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vibration frequency in Micro-vibration Therapy in Nursing Care: A Cross-Sectional Study

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Open Journal of Nursing 2023年第4期13卷 226-232页

作者： Teppei Yamashita Shinsuke Sasaki Mari Azuma Graduate School of Health and Welfare Science and Faculty of Health and Welfare Science Okayama Prefectural University Soja Japan Department of Nursing Faculty of Nursing Himeji Dokkyo University Himeji Japan Department of Nursing Science Faculty of Health and Welfare Science Okayama Prefectural University Soja Japan Department of Nursing Science Faculty of Health Care Tenri University Tenri Japan

This study investigated the vibration frequency in micro-vibration therapy (MVT) performed as a part of nursing care in Japan. We surveyed 31 nurses (25 women and 6 men) who performed MVT with accelerometers attached to the backs of their hands, and the data obtained were analyzed. The mean vibration frequency was 8.3 Hz (standard deviation [SD]: 1.9 Hz) bilaterally, with a left-right difference of 0.8 Hz (SD: 1.1 Hz, right > left). Furthermore, vibration frequency was correlated with duration of MVT use (rs = 0.5, P vibration frequency was higher in men (9.2 Hz, SD: 2.4 Hz) than in women (8.1 Hz, SD: 1.8 Hz), but this difference was not significant (P = 0.34). The vibrations of MVT are of a lower frequency than those of other vibration therapies.

关键词： Micro-vibration Therapy Nursing Care vibration frequency

Effect of Train Carbody's Parameters on Vertical Bending Stiffness Performance

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Chinese Journal of Mechanical Engineering 2016年第6期29卷 1120-1127页

作者： YANG Guangwu WANG Changke XIANG Futeng XIAO Shoune State Key Laboratory of Traction Power Southwest Jiaotong University

Finite element analysis（FEA） and modal test are main methods to give the first-order vertical bending vibration frequency of train carbody at present, but they are inefficiency and waste plenty of time. Based on Timoshenko beam theory, the bending deformation, moment of inertia and shear deformation are considered. Carbody is divided into some parts with the same length, and it＇s stiffness is calculated with series principle, it＇s cross section area, moment of inertia and shear shape coefficient is equivalent by segment length, and the fimal corrected first-order vertical bending vibration frequency analytical formula is deduced. There are 6 simple carbodies and 1 real carbody as examples to test the formula, all analysis frequencies are very close to their FEA frequencies, and especially for the real carbody, the error between analysis and experiment frequency is 0.75%. Based on the analytic formula, sensitivity analysis of the real carbody＇s design parameters is done, and some main parameters are found. The series principle of carbody stiffness is introduced into Timoshenko beam theory to deduce a formula, which can estimate the first-order vertical bending vibration frequency of carbody quickly without traditional FEA method and provide a reference to design engineers.

关键词： train carbody vertical bending vibration frequency analysis formula sensitivity analysis

Experimental research and energy analysis of a new type of dry ice powder pneumatic rock breaking technology

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International Journal of Mining Science and Technology 2023年第4期33卷 423-435页

作者： Xiaofei Wang Shaobin Hu Enyuan Wang Qiang Zhang Bing Liu Key Laboratory of Gas and Fire Control for Coal Mines(China University of Mining and Technology)Ministry of Education Xuzhou 221116China National Engineering Research Center for Coal Gas Control China University of Mining and TechnologyXuzhou 221116China State Key Laboratory of Coal Resources and Safe Mining China University of Mining and TechnologyXuzhou 221116China School of Safety Engineering China University of Mining and TechnologyXuzhou 221116China Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering HoHai UniversityNanjing 210098China Tunnel and Underground Engineering Institute College of Civil and Transportation EngineeringHoHai UniversityNanjing 210098China China Electric Construction East China Survey and Design Institute Hangzhou 311122China

When the traditional drill and blast method is applied to rock crushing projects,it has strong vibration,loud noise and dust pollution,so it cannot be used in densely populated areas such as urban public *** developed a supercritical CO_(2)true triaxial pneumatic rock-breaking experimental system,and conducted laboratory and field tests of dry ice powder pneumatic *** characteristics of the blast-induced vibration velocity waveform and the evolution of the vibration velocity and frequency with the focal distance were analyzed and *** fracturing mechanism of dry ice powder pneumatic rock breaking is *** research results show that:(1)The vibration velocity induced by dry ice powder pneumatic rock breaking decays as a power function with the increase of the focal distance;(2)The vibration frequency caused by dry ice powder pneumatic rock breaking is mainly distributed in 1–120 *** to the dispersion effect,the dominant frequency of 10–30 Hz appears abnormally attenuated;(3)The traditional CO_(2)phase change fracturing energy calculation formula is also applicable to dry ice pneumatic rock breaking technology,and the trinitrotoluene(TNT)equivalent of fracturing energy is applicable to the Sadovsky formula;(4)Dry ice powder pneumatic rock breaking is shock wave and highenergy gas acting together to fracture rock,which can be divided into three stages,among which the gas wedge action of high-energy gas plays a dominant role in rock mass damage.

关键词： Dry ice powder pneumatic rock breaking Cracking mechanism Energy analysis vibration frequency

Research on modeling and self-excited vibration mechanism in magnetic levitation-collision interface coupling system

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Applied Mathematics and Mechanics(English Edition) 2024年第5期45卷 873-890页

作者： Jinghu TANG Chaofeng LI Jin ZHOU Zhiwei WU School of Mechanical Engineering&Automation Northeastern UniversityShenyang 110819China Key Laboratory of vibration and Control of Aero-Propulsion Systems of Ministry of Education of China Northeastern UniversityShenyang 110819China School of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China

The modeling and self-excited vibration mechanism in the magnetic levitation-collision interface coupling system are *** effects of the control and interface parameters on the system's stability are *** frequency range of self-excited vibrations is investigated from the energy point of *** phenomenon of self-excited vibrations is elaborated with the phase *** corresponding control strategies are briefly analyzed with respect to the vibration *** results show that when the levitation objects collide with the mechanical interface,the system's vibration frequency becomes larger with the decrease in the collision gap;when the vibration frequency exceeds the critical frequency,the electromagnetic system continues to provide energy to the system,and the collision interface continuously dissipates energy so that the system enters the self-excited vibration state.

关键词： magnetic levitation coupling system self-excited vibration mechanical interface vibration frequency

Cushioning Performance of a Novel Polyurethane Foam Material Applied in Fragile Packaging

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Acta Mechanica Solida Sinica 2024年第3期37卷 487-497页

作者： Huifeng Xi Chunqiu Guo Jinbiao Yang Xiaogang Wang Bowei Wang Shiqing Huang Zhiwei Wang School of Mechanics and Construction Engineering Jinan UniversityGuangzhou510632China College of Packing Engineering Jinan UniversityZhuhai519070China MOE Key Lab of Disaster Forecast and Control in Engineering Jinan UniversityGuangzhou510632China Foshan Soft Valley Technology Co. Ltd.Foshan528000China

For fragile products,packaging requires cushioning protection to prevent irreversible damage from accidental falls,transportation impacts,and other *** new polyurethane foam(PUF)material demonstrates superior cushioning and vibration isolation performance in practical applications,effectively minimizing damage from *** and vibration experiments were conducted on packages comprising novel PUF,expandable polyethylene,ethylene-vinyl acetate copolymer foam,and *** verify that the new PUF material outperforms in cushioning and vibration isolation,as observed from the acceleration ***,a random vibration analysis of a packaging unit involving different thicknesses of PUF materials and bracelets reveals the enhanced vibration isolation effect within a specific thickness *** vibration results of the bracelet’s outer packaging align closely with finite element simulation results,validating the effectiveness of designing and optimizing the outer *** finite element simulation,deeper understanding and prediction of the bracelet’s vibration response under various conditions is achieved,facilitating optimized packaging design for better protection and vibration damping.

关键词： Flexible polyurethane foam Packaging of fragile goods Nonlinear dynamics vibration frequency Finite element simulation

Impact of acoustic wave propagation characteristics on aerodynamic damping of rotor blades in a transonic axial compressor

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Chinese Journal of Aeronautics 2024年第11期37卷 168-187页

作者： Yongbo YU Yanrong WANG Le HAN School of Energy and Power Engineering Beihang UniversityBeijing 100191China Collaborative Innovation Center for Advanced Aero-Engine Beijing 100191China Research Institute of Aero-Engine Beihang UniversityBeijing 100191China

The aeroelastic stability associated with the acoustic wave propagation characteristics of transonic rotor blades was numerically investigated in this *** influence of the vibration frequency on the aerodynamic damping of the first bending mode was primarily considered at different speeds,including both work and stall *** found that the state of acoustic wave propagation associated with aeroelastic instability is closely related to rotational *** low speeds near stall points,the risk of aeroelastic instability is confined to the upstream cut-off ***,at high speeds near stall points,aeroelastic instability may occur in both the downstream cut-off state and the acoustic wave propagation state of the upstream cut-off frequency,further expanding the range of the acoustic wave propagation state in which aeroelastic instability can *** research findings show that for suction surfaces,aerodynamic work is affected not only by acoustic wave propagation characteristics,but also by shock waves,radial flow,and reflux in the flow ***,for pressure surfaces,the acoustic wave propagation characteristics play a significant *** aeroelastic instability occurs,negative damping predominantly arises from the pressure *** investigate why lower-order modes are more prone to aeroelastic instability,specific simulations were conducted for the first bending and twisting modes under different operating conditions in the downstream cut-on *** the vibration frequency significantly exceeds the downstream cutoff frequency,the blade phase is minimally influenced by acoustic wave propagation characteristics,and the rotor is aeroelastically stable in these ***,there is an approximately linear increase in the unsteady pressure amplitude with increasing vibration frequency,and the aerodynamic work is predominantly influenced by the unsteady pressure amplitude.

关键词： Aeroelastic stability Nodal diameter Aerodynamic damping Acoustic wave propagation characteristic vibration frequency

Numerical prediction of ground vibrations induced by LPG boiling liquid expansion vapour explosion(BLEVE)inside a road tunnel

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Underground Space 2023年第5期12卷 44-64页

作者： Ruishan Cheng Wensu Chen Hong Hao Jingde Li Center for Infrastructural Monitoring and Protection School of Civil and Mechanical EngineeringCurtin UniversityBentley 6102Australia Earthquake Engineering Research&Test Center Guangzhou UniversityGuangzhou 510006China

Accidental boiling liquid expansion vapour explosions(BLEVEs)caused by the bursting of liquified petroleum gas(LPG)tank inside a tunnel can induce vibrations of its surrounding geological media and threaten the stability of adjacent tunnels and ***,it is essential to understand the characteristics of vibrations induced by LPG BLEVEs inside the tunnel for the safety design of its adjacent *** to the difficulty in effectively predicting the LPG BLEVE loads,the current practice usually employs equivalent methods,e.g.,the TNT-equivalency method,in LPG BLEVE load predictions for structural response analysis,which may lead to inaccurate response *** study compares ground vibrations induced by a BLEVE inside an arched road tunnel with those induced by its equivalent TNT explosion via high-fidelity numerical *** results demonstrate that the frequency of BLEVEinduced vibrations is lower than that induced by the TNT explosion at the same scaled *** intensity of LPG BLEVE-induced vibrations at relatively small-scaled distances is lower than that of TNT explosion-induced vibrations at the same scaled distance,but becomes higher after a certain scaled distance because of the relatively low attenuation *** addition,parametric analysis is conducted to evaluate the effects of various factors on the characteristics of LPG BLEVE-induced ground *** is found that the surrounding rock type,the rock porosity,and the cover depth of the tunnel have more significant influences than the concrete grade of the tunnel *** recommendation for the tunnel design is also given based on the intensity and frequency characteristics of BLEVE-induced vibrations.

关键词： Tunnel BLEVE TNT explosion vibration intensity vibration frequency

Quantum Chemical Calculations and Experimental Studies on 2,3-Diphenyl-tetrazole-5-thione

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Chinese Journal of Structural Chemistry 2004年第10期23卷 1117-1122页

作者：赵朴素卑凤利杨绪杰汪信陆路德建方方侯玉霞 Materials Chemistry Laboratory Nanjing University of Science and Technology Nanjing 210094 ChinaDepartment of Chemistry Huaiyin Teachers' College Huaiyin 223001 China Materials Chemistry Laboratory Nanjing University of Science and Technology Nanjing 210094 China New Materials & Function Coordination Chemistry Laboratory Qingdao University of Science and Technology Qingdao 266042 China

Diphenyl-tetrazole-5-thione has been synthesized and characterized by X-ray diffraction analysis and FTIR spectra. The extended MO calculations by using density functional theory (DFT) and self-consistent field molecular orbital Hartree-Fock theory with 6-31gG* basis set were carried out. The optimized structure and atomic charge distributions have been investi- gated, showing the exocyclic sulfur atom has the biggest negative charge value and this site is the most likely site of protonation and methylation as well as the potential coordination site with metallic ions. The predicted harmonic vibration frequencies are compared to the experimental values. On the basis of vibrational analyses, the thermodynamic properties of this compound at different temperature have been calculated, revealing the correlations between C0p, m, S0m, H0m and temperature.

关键词： density functional theory Hartree-Fock theory vibration frequency thermodynamic property

Changes in the natural frequency of a ferromagnetic rod in a magnetic field due to magnetoelastic interaction

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Applied Mathematics and Mechanics(English Edition) 2008年第8期29卷 1023-1032页

作者：王省哲 Key Laboratory of Mechanics on Western Disasters and Environment Lanzhou University Lanzhou 730000P.R.China

Based on the magnetoelastic generalized variational principle and Hamilton＇s principle, a dynamic theoretical model characterizing the magnetoelastic interaction of a soft ferromagnetic medium in an applied magnetic field is developed in this paper. From the variational manipulation of magnetic scale potential and elastic displacement, all the fundamental equations for the magnetic field and mechanical deformation, as well as the magnetic body force and magnetic traction for describing magnetoelastic interaction are derived. The theoretical model is applied to a ferromagnetic rod vibrating in an applied magnetic field using a perturbation technique and the Galerkin method. The results show that the magnetic field will change the natural frequencies of the ferromagnetic rod by causing a decrease with the bending motion along the applied magnetic field where the magnetoelastic buckling will take place, and by causing an increase when the bending motion of the rod is perpendicular to the field. The prediction by the mode presented in this paper qualitatively agrees with the natural frequency changes of the ferromagnetic rod observed in the experiment.

关键词： ferromagnetic rod magnetoelastic interaction generalized variational principle vibration frequency perturbation method