Role of Ponded Turbidity Currents in Reservoir Trap Efficiency

The capacity to store water in a reservoir declines as it traps sediment. A river entering a reservoir forms a prograding delta. Coarse sediment (e.g., sand) deposits in the fluvial topset and avalanching foreset of the delta, and is typically trapped with an efficiency near 100%. The trap efficiency of fine sediment (e.g., mud), on the other hand, may be below 100%, because some of this sediment may pass out of the reservoir without settling out. Here, a model of trap efficiency of mud is developed in terms of the mechanics of a turbidity current that plunges on the foreset. The dam causes a sustained turbidity current to reflect and form a muddy pond bounded upstream by a hydraulic jump. If the interface of this muddy pond rises above any vent or overflow point at the dam, the trap efficiency of mud drops below 100%. A model of the coevolution of topset, foreset, and bottomset in a reservoir that captures the dynamics of the internal muddy pond is presented. Numerical implementation, comparison against an experiment, and application to a field-scale case provide the basis for a physical understanding of the processes that determine reservoir trap efficiency.     

吐温—20增稳浊度法快速测定水泥中三氧化硫

本文研究了一种以非离子表面活性剂吐温－20为介质，硫酸钡浊度法侧定水泥中三氧化硫的新方法。吐温-20的引入使硫酸钡颗粒分散均匀，体系稳定性提高。本文选420nm为测定波长，SO2-4含量在50～500μg／25ml范围内线性关系良好，可很好地适用于水泥样品的分析。     

Towards inverse modeling of turbidity currents: The inverse lock-exchange problem

A new approach is introduced for turbidite modeling, leveraging the potential of computational fluid dynamics methods to simulate the flow processes that led to turbidite formation. The practical use of numerical flow simulation for the purpose of turbidite modeling so far is hindered by the need to specify parameters and initial flow conditions that are a priori unknown. The present study proposes a method to determine optimal simulation parameters via an automated optimization process. An iterative procedure matches deposit predictions from successive flow simulations against available localized reference data, as in practice may be obtained from well logs, and aims at convergence towards the best-fit scenario. The final result is a prediction of the entire deposit thickness and local grain size distribution. The optimization strategy is based on a derivative-free, surrogate-based technique. Direct numerical simulations are performed to compute the flow dynamics. A proof of concept is successfully conducted for the simple test case of a two-dimensional lock-exchange turbidity current. The optimization approach is demonstrated to accurately retrieve the initial conditions used in a reference calculation.     

炼钢轧钢外排污水回用的可行性研究

埋入式磁分离水处理装置成功处理轧钢、炼钢浊循环水,是济钢在实践中发明的专利技术。济钢中板厂利用其技术处理轧钢浊循环水,处理量450m3/h。山东泰山钢铁有限公司拟采用此技术处理炼钢、轧钢外排污水,处理水质达到回用水水质标准。     

地下水pH值、电导率和浊度实时监测仪器

开发了用于地震前兆研究的地下水pH值、电导率和混浊度的智能在线监测仪器。介绍了仪器的软硬件设计,包括采集电路、前置放大电路、传感器及针对在线测量要求的长期稳定性和免维护性的设计,其中浊度传感器采用表面散射的原理设计,光源采用激光。仪器具有人机交互、数据存储、参数校准、串口通讯以及自动在线测量等功能,达到要求的各项指标,并在地震台站长期稳定运行。     

Relationship between static electrification of transformer oils with turbidity and spectrophotometry measurements

The paper presents the research results on electrostatic charging tendency (ECT) of transformer oil in a spinning disk system. The measurements were performed at different aging severity. Changes in static electrification were related to some classical aging indexes (conductivity, dissipation factor, water content, resistivity, etc.). Fast, inexpensive and reliable laboratory testing procedures developed by ASTM (D 6802 and D 6181) were also used to monitor the decay products as trace impurities. The obtained results show that static electrification currents increase with temperature, oil flow velocity, coating disk material properties and oil’s aging byproducts. The polarity, the amplitude and the time constant of the streaming electrification currents are also affected. This contribution is not only intended to provide a fresh review in this domain of research, but also contains a substantial amount of new material with a view of closing some gaps in the present state of knowledge of transformer oil streaming electrification phenomenon.     

Turbidity control and fisheries enhancement in a bottomland hardwood backwater system in Louisiana (U.S.A.)

In response to a noticeable decline in recreational fishing in the formerly productive Larto—Saline backwater complex of east central Louisiana, a study was begun to identify causative factors for the decline and to determine effective methods to remedy the problem. To this end, water quality and fisheries surveys were conducted in the system for the study period 1 July, 1981 to 30 June, 1989. Data collected during the early years of the study indicated chronically high turbidity (> 100 FTU) to be the major factor limiting game fish production. The high turbidity can be related to man-made alterations of natural flood patterns that had changed the major source of backwater flooding from Black River to the highly turbid Red River. In September, 1986, a construction project was undertaken to restore flood patterns to approximate natural conditions. Sampling subsequent to this construction has shown a significant decrease in turbidity and an increase in game fish production.     

应用流式细胞仪判断二次胶黏物

在纸浆悬浮液中分别加入3种阳离子定着剂A159、A160和A169,并分别采用浊度法和流式细胞仪测定了纸浆悬浮液中溶解和胶体物质(DCS)的含量。结果表明,在3种定着效果完全不同的阳离子定着剂作用下,通过浊度计测定,滤液的浊度与处理前相比都有大幅度的下降,但3种定着剂的作用效果无显著差异。而通过流式细胞仪测定,良好定着剂处理后,DCS的数量显著减少,但DCS的颗粒大小未发生变化;较差定着剂处理后,DCS的数量虽然也有大幅度的减少,但DCS颗粒却变大,胶体系统失稳并形成了絮凝沉淀。因此,定着剂对胶体系统的处理效果,可通过流式细胞仪的检测较好地表征出来。     

Micellar Properties of Surface Active Ionic Liquid Lauryl Isoquinolinium Bromide and Anionic Polyelectrolyte Poly(Acrylic Acid Sodium Salt) in Aqueous Solution

The complex formation between anionic polyelectrolyte poly(acrylic acid sodium salt) [NaPAA] and surface active ionic liquid (SAIL) lauryl isoquinolinium bromide [C₁₂iQuin][Br] in aqueous media has been investigated by surface tension, isothermal titration calorimetry (ITC), and conductance. The self‐assembled structures have been characterized using dynamic light scattering (DLS) and turbidity measurements. A range of surface parameters have been calculated from tensiometric measurements including critical micelle concentration (CMC), surface excess concentration (Γ_cmc), surface pressure at the interface (Π_cmc), minimum area occupied at air–solvent interface (A_min), adsorption efficiency (pC₂₀), and surface tension at the CMC (γ_cmc). The thermodynamic parameters, i.e., standard enthalpy of micellization , standard free energy of micellization (), and standard entropy of micellization () have also been evaluated. Four different stages of transitions, corresponding to the progressive formation of NaPAA–[C₁₂iQuin][Br] complex (C₁)_, critical aggregation concentration (CAC), critical saturation concentration (C₃) and CMC have been observed owing to strong electrostatic and hydrophobic interactions. The results obtained from DLS and turbidity measurements show that size of the aggregates first decreases and then increases in the presence of polyelectrolyte. The binding isotherms obtained using isothermal titration calorimetry (ITC) show the concentration dependence as well as the highly cooperative nature of interactions corresponding to formation of polyelectrolyte–SAIL complexes.     

Understanding the influence of suspended solids on water quality and aquatic biota

Over the last 50 years the effects of suspended solids (SS) on fish and aquatic life have been studied intensively throughout the world. It is now accepted that SS are an extremely important cause of water quality deterioration leading to aesthetic issues, higher costs of water treatment, a decline in the fisheries resource, and serious ecological degradation of aquatic environments. As such, government-led environmental bodies have set recommended water quality guidelines for concentrations of SS in freshwater systems. However, these reference values are often spurious or based on the concept of turbidity as a surrogate measure of the concentration of SS. The appropriateness of these recommended water quality values is evaluated given: (1) the large variability and uncertainty in data available from research describing the effects of SS on aquatic environments, (2) the diversity of environments that these values are expected to relate to, and (3) the range of conditions experienced within these environments. Furthermore, we suggest that reliance solely upon turbidity data as a surrogate for SS must be treated with caution, as turbidity readings respond to factors other than just concentrations of SS, as well as being influenced by the particle-size distribution and shape of SS particles. In addition, turbidity is a measure of only one of the many detrimental effects, reviewed in this paper, which high levels of SS can have in waterbodies. In order to improve the understanding of the effects of SS on aquatic organisms, this review suggests that: First, high-resolution turbidity monitoring should be supplemented with direct, measurements of SS (albeit at lower resolution due to resource issues). This would allow the turbidity record to be checked and calibrated against SS, effectively building a rating-relationship between SS and turbidity, which would in-turn provide a clearer picture of the exact magnitude of the SS problem. Second, SS should also be characterised in terms of their particle-size distribution and chemical composition. This would provide information to develop a more comprehensive understanding of the observed variable effects of a given concentration of SS in aquatic habitats. These two suggested improvements, combined with lower-resolution concurrent measures of aquatic ecological status, would improve our understanding of the effects of SS in aquatic environments and together with a more detailed classification of aquatic environments, would provide an environment-specific evidence base for the establishment of effective water quality guidelines for SS.