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51.
Nannan Chen Yanhong Wang Xiaoqiang Du Xiaoshuang Zhang 《International Journal of Hydrogen Energy》2021,46(49):25114-25120
Urea electrolysis is a promising technology for hydrogen production, which can alleviate environmental pollution of urea-rich wastewater. It's worth noting that electrochemistry activity can be significantly improved by reasonably regulating the electron configuration around the active site for the doped materials. In this work, a series of well-tuned Ni doped CoWO4 nanoarrays on Ni foam supports have been prepared through a typical hydrothermal approach for the first time. Moreover, the resulting Ni–CoWO4-2 material significantly promotes urea oxidation performance with an applied potential of 1.35 V at 50 mA cm?2, which is lower than that of water oxidation reaction (1.60 V). Density functional theory results suggest that the Ni doped CoWO4 has larger urea adsorption energy compared with CoWO4 and the CO(NH2)2 molecule is strongly adsorbed on surface of Ni doped CoWO4, which is beneficial to accelerate the kinetics of the reaction and improve the electrocatalytic activity of the urea electrolysis. 相似文献
52.
53.
Verification of unified effective stress theory based on the effect of moisture on mechanical properties of fiber reinforced unsaturated soil 总被引:1,自引:0,他引:1
Omar Al Hattamleh Samer Rababah Ahmad Alawneh Ahmad Alqawab'ah 《Geotextiles and Geomembranes》2021,49(4):976-990
The unified effective stress theory based on suction stress (SSCC theory) enables the characterization of soils under both saturated and unsaturated conditions with one closed-form relationship. This study provides experimental verification of this theory through the unconfined compressive strength test (UCS) and indirect tensile test strength (ITS) on silty clay soil stabilized with fiber. A series of matric suction, ITS, and UCS tests were conducted to validate the SSCC theory through the representation of the results of ITS and UCS tests in terms of mean total stress (p) versus deviatoric stress (q) and mean effective stress (p`) versus deviatoric stress (q). The results of the validation procedures showed that the SSCC theory is applicable and valid at a range of 6%–16% of water content on the silty clay and the silty clay fiber-reinforced soils. There is a small fluctuation in the increase of ITS and UCS values with increasing fiber content due to randomly oriented distribution of the fiber. The addition of glass fiber does not significantly affect the capacity of water retention of the soil. It improves the condition of the mechanical soil properties at the end of construction more than of the effective stress condition. 相似文献
54.
《International Journal of Hydrogen Energy》2021,46(58):30061-30078
A uniform solid product layer normally assumed in the shrinking-core model cannot predict the kinetic transition behavior of the H2 adsorption reactions. In this study, the concept of a uniform solid product layer has been replaced by that of the inward growth of solid products on the solid surface. A rate equation is established to calculate the inward growth of the solid product and was implemented into the shrinking-core model to calculate the H2 adsorption kinetics for various shapes of Mg-based materials. The prediction accuracy of the developed model is verified from the detailed experimental data. To account for the external gas diffusion around the particle and the intraparticle gas diffusion, an analytical equation is derived using the Thiele modulus method. This model can be used to analyze various kinetic aspects and to analyze the effect of change in the particle microstructure on intraparticle diffusion. 相似文献
55.
Gang Liu Jingjing Li Chao Dong Liyuan Wu Dan Liang Huawei Cao Pengfei Lu 《International Journal of Hydrogen Energy》2021,46(35):18294-18304
Searching for the catalysts with excellent catalytic activity and high chemical stability is the key to achieve large-scale production of hydrogen (H2) through hydrogen evolution reaction (HER). Two-dimensional (2D) platinum and palladium dichalcogenides with extraordinary electrical properties have emerged as the potential candidate for HER catalysts. Here, chemical stability, HER electrocatalytic activity, and the origin of improved HER performance of Pt/Pd-based dichalcogenides with single-atom doping (B, C, N, P, Au, Ag, Cu, Co, Fe, Ni, Zn) and vacancies are explored by first-principles calculations. The calculated defect formation energy reveals that most defective structures are thermodynamically stable. Hydrogen evolution performance on basal plane is obviously improved by single-atoms doping and vacancies. Particularly, Zn-doped and Te vacancy PtTe2 have a ΔGH value close to zero. Moreover, defect engineering displays a different performance on HER catalytic activity in sulfur group elements, in order of S < Te < Se in Pd-based chalcogenides, and S < Se < Te in Pt-based chalcogenides. The origin of improved hydrogen evolution performance is revealed by electronic structure and charge transfer. Our findings of the highly activating defective systems provide a theoretical basis for HER applications of platinum and palladium dichalcogenides. 相似文献
56.
将幸福河概念与长江三角洲区域一体化发展战略相结合,基于自然、人类社会、人水关系3个系统构建了包含24个指标的长三角幸福河层次评价指标体系;引入需求层次理论,以基础Ⅰ层次、基础Ⅱ层次、提升Ⅰ层次、提升Ⅱ层次、幸福层次5个层次作为幸福河的层次评价等级,运用熵权物元模型,建立了长三角幸福河层次评价模型,并对2018年长三角三省一市幸福河层次等级进行了评价。结果表明,三省一市均处于转化中的中间状态,其中江苏省向提升Ⅰ层次转化,浙江省、安徽省向提升Ⅱ层次转化,上海市向幸福层次转化,说明区域整体幸福河层次处于较高水平,但稳定性较差。 相似文献
57.
Dispersion of nanocrystalline (94–350 nm) Ce0.9Gd0.1O2-δ in superfine (260–312 nm) Sm1.5Sr0.5NiO4+δ using modified precipitation technique is established using X-ray powder diffraction, scanning electron microscopy and transmission electron microscopy. Presence of Ce0.9Gd0.1O2-δ grains inhibits grain growth of Sm1.5Sr0.5NiO4+δ, which provides morphological stability (up to 1100 °C). Ce0.9Gd0.1O2-δ concentration dependent behaviours of ionic conductivity, surface exchange rate and electrode polarization resistance (Rp) of composites (determined using electrochemical impedance spectroscopy) are comprehended using percolation model. Three oxygen reduction reaction mechanisms are considered to understand electrochemical performance. Minimum Rp (0.81 Ω cm2 at 700 °C) for 70Sm1.5Sr0.5NiO4+δ:30Ce0.9Gd0.1O2-δ is correlated to percolation threshold (optimum (i) electrochemically active sites (ii) oxygen reduction reaction kinetics, (iii) O2- conductivity and (iv) charge transfer rate). Nano crystallite size of Ce0.9Gd0.1O2-δ is crucial for enhancement in electrochemical performance. Oxygen partial pressure dependent electrochemical impedance spectroscopy studies reveal dominance of coexisting non-charge transfer oxygen adsorption/desorption and bulk O2- diffusion. 相似文献
58.
自动化实体描述生成有助于进一步提升知识图谱的应用价值,而流畅度高是实体描述文本的重要质量指标之一。该文提出使用知识库上多跳的事实来进行实体描述生成,从而贴近人工编撰的实体描述的行文风格,提升实体描述的流畅度。该文使用编码器—解码器框架,提出了一个端到端的神经网络模型,可以编码多跳的事实,并在解码器中使用关注机制对多跳事实进行表示。该文的实验结果表明,与基线模型相比,引入多跳事实后模型的BLEU-2和ROUGE-L等自动化指标分别提升约8.9个百分点和7.3个百分点。 相似文献
59.
Visual data analysis can be envisioned as a collaboration of the user and the computational system with the aim of completing a given task. Pursuing an effective system‐user integration, in which the system actively helps the user to reach his/her analysis goal has been focus of visualization research for quite some time. However, this problem is still largely unsolved. As a result, users might be overwhelmed by powerful but complex visual analysis systems which also limits their ability to produce insightful results. In this context, guidance is a promising step towards enabling an effective mixed‐initiative collaboration to promote the visual analysis. However, the way how guidance should be put into practice is still to be unravelled. Thus, we conducted a comprehensive literature research and provide an overview of how guidance is tackled by different approaches in visual analysis systems. We distinguish between guidance that is provided by the system to support the user, and guidance that is provided by the user to support the system. By identifying open problems, we highlight promising research directions and point to missing factors that are needed to enable the envisioned human‐computer collaboration, and thus, promote a more effective visual data analysis. 相似文献
60.
对"文脉"一词进入中国建筑话语的历史作出概览式的回顾,并分别以"阙里宾舍"和"西单商业大楼"为例,从设计者的自述与建筑界的评论入手,探讨1980年代末到1990年代初"文脉热"兴起的可能原因。指出对"复古主义"的批判和创作有"民族特色"建筑的愿望是"文脉"一词背后潜在的诉求,同时,也警醒地看到,基于特定时代背景,中国建筑界对西方后现代主义等建筑思潮不可避免地片面理解和吸收,也造成了"文脉"逐渐丧失了其本应具有的批判性与创造力。 相似文献