Articoli di riviste: "Conversion de modes"

1

Zhong, Yanan, Chuxuan Lin, Juncheng Fang, Ting Lei e Xiaocong Yuan. "LP modes exchange based on multiplane light conversion". Chinese Optics Letters 22, n. 3 (2024): 030602. http://dx.doi.org/10.3788/col202422.030602.

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Nikitin, A. Yu, David Artigas, Lluis Torner, F. J. García-Vidal e L. Martín-Moreno. "Polarization conversion spectroscopy of hybrid modes". Optics Letters 34, n. 24 (15 dicembre 2009): 3911. http://dx.doi.org/10.1364/ol.34.003911.

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3

Zheng, L. J., e M. Furukawa. "Current-interchange tearing modes: Conversion of interchange-type modes to tearing modes". Physics of Plasmas 17, n. 5 (maggio 2010): 052508. http://dx.doi.org/10.1063/1.3425857.

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4

Vu, Alex, Leonard J. Bond e Sunil K. Chakrapani. "Numerical Study of Mode Conversion between Fundamental Lamb and Rayleigh Waves". Applied Sciences 13, n. 9 (1 maggio 2023): 5613. http://dx.doi.org/10.3390/app13095613.

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Abstract (sommario):

This article reports the findings of a numerical study of mode conversion between fundamental Lamb and Rayleigh waves and vice versa in quarter and half spaces. Fundamental Lamb wave (A0 and S0) propagation in a plate attached to a quarter space and the subsequent mode conversion to a Rayleigh wave was studied using finite element analysis. B-Scans show that a beat-like phenomenon can be observed for the R → L conversion and a generation length can be observed for the L → R conversion. The quarter-space model was also used to study the Rayleigh to Lamb mode conversion. Two hypotheses were developed based on the observed mode conversion efficiencies: (a) the main driving factor of mode conversion between Lamb and Rayleigh waves is the grazing incidence of bulk modes and (b) due to scattering and diffraction, the modes will require a generation length to stabilize in amplitude. Both hypotheses were tested and confirmed using numerical models, including a half-space model to study the diffraction of bulk waves from an incident Lamb wave. The results are of significance for nondestructive evaluation of complex structures where such structural discontinuities exist and it becomes important to understand the fundamental mode conversion phenomenon.

5

Huang, Wanxia, Chaogang Li, Maosheng Wang, Yong Zhou, Cunyuan Zhu, Kuanguo Li, Xinyan Yang e Fabao Zhang. "Modes conversion due to plasmons induced transparency". Physics Letters A 383, n. 13 (aprile 2019): 1520–25. http://dx.doi.org/10.1016/j.physleta.2019.02.003.

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6

Freedman, A. "Conversion modes in a free elastic plate". Journal of Sound and Vibration 145, n. 3 (marzo 1991): 391–407. http://dx.doi.org/10.1016/0022-460x(91)90110-6.

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7

Xu, Jun Jun, Hao Chi Zhang, Qian Zhang e Tie Jun Cui. "Efficient conversion of surface-plasmon-like modes to spatial radiated modes". Applied Physics Letters 106, n. 2 (12 gennaio 2015): 021102. http://dx.doi.org/10.1063/1.4905580.

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8

Wang, Shixiong, Yilin Zhang e Jianjia Yi. "Design and Test of Embedded Reconfigurable Mode Converter Based on Spontaneous Deformable Materials". Materials 16, n. 19 (27 settembre 2023): 6420. http://dx.doi.org/10.3390/ma16196420.

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Abstract (sommario):

The mode converter, as a passive mode conversion device in transmission lines, is well-investigated and widely implemented in various electromagnetic systems. However, most traditional mode converters can only realize a single conversion mode. Thus, a mode converter achieving multiple controllable output modes is urgently needed. In this paper, a reconfigurable mode converter operating in the microwave range is achieved by embedding a deformable all-dielectric material with quadrilateral shape into a rectangular waveguide based on coupled-mode theory. It can achieve different target modes with controllable output for the same input by exciting the deformable all-dielectric material. The design principle of the mode converter is expounded concretely and simulation is carried out using HFSS software 2022 R2. Experimental results, consisting of the simulation results, demonstrate that the proposed mode converter can achieve various mode conversions with mode purity higher than 95%. This article innovatively applies deformable materials to waveguide mode conversion, expanding the application of deformable memory materials in electromagnetic devices.

9

Xu, Shibo, e Alexey Stovas. "Estimation of the conversion point position in elastic orthorhombic media". GEOPHYSICS 84, n. 1 (1 gennaio 2019): C15—C25. http://dx.doi.org/10.1190/geo2018-0375.1.

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Determination of the conversion point position is very important to carry out seismic processing in the common conversion point gather of converted wave data. The anisotropic effect is very obvious for a converted wave when estimating the physical and processing parameters from real data. To estimate the conversion point in an elastic orthorhombic (ORT) medium, we have defined an explicit rational form approximation for the radial coordinate of the conversion point for converted [Formula: see text], [Formula: see text], and [Formula: see text] waves. To obtain the approximation coefficients, the Taylor series approximation in the corresponding vertical slowness for three pure wave modes is applied. The coefficients in our proposed approximation are computed within two vertical symmetry planes. The difference between the acquisition azimuth and the azimuth of the conversion point position is analyzed for different combinations of the wave modes. The accuracy of the conversion point position estimation for three ORT models is illustrated in the numerical examples. One can see from the results that for converted [Formula: see text] and [Formula: see text] waves, our approximation is very accurate in estimating the conversion point position regardless of the tested ORT model. For a converted [Formula: see text] wave, due to the existence of cusps, triplications, and shear singularities, the error in conversion point estimation is relatively larger compared with PS-waves in the vicinity of the singularity point.

10

Nikitov, S. A., e Ph Tailhades. "Optical modes conversion in magneto-photonic crystal waveguides". Optics Communications 199, n. 5-6 (dicembre 2001): 389–97. http://dx.doi.org/10.1016/s0030-4018(01)01583-8.

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11

Ma, Yancheng, Liang Fang e Guoan Wu. "Fiber-guided modes conversion using superposed helical gratings". Optics Communications 386 (marzo 2017): 1–5. http://dx.doi.org/10.1016/j.optcom.2016.11.007.

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12

Mertens, K., M. Sennewald e H. J. Schmitt. "Polarization conversion by hybrid modes: Theory and applications". Radio Science 31, n. 6 (novembre 1996): 1773–79. http://dx.doi.org/10.1029/96rs01514.

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13

Dios, Federico, Alexander B. Shvartsburg, David Artigas e Ferran Canal. "Nonlinear resonant conversion of modes in optical waveguides". Optics Communications 118, n. 1-2 (luglio 1995): 28–34. http://dx.doi.org/10.1016/0030-4018(95)91592-p.

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14

Oshima, N., e M. Koike. "Development of a parameterization of black carbon aging for use in general circulation models". Geoscientific Model Development 6, n. 2 (1 marzo 2013): 263–82. http://dx.doi.org/10.5194/gmd-6-263-2013.

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Abstract. A parameterization of black carbon (BC) aging in the atmosphere is developed for use in general circulation models (GCMs) that separately treat hydrophobic BC and hydrophilic BC modes but do not explicitly calculate the aging processes of BC. The rate of BC aging is expressed as the conversion rate from hydrophobic BC to hydrophilic BC modes (i.e., inverse of the e-folding time of the conversion, 1/τBC). In this study, the conversion rates are estimated using results of detailed calculations by a size and mixing state resolved aerosol box model with numerous initial conditions. We introduce a new concept, the hydrophobic-BC-mass-normalized coating rate (VBC), defined as the rate of increase of the mass concentration of condensed materials on hydrophobic BC normalized by the hydrophobic BC mass concentration. Although the conversion rate largely varies depending on the atmospheric conditions and the concentrations of chemical species, we find that the variations of the conversion rate are generally expressed well by a unique function of VBC for given lognormal size distributions of hydrophobic BC. The parameterized conversion rate is expressed as a function of VBC, which enables the representation of diurnal and seasonal variations of the BC aging rate and its spatial differences in polluted and clean air, while other widely used constant conversion rates cannot. Application of our newly developed parameterization to GCMs will provide more reliable estimates of the spatial distribution of BC and its radiative effects at regional and global scales.

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Oshima, N., e M. Koike. "Development of a parameterization of black carbon aging for use in general circulation models". Geoscientific Model Development Discussions 5, n. 2 (16 maggio 2012): 1263–93. http://dx.doi.org/10.5194/gmdd-5-1263-2012.

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Abstract. A parameterization of black carbon (BC) aging in the atmosphere is developed for use in general circulation models (GCMs) that separately treats size distributions of hydrophobic BC and hydrophilic BC using lognormal modes. The rate of BC aging is expressed as the conversion rate from hydrophobic BC to hydrophilic BC modes (i.e., inverse of the e-folding time of the conversion, 1/τBC). In this study, the conversion rates are estimated using results of detailed calculations by a size and mixing state resolved aerosol box model with numerous initial conditions. We introduce a new concept, the hydrophobic-BC-mass-normalized coating rate (VBC), defined as the rate of increase of the mass concentration of condensed materials on hydrophobic BC normalized by the hydrophobic BC mass concentration. Although the conversion rate largely varies depending on the atmospheric conditions and the concentrations of chemical species, we find that the variations of the conversion rate are generally expressed well by a unique function of VBC for given lognormal size distributions of hydrophobic BC. The parameterized conversion rate is expressed as a function of VBC, which enables the representation of diurnal and seasonal variations of the BC aging rate and its spatial differences in polluted and clean air, while other widely used constant conversion rates cannot. Application of our newly developed parameterization to GCMs will provide more reliable estimates of the spatial distribution of BC and its radiative effects at regional and global scales.

16

Bernau, Anke. "Bruno Latour and the Loving Assumptions of [REL]". Romanic Review 111, n. 1 (1 maggio 2020): 151–72. http://dx.doi.org/10.1215/00358118-8007992.

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Abstract In An Inquiry into the Modes of Existence, which addresses itself to the profound challenge of how to “compose” a common world in the Anthropocene, Bruno Latour proposes that the mode of religion [REL] offers a model for all the others—that of reprise. Emerging from the practice of biblical exegesis, reprise refers to an open-ended process of meaning making opposed to the rigid certainties of fundamentalism. [REL] also contributes a concept of radical transformation through love (“conversion”). For Latour, two events from the Virgin Mary’s life—the Annunciation and the Assumption—illustrate reprise and conversion, both of which are necessary in coming to terms with monogeism, the knowledge that there is only one world. This essay examines Latour’s proposed relationship between reprise and conversion through a consideration of late medieval Marian devotion. Focusing on vernacular accounts of Mary’s Assumption, it argues that reprise leads to violent as well as loving conversions; indeed, violence can proceed in the name of love. The essay concludes that composition, reprise, and conversion come together in ways that trouble late medieval accounts of the Assumption, the mode of religion, and life in the Anthropocene.

17

Serra-Garcia, Marc, Miguel Molerón e Chiara Daraio. "Tunable, synchronized frequency down-conversion in magnetic lattices with defects". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 376, n. 2127 (23 luglio 2018): 20170137. http://dx.doi.org/10.1098/rsta.2017.0137.

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We study frequency conversion in nonlinear mechanical lattices, focusing on a chain of magnets as a model system. We show that, by inserting mass defects at suitable locations, we can introduce localized vibrational modes that nonlinearly couple to extended lattice modes. The nonlinear interaction introduces an energy transfer from the high-frequency localized modes to a low-frequency extended mode. This system is capable of autonomously converting energy between highly tunable input and output frequencies, which need not be related by integer harmonic or subharmonic ratios. It is also capable of obtaining energy from multiple sources at different frequencies with a tunable output phase, due to the defect synchronization provided by the extended mode. Our lattice is a purely mechanical analogue of an opto-mechanical system, where the localized modes play the role of the electromagnetic field and the extended mode plays the role of the mechanical degree of freedom. This article is part of the theme issue ‘Nonlinear energy transfer in dynamical and acoustical systems’.

18

Quiroga-Teixeiro, M. L., D. Anderson, A. Berntson e M. Lisak. "Compression of optical solitons by conversion of nonlinear modes". Journal of the Optical Society of America B 12, n. 6 (1 giugno 1995): 1110. http://dx.doi.org/10.1364/josab.12.001110.

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19

Gür, Turgut M. "Utilization Modes for Solid Carbon Conversion in Fuel Cells". ECS Transactions 25, n. 2 (17 dicembre 2019): 1099–108. http://dx.doi.org/10.1149/1.3205637.

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20

Sementsov, D. I., e A. M. Shutyi. "Conversion of waveguide modes in nonuniformly magnetized planar structures". Optics and Spectroscopy 88, n. 3 (marzo 2000): 423–26. http://dx.doi.org/10.1134/1.626812.

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21

Qian, Cheng, Ka Hei Choi, Raymond P. H. Wu, Yongliang Zhang, Kai Guo e Kin Hung Fung. "Nonlinear frequency up-conversion via double topological edge modes". Optics Express 26, n. 4 (16 febbraio 2018): 5083. http://dx.doi.org/10.1364/oe.26.005083.

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22

Pernod, P., e V. Preobrazhensky. "Nonlinear conversion of magnetoelastic modes in a magnetostrictive plate". Journal of Magnetism and Magnetic Materials 185, n. 1 (maggio 1998): 127–30. http://dx.doi.org/10.1016/s0304-8853(98)00035-3.

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23

Shutyi, A. M., e D. I. Sementsov. "Conversion of optical modes in an absorbing magnetogyrotropic waveguide". Technical Physics 43, n. 6 (giugno 1998): 701–7. http://dx.doi.org/10.1134/1.1259057.

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24

Zolotovskii, I. O., e D. I. Sementsov. "Conversion of waveguide modes in a periodic optical fiber". Russian Physics Journal 41, n. 3 (marzo 1998): 227–32. http://dx.doi.org/10.1007/bf02766416.

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25

Baitin, Dmitry M., Irina V. Bakhlanova, Darya V. Chervyakova, Yury V. Kil, Vladislav A. Lanzov e Michael M. Cox. "Two RecA Protein Types That Mediate Different Modes of Hyperrecombination". Journal of Bacteriology 190, n. 8 (22 febbraio 2008): 3036–45. http://dx.doi.org/10.1128/jb.01006-07.

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ABSTRACT RecAX53 is a chimeric variant of the Escherichia coli RecA protein (RecAEc) that contains a part of the central domain of Pseudomonas aeruginosa RecA (RecAPa), encompassing a region that differs from RecAEc at 12 amino acid positions. Like RecAPa, this chimera exhibits hyperrecombination activity in E. coli cells, increasing the frequency of recombination exchanges per DNA unit length (FRE). RecAX53 confers the largest increase in FRE observed to date. The contrasting properties of RecAX53 and RecAPa are manifested by in vivo differences in the dependence of the FRE value on the integrity of the mutS gene and thus in the ratio of conversion and crossover events observed among their hyperrecombination products. In strains expressing the RecAPa or RecAEc protein, crossovers are the main mode of hyperrecombination. In contrast, conversions are the primary result of reactions promoted by RecAX53. The biochemical activities of RecAX53 and its ancestors, RecAEc and RecAPa, have been compared. Whereas RecAPa generates a RecA presynaptic complex (PC) that is more stable than that of RecAEc, RecAX53 produces a more dynamic PC (relative to both RecAEc and RecAPa). The properties of RecAX53 result in a more rapid initiation of the three-strand exchange reaction but an inability to complete the four-strand transfer. This indicates that RecAX53 can form heteroduplexes rapidly but is unable to convert them into crossover configurations. A more dynamic RecA activity thus translates into an increase in conversion events relative to crossovers.

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Chen, Chao, Jiyang Zhang, Nuan Wang, Lincheng Shen e Yiyong Li. "Conversion control of a tilt tri-rotor unmanned aerial vehicle with modeling uncertainty". International Journal of Advanced Robotic Systems 18, n. 4 (1 luglio 2021): 172988142110270. http://dx.doi.org/10.1177/17298814211027033.

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The tilt-rotor unmanned aerial vehicle (TRUAV) has vertical take-off and landing and high-speed flight capabilities through conversion and reconversion modes, thereby presenting wide application prospects. This article presents a compact tilt tri-rotor UAV. For flying in the conversion mode, the TRUAV needs to realize the transition of two control logic and two kinds of actuators in both of the rotor and fixed-wing modes, achieving the control of the multi-input multioutput, input nonaffine, and nonlinear multichannel cross-coupling UAV system. Furthermore, the lateral dynamics of a tilt tri-rotor UAV is more unstable for unpaired rotors. These system characteristics present a great challenge to conversion control. To solve these problems, the nonlinear dynamic model of the vehicle in the conversion mode is provided. Furthermore, a cascade control system consisting of position control, velocity control, angle control, angular velocity control, and control mixer is proposed. The simulation result of the control system shows steady flight and a fast transition in the conversion mode with modeling uncertainty in case of no wind.

27

Huang, Zesen, Chen Shi, Nikos Sioulas e Marco Velli. "Conservation of Total Wave Action in the Expanding Solar Wind". Astrophysical Journal 935, n. 1 (1 agosto 2022): 60. http://dx.doi.org/10.3847/1538-4357/ac74c5.

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Abstract The conservation of wave action in moving plasmas has been well known for over half a century. However, wave action is not conserved when multiple wave modes propagate and coexist close to the degeneration condition (where the sound speed equals the Alfvén speed, i.e., plasma β ∼ 1). Here, we show that the violation of conservation is due to wave mode conversion, and that the total wave action summed over the interacting modes is still conserved. Though the result is general, we focus on MHD waves and identify three distinctive mode-conversion mechanisms, i.e., degeneracy, linear mode conversion, and resonance, and provide an intuitive physical picture for the mode-conversion processes. We use one-dimensional MHD simulations with the Expanding Box Model to simulate the nonlinear evolution of monochromatic MHD waves in the expanding solar wind. The simulation results validate the theory; total wave action therefore remains an interesting diagnostic for studies of waves and turbulence in the solar wind.

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Ghosh, Dhrubajyoti, e Susmita Sen. "Ecological History of Calcutta's Wetland Conversion". Environmental Conservation 14, n. 3 (1987): 219–26. http://dx.doi.org/10.1017/s0376892900016416.

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The interest in the wetlands ecosystems on Calcutta's periphery should be understood in the context of the search for development alternatives—for locally-adapted, appropriate modes of development rather than transplantation of alien models. Too often, planners look abroad for ideas without realizing that appropriate principles and practices are present in their own backyards. We are now coming to understand that ecodevelopment entails bringing together creative techniques with the ways in which people perceive and approach the issues of quality of life through environmental changes that are in the forefront of planning debates. Human and ecologically-sound planning requires an integration of such understanding with suitable techniques and procedures.

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Mjølhus, Einar. "Generalized Budden resonance tunnelling, with application to linear conversion nearly parallel to magnetic field". Journal of Plasma Physics 38, n. 1 (agosto 1987): 1–26. http://dx.doi.org/10.1017/s002237780001237x.

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A model of linear wave conversion problems is formulated, which forms a natural generalization of the Budden resonance tunnelling model. The structure of the model is such as to conserve energy flux, and also is such as to allow explicit solution in terms of contour integrais. An arbitrary number of wave modes may participate. Explicit expressions for the conversion coefficients in terms of quantities derivable from the dispersion relations are obtained. A standard way of extending the model, by which resonant absorption is retrieved as conversion into an additional short wave mode, is included. The formulae obtained, are shown to include a complete solution to the problem of linear conversion in a magnetized plasma when the waves are nearly parallel to the magnetic field.

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Qi, Wei, Yu Yu e Xinliang Zhang. "On-chip arbitrary-mode spot size conversion". Nanophotonics 9, n. 14 (6 agosto 2020): 4365–72. http://dx.doi.org/10.1515/nanoph-2020-0328.

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AbstractManipulating on-chip optical modes via components in analogy with free-space devices provides intuitional light control, and this concept has been adopted to implement single-lens–assisted spot size conversion using integrated device. However, the reported schemes have been demonstrated only for fundamental mode, while high-order or irregular modes are preferred in specific applications. The 4-f system is widely used in Fourier optics for optical information processing. Under the inspiration of the 4-f system and the beam expander in bulk optics, a spot size converter (SSC) with two metamaterial-based graded-index waveguides is proposed and demonstrated. The proposed device is capable of widening an arbitrary mode while preserving its profile shape. Compared with conventional SSC using adiabatic taper, the footprint can be reduced by 91.5% under a same intermode crosstalk. Experimentally, an expansion ratio of five is demonstrated for regular modes. Furthermore, for an irregular mode, the functionality is numerically verified without structure modification. This work offers a universal solution to on-chip spot size conversion and may broaden the on-chip application prospects of Fourier optics.

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Li, Z., e P. Xia. "Aeroelastic modelling and stability analysis of tiltrotor aircraft in conversion flight". Aeronautical Journal 122, n. 1256 (12 settembre 2018): 1606–29. http://dx.doi.org/10.1017/aer.2018.93.

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ABSTRACTIn conversion flight, the aeroelastic modelling of tiltrotor aircraft needs to consider the unsteady effect of the rotor wake bending due to the rotor tilting. In this paper, the unsteady models of the rotor wake bending and dynamic inflow have been introduced into the aeroelastic modelling of the tiltrotor aircraft in conversion flight by using Hamilton’s generalized principle. The method for solving the aeroelastic stability of tiltrotor aircraft in conversion flight has been established by using the small perturbation theory and the Floquet theory. The influences of unsteady dynamic inflow on trim control inputs and aeroelastic stability of a tiltrotor aircraft in conversion flight were calculated and analysed. The calculation results show that the required collective pitch increases with the pylon tilting forward and the unsteady inflow is trimmed primarily by the lateral cyclic pitch of the rotor. The wake bending unsteady dynamic inflow can obviously reduce the stability of the flapping modes of the rotor, and have no obvious influence on the lag modes of the rotor and the motion modes of the wing. The instability of tiltrotor occurs in the chordwise bending mode of the wing when the pylon tilts to a certain angle in high speed forward flight.

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Alexeyev, C. N., S. S. Alieva, E. V. Barshak, B. P. Lapin e M. A. Yavorsky. "Influence of attenuation on the generation of optical vortices in multihelicoidal optical fibers". Journal of Physics: Conference Series 2103, n. 1 (1 novembre 2021): 012149. http://dx.doi.org/10.1088/1742-6596/2103/1/012149.

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Abstract In this paper we have studied influence of attenuation on conversion processes of the fundamental mode (FM) in multihelicoidal optical fibers (MHF) in the vicinity of the point of accidental spectrum degeneracy within the framework of the scalar approximation. To this end, we have obtained expressions for modes of the MHF, which consist of the FM and an optical vortex (OV), and shown that conversion of the FM into the OV takes place. The difference in the attenuation coefficients for the partial fields of MHF’s modes leads to deterioration in the conversion process even with an ideal system’s tuning. At sufficiently large values of attenuation coefficients the conversion of the incoming FM into the vortex vanishes. Also we have shown the presence of exceptional point (EP) in the spectra of modes of the MHF and demonstrated enhanced sensitivity of the fiber in the vicinity of the EP to perturbations.

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Lu, Ke, Hongyuan Tian, Pan Zhen, Senkui Lu e Renliang Chen. "Conversion Flight Control for Tiltrotor Aircraft via Active Disturbance Rejection Control". Aerospace 9, n. 3 (12 marzo 2022): 155. http://dx.doi.org/10.3390/aerospace9030155.

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The tiltrotor aircraft consists of three primary flight modes, which are helicopter flight mode in low forward speed flight, airplane flight mode in high forward speed flight and conversion flight mode. This paper presents an active disturbance rejection controller for tiltrotor aircraft conversion flight. First, a tiltrotor aircraft flight dynamics model is developed and verified. Then, conversion flight control laws, designed via the active disturbance rejection control (ADRC) and sliding mode control (SMC) techniques, are proposed for the tiltrotor aircraft with model uncertainties and external disturbance, which are estimated with an extended state observer. Finally, the simulation of automatic conversion flight is carried out, which shows the effectiveness of the developed controller.

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Harder, G., V. Ansari, T. J. Bartley, B. Brecht e C. Silberhorn. "Harnessing temporal modes for multi-photon quantum information processing based on integrated optics". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 375, n. 2099 (26 giugno 2017): 20160244. http://dx.doi.org/10.1098/rsta.2016.0244.

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In the last few decades, there has been much progress on low loss waveguides, very efficient photon-number detectors and nonlinear processes. Engineered sum-frequency conversion is now at a stage where it allows operation on arbitrary temporal broadband modes, thus making the spectral degree of freedom accessible for information coding. Hereby the information is often encoded into the temporal modes of a single photon. Here, we analyse the prospect of using multi-photon states or squeezed states in different temporal modes based on integrated optics devices. We describe an analogy between mode-selective sum-frequency conversion and a network of spatial beam splitters. Furthermore, we analyse the limits on the achievable squeezing in waveguides with current technology and the loss limits in the conversion process. This article is part of the themed issue ‘Quantum technology for the 21st century’.

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Hafeez, Saima, Jianguo Yu, Fahim Aziz Umrani, Wang Yun e Muhammad Ishfaq. "A Multiband and Multifunctional Metasurface for Linear and Circular Polarization Conversion in Reflection Modes". Crystals 14, n. 3 (8 marzo 2024): 266. http://dx.doi.org/10.3390/cryst14030266.

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Multifunctional integrated meta-devices are the demand of modern communication systems and are given a lot of attention nowadays. Most of the research has focused on either cross-polarization conversion (CPC) or linear-to-circular (LP–CP) conversion. However, simultaneously realizing multiple bands with good conversion efficiency remains crucial. This paper proposes a multiband and multifunctional dual reflective polarization converter surface capable of converting a linearly polarized (LP) wave into a circularly polarized (CP) wave, in frequency bands of 12.29–12.63 GHz, 16.08–24.16 GHz, 27.82–32.21 GHz, 33.75–38.74 GHz, and 39.70–39.79 GHz, with 3 dB axial ratio bandwidths of 2.7%, 40.15%, 14.6%, 13.76%, and 0.2%, respectively. Moreover, the converter is capable of achieving CPC with a polarization conversion ratio (PCR) that exceeds 95%, within the frequency ranges of 13.10–14.72 GHz, 25.43–26.00, 32.46–32.56 GHz, and 39.14–39.59 GHz. In addition, to identify the fundamental cause of the CPC and LP–CP conversion, a comprehensive theoretical investigation is provided. Furthermore, the surface current distribution patterns at different frequencies are investigated to analyze the conversion phenomena. A sample prototype consisting of 20 × 20 unit cells was fabricated and measured, verifying our design and the simulated results. The proposed structure has potential applications in satellite communications, radar, stealth technologies, and reflector antennas.

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Han, Ya, Yan-Ge Liu, Zhi Wang, Wei Huang, Lei Chen, Hong-Wei Zhang e Kang Yang. "Controllable all-fiber generation/conversion of circularly polarized orbital angular momentum beams using long period fiber gratings". Nanophotonics 7, n. 1 (1 gennaio 2018): 287–93. http://dx.doi.org/10.1515/nanoph-2017-0047.

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AbstractMode-division multiplexing (MDM) is a promising technology for increasing the data-carrying capacity of a single few-mode optical fiber. The flexible mode manipulation would be highly desired in a robust MDM network. Recently, orbital angular momentum (OAM) modes have received wide attention as a new spatial mode basis. In this paper, we firstly proposed a long period fiber grating (LPFG) system to realize mode conversions between the higher order LP core modes in four-mode fiber. Based on the proposed system, we, for the first time, demonstrate the controllable all-fiber generation and conversion of the higher order LP core modes to the first and second order circularly polarized OAM beams with all the combinations of spin and OAM. Therefore, the proposed LPFG system can be potentially used as a controllable higher order OAM beam switch and a physical layer of the translating protocol from the conventional LP modes communication to the OAM modes communication in the future mode carrier telecommunication system and light calculation protocols.

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Kašparová, Petra, e Tereza Michalová. "SECI Knowledge Model and Opportunities of Engaging Business Intelligence by Maturity Level: Case Study at Selected Businesses in the Czech Republic". Journal of Intelligence Studies in Business 13, n. 2 (2 ottobre 2023): 6–24. http://dx.doi.org/10.37380/jisib.v13i2.1080.

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This study aims to examine the possibilities of engaging business intelligence (BI) with regard to the level of maturity within systemic knowledge management (KM). The individual modes of knowledge sharing and conversion are illustrated in Nonaka’s SECI model that defines four conversion modes of knowledge exchange: socialisation, externalisation, combination and internalisation. The submitted case study presents the current and potential engagement of BI when applying knowledge conversion tools in three Czech organisations of various sizes. Most businesses use both tools (BI and KM) but they are often not able to coordinate their joint implementation in a suitable way. Currently, the results of the case study indicate a more optimal adaptation in the environment of larger businesses. However, the addressed businesses, regardless of their size, most often see the potential and great opportunities of the tools in the combination mode in the future.

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Falahat, Saeed, Jonas Nycander, Fabien Roquet e Moundheur Zarroug. "Global Calculation of Tidal Energy Conversion into Vertical Normal Modes". Journal of Physical Oceanography 44, n. 12 (26 novembre 2014): 3225–44. http://dx.doi.org/10.1175/jpo-d-14-0002.1.

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Abstract A direct calculation of the tidal generation of internal waves over the global ocean is presented. The calculation is based on a semianalytical model, assuming that the internal tide characteristic slope exceeds the bathymetric slope (subcritical slope) and the bathymetric height is small relative to the vertical scale of the wave, as well as that the horizontal tidal excursion is smaller than the horizontal topographic scale. The calculation is performed for the M2 tidal constituent. In contrast to previous similar computations, the internal tide is projected onto vertical eigenmodes, which gives two advantages. First, the vertical density profile and the finite ocean depth are taken into account in a fully consistent way, in contrast to earlier work based on the WKB approximation. Nevertheless, the WKB-based total global conversion follows closely that obtained using the eigenmode decomposition in each of the latitudinal and vertical distributions. Second, the information about the distribution of the conversion energy over different vertical modes is valuable, since the lowest modes can propagate over long distances, while high modes are more likely to dissipate locally, near the generation site. It is found that the difference between the vertical distributions of the tidal conversion into the vertical modes is smaller for the case of very deep ocean than the shallow-ocean depth. The results of the present work pave the way for future work on the vertical and horizontal distribution of the mixing caused by internal tides.

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Bernas, Marta, Kinga Zolnacz, Maciej Napiorkowski, Gabriela Statkiewicz-Barabach e Waclaw Urbanczyk. "Conversion of LP11 modes to vortex modes in a gradually twisted highly birefringent optical fiber". Optics Letters 46, n. 18 (3 settembre 2021): 4446. http://dx.doi.org/10.1364/ol.433952.

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Riedl, J. M., T. Van Doorsselaere e I. C. Santamaria. "Wave modes excited by photospheric p-modes and mode conversion in a multi-loop system". Astronomy & Astrophysics 625 (maggio 2019): A144. http://dx.doi.org/10.1051/0004-6361/201935393.

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Context. Waves are ubiquitous in the solar corona and there are indications that they are excited by photospheric p-modes. However, it is unclear how p-modes in coronal loops are converted to sausage modes and transverse (kink) modes, which are observed in the corona. Aims. We aim to investigate how those wave modes are excited in the lower corona by photospheric acoustic waves. Methods. We built 3D magnetohydrostatic loop systems with multiple inclinations spanning from the photosphere to the lower corona. We then simulated these atmospheres with the MANCHA code, in which we perturb the equilibrium with a p-mode driver at the bottom of the domain. By splitting the velocity perturbation into components longitudinal, normal, and azimuthal to the magnetic flux surfaces we can study wave behavior. Results. In vertical flux tubes, we find that deformed fast sausage surface waves and slow sausage body waves are excited. In inclined flux tubes fast kink surface waves, slow sausage body waves, and either a fast sausage surface wave or a plane wave are excited. In addition, we calculate a wave conversion factor (0 ≤ C ≤ 1) from acoustic to magnetic wave behavior by taking the ratio of the mean magnetic energy flux to the sum of the mean magnetic and acoustic energy flux and compare it to a commonly used theoretical conversion factor. We find that between magnetic field inclinations of 10° to 30° those two methods lie within 40%. For smaller inclinations the absolute deviation is smaller than 0.1.

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Babu, A. R. Vijay, P. M. Venkatesh e Dr K. Suresh. "High Frequency Link Power Conversion System for Fuel cell Applications". International Journal of Engineering & Technology 7, n. 4.24 (27 novembre 2018): 1. http://dx.doi.org/10.14419/ijet.v7i4.24.21760.

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In this paper an empirical model of the air breathing (ABFC) is proposed to investigate the cell voltage verses current density characteristics and harnessing of maximum energy from natural resource whenever it’s available. The power electronic converters role is important in between source and load. Proper controller can switch the converter in the desired time and improve the system performance and stability. The mathematical model of the ABFC is built in MATLAB/Simulink. The proposed system also has boost converter, bidirectional DC-DC converter and inverter for grid and energy integration. The boost inverter/buck rectifier in this system is controlled by ANFIS controller is for better output, boost and bidirectional DC-DC converters are controlled by PID controller in closed loop. Overall operations are based on modes main controller, which control the system operation in different modes. Any variations happening in the input, storage and load parameters, the controller changes the mode and operates the system in effective way.

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Klaver, Miranda, Johan Roeland, Peter Versteeg, Hijme Stoffels e Remco van Mulligen. "God changes people: modes of authentication in Evangelical conversion narratives". Journal of Contemporary Religion 32, n. 2 (11 aprile 2017): 237–51. http://dx.doi.org/10.1080/13537903.2017.1298905.

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Beltran, Lina, Gaetano Frascella, Angela M. Perez, Robert Fickler, Polina R. Sharapova, Mathieu Manceau, Olga V. Tikhonova, Robert W. Boyd, Gerd Leuchs e Maria V. Chekhova. "Orbital angular momentum modes of high-gain parametric down-conversion". Journal of Optics 19, n. 4 (16 marzo 2017): 044005. http://dx.doi.org/10.1088/2040-8986/aa600f.

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Abbar, Sajad, e Maria Cristina Volpe. "On fast neutrino flavor conversion modes in the nonlinear regime". Physics Letters B 790 (marzo 2019): 545–50. http://dx.doi.org/10.1016/j.physletb.2019.02.002.

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ECH-CHERIF EL-KETTANI, M., P. PAREIGE e F. LUPPÉ. "Conversion de modes de Lamb à l'extrémité d'une plaque immergée". Le Journal de Physique IV 04, n. C5 (maggio 1994): C5–873—C5–876. http://dx.doi.org/10.1051/jp4:19945190.

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Enaki, Nicolae A. "Cooperative properties of multiple quantum scattering: II. Coherentlasing". Physica Scripta 99, n. 4 (1 marzo 2024): 045101. http://dx.doi.org/10.1088/1402-4896/ad2ac0.

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Abstract The description model of the multiple scattering lasers using the superposition states between the generated photons in the ensemble of bi-modes of the resonator field, we introduced a concept of indistinguishable energy portions generated in the resonator following multiple scattering. Each of these quasi-quanta has energy equal to the difference between the pumping and scattering quantum energies at each step of multiple scattering. The conversion of the photons in the external electromagnetic mode of the resonator destroys this cooperative correlation between the bi-modes and established conservation lows during the cooperative emission. The master equation containing two parameters connected with the gain of quasi-energy portions, and their annihilation due to the losses from the resonator, is proposed. The competition between these two processes is numerically studied. An attractive problem is connected with established quantum correlations between the photons belonging to non-adjacent modes of the cavity. The time behavior of the evolution of correlations between such modes is observed. This conception may be used for the teleportation of information in other modes during the multiple Raman conversion.

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Yan, Manjun, e Long Ma. "Generation of Higher-Order Hermite–Gaussian Modes via Cascaded Phase-Only Spatial Light Modulators". Mathematics 10, n. 10 (11 maggio 2022): 1631. http://dx.doi.org/10.3390/math10101631.

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The spatial distribution of higher-order Hermite–Gaussian (HG) modes is more complicated than the fundamental mode, and the characteristics of different modes and their orthogonal characteristics have essential applications in the fields of measurement, imaging, and large-capacity communications. The main issue in future applications is how to efficiently generate higher-order HG modes. The spatial light modulator has high spatial resolution and excellent maneuverability, so it is a simple and effective way to generate higher-order HG modes. Here, the efficient generation of higher-order HG modes via cascaded spatial light modulators was experimentally investigated. For the HG90 mode, the conversion efficiency is 61%. The method with high conversion efficiency has promising application potentials in biophotonics, laser physics, and quantum information.

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Cheng, Liang, Kai-Yuan Zhang, Yu-Liang Zhang e Xiao-Qi Jia. "Effect on Starting Modes on Centrifugal Pump Performance". Processes 10, n. 11 (11 novembre 2022): 2362. http://dx.doi.org/10.3390/pr10112362.

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In this paper, a small centrifugal pump experiment was conducted under conditions of power frequency startup and frequency conversion startup respectively. The evolutionary trends for hydraulic performance parameters with time were obtained, and the transient properties of the two starting modes were revealed with the help of three dimensionless coefficients. This study revealed the similarities and differences between the two starting modes. In both starting modes, the increase of the valve opening caused a time lag for the flow to reach a steady state. Compared with the power frequency startup mode, the frequency conversion startup mode had weaker shaft power shocks and was safer in practice. The dimensionless flow curves maintained a good evolutionary agreement with the corresponding flow curves. The dimensionless shaft power was extremely high at the beginning of startup and then decreased to a stable value.

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Murillo-Yarce, Duberney, Carlos Restrepo, Diego G. Lamar, Marta M. Hernando e Javier Sebastián. "Study of Multiple Discontinuous Conduction Modes in SEPIC, Ćuk, and Zeta Converters". Electronics 11, n. 22 (15 novembre 2022): 3744. http://dx.doi.org/10.3390/electronics11223744.

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In this paper, we studied the discontinuous conduction modes (DCMs) of modified versions of the SEPIC, Ćuk, and Zeta converters. The modified versions of these converters were obtained by adding an extra diode to the classical versions of these converters; thus, we obtained converters with multiple DCMs. In the case of the SEPIC and Ćuk converters, the additional diode was added in series with the inductor placed at the input port, thus resembling the connection of a four-diode bridge rectifier at the input (where these converters work as power factor correctors in AC/DC conversion). The 2 diodes of the modified versions of these converters define 4 possible conduction modes: 1 continuous conduction mode (CCM) and 3 DCMs. In this paper, the 4 conduction modes were exhaustively studied, calculating their voltage conversion ratios and the equations of the curves that define the borders between conduction modes in both open- and closed-loop operations. The conduction modes and the straight line that describes the converter operation are represented in a plane called the “k1k2 plane”. As in the case of other characteristics exhibited by the SEPIC, Ćuk, and Zeta converters, the conduction modes, the voltage conversion ratios in each conduction mode, and the boundaries between conduction modes, coincide for the three studied converters. Finally, all theoretical predictions resulting from the analysis were verified experimentally through a reconfigurable converter prototype, working as both modified SEPIC and modified Ćuk converters.

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Tian, Ying, Lichang Han, Li Yan, Jiayun Wang, Binzhen Zhang e Zan Jiao. "Optically-Controlled Terahertz Multifunctional Polarization Conversion Metasurface with Reflection and Transmission Modes". Micromachines 13, n. 9 (25 agosto 2022): 1387. http://dx.doi.org/10.3390/mi13091387.

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In the terahertz band, how integrating multiple functions into a device with a tiny unit structure is a challenge. In this paper, an optically-controlled multifunctional linear polarization conversion metasurface working in the terahertz band is proposed. The reflection and transmission polarization conversion functions can be realized by irradiating the metasurface with pump light with different wavelengths. The metasurface is designed with a multilayer structure, and a photosensitive semiconductor alone is used to control multiple functions, which makes the manipulation of multifunctional devices easy. When the photosensitive semiconductor germanium (Ge) and silicon (Si) are in different states, the metasurface can realize broadband reflection and transmission polarization conversion functions, the corresponding relative bandwidth are 102.4% and 98.9%, respectively, and the work efficiency can be regulated by pump light with different intensity and wavelength. In addition, the working principle of the metasurface is analyzed by eigenmode theory and surface current distributions. The stability of the metasurface to structural parameters and incident angles are discussed.

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