Liquid Filled Microstructured Optical Fiber for X-Ray Detection

A liquid filled microstructured optical fiber (MOF) is used to detect x-rays. Numerical analysis and experimental observation leads to geometric fiber optics theory for MOF photon transmission. A model using this theory relates the quantity and energy of absorbed x-ray photons to transmitted MOF generated photons. Experimental measurements of MOF photon quantities compared with calculated values show good qualitative agreement. The difference between the calculated and measured values is discussed. 2010 Optical Society of Americ

Linearly polarized, 3.35 W narrow-linewidth, 1150 nm fiber master oscillator power amplifier for frequency doubling to the yellow

A high-power linearly polarized Yb-doped silica fiber master oscillator power amplifier at 1150 nm is reported. It produced 3.35 W cw and 2.33 W of average power in 1 s pulses at a 100 kHz repetition rate, both with 8 pm linewidth. This is the first report, to the best of our knowledge, of a high-power Yb-doped fiber amplifier at a wavelength longer than 1135 nm. The pulsed output was frequency doubled in a bulk periodically poled near-stoichiometric LiTaO 3 chip to generate 976 mW of average power at 575 nm with an overall system optical-to-optical efficiency of 9.8% with respect to launched pump power

Upconversion assisted self-pulsing in a high-concentration erbium doped fiber laser

We report results on experimental and theoretical characterisation of self-pulsing in high concentration erbium doped fibre laser which is free from erbium clusters. Unlike previous models of self-pulsing accounting for pair-induced quenching (PIQ) on the clustered erbium ions, new model has been developed with accounting for statistical nature of the excitation migration and upconversion and resonance-like pumpto-signal intensity noise transfer. The obtained results are in a good agreement with the experimental data

Direct Simulation of a Solidification Benchmark Experiment

International audienceA solidification benchmark experiment is simulated using a three-dimensional cellular automaton-finite element solidification model. The experiment consists of a rectangular cavity containing a Sn-3 wt pct Pb alloy. The alloy is first melted and then solidified in the cavity. A dense array of thermocouples permits monitoring of temperatures in the cavity and in the heat exchangers surrounding the cavity. After solidification, the grain structure is revealed by metallography. X-ray radiography and inductively coupled plasma spectrometry are also conducted to access a distribution map of Pb, or macrosegregation map. The solidification model consists of solutions for heat, solute mass, and momentum conservations using the finite element method. It is coupled with a description of the development of grain structure using the cellular automaton method. A careful and direct comparison with experimental results is possible thanks to boundary conditions deduced from the temperature measurements, as well as a careful choice of the values of the material properties for simulation. Results show that the temperature maps and the macrosegregation map can only be approached with a three-dimensional simulation that includes the description of the grain structure

Polymorphous adenocarcinoma of the salivary glands : reappraisal and update

Although relatively rare, polymorphous adenocarcinoma (PAC) is likely the second most common malignancy of the minor salivary glands (MiSG). The diagnosis is mainly based on an incisional biopsy. The optimal treatment comprises wide surgical excision, often with adjuvant radiotherapy. In general, PAC has a good prognosis. Previously, PAC was referred to as polymorphous low-grade adenocarcinoma (PLGA), but the new WHO classification of salivary gland tumours has also included under the PAC subheading, the so-called cribriform adenocarcinoma of minor salivary glands (CAMSG). This approach raised controversy, predominantly because of possible differences in clinical behaviour. For example, PLGA (PAC, classical variant) only rarely metastasizes, whereas CAMSG often shows metastases to the neck lymph nodes. Given the controversy, this review reappraises the definition, epidemiology, clinical presentation, diagnostic work-up, genetics, treatment modalities, and prognosis of PAC of the salivary glands with a particular focus on contrasting differences with CAMSG.Peer reviewe

PRACE project results : performing calculations on full Tier0 supercomputers with mesh adaptation and FEM very large linear systems resolution

In this paper we will present works and results obtained during the one year PRACE project Cim128Ki [1]. This project aims to make computation on full Tier0 supercomputers or at least up to 131,072 cores. The goal of such a project was to validate the scalability used to develop our application at such a large scale. The development context is a finite element formulation using an implicit scheme in time discretization leading to solve at the end very large linear systems. Another main axe in our strategy is doing mesh adaptation to reduce the size of the space discretization keeping the precision of the simulation unchanged. The main idea behind this to combine the benefits of every numerical technique rather than choosing one neglected others. This has become crucial has the power given by 10⁵ cores allow us to deal with very large problems containing several billion unknowns. To illustrate we want to use up to 10⁵ cores but keeping anisotropic mesh adaptation [2] that could reduce the number of unknowns to solve the problem by a factor 10³. To purchase in that way of reducing CPU time for larger problems we have implemented a parallel multigrid solver using PETSc framework [3] to reduce the algorithmic complexity for solving linear system and again reduce the number of operations done to solve the system by an other factor 10³. At the end as we combine all these improvements we are able to reduce the CPU time by a factor 10¹¹ to be compare to “only” 10⁵ if we “only” take full advantage of Tier0 supercomputers. We will first present improvements done to make us able to use more than 10⁵ cores where the details become a bottleneck, like using the MPI_Alltoall function; memory and IO management; but also keeping in mind that the size of local data hosted by a core has the same order of the number of cores used. Then we will present some parallel performances obtain during this PRACE campaign in term of hard and weak speed-up for the two main CPU consuming steps that are mesh adaptation and linear system resolution. 2d respectively 3d “biggest” runs will also be presented using two different Tier0 supercomputer (Curie : Bullx Intel/InfiniBand with 4GB/core and JuQUEEN IBM BlueGENE/Q with 1GB/core) leading to solve a 100 billion unknowns system respectively 50 billion unknowns using 64,536 cores on Curie and 262,144 cores on JuQUEEN in only some hundreds of seconds. Finally we will present some more reasonable (using about one thousand cores) but more realistic (using complex and real data given by big 3d tomographic image or complex object) simulations