期刊文献+
共找到9篇文章
< 1 >
每页显示 20 50 100
结构控制装置优化布置的性能指标增量方法 被引量:3
1
作者 滕军 卢伟琴 《土木工程学报》 EI CSCD 北大核心 2003年第11期88-92,共5页
为经济有效地发挥控制装置的作用,应用线性系统的二次型性能指标作为目标函数,本文研究了高层结构在地震作用下的控制装置数量、位置和参数的优化设计方法。在系统最优控制反馈增益不变的假定下,首先建立了系统最优控制性能指标增量与... 为经济有效地发挥控制装置的作用,应用线性系统的二次型性能指标作为目标函数,本文研究了高层结构在地震作用下的控制装置数量、位置和参数的优化设计方法。在系统最优控制反馈增益不变的假定下,首先建立了系统最优控制性能指标增量与控制装置减少时系统控制作用分布矩阵变化的线性关系。通过计算撤除控制装置后的系统最优控制性能指标增量,可以得到系统控制所需的控制装置数量及在这个数量下的控制装置最优布置。通过数值分析,仔细推敲了本文假设的实用性和局限性。数值分析结果表明,控制装置数量在一定范围内时,所确定的控制装置最优位置及控制装置参数是非常精确的。 展开更多
关键词 控制装置 控制装置数量 最优位置 性能指标增量
下载PDF
双及物构式ICM识解的功能、性能及语义增量 被引量:4
2
作者 康志峰 邱东林 《外语与外语教学》 CSSCI 北大核心 2010年第6期18-21,共4页
本研究的目的是通过对英语中双及物构式(EDC)结构多义联结语义链的比较研究,推理出该构式论元结构构式的功能、性能以及语义增量,使该构式内的异常句得以ICM识解。经过对构式语法的建构和对认知语义的解析,本研究指出了EDC结构的语义... 本研究的目的是通过对英语中双及物构式(EDC)结构多义联结语义链的比较研究,推理出该构式论元结构构式的功能、性能以及语义增量,使该构式内的异常句得以ICM识解。经过对构式语法的建构和对认知语义的解析,本研究指出了EDC结构的语义受限性,识解了它的无生性增量,同时也识解了它的非自愿性增量。为此,在Goldberg,Pinker,Harley,何晓炜、朱德熙等学者的研究理论基础上,本研究提出了功能、语义以及性能等增量观。本研究的结论:1.发现了EDC结构ICM识解的功能增量;2.推理出了EDC结构ICM识解的性能和语义增量;3.使许多在EDC结构系统中被认为是异常的表达句得以ICM识解。 展开更多
关键词 EDC结构 ICM 功能增量 性能增量 语义增量
原文传递
Experimental research on mechanical properties of prestressed truss concrete composite beam encased with circular steel tube 被引量:3
3
作者 张博一 郑文忠 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2009年第3期338-345,共8页
Tests of 4 simply supported unbonded prestressed truss concrete composite beams encased with circular steel tube were carried out. It is found that the ratio of the stress increment of the unbonded tendon to that of t... Tests of 4 simply supported unbonded prestressed truss concrete composite beams encased with circular steel tube were carried out. It is found that the ratio of the stress increment of the unbonded tendon to that of the tensile steel tube is 0.252 during the using stage,and the average crack space of beams depends on the ratio of the sum of the bottom chord steel tube's outside diameter and the secondary bottom chord steel tube's section area to the effective tensile concrete area. The coefficient of uneven crack distribution is 1.68 and the formula for the calculation of crack width is established. Test results indicate that the ultimate stress increment of unbonded tendon in the beams decreases in linearity with the increase of the composite reinforcement index β0. The pure bending region of beams accords with the plane section assumption from loading to failure. The calculation formula of ultimate stress increment of the unbonded tendon and the method to calculate the bearing capacity of normal section of beams have been presented. Besides,the method to calculate the stiffness of this sort of beams is brought forward as well. 展开更多
关键词 truss concrete composite beam encased with circular steel tube bearing capacity of normal section STIFFNESS crack width unbonded prestressed tendon
下载PDF
Comparison of Procedures to Evaluate the Cyclic Stress-Strain Curve from Incremental Step Test
4
作者 Giovanni Zonfrillo Duccio Nappini 《Journal of Mechanics Engineering and Automation》 2015年第6期362-369,共8页
The design of structural components in low-cycle fatigue field often requires the knowledge of the cyclic properties of the material, which are commonly described by the classical relation of Ramberg-Osgood. In order ... The design of structural components in low-cycle fatigue field often requires the knowledge of the cyclic properties of the material, which are commonly described by the classical relation of Ramberg-Osgood. In order to obtain the cyclic curve using experimental data from incremental step tests, four methodologies are described and critically discussed. Three methods differ in the procedure of evaluation of the elastic modulus, while in the last one the experimental data are interpolated with a single non-linear regression. The various techniques were applied to data obtained from tests carried out on stainless steel specimens, and the resulting differences were analysed and quantified. An average behaviour was evaluated considering the total set of data obtained from experimental tests. The choice of the most suitable method is related to both the strain range of interest and the goal for which the results are used. 展开更多
关键词 Cyclic curve incremental step test Ramberg-Osgood stainless steel.
下载PDF
The Energy Growth Property for Harmonic Maps
5
作者 Li Hongyi Zhao Di(North China institute of Water Conservancy and Hydroelectric Power, Zhengzhou, 450045 ) 《Chinese Quarterly Journal of Mathematics》 CSCD 1996年第1期53-55,共3页
In this paper,we study the energy growth property for a class of harmonic maps. A special estimation of energy growth is obtained.
关键词 harmonic maps energy density
下载PDF
Some Growth Rates of Certain Holomorphic Maps
6
作者 YANGQiao QIUJing-hua 《Chinese Quarterly Journal of Mathematics》 CSCD 2003年第3期258-263,共6页
In this paper we discuss some properties of h olomorphic maps between Kahler manifolds with certain curvature restrictions.
关键词 Hermitian metric holomorphic maps energy density
下载PDF
Intrinsically reinforced silks obtained by incorporation of graphene quantum dots into silkworms 被引量:9
7
作者 Lin Ma Maxwell Akologo Akurugu +4 位作者 Vivian Andoh Haiyan Liu Jiangchao Song Guohua Wu Long Li 《Science China Materials》 SCIE EI CSCD 2019年第2期245-255,共11页
Silkworm silks have been widely used in a variety of fields due to their sensuousness, luster and excellent mechanical properties. Researchers have paid special attention in improving the mechanical properties of silk... Silkworm silks have been widely used in a variety of fields due to their sensuousness, luster and excellent mechanical properties. Researchers have paid special attention in improving the mechanical properties of silks. In this work,Bombyx mori larval silkworms are injected with graphene quantum dots(GQDs) through a vascular injection to enhance mechanical properties of the silkworm silks. The GQDs can be incorporated into the silkworm silk gland easily due to hemolymph circulation and influence the spinning process of silkworm. The breaking strength, elongation at break and toughness modulus of the silks increase by 2.74, 1.33 and 3.62 times, respectively, by injecting per individual with 0.6 μg GQDs. Wide-angle X-ray scattering indicates that the size ofβ-sheet nanocrystals in GQDs-silks is smaller than that in control-silks. Infrared spectra suggest that GQDs confine the conformation transition of silk fibroin to β-sheet from random coil/α-helix, and the change of the size and content of β-sheet may be the reason for the improvement of the mechanical properties. The toxicity and safety limit of GQDs incorporated into each silkworm is also evaluated, and the results show that the upmost dose of GQDs per silkworm is30.0 μg. The successful obtainment of reinforced silks by in vivo uptake of GQDs provides a promising route to produce high-strength silks. 展开更多
关键词 silkworm silks graphene quantum dots decrease of β-sheets enhanced mechanical properties
原文传递
Non-Nehari manifold method for asymptotically periodic Schrodinger equations 被引量:8
8
作者 TANG XianHua 《Science China Mathematics》 SCIE CSCD 2015年第4期715-728,共14页
We consider the semilinear Schrdinger equation-△u + V(x)u = f(x, u), x ∈ RN,u ∈ H 1(RN),where f is a superlinear, subcritical nonlinearity. We mainly study the case where V(x) = V0(x) + V1(x),V0∈ C(RN), V0(x) is 1... We consider the semilinear Schrdinger equation-△u + V(x)u = f(x, u), x ∈ RN,u ∈ H 1(RN),where f is a superlinear, subcritical nonlinearity. We mainly study the case where V(x) = V0(x) + V1(x),V0∈ C(RN), V0(x) is 1-periodic in each of x1, x2,..., x N and sup[σ(-△ + V0) ∩(-∞, 0)] < 0 < inf[σ(-△ +V0)∩(0, ∞)], V1∈ C(RN) and lim|x|→∞V1(x) = 0. Inspired by previous work of Li et al.(2006), Pankov(2005)and Szulkin and Weth(2009), we develop a more direct approach to generalize the main result of Szulkin and Weth(2009) by removing the "strictly increasing" condition in the Nehari type assumption on f(x, t)/|t|. Unlike the Nahari manifold method, the main idea of our approach lies on finding a minimizing Cerami sequence for the energy functional outside the Nehari-Pankov manifold N0 by using the diagonal method. 展开更多
关键词 Schrodinger equation non-Nehari manifold method asymptotically periodic ground state solutions of Nehari-Pankov type
原文传递
Least energy solutions for semilinear Schrdinger equation with electromagnetic fields and critical growth 被引量:2
9
作者 TANG ZhongWei WANG YanLi 《Science China Mathematics》 SCIE CSCD 2015年第11期2317-2328,共12页
We study a class of semilinear SchrSdinger equation with electromagnetic fields and the nonlinearity term involving critical growth. We assume that the potential of the equation includes a parameter A and can be negat... We study a class of semilinear SchrSdinger equation with electromagnetic fields and the nonlinearity term involving critical growth. We assume that the potential of the equation includes a parameter A and can be negative in some domain. Moreover, the potential behaves like potential well when the parameter A is large. Using variational methods combining Nehari methods, we prove that the equation has a least energy solution which, as the parameter A becomes large, localized near the bottom of the potential well. Our result is an extension of the corresponding result for the SchrSdinger equation which involves critical growth but does not involve electromagnetic fields. 展开更多
关键词 semilinear Schr6dinger equation least energy solution critical growth electromagnetic fields
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部