Search results for " conversion"
showing 10 items of 447 documents
Efficient energy conversion for cubic third-harmonic generation that is phase matched in KTiOPO(4).
2000
We demonstrate, for the first time to our knowledge, that efficient third-harmonic generation can be achieved with a cubic contribution much larger than the quadratic processes. An energy-conversion efficiency of 2.4% is achieved for cubic third-harmonic generation that is phase matched along the x axis of a KTiOPO(4) crystal by use of a picosecond fundamental laser emitting at 1618 nm. The associated cascading processes are only 10% of the pure cubic interaction, which is very suitable for study of the specific quantum optical correlations. Calculations of the third-harmonic generation conversion efficiency with respect to group-velocity dispersion and to the longitudinal Gaussian beam pro…
Electrochemical reduction of carbon dioxide to formic acid at a tin cathode in divided and undivided cells: effect of carbon dioxide pressure and oth…
2016
Abstract The reduction of carbon dioxide to formic acid at a tin cathode was studied in both divided and undivided cells. In the first stage of the study, the effect of some operating parameters, including the working potential and the nature of the supporting electrolyte and of the cathode, on both the cathodic reduction of CO2 and the anodic oxidation of formic acid was investigated in a divided cell. In a second stage, the reduction of carbon dioxide was performed in an undivided cell with the aim of studying the effect on the generation of formic acid of various operating parameters such as current density, cathode to anode area ratio, mixing rate and nature of the anode and of the supp…
Second-harmonic generation in surface periodically poled lithium niobate waveguides:On the role of multiphoton absorption
2008
Second harmonic generation is investigated in lithium niobate channels realized by proton exchange and quasi-phase-matched by surface periodic-poling. The reduction in conversion efficiency at high powers is interpreted in terms of multi-photon absorption via two-color terms, yielding an estimate of the dominating three-photon process.
Fabrication and characterization of ZnO nanowires/CdSe/CuSCN eta-solar cell
2006
Des cellules solaires extremely thin absorber (eta) ZnO/CdSe/CuSCN a base de nanofils de ZnO ont ete realisees avec succes en utilisant des techniques faciles d'acces de depot en solution et par voie electrochimique. Une couche constituee de nanofils de ZnO monocristallin de plusieurs microns de hauteur et de 100-200 nm de diametre a ete deposee sur un substrat de verre conducteur (SnO 2 :F) recouvert d'une couche de ZnO formee par pyrolyse de spray agissant comme couche electronique bloquante. Une couche mince de 30-40 nm de CdSe jouant le role d'un absorbeur a ete electrodeposee de maniere conforme le long des nanofils de ZnO. Les espaces entre les nanofils composite de ZnO/CdSe ont ete r…
Counter-propagating frequency mixing with Terahertz waves in diamond
2013
Frequency conversion by means of Kerr nonlinearity is one of the most common and exploited nonlinear optical processes in the UV, visible, IR, and mid-IR spectral regions. Here we show that wave mixing of an optical field and a terahertz wave can be achieved in diamond, resulting in the frequency conversion of the terahertz radiation either by sum- or difference-frequency generation. In the latter case, we show that this process is phase matched and most efficient in a counterpropagating geometry.
Sperata resilienza
2018
Il termine ‘resilienza’ proveniva dalla metallurgia: indica, nella tecnologia metallurgica, la capacità di un metallo di resistere alle forze che vi vengono applicate. Per un metallo, la resilienza rappresenta il contrario della fragilità. Così anche in campo psicologico: la persona resiliente è l’opposto di una facilmente vulnerabile, ovvero che vive: la Notte dell’io (Mormese C., 2004). Etimologicamente ‘resilienza’ viene fatta deriva dal latino resalio, iterativo di salio. Qualcuno propone un collegamento suggestivo fra il signiicato originario di resalio, che connotava anche il gesto dell’uomo di risalire sull’imbarcazione capovolta dalla forza del mare, e l’attuale utilizzo in campo ps…
Maturation of critical technologies for the DEMO balance of plant systems
2022
The Pre-Concept Design (PCD) of the Balance of Plant (BoP) systems of the EU-DEMO power plant is described in this paper for both breeding blanket (BB) concepts under assessment, namely the Water Cooled Lithium Lead (WCLL) BB and the Helium Cooled Pebble Bed (HCPB) BB. Moreover, the results of a preliminary evaluation of a number of BoP variants are discussed. This paper outlines the steps of the BoP design development, highlighting the project objectives and the strategy for their achievement under the very challenging requirements which include, among others, the intermittent nature of the DEMO plasma heat source. The main achievements during the PCD Phase will be reported together with t…
Power Bus Management Techniques for Space Missions in Low Earth Orbit
2021
In space vehicles, the typical configurations for the Solar Array Power Regulators in charge of managing power transfer from the solar array to the power bus are quite different from the corresponding devices in use for terrestrial applications. A thorough analysis is reported for the most popular approaches, namely Sequential Switching Shunt Regulation and parallel-input Pulse Width Modulated converters with Maximum Power Point Tracking. Their performance is compared with reference to a typical mission in low Earth orbit, highlighting the respective strengths and weaknesses. A novel solar array managing technique, the Sequential Maximum Power Tracking, is also introduced in the trade-off a…
Sea Wave Energy. A Review of the Current Technologies and Perspectives
2021
The proposal of new technologies capable of producing electrical energy from renewable sources has driven research into seas and oceans. Research finds this field very promising in the future of renewable energies, especially in areas where there are specific climatic and morphological characteristics to exploit large amounts of energy from the sea. In general, this kind of energy is referred to as six energy resources: waves, tidal range, tidal current, ocean current, ocean thermal energy conversion, and saline gradient. This review has the aim to list several wave-energy converter power plants and to analyze their years of operation. In this way, a focus is created to understand how many …
ChemInform Abstract: Synthesis of (+)-Isoalantolactone and (+)-Isoalloalantolactone from (-) -Santonin.
2010
Abstract This paper reports on the chemical conversion of (−)-santonin into (+)-isoalantolactone and (+)-isoalloalantolactone involving functionality transfer from C 6 to C 8 , refunctionalization of the ring A and the formation of the α-methylene-8 β,12-olide moiety.