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Resonance analysis of single DOF parameter-varying system of magnetic-liquid double suspension bearing

High Technology Letters 2022年第1期28卷 72-79页

作者：赵建华 ZHAO Yabin ZHANG Xuze WANG Jin WANG Ziqi GAO Dianrong du guojun Fluid Power Transmission and Control Laboratory Yanshan UniversityQinhuangdao 066004P.R.China No.7 Branch Company Qinhuangdao Port Co.LtdQinhuangdao 066002P.R.China College of Civil Engineering and Mechanics Yanshan UniversityQinhuangdao 066004P.R.China

Magnetic-liquid double suspension bearing(MLDSB)is mainly supported by electromagnetic suspension and supplemented by hydrostatic supporting.Its bearing capacity and stiffness can be greatly improved,and then it is suitable for the occasions of medium speed,heavy load.When the bearing system is excited by periodic force,the flow q and current i regulated by the double-closed-loop control mechanism change periodically.Then the risk of parametric resonance in MLDSB is greatly aggravated by the change of the parameter system,which seriously affects its operation stabil-ity and reliability.Therefore,this paper intends to study the resonance characteristics of the parame-ter system of MLDSB.Firstly,Marshall-duffing equation of the parametric system is established by taking the flow q and the current i as variables respectively.Then,by using the asymptotic method,the occurrence condition and variation rule of the principal,1/2 Harmonic and 1/3 Harmonic para-metric resonance are solved.The results show that only the 1/2 Harmonic resonance of the flow q parameter varying system occurs accompanied by the resonance condition of high frequency.The principal,1/2 Harmonic and 1/3 Harmonic parametric resonance of the current i occur accompanied by the resonance condition of high frequency.And the 1/2 Harmonic resonance of the current i oc-curs accompanied by the non-single value bifurcation and dynamic bifurcation.The paper can pro-vide theoretical reference for the parameter design and stable operation of MLDSB.

关键词： magnetic-liquid double suspension bearing(MLDSB) resonance analysis flow parameter varying system current parameter varying system

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Analysis of fluid vibration transfer path and parameter sensitivity of swash plate axial piston pump

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High Technology Letters 2022年第2期28卷 217-226页

作者：赵建华 WANG Xinwei LIU Hang PEI Youzhi YANG Yong WU Zhaohua WANG Jin XING Lanchun du guojun Shijiazhuang Haishan Industrial Development Co. Ltd.Shijiazhuang 050200P.R.China Fluid Power Transmission and Control Laboratory Yanshan UniversityQinhuangdao 066004P.R.China College of Civil Engineering and Mechanics Yanshan UniversityQinhuangdao 066004P.R.China

Taking swash plate axial piston pump as the research object,the mechanism of fluid vibration and transfer rule are analyzed.The pump shell can be assumed as the ultimate recipient of vibration transmission,the path model and differential equations from the fluid to the shell are established.The parameters of the path model are determined by the simulation software,and the mathematical model is solved by the simulation software.And time/frequency domain analysis of vibration acceleration of shell is presented.Based on the different influence of various parameters in the transfer path model on transfer characteristics and vibrational recipients,the time-varying parameters are studied by using sensitivity analysis theory,and the influence of the structural parameters on the vibration characteristics of vibration subject is quantitatively analyzed.The research in the paper provides theoretical basis for vibration analysis and structure parameter optimization of axial piston pump.

关键词： axial plunger pump fluid vibration transfer path shell vibration fault analysis

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Research on robust control strategy of single DOF supporting system of MLDSB based on H∞ mixed-sensitivity Method

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High Technology Letters 2020年第3期26卷 299-305页

作者：赵建华 Chen Tao Han Fang Gao Dianrong du guojun College of Civil Engineering and Mechanics Yanshan UniversityQinhuangdao 066004P.R.China Fluid Power Transmission and Control Laboratory Yanshan UniversityQinhuangdao 066004P.R.China Jiangsu Provincial Key Laboratory of Advanced Manufacture and Process for Marine Mechanical Equipment Zhenjiang 212003P.R.China

Because of hydraulic-electromagnetic double supporting forms,the supporting capacity and stiffness of magnetic-liquid double suspension bearing(MLDSB)can be improved sharply and then it is more suitable for medium speed,heavy load and frequent-starting occasions.due to the multiple uncertainty,such as the coupling,the unmodeled dynamics,the parameter perturbation and the external disturbance perturbation,the robust stability and stiffness of control system of MLDSB are hard to meet the design requirements.Firstly,the structural features and the regulation mechanisms of MLDSB are presented and the radial 4-DOF kinetic equations are established.Secondly,the influence factors of the control system's coupling on unbalanced vibration caused by the deviation of the rotor center of mass are revealed,and then the weighting function of suppressing the unbalanced vibration can be obtained.Finally,H∞ controller of MLDSB is designed with H∞ mixed-sensitivity method,and the control performances of H∞ controller is compared with the state feedback controller.The simulation results show that single degree of freedom(DOF)supporting system of MLDSB with H∞ controller has good robust stability,stiffness and the ability to suppress unbalanced external disturbances.This study can provide the theoretical reference for stabilized suspension and control of MLDSB.

关键词： magnetic-liquid double suspension bearing(MLDSB) single degree of freedom(DOF)supporting system H∞mixed-sensitivity method state feedback controller robust stability

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Parametric sensitivity analysis of bearing characteristics of single DOF autonomous system of magnetic-liquid double suspension bearing

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High Technology Letters 2021年第4期27卷 397-407页

作者：赵建华 Wang Qiang Wang Jin Wang Ziqi Zhang Bin Chen Tao du guojun Gao Dianrong Fluid Power Transmission and Control Laboratory Yanshan UniversityQinhuangdao 066004P.R.China College of Civil Engineering and Mechanics Yanshan UniversityQinhuangdao 066004P.R.China Jiangsu Provincial Key Laboratory of Advanced Manufacture and Process for Marine Mechanical Equipment Zhenjiang 212003P.R.China

The mathematical model of single degree of freedom(DOF)nonlinear autonomous bearing system under constant flow supporting model is deduced.The single DOF nonlinear autonomous bearing system is transformed with the method of linear and nonlinear treatment,the mathematical expression and parameters sensitivity of relative error of stiffness and damping are presented.Finally,the main factors of magnetic-liquid double suspension bearing(MLDSB)are analyzed,and the influence on bearing performance indicators of single DOF nonlinear autonomous bearing system of main factors is revealed.The results show that linear stiffness/damping is the first part of equivalent stiffness/damping,and the second and third parts are high order minor term of Tayor series transform.The film thickness,the magnetic-liquid proportionality coefficient,the mass of rotor are the major influence factor of the bearing performance.The research can provide the theoretical reference for the design and nonlinear analysis of MLDSB.

关键词： magnetic-liquid double suspension bearing(MLDSB) nonlinear autonomous bearing system equivalent nonlinear treatment bearing performance indicator parameter sensitivity relative error

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切片厚度和热风温度对沙果切片干制特性、物化性质及抗氧化成分的影响

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食品工业科技 2024年第10期45卷 32-39页

作者：姜宁宁马继洋张健张爱军沈兆花刘军张洋杜国军王存堂齐齐哈尔大学食品与生物工程学院黑龙江齐齐哈尔161006 甘肃祁连葡萄酒业有限责任公司甘肃张掖734304

为探究热风温度和切片厚度对沙果切片干燥特性、物化性质以及抗氧化成分的影响,将厚度为3和5 mm的沙果切片在不同热风温度(60、70、80、90℃)进行干燥,采用5种常见食品薄层干燥模型(Newton,Henderson and Pabis, Page, Logarithmic, Two... 详细信息

为探究热风温度和切片厚度对沙果切片干燥特性、物化性质以及抗氧化成分的影响,将厚度为3和5 mm的沙果切片在不同热风温度(60、70、80、90℃)进行干燥,采用5种常见食品薄层干燥模型(Newton,Henderson and Pabis, Page, Logarithmic, Two-tern)对实验数据进行非线性拟合,计算扩散系数和活化能,并对干燥后切片的色泽、硬度、复水性能以及抗氧化成分进行分析。结果表明,随着热风温度的升高和切片厚度的减少,干燥时间缩短。在实验的干燥温度范围内,有效扩散系数随着温度的升高而增加。沙果切片厚度分别为3和5 mm时,活化能值分别为17.46和23.82 kJ/mol。应用Fick扩散模型来描述沙果切片的水分蒸发过程,相比于其他模型,Page模型能更好地拟合沙果切片的干燥过程。沙果切片厚度为3 mm,热风干制温度为90℃时,干燥后的产品为淡黄色,复水性能较高,硬度较低。从抗氧化成分的保留情况来看,加热损失了约50%的抗坏血酸,但是酚类物质仅仅下降了约35%。综上所述,可选择切片厚度3 mm,热风温度90℃进行干制,干制时间为90 min,干燥后的产品色泽为淡黄色,复水性能较高,硬度较低,并且能够更好地保留沙果中的抗氧化成分。

关键词：沙果切片热风干燥动力学切片厚度物化性质抗氧化成分

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Effect of succinic acid on morphology transformation of the anhydrous magnesium carbonate particles prepared by magnesium chloride hexahydrate and urea

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Particuology 2024年第7期90卷 209-217页

作者： Song Liu guojun Cheng Zhongfeng Tang School of Materials Science and Engineering Anhui University of Science and TechnologyHuainan232001China Shanghai Institute of Applied Physics Chinese Academy of SciencesShanghai 201800China Anhui Province Key Laboratory of Environment-friendly Polymer Materials Anhui UniversityHefei230601China

The homogeneous and controllable morphology of anhydrous magnesium carbonate(MgCO_(3))particles with excellent properties is difficult to obtain because of a variety of synthetic factors.The effect of succinic acid as a crystal modifier on the particle morphology transformation of anhydrous MgCO_(3)was investigated by the hydrothermal method.The effect of the addition of succinic acid on the particles was similar to that of temperature change.The morphology of particles with a folded diamond-like shape was gradually uniform,and the particle size was between 3.3 and 7.5μm.Anhydrous MgCO_(3)particles prepared at pH 9 could easily agglomerate,and the average particle size increased from diamond-like to cube-like as the reaction time increased.The interaction between succinic acid and magnesium ions at different concentrations was the main factor responsible for the morphological changes.The pH,temperature,and time affected the molecular motion rate and crystal growth.

关键词： MgCO_(3) MgCl_(2)·6H_(2)O Urea Succinic acid Morphology

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Chaotic Map-Based Authentication and Key Agreement Protocol with Low-Latency for Metasystem

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Computers, Materials & Continua 2024年第3期78卷 4471-4488页

作者： guojun Wang Qi Liu School of Electronics&Information Engineering Nanjing University of Information Science&TechnologyNanjing210044China Yancheng Polytechnic College Yancheng224000China Jiangsu Province Engineering Research Center of Advanced Computing and Intelligent Services School of SoftwareNanjing University of Information Science and TechnologyNanjingChina

With the rapid advancement in exploring perceptual interactions and digital twins,metaverse technology has emerged to transcend the constraints of space-time and reality,facilitating remote AI-based collaboration.In this dynamic metasystem environment,frequent information exchanges necessitate robust security measures,with Authentication and Key Agreement(AKA)serving as the primary line of defense to ensure communication security.However,traditional AKA protocols fall short in meeting the low-latency requirements essential for synchronous interactions within the metaverse.To address this challenge and enable nearly latency-free interactions,a novel low-latency AKA protocol based on chaotic maps is proposed.This protocol not only ensures mutual authentication of entities within the metasystem but also generates secure session keys.The security of these session keys is rigorously validated through formal proofs,formal verification,and informal proofs.When confronted with the Dolev-Yao(DY)threat model,the session keys are formally demonstrated to be secure under the Real-or-Random(ROR)model.The proposed protocol is further validated through simulations conducted using VMware workstation compiled in HLPSL language and C language.The simulation results affirm the protocol’s effectiveness in resisting well-known attacks while achieving the desired low latency for optimal metaverse interactions.

关键词： Metasystem authentication and key agreement chaotic map secure communication

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Combining TDLAS and multi-fusion algorithms for methane gas concentration detection

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Optoelectronics Letters 2024年第6期20卷 353-359页

作者： SHI guojun SONG Xinmin DONG Taiji School of Information&Electrical Engineering Heilongjiang Bayi Agricultural UniversityDaqing 163319China College of Electrical and Information Engineering Northeast Petroleum UniversityDaqing 163318China

High-precision methane gas detection is of great importance in industrial safety, energy production and environmental protection, etc. However, in the existing measurement techniques, the methane gas concentration information is susceptible to noise, which leads to its useful signal being drowned by noise. A fusion algorithm of variational modal decomposition(VMD) and improved wavelet threshold filtering is proposed, which is used in combination with tunable diode laser absorption spectroscopy(TDLAS) to implement a non-contact, high-resolution methane gas concentration detection. The fusion algorithm can perform noise reduction and further segmentation of the methane gas detection signal. And the simulation and experiment verify the effectiveness of the fusion algorithm, and the experimental results show that for the detection of air containing 10 ppm, 30 ppm, 60 ppm, 80 ppm, and 99 ppm methane, the errors are 12.75%, 8.18%, 3.37%, 2.46%, and 1.78%, respectively.

关键词： Combining TDLAS and multi-fusion algorithms for methane gas concentration detection TDLAS

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A Survey on the Evolution of Bootkits Attack and Defense Techniques

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China Communications 2024年第1期21卷 102-130页

作者： Yilin Zhou guojun Peng Zichuan Li Side Liu Key Laboratory of Aerospace Information Security and Trust Computing Ministry of EducationWuhan 430072China School of Cyber Science and Engineering Wuhan UniversityWuhan 430072China

According to the boot process of modern computer systems,whoever boots first will gain control first.Taking advantage of this feature,a malicious code called bootkit can hijack the control before the OS bootloader and bypass security mechanisms in boot process.That makes bootkits difficult to detect or clean up thoroughly.With the improvement of security mechanisms and the emergence of UEFI,the attack and defense techniques for bootkits have constantly been evolving.We first introduce two boot modes of modern computer systems and present an attack model of bootkits by some sophistical samples.Then we discuss some classic attack techniques used by bootkits from their initial appearance to the present on two axes,including boot mode axis and attack phase axis.Next,we evaluate the race to the bottom of the system and the evolution process between bootkits and security mechanisms.At last,we present the possible future direction for bootkits in the context of continuous improvement of OS and firmware security mechanisms.

关键词： bootkit hook legacy BIOS security mechanisms UEFI

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Wettability regulation from superhydrophilic to superhydrophobic via nanosecond laser ablation

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Science China(Technological Sciences) 2024年第6期67卷 1829-1841页

作者： CHEN Zhi WU ZhiCheng ZHANG guojun LI DongHui HAN FengLin State Key Laboratory of Precision Manufacturing for Extreme Service Performance College of Mechanical and Electrical EngineeringCentral South UniversityChangsha410083China Guangdong Provincial Key Laboratory of Manufacturing Equipment Digitization Guangdong HUST Industrial Technology Research InstituteDongguan523808China China Harzone Industry Corp. Ltd.Wuhan430299China

Metal surfaces play a crucial role in numerous applications,from self-cleaning and anti-icing to anti-fogging and oil-water separation.The regulation of their wettability is essential to enhance their performance in these areas.This paper proposes a multi-state regulation method for metal surface wettability,leveraging nanosecond laser ablation.By creating non-uniform microstructures on a metal surface,the contact area between the solid and liquid phases can be increased,resulting in the attainment of superhydrophilic properties(contact angle(CA),ranging from 4.6°to 8.5°).Conversely,the construction of uniform microstructures leads to a decreased solid-liquid contact area,thereby rendering the metal surface hydrophilic(CA=12.2°–53°).Furthermore,through heat treatment on a surface with uniform microstructures,organic matter adsorption can be promoted while simultaneously reducing surface energy.This process results in the metal surface acquiring hydrophobic properties(CA=92.1°–133.5°),facilitated by the“air cushion effect.”Building on the hydrophobic surface,stearic acid modification can further reduce surface energy,ultimately bestowing the metal surface with superhydrophobic properties(CA=150.1°–152.7°,and sliding angle=3.8°).Performance testing has validated the durability and self-cleaning effectiveness of the fabricated superhydrophobic surface while also highlighting the excellent anti-fog performance of the superhydrophilic surface.These findings strongly indicate the immense potential of these surfaces in various engineering applications.

关键词： nanosecond laser ablation surface wettability superhydrophobic superhydrophilic

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