Etude du comportement mécanique d'un liner de titane

National audienceIl s'agit dans ce travail d'étudier le comportement mécanique d'un liner constitué de titane T35, fourni sous la forme de feuillard de 300 μm d'épaisseur. Ce travail porte notamment sur la caractérisation du métal de base mais aussi sur celui des cordons de soudure.. Pour le matériau de base, les observations microstructurales ont révélé des grains équiaxes avec une texture classique de tôle laminée pour les matériaux hexagonaux. Les soudures montrent une microstructure moins régulière et une texture plus isotrope. D'un point de vue comportement mécanique, nous avons pu identifier au moyen d'essais de traction un comportement élastoviscoplastique anisotrope des tôles. Ces résultats expérimentaux ont permis l'identification de 3 modèles issus de la littérature, (Mises, Hill et Bron-Besson) donnant lieu à des comparaisons de simulation. Enfin une analyse tomographique réalisée à l'ESRF sur une éprouvette fissurée a révélée la présence de peu de cavités à proximité de la fissure

Dexterous Grasping Tasks Generated With an Add-on End Effector of a Haptic Feedback System

The simulation of grasping operations in virtual reality (VR) is required for many applications, especially in the domain of industrial product design, but it is very difficult to achieve without any haptic feedback. Force feedback on the fingers can be provided by a hand exoskeleton, but such a device is very complex, invasive, and costly. In this paper, we present a new device, called HaptiHand, which provides position and force input as well as haptic output for four fingers in a noninvasive way, and is mounted on a standard force-feedback arm. The device incorporates four independent modules, one for each finger, inside an ergonomic shape, allowing the user to generate a wide range of virtual hand configurations to grasp naturally an object. It is also possible to reconfigure the virtual finger positions when holding an object. The paper explains how the device is used to control a virtual hand in order to perform dexterous grasping operations. The structure of the HaptiHand is described through the major technical solutions required and tests of key functions serve as validation process for some key requirements. Also, an effective grasping task illustrates some capabilities of the HaptiHand

Dynamique tourbillonnaire dans un champ de houle

Cette étude présente des résultats préliminaires sur la dynamique de tourbillons générés par une plaque plane horizontale dans un canal à houle. Sous l'effet de l'écoulement orbital et fortement cisaillé de la houle, les tourbillons ondulent et se déstabilisent. Les caractéristiques des tourbillons sont déterminées, dans un premier temps, dans un plan 2D perpendiculaire à l’axe du tourbillon par méthode PIV

An add-on device to perform dexterous grasping tasks with a haptic feedback system

Achieving grasping tasks in real time with haptic feedback may require the control of a large number of degrees of freedom (DOFs) to model hand and finger movements. This is mandatory to grasp objects with dexterity. Here, a new device called HaptiHand is proposed that can be added to a haptic feedback arm and provide the user with enough DOFs so that he/she can intuitively and dexterously grasp an object, modify the virtual hand configuration and number of fingers with respect to the object while manipulating the object. Furthermore, this device is non-invasive and enables the user to apply forces on the fingers of the virtual hand. The HaptiHand lies inside the user’s hand so that the user can apply and release pressure on it in a natural manner that is transferred to the virtual hand using metaphors. The focus is placed on the description of the technology and structure of the HaptiHand to justify the choices and explain the behavior of the HaptiHand during object grasping and releasing tasks. This is combined with a short description of the models used.iLab Inria-Haptio

Optimized market value of alpine solar photovoltaic installations

Solar photovoltaic (PV) is the most rapidly expanding renewable resource worldwide. Yet, its full potential may be hindered by mismatches with market demand and correlated production profiles. In this research, we explore a case study of innovative PV placements in alpine regions using two, soft-linked optimization models of Switzerland's electricity system. Using Swissmod, an electricity dispatch and load-flow model, and OREES, an electricity system model employing evolution strategy to optimize PV placement, we simulate market prices of optimized PV placements given multiple years of weather data, various CO2 prices, and considering future electricity infrastructure developments across Europe. Mountain placements result in higher market value and less required area relative to lower-altitude PV placement strategies. The higher market value is driven by better alignment with demand, particularly during winter when demand is highest. We found that optimized alpine placements offer revenues of panel capacity (EUR/kW/year) that are on average 20% higher than revenues from urban PV installations. Furthermore, the Swiss mountains could host more than 1 GW of capacity with even greater revenues (33%). Alpine PV installations, with their higher market values and increased value factors, can potentially be very profitable investments and are also valuable from a system perspective

Design of Portable and Accessible Platform in Charge of Wheelchair Feedback Immersion

Rewarded at Laval Virtual 2014, the AccesSim project aims to develop a wheelchair simulator based on Virtual Reality (VR) and a dynamic force­‐feedback platform, which allows to experience and to evaluate the accessibility in complex urban or property environment. In order to address this issue, the dynamic force-­feedback platform should provide haptic and vestibular feedback to various user profiles: from town‐planners to wheelchair users. The platform needs to be modular and adjustable to each of these profiles. This article focuses on the dynamic force­‐feedback platform and specifically on the force­‐feedback systems used.Ile‐De­‐France region, EDF R&D (project leader), LISV (UVSQ), LAMPA (Arts & Métiers ParisTech), CEREMH, CEA-­LIST

CSF neopterin level as a diagnostic marker in primary central nervous system lymphoma

Background The diagnosis of primary central nervous system lymphoma (PCNSL) can be challenging. PCNSL lesions are frequently located deep within the brain, and performing a cerebral biopsy is not always feasible. The aim of this study was to investigate the diagnostic value of CSF neopterin, a marker of neuroinflammation, in immunocompetent patients with suspected PCNSL. Methods We retrospectively reviewed the characteristics of 124 patients with brain tumor (n = 82) or an inflammatory CNS disorder (n = 42) in whom CSF neopterin levels were assessed. Twenty-eight patients had PCNSL, 54 patients had another type of brain tumor (glioma n = 36, metastasis n = 13, other n = 5), and 13 patients had a pseudotumoral inflammatory brain lesion. Results CSF neopterin levels were significantly higher in the patients with PCNSL than in those with other brain tumors (41.8 vs 5.1 nmol/L, P < .001), those with pseudotumoral inflammatory brain lesions (41.8 vs 4.3 nmol/L, P < .001), and those with nontumefactive inflammatory CNS disorders (41.8 vs 3.8 nmol/L, P < .001). In the 95 patients with space-occupying brain lesions, at a cutoff of 10 nmol/L, the sensitivity of this approach was 96% and the specificity was 93% for the diagnosis of PCNSL. The positive and negative predictive values were 84% and 98%, respectively. Conclusion Assessing CSF neopterin levels in patients with a suspected brain tumor might be helpful for the positive and differential diagnosis of PCNSL. A prospective study is warranted to confirm these result

Evaluation of Ultrasound Haptics as a Supplementary Feedback Cue for Grasping in Virtual Environments

This paper presents an evaluation of ultrasound mid-air hap-tics as a supplementary feedback cue for grasping and lifting virtual objects in Virtual Reality (VR). We present a user study with 27 participants and evaluate 6 different object sizes ranging from 40 mm to 100 mm. We compare three supplementary feedback cues in VR; mid-air haptics, visual feedback (glow effect) and no supplementary feedback. We report on precision metrics (time to completion, grasp aper-ture and grasp accuracy) and interaction metrics (post-test questionnaire, observations and feedback) to understand gen-eral trends and preferences. The results showed an overall preference for visual cues for bigger objects (>60mm) while ultrasound mid-air haptics were preferred for small virtual targets (≤ 50 mm)

Future perspectives in melanoma research: meeting report from the "Melanoma Bridge";: Napoli, December 3rd-6th 2014.

The fourth "Melanoma Bridge Meeting" took place in Naples, December 3-6th, 2014. The four topics discussed at this meeting were: Molecular and Immunological Advances, Combination Therapies, News in Immunotherapy, and Tumor Microenvironment and Biomarkers. Until recently systemic therapy for metastatic melanoma patients was ineffective, but recent advances in tumor biology and immunology have led to the development of new targeted and immunotherapeutic agents that prolong progression-free survival (PFS) and overall survival (OS). New therapies, such as mitogen-activated protein kinase (MAPK) pathway inhibitors as well as other signaling pathway inhibitors, are being tested in patients with metastatic melanoma either as monotherapy or in combination, and all have yielded promising results. These include inhibitors of receptor tyrosine kinases (BRAF, MEK, and VEGFR), the phosphatidylinositol 3 kinase (PI3K) pathway [PI3K, AKT, mammalian target of rapamycin (mTOR)], activators of apoptotic pathway, and the cell cycle inhibitors (CDK4/6). Various locoregional interventions including radiotherapy and surgery are still valid approaches in treatment of advanced melanoma that can be integrated with novel therapies. Intrinsic, adaptive and acquired resistance occur with targeted therapy such as BRAF inhibitors, where most responses are short-lived. Given that the reactivation of the MAPK pathway through several distinct mechanisms is responsible for the majority of acquired resistance, it is logical to combine BRAF inhibitors with inhibitors of targets downstream in the MAPK pathway. For example, combination of BRAF/MEK inhibitors (e.g., dabrafenib/trametinib) have been demonstrated to improve survival compared to monotherapy. Application of novel technologies such sequencing have proven useful as a tool for identification of MAPK pathway-alternative resistance mechanism and designing other combinatorial therapies such as those between BRAF and AKT inhibitors. Improved survival rates have also been observed with immune-targeted therapy for patients with metastatic melanoma. Immune-modulating antibodies came to the forefront with anti-CTLA-4, programmed cell death-1 (PD-1) and PD-1 ligand 1 (PD-L1) pathway blocking antibodies that result in durable responses in a subset of melanoma patients. Agents targeting other immune inhibitory (e.g., Tim-3) or immune stimulating (e.g., CD137) receptors and other approaches such as adoptive cell transfer demonstrate clinical benefit in patients with melanoma as well. These agents are being studied in combination with targeted therapies in attempt to produce longer-term responses than those more typically seen with targeted therapy. Other combinations with cytotoxic chemotherapy and inhibitors of angiogenesis are changing the evolving landscape of therapeutic options and are being evaluated to prevent or delay resistance and to further improve survival rates for this patient population. This meeting's specific focus was on advances in combination of targeted therapy and immunotherapy. Both combination targeted therapy approaches and different immunotherapies were discussed. Similarly to the previous meetings, the importance of biomarkers for clinical application as markers for diagnosis, prognosis and prediction of treatment response was an integral part of the meeting. The overall emphasis on biomarkers supports novel concepts toward integrating biomarkers into contemporary clinical management of patients with melanoma across the entire spectrum of disease stage. Translation of the knowledge gained from the biology of tumor microenvironment across different tumors represents a bridge to impact on prognosis and response to therapy in melanoma