Academic literature on the topic 'Frequency response diagram'
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Journal articles on the topic "Frequency response diagram"
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Mugarra, Asier, Hernan Mayora, Jose Manuel Guerrero, and Carlos A. Platero. "Frequency Response Analysis (FRA) Fault Diagram Assessment Method." IEEE Transactions on Industry Applications 58, no. 1 (January 2022): 336–44. http://dx.doi.org/10.1109/tia.2021.3131425.
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Vodopyanov, M. A., K. A. Menzorov, V. V. Davydov, and V. Yu Rud. "Method for reducing phase fluctuations of a precision frequency response meter for microwave quantum generators." Journal of Physics: Conference Series 2086, no. 1 (December 1, 2021): 012071. http://dx.doi.org/10.1088/1742-6596/2086/1/012071.
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Abstract The principle of operation of the device for measuring frequency characteristics is considered. Block diagram of a device for measuring the frequency characteristics of a digital frequency comparator with correlation quadrature processing and description of their components is illustrated. The block diagram of the frequency multiplier is given. The accuracy characteristics of the developed meter design are evaluated. They are compared with the characteristics of previously used devices. The Improve accuracy characteristics and increased stability of operation were found.
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Graetzel, Chauncey F., Bradley J. Nelson, and Steven N. Fry. "Frequency response of lift control in Drosophila." Journal of The Royal Society Interface 7, no. 52 (May 12, 2010): 1603–16. http://dx.doi.org/10.1098/rsif.2010.0040.
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The flight control responses of the fruitfly represent a powerful model system to explore neuromotor control mechanisms, whose system level control properties can be suitably characterized with a frequency response analysis. We characterized the lift response dynamics of tethered flying Drosophila in presence of vertically oscillating visual patterns, whose oscillation frequency we varied between 0.1 and 13 Hz. We justified these measurements by showing that the amplitude gain and phase response is invariant to the pattern oscillation amplitude and spatial frequency within a broad dynamic range. We also showed that lift responses are largely linear and time invariant (LTI), a necessary condition for a meaningful analysis of frequency responses and a remarkable characteristic given its nonlinear constituents. The flies responded to increasing oscillation frequencies with a roughly linear decrease in response gain, which dropped to background noise levels at about 6 Hz. The phase lag decreased linearly, consistent with a constant reaction delay of 75 ms. Next, we estimated the free-flight response of the fly to generate a Bode diagram of the lift response. The limitation of lift control to frequencies below 6 Hz is explained with inertial body damping, which becomes dominant at higher frequencies. Our work provides the detailed background and techniques that allow optomotor lift responses of Drosophila to be measured with comparatively simple, affordable and commercially available techniques. The identification of an LTI, pattern velocity dependent, lift control strategy is relevant to the underlying motion computation mechanisms and serves a broader understanding of insects' flight control strategies. The relevance and potential pitfalls of applying system identification techniques in tethered preparations is discussed.
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Lee, Pedro J., John P. Vítkovský, Martin F. Lambert, Angus R. Simpson, and James A. Liggett. "Discrete Blockage Detection in Pipelines Using the Frequency Response Diagram: Numerical Study." Journal of Hydraulic Engineering 134, no. 5 (May 2008): 658–63. http://dx.doi.org/10.1061/(asce)0733-9429(2008)134:5(658).
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BILLINGS, S. A., and O. M. BOAGHE. "THE RESPONSE SPECTRUM MAP, A FREQUENCY DOMAIN EQUIVALENT TO THE BIFURCATION DIAGRAM." International Journal of Bifurcation and Chaos 11, no. 07 (July 2001): 1961–75. http://dx.doi.org/10.1142/s0218127401003164.
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The Response Spectrum Map (RSM) is introduced as a frequency domain equivalent to the Bifurcation Diagram. The RSM is a map of the energy distribution of a system in the frequency domain, where subharmonics, superharmonics and chaos generation can be revealed. The RSM is used in this paper to qualitatively analyze and detect various dynamical states exhibited by a nonlinear system.
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Zhou, Shengxi, Junyi Cao, Grzegorz Litak, and Jing Lin. "Numerical analysis and experimental verification of broadband tristable energy harvesters." tm - Technisches Messen 85, no. 9 (September 25, 2018): 521–32. http://dx.doi.org/10.1515/teme-2017-0076.
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Abstract This paper analyzes the dynamic characteristics of broadband tristable energy harvesters to reveal their response mechanism via a bifurcation diagram, the corresponding frequency spectral analysis and the phase portrait topology. The bifurcation diagram of response voltages shows that tristable energy harvesters orderly undergoes singly periodic intrawell oscillation, singly periodic interwell oscillation, triply periodic interwell oscillation, singly periodic interwell oscillation, double-periodic interwell oscillation, chaotic oscillation, singly periodic interwell oscillation, multi-period oscillation, and finally enters into chaotic oscillation range, as the increase of the excitation amplitude. The frequency spectral analysis demonstrates that sub-harmonics and super-harmonics numerically and experimentally exist in the response voltages of tristable energy harvesters. In addition, it is found that both the first harmonic and the third harmonic are main frequency components in the response voltages.
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Liu, Jie, Chengye Wang, and Wenchao Wu. "Research on Meshing Stiffness and Vibration Response of Pitting Fault Gears with Different Degrees." International Journal of Rotating Machinery 2020 (February 1, 2020): 1–7. http://dx.doi.org/10.1155/2020/4176430.
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In order to study the influence of pitting on meshing stiffness, the normal distribution function is used to simulate the pitting location of pitting gear, and the potential energy method is used to analyze the influence of pitting on meshing stiffness. At the same time, the meshing stiffness of pitting gears with different degrees is analyzed by finite element method, and the validity of the calculation results with potential energy method is verified. On the basis of meshing stiffness, the dynamic model of gear system is established, and the vibration response of pitting gear system with different degrees is analyzed. The results show that with the increase of pitting area, the meshing stiffness decreases; the closer the meshing area of the driving wheel is to the pitting line, the more the meshing stiffness decreases, resulting in the intensification of vibration response and periodic impact; and in the time history diagram, there is a small spurious frequencies near the meshing frequency; in the phase diagrams and the Poincare diagram, trajectory and discrete point aggregation area is gradually increased.
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Radin, V. P., E. V. Poznyak, V. P. Chirkov, and O. V. Novikova. "Dynamic characteristics and adjustment of vibration isolators using the bilinear hysteresis." Proceedings of Higher Educational Institutions. Маchine Building, no. 12 (753) (December 2022): 14–23. http://dx.doi.org/10.18698/0536-1044-2022-12-14-23.
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The paper considers dynamic characteristics of a vibration protection device with bilinear deformation diagram and hysteresis behavior as part of a system with one degree of freedom. Based on results of the numerical simulation of the system’s response to harmonic effects, the amplitude-frequency characteristics (AFC) of relative displacements and absolute accelerations were constructed. AFC dependences on the limiting elastic displacement and the ratio of the diagram sections stiffness were studied. Based on the AFC, best parameters of a bilinear vibration isolator were determined to reduce the system dynamic response; besides, the nonlinear system resonant frequencies and the damping frequency regions were found.
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Yen, Nai‐chyuan, Louis R. Dragonette, and Christopher A. Ross. "Vein diagram: A simplified version of time‐frequency display for acoustic structure response." Journal of the Acoustical Society of America 92, no. 4 (October 1992): 2474. http://dx.doi.org/10.1121/1.404435.
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Gong, Jinzhe, Aaron C. Zecchin, Angus R. Simpson, and Martin F. Lambert. "Frequency Response Diagram for Pipeline Leak Detection: Comparing the Odd and Even Harmonics." Journal of Water Resources Planning and Management 140, no. 1 (January 2014): 65–74. http://dx.doi.org/10.1061/(asce)wr.1943-5452.0000298.
Full textDissertations / Theses on the topic "Frequency response diagram"
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Sismilich, Vladimír. "Vibrace při obrábění kovů – příčiny a jejich eliminace." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-229329.
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This diploma thesis is concerning about summarizing and describing types of vibrations, their causes and influences to the machining. The stable conditions of machining were pointed out. The experiment was conducted in which the frequency response function of specific milling machine was measured. Than the stability lobe diagram was constructed.
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Štěrba, Václav. "Návrh 10-ti kanálového equalizeru s optimalizací kmitočtové charakteristiky a spektrálním audio-analyzátorem." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2013. http://www.nusl.cz/ntk/nusl-219896.
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This work deals with the design of a 10-zones equalizer with optimized frequency characteristics with a spectrum audio analyzer. In this work the problem of processing audio signals using equalization for filtering the interference frequencies, correction of frequency cover signal boost or suppression of the required zones of the audible spectrum are also analyzed. The influence of subjective perception of sound intensity of the audio signals reproduction and its use in working with equalizer is discussed too. The work describes the principles and usage of the audio-analyzer as a tool for the optimization of the audio equalization setting when ensuring the appropriate listening conditions of music reproduction, spoken word, sounds, etc. It also focuses on the signal source for testing audio-chains, their generation and measurement using the audio analyzer. The equalizer equipment, audio-analyzer generator of reference signals equipment and power supply are designed as a single unit.
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Gong, Jinzhe. "Leak detection and condition assessment for water distribution pipelines using fluid transient waves." Thesis, 2014. http://hdl.handle.net/2440/101566.
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The focus of this PhD research is to develop non-invasive and cost-effective techniques for assessing the structural condition of pressurised pipelines using fluid transient pressure waves. The specific objectives include the detection of leaks and localised deterioration that is distributed along a pipeline, such as extended sections of corrosion or the spalling of cement lining. The latter is described by pipeline condition assessment in this thesis. The transient behaviour of a leak is studied in the frequency domain. Numerical studies conducted in this research demonstrate that two leak-induced patterns (on the resonant and the anti-resonant responses) can exist in a frequency response diagram (FRD). The amplitudes of the responses are related to the impedance of the valve in a reservoir-pipeline-valve (RPV) system.
A new leak detection technique has been developed in this research based on the further understanding of the leak-induced patterns. This technique uses the relative sizes of the first three resonant responses to determine the location and size of a single leak in RPV systems. In reservoir-pipeline-dead end systems, the information required for single event leak detection is further reduced to the first two resonant responses. A new measurement strategy for the extraction of the FRD of single pipelines is proposed in this research. The boundary valve loss is used to adjust the amplitude of the leak-induced pattern on the resonant responses and also the sharpness of the resonant peaks. A specific type of pseudo-random binary sequence (PRBS) termed the inverse repeat sequence (IRS), is used as the excitation signal. The antisymmetric property of IRS enables part of the nonlinear responses of the system under excitation to be cancelled out, yielding a measured FRD close to the theoretical linear system response. A side-discharge valve based transient generator is designed and fabricated in this research to implement the new FRD measurement strategy. Laboratory experiments are conducted on an intact pipeline and a pipeline with a leak. This research also conducts analysis of the characteristics of distributed pipe wall deterioration and develops new detection techniques. In a measured pressure trace, the size of the reflection resulting from a section of pipeline with a change in wall thickness is indicative of the characteristic impedance of this section. Once the impedance of this section is determined, the wave speed and wall thickness can be estimated. A technique for the detection of a single deteriorated section in pipelines is developed based on the above analysis. Two other condition assessment techniques are developed to deal with the complexities induced by multiple deteriorated sections. The first technique is termed reconstructive MOC (method of characteristics) analysis, which uses the pressure trace measured at the upstream face of the valve in a RPV system to determine the distribution of the impedance along the pipeline. The algorithm reconstructs a MOC grid by calculating the MOC compatibility equations backwards in time, estimating the properties of the pipeline (impedance, wave speed) and the length of each pipe reach as discretised by the MOC grid from the valve towards the reservoir. Preliminary experimental verification is conducted to verify the applicability of the new technique. The second technique is reconstructive transient analysis (RTA), which can be conducted at any interior accessible points along a pipeline, and does not require a RPV boundary condition. The RTA uses two pressure transducers in close proximity to measure two transient pressure traces in one test. A signal processing algorithm is developed to extract the directional transient waves (traveling upstream and downstream). The use of the directional transient waves enables the step response function (SRF) of the section of pipe upstream or downstream of the paired pressure transducers to be obtained. The reconstructive MOC analysis is then adapted to interpret the SRF to yield the distribution of the impedance, from which the location and severity of distributed deterioration can be identified.Thesis (Ph.D.) -- University of Adelaide, School of Civil, Environmental and Mining Engineering, 2014.
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Wang, Dongqian. "The comprehensive analysis of milling stability and surface location error with considering the dynamics of workpiece." 2020. https://tud.qucosa.de/id/qucosa%3A74786.
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Cutting movement is still one of the main means to obtain the desired machined surface. As the most representative cutting method in subtractive manufacturing, milling is widely used in industrial production. However, the chatter induced by the dynamic interaction between machine tool and process not only reduces the accuracy of the machined workpiece, but also increases the tool wear and affects the rotary accuracy of the spindle. The stability lobe diagram can provide stable machining parameters for the technicians, and it is currently an effective way to avoid chatter. In fact, the dynamic interaction between the machine tool and process is very complicated, which involves the machine tool, milling tool, workpiece and fixture. The induced mechanism of chatter depends on different machining scenarios and is not entirely dependent on the vibration modes of milling tool. Therefore, it is important to obtain stable machining parameters and to know the dynamic surface location error distribution, which can ensure machining quality and improve machining efficiency.
In this dissertation, two methods for constructing stability lobe diagram are first introduced, and then two machining scales, macro milling and micro milling, are studied. For the macro-milling scale, the dynamic response of the in-process workpiece with time-varying modal parameters during the material removal process is analyzed. The stability lobe diagrams for thin-walled workpiece and general workpiece with continuous radial immersion milling are established respectively. Besides, the cumulative surface location error distribution is also studied and verified for the general workpiece. For the micro-milling scale, the dynamics at the micro-milling tool point is obtained by means of the receptance coupling substructure analysis method. The stability lobe diagram and surface location error distribution are analyzed under different restricted/free tool overhang lengths. The relationship between measurement results and burrs is further explained by cutting experiments, and the difference between the two milling scales is compared in the end.
Book chapters on the topic "Frequency response diagram"
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Tanhapour, Mozhgan, and Sharareh Rostam Niakan Kalhori. "Early Warning System for Emergency Care: Designing a Timely Monitoring Mobile-Based System." In Studies in Health Technology and Informatics. IOS Press, 2022. http://dx.doi.org/10.3233/shti220009.
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Early Warning Scores (EWSs) systems support the timely detection of patient deterioration and rapid response of the care team. Due to the mobility nature of healthcare settings, there has been a growing tendency to use mobile-based devices in these settings. This chapter aimed to design a mobile-based EWS application (app). This was a descriptive study to design the architecture of the proposed EWS app. The design of architecture was done using the Unified Modeling Language diagrams including a class diagram, use-case diagram, and activity diagram. We evaluated the architecture using the ARID scenario-based evaluation method. The proposed EWS application (app) was the integration of three EWSs, including NEWS2, PEWS, and MEOWS. The workflow of these EWSs systems was designed and integrated into a single app. Also, the static structure of the proposed EWS app was designed by class diagram and the behavioral structure was depicted by use-case and activity diagrams. The class diagram showed the system components and their relationships. However, the use-case diagram displayed the app’s interaction with its environment, and the activity diagram illustrated how the EWS app processes were carried out. Evaluation results showed the possibility of designing the architecture for the proposed EWS app. In our app, the EWSs were designed in the clinician’s workflow, and it was integrated with the patient’s Electronic Health Record (EHR). These factors may lead to more use of EWSs. Considering the frequency of alerts represented to clinicians and the user-friendly design of the app, some suggestions can be considered by EWS systems developers in the future.
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Bajracharya, Sanjeema, and Eiichi Sasaki. "Evaluation of Eddy Current Response Due to the Applied Stress on a Steel Plate Using Phase Diagram." In Studies in Applied Electromagnetics and Mechanics. IOS Press, 2020. http://dx.doi.org/10.3233/saem200008.
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Structural health monitoring of steel structures is crucial for inspection of corrosion and cracking in structural members, compromising their safety and serviceability. In the present study, the prospective of evaluation of change in stress state of structural member due to corrosion and cracking through eddy current based stress measurement is investigated. For this, three-dimensional numerical simulations are carried out in the FE software COMSOL Multiphysics 5.2a for a steel plate subjected to change in relative permeability, representative of change in stress state, whereby the eddy current indices are characterized, including the effects of additional influential parameters namely, lift-off, excitation frequency, and probe size. Phase Diagram is then proposed as a concise method to evaluate the variation of relative permeability and lift-off concurrently in a single graph for an excitation frequency and probe size. It further facilitates the selection of suitable excitation frequency and probe size to conduct the eddy current based stress measurement.
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Veloni, Anatasia, and Alex Palamides. "Frequency Response: Bode Diagrams." In Control System Problems, 249–94. CRC Press, 2018. http://dx.doi.org/10.1201/9781315217024-7.
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Schubert, Thomas F., and Ernest M. Kim. "Frequency Response and Bode Diagrams." In Fundamentals of Industrial Electronics, 6–1. CRC Press, 2018. http://dx.doi.org/10.1201/9781315218441-6.
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"Schubert, Jr. ", Thomas, and Ernest Kim. "Frequency Response and Bode Diagrams." In Fundamentals of Industrial Electronics, 1–20. CRC Press, 2011. http://dx.doi.org/10.1201/b10602-8.
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Wan, Benli, Bin Hu, Yuntao Li, and Yuhong Zhu. "Study on Effect of Electromagnetic Characteristics of Deformed 304 Stainless Steel on Eddy Current Testing." In Studies in Applied Electromagnetics and Mechanics. IOS Press, 2020. http://dx.doi.org/10.3233/saem200003.
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The induced ferrite and other high magnetic microstructures content changes are studied when 304 austenitic stainless steel stripe specimens are tested under different uniaxial tension deformation, namely its deformation less than 50%. Furtherly, the correlation is plotted between the resulting magnetic permeability or coercivity caused by these microstructures and deformation. Meanwhile, the optimal eddy current excitation frequency under different deformation was obtained, which was consistent with 3-D finite element analysis (FEA). Besides, other various factors affecting the quality of eddy current testing (ECT), such as temperature and conductivity, are also considered comprehensively during the tensile test. The results of the experiment and simulation calculation show that when the deformation is within 50% that necking deformation has occurred, the magnetic permeability of specimens increases with deformation, and gradually begin to have the magnetic properties of weak ferromagnetic materials, which also changes the optimal excitation frequency, which varies from 60 kHz to 110 kHz. Because of the electromagnetic response noise increase, the impedance plane diagrams of defects distort simultaneously, which leads to the quantitative evaluation error of defects.
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Chu, C. Y. Cyrus. "Occupation-Specific Population Models: Population and Dynastic Cycles." In Population Dynamics. Oxford University Press, 1998. http://dx.doi.org/10.1093/oso/9780195121582.003.0014.
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As Lee (1987) pointed out, vital rates of the human population are often determined by forces such as culture, institutions, technology, and individual rationality, forces that have little to do with density pressure or prior growth. Perhaps most people also expect “rational” human practice to weaken the biological responses of both fertility and mortality to density pressure, while strengthening the nonbiological response through institutional regulations. But can human institutional designs and rational responses really reduce the impact of natural checks? As we study the pattern of population dynamics in ancient China, we can provide some viewpoints different from the general opinion. The long-term relationship between human institutional designs and natural checks is discussed in chapter 14. The books by Ho (1959) and Chao and Hsieh (1988; hereinafter C&H) contain the most thorough research on the history of Chinese population. The data summarized in C&H have presented us with a time-population diagram, shown in figure 9.1. From this figure, as well as other related literature, the following “stylized facts” of population dynamics in Chinese history can be summarized: 1. Population declines often coincided with dynasty changes (C&H; Ho, 1959). 2. Population declines were often drastic in a rather short period of time. 3. Natural checks such as famine and epidemics did not independently reduce the population surplus (Ho, 1959); rather, population declines were often the direct and indirect results of internecine wars. 4. There are obvious peaks and troughs in the population data, but no regular cyclical patterns (C&H). The fact that no serious population decline appears to have been independently due to famines and epidemics seems to suggest a weak pattern of density-dependency for ancient Chinese populations, a pattern consistent with the observation of Lee mentioned in the beginning of this chapter. However, as noted by many historians (see, e.g., Ho, 1959, and C&H 1988), the frequent clashes between soldiers and rebellious peasants in Chinese history were often initiated by famine or density pressure. As such, the originally weak natural checks on population were often magnified by war, and such magnified “institutional checks” caused very drastic population changes.
Conference papers on the topic "Frequency response diagram"
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Seo, Yun-Ho, and Chong-Won Lee. "A New Frequency-Speed Diagram Weighted With Strength of Modes in Rotating Machinery." In ASME Turbo Expo 2008: Power for Land, Sea, and Air. ASMEDC, 2008. http://dx.doi.org/10.1115/gt2008-50855.
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The coincidence of operating speed and critical speed must be avoided in the design of a rotor system. If the rotor system has various critical speeds as well as many modes, the determination of dangerous modes is a first step of the design stages. In this paper, the use of a new frequency-speed diagram that displays the significance of modes in order to help the design and analysis of a rotor system is suggested. The diagram is a modified version of a waterfall chart. The method graphically shows the magnitude of the forced responses by the directional frequency response matrices in accordance with operating speed because the responses are the most important criterion to determine significance of modes. In addition, because the excitation force of a rotor system such as mass unbalances is not known before the completion of manufacturing, the concept of summation of matrix norms, which is more conservative than conventional H∞ norm, is used in order to consider the worst of the worst case. A simple rotor system and a real generator system, which has both anisotropy and asymmetry, are demonstrated for usefulness of the proposed diagrams. The information of the diagram is then used to analyze the dynamic characteristics of the generator system.
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ZHU, Xing-bang, Guochao Li, chao LIU, Zhong HAN, feng Fei, and chao LI. "Frequency response calibration technology of optical eye diagram analyzer based on femtosecond laser." In Seventh Symposium on Novel Photoelectronic Detection Technology and Application 2020, edited by Junhao Chu, Qifeng Yu, Huilin Jiang, and Junhong Su. SPIE, 2021. http://dx.doi.org/10.1117/12.2587669.
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Muehlner, Edmund, Surya Banumurthy, and John Murray. "Effect of High-Frequency Response on TLP Tendon Fatigue." In ASME 2012 31st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/omae2012-83264.
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High-frequency vibrations of Tension Leg Platforms (TLPs), commonly known as ringing and springing, have challenged TLP designers since the first full-scale TLP was installed in the North Sea in 1984. Although current design codes recognize the significance of the ringing and springing response for tendon design, no widely accepted modeling approach for their calculation has yet emerged. This paper presents a nonlinear time-domain model of a TLP that exhibits the ringing and springing response of the vessel. The analysis model uses large displacement theory for the vessel and tendons and a semi-empirical wave model based on a modified linear wave theory. Predictions of vessel motions and tendon loads made with the analysis model were compared to model tests and were found in good agreement with the measurements. The analysis model was also was used to investigate the fatigue damage in the tendons caused by the vessel’s high-frequency response. Tendon stress time histories were computed for nine different unidirectional sea-states. These sea-states represent a condensed wave scatter diagram for the Gulf of Mexico (GoM). The tendon fatigue was calculated from the stress histories by rainflow counting. Fatigue contributions from different frequency ranges were identified by Fourier analysis. The analysis showed that high-frequency response was present in all sea-states even though ringing occurred only in sea-states with significant wave heights above 10 ft. Tendon fatigue damage contribution from high-frequency loads were found to be significant in every sea-state. For all sea-states combined 73% of the up-wave tendon fatigue damage was due to high-frequency response. For the down-wave and the cross-wave tendons, the high-frequency contributions were 57% and 34%, respectively. This paper demonstrates the importance of considering high-frequency response for the fatigue design of TLP tendons. Another finding of the study is that the analysis model using a modified linear wave theory can describe the ringing and springing behavior of a TLP provided other significant nonlinearities of the system are considered.
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Hajdu, David, Tamas Insperger, and Gabor Stepan. "The Effect of Non-Symmetric FRF on Machining: A Case Study." In ASME 2015 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/detc2015-47037.
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Stability prediction of machining operations is often not reliable due to the inaccurate mechanical modeling. A major source of this inaccuracy is the uncertainties in the dynamic parameters of the machining center at different spindle speeds. The so-called tip-to-tip measurement is the fastest and most convenient method to determine the frequency response of the machine. This concept consists of the measurement of the tool tip’s frequency response function (FRF) usually in two perpendicular directions including cross terms. Although the cross FRFs are often neglected in practical applications, they may affect the system’s dynamics. In this paper, the stability diagrams are analyzed for milling operations in case of diagonal, symmetric and non-symmetric FRF matrices. First a time-domain model is derived by fitting a multiple-degrees-of-freedom model to the FRF matrix, then the semi-discretization method is used to determine stability diagrams. The results show that the omission of the non-symmetry of the FRF matrix may lead to inaccurate stability diagram.
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González, Claudia Aide, Juan Carlos Jáuregui, Oscar De Santiago, and Víctor Solórzano. "Estimation of the Rotordynamic Coefficients of a Compressor Mounted on Gas Bearings Using the Phase Diagram and the Unbalance Response." In ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-42735.
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This paper presents a novel method for identifying the dynamic parameters of a gas bearing, whose force coefficients are strong functions of frequency. The method is based on the analysis of the phase diagram with the model assuming a mass-damper-spring system with time-dependent force coefficients. Usually, it is necessary a controlled mechanism to find the transfer function, this condition limits the application of the method. On the other hand, estimation of the damping and stiffness parameters under real loading is very cumbersome and requires a special care on identifying the excitation forces. One of the main difficulties is the isolation of noise and those vibration signals with an unidentified source. In this work, the excitation force was taken from the unbalance loading of a rotor test. Therefore, there is no need for a special test rig. The dynamic parameters can be estimated analyzing data from the actual rotor mounted on the gas bearings. Identifying the parameters that cause gas bearing instabilities is a big challenge. The gas properties are very sensitive to temperature and pressure changes, and, as a consequence the bearing rotor-dynamic coefficients change drastically and the rotor behaves chaotically, which means that the dynamic parameters are nonlinear. In this research a methodology based on the phase diagram construction to identify nonlinear instabilities of gas bearings is presented. The results show the method capability to estimate the dynamic coefficients by the analysis of the energy variation. Among nonparametric methods, the phase diagram or phase space is in use to identify nonlinearities in dynamic systems. The identification is conducted through the analysis of the energy variations. The energy variations can be represented as a three dimensional function E(x,v,t). In this way the phase diagram can be related to the frequency and the dynamic parameters of the system. According to Taken’s theorem, a dynamic system can be obtained by reconstructing the phase diagram. Then, using this method, the damping and stiffness coefficients are estimated.
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Ehrich, Fredric, and Marc Berthillier. "Spontaneous Sidebanding at Subharmonic Peaks of Rotordynamic Nonlinear Response." In ASME 1997 Design Engineering Technical Conferences. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/detc97/vib-4041.
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Abstract One of the authors has shown in previous papers (Enrich, 1995; Ehrich, 1996) that, when high speed rotors are operated in the transcritical range with the rotor located eccentrically in its rotor/stator clearance with the rotor in intermittent contact with the stator, a nonlinear response, at speeds both slightly above and slightly below the critical speed, is induced. The response at a particular speed will include significant components at an asynchronous frequency which is approximately equal to the natural frequency of the system. In particular, when the speed (normalized by the natural frequency) S is approximately (J+1)/J, the dominant frequency (normalized by the natural frequency) F is precisely J/(J+1) times S or approximately 1 (where values of the whole number J < 1 give the subcritical set of speeds and values J > 1 give the supercritical set of speeds). The phenomenon has been termed spontaneous sidebanding. Observations of similar asynchronous responses noted in a Campbell diagram of the rotordynamic response of an actual high speed rotor clustered around a subharmonic response peak at a rotational speed twice the natural frequency suggest that the phenomenon is also possible at any subharmonic pseudo-critical response peak. In this more general case, we would expect that at rotational speeds in the vicinity of the M th subharmonic pseudo-critical normalized speed where S is approximately (MJ+1)/J and the dominant normalized frequency F is precisely J/(MJ+1) times S or approximately 1 [where values of the whole number J < 1 give the sub(pseudo)critical set of speeds and values J > 1 give the super(pseudo)critical set of speeds]. A simple numerical model of the nonlinear system verifies that these asynchronous responses are indeed possible. Operation of the model at a rotational speed approximately double the natural frequency yields data which closely reproduce the asynchronous response seen in the actual machine.
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Jauregui, Juan C., Oscar Gonzalez, and Eduardo Rubio. "The Application of Time-Frequency and Phase Diagram Analyses for the Early Detection of Faulty Roller Bearing." In ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-59247.
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There are many systems that monitor and analyze machinery conditions, but there is a lack on monitoring techniques that are able to identify early faults. This is critical since faulty roller bearings cause most of the problems in rotating machinery. Two major difficulties limit the early prediction of roller bearing failures: The acquisition of high frequency data, and the low energy levels emitted by surfaces cracks on rollers or tracks. Early fault detection requires adequate instrumentation and signal analysis. Therefore, it is important to identify its nonlinear response, and to be able to detect low energy signals in order to detect early faults. The vibration characteristics of the bearing depend on the rotational speed, clearance, radial load, rolling element stiffness, and the surface waviness. Additionally, they generate transient vibrations due to stiffness nonlinearities and structural defects. We present in this work a technique for the detection of early faults. The technique is based on the derivation of the rolling bearing nonlinear stiffness as a function of the roller translation and roller deformation. For the deformation, we determine the relative displacement of the roller tracks and we apply Hertz’s contact stress function. With this formulation we identify the nonlinear response to the external excitation forces. Then, the results are analyzed with a time-frequency map and the phase diagram; the two analyses are compared in order to determine the best signal procedure to identify early failures.
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Pellicano, Francesco, and Fabrizio Vestroni. "Post-Critical Response of an Axially Moving Beam." In ASME 1999 Design Engineering Technical Conferences. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/detc99/vib-8038.
Full textAbstract:
Abstract In this paper the dynamic response of a simply supported traveling beam, subjected to a pointwise transversal load, is investigated. The motion is described by means of a high dimensional system of ordinary differential equations with linear gyroscopic part and cubic nonlinearities obtained through the Galerkin method. The system is studied in the super-critical speed range with emphasis on the stability and the global dynamics that exhibits special features after the first bifurcation. A sample case of a physical beam is developed and numerical results are presented concerning bifurcation analysis and stability, and direct simulations of global postcritical dynamics. In the supercritical speed range a regular motion around a bifurcated equilibrium position becomes chaotic for particular values of frequency and force. The bifurcation diagram for varying force intensity is shown, it can be noticed that a chaotic motion occurs in a wide range of the forcing parameter, co-existing with a 3T periodic solution in a limited window.
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Caruntu, Dumitru I., Julio Beatriz, and Miguel Martinez. "Frequency-Amplitude Response of Subharmonic Resonance of One-Third Order of Electrostatically Actuated MEMS Circular Plates." In ASME 2020 Dynamic Systems and Control Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/dscc2020-3217.
Full textAbstract:
Abstract This work deals with the subharmonic resonance of one-third order of electrostatically actuated clamped MEMS circular plate resonators. The system consists of flexible MEMS circular plate parallel to a ground plate actuated only by AC voltage. Hard excitations due to large enough AC voltage of frequency near three-halves of the natural frequency of the MEMS plate resonator lead it into a subharmonic resonance. The partial differential equation describing the motion of the resonator is nondimensionalized and two reduced order models are developed. The first one consists of a one mode of vibration model which is solved using the Method of Multiple Scales (MMS). The frequency-amplitude response (bifurcation diagram) is predicted. Hard excitations were modeled by keeping the first term of the Taylor polynomial of the electrostatic force as a large term and the rest of them as small terms. The second model uses two modes of vibration, and it is solved through numerical integration. This produces time responses of the resonator. Both methods show a zero-amplitude steady-state stable branch for the entire range of resonant frequencies. Also, two branches, one unstable and one stable, with a saddle node bifurcation point are predicted for non-zero steady state amplitudes. One can notice that non-zero steady state amplitudes can be reached only from large enough initial amplitudes. Both methods are in agreement for amplitudes up to 0.7 of the gap. The effect of damping and voltage on the frequency response are reported. As the damping increases, the saddle-node bifurcation point and consequently the non-zero steady-state branches are shifted to larger amplitudes. As the voltage increases, the saddle-node bifurcation point and the non-zero branches are shifted to lower amplitudes and lower frequency.
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Martinez, Miguel A., and Dumitru I. Caruntu. "Frequency-Amplitude Response of Parametric Resonance of Electrostatically Actuated MEMS Cantilever Beams Driven by Fringe Effect." In ASME 2022 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/detc2022-89962.
Full textAbstract:
Abstract This work deals with the frequency-amplitude response of parametric resonance of electrostatically actuated micro-electro-mechanical-system (MEMS) cantilever beam resonators driven by the fringe effect. The system involves a flexible MEMS cantilever beam parallel to a ground plate. The electrostatic force induced is due to the electric field between the cantilever beam and the ground plate (volume between cantilever and ground plate) and the electric field outside this volume which leads to the fringe effect. In this work, the cantilever is driven only by the fringe effect. The electrostatic force due to the electric field within the volume between cantilever and ground plate is neglected due to hole in the ground plate (size of cantilever). Excitations due to the fringe effect near the natural frequency of the MEMS cantilever beam lead the MEMS cantilever resonator into parametric resonance. The partial differential equation describing the motion of the cantilever resonator is nondimensionalized and a reduced order model is developed. This is a one-mode of vibration model which is solved using the Method of Multiple Scales (MMS). The frequency-amplitude response (bifurcation diagram) is predicted. The fringe effect was modeled by neglecting the electrostatic force term, and keeping the first four terms of the Taylor polynomial of the fringe effect (small terms due to small bookkeeping parameter). The method shows a zero-amplitude steady-state stable branch (trivial solution) for the entire range of resonant frequencies. In addition, two branches, one stable and one unstable, with two bifurcation points, subcritical and supercritical, are predicted. The response due to the fringe effect is compared to responses that involve the electrostatic force only as well as electrostatic and fringe combined. The influence of damping and voltage on the frequency-amplitude response are also investigated. As the damping increases, both non-zero steady-state branches, are shifted to higher frequencies and larger amplitudes. On the other hand, as the voltage increases the two non-zero branches are shifted to lower frequencies and smaller amplitudes.