4381   Rate of exciton scattering and exciton absorption in crystals with LO-phonon dispersion Rate of exciton scattering and exciton absorption in crystals with LO-phonon dispersion    2003 Using the Ridley-Babiker relation for the LO-phonon energy, an exact formula for the exciton scattering rate in the one-phonon approximation is obtained. The effect of LO-phonon dispersion on the frequency and temperature dependence of the exciton attenuation is studied theoretically for the models of polar crystals with large and small exciton radii. It is shown that the role of LO-phonon dispersion is essentially different in processes with phonon absorption and phonon emission. For some fixed... 查看全文

4382   Source reactivity as an extra kinetic characteristic of coupled-source subcritical systems Source reactivity as an extra kinetic characteristic of coupled-source subcritical systems    2005 The objective of the present work is to study the kinetic (i.e., in absence of in-core feedbacks) response of the subcritical system to variation of the efficiency of the external neutron source. The particular class of the subcritical system with the intensity of the external source being intrinsically dependent on neutron production in the core (so-called coupled hybrid systems) is considered. The accelerator coupled system is taken as example, although this analysis may be expanded to other t... 查看全文

4383   Hydrogen sorption performance of MgH2 doped with mesoporous nickel- and cobalt-based oxides Hydrogen sorption performance of MgH2 doped with mesoporous nickel- and cobalt-based oxides    2011 The effect of mesoporous Co3O4, NiCo 2O4 and NiO on the hydrogen sorption performance of MgH2 was investigated. These oxides were synthesized by multi-step nanocasting and introduced during the high-energy ball milling of MgH 2 powder to act as catalysts. Hydrogen desorption on the as-milled powders was assessed upon heating the samples from room temperature to 400 °C. In all cases, the onset temperature for desorption was lowered by taking advantage of the introduced additives. The NiO-dope... 查看全文

4384   Intrinsic degradation of FeTi by thermally induced hydrogen absorption-desorption cycling Intrinsic degradation of FeTi by thermally induced hydrogen absorption-desorption cycling    1988 The deterioration of the hydrogenation properties of FeTi during thermally induced hydrogen absorption-desorption cycling was investigated using the following: (i) the change in the P-C-T curves as a function of the number of cycles, (ii) X-ray diffraction, and (iii) the thermal desorption of hydrogen after cycling. The results of the thermal desorption of hydrogen provide information about the hydrogen occupation at various interstitial sites, which are distinguished by different binding energi... 查看全文

4385   Solar desalination of sea water Solar desalination of sea water    1993 A mathematical expression is derived to predict the amount of fresh water produced from the sea water in a solar still as a function of climatic conditions and initial condition of the sea water through a simplified vapor pressure correlation. The flow rate and the inlet temperature of the sea water and the insolation influence the thermal performance of the still. Tilted stills can perform. more efficiently than basin types owing to a faster response to incident solar radiation and better energ... 查看全文

4386   Hydrogen-absorbing alloys with a large capacity for a new energy carrier Hydrogen-absorbing alloys with a large capacity for a new energy carrier    2002 In order to apply hydrogen-absorbing alloy to a new energy carrier such as a hydrogen storage tank or a Ni-MH battery, a drastic increase in hydrogen capacity of the alloy is required. For years, intermetallic compounds or single-phase alloys have been studied as hydrogen-absorbing alloys. On the contrary, we have proposed a new approach to the alloy design related to multi-phase. Through this approach, we developed a new BCC alloy consisting of the microstructure that has a large hydrogen capac... 查看全文

4387   Numerical prediction of InGaAs/GaAs MQW solar cell characteristics under concentrated sunlight Numerical prediction of InGaAs/GaAs MQW solar cell characteristics under concentrated sunlight    1998 The characteristics of InGaAs/GaAs multi-quantum well (MQW) solar cells under concentrated sunlight were analyzed by self-consistent numerical calculation and were compared with GaAs p-i-n cells that have the same structure except for the QWs. Prior to the calculations, the absorption coefficients of the InGaAs MQW cell were determined by fitting the calculated quantum efficiencies to experimental ones. In the simulation, mainly the influences of concentrated sunlight and temperature were invest... 查看全文

4388   New insight into the excited-state proton-transfer reactions of 1-naphthylamine in solution New insight into the excited-state proton-transfer reactions of 1-naphthylamine in solution    2001 Proton-transfer reactions from the excited state of 1-naphthylamine (RNH2) have been investigated in aqueous solutions of various HClO4 concentrations. The system is found to contain three species rather than simply the acidic and the neutral form. of RNH2 as previously believed. The new species X, can be clearly detected at [HClO4] ≥ 5 M, in both absorption and emission. X is proposed to be an adduct of RNH2 and an unhydrated HClO4, i.e., X ≡ RNH2- - -H+- - -ClO4-. Absorption and fluor... 查看全文

4389   Investigation of collision-induced absorption in the vibrational fundamental bands of O2 and N2 at elevated temperatures Investigation of collision-induced absorption in the vibrational fundamental bands of O2 and N2 at elevated temperatures    2005 Collision-induced absorption has been measured for the vibrational fundamental bands of N2 and O2 at temperatures up to 360 K. These data when combined with previously obtained lower temperature data show that the integrated band intensity of the O2 fundamental increases as the temperature is raised above 300 K. The integrated intensity of the N 2 band also increases, but at a much lower rate with temperature. Published by Elsevier Inc. 查看全文

4390   Measurements of photophysiological parameters and primary production in the Central North Pacific Ocean Measurements of photophysiological parameters and primary production in the Central North Pacific Ocean    1997 The North Pacific Central Gyre is one of the largest homogenous bodies of water on Earth. Phytoplankton distributions appear to remain relatively constant for thousands of kilometers throughout the year. However, recent studies conducted at Station ALOHA as part of the Hawaii Ocean Time-series (HOT) program reveal significant seasonal and interannual variability in phytoplankton biomass and production rates. Despite the high resolution sampling performed at the HOT site, spatial and temporal var... 查看全文

4391   Absorbed dose rate conversion coefficients for reference terrestrial biota for external photon and internal exposures Absorbed dose rate conversion coefficients for reference terrestrial biota for external photon and internal exposures    2004 The paper describes dosimetric models that allow the estimation of average radiation exposures to terrestrial biota due to environmental sources in the soil as well as internal uniform. distributions of radionuclides. Simple three-dimensional phantoms for 13 faunal reference organisms are specified. The calculation of absorbed dose per unit source strength for these targets is based on photon and electron transport simulations using the Monte Carlo method. The presented absorbed dose rate conver... 查看全文

4392   EUV spectral energy distribution of quasars restored from associated absorbers EUV spectral energy distribution of quasars restored from associated absorbers    2008 Aims. We reconstruct the spectral shape of the quasar ionizing radiation in the extreme-UV range (1 Ryd Ryd) from the analysis of narrow absorption lines (NAL) of the associated systems.Methods. The computational technique for inverse spectroscopic problems - a Monte Carlo Inversion augmented by the spectral shape recovering procedure and modified to account for the incomplete coverage of the light source is used to analyze observations.Results. The ionizing spectra responsible for the ionizatio... 查看全文

4393   CHEMICAL, STRUCTURAL AND OPTICAL CHARACTERIZATION OF Ni-P CHEMICAL CONVERSION COATINGS FOR PHOTOTHERMAL ABSORPTION OF SOLAR ENERGY. CHEMICAL, STRUCTURAL AND OPTICAL CHARACTERIZATION OF Ni-P CHEMICAL CONVERSION COATINGS FOR PHOTOTHERMAL ABSORPTION OF SOLAR ENERGY.    1986 I describe the investigation of a nickel-phosphorus thin film produced by chemical deposition. Its absorbing properties are enhanced for wavelengths within the visible and near-infrared spectral regions by modification of its surface state during chemical etching. The prepared layers show, by themselves, noteworthy structural properties that influence the chemical etching; because of them, it is possible to obtain highly solar selective optical properties under some conditions. The coating can w... 查看全文

4394   Role of laser heating in the intrinsic optical bistability of Yb3+-doped bromide lattices Role of laser heating in the intrinsic optical bistability of Yb3+-doped bromide lattices    2000 Materials displaying intrinsic optical bistability (IOB), i.e., allowing the coexistence of two stable steady-state excitation rates for a single given excitation power, are of interest for potential technological applications related to optical data switching and manipulation. The properties of the unusual IOB previously observed in Yb3+-doped Cs3Lu2Br9 and CsCdBr3 host materials are studied here using absorption and luminescence spectroscopies. The IOB phenomenon is concluded to derive ultimat... 查看全文

4395   In situ electron yield detection of X-ray absorption fine structure of electrodes continuously emersed from electrolyte solutions In situ electron yield detection of X-ray absorption fine structure of electrodes continuously emersed from electrolyte solutions    2003 A method is described herein for the acquisition of in situ electron yield X-ray absorption fine structure (XAFS) data of solid electrodes continuously emersed from electrolyte solutions. The success of this measurement technique relies on two key features: (i) the use of a curtain-type He jet emerging from a torch blower impinging directly on the surface of the emersed electrode to decrease the thickness of the electrolyte dragged by the electrode and eliminate droplets adhered to the surface; ... 查看全文

4396   Calculation of electron transfer rate constants from emission spectra in Re(I) chromophore-quencher complexes Calculation of electron transfer rate constants from emission spectra in Re(I) chromophore-quencher complexes    2002 The photophysical properties of the chromophore-quencher complexes, fac-[(4,4′-R2bpy)ReI(CO)3(LA)]n+ (4,4′-R2bpy = 4,4′-R2-2,2′-bipyridine, R = Me or tBu, and LA = the quinone acceptor ligands, benz[g]- isoquinoline-5,10-dione (BIQD), 2-oxy-1,4-naphthoquinone anion (ONQ-), 1/2 2,6-dihydroxyanthraquinone dianion (AFA2-), or the pyridinium acceptor, 1-methyl-6-oxyquinoline (OQD)) in 1,2-dichloroethane are described. Following ReI &rarr 4,4′-R2bpy metal-to-ligand char... 查看全文

4397   Carrier relaxation dynamics in high temperature superconductors Carrier relaxation dynamics in high temperature superconductors    2002 In this report we review recent experimental results on photoexcited carrier relaxation dynamics on high temperature superconductors (HTSC) probed by a femtosecond time-resolved optical spectroscopy, and compare the results with the data obtained on quasi two dimensional charge density waves. In these experiments, a femtosecond laser pump pulse excites electron-hole pairs via an inter-band transition in the material. These hot carriers rapidly release their energy via electron-electron and elect... 查看全文

4398   Fischer-tropsch synthesis: An in-situ TPR-EXAFS/XANES investigation of the influence of group i alkali promoters on the local atomic and electronic structure of carburized iron/silica catalysts Fischer-tropsch synthesis: An in-situ TPR-EXAFS/XANES investigation of the influence of group i alkali promoters on the local atomic and electronic structure of carburized iron/silica catalysts    2010 The promoting impact of alkali metals (i.e., Li, Na, K, Rb, Cs) on the carburization rate of Fe in Fe/Si catalysts was investigated by X-ray absorption spectroscopy. A multisample holder was used, allowing nearly simultaneous examination of the catalysts during activation in a CO/He mixture. With the white line intensity and shape as a fingerprint for oxidation state, TPR/XANES analysis enabled us to measure the relative composition of the different compounds as a function of the carburization t... 查看全文

4399   Transverse impact behavior. and energy absorption of three-dimensional orthogonal hybrid woven composites Transverse impact behavior. and energy absorption of three-dimensional orthogonal hybrid woven composites    2007 The transverse impact behaviors of three-dimensional (3D) orthogonal hybrid woven fabric composites were tested on a modified split Hopkinson pressure bar (SHPB) apparatus. The load-displacement curves of the composites in transverse impact were obtained to analyze the strain rate sensitivity of energy absorption. It was found that energy absorption of the composites increases with the impact velocity (i.e., strain rate). The failure modes under quasi-static transverse loading are tensile failur... 查看全文

4400   Dynamic Biaxial Plastic Buckling of circular shells Dynamic Biaxial Plastic Buckling of circular shells    2008 Of particular interest is the experimental study of the complex dynamic plastic buckling of circular metallic shells and their energy absorption capacity. Initially proposed by Baleh and Abdul-Latif (2006), "Quasi-Static Biaxial Plastic Buckling of Tubular Structures used as an Energy Absorber," ASME J. Appl. Mech., 74, pp. 638-635, the novel idea, which aims to enhance the strength properties of materials, is extended for studying the biaxial plastic dynamic buckling behavior. of circular shell... 查看全文

4401   A study of a solar-driven diffusion-absorption refrigerator with an adiabatic spray absorber A study of a solar-driven diffusion-absorption refrigerator with an adiabatic spray absorber    2009 In order to utilize solar energy to drive absorption refrigeration system to meet the requirements of reserving food and air conditioning in a family at the same time, a new type of diffusion-absorption refrigeration experiment set with an adiabatic spray absorber is designed and manufactured. The triple fluid of LiNO3/NH3/He is used as working fluid. Based on the prototype machine and the stable thermodynamic models, theoretical results shows that the system can operate at evaporating temperatu... 查看全文

4402   Collisional energy transfer between excited Rb atoms Collisional energy transfer between excited Rb atoms    2009 Energy pooling (EP) was observed in Rb vapor following pulsed optical excitation to the 5P1/2 state. The 5P3/2 state was populated by the energy transfer process: Rb (5P1/2) + Rb (5S1/2) &rarr Rb (5P3/2) + Rb (5S1/2). The resulting densities of Rb atoms at the 5P1/2 level were obtained from the absorption of narrow spectral line from a Rb hollow cathode lamp, connecting the 5P1/2 state to 7S state. Since the effective lifetimes of the 5P1/2 and 5P3/2 states are approximately equal, the densities... 查看全文

4403   Experimental study of energy absorption in a close-celled aluminum foam under dynamic loading Experimental study of energy absorption in a close-celled aluminum foam under dynamic loading    1999 The dynamic response of a close-celled Al foam was examined in compression at a strain rate 2.5×103/s. The mechanical properties of the metallic foam were also studied at a quasi-strain rate of 1×10-3/s. The yield stress of the Al foam exhibited a remarkable strain rate sensitivity, as compared to a polystyrene foam which showed only a weak dependence. The absorption energy per unit volume of the Al foam at the dynamic strain rate 2.5×103/s was greater than that at the quasi-st... 查看全文

4404   Research on nano-coating absorption application in laser processing Research on nano-coating absorption application in laser processing    2010 As more and more special refractory materials apply to laser processing technology, many processing problems have highlighted, this article studies on how to improve the laser absorption rate in the processing of work piece, and proposes the method of nanometers particles attached to improve absorption efficiency of laser materials before the laser processes smooth surface work piece materials, to analysis and forecast the theoretical effects[1]. Through the laser processing energy loss analysis... 查看全文

4405   Kinetic and thermodynamic investigation of hydrogen absorption by ternary LaNi4Al and LaNi4Al-Pd alloys Kinetic and thermodynamic investigation of hydrogen absorption by ternary LaNi4Al and LaNi4Al-Pd alloys    1991 The process of hydrogen absorption by ternary LaNi4Al and LaNi4Al-Pd alloys was investigated by a differential scanning calorimetry method in an atmosphere of hydrogen flow over the temperature range from room temperature to 600°C as well as by X-ray analysis. It was shown that the exothermic process of hydrogen absorption by the LaNi4Al alloy takes place within two temperature regions, at about 100 and 450°C, respectively. In case of multiple absorptions and desorptions (as a consequenc... 查看全文

4406   Z-scan technique for quantifying the excited-state parameters of the reverse saturable absorbing dye 1,1,3,3,3,3-hexamethylindotricarbocyanine iodide (HITCI) Z-scan technique for quantifying the excited-state parameters of the reverse saturable absorbing dye 1,1,3,3,3,3-hexamethylindotricarbocyanine iodide (HITCI)    1994 Reverse saturable absorption (RSA) is increasing absorption due to a high-fluence laser pulse. The increasing absorption arises from molecules in an excited state having an absorption cross section larger than the ground-state cross section. The Z-scan technique has been used to measure the RSA properties of a cyanine dye. A frequency-doubled, Q-switched Nd:YAG laser with Gaussian temporal and spatial pulses of 15 ns (FWHM) is used. The pulses are focused to a beam radius of 14.5 μm (1/e-2). ... 查看全文

4407   Effects of available energy and impact rate on Charpy absorbed energy in the upper shelf Effects of available energy and impact rate on Charpy absorbed energy in the upper shelf    2006 Advances in steelmaking technology have led to the introduction of structural steels with increased strength and toughness, to the extent that the energy absorbed by Charpy samples tested in the upper shelf region commonly approaches or exceeds the maximum available energy in conventional pendulum impact machines. In these circumstances, it becomes relevant to re-examine the validity of absorbed energy values measured in cases where the absorbed energy is a large fraction of the available energy... 查看全文

4408   Progressive crush response of multi-element foam-filled preform. RTM structures, I: architecture and rate effects Progressive crush response of multi-element foam-filled preform. RTM structures, I: architecture and rate effects    1995 The application of composites in automotive structures has been a topic of increasing interest in recent years. This has largely been driven by the need for energy efficiency, increased safety requirements, economics related to fabrication, and the designer's need for enhanced flexibility in form. through increased materials and processing options. The main objective of this study was to investigate the effect of multi-element preform. fiber architectures for a resin transfer molded structural (... 查看全文

4409   Recent progress in laser surface treatment: I. Implications of laser wavelength Recent progress in laser surface treatment: I. Implications of laser wavelength    1996 The coupling mechanisms of laser radiation and the mechanisms of heart transport in the workpiece are considered. Starting from the well-known basics of Fresnel absorption - valid only for smooth and clean surfaces - further effects of coupling are examined. Studies on the effects of surface modifications inherent to all industrial parts and process conditions are presented. The more appropriate term coupling rate is introduced: This describes the ratio of the total energy coupled into the workp... 查看全文

4410   Cross-sectional evidence of suppressed bone mineral accrual among female adolescent runners Cross-sectional evidence of suppressed bone mineral accrual among female adolescent runners Gilbert Kuepouo, Hiroaki Sato, Jean-Pierre Tchouankoue and Mamoru Murata    2010 We aimed to evaluate patterns of bone mineral accrual among a cross-sectional sample of female adolescent runners and girls participating in a nonendurance running sport. One-hundred and eighty-three interscholastic competitive female athletes (age 16.0 ± 0.1 years), 93 endurance runners and 90 nonrunners, completed a menstrual and sports history questionnaire, had their height and weight measured, and underwent a dual-energy X-ray absorptiometry scan for the measurements of... 查看全文

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