Water Bloom Precursor Analysis Based on Two Direction S-Rough Set

In the field of water quality management, it is vital to determine the main precursory anomalies from the precursor of intricate water bloom in the context of a given area. In this paper, a water bloom precursor analysis method, based on two direction singular rough set, was proposed. This approach was produced on the basis of the different sections and pre-water bloom of water bloom precursor anomalies and characteristic of elements transferred in singular rough set. For testing the validity of two direction singular rough set application in water bloom precursor analysis, Xiangxi River, which is one of the typical tributaries of Three Gorges Reservoir in China, was selected as study area. The result showed that compared with other indexes, pH and dissolved oxygen (DO) are the most valuable indicators of water bloom in the precursory anomalies. Furthermore, regarding with water bloom precursory anomalies in Xiangxi River, most of the nutrient loading and biological community are the key indicators. Hence, this method can determine the main precursory anomaly for water bloom in the study area, which provides powerful knowledge support to water quality specialists for them to comprehensively analyze precursory anomaly so as to find out its relationship with occurrence law of water bloom.     

以非线性理论阐述反馈振荡器的频率与幅度的稳定性

本文首先对线性的频率稳定理论用于近似正弦反馈振荡器的线性频率稳定理论,进行了评论性的回顾。在这方面,解释所谓的线性振荡器是清楚的。其后,是应用描述函数法和判决方程法所得到新的表达式,去阐述反馈振荡器考虑成一个非线性网络时的振荡频率和振荡幅度的稳定性。     

金沙江下游梯级水库汛期分期及汛限水位合理性研究

汛期分期以及分期汛限水位的合理确定,能够较好地协调水库防洪效益与发电效益之间的矛盾,对充分发挥水库的防洪、发电能力,以及提高汛期洪水资源利用率具有重要意义。基于改进的模糊集分析方法并依据金沙江下游乌东德、白鹤滩、溪洛渡、向家坝4个梯级水库入库洪水对其汛期进行分期,通过隶属度与防洪库容的映射关系确定梯级水库分期汛限水位,提出利用跨期选样法对分期结果及汛限水位进行修正。研究结果表明:金沙江下游梯级水库前汛期为6月1日—7月14日,主汛期为7月15日—9月16日,后汛期为9月17日—10月24日,4个梯级水库合理汛限水位分别为962,800,575,374 m。通过不同典型洪水放大的洪水过程检验了分期汛限水位的合理性。研究得到的金沙江下游梯级分期结果及各库分期汛限水位,均能够在满足防洪安全的前提下提高水库发电等经济效益,在一定程度上提高了汛期洪水资源的利用率。     

南通市地下水压缩开采对水质咸化的控制效应

为了准确评价南通市地下水压缩开采对水质咸化的控制效应,根据南通市的水文地质条件,概化出了南通市的水文地质概念模型,建立了南通市地下水渗流与溶质运移三维耦合数值模型,分别预测了现状开采和压缩开采条件下2018-2034年逐年地下水水位和地下水中氯离子质量浓度的变化趋势。预测结果表明:现状开采条件下2034年底南通市第Ⅲ承压含水层中氯离子质量浓度大于250 mg/L和270 mg/L的面积分别达到355.17 km^2和30.67 km^2,2030-2034年咸化速率为9.59 km^2/a;压缩开采条件下2034年底氯离子质量浓度大于250 mg/L和270 mg/L的面积分别为329.21 km^2和1.76 km^2,2030-2034年咸化速率为7.52 km^2/a,压缩开采方案能有效控制第Ⅲ承压水的咸化问题。     

Earnings Differentials between State and Non-State Enterprises in Urban China

The present paper estimates earnings differentials between state and non-state sectors for Chinese urban residents in 1996 by taking into account differences in non-wage benefits. Household survey data are used to estimate wage differentials while aggregate statistics are utilised in estimating non-wage benefits. We find that state-sector workers earned significantly more than workers in urban collective and domestic private enterprises in 1996. Unskilled workers in foreign invested enterprises (FIE) earned significantly less than those in the state sector but skilled workers earned more in FIE than in the state sector. These findings shed light on the source of labour immobility that state-owned enterprise had experienced until recently.     

论生态经济理论与科教兴农战略

融生态经济理论于科教兴农战略之中,以协调人与自然、经济与生态的关系,指导技术政策的制订和技术措施的选择以及科技兴农成果的评价,是中国式农业现代化的正确选择。     

生产函数与农史研究——评彭、黄大辩论

最近几年来,中国经济史研究中最轰动的大事就是美国加州大学的彭慕兰教授与黄宗智教授有关《大分流》一书的论争。①。细读双方争论的文章内容,可以发现,双方是历史学者,在讨论经济史时,对生产函数的概念与含苞欲放义并没有正确的理解。如果能够廓清一下,争论双方的逻辑可以变得更周严,双方之间的争论也许可以缓解一些。在此我只提三点,加以简述: (1)生产函数中边际产量下降的经济含义; (2)劳动生产力增加的泉源; (3 )边际产量之分析对中国小农的适用性。一　边际产量下降的含义黄宗智每次提到“内卷化”,总是写明定义是“劳动边际报酬…