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排序方式: 共有1884条查询结果,搜索用时 15 毫秒
61.
中国钢铁生产量及其能源需求和CO2排放量情景分析 总被引:8,自引:0,他引:8
从预测中国的钢铁需求量开始,利用情景分析,预测了钢铁业将来的能源需求和CO2排放量。预测结果表明,中国的钢产量还将继续增长,但应特别注意废钢回用,降低铁钢比,以减少能源需求和CO2排放。 相似文献
62.
要实现终身体育的教育目标 ,学校应加强学生的体育意识及能力培养。可以通过开展选项教学、有意识地培养学生体育需要和加强体育理论基本知识等教学活动 ,来不断增强学生的体育意识和能力。 相似文献
63.
Zden
k P. Ba
ant 《Probabilistic Engineering Mechanics》2004,19(4):541-319
The physical sources of randomness in quasibrittle fracture described by the cohesive crack model are discussed and theoretical arguments for the basic form of the probability distribution are presented. The probability distribution of the size effect on the nominal strength of structures made of heterogeneous quasibrittle materials is derived, under certain simplifying assumptions, from the nonlocal generalization of Weibull theory. Attention is limited to structures of positive geometry failing at the initiation of macroscopic crack growth from a zone of distributed cracking. It is shown that, for small structures, which do not dwarf the fracture process zone (FPZ), the mean size effect is deterministic, agreeing with the energetic size effect theory, which describes the size effect due to stress redistribution and the associated energy release caused by finite size of the FPZ formed before failure. Material randomness governs the statistical distribution of the nominal strength of structure and, for very large structure sizes, also the mean. The large-size and small-size asymptotic properties of size effect are determined, and the reasons for the existence of intermediate asymptotics are pointed out. Asymptotic matching is then used to obtain an approximate closed-form analytical expression for the probability distribution of failure load for any structure size. For large sizes, the probability distribution converges to the Weibull distribution for the weakest link model, and for small sizes, it converges to the Gaussian distribution justified by Daniels' fiber bundle model. Comparisons with experimental data on the size-dependence of the modulus of rupture of concrete and laminates are shown. Monte Carlo simulations with finite elements are the subject of ongoing studies by Pang at Northwestern University to be reported later. 相似文献
64.
Lee Dongwook; LoGalbo Anthony P.; Ba?os James H.; Novack Thomas A. 《Canadian Metallurgical Quarterly》2004,49(2):167
Objective: To evaluate the ability of the Cognitive Log (Cog-Log) to predict neuropsychological outcome at 1 year after traumatic brain injury (TBI). Study Design: The Orientation Log (O-Log) and Cog-Log were administered during morning rounds, and a battery of neuropsychological tests was administered at 1 year postinjury. Setting: Acute rehabilitation hospital. Participants: Fifty rehabilitation inpatients. Main Outcome Measures: Composite scores for processing speed, attention, language, memory, executive functioning, and visuospatial abilities. Results: The Cog-Log was found to significantly predict 1-year outcome in attention, executive functioning, and visuospatial abilities. The O-Log contributed significantly to memory outcome. The Disability Rating Scale was not a significant predictor. Conclusions: The Cog-Log has utility as a predictor of neuropsychological outcome, particularly when used with its companion instrument, the O-Log. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
65.
The decomposition of CHF3 in a mixture with O2 and Ar was investigated in a coaxial dielectric barrier discharge at atmospheric pressure. CHF3 decomposition increased linearly in regard to specific energy input (SEI), whereas energy efficiency decreased. The main product was CO2, and its selectivity increased with high SEI and the presence of O2 in the feed, but an increase of O2 in the feed led to a decrease in decomposition rate. An increase in total flow rate led to an increase of the absolute amount of CHF3 decomposition and energy efficiency; however, the decomposition of CHF3 decreased. A complete CHF3 decomposition occurred under an SEI of 1.54 kJ/L with the selectivity of CO2 and CO as 89.87% and 7.00%, respectively. Optical emission spectroscopic analysis could explain the available reaction pathways for CHF3 decomposition in the CHF3/O2/Ar atmospheric plasma and show the possibility of F2 and HF formation. 相似文献
66.
M. Kowalska K. Fabisiak A. Wrzyszczyński A. Banaszak M. Szybowicz K. Paprocki W. Bała F. Bylicki 《Materials Science-Poland》2014,32(3):475-480
Diamond electrodes of different morphologies and qualities were manufactured by hot filament chemical deposition (HF CVD) techniques by changing the parameters of diamond growth process. The estimation of diamond quality and identification of different carbon phases was performed by Raman spectroscopy measurements. The effect of diamond quality and amorphous carbon phase content on the electrochemical response of an obtained diamond electrode in 0.5 M H2SO4 as supporting electrolyte was investigated by cyclic voltammetry with [Fe(CN)6]4?/3? as a redox probe. The kinetic parameters such as catalytic reaction rate constant k0 and electron transfer coefficient α were determined. The obtained results show that the analytical performance of undoped diamond electrodes can be implemented just by the change of diamond layers quality. 相似文献
67.
Laura Moya Leandro Domenech Andrea Cardoso Hugo O´Neill Vanesa Baño 《Holz als Roh- und Werkstoff》2017,75(6):1017-1019
A previous database with bending and density data of 261 structural size specimens of currently produced Uruguayan slash pine and loblolly pine timber was adjusted to meet testing and characterization requirements of European standards. Visual parameters and mechanical properties for each specimen were evaluated and their relationship was statistically analyzed. Results suggested that all specimens can be grouped in one visual grade with engineered properties similar to those of European C14 strength class. Modulus of elasticity and characteristic bending strength were the defining properties for class assignation. 相似文献
68.
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70.
Pankaj B. Pathare Nursin Baş John J. Fitzpatrick Kevin Cronin Edmond P. Byrne 《Food and Bioproducts Processing》2012,90(3):549-554
In the fluidised bed granulation process the effect of nozzle air pressure and binder spray rate on key aggregate quality attributes were studied. The experimental results show that a decrease in nozzle air pressure leads to larger mean granule size. The combination of lowest nozzle air pressure and lowest binder spray rate results in granules with the highest levels of hardness and crispness. The combination of low nozzle air pressure and low binder spray rate results in the least distribution span. Granola hardness was affected by nozzle air pressure. Nozzle air pressure and binder spray rate did not have significant effect on crispness. 相似文献