Search results for "Ash"

Parabolic pulse generation with active or passive dispersion decreasing optical fibers

2007

International audience; We experimentally demonstrate the possibility to generate parabolic pulses via a single dispersion decreasing optical fiber with normal dispersion. We numerically and experimentally investigate the influence of the dispersion profile, and we show that a hybrid configuration combining dispersion decrease and gain has several benefits on the parabolic generated pulses.

High-repetition rate acoustic-induced Q-switched all-fiber laser

2005

We report a high repetition rate actively Q switched all fiber laser. The acousto optic interaction controls the cou pling between co propagating core and cladding modes and is used to modulate the optical losses of the cavity, which permits to perform active Q-switching. Using 1.4 m of 300 ppm Er-doped fiber and a maximum pump power of 120 mW, we have obtained up to 1 W peak power pulses, with a pulse repetition rate that can be continuously varied from 1 Hz to 120 kHz and a pulse width that changes from 70 ns to 2.2 μs.

Nanocrystal memories for FLASH device applications

2004

Nanocrystals memory cells, in which the conventional polysilicon floating gate is replaced by an array of silicon nanocrystals, have been fabricated and characterized. Single cells and cell arrays of 1 Mb and 10 k have been realized by using a conventional 0.15 μm FLASH technology. Si nanocrystals are deposited on top of tunnel oxide by chemical vapor deposition. Properties of the memory cell have been investigated both for NAND and NOR applications in terms of program/erase window and programming times. Suitable program/erase threshold voltage window can be achieved with fast voltage pulses by adequate choice of tunnel and control dielectric. The feasibility of dual bit storage is also pro…

Ultrafast buffering by molecular gas

2011

A simple molecular gas sample can be used to achieve ultrafast optical buffering in two-dimensional optical imaging, thus serving as a promising extension of the well-developed liquid-crystal display technology.

Ultrafast laser-induced micro-explosion: material modification tool

2016

Femtosecond Bessel pulses with a needle-like intensity distribution were focused inside sapphire crystal to create voids and the shock-wave affected volume which is by more than two orders of magnitude larger as compared with that made by the Gaussian pulse.

Calibration of a thermoluminescent dosimeter worn over lead aprons in fluoroscopy guided procedures

2018

Fluoroscopy guided interventional procedures provide remarkable benefits to patients. However, medical staff working near the scattered radiation field may be exposed to high cumulative equivalent doses, thus requiring shielding devices such as lead aprons and thyroid collars. In this situation, it remains an acceptable practice to derive equivalent doses to the eye lenses or other unprotected soft tissues with a dosimeter placed above these protective devices. Nevertheless, the radiation backscattered by the lead shield differs from that generated during dosimeter calibration with a water phantom. In this study, a passive personal thermoluminescent dosimeter (TLD) was modelled by means of …

Integrating the Kadomtsev-Petviashvili Equation in the 1+3 Dimensions VIA the Generalised Monge-Ampère Equation: An Example of Conditioned Painlevé T…

1994

Functional Data Analysis for Optimizing Strategies of Cash-Flow Management

2017

The cash management deals with problem of automating and managing cash-flow processes. Optimization of the management processes greatly reduces overall cash handling costs. The present analysis is an empirical study of cash flows, from and to bank branches, deriving an underlying theoretical framework, which can in a reasonable way be connected with the optimal strategy. Functional data analysis is considered an appropriate framework to analyze the dynamics of the time series behavior of cash flows: since the observations are not equally spaced in time and their number is different for each series, they are converted into a collection of random curves in a space spanned by finite dimensiona…

Quasi-nash equilibria for non-convex distributed power allocation games in cognitive radios

2013

In this paper, we consider a sensing-based spectrum sharing scenario in cognitive radio networks where the overall objective is to maximize the sum-rate of each cognitive radio user by optimizing jointly both the detection operation based on sensing and the power allocation, taking into account the influence of the sensing accuracy and the interference limitation to the primary users. The resulting optimization problem for each cognitive user is non-convex, thus leading to a non-convex game, which presents a new challenge when analyzing the equilibria of this game where each cognitive user represents a player. In order to deal with the non-convexity of the game, we use a new relaxed equilib…

Smart multi-carrier energy system: Optimised energy management and investment analysis

2016

This paper proposes an optimised Energy Management System for a multi-carrier hub, which integrates two energy distribution networks, for hydrogen and electricity. The economic sustainability of a real-life instantiation of such a system has been analysed as well. The Energy Management System has been developed by means of a multi-objective optimisation algorithm, the Non-dominated Sorting Genetic Algorithm II, implemented using MATLAB®. The achieved results consist in a series of set-points defining the working conditions of the plant for a chosen time horizon. Data provided by this process also show the effectiveness of the adopted optimisation approach. The financial analysis is performe…