严寒地区高速铁路混凝土基床聚氨酯保温特性试验研究

基于严寒区京沈客专朝阳试验段路基基床的温度监测资料分析,研究不同厚度聚氨酯保温板对高速铁路路基混凝土基床温度变化特性影响.测试结果表明:①铺设聚氨酯保温板能够有效阻断严寒区环境与路基基床间的热量传递,保温效果与板厚相关;②地温大多数时间呈阳高阴低现象,同时阴、阳坡路基温差波动幅度随埋深逐渐减小;③基床表层阴、阳面各测点的温度变化起始时间一致,而阴面的冻结时间比阳面晚一个月.由此表明,保温板能够有效降低环境与混凝土道床之间的热交换,但是对路基阴、阳坡的影响存在差异.建议在严寒地区高速铁路路基阳、阴坡可以采取不同厚度的聚氨酯保温板,减小阴阳坡地温差异,保持季冻土路基温度变化稳定.     

油气企业供应商管理存在的问题与建议——以CS公司为例

伴随着供应链管理的应用与发展,越来越多的企业认识到必须充分利用内外资源保持自身的竞争实力。作为重要的外部资源,供应商管理关系到企业成本与收益的平衡,而要做好供应端的成本管理首先要做好供应商的选择和优化。针对CS公司的供应商管理现状及存在的问题,探索适应企业的可操作性强的对策,以期为我国大型油气企业的供应商管理实践提供一定的参考。     

Stock market volatility forecasting: Do we need high-frequency data?

The general consensus in the volatility forecasting literature is that high-frequency volatility models outperform low-frequency volatility models. However, such a conclusion is reached when low-frequency volatility models are estimated from daily returns. Instead, we study this question considering daily, low-frequency volatility estimators based on open, high, low, and close daily prices. Our data sample consists of 18 stock market indices. We find that high-frequency volatility models tend to outperform low-frequency volatility models only for short-term forecasts. As the forecast horizon increases (up to one month), the difference in forecast accuracy becomes statistically indistinguishable for most market indices. To evaluate the practical implications of our results, we study a simple asset allocation problem. The results reveal that asset allocation based on high-frequency volatility model forecasts does not outperform asset allocation based on low-frequency volatility model forecasts.     

基于AD9361的掌上型LTE RRU设计与开发

当前小体积远端射频单元（Remote Radio Unit,RRU）主要是皮站级别的Pico-RRU，其重量和体积仍然难以满足掌上型的要求。为此，采用高集成度的AD9361芯片来实现长期演进（Long Term Evolution，LTE）宽带收发信机功能，配合时钟同步模块、放大器模块和控制接口电路等一起构建低成本的掌上型RRU。主要解决了基于AD9516的时钟同步、低相位噪声设计和高灵敏度接收机设计三个技术难点，成功实现了掌上型、高性能、低成本的设计目标。整个RRU样机尺寸为18 cm×10 cm×2 cm，质量约500 g，量产成本千元以内。测试表明，该RRU下行误差向量幅度（Error Vector Magnitude，EVM）小于3%，优于3GPP要求的8%；10 MHz带宽时上行接收机灵敏度优于3GPP要求的-93.5 dBm。     

浅论我国农产品流通企业扩张的基本规律与政策规制

通过对农产品流通企业扩张形式全面的理论梳理, 研究总结了二种类型的农产品流通企业扩张基本规律,即纵向扩张和横向扩张,并对中国农产品企业扩张问题进行了实证研究,最后对我国农产品流通企业扩张提出建议.     

Regulatory reform of the UK gas market: The sase of the storage auction

The UK gas industry has undergone major changes since it was privatised in 1986 as a fully integrated monopoly. The most significant of these has occurred not as a result of the privatisation legislation but by the intervention of the ordinary competition authorities in support of an active industry regulator. While price capping continues to be used as the primary instrument for welfare protection against the still substantial monopolistic powers of the incumbent, new competition (which has been positively encouraged) has had the greater impact on prices and choice. Recently, however, the regulator has encouraged the use of auctions for the sale of storage capacity. This paper considers the merits of auctions and makes a tentative evaluation of their effectiveness. Further use of auctions is recommended but reserve prices are considered inappropriate where monopoly power still remains.     

Application of multi-factor hierarchical fuzzy comprehensive evaluation model in risk assessment of gas exploration

This article classified gas exploration risk on the basis of the characteristics of oil-gas exploration investment projects, which are internal systems risk and external non-systemic risk. It described each classification specifically and introduced the basic principles and mathematical model of the multi-factor hierarchical fuzzy comprehensive judgment in detail, and then researched the conducts the risk of the gas exploration with examples.     

小氮肥清洁生产实践

文章介绍了沅江市氮肥厂废水闭路循环、尾气回收、废渣综合利用等工程,并介绍了该厂的生产工艺、污染源分布及排污特点。     

西气东输工程用感应加热弯管技术条件探讨

在对国外X70管线弯管技术条件进行调查分析与研究的基础上，对其中的几个关键技术问题包括母管成分，弯管的制造工艺和技术路线，强度与韧性要求，屈强比，Cu污染问题等进行了讨论。一些观点在西气东输感应加弯管技术条件中得到应用。     

The Financial and Operational Impacts of FERC Order 636 on the Interstate Natural Gas Pipeline Industry

The Federal Energy Regulatory Commission's Order 636 fundamentally altered the regulatory and operational environment of the natural gas industry in 1992, as the culmination of several directives aimed at relaxing regulation and fostering competition. We hypothesize that gas pipeline firms subsequently changed their operational and financial behavior in ways consistent with reduced balkanization, increased competition, and reduced expense preference behavior. Our results indicate that these firms have become more homogeneous financially but less so operationally. We find evidence that the marginal profitability of various pipeline activities has responded more to financial market conditions than to the regulatory environment.