Countercurrent reactor design and flowsheet for iodine-sulfur thermochemical water splitting process

A conceptual design is presented for the I/S process for the production of hydrogen using a high-temperature nuclear heat source to split water. The process includes a countercurrent reactor being developed by CEA within the framework of an international collaboration (I-NERI project) with DOE at General Atomics (San Diego, CA). A ProsimPlus? model of the flowsheet indicates 600 kJ high-temperature heat and 69 kJ electric power are consumed per mole of H₂ product (with an assumed pressure of 120 bars). The net thermal efficiency would be 38% (HHV basis) if electric power is available at a conversion efficiency of 45%.     

The effect of bovine whey proteins on the ability of poliovirus and Coxsackie virus to infect Vero cell cultures

The antiviral activity of esterified whey proteins (IC₅₀=20–40 μg mL⁻¹) observed against poliovirus type-1 and Coxsackie virus B6 infecting Vero cells depended on five factors (in order of importance): concentration of esterified proteins, multiplicity of infection, duration of incubation, timing of esterified proteins addition after infection, and extent of esterification of proteins. Renewal of cell growth medium after 24 h of incubation with new medium containing the same amount of esterified proteins enhanced the anti Coxsackie virus effect. Difference between start of infection of the reporter Vero cells and the time of addition of esterified proteins significantly decreased their antiviral efficacies. The poliovirus titer reduced gradually in response to the increase of the concentrations of esterified proteins. The relative amounts of viral RNA were less affected by the esterified proteins concentration than was the virus infectious titer, indicating that inhibitory proteins may slow down viral multiplication, yielding reduced amounts of viral RNA.     

Empirical Study on Collaborative Writing: What Do Co-authors Do, Use, and Like?

How do people work when they are collaborating to write a document? What kind of tools do they use and, in particular, do they resort to groupware for this task? Forty-one people filled out a questionnaire placed on the World Wide Web. In spite of the existence of specialized collaborative writing tools, most respondents reported using individual word processors and email as their main tools for writing joint documents. Respondents noted the importance of functions such as change tracking, version control, and synchronous work for collaborative writing tools. This study also confirmed the great variability that exists between collaborative writing projects, whether it be group membership, management, writing strategy, or scheduling issues.     

ARIANEXPERT: A knowledge based system to analyze ARIANE's mission data

The ARIANE launcher post mission analysis is done at ARIANESPACE. This activity is called the ‘level 0 post flight analysis’ (PFA) and is carried out after each launch by about 60 engineers who are working together under the leadership of ARIANESPACE.

The PFA is one of the most critical of ARIANE operations, for several reasons:

• - The launch rate (8 a year for ARIANE 4) leaves a very short time to carry out all the verification work. Moreover, the PFA is a mandatory step before authorizing the next launch.

• - The complexity of the ARIANE launcher results in a very high demand on the PFA engineers. Moreover, there are problems of availability of people with relevant expert knowledge (characterized by a substantial staff turn-over during the 10 year life duration of ARIANE 4) which could potentially result in errors or omissions.

It is very important to be able to take into account the experience of the preceding flights and to record the results and the knowledge accumulated for each launch.

• - The quality and the reliability of the PFA mainly depends on the accessibility of data and on the used methodology.

Because the PFA is still largely done manually, and does not benefit from improved methodologies and advanced technologies providing computerized support for data processing and diagnosis, ARIANESPACE has sponsored MATRA ESPACE for the development of a knowledge based system, called ARIANEXPERT, for supporting the PFA activity. This system combines AI techniques and numerical analysis techniques, together with advanced graphical capabilities.

A prototype has been delivered in April 1990 and has been used since 6 months by ARIANESPACE during real PFAs. Several lessons have been drawn from this operational experience and are described in this paper. They concern:

• - The utility and justification of the use of AI techniques mostly coming from the explanation capabilities and the stress put on capturing the expert knowledge.

• - The difficulties associated with the integration of such systems in the exploitation of ARIANE due to the introduction of very new tasks.

• - The user point of view which evolved from reluctant to convinced.

     

Stereospecific anionic polymerization of styrene initiated by R2Mg/ROMt ‘ate’ complexes

Various ‘ate’ complexes formed by reaction of alkali metal (Li, Na, K) derivatives and alkyl metals (Mg, Al, Zn) were used as initiator for the styrene anionic polymerization in hydrocarbon media and their influence on polystyrene microstructure has been investigated. A strong dependence of the polymer tacticity on both the nature of the alkali metal and of the associated metal alkyl used is observed. Binary systems like potassium derivatives/dialkylmagnesium yield isotactic-rich polystyrene. Eighty-five percent isotactic polystyrene (mm triad) is obtained in methylcyclohexane at −40 °C with the potassium tert-butoxide/n,s-dibutylmagnesium system. The characteristics of solubility of the stereoregular polystyrenes are in agreement with isotactic polystyrene chains containing some stereostructural defects and suggest that one single type of isospecific propagating centres is operating during the polymerization. When lithium or sodium derivatives are used in association to dialkylmagnesium instead of a potassium derivative, a strong decrease of the isotacticity is observed. The influence, on the extent of stereoregulation, of other parameters of these initiating systems as well as that of the solvent has also been investigated. The stereoregulation mechanisms involved in these styrene anionic polymerizations may be related to styrene insertion into carbon-metal bonds of the ‘ate’ complexes with a covalent character.     

Low and intermediate level waste management in EDF PWRs

This paper aims to explain how Electricité de France as owner and plant operator of nuclear power stations generating wastes has improved its management to meet its obligations which are the protection of man and preservation of the environment. Beyond the technical aspects (reducing liquid effluents and sorting waste at source for example) which have led to a significant decrease of radioactive waste volumes, continued success depends on planned management initiatives. These include computerized waste management and will be completed finally by setting up centralized treatment methods such as fusion and incineration. To provide packages in accordance with French specifications for final near-surface disposal, EDF has applied the same quality approach to radioactive waste management as that used for other operating actions. Management decisions taken mainly coordinate around two axes, namely "Accountability" and "organisation".     

Acoustic, piezoelectric, and dielectric nonlinearities of AlN in coupled resonator filters for high RF power levels

Coupled resonator filters (CRFs) are the new generation of BAW filters recently designed for the front-end modules of mobile transmission systems. Looking for designers' requirements, CRF devices have been characterized and modeled. The model based on equivalent circuits relies on material constants such as stiffness and electro-coupling coefficients, and works only for linear-mode propagation. Because of their positions between antennas and power amplifiers, they often work under high RF power, inducing nonlinear response in the AlN piezoelectric layer. In this work, we analyze for the first time the nonlinear behavior of AlN material particularly for coupled BAW resonators. To characterize the nonlinear effects in CRFs, we measure the 1-dB gain compression point (P1dB) and the intercept point (IP(3)). Then, we develop a nonlinear model of CRFs using harmonic balance (HB) simulation in commercially available software. The HB environment allows fitting simulations to measurements in terms of P(1dB) and IP(3). We find that a high RF power induces nonlinear changes in the material constants' real parts: elastic stiffness c(33) (4.9%), piezoelectric e(33) (17.4%), and permittivity ?(33) (5.2%). These nonlinear variations of material constants describe the nonlinear behavior of CRF devices using the same deposit process for AlN material.     

Solid respirometry to characterize nitrification kinetics: a better insight for modelling nitrogen conversion in vertical flow constructed wetlands

We developed an original method to measure nitrification rates at different depths of a vertical flow constructed wetland (VFCW) with variable contents of organic matter (sludge, colonized gravel). The method was adapted for organic matter sampled in constructed wetland (sludge, colonized gravel) operated under partially saturated conditions and is based on respirometric principles. Measurements were performed on a reactor, containing a mixture of organic matter (sludge, colonized gravel) mixed with a bulking agent (wood), on which an ammonium-containing liquid was applied. The oxygen demand was determined from analysing oxygen concentration of the gas passing through the reactor with an on-line analyzer equipped with a paramagnetic detector. Within this paper we present the overall methodology, the factors influencing the measurement (sample volume, nature and concentration of the applied liquid, number of successive applications), and the robustness of the method. The combination of this new method with a mass balance approach also allowed determining the concentration and maximum growth rate of the autotrophic biomass in different layers of a VFCW. These latter parameters are essential inputs for the VFCW plant modelling.     

Accurate large-signal GaAs MESFET and HEMT modeling for power MMIC amplifier design

This article describes, from an industrial user's point of view, how large-signal GaAs MESFET and HEMT modeling can be done accurately and efficiently for power MMIC amplifier design. The method is based on commercially available CAD tools enhanced by in-house software (e.g., small-signal parameter extraction, generation of load-pull contours). The Materka model is shown to predict accurately the large-signal characteristics of GaAs MESFETs, but not of pseudomorphic HEMTs. For these devices, a modified Angelov model is found to be adequate. A method for determining the numerous large-signal model parameters is presented. Model verification is achieved by comparing simulated and on-wafer measured data like static I(V)-characteristics, multiple bias S-parameters, gain compression characteristics, and load-pull contours. Results of device scaling and calculations of optimum load impedances are discussed. The close fit to the measured data proves that an excellent basis for large-signal power MMIC design has been established.     

Attraction personnelle et attraction sociale : Lorsque la saillance catégorielle annule la relation similitude-attraction.

Research on interpersonal attraction has repeatedly demonstrated that people are more attracted to similar others. In the present article, our goal is to show that this similar-attraction relationship is moderated by people's current level of self-categorization. Students were required to constitute work groups by selecting five classmates who shared to varying degrees similar attitudes. Under standard conditions (no group salience) participants' choice supported the similar-attraction relationship. However, when implicitly reminded of their gender identity, participants did not show anymore attraction to others who shared more similar attitudes. The results are discussed in terms of the self-categorization theory and suggestions are made to distinguish between two forms of attraction: interpersonal attraction and social attraction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)