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71.
湖北“人口-经济-空间”城市化及其层级结构 总被引:2,自引:0,他引:2
城市化的内在协调性是城市(区域乃至国家)综合竞争力、国民生计及可持续发展能力的综合体现。基于对城市化概念与内涵的认知--城市化是一个“人口 经济 空间”三维一体的过程,其中人是行为主体,经济是驱动力,空间是载体,构建了城市化综合测度指标,并运用时序全局主成分分析法,对2000年以来湖北省12个地级市的城市化层级结构演变过程及趋势进行了分析。结果表明湖北省城市化具有如下特征:① 城市化总量时序演变上呈现出明显的上升趋势,且存在经济城市化>空间城市化>综合城市化>人口城市化的变化趋势,但也表现出一定程度的粗放增长的内在特征;② 整个城市化过程是一个由人口城市化导向型向经济城市化导向型转变的过程;③ 城市化相关系数的时序演变与人口城市化集聚程度>空间城市化集聚程度>经济城市化集聚程度的演变趋势密切相关,表明综合城市化与人口城市化的地域协调性最高,而与经济的最低;④ 城市化等级体系空间结构及其时序演变具有首位度城市层级结构、城市层级结构动态演变,以及城市化地域协调性不强等特征;最后就城市化的协调发展提出对策和建议。为我国城市化可持续发展研究以及湖北省今后的城市化发展战略提供了理论借鉴和实践指导 相似文献
72.
Tracing the sources of refractory dissolved organic matter in a large artificial lake using multiple analytical tools 总被引:2,自引:0,他引:2
Structural and chemical characteristics of refractory dissolved organic matter (RDOM) from seven different sources (algae, leaf litter, reed, compost, field soil, paddy water, treated sewage) were examined using multiple analytical tools, and they were compared with those of RDOM in a large artificial lake (Lake Paldang, Korea). Treated sewage, paddy water, and field soil were distinguished from the other sources investigated by their relatively low specific UV absorbance (SUVA) values and more pronounced fulvic-like versus humic-like fluorescence of the RDOM samples. Microbial derived RDOM from algae and treated sewage showed relatively low apparent molecular weight and a higher fraction of hydrophilic bases relative to the total hydrophilic fraction. For the biopolymer types, the presence of polyhydroxy aromatics with the high abundance of proteins was observed only for vascular plant-based RDOM (i.e., leaf litter and reed). Molecular weight values exhibited positive correlations with the SUVA and the hydrophobic content among the different RDOM, suggesting that hydrophobic and condensed aromatic structures may be the main components of high molecular weight RDOM. Principal component analysis revealed that approximately 77% of the variance in the RDOM characteristics might be explained by the source difference (i.e., terrestrial and microbial derived) and a tendency of further microbial transformation. Combined results demonstrated that the properties of the lake RDOM were largely affected by the upstream sources of field soil, paddy water, and treated sewage, which are characterized by low molecular weight UV-absorbing and non-aromatic structures with relatively high resistance to further degradation. 相似文献
73.
初始pH值对磷酸盐还原除磷的影响研究 总被引:2,自引:0,他引:2
以超高盐(盐度7%,以NaCI计)高磷榨菜废水为研究对象,考察了初始pH值对磷酸盐还原进程的影响。实验结果表明,初始pH值对磷酸盐还原除磷效能影响显著。初始pH为8时,磷酸盐还原除磷率达到最高,平均值为65.45%。同时,初始pH值还会影响污泥中活性磷的形成以及基体对磷化氢的吸附。此外,偏碱性有利于磷形态转化,且BD-P(主要是一些可溶性的、还原性强的、带有Fe-P化合物的集合)含量的高低调控着生物膜内间隙水中溶解态可反应性磷(DRP)和可还原水溶态磷(RSP)含量,最终决定着磷酸盐还原进程。随着初始pH值的升高,污泥对磷化氢的吸附能力降低导致污泥中结合态磷化氢(MBP)含量不断减少。 相似文献
74.
以1961~2007年三江源区的气象及径流资料为基础,采用M K法和R/S分析法分析三江源区气候及水文要素变化趋势及进行未来变化趋势预测,并采用主成分分析法判定径流过程的主要驱动要素。研究表明:三江源区气温普遍显著升高,水面蒸发和地温随着气温的升高也不断增加,降水的增加并不显著,而年径流尤其是夏秋季节径流存在明显减小的趋势。R/S分析结果表明气候和水文要素未来总体的变化趋势与过去一致。三江源区径流过程是由气温起主导作用,径流对气温变化较降水变化更为敏感。本研究将为三江源区水资源开发利用及优化配置提供科学借鉴,同时为三江源区的生态建设和保护提供参考依据 相似文献
75.
76.
Yongnian Ni Lin Wang Serge Kokot 《Journal of environmental science and health. Part. B》2013,48(4):328-335
A novel differential pulse voltammetry method (DPV) was researched and developed for the simultaneous determination of Pendimethalin, Dinoseb and sodium 5-nitroguaiacolate (5NG) with the aid of chemometrics. The voltammograms of these three compounds overlapped significantly, and to facilitate the simultaneous determination of the three analytes, chemometrics methods were applied. These included classical least squares (CLS), principal component regression (PCR), partial least squares (PLS) and radial basis function-artificial neural networks (RBF-ANN). A separately prepared verification data set was used to confirm the calibrations, which were built from the original and first derivative data matrices of the voltammograms. On the basis relative prediction errors and recoveries of the analytes, the RBF-ANN and the DPLS (D – first derivative spectra) models performed best and are particularly recommended for application. The DPLS calibration model was applied satisfactorily for the prediction of the three analytes from market vegetables and lake water samples. 相似文献
77.
Irving Spiewak 《Journal of the American Water Resources Association》1971,7(4):844-855
ABSTRACT The selection of an evaporator design must reflect the balancing of captial cost (primarily in heat exchanger surface and vessels) against operating cost (primarily steam cost) to achieve minimum cost. In a conjunctive plant the tendency is to select a low-capital cost, high-operating cost plant. In addition, it is advantageous to use a high-capacity plant which needs to be operated much less of the time than a plant which is sized just at the needed rate. For example, in the study of a possible system to satisfy a future increase of 450 MGD in water supply to New York Qty, a plant of 750 MGD capacity was selected as optimum. This plant, of the advanced VTE-MSF process type, would have a performance ratio of 9 lb product/1000 Btu as compared to 10-13 normally used for base-loaded plants. Steam would be supplied by a multi-unit dual-purpose nuclear power plant. The most economical type of energy supply would be “interruptible”; the steam would be used by a low pressure turbine to generate electricity during periods of peak electrical demand but would be available to the desalting plant at other times. The low pressure turbine would be available as spinning reserve during desalting plant operation. It is estimated that the desalting plant would have a load factor of 27 per cent over its life. 相似文献
78.
高压旋喷灌浆法是本世纪70 年代发展起来的地基处理新技术,在砂性土和粘性土等软弱地层加固工程中已得到广泛应用,但在含有碎石的淤泥质土及穿过它对其下淤泥的加固尚少见,笔者简要介绍了采用钻灌分开两大工序的新双管法及其成功完成加固任务的事例。 相似文献
79.
本文通过番禺区东涌工业污水处理站污泥特性和污泥堆肥技术的研究,提出了污泥堆肥的可行性,并用之于实践,变废为宝,解决了污泥的处置问题. 相似文献
80.