There are a number of serious problems connected with building and repairing water-reining elements in embankment dams in cold regions. One of them is the difficulty in finding inexpensive clay materials with the nece...There are a number of serious problems connected with building and repairing water-reining elements in embankment dams in cold regions. One of them is the difficulty in finding inexpensive clay materials with the necessary structural properties and using them in the winter. Another is the cracks that appear in the upper part of a dam when the core freezes to the banks, and leakage along the cracks threatens to desWoy the dam. Still another is the process of erosion at the bottom of the core which may occur through fissures in the rock foundation of a dam and in transport constructions. Also, the behaviour of water-retaining elements during eazthquakes is unreliable. All of these problems can be solved by using iceand cryogel-soil composites created by cryotropic gel formation （CGF）. Our laboratory investigations demonstrate that the materials proposed for water-retaining elements have the necessary permeable, plastic, thermophysical, and slrength properties to solve all of these problems. Certain consmactious of water-retaining elements which may prove to be both safe and cost-effective are proposed. However, these iceand cryogel-soil composites need to be field-validated before they are used in dams and transport structures in cold regions.展开更多
Water hammer phenomenon involves the transformation of kinetic energy in pressure energy, this transformation occurs as the fluid conditions change inside the pipe in quite a short time. Industry requires to affront f...Water hammer phenomenon involves the transformation of kinetic energy in pressure energy, this transformation occurs as the fluid conditions change inside the pipe in quite a short time. Industry requires to affront frequent flow interruptions in pipe systems due to the closing of valves or stopping of pumping equipment. This phenomenon can initiate serious damages like destruction of the pipe system involving leakage of the working fluid to the environment. If the system operates in a fragile environment, as in cold regions, concern about the consequences of leakage increases due to the variation of physical properties of fluid as well as the pipe material as a function of the temperature. Water hammer effects can be controlled focusing efforts on reducing the pressure increment that takes place once the phenomenon is presented. Some methods try to reduce the time of closure or the rate of change before the closure using special valves, others install additional elements to absorb the pressure surge and dissipate energy, others install relief valves to release the pressure, and others try to split the problem is smaller sections by installing check valves with dashpot or non-return valves. Splitting the pipeline into shorter sections is often used to help preventing the pipeline length of water falling back after a pump stops. In this paper the numerical results of maximum and minimum pressure values at both ends of a closed section are compared to experimental data. The numerical results follow the experimental trends.展开更多
In view of the tendency of global climatic warming, the water balance model is employed to estimate the runoff changes in the Urumqi River Basin, Xinjiang Region, China, under ten climate change scenarios, which are c...In view of the tendency of global climatic warming, the water balance model is employed to estimate the runoff changes in the Urumqi River Basin, Xinjiang Region, China, under ten climate change scenarios, which are combinations of temperature increases by 2K and 4K with precipitation change of 0, ±10% and ±20%, respectively, as the atmospheric concentration of carbon dioxide increases. The results suggest that runoff changes mainly depend on the precipitation change in the glacier-free or less glacierized basins in cold alpine regions. Effect of temperature on runoff becomes marked gradually with the increase in precipitation. Runoff from glacierized areas, however, is much more sensitive to the temperature change.展开更多
为探究孕穗期冷水灌溉下粳稻籽粒灌浆过程中的干物质、氮素形成积累规律及氮代谢关键酶调控效应，以东农428和松粳10为材料，设置6个冷水灌溉持续时间（0、3、6、9、12和15 d），分析孕穗期冷水灌溉对寒地粳稻籽粒灌浆过程中的干物质、...为探究孕穗期冷水灌溉下粳稻籽粒灌浆过程中的干物质、氮素形成积累规律及氮代谢关键酶调控效应，以东农428和松粳10为材料，设置6个冷水灌溉持续时间（0、3、6、9、12和15 d），分析孕穗期冷水灌溉对寒地粳稻籽粒灌浆过程中的干物质、氮素积累及氮代谢关键酶活性的影响。结果表明，与对照相比，孕穗期冷水灌溉下，寒地粳稻产量及籽粒干物质积累量的变化规律一致，冷水灌溉持续时间越长，产量及籽粒干物质积累量降幅越大。冷水灌溉下，寒地粳稻籽粒干物质积累量降低，除与籽粒干物质最大相对积累速率降低有关外，还与结实率降低、有效穗数和每穗总粒数减少有关。冷水灌溉可提高寒地粳稻籽粒全氮、蛋白氮、成熟期籽粒粗蛋白含量及灌浆前期籽粒谷氨酰胺合成酶（GS）活性。冷水灌溉6 d 可显著提高籽粒谷草转氨酶（GOT）及谷丙转氨酶（GPT）活性，冷水灌溉9~15 d 可显著降低其活性。短期冷水灌溉下（3~6 d），寒地粳稻通过增强有机氮同化过程，促进蛋白质合成，使籽粒氮素含量增加；长期冷水灌溉下（9~15 d），籽粒有机氮同化过程受到抑制，影响氨基酸和蛋白质的合成，最终导致籽粒氮素增幅下降。籽粒全氮、蛋白氮和淀粉颗粒态结合蛋白是不同耐冷性品种响应冷水胁迫的差异产物，其含量可作为耐冷性鉴定的指标。展开更多
文摘There are a number of serious problems connected with building and repairing water-reining elements in embankment dams in cold regions. One of them is the difficulty in finding inexpensive clay materials with the necessary structural properties and using them in the winter. Another is the cracks that appear in the upper part of a dam when the core freezes to the banks, and leakage along the cracks threatens to desWoy the dam. Still another is the process of erosion at the bottom of the core which may occur through fissures in the rock foundation of a dam and in transport constructions. Also, the behaviour of water-retaining elements during eazthquakes is unreliable. All of these problems can be solved by using iceand cryogel-soil composites created by cryotropic gel formation （CGF）. Our laboratory investigations demonstrate that the materials proposed for water-retaining elements have the necessary permeable, plastic, thermophysical, and slrength properties to solve all of these problems. Certain consmactious of water-retaining elements which may prove to be both safe and cost-effective are proposed. However, these iceand cryogel-soil composites need to be field-validated before they are used in dams and transport structures in cold regions.
文摘Water hammer phenomenon involves the transformation of kinetic energy in pressure energy, this transformation occurs as the fluid conditions change inside the pipe in quite a short time. Industry requires to affront frequent flow interruptions in pipe systems due to the closing of valves or stopping of pumping equipment. This phenomenon can initiate serious damages like destruction of the pipe system involving leakage of the working fluid to the environment. If the system operates in a fragile environment, as in cold regions, concern about the consequences of leakage increases due to the variation of physical properties of fluid as well as the pipe material as a function of the temperature. Water hammer effects can be controlled focusing efforts on reducing the pressure increment that takes place once the phenomenon is presented. Some methods try to reduce the time of closure or the rate of change before the closure using special valves, others install additional elements to absorb the pressure surge and dissipate energy, others install relief valves to release the pressure, and others try to split the problem is smaller sections by installing check valves with dashpot or non-return valves. Splitting the pipeline into shorter sections is often used to help preventing the pipeline length of water falling back after a pump stops. In this paper the numerical results of maximum and minimum pressure values at both ends of a closed section are compared to experimental data. The numerical results follow the experimental trends.
基金Part of the project supported by the National Natural Science Foundation of China, No. 9488007.
文摘In view of the tendency of global climatic warming, the water balance model is employed to estimate the runoff changes in the Urumqi River Basin, Xinjiang Region, China, under ten climate change scenarios, which are combinations of temperature increases by 2K and 4K with precipitation change of 0, ±10% and ±20%, respectively, as the atmospheric concentration of carbon dioxide increases. The results suggest that runoff changes mainly depend on the precipitation change in the glacier-free or less glacierized basins in cold alpine regions. Effect of temperature on runoff becomes marked gradually with the increase in precipitation. Runoff from glacierized areas, however, is much more sensitive to the temperature change.
文摘为探究孕穗期冷水灌溉下粳稻籽粒灌浆过程中的干物质、氮素形成积累规律及氮代谢关键酶调控效应，以东农428和松粳10为材料，设置6个冷水灌溉持续时间（0、3、6、9、12和15 d），分析孕穗期冷水灌溉对寒地粳稻籽粒灌浆过程中的干物质、氮素积累及氮代谢关键酶活性的影响。结果表明，与对照相比，孕穗期冷水灌溉下，寒地粳稻产量及籽粒干物质积累量的变化规律一致，冷水灌溉持续时间越长，产量及籽粒干物质积累量降幅越大。冷水灌溉下，寒地粳稻籽粒干物质积累量降低，除与籽粒干物质最大相对积累速率降低有关外，还与结实率降低、有效穗数和每穗总粒数减少有关。冷水灌溉可提高寒地粳稻籽粒全氮、蛋白氮、成熟期籽粒粗蛋白含量及灌浆前期籽粒谷氨酰胺合成酶（GS）活性。冷水灌溉6 d 可显著提高籽粒谷草转氨酶（GOT）及谷丙转氨酶（GPT）活性，冷水灌溉9~15 d 可显著降低其活性。短期冷水灌溉下（3~6 d），寒地粳稻通过增强有机氮同化过程，促进蛋白质合成，使籽粒氮素含量增加；长期冷水灌溉下（9~15 d），籽粒有机氮同化过程受到抑制，影响氨基酸和蛋白质的合成，最终导致籽粒氮素增幅下降。籽粒全氮、蛋白氮和淀粉颗粒态结合蛋白是不同耐冷性品种响应冷水胁迫的差异产物，其含量可作为耐冷性鉴定的指标。
