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1
Abbas, Abbas Fadhil, und Adawiya Ali Hamzah. „Studying the Thermal Influence on the Vibration of Rotating Blades“. Measurement Science Review 22, Nr. 2 (12.03.2022): 65–72. http://dx.doi.org/10.2478/msr-2022-0008.
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Abstract Computing the vibrating characteristics of any machine or structure is a necessary process that should be performed by the mechanical engineers that work in engineering design field to avoid the collapse under different kinds of applied loads. One of these kinds of structures are the rotating blades, whereas this part is considered as an essential element in many rotating systems that are used in different fields of engineering, e.g., turbomachinery, turbofan, helicopters, etc. One of the biggest disadvantages that is realized in rotating blades is failure due to vibrations and unbalance. It is possible that vibrations significantly reduce the performance of rotating blades compared to standard design conditions. If these rotating blades continue to operate under these circumstances for sufficient time, then the status of these systems will be unstable. Finally, this will lead to collapse of the rotating blades. In this work, a new code was created from scratch, based on the finite element method, to determine the vibrational characteristics of the rotating blades, taking into consideration the effect of rotating speed and temperatures. The compound influence of thermal gradients and rotating speed on the vibrational response (frequencies) for different configurations of blade was studied deeply.
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Ren, Fushen, Baojin Wang und Suli Chen. „Nonlinear Modeling and Qualitative Analysis of Coupled Vibrations in a Drill String“. International Journal of Bifurcation and Chaos 28, Nr. 10 (September 2018): 1850119. http://dx.doi.org/10.1142/s0218127418501195.
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A coupled model for axial/torsional/lateral vibrations of the drill string is presented, in which the nonlinear dynamics and qualitative analysis method are employed to find out the key factors and sensitive zone for coupled vibration. The drill string is simplified as an equivalent shell under axial rotation. After dimensionless processing, the mathematical model for coupled axial/torsional/lateral vibrations of the drill string is obtained. The Runge–Kutta–Fehlberg method is employed for the numerical simulation, and the rules that govern the changing of the torsional and axial excitation are revealed. And the stability domains of the explicit Runge–Kutta method are analyzed. Furthermore, the suggestions for field applications are also presented. It is demonstrated by simulation results that the lateral/axial/torsional vibrations exist simultaneously and couple with each other. The system will obtain a stable period motion with an axial excitation zone before the coupled vibration in the three directions, and continue to increase the axial excitation to cause the coupled vibration easily. The torsional excitation of the drill string mainly contributes to the coupled vibration in the three directions when in a specific rotation speed zone. The system is more likely to obtain a periodic motion through adjusting the torsional excitation out of this zone.
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Wi, Daehan, und Angela A. Sodemann. „Exploring User Perception Challenges in Vibrotactile Haptic Display Using Resonant Microbeams under Contact with Skin“. Multimodal Technologies and Interaction 3, Nr. 2 (28.05.2019): 38. http://dx.doi.org/10.3390/mti3020038.
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Resonant vibrotactile microbeams use the concept of resonance to excite the vibration of cantilever beams, which correspond to pixels of an image. The primary benefit of this type of tactile display is its potential for high resolution. This paper presents the concept of the proposed system and human skin contact experiments to explore user perception challenges related to beam vibration during skin contact. The human skin contact experiments can be described in five phases: dried skin contact to metal beam tips, wet and soaped skin contact to metal beam tips, skin contact with a constraint, normal force measurement, and skin contact to the tips of silicone rubber beams attached to metal beam tips. Experimental results are analyzed to determine in what cases of skin contact the beams stop vibrating. It is found that the addition of silicone rubber beams allows the primary metal beams to continue vibrating while in contact with skin. Thus, the vibration response of a metal beam with silicone rubber beams is investigated for the better understanding of the effect of silicone rubber beams on the metal beam vibration.
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Pathak, Prabhat, Jeongin Moon, Se-gon Roh, Changhyun Roh, Youngbo Shim und Jooeun Ahn. „Application of vibration to the soles reduces minimum toe clearance variability during walking“. PLOS ONE 17, Nr. 1 (04.01.2022): e0261732. http://dx.doi.org/10.1371/journal.pone.0261732.
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Minimum toe clearance (MTC) is an important indicator of the risk of tripping. Aging and neuromuscular diseases often decrease MTC height and increase its variability, leading to a higher risk of tripping. Previous studies have developed visual feedback-based gait training systems to modify MTC. However, these systems are bulky and expensive, and the effects of the training continue only for a short time. We paid attention to the efficacy of vibration in decreasing the variability of gait parameters, and hypothesized that proper vibration applied to soles can reduce the MTC variability. Using shoes embedded with active vibrating insoles, we assessed the efficacy of both sub- and supra-threshold vibration in affecting MTC distribution. Experiment results with 17 young and healthy adults showed that vibration applied throughout the walking task with constant intensity of 130% of sensory threshold significantly decreased MTC variability, whereas sub-threshold vibration yielded no significant effect. These results demonstrate that a properly designed tactile sensory input which is controlled and delivered by a simple wearable device, the active insole, can reduce the MTC variability during walking.
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Liu, Jiantao, und Xiaoxiang Yang. „Learning to See the Vibration: A Neural Network for Vibration Frequency Prediction“. Sensors 18, Nr. 8 (02.08.2018): 2530. http://dx.doi.org/10.3390/s18082530.
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Vibration measurement serves as the basis for various engineering practices such as natural frequency or resonant frequency estimation. As image acquisition devices become cheaper and faster, vibration measurement and frequency estimation through image sequence analysis continue to receive increasing attention. In the conventional photogrammetry and optical methods of frequency measurement, vibration signals are first extracted before implementing the vibration frequency analysis algorithm. In this work, we demonstrate that frequency prediction can be achieved using a single feed-forward convolutional neural network. The proposed method is verified using a vibration signal generator and excitation system, and the result compared with that of an industrial contact vibrometer in a real application. Our experimental results demonstrate that the proposed method can achieve acceptable prediction accuracy even in unfavorable field conditions.
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Hale, Michael, und Jesse Porter. „Validation Techniques for 6-DOF Vibration Data Acquisition“. Journal of the IEST 55, Nr. 1 (01.10.2012): 10–24. http://dx.doi.org/10.17764/jiet.55.1.27662m34h12v32p6.
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Multiple Degree of Freedom (MDOF) excitation systems and MDOF vibration control systems continue to improve, and are now standard equipment in many dynamic test laboratories. Determination of an input specification for such MDOF systems is critically dependent on properly acquired field data. Validation of field data will be discussed and demonstrated employing the same transformation tools used in both transformation-based 6-degree-of-freedom (6-DOF) vibration control and generalized MDOF vibration specification development (VSD).
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Hale, Michael. „A 6-DOF Vibration Specification Development Methodology“. Journal of the IEST 54, Nr. 2 (01.10.2011): 103–15. http://dx.doi.org/10.17764/jiet.54.2.j6tr2r787846931n.
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Multiple degree of freedom (MDOF) excitation systems and MDOF vibration control systems continue to improve, and are now standard equipment in many dynamic test laboratories. This paper concentrates on the often overlooked process of determination of an input specification for such MDOF systems. A pair of generalized six-degree-of-freedom (6-DOF) vibration specification development (VSD) techniques are proposed, discussed, and illustrated through an example.
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Younis, Adel, Fadi AlKhatib und Zuomin Dong. „Optimal Motorcycle Engine Mount Design Parameter Identification Using Robust Optimization Algorithms“. Algorithms 15, Nr. 8 (03.08.2022): 271. http://dx.doi.org/10.3390/a15080271.
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Mechanical vibrations have a significant impact on ride comfort; the driver is constantly distracted as a result. Volumetric engine inertial unbalances and road profile irregularities create mechanical vibrations. The purpose of this study is to employ optimization algorithms to identify structural elements that contribute to vibration propagation and to provide optimal solutions for reducing structural vibrations induced by engine unbalance and/or road abnormalities in a motorcycle. The powertrain assembly, swing-arm assembly, and vibration-isolating mounts make up the vibration-isolating system. Engine mounts are used to restrict transferred forces to the motorbike frame owing to engine shaking or road irregularities. Two 12-degree-of-freedom (DOF) powertrain motorcycle engine systems (PMS) were modeled and examined for design optimization in this study. The first model was used to compute engine mount parameters by reducing the transmitted load through the mounts while only considering shaking loads, whereas the second model considered both shaking and road bump loads. In both configurations, the frame is infinitely stiff. The mount stiffness, location, and orientation are considered to be the design parameters. The purpose of this study is to employ computational methods to minimize the loads induced by shaking forces. To continue the optimization process, Grey Wolf Optimizer (GWO), a meta-heuristic swarm intelligence optimization algorithm inspired by grey wolves in nature, was utilized. To demonstrate GWO’s superior performance in PMS, other optimization methods such as a Genetic Algorithm (GA) and Sequential Quadratic Programming (SQP) were used for comparison. To minimize the engine’s transmitted force, GWO was employed to determine the optimal mounting design parameters. The cost and constraint functions were formulated and optimized, and promising results were obtained and documented. The vibration modes due to shaking and road loads were decoupled for a smooth ride.
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Wei, Shuang. „Research on wind resistance principles and design of super high-rise buildings“. Applied and Computational Engineering 62, Nr. 1 (20.05.2024): 7–14. http://dx.doi.org/10.54254/2755-2721/62/20240371.
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Due to the high and flexible characteristics of super high-rise buildings, the structure is very sensitive to wind loads, and wind vibration effects and comfort are issues that cannot be ignored in the structural design of super high-rise buildings. The paper mainly introduces the problems in wind resistance design of super high-rise buildings. Including wind load values, wind vibration effects, and vibration control methods and applications. The result show that the wind induced vibration effect and comfort of the structure are often determined through wind tunnel tests. For super high-rise buildings with complex structural forms. There are two methods for controlling wind-induced vibration in high-rise buildings: Optimizing structural form through architectural methods; Take structural control measures. At the same time, with the cost of high-performance materials and engineering technologies, it is a challenge to find building materials and technologies that can meet wind resistance requirements while keeping costs in check. However, as computational technology continues to evolve, the wind-resistant design of tall buildings will benefit from more accurate wind-tunnel simulations and computational modelling, which will help to better predict and address wind-resistance challenges. Scientists and engineers will continue to research novel materials and structural designs to improve the wind resistance of tall buildings and reduce costs.
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Matsuda, Toru, und Ryuta Tomita. „Study on vibration measurement and sensory evaluation of combined vibration for detached houses“. INTER-NOISE and NOISE-CON Congress and Conference Proceedings 268, Nr. 8 (30.11.2023): 904–13. http://dx.doi.org/10.3397/in_2023_0143.
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Sensory and psychological content accounts for 90% of all vibration complaints in Japan. Therefore, evaluation based on vibration sensation is very important. Traffic vibration is the most common source of vibration that causes complaints, when limited to detached houses. If traffic vibration is the source of complaints, occupants will suffer from vibration for a long period of time. Vibration transmitted by traffic to housing floors may not be either vertical or horizontal, but rather a combination of both vertical and horizontal vibration that exceed perceptual thresholds. Japanese standards include "JIS C 1510" and "AIJES-V0001-2018". However, they do not describe methods for sensory evaluation of combined vibration. Although ISO 2631 series describes it, it is necessary to consider whether it can be applied to Japan as it is. Considering that traffic networks will continue to develop in Japan, especially in urban areas, it is assumed that the vibration generated inside houses, mainly from traffic vibration sources, will not be a single vibration of vertical or horizontal vibration, but a combined vibration that is perceived in multiple directions. Therefore, in this paper, vibration measurement and sensory evaluation of combined vibration were examined using a real house vibrated by traffic.
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Bloomfield, Eli, und Muhammad Salman. „Numerical investigation on the effects of wake-induced vibration fluid flow over airfoil geometries“. Journal of the Acoustical Society of America 152, Nr. 4 (Oktober 2022): A233. http://dx.doi.org/10.1121/10.0016117.
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Currently, many companies are looking to innovate and decrease economic and environmental impacts in the aerospace, energy, and marine sectors. As companies continue to innovate, airfoil designs used in the aerospace, wind turbine, commercial, and military marine industries, the lighter materials used are more susceptible to fatiguing failures due to vibrations. When these geometries encounter unsteady flow, the airfoil creates a vibration response. If the vibration response is near the natural frequency of the airfoil geometry, catastrophic failure can occur. This paper analyzes the correlation between geometry and frequency response for NACA symmetric airfoils in unsteady flow due to von Karman vortex shedding. The correlation between the shedding frequency of the cylinder and the frequency response of the airfoil is also considered. The paper also aims to determine if there is a correlation between geometry and frequency response amplitude across the frequency spectrum and at the natural frequency of each airfoil. These results were compared to the airfoil natural frequency, determined through Finite Element Analysis (FEA).
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Zhao, Long Sheng, und Jin Wu Wu. „Natural Frequency and Vibration Modal Analysis of Composite Laminated Plate“. Advanced Materials Research 711 (Juni 2013): 396–400. http://dx.doi.org/10.4028/www.scientific.net/amr.711.396.
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In this paper,a layer-wise theory is used to analyze the natural frequency and vibration modal of the composite laminated plate. Layer-wise theory assumes that displacement is continue through thickness direction and has good accuracy to analyze free vibration. The frequency and vibration modal are acquired while building the equation of motion according to layer-wise theory. Through comparing layer-wise theory and other theories, numerical results show that layer-wise theory is credible to analyze composite laminated plate. At the same time, experiment is used in this paper to acquire the natural frequencies and vibration modal of a simply supported composite laminated plate. Lastly, combination of the theory method and experiment method canprobably predict the natural frequencies and vibration modal.
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Vallejo, Marcela, Francisco Luis Villa-Restrepo, Cherlly Sánchez-González und Edilson Delgado-Trejos. „Metrological Advantages of Applying Vibration Analysis to Pipelines: A Review“. Scientia et Technica 26, Nr. 1 (30.03.2021): 28–35. http://dx.doi.org/10.22517/23447214.24351.
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Flow rate is a necessary variable in industrial processes and, therefore, there is a wide variety of instruments designed to measure it. However, the most accepted measuring devices have the problem of being invasive or intrusive. The scientific and technological challenge is to achieve measurement by exploiting all the phenomenological possibilities using a non-intrusive, easy-to-install, portable and low-cost mechanism. This paper presents a literature review on the use of vibration analysis in flow rate metrological systems in order to identify research opportunities for the indirect measurement of this magnitude. A promising line of work was found based on soft flow rate sensors that use the analysis of pipeline vibrations integrated into computational intelligence routines, which allows inference of the flow rate value. The findings promote to continue with new technical and scientific challenges.
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Zheng, Gaoan, Zeheng Gu, Weixin Xu, Bin Lu, Qihan Li, Yunfeng Tan, Chengyan Wang und Lin Li. „Gravitational Surface Vortex Formation and Suppression Control: A Review from Hydrodynamic Characteristics“. Processes 11, Nr. 1 (25.12.2022): 42. http://dx.doi.org/10.3390/pr11010042.
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The energy-conversion stability of hydropower is critical to satisfy the growing demand for electricity. In low-head hydropower plants, a gravitational surface vortex is easily generated, which causes irregular shock vibrations that damage turbine performance and input-flow stability. The gravitational surface vortex is a complex fluid dynamic problem with high nonlinear features. Here, we thoroughly investigate its essential hydrodynamic properties, such as Ekman layer transport, heat/mass transfer, pressure pulsation, and vortex-induced vibration, and we note some significant scientific issues as well as future research directions and opportunities. Our findings show that the turbulent Ekman layer analytical solution and vortex multi-scale modeling technology, the working condition of the vortex across the scale heat/mass transfer mechanism, the high-precision measurement technology for high-speed turbulent vortexes, and the gas–liquid–solid three-phase vortex dynamics model are the main research directions. The vortex-induced vibration transition mechanism of particle flow in complex restricted pipelines, as well as the improvement of signal processing algorithms and a better design of anti-spin/vortex elimination devices, continue to draw attention. The relevant result can offer a helpful reference for fluid-induced vibration detection and provide a technical solution for hydropower energy conversion.
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Zheng, Gong Ming, Yuan Yuan Shen und Ling Ling Song. „Vibroseis Nonlinear Scanning Signal Simulation Analysis“. Applied Mechanics and Materials 318 (Mai 2013): 191–95. http://dx.doi.org/10.4028/www.scientific.net/amm.318.191.
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Vibrator nonlinear scan is an important means of high frequency seismic exploration. With the propagation of seismic waves, High frequency components continue to be absorbed, due to the filtering effect of the earth. Nonlinear scanning technology can get some degree of compensation to the seismic wave loss in the high frequency part in the propagation, by extending the vibration of the high frequency component time. This article through MATLAB simulation, this paper analyzed the nonlinear scanning signals in scanning signals and logarithmic index scanning signals, and the similarities and differences between the two signals are summarized.
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Melentev, Andrey V., und Oleg A. Oshkoderov. „Assessment of the diagnostic significance of modern biomarkers and hemodynamic alterations in workers of vibration-hazardous occupations“. HEALTH CARE OF THE RUSSIAN FEDERATION 65, Nr. 4 (07.09.2021): 379–83. http://dx.doi.org/10.47470/0044-197x-2021-65-4-379-383.
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Introduction. One of the most significant tasks in modern labor medicine is to reduce the indicators of early disability in persons in contact with harmful and dangerous factors of the production environment. The issue of finding markers of early preclinical manifestations of vibrational disease and establishing comorbid conditions that are prognostically unfavorable for the course of the underlying occupational disease remains relevant. The purpose of the study is assessment of diagnostic significance of current neurospecific biomarkers and hemodynamic changes in workers of the profession related to vibration. Material and methods. The results of two studies were the basis for this work. The first, aimed at determining the concentration of neurospecific markers in the blood of miners, includes 154 working vibration hazardous professions. At the same time, groups were identified depending on the type of exposure to vibration: total (69 workers), local (24 workers) and combined general and local (61 miners) and control group of workers not in contact with vibration (49 people). The second study was performed to assess the change in hemodynamic parameters among 216 industrial workers, of which 114 people were in contact with vibration generating equipment, and 102 workers were included in the control group. Results. Data from the first study showed an increase in the titer of neuron-specific indicators, mainly protein S100B, depending on the type of exposure vibration and its seniority dose. The second study results indicated an increase in systolic blood pressure and total peripheral vascular resistance in miners under exposure to vibration factor. Conclusion. The results of both studies suggest that hemodynamic disorders and changes in the performance of neuro specific proteins may be interconnected. It seems advisable to continue the study in workers in vibrant occupations with comorbid pathology.
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Kernytskyy, Ivan, Serhii Baranovych, Serhii Berezovetskyi, Bohdan Diveyev, Orest Horbay und Ihor Stukalets. „Vibration absorber optimization for boom-sprayer“. Przegląd Naukowy Inżynieria i Kształtowanie Środowiska 27, Nr. 4 (10.01.2019): 504–15. http://dx.doi.org/10.22630/pniks.2018.27.4.47.
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The main task of this work is to analyze optimal design-system of the booms of boom-sprayers. The discrete-continue models of machines dynamics of such wheeled machines as boom-sprayer with elongated boom element with the attachment of dynamic vibration absorbers are offered. The algorithms for vibration decreasing of boom are received. The new vibroabsorbing elements are proposed. The paper contemplates the provision of dynamic vibration absorbers (DVA) of buffered impact masses and particle type. Such originally designed absorbers reduce vibration selectively in maximum vibration mode, without introducing vibration in other modes. The damping results from the exchange of momentum during impacts among the masses and masses and stops as the structure vibrates. A technique is developed to give the optimal DVA’s as single degree of freedom (SDOF) buffered system. The one-digit values are established not only for the dynamic vibration absorber parameters, but also for mechanical parameter of base structure – boom in connection points of the dynamic vibration absorbers. Finally, present research develops the genetic algorithms for optimal design searching by discrete-continuum DVA’s system – base system modeling.
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Ferri, A. A. „Friction Damping and Isolation Systems“. Journal of Mechanical Design 117, B (01.06.1995): 196–206. http://dx.doi.org/10.1115/1.2836456.
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This paper surveys the literature on the use of dry friction in passive damping and vibration isolation. Several analytical techniques are presented followed by applications from various areas. Despite difficulties in the analytical and experimental treatment of friction damped systems, numerous studies have endeavored to predict, measure, and/or enhance the energy dissipation and vibration isolation properties of dry friction in order to improve system performance. Undoubtedly, friction damping will continue to play an important role in many mechanical and structural systems.
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Ferri, A. A. „Friction Damping and Isolation Systems“. Journal of Vibration and Acoustics 117, B (01.06.1995): 196–206. http://dx.doi.org/10.1115/1.2838663.
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This paper surveys the literature on the use of dry friction in passive damping and vibration isolation. Several analytical techniques are presented followed by applications from various areas. Despite difficulties in the analytical and experimental treatment of friction damped systems, numerous studies have endeavored to predict, measure, and/or enhance the energy dissipation and vibration isolation properties of dry friction in order to improve system performance. Undoubtedly, friction damping will continue to play an important role in many mechanical and structural systems.
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Zahedinejad, Parham, Chen Zhang, Haifeng Zhang und Shuai Ju. „A Comprehensive Review on Vibration Analysis of Functionally Graded Beams“. International Journal of Structural Stability and Dynamics 20, Nr. 04 (April 2020): 2030002. http://dx.doi.org/10.1142/s0219455420300025.
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Beams and beam structures are structural components commonly used in mechanical, aerospace, nuclear, and civil engineering. To meet the different engineering design limitations such as operational conditions, weight, and vibrational characteristics, these components may be made of various materials such as functionally-graded materials (FGMs), composites, and homogeneous materials. Functionally-graded (FG) beams play a key role not only in classical structural applications, but also have vast applications in thermal, electric-structural and electric-thermal-structural systems, e.g. in the form of FG beam energy harvesters, sensors and actuators. In all these applications, using new materials like FGMs can greatly improve the efficiency of the structural components and systems. Since FG beams are mostly used as moving components in engineering structures, vibration analysis of these components has been studied by numerous researchers. In order to solve the governing equation and related boundary conditions of the FG beams, powerful numerical methods with a high level of accuracy and fast rate of convergence are often required. The differential quadrature method (DQM) is a powerful and reliable numerical method which has been extensively used by researchers to perform the vibration analyses of FG structures in the last decade. In this paper, firstly various mathematical models which have been used to express the material properties of FGMs are reviewed. Secondly different elasticity theories which have been applied in vibration analysis of FG beams are summarized. In addition, a review on the DQM and its applications is presented. At the next step, a comprehensive review on free vibration analyses of FG beams based on different elasticity theories and in particular those using the DQM is performed. In continue, a brief review on the application of other numerical methods in vibration analysis of FG beams is presented. Moreover, because of the importance of nonlinear vibration analysis of FG beams, a review on the application of various numerical methods and different elasticity theories on nonlinear vibration analysis of FG beams is performed. Finally, a brief review on linear and nonlinear vibration analysis of FG microbeams, as a special type of FG beams, is presented.
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Lee, Hsin-Min, und Tzung-Ming Chen. „A Study of Polishing Feature of Ultrasonic-Assisted Vibration Method in Bamboo Charcoal“. Advances in Materials Science and Engineering 2017 (2017): 1–7. http://dx.doi.org/10.1155/2017/6750467.
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Focusing on the feature of porosity in bamboo charcoal, this study applies the ultrasonic-assisted vibration method to perform surface polishing of the silicon wafer workpiece. The self-developed bamboo charcoal polishing spindle and ultrasonic- assisted vibration mechanism are attached to a single lapping machine. In the machining process, ultrasonic vibration enables the diamond slurry to smoothly pass through the microscopic holes of bamboo charcoal; the end of the bamboo charcoalis able to continue machining on the surface of the workpiece through the grasping force which exists in the microscopic holes. Under the polishing and machining parameters of ultrasonic-assisted vibration, with a diamond slurry concentration of 0.3%, the experimental results show a polishing time of 20 min, a loading of 25 N on the workpiece surface, a spindle speed of 1200 rpm, a vibration frequency of 30 kHz and the original surface roughness value of Ra 0.252 μm equals that of a mirror-like surface at Ra 0.017 μm. These research results prove that by using bamboo charcoal and ultrasonic-assisted vibration for polishing, a very good improvement can be achieved on the workpiece surface.
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Syurin, Sergey A., und V. V. Shilov. „The characteristics of vibration disease of miners in conditions of modern technologies of mining ore raw materials in the Kola High North“. Health Care of the Russian Federation 60, Nr. 6 (24.05.2019): 312–16. http://dx.doi.org/10.18821/0044-197x-2016-60-6-312-316.
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The study was carried out to analyze characteristics of development of vibration disease in miners of mineral resources' industry enterprises of the Kola High North in 1989-2013. Altogether, in miners of 16 professions 509 cases of primarily diagnosed vibration disease were established that amounted to 22.5% of all cases of occupational diseases. The vibration disease ranked second place in the structure of occupational pathology after diseases of musculo-skeletal system. During the analyzed period, the following characteristics of vibration pathology were established: 1. significant increasing of prevalence of vibration disease (especially in 2004-2013); 2. increasing among patients with vibration disease number of workers mainly involved into loading delivering operations (from 19,3% to 62,6%) and decreasing of percentage of workers involved into sinking and drilling operations; 3. increasing up to 11.1 years of duration of labor experience until moment of primary detection of vibration disease; 4. increasing from 7,7% to 69,5% of percentage of expressed clinical forms of vibration disease (vibration disease stage II) and decreasing of percentage of vibration disease with initial clinical manifestations of vibration disease (vibration disease stage I) among primarily diagnosed cases. Therefore, implementation of modern mining engineering with decreased levels of vibration and application of modern techniques of early diagnostic and prevention of vibration pathology and also organizational activities targeted to decreasing of level of impact of hazardous industrial factors resulted in no decreasing of risk of development of vibration disease in miners of mineral resources' industry enterprises of the Kola High North. The obtained data testify that statistical indices ofprevalence and severity of vibration pathology depend on interaction of many differently directed factors. Among these factors are labor conditions, level of medical preventive activities, quality of medical examinations and expertise decisions concerning relationship between health disorders and labor conditions, motivation to continue labor activity, etc.
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Ayad, Mouloud, Kamel Saoudi, Mohamed Rezki, Mourad Benziane und Abderrazak Arabi. „Early Detection of Defects in Gear Systems Using Autocorrelation of Morlet Wavelet Transforms“. Strojniški vestnik - Journal of Mechanical Engineering 68, Nr. 1 (02.02.2022): 56–65. http://dx.doi.org/10.5545/sv-jme.2021.7384.
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The supervision task of industrial systems is vital, and the prediction of damage avoids many problems. If any system defects are not detected in the early stage, this system will continue to degrade, which may cause serious economic loss. In industrial systems, the defects change the behaviour and characteristics of the vibration signal. This change is the signature of the presence of the defect. The challenge is the early detection of this signature. The difficulty of the vibration signal is that the signal is very noisy, non-stationary and non-linear. In this study, a new method for the early defect detection of a gear system is proposed. This approach is based on vibration analysis by finding the defect’s signature in the vibration signal. This approach has used the autocorrelation of Morlet wavelet transforms (AMWT). Firstly, simulation validation is introduced. The validation of the approach on a real system is given in the second validation part.
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Li, Lin, Yuanshan Yang, Weixin Xu, Bin Lu, Zeheng Gu, Jianguo Yang und Dapeng Tan. „Advances in the Multiphase Vortex-Induced Vibration Detection Method and Its Vital Technology for Sustainable Industrial Production“. Applied Sciences 12, Nr. 17 (26.08.2022): 8538. http://dx.doi.org/10.3390/app12178538.
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Fluid-induced vibration detection technology for the multiphase sink vortex can help achieve efficient, safe, and low-carbon sustainable industrial production in various areas such as the marine, aerospace, and metallurgy industries. This paper systematically describes the basic principles and research status in light of the important issues related to this technology in recent years. The primary issues that occur in practical application are highlighted. The vital technologies involved, such as the vortex-formation mechanism, interface dynamic evolution, the shock vibration response of thin-walled shells, and vortex-induced vibration signal processing algorithms, are analyzed. Based on in-depth knowledge of the technology, some significant scientific challenges are investigated, and further research prospects are suggested. The research results show that this technology can achieve the real-time detection of vortex-induced vibration states. Two future research directions are those of exploring multiphysical field coupling under harsh conditions and more accurate modeling methods for multiphase coupling interfaces. Regarding vortex-induced vibration, forced-vibration characters with various restriction conditions, the forced-vibration displacement response of liquid-filled shells, intrinsic properties influenced by random excitation forces, and highly effective distortion-detection algorithms will continue to attract more attention. The associated results could give technical support to various fields, including energy-efficiency improvement in manufacturing processes, tidal power generation condition monitoring, and the performance optimization of low-carbon energy components.
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Hu, Jianyong, Chaohao Wang, Chengju Shan und Yunhui Guo. „Monitoring and Analysis of the Operation Performance of Vertical Centrifugal Variable Frequency Pump in Water Supply System“. Energies 16, Nr. 11 (05.06.2023): 4526. http://dx.doi.org/10.3390/en16114526.
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The stable operation of a variable frequency pump is of great importance to the management of a water supply project. Analyzing the operation performance based on monitoring data is necessary for maintaining the stable operation of a variable frequency pump. Several sensors are installed at six monitoring points on the pump to collect signals including vibration velocity, vibration acceleration and vibration displacement. Monitoring signals are preprocessed by smoothing, adjusting waveform trend and filtering on the basis of Fast Fourier Transform (FFT). Then, the vibration features are extracted by power spectrum analysis and cepstrum analysis methods. According to the extracted features, the vibration law and actual operation performance of a variable frequency pump under different operating conditions are analyzed. Results indicate that the vibration amplitude of the pump varies sharply under the operating conditions of [15 Hz, 20 Hz] and [30 Hz, 35 Hz]. The operating condition of [0 Hz, 15 Hz] is the restricted operating area of the pump. The vibration and noise continue increasing under the operating conditions of [35 Hz, 50 Hz] and reach the maximum values at 50 Hz. Therefore, the optimal operating is within the range of [20 Hz, 30 Hz]. Finally, by analyzing the critical values of the operating conditions, the fault diagnosis and the evaluation of the operating status are conducted.
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Pujari, Amit N., Richard D. Neilson und Marco Cardinale. „Fatiguing effects of indirect vibration stimulation in upper limb muscles: pre, post and during isometric contractions superimposed on upper limb vibration“. Royal Society Open Science 6, Nr. 10 (Oktober 2019): 190019. http://dx.doi.org/10.1098/rsos.190019.
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Whole-body vibration and upper limb vibration (ULV) continue to gain popularity as exercise intervention for rehabilitation and sports applications. However, the fatiguing effects of indirect vibration stimulation are not yet fully understood. We investigated the effects of ULV stimulation superimposed on fatiguing isometric contractions using a purpose developed upper limb stimulation device. Thirteen healthy volunteers were exposed to both ULV superimposed to fatiguing isometric contractions (V) and isometric contractions alone Control (C). Both Vibration (V) and Control (C) exercises were performed at 80% of the maximum voluntary contractions. The stimulation used was 30 Hz frequency of 0.4 mm amplitude. Surface-electromyographic (EMG) activity of the Biceps Brachii, Triceps Brachii and Flexor Carpi Radialis were measured. EMG amplitude (EMGrms) and mean frequency (MEF) were computed to quantify muscle activity and fatigue levels. All muscles displayed significantly higher reduction in MEFs and a corresponding significant increase in EMGrms with the V than the Control, during fatiguing contractions ( p < 0.05). Post vibration, all muscles showed higher levels of MEFs after recovery compared to the control. Our results show that near-maximal isometric fatiguing contractions superimposed on vibration stimulation lead to a higher rate of fatigue development compared to the isometric contraction alone in the upper limb muscles. Results also show higher manifestation of mechanical fatigue post treatment with vibration compared to the control. Vibration superimposed on isometric contraction not only seems to alter the neuromuscular function during fatiguing efforts by inducing higher neuromuscular load but also post vibration treatment.
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Gu, Zhaoliang, Wenbing Zhu, Mengzhao Zhu, Longlong Li, Qingdong Zhu, Jian Wang und Haozhe Wang. „Gas Production Characteristics of UHV Oil immersed Shunt Reactor with Vibration Defects“. Journal of Physics: Conference Series 2564, Nr. 1 (01.08.2023): 012052. http://dx.doi.org/10.1088/1742-6596/2564/1/012052.
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Abstract The special multi-air gap structure of Ultra high voltage (UHV) oil-immersed shunt reactor determines that its magnetic leakage is far greater than that of a power transformer of the same voltage level, and it is more prone to vibration and other problems. Overheating and suspended discharge caused by vibration are important sources of excessive gas production in UHV shunt reactors. In this paper, the source of gas production under reactor vibration is analyzed, and a reactor defect simulation gas production platform is built. Using oil chromatography analysis, partial discharge detection, and other means, the gas production characteristics, discharge characteristics and insulation degradation characteristics of typical defects such as suspended discharge and partial overheating under vibration have been experimentally studied. Then, the correlation analysis model between the vibration type, intensity, overheating degree, and the reactor performance change was established. Finally, the gas production and discharge characteristics of the reactor under different defect types were obtained. Besides, gas production characteristics under vibration with 50 Hz, 100 Hz, and 150 Hz were carried out, and it was found that the gas will continue to increase with the increase of vibration frequency, and the growth has been stabilized after exceeding 100 Hz. The relevant research results of this paper can provide technical support for the application of UHV oil-immersed shunt reactor state assessment and diagnosis, and improve the level of equipment operation and maintenance.
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Lomboy, Orlando Ariola, Bernard Ablog De Vera, Maria Eden Cada Adona-Pizarro und Eleoreph Sarmiento Llabado. „Harnessing vibration energy from a rice-milling machine“. South Florida Journal of Development 3, Nr. 3 (07.06.2022): 3736–54. http://dx.doi.org/10.46932/sfjdv3n3-055.
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In the advent of a rat race for the exploration of alternative source of power, clean and green source of electrical power is deemed to be an extreme priority. Various groups of people, professionals and even students with wide spectrum of discipline untiringly continue to source-out electricity out of their own exploration capabilities. This study had focused on the extraction and conversion of a vibration energy from a moving strainer mechanism of a rice-milling machine. The researchers of this project undertaking were able to successfully fabricate a prototype that can extract the vibration energy from the said mechanism. The harnessed vibration energy was then converted to a usable electricity via a built-in converter circuit of the said prototype. The prototype was successfully tested in a local rice mill. The device was found to fully - charge a smart phone with an initial charge of five (5) per cent and to within a span of three (3) continuous hours. The device was also found to yield a maximum charging current of 500 milliamperes.
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Park, Sang, Myunghwan Jung und Joo Sung. „Influence of Physical and Musculoskeletal Factors on Occupational Injuries and Accidents in Korean Workers Based on Gender and Company Size“. International Journal of Environmental Research and Public Health 16, Nr. 3 (26.01.2019): 345. http://dx.doi.org/10.3390/ijerph16030345.
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Though the overall incidence of occupational injuries and accidents has decreased, they continue to happen. Many associated factors are known and managing them with limited resources is difficult. This study evaluates related risk factors and prioritizes their management for reducing occupational injuries and accidents at the workplace. We used data from the 4th Korean Working Condition Survey conducted by the Korea Occupational Safety Health Research Institute from June to September 2014. A total of 14,381 persons (9776 men, 4605 women) were selected; t-test, chi-square test, and logistic regression analyses were performed to analyze data. The influence of physical (vibration, noise, abnormal temperature) and musculoskeletal (awkward posture, handling of heavy objects, repetitive tasks) factors was compared according to gender and company size. The risk of occupational injuries and accidents among men was related to musculoskeletal factors and vibration in companies with “under 50” employees and with awkward posture, vibration, and noise in companies with “50 or above” employees; however, among women in companies with “under 50” employees, it was associated with only vibration. Although we evaluated only a few risk factors, prioritizing them based on gender and company size has provided new valuable information.
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Meng, Xiang Ran, Yu Zhao, Xiao Qian Wang, Peng Fei Xu, Wen Dong Zhang und Shu Bin Yan. „The Effect of Vibration Noise for Cavity Ring Down Time Extraction“. Key Engineering Materials 562-565 (Juli 2013): 1402–7. http://dx.doi.org/10.4028/www.scientific.net/kem.562-565.1402.
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A continue-wave cavity ring down experimental system is established surrounding the micro-sphere cavity. In the experiments of measuring micro-spheres cavity quality factor (Q) upon the system, it is found that photoelectric detectors with different response characteristic have different response to the optical signal which is shut off rapidly. The vibration noise caused by changes of external environment, meanwhile, can be transformed following the change of photoelectric detector properties. With the build of photoelectric detector response model, the mean-square deviation of repeated experiments under the same conditions is used for charactering level of the error caused by vibration noise. The influence of vibration noise to photoelectric detector is discussed in detail, and further analyzes the effect for the cavity ring down time extraction. Then the optimal photoelectric detector (Newfocus1434, 15V/W) is selected to optimize the experimental system. The level of error caused by vibration noise has been decreased from 0.191ns to 1.562ps. Finally, the Q value of micro-sphere cavity is calculated according to fitted value of cavity ring down time, and the experimental correctness is verified by the line-width law.
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Gamar, Farida, Rusdhianto Effendie Abdul Kadir und Achmad Jazidie. „Desain kontrol adaptif L1 dengan band pass filter orde dua untuk pengendali vibrasi pada rotor helikopter“. JURNAL ELTEK 21, Nr. 1 (30.04.2023): 1–9. http://dx.doi.org/10.33795/eltek.v21i1.380.
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Vibrasi pada helikopter menjadi konsentrasi tersendiri untuk terus ditingkatkan penanganannya. Hal ini dikarenakan selain dapat menyebabkan kerusakan struktur badan helikopter jika vibrasi yang dihasilkan terlalu besar juga berpengaruh pada kenyamanan pilot dan penumpang. Sistem vibrasi pada helicopter terdiri dari baling-baling, rotor mount, dan suspensi dimana terdapat damper sebagai peredam. Pada penelitian ini, digunakan damper semi aktif yang variabelnya dikontrol dengan menggunakan kontrol adaptif L1 berbasis analisis Fourier dari vibrasi yang dihasilkan oleh rotor. Analisis Fourier digunakan untuk mencari frekuensi cutoff vibrasi yang digunakan untuk penalaan pada kontrol adaptif L1. Hasil rancangan band pass filter orde 2 pada sistem dapat memperbaiki respon percepatan hingga 72.52% pada rotor mount dan 65.94% badan helicopter dalam waktu 2 detik. Hasil rancangan juga dapat menangani kesalahan perpindahan sebesar 55.6% pada rotor mount dan 55.56% pada badan helikopter dalam waktu 2 detik. Perbaikan respon percepatan pada badan helicopter yang mencapai 0 m/s2 telah memenuhi rekomendasi NASA untuk minimal percepatan pada sistem vibrasi helikopter.
ABSTRACT
Vibration in helicopters is a separate concentration to continue to improve its handling. This is because, in addition to causing damage to the helicopter body structure if the vibration generated are too large, it also affects the comfort of pilot and passengers. The vibration system on the helicopter consists of propeller, rotor mount, and suspension where there are dampers as dampers. In this research, a semi-active damper is used whose variables are controlled using Fourier analysis-based L1 adaptive control of the vibrations generated by the rotor. Fourier analysis is used to find the cutoff frequency of vibration used for tuning the L1 adaptive control. The results of the second-order band pass filter design in the system can improve the acceleration response up to 72.52% on the rotor mount and 65.94% of the helicopter body within 2 seconds. The design results can also handle displacement errors of 55.6% on the rotor mount and 55.56% on the helicopter body within 2 seconds. The improvement of the acceleration response on the helicopter body which reaches 0 m/s2 has required NASA's recommendations for minimum acceleration in helicopter vibration systems.
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Sands, William A., Jeni R. McNeal, Michael H. Stone, G. Gregory Haff und Ann M. Kinser. „Effect of Vibration on Forward Split Flexibility and Pain Perception in Young Male Gymnasts“. International Journal of Sports Physiology and Performance 3, Nr. 4 (Dezember 2008): 469–81. http://dx.doi.org/10.1123/ijspp.3.4.469.
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Serious stretching in many sports involves discomfort and is often an early ceiling on improvements.Purpose:To continue investigation of the use of vibration to enhance acute range of motion while assessing the influence of vibration and stretching on pressure-to-pain threshold perception.Methods:Ten young male gymnasts were assessed for split range of motion. One side split was randomly assigned as the experimental condition, and the other side split was assigned as the control. Both side splits were performed on a vibration device; the experimental condition had the device turned on and the control condition was performed with the device turned off. In addition, the athletes were assessed for pressure-to-pain transition using an algometer on the biceps femoris (stretched muscle) and vastus lateralis (nonstretched muscle) bilaterally.Results:Pre-post difference scores between the vibrated split (most improved) and the nonvibrated split were statistically different (P = .001, 95% confidence interval of the difference 2.3 to 5.8 cm). Following the stretching protocol, the force values for the pressure-to-pain threshold comparing the vibrated and nonvibrated biceps femoris muscle were not statistically different. The nonstretched vastus lateralis muscle also showed no statistical difference in pressure-to-pain threshold between the vibration and nonvibration conditions.Conclusion:This study showed that vibration improved split range of motion over stretching alone, but did not show a difference in pressure-to-pain perception in either the stretched or nonstretched muscles.
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Mironov, Victor, Janis Viba und Lauris Shtals. „Use of Electromagnetic Impulse System for Transportation of Dry Materials and Solid Bodies“. Solid State Phenomena 147-149 (Januar 2009): 474–79. http://dx.doi.org/10.4028/www.scientific.net/ssp.147-149.474.
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In first part of the report motion of magnetic powder materials in a vertical or inclined pipe are investigated. Mathematical models are analyzed, taking into account intensity of a pulse electromagnetic field, parameters of a powder and its interaction with the surface of the pipe and air. Experimental device, including control and measure system with the analysis of parameters by computer, is described. Second part of the report investigates a motion of non-magnetic materials. For this reason an additional magnetic container with open surface is used. After an impulse action the container stops before bound. Non-magnetic materials continue flying motion. In third part of the report the authors investigate motion excitation with impulse generator for plane vibrotransporters. It is shown that this excitation is very stable, because after impulse action the mechanical system continues vibration with a non-periodical motion and stops waiting for next impulse.
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Hawryszków, Paweł, Roberto Pimentel, Rafaela Silva und Felipe Silva. „Vertical Vibrations of Footbridges Due to Group Loading: Effect of Pedestrian–Structure Interaction“. Applied Sciences 11, Nr. 4 (03.02.2021): 1355. http://dx.doi.org/10.3390/app11041355.
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The vibration serviceability of footbridges has evolved from the adoption of a single pedestrian crossing in the resonance condition to load cases in which several pedestrians cross the structure simultaneously. However, in spite of this improvement, pedestrians continue to be considered as applied loads in codes of practice. Recent research has pointed out that modeling pedestrians as dynamic systems is a step further in the search for a more realistic design approach. This is explored in this paper, focusing on the case of vertical vibration. A two-span cable-stayed test structure was selected, and accelerations were measured from single and group crossings, both at the structure and at a pedestrian’s waist. Numerical simulations considering the pedestrians modeled as loads only and also as dynamic systems were implemented, and numerical and experimental time response vibration signatures were compared. Reductions of up to 25% and 20% in peak and RMS acceleration, respectively, were obtained when pedestrians were modeled as dynamic systems, in comparison with the less realistic model of pedestrians as loads only. Such reductions were shown to depend on the number of pedestrians involved in the group. The results, thus, highlight that pedestrian–structure interaction is an asset for the vibration serviceability design of footbridges.
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Widodo, Panut, Gunawan Dwi Haryadi und Achmad Widodo. „Induction Motor Centrifugal Blower Health Diagnostic Based on Color Segmentation of Thermal Image and Vibration Signal Feature“. MATEC Web of Conferences 159 (2018): 02002. http://dx.doi.org/10.1051/matecconf/201815902002.
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The rotating machinery requires condition monitoring which its measurement without being intrusive operation, especially on the equipment needed to continue running. One such machinery is a centrifugal blower induction motor. Infrared thermography and vibration are important and effective technologies to diagnose of health condition it without destructive or disturb of operations. The diagnostics of induction motor are based on the analysis results data onto vibration and processing thermal image. This paper focused on thermography image processing based on color segmentation which it will produce ROI (region of interest) images. The ROI image is extracted based on HSV color and shape feature. Feature extraction is intended to determine value of mean, standard deviation, kurtosis, skewness and entropy HSV and shape features (area, perimeter, metric, and eccentricity). The highest RMS (root mean square) vibration data is used as reference to classify data into normal and abnormal. Parameters that can be used to classify normal and abnormal conditions based on data analysis are standard deviation Hue, kurtosis HS, skewness HSV, entropy HSV and metric.
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Zhai, Changyuan, John Long, Randal Taylor, Paul Weckler und Ning Wang. „Field scale row unit vibration affecting planting quality“. Precision Agriculture 21, Nr. 3 (26.09.2019): 589–602. http://dx.doi.org/10.1007/s11119-019-09684-4.
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Abstract With recent developments allowing increased planter speeds, improving spatial uniformity of crop emergence will continue to be an important focus of research. Vertical vibration during planting usually interferes with the seed metering and delivery process, and thereby affects seeding quality. Two different row crop planters were instrumented with accelerometers to monitor vertical vibration of planter row units in five fields with a total area of 220 ha in both no-till and strip-tilled conditions. The test results showed that the row unit vibration linearly increased with planting speeds. The R2 of each fitting equation was more than 0.90. The main frequencies of the vibration were concentrated in a low-frequency band of 3 Hz to 10 Hz. These frequencies did not show an increasing trend with the planter speed. However, the amplitude clearly increased when the planter speed increased. For the John Deere MaxEmerge™ 5 planter, the manually measured average plant spacing was close to the target plant spacing with a maximum error of 21 mm, and a max coefficient of variation (CV) of 24.3%; the standard deviation (SD) increased with travel speed and row unit vibration. For the John Deere ExactEmerge™ planter, the plant spacing was closer to the target plant spacing with a maximum error of only 5 mm and a max CV of 14.3%; the SD remained almost constant, at lower values than that of the MaxEmerge™ 5, at different speeds. For both planters, overall, the row unit vibration increased planting spatial variability. The quality of feed index decreased with increased vertical acceleration on the row unit while the miss index increased. However, the multiples index was generally unaffected by row unit vibration.
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Ku, C. P. Roger. „Dynamic Characteristics of Hard Disk Drive Spindle Motors—Comparison Between Ball Bearings and Hydrodynamic Bearings“. Journal of Tribology 118, Nr. 2 (01.04.1996): 402–6. http://dx.doi.org/10.1115/1.2831316.
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Recently, many computer hard disk drive companies and spindle motor manufacturers have been looking for a substitute for ball bearings to continue making dramatic progress in increasing the capacity of data storage systems. In this paper, the frequency-forced responses of hard disk drive spindle motors supported by both ball bearings and liquid-lubricated spiral groove hearings (SGBs) were studied experimentally. It is found that both shaft rigidity and disk flexibility have great effects on the natural frequency of the spindle motor conical (rocking) mode. The high damping capacity of the SGB is able to suppress the vibration amplitudes of both motor rocking mode and the flexible disk modes. But at a very low frequency range, the SGB motors displayed a large amplitude in the axial direction vibration test. With an adequate bearing design, the SGB motors have proven their superior dynamic characteristics.
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Mao, Qibo, und Stanislaw Pietrzko. „Active Control of a Beam for Generating Points of Zero Displacements and Zero Slopes“. Solid State Phenomena 147-149 (Januar 2009): 861–68. http://dx.doi.org/10.4028/www.scientific.net/ssp.147-149.861.
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Piezoelectric transducers have been used extensively as the distributed actuators and sensors in active control of structural vibrations. Piezoelectric actuator/sensors are distributively bonded on or embedded in the host structure and have the inherent advantage of integrating over their surface area, which leads to potentially more robust implementations as compared to implementations that use shaker/accelerometers. For this reason piezoelectric actuator/sensors have attracted more and more attention in recent years. In this paper, a theoretical analysis is presented of the active control of a vibrating beam using collocated triangular and rectangular piezoelectric actuator/sensor pairs. The aim of this study is to generate points of zero displacements and zero slopes at any designated position. So the control systems impose a virtual clamped boundary condition at the control position on the beam, in which both displacement and slope are driven to zero. Two independent single-input single-output (SISO) control systems similar to direct velocity feedback (DVFB) are implemented, i.e. for the rectangular pair the voltage signal measured by a triangular piezoelectric sensor is electronically multiplied by a fixed gain and fed directly back to a collocated piezoelectric actuator. The triangular and rectangular piezoelectric actuator/ sensor pairs positioned at one end of the beam are used to measure and control the displacement and slope of the structure respectively. The active control systems are unconditionally stable for any type of primary disturbance acting on the structure due to the collocated actuator/sensors. It should be noted that the presented control strategy is different to DVFB. In DVFB, when the control gain is increased, the vibration energy of the beam is initially reduced at resonance frequencies because of the active damping effect. However this effect does not continue. When large control gains are implemented, the overall kinetic energy of the beam is increased to the same or even higher values than those of the beam without control systems because the vibration of the beam is rearranged into a new set of lightly damped resonance frequencies. Imposing a virtual clamped boundary condition at the control position is clearly more complicated than DVFB, because in addition to the zero displacement constraints, the zero slope constraints must also be satisfied. The proposed control system allows for certain points of the structure to remain stationary without using any rigid supports. Furthermore, such control systems have the potential to create a region of nearly zero vibration for any ‘excitation’ frequency. This means that no progressive waves or reflected waves exist in the designated region, thus significantly reducing the vibration level in that region of the beam. The control systems impose a virtual clamped boundary condition at the control position on the beam in which the displacement and slope are driven to zero. As a result, the vibration of the actively controlled beam can be described in terms of two beams clamped at the control position. A numerical analysis is then performed to verify the proposed control system. It is found that the new resonance frequencies and mode shapes seen in the simulations are consistent with the natural frequencies and natural modes of the controlled beam derived analytically. The capability of the proposed method for generating a zero-vibration region is also numerically demonstrated.
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Wright, Andrew, und Amanda Nolen. „An observational protocol to measure learning in a problem-based learning vibrations course“. Journal of the Acoustical Society of America 151, Nr. 4 (April 2022): A82. http://dx.doi.org/10.1121/10.0010727.
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We have incorporated problem-based learning into several courses in an undergraduate engineering curriculum, including dynamics and vibrations. Students' prior knowledge (both formal and informal) were assessed through concept inventories to determine what prior knowledge supported or impeded the acquisition of new content in these courses. A point-and-click classroom observation tool was developed and refined over the span of two consecutive academic semesters to capture the students' interactions as they engaged in authentic learning activities in engineering. We identified patterns of discourse and interactions among the students and instructor, and, in vibrations, we identified a gap in the curriculum from the pre-requisite course, differential equations. The concept inventories and revised observational protocol that we have developed will enable instructors to assess the quality of the prior knowledge that students bring into a course and to analyze the manner in which students and instructor engage around the course content. We are developing bridge curriculum to improve transference of the theoretical knowledge in differential equations and the applied skills in vibration. This project spans across the beginning of the COVID-19 pandemic and includes observations on the interventions (successful and unsuccessful) where we attempted to continue student learning through a disrupted environment.
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Marin-Puyalto, Jorge, Alba Gomez-Cabello, Alejandro Gonzalez-Aguero, Angel Matute-Llorente, Alejandro Gomez-Bruton, Jaak Jürimäe, Jose Antonio Casajus und German Vicente-Rodriguez. „Effects of whole-body vibration training on bone density and turnover markers in adolescent swimmers“. Journal of Pediatric Endocrinology and Metabolism 33, Nr. 5 (26.05.2020): 623–30. http://dx.doi.org/10.1515/jpem-2019-0400.
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AbstractBackgroundWhole-body vibration training has recently been proposed as a complementary training modality to improve the bone health of adolescent swimmers. However, there is no longitudinal study regarding the effects of this training combination on bone metabolism. Therefore, the main goal was to analyze the effects of swimming and vibration training on bone turnover markers during adolescence.MethodsThe present study included 68 adolescent swimmers and 41 normoactive controls (CON). Swimmers were randomly selected to either continue with their regular swimming training (SWI) or participate in an additional vibration protocol (VIB). Anthropometric measurements and serum level determinations of osteocalcin (OC), procollagen type 1 N-terminal propeptide (P1NP) and C-terminal telopeptide crosslaps (CTX) were performed before and after the 6-month intervention.ResultsStatistically significant group by time interactions were found for both bone formation markers. VIB showed a decrease over time in OC (baseline: 101.4 μg/mL, follow-up: 82.8 μg/mL, p < 0.05) and P1NP (baseline: 528.4 μg/mL, follow-up: 389.0 μg/mL, p < 0.05) and SWI had analogous reductions in P1NP (baseline: 685.8 μg/mL, follow-up: 542.0 μg/mL, p < 0.05), whereas CON experienced an increase in OC levels (baseline: 94.4 μg/mL, follow-up: 103.4 μg/mL, p < 0.05). After stratifying the sample according to the pubertal status, similar interactions were observed.ConclusionsThe combination of swimming training and this particular vibration protocol led to a decrease in bone formation markers, especially during early puberty. Whole-body vibration might not induce an osteogenic stimulus in adolescent swimmers.
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GOVARDHAN, R., und C. H. K. WILLIAMSON. „Modes of vortex formation and frequency response of a freely vibrating cylinder“. Journal of Fluid Mechanics 420 (10.10.2000): 85–130. http://dx.doi.org/10.1017/s0022112000001233.
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In this paper, we study the transverse vortex-induced vibrations of an elastically mounted rigid cylinder in a fluid flow. We use simultaneous force, displacement and vorticity measurements (using DPIV) for the first time in free vibrations. There exist two distinct types of response in such systems, depending on whether one has a high or low combined mass–damping parameter (m*ζ). In the classical high-(m*ζ) case, an ‘initial’ and ‘lower’ amplitude branch are separated by a discontinuous mode transition, whereas in the case of low (m*ζ), a further higher-amplitude ‘upper’ branch of response appears, and there exist two mode transitions.To understand the existence of more than one mode transition for low (m*ζ), we employ two distinct formulations of the equation of motion, one of which uses the ‘total force’, while the other uses the ‘vortex force’, which is related only to the dynamics of vorticity. The first mode transition involves a jump in ‘vortex phase’ (between vortex force and displacement), ϕvortex, at which point the frequency of oscillation (f) passes through the natural frequency of the system in the fluid, f ∼ fNwater. This transition is associated with a jump between 2S [harr ] 2P vortex wake modes, and a corresponding switch in vortex shedding timing. Across the second mode transition, there is a jump in ‘total phase’, phis;total , at which point f ∼ fNvacuum. In this case, there is no jump in ϕvortex, since both branches are associated with the 2P mode, and there is therefore no switch in timing of shedding, contrary to previous assumptions. Interestingly, for the high-(m*ζ) case, the vibration frequency jumps across both fNwater and fNvacuum, corresponding to the simultaneous jumps in ϕvortex and ϕtotal. This causes a switch in the timing of shedding, coincident with the ‘total phase’ jump, in agreement with previous assumptions.For large mass ratios, m* = O(100), the vibration frequency for synchronization lies close to the natural frequency (f* = f/fN ≈ 1.0), but as mass is reduced to m* = O(1), f* can reach remarkably large values. We deduce an expression for the frequency of the lower-branch vibration, as follows:formula herewhich agrees very well with a wide set of experimental data. This frequency equation uncovers the existence of a critical mass ratio, where the frequency f* becomes large: m*crit = 0.54. When m* < m*crit, the lower branch can never be reached and it ceases to exist. The upper-branch large-amplitude vibrations persist for all velocities, no matter how high, and the frequency increases indefinitely with flow velocity. Experiments at m* < m*crit show that the upper-branch vibrations continue to the limits (in flow speed) of our facility.
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Chorney, Stephen R., Jennifer A. Villwock und Amar C. Suryadevara. „Vibration Versus Ice to Reduce Cosmetic Botulinum Toxin Injection Pain—A Randomized Controlled Trial“. Ear, Nose & Throat Journal 98, Nr. 6 (09.05.2019): 351–55. http://dx.doi.org/10.1177/0145561319839839.
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Botulinum toxin is the most commonly performed facial cosmetic procedure and pain at the injection site is a frequent patient concern. While various topical interventions have been described for analgesia, there have not been any studies comparing different techniques. We compared the use of a vibratory stimulus, ice pack application, and no intervention on injection site pain for cosmetic botulinum toxin injection. A prospective-, randomized-, individual-controlled study was conducted using a visual analog scale to assess pain. Patients received bilateral glabellar injections, with randomization into unilateral vibration, unilateral ice application, or vibration and ice on either side. We analyzed 88 injections on 22 patients. Mean visual analog scores were 26.5 (standard deviation [SD]: 23.1) among injections with vibration, 24.4 (SD: 22.9) with ice, and 29.4 (SD: 27.1) without analgesia. There was no significant difference in pain scale scores with the use of vibration, ice, or no topical anesthesia ( P = .737). Further, pain scale scores did not differ significantly between medial and lateral injections nor did patients have a reduction in pain on either side of the forehead regardless of which method was used. While there may be a role for topical interventions to improve injection site analgesia, we maintain that consistently proper technique plays a greater role in improving patient tolerance. Future studies will continue to investigate the role of topical anesthesia in cosmetic facial injections and address patient-specific factors contributing to discomfort.
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Ding, Huaping, Qinghong Shen und Sidan Du. „Autonomous main-cable vibration monitoring using wireless smart sensors for large-scale three-pylon suspension bridges: A case study“. Journal of Low Frequency Noise, Vibration and Active Control 39, Nr. 3 (10.12.2018): 604–15. http://dx.doi.org/10.1177/1461348418813760.
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Suspension bridges are supported by main cables that continue beyond the pillars to deck-level supports and must be anchored at each end of the bridge. The dynamic characteristics of the main cables are key indicators used to assess the structural health status of a bridge. In situ real-time health monitoring is an effective way to assess the dynamic characteristics. This paper presents a case study using vibration-based wireless smart sensors deployed on the main cables of a large-scale three-pylon suspension bridge to obtain its dynamic features. The methods of anti-aliasing filtering, statistical analysis and main cable tension force estimation were proposed and embedded into wireless smart sensors to provide autonomous data processing. According to the analysis of the vibration data from the main cables, the results demonstrate that the main cables have been in a stable state over time, and wireless smart sensors are promising for autonomous main-cable monitoring of large-scale three-pylon suspension bridges.
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Zawieska, Wiktor, und Dariusz Pleban. „Preventing Noise and Vibration During the 60 Years of Activity of the Central Institute for Labour Protection - National Research Institute“. Archives of Acoustics 36, Nr. 1 (01.02.2011): 161–71. http://dx.doi.org/10.2478/v10168-011-0013-0.
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Abstract In 2010, the Central Institute for Labour Protection - National Research Institute celebrated the 60th anniversary of its activity. Primary objectives of the Institute have been and continue to be the protection of employees against any hazards at work stations. Among the numerous hazards, vibroacoustic ones are becoming prevailing. Therefore, one can now dare to say that the 60 years of activity of the Central Institute for Labour Protection have also meant 60 years of preventing noise and vibration in the working environment. For those 60 years of activity, Central Institute for Labour Protection has been associated with outstanding acousticians and vibration specialists. The first chairperson of the Scientific Council of the Central Institute for Labour Protection was Professor Ignacy Malecki, one of the most outstanding Polish scientists. Chairpersons of the Council have also included Professor Adam Lipowczan and Professor Zbigniew Engel and the members of the Council have included Professor Stefan Ziemba and Professor Jerzy Sadowski.
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Dai, Yang, und Chao Ye. „Influence of Wheel Polygons on Dynamic Performance of Trains“. Academic Journal of Science and Technology 5, Nr. 2 (19.03.2023): 27–31. http://dx.doi.org/10.54097/ajst.v5i2.5928.
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With the continuous development of high-speed railroad technology, the operating speed and mileage of moving trains continue to increase, and the phenomenon of wheel-rail contact fatigue and wear is gradually highlighted, and the problem of wheel polygon wear is also prevalent in the operating site. Wheel polygon wear will deteriorate the wheel-rail contact relationship, so that the wheel-rail force surge, the safety and stability of the train caused serious impact. Therefore, wheel polygons become a key problem to be solved, but the formation and development mechanism of wheel polygons has not been fully clarified so far. This paper establishes a dynamic model of the moving train considering the elastic roadbed, and studies the dynamic performance of the moving train with the changing law of the moving train, respectively, in terms of wheel-rail vertical force, car body vibration acceleration, and wheelset vibration acceleration, to explore the influence of wheel polygons on the performance of the moving train. The results show that with the increase of wheel polygon order and wear depth, the safety of the moving vehicle gradually decreases and the wheel-rail vertical force gradually increases, and the wheelset vibration acceleration is more sensitive to the increase of order from 1 to 13.
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Marcinko, Peter, Mikulas Hajduk und Martin Kočan. „MEASURING CHAIN FOR CHECKING THE VIBRATION OF MECHANICAL PARTS“. TECHNICAL SCIENCES AND TECHNOLOGIES, Nr. 4(18) (2019): 121–26. http://dx.doi.org/10.25140/2411-5363-2019-4(18)-121-126.
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Urgency of the research. Interest in this topic is aroused, because mechanical vibration may damage the machinery or parts of machine. Therefore, it is appropriate to design systems that detect problems. Also these systems can help in the timely replacement of the worn part. Target setting. The main goal is to design a system that can detect in a timely manner a problem that could destroy the device. It is therefore necessary to design systems that can record this. Actual scientific researches and issues analysis. In recent years, there has been an increase in demand for equipment that can detect a timely problem. Many such devices already exist and are still being upgraded. This industry is called vibrodiagnostics. Uninvestigated parts of general matters defining. This paper is focused on the analysis of mechanical systems and the creation of a measuring chain. The research objective. The aim of this research is to analyse the mechanical systems and the assembly of the measuring chain. The functionality of the device can be verified on this measuring chain. Whether or not it is suitable for operation. In the future these systems will be upgraded with software that better records the vibrations. The statement of basic materials. The analysis consists of basic information about mechanical systems and sensors. The definition of this problem is described below. Based on this knowledge of mechanical systems, a measurement chain was designed. Conclusions. Our vision is to implement knowledge of mechanical systems not only on a simple fan stator. Problems of vibrodiagnostics are still progressing and increasingly in technical practice. We would continue to do more testing on more complex devices.
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Ray, Chase A., und Steven R. Anton. „Multilayer piezoelectret foam stack for vibration energy harvesting“. Journal of Intelligent Material Systems and Structures 28, Nr. 3 (28.07.2016): 408–20. http://dx.doi.org/10.1177/1045389x16657420.
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Electronic devices are high-demand commodities in today’s world, and such devices will continue increasing in popularity. Currently, batteries are implemented to provide power to these devices; however, the need for battery replacement, their cost, and the waste associated with battery disposal present a need for advances in self-powered technology. Energy harvesting technology has great potential to alleviate the drawbacks of batteries. In this work, a novel piezoelectret foam material is investigated for low-level vibration energy harvesting. Specifically, piezoelectret foam assembled in a multilayer stack configuration is explored. Modeling and experimentation of the stack when excited in compression at low frequencies are performed to investigate piezoelectret foam for multilayer energy harvesting. An equivalent circuit model derived from the literature is used to model the piezoelectret stack. Two 20-layer prototype devices and one 40-layer prototype device are fabricated and experimentally tested via harmonic base excitation. Electromechanical frequency response functions between input acceleration and output voltage are measured experimentally. Modeling results are compared to experimental measurements to assess the fidelity of the model near resonance. Finally, energy harvesting experimentation in which the device is subject to harmonic base excitation at the fundamental natural frequency is conducted to determine the ability of the stack to successfully charge a capacitor. For a 20-layer stack excited at 0.5 g, a 100-µF capacitor is charged to 1.45 V in 15 min, and produces a peak power of 0.45 µW. A 40-layer stack is found to charge a 100-µF capacitor to 1.7 V in 15 min when excited at 0.5 g, and produce a peak power of 0.89 µW.
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V. Shaha, Gauravkumar, und Vivek S. Chandurkar. „MANAGEMENT OF GRUDHRASI WITH UNIQUE COMBINATION OF AYURVEDIC HERBAL KWATHA & AGNIKARMA“. International Journal of Research -GRANTHAALAYAH 5, Nr. 9 (30.09.2017): 224–29. http://dx.doi.org/10.29121/granthaalayah.v5.i9.2017.2235.
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Today people are predisposed to various diseases based on their way of living and occupational habits called life style diseases. Orthopedic disorders are one of the mostly exposed to such life style habits. physical inactivity, wrong body posture, occupational posture, long sitting jobs, stresses activity, exposure to continue vibration, post-operative causes, gym, athletes muscular spasm are main contributing factors to orthopedic disorders.
One of the most common orthopedic health problems today is lower back pain which is accompanied most of the time by Sciatica. The present case study is successful Ayurvedic management of a case of “GRUDRASI”.
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Strömbergsson, D., P. Marklund, K. Berglund und P.-E. Larsson. „Property requirements of vibration measurements in wind turbine drivetrain bearing condition monitoring“. Insight - Non-Destructive Testing and Condition Monitoring 63, Nr. 11 (01.11.2021): 667–74. http://dx.doi.org/10.1784/insi.2021.63.11.667.
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Wind turbine drivetrain bearing failures continue to lead to high costs resulting from turbine downtime and maintenance. As the standardised tool to best avoid downtime is online vibration condition monitoring, a lot of research into improving the signal analysis tools of the vibration measurements is currently being performed. However, failures in the main bearing and planetary gears are still going undetected in large numbers. The available field data is limited when it comes to the properties of the stored measurements. Generally, the measurement time and the covered frequency range of the stored measurements are limited compared to the data used in real-time monitoring. Therefore, it is not possible to either reproduce the monitoring or to evaluate new tools developed through research for signal analysis and diagnosis using the readily available field data. This study utilises 12 bearing failures from wind turbine condition monitoring systems to evaluate and make recommendations concerning the optimal properties in terms of measurement time and frequency range the stored measurements should have. The results show that the regularly stored vibration measurements that are available today are, throughout most of the drivetrain, not optimal for research-driven postfailure investigations. Therefore, the storage of longer measurements covering a wider frequency range needs to begin, while researchers need to demand this kind of data.
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Mensa-Wilmot, Graham. „Technology Focus: Bits and Bottomhole Assemblies (December 2020)“. Journal of Petroleum Technology 72, Nr. 12 (01.12.2020): 52. http://dx.doi.org/10.2118/1220-0052-jpt.
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Achieving and sustaining performance drilling’s intended benefits - improved drilling efficiency with minimal down-hole tool failures and the associated reductions in project cycle time and operational costs - requires new protocols in drilling-system analysis. Drilling-system components [bits, reamers, bottomhole assemblies (BHAs), drive systems, drilling parameters, and hydraulics] must be analyzed independently for their relevance on the basis of application types and project challenges. Additionally, the drilling system must undergo holistic evaluations to establish functional compatibility and drilling-parameter responses and effects, considering project objectives and key performance indicators. This comprehensive physics-based approach ensures durability and rate-of-penetration (ROP) improvements without compromising stability and downhole tool reliability. The success of this process is strongly dependent on vibration control. Considering the different vibration modes - axial, torsional, lateral, stick/slip, and whirl - and their many dissimilar initiating and amplification factors, their sources always must be identified. Researchers have challenged the usual classification of erratic torque and revolution-rate behavior as stick/slip. BHA design and drilling-parameter ranges, considering blade spacing, can produce unfavorable tubular deformations, contact points, and side loads. This condition creates torque and revolution-rate fluctuations that have been linked to lateral vibrations. Awareness of these vibration modes, particularly their sources and intensifying conditions, ensures development of effective remediation solutions. Improved borehole quality, with regard to tortuosity and rugosity, must always be considered as a critical requirement in performance drilling. This condition reduces borehole drag, enhances drilling-parameter transfer, and improves ROP and overall run lengths. Most importantly, it reduces vibrations, leading to improvements in downhole tool life and directional drilling performance. In addition to formation drillability effects, drilling-systems components and operational practices have strong effects on borehole quality. Consequently, this must be part of the drilling-system analysis. The industry’s advancements at developing physics-based solutions for drilling challenges have matured. Continuing to ask questions that help us understand how and why we fail or succeed puts more wind beneath our wings to accelerate learning and reduce cycle times. Recommended additional reading at OnePetro: www.onepetro.org. SPE 200740 Digital Twins for Well Planning and Bit-Dull-Grade Prediction by Mehrdad Gharib Shirangi, Baker Hughes, et al. SPE 201616 Validating Bottomhole-Assembly Analysis Models With Real-Time Measurements for Improved Drilling Performance by Mark Smith, Premier Directional Drilling, et al. IADC/SPE 199658 Simulation and Measurement of High-Frequency Torsional Oscillation (HFTO)/High-Frequency Axial Oscillation and Downhole HFTO Mitigation: Knowledge Gains Continue by Using Embedded High-Frequency Drilling Dynamics Sensors by Junichi Sugiura, Sanvean Technologies, et al.