Based on the experimental results of super-elastic NiTi alloy, a three-dimensional super-elastic constitutive model including both of stress-induced martensite transformation and plasticity is constructed in a framewo...Based on the experimental results of super-elastic NiTi alloy, a three-dimensional super-elastic constitutive model including both of stress-induced martensite transformation and plasticity is constructed in a framework of general inelasticity. In the proposed model, transformation hardening, reverse transformation of stress-induced martensite, elastic mismatch between the austenite and martensite phases, and temperature-dependence of transformation stress and elastic modulus of each phase are considered. The plastic yielding of martensite occurred under high stress is addressed by a bilinear isotropic hardening rule. Drucker-Prager-typed transformation surfaces are employed to describe the asymmetric behavior of NiTi alloy in tension and compression. The prediction capability of the proposed model is verified by comparing the simulated results with the correspondent experimental ones. Based on backward Euler＇s integration, a new expression of consistent tangent modulus is derived. The proposed model is then implemented into a finite element package ABAQUS by user-subroutine UMAT. Finally, the validity of such implementation was verified by some numerical samples.展开更多
The newly proposed element energy projection(EEP) method has been applied to the computation of super_convergent nodal stresses of Timoshenko beam elements.General formulas based on element projection theorem were der...The newly proposed element energy projection(EEP) method has been applied to the computation of super_convergent nodal stresses of Timoshenko beam elements.General formulas based on element projection theorem were derived and illustrative numerical examples using two typical elements were given.Both the analysis and examples show that EEP method also works very well for the problems with vector function solutions.The EEP method gives super_convergent nodal stresses,which are well comparable to the nodal displacements in terms of both convergence rate and error magnitude.And in addition,it can overcome the “shear locking” difficulty for stresses even when the displacements are badly affected.This research paves the way for application of the EEP method to general one_dimensional systems of ordinary differential equations.展开更多
Based on the newly-developed element energy projection （EEP） method with optimal super-convergence order for computation of super-convergent results, an improved self-adaptive strategy for one-dimensional finite ele...Based on the newly-developed element energy projection （EEP） method with optimal super-convergence order for computation of super-convergent results, an improved self-adaptive strategy for one-dimensional finite element method （FEM） is proposed. In the strategy, a posteriori errors are estimated by comparing FEM solutions to EEP super-convergent solutions with optimal order of super-convergence, meshes are refined by using the error-averaging method. Quasi-FEM solutions are used to replace the true FEM solutions in the adaptive process. This strategy has been found to be simple, clear, efficient and reliable. For most problems, only one adaptive step is needed to produce the required FEM solutions which pointwise satisfy the user specified error tolerances in the max-norm. Taking the elliptical ordinary differential equation of the second order as the model problem, this paper describes the fundamental idea, implementation strategy and computational algorithm and representative numerical examples are given to show the effectiveness and reliability of the proposed approach.展开更多
Dispersed elements do not always occur as associated elements in the ore deposits of other elements. Instead, they can constitute independent ore deposits. The focus of this paper is placed on the mechanism of super-e...Dispersed elements do not always occur as associated elements in the ore deposits of other elements. Instead, they can constitute independent ore deposits. The focus of this paper is placed on the mechanism of super-enrichment of the four dispersed elements Tl, Ge, Se, and Te under favorable geological conditions, where their enrichment coefficients are so high that their abundances can reach n×10+3-n×10+4, sometimes even up to n×10+6 times (e.g. Te) those of the crust. As a result, they can form their independent ore deposits. Studies have shown that such independent ore deposits are mostly distributed in the southwestern part of China, most of which belong to low-temperature ore deposits, ranging in age from Yanshanian to Himalayan (Cretaceous to Cenozoic), with a significant time gap with the host strata. Moreover, this paper also deals with the existing forms (as independent minerals, occurring isomorphously and being adsorbed) of the dispersed elements in those independent ore deposits. The discovery of independent ore deposits of dispersed elements is a great breakthrough in the study of dispersed element metallogenesis.展开更多
The element energy projection （EEP） method for computation of super- convergent resulting in a one-dimensional finite element method （FEM） is successfully used to self-adaptive FEM analysis of various linear probl...The element energy projection （EEP） method for computation of super- convergent resulting in a one-dimensional finite element method （FEM） is successfully used to self-adaptive FEM analysis of various linear problems, based on which this paper presents a substantial extension of the whole set of technology to nonlinear problems. The main idea behind the technology transfer from linear analysis to nonlinear analysis is to use Newton＇s method to linearize nonlinear problems into a series of linear problems so that the EEP formulation and the corresponding adaptive strategy can be directly used without the need for specific super-convergence formulation for nonlinear FEM. As a re- sult, a unified and general self-adaptive algorithm for nonlinear FEM analysis is formed. The proposed algorithm is found to be able to produce satisfactory finite element results with accuracy satisfying the user-preset error tolerances by maximum norm anywhere on the mesh. Taking the nonlinear ordinary differential equation （ODE） of second-order as the model problem, this paper describes the related fundamental idea, the imple- mentation strategy, and the computational algorithm. Representative numerical exam- ples are given to show the efficiency, stability, versatility, and reliability of the proposed approach.展开更多
Based on the newly-developed element energy projection （EEP） method for computation of super-convergent results in one-dimensional finite element method （FEM）, the task of self-adaptive FEM analysis was converted ...Based on the newly-developed element energy projection （EEP） method for computation of super-convergent results in one-dimensional finite element method （FEM）, the task of self-adaptive FEM analysis was converted into the task of adaptive piecewise polynomial interpolation. As a result, a satisfactory FEM mesh can be obtained, and further FEM analysis on this mesh would immediately produce an FEM solution which usually satisfies the user specified error tolerance. Even though the error tolerance was not completely satisfied, one or two steps of further local refinements would be sufficient. This strategy was found to be very simple, rapid, cheap and efficient. Taking the elliptical ordinary differential equation of second order as the model problem, the fundamental idea, implementation strategy and detailed algorithm are described. Representative numerical examples are given to show the effectiveness and reliability of the proposed approach.展开更多
Liaohe super-heavy crude oil was separated into its components, namely saturates, aromatics, resins, and asphaltenes （SARA）, by the group separation method. Several solvents were used to extract different forms of m...Liaohe super-heavy crude oil was separated into its components, namely saturates, aromatics, resins, and asphaltenes （SARA）, by the group separation method. Several solvents were used to extract different forms of metallic elements from crude oil. The metallic elements, such as calcium, nickel, iron and manganese, in crude oil, SARA and extract samples were analyzed by inductively coupled plasma atomic emission spectroscopy （ICP-AES）. The results demonstrate that the contents of calcium, nickel, iron, and manganese gradually increase in saturates, aromatics, resins, and asphaltenes, suggesting that the abundance of the four metallic elements in asphaltenes is much higher than that in the other groups. For example, the content of calcium in asphaltenes reaches a maximum of 7,920 pg/g. Among the SARA components of Liaohe super-heavy crude oil, resins account for more than 50 wt%, suggesting that the total amount of the four metallic elements are higher in the resin component than in other components. The four metallic elements mainly exist in the form of organic metallic compounds in crude oil. Further analysis shows that calcium and manganese elements exist mainly as metal salts of petroleum acids, and the majority of the iron and all the nickel exist mainly as metalloporphyrin and non-metalloporphyrin compounds.展开更多
Repressor elements significantly influence economically relevant phenotypes in pigs;however,their precise roles and characteristics are inadequately understood.In the present study,we employed H3K27me3 profiling,assay...Repressor elements significantly influence economically relevant phenotypes in pigs;however,their precise roles and characteristics are inadequately understood.In the present study,we employed H3K27me3 profiling,assay for transposase-accessible chromatin with highthroughput sequencing(ATAC-seq),and RNA sequencing(RNA-seq)data across six tissues derived from three embryonic layers to identify and map 2034 super repressor elements(SREs) and 22223 typical repressor elements(TREs) in the pig genome.Notably,many repressor elements were conserved across mesodermal and ectodermal tissues.SREs exhibited tight regulation of their target genes,affecting a limited number of genes within a specific genomic region with pronounced effects,while TREs exerted broader but weaker regulation over a wider range of target genes.Furthermore,in neuronal tissues,genes regulated by repressor elements started to be repressed during the differentiation of stem cells into progenitor cells.Notably,analysis showed that many repressor elements exhibited cooperative and additive effects on the modulation of KLF4 expression.This research provides the first comprehensive map of pig repressor elements,serving as an essential reference for future studies on repressor elements.展开更多
Long piles of the ocean oil platform are usually manufactured as the integration of several segments, which have to be assembled one by one during installation. During pile driving, excessive pore pressure will build ...Long piles of the ocean oil platform are usually manufactured as the integration of several segments, which have to be assembled one by one during installation. During pile driving, excessive pore pressure will build up in such a high level that hydraulic fracturing in the soil round the pile may take place, which will cause the soil to consolidate much faster during pile extension period. Consequently, after pile extension, the soil strength will recover to some extent and the driving resistance will increase considerably, which makes restarting driving the pile very difficult and even causes refusal. A finite element （FE） analysis procedure is presented for judging the risk of refusal by estimating the blow counts after pile extension, in which the regain of soil strength is considered. A case analysis in Bohai Gulf is performed using the proposed orocedure to exolain the nile refusal phenomenon.展开更多
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
Static strength finite element analysis was conducted to decrease the weight of a skeleton vehicle＇s frame. Results indicated that the maximum stress occurs on the front beam ＇s variable section area. Dynamic sensit...Static strength finite element analysis was conducted to decrease the weight of a skeleton vehicle＇s frame. Results indicated that the maximum stress occurs on the front beam ＇s variable section area. Dynamic sensitivity analysis elucidated the relationship between the maximum stress and the thickness of a particular beam,e. g.,top,middle,and bottom beam. Displacement was analyzed by the key part that influenced the maximum stress. Finally,the new plan using BS960 super-high-strength beam steel and the preferred beam thickness was compared with the original plan. New combinations of beam thickness were introduced on the basis of different purposes; the maximum responding light w eight ratio was 21%.展开更多
目的建立超级微波消解-碰撞反应池电感耦合等离子体质谱法同时测定蔬菜中铅、砷、镉、铬等21种元素的方法。方法选择超级微波消解法进行样品预处理,以硝酸为消解液,运用具有八极杆反应池系统的电感耦合等离子体质谱仪,以铂锥作为采样锥...目的建立超级微波消解-碰撞反应池电感耦合等离子体质谱法同时测定蔬菜中铅、砷、镉、铬等21种元素的方法。方法选择超级微波消解法进行样品预处理,以硝酸为消解液,运用具有八极杆反应池系统的电感耦合等离子体质谱仪,以铂锥作为采样锥,使用He气碰撞模式(5 m L/min),通过动能歧视和碰撞诱导解离进行干扰的消除。此外,选择包括低、中、高质量范围的^(6)Li、^(45)Sc、^(72)Ge、^(103)Rh、^(115)In、^(159)Tb、^(175)Lu、^(209)Bi元素作为内标,使用在线添加内标的方式进行干扰消除,并在数据分析时采用虚拟内标校正模式。结果在优化后的实验条件下,21种元素在一定的质量浓度区间内,其对应的信号强度与质量浓度呈线性关系。标准曲线线性良好,相关系数在0.999~1.000之间。方法的检出限在0.005~1.200 mg/kg,定量限在0.015~3.600 mg/kg。方法通过加标回收测定回收率,加标回收率在85.2%~119.9%之间。对处理后的蔬菜样品加入低、中、高3种不同浓度的标准,每份平行测定7次,测定值的相对标准偏差在1.03%~4.60%之间。结论通过本研究方法对蔬菜样品中21种元素进行测定,满足国家标准对各项技术指标参数的要求。该方法检出限低,选择性好,结果准确可靠,为蔬菜样品中多种元素分析测定提供了新的参考方法。展开更多
基金supported by the New Century Excellent Talents in University (No.NCET05-0796)National Natural Science Foundation of China (No.50625515)the Innovation Foundation of Southwest Jiaotong University (2008)
文摘Based on the experimental results of super-elastic NiTi alloy, a three-dimensional super-elastic constitutive model including both of stress-induced martensite transformation and plasticity is constructed in a framework of general inelasticity. In the proposed model, transformation hardening, reverse transformation of stress-induced martensite, elastic mismatch between the austenite and martensite phases, and temperature-dependence of transformation stress and elastic modulus of each phase are considered. The plastic yielding of martensite occurred under high stress is addressed by a bilinear isotropic hardening rule. Drucker-Prager-typed transformation surfaces are employed to describe the asymmetric behavior of NiTi alloy in tension and compression. The prediction capability of the proposed model is verified by comparing the simulated results with the correspondent experimental ones. Based on backward Euler＇s integration, a new expression of consistent tangent modulus is derived. The proposed model is then implemented into a finite element package ABAQUS by user-subroutine UMAT. Finally, the validity of such implementation was verified by some numerical samples.
文摘The newly proposed element energy projection(EEP) method has been applied to the computation of super_convergent nodal stresses of Timoshenko beam elements.General formulas based on element projection theorem were derived and illustrative numerical examples using two typical elements were given.Both the analysis and examples show that EEP method also works very well for the problems with vector function solutions.The EEP method gives super_convergent nodal stresses,which are well comparable to the nodal displacements in terms of both convergence rate and error magnitude.And in addition,it can overcome the “shear locking” difficulty for stresses even when the displacements are badly affected.This research paves the way for application of the EEP method to general one_dimensional systems of ordinary differential equations.
基金the National Natural Science Foundation of China(No.50678093)Program for Changjiang Scholars and Innovative Research Team in University(No.IRT00736)
文摘Based on the newly-developed element energy projection （EEP） method with optimal super-convergence order for computation of super-convergent results, an improved self-adaptive strategy for one-dimensional finite element method （FEM） is proposed. In the strategy, a posteriori errors are estimated by comparing FEM solutions to EEP super-convergent solutions with optimal order of super-convergence, meshes are refined by using the error-averaging method. Quasi-FEM solutions are used to replace the true FEM solutions in the adaptive process. This strategy has been found to be simple, clear, efficient and reliable. For most problems, only one adaptive step is needed to produce the required FEM solutions which pointwise satisfy the user specified error tolerances in the max-norm. Taking the elliptical ordinary differential equation of the second order as the model problem, this paper describes the fundamental idea, implementation strategy and computational algorithm and representative numerical examples are given to show the effectiveness and reliability of the proposed approach.
文摘Dispersed elements do not always occur as associated elements in the ore deposits of other elements. Instead, they can constitute independent ore deposits. The focus of this paper is placed on the mechanism of super-enrichment of the four dispersed elements Tl, Ge, Se, and Te under favorable geological conditions, where their enrichment coefficients are so high that their abundances can reach n×10+3-n×10+4, sometimes even up to n×10+6 times (e.g. Te) those of the crust. As a result, they can form their independent ore deposits. Studies have shown that such independent ore deposits are mostly distributed in the southwestern part of China, most of which belong to low-temperature ore deposits, ranging in age from Yanshanian to Himalayan (Cretaceous to Cenozoic), with a significant time gap with the host strata. Moreover, this paper also deals with the existing forms (as independent minerals, occurring isomorphously and being adsorbed) of the dispersed elements in those independent ore deposits. The discovery of independent ore deposits of dispersed elements is a great breakthrough in the study of dispersed element metallogenesis.
基金supported by the National Natural Science Foundation of China(Nos.51378293,51078199,50678093,and 50278046)the Program for Changjiang Scholars and the Innovative Research Team in University of China(No.IRT00736)
文摘The element energy projection （EEP） method for computation of super- convergent resulting in a one-dimensional finite element method （FEM） is successfully used to self-adaptive FEM analysis of various linear problems, based on which this paper presents a substantial extension of the whole set of technology to nonlinear problems. The main idea behind the technology transfer from linear analysis to nonlinear analysis is to use Newton＇s method to linearize nonlinear problems into a series of linear problems so that the EEP formulation and the corresponding adaptive strategy can be directly used without the need for specific super-convergence formulation for nonlinear FEM. As a re- sult, a unified and general self-adaptive algorithm for nonlinear FEM analysis is formed. The proposed algorithm is found to be able to produce satisfactory finite element results with accuracy satisfying the user-preset error tolerances by maximum norm anywhere on the mesh. Taking the nonlinear ordinary differential equation （ODE） of second-order as the model problem, this paper describes the related fundamental idea, the imple- mentation strategy, and the computational algorithm. Representative numerical exam- ples are given to show the efficiency, stability, versatility, and reliability of the proposed approach.
基金Project supported by the National Natural Science Foundation of China (No.50278046)
文摘Based on the newly-developed element energy projection （EEP） method for computation of super-convergent results in one-dimensional finite element method （FEM）, the task of self-adaptive FEM analysis was converted into the task of adaptive piecewise polynomial interpolation. As a result, a satisfactory FEM mesh can be obtained, and further FEM analysis on this mesh would immediately produce an FEM solution which usually satisfies the user specified error tolerance. Even though the error tolerance was not completely satisfied, one or two steps of further local refinements would be sufficient. This strategy was found to be very simple, rapid, cheap and efficient. Taking the elliptical ordinary differential equation of second order as the model problem, the fundamental idea, implementation strategy and detailed algorithm are described. Representative numerical examples are given to show the effectiveness and reliability of the proposed approach.
基金supported by the National Natural Science Foundation of China (No. 20576075 and 21206194)
文摘Liaohe super-heavy crude oil was separated into its components, namely saturates, aromatics, resins, and asphaltenes （SARA）, by the group separation method. Several solvents were used to extract different forms of metallic elements from crude oil. The metallic elements, such as calcium, nickel, iron and manganese, in crude oil, SARA and extract samples were analyzed by inductively coupled plasma atomic emission spectroscopy （ICP-AES）. The results demonstrate that the contents of calcium, nickel, iron, and manganese gradually increase in saturates, aromatics, resins, and asphaltenes, suggesting that the abundance of the four metallic elements in asphaltenes is much higher than that in the other groups. For example, the content of calcium in asphaltenes reaches a maximum of 7,920 pg/g. Among the SARA components of Liaohe super-heavy crude oil, resins account for more than 50 wt%, suggesting that the total amount of the four metallic elements are higher in the resin component than in other components. The four metallic elements mainly exist in the form of organic metallic compounds in crude oil. Further analysis shows that calcium and manganese elements exist mainly as metal salts of petroleum acids, and the majority of the iron and all the nickel exist mainly as metalloporphyrin and non-metalloporphyrin compounds.
基金supported by the Science&Technology Department of Yunnan Province (202102AE090039)National Natural Science Foundation of China (32100502)+3 种基金Yunnan Revitalization Talent Support Program Young Talent ProjectCAS “Light of West China”ProgramSpring City Plan:High-level Talent Promotion and Training Project of Kunming (2022SCP001)CAS Key Technology Talent Program to Y.G。
文摘Repressor elements significantly influence economically relevant phenotypes in pigs;however,their precise roles and characteristics are inadequately understood.In the present study,we employed H3K27me3 profiling,assay for transposase-accessible chromatin with highthroughput sequencing(ATAC-seq),and RNA sequencing(RNA-seq)data across six tissues derived from three embryonic layers to identify and map 2034 super repressor elements(SREs) and 22223 typical repressor elements(TREs) in the pig genome.Notably,many repressor elements were conserved across mesodermal and ectodermal tissues.SREs exhibited tight regulation of their target genes,affecting a limited number of genes within a specific genomic region with pronounced effects,while TREs exerted broader but weaker regulation over a wider range of target genes.Furthermore,in neuronal tissues,genes regulated by repressor elements started to be repressed during the differentiation of stem cells into progenitor cells.Notably,analysis showed that many repressor elements exhibited cooperative and additive effects on the modulation of KLF4 expression.This research provides the first comprehensive map of pig repressor elements,serving as an essential reference for future studies on repressor elements.
基金supported by the National Natural Science Foundation of China(51322904 and 51279127)the Program for New Century Excellent Talents in University(HCET-11-0370)
文摘Long piles of the ocean oil platform are usually manufactured as the integration of several segments, which have to be assembled one by one during installation. During pile driving, excessive pore pressure will build up in such a high level that hydraulic fracturing in the soil round the pile may take place, which will cause the soil to consolidate much faster during pile extension period. Consequently, after pile extension, the soil strength will recover to some extent and the driving resistance will increase considerably, which makes restarting driving the pile very difficult and even causes refusal. A finite element （FE） analysis procedure is presented for judging the risk of refusal by estimating the blow counts after pile extension, in which the regain of soil strength is considered. A case analysis in Bohai Gulf is performed using the proposed orocedure to exolain the nile refusal phenomenon.
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Static strength finite element analysis was conducted to decrease the weight of a skeleton vehicle＇s frame. Results indicated that the maximum stress occurs on the front beam ＇s variable section area. Dynamic sensitivity analysis elucidated the relationship between the maximum stress and the thickness of a particular beam,e. g.,top,middle,and bottom beam. Displacement was analyzed by the key part that influenced the maximum stress. Finally,the new plan using BS960 super-high-strength beam steel and the preferred beam thickness was compared with the original plan. New combinations of beam thickness were introduced on the basis of different purposes; the maximum responding light w eight ratio was 21%.
文摘目的建立超级微波消解-碰撞反应池电感耦合等离子体质谱法同时测定蔬菜中铅、砷、镉、铬等21种元素的方法。方法选择超级微波消解法进行样品预处理,以硝酸为消解液,运用具有八极杆反应池系统的电感耦合等离子体质谱仪,以铂锥作为采样锥,使用He气碰撞模式(5 m L/min),通过动能歧视和碰撞诱导解离进行干扰的消除。此外,选择包括低、中、高质量范围的^(6)Li、^(45)Sc、^(72)Ge、^(103)Rh、^(115)In、^(159)Tb、^(175)Lu、^(209)Bi元素作为内标,使用在线添加内标的方式进行干扰消除,并在数据分析时采用虚拟内标校正模式。结果在优化后的实验条件下,21种元素在一定的质量浓度区间内,其对应的信号强度与质量浓度呈线性关系。标准曲线线性良好,相关系数在0.999~1.000之间。方法的检出限在0.005~1.200 mg/kg,定量限在0.015~3.600 mg/kg。方法通过加标回收测定回收率,加标回收率在85.2%~119.9%之间。对处理后的蔬菜样品加入低、中、高3种不同浓度的标准,每份平行测定7次,测定值的相对标准偏差在1.03%~4.60%之间。结论通过本研究方法对蔬菜样品中21种元素进行测定,满足国家标准对各项技术指标参数的要求。该方法检出限低,选择性好,结果准确可靠,为蔬菜样品中多种元素分析测定提供了新的参考方法。
