TEM image analysis and modelling: application to boehmite nanoparticles

Boehmite occurs in the form of nanoparticles. Upon drying, it can form the alumina that is common in catalyst support used in refining and petrochemicals. The topotactic transformation of boehmite alumina led to an interest in the precise shape and size of these nanoparticles which is highly linked to the catalyst activity. Boehmite nanoparticles can be observed by transmission electron microscopy. Although they are highly aggregated, the analysis of transmission electron microscopy images with a specific random model approach, here a dilution model, can give an accurate estimate of their size. To use this approach, electronic noise and diffraction artefacts on the edges of the nanoparticles have to be removed. Covariance measurements on micrographs can be performed. They can be used to fit a model. The fitting uses a novel numerical method to estimate the covariogram of grains. The model can take into account the specific orientations of the nanoparticles. The influence of noise, image filters used to remove noise and diffraction artefacts, as well as all the parameters of the model are all studied in this paper. We propose nanoparticle size estimations procedures based on both single and mixture-of-two particle models.     

Optimal design of measurement network for neutronic activity field reconstruction by data assimilation

An optimal reconstruction of the neutronic activity field can be determined for a nuclear reactor core using a data assimilation framework to merge information from models and measurements. In this paper, we focus on solving the inverse problem of determining an optimal repartition of the measuring instruments within the core, to get the best possible results from the data assimilation reconstruction procedure. The position optimisation is realised using a Simulated Annealing algorithm, based on the Metropolis-Hastings proposition. Moreover, algebraic improvements of data assimilation have been developed, optimising their computational performance, and are presented here.     

Investigation of the Equivalence of National Dew-Point Temperature Realizations in the ?50?°C to +?20?°C Range

In the field of humidity quantities, the first CIPM key comparison, CCT-K6 is at its end. The corresponding European regional key comparison, EUROMET.T-K6, was completed in early 2008, about 4?years after the starting initial measurements in the project. In total, 24 NMIs from different countries took part in the comparison. This number includes 22 EURAMET countries, and Russia and South Africa. The comparison covered the dew-point temperature range from ?50?°C to +20?°C. It was carried out in three parallel loops, each with two chilled mirror hygrometers as transfer standards in each loop. The comparison scheme was designed to ensure high quality results with evenly spread workload for the participants. It is shown that the standard uncertainty due to the long-term instability was smaller than 0.008?°C in all loops. The standard uncertainties due to links between the loops were found to be smaller than 0.025?°C at ?50?°C and 0.010?°C elsewhere. Conclusions on the equivalence of the dew-point temperature standards are drawn on the basis of calculated bilateral degrees of equivalence and deviations from the EURAMET comparison reference values (ERV). Taking into account 16 different primary dew-point realizations and 8 secondary realizations, the results demonstrate the equivalence of a large number of laboratories at an uncertainty level that is better than achieved in other multilateral comparisons so far in the humidity field.     

VO2 nanostructures based chemiresistors for low power energy consumption hydrogen sensing

Mott-type VO₂ oxide nanobelts are demonstrated to be effective hydrogen gas sensors at room temperature. These nanobelts, synthesized by hydrothermal process and exhibiting the VO₂ (A) crystallographic phase, display room temperature H₂ sensitivity as low as 0.17 ppm. The nanobelts (ultralong belt-like) nanostructures could be an ideal system for fully understanding dimensionally confined transport phenomena in functional oxides and for building functional devices based on individual nanobelts.     

Automatic low-cost IP watermarking technique based on output mark insertions

Today, although intellectual properties (IP) and their reuse are common, their use is causing design security issues: illegal copying, counterfeiting, and reverse engineering. IP watermarking is an efficient way to detect an unauthorized IP copy or a counterfeit. In this context, many interesting solutions have been proposed. However, few combine the watermarking process with synthesis. This article presents a new solution, i.e. automatic low cost IP watermarking included in the high-level synthesis process. The proposed method differs from those cited in the literature as the marking is not material, but is based on mathematical relationships between numeric values as inputs and outputs at specified times. Some implementation results with Xilinx Virtex-5 FPGA that the proposed solution required a lower area and timing overhead than existing solutions.     

An optimal control of a wastewater treatment reactor by catalytic ozonation

This paper deals with the control of a wastewater treatment pilot by catalytic ozonation. In general, catalytic ozonation processes operate with a deliberate ozone overproduction to obtain a treated water which respects discharge standards. But, in this case, the oxygen consumption is not optimal and the operating costs are important. The objective of this study focuses on the optimization of the catalytic ozonation reactor. A continuous-time transfer function model is identified to represent the pilot behavior, and an optimal control is proposed to obtain a significant abatement of the pollutant. In this application, the pollutant abatement is represented by the absorbance.     

A Strategic Approach for Managing Oil and Gas Assets

The global oil market is experiencing a structural shift. Faced with a rapid price decline, large oil-producing countries had decided to protect their market share, with the hopes of permanently removing expensive supply from the market. Meanwhile, the ability of the US shale oil producers to respond quickly to positive price signals puts downward pressure on prices. On the demand side, advances in renewable technology and the continued effort to curb consumption of fossil fuel conspire to inhibit long-run growth.¹ These factors suggest that the current down-cycle may continue for an extended period of time or even invoke another down-cycle.