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.     

Research notes and communications corporate restructuring and strategic change: The effect on diversification strategy and R & D intensity

In the 1980s a number of large corporations restructured their diversified businesses through divestitures. It is hypothesized that restructuring activity focused on firms at intermediate levels of diversification (e.g., related-linked) which have a mixture of related and unrelated business units. Results confirm this hypothesis which explains that such mixed corporate strategies create organizational and control inefficiencies in managing both related and unrelated types of business units. Restructured firms were also found to move towards two types of different internal capital markets (related and unrelated). Most restructuring firms moved toward lower levels of diversification (e.g., related-constrained), although some moved toward higher levels of diversification (e.g., unrelated business). Also, this study finds restructuring firms that changed their corporate strategy by reducing diversified scope increased their R&D intensity. Firms that restructured and increased their diversified scope decreased R&D intensity. This result suggested a partial substitution between diversification and R&D activity.     

全低变工艺开发应用中的问题与对策

讨论了全低变工艺开发过程中遇到的一些问题和对策,对中、小氮肥企业进行技术改造具有一定的参考意义。     

康佳T2988彩电电源保护电路工作原理分析

为提高彩电的安全性能,保护电路在大屏幕彩电中得到广泛应用。本文分析了康佳 T2988型画中画大屏幕彩电电源保护电路的保护模式和工作原理。     

激励性规制的强度分析

网络型产业中存在的信息不对称使规制契约的存在成为必然。现实经济活动中之所以要设计和采用不同强度的激励性规制,主要是由于没有哪种规制机制能够解决所有问题。在理论综述的基础上,借鉴前人的研究,分析了网络型产业的激励性规制模型中的激励强度与激励绩效的关系,并指出其在实践中的应用以及对我国的借鉴。     

城市低收入保障制度与反贫困的公共政策

城市低收入保障制度实施中“应保未保”的现象较为普遍，低收入保障所需资金的缺口较大，缺乏全国统一的贫困标准使得其随意性很大。解决这一社会问题必须从近期和远期两个目标入手，近期目标是尽快遏制城市贫困人口剧增的势头，防止在深化改革的过程中出现快速增长的新生贫困人口；远期目标是立足最终消除城市贫困现象。     

开放条件下的贵州工业结构升级

工业化过程不仅涵盖了工业产值不断提高并最终在国民经济中占主导地位,还应该实现工业结构的不断升级.1997年至2004年期间,贵州工业结构在轻重工业比例、结构高度化和生产要素密集度等方面有所升级但仍存在一些偏差.在未来开放条件下贵州促进工业结构升级应注意避免结构低度化,创造和提供合适的市场空间,正确处理技术引进与自主开发的关系,发挥比较优势以及规范政府职能等问题.     

简述PHC管桩的发展态势

通过对桩基常用施工方法的比较，阐述了预应力高强度混凝土管桩的优点和静压法沉桩施工工艺的先进性。特别对人们关注的可靠性和经济性等问题作了较全面的分析，认为在诸多型式的桩基中预应力高强度混凝土管桩将独占鳌头。