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排序方式: 共有3705条查询结果,搜索用时 15 毫秒
1.
《International Journal of Hydrogen Energy》2022,47(10):6638-6649
Developing low cost, highly efficient, and long-term stability electrocatalysts are critical for direct oxidation methanol fuel cell. Despite huge efforts, designing low-cost electrocatalysts with high activity and long-term durability remains a significant technical challenge. Here, we prepared a new kind of platinum-nickel catalyst supported on silane-modified graphene oxide (NH2-rGO) by a two-step method at room temperature. Powder X-ray diffraction, UV–vis spectroscopy, Raman, FTIR spectroscopy and X-ray photoelectron spectroscopy results confirm that GO was successfully modified with 3-aminopropyltriethoxysilane (APTES), which helps to uniformly disperse PtNi nanoparticles. Cyclic voltammetry, chronoamperometry, CO-stripping and rotating disk electrode (RDE) results imply that PtNi/NH2-rGO catalyst has significantly higher catalytic activity, enhance the CO toxicity resistance, higher stability and much faster kinetics of methanol oxidation than commercial Pt/C under alkaline conditions. 相似文献
2.
《Ceramics International》2022,48(22):33122-33134
Gradient refractive index (GRIN) micro-optics present unique opportunities for control of the chromatic properties, new degrees of freedom for optical design as well as the potential for use in new optical system applications. GRIN microgratings were imprinted in GeS2-Ga2S3-MCl (M = Na, K, Cs) chalcohalide glasses by microthermal poling, and the effects of the type and concentration of alkali cations on their performance were investigated. Two effective imprinting formation regions of the GRIN microstructure based on the poling saturation voltage (Us) and glass composition are observed at fixed poling time and temperature. The Us increases from 140 to 750 and 2600 V in accordance with the activation energy (Ea) of alkali ions (Na+ to K+ and Cs+) increasing from 45.15 to 58.62 and 92.58 kJ/mol for studied samples. The saturated numbers of diffraction order (Ns) of the gratings in these samples are 7, 9 and 6, respectively, the highest number being provided by the K+-containing sample. This is in accordance with imprinting-induced phase differences (0.14λ, 0.19λ and 0.09λ) measured in the fabricated samples containing Na+, K+ and Cs+ ions. Furthermore, the Us of samples decreases from 1500 to 300 V with four concentrations of K+ from 10 to 30%, associated with their Ea of K+ decreasing from 69.62 to 53.46 kJ/mol, while Ns increases from 8 to 14, which is attributed to the increase of the phase difference in the GRIN structures. The controllable GRIN microstructures are realized by adjusting the type and concentration of alkali cations in chalcohalide glasses, which is expected to drive the design of broadband GRIN microgratings. 相似文献
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Tongling Xia Yue Qi Xilei Dai Jinyu Liu Can Xiao Ruoyu You Dayi Lai Junjie Liu Chun Chen 《Indoor air》2021,31(6):2020-2032
To evaluate the separate impacts on human health and establish effective control strategies, it is crucial to estimate the contribution of outdoor infiltration and indoor emission to indoor PM2.5 in buildings. This study used an algorithm to automatically estimate the long-term time-resolved indoor PM2.5 of outdoor and indoor origin in real apartments with natural ventilation. The inputs for the algorithm were only the time-resolved indoor/outdoor PM2.5 concentrations and occupants’ window actions, which were easily obtained from the low-cost sensors. This study first applied the algorithm in an apartment in Tianjin, China. The indoor/outdoor contribution to the gross indoor exposure and time-resolved infiltration factor were automatically estimated using the algorithm. The influence of outdoor PM2.5 data source and algorithm parameters on the estimated results was analyzed. The algorithm was then applied in four other apartments located in Chongqing, Shenyang, Xi'an, and Urumqi to further demonstrate its feasibility. The results provided indirect evidence, such as the plausible explanations for seasonal and spatial variation, to partially support the success of the algorithm used in real apartments. Through the analysis, this study also identified several further development directions to facilitate the practical applications of the algorithm, such as robust long-term outdoor PM2.5 monitoring using low-cost light-scattering sensors. 相似文献
5.
匡红云 《上海第二工业大学学报》2019,(4):298-303
澳大利亚职业教育在全球享有较高的声誉,这与其坚持严格的"基于能力本位的评估"(competency based assessment, CBA)密不可分。介绍了澳大利亚CBA的内涵特征,并详细描述"准备评估、开发评估工具、开展评估、对评估结果进行评估"的CBA运作过程,关注评估工具的开发和后续常规系统性检查及完善,以期对我国的高等职业教育质量评估起到启示和借鉴作用。 相似文献
6.
以某典型废玻璃回收厂区作为研究对象, 监测和分析了车间及厂区内部的噪声强度、空气颗粒物(PM2.5、PM10) 浓度等环境指标, 点位布设涵盖了车间入口、人工分拣、物料筛分、破碎、干法清洗等关键工艺环节; 其次, 解析了空气颗粒物的组分及形貌特征, 并对其在厂区及车间内部的时空分布特征进行了研究; 此外, 利用噪声控制模型模拟并分析了隔声罩对噪声的控制作用。结果表明, 生产车间中工作态的空气颗粒物浓度显著高于非工作态, 其中干法清洗区浓度最高, 其PM2.5 浓度为3.725 mg/m3, PM10浓度为4.055 mg/m3; 噪声监测结果显示生产车间内噪声强度较高, 达到99.5 dB, 而引入隔声罩后噪声强度可降至67 dB, 结果表明, 隔声罩可有效控制频率为125~1 000 Hz 的噪声。该研究可为废玻璃的绿色、高效回收处置提供理论基础和实践经验。 相似文献
7.
《Ceramics International》2022,48(7):9651-9657
Friction is a common clean energy and can be harvested and converted into electricity energy via triboelectricity, which can electrochemically drive dye decomposition in theory. In this work, the tribocatalytic Rhodamine B dye decomposition has been experimentally realized in strontium titanate (SrTiO3) nanofibers, which are synthesized via a hydrothermal method. In the tribocatalytic dye decomposition process, the friction is exerted in the interface between catalyst surface and a polytetrafluoroethylene (PTFE) Teflon rod setup with the different stirring speed. The RhB dye decomposition ratios of SrTiO3 nanofibers at these stirring speeds of 200 rpm, 400 rpm, 600 rpm, and 800 rpm are respectively 24.2%, 51.8%, 73.9% and 88.6%, yielding to these reaction rate constants of ~0.0112 h?1, ~0.0260 h?1, ~0.0562 h?1 and ~0.0877 h?1. The main active species, which play an important role in tribocatalytic process, are the superoxide radicals and holes on basis of the active species quenching experiment results. The excellent tribocatalysis activity makes SrTiO3 nanofibers potential for application in dye wastewater treatment through utilizing the environmental friction energy. 相似文献
8.
Multimedia Tools and Applications - Background modeling and subtraction, the task to detect moving objects in a scene, is a fundamental and critical step for many high level computer vision tasks.... 相似文献
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10.
《International Journal of Hydrogen Energy》2020,45(1):904-915
A solid oxide fuel cell based on double-sided cathodes is developed in our group, showing special properties and many advantages under some harsh conditions. To optimize the cell further, a thermo-electro-chemo-mechanical coupled 3D model is developed to simulate the distributions of temperature, current density, fuel gas and thermal stress under different voltages. The numerical results indicate that the temperature distribution, current, fuel gases and thermal stress is non-uniform in the cell at different voltages. The distribution of thermal stress in the electrolyte is also non-uniform because of the un-even electrochemical reaction and convective heat transfer. Furthermore, the result shows that about 47%~54% of maximum 1st principal stress in SOFC is caused by the mismatch of coefficients of thermal expansion (CTEs) among materials, while the other part of the maximum 1st principal stress is mainly caused by temperature gradient. 相似文献