关于我国农业可持续发展的若干思考

农业可持续发展的理念是对传统的农业现代化思路的否定，它要求逐步改变形成于计划经济时代的旧的生产经营体制，这是一项长期，杂复和艰巨的任务，我们必须为此作不懈的努力。     

A nonlinear long memory model, with an application to US unemployment

Two important empirical features of US unemployment are that shocks to the series seem rather persistent and that it seems to rise faster during recessions than that it falls during expansions. To jointly capture these features of long memory and nonlinearity, we put forward a new time series model and evaluate its empirical performance. We find that the model describes the data rather well and that it outperforms related competitive models on various measures of fit.     

构建“三个代表”重要思想“三进”的运作体系

党的十六大把“三个代表”重要思想写进党章,作为党必须长期坚持的指导思想。把“三个代表”重要思想与邓小平理论同时“进教材、进课堂、进学生头脑”,是新的形势向高校提出的战略任务。     

论税收的时效性

时效性是税收强制性在时间上的体现，是税法赋予的一种规定性，是国家财政收支及时稳定的重要保证，是依法治税的必然要求，是衡量税务机关征管水平的基本依据。不论是税收法治的严肃性，还是国家各项事业急需财政资金的现实，都迫切需求提高税收的时效性。及时有效地组织好财政收入。     

A note on the Robust Trend and ARARMA methodologies used in the M3 Competition

This brief note describes two of the forecasting methods used in the M3 Competition, Robust Trend and ARARMA. The origins of these methods are very different. Robust Trend was introduced to model the special features of some telecommunications time series. It was subsequently found to be competitive with Holt’s linear model for the more varied set of time series used in the M1 Competition. The ARARMA methodology was proposed by Parzen as a general time series modelling procedure, and can be thought of as an alternative to the ARIMA methodology of Box and Jenkins. This method was used in the M1 Competition and achieved the lowest mean absolute percentage error for longer forecasting horizons. These methods will be described in more detail and some comments on their use in the M3 Competition conclude this note.     

Mean squared error of the empirical best linear unbiased predictor in an orthogonal finite discrete spectrum linear regression model

The mean squared error (MSE) of the empirical best linear unbiased predictor in an orthogonal finite discrete spectrum linear regression model is derived and a comparison with the MSE of the best linear unbiased predictor in this model is made. It is shown that under weak conditions these two mean square errors are asymptotically the same.     

The asymmetry of judgemental confidence intervals in time series forecasting

In forecasting a time series, one may be asked to communicate the likely distribution of the future actual value, often expressed as a confidence interval. Whilst the accuracy (calibration) of these intervals has dominated most studies to date, this paper is concerned with other possible characteristics of the intervals. It reports a study in which the prevalence and determinants of the symmetry of judgemental confidence intervals in time series forecasting was examined. Most prior work has assumed that this interval is symmetrically placed around the forecast. However, this study shows that people generally estimate asymmetric confidence intervals where the forecast is not the midpoint of the estimated interval. Many of these intervals are grossly asymmetric. Results indicate that the placement of the forecast in relation to the last actual value of a time series is a major determinant of the direction and size of the asymmetry.     

Distance in time between transition economies and the European Union

The time distance methodology used offers a new perspective to the problem, an additional statistical measure, and a presentation tool for policy analysis and debate readily understood by policy makers, media and general public. Disparity between the analysed transition economies and EU countries is considerably smaller for other indicators than for GDP per capita. Compared with Ireland, Portugal and Greece Slovenia was in 1995 in 13 cases behind (but time lag of Slovenia never exceeded 10 years) and in 13 cases ahead of them. Sicherl (1997a) discusses application of S-distance to time series regressions, models, forecasting and monitoring. First version received: October 1995/final version received: April 1998     

评审专家抽取中的时间距离约束分析

针对现有评审专家抽取中距离约束存在的不足,本文提出了一种新的时间距离约束。本文介绍了时间距离的含义及其提出的必要性,并给出了基于GIS技术的时间距离计算方法,具体包括相关假设、计算步骤、解决方案以及实现过程。时间距离约束的提出不仅可以保证所有被选专家都可按时到达评审地点,而且还能打破行政区域的限制,合理调配专家资源,具有重要的现实意义。     

一种利用短时DFT分析实现全数字2DPSK接收机解调的新算法

本文提出了一种简单而实用的利用短时DFT（ST-DFT）分析实现全数字2DPSK接收机的解调算法。该算法对由多谱勒效应引起的时变频率漂移具有鲁棒性。由于该算法是通过检测在载频处的瞬时能量谱的跳变来实现2DPSK信号的解调，所以该算法不需要进行专门的载波相位恢复、符号定时，且具有较好的抗噪性能，实现起来简单。