STUDY OF TURBULENT FLOW STRUCTURE AND CONTAMINANT DISTRIBUTION IN A 45°－BEND BY 3－D 2－LAYER MODEL

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Rapid identification of single constant contaminant source by considering characteristics of real sensors

For the release of hazardous contaminant indoors, source identification is critical for developing effective response measures. A method which can quickly and accurately identify the position, emission rate, and release time of a single constant contaminant source by using real sensors was presented. The method was numerically demonstrated and validated by a case study of contaminant release in a three-dimensional office. The effects of the measurement errors and total sampling period of sensor on the performance of source identification were thoroughly studied. The results indicate that the adverse effects of the measurement errors can be mitigated by extending the total sampling period. For reaching a desirable accuracy of source identification, the total sampling period should exceed a certain threshold, which can be determined by repeatedly running the identification method until the results tend to be stable. The method presented can contribute to develop an onsite source identification system for protecting occupants from indoor releases.     

Experimental study on the effects of sediment size and porosity on contaminant adsorption/desorption and interfacial diffusion characteristics

The joint effects of the sediment size and porosity on the contaminant adsorption/desorption and interfacial diffusion characteristics were experimentally investigated. The adsorption of Phosphorus (P) on the natural and artificial sediment suspensions was measured with respect to the P adsorption isotherms and kinetics in the experiment. The obtained adsorption isotherms for different grain-sized sediment suspensions fit well with the Langmuir equation, dependent on the initial aqueous concentration and sediment content. The P kinetic adsorption behaviors for cohesive fine-grained and non-cohesive coarse-grained sediment suspensions clearly show the size-dependent feature. On the other hand, the P kinetic release feature of a porous sediment layer is affected by not only the direct desorption of the uppermost sediments, but also the diffusivity in the pore-water within the underlying sediment layer, characterized by the sediment size and porosity, respectively. Furthermore, the temporal contaminant release from the permeable sediment layer into the overlying water column increases with the increasing flow velocity, while this enhancement in mediating the interfacial diffusion flux is somewhat insignificant in an immediate release stage, largely due to the resistance of the diffusive boundary layer on the hydrodynamic disturbance.     

铝沉积还原制备蓝色二氧化钛

在光催化研究中, 提高光催化剂的催化效率, 降低催化剂成本吸引了广泛的研究兴趣。本研究通过铝沉积还原方法制备出表面铝原子修饰的蓝色二氧化钛。该蓝色二氧化钛具有一种独特的核壳结构, 纳米颗粒内部为结晶核, 外部为含有大量氧空位和一定量沉积铝原子的非晶层。在模拟太阳光照射下, 该蓝色二氧化钛表现出优异的光催化污染物降解和光电化学性能。在高真空条件下, 当蒸发的金属铝原子沉积在二氧化钛纳米颗粒上时, 可以进一步将Ti⁴⁺还原成Ti³⁺, 使得催化剂表面含有大量的氧空位等表面缺陷。此外, 适量的铝沉积在催化剂表面成为光生载流子阱, 促进光生载流子的分离和输运, 从而使得样品光催化活性增强。当沉积适量Al时, 样品TiO₂-Al_0.36表现出最为优异的光催化污染物降解性能, 在8 min内就可将甲基橙溶液完全降解, 且其光电流(1.47 mA·cm^-2)是本征二氧化钛(0.17 mA·cm^-2)的8倍以上, 展现出优异的光电化学性能。     

基于复杂agent的水污染运移仿真模拟

针对水污染运移仿真表现力不强的问题,采用复杂性理论思想,在干流河道多尺度分解的基础上形成水质体积微元,建立具有吸附行为、自净行为、沉降行为、挥发行为、平推行为、扩散行为和演化行为的复杂agent模型,开展基于高性能计算技术的agent计算力优化,实现以多agent涌现为特征的污染物运移仿真模拟,并在数字地球上进行可视化表现.实验表明,该方法能够有效反映污染物的演化状况,并可以汇集3S所提供的地形地貌数据,更加丰富直观地表现水污染运移过程.     

入河排污口的监督管理

根据新水法和水功能区规划,对入河排污口的监督管理提出了合理的建议。     

优化锅炉连续排污控制方式

以在线炉水电导率表的输出信号控制连排阀门开度实现连排自动控制，在特定条件下，能取得一定的实际效果。但其会与汽包加药造成冲突，二者难以协调工作。因此提出，根据炉水中硅酸的蒸汽溶解携带性最强的特性，以在线炉水硅表控制连排会取得更好的控制水汽质量的效果。     

基于紫外成像的污秽绝缘子放电特性研究

污秽绝缘子在一定的湿度下会形成放电并辐射出紫外光信号,日盲紫外成像是一种有效的放电检测方法,首先在人工气候室中研究了几种不同污秽度的绝缘子在不同湿度下的放电现象,根据放电紫外图像特征将放电分为两个典型阶段,通过对放电视频信号的分析并结合图像处理算法提取了平稳紫外光斑面积、间歇性紫外光斑面积以及间歇性紫外光斑重复次数三个特征参数来表征其放电,得到了上述参数与湿度和污秽度之间的关系曲线,研究结果将为基于紫外成像法评估污秽状态奠定基础。     

基于声发射技术的绝缘子在线监测方法的研究

通过对绝缘子现行的污秽监测方法的研究分析,提出了基于声发射技术的绝缘子污秽放电在线监测方法,对电晕放电和污秽放电声发射信号进行了实验研究,并对两者放电声发射在波形相位与强度上的差别进行了分析比较,基本消除了电晕放电对污秽放电声发射信号的干扰,从而揭示了污秽放电的严重程度和声信号之间的关系,证明了声发射技术在绝缘子在线检测上的可行性。     

污染物离子在粘土介质中扩散系数和分配系数的测定(英文)

介绍了利用一种自制的特殊装置,测定污染物离子在粘土介质中迁移的扩散参数D和分配系数Kd的方法。通过一系列污染物在上海粘土中的纯扩散迁移试验,系统中污染物的质量不变,源浓度随试验的进行是下降的,运用一个简单的理论模型,通过拉普拉撕(Laplace)变换方法,对一个单独的试验,可同时推断出扩散系数和分配系数。通过拉普拉撕转换程序求出了阴离子(Cl-)和阳离子(K+,Ca2+,Zn2+,Cu2+)的扩散系数D和分配系数Kd。试验结果发现:阴离子在粘性土壤中的显扩散系数比阳离子的大;一价阳离子K+的显扩散系数比二价阳离子的大。