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Статті в журналах з теми "Vibration frequency control method"
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Oliinyk, O. Yu. "VIBRATION FREQUENCY DENSITY CONTROL METHOD IN VIBRATION CONDITIONS." METHODS AND DEVICES OF QUALITY CONTROL, no. 2(43) (December 24, 2019): 41–47. http://dx.doi.org/10.31471/1993-9981-2019-2(43)-41-47.
Повний текст джерелаАнотація:
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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Barrault, Guillaume, Dunant Halim, and Colin Hansen. "High frequency spatial vibration control using method." Mechanical Systems and Signal Processing 21, no. 4 (May 2007): 1541–60. http://dx.doi.org/10.1016/j.ymssp.2006.08.013.
Повний текст джерела
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Jiao, Z., P. Chen, Q. Hua, and S. Wang. "Adaptive vibration active control of fluid pressure pulsations." Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering 217, no. 4 (June 1, 2003): 311–18. http://dx.doi.org/10.1177/095965180321700407.
Повний текст джерелаАнотація:
Conventionally, passive hydraulic absorbers are utilized in order to reduce the vibrations of the fluid power supply systems. It is very difficult to adapt the variable operation conditions, such as inconsistent vibration frequency and varying loads. This paper presents a new vibration active control method to diminish the vibrations of the fluid power supply efficiently. This method is adaptive and robust in controlling the fluctuating frequencies and load disturbances and is capable of keeping the vibrations at a minimum level under variable pump speeds. This paper illustrates the theory and experimentation of vibration active control of a fluid power supply pipeline system in detail. The multilayer piezoelectric technology (PZT) driven orifice valve is designed with characteristics of a proportional opening area to the control voltage, a high-frequency bandwidth and small size. The adaptive-optimum control method is adopted to adjust the control parameters at any instant against emerging disturbances. Based on the test rig, different vibration control methods were applied; the results indicate and confirm the validity of this principle.
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Cheng, Mingke, Feng Gao, and Yan Li. "Vibration Detection and Experiment of PMSM High Speed Grinding Motorized Spindle Based on Frequency Domain Technology." Measurement Science Review 19, no. 3 (June 1, 2019): 109–25. http://dx.doi.org/10.2478/msr-2019-0017.
Повний текст джерелаАнотація:
Abstract The spindle vibrations of the high-speed grinding motorized spindle largely determine the machining quality and precision. In order to accurately predict the spindle vibrations of the PMSM high-speed grinding motorized spindle, the vibration causes are explored and analyzed. The radial vibration, inclined vibration, and axial vibration model are established. The experimental modal analysis method is proposed to analyze the dynamic response of the spindle and to identify the modal parameters of the spindle structure. Thereafter, the frequency response function (FRF) is calculated by self-power spectrum and cross-power spectrum. It is transformed into the vibration spectrum analysis of the spindle. The least-square method is used to fit the radial trajectory of the spindle. This paper aims to propose double standard spheres for 5- DOF spindle vibrations used to detect the spindle vibrations. In the experiment, the method proposed in this paper can effectively and accurately determine the causes of the spindle vibrations. The spectrum analysis and the trajectory are common tools in the spindle vibration detection.
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Du, Xiangyu, Rong Huang, Balaji Vengatachalam, and Zishun Liu. "Vibration control for slotted plate using structural intensity method." International Journal of Computational Materials Science and Engineering 07, no. 01n02 (June 2018): 1850006. http://dx.doi.org/10.1142/s2047684118500069.
Повний текст джерелаАнотація:
In this paper, we study the vibration performance of simply supported slotted plate using structural intensity (SI) method. First, the SI distribution of the slotted plate under given excitation for different slot depths is obtained using finite element methods. The SI streamline of each case shows that the SI distribution can be significantly affected by adjusting the slot depth. The optimal position of dampers which can effectively implement vibration control of slotted plate for the fixed value of exciting frequency can be obtained from the SI streamline distribution. In case of changing vibrating frequencies, a new strategy of vibration control by adding soft material (hydrogel) layers is proposed. The main advantage of this strategy is that the properties of hydrogel can be easily adjusted by changing the chemical potential, thereby achieving the desired vibration control for different excitation conditions. The effectiveness of the proposed vibration control using hydrogel layers is investigated using SI method. The SI distribution and SI streamlines of the slotted plate with the new vibration control show that the proposed strategy is convenient. Our proposed method conceptualizes a new approach toward vibration control using constrained hydrogel layer.
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Zheng, Yangbo, Ni Mo, Zhe Sun, Yan Zhou, and Zhengang Shi. "Study on Unbalanced Magnetic Pulling Analysis and Its Control Method for Primary Helium Circulator of High-Temperature Gas-Cooled Reactor." Energies 12, no. 19 (September 26, 2019): 3682. http://dx.doi.org/10.3390/en12193682.
Повний текст джерелаАнотація:
In addition to providing an extremely clean environment for primary loop of high-temperature gas-cooled reactor (HTR), the primary helium circulator (PHC) using electromagnetic levitation technology also provides an effective means for vibration control. Besides synchronous vibration produced by mass imbalance and sensor runout, double-frequency vibration produced by unbalanced magnetic pull (UMP) is serious in PHC engineering prototype (PHC-EP). In this paper, we firstly analyzed the mechanism of UMP and the multi-frequency vibration characteristics in combination with the PHC-EP. Then we put forward a distributed iterative learning control (ILC) algorithm and a parallel control scheme to suppress the periodic vibrations. Finally, we verified the methods by carrying out experimental researches on the active magnetic bearing (AMB) bench of PHC-EP. The results show that the methods put forward in this paper have significant control effect on the double-frequency vibration generated by UMP of the PHC-EP and provide theoretical and practical references for the PHC safe operation in HTR.
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Ma, Xibin, Zhangwei Chen, Huinong He, and Yugang Zhao. "Research on Control Technologies for a High-Precision Multi-Source Vibration Simulation System." Energies 11, no. 11 (October 29, 2018): 2956. http://dx.doi.org/10.3390/en11112956.
Повний текст джерелаАнотація:
Vehicles commonly suffer from the narrow-band noises and vibrations, usually a superposition of multiple sinusoidal signals, due to the excitations of engines, electrical motors, gear boxes, and other rotating mechanical parts. These excitations are transmitted to a reference point of some structure with certain transmission paths. The vibration signal measured at the reference point can be used for power system monitoring, fault diagnosis, modal analysis, noise analysis, etc. For convenience, researchers in a laboratory usually use shakers to generate expected narrow-band vibration signals acting on the vehicle structure reference points to simulate the vibration signals. However, there is a prominent difficulty in ensuring the amplitude and phase accuracy of each sub-frequency component simultaneously. In order to improve the accuracy of generating the expected vibration signal, this paper presents a multi-source vibration simulation control technology based on the tracking filter method. The main idea is to use the tracking filter to estimate the amplitude and phase of the target sub-frequency component accurately. Further, on the target sub-frequency, the drive signal of shakers is then corrected based on the amplitude and phase errors to achieve a more accurate target vibration signal. The amplitude and phase of each sub-frequency component in the excitation signal can be controlled independently. Compared with other Fast Fourier Transform (FFT)-based frequency domain analysis algorithms and numerical methods by solving the equations, the tracking filter method has a higher frequency resolution and higher accuracy. It can be easily realized in real time applications due to its simplicity. Finally, verification experiments are completed. The experimental results show that the multi-source vibration simulation control technology presented in this paper can achieve high-precision amplitude and phase on each sub-frequency component of the target vibration signals, which contain up to eight sub-frequency components.
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Shiota, Ryosuke, Tatsuya Furuki, Toshiki Hirogaki, and Eiichi Aoyama. "Investigation of Control Methods of Chatter Vibration Based on Analysis of End-Milling Chatter Mark." Advanced Materials Research 1136 (January 2016): 639–44. http://dx.doi.org/10.4028/www.scientific.net/amr.1136.639.
Повний текст джерелаАнотація:
Chatter vibration generated by coupling a work-piece, machine tools, and cutting tool is a serious problem for engineers. A regular pattern forms the machined surface when chatter vibration occurs. There must be a direct relationship between the relative displacement and machined surface. We propose a method for controlling chatter vibration of end-milling from a machined surface. Hammering tests were first carried out to determine the natural frequencies of machine tools and the tool system, which are likely to be the cause of vibration. We also propose a technique of applying reverse analysis to end-milling surfaces. The machined surface is assumed to include an essential index to easily control chatter vibration at the factory. We found that chatter vibration occurs near the frequency of the cutting tool, tool holder, and their coupling, not at the natural frequency, and the chatter vibration frequency can be calculated by analyzing the surface pattern and cutting conditions. Moreover, the proposed method was effective in analyzing chatter vibrations including more than two kinds of natural frequencies at the same time.
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Zhang, Laixi, Chenming Zhao, Feng Qian, Jaspreet Singh Dhupia, and Mingliang Wu. "A Variable Parameter Ambient Vibration Control Method Based on Quasi-Zero Stiffness in Robotic Drilling Systems." Machines 9, no. 3 (March 21, 2021): 67. http://dx.doi.org/10.3390/machines9030067.
Повний текст джерелаАнотація:
Vibrations in the aircraft assembly building will affect the precision of the robotic drilling system. A variable stiffness and damping semiactive vibration control mechanism with quasi-zero stiffness characteristics is developed. The quasi-zero stiffness of the mechanism is realized by the parallel connection of four vertically arranged bearing springs and two symmetrical horizontally arranged negative stiffness elements. Firstly, the quasi-zero stiffness parameters of the mechanism at the static equilibrium position are obtained through analysis. Secondly, the harmonic balance method is used to deal with the differential equations of motion. The effects of every parameter on the displacement transmissibility are analyzed, and the variable parameter control strategies are proposed. Finally, the system responses of the passive and semiactive vibration isolation mechanisms to the segmental variable frequency excitations are compared through virtual prototype experiments. The results show that the frequency range of vibration isolation is widened, and the stability of the vibration control system is effectively improved without resonance through the semiactive vibration control method. It is of innovative significance for ambient vibration control in robotic drilling systems.
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Zhou, Chun. "Control Lorenz System with Vibration Estimation with Averaging Method." Applied Mechanics and Materials 43 (December 2010): 36–39. http://dx.doi.org/10.4028/www.scientific.net/amm.43.36.
Повний текст джерелаАнотація:
The vibrational control theory stems from the well-known of stabilization of the upper unstable equilibrium position of the inverted pendulum having suspension point vibration along the vertical line with amplitude as small as desired and a frequency reason high. Chaotic phenomena have been found in many nonlinear systems including continuous time and discrete time. The chaotic systems are characterized by their extreme sensitivity to initial conditions, nonperiodic and boundary. The trajectories start even from close initial states will diverge from each other at an exponential rate as time goes. The vibrational control method was applied to Lorenz system. The effect of the control can be estimated with the APAZ method. It was showed that vibrational control brought the controlled Lorenz system to stable equilibrium with appropriate parameters. Numerical simulation demonstrated validity of the proposed method.
Дисертації з теми "Vibration frequency control method"
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Олійник, Ольга Юріївна. "Науково-методологічні засади віброчастотного контролю технологічних параметрів в умовах вібрації". Thesis, Національний технічний університет "Харківський політехнічний інститут", 2019. http://repository.kpi.kharkov.ua/handle/KhPI-Press/42234.
Повний текст джерелаАнотація:
Дисертація на здобуття наукового ступеня доктора технічних наук за спеціальністю 05.11.13 – прилади і методи контролю та визначення складу речовин» ‒ Державний вищий навчальний заклад «Український державний хіміко-технологічний університет», МОН України, Дніпро, 2019. Дисертація присвячена вирішенню науково-прикладної проблеми підвищення достовірності контролю технологічних параметрів (густини, в’язкості, зусилля (тиску)) в умовах вібрації за рахунок розроблення нових математичних моделей та методів визначення технологічних параметрів, застосування нових багатопараметричних віброчастотних перетворювачів з універсальною характеристикою та змінним співвідношенням сигнал-шум, розробки програмних засобів фільтрації зашумленої вимірювальної інформації з невідомими законами розподілу. Розроблено віброчастотний метод контролю та вимірювання густини, в’язкості, зусилля (тиску) газорідинних середовищ у виробничих умовах, який реалізується за допомогою віброчастотного вимірювального перетворювача з трубчатим, циліндричним резонатором у якості якого може використовуватись частина технологічного апарату, отримано математичні моделі амплітудно- частотних характеристик технологічних параметрів в апаратах різного типа конструкції. Розроблено теоретичні основи проектування неметалевих трубчатих проточних резонаторів з широкою сферою застосування. Розроблено багатофункціональний віброчастотний перетворювач для вимірювання густини, в’язкості, зусилля (тиску) з циліндричним резонатором, який має універсальну характеристику. Виконані дослідницькі роботи щодо попередньої ідентифікації законів розподілу, розроблено алгоритм фільтрації Калмана вимірювальної інформації з підвищеними завадами та структура багатопараметричної системи контролю технологічних параметрів з системою діагностики форми коливань резонатора; вдосконалено пристрій для ідентифікації активного стану оператора. Здійснені впровадження інженерних розробок дисертаційної роботи на провідних підприємствах Дніпра та за кордоном.Thesis for a degree of Doctor of Science (Technology), Specialty 05.11.13 – Instruments and Methods of Control and compounds` composition determination. – State Higher Educational Institution «Ukrainian State Chemical-Technological University», Ministry of Education and Science of Ukraine, Dnipro, 2019. The dissertation is devoted to solving the scientific and applied problem of increasing the reliability of the control of technological parameters (density, viscosity, force (pressure)) in a production environment through the development of new mathematical models and methods for determining technological parameters from the amplitude-frequency characteristics of the oscillatory environment of apparatuses, the use of new multiparameter vibration frequency converters with a universal characteristic and variable signal-to-noise ratio, as well as software development STV filtering noisy measurement information with unknown distribution laws. A vibration frequency method has been developed for monitoring and measuring the density, viscosity, force (pressure) of gas-liquid media under industrial conditions using a measuring transducer with a tubular, cylindrical resonator, mathematical models of the amplitude-frequency characteristics of technological parameters in devices of various designs are obtained. Theoretical foundations have been developed for the design of non-metallic tubular flow resonators with a wide scope. A multifunctional vibration frequency converter has been developed for measuring density, viscosity, force (pressure) with a cylindrical resonator, which has a universal characteristic. Research work on the identification of distribution laws has been completed, an Kalman filtering algorithm has been developed for measuring information with increased noise, and the structure of a multidimensional control system for technological parameters with a system for diagnosing the shape of resonator vibrations; improved device for identifying the active state of the operator. Implementation of engineering developments of the thesis was carried out at the leading enterprises of the Dnieper and abroad.
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Олійник, Ольга Юріївна. "Науково-методологічні засади віброчастотного контролю технологічних параметрів в умовах вібрації". Thesis, Національний технічний університет "Харківський політехнічний інститут", 2019. http://repository.kpi.kharkov.ua/handle/KhPI-Press/42235.
Повний текст джерелаАнотація:
Дисертація на здобуття наукового ступеня доктора технічних наук за спеціальністю 05.11.13 – «прилади і методи контролю та визначення складу речовин». ‒ Державний вищий навчальний заклад «Український державний хіміко-технологічний університет» Міністерства освіти і науки України, Дніпро, 2019. ‒ Національний технічний університет «Харківський політехнічний інститут» Міністерства освіти і науки України. Дисертація присвячена вирішенню науково-прикладної проблеми впідвищення достовірності контролю технологічних параметрів (густини, в’язкості, зусилля (тиску)) в умовах выбрації (технологічних апратах та обладнанні) за рахунок розроблення нових математичних моделей та методів визначення технологічних параметрів за амплітудно-частотними характеристиками коливального середовища апаратів, застосування нових багатопараметричних віброчастотних перетворювачів з універсальною характеристикою та змінним співвідношенням сигнал-шум, отриманих завдяки використанню автоколивальної системи зі стабільними характеристиками на першій гармоніці без застосування додаткових частотних фільтрів, розробки програмних засобів фільтрації зашумленої вимірювальної інформації з невідомими законами розподілу Проведено аналіз сучасних підходів до вимірювання технологічних параметрів (густини, в’язкості, зусилля (тиску) у виробничих умовах, що характеризуються підвищеною вібрацією, встановлені фактори, що вносять найсуттєвіший вплив на викривлення результатів вимірювання і створюють додаткові похибки, запропоновані методи компенсації впливу зазначених факторів. Існуючі методи неруйнівного контролю не задовольняють поставленим завданням, оскільки не дають можливості контролювати швидкоплинні технологічні процеси, а створення штучної коливальної системи не дає змогу контролювати амплітудно-частотні характеристики природної коливальної системи, що виникає в апараті. Вперше отримано математичні моделі статичних характеристик перетворення для розробленого віброчастотного методу вимірювання технологічних параметрів (густини, в’язкості, зусилля (тиску) в апаратах з природними коливальними системам для типу конструкції апаратів «труба», «циліндр» та для апаратів з барботажем та пульсацією середовища на основі гіпотез Сорокіна та Кірхгофа-Лява у виробничих умовах, що дозволяють визначати вказані параметри за амплітудно-частотними характеристиками природних коливальних систем у апаратах та зменшити динамічну похибку каналу вимірювання параметру більш ніж у 10 разів (0,012 %). Запропановано теоретичні основи проектування неметалевих трубчатих проточних резонаторів з широкою сферою застосування (вимірювання густини рідких і газоподібних середовищ, концентрації розчинів, температурного коефіцієнта, модуля пружності матеріалу) конструкція яких дозволяє підвищити точність вимірювання за рахунок регулювання активної частини резонатора з урахуванням жорсткості (піддатливості) типу кріплення і його розташування. Метод визначення частоти та форми коливань дозволяє 17% точніше визначати місця максимальних напружень між кріпленнями та одночасно зменшити вплив віброакустичний вплив трубопроводів на результат вимірювання амплитудно-частотних характеристик апарату.
Після розроблення і виготовлення дослідних зразків багатофункціонального віброчастотного давача для вимірювання густини, в’язкості, зусилля (тиску) з циліндричним резонатором було проведено серію експериментів для визначення густини та зусилля з використанням двіброчастотного методу методу Результати експериментів показали покращені метрологічні характеристики ЗВТ та дієвість методу. Результати проведених теоретичних і експериментальних досліджень впроваджено у практику таких підприємств і організацій: ТОВ «Укртехавіа» (Павлоград, Україна), «ММС Інтернешнл Белград» (Белград, Республіка Сербія); ВАТ «РПК «АДМІРАЛ»» (Дніпро, Україна), навчальний процесс Українського державного хіміко-технологічного університету, Дніпровського державного аграрно-економічного університету.Dissertation for the degree of Doctor of Sciences (Technology), Specialty 05.11.13 – «Instruments and Methods of Control and compounds` composition determination». ‒ State Higher Educational Institution «Ukrainian State Chemical Technology University» of the Ministry of Education and Science of Ukraine, Dnipro, 2019. ‒ National Technical University «Kharkiv Polytechnic Institute» of the Ministry of Education and Science of Ukraine. The dissertation is devoted to solving the scientific and applied problem of increasing the reliability of the control of technological parameters (density, viscosity, force (pressure)) in a production environment through the development of new mathematical models and methods for determining technological parameters from the amplitude-frequency characteristics of the oscillatory environment of apparatuses, the use of new multiparameter vibration frequency converters with a universal characteristic and variable signal-to-noise ratio, as well as software development STV filtering noisy measurement information with unknown distribution laws. A vibrational frequency method has been developed for monitoring and measuring the density, viscosity, force (pressure) of gas-liquid media under industrial conditions using a measuring transducer with a tubular, cylindrical resonator, mathematical models of the amplitude-frequency characteristics of technological parameters in devices of various designs are obtained. Theoretical foundations have been developed for the design of non-metallic tubular flow resonators with a wide scope. A multifunctional vibration frequency converter has been developed for measuring density, viscosity, force (pressure) with a cylindrical resonator, which has a universal characteristic. Research work on the identification of distribution laws has been completed, an Kalman filtering algorithm has been developed for measuring information with increased noise, and the structure of a multidimensional control system for technological parameters with a system for diagnosing the shape of resonator vibrations; improved device for identifying the active state of the operator. Implementation of engineering developments of the thesis was carried out at the leading enterprises of the Dnieper and abroad.
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Abdul, Muthalif Asan Gani. "Active control of high-frequency vibration." Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612225.
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Ho, C. "Nonlinear vibration control : a frequency domain approach." Thesis, University of Sheffield, 2014. http://etheses.whiterose.ac.uk/5157/.
Повний текст джерелаАнотація:
A vibration isolator, sometimes called an isolating mount, is the device situating between the vibration source and the sensitive system preventing the transmission of undesired disturbances. The performance is measured by the force or the displacement transmissibility, both functions of frequency. A good vibration isolation system has three main properties - a low resonant peak, a large isolation range and low transmissibility at non-resonant regions. Unfortunately, these characteristics cannot be achieved simultaneously by a simple linear vibration isolation system. The thesis addresses this problem for single-degree-of-freedom (sdof) vibration isolation systems by introducing nonlinear damping and stiffness devices into the system. First, theoretical studies were carried out to rigorously reveal the benefits of the proposed nonlinear vibration isolation systems over linear ones. Next, the performance of these nonlinear systems were analysed by simulations. Then, experimental studies were conducted to verify the theoretical and simulations results. Finally, a systematic approach was developed to design the parameters of the nonlinear damping and stiffness devices in order to satisfy specific vibration isolation requirements. Many vibration isolators can be modelled as a single-degree-of-freedom mass-spring-damper system. Many researchers have attempted to enhance the vibration isolation performance by designing springs with nonlinear stiffness. Others have focused on different types of damping nonlinearities. The new vibration isolation system proposed in the thesis combines both spring and damping nonlinearities in one system to exploit the advantages of both components while avoiding their undesirable effects. The theoretical properties of this proposed nonlinear vibration isolation system were analysed rigorously using the output frequency response function (OFRF) approach, a novel and unique method recently proposed at Sheeld. The stiffness nonlinearity is already a well researched area and can readily be realised in practice. Therefore, the implementation of the proposed nonlinear vibration suppression system focused on the realisation of the nonlinear damping component using commercially available magneto-rheological (MR) dampers which provide a damping force that is dependent on a control current. With feedback control, the force-velocity relationship of an MR damper can be shaped into a designed function. This implementation has been incorporated first in a vibration isolation system by simulation, then in a physical experimental rig which has a moving mass. The simulation and experimental data not only showed the successful realisation of a damping device with a particular nonlinear damping characteristic, but also confirmed the theoretical findings on the beneficial effects of nonlinear damping on a vibration isolation application. The final part of the thesis is devoted to the practical design of the proposed vibration isolation system. Given specific transmissibility requirements at certain critical frequencies, the values of the linear parameters are first designed, then the OFRF approach is applied to determine the nonlinear parameters. This pragmatic method simplifies the design of a complicated nonlinear system, which was traditionally difficult to work with, into a step-by-step guide and, therefore, has significant potential of industrial applications. The thesis has exploited the special effects of two nonlinear components on the performance of a passive sdof vibration isolation system. With the support of theoretical, simulation and experimental studies, the newly proposed configuration has shown substantial benefits to many vibration isolation problems. The simple yet effective design and implementation has significant implications for a wide range of engineering applications such as car suspension designs and building protection against earthquakes.
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Luo, Jian. "Frequency domain iterative tuning for active noise and vibration control." Thesis, University of Southampton, 2008. https://eprints.soton.ac.uk/63858/.
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In this thesis a new adaptive control method, called Iterative Tuning in the Frequency Domain (FD-IT), is proposed for Active Noise and Vibration Control (ANVC). This approach is a gradient based self-tuning method which completely relies on analysis of the frequency response of system dynamics and the spectrum of signals. The new method is based on a new gradient estimation theory in the frequency domain. In this theory the gradient of the output spectrum with respect to controller parameters is expressed with the frequency response of dynamics and the spectrum of signals. When the performance gradient with respect to controller parameters can be expressed as some function of the signals’ spectrum, it can be computed out completely in the frequency domain. Similar to audio compression, when the system’s signals contain few frequencies, the computation of performance gradient can be greatly simplified by making ”partial modelling” with respect to those frequencies. According to the proposed theory, the new iterative tuning method, i.e., FD-IT, is developed for ANVC problems with periodic disturbances. It can tune the feedback/feed-forward controllers simultaneously with one experiment per iteration except some extra experiments for initial tuning. It covers both Single Input Single Output (SISO) and Multiple Input Multiple Output (MIMO) systems. Furthermore, it can be extended to nonlinear systems as well. Some issues about the implementation of the iterative method are discussed. Through the comparison with some other popular active control methods in ANVC, the advantages of the new method, including: the flexibility in selecting controllers, the simplicity in control structure, and the convenience in implementation, are emphasized. The effectiveness and robustness of the proposed iterative tuning method are tested through simulated SISO and MIMO Linear Time Invariant (LTI) systems. Two simulated nonlinearities are used to illustrate the usefulness of the methods in nonlinear system as well. To show the practicability, the linear and nonlinear FD-ITs are implemented in an air-duct system with a PC-DSP based agent-architecture. All the results illustrate that FD-IT is an easy and effective approach to solve ANVC problems with periodic disturbances.
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Jeon, Byung Ho. "Proposed automobile steering wheel test method for vibration." Thesis, Brunel University, 2010. http://bura.brunel.ac.uk/handle/2438/4623.
Повний текст джерелаАнотація:
This thesis proposes a test method for evaluating the perceived vibration which occurs at the driver's hand in automotive steering wheel interface. The objective of the research was to develop frequency weightings for quantifying the human perception of steering wheel hand-arm vibration. Family of frequency weightings were developed from equal sensation curves obtained from the psychophysical laboratory experimental tests. The previous literature suggests that the only internationally standardised frequency weighting Wh is not accurate to predict human perception of steering wheel hand-arm vibration (Amman et. al, 2005) because Wh was developed originally for health effects, not for the human perception. In addition, most of the data in hand-arm vibration are based upon responses from male subjects (Neely and Burström, 2006) and previous studies based only on sinusoidal stimuli. Further, it has been continuously suggested by researchers (Gnanasekarna et al., 2006; Morioka and Griffin, 2006; Ajovalasit and Giacomin, 2009) that only one weighting is not optimal to estimate the human perception at all vibrational magnitudes. In order to address these problems, the investigation of the effect of gender, body mass and the signal type on the equal sensation curves has been performed by means of psychophysical laboratory experimental tests. The test participants were seated on a steering wheel simulator which consists of a rigid frame, a rigid steering wheel, an automobile seat, an electrodynamic shaker unit, a power amplifier and a signal generator. The category-ratio Borg CR10 scale procedure was used to quantify the perceived vibration intensity. A same test protocol was used for each test and for each test subject. The first experiment was conducted to investigate the effect of gender using sinusoidal vibration with 40 test participants (20 males and 20 females). The results suggested that the male participants provided generally lower subjective ratings than the female participants. The second experiment was conducted using band-limited random vibration to investigate the effect of signal type between sinusoidal and band-limited random vibration with 30 test participants (15 males and 15 females). The results suggested that the equal sensation curves obtained using random vibration were generally steeper and deeper in the shape of the curves than those obtained using sinusoidal vibration. These differences may be due to the characteristics of random vibration which produce generally higher crest factors than sinusoidal vibration. The third experiment was conducted to investigate the effect of physical body mass with 40 test participants (20 light and 20 heavy participants) using sinusoidal vibration. The results suggested that the light participants produced generally higher subjective ratings than the heavy participants. From the results it can be suggested that the equal sensation curves for steering wheel rotational vibration differ mainly due to differences of body size rather than differences of gender. The final experiments was conducted using real road signals to quantify the human subjective response to representative driving condition and to use the results to define the selection method for choosing the adequate frequency weightings for the road signals by means of correlation analysis. The final experiment was performed with 40 test participants (20 light and 20 heavy participants) using 21 real road signals obtained from the road tests. From the results the hypothesis was established that different amplitude groups may require different frequency weightings. Three amplitude groups were defined and the frequency weightings were selected for each amplitude group. The following findings can be drawn from the research: • the equal sensation curves suggest a nonlinear dependency on both the frequency and the amplitude. • the subjective responses obtained from band-limited random stimuli were steeper and the deeper in the shape of the equal sensation curves than those obtained using sinusoidal vibration stimuli. • females provided higher perceived intensity values than the males for the same physical stimulus at most frequencies. • light test participants provided higher perceived intensity than the heavy test participants for the same physical stimulus at most frequencies. • the equal sensation curves for steering wheel rotational vibration differ mainly due to differences in body size, rather than differences of gender. • at least three frequency weightings may be necessary to estimate the subjective intensity for road surface stimuli.
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Tehrani, Maryam Ghandchi. "Passive modification and active vibration control by receptance method." Thesis, University of Liverpool, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.441935.
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Rafique, Sajid. "Piezoelectric vibration energy harvesting and its application to vibration control." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/piezoelectric-vibration-energy-harvesting-and-its-application-to-vibration-control(d9edcedf-054e-4921-9ba3-5e015b9bbd8f).html.
Повний текст джерелаАнотація:
Vibration-based energy harvesting using piezoelectric materials have been investigated by several research groups with the aim of harvesting maximum energy and providing power to low-powered wireless electronic systems for their entire operational life. The electromechanical coupling effect introduced by the piezoelectric vibration energy harvesting (PVEH) mechanism presents modelling challenges. For this reason, there has been a continuous effort to develop different modelling techniques to describe the PVEH mechanism and its effects on the dynamics of the system. The overall aims of this thesis are twofold: (1) a thorough theoretical and experimental analysis of a PVEH beam or assembly of beams; (2) an in-depth analytical and experimental investigation of the novel concept of a dual function piezoelectric vibration energy harvester beam/tuned vibration absorber (PVEH/TVA) or 'electromechanical TVA' and its potential application to vibration control. The salient novel contributions of this thesis can be summarised as follows: (i) An in-depth experimental validation of a PVEH beam model based on the analytical modal analysis method (AMAM), with the investigations conducted over a wider frequency range than previously tested. (ii) The precise identification of the electrical loads that harvest maximum power and that induce maximum electrical damping. (iii) A thorough investigation of the influence of mechanical damping on PVEH beams. (iv) A procedure for the exact modelling of PVEH beams, and assemblies of such beams, using the dynamic stiffness matrix (DSM) method. (v) A procedure to enhance the power output from a PVEH beam through the application of a tip rotational restraint and the use of segmented electrodes. (vi) The theoretical basis for the novel concept of a dual function PVEH beam/TVA, and its realisation and experimental validation for a prototype device. A thorough experimental validation of a cantilever piezoelectric bimorph energy harvester without a tip mass is presented under random excitation. The study provided a deep insight into the effect of PVEH on the dynamics of the system for variations in electrical load. An alternative modelling technique to AMAM, based on the DSM, is introduced for PVEH beams. Unlike AMAM, the DSM is exact, since it is based on the exact solution to the bending wave equation. It also readily lends itself to the modelling of beams with different boundary conditions or assemblies of beams of different crosssections. AMAM is shown to converge to DSM if a sufficiency of modes is used. Finally, an in-depth theoretical and experimental investigation of a prototype PVEHbeam/TVA device is presented. This device comprises a pair of bimorphs shunted by R-L-C circuitry and can be used as a tuned mass damper (TMD) to attenuate a vibration mode of a generic structure. The optimal damping required by this TMD is generated by the PVEH effect of the bimorphs. Such a device combines the advantages of conventional mechanical and electrical TVAs, overcoming their relative disadvantages. The results demonstrate that the ideal degree of attenuation can be achieved by the proposed device through appropriate tuning of the circuitry, thereby presenting the prospect of a novel class of 'electromechanical' tuned vibration absorbers.
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Jamal, Ahmad Mohammad Hafiz Fazl Elahi. "An automated frequency tracking method for structural health monitoring using vibration data." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/42779.
Повний текст джерелаАнотація:
The process of extracting modal parameters using vibration response data from aerospace, civil and mechanical structures is well-established and many techniques exist to cater for the availability of spatial and temporal data. These techniques need extensive interaction with an expert user to guide them towards an acceptable set of solutions and are not adequate for structural health monitoring which fundamentally requires an automated process. Research into automated algorithms for the extraction and tracking of modal parameters started to gather momentum recently due to advances in technology and computing. Currently there is a lack of automated procedures due to the difficulty of replacing the interactions of an expert user with software algorithms and those that have been proposed have not yet been widely adopted. In this thesis, we propose a new automated method to track resonant frequencies for the purpose of detecting change. The method uses wavelet decomposition, principal component analysis, spectrum estimation and adaptive filtering. The aim is to identify resonant frequencies and then to monitor their magnitudes and frequencies in an automated fashion without user interaction for the detection of change in performance. The proposed method is validated on several benchmark problems widely studied in the literature, one simulated and four experimental. It is shown that using the new method it is possible to detect all the data cases for these benchmark structures because they produce changes in the resonant frequencies or in their magnitudes. The new method is also compared with an existing automated method called frequency domain decomposition (FDD) and it is shown that for the benchmark problems considered in this thesis the frequency tracking performance of the new method is superior.
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Hwang, HaDong. "Extension de la méthode SmEdA par la prise en compte des matériaux dissipatifs en moyennes fréquences." Thesis, Lyon, INSA, 2015. http://www.theses.fr/2015ISAL0048/document.
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Le projet CLIC (City Lightweight Innovative Cab) dans lequel s’inscrit cette thèse de doctorat vise à développer une cabine de camion allégée sans dégrader les performances vibratoires et acoustiques. Pour cela il est nécessaire d’établir dans un premier temps un modèle de prédiction vibroacoustique du système couplé structure/espace intérieur incluant l’influence des matériaux dissipatifs (amortissement ou absorption) dans le domaine des moyennes fréquences. Les méthodes basées sur les éléments finis et les approches statistiques les plus couramment utilisées étant peu adaptées pour ce domaine de fréquence (coût de calcul important, méthodes peu flexibles), nous utiliserons le formalisme de la méthode SmEdA (Statistical modal Energy distribution Analysis). L’objectif principal de cette thèse de doctorat est dès lors, d’étendre cette méthode à la prise en compte de l’effet d’amortissement induit par des matériaux dissipatifs. La méthodologie se divise en trois étapes: 1. Les modèles équivalents des matériaux dissipatifs sont établis: (1) un modèle de plaque équivalent pour décrire la plaque amortie par un ou plusieurs patch(s) viscoélastique(s) et (2) un modèle de fluide équivalent pour décrire un matériau poreux agissant dans la cavité. 2. Chaque sous-système amorti est modélisé par éléments finis. Les méthodes MSE (Modal Strain Energy) et MSKE (Modal Strain Kinetic Energy) sont ensuite utilisées pour estimer les facteurs de perte modaux de chaque sous-système. 3. Le calcul SmEdA est effectué sur le système couplé en prenant en compte les facteurs de pertes modaux de chaque sous-système estimés dans la deuxième étape. Le point d’excitation est appliquée à la plaque, en supposant la force stationnaire et large bande. Afin de valider la méthodologie proposée un cas semi-complexe composé d’une plaque rectangulaire couplée à une cavité parallélépipédique est considéré. Ce système peut être utilisé pour étudier l’interaction vibroacoustique entre la structure de la cabine et l’intérieur de l’habitacle. Deux cas d’amortissement sont étudiés pour le système semi-complexe plaque-cavité: (1) un cas où la plaque est amortie avec un (ou plusieurs) patch(s) viscoélastique(s) et (2) un cas où un matériau poreux est placé dans la cavité. Le problème vibroacoustique est pour chaque cas modélisé suivant les trois étapes proposées et analyses dans le formalisme de la méthode SmEdA. Les résultats sont ensuite comparés au cas de référence (sans matériau dissipatif). La dernière partie de la thèse porte sur la validation expérimentale pour chaque cas test de la méthodologie numérique proposée. a mobilité d’éntrée, la puissance injectée et les énergies des sous-systèmes sont comparées aux prédictions numériques. Enfin les facteurs de pertes modaux des sous-systèmes estimés par les méthodes MSE et MSKE sont comparés aux résultats expérimentaux obtenus par la méthode d’analyse modale à haute résolution (méthode ESPRIT)The project CLIC (City Lightweight Innovative Cab) aims to develop a lighter-weighted truck that maintains NVH performances of the initial design. This PhD research is then to establish a vibroacoustic prediction model of a complex structure-bounded fluid system (cabin structure coupled to cabin space) including dissipative treatments (damping or absorbing materials) for the mid-frequency domain. Since most commonly used element based and statistical methods are not suitable for this frequency domain, a proper prediction tool, which should be flexible in modeling capabilities and feasible in computational cost, must be implemented. The SmEdA (Statistical modal Energy distribution Analysis) method is considered in this thesis to comply with these requirements. The main objective of this research is to extend this method for taking account of the damping effect induced by dissipative materials. Development and validation of the methodology are carried out. 1. Dissipative materials are represented by simplified equivalent models: (1) the equivalent single layer model for describing the plate covered with a viscoelastic layer and (2) the equivalent fluid model for describing a porous material into the cavity. 2. Each subsystem including the equivalent models of the dissipative materials is modeled with FEM(Finite Element Model). The FE matrices including the energy dissipation are then computed. The MSE (Modal Strain Energy) and MSKE (Modal Strain Kinetic Energy) methods are used to estimate the modal damping loss factor of each subsystem mode. 3. The SmEdA calculation is performed on a whole system considering the modal damping loss factors estimated in the second step for each subsystem. The power is injected into the plate at a localized point by the stationary white noise force and subsequently, the SmEdA parameters are computed. To validate the proposed methodology, laboratory test cases of the structure-fluid problem composed of a rectangular plate coupled to a parallelepipedic cavity are considered. Such system can be used to study the vibroacoustic interaction between structure and fluid. Two damped test cases of the plate-cavity system are studied: (1) a system with a viscoelastic damping pad on the plate and (2) a system with a composite fibre in the cavity. The damped test cases are modeled following the three steps and are analyzed in the framework of SmEdA. The results are then compared to the original case with no damping treatment. The last part of the thesis presents an experimental validation of the numerical computation results on each test case. Measured quantities such as input mobility, injected power and subsystem energies are compared to the numerical predictions. The modal damping loss factors of the damped subsystems estimated with MSE and MSKE methods are compared to the experimental results estimated by a high-resolution modal analysis method (ESPRIT method)
Книги з теми "Vibration frequency control method"
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Pantling, Carey M. Active vibration control method for space truss using piezoelectric actuators and finite elements. Monterey, Calif: Naval Postgraduate School, 1999.
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Szabo, J. P. A forced vibration non-resonant method for the determination of complex modulus in the audio frequency range. Dartmouth, N.S: Defence Research Establishment Atlantic, 1992.
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Ontario. Ministry of Natural Resources. Regional flood frequency analysis for Ontario streams: Single station analysis and index method. Toronto: Queen's Printer for Ontario, 1985.
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International Meeting on Low Frequency Noise and Vibration and Its Control (11 2004 Maastricht, Netherlands). Proceedings Low Frequency 2004: 11th International Meeting on Low Frequency Noise and Vibration and its Control, Maastricht The Netherlands 30 August - 1st September 2004. Brentwood, Essex: Multi-Science, 2004.
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Dilsavor, Ronald Louis. Analysis of modified SMI method for adaptive array weight control. Washington, DC: National Aeronautics and Space Administration, 1989.
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Kaiser, W. Sound and vibration from heavy military vehicles: Investigations of frequency assignment and wave spreading with respect to monitoring under disarmanent treaties. Hagen: ISL-Verlag, 1998.
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Schuring, J. Design and experimental verification of a calculation method for frequency response analysis of digital control systems in a continuous environment. Amsterdam: National Aerospace Laboratory, 1985.
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Rudolf, Rabenstein, ed. Digital sound synthesis by physical modeling using the functional transformation method. New York: Kluwer Academic/Plenum Publishers, 2003.
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Phan, Minh Q. Stochastic prediction of vibration levels in the presence of modeling uncertainties: Final report, NASA grant NAG1-1698. [Princeton, N.J.]: Princeton University, Dept. of Mechanical and Aerospace Engineering, 1997.
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ZnO bao mo zhi bei ji qi guang, dian xing neng yan jiu. Shanghai Shi: Shanghai da xue chu ban she, 2010.
Знайти повний текст джерелаЧастини книг з теми "Vibration frequency control method"
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Shilin, Aleksandr N., Aleksey A. Shilin, Mikhail N. Sedov, and Mohanad N. Mustafa. "Intelligent Low-Frequency Electromechanical Vibration Transducers." In Studies in Systems, Decision and Control, 327–37. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-99759-9_27.
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Preumont, A. "Analysis and Synthesis in the Frequency Domain." In Vibration Control of Active Structures, 215–46. Dordrecht: Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-94-007-2033-6_10.
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Preumont, André. "Analysis and Synthesis in the Frequency Domain." In Vibration Control of Active Structures, 227–57. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-72296-2_10.
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Li, Aiqun. "Basic Principle of Frequency Modulation Vibration Control." In Vibration Control for Building Structures, 47–61. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-40790-2_3.
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Preumont, André. "Analysis and synthesis in the frequency domain." In Vibration Control of Active Structures, 118–44. Dordrecht: Springer Netherlands, 1997. http://dx.doi.org/10.1007/978-94-011-5654-7_7.
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Li, Aiqun. "Vibration Control Design Method of Building Structure." In Vibration Control for Building Structures, 483–523. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-40790-2_12.
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Du, Chunling, and Chee Khiang Pang. "High-Frequency Vibration Control Using PZT Active Damping." In Multi-Stage Actuation Systems and Control, 133–54. First edition. | Boca Raton, FL : CRC Press/Taylor & Francis: CRC Press, 2018. http://dx.doi.org/10.1201/9781351062183-10.
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Yem, Vibol, Ryuta Okazaki, and Hiroyuki Kajimoto. "Low-Frequency Vibration Actuator Using a DC Motor." In Haptics: Perception, Devices, Control, and Applications, 317–25. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-42324-1_31.
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Li, Aiqun. "Intelligent Optimization Method of Building Structure Vibration Control." In Vibration Control for Building Structures, 525–56. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-40790-2_13.
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Singh, Aabhas, Matt Allen, and Washington J. DeLima. "Multi–input Multi–output Active Vibration Control for High Frequency Random Vibration." In Special Topics in Structural Dynamics, Volume 5, 37–47. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-75390-4_3.
Повний текст джерелаТези доповідей конференцій з теми "Vibration frequency control method"
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Olgac, N., and Chang Huang. "A new method for multiple frequency vibration absorption." In Proceedings of 2000 American Control Conference (ACC 2000). IEEE, 2000. http://dx.doi.org/10.1109/acc.2000.879571.
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Zhang Jianying and Liu Tun. "Component synthesis active vibration suppression method in frequency domain." In 2008 Chinese Control Conference (CCC). IEEE, 2008. http://dx.doi.org/10.1109/chicc.2008.4605134.
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Jianhai, Zhang, Han Yingchun, Li Lianzhou, Liu Jun, and Che Bin. "An improved EMD time-frequency analysis method for rocket vibration signal." In 2014 IEEE Chinese Guidance, Navigation and Control Conference (CGNCC). IEEE, 2014. http://dx.doi.org/10.1109/cgncc.2014.7007461.
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Pan, Nan, and Jingshu Yang. "Bearing fault vibration diagnosis using frequency domain semi-blind extraction method." In 2015 7th International Conference on Modelling, Identification and Control (ICMIC). IEEE, 2015. http://dx.doi.org/10.1109/icmic.2015.7409374.
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Xu, Wen-Long, Guo-Qing Gong, Hong-Hai Li, and Kun-Li Wen. "The Study of High Frequency Vibration in Complex Coupling Structure via GM(h,N) Method." In Modelling, Identification and Control. Calgary,AB,Canada: ACTAPRESS, 2013. http://dx.doi.org/10.2316/p.2013.801-014.
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Seto, Kazuto, Yoshihiro Toba, and Fumio Doi. "Active Vibration Control of a Triple Flexible Structures Combined With Actuators." In ASME 1995 Design Engineering Technical Conferences collocated with the ASME 1995 15th International Computers in Engineering Conference and the ASME 1995 9th Annual Engineering Database Symposium. American Society of Mechanical Engineers, 1995. http://dx.doi.org/10.1115/detc1995-0598.
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Abstract In order to realize living comfort of tall buildings by reducing the vibration of higher floors by strong winds, this paper proposes a new method of vibration control for flexible structures with a large scale. The higher a tall building the lower its natural frequency. Since obtaining sufficient force to control the lower frequency vibrations of tall buildings is a difficult task, controlling the vibration of ultra-tall buildings using active dynamic absorbers is nearly impossible. This problem can be overcome by placing actuators between a pair of two or three ultra-tall buildings and using the vibrational force of each building to offset the vibrational movement of its paired mate. Therefore, it is able to obtain enough control force under the low frequency when the proposed method is used. In this paper, a reduced-order model expressed by 2DOF system under taking into consideration for preventing spillover instability is applied to control each flexible structure. The LQ control theory is applied to the design of such a control system. The effectiveness of this method is demonstrated theoretically as well as experimentally.
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Chen, Jiandong, Yue Yang, Xiaoyi Pan, Zhanghai Wang, Zili Zhang, and Huiliang Ge. "A New Measurement Method for Resonance Frequency of Fiber Optic Interferometric Vibration Detector." In 2019 4th International Conference on Measurement, Information and Control (ICMIC). IEEE, 2019. http://dx.doi.org/10.1109/icmic48233.2019.9068532.
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Korman, J. C. "A Progress Report on Manufacturing Methods and Technology for Production of High-Stability, Vibration-Resistant Quartz Crystal Units." In 39th Annual Symposium on Frequency Control. IEEE, 1985. http://dx.doi.org/10.1109/freq.1985.200865.
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Xu, Shidong. "Finite Frequency Robust Vibration Control of Flexible-Rigid Coupled Spacecraft." In ASME 2020 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/imece2020-23125.
Повний текст джерелаАнотація:
Abstract This paper is concerned with robust vibration control of flexible-rigid coupling spacecraft with finite frequency constraint. Considering that the major vibration energy of flexible structure is induced by the vibration modes located in a specific frequency range, the dynamics of the considered spacecraft are derived as a system with given vibration modes. A novel robust finite frequency controller is proposed by using output feedback method, which focuses on suppressing the vibration modes in given frequency region. Compared with the classic entire frequency controller, the newly proposed controller can achieve better vibration attenuation performance. Finally, illustrative simulation results are provided to demonstrate the effectiveness and superiority of our proposed control method.
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Weidong Jiao. "A method for time-frequency feature extraction from vibration signal based on Hilbert-Huang Transform." In 2008 7th World Congress on Intelligent Control and Automation. IEEE, 2008. http://dx.doi.org/10.1109/wcica.2008.4594607.
Повний текст джерелаЗвіти організацій з теми "Vibration frequency control method"
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Liang, BiYan, BiYan Liang, and Jian Wang. A Meta Analysis of the Efficacy of Tonic Method in Traditional Chinese Medicine for AIDS Immunological Nonresponses. INPLASY - International Platform of Registered Systematic Review and Meta-analysis Protocols, April 2022. http://dx.doi.org/10.37766/inplasy2022.4.0077.
Повний текст джерелаАнотація:
Review question / Objective: To evaluate the efficacy of tonic method in treating AIDS immunological nonresponses. Eligibility criteria: ①Study type: RCT based on tonic method in TCM for AIDS INRs. The language was limited to Chinese and English. ②The research object: HIV/AIDS patients with any disease stage; the intervention objects were adults with no gender restrictions. ③Intervention measures: The treatment group was treated with tonic prescriptions combined with ART, including four types of prescriptions for nourishing qi, nourishing blood, nourishing yin, or nourishing yang; the dosage, frequency, and method were not limited. The control group was treated with ART or mock agent and placebo. ④Outcome indicators: The observation indicators reported in the included studies should include at least one of the following indicators: 1) Effective rate of immune function reconstruction: formulated in accordance with "AIDS (Adult) Chinese Medicine Diagnosis and Treatment Program" (2016 Edition) , effective: CD4 + T lymphocyte counts increased by ≥ 50 cells/l or ≥ 30%, invalid: CD4+ T lymphocyte counts decreased by ≥ 50 cells/l or ≥ 30%; total effective rate = effective number/total number; 2) CD4+T lymphocyte counts level.
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Galili, Naftali, Roger P. Rohrbach, Itzhak Shmulevich, Yoram Fuchs, and Giora Zauberman. Non-Destructive Quality Sensing of High-Value Agricultural Commodities Through Response Analysis. United States Department of Agriculture, October 1994. http://dx.doi.org/10.32747/1994.7570549.bard.
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The objectives of this project were to develop nondestructive methods for detection of internal properties and firmness of fruits and vegetables. One method was based on a soft piezoelectric film transducer developed in the Technion, for analysis of fruit response to low-energy excitation. The second method was a dot-matrix piezoelectric transducer of North Carolina State University, developed for contact-pressure analysis of fruit during impact. Two research teams, one in Israel and the other in North Carolina, coordinated their research effort according to the specific objectives of the project, to develop and apply the two complementary methods for quality control of agricultural commodities. In Israel: An improved firmness testing system was developed and tested with tropical fruits. The new system included an instrumented fruit-bed of three flexible piezoelectric sensors and miniature electromagnetic hammers, which served as fruit support and low-energy excitation device, respectively. Resonant frequencies were detected for determination of firmness index. Two new acoustic parameters were developed for evaluation of fruit firmness and maturity: a dumping-ratio and a centeroid of the frequency response. Experiments were performed with avocado and mango fruits. The internal damping ratio, which may indicate fruit ripeness, increased monotonically with time, while resonant frequencies and firmness indices decreased with time. Fruit samples were tested daily by destructive penetration test. A fairy high correlation was found in tropical fruits between the penetration force and the new acoustic parameters; a lower correlation was found between this parameter and the conventional firmness index. Improved table-top firmness testing units, Firmalon, with data-logging system and on-line data analysis capacity have been built. The new device was used for the full-scale experiments in the next two years, ahead of the original program and BARD timetable. Close cooperation was initiated with local industry for development of both off-line and on-line sorting and quality control of more agricultural commodities. Firmalon units were produced and operated in major packaging houses in Israel, Belgium and Washington State, on mango and avocado, apples, pears, tomatoes, melons and some other fruits, to gain field experience with the new method. The accumulated experimental data from all these activities is still analyzed, to improve firmness sorting criteria and shelf-life predicting curves for the different fruits. The test program in commercial CA storage facilities in Washington State included seven apple varieties: Fuji, Braeburn, Gala, Granny Smith, Jonagold, Red Delicious, Golden Delicious, and D'Anjou pear variety. FI master-curves could be developed for the Braeburn, Gala, Granny Smith and Jonagold apples. These fruits showed a steady ripening process during the test period. Yet, more work should be conducted to reduce scattering of the data and to determine the confidence limits of the method. Nearly constant FI in Red Delicious and the fluctuations of FI in the Fuji apples should be re-examined. Three sets of experiment were performed with Flandria tomatoes. Despite the complex structure of the tomatoes, the acoustic method could be used for firmness evaluation and to follow the ripening evolution with time. Close agreement was achieved between the auction expert evaluation and that of the nondestructive acoustic test, where firmness index of 4.0 and more indicated grade-A tomatoes. More work is performed to refine the sorting algorithm and to develop a general ripening scale for automatic grading of tomatoes for the fresh fruit market. Galia melons were tested in Israel, in simulated export conditions. It was concluded that the Firmalon is capable of detecting the ripening of melons nondestructively, and sorted out the defective fruits from the export shipment. The cooperation with local industry resulted in development of automatic on-line prototype of the acoustic sensor, that may be incorporated with the export quality control system for melons. More interesting is the development of the remote firmness sensing method for sealed CA cool-rooms, where most of the full-year fruit yield in stored for off-season consumption. Hundreds of ripening monitor systems have been installed in major fruit storage facilities, and being evaluated now by the consumers. If successful, the new method may cause a major change in long-term fruit storage technology. More uses of the acoustic test method have been considered, for monitoring fruit maturity and harvest time, testing fruit samples or each individual fruit when entering the storage facilities, packaging house and auction, and in the supermarket. This approach may result in a full line of equipment for nondestructive quality control of fruits and vegetables, from the orchard or the greenhouse, through the entire sorting, grading and storage process, up to the consumer table. The developed technology offers a tool to determine the maturity of the fruits nondestructively by monitoring their acoustic response to mechanical impulse on the tree. A special device was built and preliminary tested in mango fruit. More development is needed to develop a portable, hand operated sensing method for this purpose. In North Carolina: Analysis method based on an Auto-Regressive (AR) model was developed for detecting the first resonance of fruit from their response to mechanical impulse. The algorithm included a routine that detects the first resonant frequency from as many sensors as possible. Experiments on Red Delicious apples were performed and their firmness was determined. The AR method allowed the detection of the first resonance. The method could be fast enough to be utilized in a real time sorting machine. Yet, further study is needed to look for improvement of the search algorithm of the methods. An impact contact-pressure measurement system and Neural Network (NN) identification method were developed to investigate the relationships between surface pressure distributions on selected fruits and their respective internal textural qualities. A piezoelectric dot-matrix pressure transducer was developed for the purpose of acquiring time-sampled pressure profiles during impact. The acquired data was transferred into a personal computer and accurate visualization of animated data were presented. Preliminary test with 10 apples has been performed. Measurement were made by the contact-pressure transducer in two different positions. Complementary measurements were made on the same apples by using the Firmalon and Magness Taylor (MT) testers. Three-layer neural network was designed. 2/3 of the contact-pressure data were used as training input data and corresponding MT data as training target data. The remaining data were used as NN checking data. Six samples randomly chosen from the ten measured samples and their corresponding Firmalon values were used as the NN training and target data, respectively. The remaining four samples' data were input to the NN. The NN results consistent with the Firmness Tester values. So, if more training data would be obtained, the output should be more accurate. In addition, the Firmness Tester values do not consistent with MT firmness tester values. The NN method developed in this study appears to be a useful tool to emulate the MT Firmness test results without destroying the apple samples. To get more accurate estimation of MT firmness a much larger training data set is required. When the larger sensitive area of the pressure sensor being developed in this project becomes available, the entire contact 'shape' will provide additional information and the neural network results would be more accurate. It has been shown that the impact information can be utilized in the determination of internal quality factors of fruit. Until now,
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Lafrancois, Toben, Mark Hove, and Jay Glase. Zebra mussel (Dreissena polymorpha) distribution in Apostle Islands National Lakeshore: SCUBA-based search and removal efforts: 2019–2020. National Park Service, May 2022. http://dx.doi.org/10.36967/nrr-2293376.
Повний текст джерелаАнотація:
Invasive zebra mussels (Dreissena polymorpha) were first observed in situ at Apostle Islands National Lakeshore (APIS) in 2015. This report builds on 2018 SCUBA surveys and Environmental Protection Agency (EPA) veliger sampling to: 1) determine whether shoals on APIS borders act as sentinel sites to corroborate veliger drift hypotheses about invasion pathways, 2) evaluate ongoing hand-removal of zebra mussels from easily identified structures, and 3) continue efforts to assess native unionid mussel populations, particularly where zebra mussels are also present. Standard catch per unit effort survey methods by SCUBA teams were used to determine the distribution and relative abundance of zebra or quagga mussels (dreissenids) and native mussels (unionids). Zebra mussels were present at densities between 3 and 42 n/diver/hr (number of mussels per diver per hour), while native unionids were present at densities between 5 and 72 n/diver/hr. Shoal surveys (Eagle Island shoal, Sand Island shoal, York Island shoal, Bear Island shoal, Oak Island shoal, and Gull Island shoal) showed zebra mussels were more abundant on the west side of APIS and absent on the easternmost shoal (Gull Island), corroborating veliger work by the EPA that suggested drift from the Twin Ports of Duluth, Minnesota, and Superior, Wisconsin, is one pathway of invasion. Our results support the use of shallow shoals along the periphery of the park as sentinel sites gauging zebra mussel immigration and population dynamics. Zebra mussel densities in the central islands showed no obvious spatial pattern, and this survey cannot determine whether currents or human transport (or both) are invasion vectors. Given the mussels’ continued presence at heavily used mooring areas and docks where there are no zebra mussels on nearby natural features (e.g., Rocky Island dock, Stockton Island mooring areas), our findings are consistent with multiple invasion pathways (drift from the Twin Ports and anthropogenic sources at mooring areas). SCUBA search and removal of zebra mussels from docks was confirmed to be an effective method for significantly lowering the risk of zebra mussels reproducing and dispersing from these locations. We caution that this work is being done on what look like initial invasions at low densities. Repeated removal of zebra mussels by divers reduced numbers to zero at some sites after one year (South Twin docks, Stockton Island NPS docks, and the Ottawa wreck) or decreased numbers by an order of magnitude (Rocky Island docks). Dreissenid densities were more persistent on the Sevona wreck and longer-term work is required to evaluate removal versus recruitment (local and/or veliger drift). Given the size of the wreck, we have tracked detailed survey maps to guide future efforts. Zebra mussels were again observed attached to native mussels near Stockton Island and South Twin Island. Their continued presence on sensitive native species is of concern. Native unionid mussels were more widely distributed in the park than previously known, with new beds found near Oak and Basswood Islands. The work reported here will form the basis for continued efforts to determine the optimal frequency of zebra mussel removal for effective control, as well as evaluate impacts on native species.
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Vehicle Surge Reduction Technology during Towing in Parallel HEV Pickup Truck. SAE International, March 2022. http://dx.doi.org/10.4271/2022-01-0613.
Повний текст джерелаАнотація:
This paper proposes a technology to reduce vehicle surge during towing that utilizes motors and shifting to help ensure comfort in a parallel HEV pickup truck. Hybridization is one way to reduce fuel consumption and help realize carbon neutrality. Parallel HEVs have advantages in the towing, hauling, and high-load operations often carried out by pickup trucks, compared to other HEV systems. Since the engine, motor, torque converter, and transmission are connected in series in a parallel HEV, vehicle surge may occur when the lockup clutch is engaged to enhance fuel efficiency, similar to conventional powertrains. Vehicle surge is a low-frequency vibration phenomenon. In general, the source is torque fluctuation caused by the engine and tires, with amplification provided by first-order torsional driveline resonance, power plant resonance, suspension resonance, and cabin resonance. This vibration is amplified more during towing. Therefore, this paper proposes two surge reduction technologies to help achieve fuel efficiency and surge at the same time during towing. One technology is a gear shift control that avoids engine operating zones where two or more resonance frequencies coincide, which is realized by changing the equivalent inertia via appropriate gear selection. The second technology is an anti-vibration control, which makes effective use of the hybrid system motors by adding motor torque to suppress the relative displacement between the driveline and the tires.