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排序方式: 共有535条查询结果,搜索用时 15 毫秒
101.
This study attempts to identify in what aspects China and India are different and similar in forming consumer attitudes and purchase intentions toward US apparel brand goods. To this end, this study proposed a composite model incorporating the theory of planned behavior and a modified Fishbein model, and empirically compared the model with data collected in China and India. Structural equation modeling results yielded both similarities and differences in patterns of significance and the direction of effects for specific hypothesized paths. Differences were found in the paths of face saving → attitude, face saving → purchase intention (paths were positive and significant in the Chinese sample but non-significant in the Indian sample), group conformity → attitude and group conformity → purchase intention (paths were positive and significant in the Indian sample but non-significant in the Chinese sample). Similarities between two countries were found in the rest of the proposed paths. Based on the findings, discussions and implications were provided. 相似文献
102.
Dawei Di Heli Xu Ivan Perez‐Wurfl Martin A. Green Gavin Conibeer 《Progress in Photovoltaics: Research and Applications》2013,21(4):569-577
An all‐Si tandem solar cell has the potential to achieve high conversion efficiency at low cost. However, the selection and synthesis of candidate material remain challenging. In this work, we show that the conventional ‘Si quantum dots (Si QDs) in SiO2 matrix’ approach can lead to the formation of over‐sized Si nanocrystals especially when doped with phosphorous, making the size‐dependent quantum confinement less effective. Also, our investigation has shown that the high resistivity of this material has become the performance bottleneck of the solar cell. To resolve these matters, we propose a new design based on Si QDs embedded in a SiO2/Si3N4 hybrid matrix. By replacing the SiO2 tunnel barriers by the Si3N4 layers, the new material manages to constrain the growth of doped Si QDs effectively and enhances the apparent band gap, as shown in X‐ray diffraction, Raman, photoluminescence and optical spectroscopic measurements. Besides, electrical characterisation on Si QD/c‐Si heterointerface test structures indicates the new material possesses improved vertical carrier transport properties. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
103.
Gavin Sutton Robin Underwood Laurent Pitre Michael de Podesta Staf Valkiers 《International Journal of Thermophysics》2010,31(7):1310-1346
We report on two sets of isothermal acoustic measurements made with argon close to the triple point of water using a 50 mm
radius, thin-walled, diamond-turned quasisphere. Our two isotherms yielded values for the Boltzmann constant, k
B, which differ by 0.9 parts in 106, and have an average value of k
B = (1.380 649 6 ± 0.000 004 3) × 10−23J · K−1. The relative uncertainty is 3.1 parts in 106, and the average value is 0.58 parts in 106 below the 2006 CODATA value (Mohr et al. Rev Mod Phys 80:633, 2008), and so the values are consistent within their combined
(k = 1) uncertainties. 相似文献
104.
Herickhoff CD Grant GA Britz GW Smith SW 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2010,57(11):2572-2584
In this study, we investigated the feasibility of modifying 3-Fr IVUS catheters in several designs to potentially achieve minimally-invasive, endovascular access for image-guided ultrasound hyperthermia treatment of tumors in the brain. Using a plane wave approximation, target frequencies of 8.7 and 3.5 MHz were considered optimal for heating at depths (tumor sizes) of 1 and 2.5 cm, respectively. First, a 3.5-Fr IVUS catheter with a 0.7-mm diameter transducer (30 MHz nominal frequency) was driven at 8.6 MHz. Second, for a low-frequency design, a 220-μm-thick, 0.35 x 0.35-mm PZT-4 transducer--driven at width-mode resonance of 3.85 MHz--replaced a 40-MHz element in a 3.5-Fr coronary imaging catheter. Third, a 5 x 0.5-mm PZT-4 transducer was evaluated as the largest aperture geometry possible for a flexible 3-Fr IVUS catheter. Beam plots and on-axis heating profiles were simulated for each aperture, and test transducers were fabricated. The electrical impedance, impulse response, frequency response, maximum intensity, and mechanical index were measured to assess performance. For the 5 x 0.5-mm transducer, this testing also included mechanically scanning and reconstructing an image of a 2.5-cm-diameter cyst phantom as a preliminary measure of imaging potential. 相似文献
105.
Gavin S. Walker David M. Grant Tobias C. Price Xuebin Yu Vincent Legrand 《Journal of power sources》2009,194(2):1128-1134
LiBH4–MgH2 is an attractive reversible hydrogen storage system, it combines two high capacity hydrides (18.3 and 7.6 wt.%, respectively) and the concerted dehydrogenation reaction has a smaller enthalpy change than either species on its own. The latter effect leads to a destabilisation of the hydrided products and results in a lowering of the dehydrogenation temperature. In situ neutron diffraction experiments have been undertaken to characterise the mechanism of decomposition of the LiBD4–MgD2 system, with an emphasis on investigating the synergistic effects of the components during cycling under various conditions. This study compares the effect of stoichiometry of the multicomponent system on the cycling mechanism. Results show that LiBD4–MgD2 in a 2:1 molar ratio can be reversibly dehydrogenated under low pressures of hydrogen or under vacuum, contrary to earlier reports in the literature, although the reaction was only partially reversed for the 2:1 mixture decomposed under vacuum. This work shows that the reaction pathway was affected by dehydrogenation conditions, but the stoichiometry of the multicomponent system played a minor role. 相似文献
106.
Shaft Capacity of Continuous Flight Auger Piles in Sand 总被引:1,自引:0,他引:1
This paper presents the results of a series of field experiments performed to study the development of shaft resistance on continuous flight auger piles installed in sand. The test piles were instrumented in order to separate the shaft and base resistance, and to allow the determination of the distribution of shaft resistance along the pile shaft. The tests highlighted the importance of accurate calculation of the shaft resistance for nondisplacement piles. At a typical maximum allowable pile head settlement of 25?mm, more than 71% of the pile resistance was provided by shaft friction. Conventional methods of estimating shaft resistance were assessed. It was found that methods which incorporated parameters directly interpreted from in situ test results provided the most consistent estimates. In the final section, differences between the shaft resistances mobilized on displacement and nondisplacement piles are considered. 相似文献
107.
Psychrophilic and mesophilic anaerobic digestion of brewery effluent: a comparative study 总被引:1,自引:0,他引:1
Two expanded granular sludge bed-anaerobic filter (EGSB-AF) bioreactors (3.38 l active volume) were used to directly compare psychrophilic (15 degrees C), anaerobic digestion (PAD) to mesophilic (37 degrees C) anaerobic digestion (MAD) for the treatment of a brewery wastewater (chemical oxygen demand (COD) concentration of 3,136+/-891 mg l(-1)). Bioreactor performance was evaluated by COD removal efficiency and biogas yields at a range of hydraulic and organic loading rates. Specific methanogenic activity (SMA) assays were also employed to investigate the activity of the biomass in the bioreactors. No significant difference in the COD removal efficiencies (which ranged from 85-93%) were recorded between PAD and MAD during the 194-d trial at maximum organic and hydraulic loading rates of 4.47 kg m(-3) day(-1) and 1.33 m(3) m(-3) day(-1), respectively. In addition, the methane content (%) of the biogas was very similar. The volumetric biogas yield from the PAD bioreactor was approximately 50% of that from the MAD bioreactor at an organic loading rate of 4.47 kg COD m(-3) day(-3) and an applied liquid up-flow velocity (V(up)) of 2.5 m h(-1). Increasing the V(up) in the PAD bioreactor to 5 m h(-1) resulted in a volumetric biogas production rate of approximately 4.1 l d(-1) and a methane yield of 0.28 l CH(4) g(-1) COD d(-1), which were very similar to the MAD bioreactor. Significant and negligible biomass washout was observed in the mesophilic and psychrophilic systems, respectively, thus increasing the sludge loading rate applied to the former and underlining the robustness of the latter, which appeared underloaded. A psychrotolerant mesophilic, but not truly psychrophilic, biomass developed in the PAD bioreactor biomass, with comparable maximum SMA values to the MAD bioreactor biomass. PAD, therefore, was shown to be favourably comparable to MAD for brewery wastewater treatment and biogas generation. 相似文献
108.
Gavin H. C. Richards Kathryn L. Hong Michael Y. Henein Colm Hanratty Usama Boles 《International journal of molecular sciences》2022,23(9)
Coronary artery ectasia (CAE) is frequently encountered in clinical practice, conjointly with atherosclerotic CAD (CAD). Given the overlapping cardiovascular risk factors for patients with concomitant CAE and atherosclerotic CAD, a common underlying pathophysiology is often postulated. However, coronary artery ectasia may arise independently, as isolated (pure) CAE, thereby raising suspicions of an alternative mechanism. Herein, we review the existing evidence for the pathophysiology of CAE in order to help direct management strategies towards enhanced detection and treatment. 相似文献
109.
An investigation was made into a reasonable continuous sampling frequency for cardiac Purkinje fiber action potentials. Under the assumption that digital sampling will effectively capture frequency components up to half the sampling rate, action potential records made at 25 kHz were low-pass filtered at various cutoff frequencies. The filtered and unfiltered records were compared by calculating Vmax to determine the effects of progressive loss of high frequency components. It was determined that sampling at 13 kHz is adequate for action potentials with upstroke velocities up to 500 V/sec, and that estimation of Vmax in excess of 800 V/sec is possible. 相似文献
110.
Gavin M. Mudd Tamie R. Weaver Jayantha Kodikara 《Canadian Metallurgical Quarterly》2004,130(12):1514-1526
The long-term disposal of ash from brown coal combustion requires a thorough understanding of the geochemical controls on leachate quality. The geochemistry of leachate in ash generated from the combustion of coal in the Latrobe Valley region of Victoria, Australia, has been studied in the field and laboratory. The field studies, conducted over 14 months, showed active leaching and changes in leachate chemistry in the ash with mobilization of some trace elements. A further series of laboratory columns demonstrated similar leaching dynamics. Geochemical modeling indicated that both sulfate and carbonate minerals are the most likely solubility-controlling mineral phases in the ash. For regularly detected trace elements, such as As, Ba, and B but particularly Mo, Se, and Sr, the trends suggest that adsorption and coprecipitation controls are also important. The overall approach adopted in this paper has enabled a more realistic assessment of the controlling processes for solute transport during the active leaching phase of ash disposal, thereby improving long-term environmental management. 相似文献