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新型双活塞磁流变阻尼器的理论分析与实验研究

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振动与冲击 2015年第21期34卷 144-149,169页

作者：王强陈照波 ahmadian mehdi 刘文涛哈尔滨工业大学机电工程学院哈尔滨150001 弗吉尼亚理工大学机械工程系

针对空间柔性桁架结构振动半主动控制的需要,提出了一种重量轻、结构紧凑的双活塞磁流变阻尼器。基于磁流变液流变特性和流体动力学理论,通过分析阻尼器节流通道内的流场情况,建立了阻尼力与活塞速度之间的关系。给出了适用于阻尼器初... 详细信息

针对空间柔性桁架结构振动半主动控制的需要,提出了一种重量轻、结构紧凑的双活塞磁流变阻尼器。基于磁流变液流变特性和流体动力学理论,通过分析阻尼器节流通道内的流场情况,建立了阻尼力与活塞速度之间的关系。给出了适用于阻尼器初始设计的简化阻尼力计算方法,准静态测试的结果验证了计算方法的正确性。针对动态测试实验结果中输出力在去程和回程的不对称问题,提出了一种改进的非对称双曲正切模型。结果表明,改进模型能够准确描述新型阻尼器的动力学特性,在去程和回程都有很高的建模精度。

关键词：磁流变阻尼器磁流变液 Bingham模型非对称双曲正切模型

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基于磁流变技术的六自由度半主动隔振平台

机床与液压 2015年第5期43卷 1-4页

作者：王强陈照波刘文涛 mehdi ahmadian 哈尔滨工业大学机电工程学院黑龙江哈尔滨150001 弗吉尼亚理工大学机械工程系

针对精密仪器设备六自由度半主动隔振的需求,提出了一种基于新型双活塞磁流变液阻尼器的六自由度半主动隔振平台。首先,完成了阻尼器的研制,通过实验方法获得了阻尼器的动力学特性曲线,并建立了其双曲正切模型。其次,在新型阻尼器的基... 详细信息

针对精密仪器设备六自由度半主动隔振的需求,提出了一种基于新型双活塞磁流变液阻尼器的六自由度半主动隔振平台。首先,完成了阻尼器的研制,通过实验方法获得了阻尼器的动力学特性曲线,并建立了其双曲正切模型。其次,在新型阻尼器的基础上设计了一种基于Stewart平台结构的六自由度半主动隔振平台。对平台隔振性能仿真研究的结果表明,此平台在6个方向上都有明显的隔振效果。所提出的六自由度半主动隔振平台具有自身质量轻、结构紧凑的优点,并且隔振效果明显,满足精密仪器设备的六自由度半主动隔振需求。

关键词：磁流变液阻尼器双曲正切模型 Stewart平台振动半主动控制天棚阻尼

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新型双活塞磁流变液阻尼器及其实验建模

液压与气动 2014年第6期38卷 17-19,23页

作者：王强陈照波 mehdi ahmadian 刘文涛哈尔滨工业大学机电工程学院黑龙江哈尔滨150001 弗吉尼亚理工大学机械工程系美国黑堡va24061

针对轻质空间桁架结构振动半主动控制的需求,提出了一种新型双活塞磁流变液阻尼器,完成了阻尼器的研制。搭建了阻尼器动态特性实验装置,通过实验方法获得了其动力学特性曲线。采用双曲正切模型描述其非线性滞后效应,使用非线性最小二乘... 详细信息

针对轻质空间桁架结构振动半主动控制的需求,提出了一种新型双活塞磁流变液阻尼器,完成了阻尼器的研制。搭建了阻尼器动态特性实验装置,通过实验方法获得了其动力学特性曲线。采用双曲正切模型描述其非线性滞后效应,使用非线性最小二乘法完成了模型参数的优化。结果表明,所建立的模型能够准确描述阻尼器的动力学特性。

关键词：磁流变液阻尼器 MR阻尼器双曲正切模型非线性最小二乘法

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现代机车司机室内噪声及振动试验评价

国外内燃机车 2002年第5期 17-23页

作者： mehdi ahmadian 张钟浩

本研究的主要目的是确定用于北美铁路的典型货运机车司机室的振动特性和评价各种结构修改对司机室内部噪声和振动的效果。为此 ,在试验室环境中研究了一台批量生产型机车司机室的结构动力学特性。以接近类似司机室在现场承受的输入方式... 详细信息

本研究的主要目的是确定用于北美铁路的典型货运机车司机室的振动特性和评价各种结构修改对司机室内部噪声和振动的效果。为此 ,在试验室环境中研究了一台批量生产型机车司机室的结构动力学特性。以接近类似司机室在现场承受的输入方式用液压致动器对其激振。通过一系列试验 ,建立司机室的振动基线 ,并确定司机室各部分如何振动。然后 ,对司机室地板和顶盖进行一系列修改以降低振动水平。试验结果表明 ,加强司机室地板刚度可以降低频率在 2 0 0Hz以下的司机室内部噪声和振动。然而 ,这种降低是以增加高频振动为代价的。在司机室顶盖结构中加减振材料可看到相似的连带关系。加入减振材料降低了某些加速度峰值 ,而在 5 3Hz下却增加了一个峰值。本研究的结果指出 ,实际上 ,在能够作出哪种解决方法对于某种特定的应用场合是最有效的决定之前 ,必需对不同的噪声和振动解决办法分别进行试验。然而 ,只有在结构噪声和振动特性和主要噪声源已经被识别的情况下才可能作出这种决定。本文描述的实验室装备对于创造一个有助于可精确和重复评价不同噪声和振动解决方法的环境特别有效 ,而司机室结构则以与它在现场相同的方式被激振。没有这样的试验装备 ,许多解决方法的效果就不可能被精确地确定。

关键词：内燃机车司机室噪声振动改进措施

机车自导向转向架对改善曲线轨道上粘着的作用

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国外内燃机车 2002年第4期 10-15页

作者： mehdi ahmadian 张钟浩

本文的基本目的是为普遍用于美国铁路的自导向转向架 (即EMD的径向转向架和GE的可导向转向架 )增加曲线粘着的效果提供一种定性分析。机车转向架的曲线高粘着性能实质上表现于两个方面。首先 ,允许车轴相对于转向架构架可充分偏转 ,由... 详细信息

本文的基本目的是为普遍用于美国铁路的自导向转向架 (即EMD的径向转向架和GE的可导向转向架 )增加曲线粘着的效果提供一种定性分析。机车转向架的曲线高粘着性能实质上表现于两个方面。首先 ,允许车轴相对于转向架构架可充分偏转 ,由此 ,轮对相对于轨道保持小的冲角。其次 ,在车轴和转向架构架间提供足够大的纵向刚度 ,以适应高粘着。一种当量刚度分析用于证明本论文考虑的两种可导向转向架在为高粘着性能提供小冲角和大纵向刚度两方面远优于传统的三轴直向转向架。本文的定性分析符合美国铁路自导向转向架粘着性能的实际经验。

关键词：机车自导向转向架曲线轨道粘着性能当量刚度计算

Data-Based Filters for Non-Gaussian Dynamic Systems With Unknown Output Noise Covariance

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IEEE/CAA Journal of Automatica Sinica 2024年第4期11卷 866-877页

作者： Elham Javanfar mehdi Rahmani the Department of Electrical Engineering Imam Khomeini International UniversityQazvin ***Iran

This paper proposes linear and nonlinear filters for a non-Gaussian dynamic system with an unknown nominal covariance of the output *** challenge of designing a suitable filter in the presence of an unknown covariance matrix is addressed by focusing on the output data set of the *** that data generated from a Gaussian distribution exhibit ellipsoidal scattering,we first propose the weighted sum of norms(SON)clustering method that prioritizes nearby points,reduces distant point influence,and lowers computational ***,by introducing the weighted maximum likelihood,we propose a semi-definite program(SDP)to detect outliers and reduce their impacts on each *** these weights paves the way to obtain an appropriate covariance of the output ***,two filtering approaches are presented:a cluster-based robust linear filter using the maximum a posterior(MAP)estimation and a clusterbased robust nonlinear filter assuming that output noise distribution stems from some Gaussian noise resources according to the ellipsoidal *** last,simulation results demonstrate the effectiveness of our proposed filtering approaches.

关键词： Data-based filter maximum likelihood estimation unknown covariance weighted maximum likelihood estimation weighted sum-of-norms clustering

Reinforcement Learning-Empowered Graph Convolutional Network Framework for Data Integrity Attack Detection in Cyber-Physical Systems

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CSEE Journal of Power and Energy Systems 2024年第2期10卷 797-806页

作者： Edeh Vincent mehdi Korki mehdi Seyedmahmoudian Alex Stojcevski Saad Mekhilef School of Science Computingand Engineering TechnologiesSwinburne University of TechnologyMelbourneAustralia

The massive integration of communication and information technology with the large-scale power grid has enhanced the efficiency, safety, and economical operation of cyber-physical systems. However, the open and diversified communication environment of the smart grid is exposed to cyber-attacks. Data integrity attacks that can bypass conventional security techniques have been considered critical threats to the operation of the grid. Current detection techniques cannot learn the dynamic and heterogeneous characteristics of the smart grid and are unable to deal with non-euclidean data types. To address the issue, we propose a novel Deep-Q-Network scheme empowered with a graph convolutional network (GCN) framework to detect data integrity attacks in cyber-physical systems. The simulation results show that the proposed framework is scalable and achieves higher detection accuracy, unlike other benchmark techniques.

关键词： Deep reinforcement learning graph convolutional network heterogeneous smart grid network

A novel mitigation measure for normal fault-induced deformations on pile-raft systems

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Earthquake Engineering and Engineering Vibration 2024年第1期23卷 15-33页

作者： Mohammadreza Jahanshahi Nowkandeh mehdi Ashtiani Faculty of Civil Engineering Babol Noshirvani University of TechnologyBabolIran

Evidence from recent earthquakes has shown destructive consequences of fault-induced permanent ground movement on *** observations have increased the demand for improvements in the design of structures that are dramatically vulnerable to surface fault *** this study a novel connection between the raft and the piles is proposed to mitigate the hazards associated with a normal fault on pile-raft systems by means of 3D finite element(FE)*** embarking on the parametric study,the strain-softening constitutive law used for numerical modeling of the sand has been validated against centrifuge test *** exact location of the fix-head and unconnected pile-raft systems relative to the outcropping fault rupture in the free-field is parametrically investigated,revealing different failure *** performance of the proposed connection for protecting the pile-raft system against normal fault-induced deformations is assessed by comparing the geotechnical and structural responses of both types of *** results indicate that the pocket connection can relatively reduce the cap rotation and horizontal and vertical displacements of the raft in most *** proposed connection decreases the bending moment response of the piles to their bending moment capacity,verging on a fault offset of 0.6 m at bedrock.

关键词： normal fault rupture failure mechanism pile-raft system pocket connection finite element modeling

Correlation between platinum–aluminide coating features and tensile behavior of nickel-based superalloy Rene?80

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Rare Metals 2024年第10期43卷 5391-5402页

作者： Mohammad mehdi Barjesteh Seyed mehdi Abbasi Karim Zangeneh Madar Kourosh Shirvani Metallic Materials Research Center Malek Ashtar University of Technology (MUT) Department of Advanced Materials and New Energies Iranian Research Organization for Science and Technology (IROST)

The effect of platinum （a rare metal）–aluminide coating parameters on the tensile properties of nickel-based superalloy Rene?80 was evaluated at 871。*** this purpose,initial layers of platinum with different thicknesses （2,4,6 and 8μm） were coated on tensile samples Then,low-temperature high-activity （LTHA） and hightemperature low-activity （HTLA） processes were used for *** of microstructural evaluations using scanning electron microscope （SEM） and phase analysis by X-ray diffraction （XRD） showed a three-layer structure coating for different platinum layer thicknesses and both aluminizing *** the thickness of the platinum layer from 2 to 8μm led to the improvement in the final coating thickness from 91.6 to 102.1μm in *** increase was from 128.1 to 148.6 μm in *** results of hot tensile tests at 871℃ showed a decrease in strength properties of the coated samples compared to the uncoated ***,HTLA and high thicknesses of the initial platinum layer showed an intense *** results of fractographic evaluations abou uncoated samples showed a ductile *** the other hand,coated samples showed a simultaneous ductile and brittle fracture failure *** the main fracture morphology was brittle cleavage fracture which was for the HTLA.

关键词： Aluminizing Fractography Platinum–aluminide Rene®80 Tensile properties