Papers by Author: Jun Yan

Abstract: Chose high-chromium cast iron as the material to make the mud pump shell, the composition of high-chromium alloy has been optimized and five kinds of alloy ( A, B, C, D and E) are designed. Furthermore, using the heat treatment method of air-cooled quenching of 1040°C + 260°C tempering, the relationship among material hardness, the impact toughness and the heating temperature is analyzed after heat treatment. Finally, the abrasion performance of wear-resistant materials is tested. The test result shows that all kinds of wear-resistant materials display well anti-abrasion performance, where the material E has the best relative wear resistance and 19.3% higher than the imported pump casing material. The results provide a scientific standard for selecting the practical wear-resistant materials and locating the piece casting bivalve pump of Cr26 high-chromium cast iron.

Abstract: in the River, velocities of surface water flow typically are larger than the near-bottom flow. Combined with background of artificial disturbance sediment, surface water flows is taken to the river bottom to loose and raise sediment, dredge and so as to achieve the purpose of slowing river siltation. Preliminary tests showed that using low-power diversion disturbing sand dredging system, flow velocity of disturbing nozzle is larger than the incipient velocity of sediment, and the purpose of disturbing sediment and sediment transport can be obtained.

Abstract: Pipe drainage system is used mostly on urban area, but under the pressure of the rapid urbanization, the disadvantages of traditional pipe drainage system are more and more serious. Analyzed the urban rain flood utilization situation in China and foreign countries, and main problems of traditional pipe drainage system in China, the key technology of comprehensive utilization for urban rain flood is put forward, which contains the multi-function tunnel building based on the concave green fields constructing, permeable bricks laying, reservoir constructing for rain flood collecting. This method can effectively prevent the drought or flood disaster due to inadequate or extensive rain volume and can make full use of rain flood resources too.

Abstract: Urban Rain-Flood disasters become more ordinary and serious recently under global warming and unreasonable exploitation. Summed up the characters of urban rain-floods, the mechanism of urban rain-flood disasters is analyzed. More ever, the main countermeasures to utilize urban rain-flood based on Nano technology comprehensively and effectively are put forward.

Abstract: With the development of the economy, human activities have more and more effects on natural environment. The large water conservancy and hydropower projects caused great multi-aspect influences on the environmental changes. The unreasonable activities of mankind in water resources exploitation have deteriorated the natural environment, intensifying the conflicts between human beings and the nature. Environment and natural disasters have brought forward rigorous challenge on the survival and development of the mankind. The concept of environmental variation is proposed in analyzing the processes of environmental change, and the reparation methods for the river environment variation have been stated as well. Styles of river environmental variation can be classified according to characteristics of the river and of human activities. The characteristics and the consequences of the environmental variation in the estuary of Yellow River are analyzed, so have the reparation methods. With the development of the economy, the human activities have more and more effects on natural environment. The large Water Conservancy and Hydropower Projects, such as the big-dam-building on the river, the water-transferring project, the water resources-exploiting project, and the sewage-discharge project, etc., have caused great multi-aspect influences on the environmental changes. The unreasonable activities of mankind in water resources exploitation have deteriorated the natural environment, intensifying the conflicts between the human beings and the nature. Environment and natural disasters have brought forward rigorous challenge on the survival and development of the mankind. Some abnormal environmental changes (Environment Variation) can be observed in rivers, influencing our life greatly, especially the environmental variation in the mouth of Yellow River.

Abstract: Analyzed the sediment-transport process in high sediment-laden river, the new concept and calculating method for sediment-transport water volume are proposed. Based on field data of sediment and water volume in the Lower Yellow River from 1950 to 2000, the sediment-transport water volume and unit sediment-transport water volume in LYR are calculated. Meanwhile, relations between them and influencing factors are confirmed to calculate efficient sediment-transport water volume after construction of the Xiaolangdi reservoir. Results gained from these functions are consistent well with the facts of real water-sediment regulation in LYR.

Abstract: The urban rain-flood disaster occurs more ordinary and more serious recently. Summing up the characters of urban rain-floods, the mechanism of urban rain-flood disasters is analyzed. More ever, the main countermeasures to prevent urban rain-flood disasters are stated. Finally, the method to use urban rain-flood comprehensively based on nanotechnology is put forward.

Abstract: The acceleration of urbanization and global warming are making urban rain-flood disaster more ordinary and more serious recently. Summing up the characters of urban rain-floods, the mechanism of urban rain-flood disasters is analyzed. More ever, the main countermeasures to prevent urban rain-flood disasters are stated. Finally, the optimal method to utilize urban rain-flood comprehensively is put forward with the aid of artificial neural network.

Abstract: Analyzed the variation reasons and its influence factors of the Lower Yellow River (LYR), the characteristics of typical water environment abnormal variation caused by human activities and the natural influence factors are put forward. The concept of environmental abnormal variation has been proposed. Further more, the reparation methods for the environment abnormal variation in the Lower Yellow River are stated.

Abstract: Analyzed the sediment-transport process in the Lower Yellow river, the concept and normal calculating method for sediment-transport water volume are proposed. Based on field data of sediment and water volume in the Lower Yellow River from 1950 to 2000, the sediment-transport water volume and unit sediment-transport water volume in LYR are calculated. Furthermore, BP model is set up to calculate the high efficient sediment-transport water volume in the Lower Yellow River. Compared the results of BP model with normal calculating method, BP model is confirmed for calculating the high efficient sediment-transport water volume in the Lower Yellow river.