Variations in Spectral Slope in Lake Taihu,a Large Subtropical Shallow Lake in China

Spectral slope (S), describing the exponential decrease of the absorption spectrum over a given wavelength range, is an important parameter in the study of of chromophoric dissolved organic matter (CDOM) dynamics, and also an essential input parameter in remote sensing models. Furthermore, S is often used as a proxy for CDOM composition, including the ratio of fulvic to humic acids and molecular weight. The relative broad range in S values reported in the literature can be explained by the different spectral ranges and fitting methods used. A single exponential model is used to fit the S values for 17 investigations involving 458 samples in Lake Taihu from January to October in 2004. The average S value was 15.18 ± 1.39 μm⁻¹ for the range of 280–500 nm, which fell within the range reported in the literature. The frequency distribution of S value basically obeyed a normal distribution. Significant differences in S values between summer and other seasons showed that phytoplankton degradation was one of the important sources of CDOM in summer, whereas CDOM mainly came from the river input in other seasons. Furthermore, the estimated S value decreased with increasing wavelength range used in regression. The maximum and minimum values derived from the regression were 17.89 ± 1.25 μm⁻¹ and 13.62 ± 2.11 μm⁻¹ for the wavelength ranges of 280–380 nm and 400–500 nm, respectively, a decrease of 23.9%. S values significantly decreased with the increase of CDOM absorption coefficients. CDOM absorption coefficients could be more appropriately estimated from exponential model introducing the variation of S with absorption coefficients, making them useful for a remote sensing bio-optical model of Lake Taihu. DOC-specific absorption coefficient a*(λ) and the parameter M describing molecular size of the humic molecules could also be used as a proxy for the sources and types of CDOM. A general relationship was found between S and a*(λ), and M values. S increased with the decrease of DOC-specific absorption coefficient and the increase of M corresponding to the decrease of molecular weight.     

精馏过程的节能和优化设计的探讨

精馏过程的节能,对于减少能源消耗,降低生产成本和保护环境具有十分重要的意义.在精馏过程中可以采用最适宜回流比操作和最佳进料状态,使用中间冷凝器和中间再沸器,高效精馏、热泵精馏.合理安排多组分物料分离流程,直接利用过程热量及开发应用高效换热器等措施.本文从最佳回流比R的选择、进料温度及进料状态的确定等方面,详细的分析了在精馏塔的设计过程中,如何实现设计的优化问题,以实现节能降耗.     

永远流淌的大瀑布——欧茨小说《大瀑布》的生态解读

全球变暖,生态危机是当下最热点话题,因为生态危机已经威胁到了人类的生命安全.跟许多有识之士一样,欧茨也关注生态问题,虽然她不是生态主义者,更不是生态女性主义者.近作<大瀑布>探讨了人与人、人与社会、人与自然的关系,尤其是人与自然关系的思考给读者以启示:人类只不过是生物圈的一份子而已,任何生命体都有其内在价值.     

区港合一与厦门港城经济发展

区港合一指的是保税区、港口码头作业区实行一体化运作,在货物监管上采取一线放开、二线管住、区内宽松的自由贸易模式。按照构想,在厦门实行区、港合一,主要是充分利用象屿保税区坐落在东渡港区、区内无居民而便于实行隔离监管的优势,将象屿保税区与东渡港区进行组合,形成一体     

新时期广东省山区人口控制探析

20世纪90年代以来，广东省的山区人口增长速度虽然得到了控制，但与珠江三角洲相比还存在一定差距，地区之间发展也不平衡，生育水平仍不稳定，有效的人口控制机制尚末真正形成。因此，必须建立保障体系 和切合实际人口控制工作新机制，把人口控制工作寓于服务之中；加强计划生育队伍建设，提高队伍整体素质和工作效率。     

SIMILARITY LAW OF FLUCTUATING PRESSURE WITHIN HYDRAULIC JUMP AREA

Through a series of model tests of five scales for 2-D free hydraulic jump, the da-ta of fluctuating pressure acting on the floor level within the hydraulic jump were obtained. Dur-ing the experiments, Froude number varied from 2.94 to 8.61, and Reynolds number rangedfrom 2×10~4 to 6×10~5. Experiment results indicate that the amplitude scale of fluctuating pres-sure is the length scale of model, i. e. P'=L, which agrees with gravity similarity law: Thefrequency scale of the fluctuating pressure is a unity i. e., f=1, which does not satisfy thegravity similarity law.     

关于供排水管网的水力计算和校核

以往对电站技术供排水系统大都未进行水力平差计算，致使一些实际电站的供排水系统达不到预期的效果，甚至影响机组的正常运行。据此，给出了供排水管网的平差计算方法，有利于正确评估电站管网，另外，提出了管网校核应注意的问题。     

鄱阳湖流域水土保持与防洪治涝

鄱阳湖流域水土流失加剧了洪涝灾害。治理水土流失能增强山丘地涵养水源的能力,削洪减沙,减少库容损失,降低河床,具有明显的防洪效益。进行流域防洪规划时,应将防治水土流失与防洪治涝结合起来,因地制宣,综合治理。