We have investigated numerically the dynamics of quantum Fisher information (QFI) and quantum entanglement (QE) for N-level atomic system interacting with a coherent field in the presence of Kerr (linear and non-linea...We have investigated numerically the dynamics of quantum Fisher information (QFI) and quantum entanglement (QE) for N-level atomic system interacting with a coherent field in the presence of Kerr (linear and non-linear medium) and Stark effects. It is observed that the Stark and Kerr effects play a prominent role during the time evolution of the quantum system. The evolving quantum Fisher information (QFI) is noted as time grows under the non-linear Kerr medium contrary to the QE for higher dimensional systems. The effect of non-linear Kerr medium is greater on the QE as we increase the value of Kerr parameter. However, QFI and QE maintain their periodic nature under atomic motion. On the other hand, linear Kerr medium has no prominent effects on the dynamics of N-level atomic system. Furthermore, it has been observed that QFI and QE decay soon under the influence of Stark effect. In short, the N-level atomic system is found prone to the change of the Kerr medium and Stark effect for higher dimensional systems.展开更多
In this paper,the authors propose a new space vector pulse width modulation(SVPWM)algorithm based on non-orthogonal coordinates for N-level inverters.First,it is pointed out that classicalαβcoordinates-based SVPWM h...In this paper,the authors propose a new space vector pulse width modulation(SVPWM)algorithm based on non-orthogonal coordinates for N-level inverters.First,it is pointed out that classicalαβcoordinates-based SVPWM has many shortcomings because of improper coordinate choice.Then,a non-orthogonal coordinates-based SVPWM is proposed to solve these problems.The proposed algorithm can easily identify which sector the reference space vector falls in and conduct simple operations to find the duty cycle of each vector.Finally,it is verified that the proposed SVPWM is actually a pulse−width modulation(PWM)technology based on line voltages.展开更多
【目的】适宜机栽的油菜毯苗密度大,个体小,抗逆能力差,研究不同氮肥用量对油菜毯苗农艺性状、生理指标以及栽后活棵率的影响,明确油菜机栽毯苗培育的适宜供氮水平。【方法】于2020和2021年份以秦优10号和宁杂158两个油菜品种为供试材料...【目的】适宜机栽的油菜毯苗密度大,个体小,抗逆能力差,研究不同氮肥用量对油菜毯苗农艺性状、生理指标以及栽后活棵率的影响,明确油菜机栽毯苗培育的适宜供氮水平。【方法】于2020和2021年份以秦优10号和宁杂158两个油菜品种为供试材料,在子叶期喷施0.25 g N/盘基础上,于一叶一心期设置0(不施氮肥)、0.5、1.0、1.5和2.0 g N/盘共5个氮肥用量处理,播种后30 d测定农艺性状和生理指标,机栽后10 d田间调查活棵率。【结果】播种后30 d每盘存苗数的变化范围为627—669,随着供氮水平增加,存苗数呈先增加后降低。不同部位的含氮率随着氮肥用量的增加逐渐增加,地上部含氮率高于地下部,碳素含量随着供氮水平的增加总体上呈降低趋势,地下部碳素含量高于对应的地上部碳素含量。地上、地下部碳氮比的变化范围分别为6.98—9.69和12.35—16.26,随着供氮水平的增加均表现为下降趋势。随着氮肥用量增加,油菜毯苗株高、单株叶面积、鲜重、干重和水分含量逐渐增加,其中以地下部鲜重的增加幅度最大,秦优10号和宁杂158两个油菜品种2.0 g N/盘处理的地下部鲜重平均值与不施氮肥处理相比增加幅度分别为106.3%和95.0%。根颈直径和栽后活棵率随着氮肥用量的增加呈先增加后降低趋势,相同年份和品种试验中根颈直径均以1.5 g N/盘处理最高,不同处理栽后活棵率的变化范围为81.7%—97.1%,以1.0和1.5 g N/盘处理较高,均在95%以上,并且两者之间无显著差异。【结论】油菜毯苗培育过程中,在子叶期喷施0.25 g N/盘基础上,一叶一心期喷施1.0—1.5 g N/盘时,机械移栽后每盘存苗数较高,根颈粗、含氮率和碳氮比值适宜,栽后活棵率高。展开更多
【目的】定量中国不同农业生态区和不同产量水平条件下的玉米百千克籽粒地上部吸氮量(N_(100)),分析气候、土壤、品种和施肥因素对玉米N_(100)的影响,为确定合理施氮量提供科学依据。【方法】将中国分为东北、西北、华北平原、长江中下...【目的】定量中国不同农业生态区和不同产量水平条件下的玉米百千克籽粒地上部吸氮量(N_(100)),分析气候、土壤、品种和施肥因素对玉米N_(100)的影响,为确定合理施氮量提供科学依据。【方法】将中国分为东北、西北、华北平原、长江中下游平原、西南和东南6大农作区,搜集1980—2022年发表的349篇符合要求的文献,通过数据统计分析不同区域和不同产量水平条件下的玉米N_(100),并分析采用统一和区域化的N_(100)计算出的理论施氮量差异,采用皮尔逊相关系数(pearson correlation coefficient)、随机森林(random forest)模型和整合分析(Meta-analysis)方法分析气候、土壤和施肥因素对玉米N_(100)的影响,揭示导致中国玉米N_(100)空间差异的原因。【结果】优化处理条件下,中国春玉米N_(100)显著低于夏玉米,分别为2.21和2.46;不同农业生态区玉米N_(100)存在显著差异,分别为2.19(东北春玉米)、2.12(西北春玉米)、2.54(西北夏玉米)、2.45(华北夏玉米)、2.77(长江中下游春玉米)、2.38(长江中下游夏玉米)和2.39(西南玉米区)。依据本研究全国玉米平均N_(100)(2.34)计算的理论施氮量与采用区域化的N_(100)计算得到的理论施氮量相差-22—31 kg N·hm^(-2)。地上部吸氮量、产量、年均气温是影响玉米N_(100)的最重要因素;N_(100)随产量增加呈显著二次曲线降低的趋势(P<0.01),籽粒产量可以很好地预测N_(100);品种显著影响玉米N_(100),中国常见的玉米品种郑单958、先玉335和登海605的N_(100)分别为2.42、2.12和2.39,新品种玉米N_(100)显著低于老品种。施用氮肥显著增加了玉米N_(100),且在施氮量200—300 kg N·hm^(-2)时,施氮肥引起的N_(100)增加效应最大。单施缓控释肥、深施氮肥、减少氮肥基施比例以及增加施氮次数均显著增加了玉米N_(100)。【结论】在利用N_(100)进行合理施氮量计算时,需要考虑不同农业生态区N_(100)的显著差异,以得到更加准确的推荐施氮量,玉米N_(100)的驱动因素主要为作物地上部吸氮量、产量和年均气温的变异。展开更多
文摘We have investigated numerically the dynamics of quantum Fisher information (QFI) and quantum entanglement (QE) for N-level atomic system interacting with a coherent field in the presence of Kerr (linear and non-linear medium) and Stark effects. It is observed that the Stark and Kerr effects play a prominent role during the time evolution of the quantum system. The evolving quantum Fisher information (QFI) is noted as time grows under the non-linear Kerr medium contrary to the QE for higher dimensional systems. The effect of non-linear Kerr medium is greater on the QE as we increase the value of Kerr parameter. However, QFI and QE maintain their periodic nature under atomic motion. On the other hand, linear Kerr medium has no prominent effects on the dynamics of N-level atomic system. Furthermore, it has been observed that QFI and QE decay soon under the influence of Stark effect. In short, the N-level atomic system is found prone to the change of the Kerr medium and Stark effect for higher dimensional systems.
文摘In this paper,the authors propose a new space vector pulse width modulation(SVPWM)algorithm based on non-orthogonal coordinates for N-level inverters.First,it is pointed out that classicalαβcoordinates-based SVPWM has many shortcomings because of improper coordinate choice.Then,a non-orthogonal coordinates-based SVPWM is proposed to solve these problems.The proposed algorithm can easily identify which sector the reference space vector falls in and conduct simple operations to find the duty cycle of each vector.Finally,it is verified that the proposed SVPWM is actually a pulse−width modulation(PWM)technology based on line voltages.
文摘长身高原鳅(Triplophysa tenuis)对维持木扎提河的水生态系统物质和能量流动具有重要作用。文章基于脂肪酸生物标记法和碳、氮稳定同位素(δ^(13)C、δ^(15)N)技术研究了长身高原鳅的食性和营养生态位特征。结果显示,其肌肉中共检测出22种脂肪酸,其中有8种饱和脂肪酸、6种单不饱和脂肪酸、8种多不饱和脂肪酸;由特征脂肪酸组成情况推测,长身高原鳅对浮游动物、硅藻、陆地植物或喜摄食硅藻的鱼虾均有摄食,表现为杂食性。长身高原鳅的δ^(13)C和δ^(15)N分别介于-27.09‰~-20.98‰和5.71‰~8.45‰,营养级介于2.68~3.48。雌雄样本间的δ^(13)C、δ^(15)N和营养级均不存在显著性差异(P>0.05);雄性样本核心生态位(Standard ellipse area,SEAc)和总生态位(Total area of convex hull,TA)均高于雌性。δ^(13)C与体长间表现为极显著正相关性(P<0.01),δ^(15)N和营养级与体长间不具有显著相关性。70~80 mm体长组与90 mm以上体长组SEAc面积不存在重叠且在聚类分析中被分为不同组。综上,长身高原鳅的食性为杂食性且食物组成随体长变化而不同,作为营养级偏高的捕食者,长身高原鳅能延长食物链长度,增加食物网复杂性,有利于维持水域生态系统的稳定性。
文摘【目的】适宜机栽的油菜毯苗密度大,个体小,抗逆能力差,研究不同氮肥用量对油菜毯苗农艺性状、生理指标以及栽后活棵率的影响,明确油菜机栽毯苗培育的适宜供氮水平。【方法】于2020和2021年份以秦优10号和宁杂158两个油菜品种为供试材料,在子叶期喷施0.25 g N/盘基础上,于一叶一心期设置0(不施氮肥)、0.5、1.0、1.5和2.0 g N/盘共5个氮肥用量处理,播种后30 d测定农艺性状和生理指标,机栽后10 d田间调查活棵率。【结果】播种后30 d每盘存苗数的变化范围为627—669,随着供氮水平增加,存苗数呈先增加后降低。不同部位的含氮率随着氮肥用量的增加逐渐增加,地上部含氮率高于地下部,碳素含量随着供氮水平的增加总体上呈降低趋势,地下部碳素含量高于对应的地上部碳素含量。地上、地下部碳氮比的变化范围分别为6.98—9.69和12.35—16.26,随着供氮水平的增加均表现为下降趋势。随着氮肥用量增加,油菜毯苗株高、单株叶面积、鲜重、干重和水分含量逐渐增加,其中以地下部鲜重的增加幅度最大,秦优10号和宁杂158两个油菜品种2.0 g N/盘处理的地下部鲜重平均值与不施氮肥处理相比增加幅度分别为106.3%和95.0%。根颈直径和栽后活棵率随着氮肥用量的增加呈先增加后降低趋势,相同年份和品种试验中根颈直径均以1.5 g N/盘处理最高,不同处理栽后活棵率的变化范围为81.7%—97.1%,以1.0和1.5 g N/盘处理较高,均在95%以上,并且两者之间无显著差异。【结论】油菜毯苗培育过程中,在子叶期喷施0.25 g N/盘基础上,一叶一心期喷施1.0—1.5 g N/盘时,机械移栽后每盘存苗数较高,根颈粗、含氮率和碳氮比值适宜,栽后活棵率高。
文摘【目的】定量中国不同农业生态区和不同产量水平条件下的玉米百千克籽粒地上部吸氮量(N_(100)),分析气候、土壤、品种和施肥因素对玉米N_(100)的影响,为确定合理施氮量提供科学依据。【方法】将中国分为东北、西北、华北平原、长江中下游平原、西南和东南6大农作区,搜集1980—2022年发表的349篇符合要求的文献,通过数据统计分析不同区域和不同产量水平条件下的玉米N_(100),并分析采用统一和区域化的N_(100)计算出的理论施氮量差异,采用皮尔逊相关系数(pearson correlation coefficient)、随机森林(random forest)模型和整合分析(Meta-analysis)方法分析气候、土壤和施肥因素对玉米N_(100)的影响,揭示导致中国玉米N_(100)空间差异的原因。【结果】优化处理条件下,中国春玉米N_(100)显著低于夏玉米,分别为2.21和2.46;不同农业生态区玉米N_(100)存在显著差异,分别为2.19(东北春玉米)、2.12(西北春玉米)、2.54(西北夏玉米)、2.45(华北夏玉米)、2.77(长江中下游春玉米)、2.38(长江中下游夏玉米)和2.39(西南玉米区)。依据本研究全国玉米平均N_(100)(2.34)计算的理论施氮量与采用区域化的N_(100)计算得到的理论施氮量相差-22—31 kg N·hm^(-2)。地上部吸氮量、产量、年均气温是影响玉米N_(100)的最重要因素;N_(100)随产量增加呈显著二次曲线降低的趋势(P<0.01),籽粒产量可以很好地预测N_(100);品种显著影响玉米N_(100),中国常见的玉米品种郑单958、先玉335和登海605的N_(100)分别为2.42、2.12和2.39,新品种玉米N_(100)显著低于老品种。施用氮肥显著增加了玉米N_(100),且在施氮量200—300 kg N·hm^(-2)时,施氮肥引起的N_(100)增加效应最大。单施缓控释肥、深施氮肥、减少氮肥基施比例以及增加施氮次数均显著增加了玉米N_(100)。【结论】在利用N_(100)进行合理施氮量计算时,需要考虑不同农业生态区N_(100)的显著差异,以得到更加准确的推荐施氮量,玉米N_(100)的驱动因素主要为作物地上部吸氮量、产量和年均气温的变异。
