Advanced Materials Research Vols. 518-523

Abstract: In this article, based on the principal-agent theory and introducing an auxiliary observing variable sets up an optimal model of principal-agent relationship between the waste military air materials reverse logistics demand side and the logistics service provider，and analyzes the principal-agent problems in the waste military air materials reverse logistics such as moral hazard and incentive monitoring mechanism designing owing to the asymmetric information．Furthermore，the papers analyzes the agent costs of outsourcer and incentive intensity coefficient of provider and points out that the designing of incentive monitoring mechanism for provider must reflect the influences of provider specialty the change of external environment and the agent costs of the waste military air materials reverse logistics demand side.

Abstract: Study on groundwater baseline quality is very important for groundwater management, as managers want to know the magnitude and reason for the elevated content (whether the elevated content is geological or anthropogenic in origin). As the baseline is defined as the range of concentration of a give element is derived entirely from natural sources under condition not perturbed by anthropogenic activity, it can be obtained from the palaeowaters. Based on the published data in the Minqin Basin, NW China, the groundwater baseline quality is determined. This will be one of the first groundwater baseline quality studies in China. Results show that the relatively high total mineral content in the basin is related to arid condition and low groundwater flow velocity and that the most groundwater quality has not been affected by human activities.

Abstract: The groundwater recharge environments and hydrogeochemical characteristics in Beijing were investigated using a combination of chemical indicators, stable isotopes, and radiocarbon dating. There are two distinct zones for those groundwaters: modern water (1000 a) are depleted, which implies that the palaeowaters were recharged in relatively cold climate. The TDS for all groundwater samples range from 312 to 914 mg/L. Groundwaters are supersaturated with respect to calcite and the δ13C value is stable (around -13‰), which suggests dissolution of calcite is limited. Dissolution of halite, sulfate and carbonate and exchange of cations are main processes of water chemistry. The results have important implications for groundwater management in Beijing, where a certain proportion of the unrenewable water has been mined.

Abstract: Use the flood years (1998、2010) the data of the hydrologic information and disaster information, comparative analysis the impact on hydrologic information and disaster information in Dongting Lake area of the Three Gorges Reservoir flood prevention dispatching .The results show that: the inflow of lake into Jingjiang Sankou reduces about 242.61 × 108 m3,the flood level of Hukou Chenglingji lowers 0.82m, the daily average increasing rate of flood peak level slows 0.23m, the over-warning water level duration time reduces 62d; both have saved a great deal of flood control emergency rescue and disaster relief material consumption, manpower input, namely RMB 0.638 x 108yuan, and reduce the lake area flood damage 19.983 x 108yuan; in the process of 5 times flood prevention dispatching of the Three Gorges Reservoir, three times in July to alleviate flood control operation regime, disaster in Dongting Lake area the contribution of the largest, flood control operation effect is not very sensitive in June, and the impound floodwater sums to 80.7×108m3, not only of the lake area is no sense of flood control, but also because the flood retention of reservoir is more, the water of Sankou into the lake is greatly reduced, and Hunan sishui has begun to enter withered period, total amount into the lake gradually reduce, make the Dongting Lake water into withered period early; the ability of the Three Gorges Reservoir flood prevention dispatching operation to the flood prevention function is very limited, from the overall and long-term ways ,to enhance their ability of flood prevention and disaster alleviation of Dongting Lake area is still an important and comprehensive affairs.

Abstract: For the problems of unsteady water quality change caused by complicated flow in a plain river network a nonlinear flow calculation model is applied to adapt different hydrological conditions, and flow adjustment factor is introduced to water quality calculation model based on the upwind difference schema. The flow adjustment factor forms are given with different flow direction in a river. The parameters of the water quality calculation model are calibrated and validated by observed data in the study area. The results show that the improved water quality calculation model has high simulation accuracy and reliability. Aiming at the serious water pollution in the local area of the plain river network, four combination schemes on water diversion and reduction of pollution load are calculated, and the water quality improvement effect analyzed. The practice provides a feasible calculation way for unsteady water quality change in the plain river network and scientific decision making for the local government.

Abstract: The slope roughness is a character parameter which shows the blocking effects of earth surface on the overland flow. As a result of the impact of human activities, the land utilization types spatially change rapidly. Consequently, the catchment surface appears as broken patches pattern so that the spatial variation of surface roughness increased. And this leads to change on the runoff flow convergence velocity, the flow direction and the flow assignment in each direction. The accurately runoff simulation is not available when the roughness effect is neglected. Therefore, study on slope roughness effects become important in human activities impacted hydrological research. Based on former researches, we divided the slope roughness research into three levels, and discussed the inappropriate points of the slope runoff flow convergence algorithm, which adopted by the current distributed hydrological model, when dealing with the slope roughness on the human activities impacted catchment. Moreover, we presented that in order to obtain an effective result of simulating overland runoff. The distributed hydrological model should take the spatial variation effect of the slope roughness factor into consideration and formulation.

Abstract: We designed a set of water saving system for college dorms based on the current college water use status. This system mainly included a water collection tank and the enclosed sanitary-wares. We designed the subsidence area on one side of the water collection tank so it’s easy to clean the sludge and the allocation of water-saving effect demonstration system. There are no devices in the water collection tank for eliminating the peculiar smell of wastewater, heterochromatic carbon absorber and ozone generator. In order to ensure the smooth implementation of the system, in view that the peculiar smell and different color of the wastewater affecting users mood, in order to reduce the users conflicted emotion, according to the shortage of current toilet sanitary-wares,we designed an enclosed squats bedpan that using the user’s gravity to expansion and it will be closed automatic when users left. We also designed an enclosed toilet that using the user’s gravity to expansion and it will be closed automatic when users left. And we designed an enclosed urinal that using the user’s gravity to expansion and it will be closed automatic when users left. And according to the lower pressure situation of the upper water collection tank, the special structure of the squats bedpan and toilet in this project don't need a large scouring force, rejected the “siphon principle” that widely used in the traditional design scheme, reduce the required water, improve water saving effect.

Abstract: The reservoir real-time operation is a cyclic process of forcast-decision making-implementation, in which the key issue is to confirm discharges quickly and exactly. In order to solve this issue, a reservoir real-time optimization operation model based on Particle Swarm Optimization (PSO) is proposed and the real-time operation procedure is illustrated in this paper. Taking the flood hydrograph 19750729 of Huanren reservoir as an example, discharges calculated by the real-time optimization operation model are compared with those calculated by conventional operation. It could be seen that the running speed of the real-time optimization operation model is quickly, discharges are uniform and reduced under the safety of dam, and the benefit is improved. Therefore, this model is reasonable and feasible.

Abstract: Based on batch settling tests, a model describing the compression settling stage was developed and validated by experimental data. A equation determining the critical point when the compression settling stage commences, and a new velocity function for compression settling process were deduced from the model. It was shown that compression settling velocity, time and sludge concentration of the critical point occurrence depend on the initial sludge concentrations, the initial sludge blanket height and the sludge characteristic. Dividing the entire settling process of activated sludge into the zone settling and compression settling stages, and describing them by respective velocity models was more reasonable for characterizing the entire settling behaviour of activated sludge. The method was applied to predict the sludge blanket height during batch settling tests, and the results showed that the settling processes could be simulated well.

Abstract: Flocs size is an important parameter in the blanket clarifier process, hence, it is necessary to investigate flocs average diameter in different blanket height to achieve optimum operation parameters of the process. To investigate the flocs size under different operational conditions，flocs were sampled from different locations of the blanket in various operating stages to analyze its size. Experimental works with water plant wastes flocculated with polyacrylamide (PAM) suspended in a pilot-scale blanket confirmed the theoretical predictions. Change in operational conditions such as raw water concentration and up-flow rate would affect the blanket flocs size, there exists a linear relationship between up-flow rate and flocs average size, and flocs size were improved along with the increase of raw sludge concentration. The experimental results identified an inverse proportion between flocs average size and the blanket depth, the average flocs diameter increased along with the depth of the blanket.