM investigations, combined with FIB cross-sections and EDX measurements show that three different types of particles are distributed in the contaminated silicone matrix. The particles differ in shape and size, with a range from 50 nm to 50 µm. This explains the loss in transparency and the hardened haptics of contaminated molds.     

SETTLING ALONG,WITH, AND ON WATER IN THUA THIEN HUE,VIETNAM: PAST,PRESENT, AND FUTURE

This paper develops a water-based spatial biography of the Thua Thien Hue Province in Vietnam’s Central Highlands and critically interprets the territory’s intertwined contemporary challenges — a growing population, greater demands on agriculture, fisheries, and aquaculture, tourism and changes in annual rainwater, and sea level regimes. It is structured by four sections (typical geography and exceptional ecology, diverse settlement typologies, curse and perils of water, contemporary challenges) which interpretatively read the context. Historical analysis and mapping of present-day projects in the pipeline are complemented by extensive fieldwork in an attempt to reveal (and later build upon) the logics of the territory. It concludes with a series of projective design strategies developed by Research Urbanism and Architecture for the Thua Thien Hue Province Peoples’ Committee and the Hanoi-based investor Van Phu, which attempt to balance ecology with economy with a focus on lagoon restoration and new city and settlement types (for the living and the dead) which respond to the predicted consequences of climate change (particularly severe flooding). The project is premised on policy shifts from hardengineering to approaches that work as much as possible with natural means to simultaneously restore ecologies and generates opportunities to embed new sustainable economies. Not surprisingly, water urbanism strategies are key to this envisioned future development of the province.     

Bleeding and Thrombosis: Insights into Pathophysiology of Bothrops Venom-Related Hemostasis Disorders

Toxins from Bothrops venoms targeting hemostasis are responsible for a broad range of clinical and biological syndromes including local and systemic bleeding, incoagulability, thrombotic microangiopathy and macrothrombosis. Beyond hemostais disorders, toxins are also involved in the pathogenesis of edema and in most complications such as hypovolemia, cardiovascular collapse, acute kidney injury, myonecrosis, compartmental syndrome and superinfection. These toxins can be classified as enzymatic proteins (snake venom metalloproteinases, snake venom serine proteases, phospholipases A₂ and L-amino acid oxidases) and non-enzymatic proteins (desintegrins and C-type lectin proteins). Bleeding is due to a multifocal toxicity targeting vessels, platelets and coagulation factors. Vessel damage due to the degradation of basement membrane and the subsequent disruption of endothelial cell integrity under hydrostatic pressure and tangential shear stress is primarily responsible for bleeding. Hemorrhage is promoted by thrombocytopenia, platelet hypoaggregation, consumption coagulopathy and fibrin(ogen)olysis. Onset of thrombotic microangiopathy is probably due to the switch of endothelium to a prothrombotic phenotype with overexpression of tissue factor and other pro-aggregating biomarkers in association with activation of platelets and coagulation. Thrombosis involving large-caliber vessels in B. lanceolatus envenomation remains a unique entity, which exact pathophysiology remains poorly understood.