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细长弹/箭体简化梁结构动特性设计研究
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作者 张琪 王坤 +1 位作者 高少鹏 王国发 《北华航天工业学院学报》 CAS 2023年第6期4-6,共3页
将细长弹体等效为等截面自由直梁,分析比较了三种求解其低阶固有频率的方法,算例证明:比起有限元方法和经验公式,根据自由振动方程求解得到频率解析式的方法计算精度较高且使用方便。应用频率解析式,利用优化方法,对等截面自由直梁进行... 将细长弹体等效为等截面自由直梁,分析比较了三种求解其低阶固有频率的方法,算例证明:比起有限元方法和经验公式,根据自由振动方程求解得到频率解析式的方法计算精度较高且使用方便。应用频率解析式,利用优化方法,对等截面自由直梁进行初始动力学设计。细长体飞行器作为弹性体,只考虑其刚体运动是不能满足要求的,本文可为细长体飞行器的早期动力学设计提供参考,具有一定的工程应用价值。 展开更多
关键词 结构动力学分析 低阶固有频率 动力学设计
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电力系统超低频振荡和倍频振荡的正规形分析 被引量:4
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作者 苏小林 周双喜 阎晓霞 《电力自动化设备》 EI CSCD 北大核心 2011年第1期7-10,14,共5页
正规形法揭示了电力系统中动态模式之间的非线性相互作用,可用于分析因模式间非线性相互作用而产生的复杂动态现象和动态行为。分析表明,动态模式间相互作用所产生的组合模式使得振荡频率减小或增大,可能导致超低频振荡或倍频振荡现象,... 正规形法揭示了电力系统中动态模式之间的非线性相互作用,可用于分析因模式间非线性相互作用而产生的复杂动态现象和动态行为。分析表明,动态模式间相互作用所产生的组合模式使得振荡频率减小或增大,可能导致超低频振荡或倍频振荡现象,而且其明显程度取决于系统的非线性作用程度。正规形变换系数和正规形变量初值乘积可反映超低频振荡模式或倍频振荡模式在状态量响应中的作用程度,其值大,则组合模式作用模值大;组合模式的实部绝对值可反映组合模式持续时间的长短,其值小,则组合模式作用时间长。该分析揭示了电力系统产生超低频振荡和倍频振荡的可能性和条件。对一2区域4机系统进行仿真,应用所提方法分析出了该系统在重载运行条件下出现的超低频振荡现象。 展开更多
关键词 低频振荡 正规形法 超低频振荡 倍频振荡
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宁波港船舶岸电推广应用的问题和对策 被引量:4
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作者 王金波 《港口科技》 2016年第5期29-32,共4页
分析宁波港船舶岸电推广面临的电制标准不统一、不同货种船舶岸电适应性不同和经济效益不佳等3个方面的技术经济问题,并提出宁波港应优先发展低压常频岸电,适时发展集装箱码头高压变频岸电等对策建议。
关键词 港口 船舶岸电 低压常频 高压变频
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Parametric Modeling of Electromagnetically Induced Vibration Processes Occurring Within Induction Systems 被引量:1
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作者 PETRYKOWSKI John C. SHI Yinghui 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2012年第S2期709-712,共4页
A continuum based model is presented which identifies a favorable set of operational conditions whereby an effective and efficient electromagnetically induced vibratory motion can proceed within an induction system.Sp... A continuum based model is presented which identifies a favorable set of operational conditions whereby an effective and efficient electromagnetically induced vibratory motion can proceed within an induction system.Specifically, an analytical assessment is presented for the electromagnetic field and the electromagnetically induced acoustic field, with parametric factors incorporated into the model to permit a normal modes solution for the acoustic field which here is sensitive to the compliance of both the molten metal and the wall,as well as electromagnetic properties of the metal.A parametric analysis is presented which identifies the importance of matching the mechanical impedances of the melt-wall configuration so that the generation of acoustic energy within the melt system can be more effectively utilized.Relatively straight-forward calculations,presented for the acoustic field,may provide a more computationally efficient means for implementing process simulation studies for these systems. 展开更多
关键词 induction systems low-frequency electromagnetic vibrating casting(LFEVC) normal modes
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Quasi-Steady Vibratory Motion Within an Inductively Heated Cylindrically-Shaped Liquid Volume
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作者 SHI Yinghui PETRYKOWSKI John C. 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2012年第S2期739-742,共4页
The motion of an inductively heated fluid volume of cylindrical shape is assessed based on time dependent oscillatory components of the Lorentz force.The applications considered include vibratory motion in a channel i... The motion of an inductively heated fluid volume of cylindrical shape is assessed based on time dependent oscillatory components of the Lorentz force.The applications considered include vibratory motion in a channel induction furnace and vibratory motion in an electromagnetically excited direct chill casting.The governing equations for the resulting magnetoacoustic problem are presented with the acoustic field solutions expressed in terms of normal modes. Closed form expressions are developed for the velocity,pressure and phase relationships between the excitation and the response.Calculations are prescribed for the pressure in both the channel furnace and the direct chill casting,with the calculational results from the casting application suggesting that,roughly,a two-fold increase in the effective peak acoustic pressure can be achieved by superimposing on the AC electromagnetic field a DC magnetic field of strength sufficient to match the peak alternating magnetic field.A procedure is also outlined for developing field descriptions of the velocity and pressure which can be effected in a MATLAB environ. 展开更多
关键词 induction systems low-frequency electromagnetic vibrating casting(LFEVC) normal modes
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