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Forced response of quadratic nonlinear oscillator: comparison of various approaches

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Applied Mathematics and Mechanics(English Edition) 2015年第11期36卷 1403-1416页

作者： wenan jiang Guoce ZHANG Liqun CHEN Shanghai Institute of Applied Mathematics and Mechanics Shanghai University College of Sciences Shanghai University Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai University

The primary resonances of a quadratic nonlinear system under weak and strong external excitations are investigated with the emphasis on the comparison of dif- ferent analytical approximate approaches. The forced vibration of snap-through mecha- nism is treated as a quadratic nonlinear oscillator. The Lindstedt-Poincar method, the multiple-scale method, the averaging method, and the harmonic balance method are used to determine the amplitude-frequency response relationships of the steady-state responses. It is demonstrated that the zeroth-order harmonic components should be accounted in the application of the harmonic balance method. The analytical approximations are com- pared with the numerical integrations in terms of the frequency response curves and the phase portraits. Supported by the numerical results, the harmonic balance method pre- dicts that the quadratic nonlinearity bends the frequency response curves to the left. If the excitation amplitude is a second-order small quantity of the bookkeeping parameter, the steady-state responses predicted by the second-order approximation of the Lindstedt- Poincar method and the multiple-scale method agree qualitatively with the numerical results. It is demonstrated that the quadratic nonlinear system implies softening type nonlinearity for any quadratic nonlinear coefficients.

关键词： forced vibration quadratic nonlinearity primary resonance multiple-scalemethod Lindstedt-Poincar~ method averaging method harmonic balance method

Improving energy harvesting by internal resonance in a spring-pendulum system

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Acta Mechanica Sinica 2020年第3期36卷 618-623页

作者： wenan jiang Xiujing Han Liqun Chen Qinsheng Bi Faculty of Civil Engineering and Mechanics Jiangsu UniversityZhenjiang 212013China School of Science Harbin Institute of TechnologyShenzhen 518055China Department of Mechanics Shanghai UniversityShanghai 200072China

This paper proposes a two-to-one internal resonance to widen the bandwidth of vibratory energy *** describe the improved characteristic,an electromagnetic spring-pendulum harvester is *** analytical solutions of the electromechanical coupled system are carried out by introducing the method of multiple scales,and the frequency response relationships of the displacement and the current are *** character of broadband harvesting performance is examined,the two peaks and double jump phenomena for variation of design parameters were *** effect of key control parameters on the harvesters bandwidth is considered,and the nonlinear behaviors of the harvester are validated via numerical results.

关键词： Energy harvesting Internal resonance Broadband Nonlinear modal interactions

Path integral solution of vibratory energy harvesting systems

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Applied Mathematics and Mechanics(English Edition) 2019年第4期40卷 579-590页

作者： wenan jiang Peng SUN Gangling ZHAO Liqun CHEN Department of Engineering Mechanics Jiangsu University of Science and Technology School of Electronic and Electrical Engineering Shangqiu Normal University Department of Mechanics Shanghai University

A transition Fokker-Planck-Kolmogorov(FPK) equation describes the procedure of the probability density evolution whereby the dynamic response and reliability evaluation of mechanical systems could be carried out. The transition FPK equation of vibratory energy harvesting systems is a four-dimensional nonlinear partial differential equation. Therefore, it is often very challenging to obtain an exact probability density. This paper aims to investigate the stochastic response of vibration energy harvesters(VEHs)under the Gaussian white noise excitation. The numerical path integration method is applied to different types of nonlinear VEHs. The probability density function(PDF)from the transition FPK equation of energy harvesting systems is calculated using the path integration method. The path integration process is introduced by using the GaussLegendre integration scheme, and the short-time transition PDF is formulated with the short-time Gaussian approximation. The stationary probability densities of the transition FPK equation for vibratory energy harvesters are determined. The procedure is applied to three different types of nonlinear VEHs under Gaussian white excitations. The approximately numerical outcomes are qualitatively and quantitatively supported by the Monte Carlo simulation(MCS).

关键词： nonlinear energy harvester path integration probability density function(PDF)

TPA Enhances Growth Horm one (GH) Secretion Effect ofGH-Releasing Horm one (GHRH) by Hum an gsp-PositivePi-tuitary Som atotrophinom as

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Journal of Huazhong University of Science and Technology(Medical Sciences) 1999年第3期19卷 237-239,248页

作者： LEI Ting , BAI Xiangjun , HU wenan , XUE Delin , jiang Xianhui Department of Neurosurgery, Tongji Hospital, Tongji Medical University, Wuhan 430030 Department of Neurosurgery Tongji Hospital Tongji Medical University Wuhan

In recent years, one of the most exciting advances in the researches of pituitary adenomas is the discovery that 30 %-40 % of human pituitary somatotrophinomas carry somatic mutations of the gene for the α subunit of the stimulatory GTP binding protein, G s (G sα). These mutations, termed gsp oncogenes, may play an important role in the tumorigenesis of pituitary adenomas. Of 10 somatotrophinomas examined, 3 (30 %) were proved to be gsp positive, as determined by sequence analysis of DNA generated by the polymerase chain reaction (PCR). GHRH exerted a significant stimulatory effect on GH secretion in 2 of 3 gsp positive and 4 of 7 gsp negative tumors. Moreover, phorbol ester, 1, 2 tetradecanoylphorbol 13 acetate (TPA), enhanced stimulation of lated the GH secretion effect exerted by GHRH in gsp positive somatotrophinomas, whereas this effect was not observed in gsp negative tumors. This result suggests that the protein kinase C signal system as well as adenylyl cyclase cAMP protein kinase A intracellular signal transduction system plays a pivotal role in GH secretory control of GHRH, which may work together via a cross talk mechanism.

关键词： pituitary adenomas gsp oncogenes growth hormone releasing hormone TPA

一类三维非线性系统的复杂簇发振荡行为及其机理

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力学学报 2020年第6期52卷 1789-1799页

作者：马新东姜文安张晓芳韩修静毕勤胜江苏大学土木工程与力学学院江苏镇江212013 江苏科技大学船舶与海洋工程学院江苏镇江212003

由多时间尺度耦合效应引起的簇发振荡行为是非线性动力学研究的重要课题之一.本文针对一类参数激励下的三维非线性电机系统(该系统可以描述两种自激同极发电机系统的动力学行为,两种系统在数学上等效),研究了当参数激励频率远小于系统... 详细信息

由多时间尺度耦合效应引起的簇发振荡行为是非线性动力学研究的重要课题之一.本文针对一类参数激励下的三维非线性电机系统(该系统可以描述两种自激同极发电机系统的动力学行为,两种系统在数学上等效),研究了当参数激励频率远小于系统自然频率时的各种复杂簇发振荡行为及其产生机理.通过快慢分析方法,将参数激励作为慢变参数,得到了非自治系统对应的广义自治系统及快子系统和慢变量,并给出了快子系统的稳定性和分岔条件以及系统关于典型参数的单参数分岔图.借助转换相图与分岔图的叠加,分析了对称式delayed subHopf/fold cycle簇发振荡的产生机理及其动力学转迁,即delayed subHopf/fold cycle簇发振荡、焦点/焦点型对称式叉形分岔滞后簇发振荡和焦点/焦点型叉形分岔滞后簇发振荡.研究结果表明,系统会出现两种不同的分岔滞后形式,一种是亚临界Hopf分岔滞后,另一种是叉形分岔滞后,而且控制参数显著影响平衡点的稳定性和分岔滞后区间的宽度.同时初始点的选取则会影响系统动力学行为的对称性.本文的研究进一步加深了对由分岔滞后引起的簇发振荡的认识和理解.

关键词：三维非线性系统簇发振荡快慢分析 Hopf分岔滞后叉形分岔滞后

海洋平台桁架结构半主动颗粒阻尼减振技术研究

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振动与冲击 2018年第4期37卷 93-98,109页

作者：夏兆旺茅凯杰王雪涛姜文安杨绍普江苏科技大学能源与动力学院江苏镇江212003 江苏科技大学船舶与海洋工程江苏镇江212003 石家庄铁道大学机械工程学院石家庄050043

海洋平台桁架结构的减振装置长期暴露在盐雾和高强度的紫外线辐射下,传统的黏弹性阻尼减振技术易老化、失效,其使用寿命有限。通过电磁场控制颗粒运动的半主动颗粒阻尼技术在被动颗粒阻尼技术耐高温、抗老化等优点的同时,还能适应外界... 详细信息

海洋平台桁架结构的减振装置长期暴露在盐雾和高强度的紫外线辐射下,传统的黏弹性阻尼减振技术易老化、失效,其使用寿命有限。通过电磁场控制颗粒运动的半主动颗粒阻尼技术在被动颗粒阻尼技术耐高温、抗老化等优点的同时,还能适应外界复杂载荷的变化。基于耦合仿真分析方法研究半主动颗粒阻尼技术在海洋平台桁架结构中的减振性能,分析了控制策略、控制电流、颗粒参数等因素对海洋平台桁架结构振动特性的影响规律。结果表明:半主动颗粒阻尼减振效果优于被动颗粒阻尼减振效果;控制策略在不同频段对系统减振效果的不同;仿真结果与试验结果具有很好的一致性。

关键词：半主动颗粒阻尼桁架结构减振开关控制

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相对运动中一类质点运动方程的同伦摄动解

力学与实践 2023年第6期45卷 1399-1402页

作者：姜文安刘若冰顾叶彤李浚超江苏大学土木工程与力学学院江苏镇江212013

相对运动中质点的运动方程大多数是非线性的,其精确显式求解是一个难点。本文基于同伦摄动分析方法,研究了相对运动中一类质点运动非线性微分方程的近似显式解。先构造了系统的同伦方程,再结合Lindstedt–Poincare方法和系统的初始条件... 详细信息

相对运动中质点的运动方程大多数是非线性的,其精确显式求解是一个难点。本文基于同伦摄动分析方法,研究了相对运动中一类质点运动非线性微分方程的近似显式解。先构造了系统的同伦方程,再结合Lindstedt–Poincare方法和系统的初始条件,推导了系统自由振动的固有频率,求解了系统的位移近似响应,并通过数值仿真验证了理论分析解的正确性,为相对运动的质点运动方程求解提供了一种新的求解方法。

关键词：理论力学相对运动非线性同伦摄动

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簇发振荡能量采集动力学理论研究进展

动力学与控制学报 2024年第8期22卷 1-12页

作者：姜文安卞明礼陈立群毕勤胜江苏大学土木工程与力学学院镇江212013 上海大学力学与工程科学学院上海200072

将自然环境中的振动能,通过能量采集装置转化为电能,为低功耗的电子器件提供清洁可持续的能源,对推动无线传感电子技术的发展具有重要意义.当环境的振动频率远低于采集装置的固有频率时,传统振动能量采集技术的采集效率将会明显降低,无... 详细信息

将自然环境中的振动能,通过能量采集装置转化为电能,为低功耗的电子器件提供清洁可持续的能源,对推动无线传感电子技术的发展具有重要意义.当环境的振动频率远低于采集装置的固有频率时,传统振动能量采集技术的采集效率将会明显降低,无法匹配低频的环境激励,而基于低频激励的簇发振荡通常表现为激发态的大幅振荡与沉寂态的微幅振荡的组合,具有大幅运动的高能轨道,在低频慢变激励的环境下依然保持较为良好的采集性能.因此,开展适应低频激励环境的能量采集技术的研究是很有必要.本文系统地概述了簇发振荡能量采集器的机电耦合能量转换装置、簇发振荡能量采集的动力学机理、簇发振荡能量采集的效率三个方面的研究进展.最后,给出了开展簇发振荡能量采集技术研究的一些建议.

关键词：簇发振荡能量采集快慢分析分岔理论

Toward understanding the role of genomic repeat elements in neurodegenerative diseases

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Neural Regeneration Research 2025年第3期20卷 646-659页

作者： Zhengyu An Aidi jiang Jingqi Chen Institute of Science and Technology for Brain-Inspired Intelligence Fudan UniversityShanghaiChina MOE Frontiers Center for Brain Science Fudan UniversityShanghaiChina MOE Key Laboratory of Computational Neuroscience and Brain-Inspired Intelligence Fudan UniversityShanghaiChina Zhangjiang Fudan International Innovation Center ShanghaiChina

Neurodegenerative diseases cause great medical and economic burdens for both patients and society;however, the complex molecular mechanisms thereof are not yet well understood. With the development of high-coverage sequencing technology, researchers have started to notice that genomic repeat regions, previously neglected in search of disease culprits, are active contributors to multiple neurodegenerative diseases. In this review, we describe the association between repeat element variants and multiple degenerative diseases through genome-wide association studies and targeted sequencing. We discuss the identification of disease-relevant repeat element variants, further powered by the advancement of long-read sequencing technologies and their related tools, and summarize recent findings in the molecular mechanisms of repeat element variants in brain degeneration, such as those causing transcriptional silencing or RNA-mediated gain of toxic function. Furthermore, we describe how in silico predictions using innovative computational models, such as deep learning language models, could enhance and accelerate our understanding of the functional impact of repeat element variants. Finally, we discuss future directions to advance current findings for a better understanding of neurodegenerative diseases and the clinical applications of genomic repeat elements.

关键词： Alzheimer's disease ataxia deep learning long-read sequencing neurodegeneration neurodegenerative diseases Parkinson's disease repeat element structural variant