Articles in press have been peer-reviewed and accepted, which are not yet assigned to volumes /issues, but are citable by Digital Object Identifier (DOI).
Display Method:
Event-Based State Estimation of Complex-Value Neural Networks With Mixed Delays
LIU Feiyang, LI Bing
 doi: 10.21656/1000-0887.420359
Abstract(43) HTML(33) PDF(10)
Abstract:
The event-based state estimation problem is investigated for a class of complex valued neural networks with mixed delays. By utilizing the measurement output, a novel event-triggering scheme is introduced to reduce the frequency of updating while ensuring estimation performance. A waiting time is first employed to avoid the Zeno phenomenon. By using the Lyapunov direct method and some properties of complex-valued matrix, a sufficient criterion is established to guarantee the globally asymptotic stability for the error system. The weighted parameters and gain matrices are designed by resorting to the feasible solution of matrices inequalities. Finally, a numerical example and its simulations are presented to illustrate the effectiveness of proposed approach.
Dynamic Modeling of Spatial Cooperation of Dual Mobile Manipulators
DONG Fangfang, YU Bin, ZHAO Xiaomin, CHEN Shan
 doi: 10.21656/1000-0887.420223
Abstract(46) HTML(31) PDF(3)
Abstract:
The complex non-linear coupling generated in spatial cooperation process of mobile manipulators, makes it extremely tedious to model directly for spatial cooperative systems with Lagrange equation or Newton-Euler method. A dynamic modeling method, combining Udwadia-Kalaba (U-K) method with Lagrange equation, for spatial cooperation of dual mobile manipulators is explored. The load was simplified as a connecting link while modeling. The center of load was selected to be disconnected for decomposition, so that the lack of constraint information between the end joint angle and the end link angle caused by disconnecting the end joint of the manipulator is avoided; the segmented two subsystems were modeled with Lagrange equation, thus, the dynamic model of subsystems was obtained. The inherent geometric relationships of cooperative system were introduced in the form of constraints, and the U-K method was applied to obtain the dynamic model of cooperative system. The computation for modeling is reduced. Finally, the accuracy of the model was verified by numerical simulation.
Dynamic Analyses of the Assembling Process of Ultra-Large Structures by a Space Robot
WANG Qisheng, JIANG Jianping, LI Qingjun, JIANG Guoqi, DENG Zichen
 doi: 10.21656/1000-0887.420244
Abstract(36) HTML(28) PDF(4)
Abstract:
Structural vibrations of the ultra-large structures during on-orbit assembly should be prevented to the maximum extent, because of the extreme flexibility and low natural frequencies. The assembling process is divided into four stages: grasping stage, position-attitude adjusting and stabilizing stage, mounting stage, and crawling stage. This paper focuses on the mounting stage, and a collinear assembly trajectory planning method is proposed to prevent structural vibrations. First, a dynamic model of the on-orbit assembly system (including the main structure, the space robot, and the assembling structure) is established based on natural coordinate formulation and absolute node coordinate formulation. Second, the requirements of collinear assembly are transformed into a trajectory planning problem of the space robot. The distance from the center of mass of the space robot to the main structure should remain unaltered, which is main idea of the proposed collinear assembly method. Numerical simulation results show that the proposed assembly method can effectively prevent the transverse motions of the ultra-large structure and reduce the required grasping moment. Finally, the influences of the system parameters on the dynamic response of the assembly process are studied, which provides a theoretical basis for the on-orbit assembly of ultra-large spacecraft.
Effects of Cone Angle on Nonlinear Vibration Response of Functionally Graded Shells
ZHANG Yuhang, LIU Wenguang, LIU Chao, LÜ Zhipeng
 doi: 10.21656/1000-0887.420273
Abstract(31) HTML(22) PDF(5)
Abstract:
The nonlinear vibration responses of functionally graded shells with different cone angles under external load are studied in this paper. Firstly, the Voigt model was employed to describe the physical properties along the thickness direction of FGMs conical shells. Then, the motion equations were derived based on the first shear deformation theory, von Kármán geometric nonlinearity and Hamilton’s principle. Next, the Galerkin method was applied to discretize the motion equations and the governing equations was simplified into a single degree of freedom nonlinear vibration differential equation based on the Volmir’s assumption. Finally, the nonlinear motion equation was solved by the harmonic balance method and Runge-Kutta method, and the amplitude frequency response characteristic curves of FGMs conical shell were obtained. The effects of different material distribution function and the ceramic volume fraction exponents on the amplitude frequency response curve of conical shell were discussed. The bifurcation diagrams of conical shells with different cone angles and time process diagrams and phase diagrams with different excitation amplitudes were described. The motion characteristic was characterized by Poincaré map. The results show that FGMs conical shell presents the nonlinear characteristics of "hardening" spring. The chaotic motion of FGMs conical shell is restrained and FGMs conical shell is not prone to produce motion instability with the increase of cone angle. The motion of FGMs conical shell presents a process from periodic motion to multi-periodic motion and then to chaos with the increase of excitation amplitude.
Magneto-Thermoelastic Coupling Dynamic Response of Narrow Long Thin Plate Considering Memory Effect and Size Effect
MA Yongbin, LI Dongsheng
 doi: 10.21656/1000-0887.420200
Abstract(48) HTML(30) PDF(5)
Abstract:
The dual-phase-lag thermoelasticity theory with memory-dependent derivative can perfectly describe the phenomenon of non-Fourier heat conduction, nevertheless, it has not been comprehensively considered: the mechanical response of materials aroused by the size-dependent effects and the influence of multiple coupling effects such as magnetic, thermal and elastic fields. A dual-phase-lag thermoelasticity theory considering memory dependent effect and non-local effect is established. Based upon the revised theory, the magneto-thermoelastic coupling problem of a thin plate subjected to a cyclical heat source is investigated. First the governing equations of the problem are formulated. Then combining the boundary conditions and initial conditions, the solution of the problem is obtained by using Laplace transform and inverse transform techniques. Last, the effects of magnetic field, phase lag, time-delay, kernel function, non-local effect and time on the dimensionless quantities were investigated respectively, which provided a powerful reference for the dynamic response of micro-scale materials.
Interface Model and Interphase Model for Predicting the Effective Elastic Properties of Nano-Fiber Composites
CUI Chunli, XU Yaoling
 doi: 10.21656/1000-0887.420231
Abstract(39) HTML(22) PDF(2)
Abstract:
The effective bulk modulus and the effective in-plane shear modulus of nano-fiber composites are investigated using interface model and interphase model based on the generalized self-consistent method, the closed-form analytical solutions of effective bulk modulus and all equations for predicting effective in-plane shear modulus by numerical method based on the two models are presented. Using the interface model, interface effects of the effective bulk modulus and the effective in-plane shear modulus are discussed by use of numerical examples. Further research demonstrates that the analytical formula of the effective bulk modulus and the numerical results of the effective in-plane shear modulus derived from the interface model can be obtained again from the interphase model. An example of aluminium containing nano voids shows that the effective bulk modulus and the effective in-plane shear modulus predicted by the interface model have large deviations from that of the interphase model when the void radius is small, however for larger void radius, the difference is small.
A Double Projection Algorithm for Solving Non-Monotone Variational Inequalities
WANG Xiaoting, LONG Xianjun, PENG Zaiyun
 doi: 10.21656/1000-0887.420414
Abstract(34) HTML(24) PDF(10)
Abstract:
The projection algorithm is one of the main methods to solve variational inequality problems. At present, the research on projection algorithms usually requires the assumption that the mapping is monotone and Lipschitz continuous, but in practical problems, these assumptions are often unsatisfied. In this paper, a new double projection algorithm for solving non-monotone variational inequality problems is proposed by using the line search method. Under the assumption that the mapping is uniformly continuous, it is proved that the sequence generated by the algorithm strongly converges to a solution of variational inequalities. The numerical experiments illustrate effectiveness and superiority of the proposed algorithm.
Structural Instantaneous Frequency Identification Based on Fractional Fourier Transform
LU Lian, REN Weixin, WANG Shidong
 doi: 10.21656/1000-0887.420241
Abstract(38) HTML(37) PDF(5)
Abstract:
In order to identify the instantaneous frequency of time-varying signals, this paper derives the theoretical relationship between the frequency in a signal and rotational angle α in a fractional Fourier transform. It is demonstrated that the fractional Fourier transform is actually an algorithm of ordinary Fourier transform combined with telescopic translation window. A general expression of signal instantaneous frequency in the fractional Fourier domain is thereafter formulated so that structural instantaneous frequency can be extracted accordingly. The feasibility and reliability of proposed method is verified by a simulated nonlinear frequency modulation signal and a numerical example of a three-degree-of-freedom damped time-varying structure system. The results show that the proposed method is in good agreement with the theoretical values and the method has a certain degree of anti-noise capability. Subsequently, the proposed method is capable of identifying the instantaneous frequency of time-varying structures.
State Feedback Generalized H2 Control for Continuous Integrated Control System
SUN Fengqi
 doi: 10.21656/1000-0887.420169
Abstract(39) HTML(21) PDF(8)
Abstract:
Based on Lyapunov stability theory, matrix analysis method, linear matrix inequality methods, etc, the generalized H2 control of singularly perturbed uncertain control systems with time-varying delay and control input and disturbance input is studied. A memory state H2 generalized controller is designed, the decision theorem of the specific design method given. Quoting new lemma for delay dependent and delay independent cases, the relatively less conservative stability criterion is derived. The obtained results are linearized, the selected numerical examples are used to verify the effectiveness and feasibility to the derived conclusions. It is pointed out that the closed-loop system is asymptotically stable in the whole range from zero to singular perturbation upper bound, which expands the generalized H2 stability space and reduces the L2-L performance index. By comparing the stability state parameter index with the related literatures, it is shown that the proposed method has certain advantages and less conservatism, and is suitable for standard and non-standard cases.
Explicit Solutions for Wave Equation of Nonlinear Elastic Rod
GUO Peng, TANG Rongan, SUN Xiaowei, HONG Xueren, SHI Yuren
 doi: 10.21656/1000-0887.420245
Abstract(46) HTML(38) PDF(6)
Abstract:
The sine-cosine method is applied to the wave equation of nonlinear elastic rod, and some new periodic and soliton solutions of the equation is obtained (material constant n is a constant different from 1). The graphs of some solutions are given through math software. The results are helpful to further research on existence of solitary waves in the nonlinear elastic rod.
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2022, Volume 43, Issue 7 publish date:July 01 2022
Display Method:
Fluid Mechanics
Research on Deposition and Orientation Characteristics of Cylindrical Particles in Gas-Solid 2-Phase Turbulent Flow in Curved Tubes
LI Liang, SHI Ruifang, LIN Jianzhong
2022, 43(7): 707-718.   doi: 10.21656/1000-0887.420320
Abstract(120) HTML(53) PDF(56)
Abstract:

In the cases of Reynolds number Re=3 000~50 000, Stokes number Stk=0.1~10, Dean number De=1 400~2 800, the orientation and deposition characteristics of cylindrical particles with aspect ratio β=2~12 in turbulent flow in curved tubes were studied. The motion of cylindrical particles was described under the slender body theory combined with Newton’s 2nd law. The orientation distribution function of cylindrical particles was given by the Fokker Planck equation. The mean velocity of the flow was obtained by solving the Reynolds-averaged Navier-Stokes equation and the Reynolds stress equation. The turbulent fluctuating velocity acting on particles was described with the kinetic simulation sweeping model. By solving the equations of the turbulent flow, the particle motion and the orientation distribution function, the orientation distributions of particles on the cross sections in different axial positions and the outlet were obtained and analyzed. The effects of various parameters on the deposition rate of particles were discussed. The results showed that, the main axis of particles turns toward the flow direction with the increase of Stk and β, and the decrease of De and Re. The deposition rate of particles increases with De, Re and β. However, it shows a non-monotonic trend with the change of Stk

. The work has reference values for practical engineering application.

Analysis and Simulation of Natural Frequencies of Slightly Curved Pipes
YUAN Jiarui, DING Hu, CHEN Liqun
2022, 43(7): 719-726.   doi: 10.21656/1000-0887.420299
Abstract(98) HTML(43) PDF(54)
Abstract:

For the transverse vibration of slightly curved pipes, a dynamic mechanical model based on the Timoshenko beam theory was established for the 1st time. The natural vibration characteristics of slightly curved pipes under the influence of the fluid flow were analyzed. With the generalized Hamiltonian principle, the governing equation of the transverse vibration of slightly curved pipes under the fluid-structure coupling effect was derived. Based on the Galerkin truncation, the natural frequencies of slightly curved pipes were obtained with the generalized eigenvalue method. Effects of the fluid velocity and the initial deflection on the natural vibration characteristics of the pipe were studied. The equivalent stiffness and damping method-based finite element simulation of the natural vibration of the slightly curved pipe was developed. Then through the finite element numerical simulation, the results of the Galerkin truncation method and the effectiveness of the Timoshenko model were verified. The work shows that, both the fluid velocity and the initial deflection have significant effects on the natural frequencies of slightly curved pipes.

Mesoscopic Numerical Study on Flow Boiling Heat Transfer Performance in Channels With Multiple Rectangular Heaters
LI Yingxue, WANG Haoyuan, LOU Qin
2022, 43(7): 727-739.   doi: 10.21656/1000-0887.420325
Abstract(64) HTML(53) PDF(25)
Abstract:

The flow boiling phenomenon in a channel with multiple rectangular heaters under a constant wall temperature was numerically studied with the lattice Boltzmann method. The effects of spacings between heaters, heater lengths and heater surface wettabilities on the bubble morphology, the bubble area and the heat flux on the heater surface, were studied. The results show that, the bubble growth rate increases with the spacing between heaters. The larger the bubble area is, the earlier the nucleated bubbles will leave the heater surface. The corresponding boiling heat transfer performance increases by 12% with the spacing between heaters growing from 250 lattices to 1 000 lattices. On the other hand, the longer the heater length is, the earlier the bubble will nucleate and leave the heater surface, and the better the boiling heat transfer performance will be. The boiling heat transfer performance increases by 13% with the heater length rising from 16 lattices to 22 lattices. In addition, the bubble nucleates later on the hydrophilic surface than on the hydrophobic surface. Compared with the hydrophilic surface, the hydrophobic surface retains residual bubbles after the leaving of bubbles from the heater. The average heat flux and the bubble area of the hydrophilic surface are less than those of the hydrophobic surface. With the contact angle changing from 77° to 120°, the heat transfer performance increases by 26%. Finally, the orthogonal test results indicate that, the wettability of the heat exchanger surface has the greatest influence on the flow boiling heat transfer performance, while the heater length has the least influence.

Solid Mechanics
Size-Dependent Effects of Micro-Nano Mindlin Plates Based on the Couple Stress Theory
XUE Jianghong, HE Zanhang, XIA Fei, LI Zerong, JIN Fusong, YANG Peng
2022, 43(7): 740-751.   doi: 10.21656/1000-0887.420171
Abstract(54) HTML(32) PDF(20)
Abstract:

A Mindlin plate theory for micro-nano structures was proposed based on the couple stress theory. A length parameter was introduced to consider the size effect, and the constitutive equations for the micro-nano Mindlin plate were derived in view of the transverse shear deformation. The buckling and free vibration governing equations in terms of displacements and the slope functions of the shear deformation micro-nano plate were further deduced with the force equilibrium conditions. The analytical solutions of buckling and free vibration for the shear deformation micro-nano plate were obtained through separation of the displacement and rotation variables in space and time domains. Two scenarios of boundary conditions were analyzed: SSSS (simply supported by 4 edges) and SCSC (2 opposite edges simply supported and other 2 edges clamped). A MATLAB program was developed to compute the critical buckling and natural frequencies with different values of dimensional parameters, aspect ratios and length-to-thickness ratios. The research results, in comparison with those from the ABAQUS finite element analysis and previous literatures, are consistent with the latter ones. The examples show that, the size effects significantly influence the buckling load and the natural frequency.

Williams Elements With Generalized Degrees of Freedom for Crack Tip SIFs Analysis Under Crack Surface Distributed Loading
XU Hua, CAO Zheng, ZOU Yunpeng, YANG Lüfeng
2022, 43(7): 752-760.   doi: 10.21656/1000-0887.420317
Abstract(80) HTML(57) PDF(18)
Abstract:

Service with cracks is the normal state of engineering structures. Due to the fluid invading into the crack, the crack surface is loaded directly, which makes the crack further expand, and even affects the safety of the structure. In the analysis of fracture problems, according to the Williams element with generalized degrees of freedom (W element), the Williams series was used to establish the displacement field of the singular zone around the crack tip, and the stress intensity factors (SIFs) can be directly obtained by solving the generalized stiffness equation with high precision and high efficiency. However, the W element needs to satisfy the free boundary condition of the crack surface in the singular zone, so it is limited in the analysis of crack surface loading. Based on the SIFs reciprocity, the loading on the crack surface is equivalent to the concentrated force on the crack surface at the periphery of the equivalent singular zone, so the loading on the crack surface in the singular zone can be avoided, and the W element can be easily used for calculation. The numerical examples show that, the size of the equivalent singular zone is 1/20 of the crack length, the suggested equivalent load coefficient P is 2.0, and the calculation accuracy of the W element meets the error limit of 1%. The equivalent treatment method for the analysis of crack surface loading in the singular zone is reasonable and universal, and overcomes the limitation on the W element in analysis of the loading problem on crack surface.

Stochastic Model Updating Based on Kriging Model and Lifting Wavelet Transform
WU Yucheng, YIN Hong, PENG Zhenrui
2022, 43(7): 761-771.   doi: 10.21656/1000-0887.420128
Abstract(56) HTML(33) PDF(17)
Abstract:

In order to improve the efficiency of stochastic model updating and reduce the amount of calculation, a stochastic model updating method based on Kriging model and lifting wavelet transform was proposed. Firstly, the lifting wavelet transform was performed on the acceleration frequency response function, and the 5th-level approximate coefficients were extracted to replace the original frequency response function; secondly, the Latin hypercube sampling was applied to sample the parameters to be updated and the corresponding approximate coefficients as the outputs to build the Kriging model. A butterfly optimization algorithm with Lévy flight (LBOA) was proposed and used to improve the accuracy of  Kriging model; finally, with the goal of minimizing the Wasserstein distance, the mean values of the parameters to be updated were solved with the whale optimization algorithm. The results of the test function show that, the LBOA greatly improves in terms of optimization, convergence accuracy and stability. The updating errors of the numerical examples are all less than 0.4%, and indicate the high accuracy and efficiency of the proposed model updating method.

Prediction of the Macroscopic Mechanics Properties of Recycled Aggregate Concrete Based on the Mesoscopic Equivalence Theory
CHEN Haiyu, XU Fuwei
2022, 43(7): 772-782.   doi: 10.21656/1000-0887.420079
Abstract(73) HTML(37) PDF(25)
Abstract:
Prediction of the influence of each component of recycled aggregate concrete on the macroscopic mechanics properties of recycled aggregate concrete is a way to develop the basic mechanics properties of recycled aggregate concrete. For this purpose, a meso-equivalent model was established according to the meso-structure composition of recycled aggregate concrete. Based on the torsional deformation theory, the meso-inclusion theory, the elastic equivalent thought and the M-T model, the prediction model for macroscopic mechanics properties of recycled aggregate concrete composed of natural aggregate, old interface, old cement mortar, new interface and new cement mortar, was deduced. The prediction results show that, with the increase of the recycled aggregate replacement rate, the content of cement mortar and the porosity of recycled aggregate concrete rise, resulting in the increase of Poisson’s ratio of recycled aggregate concrete, and the decreases of the elastic modulus, the shear modulus and the volume modulus. The model well predicts the changing trend of the macroscopic mechanics properties of recycled aggregate concrete with the increase of the recycled aggregate replacement rate, and provides a simple and practical new way to the research and analysis of the basic mechanics properties of recycled aggregate concrete.
Applied Mathematics
Sampling Consensus of 2nd-Order Multi-Agent Systems Based on Time-Varying Topology
ZHENG Liying, YANG Yongqing, XU Xianyun
2022, 43(7): 783-791.   doi: 10.21656/1000-0887.420220
Abstract(59) HTML(46) PDF(25)
Abstract:

The sampling consensus of 2nd-order multi-agent systems with time-varying topology was investigated based on the constant position difference and the consistent speed. Firstly, the virtual leader was introduced and the sampling consensus problem of multi-agent systems was transformed into the stability problem of the corresponding error system. Secondly, with estimation of the sampling errors, the influence of sampling errors on system consistency was studied. Finally, by virtue of the Lyapunov stability theory, the stability of the constructed error system was analyzed, and a sufficient condition for the stability of the error system was given. The numerical simulation results verify the effectiveness and correctness of the theoretical analysis.

SQP Methods for Mathematical Programs With Switching Constraints
LUO Meiling, LI Gaoxi, HUANG Yingquan, LIU Liying
2022, 43(7): 792-801.   doi: 10.21656/1000-0887.420294
Abstract(62) HTML(41) PDF(28)
Abstract:

The mathematical program with switching constraint (MPSC) problem makes a new-type optimization issue in recent years. Due to the existence of switching constraints, the common constraint specification is not satisfied, so that the convergence results of existing algorithms can not be directly applied to this problem. The sequential quadratic programming (SQP) method was applied to solve the problem, and to prove that the clustering point of the solution sequence of the subproblem is the Karush-Kuhn-Tucker point of the original problem under the linear independent constraint specification with the switching constraint. At the same time, in order to improve the relationship between stationary points, the equivalence between the strong stationary point and the KKT point was proved. Finally, the numerical results show that, the sequential quadratic programming method is feasible to deal with this type of problems.

An Improved 3rd-Order WENO Scheme Based on a New Reference Smoothness Indicator
WANG Yahui
2022, 43(7): 802-815.   doi: 10.21656/1000-0887.420194
Abstract(129) HTML(37) PDF(25)
Abstract:

In order to meet the requirement of high accuracy and high resolution in computational fluid dynamics (CFD), a new reference smoothness indicator was proposed to reduce the numerical dissipation of the classical 3rd-order weighted essentially non-oscillatory (WENO) scheme. The construction method is different from the classical WENO-Z scheme. It is obtained through the L2-norm approximation of the derivatives of the reconstruction polynomials of the whole global stencil, and the linear combination of the derivatives of the reconstruction polynomials on the candidate sub-stencils. With this calculation method, higher-order reference smoothness indicators can be obtained than the WENO-Z scheme. In addition, different reference smoothness indicators can be obtained by change of the value of free parameter

\begin{document}$ \varphi$\end{document}

. A series of numerical examples prove the effectiveness of the reference smoothness indicator.

Global Existence of Solutions and Lower Bound Estimate of Blow-Up Time for the Keller-Segel Chemotaxis Model
LI Yuanfei
2022, 43(7): 816-824.   doi: 10.21656/1000-0887.420109
Abstract(149) HTML(59) PDF(31)
Abstract:

A macroscopic nonlinear Keller-Segel model for chemotactic cell migration was considered, where the existence region of the model is a bounded convex one on

\begin{document}$\varOmega\subset\mathbb{R}^N(N\geqslant2)$\end{document}

. The global existence of the solution on

$\varOmega\subset\mathbb{R}^3$

was obtained by means of the energy estimate method. The lower bound of the blow-up time was proved for

$N=3 $

and

$N=2$

.

Damage Identification for Bridge Structures Based on the Wavelet Neural Network Method
XIAO Shu-min, YAN Yun-ju, JIANG Bo-lan
2016, 37(2): 149-159.   doi: 10.3879/j.issn.1000-0887.2016.02.004
[Abstract](1172) [PDF 5386KB](743)
摘要:
桥梁结构在服役期间会承受复杂的荷载,长期使用会不可避免地出现各种损伤。若这些损伤不能被及时发现和适当处理,将有可能造成严重的事故。因此,桥梁结构的局部小损伤识别对于其及时检修有重要意义。通常,损伤结构的全局动态特性测试可能对局部的结构损伤不敏感,特别是对小损伤,这就需要从结构动态响应信号中提取对损伤更敏感的特征量。建立了桥梁结构的有限元模型并进行动力特性分析;采用小波包分析方法处理结构动态响应信号以构造结构损伤指标,并结合结构损伤指标和人工神经网络方法进行桥梁结构的损伤定位.
The PseudoExcitation Method and Its Industrial Applications in China and Abroad
LIN Jia-hao, ZHANG Ya-hui, ZHAO Yan
2017, 38(1): 1-31.   doi: 10.21656/1000-0887.370578
[Abstract](1227) [PDF 1039KB](1423)
摘要:
《随机振动的虚拟激励法》自1985年正式发表以来,逐渐得到许多工程领域的认可和采用,解决了很多重要而困难的工程问题.该方法不但被国内某些工程规范所推荐,而且被3种国际工程手册成章刊载,在国际上亦占有了一席之地.该文是笔者参考了数百篇国内外论文,依据其中一部分在11个工程领域对虚拟激励法的应用和一些学者的评论所撰写的综述.借以让更多工程技术人员和研究者对虚拟激励法有较为全面的了解,以结合各自工程领域更有效地开展对随机振动理论和方法研究成果的应用和发展.
Uncertainty Quantification for System Identification Utilizing the Bayesian Theory and Its Recent Advances
YAN Wang-ji, CAO Shi-ze, REN Wei-xin.
2017, 38(1): 44-59.   doi: 10.21656/1000-0887.370571
[Abstract](1153) [PDF 647KB](950)
摘要:
受测试误差、建模误差、数值离散化以及环境变异等因素的影响,结构系统识别过程不可避免地存在不确定性,因此有必要引入概率统计方法来提高其鲁棒性,为工程结构安全监测提供更为可靠的结果.近年来,Bayes(贝叶斯)方法因为其诸多优势在系统识别领域受到了广泛关注.该文梳理了Bayes系统识别的历史脉络和研究进展.从Bayes系统识别的理论框架出发,分析了量化系统识别不确定性两类方法的适用条件与局限性.此外,文章综述了Bayes方法在模态参数识别、有限元模型修正以及结构损伤识别方面进行不确定性分析的理论、实现及其应用.最后对基于Bayes方法进行系统识别研究的发展趋势做出了展望.
Convergence Results on Heat Source for 2D Viscous Primitive Equations of Ocean Dynamics
LI Yuanfei
2020, 41(3): 339-352.   doi: 10.21656/1000-0887.400176
[Abstract](726) [FullText HTML](81) [PDF 405KB](293)
摘要:
考虑了在一个柱形区域上的海洋动力学中二维黏性方程组解的收敛性.在此模型中存在一个关键的参数就是热源,众多周知,它的存在可能会使流体内层之间出现共振从而导致不稳定.因此,通过推导方程组的先验界,得到了方程组的解对热源自身的收敛性.
Detached-Eddy Simulation of Flow Past Tandem Cylinders
ZHAO Wei-wen, WAN De-cheng
2016, 37(12): 1272-1281.   doi: 10.21656/1000-0887.370546
[Abstract](830) [PDF 3862KB](614)
摘要:
主要开发了SST-DES和SST-DDES两种分离涡方法,并集成到基于开源代码平台OpenFOAM开发的CFD求解器naoe-FOAM-SJTU中.选用高Reynolds(雷诺)数下串列双圆柱绕流问题作为标准算例来验证所开发的分离涡方法.该标准算例此前在美国国家航空航天局兰利研究中心的两个不同风洞做过物理试验.该研究将数值模拟得到的时均流场信息和一些其他物理量同物理试验结果比较,同时讨论分析了三维瞬态流场结构.结果表明该文开发的SST-DES和SST-DDES分离涡方法能够解决高Reynolds数下有大量流动分离的复杂流动问题.
Some New Advances in the Probability Density Evolution Method
LI Jie, CHEN Jian-bing
2017, 38(1): 32-43.   doi: 10.21656/1000-0887.370336
[Abstract](1190) [PDF 683KB](2058)
摘要:
介绍了随机动力系统中概率密度演化理论的基本方程与求解方法〖CX4〗.〖CX〗在此基础上,论述了广义概率密度演化方程求解的若干新进展,包括群演化方程及其求解、概率空间剖分的理性准则、点集加密技术与信息拓展方法等.
Simulation of Multi-Hydrofracture Horizontal Wells in Shale Based on the Extended Finite Element Method
CHEN Jun-bin, WEI Bo, XIE Qing, WANG Han-qing, LI Tao-tao, WANG Hao
2016, 37(1): 73-83.   doi: 10.3879/j.issn.1000-0887.2016.01.006
[Abstract](1008) [PDF 1871KB](688)
摘要:
页岩储层水平井分段多簇压裂簇间距优选是压裂技术的关键,建立了水力压裂流固耦合数学模型,基于扩展有限单元法模拟多条裂缝的扩展过程,研究多条裂缝同时扩展的转向规律,以及应力干扰、水平主应力差、裂缝间距等因素与裂缝转向角度的关系.结果表明:应力干扰作用对裂缝宽度具有限制作用,单条裂缝张开宽度比两条裂缝的大;裂缝转角随应力差的减小而增大,随压裂时间的增加而增大.簇间距越小,应力干扰越强,转角越大,综合主缝均匀扩展、支撑剂填充以及复杂裂缝网络形成等条件,确定最优簇间距为30~40 m.多条裂缝同时扩展时,中间裂缝会受到两边裂缝的限制作用,簇间距越小,限制作用越强,裂缝发育时间越长,扩展速度越慢.
Optimization of Multimodal Transport Paths for Refrigerated Containers Under Carbon Emission Restriction
LIU Song, SHAO Yiming, PENG Yong
2020, 41(2): 204-215.   doi: 10.21656/1000-0887.400159
[Abstract](791) [FullText HTML](80) [PDF 1329KB](400)
摘要:
为了降低碳排放限制下的冷藏集装箱多式联运成本,实现节能减排的目的,高效的路径选择至关重要.该文基于碳排放限制的视角,针对多式联运网络中铁路和水路运输具有发班时间限制,以及冷藏集装箱需要考虑制冷费用、货损货差的特点,建立了在碳排放限制下以总成本最低为目标的优化模型.构建总成本时不仅考虑了运输费用和转运费用,还考虑了受发班时间影响而动态变化的冷藏费用和货损费用.设计了遗传算法求解,并进行了算例分析.结果表明:通过该模型和算法,可根据决策者的要求快速地选出成本最少的运输方案,为决策者提供决策支持.
Analysis on Shear Deformation and Shear-lag Effects on Twin-Cell Box Girders
ZHANG Hui, ZHANG Yu-yuan, ZHANG Yuan-hai, LI Wei
2016, 37(8): 791-803.   doi: 10.21656/1000-0887.370056
[Abstract](840) [PDF 589KB](831)
摘要:
基于各个翼板选取不同的最大剪切转角差为剪力滞广义位移,应用能量变分原理分别推导出了考虑和不考虑剪切变形时单箱双室截面控制微分方程组,结合边界条件给出了箱梁纵向应力和竖向挠度的初参数解,从力学、数学角度上证实了剪切变形和剪力滞效应是两个相对独立的力学行为,进一步阐述了二者对箱梁的影响,即剪切变形对箱梁截面纵向应力无影响,但是对竖向挠度有很大的影响.数值算例表明,利用该文解和数值解分析跨中截面剪力滞系数横向分布规律,二者吻合程度良好,其横向分布规律与单室箱梁类似,唯独不同之处是边腹板处的剪力滞效应比中腹板处的剪力滞效应略微大一些;挠度计算表明,剪切效应使得该箱梁在集中和均布荷载作用下跨中挠度分别增大4.6%和2.7%.
Progresses in the Study on Vibration Damping Properties of Novel Lightweight Composite Sandwich Structures
MA Li, YANG Jin-shui
2017, 38(4): 369-398.   doi: 10.21656/1000-0887.370328
[Abstract](1279) [PDF 6800KB](1188)
摘要:
作为新一代先进轻质超强韧结构材料,复合材料格栅和点阵夹芯结构受到了国内外学者的广泛关注.目前关于该类结构材料的设计制备以及相关力学性能研究已取得了大量的研究成果.然而对该类结构振动阻尼性能的研究则处于起步阶段.该文综述了纤维增强树脂基复合材料简单层合结构以及各类夹芯结构振动阻尼性能的研究现状.首先阐述其阻尼机理, 然后分别概述了复合材料简单层合板的微观和宏观阻尼模型、复合材料粘弹性阻尼夹层结构和新型夹层结构的阻尼预报工作,最后总结归纳现有关于该类结构阻尼特性研究工作中已取得的成果和不足之处,并对其未来发展进行了展望.
Study of Stress Field Near Interface Crack Tip of Double Dissimilar Orthotropic Composite Materials
LI Jun-lin, ZHANG Shao-qin, YANG Wei-yang
2008, 29(8): 947-953.  
[Abstract](3008) [PDF 460KB](25)
Abstract:
A study of double dissintilar orthotropic composite materials interfacial crack was made by constivcting new stress functions and employing the method of composite material complex.In the case that the characteristic equations' discriminants are all more than zero,the theoretical fonmula of the stress field and the displacement field near the mode Ⅰ interface crack tip,without oscillation and inter-embedding between the interfaces of the crack were delved.
Second Order Approximation Solution of Nonlinear Large Deflection Problem of Yongjiang Railway Bridge in Ningbo
CHIEN Wei-zang
2002, 23(5): 441-451.  
[Abstract](5622) [PDF 395KB](124)
Abstract:
The solution and computational aspects on nonlinear deflection of Yongjiang Railway Bridge in Ningbo were investigated.An approximate iteration algorithm on nonlinear governing equation was presented,and the obtained results show that,if altitude difference and span of the riverbanks are taken as 5 meters and 100 meters,respectively,the maximum gradient in the middle of the bridge exceeds 5%,much larger than maximum allowance gradient in railway design code.Therefor,a new solution scheme for decreasing gradient of the bridge is put forward,that is,the altitude difference between two riverbanks can be decreased to about 1/10 of the initial magnitude by building roadbeds with 0.5% gradient and 1 kilometer length at two riverbanks.As a direct result,the deflection gradient of the railway bridge is much reduced and the value is between 0.5%~0.6%.