Experimental and numerical study of crack healing in a nuclear glass

International audiencea b s t r a c t An experimental study of thermally or water-induced crack healing in an inactive borosil-icate glass, chemically analogous to that used in France for the vitrification of nuclear waste was carried out. Partial welding of glass plates was observed after annealing in air at 425 °C (77 °C below T g) when at least 20 MPa compressive stress was applied, while annealing at 450 °C under 20 MPa led to a complete disappearance of the interface. Closure of indenta-tion-induced cracks was observed during annealing at 400 °C in an ESEM as a result of viscous relaxation of residual stresses but it did not constitute a sufficient proof of crack healing. DCDC specimens were thus pre-cracked in an ESEM and then either annealed at various temperatures (350–490 °C) in secondary vacuum or in air, or left in water at 70–90 °C, sometimes under a compressive stress normal to the crack face. The specimens were then reloaded in the ESEM and the crack opening displacements under a given load were compared to those measured during pre-cracking. The cracks were bridged by an alteration layer over a distance from the crack tip which decreased as loading increased. The restraining effect of these bridges on crack opening was assessed via finite element simulations, using interface elements. The tensile strength of the bridging layer was estimated as 27–39 MPa after vacuum annealing at 400 °C, 11–20 MPa after 15 days in water at 90 °C and 44–78 MPa after 11 days in water at 70 °C under 5 MPa normal compression. Partially healed cracks did not resume propagation from their former crack tip, but due to branch cracks re-initiated a few hundred microns behind it which grow avoiding the healed area. This behaviour was explained using finite element simulations

El Feto, un Paciente que Espera

La preocupación sobre la salud fetal surge en nuestra sociedad a medida que se conoce que una de las causas fundamentales de las muertes prenatales es debida a las malformaciones y enfermedades fetales. En este artículo, se entrega información relevante sobre este tema que es de alta complejidad. Las preguntas que surgen frente a estos hechos son:¿Cómo y cuando enferma un feto?, ¿Cómo se pueden prevenir estas enfermedades o bien curarlas?, ¿Que se puede hacer frente a un feto enfermo? El objetivo de nuestro artículo es aportar información sobre un tema no bien conocido pero que, de una u otra forma, interesa a cada uno de nosotros

High intensity and space charge problems at GANIL

http://accelconf.web.cern.ch/AccelConf/c86/papers/g-04.pdfInternational audienceWe routinely accelerate up to micro-amperes of ionsat energies ranging from 25 to 95 MeV / A. Already atthese levels, space charge (S.C) problems drasticallyaffect the bunching efficiency between the ECRexternal ion-source and our Co compact injector.Moreover in the "2.5" version of GANIL we expectcurrents above 50 e\l A (Ar+6 for instance) and S.Ceffects will be of prime importance during accelerationin the injector and even in our first SSC. Wepresent our computer codes and our first results

Upper Bounding in Inner Regions for Global Optimization under Inequality Constraints

International audienceIn deterministic continuous constrained global optimization, upper bounding the objective function generally resorts to local minimization at several nodes/iterations of the branch and bound. We propose in this paper an alternative approach when the constraints are inequalities and the feasible space has a non-null volume. First, we extract an inner region , i.e., an entirely feasible convex polyhedron or box in which all points satisfy the constraints. Second, we select a point inside the extracted inner region and update the upper bound with its cost. We describe in this paper two original inner region extraction algorithms implemented in our interval B&B called IbexOpt. They apply to nonconvex constraints involving mathematical operators like +,x,power,sqrt,exp,log,sin. This upper bounding shows very good performance obtained on medium-sized systems proposed in the COCONUT suite

Preliminary design of a new high intensity injection system for GANIL.

http://accelconf.web.cern.ch/AccelConf/c89/papers/f6-12.pdfInternational audienc

Pemberdayaan Masyarakat Pesisir Pulau Untungjawa Dalam Upaya Meningkatkan Kesadaran Hukum Dan Kemandirian Nelayan

Kelurahan Pulau Untung Jawa merupakan salah satu dari enam kelurahan di wilayah kepulauan Seribu atau satu di antara tiga kelurahan di wilayah kecamatan Kepulauan Seribu Selatan. Penduduk Pulau Untung Jawa sebagian besar adalah masyarakat pribumi yang silsilahnya berasal dari Pulau Untung Jawa dan perpindahan masyarakat Pulau Ubi Besar tanggal 13 Februari 1954. Kelurahan Pulau Untung Jawa merupakan kawasan andalan Wisata Pemukiman yang mempunyai peranan penting dalam mewujudkan visi kabupaten yaitu: Sebagai Taman dan Ladang Kehidupan Bahari yang Berkelanjutan Penelitian ini menemukan model pemberdayaan yang tepat bagi masyarakat pesisir pulau UntungJawa dan menganalisis upaya peningkatan kesadaran hukum dan kemandirian nelayan Pulau UntungJawa. Penelitian ini termasuk dalam penelitian deskriptif kualitatif dengan pendekatan sosiologis, atau dalam penelitian hukum biasa disebut normatif terapan/normatif empiris. Model pemberdayaan yang bertujuan membangun kemandirian nelayan pulau UntungJawa dapat dilaksanakan dengan kerjasama dan partisipasi masyarakat. Perlu sinergitas antara peran pemerintah baik aparat kelurahan dan instansi terkait lainnya, LSM yang peduli atau pun Perusahaan, kampus maupun masyarakat nelayan itu sendiri. Terdapat faktor pendukung dan faktor penghambat yang harus diperhatikan dan dicarikan solusinya. Faktor pendukung antara lain sudah terbangun konsep kesadaran dalam melakukan segala macam kegiatan yang sesuai dengan hukum yang ada, potensi wisata dan produksi perikanan, aparat Kelurahan yang cukup aktif dan kesiapan SDM untuk memotivasi diri dan menerima pendampingan serta berbagai pelatihan. Adapun faktor penghambatnya antara lain: terbatasnya modal, faktor alam, sarana prasarana, kurangnya gairah wisata, daya minat beli dan daya minat permainan air, tidak adanya penghasillan rutin, honor pekerja yang kurang dari UMP, SDM, dan kurangnya kesadaran hukum, bantuan hukum dan perlindungan hukum

Determination of set-membership identifiability sets

International audienceThis paper concerns the concept of set-membership identifiability introduced in \cite{jauberthie}. Given a model, a set-membership identifiable set is a connected set in the parameter domain of the model such that its corresponding trajectories are distinct to trajectories arising from its complementary. For obtaining the so-called set-membership identifiable sets, we propose an algorithm based on interval analysis tools. The proposed algorithm is decomposed into three parts namely {\it mincing}, {\it evaluating} and {\it regularization} (\cite{jaulin2}). The latter step has been modified in order to obtain guaranteed set-membership identifiable sets. Our algorithm will be tested on two examples

Ergodicity criteria for non-expanding transformations of 2-adic spheres

In the paper, we obtain necessary and sufficient conditions for ergodicity (with respect to the normalized Haar measure) of discrete dynamical systems $$ on 2-adic spheres $\mathbf S_{2^{-r}}(a)$ of radius $2^{-r}$, $r\ge 1$, centered at some point $a$ from the ultrametric space of 2-adic integers $\mathbb Z_2$. The map $f\colon\mathbb Z_2\to\mathbb Z_2$ is assumed to be non-expanding and measure-preserving; that is, $f$ satisfies a Lipschitz condition with a constant 1 with respect to the 2-adic metric, and $f$ preserves a natural probability measure on $\mathbb Z_2$, the Haar measure $\mu_2$ on $\mathbb Z_2$ which is normalized so that $\mu_2(\mathbb Z_2)=1$

Boosted tops: Physics and reconstruction

The production of boosted top quarks in the high centre-of-mass energy collisions at the LHC is a probe to new phenomena at the TeV scale. Numerous extensions to the Standard Model (SM) predict massive particles whose couplings to top quarks are enhanced. Such massive particles, referred as t¯t resonances, will distort the t¯t invariant mass spectrum relative to the SM expectation. This presentation is dedicated to studies performed by the ATLAS and CMS Collaborations. New techniques were developed to reconstruct boosted top quarks as single objects, both as a top-tagged jet with a substructure in the hadronic decay mode and a jet with a lepton inside in the leptonic decay mode. These techniques were applied in dedicated analyses to search for high mass t¯t resonances. Expected limits and the potential for observation are presented for a luminosity of few hundreds of pb−1