962 resultados para electronic transition energy
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Germany’s current energy strategy, known as the “energy transition”, or Energiewende, involves an accelerated withdrawal from the use of nuclear power plants and the development of renewable energy sources (RES). According to the government’s plans, the share of RES in electricity production will gradually increase from its present rate of 26% to 80% in 2050. Greenhouse gas emissions are expected to fall by 80–95% by 2050 when compared to 1990 levels. However, coal power plants still predominate in Germany’s energy mix – they produced 44% of electricity in 2014 (26% from lignite and 18% from hard coal). This makes it difficult to meet the emission reduction objectives, lignite combustion causes the highest levels of greenhouse gas emissions. In order to reach the emission reduction goals, the government launched the process of accelerating the reduction of coal consumption. On 2 July, the Federal Ministry for Economic Affairs and Energy published a plan to reform the German energy market which will be implemented during the present term of government. Emission reduction from coal power plants is the most important issue. This problem has been extensively discussed over the past year and has transformed into a conflict between the government and the coal lobby. The dispute reached its peak when lignite miners took to the streets in Berlin. As the government admits, in order to reach the long-term emission reduction objectives, it is necessary to completely liquidate the coal energy industry in Germany. This is expected to take place within 25 to 30 years. However, since the decision to decommission nuclear power plants was passed, the German ecological movement and the Green Party have shifted their attention to coal power plants, demanding that these be decommissioned by 2030 at the latest.
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To shift to a low-carbon economy, the EU has been encouraging the deployment of variable renewable energy sources (VRE). However, VRE lack of competitiveness and their technical specificities have substantially raised the cost of the transition. Economic evaluations show that VRE life-cycle costs of electricity generation are still today higher than those of conventional thermal power plants. Member States have consequently adopted dedicated policies to support them. In addition, Ueckerdt et al. (2013) show that when integrated to the power system, VRE induce supplementary not-accounted-for costs. This paper first exposes the rationale of EU renewables goals, the EU targets and current deployment. It then explains why the LCOE metric is not appropriate to compute VRE costs by describing integration costs, their magnitude and their implications. Finally, it analyses the consequences for the power system and policy options. The paper shows that the EU has greatly underestimated VRE direct and indirect costs and that policymakers have failed to take into account the burden caused by renewable energy and the return of State support policies. Indeed, induced market distortions have been shattering the whole power system and have undermined competition in the Internal Energy Market. EU policymakers can nonetheless take full account of this negative trend and reverse it by relying on competition rules, setting-up a framework to collect robust EU-wide data, redesigning the architecture of the electricity system and relying on EU regulators.
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Policies and politics are an integral part of socio-technical transitions but have not received much attention in the transitions literature so far. Drawing on the advocacy coalition framework, our paper addresses this gap with a study on actors and coalitions in Swiss energy policy. Our results show that advocacy coalitions in Switzerland have largely remained stable despite the Fukushima shock. However, heterogeneity of beliefs has increased and in 2013, even a majority of actors expressed their support for the energy transition – an indication that major policy change might be ahead. It seems that in socio-technical transitions, changes in the policy issue and in the actor base also work toward policy change, next to changes in core beliefs. We make suggestions how the advocacy coalition framework can inform analysis and theory building in transition studies. We also present first ideas about the interplay of socio-technical systems and policy systems.
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Energy harvesting devices are widely discussed as an alternative power source for todays active implantable medical devices. Repeated battery replacement procedures can be avoided by extending the implants life span, which is the goal of energy harvesting concepts. This reduces the risk of complications for the patient and may even reduce device size. The continuous and powerful contractions of a human heart ideally qualify as a battery substitute. In particular, devices in close proximity to the heart such as pacemakers, defibrillators or bio signal (ECG) recorders would benefit from this alternative energy source. The clockwork of an automatic wristwatch was used to transform the hearts kinetic energy into electrical energy. In order to qualify as a continuous energy supply for the consuming device, the mechanism needs to demonstrate its harvesting capability under various conditions. Several in-vivo recorded heart motions were used as input of a mathematical model to optimize the clockworks original conversion efficiency with respect to myocardial contractions. The resulting design was implemented and tested during in-vitro and in-vivo experiments, which demonstrated the superior sensitivity of the new design for all tested heart motions.
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La réaction d’amination de liens C-H, impliquant la transformation directe d’un lien C-H en lien C-N constitue une approche synthétique d’avenir pour la préparation de composés azotés. L’application de cette stratégie de manière intramoléculaire apparaît comme une approche puissante pour la synthèse de composés hétérocycliques. En particulier, les oxazolidinones, carbamates cycliques à cinq chaînons, constituant une nouvelle classe d’antibiotiques très prometteuse, pourraient être synthétisées par cette méthode. Il y a moins d’une dizaine d’années, notre groupe de recherche a travaillé sur le développement de méthodologies utilisant des espèces nitrènes métalliques pour l’amination intra et intermoléculaire. Les N-tosyloxycarbamates, en présence d’une base et d’un catalyseur dimère de rhodium (II) tétracarboxylate sont les précurseurs de ces espèces nitrènes métalliques, capables de faire l’insertion de liens C(sp3)-H. Dans ces travaux de thèse, nous avons travaillé sur le développement d’une méthode plus « verte » d’amination intramoléculaire. Les N-mésyloxycarbamates, plus légers que leurs homologues N-tosyloxycarbamates, ont été identifiés comme d’excellents précurseurs de nitrènes. La méthodologie développée ne nécessite que 3 mol % de dimère de rhodium Rh2(tpa)4 et de 1,5 équivalents de solution aqueuse saturée de K2CO3, le tout dans l’acétate d’éthyle et donne de bons rendements de cyclisation. Une étude de l’étendue réactionnelle a été effectuée, montrant la tolérance et les limitations de notre système catalytique : les hétéroatomes ne posent pas de problèmes hormis l’atome d’azote, qui doit être protégé afin de garantir la transformation. En outre, nous avons constaté que les liens C-H aliphatiques secondaires sont moins réactifs que les liens tertiaires. Après avoir tenté de développer des conditions réactionnelles spécifiques aux liens C-H non activés, nous avons montré la possibilité d’aminer des liens C-H propargyliques de manière chimiosélective ; la triple liaison C-C peut ensuite être dérivatisée efficacement, donnant accès à la formule saturée correspondante ainsi qu’à d’autres motifs. Dans un désir de substituer les complexes de rhodium par d’autres complexes de métaux plus abondants et moins dispendieux, nous nous sommes tournés, dans un premier temps, vers les complexes de fer et par la suite, vers les pinceurs de nickel. Les phtalocyanines de fer ont été identifiées comme étant de bons catalyseurs de l’amination intramoléculaire de N-mésyloxycarbamates. Le chlorure de phtalocyanine de fer (III), en présence d’un sel de AgBF4 et de K2CO3, dans le 1,1,2,2-tétrachloroéthane anhydre, permet l’obtention de la 4-phenyloxazolidin-2-one avec 63% de rendement. En outre, il est possible d’atteindre un rendement de 49% à partir du même substrat N-mésyloxycarbamate, par catalyse avec un pinceur de nickel de type POCN, en présence d’un sel de mésylate. Des indices sur le mécanisme des ces deux transformations ont pu être recueillis lors de la courte étude de ces systèmes.
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"Serial no. 108-35."
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"DOE/EIA-0408."
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"July 1965."
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"May 12, 2006."
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Thesis (Ph.D.)--University of Washington, 2016-06
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Thesis (Master's)--University of Washington, 2016-06
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The design of a switched-beam antenna formed by a circular array of monopoles housed inside a radial guide with a transition to free space is presented. Two alternative types of transitions to free space, one using a truncated conducting cone and the other created by a tapered dielectric material at the edge of the radial guide, are described. The use of the radial guide with transition increases the return-loss bandwidth of the array and enables shaping its beam in elevation. (C) 2004 Wiley Periodicals, Inc.
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The metal-to-metal charge transfer (MMCT) transitions of a series of Class II mixed valence dinuclear complexes bearing cyano bridging ligands may be varied systematically by variations to either the hexacyanometallate(II) donor or Co-III acceptor moieties. Specifically, the new dinuclear species trans-[(LCoNCFe)-Co-14S(CN)(5)](-) (L-14S = 6-methyl-1,11-diaza-4,8-dithia- cyclotetradecane-6-amine) and trans-[(LCoNCRu)-Co-14(CN)(5)]-(L-14 = 6-methyl-1,4,8,11-tetraazacyclotetradecane-6-amine) have been prepared and their spectroscopic and electrochemical properties are compared with the relative trans-[(LCoNCFe)-Co-14(CN)(5)](-). The crystal structures of Na{trans-[(LCoNCFe)-Co-14S(CN)(5)]}.51/2H(2)O.1/2EtOH, Na{trans-[(LCoNCRu)-Co-14(CN)(5)]}.3H(2)O and Na{trans-[(LCoNCRu)-Co-14(CN)(5)]}.8H(2)O are also reported. The ensuing changes to the MMCT energy have been examined within the framework of Hush theory, and it was found that the free energy change between the redox isomers was the dominant effect in altering the energy of the MMCT transition.
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The syntheses and characterization of two new redox active cyclam ligands ferrocenylmethyl-(6-methyl-1,4,8,11-tetraazacyclotetradec-6-yl)-amine(L-3) and 1, 1'-ferrocenylmethyl-bis(6-methyl-1,4,8,11-tetraazacyclotetradec-6-yl)-amine (L-4) are reported. The compounds each possess a ferrocenyl group bearing one (L-3) or two (L-4) appended macrocycles linked by their exocyclic amino groups and the crystal structures of both compounds have been determined. Anion binding of L-3 and L-4 was investigated by electrochemical titrations where H-bonding to each macrocycle causing a shift in the Fc(+/0) redox potential was used as a reporter of guest binding. The Zn-II complex of L-3 has also been isolated and characterized structurally. These compounds were analysed for their capacity to electrochemically recognize anions in both aqueous and non-aqueous solution. We have found that L-3, L-4 and [ZnL3-](2+) sense Cl- and AcO- anions in MeCN-CH2Cl2, a function that is lost in aqueous solution.
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The ab initio/Rice-Ramsperger-Kassel-Marcus (RRKM) approach has been applied to investigate the photodissociation mechanism of benzene at various wavelengths upon absorption of one or two UV photons followed by internal conversion into the ground electronic state. Reaction pathways leading to various decomposition products have been mapped out at the G2M level and then the RRKM and microcanonical variational transition state theories have been applied to compute rate constants for individual reaction steps. Relative product yields (branching ratios) for C6H5+H, C6H4+H-2, C4H4+C2H2, C4H2+C2H4, C3H3+C3H3, C5H3+CH3, and C4H3+C2H3 have been calculated subsequently using both numerical integration of kinetic master equations and the steady-state approach. The results show that upon absorption of a 248 nm photon dissociation is too slow to be observable in molecular beam experiments. In photodissociation at 193 nm, the dominant dissociation channel is H atom elimination (99.6%) and the minor reaction channel is H-2 elimination, with the branching ratio of only 0.4%. The calculated lifetime of benzene at 193 nm is about 11 mus, in excellent agreement with the experimental value of 10 mus. At 157 nm, the H loss remains the dominant channel but its branching ratio decreases to 97.5%, while that for H-2 elimination increases to 2.1%. The other channels leading to C3H3+C3H3, C5H3+CH3, C4H4+C2H2, and C4H3+C2H3 play insignificant role but might be observed. For photodissociation upon absorption of two UV photons occurring through the neutral hot benzene mechanism excluding dissociative ionization, we predict that the C6H5+H channel should be less dominant, while the contribution of C6H4+H-2 and the C3H3+C3H3, CH3+C5H3, and C4H3+C2H3 radical channels should significantly increase. (C) 2004 American Institute of Physics.