Empirical Analysis of the Demand of Rail Freight Transport in China on Basis of VAR Model     

WEN Shu-sheng  YE Huai-zhen 《保鲜与加工》2007,(10):152-158

With the rapid development of road and other transport modes in China, the railway freight transport is confronted with great challenge. So, the relations of rail freight transport, development of national economy and extension of railway become focuses. This paper makes a cointegreting VAR model according to the data from Chinese Statistical Year Book. On the basis of the model of the long-run and short-run equilibrium of rail freight demand are analyzed, The result shows that the rail freight transport in China has a stable and low elastic coefficient of income and a high but unstable elastic coefficient of supply in long-run. In short dynamics, the national economy is the first factor affecting rail freight demand and in the second term the innovation reaches a top point. Extension of railway has little effect on rail freight transport. The innovations from rail freight transport and railway extension has little impulse on national economy. Rail freight is the important factor affecting extension of rail-way with a third-term top, but GDP has a little impulse on it. Further analysis on the result and suggestion on policy are made.  相似文献   

Study on Genetic Fingerprinting Technique of Microbial Communities     

YE Jiang yu  LUO Gu yuan 《保鲜与加工》2003,(3):147-153

The 99% of all microorganisms in naturecannot be isolated by standard culture methods without conspicuous external characters to classify them morphologically. In addition, classification based on physiological or biochemical features are often fuzzy. Molecular techniques are used for uncultured microorganisms to explore the diversity of microbial communities and novel resources without the need of cultivation. DNA dynamics and cloning of PCR products obtained from environmental DNA is now routinely used to identify microbial populations in microbial ecology. For practical reasons the approach is not suited to study the complex dynamics of microbial communities in environment. Genetic fingerprinting techniques are better tools, which give complement for the traditional microbiological methods. The methods are rapid and relatively easy to perform, and they allow the simultaneous analysis of multiple samples, which makes it possible to compare the genetic diversity of microbial communities from different habitats, or to study the behaviour of individual communities over time.  相似文献   

有机-无机复混肥圆盘造粒试验研究   总被引：1，自引：0，他引：1  

孙学军  叶进  兰银在  牛敏杰 《中国农机化》2005,(2):51-53

对有机-无机复混肥圆盘造粒进行试验研究，分析了圆盘转速、圆盘倾角、喷头喷孔直径以及水分含量对颗粒成粒率和颗粒抗压强度的影响，确定了有机一无机复混肥圆盘造粒时较适宜的圆盘倾角、圆盘转速和水分含量。  相似文献   

拖拉机带辅助油缸的悬挂机构速度分析     

韦志康  张长坤  叶忠慧  罗子华 《中国农机化》2007,(4):79-82

运用解析法对带有辅助油缸装置的整体式拖拉机悬挂机构进行提升速度分析,推导主油缸与辅助油缸的同步速比的数学模型,从而应用计算机编程优化悬挂机构的结构参数和工作参数。  相似文献   

主动磁悬浮轴承集中控制器的研究     

叶建民 《湖南农机》2006,(5)

将传统PID理论和LQR理论相结合,提出了一种易于工程实现的交叉PID集中控制器,解决了磁悬浮轴承系统中集中控制器普遍存在的设计复杂、实时计算量大、过度依赖精确的数学模型等缺陷。针对实验室的磁悬浮轴承试验平台,采用Matlab仿真软件进行了交叉PID集中控制系统的仿真研究。仿真结果表明,交叉PID集中控制器具有较好的控制性能,可以实现电磁轴承转子的稳定悬浮。  相似文献   

柴油机燃用菜籽油的耐久性试验研究     

叶丽华  施爱平  张春丰 《农机化研究》2007,(11):205-207

柴油机燃用菜籽油植物油的短期耐久试验证明了植物油可作为一种代用燃料,但同时也暴露出了一系列的问题.试验后观察试验柴油机的主要零部件可看到:燃烧室的表面有大量的积碳、喷油器结焦、气门黏滞、缸套轻微刮伤等现象.这导致了柴油机性能的下降、油耗的升高和经济性的下降.其中,喷油器结焦和气门黏滞是性能下降的主要原因.  相似文献   

机动车排放净化技术研究   总被引：1，自引：0，他引：1  

陈松玲  路淼  储金宇  叶丽华 《中国农机化》2005,(1):53-55

机动车排放污染严重，本文简要介绍了净化机动车排放的方法．探讨了低温等离子体净化尾气的反应机理，阐述了两种低温等离子体发生器。  相似文献   

载体好氧预处理对厌氧消化反应器运行性能的影响     

叶芬霞 《中国沼气》2001,19(1):16-19

将用于厌氧消化反应器的载体经好氧挂膜预处理，采用有机负荷递增法启动厌氧附着膜膨胀床（AAFEB）反应器，好氧预处理后的反应器比对照提前15天完成启动，并且具有较好的耐冲击负荷能力和耐水力负荷能力。这与污泥结构良好，持留能力强，污泥流失量小呈正相关。在反应器的稳态运行和再启动运行期间，反应器的主要运行参数与对照反应器无明显差异。  相似文献   

FEM技术用于车门设计的研究   总被引：3，自引：0，他引：3  

叶德涛 《拖拉机与农用运输车》2006,33(4):18-19

介绍了解决有限元FEM(fin ite elem entm ethod)技术用于某小型运输车车门设计的关键问题的方法。对没有用加强板进行加强的车门进行了下沉工况静力分析和自由状态的模态分析,得到了车门的固有频率及其相应振型,对车门的静刚度和动刚度做出了评价,为进一步设计提供了参考。  相似文献   

红心中华猕猴桃新品种‘桂红’的选育     

莫权辉  叶开玉  龚弘娟  王发明  蒋桥生  刘平平  李洁维 《中国果树》2021,(2):76-78,I0002

‘桂红’是从野生中华猕猴桃后代中选育出来的猕猴桃新品种。平均单果重94.4 g。果实短圆柱形,果顶平或微凸;果皮黄绿色、薄,果毛残存、柔软,果斑黄褐色。果肉外缘金黄色,中轴白色,子房桃红色,呈放射状,肉质细,汁多,清甜,有香味,干物质含量17.39%,可溶性固形物含量16.70%,可溶性糖含量10.69%,可滴定酸含量1.56%,维生素C含量994.3mg/kg,含18种氨基酸,含包括硒在内的多种矿物质。在广西桂林地区,果实9月中下旬成熟。  相似文献