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51.
对箱梁各翼板(顶板、悬臂板、底板)分设不同剪力滞广义纵向位移,其横向分布均取二次抛物线形式,并引入载荷横向位置参数η,以分析载荷横向变位对剪力滞效应的影响.运用能量变分原理,建立剪力滞控制微分方程,求解了简支梁和悬臂梁在均布载荷作用下的控制微分方程的解.算例分析表明:载荷横向变位改变直接承受载荷的翼板的正负剪力滞特性,对非直接承载翼板只改变其应力幅度;箱梁横向框架效应对直接承载翼板纵向应力的贡献远远大于剪切变形.与块体有限元分析结果较吻合,表明该算法能较准确分析载荷横向变位作用下箱梁剪力滞的变化规律. 相似文献
52.
Ibrahim A. Abbas 《基于设计的结构力学与机械力学》2015,43(4):501-513
The model of generalized thermoelasticity proposed by dual phase lag (DPL), is applied to study the thermoelastic interactions in an infinite fiber-reinforced anisotropic medium with a circular hole. A decaying with time thermal field on the boundary of the hole, which is stress free, causes the thermoelastic interactions. The solutions for displacement, temperature, and stresses are obtained with the help of the finite element procedure. The effects of the reinforcement on temperature, stress, and displacement are studied. The exact solution in the case of isotropic medium is discussed explicitly. The accuracy of the finite element method validated by comparing between the finite element and exact solutions for absence the reinforcement. 相似文献
53.
Lu Chuanrong Zhejiang University of Finance Economics Zhejiang University Hangzhou China. 《高校应用数学学报(英文版)》2005,20(3):331-337
§1Introductionandresults A2-parameterGaussianprocess{Z(t,s);t,s≥0}iacalleda2-parameterfractional Wienerprocesswithorderα(0<α<1),ifZ(0,0)=0a.s.EZ(s,t)=0anditscovariance EZ(t1,s1)Z(t2,s2)={|t1|2α+|t2|2α-|t2-t1|2α}{|s1|2α+|s2|2α-|s2-s1|2α}/4.LetR=[x1,x2]×[y1,y2],DT={(x,y)∶0≤x,y≤bT,xy≤T}.Let0相似文献
54.
Detection of drug vapors and volatile products of their decomposition is an important, and sometimes the only way to determine the presence of illegal drug traces at the surface of mail items, documents, hands and banknotes. This paper gives the results of experimental studies on the effect of UV irradiation on the sensitivity of a vapor phase detection of cocaine of different origin by a technology of ion mobility increment spectrometry (IMIS). It is shown that the influence of UV irradiation on the surface of cocaine hydrochloride and crack increases the amplitude of IMIS signals by about eight times. We analyzed ions emerged by photolysis of tested cocaine samples using mass-spectrometry with atmospheric pressure ionization (API-MS). The assumption is made about structural formula of volatile products of photolysis of crack and cocaine hydrochloride. By the results of API-MS and IMIS studies on photolysis of cocaine samples it is assumed that compound C10H15NO3 with a molecular weight of 197 amu and ecgonidine methyl ester with a molecular weight of 181 amu are responsible for the increase of an amplitude of IMIS signals upon UV irradiation of samples of crack and cocaine hydrochloride. 相似文献
55.
M. Vaičiulis 《Lithuanian Mathematical Journal》2009,49(2):222-233
In this paper, we introduce an increment ratio statistic (IR
N,m
) based estimator for estimation of the tail index of a heavy-tailed distribution. For i.i.d. observations depending on the
zone of attraction of an α-stable law (0 < α < 2), the IR
N,m
statistic converges to a decreasing function L(α) as both the sample size N and bandwidth parameter m tend to infinity. We obtain a rate of decay of the bias EIR
N,m
−L(α) and mean square error E(IR
N,m
−L(α))2. A central limit theorem (IR
N,m
−EIR
N,m
)⟹ (0,σ2(α)) is also obtained. Monte Carlo simulations show that our tail index estimator has quite good empirical mean square error
and, unlike the Hill estimator, is not so sensitive to a change of bandwidth parameter m.
The research was partially supported by the Lithuanian State Science and Studies Foundation, grant No. T-25/08. 相似文献
56.
考虑资本闲置的多年时滞人力资本投入占用产出模型 总被引:1,自引:1,他引:0
人力资本理论强调的是由教育所新增的人力资本对经济增长的决定作用.为了规划与中国经济持续增长相适应的人力资本需求,建立了一个新颖的考虑资本闲置的多年时滞投入占用产出模型.为了考虑人力资本时滞长的特点以及人力资本占用的损耗补偿,在斯通人口投入产出模型和Leontief动态投入产出模型基础上,提出了多年时滞人力资本投入占用产出模型.将LDS模型推广为考虑资本闲置的多年时滞人力资本投入占用产出模型,以便考虑影响教育产出的外生因素,并推导出既适于产出增加也适于产出减少的正解.应用上,预测至2015年的各种教育水平人力资本的总量和部门需求,发现高级人力资本短缺和人才行业结构不合理是经济发展需要解决的重要问题. 相似文献
57.
Lagwise dynamic characteristics of a wind turbine blade subjected to unsteady aero- dynamic loads are studied in this paper. The partial differential equations governing the coupled longitudinal-transverse vibration of the blade with large bending deflection are obtained by ap- plying Hamilton's principle. The modal problem of the coupled vibration is handled by using the method of numerical integration of Green's function. Influences of the rotating speed, the pitch angle, the setting angle, and the aerodynamic loads on natural frequencies are discussed. Results show that: (I) Lagwise natural frequencies ascend with the increase of rotating speed; effects of the rotating speed on low-frequencies are dramatic while these effects on high-frequencies become less. (2) Influences of the pitch angle on natural frequencies are little; in the range of the normal rotating speed, the first frequency ascends with the increase of the absolute value of the pitch angle, while it is contrary to the second and third frequencies. (3) Effects of the setting angle on natural frequencies depend on the rotating speed; influences are not significant at low speed, while they are dramatic on the first frequency at high speed. (4) Effects of the aerodynamic loads on natural frequencies are very little; frequencies derived from the model considering aerodynamic loads are smaller than those from the model neglecting aerodynamic loads; relative errors of the results corresponding to two models ascend with the increase of the absolute value of the setting angle. 相似文献
58.
制作了钢筋混凝土简支箱梁模型,试验包括模型梁开裂范围内的加载及开裂后的加载。在开裂范围内,对该试验梁分别进行了顶板满布均布荷载、均布荷载作用于肋板上方、集中力作用于跨中以及对称集中力作用下的加载;对开裂后的试验梁,进行了对称集中力作用下的加载。用应变采集仪与电脑连接,并用半桥测量,温度自补偿方法测取应变值,采用百分表测试梁体挠度,采用读数显微镜观测裂缝。测量得到应力、应变的分布规律,验证了钢筋混凝土箱梁中存在剪滞效应。试验结果与考虑混凝土非线性的有限段法的计算结果吻合较好,验证了有限段法在混凝土箱梁剪滞效应分析中的适用性。 相似文献
59.
Adaptive lag synchronization and parameter identification of fractional order chaotic systems 下载免费PDF全文
This paper proposes a simple scheme for the lag synchronization and the parameter identification of fractional order chaotic systems based on the new stability theory. The lag synchronization is achieved and the unknown parameters are identified by using the adaptive lag laws. Moreover, the scheme is analytical and is simple to implement in practice. The well-known fractional order chaotic Lü system is used to illustrate the validity of this theoretic method. 相似文献
60.