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41.
黄运凤 《广州城市职业学院学报》2008,2(4):37-39
SO4^2-/TiO2固体超强酸薄膜化催化剂能完全代替浓硫酸作催化剂,用乙酸、乙醇来合成乙酸乙酯。在膜催化器上,考察了薄膜化催化剂对乙醇和乙酸合成乙酸乙酯的催化性能。结果表明,薄膜化催化剂显著提高了催化活性;当n(乙醇):n(乙酸)=1.5:1,原料流量3.0mL/h,在反应温度为110℃时,乙酸乙酯产率可达94.8%,且薄膜催化剂的处理很方便,催化剂再生后可重复使用,不污染环境。 相似文献
42.
银行间同业拆借利率的复杂性研究 总被引:2,自引:0,他引:2
本文运用复杂性理论对我国银行间同业拆借利率进行了实证研究.通过银行间同业拆借利率的关联积分关于相空间维数的数值计算发现,当相空间维数大于9以后,关联维数趋于平稳,从而确定银行间同业拆借利率的嵌入维数约为9,这时对应的关联维数约为3.64.通过对Kolmogorov熵的计算得出,我国7天银行间同业拆借利率的可预测时间尺度约为7天.本文将H.E.Hurst提出的R/S分析法应用于我国银行间同业拆借利率分析.测定了我国银行问同业拆借利率收益率的Hurst指数.运用消除趋势波动分析方法,计算了我国银行问同业拆借利率收益率的标度指数.结果表明:银行间同业拆借利率显示为状态反持续性. 相似文献
43.
在对4PL模式下供应链资源整合运作特征及整合中主导因素及其关系进行简要描述的基础上,围绕对整合决策具有重要影响作用的整合风险进行了分析;提出了引入整合风险的资源整合决策模式,建立了4PL模式下供应链资源整合决策的拓展多目标优化数学模型,搭建了改进的蚁群寻优算法实现该整合决策优化过程的求解。最后通过算例验证了优化过程及算法的有效性与可行性。整合决策优化模型及算法突出体现了4PL的运作优势,突出了从战略高度及系统性角度对供应链整合风险的把握,同时实现了资源整合优化多目标之间的权衡。 相似文献
44.
This study proposes a new and highly efficient dynamic combinatorial auction mechanism—the N-bilateral optimized combinatorial auction (N-BOCA). N-BOCA is a flexible iterative combinatorial auction model that offers more optimized trading for multiple suppliers and purchasers in the supply chain than one-sided combinatorial auction. We design the N-BOCA model from the perspectives of market architecture, trading rules, and decision strategy for winner determination, the decision strategy for winner determination needs flexible optimization modeling capability. Thus rule-based reasoning was applied for reflecting the flexible decision strategies. We also show the viability of N-BOCA through Paired Samples T-test experimentation. It shows that N-BOCA yields higher purchase efficiency and effectiveness than the one-auctioneer to multi-bidders (1-to-N) combinatorial auction mechanism. 相似文献
45.
《Risk analysis》2018,38(9):1962-1971
Given the recent increase in dust‐induced lung disease among U.S. coal miners and the respiratory hazards encountered across the U.S. mining industry, it is important to enhance an understanding of lung disease trends and the organizational contexts that precede these events. In addition to exploring overall trends reported to the Mine Safety and Health Administration (MSHA), the current study uses MSHA's enforcement database to examine whether or not compliance with health regulations resulted in fewer mine‐level counts of these diseases over time. The findings suggest that interstitial lung diseases were more prevalent in coal mines compared to other mining commodities, in Appalachian coal mines compared to the rest of the United States, and in underground compared to surface coal mines. Mines that followed a relevant subset of MSHA's health regulations were less likely to report a lung disease over time. The findings are discussed from a lung disease prevention strategy perspective. 相似文献
46.
James A Davis 《Social science research》1978,7(2):151-179
A review of recently developed simple techniques for analyzing data in the form of proportions from replicated, cross-sectional, sample surveys. (A) One variable over time—tests for homogeneity, pooling homogeneous proportions, tests for linear trends with as few as three time points, tests for departures from linearity; (B) Two variables with a constant percentage difference—four fold tables as rudimentary causal models, decomposing change with linear flow graphs; (C) Extension of the flow graph techniques to—three or more variables and changing coefficients; (D) Comments implying panel designs are somewhat over-rated and successive cross-sections somewhat under-rated. 相似文献
47.
Li Haiming 《Social Sciences in China》2016,37(1):152-163
Article 4 of the Labor Contract Law lays down the right of the Staff and Workers’ Representative Congress (SWRC) to deliberate on the formulation of (intra-enterprise) work regulations, but this has become a “soft” law in judicial practice. The judicial criteria for judging the validity of work regulations are in essence determined by the judge’s judgment on their reasonableness. As an important embodiment of Chinese politics, economics and culture, the transformation of the SWRC that accompanied the market economy has not negated its value as an indigenous traditional resource. The SWRC does not just enjoy deliberative rights in the formation of regulations, as clearly specified in constitutional law, but also has rights under the law in local legislation and practice. Hence the system of work regulations is neither a unilateral decision on the part of management nor a contract, but rather an autonomous norm developed through the SWRC mechanism. Given the mandatory nature of Article 4 of the Labor Contract Law, regulations will only be valid after they have gone through a democratic process. The further development of the theory of normative system formation should endow the SWRC with greater rights and integrate it smoothly with the collective contract system to standardize collective labor relations. 相似文献
48.
以学界广为关注的“S(是)AV(())的”句式为例,重点分析“(是)……的”类句式在语境、词汇和句法三个层面所显示的不同已然义特征,并以此为基础对国内外关于已然义“(是)……的”类句式的相关研究进行简要的评价。 相似文献
49.
Land subsidence risk assessment (LSRA) is a multi‐attribute decision analysis (MADA) problem and is often characterized by both quantitative and qualitative attributes with various types of uncertainty. Therefore, the problem needs to be modeled and analyzed using methods that can handle uncertainty. In this article, we propose an integrated assessment model based on the evidential reasoning (ER) algorithm and fuzzy set theory. The assessment model is structured as a hierarchical framework that regards land subsidence risk as a composite of two key factors: hazard and vulnerability. These factors can be described by a set of basic indicators defined by assessment grades with attributes for transforming both numerical data and subjective judgments into a belief structure. The factor‐level attributes of hazard and vulnerability are combined using the ER algorithm, which is based on the information from a belief structure calculated by the Dempster‐Shafer (D‐S) theory, and a distributed fuzzy belief structure calculated by fuzzy set theory. The results from the combined algorithms yield distributed assessment grade matrices. The application of the model to the Xixi‐Chengnan area, China, illustrates its usefulness and validity for LSRA. The model utilizes a combination of all types of evidence, including all assessment information—quantitative or qualitative, complete or incomplete, and precise or imprecise—to provide assessment grades that define risk assessment on the basis of hazard and vulnerability. The results will enable risk managers to apply different risk prevention measures and mitigation planning based on the calculated risk states. 相似文献
50.
David E. Bloom Mathew J. McKenna Klaus Prettner 《International social security review》2019,72(3):43-78
Globally, an estimated 734 million jobs will be required between 2010 and 2030 to accommodate recent and ongoing demographic shifts, account for plausible changes in labour force participation rates, and achieve target unemployment rates of at or below 4 per cent for adults and at or below 8 per cent for youth. The facts that most new jobs will be required in countries where “decent” jobs are less prevalent and workers in many occupations are increasingly subject to risks of automation further compound the challenge of job creation, which is already quite sizable in historical perspective. Failure to create the jobs that are needed through 2030 would put currently operative social security systems under pressure and undermine efforts to guarantee the national social protection floors enshrined in the Sustainable Development Goals (SDGs). 相似文献