在机械切削加工中,当刀具无修光刃的情况下,加工后的工件表面上会残留下类似于螺纹一样的表面,即残留面积,它在很大程度上影响着已加工表面质量。本文将分析在不同的切削条件下残留面积的形状,并着重推导各种形状的残留面积高度 R 的理...在机械切削加工中,当刀具无修光刃的情况下,加工后的工件表面上会残留下类似于螺纹一样的表面,即残留面积,它在很大程度上影响着已加工表面质量。本文将分析在不同的切削条件下残留面积的形状,并着重推导各种形状的残留面积高度 R 的理论计算公式。展开更多
[Objective] The aim was to study the dynamic variation of extinction coefficient of corn population, so as to improve the accuracy of assessment on net primary productivity （NPP） or yield. [Method] Based on the data...[Objective] The aim was to study the dynamic variation of extinction coefficient of corn population, so as to improve the accuracy of assessment on net primary productivity （NPP） or yield. [Method] Based on the data of photosynthetic active radiation and leaf area index during corn growing season （from May to September） in 2006, observed in Jinzhou observation station of corn farmland ecosystem, China Meteorological Administration, the dynamic variation of extinction coefficient of corn population was analyzed. [Result] There was a great daily variation in the extinction coefficient of corn population during growing season, and the maximum value appeared from 7：00 to 9：00 and from 15：00 to 17：00, while the minimum could be found around 12：00, but the amplitude of variation decreased in tasseling stage. On a large time scale （5 d）, there was a parabolic relationship between extinction coefficient （K） and leaf area index （LAI）, with determination coefficient R2 of 0.960 7. The simulation equation of extinction coefficient, based on the sun elevation angle or leaf area index, had poor accuracy at various time during growing season, so a new dynamic model of extinction coefficient was established, namely K=λ（0.784 8-0.001 6θ）（0.154 8LAI2-0.558 6LAI＋0.654）. [Conclusion] The effect of sun elevation angle and leaf area index on extinction coefficient during corn growing season was considered in the new dynamic model of extinction coefficient, and its simulated result was superior to that of single-factor model.展开更多
Glaciers in the Tomor region of Tianshan Mountains preserve vital water resources. However, these glaciers suffer from strong mass losses in the recent years because of global warming. From 2008 to 2009, a large-scale...Glaciers in the Tomor region of Tianshan Mountains preserve vital water resources. However, these glaciers suffer from strong mass losses in the recent years because of global warming. From 2008 to 2009, a large-scale scientific expedition has been carried out in this region. As an individual reference glacier, the tongue area of Qingbingtan glacier No. 72 was measured by the high precise Real Time Kinematic-Global Position System （RTK-GPS）. In this paper, changes of the tongue area of Qingbingtan glacier No.72 has been studied based on topographic map, remote sensing image and the survey during 2008-2009 field campaign. Results indicated that the ice surface-elevation of the tongue area changed - 0.22~0.14 m a-1 from 1964 to 2008. The estimated loss in ice volume was 0.0144-0.009 km3, which represented a ~20 % decrease from the 1964 volume and was equivalent to average annual mass balance of -0.204-0.12 m water equivalent for the tongue area during 1964-2oo8. Terminus retreated by 1852 m, approximately 41 m a-1, with the area reduction of 1.533 km2 （0.034 km2 a-0 from 1964 to 2009. Furthermore, the annual velocity reached to -70 m a-1. Comparing with the other monitored glaciers in the eastern Tianshan Mountains, Qingbingtan glacier No.72 experienced more intensive in shrinkage, which resulted from the combined effects of climate change and glacier dynamic, providing evidence of the response to climatic warming.展开更多
Coal-based Magnetic Activated Carbons （CMAC＇s） were prepared from three representative coal samples of various ranks： Baorigele lignite from Inner Mongolia; Datong bitumite from Shanxi province; and Taixi anthraci...Coal-based Magnetic Activated Carbons （CMAC＇s） were prepared from three representative coal samples of various ranks： Baorigele lignite from Inner Mongolia; Datong bitumite from Shanxi province; and Taixi anthracite from Ningxia Hui Auto- nomous Region. Fe3O4 was used as a magnetic additive. A nitrogen-adsorption analyzer was used to determine the specific surface area and pore structure of the resulting activated carbons. The adsorption capacity was assessed by the adsorption of iodine and methylene blue. X-ray diffraction was used to measure the evolution behavior of Fe304 during the preparation process. Magnetic properties were characterized with a vibrating-sample magnetometer. The effect of the activation temperature on the performance of CMAC＇s was also studied. The results show that, compared to Baorigele lignite and Taixi anthracite, the Datong bitumite is more appropriate for the preparation of CMAC＇s with a high specific surface area, an advanced pore structure and suitable magnetic properties. Fe304 can effectively enhance the magnetic properties and control the pore structure by increasing the ratio of meso- pores. An addition of 6.0% Fe304 and an activation temperature of 880 ℃ produced a CMAC having a specific surface area, an iodine adsorption, a methylene blue adsorption and a specific saturation magnetization of 1152.0 m2/g, 1216.7 mg/g, 229.5 mg/g and 4.623 emu/g, respectively. The coal used to prepare this specimen was Datong bitumite.展开更多
[Objective] To reveal the leaf functional traits and adaptive strategy of Torreya fargesii at different altitude gradients.[Method] Leaves of T. fargesii were selected from the altitudes of 1 570, 1 700, 1 900, 2 125 ...[Objective] To reveal the leaf functional traits and adaptive strategy of Torreya fargesii at different altitude gradients.[Method] Leaves of T. fargesii were selected from the altitudes of 1 570, 1 700, 1 900, 2 125 and 2 360 m in Jiajinshan forest area of Sichuan Baoxing County, and the altitudes of 1 000, 1 200, 1 450, and 1 700 m in Hua'eshan Mountain Nature Reserve of Sichuan Wanyuan County as the research materials. Leaf blade traits such as leaf length, leaf width, leaf girth, leaf area and leaf dry weight were determined, and the influence of altitude on each index and correlation between characters were analyzed. [Result] For the leaves from both Baoxing County and Wanyuan County, leaf length, leaf width, leaf girth, leaf aspect ratio and leaf area decreased with the increase of altitude. There was no significant difference in the changes of leaf width, leaf girth and leaf aspect ratio among different altitudes(P>0.05), while the difference was significant in leaf length between high altitude and low attitude(P<0.05), and the difference was also significant in leaf area for the leaves from Baoxing County between high altitude and low altitude. However, there was no obvious correlation between leaf width and altitude, which could be considered as a relatively stable parameter. Leaf thickness and leaf dry weight increased first and then decreased with altitude,while the specific leaf area decreased first and then increased. In leaf length, leaf girth, leaf width and leaf area parameters, except for leaf width and leaf area for the T. fargesii from Wanyuan County, any two parameters reached significant or very significant positive correlation level(P<0.01). Leaf dry weight and leaf thickness had significant or very significant positive correlation, leaf dry weight and leaf area had a certain positive correlation but not significant. There existed no significant positive correlation between specific leaf area and leaf area, while specific leaf area was in negative correlation with leaf dry weight, and the negative correlation of specific leaf area with leaf area of T. fargesii from Wanyuan County reached the significant level.[Conclusion] T. fargesii adapted to different altitudes by changing leaf dry weight, leaf area and leaf area ratio, and the most suitable altitudes for the growth of T. fargesii were 1 900 and 1 450 m in Baoxing and Wanyuan area respectively.展开更多
Maritime-type glaciers in the eastern Nyainqêntanglha Range, located in the southeastern part of the Tibetan Plateau, are an important water source for downstream residents and ecological systems. To better under...Maritime-type glaciers in the eastern Nyainqêntanglha Range, located in the southeastern part of the Tibetan Plateau, are an important water source for downstream residents and ecological systems. To better understand the variability of glaciers in this region, we used the band ratio threshold（TM3/TM5 for the Landsat TM /ETM＋ and TM4/TM6 for Landsat OLI） to extract glacier outlines in ~1999 and ~2013. After that, we also generated a series of glacier boundaries and monitored glacier variations in the past 40 years with the help of the Chinese Glacier Inventory data（1975） and Landsat TM, ETM＋ and OLI data. The total glacier area decreased by 37.69 ± 2.84% from 1975 to 2013. The annual percentage area change（APAC） was ~1.32% a-1 and ~1.29% a-1 in the periods 1975-1999 and 1999-2013, respectively. According to the lag theory, the reaction time is probably about 10 years and we discuss the variations of temperature and precipitation between 1965 and 2011. Temperature and precipitation increased between 1965 and 2011 at a rate of 0.34°C /10 a and 15.4 mm/10 a, respectively. Extensive meteorological data show that the glacier shrinkage rate over the period may be mainly due to increasing air temperature, while the increasing precipitation partly made up for the mass loss of glacier ice resulting from increasing temperature may also lead to the low APAC between 1999 and 2013. The lag theory suggests that glacier shrinkage may accelerate in the next 10 years. Small glaciers were more sensitive to climate change, and there was a normal distribution between glacier area and elevation. Glaciers shrank in all aspects, and south aspects diminished faster than others.展开更多
基金Supported by Major Project of Chinese National Programs for Fundamental Research and Development(2006CB400502)National Natural Science Funds for Distinguished Young Scholar(40625015)~~
文摘[Objective] The aim was to study the dynamic variation of extinction coefficient of corn population, so as to improve the accuracy of assessment on net primary productivity （NPP） or yield. [Method] Based on the data of photosynthetic active radiation and leaf area index during corn growing season （from May to September） in 2006, observed in Jinzhou observation station of corn farmland ecosystem, China Meteorological Administration, the dynamic variation of extinction coefficient of corn population was analyzed. [Result] There was a great daily variation in the extinction coefficient of corn population during growing season, and the maximum value appeared from 7：00 to 9：00 and from 15：00 to 17：00, while the minimum could be found around 12：00, but the amplitude of variation decreased in tasseling stage. On a large time scale （5 d）, there was a parabolic relationship between extinction coefficient （K） and leaf area index （LAI）, with determination coefficient R2 of 0.960 7. The simulation equation of extinction coefficient, based on the sun elevation angle or leaf area index, had poor accuracy at various time during growing season, so a new dynamic model of extinction coefficient was established, namely K=λ（0.784 8-0.001 6θ）（0.154 8LAI2-0.558 6LAI＋0.654）. [Conclusion] The effect of sun elevation angle and leaf area index on extinction coefficient during corn growing season was considered in the new dynamic model of extinction coefficient, and its simulated result was superior to that of single-factor model.
基金jointly supported by National Key Project for Basic Research of China (Grant No.2010CB951003)Knowledge Innovation Project of the Chinese Academy of Sciences (Grant No.No.KZCX2-EW-311)National Natural Science Foundation of China (Grant Nos.40631001,41001040,41101066)
文摘Glaciers in the Tomor region of Tianshan Mountains preserve vital water resources. However, these glaciers suffer from strong mass losses in the recent years because of global warming. From 2008 to 2009, a large-scale scientific expedition has been carried out in this region. As an individual reference glacier, the tongue area of Qingbingtan glacier No. 72 was measured by the high precise Real Time Kinematic-Global Position System （RTK-GPS）. In this paper, changes of the tongue area of Qingbingtan glacier No.72 has been studied based on topographic map, remote sensing image and the survey during 2008-2009 field campaign. Results indicated that the ice surface-elevation of the tongue area changed - 0.22~0.14 m a-1 from 1964 to 2008. The estimated loss in ice volume was 0.0144-0.009 km3, which represented a ~20 % decrease from the 1964 volume and was equivalent to average annual mass balance of -0.204-0.12 m water equivalent for the tongue area during 1964-2oo8. Terminus retreated by 1852 m, approximately 41 m a-1, with the area reduction of 1.533 km2 （0.034 km2 a-0 from 1964 to 2009. Furthermore, the annual velocity reached to -70 m a-1. Comparing with the other monitored glaciers in the eastern Tianshan Mountains, Qingbingtan glacier No.72 experienced more intensive in shrinkage, which resulted from the combined effects of climate change and glacier dynamic, providing evidence of the response to climatic warming.
基金supported by the National Natural Science Foundation of China (No20776150)the National High Technology Research and Development Program of China (No2008AA05Z308)
文摘Coal-based Magnetic Activated Carbons （CMAC＇s） were prepared from three representative coal samples of various ranks： Baorigele lignite from Inner Mongolia; Datong bitumite from Shanxi province; and Taixi anthracite from Ningxia Hui Auto- nomous Region. Fe3O4 was used as a magnetic additive. A nitrogen-adsorption analyzer was used to determine the specific surface area and pore structure of the resulting activated carbons. The adsorption capacity was assessed by the adsorption of iodine and methylene blue. X-ray diffraction was used to measure the evolution behavior of Fe304 during the preparation process. Magnetic properties were characterized with a vibrating-sample magnetometer. The effect of the activation temperature on the performance of CMAC＇s was also studied. The results show that, compared to Baorigele lignite and Taixi anthracite, the Datong bitumite is more appropriate for the preparation of CMAC＇s with a high specific surface area, an advanced pore structure and suitable magnetic properties. Fe304 can effectively enhance the magnetic properties and control the pore structure by increasing the ratio of meso- pores. An addition of 6.0% Fe304 and an activation temperature of 880 ℃ produced a CMAC having a specific surface area, an iodine adsorption, a methylene blue adsorption and a specific saturation magnetization of 1152.0 m2/g, 1216.7 mg/g, 229.5 mg/g and 4.623 emu/g, respectively. The coal used to prepare this specimen was Datong bitumite.
基金Supported by the National Natural Science Foundation of China(31470568,31400321)the Science and Technology Project of Fuling District,Chongqing,China(FLKJ,2017ABA)
文摘[Objective] To reveal the leaf functional traits and adaptive strategy of Torreya fargesii at different altitude gradients.[Method] Leaves of T. fargesii were selected from the altitudes of 1 570, 1 700, 1 900, 2 125 and 2 360 m in Jiajinshan forest area of Sichuan Baoxing County, and the altitudes of 1 000, 1 200, 1 450, and 1 700 m in Hua'eshan Mountain Nature Reserve of Sichuan Wanyuan County as the research materials. Leaf blade traits such as leaf length, leaf width, leaf girth, leaf area and leaf dry weight were determined, and the influence of altitude on each index and correlation between characters were analyzed. [Result] For the leaves from both Baoxing County and Wanyuan County, leaf length, leaf width, leaf girth, leaf aspect ratio and leaf area decreased with the increase of altitude. There was no significant difference in the changes of leaf width, leaf girth and leaf aspect ratio among different altitudes(P>0.05), while the difference was significant in leaf length between high altitude and low attitude(P<0.05), and the difference was also significant in leaf area for the leaves from Baoxing County between high altitude and low altitude. However, there was no obvious correlation between leaf width and altitude, which could be considered as a relatively stable parameter. Leaf thickness and leaf dry weight increased first and then decreased with altitude,while the specific leaf area decreased first and then increased. In leaf length, leaf girth, leaf width and leaf area parameters, except for leaf width and leaf area for the T. fargesii from Wanyuan County, any two parameters reached significant or very significant positive correlation level(P<0.01). Leaf dry weight and leaf thickness had significant or very significant positive correlation, leaf dry weight and leaf area had a certain positive correlation but not significant. There existed no significant positive correlation between specific leaf area and leaf area, while specific leaf area was in negative correlation with leaf dry weight, and the negative correlation of specific leaf area with leaf area of T. fargesii from Wanyuan County reached the significant level.[Conclusion] T. fargesii adapted to different altitudes by changing leaf dry weight, leaf area and leaf area ratio, and the most suitable altitudes for the growth of T. fargesii were 1 900 and 1 450 m in Baoxing and Wanyuan area respectively.
基金supported by the National Science Foundation of China (Grant Nos. 41271024, 41411130204)
文摘Maritime-type glaciers in the eastern Nyainqêntanglha Range, located in the southeastern part of the Tibetan Plateau, are an important water source for downstream residents and ecological systems. To better understand the variability of glaciers in this region, we used the band ratio threshold（TM3/TM5 for the Landsat TM /ETM＋ and TM4/TM6 for Landsat OLI） to extract glacier outlines in ~1999 and ~2013. After that, we also generated a series of glacier boundaries and monitored glacier variations in the past 40 years with the help of the Chinese Glacier Inventory data（1975） and Landsat TM, ETM＋ and OLI data. The total glacier area decreased by 37.69 ± 2.84% from 1975 to 2013. The annual percentage area change（APAC） was ~1.32% a-1 and ~1.29% a-1 in the periods 1975-1999 and 1999-2013, respectively. According to the lag theory, the reaction time is probably about 10 years and we discuss the variations of temperature and precipitation between 1965 and 2011. Temperature and precipitation increased between 1965 and 2011 at a rate of 0.34°C /10 a and 15.4 mm/10 a, respectively. Extensive meteorological data show that the glacier shrinkage rate over the period may be mainly due to increasing air temperature, while the increasing precipitation partly made up for the mass loss of glacier ice resulting from increasing temperature may also lead to the low APAC between 1999 and 2013. The lag theory suggests that glacier shrinkage may accelerate in the next 10 years. Small glaciers were more sensitive to climate change, and there was a normal distribution between glacier area and elevation. Glaciers shrank in all aspects, and south aspects diminished faster than others.
