煤炭城市生态环境可持续发展研究--以淮南市为例

根据城市生态学原理和方法,针对煤炭城市生态环境特点,构建了能够体现煤炭城市生态环境质量主要特征的,定性、定量考核的评价指标体系。利用层次分析、变权综合指数等方法,建立了煤炭城市生态环境质量综合评价模型。从自然、经济、社会三个方面对淮南市生态环境质量进行评价,并对淮南市生态环境可持续发展提出了相应对策。     

Ammonium regeneration in intertidal sediments of the Yangtze estuary during air-exposure

The influences of exposure to the atmosphere on ammonium cycle in the intertidal surface sediments were in situ studied with a geochemical approach at a typical station in the Yangtze Estuary during three tidal cycles in September 2003. During an about 8-h emersion period of each diurnal tide, six high-resolution vertical profiles of adsorbed and dissolved ammonium were measured. It was observed that both adsorbed and dissolved ammonium generally had an increasing trend in sediment cores during the exposure. The rate of ammonium regeneration in sediments was estimated using the accumulation amount of ammonium including adsorbed and soluble fractions during the daytime emersion. The calculation result showed that there was relatively high ammonification rate (˜500 nmol N cm⁻³ day⁻¹), which reflected that organic nitrogen in sediments was quickly decomposed with a residence time of ˜52.7 days. Due to the dramatic temperature difference observed in sediment profiles, free convection was considered an important mechanism of regulating the efflux of produced ammonium into overlying waters. The total estimated amount of regenerated ammonium was ˜1.35×10⁵ t N year⁻¹ in the intertidal flat of the Yangtze Estuary, which occupied 7.6% of the total inorganic nitrogen annually transported to the estuarine ecosystem.     

A model of equilibrium bed topography for meander bends with erodible banks

Channel curvature produces secondary currents and a transverse sloping channel bed, along which the depth increases towards the outer bank. As a result deep pools tend to form adjacent to the outer bank, promoting bank collapse. The interaction of sediment grains with the primary and secondary flow and the transverse sloping bed also causes meanders to move different grain sizes in different proportions and directions, resulting in a consistent sorting pattern. Several models have been developed to describe this process, but they all have the potential to over‐predict pool depth because they cannot account for the influence of erodible banks. In reality, bank collapse might lead to the development of a wider, shallower cross‐section and any resulting flow depth discrepancy can bias associated predictions of flow, sediment transport, and grain‐size sorting. While bed topography, sediment transport and grain sorting in bends will partly be controlled by the sedimentary characteristics of the bank materials, the magnitude of this effect has not previously been explored. This paper reports the development of a model of flow, sediment transport, grain‐size sorting, and bed topography for river bends with erodible banks. The model is tested via intercomparison of predicted and observed bed topography in one low‐energy (5·3 W m^?2 specific stream power) and one high‐energy (43·4 W m^?2) study reach, namely the River South Esk in Scotland and Goodwin Creek in Mississippi, respectively. Model predictions of bed topography are found to be satisfactory, at least close to the apices of bends. Finally, the model is used in sensitivity analyses that provide insight into the influence of bank erodibility on equilibrium meander morphology and associated patterns of grain‐size sorting. The sensitivity of meander response to bank cohesion is found to increase as a function of the available stream power within the two study bends. Copyright © 2002 John Wiley & Sons, Ltd.     

DSQ型水管倾斜仪电压灵敏度的调整技巧

DSQ型水管倾斜仪是“九五”期间推出的数字化地震前兆仪器，本文介绍了一些如何调整换能器的电压灵敏度及调整中的技巧。     

北江大堤植草护坡效应研究

北江大堤在航运的浪涛侵蚀以及洪水和雨水的冲蚀下，部分河段边坡已变得支离破碎，对广州和珠江三角洲地区的防洪安全构成了严重威胁。香根草和百喜草都能耐较长时间的水淹，并都有较强的抗逆性。结合土石方工程，并辅以三维网覆盖，将香根草和百喜种在北江两岸的边坡上。结果，这一护坡措施不仅有较地防止了洪流冲蚀和雨水侵蚀，较好地起到了固土护坡作用，而且绿化美化了河岸边坡，成功解决了河湖水库的河岸带难以植被覆盖的难题。     

Parameter identification for lined tunnels in a viscoplastic medium

This paper is dedicated to the identification of constitutive parameters of elasto‐viscoplastic constitutive law from measurements performed on deep underground cavities (typically tunnels). This inverse problem is solved by the minimization of a cost functional of least‐squares type. The exact gradient is computed by the direct differentiation method and the descent is done using the Levenberg–Marquardt algorithm. The method is presented for lined or unlined structures and is applied for an elastoviscoplastic constitutive law of the Perzyna class. Several identification problems are presented in one and two dimensions for different tunnel geometries. The used measurements have been obtained by a preliminary numerical simulation and perturbed with a white noise. The identified responses match the measurements. We also discuss the usage of the sensitivity analysis of the system, provided by the direct differentiation method, for the optimization of in situ monitoring. The sensitivity distribution in space and time assess the location of the measurements points as well as the time of observation needed for reliable identification. Copyright © 2002 John Wiley & Sons, Ltd.     

Sensitivity Analysis of a Feedforward Neural Network for Considering Genetic Mechanisms of Kuroko Deposits

Exploration for volcanogenic massive sulfide deposits of the kuroko-type is underway in many places. Clarifying the spatial patterns of the metals in kuroko deposits will be useful for understanding their genetic mechanisms and for future exploration of such types of deposits. This study represents a spatial distribution analysis on the contents of principal metals of kuroko deposits: Cu, Pb, and Zn, in the Hokuroku district, northern Japan, by a feedforward neural network and 1917 sample data at 143 drillhole sites. The network, which consists of three layers, was trained by the principle of SLANS in which the numbers of neurons in the middle layer and training data are changed to improve estimation accuracy. Using the weight coefficients connecting adjacent neurons, sensitivity analysis of the neural network was carried out to identify factors influencing spatial distributions of the three metals. The coordinates depth (z) direction, Bouguer gravity, and specific lithology such as dacite were determined to be influencing factors. The high frequency of the z coordinate signifies that the metal contents differ to a large extent by depth. The sensitivity vector was defined using sensitivity coefficients for x, y, and z coordinates of an estimation point. We determined that the directions of large vectors were different inside and outside of the Hanawa-Ohdate area. This characteristic is considered to originate from the differences in the permeability of fractures that became the paths for rising ore solutions, and the depths that the solutions mixed with sea water.     

加卸载响应比(LURR)理论的实验研究

利用大尺度岩石试件破坏声发射实验，对加卸载响应比(Load/Unload Response Ratio)理论进行了实验研究。实验采用的加载条件力求能够模拟地下岩石的复杂受力过程。在加载过程中，岩石试件内部出现的损伤用声发射技术进行了记录。实验数据经过分析之后所得的结论与加卸载响应比理论预测的结果相符合。把加卸载响应比值Y的变化情况与声发射事件定位的过程相对比，也可以进一步看出岩石材料内部的损伤发展过程与加卸载响应比Y值的变化具有一致性。而高Y值的异常情况出现，又是在材料发生最终破坏之前，所以，可以用加卸载响应比理论定量地分析岩石试件损伤演化情况，从而对岩石材料的破坏及地震做出预测。实验结果再一次验证了加卸载响应比理论。     

地下非均匀非饱和带中地下洞室的渗流问题数值模拟--介质参数的灵敏度分析

影响任何一个地下废物处置场所长期行为的一个重要因素是进入地下废物贮置洞室内的渗流量的大小，预测地下洞室中的渗流量是困难的，特别是当地下废物贮置洞室位于非均质非饱和带中，三维数值模型用于研究地下非均质中非饱和流动及流入地下洞室中的渗流量，讨论了非均质模型与均质模型的比较以及数值剖分尺度对计算结果的影响，进入洞室中的渗漏率随着引入系统中入渗量的增加而增大，选用4个参数来衡量渗流场的非均质程度：(1)介质的平均渗透率K0；(2)Van Genuchten参数α；(3)渗透率空间分布相关尺度；(4)渗透率空间分布变化的标准差σ，根据一个随机实现的渗透率分布，通过改变平均渗透率来研究其对流入洞室中渗透量的影响，对一个固定的入渗率而言，流入洞室中的渗漏率将随着Van Genuchten参数α的减小而减小，模拟结果表明流入洞室的渗漏率与介质的平均渗透率相关，即随平均渗透率的增大，流入洞室的渗漏率亦增大，流入洞室的渗漏率还高度依赖于非均质渗透率场的空间分布相关长度与标准差，一个大的相关长度或高的标准差均能导致流入洞室的渗漏率增大。     

Modelling of oxygen and nitrogen cycling as a function of macrophyte community in the Thau lagoon

A three-dimensional model coupling physical and biological processes for the whole Thau lagoon (Mediterranean coast of France) was developed in order to assess the relationships between macrophytes and the oxygen and nitrogen cycles. Ten species have been inserted as forcing variables in the model. Plankton dynamics, shellfish cultivation impact and mineralization of organic matter are also considered, as well as nutrient and oxygen exchanges between the sediment and the water column.Simulations with and without the macrophytes have shown that the system can be characterized as having a highly structured pattern involving lagoon nitrogen and oxygen cycles. This pattern is created by the combined influence of macrophytes, watershed and oyster farming.The model has been also used to assess the total annual macrophyte production at the whole lagoon scale. Comparisons with phytoplankton production and with results from other temperate lagoons have underlined the high productivity of the Thau lagoon supported by active nutrient regeneration.