基于对单元能量投影(element energy projection,EEP)法误差项的直接推导及分析,用EEP简约格式的解计算出略掉的误差项,反补后得到比简约格式高一阶精度的EEP超收敛计算的加强格式。该文以一维Galerkin有限元为例,给出EEP加强格式的算...基于对单元能量投影(element energy projection,EEP)法误差项的直接推导及分析,用EEP简约格式的解计算出略掉的误差项,反补后得到比简约格式高一阶精度的EEP超收敛计算的加强格式。该文以一维Galerkin有限元为例,给出EEP加强格式的算法公式和数学证明。理论分析和算例验证表明:对于m (≥1)次单元,采用EEP加强格式计算的内点位移和内点导数都具有h^(min(m+3,2m))阶的收敛精度,对系数特例问题二者甚至可以分别达到h^(min(m+5,2m))和h^(min(m+4,2m))阶的收敛精度。并对该法的进一步拓展作了讨论。展开更多
对m(>1)次单元,基于单元能量投影(element energy projection,简称EEP)法提出的简约格式位移解u∗具有比常规有限元解uh至少高一阶的精度,据此提出了EEP单元概念,并给出以EEP单元作为最终解的自适应有限元求解策略.通过编制相应的计...对m(>1)次单元,基于单元能量投影(element energy projection,简称EEP)法提出的简约格式位移解u∗具有比常规有限元解uh至少高一阶的精度,据此提出了EEP单元概念,并给出以EEP单元作为最终解的自适应有限元求解策略.通过编制相应的计算程序分析了一维非自伴随问题,计算结果与理论预期吻合较好,验证了自适应求解策略的有效性和可靠性.研究结果表明:该法可以给出按最大模度量、逐点满足误差限的解答,相较于常规单元,最终的求解单元数更少.展开更多
为了降低入侵检测系统的误报率和漏报率,我们将两阶段分类算法(Classification of EssentialEmerging Pattern in Two Phases)CEEPTP应用到入侵检测中。该算法结合两阶段思想和基本显露模式eEP在分类方面的优势,使用两个阶段挖掘eEP并...为了降低入侵检测系统的误报率和漏报率,我们将两阶段分类算法(Classification of EssentialEmerging Pattern in Two Phases)CEEPTP应用到入侵检测中。该算法结合两阶段思想和基本显露模式eEP在分类方面的优势,使用两个阶段挖掘eEP并用于分类,分类时考虑第二阶段对第一阶段的修正作用,实验表明具有较好的分类结果。展开更多
对于结构动力分析中的离散系统运动方程,现有算法的计算精度和效率均依赖于时间步长的选取,这是时间域问题求解的难点.基于EEP(element energy projection)超收敛计算的自适应有限元法,以EEP超收敛解代替未知真解,估计常规有限元解的误...对于结构动力分析中的离散系统运动方程,现有算法的计算精度和效率均依赖于时间步长的选取,这是时间域问题求解的难点.基于EEP(element energy projection)超收敛计算的自适应有限元法,以EEP超收敛解代替未知真解,估计常规有限元解的误差,并自动细分网格,目前已对诸类以空间坐标为自变量的边值问题取得成功.对离散系统运动方程建立弱型Galerkin有限元解,引入基于EEP法的自适应求解策略,在时间域上自动划分网格,最终得到所求时域内任一时刻均满足给定误差限的动位移解,进而建立了一种时间域上的新型自适应求解算法.展开更多
This study investigated the emission characteristics of ultra.fine particles based on test bench and on-board measurements. The bench test results showed the ultrafine particle number concentration of the diesel engin...This study investigated the emission characteristics of ultra.fine particles based on test bench and on-board measurements. The bench test results showed the ultrafine particle number concentration of the diesel engine to be in the range of （0.56-8.35）×10^8 cm^-3. The on-board measurement results illustrated that the ultra_fine particles were strongly correlated with changes in real-world driving cycles. The particle number concentration was down to 2.0 ×10^6 cm^-3 and 2.7 ×10^7 cm^-3 under decelerating and idling operations and as high as 5.0×10^8 cm^-3 under accelerating operation. It was also indicated that the particle number measured by the two methods increased with the growth of engine load at each engine speed in both cases. The particle number presented a ＂U＂ shaped distribution with changing speed at high engine load conditions, which implies that the particle number will reach its lowest level at medium engine speeds. The particle sizes of both measurements showed single mode distributions. The peak of particle size was located at about 50-80 nm in the accumulation mode particle range. Nucleation mode particles will significantly increase at low engine load operations like idling and decelerating caused by the high concentration of unburned organic compounds.展开更多
This paper completely introduces the basic idea of the EFP (Equivalent Frame Photo) aerial triangulation, EFP image point coordinate calculation and the function model of adjustment as well as the digital simulation o...This paper completely introduces the basic idea of the EFP (Equivalent Frame Photo) aerial triangulation, EFP image point coordinate calculation and the function model of adjustment as well as the digital simulation of the satellite photogrammetry. Then, the free framework + the control points adjustment, the adjustment with the observations of the exterior orientation element, detection the constant error of the observations of the exterior orientation element and the block adjustment are calculated and analysed using the simulated data. Through experiments and analysis, the conclusions are: The strip length of the three baselengths can be built up a stable model of the three-line array CCD image strip adjustment; The control points can be arranged on the start and the end of the strip. The elevation accuracy of the twofold area is lower about a factor of 1.4 than the threefold area; The observations of the exterior orientation element are the necessary data for the three-line array CCD image bundle adjustment. By the adjustment, the elevation accuracy can be improved in variant levels. Even if the accuracy of the observations of the exterior orientation elements are so high now, the elevation accuracy of the bundle adjustment is higher than the only forward intersection, so the three-line array CCD camera is more advantageous than single-line and double-line cameras in global satellite photogrammetry without control points or the exterior planet photogrammetry.展开更多
利用单元能量投影(Element Energy Projection,简称EEP)法所计算的EEP超收敛解,在不改变有限元网格及其整体刚度矩阵的情况下,导出残差的等效结点荷载向量,只经回代过程即可得到具有更高阶精度的结点位移的误差估计,使结点位移精度得到...利用单元能量投影(Element Energy Projection,简称EEP)法所计算的EEP超收敛解,在不改变有限元网格及其整体刚度矩阵的情况下,导出残差的等效结点荷载向量,只经回代过程即可得到具有更高阶精度的结点位移的误差估计,使结点位移精度得到极大提高。该文以一般的二阶常微分方程边值和初值问题为例,给出算法和相应的数值算例。从中可以看出,本法十分简单而高效:对于m≥1次单元,采用EEP简约格式和凝聚格式修正后的结点位移,分别具有O(h^(2m+2))和O(h^(3m+mod(m,2)))的超常规的超收敛阶。该文给出了典型算例,并对该法的进一步拓展和应用作了讨论。展开更多
文摘基于对单元能量投影(element energy projection,EEP)法误差项的直接推导及分析,用EEP简约格式的解计算出略掉的误差项,反补后得到比简约格式高一阶精度的EEP超收敛计算的加强格式。该文以一维Galerkin有限元为例,给出EEP加强格式的算法公式和数学证明。理论分析和算例验证表明:对于m (≥1)次单元,采用EEP加强格式计算的内点位移和内点导数都具有h^(min(m+3,2m))阶的收敛精度,对系数特例问题二者甚至可以分别达到h^(min(m+5,2m))和h^(min(m+4,2m))阶的收敛精度。并对该法的进一步拓展作了讨论。
文摘对m(>1)次单元,基于单元能量投影(element energy projection,简称EEP)法提出的简约格式位移解u∗具有比常规有限元解uh至少高一阶的精度,据此提出了EEP单元概念,并给出以EEP单元作为最终解的自适应有限元求解策略.通过编制相应的计算程序分析了一维非自伴随问题,计算结果与理论预期吻合较好,验证了自适应求解策略的有效性和可靠性.研究结果表明:该法可以给出按最大模度量、逐点满足误差限的解答,相较于常规单元,最终的求解单元数更少.
文摘为了降低入侵检测系统的误报率和漏报率,我们将两阶段分类算法(Classification of EssentialEmerging Pattern in Two Phases)CEEPTP应用到入侵检测中。该算法结合两阶段思想和基本显露模式eEP在分类方面的优势,使用两个阶段挖掘eEP并用于分类,分类时考虑第二阶段对第一阶段的修正作用,实验表明具有较好的分类结果。
文摘对于结构动力分析中的离散系统运动方程,现有算法的计算精度和效率均依赖于时间步长的选取,这是时间域问题求解的难点.基于EEP(element energy projection)超收敛计算的自适应有限元法,以EEP超收敛解代替未知真解,估计常规有限元解的误差,并自动细分网格,目前已对诸类以空间坐标为自变量的边值问题取得成功.对离散系统运动方程建立弱型Galerkin有限元解,引入基于EEP法的自适应求解策略,在时间域上自动划分网格,最终得到所求时域内任一时刻均满足给定误差限的动位移解,进而建立了一种时间域上的新型自适应求解算法.
基金supported the Instantaneous Emission and Environmental Impact study on Vehicle Alternative Fuel(No.10231201902)the Project of Study and Demonstration of Real Time On-Road Vehicle Emission and Pollution Warning (No.10231201700) from the Shanghai Science and Technology Commission
文摘This study investigated the emission characteristics of ultra.fine particles based on test bench and on-board measurements. The bench test results showed the ultrafine particle number concentration of the diesel engine to be in the range of （0.56-8.35）×10^8 cm^-3. The on-board measurement results illustrated that the ultra_fine particles were strongly correlated with changes in real-world driving cycles. The particle number concentration was down to 2.0 ×10^6 cm^-3 and 2.7 ×10^7 cm^-3 under decelerating and idling operations and as high as 5.0×10^8 cm^-3 under accelerating operation. It was also indicated that the particle number measured by the two methods increased with the growth of engine load at each engine speed in both cases. The particle number presented a ＂U＂ shaped distribution with changing speed at high engine load conditions, which implies that the particle number will reach its lowest level at medium engine speeds. The particle sizes of both measurements showed single mode distributions. The peak of particle size was located at about 50-80 nm in the accumulation mode particle range. Nucleation mode particles will significantly increase at low engine load operations like idling and decelerating caused by the high concentration of unburned organic compounds.
文摘This paper completely introduces the basic idea of the EFP (Equivalent Frame Photo) aerial triangulation, EFP image point coordinate calculation and the function model of adjustment as well as the digital simulation of the satellite photogrammetry. Then, the free framework + the control points adjustment, the adjustment with the observations of the exterior orientation element, detection the constant error of the observations of the exterior orientation element and the block adjustment are calculated and analysed using the simulated data. Through experiments and analysis, the conclusions are: The strip length of the three baselengths can be built up a stable model of the three-line array CCD image strip adjustment; The control points can be arranged on the start and the end of the strip. The elevation accuracy of the twofold area is lower about a factor of 1.4 than the threefold area; The observations of the exterior orientation element are the necessary data for the three-line array CCD image bundle adjustment. By the adjustment, the elevation accuracy can be improved in variant levels. Even if the accuracy of the observations of the exterior orientation elements are so high now, the elevation accuracy of the bundle adjustment is higher than the only forward intersection, so the three-line array CCD camera is more advantageous than single-line and double-line cameras in global satellite photogrammetry without control points or the exterior planet photogrammetry.
文摘利用单元能量投影(Element Energy Projection,简称EEP)法所计算的EEP超收敛解,在不改变有限元网格及其整体刚度矩阵的情况下,导出残差的等效结点荷载向量,只经回代过程即可得到具有更高阶精度的结点位移的误差估计,使结点位移精度得到极大提高。该文以一般的二阶常微分方程边值和初值问题为例,给出算法和相应的数值算例。从中可以看出,本法十分简单而高效:对于m≥1次单元,采用EEP简约格式和凝聚格式修正后的结点位移,分别具有O(h^(2m+2))和O(h^(3m+mod(m,2)))的超常规的超收敛阶。该文给出了典型算例,并对该法的进一步拓展和应用作了讨论。
