This paper focuses on studying the Lie symmetry and a conserved quantity of a system of first-order differential equations. The determining equations of the Lie symmetry for a system of first-order differential equati...This paper focuses on studying the Lie symmetry and a conserved quantity of a system of first-order differential equations. The determining equations of the Lie symmetry for a system of first-order differential equations, from which a kind of conserved quantity is deduced, are presented. And their general conclusion is applied to a Hamilton system, a Birkhoff system and a generalized Hamilton system. Two examples are given to illustrate the application of the results.展开更多
In nD differential geometry, basic geometric structures and properties are described locally by differentiable functions and equations with indices that obey Einstein summation convention. Although symbolic manipulati...In nD differential geometry, basic geometric structures and properties are described locally by differentiable functions and equations with indices that obey Einstein summation convention. Although symbolic manipulation of such indexed functions is one of the oldest research topics in computer algebra, so far there exists no normal form reduction algorithm to judge whether two indexed polynomials involving indices of different coordinate systems are equal or not. It is a challenging task in computer algebra. In this paper, for a typical framework—the partial derivatives in coordinate transformation matrix involved are of order no more than two (such as local computations of ordinary curvatures and tor-sion), we put forward two algorithms, one on elimination of all redundant dummy indices of indexed polynomials, the other on normalization of such indexed polynomials, by which we can judge whether two indexed polynomials are equal or not. We implement the algorithms with Maple V.10 and use them to solve tensor verification problems in differential geometry, and to derive automatically the transformation rules of locally defined indexed functions under the change of local coordinates.展开更多
目的研究机械牵张作用对大鼠小梁网细胞蛋白组学的表达影响。方法实验对象选用对数生长期的大鼠小梁网细胞。采用FX-5000牵张应力加载系统拉伸细胞,提取细胞全蛋白后进行基于鸟枪法的质谱测试和蛋白质的鉴定。运用微阵列显著性分析(sign...目的研究机械牵张作用对大鼠小梁网细胞蛋白组学的表达影响。方法实验对象选用对数生长期的大鼠小梁网细胞。采用FX-5000牵张应力加载系统拉伸细胞,提取细胞全蛋白后进行基于鸟枪法的质谱测试和蛋白质的鉴定。运用微阵列显著性分析(significance analysis of microarray,SAM)方法分析实验组和对照组的蛋白组学差异;对差异蛋白进行基于Gene Ontology(GO)的功能注释、富集和Kyoto Encyclopedia of Genes and Genomes(KEGG)通路富集并筛选出显著富集的蛋白。结果 SAM法筛选出差异蛋白共计57种,均表达上调,分布在细胞各个区域,参与细胞发育、免疫调节、刺激反应、代谢、细胞黏附等过程。其中24种显著富集在9个隶属生物学过程的GO term中,进一步KEGG通路富集分析显示热休克蛋白和核糖体蛋白显著富集在内质网蛋白加工通路和核糖体通路中。结论机械牵张对大鼠小梁网细胞的蛋白质表达影响区域广,过程复杂。富集分析说明热休克蛋白和核糖体蛋白在牵张刺激下的应答保护和眼压调控中起到了重要作用。展开更多
Nature consists of various soft tissues with well-ordered hierarchical anisotropic structures, which play essential roles in biological systems to exhibit particular functions. Mimicking bio-tissues, synthetic hydroge...Nature consists of various soft tissues with well-ordered hierarchical anisotropic structures, which play essential roles in biological systems to exhibit particular functions. Mimicking bio-tissues, synthetic hydrogels with anisotropic structures have received considerable attention in recent years. However, existing approaches to fabricate anisotropic hydrogels often require complicated procedures, which are timeconsuming and labor-demanding. Inspired by the dry-induced crystallization phenomenon, we report a simple yet effective prestretching-drying-swelling method to afford anisotropic crystalline polyvinyl alcohol hydrogels. Owing to the distinct anisotropic microstructure, the hydrogels demonstrate excellent mechanical properties with noticeable directional distinction. It is revealed that both the enhancing of pre-orientation strain and the extending of heating time make the hydrogels with better mechanical properties and more remarkable anisotropicity. Owing to the anisotropically aligned structure, the hydrogels exhibit remarkably differential ionic conductivity: the difference between the parallel and vertical conductivity of the same sample can reach as high as 6.6 times, making the materials possible candidates as nano-conductive materials. We anticipate that this simple yet effective approach may become highly useful for fabricating oriented hydrogels and endow the materials with more promising application prospects in the future.展开更多
A set of nonlinear partial differential equations was used to describe the motions of an internal flowing system, with the consideration of transient fluid structure interaction (FSI). The stability characteristics of...A set of nonlinear partial differential equations was used to describe the motions of an internal flowing system, with the consideration of transient fluid structure interaction (FSI). The stability characteristics of the system were analyzed on the basis of the nonlinear FSI-equation model. The results show that the stability of the nonlinear FSI system become very complicated because of the influence of strongly coupled interaction between flowing liquid and vibrating pipe. The flowing velocity, pressure, the piping stiffness, and constrained conditions, etc. play a very important role in developing procedure of the system stabilization. In an analysis example given in this paper, for example, when the flowing pressure is comparatively small, the system exhibits flutter instability, and when the flowing pressure is increases to a specified value, a subcritical divergence and a supercritical flutter bifurcation take successively place in the same velocity range.展开更多
Given the speed requirements of a mechanical press slider, a differential gear train is adopted instead of the belt and gear drive of a general mechanical press. Two electric motors are used to drive the differential ...Given the speed requirements of a mechanical press slider, a differential gear train is adopted instead of the belt and gear drive of a general mechanical press. Two electric motors are used to drive the differential gear train with hybrid input. Based on the working principle of a differential gear train, the angular speed equations and the power dis- tribution equations of the input-output system are established. By controlling the angular speeds of the two motors, the slider can move at different speeds. Taken a JH23-100 type mechanical press as example, the driving system is designed and the power of two motors determined. The simulated results show that the highest slider speed in the mechanical press approaches 39 mm/s only at the forging-punching stage, far less than the 232 mm/s of a general JH23-100 type mechanical press. This provides a new scheme to realize low-speed forging-punching technology from a mechanical press.展开更多
基金Project supported by the National Natural Science Foundation of China （Grant No 10272021） and the Doctoral Program Foundation of Institution of Higher Education of China （Grant No 20040007022）.
文摘This paper focuses on studying the Lie symmetry and a conserved quantity of a system of first-order differential equations. The determining equations of the Lie symmetry for a system of first-order differential equations, from which a kind of conserved quantity is deduced, are presented. And their general conclusion is applied to a Hamilton system, a Birkhoff system and a generalized Hamilton system. Two examples are given to illustrate the application of the results.
基金supported by Major State Basic Research Development Program of China (Grant No.2004CB318001)Leading Academic Disciplines Program of Shanghai (Grant No. S30501)
文摘In nD differential geometry, basic geometric structures and properties are described locally by differentiable functions and equations with indices that obey Einstein summation convention. Although symbolic manipulation of such indexed functions is one of the oldest research topics in computer algebra, so far there exists no normal form reduction algorithm to judge whether two indexed polynomials involving indices of different coordinate systems are equal or not. It is a challenging task in computer algebra. In this paper, for a typical framework—the partial derivatives in coordinate transformation matrix involved are of order no more than two (such as local computations of ordinary curvatures and tor-sion), we put forward two algorithms, one on elimination of all redundant dummy indices of indexed polynomials, the other on normalization of such indexed polynomials, by which we can judge whether two indexed polynomials are equal or not. We implement the algorithms with Maple V.10 and use them to solve tensor verification problems in differential geometry, and to derive automatically the transformation rules of locally defined indexed functions under the change of local coordinates.
文摘目的研究机械牵张作用对大鼠小梁网细胞蛋白组学的表达影响。方法实验对象选用对数生长期的大鼠小梁网细胞。采用FX-5000牵张应力加载系统拉伸细胞,提取细胞全蛋白后进行基于鸟枪法的质谱测试和蛋白质的鉴定。运用微阵列显著性分析(significance analysis of microarray,SAM)方法分析实验组和对照组的蛋白组学差异;对差异蛋白进行基于Gene Ontology(GO)的功能注释、富集和Kyoto Encyclopedia of Genes and Genomes(KEGG)通路富集并筛选出显著富集的蛋白。结果 SAM法筛选出差异蛋白共计57种,均表达上调,分布在细胞各个区域,参与细胞发育、免疫调节、刺激反应、代谢、细胞黏附等过程。其中24种显著富集在9个隶属生物学过程的GO term中,进一步KEGG通路富集分析显示热休克蛋白和核糖体蛋白显著富集在内质网蛋白加工通路和核糖体通路中。结论机械牵张对大鼠小梁网细胞的蛋白质表达影响区域广,过程复杂。富集分析说明热休克蛋白和核糖体蛋白在牵张刺激下的应答保护和眼压调控中起到了重要作用。
基金financial support from the National Key Research and Development Program of China (No.2019YFE0111000)the National Natural Science Foundation of China (NSFC,Nos.51903253,51903257)+2 种基金Natural Science Foundation of Guangdong Province of China (Nos.2019A1515011150,2019A1515011258)Macao University of Science and Technology Foundation (No.FRG-19-003-SP)the Science and Technology Development Fund of Macao (Nos.FDCT 0009/2019/A,0083/2019/A2,0007/2019/AKP)。
文摘Nature consists of various soft tissues with well-ordered hierarchical anisotropic structures, which play essential roles in biological systems to exhibit particular functions. Mimicking bio-tissues, synthetic hydrogels with anisotropic structures have received considerable attention in recent years. However, existing approaches to fabricate anisotropic hydrogels often require complicated procedures, which are timeconsuming and labor-demanding. Inspired by the dry-induced crystallization phenomenon, we report a simple yet effective prestretching-drying-swelling method to afford anisotropic crystalline polyvinyl alcohol hydrogels. Owing to the distinct anisotropic microstructure, the hydrogels demonstrate excellent mechanical properties with noticeable directional distinction. It is revealed that both the enhancing of pre-orientation strain and the extending of heating time make the hydrogels with better mechanical properties and more remarkable anisotropicity. Owing to the anisotropically aligned structure, the hydrogels exhibit remarkably differential ionic conductivity: the difference between the parallel and vertical conductivity of the same sample can reach as high as 6.6 times, making the materials possible candidates as nano-conductive materials. We anticipate that this simple yet effective approach may become highly useful for fabricating oriented hydrogels and endow the materials with more promising application prospects in the future.
基金TheworkwassupportedbytheNationalNaturalScienceFoundationofChina (No :5 0 0 790 0 7) thekeyprojectofScienceandTechnolgyinHydraulicEngineeringfromtheMinistryofWaterConservancy (No :Sz9830 )andtheProvincialNaturalScienceFoundationofYunnan (No :97E0 0
文摘A set of nonlinear partial differential equations was used to describe the motions of an internal flowing system, with the consideration of transient fluid structure interaction (FSI). The stability characteristics of the system were analyzed on the basis of the nonlinear FSI-equation model. The results show that the stability of the nonlinear FSI system become very complicated because of the influence of strongly coupled interaction between flowing liquid and vibrating pipe. The flowing velocity, pressure, the piping stiffness, and constrained conditions, etc. play a very important role in developing procedure of the system stabilization. In an analysis example given in this paper, for example, when the flowing pressure is comparatively small, the system exhibits flutter instability, and when the flowing pressure is increases to a specified value, a subcritical divergence and a supercritical flutter bifurcation take successively place in the same velocity range.
文摘Given the speed requirements of a mechanical press slider, a differential gear train is adopted instead of the belt and gear drive of a general mechanical press. Two electric motors are used to drive the differential gear train with hybrid input. Based on the working principle of a differential gear train, the angular speed equations and the power dis- tribution equations of the input-output system are established. By controlling the angular speeds of the two motors, the slider can move at different speeds. Taken a JH23-100 type mechanical press as example, the driving system is designed and the power of two motors determined. The simulated results show that the highest slider speed in the mechanical press approaches 39 mm/s only at the forging-punching stage, far less than the 232 mm/s of a general JH23-100 type mechanical press. This provides a new scheme to realize low-speed forging-punching technology from a mechanical press.
