不良贷款约束下我国上市商业银行全要素生产率时序演变及其驱动因素研究——基于非期望产出的Malmquist-luenberger和Tobit模型

基于我国上市商业银行2007~2013年面板数据,构建包括不良贷款约束条件下我国上市商业银行投入产出指标体系,采用基于非期望产出的M-L生产率指数方法对我国上市商业银行全要素生产率跨期动态变化进行实证测度,并应用Tobit回归分析方法对影响我国上市商业银行全要素生产率的因素进行实证分析,实证结果显示:我国上市商业银行全要素生产率平均增长率为2.4%,上市城市商业银行全要素生产率高于股份制上市商业银行,而股份制商业银行高于国有商业银行,其主要来源与规模效率提升;此外,银行规模和存贷比对商业银行技术效率提升产生显著的正向驱动影响;而银行集中度对其产生显著的负向驱动影响;资产收益率和所有权结构对其影响不显著。     

基于省际面板数据的全要素生产率的计算:1995-2006

本文采集并处理了1995年到2006年间全国30余个各省、直辖市和自治区的产出、资本投入和劳动力投入的数据,经过单位根检验、协整分析和模型选择,利用面板回归模型,计算了各地区的TFP及其在不同时期的增长率。研究表明,1995年-2006年间东部省份的TFP水平要高于中西部地区,但TFP水平较高的省份的TFP增长率速度并不一定高,尤其是部分东部省份的TFP的增长率出现了下降,而部分西部地区的TFP的平均增长率发展势头较好。     

陕西关中地区生态弹性计量模型与测算

关中地区是关中-天水经济区的主要部分,生态环境面临来自社会经济、自然环境等方面的压力,研究关中地区的生态弹性及其影响因素具有重要意义.通过GIS和RS技术,运用生态弹性度计算模型,测算了2000-2015年15 a间陕西省关中地区的生态弹性度,分析了市区间生态弹性度和生态弹性动态度的时空特征;探讨了土地利用变化和植被净初级生产力对生态弹性度的影响.研究结果表明：关中地区生态弹性度总体在4~8,从2000年的4.17~7.67升至2015年的5.94~7.52,总体呈上升趋势,生态环境有所改善.区域生态弹性受土地利用方式和NPP的影响,其中林地对区域生态弹性的提高影响最大,草地、耕地次之.通过植树造林增加建成区植被覆盖面积,有益于改善区域生态环境,提高区域生态弹性度.     

水平井体积压裂缝网表征及流动耦合模型

针对岩石脆性系数高且发育天然裂缝的储层,提出表征水平井体积压裂形成裂缝网络的三种基本模式,并将渗流过程划分为油藏流动和缝网内部流动.在此基础上,利用势叠加原理导出油藏流动控制方程,利用有限差分方法建立缝网内部有限导流等式;其次,采用星三角变换法处理人工缝与天然缝的交汇流动;最后,耦合两部分流动矩阵方程得到水平井体积压裂缝网渗流数学模型.该模型表明:当水平井改造段长度一定时,压裂段数与段内分簇数是决定产能的最主要因素,其次是人工裂缝半长和人工缝导流能力,而天然裂缝密度和导流能力对产量影响较小.实例应用表明,实际产油量与模型计算值一致,误差较小.     

Biomass Productivities in Wild Type and Pigment Mutant of <Emphasis Type="Italic">Cyclotella</Emphasis> sp. (Diatom)

Microalgae are expected to play a significant role in greenhouse gas mitigation because they can utilize CO₂ from power plant flue gases directly while producing a variety of renewable carbon-neutral biofuels. In order for such a microalgal climate change mitigation strategy to become economically feasible, it will be necessary to significantly improve biomass productivities. One approach to achieve this objective is to reduce, via mutagenesis, the number of light-harvesting pigments, which, according to theory, should significantly improve the light utilization efficiency, primarily by increasing the light intensity at which photosynthesis saturates (I _s). Employing chemical (ethylmethylsulfonate) and UV mutagenesis of a wild-type strain of the diatom Cyclotella, approximately 10,000 pigment mutants were generated, and two of the most promising ones (CM1 and CM1-1) were subjected to further testing in both laboratory cultures and outdoor ponds. Measurements of photosynthetic oxygen production rates as a function of light intensity (i.e., P–I curves) of samples taken from laboratory batch cultures during the exponential and linear growth phase indicated that the light intensity at which photosynthesis saturates (I _s) was two to three times greater in the pigment mutant CM1-1 than in the wild type, i.e., 355–443 versus 116–169 μmol/m² s, respectively. While theory, i.e., the Bush equation, predicts that such a significant gain in I _s should increase light utilization efficiencies and thus biomass productivities, particularly at high light intensities, no improvements in biomass productivities were observed in either semi-continuous laboratory cultures or outdoor ponds. In fact, the maximum biomass productivity in semi-continuous laboratory culture was always greater in the wild type than in the mutant, namely 883 versus 725 mg/L day, respectively, at low light intensity (200 μmol/m² s) and 1,229 versus 1,043 mg/L day, respectively, at high light intensity (1,000 μmol/m² s). Similarly, the biomass productivities measured in outdoor ponds were significantly lower for the mutant than for the wild type. Given that these mutants have not been completely characterized in these initial studies, the exact reasons for their poor performance are not known. Most likely, it is possible that the mutation procedure affected other photosynthetic or metabolic processes. This hypothesis was partially validated by the observation that the pigment mutant had a longer lag period following inoculation, a lower maximum specific growth rate, and poorer stability than the wild type.     

环境约束下中国地区物流业全要素生产率重估及收敛性研究

利用基于方向距离函数的Malmquist-Luenberger(ML)生产率指数方法对环境约束下中国1997-2009年30个省级地区物流业全要素生产率增长及其成分进行了重新估算,并通过技术创新者研究,分析了推动生产可能性边界外移的地区.研究发现:忽视非期望产出的传统Malmquist指数方法会低估物流业技术效率水平、高估物流业技术进步指数和全要素生产率指数.环境约束下我国物流业ML生产率指数年均增长率呈现下降趋势,下降的原因一方面是由于技术效率偏低阻碍了生产率的增长,另一方面是我国物流业技术进步的动力不足所致,物流环境技术创新主要集中于东部和西部地区个别省份,中部地区技术创新水平较低.收敛性检验表明,研究样本期内,全国以及三大地区物流业全要素生产率均存在显著的收敛趋势.     

制造业集聚对劳动生产率影响的区域差异和产业差异

我国制造业由90年代开始急速向东部地区集聚,但近几年这种集聚态势有所减弱,甚至有一些东部地区行业向其他地区进行了转移,产业集聚存在区域差异导致这种现象的根本原因.并针对产业的行业差异给出产业转移建议.利用我国2007-2009年29个省、市、自治区(不包括青海和西藏)四位码制造业数据探索产业外部性对劳动生产率的影响及这种影响的区域差异和产业差异,有如下发现:首先,"地方化经济"的可分解为"就业密度"和"竞争程度".计量结果表明:1)地区差异:就全国样本来说,就业密度对劳动生产率有正向影响,但对东部地区的影响由2007年的显著正向影响转变为2009年的影响不显著.竞争程度对劳动生产率有正向影响,但2007-2009年三年间,其对东部地区的影响均小于对内陆地区的影响.表明东部地区已经逐步丧失考劳动力集聚所得到的优势,且竞争的负面影响有所显现,2)行业差异:竞争程度对劳动生产率的影响因行业而不同,劳动密集型行业受到竞争程度的正向影响更大,而资本密集型行业受到竞争程度的正向影响较小,即同行业的集聚对劳动密集型行业有利,而对资本密集型行业影响较小,这也是创新点之一.最后,对计量结果进行了现实性分析并提出政策建议,建议劳动密集型行业由东部向中部转移,因为东部已失去了单纯靠劳动力数目提高劳动生产率的优势,并且东部地区企业竞争的负面效应有所显现,同时中部地区也有能力做好承接工作,但是这还要建立在中部加速自身发展和建设的基础之上.     

居民消费的习惯形成与实际经济周期模型的求解分析——一个基于三部门RBC模型的研究

结合H-P滤波法和King,Plosser&.Robelo(1987)的研究,探讨了一个求解引入居民消费的习惯形成和存在稳态趋势增长的RBC模型的对数线性化方法,并利用该方法求解引入习惯形成和政府支出冲击的三部门RBC模型来分析中国1979-2009年间宏观经济波动.研究表明:这个方法求解本文模型的预测结果与中国的特征事实较一致;与NHG方法求解的预测结果相比较,二者存在明显的差异;对中国经济的解释力要强于NHG方法求解的预测结果.     

Comparative ethanol productivities of different Zymomonas recombinants fermenting oat hull hydrolysate

Iogen Corporation of Ottawa, Canada, has recently built a 50 t/d biomass-to-ethanol demonstration plant adjacent to its enzyme production facility. Iogen has partnered with the University of Toronto to test the C6/C5 cofermentation performance characteristics of National Renewable Energy Laboratory's metabolically engineered Zymomonas mobilis using its biomass hydrolysates. In this study, the biomass feedstock was an agricultural waste, namely oat hulls, which was hydrolyzed in a proprietary two-stage process involving pretreatment with dilute sulfuric acid at 200–250°C, followed by cellulase hydrolysis. The oat hull hydrolysate (OHH) contained glucose, xylose, and arabinose in a mass ratio of about 8:3:0.5. Fermentation media, prepared from diluted hydrolysate, were nutritionally amended with 2.5 mL/L of corn steep liquor (50% solids) and 1.2 g/L of diammonium phosphate. The estimated cost for large-scale ethanol production using this minimal level of nutrient supplementation was 4.4c/gal of ethanol. This work examined the growth and fermentation performance of xyloseutilizing, tetracycline-resistant, plasmid-bearing, patented, recombinant Z. mobilis cultures: CP4:pZB5, ZM4:pZB5, 39676:pZB4L, and a hardwood prehydrolysate-adapted variant of 39676:pZB4L (designated asthe “adapted” strain). In pH-stat batch fermentations with unconditioned OHH containing 6% (w/v) glucose, 3% xylose, and 0.75% acetic acid, rec Zm ZM4:pZB5 gave the best performance with a fermentation time of 30h, followed by CP4:pZB5 at 48h, with corresponding volumetric productivities of 1.4 and 0.89 g/(L·h), respectively. Based on the available glucose and xylose, the process ethanol yield for both strains was 0.47 g/g (92% conversion efficiency). At 48 h, the process yield for rec Zm 39676:pZB4L and the adapted strain was 0.32 and 0.34 g/g, respectively. None of the test strains was able to fermentarabinose. Acetic acid tolerance appeared to be a major determining factor in cofermentation performance.     

A New Analytical Approximation for the Flow into a Well in a Finite Reservoir

A new approach is presented for the pressure calculation around a horizontal well or a partially penetrating vertical well in a finite height reservoir. The new method matches the asymptotic solutions close to- and far from the well. To this end, the reservoir is divided into two distinct volumes with ellipsoidal and elliptically cylindrical symmetry, respectively. Comparison with other techniques shows that the new expressions yield excellent results. The method is also applicable to reservoirs containing one elliptical, vertical or horizontal fracture, and can be used with account of a zone of altered permeability around the well or fracture due to formation damage or stimulation.