石油企业加强库存控制的策略

库存管理是企业管理的重要组成部分。加强库存管理已成为企业转变经营方式、提高经营业绩的重要内容。为了更好地解决石油企业当前由于库存管理的观念相对落后、石油企业物资供应模式流转环节过多、部门之间缺乏必要交流、缺乏物资储备定额研究等问题,石油企业必须进一步加强石油企业库存控制,努力降低物流总成本,提高经营业绩、提高客户服务水平,制订石油企业库存控制策略,加强物质储备定额研究,实施全面库存管理,加大积压物资处理力度、努力降低当前库存,强化库存考核,强化物资计划管理,积极开展VMI（供应商管理库存）。     

Multiperiod forecasting in stock markets: a paradox solved

One of the most striking results on asset pricing in the last 20 years is the better forecastability of long-horizon returns over one-step return forecasts. This could seem a paradox, given that the further our forecast horizon the greater the uncertainty we are bound to face. This point can be found in Campbell and Shiller [Journal of Finance 43 (1988) 661; Journal of Finance 40 (1985) 793; American Economic Review 76 (1986) 1142] among others. In this paper, we offer an alternative explanation to this “forecast paradox ” that is in agreement with Kim et al. [Review of Economic Studies 30 (1992) 25], who found that the negative serial correlation in long-horizon returns depends very much on the sample choice. Our explanation is based on the existence of simultaneous shifts in the time series of the equilibrium stock price and dividends. This explanation relies on the concept of co-breaking [D.F. Hendry, A theory of co-breaking, Mimeo, Nuffield College, Oxford, 1995.]. We put forward a stochastic present value model, in which we are able to show how shifts in the process for dividends lead to shifts in the equilibrium stock price.This has important implications for multiperiod forecasting, as we demonstrate in this paper. An empirical application supports our results. In our empirical application, we model earning, dividends, stock prices, and the risk-free interest in the United States from 1926 to 1985. We can distinguish three different historical periods where the process for dividends and the equilibrium stock prices are characterized by different properties in terms of their means and variances. Our empirical model is extended to a forecasting exercise where the “forecast paradox” is solved.     

A computational implementation of stock charting: abrupt volume increase as signal for movement in New York Stock Exchange Composite Index

In this case study in knowledge engineering, data mining, and behavioral finance, we implement a variation of the bull flag stock charting heuristic using a template matching technique from pattern recognition to identify abrupt increases in volume in the New York Stock Exchange Composite Index. Such volume increases are found to signal subsequent increases in price under certain conditions during the period from 1981 to 1999, the Great Bull Market. A 120-trading-day history of price and volume is used to forecast price movement at horizons from 20 to 100 trading days.     

Two-dimensional cutting stock problem research: A review and a new rectangular layout algorithm

The two-dimensional cutting stock problem addresses the allocation of a required bill of materials onto stock sheets in a manner that minimizes the trim losses. This paper surveys the progress made on the study of the problem from the original contributions by Gilmore and Gomory in the mid-1960s to the present. Conclusions are for these algorithms to find greater application in industry, one must consider the allocation of both regular and irregular shapes. Moreover, the objective of minimizing the trim losses is not an adequate performance measure when the cutting department is placed in the perspective of the entire manufacturing system. The costs of inventory and production have to be included in the objective to be minimized in order to ensure maximum production efficiency. In addition, an algorithm based on the first fit decreasing heuristic¹ is presented to achieve layouts of rectangular bills of material on rectangular stock sheets, and its performance is examined. A number of nesting algorithms are currently in use in industry, but virtually all of these systems are considered to be highly proprietary and specific. The cutting stock problem has been variously adapted to applications in numerous industries. From its original form described later, it has been modified for use in paper, lumber, cloth, metal, leather stamping and other industries. In each case, the problem has been reformulated to suit the needs of the specific industry.     

Nitrate removal with reverse osmosis in a rural area in South Africa

The nitrate-nitrogen concentration (>6 mg/l) and the salinity (>1000 mg/l TDS) of many borehole waters in rural areas in South Africa are too high for human consumption. Therefore, an urgent need for water denitrification and water desalination exists in these areas. Reverse osmosis (RO), electrodialysis (ED), ion-exchange (IX) and certain biological technologies can be very effectively applied for water denitrification. Each of these technologies, however, has its own advantages and disadvantages. Reverse osmosis technology, however, has been selected for this study because the technology is well known in South Africa and because it can be very effectively applied for water desalination. The objectives of this study were: (a) to transfer RO technology through process demonstration performance for water denitrification and water desalination to people living in rural areas; (b) to build capacity regarding the operation and maintenance of an RO application in a rural area; (c) to produce a preliminary operational and maintenance manual for the operation of an RO unit in a rural environment; (d) to train local operators to operate and maintain an RO plant in a rural environment; (e) to evaluate stock watering as brine disposal option; and (f) to determine the preliminary economics ofthe process. The following conclusions were drawn. It was demonstratedthatthe RO process could be very effectively applied for water denitrification and water desalination in a rural area. Nitrate-nitrogen was reduced from 42.5 mg/l in the RO feed to only 0.9 mg/l in the RO product water. The TDS of the RO feed was reduced from 1292 mg/l to 24 mg/l in the RO permeate. Therefore, an excellent quality water could be produced for potable purposes. The RO brine at approximately 50% water recovery should be suitable for stock watering if the conditions for stock watering are met in terms of nitrate-nitrogen concentration, TDS and other constituent concentrations. The capital cost for an approximately 50 m³/d output RO plant is approximately US $29,900. Preliminary cost estimates have shown that the operational cost for water denitrification is approximately US $0.50/m³. This cost, however, should be significantly reduced by optimisation of the chemical dosing and by blending borehole water with RO product water.     

An analysis of the flexibility of Asymmetric Power GARCH models

The Asymmetric Power GARCH (APGARCH) model allows a wider class of power transformations than simply taking the absolute value or squaring the data as in classical heteroscedastic models. A dynamic estimation is used to compare the three GARCH families and examine their forecasting performances in a value-at-risk setting. The results suggest that the optimal power transformation obtained with the APGARCH model is virtually never statistically different from 1 or 2. Moreover, although some indices switch between these two values over the time, the measures of accuracy and efficiency used to assess the performance of VaR forecasts indicate that the additional flexibility brought by the APGARCH model provides little, if any, improvements for risk management.     

试论股票流通配额制度

本文提出了一项关于金融体制转换的建议:实行股票流通与交换配额制度。方案的特点主要在以现实条件为依托,逐步打破资金统配,采用凭借流通券交易股票的方式,克服垄断和严重的资源浪费等资本主义发展中常见的痼疾。     

Herbicidal activity of sulforaphene from stock (Matthiola incana)

A herbicidal compound was isolated from extracts ofMatthiola incana and identified as sulforaphene (4-methylsulfinyl-3-butenyl isothiocyanate). The ED₅₀ of this compound against velvetleaf seedlings was approximately 2×10^–4 M. Glucoraphenin, the glucosinolate that is the natural precursor of sulforaphene, was less phytotoxic, with an ED₅₀ of near 6×10^–3M.The mention of firm name or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned.     

Quick and precise clustering of arbitrarily shaped flat patterns based on stringy effect

Grouping a given number of arbitrarily shaped flat patterns to form a cluster which occupies minimal-area convex enclosure is very useful in solving cutting stock problem. This study is aimed at improving the effectiveness of conventional clustering processes by incorporating a new technique for the determination of optimal conditions for the sliding process. The new technique is referred to as ‘stringy effect’ which is based on minimizing the distance between centroids of the patterns during clustering. The efficiency of the proposed method is shown with the help of some typical multiple flat patterns.