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[en] Electronic states of the molecular lithium anion are investigated by configuration-interaction calculations. Comparison with the analogously computed potential energy curves for the lowest singlet and triplet states of the neutral Li2 shows that in addition to the well-known stable ground state X2Σu+ there also exist metastable excited states of Li2−. Within the quartet sector, two candidates for such long-lived states are identified and their spectroscopic properties studied.
[en] The Classical Trajectory Monte-Carlo (CTMC) simulation method has been employed to calculate the total electron capture cross-sections with sub-shell distributions and ionization cross-sections in collision of Bq+(q = 1−4) with ground state atomic hydrogen in the energy range of 10–200 keV/amu. The computed results have been observed to be in reasonable agreement with other existing theoretical and experimental results over the entire energy region considered.
[en] School buildings differ from other types of buildings because they are where our children are educated and have the opportunity to learn how to become environmentally-aware citizens. It is therefore essential that schools set a good example regarding efficient fossil energy utilisation, pollution control, environmentally-friendly material selection, quality of life, users' comfort, etc. These experiences can serve as teaching aids for educational developments to raise awareness about different energy resources and their possible sustainable use. All European municipalities have some involvement in managing, retrofitting and/or building schools. They are also concerned about balancing the municipal budget. Some existing schools have very high energy consumption due to poor design, operation or maintenance. Such schools would clearly benefit from energy efficiency improvements. New schools, if properly designed and constructed, can achieve extremely low energy use. Hence, there are significant attractions for municipalities to opt for sustainable solutions which involve energy efficient technologies and measures. This is the challenging background which led to the production the Guide to Sustainable Energy Technologies for Schools. This guide is a decision-making tool intended for European municipalities and school managers. Its aim is to: - assist them in choosing between the energy technologies that will be used in school building or retrofitting projects, - provide them with a framework for measuring and comparing different aspects of energy performance that can be used to convince decision-makers to select sustainable energy technologies and measures. The guide is composed of three parts: - An illustrative list of sustainable energy technologies, - An introduction to energy performance indicators, - Fifteen case studies describing practical sustainable energy solutions applied to schools in seven European countries.
[en] The results of an experimental study of population dynamics following excitation of 62D5/2, 3/2 and 82S1/2 states of rubidium are reported. Excitation transfer and quenching cross-sections in collisions with ground state rubidium atoms, and natural lifetimes have been measured. The experiment was performed in a vapour cell, using pulsed two-photon excitation and photon counting detection. The analysis of time dependent signals was based on a rate equation model in which transitions induced by thermal radiation have been accounted for. The measurements yielded following results: (1) 62D state J-mixing cross-section: σ6D 5/2Rb-Rb = 9.2(2.1) × 10−14 cm2; (2) cross-sections for 82S → 62D excitation transfer process: σ8S→6DRb-Rb = 3.4(1.2) × 10−14 cm2; (3) quenching cross-sections: σq, 8SRb-Rb = 12,8(3.4) × 10−14 cm2, σq, 6D 3/2Rb-Rb = 22.8(2.9) × 10−14 cm2, σq, 6D5/2Rb-Rb = 14.1(5.7) × 10−14 cm2; (4) radiative lifetimes: τ8S = 161(3) ns, τ6D 3/2 = 256(4) ns, τ6D 5/2 = 249(5) ns.
[en] An efficent method of solving the inverse heat transfer problem of estimating the unknown function of wall heat flux for laminar flow inside a duct is proposed in the present paper. It is based on the Karhunen—Loève Galerkin procedure which employs the empirical eigenfunctions of the Karhunen—Loève decomposition as basis functions of a Galerkin procedure. With the empirical eigenfunctions, one can a priori limit the function space considered to the smallest linear subspace that is sufficient to describe the observed phenomena, and thus convert the governing equations to a model with a minimum degree of freedom, resulting in a drastic reduction of computation time without loss of accuracy. The performance of the present technique of inverse analysis using the Karhunen—Loève Galerkin procedure is evaluated by several numerical experiments, and is found to be very accurate as well as efficient.
[en] For a class of two hyperbolic conservation laws in two space dimensions, which includes the Weyl equation of relativistic quantum mechanics and the complex Burgers equation as prototypes, we derive a class of radially symmetric solutions. These solutions are multiple valued, a fact which does have a physical interpretation in case of the Weyl equation.
[en] In and around high energy accelerator facilities, high-energy radiation dose estimation is important to the radiological protection of workers. The contribution of high-energy protons and neutrons to the radiation exposure of astronauts cannot also be disregarded inside a spacecraft. Effective doses are adequate radiological quantities to evaluate radiation risks of individuals, exposed to radiation not only of low and intermediate energy but also of high energy. The conversion coefficients of fluence to effective doses have not been specified for all kinds of radiation in any publications of ICRP or ICRU, except the data up to 180 MeV of neutron in the ICRP74. This report provides an overview of calculational methodologies and estimated results of dose conversion coefficient of effective doses for high energy radiation such as photon, neutron, proton, alpha particle, electron, muon and pion in five groups: USA group (LAHET code), German group (LAHET), Japanese group (HERMES), Italian group (FLUKA) and Russian group (HADRON). This overview also summarized the calculational conditions and data such as computer codes, data libraries, mathematical phantoms and energy range of each particle for estimating dose conversion coefficient for each particle. Comparison of effective dose conversion coefficients of neutron, photon and proton in five groups were performed up to 10 GeV. These results will be helpful to establish an authoritative dose equivalent conversion coefficient for high-energy radiation up to 10 GeV. (author)
[en] After introducing the subject of shielding high-energy accelerators, point-source line-of-sight models, and in particular the Moyer Model, are discussed and the limitations of such models noted. Fermi-Eyges diffusion theory in the scattering of muon beams will be taken as an example of a situation where classical pre-1950s physics is still applicable today for accelerator shielding design. However new physics has affected shield design within several years of the discovery of a phenomenon. The importance of experimental shielding information and the increase in computing power that has become available in recent years is noted. The paper concludes by mentioning the unhelpfulness of many of the dosimetric concepts of the International Commission on Radiological Protection (ICRP) especially and to some extent the International Commission on Radiation Units and Measurements (ICRU). (author)
[en] This paper presents the study and realization, in hybrid technology, of a prototype power switch of 3.9 kV, obtained by series of six components of the MOS type, switching a unit voltage of a few hundred volts. The design is modular, which means that it can be combined in series with other identical modules, in order to form a high voltage macro-switch of several tens of kilovolts. The paper focuses on the technological aspect of the problem, in order to appreciate the limits and possibilities of hybridization vis-a-vis the set-up. Most of the principles of control and modularity developed in previous works in discrete technology at the CEA have been preserved. The insulation and shaping circuits of the control orders, as well as the protection circuits, are integrated inside the module. The power substrate, sized for 6 kV and 50 A permanent regime, belongs to the commonly used low voltage hybridization. It is composed of 0.635 mm Al2O3 and 2 x 0.3 mm copper. It is shown how hybridization associated with serialization offers the following perspectives: - facilitating the cooling, - reducing different delays in the transmission of control orders thanks to a smaller size, - increased possibilities in di/dt by the reduction of parasitic inductions. On the other hand, the insulation of the cooler offered in low voltage by this technology cannot be obtained in high voltage, due to the inherent dielectric and electrostatic constraints. When combining several modules, the insulation of orders requires the implementation of additional isolation transformers.(author)
[fr]Le present memoire a pour objet l'etude et la realisation, en technologie hybride, d'un prototype interrupteur de puissance de 3,9 kV, obtenu par mise en serie de six composants du type MOS commutant une tension unitaire de quelques centaines de volts. Sa conception est modulaire, ce qui signifie qu'il peut lui-meme etre associe en serie avec d'autres modules identiques, afin de constituer un macro-interrupteur haute tension de plusieurs dizaines de kilovolts. Nous nous sommes penches essentiellement sur l'aspect technologique du probleme, en vue d'apprecier les limites et possibilites de l'hybridation vis a vis de la mise en serie. La plupart des principes de commande et de modularite etablis et mis au point lors de precedents travaux menes en technologie discrete au CEA ont ete conserves. Les circuits d'isolation et de mise en forme des ordres de commande, ainsi que les circuits de protection, sont integres a l'interieur du module. Le substrat de puissance, dimensionne pour 6 kV et 50 A en regime permanent, appartient a la filiere DBC couramment utilisee en hybridation basse tension. Il est constitue de 0,635 mm d'Al2O3 et 2 x 0,3 mm de cuivre. Il ressort de cette etude que l'hybridation associee a la mise en serie offre les perspectives suivantes: - facilite de refroidissement, - diminution des retards differentiels de transmission des ordres de commande obtenue par un encombrement moindre, - augmentation des possibilites en di/dt par la reduction des inductances parasites. En revanche, l'isolation du refroidisseur offerte en basse tension par cette technologie ne peut etre obtenue en haute tension, en raison des contraintes dielectriques et electrostatiques inherentes a la mise en serie. L'isolation des ordres de commande necessite, quant a elle, la mise en oeuvre de transformateurs d'isolement supplementaires lors de l'association de plusieurs modules. (auteur)
[en] France's energy policy since the first oil crisis has already permitted a substantial reduction in CO2 emissions and therefore of France's contribution to the greenhouse effect. This policy has relied in particular on the following items: - defining strict regulations aimed at fostering energy savings. Thermal regulations on housing are a prime example. - taxation policy. High fuel taxes, higher than in most countries in Annex 1, strongly contributed to limiting CO2 emissions. Moreover, numerous energy efficiency tax incentives were implemented as early as 1974, in particular in industry and housing; - a major energy saving and efficiency awareness program. Since 1974, France has an Energy Management Agency to implement these actions, it has influenced end-user energy demand and from industry, forming over time a resource of skill and expertise; - the creation of a large nuclear industry allowing for a reduction in CO2 emissions, not only in France, but also in other Member States of the European Union. Considering the major efforts already undertaken and the results achieved, the cost of new measures that could be taken in France may often be higher than in other European Union countries or the OECD. This is why France considers it mandatory that the cost, per ton of offset carbon, of actions aimed at reducing emissions chosen in the national programs be similar to those of the various countries in Annex 1, in order to comply with economic efficiency and the polluter-pays principles. Content: 1 - Analytical summary; 2 - Introduction; 3 - National circumstances: Demographic profile, Geographic profile, Climate profile, Economic profile, Energy profile, Social profile, Public institutions and administrative organization, Greenhouse gas emissions; 4 - Greenhouse gas inventory: CO2, Methane, Nitrous oxide, HFC, PFC and SF6 emissions, Indirect greenhouse gases (tropospheric ozone precursors), Sulfur dioxide (SO2); 5 - Description of policies and actions mitigating greenhouse gas emissions; 6 - Joint implementation of activities; 7 - Projections and estimates of the effects of measures; 8 - Assessing vulnerability and adaptation measures; 9 - International cooperation and financial mechanisms; 10 - French contribution to research on global climate change; 11 - Appendix 1: Greenhouse gas emissions' inventory; 12 - Appendix 2: Summary of the policies and measures for mitigating climate change; 13 - Appendix 3: Changes in land-use; 14 - Appendix 4: French contribution to research on global climate change; 15 - Acronyms, abbreviations