California is one of the major alfalfa (Medicago sativa L) forage-producing states in the U.S, but its production area has decreased significantly in the last couple of decades. Selection of cultivars with high yield ...California is one of the major alfalfa (Medicago sativa L) forage-producing states in the U.S, but its production area has decreased significantly in the last couple of decades. Selection of cultivars with high yield and nutritive value under late-cutting schedule strategy may help identify cultivars that growers can use to maximize yield while maintaining area for sustainable alfalfa production, but there is little information on this strategy. A field study was conducted to determine cumulative dry matter (DM) and nutritive values of 20 semi- and non-fall dormant (FD) ratings (FD 7 and FD 8 - 10, respectively) cultivars under 35-day cut in California’s Central Valley in 2020-2022. Seasonal cumulative DM yields ranged from 6.8 in 2020 to 37.0 Mg·ha−1 in 2021. Four FD 8 - 9 cultivars were the highest yielding with 3-yrs avg. DM greater than the lowest yielding lines by 46%. FD 7 cultivar “715RR” produced the highest crude protein (CP: 240 g·Kg−1) while FD 8 cultivar “HVX840RR” resulted in the highest neutral detergent fiber digestibility (NDFD: 484 g·Kg−1, 7% greater than the top yielding cultivars) but with DM yield intermediate. Yields and NDFD correlated positively but weakly indicating some semi- and non-FD cultivars performing similarly. These results suggest that selecting high yielding cultivars under 35-day cutting schedule strategy can be used as a tool to help growers to maximize yield while achieving good quality forages for sustainable alfalfa production in California’s Central Valley.展开更多
针对R-cut(Ratio cut)边缘检测分割模型对高分辨率遥感影像分割时存在过分割和模糊边缘敏感性问题,提出了一种多尺度R-cut(Multi-scale ratio cut,MSR-cut)的遥感影像边缘检测分割方法。首先,采用形态重建的分水岭分割算法对影像过分割...针对R-cut(Ratio cut)边缘检测分割模型对高分辨率遥感影像分割时存在过分割和模糊边缘敏感性问题,提出了一种多尺度R-cut(Multi-scale ratio cut,MSR-cut)的遥感影像边缘检测分割方法。首先,采用形态重建的分水岭分割算法对影像过分割,形成多个超像素区域;然后计算并提取影像各个区域的纹理特征信息熵值、光谱特征与邻域均值差分归一化值,分别进行同质性和异质性的有效衡量;并构建评价函数获取最优分割尺度,对这些超像素区域进行初步合并,得到影像的粗分割结果;最后结合各地物的边界权重信息,从全局角度用R-cut的方法对粗分割结果进一步合并,完成对影像的精细分割,生成最终的分割结果。实验选取5个不同场景的高分辨率遥感影像,采用定性和定量两种方法对比分析本文方法与传统R-cut边缘检测分割、Spectral-Rcut边缘检测分割和Textured-Rcut边缘检测分割方法。实验结果表明,MSR-cut边缘检测分割方法能够有效提高分割精度,增强噪声鲁棒性,可取得较好的分割视觉效果。展开更多
Te is widely used in iron and steel industry. After adding a certain amount of Te in the steel, many physical and chemical properties can be improved. As a free-cutting element, a small amount of Te can significantly ...Te is widely used in iron and steel industry. After adding a certain amount of Te in the steel, many physical and chemical properties can be improved. As a free-cutting element, a small amount of Te can significantly improve the machinability of steel. The existing form of Te in the steel, the modification law of MnS inclusion by Te and the influence rule and mechanism of Te on the machinability of steel are summarized and expounded in detail, providing a reference for further study and development of Te-containing free-cutting steels.展开更多
A combined process consisting of a short-cut nitrification （SN） reactor and an anaerobic ammonium oxidation upflow anaerobic sludge bed （ANAMMOX） reactor was developed to treat the diluted effluent from an upflow ...A combined process consisting of a short-cut nitrification （SN） reactor and an anaerobic ammonium oxidation upflow anaerobic sludge bed （ANAMMOX） reactor was developed to treat the diluted effluent from an upflow anaerobic sludge bed （UASB） reactor treating high ammonium municipal landfill leachate.The SN process was performed in an aerated upflow sludge bed （AUSB） reactor （working volume 3.05 L）,treating about 50% of the diluted raw wastewater.The ammonium removal efficiency and the ratio of NO 2 N to NOx-N in the effluent were both higher than 80%,at a maximum nitrogen loading rate of 1.47 kg/（m 3 ·day）.The ANAMMOX process was performed in an UASB reactor （working volume 8.5 L）,using the mix of SN reactor effluent and diluted raw wastewater at a ratio of 1：1.The ammonium and nitrite removal efficiency reached over 93% and 95%,respectively,after 70-day continuous operation,at a maximum total nitrogen loading rate of 0.91 kg/（m 3 ·day）,suggesting a successful operation of the combined process.The average nitrogen loading rate of the combined system was 0.56 kg/（m 3 ·day）,with an average total inorganic nitrogen removal efficiency 87%.The nitrogen in the effluent was mostly nitrate.The results provided important evidence for the possibility of applying SN-ANAMMOX after UASB reactor to treat municipal landfill leachate.展开更多
The machinability tests were conducted by using a YD-21 dynamometer on a CA6161A lathe.The experiments were conducted to determine the effect of free-cutting additives on machining characteristics of austenitic stainl...The machinability tests were conducted by using a YD-21 dynamometer on a CA6161A lathe.The experiments were conducted to determine the effect of free-cutting additives on machining characteristics of austenitic stainless steels.The conventional austenitic stainless steel 1Cr18Ni9Ti（steel A） and the free cutting austenitic stainless steel（steel B） were prepared.The results have shown that machinable inclusions were composed of MnS and CuO,and they might be also Ti4C2S2.The presence of Bi in the inclusion was detected by the atom map and electro-probe microanalysis（EPMA）,which might be one of the most important factors to improve the machinability of austenitic stainless steels.The cutting forces for steel B were lower than those of steel A at various cutting speeds;the abrasion depth of the flank of the tool for steel B was less than that of the steel A under the same cutting conditions.The machinability of austenitic stainless steel was visibly improved by adding free-cutting additives,such as S,Cu and Bi.Ultimate tensile,yield strength,and total elongation values of the free cutting austenitic stainless steel were improved due to the addition of these free-cutting additives.展开更多
A new method called mixed Lagrangian and Eulerian （MiLE） method was used to simulate the continuous casting process in a mold of free-cutting steel 38MnVS.The simulation results are basically in agreement with exper...A new method called mixed Lagrangian and Eulerian （MiLE） method was used to simulate the continuous casting process in a mold of free-cutting steel 38MnVS.The simulation results are basically in agreement with experimental data in the literature,achieving the three-dimensional visualization of temperature distribution,melt flow,shell thickness,and stress distribution of blooms in a mold.It is shown that the flow velocity of steel melt becomes smaller gradually as the casting proceeds.When the flow reaches a certain depth,two types of flow patterns can be observed in the upper zone of the mold.The first flow pattern is to flow downwards,and the second one is to flow upwards to the meniscus.The corner temperature is higher,and the thickness is thinner than those in the mid-face.The effective stress in the corner area is much bigger than that in the mid-face,indicating that the corner area is the dangerous zone of cracking.展开更多
文摘California is one of the major alfalfa (Medicago sativa L) forage-producing states in the U.S, but its production area has decreased significantly in the last couple of decades. Selection of cultivars with high yield and nutritive value under late-cutting schedule strategy may help identify cultivars that growers can use to maximize yield while maintaining area for sustainable alfalfa production, but there is little information on this strategy. A field study was conducted to determine cumulative dry matter (DM) and nutritive values of 20 semi- and non-fall dormant (FD) ratings (FD 7 and FD 8 - 10, respectively) cultivars under 35-day cut in California’s Central Valley in 2020-2022. Seasonal cumulative DM yields ranged from 6.8 in 2020 to 37.0 Mg·ha−1 in 2021. Four FD 8 - 9 cultivars were the highest yielding with 3-yrs avg. DM greater than the lowest yielding lines by 46%. FD 7 cultivar “715RR” produced the highest crude protein (CP: 240 g·Kg−1) while FD 8 cultivar “HVX840RR” resulted in the highest neutral detergent fiber digestibility (NDFD: 484 g·Kg−1, 7% greater than the top yielding cultivars) but with DM yield intermediate. Yields and NDFD correlated positively but weakly indicating some semi- and non-FD cultivars performing similarly. These results suggest that selecting high yielding cultivars under 35-day cutting schedule strategy can be used as a tool to help growers to maximize yield while achieving good quality forages for sustainable alfalfa production in California’s Central Valley.
文摘针对R-cut(Ratio cut)边缘检测分割模型对高分辨率遥感影像分割时存在过分割和模糊边缘敏感性问题,提出了一种多尺度R-cut(Multi-scale ratio cut,MSR-cut)的遥感影像边缘检测分割方法。首先,采用形态重建的分水岭分割算法对影像过分割,形成多个超像素区域;然后计算并提取影像各个区域的纹理特征信息熵值、光谱特征与邻域均值差分归一化值,分别进行同质性和异质性的有效衡量;并构建评价函数获取最优分割尺度,对这些超像素区域进行初步合并,得到影像的粗分割结果;最后结合各地物的边界权重信息,从全局角度用R-cut的方法对粗分割结果进一步合并,完成对影像的精细分割,生成最终的分割结果。实验选取5个不同场景的高分辨率遥感影像,采用定性和定量两种方法对比分析本文方法与传统R-cut边缘检测分割、Spectral-Rcut边缘检测分割和Textured-Rcut边缘检测分割方法。实验结果表明,MSR-cut边缘检测分割方法能够有效提高分割精度,增强噪声鲁棒性,可取得较好的分割视觉效果。
基金Acknowledgements This work was financially supported by the National Key Research and Development Program of China （No. 2018YFB0704400）, the National Natural Science Foundation of China （Nos. 51474142 and 51671124） and the China Postdoctoral Science Foundation （No. 2018M632082）.
文摘Te is widely used in iron and steel industry. After adding a certain amount of Te in the steel, many physical and chemical properties can be improved. As a free-cutting element, a small amount of Te can significantly improve the machinability of steel. The existing form of Te in the steel, the modification law of MnS inclusion by Te and the influence rule and mechanism of Te on the machinability of steel are summarized and expounded in detail, providing a reference for further study and development of Te-containing free-cutting steels.
基金supported by the Special Fundof State Key Joint Laboratory of Environment Simulation and Pollution Control,China (No. 08Y03ESPCT)the Key Projects in the National Science & Technology Pillar Program in the Eleventh Five-Year Plan Period of China(No. 2006BACl9B01)
文摘A combined process consisting of a short-cut nitrification （SN） reactor and an anaerobic ammonium oxidation upflow anaerobic sludge bed （ANAMMOX） reactor was developed to treat the diluted effluent from an upflow anaerobic sludge bed （UASB） reactor treating high ammonium municipal landfill leachate.The SN process was performed in an aerated upflow sludge bed （AUSB） reactor （working volume 3.05 L）,treating about 50% of the diluted raw wastewater.The ammonium removal efficiency and the ratio of NO 2 N to NOx-N in the effluent were both higher than 80%,at a maximum nitrogen loading rate of 1.47 kg/（m 3 ·day）.The ANAMMOX process was performed in an UASB reactor （working volume 8.5 L）,using the mix of SN reactor effluent and diluted raw wastewater at a ratio of 1：1.The ammonium and nitrite removal efficiency reached over 93% and 95%,respectively,after 70-day continuous operation,at a maximum total nitrogen loading rate of 0.91 kg/（m 3 ·day）,suggesting a successful operation of the combined process.The average nitrogen loading rate of the combined system was 0.56 kg/（m 3 ·day）,with an average total inorganic nitrogen removal efficiency 87%.The nitrogen in the effluent was mostly nitrate.The results provided important evidence for the possibility of applying SN-ANAMMOX after UASB reactor to treat municipal landfill leachate.
基金supported by the National Natural Science Foundation of China(No.50334010)the Educational Department of Liaoning Province,China(No.2008535)the Shenyang City Application Basic Research Project,China(No.1071198-1-00)
文摘The machinability tests were conducted by using a YD-21 dynamometer on a CA6161A lathe.The experiments were conducted to determine the effect of free-cutting additives on machining characteristics of austenitic stainless steels.The conventional austenitic stainless steel 1Cr18Ni9Ti（steel A） and the free cutting austenitic stainless steel（steel B） were prepared.The results have shown that machinable inclusions were composed of MnS and CuO,and they might be also Ti4C2S2.The presence of Bi in the inclusion was detected by the atom map and electro-probe microanalysis（EPMA）,which might be one of the most important factors to improve the machinability of austenitic stainless steels.The cutting forces for steel B were lower than those of steel A at various cutting speeds;the abrasion depth of the flank of the tool for steel B was less than that of the steel A under the same cutting conditions.The machinability of austenitic stainless steel was visibly improved by adding free-cutting additives,such as S,Cu and Bi.Ultimate tensile,yield strength,and total elongation values of the free cutting austenitic stainless steel were improved due to the addition of these free-cutting additives.
基金supported by the National Natural Science Foundation of China (No.50874007)
文摘A new method called mixed Lagrangian and Eulerian （MiLE） method was used to simulate the continuous casting process in a mold of free-cutting steel 38MnVS.The simulation results are basically in agreement with experimental data in the literature,achieving the three-dimensional visualization of temperature distribution,melt flow,shell thickness,and stress distribution of blooms in a mold.It is shown that the flow velocity of steel melt becomes smaller gradually as the casting proceeds.When the flow reaches a certain depth,two types of flow patterns can be observed in the upper zone of the mold.The first flow pattern is to flow downwards,and the second one is to flow upwards to the meniscus.The corner temperature is higher,and the thickness is thinner than those in the mid-face.The effective stress in the corner area is much bigger than that in the mid-face,indicating that the corner area is the dangerous zone of cracking.
