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Chinese Optics Letters 2018年第11期16卷 61-65页

作者： Suhui Deng Yiping Xiao Jie hu Jianfang Chen Yuhao wang Mingping Liu school of Information engineering Nanchang UniversityNanchang 330031China Division of physical Biology Shanghai Institute of Applied PhysicsChinese Academy of SciencesShanghai 201800China shanghai Institute of Optics and Fine mechanics Chinese Academy of SciencesShanghai 201800China

The fluorescence from the out-of-focus region excited by the sidelobes of a Bessel beam is the major concern for light-sheet fluorescence microscopy （LSFM） with Bessel beam plane illumination. Here, we propose a method of applying the subtractive imaging to overcome the limitation of the conventional LSFM with Bessel beam plane illumination. In the proposed method, the sample is imaged twice by line scanning using the extended solid Bessel beam and the ring-like Bessel beam. By subtracting between the two images with similar out-of-focus blur, the improved image quality with the suppression of the Bessel beam sidelobes and enhanced sectioning ability with improved contrast are demonstrated.

关键词： Sidelobe suppression in light-sheet fluorescence microscopy with Bessel beam plane illumination using subtractive imaging

Stability and Hopf bifurcation of a delayed ratio-dependent predator-prey system

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Acta Mechanica Sinica 2011年第2期27卷 285-296页

作者： Wan-Yong wang Li-Jun pei school of aerospace engineering and applied mechanics Tongji University 200092 Shanghai China Department of Mathematics Zhengzhou University 450001 Zhengzhou China

Since the ratio-dependent theory reflects the fact that predators must share and compete for food, it is suitable for describing the relationship between predators and their preys and has recently become a very important theory put forward by biologists. In order to investigate the dynamical relationship between predators and their preys, a so-called Michaelis-Menten ratio-dependent predator-prey model is studied in this paper with gestation time delays of predators and preys taken into consideration. The stability of the positive equilibrium is investigated by the Nyquist criteria, and the existence of the local Hopf bifurcation is analyzed by employing the theory of Hopf bifurcation. By means of the center manifold and the normal form theories, explicit formulae are derived to determine the stability, direction and other properties of bifurcating periodic solutions. The above theoretical results are validated by numerical simulations with the help of dynamical software Winpp. The results show that if both the gestation delays are small enough, their sizes will keep stable in the long run, but if the gestation delays of predators are big enough, their sizes will periodically fluc-tuate in the long term. In order to reveal the effects of time delays on the ratio-dependent predator-prey model, a ratiodependent predator-prey model without time delays is considered. By hurwitz criteria, the local stability of positive equilibrium of this model is investigated. The conditions under which the positive equilibrium is locally asymptotically stable are obtained. By comparing the results with those of the model with time delays, it shows that the dynamical behaviors of ratio-dependent predator-prey model with time delays are more complicated. Under the same conditions, namely, with the same parameters, the stability of positive equilibrium of ratio-dependent predator-prey model would change due to the introduction of gestation time delays for predators and preys. Moreover, w

关键词： Time delays · Stability · Hopf bifurcation · Normal form · Center manifold

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基于相场法的混凝土冻融疲劳耐久性能研究

力学季刊 2024年第3期45卷 676-687页

作者：邹博煜贺鹏飞戴瑛王本劲同济大学航空航天与力学学院上海200092

为了研究混凝土在疲劳与冻融耦合作用下的性能表现,采用疲劳相场法对混凝土的性能演化进行了研究.基于随机骨料投放算法,得到一定面积分数与带界面过渡区(Interfacial Transition Zone,ITZ)的混凝土骨料模型.通过引入热力耦合疲劳相场模... 详细信息

为了研究混凝土在疲劳与冻融耦合作用下的性能表现,采用疲劳相场法对混凝土的性能演化进行了研究.基于随机骨料投放算法,得到一定面积分数与带界面过渡区(Interfacial Transition Zone,ITZ)的混凝土骨料模型.通过引入热力耦合疲劳相场模型,对混凝土冻融疲劳开裂的全过程进行了数值模拟研究.结果表明:冻融过程中,损伤起始于骨料角点处应力水平最高的界面过渡区;纯冻融条件下,冻融前期损伤发展比较缓慢,后期损伤迅速发展;冻融加疲劳条件下,混凝土耐久性能大大降低,寿命仅为纯冻融条件下的50%,随着冻融次数的增加,混凝土强度、弹性模量逐渐降低,且降幅增大.

关键词：混凝土冻融循环疲劳相场法骨料模型

Effects of time-delayed vibration absorber on bandwidth of beam for low broadband vibration suppression

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applied Mathematics and mechanics(English Edition) 2023年第10期44卷 1629-1650页

作者： Xiuting SUN Yipeng QU Feng wang Jian XU school of aerospace engineering and applied mechanics Tongji UniversityShanghai 200092China

The effects of time-delayed vibration absorber(TDVA) on the dynamic characteristics of a flexible beam are investigated. First, the vibration suppression effect of a single TDVA on a continuous beam is studied. The first optimization criterion is given,and the results show that the introduction of time-delayed feedback control(TDFC) is beneficial to improving the vibration suppression at the anti-resonance band. When a single TDVA is used, the anti-resonance is located at a specific frequency by the optimum design of TDFC parameters. Then, in order to obtain low-frequency and broad bands for vibration suppression, multiple TDVAs are uniformly distributed on a continuous beam,and the relationship between the dynamic responses and the TDFC parameters is investigated. The obtained relationship shows that the TDVA has a significant regulatory effect on the vibration behavior of the continuous beam. The effects of the number of TDVAs and the nonlinearity on the bandgap variation are discussed. As the multiple TDVAs are applied, according to the different requirements on the location and bandwidth of the effective vibration suppression band, the optimization criteria for the TDFC parameters are given, which provides guidance for the applications of TDVAs in practical projects such as bridge and aerospace.

关键词： time-delayed vibration absorber(TDVA) time-delayed feedback control(TDFC) parameter design criterion broadband vibration suppression

Surface contact behavior of functionally graded thermoelectric materials indented by a conducting punch

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applied Mathematics and mechanics(English Edition) 2021年第5期42卷 649-664页

作者： Xiaojuan TIAN Yueting ZHOU Lihua wang Shenghu DING school of aerospace engineering and applied mechanics Tongji UniversityShanghai 200092China school of Mathematics and Statistics Ningxia UniversityYinchuan 750021China

The contact problem for thermoelectric materials with functionally graded properties is *** material properties,such as the electric conductivity,the thermal conductivity,the shear modulus,and the thermal expansion coefficient,vary in an exponential *** the Fourier transform technique,the electro-thermoelastic problems are transformed into three sets of singular integral equations which are solved numerically in terms of the unknown normal electric current density,the normal energy flux,and the contact ***,the complex homogeneous solutions of the displacement fields caused by the gradient parameters are simplified with the help of Euler’s *** addressing the non-linearity excited by thermoelectric effects,the particular solutions of the displacement fields can be *** effects of various combinations of material gradient parameters and thermoelectric loads on the contact behaviors of thermoelectric materials are *** results give a deep insight into the contact damage mechanism of functionally graded thermoelectric materials(FGTEMs).

关键词： thermoelectric material functionally graded property conducting punch conjugate complex root energy flux contact pressure

Impact Dynamics of a Dragonfly Wing

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Computer Modeling in engineering & Sciences 2020年第3期122卷 889-906页

作者： Lihua wang Wenjing Ye Yueting Zhou school of aerospace engineering and applied mechanics Tongji UniversityShanghaiChina.

The lift force was reported not to be high enough to support the dragonfly’s weight during flight in some conventional investigations,and higher lift force is required for its *** this study,by employing a thin plate model,impact effect is investigated for the wing deformation in dragonfly flapping during *** static displacement is formulated to compare with the dynamical displacement caused by *** governing equation of motion for the impact dynamics of a dragonfly wing is derived based on Newton’s second *** of variables technique and assumed modes method are introduced to solve the resulting ***,lift force is presented for the cases of considering and without considering the impact on the wing flapping which indicates that the impact has prominent effects for the dragonfly’s aerodynamic *** simulations demonstrate that considering the impact effect on the wing flapping can increase the wing deformation,which results in the rise of the lift *** enhanced lift force is of critical importance for the dragonfly’s takeoff.

关键词： Impact dynamics wing deformation thin plate model lift force.

Seepage flow around twin circular tunnels in anisotropic ground revealed by an analytical solution

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Underground Space 2023年第3期10卷 1-14页

作者： Fengran Wei huaning wang Guangshang Zeng Mingjing Jiang school of aerospace engineering and applied mechanics Tongji UniversityShanghai 200092China school of Urban Construction and Safety engineering Shanghai Institute of TechnologyShanghai 201418China State Key Laboratory of Disaster reduction in Civil engineering Tongji UniversityShanghai 200092China

A new analytical solution is proposed for steady seepage flow around twin circular tunnels in fully saturated anisotropic *** solution is an exact one that fully satisfies all the boundary conditions and precisely considers the different permeabilities along two direc-tions and the interactions between twin *** solution provides a fast approach for the estimation of the seepage field and a useful tool for design *** solution is successfully addressed using problem equivalence and the Schwartz alternating method com-bined with a mapping *** a coordinate transformation of the governing equation,the anisotropic problem of circular tunnels is first equivalent to that of isotropic elliptical tunnels,and the length of the ellipse along the anisotropic axis depends on the anisotropic permeability *** Schwartz alternating method is then employed to address the solution of equivalent elliptical twin tunnel prob-lems,where a mapping function,with which an elliptical tunnel in the half-plane can be mapped into an annulus in the image plane,is introduced to solve the single tunnel problems in each iterative *** iterative procedure is quite simple and efficient in its calculations and achieves good convergence,and the analytical solution agrees very well with the numerical results to reflect its high precision in the entire ***,parametric studies are performed to investigate the influences of the anisotropic permeability and tunnel spacing on the seepage *** is the first study to provide the exact analytical solution of the seepage field of twin tunnel problems in aniso-tropic ground,and the procedure can be extended to multiple tunnel problems.

关键词： Underwater tunnel Seepage field Anisotropy Schwartz alternating method Conformal mapping method

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外部载荷对硅电极锂电池循环性能的影响

储能科学与技术 2024年第8期13卷 2559-2569页

作者：何忆南张锴周俊武王欣杨郑百林同济大学航空航天与力学学院上海200092

硅具有高比容量和低电压平台等优点,被认为是最有前途的锂离子电池负极材料之一。然而,硅电极在锂化/脱锂过程中巨大的体积膨胀以及伴随的材料破裂和粉化,限制了其倍率性能和循环性能。现有研究表明,在循环过程中对硅电极施加外部载荷... 详细信息

硅具有高比容量和低电压平台等优点,被认为是最有前途的锂离子电池负极材料之一。然而,硅电极在锂化/脱锂过程中巨大的体积膨胀以及伴随的材料破裂和粉化,限制了其倍率性能和循环性能。现有研究表明,在循环过程中对硅电极施加外部载荷能有效提高电池的循环性能。本研究提出了一种宏观调控方法,即通过施加外部机械载荷以提高硅电极锂离子电池的容量保持率。采用设计定制的原位充放电加压实验设备,以Cr2032纽扣电池为对象开展实验,通过充放电循环测试验证了该方法的有效性。实验结果显示,在Cr2032电池表面施加0.2 Mpa大小的轴向外部载荷,可以有效抑制硅电极在充放电过程中的膨胀,并调节电池内部状态。经过50个充放电循环后,电池容量保持率将从无外部载荷时的59%提升至70%。同时,由于硅电极活性物质颗粒在锂化和脱锂过程中存在不同的应力状态,提出了一种新的调控方法,即在循环过程中在电极材料的锂化阶段施加0.1 Mpa大小的外部载荷,并在脱锂阶段施加0.2 Mpa的载荷。实验结果证明,该方法可以进一步提高硅电极锂离子电池的循环性能。此外,电极表面的扫描电子显微镜成像结果也支持了这一结论。本研究采用的外部机械载荷施加方法,为从宏观角度提高硅负极锂离子电池性能提供重要的借鉴。

关键词：锂离子电池硅电极外部载荷电化学性能

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基于激光剪切散斑干涉评估包覆药柱粘接质量

激光与红外 2019年第6期49卷 675-679页

作者：刘斌王虎孙霖上海工程技术大学机械与汽车工程学院上海201620 湖北航天化学技术研究所湖北襄阳441003

提出了一种新的模拟包覆药柱界面粘接缺陷的试样制作方式,并通过剪切散斑干涉技术评估包覆药柱的粘接质量,进而讨论该无损检测技术的探伤能力。文章首先介绍了包覆药柱人工缺陷的制作方式,制备了三个脱粘缺陷直径分别在2~4 mm之间的包... 详细信息

提出了一种新的模拟包覆药柱界面粘接缺陷的试样制作方式,并通过剪切散斑干涉技术评估包覆药柱的粘接质量,进而讨论该无损检测技术的探伤能力。文章首先介绍了包覆药柱人工缺陷的制作方式,制备了三个脱粘缺陷直径分别在2~4 mm之间的包覆药柱试块;接着简单介绍了剪切散斑干涉的基本原理,搭建了基于迈克尔逊干涉的光路系统,使用真空激励对包覆药柱试块加载;最后使用剪切散斑干涉技术对实际包覆药柱产品进行验证性探伤测试。实验结果表明,剪切散斑干涉技术是评估包覆层粘接质量有效的探伤手段,可检出直径为2 mm左右的人工缺陷,同时可以检测出实际包覆药柱产品的界面脱粘缺陷。本文的研究可为包覆药柱界面脱粘缺陷的制作以及该类型缺陷的检测提供技术支撑。

关键词：包覆药柱粘接质量剪切散斑无损检测

Ultraflat, broadband, and highly coherent supercontinuum generation in all-solid microstructured optical fibers with all-normal dispersion

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photonics research 2018年第6期6卷 601-608页

作者： ChuNLEI huANG MEISONG LIAO WANJUN BI XIA LI LILI hu LONG ZHANG LONGFEI wang GUANSHI QIN TIANFENG XUE DANpING CHEN WEIQING GAO Key Laboratory of Materials for High power Laser Shanghai Institute of Optics and Fine Mechanics Chinese Academy of SciencesShanghai 201800 China university of Chinese Academy of Sciences Beijing 100049 China State Key Laboratory on Integrated Optoelectronics College of Electronic Science and Engineering Jilin University Changchun 130012 China school of Electronic Science & applied physics Hefei University of Technology Hefei 230009 China

High flatness, wide bandwidth, and high-coherence properties of supercontinuum(SC) generation in fibers are crucial in many applications. It is challenging to achieve SC spectra in a combination of the properties, since special dispersion profiles are required, especially when pump pulses with duration over 100 fs are employed. We propose an all-solid microstructured fiber composed only of hexagonal glass elements. The optimized fiber possesses an ultraflat all-normal dispersion profile, covering a wide wavelength interval of approximately 1.55 μm. An SC spectrum spanning from approximately 1030 to 2030 nm(corresponding to nearly one octave) with flatnessrically generated in the fiber with 200 fs pump pulses at 1.55 μm. The results indicate that the broadband ultraflat SC sources can be all-fiber and miniaturized due to commercially achievable 200-fs fiber lasers. Moreover, the SC pulses feature high coherence and a single pulse in the time domain, which can be compressed to 13.9-fs pulses with high quality even for simple linear chirp compensation. The Fourier-limited pulse duration of the spectrum is 3.19 fs, corresponding to only 0.62 optical cycles.

关键词： Fiber design and fabrication photonic crystal fibers Nonlinear optics fibers pulse compression Femtosecond phenomena Supercontinuum generation