The medium-term runoff forecasting provided new information for forecast of medium and long term runoff and optimal hydroelectric power generation.According to the actual runoff and hydropower generating characteristi...The medium-term runoff forecasting provided new information for forecast of medium and long term runoff and optimal hydroelectric power generation.According to the actual runoff and hydropower generating characteristics of Ertan Hydropower Station,we studied the decade runoff quantitatively and grade forecast model based on Global Forecasting System(GFS) precipitation forecast information in wet season,then used the posteriori runoff transition probability and measurable probability of runoff forecast to research the uncertain runoff description based on runoff forecast;finally on the basis of the runoff description and the grading forecast accuracy of GFS-based next 10 days'total forecast precipitation,we studied the uncertain optimal operating model of Ertan Hydropower Station considering runoff forecast.The results showed that the runoff forecast considering GFS forecast precipitation and uncertainty has significantly improved the existing runoff description and operating optimization model,and obviously raised the hydropower generation efficiency of Ertan Reservoir.展开更多
Taking the flood resources utilization in Baicheng, Jilin during 2002–2007 as the research background, and based on the entropy weight and multi-level & multi-objective fuzzy optimization theory, this research es...Taking the flood resources utilization in Baicheng, Jilin during 2002–2007 as the research background, and based on the entropy weight and multi-level & multi-objective fuzzy optimization theory, this research established a multi-level & semi-constructive index system and dynamic successive evaluation model for comprehensive benefit evaluation of regional flood resources utilization. With the year 2002 as the base year, the analyzing results showed that there existed a close positive correlation between flood utilization volume and its benefits, comprehensive evaluation value and its comparison increment. Within the six successive evaluation years, the comprehensive benefit of 2003 was the best, in which the benefit evaluation increment reached 82.8% whereas the year of 2004 was the worst, in which the increment was only 18.2%. Thus the sustainability and correctness of the evaluation were verified by six years successive evaluation and increment comparison. The analyzing results showed that the economic benefits, ecological benefits and social benefits of flood utilization were remarkable, and that the comprehensive benefit could be improved by increasing flood utilization capacity, which would promote the regional sustainable development as well. The established dynamic successive evaluation provides a stable theoretical basis and technical support for further flood utilization.展开更多
Based on the existing Land Surface Physical Process Models(Deardorff, Dickinson, LIU, Noilhan, Seller, ZHAO), a Comprehensive Land Surface Physical Process Model (CLSPPM) is developed by considering the different phys...Based on the existing Land Surface Physical Process Models(Deardorff, Dickinson, LIU, Noilhan, Seller, ZHAO), a Comprehensive Land Surface Physical Process Model (CLSPPM) is developed by considering the different physical processes of the earth's surface-vegetation-atmosphere system more completely. Compared with SiB and BATS, which are famous for their detailed parameterizations of physical variables, this simplified model is more convenient and saves much more computation time. Though simple, the feas...展开更多
Human history begins with stories. These stories were so important that they were memorized and passed down for countless generations.Storytelling is an ancient and powerful tool. The ability to 1)process, remember an...Human history begins with stories. These stories were so important that they were memorized and passed down for countless generations.Storytelling is an ancient and powerful tool. The ability to 1)process, remember and communicate stories is man’s oldest and best trick.展开更多
Based on conventional static line rating method, the actual current carrying capability of overhead conductors cannot be judged. Due to continuous increment in electricity demand and the difficulties associated with n...Based on conventional static line rating method, the actual current carrying capability of overhead conductors cannot be judged. Due to continuous increment in electricity demand and the difficulties associated with new line constructions, the overhead lines are therefore required to be rated based on a method that should establish their real-time capability in terms of electricity transmission. The method used to determine the real-time ampacity of overhead conductors not only can enhance their transmission capacity but can also help in allowing excessive renewable generation in the electricity network. In this research work, the issues related to analyzing an impact of wind power on periodical loading of overhead line as well as finding its static and dynamic ampacities with line current are investigated in detail. Moreover, the investigation related to finding a suitable location for the construction of a 60 MW wind farm is taken on board. Thereafter, the wind park is integrated with a regional grid, owned by Fortum Distribution AB. In addition to that, the electricity generated from the wind park is also calculated in this project. Later on, the work is devoted to finding the static and dynamic line ratings for “VL3” overhead conductor by using IEEE-738-2006 standard. Furthermore, the project also deals with finding the line current and making its comparison with maximum capacity of overhead conductor (VL3) for loading it in such a way that no any violation of safe ground clearance requirements is observed at all. Besides, the line current, knowing the conductor temperature when it transmits the required electricity in the presence of wind power generation is also an important factor to be taken into consideration. Therefore, based on real-time ambient conditions with actual line loading and with the help of IEEE-738-2006 standard, the conductor temperature is also calculated in this project. At the end, an economic analysis is performed to evaluate the financial advantages related to applying the dynamic展开更多
The paper presents a detailed account of the status quo and potential hazards of geological environmental disasters (GED) in Qinghai Province as well as a systematic analysis of the formation and evolution of GED ...The paper presents a detailed account of the status quo and potential hazards of geological environmental disasters (GED) in Qinghai Province as well as a systematic analysis of the formation and evolution of GED and of the threat and loss caused to the life and property of the local people. Recommendations on how to take effective measures to prevent and control the GED in Qinghai are provided.展开更多
BACKGROUND: Veterans Affairs (VA) Cooperative Study 380 showed that some advan ced colorectal neoplasias (i.e., adenomas at least 1 cm in diameter, villous ade nomas, adenomas with highgrade dysplasia, or cancer) in...BACKGROUND: Veterans Affairs (VA) Cooperative Study 380 showed that some advan ced colorectal neoplasias (i.e., adenomas at least 1 cm in diameter, villous ade nomas, adenomas with highgrade dysplasia, or cancer) in men would be missed wi th the use of flexible sigmoidoscopy but detected by colonoscopy. In a tandem st udy, we examined the yield of screening colonoscopy in women. METHODS: To determ ine the prevalence and location of advanced neoplasia, we offered colonoscopy to consecutive asymptomatic women referred for coloncancer screening. The diagno stic yield of flexible sigmoidoscopy was calculated by estimating the proportion of patients with advanced neoplasia whose lesions would have been identified if they had undergone flexible sigmoidoscopy alone. Lesions were considered detect able by flexible sigmoidoscopy if they were in the distal colon or if they were in the proximal colon in patients who had concurrent small adenomas in the dista l colon, a finding that would have led to colonoscopy. The results were compared with the results from VA Cooperative Study 380 for agematched men and women wit h negative fecal occultblood tests and no family history of colon cancer. RESU LTS: Colonoscopy was complete in 1463 women, 230 of whom (15.7 percent) had a fa mily history of colon cancer. Colonoscopy revealed advanced neoplasia in 72 wome n (4.9 percent). If flexible sigmoidoscopy alone had been performed, advanced ne oplasia would have been detected in 1.7 percent of these women (25 of 1463) and missed in 3.2 percent (47 of 1463). Only 35.2 percent ofwomen with advanced neop lasia would have had their lesions identified if they had undergone flexible sig moidoscopy alone, as compared with 66.3 percent of matched men from VA Cooperati ve Study 380 (P< 0.001). CON CLUSIONS: Colonoscopy may be the preferred method of screening for colorectal cancer in women.展开更多
Due to the complexity of metal AM （additive manufacturing）, it can require many trial runs to obtain processing parameters which produce a quality build. Because of this trial and error process, the drive for simula...Due to the complexity of metal AM （additive manufacturing）, it can require many trial runs to obtain processing parameters which produce a quality build. Because of this trial and error process, the drive for simulations of AM has grown significantly. A simulation only becomes useful to researchers if it can be shown that it is a true representation of the physical process being simulated. Each process being simulated has a different method of validation to show it is an accurate representation of the process. This paper explores the various methodologies for validation of laser-based metal AM simulations, focusing mainly on the modeling of the thermal processes and other characteristics derived from the thermal history. It will identify and explain the various validation techniques used, specifically looking at the frequency of reported use of each technique.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.50579095,51079015)
文摘The medium-term runoff forecasting provided new information for forecast of medium and long term runoff and optimal hydroelectric power generation.According to the actual runoff and hydropower generating characteristics of Ertan Hydropower Station,we studied the decade runoff quantitatively and grade forecast model based on Global Forecasting System(GFS) precipitation forecast information in wet season,then used the posteriori runoff transition probability and measurable probability of runoff forecast to research the uncertain runoff description based on runoff forecast;finally on the basis of the runoff description and the grading forecast accuracy of GFS-based next 10 days'total forecast precipitation,we studied the uncertain optimal operating model of Ertan Hydropower Station considering runoff forecast.The results showed that the runoff forecast considering GFS forecast precipitation and uncertainty has significantly improved the existing runoff description and operating optimization model,and obviously raised the hydropower generation efficiency of Ertan Reservoir.
基金supported by the National Natural Science Foundation of China (Grant No. 50679012)National Key Technologies Research and Development Program of China (Grant No. 2006BAB14B05)
文摘Taking the flood resources utilization in Baicheng, Jilin during 2002–2007 as the research background, and based on the entropy weight and multi-level & multi-objective fuzzy optimization theory, this research established a multi-level & semi-constructive index system and dynamic successive evaluation model for comprehensive benefit evaluation of regional flood resources utilization. With the year 2002 as the base year, the analyzing results showed that there existed a close positive correlation between flood utilization volume and its benefits, comprehensive evaluation value and its comparison increment. Within the six successive evaluation years, the comprehensive benefit of 2003 was the best, in which the benefit evaluation increment reached 82.8% whereas the year of 2004 was the worst, in which the increment was only 18.2%. Thus the sustainability and correctness of the evaluation were verified by six years successive evaluation and increment comparison. The analyzing results showed that the economic benefits, ecological benefits and social benefits of flood utilization were remarkable, and that the comprehensive benefit could be improved by increasing flood utilization capacity, which would promote the regional sustainable development as well. The established dynamic successive evaluation provides a stable theoretical basis and technical support for further flood utilization.
基金National Natural Science Foundation of China (No. 40275004)State Key Laboratory of Atmosphere Physics and Chemistry
文摘Based on the existing Land Surface Physical Process Models(Deardorff, Dickinson, LIU, Noilhan, Seller, ZHAO), a Comprehensive Land Surface Physical Process Model (CLSPPM) is developed by considering the different physical processes of the earth's surface-vegetation-atmosphere system more completely. Compared with SiB and BATS, which are famous for their detailed parameterizations of physical variables, this simplified model is more convenient and saves much more computation time. Though simple, the feas...
文摘Human history begins with stories. These stories were so important that they were memorized and passed down for countless generations.Storytelling is an ancient and powerful tool. The ability to 1)process, remember and communicate stories is man’s oldest and best trick.
文摘Based on conventional static line rating method, the actual current carrying capability of overhead conductors cannot be judged. Due to continuous increment in electricity demand and the difficulties associated with new line constructions, the overhead lines are therefore required to be rated based on a method that should establish their real-time capability in terms of electricity transmission. The method used to determine the real-time ampacity of overhead conductors not only can enhance their transmission capacity but can also help in allowing excessive renewable generation in the electricity network. In this research work, the issues related to analyzing an impact of wind power on periodical loading of overhead line as well as finding its static and dynamic ampacities with line current are investigated in detail. Moreover, the investigation related to finding a suitable location for the construction of a 60 MW wind farm is taken on board. Thereafter, the wind park is integrated with a regional grid, owned by Fortum Distribution AB. In addition to that, the electricity generated from the wind park is also calculated in this project. Later on, the work is devoted to finding the static and dynamic line ratings for “VL3” overhead conductor by using IEEE-738-2006 standard. Furthermore, the project also deals with finding the line current and making its comparison with maximum capacity of overhead conductor (VL3) for loading it in such a way that no any violation of safe ground clearance requirements is observed at all. Besides, the line current, knowing the conductor temperature when it transmits the required electricity in the presence of wind power generation is also an important factor to be taken into consideration. Therefore, based on real-time ambient conditions with actual line loading and with the help of IEEE-738-2006 standard, the conductor temperature is also calculated in this project. At the end, an economic analysis is performed to evaluate the financial advantages related to applying the dynamic
文摘The paper presents a detailed account of the status quo and potential hazards of geological environmental disasters (GED) in Qinghai Province as well as a systematic analysis of the formation and evolution of GED and of the threat and loss caused to the life and property of the local people. Recommendations on how to take effective measures to prevent and control the GED in Qinghai are provided.
文摘BACKGROUND: Veterans Affairs (VA) Cooperative Study 380 showed that some advan ced colorectal neoplasias (i.e., adenomas at least 1 cm in diameter, villous ade nomas, adenomas with highgrade dysplasia, or cancer) in men would be missed wi th the use of flexible sigmoidoscopy but detected by colonoscopy. In a tandem st udy, we examined the yield of screening colonoscopy in women. METHODS: To determ ine the prevalence and location of advanced neoplasia, we offered colonoscopy to consecutive asymptomatic women referred for coloncancer screening. The diagno stic yield of flexible sigmoidoscopy was calculated by estimating the proportion of patients with advanced neoplasia whose lesions would have been identified if they had undergone flexible sigmoidoscopy alone. Lesions were considered detect able by flexible sigmoidoscopy if they were in the distal colon or if they were in the proximal colon in patients who had concurrent small adenomas in the dista l colon, a finding that would have led to colonoscopy. The results were compared with the results from VA Cooperative Study 380 for agematched men and women wit h negative fecal occultblood tests and no family history of colon cancer. RESU LTS: Colonoscopy was complete in 1463 women, 230 of whom (15.7 percent) had a fa mily history of colon cancer. Colonoscopy revealed advanced neoplasia in 72 wome n (4.9 percent). If flexible sigmoidoscopy alone had been performed, advanced ne oplasia would have been detected in 1.7 percent of these women (25 of 1463) and missed in 3.2 percent (47 of 1463). Only 35.2 percent ofwomen with advanced neop lasia would have had their lesions identified if they had undergone flexible sig moidoscopy alone, as compared with 66.3 percent of matched men from VA Cooperati ve Study 380 (P< 0.001). CON CLUSIONS: Colonoscopy may be the preferred method of screening for colorectal cancer in women.
文摘Due to the complexity of metal AM （additive manufacturing）, it can require many trial runs to obtain processing parameters which produce a quality build. Because of this trial and error process, the drive for simulations of AM has grown significantly. A simulation only becomes useful to researchers if it can be shown that it is a true representation of the physical process being simulated. Each process being simulated has a different method of validation to show it is an accurate representation of the process. This paper explores the various methodologies for validation of laser-based metal AM simulations, focusing mainly on the modeling of the thermal processes and other characteristics derived from the thermal history. It will identify and explain the various validation techniques used, specifically looking at the frequency of reported use of each technique.
