本文利用同步辐射真空紫外和超声分子束反射式飞行时间质谱系统研究间二甲苯的光电离和离解光电离.通过测定母体离子C_(8)H_(10)^(+)和主要碎片离子(C_(8)H_(9)^(+)和C_(7)H_(7)^(+))的光电离效率谱,确定了母体分子的电离能和主要碎片离...本文利用同步辐射真空紫外和超声分子束反射式飞行时间质谱系统研究间二甲苯的光电离和离解光电离.通过测定母体离子C_(8)H_(10)^(+)和主要碎片离子(C_(8)H_(9)^(+)和C_(7)H_(7)^(+))的光电离效率谱,确定了母体分子的电离能和主要碎片离子(C_(8)H_(8)^(+)和C_(7)H_(7)^(+))的出现势分别为8.60±0.03 eV,11.76±0.04 eV和11.85±0.05 eV eV.在B3LYP/6-311++G(d,p)水平上优化了两个主要解离通道的反应物、过渡态、中间体和产物的结构,并在G3水平上计算了它们的能量,以及两个主要的离解光电离通道产物C_(7)H_(7)^(+)+CH_(3)和C_(8)H_(9)^(+)+H的能量.结合理论和实验结果,间二甲苯的离解光电离机理主要过程是C-H键或C-C键的离解和氢迁移.展开更多
In real machining, the tool paths are composed of a series of short line segments, which constitute groups of sharp corners correspondingly leading to geometry discontinuity in tangent. As a result, high acceleration ...In real machining, the tool paths are composed of a series of short line segments, which constitute groups of sharp corners correspondingly leading to geometry discontinuity in tangent. As a result, high acceleration with high fluctuation usually occurs. If these kinds of tool paths are directly used for machining, the feedrate and quality will be greatly reduced. Thus, generating continuous tool paths is strongly desired. This paper presents a new error-controllable method for generating continuous tool path. Different from the traditional method focusing on fitting the cutter locations, the proposed method realizes globally smoothing the tool path in an error-controllable way. Concretely, it does the smoothing by approaching the newly produced curve to the linear tool path by taking the tolerance requirement as a constraint. That is, the error between the desired tool path and the G01 commands are taken as a boundary condition to ensure the finally smoothed curve being within the given tolerance. Besides, to improve the smoothing ability in case of small corner angle, an improved local smoothing method is also proposed by symmetrically assigning the control points to the two adjacent linear segments with the constrains of tolerance and G3 continuity. Experiments on an open five-axis machine are developed to verify the advantages of the proposed methods.展开更多
基金This work was supported by the National Natural Science Foundation of China(No.11275006,No.12105042,No.11805032,No.11505027,No.11575178,No.U1532137)Nuclear Technology Application Engineering Research Center Open Foundation of Ministry of Education(No.HJSJYB2015-6,No.HJSJYB2017-1,HJSJYB2018-6)+4 种基金the Chinese Scholarship Council(No.201608360053)the Graduate Students High-Quality Course Construction Program of Jiangxi Province(No.JXYYK2016-12)the China Postdoctoral Science Foundation(No.2013M531530)the Doctoral Foundation of East China University of Technology(No.DHBK201401,No.DHBK2018059)the Provincial Natural Science Research Program of Higher Education Institutions of Anhui Province(No.KJ2012B086).
文摘本文利用同步辐射真空紫外和超声分子束反射式飞行时间质谱系统研究间二甲苯的光电离和离解光电离.通过测定母体离子C_(8)H_(10)^(+)和主要碎片离子(C_(8)H_(9)^(+)和C_(7)H_(7)^(+))的光电离效率谱,确定了母体分子的电离能和主要碎片离子(C_(8)H_(8)^(+)和C_(7)H_(7)^(+))的出现势分别为8.60±0.03 eV,11.76±0.04 eV和11.85±0.05 eV eV.在B3LYP/6-311++G(d,p)水平上优化了两个主要解离通道的反应物、过渡态、中间体和产物的结构,并在G3水平上计算了它们的能量,以及两个主要的离解光电离通道产物C_(7)H_(7)^(+)+CH_(3)和C_(8)H_(9)^(+)+H的能量.结合理论和实验结果,间二甲苯的离解光电离机理主要过程是C-H键或C-C键的离解和氢迁移.
基金supported by the National Natural Science Foundation of China under Grant Nos.51675440 and 11620101002National Key Research and Development Program of China under Grant No.2017YFB1102800the Fundamental Research Funds for the Central Universities under Grant No.3102018gxc025
文摘In real machining, the tool paths are composed of a series of short line segments, which constitute groups of sharp corners correspondingly leading to geometry discontinuity in tangent. As a result, high acceleration with high fluctuation usually occurs. If these kinds of tool paths are directly used for machining, the feedrate and quality will be greatly reduced. Thus, generating continuous tool paths is strongly desired. This paper presents a new error-controllable method for generating continuous tool path. Different from the traditional method focusing on fitting the cutter locations, the proposed method realizes globally smoothing the tool path in an error-controllable way. Concretely, it does the smoothing by approaching the newly produced curve to the linear tool path by taking the tolerance requirement as a constraint. That is, the error between the desired tool path and the G01 commands are taken as a boundary condition to ensure the finally smoothed curve being within the given tolerance. Besides, to improve the smoothing ability in case of small corner angle, an improved local smoothing method is also proposed by symmetrically assigning the control points to the two adjacent linear segments with the constrains of tolerance and G3 continuity. Experiments on an open five-axis machine are developed to verify the advantages of the proposed methods.
