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921.
碳酸盐岩储层岩性组成复杂,仅仅依靠少量的岩心、岩屑和几条常规的测井曲线资料很难准确地展现储层岩性的纵向及横向分布特征,从而影响对储层空间分布的预测。本文以上余家坝石炭系石炭系地层的岩心、岩屑录井资料为分析样本,结合对应的常规测井资料并对其进行数学处理,处理后共有12个参数供逐步判别函数筛选,经过多次的引入与剔除,建立了各类岩石的判别函数。其中灰岩、灰质云岩、云岩选择了9个参数;云质灰岩选择了10个参数。将岩性判别结果与取心井段的岩性对照,每类岩性的判别符合率都在85.39%以上,综合符合率为91.49%。说明本方法对目的层段碳酸盐岩储层岩性的识别是可行的。 相似文献
922.
We demonstrate how it is possible to generate value for an investor with a hedge attached to the buy-and-hold strategy of an S&P 500 index fund. We study the S&P 500 index portfolio (not including dividends) and the value-weighted S&P 500 index portfolio (including dividends) of the Center for Research in Securities Prices for 1967:01–2011:12, using the capacity utilization and the unemployment rates in real time to determine if a hedge position should be initiated or closed. A hedge is initiated if the capacity utilization, the unemployment rate or a combination of the two signals a contraction in the real economy. The hedge position is closed if it signals otherwise an expansion. We use utility gains (Campbell and Thompson 2008), the manipulation-proof performance measure (MPPM) statistics (Ingersoll et al. 2007) and the P-Sharpe ratio (Bailey and López de Prado 2012) to evaluate the performance of a particular hedge strategy. The empirical results show that there are infinitely many hedges that can generate positive utility gains, higher MPPM statistics and higher P-Sharpe ratios. 相似文献
923.
在对颠覆性创新理论再认识的基础上,对现有研究的不足之处进行了评论,并从价值创造角度构建了一个用于颠覆性创新的分析框架,在此框架基础上,进而对物流业颠覆性创新进行了系统分析。 相似文献
924.
The main aim of this paper is to investigate the transformations of the Romanian agricultural paradigm under the domestic economic policy reforms. An econometric approach is adopted by analyzing the evolution of Romanian agriculture between 1960 and 2011 from the perspective of its implications on residential land economy. This methodological choice relies on its high degree of applicability and its ability to reveal the massive transformation of the Romanian agricultural paradigm during the period under focus. Two regression models have been developed in the attempt to analyze the evolution of total value added and labor productivity in agriculture. The results obtained during the research confirm that Romanian agriculture exhibits determinant and significant elements able to trigger a massive change of paradigm. 相似文献
925.
Despite the widespread belief that Japan’s “Great Stagnation” in the 1990s is due to the financial dysfunction after the collapse of asset price bubbles, Hayashi and Prescott (2002) argue that its main cause is a slowdown in total factor productivity growth, using a calibrated neoclassical growth model. The present paper aims to fill this gap by estimating a New Keynesian dynamic stochastic general equilibrium model augmented with a financial accelerator mechanism and associated financial shocks. Our estimation results show that even in the presence of the financial shocks an adverse neutral technology shock mainly induced the Great Stagnation and that the rate of neutral technological change is strongly correlated with all enterprises’ financial position in the Tankan. Based on these findings, the paper argues that the Great Stagnation was caused by an adverse neutral technology shock that is likely to represent a tightening of firms’ financing, which induced reduction of R&D investment and misallocation of resources as indicated in previous literature. 相似文献
926.
《Food Policy》2017
We report on the prevalence and patterns of non-farm enterprises in six sub-Saharan African countries, and study their performance in terms of labor productivity, survival and exit, using the World Bank’s Living Standards Measurement Study - Integrated Surveys on Agriculture (LSMS-ISA). Rural households operate enterprises due to both push and pull factors and tend to do so predominantly in easy-to-enter activities, such as sales and trade, rather than in activities that require higher starting costs, such as transport services, or educational investment, such as professional services. Labor productivity differs widely: rural and female-headed enterprises, those located further away from population centers, and businesses that operate intermittently have lower levels of labor productivity compared to urban and male-owned enterprises, or enterprises that operate throughout the year. Finally, rural enterprises exit the market primarily due to a lack of profitability or finance, and due to idiosyncratic shocks. 相似文献
927.
目前,我国在医疗信息安全保障建设方面严重滞后,信息安全工作的战略统筹和综合协调不够,缺乏体系化的安全策略研究以及针对数字化医疗业务特点的管理机制研究。为了实现安全可信的医疗信息发展环境,笔者针对现有医疗信息系统中各个需要实施安全保护的目标,给出了在推动医疗信息安全保障体系建设方面应涉及的各项安全问题及管理机制,旨在构建一个全面涵盖了信息技术、组织策略、法律意识的整体性治理方案。 相似文献
928.
伴随着互联网络的发展以及经济全球化的进程,电子商务近年来发展极为迅猛,在为人类社会带来深刻变革的同时,也对各国税收制度带来极大挑战。本文探讨了电子商务的各种特征,分析了电子商务对税收的影响因素,并结合国外知名公司的真实案例,研究了国外针对电子商务的各种税收政策。希望对我国制定符合国情的电子商务税收制度方面提供参考和借鉴。 相似文献
929.
卢良艳 《中国保险管理干部学院学报》2014,(3):62-65
根据对湖南省农村信贷现状的调查,进而对湖南农村信贷在发展中存在的问题进行了分析,并提出了完善湖南省农村信贷的发展对策. 相似文献
930.
2013年12月30日财政部颁布了《高等学校会计制度》,并于2014年1月1日正式执行。本文立足实际工作,针对新高校会计制度中会计科目的设置及衔接中存在的问题进行分析,并提出建议,以保证新高校会计制度的顺利过渡实施。 相似文献