Статті в журналах: "Self-oscillating mode"

1

Indeitsev, D. A., O. S. Loboda, N. F. Morozov, D. Yu Skubov, and L. V. Shtukin. "Self-Oscillating Mode of a Nanoresonator." Physical Mesomechanics 21, no. 3 (May 2018): 203–7. http://dx.doi.org/10.1134/s1029959918030037.

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2

Manning, L., B. Rogers, M. Jones, J. D. Adams, J. L. Fuste, and S. C. Minne. "Self-oscillating tapping mode atomic force microscopy." Review of Scientific Instruments 74, no. 9 (September 2003): 4220–22. http://dx.doi.org/10.1063/1.1602935.

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3

Ali, Samer, Zein Alabidin Shami, Ali Badran, and Charbel Habchi. "Heat transfer enhancement using second mode self-oscillating structures." International Journal of Numerical Methods for Heat & Fluid Flow 30, no. 7 (November 22, 2019): 3827–42. http://dx.doi.org/10.1108/hff-07-2019-0583.

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Purpose In this paper, self-sustained second mode oscillations of flexible vortex generator (FVG) are produced to enhance the heat transfer in two-dimensional laminar flow regime. The purpose of this study is to determine the critical Reynolds number at which FVG becomes more efficient than rigid vortex generators (RVGs). Design/methodology/approach Ten cases were studied with different Reynolds numbers varying from 200 to 2,000. The Nusselt number and friction coefficients of the FVG cases are compared to those of RVG and empty channel at the same Reynolds numbers. Findings For Reynolds numbers higher than 800, the FVG oscillates in the second mode causing a significant increase in the velocity gradients generating unsteady coherent flow structures. The highest performance was obtained at the maximum Reynolds number for which the global Nusselt number is improved by 35.3 and 41.4 per cent with respect to empty channel and rigid configuration, respectively. Moreover, the thermal enhancement factor corresponding to FVG is 72 per cent higher than that of RVG. Practical implications The results obtained here can help in the design of novel multifunctional heat exchangers/reactors by using flexible tabs and inserts instead of rigid ones. Originality/value The originality of this paper is the use of second mode oscillations of FVG to enhance heat transfer in laminar flow regime.

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4

Polyakov, Dmitry N., Valeria V. Shumova, and Leonid M. Vasilyak. "Self-Oscillating Mode of Dusty Plasma and Particles Separation." IEEE Transactions on Plasma Science 42, no. 10 (October 2014): 2684–85. http://dx.doi.org/10.1109/tps.2014.2311584.

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5

Watanabe, Toshiro. "Oscillation of modes of some semi-stable Lévy processes." Nagoya Mathematical Journal 132 (December 1993): 141–53. http://dx.doi.org/10.1017/s0027763000004682.

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In this paper it is shown that there is a unimodal Levy process with oscillating mode. After the author first constructed an example of such a self-decomposable process, Sato pointed out that it belongs to the class of semi-stable processes with β < 0. We prove that all non-symmetric semi-stable self-decomposable processes with β < 0 have oscillating modes.

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6

Giessibl, Franz J., and Marco Tortonese. "Self-oscillating mode for frequency modulation noncontact atomic force microscopy." Applied Physics Letters 70, no. 19 (May 12, 1997): 2529–31. http://dx.doi.org/10.1063/1.118910.

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7

Yu, Tae-Jun, Jai-Hee Sung, and Chang-Hee Nam. "Self-Oscillating, Third-Harmonic Mode-Locked l-GHz Nd:YLF Laser." Journal of the Optical Society of Korea 3, no. 2 (September 1, 1999): 51–54. http://dx.doi.org/10.3807/josk.1999.3.2.051.

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8

Biswas, S. K., and B. Basak. "A New Self-Oscillating Inverter for Switch Mode Power Supplies." IETE Journal of Research 31, no. 5 (September 1985): 187–89. http://dx.doi.org/10.1080/03772063.1985.11436530.

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9

Zöllner, Jens-Peter, Steve Durstewitz, Jaqueline Stauffenberg, Tzvetan Ivanov, Mathias Holz, Waleed Ehrhardt, W. Ulrich Riegel, and Ivo W. Rangelow. "Gas-Flow Sensor Based on Self-Oscillating and Self-Sensing Cantilever." Proceedings 2, no. 13 (December 3, 2018): 846. http://dx.doi.org/10.3390/proceedings2130846.

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In this work the application of a self-sensing and self-actuating cantilever for gas-flow measurement is investigated. The cantilever placed in the flow is excited permanently at its first resonance mode. Simultaneously the resonance amplitude, the resonance frequency and the static bending of the cantilever are detected. All three sizes are related to the velocity of the gas-flow.

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10

Khawaja, Bilal A., and Martin J. Cryan. "A Millimeter-Wave Self-Oscillating Mixer Using a Mode-Locked Laser." IEEE Transactions on Microwave Theory and Techniques 58, no. 11 (November 2010): 3352–58. http://dx.doi.org/10.1109/tmtt.2010.2077513.

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11

Yao, Xue Li, Song Lin Yi, Xiao Yan Zhang, and Bi Guang Zhang. "A Preliminary Study of Self-Exciting Mode Oscillating-Flow Heat Pipe Used in the Heat Recovery of Wood Drying." Advanced Materials Research 160-162 (November 2010): 1112–17. http://dx.doi.org/10.4028/www.scientific.net/amr.160-162.1112.

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First building up the test bed of heat recovery unit which made use of Self-Exciting Mode Oscillating-Flow Heat Pipe heat exchanger, simulated the conventional wood drying chamber exhaust conditions, this paper compared and analyzed the different heat recovery efficiency of this heat exchanger under different operating modes. The results showed that: when the air flow and temperature at the hot end kept steady, the heat recovery efficiency increased as the relative humidity increasing; while the air flow and relative humidity at the hot end remained stable, the heat recovery efficiency decreased along with the temperature increasing; the hot end temperature reached the top on the dew point. The average heat recovery efficiency of Self-Exciting Mode Oscillating-Flow Heat Pipe heat exchanger was about 15%.

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12

Chini, A. "Analysis of self‐oscillating switched‐mode circuit for low‐voltage energy harvesting." Electronics Letters 49, no. 15 (July 2013): 955–57. http://dx.doi.org/10.1049/el.2013.1372.

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13

Чеврычкина, А. А., Н. М. Бессонов та А. Л. Корженевский. "Расчет динамики границы аморфная фаза-кристалл при твердофазной взрывной кристаллизации". Физика твердого тела 63, № 11 (2021): 1927. http://dx.doi.org/10.21883/ftt.2021.11.51599.162.

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The nonlinear differential equation described a dynamics of solid-phase explosive crystallization front in a much larger parameters domain in comparison with the theoretical results available in literature was obtained. The features of the self-oscillating mode transition of the front motion to the mode of its self-propagation with a constant velocity was numerically studied in detail.

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14

Ge, Dali, Peibao Xu, and Kai Li. "Self-Sustained Oscillation of a Photothermal-Responsive Pendulum under Steady Illumination." Mathematical Problems in Engineering 2021 (February 15, 2021): 1–12. http://dx.doi.org/10.1155/2021/5531530.

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Self-sustained oscillation has the advantages of harvesting energy from the environment and self-control, and thus, the development of new self-oscillating systems can greatly expand its applications in active machines. In this paper, based on conventional photothermal shrinkable material or photothermal expansive material, a simple pendulum is proposed. The light-powered self-sustained oscillation of the simple pendulum is theoretically studied by establishing a dynamic model of the photothermal-responsive pendulum. The results show that there are two motion modes of the simple pendulum, which are the static mode and the oscillation mode. Based on the photothermal-responsive model, this paper elucidates the mechanism of the self-excited oscillation. The condition for triggering self-excited oscillation is further studied. In addition, the influence of the system parameters on the amplitude and frequency is also obtained. This study may have potential applications in energy harvesting, signal monitoring, and soft machines.

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15

Bettouche, Mohamed Amine, Mohamed Fouad Benkhoris, Jean-Claude Le Claire, Djamal Aouzellag, Kaci Ghedamsi, and Mourad Ait Ahmed. "Analysis of the effect neutral connection mode for permanent magnet synchronous generator-vienna rectifier set." E3S Web of Conferences 152 (2020): 03010. http://dx.doi.org/10.1051/e3sconf/202015203010.

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In this paper, it was considered to investigate a new electrical architecture for the conversion of mechanical energy from renewable sources into electrical energy, fault tolerant and high energy and dynamic performance for the exploitation of marine renewable energy (MRE). The architecture to be investigated concerns a three-phase permanent magnet synchronous generator combined with a Vienna rectifier, with a topology that minimizes the number of active switches to increase the reliability of the energy conversion chain. Despite the high non-linearity of this architecture, this control is made possible through to the dynamic performance and control of the maximum switching frequency of the self-oscillating controller called the Phase-Shift Self-Oscillating Current-Controller (PSSOCC). The study of the impact of the connection of the PMSG neutral to the mid-point of the DC bus is being investigated.

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16

Huq, M. Z., C. Butaye, and J.-P. Celis. "An Innovative System for Fretting Wear Testing Under Oscillating Normal Force." Journal of Materials Research 15, no. 7 (July 2000): 1591–99. http://dx.doi.org/10.1557/jmr.2000.0228.

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Material damage caused by fretting wear is of significant concern in many engineering applications. This paper describes the design and performance of a new machine for the laboratory investigation of fretting wear under oscillating normal force (fretting mode II). The test machine uses an electromagnetic actuator to impose an oscillating normal force between the contacting bodies at a constant force amplitude over a wide range of frequencies. The principle of the actuation mechanism and the fretting wear induced with this particular wear test configuration are outlined in detail. Normal force and electrical contact resistance were measured on-line during fretting mode II wear tests. The performance of the wear test machine is illustrated by data obtained for different materials combinations, namely, hard materials, such as high-speed steel and (Ti,Al)N coatings oscillating against alumina ball counterbodies, and soft materials, such as a tin coating oscillating against the same. In general, wearing of the counterbodies was observed in the slip region. It has been observed that hard coatings and bulk ceramics are prone to fretting fatigue cracking. The evolution of electrical contact resistance in the case of the self-mated soft tin coatings tested under fretting mode II conditions is also reported.

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17

Zhileykin, M. M. "Research of Self-Oscillating Processes in the Zone of Interaction of an Elastic Tire with a Solid Support Base." Proceedings of Higher Educational Institutions. Маchine Building, no. 10 (739) (October 2021): 3–15. http://dx.doi.org/10.18698/0536-1044-2021-10-3-15.

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When two bodies interact in contact, self-oscillations or relaxation vibrations can occur, which are vibrations of parts of bodies relative to each other. The study of the processes occurring in the zone of an elastic tire interaction with a solid support base is of particular interest, since they directly affect the safety of movement of wheeled vehicles. The aim of the work is to study the conditions for the occurrence of self-oscillating processes in the zone of interaction of an elastic tire with a solid support base in three rolling modes: traction, driven, and braking. It has been established that the appearance of a self-oscillating mode in the zone of interaction of an elastic tire with a solid support base is a useful diagnostic feature providing recognition of the development of the process of losing adhesion of a wheel with a support base when the rear axle skids at early stages.

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18

Губаль, Г. "Construction and study of the system of differential equations that describes the mutual synchronization of coupled self-oscillating chemical systems." COMPUTER-INTEGRATED TECHNOLOGIES: EDUCATION, SCIENCE, PRODUCTION, no. 41 (December 14, 2020): 30–34. http://dx.doi.org/10.36910/6775-2524-0560-2020-41-05.

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The article constructs and investigates the system of differential equations that describes the mutual synchronization of coupled self-oscillating chemical systems, defines the synchronization bar in which a synchronous mode exists and determines the time of establishment of the synchronous phase difference.

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19

Vizgalov, I. V., K. M. Gutorov, V. A. Kurnaev, and I. A. Sorokin. "Self-Oscillating Mode of a Probe with Increased Secondary Emission for Nonequilibrium Plasma Diagnostics." Physics of Atomic Nuclei 82, no. 10 (December 2019): 1368–75. http://dx.doi.org/10.1134/s1063778819100181.

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20

Wang, Ting, Ji-Liang Wu, Ke Yang, Yue-De Yang, Jin-Long Xiao, and Yong-Zhen Huang. "Flat Self-Oscillating Parametric Optical Frequency Comb Based on a Dual-Mode Microcavity Laser." IEEE Photonics Technology Letters 34, no. 6 (March 15, 2022): 325–28. http://dx.doi.org/10.1109/lpt.2022.3155763.

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21

Samsam-Khayani, Hadi, Shabnam Mohammadshahi, and Kyung Chun Kim. "Experimental Study on Physical Behavior of Fluidic Oscillator in a Confined Cavity with Sudden Expansion." Applied Sciences 10, no. 23 (December 3, 2020): 8668. http://dx.doi.org/10.3390/app10238668.

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In this study, two-dimensional time-resolved particle image velocimetry (2D-TR-PIV) was used to investigate the effect of the external domain on oscillating jets from double-feedback fluidic oscillators. Two different cases with different Re numbers (2680–10,730), as free external domain and fully confined were studied. Time-averaged results showed although a self-oscillating jet was attained for the free external domain, it could not be achieved for a fully confined geometry. For a fully confined geometry at Re = 2680, two symmetric vortices did not allow the jet to oscillate and at Re = 6440, the flow pattern in the external region became non-symmetric due to the Coanda vortex, subsequently, the self-oscillating jet was not observed. At Re = 10,730, the strength of the jet was inclined to cope with such vortices and tended to oscillate. However, strong vortices were created near the exit region of the fluidic oscillator, which led to an almost non-symmetric pattern. In addition, the proper orthogonal decomposition (POD) method and phase-averaged analysis were applied to obtain the unsteady behavior of flow and the most energetic dynamic structure. Interestingly, at Re = 6440, the third mode was still energetic for fully confined, but for other cases, the first two modes were the most energetic modes, which showed vigorous coherent structures.

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22

Zhang Zhen-Yu, Ke Wu, and Ning Yang. "A Millimeter-Wave Sub-Harmonic Self-Oscillating Mixer Using Dual-Mode Substrate Integrated Waveguide Cavity." IEEE Transactions on Microwave Theory and Techniques 58, no. 5 (May 2010): 1151–58. http://dx.doi.org/10.1109/tmtt.2010.2045565.

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23

Gavrilov, N. V., and A. S. Kamenetskikh. "Self-oscillating mode of electron beam generation in a source with a grid plasma emitter." Technical Physics 58, no. 10 (October 2013): 1426–31. http://dx.doi.org/10.1134/s1063784213100101.

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24

Alekseev, Yu I., A. V. Dem’yanenko, and M. V. Orda-Zhigulina. "Analysis of transition of a deterministic self-oscillating microwave system to the chaotic generation mode." Journal of Communications Technology and Electronics 59, no. 7 (July 2014): 755–57. http://dx.doi.org/10.1134/s106422691407002x.

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25

Wen, Yue, and Olivier Trescases. "Analysis and Comparison of Frequency Stabilization Loops in Self-Oscillating Current Mode DC–DC Converters." IEEE Transactions on Power Electronics 28, no. 10 (October 2013): 4753–66. http://dx.doi.org/10.1109/tpel.2012.2232307.

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26

Du, Changshen, Quanbao Cheng, Kai Li, and Yong Yu. "A Light-Powered Liquid Crystal Elastomer Spring Oscillator with Self-Shading Coatings." Polymers 14, no. 8 (April 9, 2022): 1525. http://dx.doi.org/10.3390/polym14081525.

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The self-oscillating systems based on stimuli-responsive materials, without complex controllers and additional batteries, have great application prospects in the fields of intelligent machines, soft robotics, and light-powered motors. Recently, the periodic oscillation of an LCE fiber with a mass block under periodic illumination was reported. This system requires periodic illumination, which limits the application of self-sustained systems. In this paper, we creatively proposed a light-powered liquid crystal elastomer (LCE) spring oscillator with self-shading coatings, which can self-oscillate continuously under steady illumination. On the basis of the well-established dynamic LCE model, the governing equation of the LCE spring oscillator is formulated, and the self-excited oscillation is studied theoretically. The numerical calculations show that the LCE spring oscillator has two motion modes, static mode and oscillation mode, and the self-oscillation arises from the coupling between the light-driven deformation and its movement. Furthermore, the contraction coefficient, damping coefficient, painting stretch, light intensity, spring constant, and gravitational acceleration all affect the self-excited oscillation of the spring oscillator, and each parameter is a critical value for triggering self-excited oscillation. This work will provide effective help in designing new optically responsive structures for engineering applications.

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27

WANG, WEN-YUAN, WEN-SHAN DUAN, and JIE LIU. "THE EFFECTS OF THE BEYOND MEAN FIELD CORRECTIONS OF FERMI SUPERFLUID GAS IN A DOUBLE-WELL POTENTIAL." International Journal of Modern Physics C 23, no. 11 (November 2012): 1250076. http://dx.doi.org/10.1142/s0129183112500763.

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By considering the contribution of the higher-order term representing the lowest approximation of beyond mean field corrections, we investigate a superfluid Fermi gas confined in a double-well potential in Bose–Einstein Condensation (BEC) side of the Bardeen–Cooper–Schrieffer (BCS) to BEC crossover. Two limited cases of deep BEC regime and BEC regime of BCS–BEC crossover, corresponding to the two-body scattering length a sc is small enough and large enough, respectively. We derive a simple two-mode model that could depict the dynamics effectively. With making thorough analysis on the two-mode model and its corresponding classical Hamiltonian, we find that the Josephson oscillation or self-trapping phenomenon could emerge at certain parameters. We find three kinds of the phase states: Josephson oscillation (JO), oscillating-phase-type self-trapping (OPTST) and running-phase-type self-trapping (RPTST). The dependence of these three phase states on the dimensionless interaction parameter y = 1/(kFa sc ) and the initial system energy are given in this paper.

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28

Pogrebnyak, V. G., and І. V. Perkun. "The Peculiarities of Oil Displacement in the Process of Oscillating Injection of Polymer Solution into the Bed with Layered Heterogeneity." Prospecting and Development of Oil and Gas Fields, no. 3(72) (September 30, 2019): 42–50. http://dx.doi.org/10.31471/1993-9973-2019-3(72)-42-50.

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The authors study the filtration flow of polyethylene oxide (PEO) water solutions of molecular weights 4∙106 and 6∙106 within the concentration range from 0 to 0.05% when exposed to an oscillating hydrodynamic field. Photographs characterizing the displacement of oil (with a viscosity of 10 to 50 mPa. s) with PEO water solutions from model porous formations with layered heterogeneity have been obtained. They have made it possible to specify the effectiveness of different oil displacement modes. It is shown that pumping a polymer solution into porous heterogeneous strata, while exposing it to oscillating hydrodynamic field, proved to yield a higher oil displacement ratio, as compared with a stationary oil displacement mode. The authors find out the conditions providing the positive influence on elastic deformations effects in the process of enhanced oil recovery by using polymer solutions. If elastic deformations take place, the filtration flow of polymer solutions should be carried out in the oscillating mode, whereas the frequency of the oscillating effect on the filtration flow should correspond to the dissipative function maximum. The stated results of the polymer solution flow research, under model conditions of a porous bed, have confirmed the nonlinearity mechanism of the polymer solutions filtration flow. In essence, the molecular and macromolecular non-linearity mechanism of the polymer solutions filtration flow means that in a porous medium under the influence of quasi-regular longitudinal velocity gradients, there arise self-sustained oscillations of reversible macromolecular deployment; the deployed macromolecules, in turn, influence the structure of the filtration flow, both on the molecular and macromolecular levels. Deformation oscillations of macromolecules and dissolubility of dynamic macromolecular structures formed under the influence of tensile currents result in the energy dissipation increase and the filtration flow nonlinearity. The nonlinearity of polymer solutions filtration flow ensures the alignment of the frontal advance of the polymer solutions within a porous bed with a layered heterogeneity and, consequently, higher oil displacement efficiency.

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29

UEMURA, Mitsuhiro. "H211 Heat Transport Performance Test of Self-Exiting Mode Oscillating-Flow Heat Pipe made of Pressed." Proceedings of the Thermal Engineering Conference 2013 (2013): 409–10. http://dx.doi.org/10.1299/jsmeted.2013.409.

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30

Centurelli, Francesco, Pietro Monsurrò, Giuseppe Scotti, Pasquale Tommasino, and Alessandro Trifiletti. "A Power Efficient Frequency Divider With 55 GHz Self-Oscillating Frequency in SiGe BiCMOS." Electronics 9, no. 11 (November 21, 2020): 1968. http://dx.doi.org/10.3390/electronics9111968.

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A power efficient static frequency divider in commercial 55 nm SiGe BiCMOS technology is reported. A standard Current Mode Logic (CML)-based architecture is adopted, and optimization of layout, biasing and transistor sizes allows achieving a maximum input frequency of 63 GHz and a self-oscillating frequency of 55 GHz, while consuming 23.7 mW from a 3 V supply. This results in high efficiency with respect to other static frequency dividers in BiCMOS technology presented in the literature. The divider topology does not use inductors, thus optimizing the area footprint: the divider core occupies 60 × 65 μm2 on silicon.

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31

Shang, Fu Min, Jian Hong Liu, and Deng Ying Liu. "Experimental Investigation on the Heat Transfer Characteristics of Nanofluids in Self-Exciting Mode Oscillating-Flow Heat Pipe." Advanced Materials Research 396-398 (November 2011): 250–54. http://dx.doi.org/10.4028/www.scientific.net/amr.396-398.250.

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The objective of this article is to provide the heat transfer characteristics of Cu-H2O nanofluids in self-exciting mode oscillating-flow heat pipe under different laser heating input, and to compare with the heat transfer characteristics of the same heat pipe with distilled water as working fluids. In this paper, the peculiarity of heat transfer rate of the SEMOS heat pipe with Cu-H2O fluid has been experimentally confirmed by changing the proportion of working fluid and Cu nanoscale particles in the heat pipe. As the results, it has been confirmed that the parameter of filling rate of working fluid determine the heat transfer rate of SEMOS heat pipe, although under certain condition heat transfer performance could be improved because of the addition of nanofluids.

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32

Nikolaev, O. O., A. E. Tubolkin, V. P. Britov, G. A. Steblovskii, and V. V. Bogdanov. "Preparation and modification of low-viscous polymeric composites in rotary-pulsatory apparatus in the self-oscillating mode." Russian Journal of Applied Chemistry 81, no. 3 (March 2008): 482–86. http://dx.doi.org/10.1134/s1070427208030282.

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33

Bagheri, Shervin. "Koopman-mode decomposition of the cylinder wake." Journal of Fluid Mechanics 726 (June 11, 2013): 596–623. http://dx.doi.org/10.1017/jfm.2013.249.

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AbstractThe Koopman operator provides a powerful way of analysing nonlinear flow dynamics using linear techniques. The operator defines how observables evolve in time along a nonlinear flow trajectory. In this paper, we perform a Koopman analysis of the first Hopf bifurcation of the flow past a circular cylinder. First, we decompose the flow into a sequence of Koopman modes, where each mode evolves in time with one single frequency/growth rate and amplitude/phase, corresponding to the complex eigenvalues and eigenfunctions of the Koopman operator, respectively. The analytical construction of these modes shows how the amplitudes and phases of nonlinear global modes oscillating with the vortex shedding frequency or its harmonics evolve as the flow develops and later sustains self-excited oscillations. Second, we compute the dynamic modes using the dynamic mode decomposition (DMD) algorithm, which fits a linear combination of exponential terms to a sequence of snapshots spaced equally in time. It is shown that under certain conditions the DMD algorithm approximates Koopman modes, and hence provides a viable method to decompose the flow into saturated and transient oscillatory modes. Finally, the relevance of the analysis to frequency selection, global modes and shift modes is discussed.

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34

Mouro, João, Paolo Paoletti, Michele Basso, and Bruno Tiribilli. "Measuring Viscosity Using the Hysteresis of the Non-Linear Response of a Self-Excited Cantilever." Sensors 21, no. 16 (August 19, 2021): 5592. http://dx.doi.org/10.3390/s21165592.

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A self-oscillating microcantilever in a feedback loop comprised of a gain, a saturator, and an adjustable phase-shifter is used to measure the viscosity of Newtonian fluids. Shifting the signal of the loop with the adjustable phase-shifter causes sudden jumps in the oscillation frequency of the cantilever. The exact position of these jumps depends on whether the shift imposed by the phase-shifter is increasing or decreasing and, therefore, the self-excited cantilever exhibits a hysteretic non-linear response. This response was studied and the system modeled by a delay differential equation of motion where frequency-dependent added mass and damping terms accounted for the density and the viscosity of the medium. Experimental data were obtained for solutions with different concentrations of glycerol in water and used to validate the model. Two distinct sensing modalities were proposed for this system: the sweeping mode, where the width of the observed hysteresis depends on the viscosity of the medium, and the threshold mode, where a sudden jump of the oscillation frequency is triggered by an arbitrarily small change in the viscosity of the medium.

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35

Kucera, Martin, Elisabeth Wistrela, Georg Pfusterschmied, Víctor Ruiz-Díez, Tomás Manzaneque, Jorge Hernando-García, José Luis Sánchez-Rojas, et al. "Design-dependent performance of self-actuated and self-sensing piezoelectric-AlN cantilevers in liquid media oscillating in the fundamental in-plane bending mode." Sensors and Actuators B: Chemical 200 (September 2014): 235–44. http://dx.doi.org/10.1016/j.snb.2014.04.048.

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36

Deineka, Kateryna, Yurii Naumenko, and Anatolii Zmiievskyi. "THE DRUM ROTATION VELOCITY VALUE WHEN AUTO-OSCILLATION SELF-EXCITATION WITH MAXIMUM SWING OF A POLYGRANULAR INTRACHAMBER FILL." Vibrations in engineering and technology, no. 1(96) (August 27, 2020): 61–69. http://dx.doi.org/10.37128/2306-8744-2020-1-7.

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The influences of the structure of two-fractional polygranular intrachamber fill on the drum rotation velocity value when auto-oscillation self-excitation with maximum swing is considered. The pulsating mode of flow of such intrachamber fill is used in the self-oscillating grinding process in a tumbling mill. Spherical particles of non-coherent granular material of 2.2 mm size were used as a large fraction modeling the grinding bodies. Cement was used as the small fraction modeling the particles of the crushed material. The factors of experimental studies were accepted: the gaps between particles of large fraction degree of filling at rest dispersed particles of small fraction 0, 25, 50 and 100%, the relative size of particles of large fraction in the drum chamber 0.519, 0.733, 1.04, 1.47, 2.08, 2.93, 4.15 and 5.87% (drum chamber radius 212, 150, 106, 75, 53, 37.5, 26.5 and 18.75 mm), the chamber degree of filling at rest 25, 35 and 45%. The method of visual analysis of transient processes of self-oscillating fill flow modes in the cross section of a rotating chamber was applied. Measurements of the drum rotation velocity during fill self-excited self-oscillations were performed. The magnitude of the self-oscillation swing was estimated by the increase in the difference of the maximum and minimum values of the fill dilatation over one period of pulsating. The magnitude of the relative drum rotation velocity at the maximum range of fill self-oscillation swing varied within 0.777-1.4. The effect of a decrease in the relative drum rotation velocity value, when the maximum polygranular intrachamber fill self-oscillations swing, with enhanced fill coherent properties has been registered. A decrease in the relative rotational velocity was established with a decrease in the relative particle size of large fill fraction and an increase in the content of small fill fraction and an increase in the chamber degree of filling. A sharp intensification of the decrease in the relative rotation velocity at a value of the relative size of large particles of less than 0.015 is revealed.

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37

Гришин, С. В., Б. С. Дмитриев та В. Н. Скороходов. "Генерация импульсов гигантской амплитуды в клистронном автогенераторе хаоса". Письма в журнал технической физики 45, № 19 (2019): 33. http://dx.doi.org/10.21883/pjtf.2019.19.48315.17928.

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The presented experimental results demonstrate the formation of giant amplitude microwave impulses by a chaotic klystron generator operating in autonomous mode. The auto-oscillator is constructed on the basis of a “noisetron” scheme, which contains two five-resonator drift klystrons connected in series in a ring. One of the klystrons operates in a signal linear amplification mode (a linear klystron) and the other - in a signal nonlinear amplification mode (a nonlinear klystron). It has been established that a regime of dynamic intermittency of the “chaos-chaos” type appears in a self-oscillating system at a certain value of a beam current of the nonlinear klystron. In this case, the chaotic sequences of microwave impulses of giant amplitude are formed on a chaotic amplitude background. This type of intermittency is due to the amplitude bistability of the nonlinear klystron.

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38

Deineka, Kateryna, and Yurii Naumenko. "ESTABLISHING THE ROTATION SPEED VARIATION RANGE LIMITS FOR AUTO-EXCITATION OF SELF-OSCILLATING GRINDING IN A TUMBLING MILL." Technology transfer: fundamental principles and innovative technical solutions 4 (November 30, 2020): 32–35. http://dx.doi.org/10.21303/2585-6847.2020.001479.

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The influence of the structure of a two-fraction polygranular feed of the chamber on the value of the drum rotation speed at auto-excitation of self-excited oscillations with a maximum swing is considered. Such a pulsating mode of movement of the charge is used in the self-oscillating process of grinding in a tumbling mill. The coarse fraction simulated the grinding bodies was steel bullets with a relative size ψdb=0.026. The fine fraction, simulated the particles of the crushed material, was a cement clinker with a relative particle size ψdm=0.00013. Variable factors of experimental studies were: the degree of filling the chamber in the state of rest κbr=0.25; 0.29; 0.33 and the degree of filling the gaps between the particles of the coarse fraction with particles of the fine fraction κmbgr=0.0625; 0.375; 0.6875; 1. The method of visual analysis of transient processes of self-oscillating modes of feed behavior in the cross section of the rotating drum chamber is applied. Measurements of the speed limits of the drum rotation were carried out with auto-excitation of self-oscillations of the filling. The magnitude of the self-oscillation swing was estimated by the increase in the difference between the maximum and minimum values of the filling dilatancy for one period of pulsations. An increase in the upper limit of the speed range ψω2 with a decrease in κbr and κmbgr was established. The growth rate of ψω2 increases at low values of κbr and κmbgr. Some increase in the lower limit of the ψω1 range with a decrease in κbr and κmbgr was revealed. An increase in the range of speeds of rotation was recorded at the maximum range of self-oscillations ψω1–ψω2 with a decrease in the connected interaction of the intra-mill filling. This coherent interaction is due to an increase in κbr and κmbgr. The value of the ψω1–ψω2 range varies from 1.01–1.03 at κbr=0.33 and κmbg=1 to 1.22–1.66 at κbr=0.25 and κmbgr=0.0625. The range gets its maximum value with fine and superfine grinding

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39

Flierl, G. R., and J. Pedlosky. "The Nonlinear Dynamics of Time-Dependent Subcritical Baroclinic Currents." Journal of Physical Oceanography 37, no. 4 (April 1, 2007): 1001–21. http://dx.doi.org/10.1175/jpo3034.1.

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Abstract The nonlinear dynamics of baroclinically unstable waves in a time-dependent zonal shear flow is considered in the framework of the two-layer Phillips model on the beta plane. In most cases considered in this study the amplitude of the shear is well below the critical value of the steady shear version of the model. Nevertheless, the time-dependent problem in which the shear oscillates periodically is unstable, and the unstable waves grow to substantial amplitudes, in some cases with strongly nonlinear and turbulent characteristics. For very small values of the shear amplitude in the presence of dissipation an analytical, asymptotic theory predicts a self-sustained wave whose amplitude undergoes a nonlinear oscillation whose period is amplitude dependent. There is a sensitive amplitude dependence of the wave on the frequency of the oscillating shear when the shear amplitude is small. This behavior is also found in a truncated model of the dynamics, and that model is used to examine larger shear amplitudes. When there is a mean value of the shear in addition to the oscillating component, but such that the total shear is still subcritical, the resulting nonlinear states exhibit a rectified horizontal buoyancy flux with a nonzero time average as a result of the instability of the oscillating shear. For higher, still subcritical, values of the shear, a symmetry breaking is detected in which a second cross-stream mode is generated through an instability of the unstable wave although this second mode would by itself be stable on the basic time-dependent current. For shear values that are substantially subcritical but of order of the critical shear, calculations with a full quasigeostrophic numerical model reveal a turbulent flow generated by the instability. If the beta effect is disregarded, the inviscid, linear problem is formally stable. However, calculations show that a small degree of nonlinearity is enough to destabilize the flow, leading to large amplitude vacillations and turbulence. When the most unstable wave is not the longest wave in the system, a cascade up scale to longer waves is observed. Indeed, this classically subcritical flow shows most of the qualitative character of a strongly supercritical flow. This result supports previous suggestions of the important role of background time dependence in maintaining the atmospheric and oceanic synoptic eddy field.

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40

Soualhi, Abdenour, Bilal El Yousfi, Hubert Razik, and Tianzhen Wang. "A Novel Feature Extraction Method for the Condition Monitoring of Bearings." Energies 14, no. 8 (April 20, 2021): 2322. http://dx.doi.org/10.3390/en14082322.

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This paper presents an innovative approach to the extraction of an indicator for the monitoring of bearing degradation. This approach is based on the principles of the empirical mode decomposition (EMD) and the Hilbert transform (HT). The proposed approach extracts the temporal components of oscillating vibration signals called intrinsic mode functions (IMFs). These components are classified locally from the highest frequencies to the lowest frequencies. By selecting the appropriate components, it is possible to construct a bank of self-adaptive and automatic filters. Combined with the HT, the EMD allows an estimate of the instantaneous frequency of each IMF. A health indicator called the Hilbert marginal spectrum density is then extracted in order to detect and diagnose the degradation of bearings. This approach was validated on two test benches with variable speeds and loads. The obtained results demonstrated the effectiveness of this approach for the monitoring of ball and roller bearings.

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41

L’Heureux, Ivan. "Diagenetic Self-Organization and Stochastic Resonance in a Model of Limestone-Marl Sequences." Geofluids 2018 (2018): 1–18. http://dx.doi.org/10.1155/2018/4968315.

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Banded patterns in limestone-marl sequences (“rhythmites”) form widespread sediments typical of shallow marine environments. They are characterized by alternations of limestone-rich layers and softer calcareous-clayey material (marl) extending over hundreds of meters with a thickness of a few tens of meters. The banded sequences are usually thought to result from systematic variations in the external environment, but the pattern may be distorted by diagenetic nonlinear processes. Here, we present a reactive-transport model for the formation of banded patterns in such a system. The model exhibits interesting features typical of nonlinear dynamical systems: (i) the existence of self-organized oscillating patterns between a calcite-rich mode (“limestone”) and a calcite-poor one (“marl”) for fixed environmental conditions and (ii) bistability between these two modes. We then illustrate the phenomena of stochastic resonance, whereby the multistable system is driven by a small external periodic signal (the 100,000 years’ Milankovitch cycle comes to mind) that is too weak to generate oscillations between the states on its own. In the presence of random fluctuations, however, the system generates transitions between the calcite-rich and calcite-poor states in statistical synchrony with the external forcing. The signal-to-noise ratio exhibits many maxima as the noise strength is varied. Hence, this amplification effect is maximized for specific values of the noise strength.

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42

Oberleithner, Kilian, Lothar Rukes, and Julio Soria. "Mean flow stability analysis of oscillating jet experiments." Journal of Fluid Mechanics 757 (September 19, 2014): 1–32. http://dx.doi.org/10.1017/jfm.2014.472.

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AbstractLinear stability analysis (LSA) is applied to the mean flow of an oscillating round jet with the aim of investigating the robustness and accuracy of mean flow stability wave models. The jet’s axisymmetric mode is excited at the nozzle lip through a sinusoidal modulation of the flow rate at amplitudes ranging from 0.1 % to 100 %. The instantaneous flow field is measured via particle image velocimetry (PIV) and decomposed into a mean and periodic part utilizing proper orthogonal decomposition (POD). Local LSA is applied to the measured mean flow adopting a weakly non-parallel flow approach. The resulting global perturbation field is carefully compared with the measurements in terms of spatial growth rate, phase velocity, and phase and amplitude distribution. It is shown that the stability wave model accurately predicts the excited flow oscillations during their entire growth phase and during a large part of their decay phase. The stability wave model applies over a wide range of forcing amplitudes, showing no pronounced sensitivity to the strength of nonlinear saturation. The upstream displacement of the neutral point and the successive reduction of gain with increasing forcing amplitude is very well captured by the stability wave model. At very strong forcing ($\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}{>}40\, \%$), the flow becomes essentially stable to the axisymmetric mode. For these extreme cases, the prediction deteriorates from the measurements due to an interaction of the forced wave with the geometric confinement of the nozzle. Moreover, the model fails far downstream in a region where energy is transferred from the oscillation back to the mean flow. This study supports previously conducted mean flow stability analysis of self-excited flow oscillations in the cylinder wake and in the vortex breakdown bubble and extends the methodology to externally forced convectively unstable flows. The high accuracy of mean flow stability wave models as demonstrated here is of great importance for the analysis of coherent structures in turbulent shear flows.

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43

Шакирова, А. А., П. П. Фирстов, and Р. И. Паровик. "Phenomenological model of the generation of the seismic mode «drumbeats» earthquakes accompanying the eruption of Kizimen volcano in 2011-2012." Вестник КРАУНЦ. Физико-математические науки, no. 4 (December 29, 2020): 86–101. http://dx.doi.org/10.26117/2079-6641-2020-33-4-86-101.

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Извержение вулкана Кизимен в 2011-2012 гг. характеризовалось устойчивым, почти равномерным выжиманием вязкого лавового потока объемом 0.3 км³. Формирование лавового потока сопровождалось возникновением квазипериодических землетрясений режима «drumbeats» с энергетическими классами Ks<7, регистрируемых на длительных временных участках. Показано, что землетрясения генерировались движением фронта вязкого лавового потока, что в практике вулканологических исследований наблюдалось впервые. Предложена феноменологическая модель генерации сейсмического режима «drumbeats». Движение фронта лавового потока по склону вулкана происходило в результате прерывистого скольжения с включением механизма «stick-slip» и возбуждением автоколебательного процесса с генерацией сейсмического режима «drumbeats». Правдоподобность феноменологической модели режима ««drumbeats» на качественном уровне подтверждена математической моделью дробного нелинейного осциллятора. The eruption of the Kizimen volcano in 2011-2012 characterized by stable, almost uniform squeezing of a viscous lava flow with a volume of 0.3 km³. The formation of the lava flow was accompanied by the occurrence of quasiperiodic earthquakes of the “drumbeats” mode with energy classes Ks < 7, recorded at long time intervals. Shown that earthquakes were generated by the movement of the front of a viscous lava flow, which was observed for the first time in the practice of volcanological research. A phenomenological model of “drumbeats” seismic mode generation is proposed. The movement of the front of the lava flow along the slope of the volcano occurred because of intermittent sliding with the inclusion of the «stick-slip» mechanism and the initiation of a self-oscillating process with the generation of a seismic mode «drumbeats». The mathematical model of a fractional nonlinear oscillator qualitatively confirms the plausibility of the phenomenological model of the “drumbeats” mode.

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44

Horváth, Róbert, Jean-François Roux, Julien Poëtte, and Béatrice Cabon. "Optoelectronic mixer with a photoconductive switch for 1550 nm wavelengths." Infocommunications journal, no. 4 (2018): 16–21. http://dx.doi.org/10.36244/icj.2018.4.3.

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We demonstrate an optoelectronic mixer based on an ultrafast InGaAs photoconductive switch and its use in an innovative heterodyne detection system for Radio over Fibre transmission. The advantage of the proposed switch is its relatively flat response curve in a wide frequency range up to 67 GHz. Two mixing schemes are presented through I-Q modulated data-stream down-conversion. The data can modulate either the electrical signal or the optical signal. In case the electrical signal is modulated, a mode-locked semiconductor laser diode is used as an optical local oscillator at the self-oscillating frequency of 24.5 GHz. The InP based quantum-dash mode-locked laser emitting in the 1570 nm wavelength range is stabilized by a feedback loop and shows a low phase noise in order to increase the mixing performances of the detection apparatus. In a second experiment, the photoconductive switch is combined with a continuous wave laser to demonstrate the feasibility of down converting an optically provided data-stream with an electrical local oscillator.

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45

Chen, Zhaopin, Yongyao Li та Boris A. Malomed. "𝒫𝒯-symmetric and antisymmetric nonlinear states in a split potential box". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 376, № 2124 (11 червня 2018): 20170369. http://dx.doi.org/10.1098/rsta.2017.0369.

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We introduce a one-dimensional -symmetric system, which includes the cubic self-focusing, a double-well potential in the form of an infinitely deep potential box split in the middle by a delta-functional barrier of an effective height ε , and constant linear gain and loss, γ , in each half-box. The system may be readily realized in microwave photonics. Using numerical methods, we construct -symmetric and antisymmetric modes, which represent, respectively, the system’s ground state and first excited state, and identify their stability. Their instability mainly leads to blowup, except for the case of ε =0, when an unstable symmetric mode transforms into a weakly oscillating breather, and an unstable antisymmetric mode relaxes into a stable symmetric one. At ε >0, the stability area is much larger for the -antisymmetric state than for its symmetric counterpart. The stability areas shrink with increase of the total power, P . In the linear limit, which corresponds to , the stability boundary is found in an analytical form. The stability area of the antisymmetric state originally expands with the growth of γ , and then disappears at a critical value of γ . This article is part of the theme issue ‘Dissipative structures in matter out of equilibrium: from chemistry, photonics and biology (part 1)’.

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46

PAAR, N., T. NIKŠIĆ, D. VRETENAR, and P. RING. "RELATIVISTIC DESCRIPTION OF EXOTIC COLLECTIVE EXCITATION PHENOMENA IN ATOMIC NUCLEI." International Journal of Modern Physics E 14, no. 01 (February 2005): 29–37. http://dx.doi.org/10.1142/s0218301305002746.

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The low-lying dipole and quadrupole states in neutron rich nuclei are studied within the fully self-consistent relativistic quasiparticle random-phase approximation (RQRPA), formulated in the canonical basis of the Relativistic Hartree–Bogoliubov model (RHB), which is extended to include the density dependent interactions. In heavier nuclei, the low-lying E1 excited state is identified as a pygmy dipole resonance (PDR), i.e. as a collective mode of excess neutrons oscillating against a proton–neutron core. Isotopic dependence of the PDR is characterized by a crossing between the PDR and one-neutron separation energies. Already at moderate proton–neutron asymmetry the PDR peak is calculated above the neutron emission threshold, indicating important implications for the observation of the PDR in (γ, γ′) scattering, and on the theoretical predictions of the radiative neutron capture rates in neutron-rich nuclei. In addition, a novel method is suggested for determining the neutron skin of nuclei, based on measurement of excitation energies of the Gamow–Teller resonance relative to the isobaric analog state.

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47

Abdollahzadeh Jamalabadi, M. Y., and Moon K. Kwak. "Dynamic modeling of a galloping structure equipped with piezoelectric wafers and energy harvesting." Noise Control Engineering Journal 67, no. 3 (May 1, 2019): 142–54. http://dx.doi.org/10.3397/1/376713.

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This study presents the analytical solution and experimental investigation of the galloping energy harvesting from oscillating elastic cantilever beam with a rigid mass. A piezoelectric wafer was attached to galloping cantilever beam to harvest vibrational energy in electric charge form. Based on Euler-Bernoulli beam assumption and piezoelectric constitutive equation, kinetic energy and potential energy of system were obtained for the proposed structure. Virtual work by generated charge and galloping force applied onto the rigid mass was obtained based on Kirchhoff's law and quasistatic assumption. Nonlinear governing electro-mechanical equations were then obtained using Hamilton's principle. As the system vibrates by self-exciting force, the fundamental mode is the only one excited by galloping. Hence, multi-degreeof-freedom equation of motion is simplified to one-degree-of-freedom model. In this study, closed-form solutions for electro-mechanical equations were obtained by using multi-scale method. Using these solutions, we can predict galloping amplitude, voltage amplitude and harvested power level. Numerical and experimental results are presented and discrepancies between experimental and numerical results are fully discussed.

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48

Palies, Paul, Milos Ilak, and Robert Cheng. "Transient and limit cycle combustion dynamics analysis of turbulent premixed swirling flames." Journal of Fluid Mechanics 830 (October 5, 2017): 681–707. http://dx.doi.org/10.1017/jfm.2017.575.

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Premixed low swirling flames (methane–air and hydrogen–methane–air) are experimentally investigated for three different regimes. Stable, local transient to instability and limit cycle regimes corresponding to three distinct equivalence ratios are considered. Dynamic mode decomposition is applied to the hydrogen–air–methane flame to retrieve the modes frequencies, growth rates and spatial distributions for each regime. The results indicate that a vortical wave propagating along the flame front is associated with the transition from stability to instability. In addition, it is shown that a key effect on stability is the location of the non-oscillating (0 Hz) flame component. The phase-averaged unsteady motion of the flames over one cycle of oscillation shows the vortical wave rolling up the flame front. The Rayleigh index maps are formed to identify the region of driving and damping of the self-sustained oscillation, while the flame transfer function phase leads to the propagation mode of the perturbations along the flame front. The second mechanism identified concerns the swirl number fluctuation induced by the mode conversion. By utilizing hypotheses for the flow field and the flame structure, it is pointed out that those mechanisms are at work for both flames (methane–air and hydrogen–methane–air) and their effects on the unsteady heat release are determined. Both unsteady heat release contributions, the vortical wave induces flame surface fluctuations and swirl number oscillation induces unsteady turbulent burning velocity, are in phase opposition and of similar amplitudes.

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49

Кучин, Д. С., П. В. Лега, А. П. Орлов, А. В. Фролов, А. В. Иржак, А. М. Жихарев, А. П. Каманцев, В. В. Коледов, А. В. Шеляков та В. Г. Шавров. "Высокоскоростной композитный микроактюатор на основе сплава Ti-=SUB=-2-=/SUB=-NiCu с эффектом памяти формы". Физика твердого тела 60, № 6 (2018): 1152. http://dx.doi.org/10.21883/ftt.2018.06.45991.02m.

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AbstractSamples of microactuators are made of a bimorph composite of Ti_2NiCu alloy with a thermoelastic martensitic transition and the shape memory effect, and their response rate is investigated. The active layer of the composite actuator is a layer of the rapidly quenched Ti_2NiCu alloy, pseudoplastically prestretched, and an amorphous layer of the same alloy is used as an elastic layer. Typical sizes of the microactuator are 30 × 2 × 2 μm. The controlled amplitude of the displacement of the microactuator tip is approximately 1 μm. The response rate of the microactuator was investigated by scanning electron microscopy. Activation of the microactuator was achieved by heating when electric pulses were passed through it. Full activation of the microactuator at frequencies up to 1 kHz was demonstrated; partial activation was observed at frequencies up to 8 kHz. The possibility of operating the device in a self-oscillating mode at frequencies of the order of 100 kHz is demonstrated.

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50

Abramov, Yuriy, Oleksii Basmanov, Valentina Krivtsova, Andrey Mikhayluk, and Oleksandra Mikhayluk. "Developing an algorithm for monitoring gas generators of hydrogen storage and supply systems." EUREKA: Physics and Engineering, no. 2 (March 31, 2022): 45–54. http://dx.doi.org/10.21303/2461-4262.2022.002262.

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In relation to the main element of the hydrogen storage and supply system based on the hydro-reacting composition – the gas generator – an algorithm for its control has been developed. The development of such an algorithm is carried out in three stages. At the first stage, the problem of formalizing the hydrogen generation process is solved. Formalization of this process is carried out using the transfer function of the gas generator. The use of the criterion for the minimum error of the mismatch of the given amplitude-frequency characteristics of the gas generator allows to represent its transfer function in the form of a transfer function of the inertial link. At the second stage, the problem of determining the conditions for the occurrence of self-oscillations in the pressure stabilization subsystem is solved. A prerequisite for the emergence of a self-oscillating mode of operation of the hydrogen storage and supply system is the presence of a relay static characteristic of the pressure sensor. For the characteristic parameters of such a system, the ranges of values of the parameters of self-oscillations, frequencies and amplitudes, are determined. For these parameters, analytical expressions are obtained, which include the main parameters of the pressure stabilization subsystem in the hydrogen storage and supply system. At the third stage, the problem of forming a gas generator control algorithm is solved. As a test action in the implementation of the control algorithm, self-oscillations in the pressure stabilization subsystem are used. The control algorithm for the gas generator of the hydrogen storage and supply system includes determining the parameters of self-oscillations and comparing their values with the values obtained a priori. A typical diagram of a hydrogen storage and supply system is presented, in which the developed gas generator control algorithm is implemented

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