The likelihood of extreme heat occurrence is continuously increasing with global warming.Under high temperatures,humidity may exacerbate the heat impact on humanity.As atmospheric humidity depends on moisture availabi...The likelihood of extreme heat occurrence is continuously increasing with global warming.Under high temperatures,humidity may exacerbate the heat impact on humanity.As atmospheric humidity depends on moisture availability and is constrained by air temperature,it is important to project the changes in the distribution of atmospheric humidity conditional on air temperature as the climate continuously warms.Here,a non-crossing quantile smoothing spline is employed to build quantile regression models emulating conditional distributions of dew point(a measure of humidity)on local temperature evolving with escalating global mean surface temperature.By applying these models to 297 weather stations in seven regions in China,the study analyzes historical trends of humid-heat and dry-hot days,and projects their changes under global warming of 2.0℃ and 4.5℃.In response to global warming,rising trends of humid-heat extremes,while weakening trends of dry-hot extremes,are observed at most stations in Northeast China.Additionally,results indicate an increasing trend in dry-hot extremes at numerous stations across central China,but a rise in humid-heat extremes over Northwest China and coastal regions.These trends found in the current climate state are projected to intensify under 2.0℃ and 4.5℃ warming,possibly influenced by the heterogeneous variations in precipitation,soil moisture,and water vapor fluxes.Requiring much lower computational resources than coupled climate models,these quantile regression models can further project compound humidity and temperature extremes in response to different levels of global warming,potentially informing the risk management of compound humid-heat extremes on a local scale.展开更多
Active Contour Model or Snake model is an efficient method by which the users can extract the object contour of Region Of Interest （ROI）. In this paper, we present an improved method combining Hermite splines curve ...Active Contour Model or Snake model is an efficient method by which the users can extract the object contour of Region Of Interest （ROI）. In this paper, we present an improved method combining Hermite splines curve and Snake model that can be used as a tool for fast and intuitive contour extraction. We choose Hermite splines curve as a basic function of Snake contour curve and present its energy function. The optimization of energy minimization is performed hy Dynamic Programming technique. The validation results are presented, comparing the traditional Snake model and the HSCM, showing the similar performance of the latter. We can find that HSCM can overcome the non-convex constraints efficiently. Several medical images applications illustrate that Hermite Splines Contour Model （HSCM） is more efficient than traditional Snake model.展开更多
We evaluated the spatial and temporal patterns of forest fires in two fire seasons (March to June and September to November) from 1996 to 2010 in Jilin Province, China, using the Canadian Forest Fire Weather Index Sys...We evaluated the spatial and temporal patterns of forest fires in two fire seasons (March to June and September to November) from 1996 to 2010 in Jilin Province, China, using the Canadian Forest Fire Weather Index System. Fire data were obtained from the Provincial Fire Agency, and historical climate records of daily weather observations were collected from 36 weather stations in Jilin and its neighboring provinces. A linear regression model was used to analyze linear trends between climate and fire weather indices with time treated as an independent variable. Correlation analysis was used to detect correlations between fire frequency, areas burned, and fire weather indices. A thin-plate smooth spline model was used to interpolate the point data of 36 weather stations to generate a surface covering the whole province. Our analyses indicated fire frequency and areas burned were significantly correlated with fire weather indices. Overall, the Canadian Forest Fire Weather Index System appeared to be work well for determining the fire danger rating in Jilin Province. Also, our analyses indicated that in the forthcoming decades, the overall fire danger in March and April should decrease across the province, but the chance of a large fire in these months would increase. The fire danger in the fall fire season would increase in the future, and the chance of large fire would also increase. Historically, because most fires have occurred in the spring in Jilin Province, such a shift in the future fire danger between the two fire seasons would be beneficial for the province's fire management.展开更多
A three-component geomagnetic survey was carried out during the period from 2002 to 2004 in China including Jiujiang-Ruichang region. Comparing the ＂2005.0 surface spline model of China geomagnetic field＂ created on...A three-component geomagnetic survey was carried out during the period from 2002 to 2004 in China including Jiujiang-Ruichang region. Comparing the ＂2005.0 surface spline model of China geomagnetic field＂ created on the basis of the survey data with the ＂1970.0 surface spline model of China geomagnetic field＂, we can see an obvious abnormity in the geomagnetic horizontal component within a range of about 100 km around the epicenter of the Ms=5.7 Jiujiang-Ruichang earthquake occurred on November 26, 2005. After the earthquake, we carded out a repeated geomagnetic survey at 21 stations in the Jiujiang-Ruichang region and created a corresponding ＂2005.0 partially revised surface spline model of China geomagnetic field＂. By comparing the above three models, analyzing the geomagnetic horizontal component at the profile in the Jiujiang-Ruichang region and quantitatively studying the geomagnetic data of every stations around the Ms=5.7 earthquake, we have obtained the geomagnetic abnormity associated with this earthquake. Then the geomagnetic abnormity and its relation with seismic activity are discussed in this paper.展开更多
The objective of this study was to investigate the possibility of fitting spline regression models for power take-off(PTO)performance characteristics of an agricultural tractor tested with four different fuels,includi...The objective of this study was to investigate the possibility of fitting spline regression models for power take-off(PTO)performance characteristics of an agricultural tractor tested with four different fuels,including diesel fuel(B0)and three biodiesel blends made of canola oil(B10:10%biodiesel+90%petro-diesel blend;B20:20%biodiesel+90%petro-diesel blend;B30:30%biodiesel+90%petro-diesel blend).The performance characteristics evaluated were PTO power,engine torque,engine fuel consumption,and specific fuel consumption.Due to sharp slopes in measured quantities around the nominal engine speed(2200 r/min),compared to the standard regression method,the spline regression models suited well to the experimental data with coefficient of determination R2=0.99 for PTO power and engine torque.R2 varied between 0.97 and 0.99 for fuel consumption and 0.91 and 0.95 for specific fuel consumption.The weaker correlation found for specific fuel consumption could be attributed to profound fluctuations in measured data causing atypical pattern in the corresponding graphs around the nominal engine speed.It was concluded that splines were useful to accurately predict the measured PTO power and engine torque.Neither standard methods nor splines were sufficient to obtain very good regression models for specific fuel consumption.展开更多
This paper provides a survey of local refinable splines,including hierarchical B-splines,T-splines,polynomial splines over T-meshes,etc.,with a view to applications in geometric modeling and iso-geometric analysis.We ...This paper provides a survey of local refinable splines,including hierarchical B-splines,T-splines,polynomial splines over T-meshes,etc.,with a view to applications in geometric modeling and iso-geometric analysis.We will identify the strengths and weaknesses of these methods and also offer suggestions for their using in geometric modeling and iso-geometric analysis.展开更多
A 2-D depth averaged RNG k- ε model is developed to simulate the flow in a typical reach of the Upper Yellow River with non-monotonic banks. In order to take account of the effect of the secondary flow in a bend, the...A 2-D depth averaged RNG k- ε model is developed to simulate the flow in a typical reach of the Upper Yellow River with non-monotonic banks. In order to take account of the effect of the secondary flow in a bend, the momentum equations are modified by adding an additional source term. A comparison between the numerical simulation and the field measurements indicates that the improved 2-D depth averaged RNG k- ε model can improve the accuracy of the numerical simulation. An arc spline interpolation method is developed to interpolate the non-monotonic river banks. The method can also be reasonably applied for the 2-D interpolation of the river bed level. Through a comparison of the water surface gradients simulated in the seven bends of the studied reach, some analytical formulae are improved to reasonably calculate the longitudinal and transverse gradients in meandering river reaches. Furthermore, the positions of the maximum water depth and the maximum velocity in a typical bend are discussed.展开更多
基金supported by the National Natural Science Foundation of China[grant number 42175066]the Shanghai International Science and Technology Partnership Project[grant number 21230780200].
文摘The likelihood of extreme heat occurrence is continuously increasing with global warming.Under high temperatures,humidity may exacerbate the heat impact on humanity.As atmospheric humidity depends on moisture availability and is constrained by air temperature,it is important to project the changes in the distribution of atmospheric humidity conditional on air temperature as the climate continuously warms.Here,a non-crossing quantile smoothing spline is employed to build quantile regression models emulating conditional distributions of dew point(a measure of humidity)on local temperature evolving with escalating global mean surface temperature.By applying these models to 297 weather stations in seven regions in China,the study analyzes historical trends of humid-heat and dry-hot days,and projects their changes under global warming of 2.0℃ and 4.5℃.In response to global warming,rising trends of humid-heat extremes,while weakening trends of dry-hot extremes,are observed at most stations in Northeast China.Additionally,results indicate an increasing trend in dry-hot extremes at numerous stations across central China,but a rise in humid-heat extremes over Northwest China and coastal regions.These trends found in the current climate state are projected to intensify under 2.0℃ and 4.5℃ warming,possibly influenced by the heterogeneous variations in precipitation,soil moisture,and water vapor fluxes.Requiring much lower computational resources than coupled climate models,these quantile regression models can further project compound humidity and temperature extremes in response to different levels of global warming,potentially informing the risk management of compound humid-heat extremes on a local scale.
文摘Active Contour Model or Snake model is an efficient method by which the users can extract the object contour of Region Of Interest （ROI）. In this paper, we present an improved method combining Hermite splines curve and Snake model that can be used as a tool for fast and intuitive contour extraction. We choose Hermite splines curve as a basic function of Snake contour curve and present its energy function. The optimization of energy minimization is performed hy Dynamic Programming technique. The validation results are presented, comparing the traditional Snake model and the HSCM, showing the similar performance of the latter. We can find that HSCM can overcome the non-convex constraints efficiently. Several medical images applications illustrate that Hermite Splines Contour Model （HSCM） is more efficient than traditional Snake model.
基金financially supported by the National Natural Science Foundation of China(31470497)Project 2013-158,Jilin Provincial Education Department+1 种基金Project 2013-007,Jilin Provincial Forestry Departmentsupported by the Program for New Century Excellent Talents in the University(NCET-12-0726)
文摘We evaluated the spatial and temporal patterns of forest fires in two fire seasons (March to June and September to November) from 1996 to 2010 in Jilin Province, China, using the Canadian Forest Fire Weather Index System. Fire data were obtained from the Provincial Fire Agency, and historical climate records of daily weather observations were collected from 36 weather stations in Jilin and its neighboring provinces. A linear regression model was used to analyze linear trends between climate and fire weather indices with time treated as an independent variable. Correlation analysis was used to detect correlations between fire frequency, areas burned, and fire weather indices. A thin-plate smooth spline model was used to interpolate the point data of 36 weather stations to generate a surface covering the whole province. Our analyses indicated fire frequency and areas burned were significantly correlated with fire weather indices. Overall, the Canadian Forest Fire Weather Index System appeared to be work well for determining the fire danger rating in Jilin Province. Also, our analyses indicated that in the forthcoming decades, the overall fire danger in March and April should decrease across the province, but the chance of a large fire in these months would increase. The fire danger in the fall fire season would increase in the future, and the chance of large fire would also increase. Historically, because most fires have occurred in the spring in Jilin Province, such a shift in the future fire danger between the two fire seasons would be beneficial for the province's fire management.
文摘A three-component geomagnetic survey was carried out during the period from 2002 to 2004 in China including Jiujiang-Ruichang region. Comparing the ＂2005.0 surface spline model of China geomagnetic field＂ created on the basis of the survey data with the ＂1970.0 surface spline model of China geomagnetic field＂, we can see an obvious abnormity in the geomagnetic horizontal component within a range of about 100 km around the epicenter of the Ms=5.7 Jiujiang-Ruichang earthquake occurred on November 26, 2005. After the earthquake, we carded out a repeated geomagnetic survey at 21 stations in the Jiujiang-Ruichang region and created a corresponding ＂2005.0 partially revised surface spline model of China geomagnetic field＂. By comparing the above three models, analyzing the geomagnetic horizontal component at the profile in the Jiujiang-Ruichang region and quantitatively studying the geomagnetic data of every stations around the Ms=5.7 earthquake, we have obtained the geomagnetic abnormity associated with this earthquake. Then the geomagnetic abnormity and its relation with seismic activity are discussed in this paper.
文摘The objective of this study was to investigate the possibility of fitting spline regression models for power take-off(PTO)performance characteristics of an agricultural tractor tested with four different fuels,including diesel fuel(B0)and three biodiesel blends made of canola oil(B10:10%biodiesel+90%petro-diesel blend;B20:20%biodiesel+90%petro-diesel blend;B30:30%biodiesel+90%petro-diesel blend).The performance characteristics evaluated were PTO power,engine torque,engine fuel consumption,and specific fuel consumption.Due to sharp slopes in measured quantities around the nominal engine speed(2200 r/min),compared to the standard regression method,the spline regression models suited well to the experimental data with coefficient of determination R2=0.99 for PTO power and engine torque.R2 varied between 0.97 and 0.99 for fuel consumption and 0.91 and 0.95 for specific fuel consumption.The weaker correlation found for specific fuel consumption could be attributed to profound fluctuations in measured data causing atypical pattern in the corresponding graphs around the nominal engine speed.It was concluded that splines were useful to accurately predict the measured PTO power and engine torque.Neither standard methods nor splines were sufficient to obtain very good regression models for specific fuel consumption.
基金supported by National Natural Science Foundation of China(Grant Nos.11031007 and 60903148)the Chinese Universities Scientific Fund+2 种基金Scientific Research Foundation for the Returned Overseas Chinese ScholarsState Education Ministry,the Chinese Academy of Sciences Startup Scientific Research Foundationthe State Key Development Program for Basic Research of China(973 Program)(Grant No.2011CB302400)
文摘This paper provides a survey of local refinable splines,including hierarchical B-splines,T-splines,polynomial splines over T-meshes,etc.,with a view to applications in geometric modeling and iso-geometric analysis.We will identify the strengths and weaknesses of these methods and also offer suggestions for their using in geometric modeling and iso-geometric analysis.
基金supported by the National Natural Science Foun-dation of China(Grant Nos.91230111,11361002)the Natural Science Foundation of Ningxia Hui Autonomous Region(Grant No.NZ13086)
文摘A 2-D depth averaged RNG k- ε model is developed to simulate the flow in a typical reach of the Upper Yellow River with non-monotonic banks. In order to take account of the effect of the secondary flow in a bend, the momentum equations are modified by adding an additional source term. A comparison between the numerical simulation and the field measurements indicates that the improved 2-D depth averaged RNG k- ε model can improve the accuracy of the numerical simulation. An arc spline interpolation method is developed to interpolate the non-monotonic river banks. The method can also be reasonably applied for the 2-D interpolation of the river bed level. Through a comparison of the water surface gradients simulated in the seven bends of the studied reach, some analytical formulae are improved to reasonably calculate the longitudinal and transverse gradients in meandering river reaches. Furthermore, the positions of the maximum water depth and the maximum velocity in a typical bend are discussed.
