计轴自动站间闭塞及调度集中设备的行车组织对策建议

介绍了计轴自动站间闭塞和调度集中设备概况,针对这些技术设备在青藏铁路哈尔盖—格尔木间的应用,论述了相应的行车组织对策,并根据目前的有关规章要求,对计轴自动站间闭塞方式和调度集中作业提出了应进一步研究和探讨的问题。     

A theoretical framework to evaluate different margin‐setting methodologies

The margin system is the first line of defense against the default risk of a clearinghouse. From the perspectives of a clearinghouse, the utmost concern is to have a prudential system to control the default exposure. Once the level of prudentiality is set, the next concern will be the opportunity cost of the investors, because high opportunity cost discourages people from hedging futures, and thus defeats the function of a futures market. In this article, we first develop different measures of prudentiality and opportunity cost. We then formulate a statistical framework to evaluate different margin‐setting methodologies, all of which strike a balance between prudentiality and opportunity cost. Three margin‐setting methodologies, namely, (1) using simple moving averages; (2) using exponentially weighted moving averages; (3) using a GARCH approach, are applied to the Hang Seng Index futures. Keeping the same prudentiality level, it is shown that the one using a GARCH approach by and large gives the lowest average overcharge. © 2004 Wiley Periodicals, Inc. Jrl Fut Mark 24:117–145, 2004     

The index futures markets: Is screen trading more efficient?

This article uses a nonparametric test based on the arc‐sine law (see, e.g., Feller, 1965 ), which involves comparing the theoretical distribution implied by an intraday random walk with the empirical frequency distribution of the daily high/low times, in order to address the question of whether the abandonment of pit trading has been associated with greater market efficiency. If market inefficiencies result from flaws in the market microstructure of pit trading, they ought to have been eliminated by the introduction of screen trading. If, on the other hand, the inefficiencies are a reflection of investor psychology, they are likely to have survived, unaffected by the changeover. We focus here on four cases. Both the FTSE‐100 and CAC‐40 index futures contracts were originally traded by open outcry and have moved over to electronic trading in recent years, so that we are able to compare pricing behavior before and after the changeover. The equivalent contracts in Germany and Korea, on the other hand, have been traded electronically ever since their inception. Our results overwhelmingly reject the random‐walk hypothesis both for open‐outcry and electronic‐trading data sets, suggesting there has been no increase in efficiency as a result of the introduction of screen trading. One possible explanation consistent with our results would be that the index futures market is characterized by intraday overreaction. © 2004 Wiley Periodicals, Inc. Jrl Fut Mark 24:337–357, 2004     

An empirical analysis of the relationship between the hedge ratio and hedging horizon: A simultaneous estimation of the short‐ and long‐run hedge ratios

This article analyzes the effects of the length of hedging horizon on the optimal hedge ratio and hedging effectiveness using 9 different hedging horizons and 25 different commodities. We discuss the concept of short‐ and long‐run hedge ratios and propose a technique to simultaneously estimate them. The empirical results indicate that the short‐run hedge ratios are significantly less than 1 and increase with the length of hedging horizon. We also find that hedging effectiveness increases with the length of hedging horizon. However, the long‐run hedge ratio is found to be close to the naïve hedge ratio of unity. This implies that, if the hedging horizon is long, then the naïve hedge ratio is close to the optimum hedge ratio. © 2004 Wiley Periodicals, Inc. Jrl Fut Mark 24:359–386, 2004     

从“江阴板块”看苏南乡镇企业的新发展

苏南乡镇企业能否实现与现代市场经济的有效对接是社会各界广泛关注的重要课题。可喜的是，作为苏南乡镇企业的发源地之一，进入９０年代以来，江苏无锡地区的江阴市，一大批乡镇企业积极实施资本经营战略，从１９９７年至今的短短几年间，已有１０家公司上市，形成了中国股市     

‘Double marginalization’ problems: evidence from the Korean fixed-to-mobile service market

In this paper, examination of the possibility of a ‘double marginalization’ problem existing in the Korean telecommunication industry is conducted and suggestions are made for the provision of a new scheme to eliminate this possibility by changing the pricing system for fixed-to-mobile calls. Based on five key economic characteristics in the Korean mobile market, a simple model for double marginalization in the telecommunication market is introduced. Evidence was found to suggest that a double marginalization problem is likely to exist within Korea's telecommunication industry as it is presently structured, and that this problem is further likely to have an adverse effect on the industry by inflating the price of fixed-to-mobile calls. Two alternatives are proposed to effectively remedy this double marginalization issue. It is also shown that prices of fixed-to-mobile calls could be lowered by changing the caller pays principle into a receiver pays principle.     

The dynamics of positive action in UK trade unions: the case of women and black members

This paper considers positive action strategies amongst UK trade unions, aimed at increasing membership and levels of participation and representation among women and black workers. It provides an overview of women’s, black members’ and race structures within large Trades Union Congress unions and a detailed case study of one large UK trade union. We find that there are salient differences in the way that unions approach issues of gender equality, compared with the approach adopted towards race equality. The paper explores possible explanations, justifications and implications of these differences.     

物流热的冷思考

物流圈内好热闹自2000年以来,随着各种物流高峰会、研讨会、展览会的召开,“物流”和“网络”并驾齐驱,驰骋于各种媒体之上。如果说去年物流圈内热闹纷繁还只局限于理论炒作上,那么去年众多高科技企业和上市公司的强力介入,物流“热”似乎显得实在了一些。中国诚通集团在上海宣     

随机存货决策中的安全库存研究

在有短缺成本下 ,讨论了再定购点的确定 ,着重分析了安全库存的一种简易计算。     

General‐to‐Specific Model Selection Procedures for Structural Vector Autoregressions*

Structural vector autoregressive (SVAR) models have emerged as a dominant research strategy in empirical macroeconomics, but suffer from the large number of parameters employed and the resulting estimation uncertainty associated with their impulse responses. In this paper, we propose general‐to‐specific (Gets) model selection procedures to overcome these limitations. It is shown that single‐equation procedures are generally efficient for the reduction of recursive SVAR models. The small‐sample properties of the proposed reduction procedure (as implemented using PcGets) are evaluated in a realistic Monte Carlo experiment. The impulse responses generated by the selected SVAR are found to be more precise and accurate than those of the unrestricted VAR. The proposed reduction strategy is then applied to the US monetary system considered by Christiano, Eichenbaum and Evans (Review of Economics and Statistics, Vol. 78, pp. 16–34, 1996) . The results are consistent with the Monte Carlo and question the validity of the impulse responses generated by the full system.