Influence of Rolling Element Bearing Modeling on the Predicted Thermal Behavior of the FZG Test Rig

A thermomechanical model of the FZG test rig is presented. The numerical model is based on the thermal network method and takes into account power losses due to tooth friction, rolling element bearings (REBs), oil churning, and shaft seals. Some measurements underline that REB rings run at different temperatures. To investigate this difference, several REB models are proposed and compared to measurements. Their influence on the global thermal behavior of the gear unit is discussed and analyzed.     

Guaranteed master for interval-based cosimulation

Software and Systems Modeling - In this paper, we tackle the problem of guaranteed simulation of cyber-physical systems, an important model for current engineering systems. Their is always...     

Automatic Stress Classification With Pupil Diameter Analysis

This article proposes a method based on wavelet transform and neural networks for relating pupillary behavior to psychological stress. The proposed method was tested by recording pupil diameter and electrodermal activity during a simulated driving task. Self-report measures were also collected. Participants performed a baseline run with the driving task only, followed by three stress runs where they were required to perform the driving task along with sound alerts, the presence of two human evaluators, and both. Self-reports and pupil diameter successfully indexed stress manipulation, and significant correlations were found between these measures. However, electrodermal activity did not vary accordingly. After training, the four-way parallel neural network classifier could guess whether a given unknown pupil diameter signal came from one of the four experimental trials with 79.2% precision. The present study shows that pupil diameter signal has good discriminating power for stress detection.     

Homogeneous Optical and Electronic Properties of Graphene Due to the Suppression of Multilayer Patches During CVD on Copper Foils

A synthesis method of strictly monolayer and fully homogeneous graphene across tens of centimeter squares, by chemical vapour deposition onto standard copper foils, is presented. The growth technique involves cyclic injection of a carbon precursor separated by idle times with constant hydrogen exposure. The formation of spurious multilayer patches, which accompanies the standard growth techniques based on continuous exposure to methane, is inhibited here, in a broad range of pressure and gas composition, including in two pressure regimes which are known to yield distinctive grain morphologies (dendritic versus hexagonal). Raman spectra confirm the absence of defects within the graphene films. A mechanism for growth/suppression of the multilayer patches based on the carbon storage at defective regions is proposed. The importance of multilayer suppression is highlighted in a comparative study showing the detrimental effect of patches on the performances of graphene transistors and on the optical transparency of stacked layers. The full‐layer graphene sheets are superiorly homogeneous in terms of their optical and electronic properties, and are thus suited for applications for high‐density integration as well as transparent electrodes with spatially continuous optical absorbance. Graphene transistors fabricated by the pulsed CVD method exhibit room‐temperature mobilities with a mean value of 5000 cm² V^?1 s^?1.     

Crystal Structure of HydG from Carboxydothermus hydrogenoformans: A Trifunctional [FeFe]‐Hydrogenase Maturase

The structure of the radical S‐adenosyl‐L ‐methionine (SAM) [FeFe]‐hydrogenase maturase HydG involved in CN^?/CO synthesis is characterized by two internal tunnels connecting its tyrosine‐binding pocket with the external medium and the C‐terminal Fe₄S₄ cluster‐containing region. A comparison with a tryptophan‐bound NosL structure suggests that substrate binding causes the closing of the first tunnel and, along with mutagenesis studies, that tyrosine binds to HydG with its amino group well positioned for H‐abstraction by SAM. In this orientation the dehydroglycine (DHG) fragment caused by tyrosine Cα?Cβ bond scission can readily migrate through the second tunnel towards the C‐terminal domain where both CN^? and CO are synthesized. Our HydG structure appears to be in a relaxed state with its C‐terminal cluster CysX₂CysX₂₂Cys motif exposed to solvent. A rotation of this domain coupled to Fe₄S₄ cluster assembly would bury its putatively reactive unique Fe ion thereby allowing it to interact with DHG.     

Genome-wide association study between copy number variants and hoof health traits in Holstein dairy cattle

Genome-wide association studies based on SNP have been completed for multiple traits in dairy cattle; however, copy number variants (CNV) could add genomic information that has yet to be harnessed. The objectives of this study were to identify CNV in genotyped Holstein animals and assess their association with hoof health traits using deregressed estimated breeding values as pseudophenotypes. A total of 23,256 CNV comprising 1,645 genomic regions were identified in 5,845 animals. Fourteen genomic regions harboring structural variations, including 9 deletions and 5 duplications, were associated with at least 1 of the studied hoof health traits. This group of traits included digital dermatitis, interdigital dermatitis, heel horn erosion, sole ulcer, white line lesion, sole hemorrhage, and interdigital hyperplasia; no regions were associated with toe ulcer. Twenty candidate genes overlapped with the regions associated with these traits including SCART1, NRXN2, KIF26A, GPHN, and OR7A17. In this study, an effect on infectious hoof lesions could be attributed to the PRAME (Preferentially Expressed Antigen in Melanoma) gene. Almost all genes detected in association with noninfectious hoof lesions could be linked to known metabolic disorders. The knowledge obtained considering information of associated CNV to the traits of interest in this study could improve the accuracy of estimated breeding values. This may further increase the genetic gain for these traits in the Canadian Holstein population, thus reducing the involuntary animal losses due to lameness.     

Global behaviour of a composite stiffened panel in buckling. Part 1: Numerical modelling

The present study analyses an aircraft composite fuselage structure manufactured by the Liquid Resin Infusion (LRI) process and subjected to a compressive load. LRI is based on the moulding of high performance composite parts by infusing liquid resin on dry fibres instead of prepreg fabrics or Resin Transfer Moulding (RTM). Actual industrial projects face composite integrated structure issues as a number of structures (stiffeners, …) are more and more integrated onto the skins of aircraft fuselage. A representative panel of a composite fuselage to be tested in buckling is studied numerically.     

The transfer of metallic contamination via contact between solid objects

The transfer of metallic contamination via solid contact is an almost non documented topic in the literature when compared to the spread through liquids which is has been intensively investigated for cleaning studies.This paper presents the transfer mechanisms of metallic aggregates from substrate to substrate though contact with tools used during wafer processing. In addition we propose models which agree with the experimental observations. The influence of several parameters on the transfer coefficients has been investigated, including the type of contamination (deposited films, particles…), the size or shape of the particle, the composition of the particle (metallic or dielectric), the substrate and the roughness and flatness of the plates used to hold the wafers during processing as well as the substrate surface composition (bare Si, oxidized…).The transfer of metals via the contact between solid objects only occurs from particular mechanisms. Not considering electrical forces, the first order parameter on the transfer is the particle size. Global transfer by contact occurs mainly in the 0.5-5 μm range and can be as high as 10%. For the second order, the parameters mentioned previously can affect the transfer of the particles, for example, an increase of the particle roughness induces an increase of the separation distance between particle and substrate which consequently decreases the Van der Waals interactions.     

Further clinical evaluations elicited by functional biological investigations in childhood autism

Data on the protective role of antioxidants in models of atherosclerosis are only partially confirmed in man. Observational and epidemiological data, as well as randomized trials, provide no clear cut indications, because of positive and disappointing results on the use of antioxidants in cardiovascular protection. Despite the lack of a general consensus, recent data reinforce the concept that the regular intake of antioxidants present in food limits the progression of atherosclerosis. When it is possible to monitor the efficacy of any antioxidant therapy with validated markers of oxidation, the potential influence of vitamins and antioxidants on coronary artery disease may eventually be resolved.     

Investigation on the properties of linear PLA-poloxamer and star PLA-poloxamine copolymers for temporary biomedical applications

The objective of this work was to develop and study new biodegradable thermoplastics with improved mechanical properties for potential use as temporary implantable biomaterials. Linear poloxamer and star-shaped poloxamine have been used as macroinitiators for the ring-opening polymerization (ROP) of lactide to yield high molecular weight PLA-based thermoplastic block copolymers. The influence of the nature of the macroinitiator, PLA crystallinity and initial molecular weight on the copolymers properties was investigated by performing a 7-week degradation test in PBS. The evaluation of water uptakes and molecular weights during the degradation pointed out an early hydrolytic degradation of the 100-kg?mol^? 1 copolymers compared to the 200-kg?mol^? 1 ones (molecular weight decrease of ca. 40% and 20%, respectively). A dramatic loss of tensile mechanical properties was also observed for the 100-kg?mol^? 1 copolymers, whereas the 200-kg?mol^? 1 copolymers showed stable or even slightly improved properties with Young's moduli around 500 MPa and yield strains around 3% to 4%. Finally, the cytocompatibility of the more stable 200 kg?mol^? 1 copolymers was confirmed by murine mesenchymal stem cells (MSCs) culture.