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101.
车用汽油驱动性指数(DI)综合考虑了汽油各个馏分的分布,能较好地表征汽车冷起动性能和暖机性能。对DI的提出、研究进展及用途进行了阐述,并对我国车用汽油样品DI分布情况进行了初步分析研究。考察了不同季节、不同区域DI的分布情况,并考察了车用汽油质量升级对DI的影响。结果表明:我国汽油DI值范围分布较宽,不同地区的DI值差别很大;被考察地区不同季节DI值差别明显,冬季汽油DI值整体偏低;同一季节有些地区汽油DI值差别不大,但有的地区汽油DI值跨度很大。被考察的两个地区近几年随着油品的升级DI数值变化不大。有些地区的部分样品DI值较高应给予关注。 相似文献
102.
电子鼻在小麦品质控制中的应用研究 总被引:4,自引:0,他引:4
采用PEN3型电子鼻系统对我国10个省份47个小麦样品的挥发性物质进行检测。通过Loadings分析不同传感器在模式识别中的贡献率,对传感器阵列进行优化,并对传感器的响应值进行了主成分分析(PCA)和线性判别分析(LDA)。结果表明W5S、W1S、W2S3根传感器在小麦样品的用途、产地、品种区分识别时作用都较大,W1C、W3C2根传感器贡献率较小。PCA分析可以区分面包用小麦和馒头面条用小麦,总贡献率达85.5%;也可以区分不同产地的小麦样品和同一产地不同品种的小麦样品。线性判别分析(LDA)仅可以对不同产地、不同品种的小麦样品实现部分区分,无法将不同用途的小麦区分开来。主成分分析效果优于线性判别分析。 相似文献
103.
104.
This paper examines the localized effect of clusters of universities by exploiting a university town (UT) construction boom in China. We show that UT establishment has generated positive impact on local night-time light density and population concentration. The UT effect is much localized, and completely decays within 10 km. We emphasize the role of knowledge spillover and find that UT establishment has increased local human capital level. The number of high skill labors as well as high-tech firms has experienced higher growth in UT districts, as they benefited more from knowledge spillovers. Finally, we find that land prices in the UT have appreciated by 7%-12% using a unique dataset of land parcel transactions. 相似文献
105.
阳极焙烧炉的燃料消耗是阳极焙烧的一项重要指标,焙烧炉的燃料消耗取决于多种因素,合理的燃烧工艺管理操作方法是减少燃料消耗的一个重要环节.本文从阳极焙烧炉热平衡分析入手,通过分析找出影响燃料消耗的影响因素与燃烧消耗之间的关系并根据工作实践提出阳极焙烧工艺管理节能优化的措施. 相似文献
106.
As all couples experience stressful life events, addressing how couples adapt to stress is imperative for understanding marital development. Drawing from theories of stress inoculation, which suggest that the successful adaptation to moderately stressful events may help individuals develop a resilience to future stress, the current studies examined whether experiences with manageable stressors early in the marriage may serve to make the relationship more resilient to future stress. In Study 1, 61 newlywed couples provided data regarding their stressful life events, relationship resources (i.e., observed problem-solving behaviors), and marital satisfaction at multiple points over 2? years. Results revealed that among spouses displaying more effective problem-solving behaviors, those who experienced moderate stress during the early months of marriage exhibited fewer future stress spillover effects and reported greater increases in felt efficacy than did spouses who had less experience with early stress. Study 2 examined stress resilience following the transition to parenthood in a new sample of 50 newlywed couples. Again, spouses who experienced moderate stress during the early months of marriage and had good initial relationship resources (i.e., observed support behaviors) reported greater marital adjustment following the transition to parenthood than did spouses who had good initial resources but less prior experience coping with stress. Together, results indicate that entering marriage with better relationship resources may not be sufficient to shield marital satisfaction from the detrimental effects of stress; rather, couples may also need practice in using those resources to navigate manageable stressful events. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
107.
邓醉茶 《纺织高校基础科学学报》2004,17(4):321-325
确定原生资产的隐含波动率无论是在理论还是实际应用上都有重要意义,本文利用Green函数法将此问题化为一个“终端”控制问题,通过最佳控制解法讨论了控制泛函极小元的存在性定理,并给出了极小元所满足的必要条件。 相似文献
108.
Vapor-liquid equilibrium (VLE) data were measured for ternary system water + ethanol + 1-butyl-3- methylimidazolium acetate ([bmim][OAc]), in a relatively wide range of ionic liquid (IL) mass fractions up to 0.8. Six sets of complete T-x-y data were obtained, in which the mole fraction of ethanol on IL-free basis was fixed separately at 0.1, 0.2, 0.4, 0.6, 0.8, and approximate 0.98. The non-random-two-liquid (NRTL) and electrolyte non-random-two-liquid (eNRTL) equations were used for correlation, showing similar deviations. The ternary VLE was also modeled with the correlation from two data sets, with the mole fractions of ethanol on IL-free basis being 0.1 and approximate 0.98. The VLE data were also reproduced satisfactorily. With the eNRTL model, the root-mean-square deviation for temperature is 0.79 K and that for vapor-phase mole fraction is 0.0094. The calculations are in good agreement with experimental data. The effect of the IL on the VLE behavior of the volatile components is also illustrated. 相似文献
109.
Hydrogen Storage on Carbon-Based Adsorbents and Storage at Ambient Temperature by Hydrogen Spillover
Lifeng Wang 《Catalysis Reviews》2013,55(4):411-461
Hydrogen storage is a crucially missing link to a future “hydrogen economy.” Extensive hydrogen storage studies have been focused on carbon-based adsorbents due to their light weight, high surface area, and tailorable structure. An overview/analysis of the progress on hydrogen storage on various carbon-based adsorbents is given in this review. Particularly, a recent, fast-developing research direction—hydrogen storage via spillover on carbons via added catalysts — is reviewed separately. A fundamental understanding of the factors that affect both H2 and spillover hydrogen storage capacities, as well as strategies for improving the storage performance from the viewpoints of both hydrogen storage and materials chemistry, are discussed. 相似文献
110.
The long lead time required to add new capacity in the electricity generation industry means that daily demands are necessarily served by capacity already installed. However, in a competitive market, even if the installed capacity was designed to serve the projected demands, frequent surpluses and occasional full utilization inevitably lead to price volatility. This paper develops a two-stage model of the generation market in which capacity construction occurs in stage 1, before demand realization, and price determination occurs in stage 2, when the equilibrium price ensures that the realized demand does not exceed the installed capacity. We show that price volatility and price spikes are inevitable, and that while price capping can mitigate high and volatile prices, it causes unmet demands and reduction in system reliability. This paper accentuates the interdependence among generating capacity, price volatility and service reliability, a primary cause of concern in the debate on electricity market reform. 相似文献