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1
Ryazancev, V., M. Gerasimov, N. Lyubimyy, A. Pol'shin e A. Tihonov. "PHYSICAL MODEL OF A TWO-STAGE VIBRATION UNIT FOR GENERATING ASYMMETRIC OSCILLATIONS". Bulletin of Belgorod State Technological University named after. V. G. Shukhov 7, n.º 10 (10 de junho de 2022): 107–14. http://dx.doi.org/10.34031/2071-7318-2022-7-10-107-114.
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Vibrating devices occupy a large cluster in the construction and road construction industry. The improvement of all vibration machines begins, first of all, with a vibration device, as the main working body of the machine. Basically, vibrators acted as a vibrating device for all road construction equipment. Initially, vibrators with circular vibrations were used, which are not so effective and not always sufficient for performing special work on driving piles into the ground and also extracting them from the soil. Vibratory systems with asymmetric vibrations are increasingly being used in the construction industry. For example, when driving piles, pile drivers are used. Their principle of operation is similar in its action to the operation of a vibration plant with asymmetric vibrations. However, a vibration plant with asymmetric oscillations, when the direction of the driving force is turned in the opposite direction, not down, but up, also makes it possible to extract worn-out piles and sheet piles from the soil. Based on the above, we propose a description, a method for calculating the optimal values of the asymmetry coefficient, driving force and set out the principle of operation of a physical model of a vibration plant with two stages of generating asymmetric vibrations, consisting of standard vibration equipment: the first stage: a table of the brand EV-341 and the second stage : vibrator of directional vibrations brand IV-99B, manufactured by OOO Yaroslavl Plant Krasny Mayak.
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Ryazancev, V., M. Gerasimov e Y. Brazhnik. "REDUCTION OF DIFFERENTLY DIRECTIONAL VIBRATIONS TO ASYMMETRICAL BY CHANGING THE RATIO OF VALUES COMPOSING THE DRIVING FORCE". Bulletin of Belgorod State Technological University named after. V. G. Shukhov 6, n.º 5 (18 de maio de 2021): 87–94. http://dx.doi.org/10.34031/2071-7318-2021-6-5-87-94.
Texto completo da fonteResumo:
Vibrating machines play a primary role in the implementation of programs in the construction and road construction kit. The improvement of vibration machines allows to significantly increase the speed of construction and road construction work. The main working unit of a vibrating machine is a vibrating device or vibrator. Currently, in the industry, vibration devices are used with circular or directional, along a certain straight line of vibrations. Further improvement of vibrating machines is carried out in the direction of creating vibration devices with asymmetric vibrations. At present, there are practically no vibrating machines with asymmetric vibrations. These machines allow to distinguish between the "working" process phase and the "idle" phase within each oscillation period. Moreover, the value of the driving force in the phase of performing useful work is several times higher than the value of the driving force in the direction of idling. Therefore, much less work is spent on idling. This allows to get rid of massive elements - overloads that extinguish the magnitude of the driving force in the direction of idling. Therefore, the urgency is to develop a method for converting existing machines with directional vibrations into asymmetric ones, with a given coefficient of asymmetry of the driving force. This makes it possible to reduce the specific indicators of the metal consumption of vibrating machines and the energy consumption of the work performed.
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Yu, Yingjie, Ying Cao, Qinghui Lai, Qinghui Zhao, Zhexing Sun, Shengwu Zhou e Dake Song. "Design and Operation Parameters of Vibrating Harvester for Coffea arabica L." Agriculture 13, n.º 3 (17 de março de 2023): 700. http://dx.doi.org/10.3390/agriculture13030700.
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This study designed a handheld vibrating coffee harvester to improve the mechanized harvesting of Coffea arabica L. The proposed device was used to vibrate branches of Coffea arabica L. trees, and the shedding of coffee fruit and the operation parameters of vibrational harvesting were analyzed. Images captured using high-speed photography were used to derive a force equation that represents the forced vibration of the coffee fruit-stalk joint. In addition, the vibrations of coffee berries and branches were theoretically analyzed, and the results were used to establish a dynamic vibration model of coffee trees. The shedding of coffee berries was primarily affected by the vibration frequency, vibration amplitude, and excitation position, which were simulated using a rigid–flexible branch-machine coupling model on RecurDyn software. Furthermore, field experiments were conducted to determine the optimal working parameters for coffee harvesting using vibrations. The results indicated optimal picking performance when the vibration frequency, vibration amplitude, and excitation position were 62 Hz, 9 mm, and 0.4 L, respectively. The harvesting rates of ripe and unripe coffee were 92.22% and 8.33%, respectively, and the damage rate was 5.23%. Thus, the proposed harvester can satisfactorily achieve the optimal harvesting of Coffea arabica L.
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Mohanty, Lipi, Yaowen Yang e Swee Tjin. "Passively Conducted Vibration Sensing with Fiber Bragg Gratings". Applied Sciences 8, n.º 9 (10 de setembro de 2018): 1599. http://dx.doi.org/10.3390/app8091599.
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Measuring vibrations is a common method of monitoring the integrity of structures and heavy machinery, that are subject to dynamic loads. Strong vibrations for prolonged periods of time can be caused by various sources, such as trains, motors and heavy machinery. These strong vibrations should be identified and managed to ensure operational safety. This study proposes a flexible metal beam sensor with a fiber Bragg grating (FBG) mounted on the surface to measure the vibrational frequency. We present a sensor for measuring the vibrational frequencies on-site by placing the beam so that it makes physical contact with the vibrating body. The sensor has been tested in the range of 50–200 Hz. The sensing beam can detect the vibrations that are induced in other metallic bodies where there are metallic structures of low stiffness to conduct the vibration. The results show that the sensing beam is capable of detecting the frequency of forced vibrations from its periphery when placed in different orientations.
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Bratu, Polidor. "Multibody System with Elastic Connections for Dynamic Modeling of Compactor Vibratory Rollers". Symmetry 12, n.º 10 (29 de setembro de 2020): 1617. http://dx.doi.org/10.3390/sym12101617.
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The dynamic model of the system of bodies with elastic connections substantiates the conceptual basis for evaluating the technological vibrations of the compactor roller as well as of the parameters of the vibrations transmitted from the vibration source to the remainder of the equipment components. In essence, the multi-body model with linear elastic connections consists of a body in vertical translational motion for vibrating roller with mass m1, a body with composed motion of vertical translation and rotation around the transverse axis passing through its weight center for the chassis of the car with mass m and the moment of mass inertia J and a body of mass m’ representing the traction tire-wheel system located on the opposite side of the vibrating roller. The study analyzes the stationary motion of the system of bodies that are in vibrational regime as a result of the harmonic excitation of the m mass body, with the force F(t)= m0rω2sinωt, generated by the inertial vibrator located inside the vibrating roller. The vibrator is characterized by the total unbalanced m0 mass in rotational motion at distance r from the axis of rotation and the angular velocity or circular frequency ω.
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Ni, Cheng-Hua, Yueh-Hsun Lu, Li-Wei Chou, Shu-Fen Kuo, Chia-Huei Lin, Shang-Lin Chiang, Liang-Hsuan Lu, Xin-Miao Wang, Jia-Lan Chang e Chueh-Ho Lin. "Analysis of Vibration Frequency and Direction for Facilitating Upper-Limb Muscle Activity". Biology 12, n.º 1 (27 de dezembro de 2022): 48. http://dx.doi.org/10.3390/biology12010048.
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We aimed to determine the effect of vibration frequency and direction on upper-limb muscle activation using a handheld vibrator. We recruited 19 healthy participants who were instructed to hold a handheld vibrator in their dominant hand and maintain the elbow at 90° flexion, while vertical and horizontal vibrations were applied with frequencies of 15, 30, 45, and 60 Hz for 60 s each. Surface electromyography (EMG) measured the activities of the flexor digitorum superficialis (FDS), flexor carpi radialis (FCR), extensor carpi ulnaris (ECU), extensor carpi radialis (ECR), biceps, triceps, and deltoid anterior muscles. EMG changes were evaluated as the difference in muscle activity between vibration and no-vibration (0 Hz) conditions. Muscle activity was induced under vibration conditions in both vertical and horizontal (p < 0.05) directions. At 45 Hz, FDS and FCR activities increased during horizontal vibrations, compared with those during vertical vibrations. ECU activity significantly increased under 15-Hz vertical vibrations compared with that during horizontal vibrations. Vibrations from the handheld vibrator significantly induced upper-limb muscle activity. The maximum muscle activations for FDS, ECR, ECU, biceps, and triceps were induced by 45-Hz horizontal vibration. The 60-Hz vertical and 30-Hz horizontal vibrations facilitated maximum muscle activations for the FCR and deltoid anterior, respectively.
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Lian, Jijian, Yan Zheng, Chao Liang e Bin Ma. "Analysis for the Vibration Mechanism of the Spillway Guide Wall Considering the Associated-Forced Coupled Vibration". Applied Sciences 9, n.º 12 (25 de junho de 2019): 2572. http://dx.doi.org/10.3390/app9122572.
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During the flood discharge in large-scale hydraulic engineering projects, intense flow-induced vibrations may occur in hydraulic gates, gate piers, spillway guide walls, etc. Furthermore, the vibration mechanism is complicated. For the spillway guide wall, existing studies on the vibration mechanism usually focus on the vibrations caused by flow excitations, without considering the influence of dam vibration. According to prototype tests, the vibrations of the spillway guide wall and the dam show synchronization. Thus, this paper presents a new vibration mechanism of associated-forced coupled vibration (AFCV) for the spillway guide wall to investigate the dynamic responses and reveal coupled vibrational properties and vibrational correlations. Different from conventional flow-induced vibration theory, this paper considers the spillway guide wall as a lightweight accessory structure connected to a large-scale primary structure. A corresponding simplified theoretical model for the AFCV system is established, with theoretical derivations given. Then, several vibrational signals measured in different structures in prototype tests are handled by the cross-wavelet transform (XWS) to reveal the vibrational correlation between the spillway guide wall and the dam. Afterwards, mutual analyses of numeral simulation, theoretical derivation, and prototype data are employed to clarify the vibration mechanism of a spillway guide wall. The proposed mechanism can give more reasonable and accurate results regarding the dynamic response and amplitude coefficient of the guide wall. Moreover, by changing the parameters in the theoretical model through practical measures, the proposed vibration mechanism can provide benefits to vibration control and structural design.
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Fardelin, Gustav, Niklas Ricklund e Ing-Liss Bryngelsson. "Hand nerve function after mountain bike cycling". Journal of Science and Cycling 11, n.º 3 (31 de dezembro de 2022): 23–32. http://dx.doi.org/10.28985/1322.jsc.10.
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Hand-arm vibrations can cause permanent injuries and temporary changes affecting the sensory and circulatory systems in the hands. Vibrational effects have been thoroughly studied within the occupational context concerning work with handheld vibrating tools. Less is known about vibrational exposure and risk of effects during cycling. In the present study, 10 cyclists were recruited for exposure measurements of hand-arm vibrations during mountain bike cycling on the trail, and the effects on the nerve function were examined with quantitative sensory testing (QST) before and after the ride.
The intervention group was compared to a control group that consisted of men exposed to hand-arm vibrations from a polishing machine. The results of the QST did not statistically significantly differ between the intervention and study groups. The intervention group showed a lesser decrease in vibration perception in digitorum II, digitorum V, and hand grip strength than the control group. It was concluded that no acute effects on nerve function in the dominant hand were measured after mountain bike cycling on the trail, despite high vibration doses through the handlebars.
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Niu, Jianye, Jiang Wu, Qiming Liu, Li Chen e Shijie Guo. "A Dumbbell Shaped Piezoelectric Motor Driven by the First-Order Torsional and the First-Order Flexural Vibrations". Actuators 9, n.º 4 (30 de novembro de 2020): 124. http://dx.doi.org/10.3390/act9040124.
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A piezoelectric motor driven by the first-order torsional and first-order flexural (T/F) vibrations is designed, fabricated, and tested in this study. The actuating force is generated by the torsional vibration of the dumbbell-shaped vibrator, while the elliptical motion shape is adjusted with the flexural vibration. The rotor, pressed onto the vibrator’s lateral surface, is frictionally driven with the vibrator. Here, the torsional vibration, the shear modes of piezoelectric ceramics, and the driving method may contribute to high torque and high output power. To test the feasibility of our proposal, first, a prototype of the T/F vibrator is built and its vibration properties are explored. As predicted, the torsional and flexural vibrations are excited on the vibrator. Then, the load characteristics of the piezoelectric motor are investigated. The maximal torque, the no-load rotation speed, and maximal output power are 4.3 Nm, 125 r/min, and 16.9 W, respectively. The results imply that using the first-order torsional and the first-order flexural vibrations is a feasible method to achieve high torque and high output power of piezoelectric motors.
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Yin, Zhen, Hua Li, Bang Fu Wang e Ke Feng Song. "Study on the Design of Longitudinal-Torsional Composite Ultrasonic Elliptical Vibrator Based on FEM". Advanced Materials Research 308-310 (agosto de 2011): 341–45. http://dx.doi.org/10.4028/www.scientific.net/amr.308-310.341.
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Based on FEM, a new type of ultrasonic elliptic vibrator design method was proposed, the ultrasonic elliptic vibration was achieved by the structural curve of the longitudinal and torsional vibrations. The impedance and vibration characteristics of the new longitudinal-torsional composite ultrasonic elliptic vibrator prototype were tested. It provides an important basis for impedance matching and longitudinal-torsional composite ultrasonic elliptical vibration application.
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Rasangika, Ambagaha Hewage Dona Kalpani, Mohammad Shakir Nasif e Rafat Al-Waked. "Comparison of Forced Convective Heat-Transfer Enhancement of Conventional and Thin Plate-Fin Heat Sinks under Sinusoidal Vibration". Applied Sciences 13, n.º 21 (31 de outubro de 2023): 11909. http://dx.doi.org/10.3390/app132111909.
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Applying sinusoidal vibration to heat sinks has proven to be a promising technique for improving heat transfer by disrupting the thermal boundary layer. However, applying sinusoidal vibration to the base of thin plate-fin heat sinks can cause a flapping motion within the fins, further enhancing heat transfer. Therefore, the current study numerically investigates and compares the effects of sinusoidal vibrations on the thermal performance of conventional and thin plate-fin heat sinks. The study concludes that increased vibrational amplitude and frequency (f ˃ 30 Hz) increases the vibration-assisted thermal performance. It was found that the thin plate-fin heat sink provides higher thermal performance compared to the conventional heat sink at every level of vibrational characteristics. The study found that the application of vibration enhances the Nusselt number up to a maximum of 20% and 15% in thin plate-fin and conventional heat sinks, respectively. Furthermore, the Reynolds number is reduced by 33.3% and 28% with thin plate-fin and conventional heat sinks compared with non-vibrating heat sinks, indicating a potential reduction of the size of the cooling system or fin size.
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Suzuki, Kiyoshi, Takuya Takada, Zhi Rong Zhou, Takuya Okamichi, Manabu Iwai e Shinichi Ninomiya. "Effects of Ultrasonic Vibrations Given to an Electrode on the EDM Performance in Processing PCD". Advanced Materials Research 565 (setembro de 2012): 394–99. http://dx.doi.org/10.4028/www.scientific.net/amr.565.394.
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EDM machinability of PCD was investigated using a copper electrode giving ultrasonic vibrations. In this series of EDM experiments, three types of ultrasonic vibration modes were selected (axial vibration, flexural vibration and complex vibration). From the experimental results, it was found that EDM efficiency became 3 times higher than the ordinary EDM (no vibration given to the electrode) under the two specific vibration modes, namely, 1) the axial vibration (large) mode and 2) the complex vibration (axial vibration: large + flexural vibration: small) mode. Furthermore, it was shown that the effects resulted from not only the cavitation effect of the working fluid but also the vibrational action of the electrode itself.
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Mistry, Yash Ashwin, e Kushagra Goel. "Surface Mounted Active Vibration Cancellation Device Using Raspberry Pi". ECS Transactions 107, n.º 1 (24 de abril de 2022): 19289–97. http://dx.doi.org/10.1149/10701.19289ecst.
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Active vibration cancellation device detects vibrations on a host surface using a piezoelectric vibration sensor, amplifies them using a signal amplifier, and sends them to a Raspberry Pi board implemented with PID control, responsible for signal processing, which further actuates Piezoelectric actuators vibrating at a phase difference of 180° to the vibrating surface (destructive interference) and reduces the vibrations over the surface. The device presented in this paper suggests an application that tries to make it accessible to a large group of people.
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Picu, Mihaela. "A Study of Vertical Vibration Transmissibility by the Human Body". Applied Mechanics and Materials 325-326 (junho de 2013): 152–57. http://dx.doi.org/10.4028/www.scientific.net/amm.325-326.152.
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The transmission of longitudinal vibration (generated by the vibrating platform Brüel & Kjær 4827) in the whole body of ten subjects was investigated. Altogether 200 individual tests were made. Vibration was measured with 356A16 PCB Piezotronics triaxial accelerometers fixed to the toes, ankles, lumbar, cervical, fingers, elbow and shoulder. Vibrations were analyzed with a multiple acquisition vibrations system NetdB. Data were processed using dBFA Suite. Vibration time was 1min and frequency range was between 10-40Hz, because the low frequencies are the resonance frequencies for the human body. Body vibration transmissibility was determined by the ratio of root mean square acceleration signal from accelerometer by the root mean square of acceleration signal from the vibrating platform. It was found that the accelerations at the lumbar level are more attenuated than the accelerations at the ankle level.
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Spirin, Anatoly, Dmytro Borysiuk, Oleksandr Tsurkan e Igor Tverdokhlib. "NFLUENCE OF VIBRATION ON THE ERGONOMIC INDICATORS OF THE PRODUCTION PROCESS". Vibrations in engineering and technology, n.º 1 (108) (1 de maio de 2023): 45–56. http://dx.doi.org/10.37128/2306-8744-2023-1-5.
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Features of the impact of industrial vibration, the nature, depth and direction of physiological changes of various body systems depend on the level, frequency composition of vibrations and physiological properties of the human body. Vibration is one of the main causes of occupational diseases. The study of the sources of production vibration, the ways of its propagation, the specifics of the impact on the human body and protection against harmful effects is currently an urgent issue. The analysis of the latest sources shows that the majority of works consider individual elements of a complex system of ergonomic provision of safe working conditions in case of vibrational impact on workers. Therefore, there is a need to deepen the study of this issue, comprehensive consideration of the causes of vibration, its characteristics and specific effects on the worker's body, planning measures and means to minimize the consequences of its negative effects. There are two types of vibration: local, which primarily affects those organs of the human body that are in direct contact with vibrating elements, and general vibration, which causes the body to move in space and affects the entire body. The main parameters of vibration are amplitude and frequency of oscillations, speed and vibration acceleration. The effect of general vibration on the central nervous system leads to a disturbance in the balance between excitation and inhibition. Under the influence of vibration, workers become irritable, get tired quickly, feel drowsy (and sometimes, on the contrary, insomnia), work capacity decreases, the time it takes to complete production tasks increases, and the time of simple and complex reactions increases. The fight against the harmful effects of mechanical vibrations in most cases boils down to compliance with existing norms and rules. Also, a special role is played by means of protecting workers from the harmful effects of vibration. First of all, this is the improvement of the design of vehicles, machines, mechanisms and tools.
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Гапонюк, Т. О., Р. В. Кірчук e Л. Ю. Забродоцька. "USING HYDRAULIC PARAMETRIC VIBRATION EXCITER IN AGRICULTURAL ENGINEERING". СІЛЬСЬКОГОСПОДАРСЬКІ МАШИНИ, n.º 48 (31 de outubro de 2022): 7–14. http://dx.doi.org/10.36910/acm.vi48.778.
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Vibration technology is widely used in mechanical engineering, construction, road building and different sectors of the manufacturing. In agriculture, it is used for dosing feed, cleaning and sorting seeds, digging up root crops, planting potatoes, and transporting bulk materials. Vibrations make the mechanical system more stable in relation to external force disturbances and do not change the technological properties of materials during its movement along the working surfaces. Also, the material passing through the vibration zone is not damaged. A wide range of frequency and amplitude of vibrations provides the possibility of vibration regime varying, and the characteristics of the movement of agricultural plant material on the vibrating working bodies. The analysis of possibility of application of vibrating hydraulic drives as elements of transmission of movement to working bodies of agricultural machines is executed. A historical excursion was conducted and the first mentions of the use of hydraulic drives were pointed out. The estimation of technological processes in agricultural production where it is expedient and possible to use vibration and vibrating drives is made. At the present stage of development of agricultural engineering, using vibrating hydraulic drive is accorded to the basic trends of agriculture machinery development. The stand for conduction of studies of amplitude-frequency characteristics of the vibrating drive with regulated perturbations is offered. A mathematical model is presented, which generally describes the course of the vibration process and estimates the stiffness of the mechanical system. The hydraulic parametric vibration exciter is recommended to use for studying and determination the conditions for the occurrence of parametric vibrations in working body of agricultural machines. Also, using a hydraulic drive makes it possible to simplify the kinematics, reduce metal consumption, increase accuracy, reliability and level of automation of working bodies of agricultural machines.
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Li, Hua, Jiang Jiang Zhao, Zhen Yin e Kun Ren. "Design and Research of a New Ultrasonic Atomizing Vibrator". Applied Mechanics and Materials 328 (junho de 2013): 468–72. http://dx.doi.org/10.4028/www.scientific.net/amm.328.468.
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Based on the theory of ultrasonic vibration, a new type of ultrasonic atomizing vibrator (UAV) with a vibrating steel sheet was proposed. By using the finite element analysis software to simulation analysis and research for the new type of vibrator, the frequency and vibration mode of atomizing steel sheet was obtained and the prototype of vibrator was fabricated. The impedance and vibration displacement of the vibrator was tested and the experiment of the new type of vibrator was carried out, which verified the feasibility of the new type of vibrator design method.
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Dong, Jie, Yue Yang e Zhi-Hui Wu. "Propagation characteristics of vibrations induced by heavy-haul trains in a loess area of the North China Plains". Journal of Vibration and Control 25, n.º 4 (9 de outubro de 2018): 882–94. http://dx.doi.org/10.1177/1077546318802980.
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To study heavy train-related vibration, this paper examines the world's largest heavy-freight railway – the Daqin Railway – to study the impacts of the seasonally frozen soil layer on vibrational acceleration. With increasing axle weight, the peak and mean values of the acceleration increased. Vibration acceleration attenuated the most from the shoulder to the embankment footing (51%–71%), while the vibrations at 70 m were attenuated by more than 90%. Certain measures must be taken by those living within 70 m of the railway shoulder. In addition, the acceleration peak caused by trains running in parallel after meeting amplified the vibration by 10%–39%. Moreover, the overall vibrations attenuate with increasing distance, whereas the local vibrations fluctuate. During the freezing period, the acceleration is 13%–26% greater than that of the unfrozen period. The vibration acceleration spectrum is comparatively wider, and is dominated by high-frequency components. Finally, using a three-dimensional model verified by field measurements, the vibrational features were analyzed at different embankment and foundation depths.
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Ragaišis, L., R. Jonušas, K. Ragulskis e V. Jurėnas. "Research of Possibilities of Energy Transformation Using an Autovibrating System, Excited by Small Outer Excitement". Solid State Phenomena 113 (junho de 2006): 207–12. http://dx.doi.org/10.4028/www.scientific.net/ssp.113.207.
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There are lots of sources of disturbance in people’s surrounding environment - e.g. wind, sea, river flow, and intensive acoustic noise. These sources can cause auto vibrations of particular dynamic systems. Such phenomenon could be used for converting mechanical vibration energy to electrical energy. Solving this problem is topical because it could help to create autonomic sources of renewable energy. Dynamic model, described by a presumptive differential motion equation, of auto vibrating system, affected by airflow is made and inspected. Possible modes of vibrations and different states of nonlinear auto vibrating system are analyzed using methods of Newmark and Runge-Kutta. Auto vibration existence zones of the system are designated. Reliance on the existence of poly-solutions, stability or chaotic solutions of vibrating system is estimated. Consistencies of using electro dynamical principle of converting mechanical vibration energy to electric energy are inspected.
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Shiozaki, Tetsuya, Hisaya Tanaka, Akio Nozawa, Hideto Ide e Masafumi Uchida. "Qualitative Evaluation by ERP for vibration Discrimination". Journal of Robotics and Mechatronics 14, n.º 3 (20 de junho de 2002): 313–17. http://dx.doi.org/10.20965/jrm.2002.p0313.
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We have developed a method of quantitative evaluation for vibration discrimination by event-related potentials (ERP). We made a modulation matrix of high-pass component f1: (40-200 Hz) and low-pass component f2: (2-20 Hz), and gave modulated vibrations to a forefinger by a piezoelectric vibrator. We examined ERP differences, which are amplitudes, areas and intervals, between a reference vibration of (f1, f2) = (40, 2) Hz and controlled vibrations.
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Jurevicius, M., V. Vekteris, V. Turla, A. Kilikevicius e G. Viselga. "Investigation of the dynamic efficiency of complex passive low-frequency vibration isolation systems". Journal of Low Frequency Noise, Vibration and Active Control 38, n.º 2 (3 de janeiro de 2019): 608–14. http://dx.doi.org/10.1177/1461348418822230.
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In this study, the theoretical and experimental investigations of the dynamics of complex passive low-frequency vibration systems are described. It is shown that a complex system consisting of a vibrating platform, an optical table and a vibration isolation system of quasi-zero stiffness loaded by a certain mass may isolate low-frequency vibrations in a narrow frequency range only. In another case, the system does not isolate vibrations; it even operates as an amplifier. The frequencies that ensure the top efficiency of the vibration damping system of quasi-zero stiffness were established.
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Yu, Dongyang, Feihu Peng, Zhihao Zeng, Minghua Zhang, Wenwu Yang, Ying Zang, Jianfei He et al. "Vibrational Dynamics of Rice Precision Hole Seeders and Their Impact on Seed Dispensation Efficacy". Agriculture 14, n.º 2 (18 de fevereiro de 2024): 324. http://dx.doi.org/10.3390/agriculture14020324.
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This investigation considered the effects of both internal and external excitation vibrations on the efficacy of the seed dispenser in a rice precision hole seeder. Through comprehensive field tests, we analyzed vibrational characteristics during direct seeder operations and established a vibration seeding test bed for systematic examination of these effects. Time-domain analysis of the vibration data revealed a predominantly vertical vibration direction, with notably higher levels in sandy loam soil compared to clay loam. A correlation was observed between increased engine size and rotary ploughing speeds, as well as forward speed and elevated vibration amplitudes. Frequency domain analysis pinpointed the primary vibration frequency of the machinery within the 0–170 Hz range, remaining consistent across different operating conditions. Crucially, bench test results indicated that seeding accuracy and dispersion were significantly influenced by vibration frequencies, particularly within the 70–130 Hz range, where a decrease in accuracy and increase in dispersion were noted. A regression model suggested a complex, non-linear relationship between seeding performance and vibration frequency. These insights highlight the necessity for a robust mechanism to effectively address these vibrational impacts. This study paves the way for enhancing the operational efficiency of the rice precision hole seeder, aiming to achieve the design goals of minimized vibrations in the paddy power chassis.
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Sobolev, Vladimir I., e Tatiana N. Chernigovskaya. "Research into the dynamics of radio telescope foundationsusing laser vibration measuring equipment". Journal «Izvestiya vuzov. Investitsiyi. Stroyitelstvo. Nedvizhimost» 10, n.º 3 (2020): 420–27. http://dx.doi.org/10.21285/2227-2917-2020-3-420-427.
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This study presents a technology for determining the dynamic parameters of the foundation structures of radio telescopes by a non-contact method based on the use of laser vibration measuring equipment. The main results of a dynamic process analysis are described. The research was carried out in the form of microdynamic tests of foundation structures with the determination of natural oscillation periods based on lower vibrational forms. Measurements of natural vibrations of radio telescope foundations under applied shock were performed, followed by spectral mapping of vibrational processes. The tests were carried out using a tachometric laser vibrometer RSV-150 included in the register of vibration measuring equipment in Russia. Spectral mappings were obtained using Fourier transforms implemented in software packages of the hardware developers. The dynamic features of radio tele-scope foundations are formalized in the form of spectral maps of the initial records of vibrational proc-esses. The method of microdynamic tests using a vibration meter is presented, along with the principles of its operation and the sequence of numerical processing of records of dynamic processes imple-mented on a personal computer using frequency displays of natural vibrations of structures. The values of natural vibration frequencies obtained as a result of measurements confirmed the rigidity and integ-rity of foundation piles. Pronounced solitary peaks of natural vibration frequencies point to the form of natural vibrations of structures as single-mass systems with the absence of deformational forms of vi-brations in the foundation body.
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Beltran-Carbajal, Francisco, Hugo Francisco Abundis-Fong, Luis Gerardo Trujillo-Franco, Hugo Yañez-Badillo, Antonio Favela-Contreras e Eduardo Campos-Mercado. "Online Frequency Estimation on a Building-like Structure Using a Nonlinear Flexible Dynamic Vibration Absorber". Mathematics 10, n.º 5 (24 de fevereiro de 2022): 708. http://dx.doi.org/10.3390/math10050708.
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The online frequency estimation of forced harmonic vibrations on a building-like structure, using a nonlinear flexible vibration absorber in a cantilever beam configuration, is addressed in this article. Algebraic formulae to compute online the harmonic excitation frequency on the nonlinear vibrating mechanical system using solely available measurement signals of position, velocity, or acceleration are presented. Fast algebraic frequency estimation can, thus, be implemented to tune online a semi-active dynamic vibration absorber to obtain a high attenuation level of undesirable vibrations affecting the main mechanical system. A semi-active vibration absorber can be tuned for application where variations of the excitation frequency can be expected. Adaptive vibration absorption for forced harmonic vibration suppression for operational scenarios with variable excitation frequency can be then performed. Analytical, numerical, and experimental results to demonstrate the effectiveness and efficiency of the operating frequency estimation, as well as the acceptable attenuation level achieved by the tunable flexible vibration absorber, are presented. The algebraic parametric estimation approach can be extended to add capabilities of variable frequency vibration suppression for several configurations of dynamic vibration absorbers.
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Shiozaki, Tetsuya, Akio Nozawa, Yoshimi Nakazono, Masafumi Uchida, Hisaya Tanaka e Hideto Ide. "Quantitative Evaluation of the Tactile Sense by ERP". Journal of Robotics and Mechatronics 15, n.º 1 (20 de fevereiro de 2003): 33–38. http://dx.doi.org/10.20965/jrm.2003.p0033.
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We have developed a method of quantitative evaluation for vibration discrimination by ERP (Event Related Potential). We made a modulation matrix of high-pass component (40-200Hz) and low-pass component (2-20Hz), and gave modulated vibrations to a foretinger by a piezoelectric vibratos We examined ERP differences, which are amplitudes, areas and intervals, between a reference vibration of 2/40Hz and controlled vibrations.
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He, Hong Lin, Dong Mei Wu e Wen Guang Liu. "A Linear Piezoelectric Linear Motor Driven by the in-Plane Longitudinal and Bending Vibrations of an H-Shaped Vibrator". Advanced Materials Research 472-475 (fevereiro de 2012): 2824–27. http://dx.doi.org/10.4028/www.scientific.net/amr.472-475.2824.
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In order to develop theoretical instructions for design of high performance linear motor, a piezoelectric linear motor based on an H-shaped vibrator is proposed, which employed the vibrator’s 2nd bending vibration mode and 1st longitudinal planar vibration to drive the motor in this paper. Firstly, the driving principle of the motor is presented, and the elliptical motion generated on the driving end of the vertical bars of the vibrator is proved. Then, FEM simulation model is built for the vibrator, which is used to calculate the vibrator’s working modes and to execute harmonic response analysis and sensitivity analysis for the vibrator. Furthermore, the vibration’s optimal size is given and the motor assembly structure is designed. Finally, modal test is done for the vibrator to validate the anticipated work modes vibration and the bending vibration and longitudinal planar vibration could be 1.4μm and1.2μm under normal drive.
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Oroszi, Tamás, Marieke J. G. van Heuvelen, Csaba Nyakas e Eddy A. van der Zee. "Vibration detection: its function and recent advances in medical applications". F1000Research 9 (17 de junho de 2020): 619. http://dx.doi.org/10.12688/f1000research.22649.1.
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Vibrations are all around us. We can detect vibrations with sensitive skin mechanoreceptors, but our conscious awareness of the presence of vibrations is often limited. Nevertheless, vibrations play a role in our everyday life. Here, we briefly describe the function of vibration detection and how it can be used for medical applications by way of whole body vibration. Strong vibrations can be harmful, but milder vibrations can be beneficial, although to what extent and how large the clinical relevance is are still controversial. Whole body vibration can be applied via a vibrating platform, used in both animal and human research. Recent findings make clear that the mode of action is twofold: next to the rather well-known exercise (muscle) component, it also has a sensory (skin) component. Notably, the sensory (skin) component stimulating the brain has potential for several purposes including improvements in brain-related disorders. Combining these two components by selecting the optimal settings in whole body vibration has clear potential for medical applications. To realize this, the field needs more standardized and personalized protocols. It should tackle what could be considered the “Big Five” variables of whole body vibration designs: vibration amplitude, vibration frequency, method of application, session duration/frequency, and total intervention duration. Unraveling the underlying mechanisms by translational research can help to determine the optimal settings. Many systematic reviews on whole body vibration end with the conclusion that the findings are promising yet inconclusive. This is mainly because of the large variation in the “Big Five” settings between studies and incomplete reporting of methodological details hindering reproducibility. We are of the opinion that when (part of) these optimal settings are being realized, a much better estimate can be given about the true potential of whole body vibration as a medical application.
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Bespalov, A. L., e I. G. Svidrak. "Universalization of the elastic system of vibration feeders with vertical electromagnetic vibration drive". Scientific Messenger of LNU of Veterinary Medicine and Biotechnologies 24, n.º 97 (28 de junho de 2022): 41–45. http://dx.doi.org/10.32718/nvlvet-f9707.
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Vibrating feed bins with electromagnetic drive are widely used in the automation of production processes in mechanical engineering and instrument engineering. They are used for feeding miniature, small, or medium-sized parts to automated production equipment. This equipment is used in automatic lines, automated complexes, or any other flexible automated production facilities. These devices are most widely used for loading parts to assembly positions in automated assembly complexes. In this case, the parts fed to these positions must be located in a certain stable position. Various orientation tools are used for this purpose. They are located directly on the transport trays in the bins of these devices. Therefore, for reliable operation of orientation devices, the movement of parts on the trays should be smooth without sensitive tossing. The designs of vibrating hopper feeders with a hopper connected to a reactive plate by a directional elastic system in the form of a lattice torsion bar are considered. An electromagnetic vibration exciter is placed between the torsion flanges. The disadvantage of such vibration feeders is low productivity in operating modes, especially when there are increased requirements for the smooth movement of transported parts. An increase in the productivity of such feeders is carried out by increasing the amplitude of hopper vibrations in the direction of movement of parts, that is, the horizontal component of vibrations. However, this also leads to an increase in the vertical component, since vibrations are carried out at an angle to the feeder transport tray. When the vertical component of vibrations increases, the transportation of parts switches to the intensive tossing mode. A further increase in the oscillation amplitude leads to a violation of the normal mode of vibrational transport. Modern production involves the modernization of existing structures, as well as the creation of new models of machines with high technical and economic indicators Therefore, the universalization of existing equipment and the development of new machine schemes is an important task for developers and manufacturers of technological equipment, since even a minimal improvement in its technological or operational indicators can lead to a significant economic effect. The paper considers a complex of additional elements used that make it possible to universalize the design of vibrating hopper feeders with electromagnetic drives having a directional elastic system. These changes make it possible to adjust the horizontal component of the device hopper vibrations at a constant vertical one. Additional structural elements are proposed that increase the range of application of such feeders.
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Pal, Anjan. "Design, Analysis & Optimization of Muffler for Four Stroke Petrol Engine Motorcycle". International Journal for Research in Applied Science and Engineering Technology 11, n.º 5 (31 de maio de 2023): 886–90. http://dx.doi.org/10.22214/ijraset.2023.51692.
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Abstract: Objective: The exhaust pipe is subjected to several stresses, most of which are due to vibration. Particular attention should be given to gas forces which will induce vibration. These vibrations will then induce a fatigue life to the system. It is therefore necessary to study the fatigue behavior of the exhaust pipe by analyzing the vibration modes and the response of vibrations by its sources. Methods: The vibrations of silencer are affecting the performance of silencer and it is uncomfortable to operators. So, it is necessary to analyze the vibrations which would further help to minimize cracks, improving life and efficiency of silencer. the main goal of this project will be to design a new automobile exhaust piper muffler (silencer) is to increase the durability of its life. Decrease the weight, and reduce the manufacturing cost with efficient working condition. design, analyze the model using ANSYS workbench static structural and model analysis for vibration study. If muffler or silencer part impacts high vibrations, or stress then topology will be conducted to solve the high stress concentration and vibrational impacts
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Hubbard, Mont, e Christy D. Bergman. "Effect of Vibrations on Javelin Lift and Drag". International Journal of Sport Biomechanics 5, n.º 1 (fevereiro de 1989): 40–59. http://dx.doi.org/10.1123/ijsb.5.1.40.
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The theory of crossflow aerodynamics is used to estimate the effect of thrower-induced vibrations on javelin mean lift and drag. Vibrations of all modes increase both lift and drag from the vibration-free condition. Percentage in-creases in lift and drag are largest at small mean angles of attack, large vibrational amplitudes, and large relative wind speeds. Thus the consequences of vibration effects on aerodynamics may be most significant for elite throwers.
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Kłosiński, Jacek, Ludwik Majewski e Arkadiusz Trąbka. "Control of Two-Dimensional Vibrating System". Solid State Phenomena 164 (junho de 2010): 333–38. http://dx.doi.org/10.4028/www.scientific.net/ssp.164.333.
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A strategy for control of a system of two electrical vibrators mounted onto the vibrating plate of a typical small table vibrator was discussed in the present paper. The aim of the considered control system is rapid positioning of counterbalances for ensuring achievement of the assumed directions of vibrations and loading forces (where , m is unbalanced mass, ω is angular velocity of the vibrator shaft, e is distance between the unbalanced mass and the vibrator rotary axis). The strategy of the control consists in setting of different directions of vibrator rotations together with controlled change of vibration frequency and amplitude. Numerical analysis was performed. The obtained results are presented in a graphical form.
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Oliinyk, O. Yu. "VIBRATION FREQUENCY DENSITY CONTROL METHOD IN VIBRATION CONDITIONS". METHODS AND DEVICES OF QUALITY CONTROL, n.º 2(43) (24 de dezembro de 2019): 41–47. http://dx.doi.org/10.31471/1993-9981-2019-2(43)-41-47.
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The use of existing vibration frequency measuring instruments for monitoring technological parameters inside apparatus and equipment is limited due to the presence of vibrations and industrial noise. The lack of data on the use of part of the technological apparatus as flow resonators through the unexplored basic analytical equations for determining the amplitude-frequency characteristics of such resonators determined the direction of these studies. The article is devoted to studies aimed at establishing the relationship between the vibrational field of the resonator, which is used as part of the technological apparatus with a controlled environment, and its reaction in the form of a change in the frequency or amplitude of the resonator’s own vibrations, which carries information about the properties of the substance in the apparatus. The experimental setup diagram, experimental methodology, and data on determining the oscillation frequency of the resonator under vibration conditions for metallic (corrosion-resistant steel) and non-metallic (organic glass) resonators are presented. The curves obtained from the experimental values were approximated using linear and hyperbolic approximations. It was found that the use of hyperbolic approximation reduces the average approximation error by more than six times. It was found that the error of the hyperbolic approximation error does not exceed 0.022% for a metal resonator and 0.05% for an organic glass resonator. The conducted experimental studies confirm the presence of a determinate coupling of the measured frequency characteristics of the resonator with the density, which was measured inside the equipment. The obtained data was used to develop the scientific and methodological foundations of the vibrational frequency control method in conditions of vibration using a part of the device as a resonator of the vibrational frequency sensor.
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Shimose, Shigeru, Kanjuro Makihara e Junjiro Onoda. "Comparison of Analog and Digital Self-Powered Systems in Multimodal Vibration Suppression". Smart Materials Research 2012 (21 de fevereiro de 2012): 1–9. http://dx.doi.org/10.1155/2012/287128.
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This paper compares our analog and digital self-powered systems for vibration suppression, and shows experimental results of multimodal vibration suppression for both self-powered systems. The experimental results are evaluated in light of the damping performance and adaptability under various vibrational conditions. We demonstrate various examples of our innovative vibration suppression method, called “digital self-powered.” Proper status switching of an electric circuit made up of an inductor and a selective switch connected to a piezoelectric transducer attenuates the vibrations. The control logic calculation and the switching events are performed with a digital microprocessor that is driven by the electrical energy converted from the mechanical vibration energy. Therefore, this vibration suppression system runs without any external power supply. The self-powering feature makes this suppression method useful in various applications. To realize an ideal vibration suppression system that is both self-powered and effective in suppressing multimode vibration, sophisticated control logic is implemented in the digital microprocessor. We demonstrate that our digital self-powered system can reduce the vibrational displacements of a randomly excited multimodal structure, by as much as 35.5%.
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Jiang, Li, Zhenyue Ma, Jianwei Zhang, Mohd Yawar Ali Khan, Mengran Cheng e Libin Wang. "Chaotic Characteristic Analysis of Vibration Response of Pumping Station Pipeline Using Improved Variational Mode Decomposition Method". Applied Sciences 11, n.º 19 (23 de setembro de 2021): 8864. http://dx.doi.org/10.3390/app11198864.
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The measured vibrational responses of the pumping station pipeline in the irrigation site were chosen to confirm the chaotic characteristics of the pumping station pipeline vibration and to determine the vibrational excitation that makes it chaotic. First, the chaotic properties of the pipeline vibration responses were investigated using a saturation correlation dimension and the maximum Lyapunov exponent. The vibration excitation with chaotic features was obtained using an improved variational mode decomposition (IVMD) method to examine the multi-time-scale chaotic characteristics of the pipeline vibration responses. The results show that the vibrational responses of each measuring point of the pipeline under different operating conditions have clear chaotic characteristics, where the chaotic characteristics of the axial points and bifurcated pipe points are relatively strong. The vibration of the operating conditions and measurement points affected by the unit’s operation and flow state change is further complicated. The intrinsic mode function (IMF) produces a low-dimensional chaotic attractor after the IVMD disrupts the vibration response. Still, the vibration excitation of the remaining components on behalf of the units does not have chaotic properties, implying that water pulsation excitation makes the pumping station pipeline vibrations chaotic. The vibration excitation caused by the unit’s operation covers the chaotic characteristics of the pipeline vibration and increases its uncertainty. The outcomes of this study provide a theoretical basis for further exploration of the vibration characteristics of pumping station pipelines, and a new method of chaos analysis is proposed.
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Liang, Hongyu, Zhigang Wu, Jifeng Hu, Yuannan Gan e Sheng Qiang. "Simulation Test of an Intelligent Vibration System for Concrete under Reinforcing Steel Mesh". Buildings 14, n.º 8 (23 de julho de 2024): 2277. http://dx.doi.org/10.3390/buildings14082277.
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Concrete vibration construction sustains high labor intensity, a poor working environment, difficulties in quality control, and other problems. Current research on concrete vibration focuses on monitoring vibration quality, evaluating vibration processes quantitatively, and assessing mechanical vibration of unreinforced mesh concrete (plain concrete). Standardizing concrete vibration under reinforcing steel mesh remains difficult. There is still a lag in the evaluation of the quality of rework and the consumption of human and material resources. To tackle these issues, a vibrating robotic arm system based on automation control technology, machine vision, and kinematic modeling is proposed. Research and simulation tests on intelligent concrete vibration under reinforcing steel mesh aim to enhance construction efficiency and quality. A five-degree-of-freedom robotic arm with a vision module identifies each rebar grid center in the image, extracts the pixel coordinates, and converts them to the mechanical coordinates by the integration of machine vision algorithms. A vibrator point screening algorithm is introduced to determine actual vibrator point locations based on specific insertion spacing, alongside a vibro-module for vertical movement. Real-time assessment of vibration quality is achieved using the YOLOv5 target detection model. Simulation tests confirm the feasibility of automated concrete vibration control under reinforcing steel mesh by a vibrating robot arm system. This research offers a new approach for unmanned vibration technology in concrete under reinforcing steel mesh, supporting future related technological advancements with practical value.
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Shpachuk, V. P., M. A. Zasiadko, T. O. Suprun e V. V. Dudko. "Variation coefficient of torsional vibrations of the connection nodes of vibrating machines". Naukovyi Visnyk Natsionalnoho Hirnychoho Universytetu, n.º 6 (2021): 85–89. http://dx.doi.org/10.33271/nvngu/2021-6/085.
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Purpose. To formalize the dependence of the eigenfrequencies of translational and torsional vibrations of the structural elements of the vibrating machine articulated by the connection node on their design parameters and mechanical characteristics, as well as regulatory requirements for vibration activity, strength and accuracy. To develop a method for selecting the design parameters of the elastic band element of the package, taking into account the specified values of the amplitude and frequency characteristics of the dynamic loads reproduced by the supporting structure and the coefficient of variation of the natural frequencies of translational and torsional vibrations. Methodology. The research is based on fundamental approaches of applied mechanics, machine dynamics and vibration reliability. Findings. The dependences of the eigenfrequencies of torsional vibrations of the body parts of the vibrating machine connected by the connection node on their design parameters and mechanical characteristics are obtained and analyzed. Vibrations around an axis orthogonal to the working direction of the node are considered. A comparative analysis of the natural frequencies of the node in the direction of the transmitted vibration and its circular vibrations from the design parameters and mechanical characteristics of the elastic band elements, their number in the package and the number of packages in the connection node is performed. Originality. It is in the fact that for the first time the dependences describing the natural frequencies of translational and torsional vibrations of the body parts of a vibrating machine, articulated by a package of elastic band elements, are obtained. Also the paradigm for the choice of design parameters and mechanical characteristics of the elastic band element of the package, which is based on the results of a comparative analysis of the eigenfrequencies of vibrations in the working and connected directions through their coefficient of variation is innovative. This made it possible to include the criterion of vibration reproduction accuracy, which is formalized through the coefficient of frequency variation, together with the criteria of strength and rigidity, in the methodology of synthesis of the structural scheme of the vibrating machine. Practical value. The proposed methodological solutions for the calculation and selection of design parameters and mechanical characteristics of tape elastic elements ensure the achievement of vibration activity indicators of articulated parts, as well as the ratio of natural vibration frequencies in the working and related directions at the level of the requirements of normative documents when upgrading existing machines and creating new modern equipment. As a result, the reliability, durability, safety, productivity and load-bearing capacity of machines, equipment and mechanisms of mining engineering, aviation, transport and space technology are increased.
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Li, Shan, Liang Xu e Yu Qi Wang. "The Research of COMAS Vibrating Conveyor Noise Reduction". Applied Mechanics and Materials 184-185 (junho de 2012): 583–86. http://dx.doi.org/10.4028/www.scientific.net/amm.184-185.583.
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In a cigarette silk production line of a cigarette factory, the noise of vibrating conveyor not only endangers the health of workers’ listening, but also reduces work efficiency. In this paper, the modal of the frame was analyzed with the ANSYS software. The analysis results show that the frame has torsion vibration and swing. These vibrations will bring adverse effects and noise. Through designing a vibration isolation system on the vibrating conveyor, the reasonableness and effectiveness of the isolation component were proved with static and dynamic analysis of the vibration isolation system with finite element method. At the same time, some rules what select the spring parameters were summed up. Through analyzing the isolation effect of the vibration isolation system in different parameters, these regularity conclusions will provide a basis for the noise reduction [1].
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Pelmear, P. L., e D. K. N. Leong. "EU Directive on Physical Agents — Vibration". Journal of Low Frequency Noise, Vibration and Active Control 21, n.º 3 (setembro de 2002): 131–39. http://dx.doi.org/10.1260/026309202321164702.
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Vibrations that arouse human health concerns are classified into two main categories: (1) hand-arm vibrations (HAV) and (2) whole-body vibrations (WBV). Hand-transmitted vibration from a power or impact tool affects the upper extremities of the body. WBV affects the entire body and is transmitted from a vibrating seat, bed or floor to a person who is in a sitting, Iying or standing position. The EU Directive April 5, 2002 provides exposure limit and action values for both HAV and WBV. These values have taken into consideration recent advances in knowledge and the political judgment of the Member States so are at variance with the present Health and Safety Executive (HSE) values and the ACGIH TLVs. This paper reviews the development of international standards for vibration and the requirements of the EU Directive.
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Tytova, Tamila, Aleksander Shashuryn, Konstantin Buzhynskiy e Valeriy Svetlov. "Vibrations’ formation and transmission during high-speed trains’ operation". Bulletin of scientific research results, n.º 3 (17 de outubro de 2017): 89–95. http://dx.doi.org/10.20295/2223-9987-2017-3-89-95.
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Objective: To determine the mechanisms of vibration’s occurrence and transmission during high-speed trains’ operation. Methods: The occurrence and transmission of vibration is calculated by means of vibration attenuation calculation method, which results from the extension of the vibration wave front in space, ground internal loss and elastic medium wave impedance. Results: Theoretical studies were generally confirmed by the results of experimental studies. Practical importance: Application of the given calculation method of vibration dumping in the early stages of high-speed railway lines construction, in order to predict the level of vibrations and select the means of level protection.
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Qin, Bin, Md Mahbub Alam e Yu Zhou. "Free vibrations of two tandem elastically mounted cylinders in crossflow". Journal of Fluid Mechanics 861 (21 de dezembro de 2018): 349–81. http://dx.doi.org/10.1017/jfm.2018.913.
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The paper presents an experimental investigation on the flow-induced vibrations of two tandem circular cylinders for spacing ratio $L/D=1.2{-}6.0$ and reduced velocity $U_{r}=3.8{-}47.8$, where $L$ is the cylinder centre-to-centre spacing and $D$ is the cylinder diameter. Both cylinders are allowed to vibrate only laterally. Extensive measurements are conducted to capture the cylinder vibration and frequency responses, surface pressures, shedding frequencies and flow fields using laser vibrometer, hotwire, pressure scanner and PIV techniques. Four vibration regimes are identified based on the characteristics and generation mechanisms of the cylinder galloping vibrations. Several findings are made on the mechanisms of vibration generation and sustainability. First, the initial states (vibrating or fixed) of a cylinder may have a pronounced impact on the vibration of the other. Second, alternating reattachment, detachment, rolling up and shedding of the upper and lower gap shear layers all contribute to the vibrations. Third, the gap vortices around the base surface of the upstream cylinder produce positive work on the cylinder, sustaining the upstream cylinder vibration. Fourth, reattachment, detachment and switching of the gap shear layers result in largely positive work on the downstream cylinder, playing an important role in sustaining its vibration.
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Itoh, Shingo, Keigo Tsujita, Taiki Morishige e Toshihide Takenaka. "The Effect of Vibration Condition for Magnesium Dry Gravity Sorting by Vibrating Particulate Bed". Materials Science Forum 941 (dezembro de 2018): 1535–39. http://dx.doi.org/10.4028/www.scientific.net/msf.941.1535.
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Recycling Mg alloys has been demanded as the demand of Mg alloys has been increased. It is difficult to separate Mg with Al because the properties are similar except for the density. In this study, gravity sorting by vibrating particulate bed ajusted the density to intermediate between Mg and Al was applied for Mg separation with Al. The relationship the vibrating condition and the sorting accuracy was investigated by applying different vibration acceleration and by applying the vertical and horizontal vibration. Turbulent flow was observed and the recovery rate was improved when vertical vibration with high acceleration was applied to the bed. Higher recovery rate was achieved when horizontal vibration was applied to the bed. This result suggested that the horizontal movement of particle affected the behavior of sorting materials and high recovery ratio was achieved by optimizing vibrational condition such as vibration acceleration and the direction of vibration.
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Alphin, M. S., J. Paul Chandra Kumar e B. Jain A. R. Tony. "Biomechanical Response of the Human Foot Model Exposed to Vibrations: A Finite Element Analysis". Journal of Biomaterials and Tissue Engineering 11, n.º 11 (1 de novembro de 2021): 2097–108. http://dx.doi.org/10.1166/jbt.2021.2748.
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Prolonged exposure to mechanical vibration has been associated with many musculoskeletal, vascular and sensorineural disorders of the foot from simple Plantar fasciitis and Achilles Tendonitis to complex ones as Tarsal tunnel syndrome (TTS) and Vibration white feet/toes. Foot-transmitted vibrations (FTV) are exposed to the occupants using vibrating equipment’s or standing on vibrating platforms. Prolonged exposure to foot-transmitted vibrations (FTV) can lead to syndromes like vibration white feet/toes may result in tingling sensation, blanching of the toes and even numbness in the feet and toes. A multi-layered two dimensional, plane strain finite element model is developed from the actual cross-section of the human foot to study the stresses and strains developed in the skin and soft tissues. The foot is assumed to be in contact with a steel plate, mimicking the interaction between the foot and the work platform. The skin and the subcutaneous tissue are considered as hyperelastic and viscoelastic. The effects of loading in the form of displacements and the frequency of sinusoidal vibration on a time-dependent stress/strain distribution at various depths in the subcutaneous tissue of the foot are investigated. The simulations indicate that lower frequency vibrations penetrate deep into the subcutaneous tissue while higher frequencies are concentrated in the outer skin layer. The present biomechanical model may serve as a valuable tool to study the response of foot of those who work on a vibrating platform.
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Rahemtulla, Hughes-Riley e Dias. "Developing a Vibration-Sensing Yarn for Monitoring Hand-Transmitted Vibrations". Proceedings 32, n.º 1 (4 de dezembro de 2019): 6. http://dx.doi.org/10.3390/proceedings2019032006.
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Overexposure to hand-transmitted vibrations (HTVs) is a serious concern within industries that use vibrating power tools as HTVs can lead to severe and chronic injuries to the hand-arm system, which are preventable by limiting vibration exposure. This study presents a novel vibration-sensing electronic yarn (E-yarn) that can be used to monitor HTVs at the point-of-entry of the vibrations into the hand. The construction of the vibration-sensing E-yarn is described, with the vibration-sensing E-yarns being fully characterised at each stage of the manufacturing process to understand how the manufacturing stages affect the behaviour of the embedded sensor. The results show that there is no significant difference in the sensor response at each of the three stages in the E-yarn production over a range of frequencies and amplitudes relevant to HTVs.
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YAN, Y., W. Q. WANG e L. X. ZHANG. "NONLINEAR VIBRATION CHARACTERISTICS OF FLUID-FILLED DOUBLE-WALLED CARBON NANOTUBES". Modern Physics Letters B 23, n.º 22 (30 de agosto de 2009): 2625–36. http://dx.doi.org/10.1142/s0217984909020746.
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Nonlinear vibration behaviors of double-walled carbon nanotubes (DWCNTs) with fluid inside the inner tube are investigated based on Donnell's cylindrical shell model and the more refined van der Waals (vdW) interaction formula. The Galerkin method and harmonic balance method are used to study the issue. The results obtained show that the radial vibrational modes of simply supported DWCNTs have twice the dynamical mode transitions as the frequency increases. The transitions correspond to twice the noncoaxial vibrations which play a critical role in electronic and transport properties of CNTs. Moreover, comparisons of the dynamical behaviors of fluid-filled DWCNTs with different wave numbers, radii and aspect ratios demonstrate that the amplitude–frequency curve topological forms are identical. Meanwhile, it is also concluded that the existence of fluid is significant for the value of amplitude ratio corresponding to noncoaxial vibration whereas it does not change the nonlinear vibrating topological pattern of amplitude–frequency curves.
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Cieplok, Grzegorz. "Estimation of the resonance amplitude in machines with inertia vibrator in the coast-down phase". Mechanics & Industry 19, n.º 1 (2018): 102. http://dx.doi.org/10.1051/meca/2017035.
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The work concerns mechanical systems with transient resonance formed as a result of an unbalanced rotating mass passing through an area of the system's natural frequency. In particular, this concerns over-resonant vibrating machines driven by inertia vibrators, which during start-up and coast-down pass through the natural frequency area related to the vibrating mass – flexible suspension system. The work analyses a system consisting of a soft-mounted machine body excited into vibrations by means of the inertia vibrator in order to designate the amplitude of resonant vibration, taking into consideration strong coupling between movements of the body and vibrator. The research results are presented in the form of nomograms and approximation formulas expressed in terms of relative parameters. The results of the theoretical research were verified on the laboratory model and industrial machines.
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Trujillo-Franco, Luis Gerardo, Nestor Flores-Morita, Hugo Francisco Abundis-Fong, Francisco Beltran-Carbajal, Alejandro Enrique Dzul-Lopez e Daniel Eduardo Rivera-Arreola. "Oscillation Attenuation in a Building-like Structure by Using a Flexible Vibration Absorber". Mathematics 10, n.º 3 (18 de janeiro de 2022): 289. http://dx.doi.org/10.3390/math10030289.
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This is a theoretical, numerical, and experimental study on the vibration attenuation capability of the dynamic response of a building-like structure using a dynamic vibration absorber in cantilever flexible beam configuration, taking into account gravitational effects associated with its mass. The dynamic model of the primary vibrating structure with the passive vibration control device is obtained using the Euler–Lagrange formulation considering the flexible vibration absorber as a generalized system of one degree of freedom. The application of the Hilbert transform to the frequency response function to determine the tuning conditions between this nonlinear flexible beam vibration absorber and the primary system is also proposed. In this fashion, Hilbert transform analysis is then carried out to show that nonlinearities present in the dynamic model do not significantly contribute to the performance of the implemented absorber. Therefore, it is valid to linearize the equations of motion to obtain the tuning condition in which the flexible vibration absorber can attenuate undesirable harmonic vibrations that are disturbing to the building-like flexible structure. Thus, the present study shows that the Hilbert transform can be applied to obtain tuning conditions for other configurations of dynamic vibration absorbers in nonlinear vibrating systems. Simulation and experimental results are included to demonstrate the efficient performance of the presented vibration absorption scheme.
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BIENIEK, Piotr, Grzegorz KOWALIK e Karol ŁYSIAK. "Influence of Technological Instruments on the Course of Vibration Tests Carried Out on the Inductor of Vibrations for 120 mm Mortar Cartridges". PROBLEMY TECHNIKI UZBROJENIA 159 (16 de maio de 2022): 47–71. http://dx.doi.org/10.5604/01.3001.0015.8553.
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The paper deals with a proper selection of technological instruments for fixing 120 mm mortar cartridges into the vibrations inductor at laboratory testing. The work was aimed to find out the influence of modified technological instruments on the course of vibration tests in comparison to an original design which had been changed along with performed trials to take into account the fixation on the vibrations inductor and matching with the tested sample. Aspects connected with the improvement of the technological handle, which is a transitional device between the vibrating system and tested sample, have essential impact into the course of vibration tests which were conducted both on the head and the sliding table of the inductor for comparison. Each test is burdened by actions of adverse effects which are partially caused by the design of the vibrating system, and hence the experience of operator and selection of suitable technological handle are also important for coping with difficulties. For this reason it may be helpful to use some recommendations described in the paper for balancing disproportions connected with the limitations of the vibration inductor and fabrication and fixation of the handle for 120 mm mortar cartridge. The way of coping with encountered difficulties is presented directly with proposed solutions on the base of vibration tests examining the resistance of 120 mm mortar cartridges against mechanical loads in the form of sinusoidal vibrations.
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Shen, Xiaoyan, Jing Yu, Jianlong Yin e Dongsheng Li. "Experimental Study of See-Saw Mode Nano-Vibration on Orifice-Type Restrictors". Applied Sciences 11, n.º 11 (6 de junho de 2021): 5265. http://dx.doi.org/10.3390/app11115265.
Texto completo da fonteResumo:
Slide stability is key to the aerostatic guide in ultra-precise machines; thus, it has garnered plenty of attention. Macro-scale studies are commonplace, but micro- and nano-vibration issues require more attention. Microscope vibration is mainly caused by tiny changes in the fluid parameters of lubricating gas film, which is complex and has no verdict. In this case, slide-gas interaction should be considered. In this study, the widely used orifice-type restrictor was investigated for its nano-vibration performance. A Comsol finite-element-method fluid–structure interaction model was used to simulate and analyze an orifice-type restrictor, and orifice-restrictor vibration characteristics at the nanometer scale were inspected using a high-performance laser vibrometer. The results demonstrate that see-saw mode vibrations occur in the restrictors, growing stronger with increased air-supply pressure. The see-saw vibration’s axis is speculatively determined based on orifice and restrictor structures, and the vibration type is related to the number of orifices. The results also show that the vibration is random with natural frequencies at the kilohertz level. The newly provided research results are beneficial for better understanding the nano-vibrations of orifice-type restrictors.
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Chang, Shuqi, Luoning Zhang, Zhimeng Zhang e Chunning Ji. "Dynamics and Wake Interference Mechanism of Long Flexible Circular Cylinders in Side-by-Side Arrangements". Energies 17, n.º 11 (4 de junho de 2024): 2741. http://dx.doi.org/10.3390/en17112741.
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The vortex-induced vibrations of two side-by-side flexible cylinders in a uniform flow were studied using a three-dimensional direct numerical simulation at Reynolds number Re = 350 with an aspect ratio of 100, and a center-to-center spacing ratio of 2.5. A mixture of standing-traveling wave pattern was induced in the in-line (IL) vibration, while the cross-flow (CF) vibration displayed a standing-wave characteristic. The ninth vibration mode prominently occurred in both IL and CF directions, along with competition between multiple modes. Proximity effects from the neighboring cylinder caused the primary frequency to be consistent between IL and CF vibrations for each cylinder, deviating from the IL to CF ratio of 2:1 in isolated cylinder conditions. Repulsive mean lift coefficients were observed in both stationary and vibrating conditions for the two cylinders due to asymmetrical vortex shedding in this small gap. Comparatively, lift and drag coefficients were notably increased in the vibrating condition, albeit with a lower vortex shedding frequency. Positive energy transfer was predominantly excited along the span via vortex shedding from the cylinder itself and the neighboring one, leading to increasing lower-mode vibration amplitudes. The flip-flopping (FF) wake pattern was excited in the stationary and vibrating cylinders, causing spanwise vortex dislocations and wake transition over time, with the FF pattern being more regular in the stationary cylinder case.
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Nikulina, S. A., A. V. Perminov e T. P. Lyubimova. "Thermal vibrational convection of a pseudoplastic fluid in a rectangular cavity". Вестник Пермского университета. Физика, n.º 3 (2020): 14–23. http://dx.doi.org/10.17072/1994-3598-2020-3-14-23.
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Thermal vibrational convection of a pseudoplastic fluid in a closed rectangular cavity, which is in zero gravity and performing longitudinal high-frequency linearly polarized vibrations, is studied. The temperature gradient is perpendicular to the direction of vibration. The system of equations of thermovibrational convection of a Williamson pseudoplastic fluid is given. The problem was solved by the finite difference method. The effect of vibrations on the structure and intensity of flows is investigated. The magnitude of the vibrational effect on the liquid was determined by the vibrational Grashof number. The dependences of the maximum of the stream function and the Nusselt number, which determines the heat flux through the boundary of the cavity, on the vibrational Grashof number are obtained. The threshold values of the vibrational Grashof number and the Nusselt number corresponding to a change in the flow regime are determined. At small values of the Grashof vibration number in the cavity, a slow four-vortex symmetric flow is observed. With an increase in the vibrational impact, an intense three-vortex motion arises in the cavity, which transforms into five vortex-like motion. For the five vortex flows, there exists the region of Grashof vibration numbers, where this flow is oscillatory in nature. With increasing degree of non-Newtonian fluid, initially periodic oscillations become chaotic.