沈四联污水处理的措施研究

沈阳采油厂的沈四联负责沈84块原油处理、原油外输以及污水处理工作,为了确保回注污水水质达到低渗区块的要求,针对污水处理中存在的实际问题提出改进方案,完善了过滤罐内部整体结构。同时采用新型滤料提高处理效果,对除油罐内部进水结构进行了优化改造,强化除油罐液位控制管理,沈四联的污水处理质量得到明显提高。     

基于分位数回归的粮食产量影响因素分析——以湖北省为例

影响粮食产量的主要因素有播种面积、成灾面积、农用机械总动力、化肥投入折纯量、农村用电量、有效灌溉面积等方面。利用HP滤波处理1979年至2009年湖北省粮食产量数据得出其的波动特征,并将各时间序列的长期趋势剔除,使序列仅含波动项以进行分位数分析。结果表明：在粮食产量的低分位点上,各因素对粮食增产的作用明显;在其它分位点处,作用不明显。需要确保粮食播种面积,科学投放化肥,保障农业生产用电,鼓励粮食生产规模化,完善粮食生产的风险管理工具和制度,以保证粮食产量,保障粮食安全。     

The Stochastic Seasonal Behaviour of Natural Gas Prices

Previous studies have explored the seasonal behaviour of commodity prices as a deterministic factor. This paper goes further by proposing a general (n+2m)‐factor model for the stochastic behaviour of commodity prices, which nests the deterministic seasonal model by Sorensen (2002) . We consider seasonality as a stochastic factor, with n non‐seasonal and m seasonal factors. The non‐seasonal factors are as defined in Schwartz (1997) , Schwartz and Smith (2000) and Cortazar and Schwartz (2003) . The seasonal factors are trigonometric components generated by stochastic processes. The model has been applied to the Henry Hub natural gas futures contracts listed by NYMEX. We find that models allowing for stochastic seasonality outperform standard models with deterministic seasonality. We obtain similar results with other energy commodities. Moreover, we find that stochastic seasonality implies that the volatility of futures returns follows a seasonal pattern. This result has important implications in terms of option pricing.     

注水过滤器滤芯主体质量可靠性试验与改进

结合采油现场实际，通过综合分析滤芯失效的表现形式，将滤芯材质、主体管壁厚度、过水孔密度作为影响滤芯主体现场使用寿命的三个可靠性主导影响因素，合理确定位极，科学设计试验方案；通过对过滤器滤芯主体的筛选试验，确定了经济合理、满足现场需要的滤芯主体。采用新型滤芯主体实现了在保持注水流量的同时，提高了滤芯的承压强度，可靠性增强。新型滤芯主体在正常工作压力环境中，使用时间平均为30天，是改进前的3倍。采用可拆洗式滤网结构,更换滤网方便快捷,减少了工人的劳动强度，可有效节约滤芯的成本投入,推广应用前景广阔。     

A Closer Look at the Relation between GARCH and Stochastic Autoregressive Volatility

We show that, for three common SARV models, fitting a minimummean square linear filter is equivalent to fitting a GARCH model.This suggests that GARCH models may be useful for filtering,forecasting, and parameter estimation in stochastic volatilitysettings. To investigate, we use simulations to evaluate howthe three SARV models and their associated GARCH filters performunder controlled conditions and then we use daily currency andequity index returns to evaluate how the models perform in arisk management application. Although the GARCH models produceless precise forecasts than the SARV models in the simulations,it is not clear that the performance differences are large enoughto be economically meaningful. Consistent with this view, wefind that the GARCH and SARV models perform comparably in testsof conditional value-at-risk estimates using the actual data.     

住宅市场量价关系分析——基于香港数据的实证研究

本文基于滤波方法-9向量自回归模型，对香港十多年的住宅交易量和价格数据进行实证研究。结果显示，考察1996．1-1997．6区间的样本交易量与价格互为格兰杰因果关系，表现出正反馈效应，投机现象非常明显。但当选取1997．7-2007．7区间的样本则仅发现价格是交易量的格兰杰原因，并不存在双向因果关系。方差分解结果表明，交易量波动对于价格波动的影响要大于价格波动对于交易量的影响。     

Varying the VaR for unconditional and conditional environments

Accurate forecasting of risk is the key to successful risk management techniques. Using the largest stock index futures from 12 European bourses, this paper presents VaR measures based on their unconditional and conditional distributions for single and multi-period settings. These measures underpinned by extreme value theory are statistically robust explicitly allowing for fat-tailed densities. Conditional tail estimates accounting for volatility clustering are obtained by adjusting the unconditional extreme value procedure with GARCH filtered returns. The conditional modelling results in iid returns allowing for the use of a simple and efficient multi-period extreme value scaling law. The paper examines the properties of these distinct conditional and unconditional trading models. The paper finds that the biases inherent in unconditional single and multi-period estimates assuming normality extend to the conditional setting.     

GDP growth and currency valuation: The case of the dollar

One popular view on the strength of the US dollar around the turn of the century is that the higher growth in the US compared to Europe had stimulated foreigners to buy American assets, thereby driving up the exchange rate. In this paper a modified portfolio balance model is presented, in which it is shown that the impact of output growth on the exchange rate depends crucially on the origin of this growth. An improvement of the output gap is shown to actually depress the exchange rate whereas an increase in potential output growth leads to an appreciation, especially if this improvement is likely to be persistent. In an empirical example, it is shown that the equilibrium real dollar rate is indeed positively affected by high trend growth in the US, whereas it is negatively affected by a positive output gap. The model outperforms the random walk in forecasting future real dollar rates one to eight quarters ahead.     

码移键控系统的性能分析

讨论了码移键控(CSK)基本原理、基于数字匹配滤波器(DMF)的快速捕获结构和用相关乘法器代替数字匹配滤波器的快速捕获结构,并对CSK系统的接收性能进行数学分析,得到了数据码错误率公式。     

A system approach for measuring the euro area NAIRU

This paper addresses the issue of measuring the NAIRU for the euro area and assessing the robustness and precision of the obtained estimates. The empirical framework adopted is based on systems combining an Okun-type relationship between cyclical unemployment and the output gap with a Phillips curve and stochastic laws of motion for the NAIRU and potential output. Such systems have been estimated using Kalman-filter techniques. The results obtained point to an estimate of the area-wide NAIRU that is robust to changes in the underlying models. This robustness is shown to hold both in terms of the mean – i.e., the shape of the resulting NAIRU – and the variance of the process. The latter is derived through bootstrap exercises using the models alone or pooled together. The evidence found suggests that the increase in the aggregate NAIRU that took place in the early part of the sample period has come to a halt and may be about to be reversed.Jel classification: C11, C15, E31, E32The opinions expressed in this paper are those of the authors and do not necessarily reflect the views of the Institutions they belong to. The authors are grateful to Per Jansson for providing parts of the econometric RATS code and to Gonzalo Camba-Mendez and Frank Smets of the ECB for useful comments. Comments and recommendations by two anonimous referees are also gratefully acnowledged. All the remaining errors are the authors responsibility. All correspondence to Ricardo Mestre.First version received: January 2002/Final version received December 2002