丙烷脱氢制丙烯技术进展

丙烯是一种很有应用潜力的无色可燃气态烃。本文综述了丙烷脱氢制丙烯的国内外发展状况,对丙烷脱氢热力学进行了分析:因为该反应为一可逆、增分子、强吸热反应,所以必须采用选择性良好的催化剂,才有利于丙烷选择性的提高;对无机膜反应器中的丙烷脱氢及以氧气和二氧化碳作氧化剂的丙烷氧化脱氢几种丙烯制备方法进行了总结。     

模块式小型反应堆研发现状及前景分析

目前的核电站大多数为装机容量较大的反应堆,有些甚至达到了175万千瓦的单机容量,大型堆核电站一次性投入成本高、建造周期长,且难以适应小型电网的需求,而小型反应堆恰好可以解决这一问题,全球掀起了模块式小型核电机组的开发热潮。文章主要介绍了模块式小型反应堆的研发现状、用途,并分析了小型堆与常规堆的优劣势及其发展前景。     

我国出租车牌照拍卖机制研究

论文以有效分配、促进竞争、实现经济价值为目标，建立了公开升价拍卖+密封拍卖的两阶段牌照拍卖模型，证明了其有效性和最优性。并以北京市为例讨论了牌照数量的确定、进入密封拍卖阶段的时机和牌照的流通等实际问题。这些讨论将有利于拍卖机制在现实中的操作实施。     

Predictors of export performance in developing economies: a longitudinal analysis of Moroccan SMEs

Purpose: To help increase understanding of the export performance, we investigate the influence of firm size, research and development (R&D), advertising expenditures and network relationships, and develop a conceptual model to increase export intensity. Design/methodology/approach: The research involved a four-year longitudinal study of export performance of 168 exporting SMEs in Morocco (672 observations). The two-stage least square estimation (G2SLS) was used to test the hypotheses. Findings: The findings of the two-stage least square estimation (G2SLS) suggest that export sales and domestic sales are interdependent and influence each other. R&D expenditures and network affiliation have positive and significant impact on export sales, while advertising expenditure has a negative and significant influence on export sales. Research limitations/implications: Readers should use caution in generalizing the findings unless verified in other developing contexts. Practical implications: The findings of this study are useful for managers and export policy makers in developing countries. A proper understanding of the predictors of export performance may help them encourage the growth and diversification of exports that is so vital for developing countries. Originality/value: Export performance is a key element in the field of international marketing. Unfortunately, the literature exhibits a lack of empirical studies in developing countries, particularly in Maghreb regions. The empirical testing of the theoretical model in a developing economy is a significant contribution to fill the needed gap in the literature toward generalizing findings.     

谐波对电容的影响及防范措施

简要介绍了电力系统中谐波对电容器造成的影响及原因,以及理论上的解决方法,并结合实际提出了解决谐波影响的实施措施。     

UASB反应器设计及启动实验

UASB反应器是当前发展最快的一种废水处理工艺。本文重点介绍了UASB反应器的设计原则和设计方法,以及UASB反应器各部分尺寸的计算和确定原则,并对反应器进行了常温启动实验。实验结果表明:用葡萄糖配水模拟生活污水,进水COD控制在500mg/L,反应器运行一个月,进水COD去除率达到71.2%。进水的pH控制在7.5-8.0可以保证反应器的正常稳定运行。     

智能型生化反应器控制仪

针对生化反应器在不同生产工艺反应过程中的共同特点,提出以单片机为核心,采用微电子、扩大量程自诊断法、相关自诊断方法、自校正及抗干扰技术,由时间最优、预估、PID、Bang-Bang基本控制规律组成的复合控制算法,并根据偏差和偏差变化率自动切换执行不同的算法。     

Agriculture–nutrition linkages with heterogeneous,unobserved returns and costs: Insights from Tajikistan

Agriculture–nutrition linkages (ANLs) have been increasingly investigated in the literature. However, nutritional returns and costs of household agricultural production practices (APPs) in semisubsistence settings are poorly understood. We fill these knowledge gaps using pooled cross-section data sets in Tajikistan, where semisubsistence farming and undernutrition coexist despite relatively good agricultural infrastructure and education systems. Agricultural diversification, yield enhancement, production expansion are positively associated with various nutritional outcomes, particularly in areas with poor food market access. Decomposition exercises suggest that nutritional returns and costs of these APPs vary across households, and the adoption of APPs is driven by the expected nutritional returns. In Tajikistan, improving nutrition through household ANLs requires growing the smallholder agricultural sector in multiple dimensions, including diversification, intensification, and expansion, while also understanding better the pathways of ANLs and addressing bottlenecks at appropriate stages of such pathways.     

气固流化床制备氯化聚乙烯的研究

对流化床反应器中聚乙烯氯化反应进行了实验研究。探讨了反应操作条件对产品氯化聚乙烯中氯含量的影响。结果表明,反应起始温度、操作气速、原料气中2种气体的流量比、反应时间以及引发方式等条件都会对最终产品的氯含量产生不同程度的影响,产品氯化聚乙烯中的氯含量可以通过改变反应时间等条件在一定范围内进行调节。用气固流化床制备氯化聚乙烯,避免了悬浮法和溶液法中存在的对设备腐蚀严重、溶剂回收难等一系列问题。     

Induced Innovation in U.S. Agriculture: Time-series, Direct Econometric, and Nonparametric Tests

The hypothesis of induced innovation is tested for U.S. agriculture using a high-quality state-level panel data set and three disparate testing techniques—time series, direct econometric, and nonparametric. We find little support for the hypothesis. That conclusion is robust across testing techniques. However, as with all empirical tests of this hypothesis conducted to date, ours focus only on the demand side of the hypothesis. The hypothesis could have been rejected simply because the marginal cost of developing and implementing input-saving technologies for the relatively expensive inputs is greater than for the relatively cheap inputs.