Artículos de revistas: "Propagation favorable"

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Makarewicz, Rufin y Katsuko Masuda. "Highway noise under favorable conditions of generation and propagation." Journal of the Acoustical Society of Japan (E) 19, n.º 3 (1998): 181–86. http://dx.doi.org/10.1250/ast.19.181.

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2

Masouros, Christos y Michail Matthaiou. "Space-Constrained Massive MIMO: Hitting the Wall of Favorable Propagation". IEEE Communications Letters 19, n.º 5 (mayo de 2015): 771–74. http://dx.doi.org/10.1109/lcomm.2015.2409832.

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3

Cheng, Yifeng, Lu Wang y Tim Li. "Causes of Interdecadal Increase in the Intraseasonal Rainfall Variability over Southern China around the Early 1990s". Journal of Climate 33, n.º 21 (1 de noviembre de 2020): 9481–96. http://dx.doi.org/10.1175/jcli-d-20-0047.1.

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AbstractThe southern China (SC) summer rainfall exhibits prominent intraseasonal variability, which exhibits a significant increase in the early 1990s with the turning point at 1993. The SC intraseasonal rainfall events could be divided into three categories according to different propagations, including the southward-propagating (SP) events, the northwestward-propagating (NWP) events, and the northward-propagating (NP) events. This study explores the causes of the observed interdecadal increase in the intraseasonal rainfall variability over SC by comparing the SC intraseasonal rainfall events of each category between the former decadal period (P1) and the later decadal period (P2). The result indicates that such interdecadal change is due to the more frequent NP events coming from the South China Sea (SCS). Based on the moisture and vorticity budget analysis, it is revealed that the summer mean southerly wind in the middle to lower troposphere is the dominant factor of the northward propagation over the SCS, as it could induce positive meridional moisture and vorticity advection anomalies ahead of the convection. A marked interdecadal enhancement of the summer mean southerly wind over the SCS is the cause of more frequent occurrence of NP events over SC, as it provides more favorable conditions for the northward propagation. The change of the atmospheric instability over the SCS where the NP convection perturbation originates was also investigated, but no significant change was found.

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4

Anarakifirooz, Elham y Sergey Loyka. "Favorable Propagation for Massive MIMO With Circular and Cylindrical Antenna Arrays". IEEE Wireless Communications Letters 11, n.º 3 (marzo de 2022): 458–62. http://dx.doi.org/10.1109/lwc.2021.3132255.

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Fathy, Abdallah, Fatma Newagy y Wagdy Refaat Anis. "Performance Evaluation of UWB Massive MIMO Channels With Favorable Propagation Features". IEEE Access 7 (2019): 147010–20. http://dx.doi.org/10.1109/access.2019.2946335.

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6

LaBelle, J. "High-latitude propagation studies using a meridional chain of LF/MF/HF receivers". Annales Geophysicae 22, n.º 5 (8 de abril de 2004): 1705–18. http://dx.doi.org/10.5194/angeo-22-1705-2004.

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Abstract. For over a decade, Dartmouth College has operated programmable radio receivers at multiple high-latitude sites covering the frequency range 100-5000kHz with about a 1-s resolution. Besides detecting radio emissions of auroral origin, these receivers record characteristics of the ionospheric propagation of natural and man-made signals, documenting well-known effects, such as the diurnal variation in the propagation characteristics of short and long waves, and also revealing more subtle effects. For example, at auroral zone sites in equinoctial conditions, the amplitudes of distant transmissions on MF/HF frequencies are often enhanced by a few dB just before they fade away at dawn. The polarization and/or direction of the arrival of ionospherically propagating signals in the lower HF range (3-5MHz) show a consistent variation between pre-midnight, post-midnight, and pre-dawn conditions. As is well known, magnetic storms and substorms dramatically affect ionospheric propagation; data from multiple stations spanning the invariant latitude range 67-79° reveal spatial patterns of propagation characteristics associated with magnetic storms and substorms. For example, in the hours preceding many isolated substorms, favorable propagation conditions occur at progressively lower latitudes as a function of time preceding the substorm onset. For some of these effects, explanations follow readily from elementary ionospheric physics, but understanding others requires further investigation.Key words. Magnetospheric physics (annual phenomena) – Radio science (ionosphere propagation; radio-wave propagation)6

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7

Bashkuev, Yuri y Mikhail Dembelov. "Modeling of the Propagation of LF–MF–SF Bands Electromagnetic Waves on Arctic Paths". Infocommunications and Radio Technologies 6, n.º 1 (18 de agosto de 2023): 53–62. http://dx.doi.org/10.29039/2587-9936.2023.06.1.05.

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The article demonstrates that the conditions of LF–MF–SF bands electromagnetic wave propagation over the “ice-sea” structure with highly inductive impedance are more favorable than over the sea without ice because of the appearance of surface electromagnetic waves (SEW). It was determined that the conditions of radio wave propagation over ice paths depend on a frequency, ice thickness and distance from the transmitter within the 100 kHz – 5 MHz range on the paths with ice thickness from 0.6 to 2.7 meters.

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Nuss, Wendell A. "Synoptic-Scale Structure and the Character of Coastally Trapped Wind Reversals". Monthly Weather Review 135, n.º 1 (1 de enero de 2007): 60–81. http://dx.doi.org/10.1175/mwr3267.1.

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Abstract Coastally trapped wind reversals that occur along the U.S. West Coast have been described in numerous other studies. The synoptic-scale environment and the forcing of a coastally trapped Kelvin wave are highly linked in the development of these wind reversals. However, not all wind reversals appear to behave like propagating Kelvin waves and the analysis of coastal buoy observations for three years indicates that different types of disturbances occur. Both propagating disturbances and nonpropagating disturbances occur with similar frequencies. While the synoptic-scale characteristics associated with propagating and nonpropagating wind reversals are sometimes rather subtle, several distinct differences occur that suggest a direct link between the coastal dynamics and the synoptic-scale forcing. Synoptic forcing characterized by persistent low-level offshore flow favors the development of propagating disturbances, while weak, nonsustained offshore flow characterizes nonpropagating disturbances. These differences support the idea that propagating events represent a favorable interaction between the synoptic-scale forcing and the excitation and propagation of Kelvin waves, whereas nonpropagating events either represent a less favorable interaction or are simply trapped ageostrophic flow due to the synoptic scale without a Kelvin wave response. These dynamic differences imply different stratus behavior, which is important to forecasters.

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9

Chen, Zheng y Emil Bjornson. "Channel Hardening and Favorable Propagation in Cell-Free Massive MIMO With Stochastic Geometry". IEEE Transactions on Communications 66, n.º 11 (noviembre de 2018): 5205–19. http://dx.doi.org/10.1109/tcomm.2018.2846272.

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10

Loyka, Sergey y Mahdi Khojastehnia. "Comments on “On Favorable Propagation in Massive MIMO Systems and Different Antenna Configurations”". IEEE Access 7 (2019): 185369–72. http://dx.doi.org/10.1109/access.2019.2960025.

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11

Marinova, Maya, Ariadne Andreadou, Alkyoni Mantzari y Efstathios K. Polychroniadis. "On the Twin Boundary Propagation in (111) 3C-SiC Layers". Materials Science Forum 717-720 (mayo de 2012): 419–22. http://dx.doi.org/10.4028/www.scientific.net/msf.717-720.419.

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The present study reports on the propagation of twin boundaries in (111) 3C-SiC by means of conventional (CTEM) and high resolution transmission electron microscopy (HRTEM). The investigated 3C-SiC layers were homoepitaxially grown by Chemical Vapour Deposition (CVD) on layers previously grown by Vapor Liquid Solid (VLS) mechanism on 6H-SiC substrates. At the initial stages of growth the usual twin boundary that occurs is an incoherent {-211} Σ3 one. It transforms to more energetically favorable cases by several ways: (i) The initial {-211} boundary turns 90º, to a fully coherent (111) interface, forming microtwins; (ii) A step-like interface occurs with facets along the (111) and the {-211} planes; (iii) It transforms in a fourfold twin complex propagating to the surface.

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12

Liu, Xiaoyang, Chao Liu y Xiaoping Zeng. "Online Social Network Emergency Public Event Information Propagation and Nonlinear Mathematical Modeling". Complexity 2017 (2017): 1–7. http://dx.doi.org/10.1155/2017/5857372.

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Emergency public event arises everyday on social network. The information propagation of emergency public event (favorable and harmful) is researched. The dynamics of a susceptible-infected-susceptible and susceptible-infected-removed epidemic models incorporated with information propagation of emergency public event are studied. In particular, we investigate the propagation model and the infection spreading pattern using nonlinear dynamic method and results obtained through extensive numerical simulations. We further generalize the model for any arbitrary number of infective network nodes to mimic existing scenarios in online social network. The simulation results reveal that the inclusion of multiple infective node achieved stability and equilibrium in the proposed information propagation model.

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13

Ko, Ken-Chung y Huang-Hsiung Hsu. "ISO Modulation on the Submonthly Wave Pattern and Recurving Tropical Cyclones in the Tropical Western North Pacific". Journal of Climate 22, n.º 3 (1 de febrero de 2009): 582–99. http://dx.doi.org/10.1175/2008jcli2282.1.

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Abstract This study demonstrates the multiscale nature, from synoptic to intraseasonal time scales, of the atmospheric flow in the tropical western North Pacific. The multiscale features include intraseasonal oscillations (ISO), northwestward-propagating submonthly wave patterns, and recurving tropical cyclones (TCs). In the ISO westerly phase, the wave pattern was better organized and the TCs were clustered near the cyclonic circulation of the wave pattern during the genesis, development, and propagation. On the other hand, the wave pattern and TCs were weak and poorly organized in the ISO easterly phase. The distinct characteristics between the westerly and easterly phases could be attributed to the ISO modulation on the monsoon trough and the subtropical anticyclonic ridge. The ISO in the westerly phase provided a favorable background (e.g., enhanced monsoon trough and moisture confluent zone) for the wave–TC pattern development, while the ISO in the easterly phase provided a less favorable environment.

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14

Zhu, Jieshun, Wanqiu Wang y Arun Kumar. "Simulations of MJO Propagation across the Maritime Continent: Impacts of SST Feedback". Journal of Climate 30, n.º 5 (14 de febrero de 2017): 1689–704. http://dx.doi.org/10.1175/jcli-d-16-0367.1.

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Abstract The observed Madden–Julian oscillation (MJO) tends to propagate eastward across the Maritime Continent from the eastern equatorial Indian Ocean to the western Pacific. However, numerical simulations present different levels of fidelity in representing the propagation, especially for the tropical convection associated with the MJO. This study conducts a series of coupled simulations using the NCEP CFSv2 to explore the impacts of SST feedback and convection parameterization on the propagation simulations. First, two simulations differing in the model horizontal resolutions are conducted. The MJO propagation in these two simulations is found generally insensitive to the resolution change. Further, based on the CFSv2 with a lower resolution, two additional experiments are performed with model SSTs nudged to climatologies with different time scales representing different air–sea coupling strength. It is demonstrated that weakening the air–sea coupling strength significantly degrades the MJO propagation simulation, suggesting the critical role of SST feedback in maintaining MJO propagation. Last, the sensitivity to convection parameterization is explored by comparing two simulations with different convection parameterization schemes. Analyses of these simulations indicate that including air–sea coupling alone in a dynamical model does not result in realistic maintenance of the MJO eastward propagation without the development of favorable SST conditions in the western Pacific. In both observations and one simulation with realistic MJO propagations, the preconditioning of SSTs is strongly affected by surface latent heat fluxes that are modulated by surface wind anomalies in both zonal and meridional directions. The diagnostics highlight the critical contribution from meridional winds in wind speed variations, which has been neglected in most MJO studies.

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15

Yang, C. H. y M. F. Huang. "Measurement and Modelling for the Dispersion Relations of Acoustic Waves Propagating in a Free Piezoelectric Plate". Journal of Mechanics 19, n.º 2 (junio de 2003): 311–18. http://dx.doi.org/10.1017/s1727719100004342.

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ABSTRACTThis research is focused in the measurement and modelling of the dispersion relations of Lamb waves propagating in a piezoelectric plate. A theoretical model based on a partial wave analysis is used to provide numerical calculations for the dispersion relations of Lamb waves propagating in an LiNbO3 plate with different propagating directions. The dispersion relations are presented in an innovative image format. A non-contact laser ultrasound technique operated in B-scan mode with the aid of double Fast Fourier transform signal-processing scheme is used to measured multi-mode dispersion realtions. Among all the propagation angles, the measured dispersion curves show good agreement with the theoretical calculations. The Rayleigh wave speeds are extracted from the measured and calculated dispersion curves, showing favorable comparison with classical theory by Campbell.

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16

Yang, Gui-Ying, Brian J. Hoskins y Julia M. Slingo. "Equatorial Waves in Opposite QBO Phases". Journal of the Atmospheric Sciences 68, n.º 4 (1 de abril de 2011): 839–62. http://dx.doi.org/10.1175/2010jas3514.1.

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Abstract A methodology for identifying equatorial waves is used to analyze the multilevel 40-yr ECMWF Re-Analysis (ERA-40) data for two different years (1992 and 1993) to investigate the behavior of the equatorial waves under opposite phases of the quasi-biennial oscillation (QBO). A comprehensive view of 3D structures and of zonal and vertical propagation of equatorial Kelvin, westward-moving mixed Rossby–gravity (WMRG), and n = 1 Rossby (R1) waves in different QBO phases is presented. Consistent with expectation based on theory, upward-propagating Kelvin waves occur more frequently during the easterly QBO phase than during the westerly QBO phase. However, the westward-moving WMRG and R1 waves show the opposite behavior. The presence of vertically propagating equatorial waves in the stratosphere also depends on the upper tropospheric winds and tropospheric forcing. Typical propagation parameters such as the zonal wavenumber, zonal phase speed, period, vertical wavelength, and vertical group velocity are found. In general, waves in the lower stratosphere have a smaller zonal wavenumber, shorter period, faster phase speed, and shorter vertical wavelength than those in the upper troposphere. All of the waves in the lower stratosphere show an upward group velocity and downward phase speed. When the phase of the QBO is not favorable for waves to propagate, their phase speed in the lower stratosphere is larger and their period is shorter than in the favorable phase, suggesting Doppler shifting by the ambient flow and a filtering of the slow waves. Tropospheric WMRG and R1 waves in the Western Hemisphere also show upward phase speed and downward group velocity, with an indication of their forcing from middle latitudes. Although the waves observed in the lower stratosphere are dominated by “free” waves, there is evidence of some connection with previous tropical convection in the favorable year for the Kelvin waves in the warm water hemisphere and WMRG and R1 waves in the Western Hemisphere, which is suggestive of the importance of convective forcing for the existence of propagating coupled Kelvin waves and midlatitude forcing for the existence of coupled WMRG and R1 waves.

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Zhang, Yuxiang, Jianhua Zhang, Jian Zhang, Guangyi Liu, Yuan Zhang y Yuan Yao. "A Theoretical Analysis of Favorable Propagation on Massive MIMO Channels with Generalized Angle Distributions". Electronics 11, n.º 14 (9 de julio de 2022): 2150. http://dx.doi.org/10.3390/electronics11142150.

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Massive MIMO obtains the multiuser performance gain based on the favorable propagation (FP) assumption, defined as the mutual orthogonality of different users’ channel vectors. Until now, most of the theoretical analyses of FP are based on uniform angular distributions and only consider the horizontal dimension. However, the real propagation channel contains full dimensions, and the spatial angle varies with the environment. Thus, it remains unknown whether the FP condition holds in real deployment scenarios and how it impacts the massive MIMO system performance. In this paper, we analyze the FP condition theoretically based on a cluster-based three-dimensional (3D) MIMO channel with generalized angle distributions. Firstly, the FP condition’s unified mathematical expectation and variance expressions with full-dimensional angular integral are given. Since the closed-form expressions are hard to derive, we decompose generalized angle distributions, i.e., wrapped Gaussian (WG), Von Mises (VM), and truncated Laplacian (TL) into the functions of Bessel and Cosine basis by introducing Jacobi-Anger expansions and Fourier series. Thus the closed-form expressions of the FP condition are derived. Based on the above, we theoretically analyze the asymptotically FP condition under generalized angle distributions and then compare the impact of angular spreads on the FP performance. Furtherly, the FP condition is also investigated by numerical simulations and practical measurements. It is observed that environments with larger angle spreads and larger antenna spacing are more likely to realize FP. This paper provides valuable insights for the theoretical analysis of the practical application of massive MIMO systems.

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Van Renterghem, T. y D. Botteldooren. "Variability due to short-distance favorable sound propagation and its consequences for immission assessment". Journal of the Acoustical Society of America 143, n.º 6 (junio de 2018): 3406–17. http://dx.doi.org/10.1121/1.5040483.

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Adames, Ángel F. y Yi Ming. "Moisture and Moist Static Energy Budgets of South Asian Monsoon Low Pressure Systems in GFDL AM4.0". Journal of the Atmospheric Sciences 75, n.º 6 (1 de junio de 2018): 2107–23. http://dx.doi.org/10.1175/jas-d-17-0309.1.

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Abstract The mechanisms that lead to the propagation of anomalous moisture and moist static energy (MSE) in monsoon low and high pressure systems, collectively referred to as synoptic-scale monsoonal disturbances (SMDs), are investigated using daily output fields from GFDL’s atmospheric general circulation model, version 4.0 (AM4.0). On the basis of linear regression analysis of westward-propagating rainfall anomalies of time scales shorter than 15 days, it is found that SMDs are organized into wave trains of three to four individual cyclones and anticyclones. These events amplify over the Bay of Bengal, reach a maximum amplitude over the eastern coast of India, and dissipate as they approach the Arabian Sea. The structure and propagation of the simulated SMDs resemble those documented in observations. It is found that moisture and MSE anomalies exhibit similar horizontal structures in the simulated SMDs, indicating that moisture is the leading contributor to MSE. Propagation of the moisture anomalies is governed by vertical moisture advection, while the MSE anomalies propagate because of horizontal advection of dry static energy by the anomalous winds. By combining the budgets, we interpret the propagation of the moisture anomalies in terms of lifting that is forced by horizontal dry static energy advection, that is, ascent along sloping isentropes. This process moistens the lower free troposphere, producing an environment that is more favorable to deep convection. Ascent driven by radiative heating is of primary importance to the maintenance of the moisture anomalies.

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20

Keenan, T. D. y R. E. Carbone. "Propagation and Diurnal Evolution of Warm Season Cloudiness in the Australian and Maritime Continent Region". Monthly Weather Review 136, n.º 3 (1 de marzo de 2008): 973–94. http://dx.doi.org/10.1175/2007mwr2152.1.

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Abstract Warm season cold cloud-top climatology in the Austral–Indonesian region is examined for evidence of propagating modes of precipitation that originate from elevated heat sources and the diurnal heating cycle. Using satellite-inferred cloudiness from the period 1996–2001 as a proxy for rainfall, this coherent regeneration process and subsequent event propagation is found to consistently occur from the midlatitudes (30°–40°S) to the tropics (10°–20°S) in the Austral region. Given favorable environmental shear at midlatitudes, long-lived eastward-propagating events are observed to occur regularly with a span and duration typically larger than observed by Carbone et al. The genesis of these events, while intermittent, is directly related to elevated heat sources and the diurnal cycle, similar to the United States. However, given the relatively flat terrain of Australia, an elevated heat source is often insufficient, thus increasing the relative influence of transient synoptic forcing. In the tropics, the thermal forcing associated with elevated terrain found over the islands of the Maritime Continent and the land–sea interface is increasingly dominant on daily basis. While eastward- and westward-propagating events are found in the more varied environment of the monsoon regime, evidence for meridionally propagating modes is also found. In this manner, complex interactions occur that modify the location and timing of clouds that develop over neighboring oceanic and continental locations. The impact of convection initially linked to the New Guinea highlands and subsequently impacting the Java Sea region is particularly evident affecting the observed diurnal cycle. The subtropics show characteristics intermediate between the above extremes. With the seasonal cycle, the spring environment favors eastward-propagating events but in summer there is an increasing frequency of diurnally forced quasi-stationary development over elevated terrain enhanced by favorable synoptic conditions. Overall the subtropical summer events have a shorter duration and span than their spring counterparts. The increased environmental steering winds and shear in spring are thought to be the primary reason.

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Magalhaes, J. M., I. B. Araújo, J. C. B. da Silva, R. H. J. Grimshaw, K. Davis y J. Pineda. "Atmospheric gravity waves in the Red Sea: a new hotspot". Nonlinear Processes in Geophysics 18, n.º 1 (3 de febrero de 2011): 71–79. http://dx.doi.org/10.5194/npg-18-71-2011.

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Abstract. The region of the Middle East around the Red Sea (between 32° E and 44° E longitude and 12° N and 28° N latitude) is a currently undocumented hotspot for atmospheric gravity waves (AGWs). Satellite imagery shows evidence that this region is prone to relatively high occurrence of AGWs compared to other areas in the world, and reveals the spatial characteristics of these waves. The favorable conditions for wave propagation in this region are illustrated with three typical cases of AGWs propagating in the lower troposphere over the sea. Using weakly nonlinear long wave theory and the observed characteristic wavelengths we obtain phase speeds which are consistent with those observed and typical for AGWs, with the Korteweg-de Vries theory performing slightly better than Benjamin-Davis-Acrivos-Ono theory as far as phase speeds are concerned. ERS-SAR and Envisat-ASAR satellite data analysis between 1993 and 2008 reveals signatures consistent with horizontally propagating large-scale internal waves. These signatures cover the entire Red Sea and are more frequently observed between April and September, although they also occur during the rest of the year. The region's (seasonal) propagation conditions for AGWs, based upon average vertical atmospheric stratification profiles suggest that many of the signatures identified in the satellite images are atmospheric internal waves.

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22

Kolo, Isa, Rashid K. Abu Al-Rub y Rita L. Sousa. "Computational Modelling of Fracture Propagation in Rocks Using a Coupled Elastic-Plasticity-Damage Model". Mathematical Problems in Engineering 2016 (2016): 1–15. http://dx.doi.org/10.1155/2016/3231092.

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A coupled elastic-plasticity-damage constitutive model, AK Model, is applied to predict fracture propagation in rocks. The quasi-brittle material model captures anisotropic effects and the distinct behavior of rocks in tension and compression. Calibration of the constitutive model is realized using experimental data for Carrara marble. Through the Weibull distribution function, heterogeneity effect is captured by spatially varying the elastic properties of the rock. Favorable comparison between model predictions and experiments for single-flawed specimens reveal that the AK Model is reliable and accurate for modelling fracture propagation in rocks.

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23

Tavernetti, W. E. y M. M. Hafez. "Numerical Modeling and Simulation of Combustion Phenomena Related to Thermal Ignition and Flame Fronts". International Journal of Computational Methods 15, n.º 01 (27 de septiembre de 2017): 1750074. http://dx.doi.org/10.1142/s0219876217500748.

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In this study, we consider problems of thermal ignition and flame front propagation. Ordinary and partial differential equations with proper initial and boundary conditions are solved for generic cases. Numerical schemes are tested and results are discussed. Comparisons with the literature for benchmark cases are favorable.

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Chien, Trinh Van, Hien Quoc Ngo, Symeon Chatzinotas y Bjorn Ottersten. "Reconfigurable Intelligent Surface-Assisted Massive MIMO: Favorable propagation, channel hardening, and rank deficiency [Lecture Notes]". IEEE Signal Processing Magazine 39, n.º 3 (mayo de 2022): 97–104. http://dx.doi.org/10.1109/msp.2021.3128352.

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25

Titze, Ingo R., Anil Palaparthi, Karin Cox, Amanda Stark, Lynn Maxfield y Brian Manternach. "Vocalization with semi-occluded airways is favorable for optimizing sound production". PLOS Computational Biology 17, n.º 3 (29 de marzo de 2021): e1008744. http://dx.doi.org/10.1371/journal.pcbi.1008744.

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Vocalization in mammals, birds, reptiles, and amphibians occurs with airways that have wide openings to free-space for efficient sound radiation, but sound is also produced with occluded or semi-occluded airways that have small openings to free-space. It is hypothesized that pressures produced inside the airway with semi-occluded vocalizations have an overall widening effect on the airway. This overall widening then provides more opportunity to produce wide-narrow contrasts along the airway for variation in sound quality and loudness. For human vocalization described here, special emphasis is placed on the epilaryngeal airway, which can be adjusted for optimal aerodynamic power transfer and for optimal acoustic source-airway interaction. The methodology is three-fold, (1) geometric measurement of airway dimensions from CT scans, (2) aerodynamic and acoustic impedance calculation of the airways, and (3) simulation of acoustic signals with a self-oscillating computational model of the sound source and wave propagation.

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26

Ge, Pei Pei y Gui Lan Yu. "Vibration Propagation Characteristics of Binary Periodic Sandwich Panels". Applied Mechanics and Materials 226-228 (noviembre de 2012): 172–75. http://dx.doi.org/10.4028/www.scientific.net/amm.226-228.172.

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By using the finite element method, the band structures of the periodic hollow cylinder sandwich panels are investigated, and the influences of the material and geometrical parameters on the band gap are discussed in detail. The results show that The Young's modulus of panel and the coated layer have the greatest influences on the band gap of binary periodic hollow steel cylinder sandwich panels. The smaller the Young's modulus, the lower the frequency band gap. The material and geometrical parameters of the core have important influences on the lower edges of the band gap. Thicker and higher hollow steel cylinder with large density is favorable to gain a wide low-frequency band gap. The work presented will provide a theoretical guidance in the vibration isolation research.

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He, J. H. y H. H. Huang. "Tunable Acoustic Wave Propagation Through Planar Auxetic Metamaterial". Journal of Mechanics 34, n.º 2 (17 de julio de 2017): 113–22. http://dx.doi.org/10.1017/jmech.2017.51.

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AbstractThis paper presents a tunable planar auxetic metamaterial (PAM) for controlling and filtering acoustic waves and provides guidelines for bandgap design of the proposed PAMs. Numerical results for deformed and undeformed PAMs were obtained from several finite element analyses based on Bloch–Floquet theory. The acoustic band structures of the PAMs were calculated with periodic boundaries. Tunable bandgaps in certain frequency ranges were generated by various deformations applied to the PAMs. Wave attenuation in experimental transmission loss at specific frequencies was demonstrated, showing favorable agreement with the bandgaps obtained from numerical calculations. Both the numerical and experimental results indicate that the proposed structure demonstrates great tunability and offers significant advantages over the regular materials for controlling sound wave propagation and filtering sound waves within specific frequency ranges.

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Istiqomah, Fadhilatul, Erma Yulihastin, Joko Wiratmo, Eddy Hermawan, Nurjanna Joko Trilaksono, Dasapta Erwin Irawan, Kristy Natasha Yohanes y Amalia Qurrotu Ayunina. "Propagation Characteristics of Madden Julian Oscillation in the Indonesian Maritime Continent: Case Studies for 2020-2022". Agromet 38, n.º 1 (2 de febrero de 2024): 1–12. http://dx.doi.org/10.29244/j.agromet.38.1.1-12.

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Madden-Julian Oscillation (MJO) can affect weather and climate variability in the Indonesian Maritime Continent. MJO propagation is not always the same, previous research has classified MJO into 4 categories: slow, fast, stand, and jump. The objective of this study is to investigate the differences in MJO propagation and the factors that impact it. Daily data for variables such as Outgoing Longwave Radiation (OLR), zonal wind, and sea surface temperature are utilized in this research. The collected data is processed using composite methods based on the 8 MJO phases, with a specific focus on the years 2020, 2021, and 2022. The research findings suggest that warm sea surface temperatures in the Pacific Ocean and zonal winds dominated by Kelvin waves are favorable for MJO propagation. Conversely, cooling sea surface temperatures in the Pacific Ocean and zonal winds dominated by equatorial Rossby waves can hinder MJO propagation. Future researchers are expected to examine the impact of MJO propagation during extreme rainfall occurrences in several regions of Indonesia, as well as the application of machine learning and deep learning methods to predict MJO propagation in the future.

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Brouk, James D. y Kyle J. DeMars. "Uncertainty Propagation for Inertial Navigation with Coning, Sculling, and Scrolling Corrections". Sensors 21, n.º 24 (18 de diciembre de 2021): 8457. http://dx.doi.org/10.3390/s21248457.

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This paper investigates the propagation of estimation errors through a common coning, sculling, and scrolling architecture used in modern-day inertial navigation systems. Coning, sculling, and scrolling corrections often have an unaccounted for effect on the error statistics of inertial measurements used to describe the state and uncertainty propagation for position, velocity, and attitude estimates. Through the development of an error analysis for a set of coning, sculling, and scrolling algorithms, mappings of the measurement and estimation errors through the correction term are adaptively generated. Using the developed mappings, an efficient and consistent propagation of the state and uncertainty, within the multiplicative extended Kalman filter architecture, is achieved. Monte Carlo analysis is performed, and results show that the developed system has favorable attributes when compared to the traditional mechanization.

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30

Miske, Diane M. y Nina L. Bassuk. "Propagation of Hybrid Lilacs Using Stock Plant Etiolation". Journal of Environmental Horticulture 3, n.º 3 (1 de septiembre de 1985): 111–14. http://dx.doi.org/10.24266/0738-2898-3.3.111.

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Outdoor grown stock plants of French hybrid lilacs, (Syringa vulgaris), were allowed to leaf out under dense shade. The resulting etiolated shoots were banded at the base with black tape to retain their etiolated condition, after which time shade was removed and the tops were allowed to green up. Cuttings from shoots treated this way rooted significantly better over a longer period of time than did the controls. Localized blanching of the shoots with black tape without prior shade treatment also had a favorable effect on rooting. Cuttings taken from stock plants forced during the winter in a greenhouse rooted as well as the best etiolation treatment outdoors. Shading or IBA treatment did not improve the rooting of these greenhouse grown plants. Only localized banding with black tape increased rooting significantly in the greenhouse grown cuttings.

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31

GUMEN, L., NAGARAJ, A. NEOGI y A. KROKHIN. "LONG-RANGE SURFACE PLASMONS ON HIGHLY ANISOTROPIC DIELECTRIC SUBSTRATES". Journal of Nonlinear Optical Physics & Materials 19, n.º 04 (diciembre de 2010): 613–19. http://dx.doi.org/10.1142/s0218863510005625.

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We calculate the propagation length of surface plasmons in metal-dielectric structures with anisotropic substrates. We show that the Joule losses can be minimized by appropriate orientation of the optical axis of a birefringent substrate and that the favorable orientation of the axis depends on ω. A simple Kronig-Penney model for anisotropic plasmonic crystal is also proposed.

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32

Sirkova, Irina. "Revisiting Enhanced AIS Detection Range under Anomalous Propagation Conditions". Journal of Marine Science and Engineering 11, n.º 9 (21 de septiembre de 2023): 1838. http://dx.doi.org/10.3390/jmse11091838.

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Two clear-air over-the-horizon propagation mechanisms affecting the Automatic Identification System (AIS) detection range are considered. Comparison results are presented between the path loss due to tropospheric ducting and path loss due to tropospheric scattering (troposcatter) for the AIS frequencies. The calculations are based on the well-known parabolic equation approximation to the wave equation, in which a simple troposcatter formula is incorporated. In most studied cases, the ducting ensures a significantly greater reduction in path loss than troposcatter even when the AIS frequencies are not well trapped in the duct. Emphasis is placed on the elevated trapping layers, and some features that may make ducting propagation less favorable in terms of increasing the AIS detection range are discussed.

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33

Smirnov, B. M. y S. O. Plitchenko. "MATHEMATICAL MODELING OF THE PROCESS OF CRYSTALLIZATION CORES TURNOUTS IN THE TWO CASTING FORM". Science and Transport Progress, n.º 25 (25 de diciembre de 2008): 210–14. http://dx.doi.org/10.15802/stp2008/14472.

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The mathematical model of the temperature field of the «Casting» system is presented in the article. «Casting» as a two-layer foundry form is supposed to estimate the character of propagation of crystallization front along the casting section and to define the parameters of the casting form, which will provide the most favorable thermal conditions of the core structure formation.

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34

Gu, Sheng-Yang, Han-Li Liu, Xiankang Dou y Tao Li. "Influence of the sudden stratospheric warming on quasi-2-day waves". Atmospheric Chemistry and Physics 16, n.º 8 (20 de abril de 2016): 4885–96. http://dx.doi.org/10.5194/acp-16-4885-2016.

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Abstract. The influence of the sudden stratospheric warming (SSW) on a quasi-2-day wave (QTDW) with westward zonal wave number 3 (W3) is investigated using the Thermosphere–Ionosphere–Mesosphere Electrodynamics General Circulation Model (TIME-GCM). The summer easterly jet below 90 km is strengthened during an SSW, which results in a larger refractive index and thus more favorable conditions for the propagation of W3. In the winter hemisphere, the Eliassen–Palm (EP) flux diagnostics indicate that the strong instabilities at middle and high latitudes in the mesopause region are important for the amplification of W3, which is weakened during SSW periods due to the deceleration or even reversal of the winter westerly winds. Nonlinear interactions between the W3 and the wave number 1 stationary planetary wave produce QTDW with westward zonal wave number 2 (W2). The meridional wind perturbations of the W2 peak in the equatorial region, while the zonal wind and temperature components maximize at middle latitudes. The EP flux diagnostics indicate that the W2 is capable of propagating upward in both winter and summer hemispheres, whereas the propagation of W3 is mostly confined to the summer hemisphere. This characteristic is likely due to the fact that the phase speed of W2 is larger, and therefore its waveguide has a broader latitudinal extension. The larger phase speed also makes W2 less vulnerable to dissipation and critical layer filtering by the background wind when propagating upward.

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35

Prudnikov, I. R. "Guiding hard X-rays by means of a periodic multilayer waveguide with an air clearance: a numerical study". Journal of Applied Crystallography 40, n.º 3 (15 de mayo de 2007): 427–35. http://dx.doi.org/10.1107/s0021889807012253.

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A periodic multilayer waveguide for X-rays with an air gap serving as a guiding layer is considered. The propagation of hard X-ray guided modes through such a waveguide has been investigated with the help of numerical modeling. The propagation lengths of the guided modes are analyzed thoroughly with respect to their dependence on the reflectivity of the periodic multilayers forming the waveguide. It is shown that the guided modes can be generated even in a waveguide composed of low-reflectivity multilayers. The influence of a standing wave inside the reflecting multilayers on the transmission of the guided waves by the waveguide is demonstrated. Conditions which are favorable for the excitation of the guided modes are discussed.

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36

Su, Pei Li y Shuan Cheng Gu. "Splitting Criterion of Grouting Bore-Hole Wall and Study on Numerical Simulation of Crack Propagation". Applied Mechanics and Materials 226-228 (noviembre de 2012): 1411–14. http://dx.doi.org/10.4028/www.scientific.net/amm.226-228.1411.

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The situation that the grouting borehole doesn’t intersect with natural fractures of rock masses is often met in practical grouting project. Hence, it’s very necessary to discuss whether the rock masses around borehole will split under the grouting pressure and the corresponding splitting orientation. After the splitting crack finishes propagation, we can estimate whether it will penetrate with original fractures, and it’s favorable for grouting theory analysis and numerical simulation and so on. According to this, the splitting criterion and splitting orientation are proposed with and without considering ground stress, respectively. In the meantime, under the situation of splitting, the singularity of crack-tip’s stress field is simulated by 6 nodes singular isoparametric element through secondary development of large-scale finite element analysis software-ANSYS. The stress intensity factor is introduced and the propagation of the splitting crack is simulated to obtain the final propagation length, which has significant guiding meaning to grouting theory and the practical grouting projects.

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37

Yan, Zhice, Lasheng Zhao, Xiaopeng Wei y Qiang Zhang. "Improved Label Propagation Model to Predict Drug - drug Interactions". MATEC Web of Conferences 173 (2018): 02007. http://dx.doi.org/10.1051/matecconf/201817302007.

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Drug-drug interactions (DDIs) is one of the most concerned issues in drug design. Accurate prediction of potential DDIs in clinical trials can reduce the occurrence of side effects in real life of drugs. Therefore, we propose a model to predict DDIs. The model integrates several methods that can improve label propagation algorithm. Firstly, the chi-square test (CHI) method is adopted to filter or select the features that contain a large amount of information. Secondly, the sample similarity calculation method is reconstructed by label similarity and feature similarity. Then the label initialization information of unlabeled samples is constructed. Finally, we use label propagation algorithm to estimate the labels of the unlabeled drugs. The results show that the proposed model can obtain higher the area under the receiver operating characteristic curve (AUROC) and the area under the precision-recall curve (AUPR), which provides a favorable guarantee for the discovery of DDIs in the clinical stage.

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38

Hong, Zhiyong, Huiyu Zhou, Zhishuang Wang, Qian Yin y Jingang Liu. "Coupled Propagation Dynamics of Information and Infectious Disease on Two-Layer Complex Networks with Simplices". Mathematics 11, n.º 24 (8 de diciembre de 2023): 4904. http://dx.doi.org/10.3390/math11244904.

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The mutual influence between information and infectious diseases during the spreading process is becoming increasingly prominent. To elucidate the impact of factors such as higher-order interactions, interpersonal distances, and asymptomatic carriers on the coupled propagation of information and infectious diseases, a novel coupled spreading model is constructed based on a two-layer complex network, where one layer is a higher-order network and another layer is a weighted network. The higher-order interactions in information propagation are characterized using a 2-simplex, and a sUARU (simplicial unaware-aware-removed-unaware) model is employed to articulate information propagation. The inter-individual social distances in disease propagation are represented by the weights of a weighted network, and an SEIS (susceptible-exposed-infected-susceptible) model is utilized to describe disease propagation. The dynamic equations of coupled spreading are formulated utilizing the microscopic Markov chain approach. An analytical expression for the epidemic threshold is obtained by deriving it from the steady-state form of the dynamic equations. Comprehensive simulations are conducted to scrutinize the dynamic characteristics of the coupled spreading model. The findings indicate that enhancing the effects of higher-order interactions in information propagation and increasing inter-individual social distances both lead to higher outbreak thresholds and greater spreading of diseases. Additionally, a stronger infectivity among asymptomatic carriers and an extended incubation period are favorable for the outbreak and spread of an epidemic. These findings can provide meaningful guidance for the prevention and control of real-world epidemics.

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39

Alam Kherani, E., M. A. Abdu, E. R. de Paula, D. C. Fritts, J. H. A. Sobral y F. C. de Meneses. "The impact of gravity waves rising from convection in the lower atmosphere on the generation and nonlinear evolution of equatorial bubble". Annales Geophysicae 27, n.º 4 (7 de abril de 2009): 1657–68. http://dx.doi.org/10.5194/angeo-27-1657-2009.

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Abstract. The nonlinear evolution of equatorial F-region plasma bubbles under varying ambient ionospheric conditions and gravity wave seeding perturbations in the bottomside F-layer is studied. To do so, the gravity wave propagation from the convective source region in the lower atmosphere to the thermosphere is simulated using a model of gravity wave propagation in a compressible atmosphere. The wind perturbation associated with this gravity wave is taken as a seeding perturbation in the bottomside F-region to excite collisional-interchange instability. A nonlinear model of collisional-interchange instability (CII) is implemented to study the influences of gravity wave seeding on plasma bubble formation and development. Based on observations during the SpreadFEx campaign, two events are selected for detailed studies. Results of these simulations suggest that gravity waves can play a key role in plasma bubble seeding, but that they are also neither necessary nor certain to do so. Large gravity wave perturbations can result in deep plasma bubbles when ionospheric conditions are not conducive by themselves; conversely weaker gravity wave perturbations can trigger significant bubble events when ionospheric conditions are more favorable. But weak gravity wave perturbations in less favorable environments cannot, by themselves, lead to strong plasma bubble responses.

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40

Arjoo, Sushil Sharma, Rajat, Aayush y Vikalp. "Interactive Effects of Grafting Time and Technique on the Sprouting Time and Growth of Guava Grafts (Psidium guajava L.)". International Journal of Bio-resource and Stress Management 15, Feb, 2 (19 de febrero de 2024): 01–06. http://dx.doi.org/10.23910/1.2024.5052a.

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The present study was conducted during June to September, 2021 at the experimental orchard of the Department of Horticulture, CCS Haryana Agricultural University, Haryana, India to investigate the impact of propagation methods, time, and varieties on the success rate of guava (Psidium guajava L.) propagation. The treatments were arranged in a three factorial layout using a Randomized Complete Design with three replications. In the months of June, July, August, and September, two different cultivars (L-49 and Hisar Safeda) and four different propagation techniques (Patch budding, T-budding, Wedge grafting, and Inarching) were applied six times each. The results revealed that wedge grafting exhibited the shortest time to sprout (14 days), whereas inarching displayed the longest duration for sprouting (54.33 days). The 2nd fortnight of July and the 1st fortnight of September demonstrated the most favorable time for bud sprouting. Moreover, Hisar Safeda exhibited superior performance compared to L-49 in terms of earlier sprouting and better growth. Therefore, propagation of guava using wedge grafting techniques during the months of July and September can be recommended for the study area and areas with similar agro-ecologies so as to achieve successful grafting within the shortest feasible timeframe. These findings offer crucial insights for agricultural practitioners seeking enhanced propagation techniques and optimal timings, thereby fostering improved guava cultivation practices and augmenting yields in similar agricultural settings.

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41

Zhou, Lei, Raghu Murtugudde, Dake Chen y Youmin Tang. "A Central Indian Ocean Mode and Heavy Precipitation during the Indian Summer Monsoon". Journal of Climate 30, n.º 6 (marzo de 2017): 2055–67. http://dx.doi.org/10.1175/jcli-d-16-0347.1.

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A central Indian Ocean (CIO) mode is found to play a critical role in driving the heavy precipitation during the Indian summer monsoon (ISM). It is typically denoted with a combination of intraseasonal sea surface temperature (SST) anomalies and intraseasonal wind anomalies over the central Indian Ocean, and it preserves the mechanistic links among various dynamic and thermodynamic fields. Like a T junction, it controls the propagation direction of the intraseasonal variabilities (ISVs) originating in the western Indian Ocean. During the ISM, the CIO mode creates an environment favorable for the northward-propagating mesoscale variabilities. These results unveil the relation between the subseasonal monsoonal precipitation and the CIO mode in the ocean–atmosphere system in the Indian Ocean. The identification of the CIO mode deepens our understanding of the coupled monsoon system and brightens the prospects for better simulation and prediction of monsoonal precipitation in the affected countries.

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42

Grynko, Valeriy. "Theoretical sources of the Great White Brotherhood". Ukrainian Religious Studies, n.º 5 (6 de mayo de 1997): 20–32. http://dx.doi.org/10.32420/1997.5.94.

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Complex processes that accompany the formation and development of Ukrainian statehood have created favorable conditions for the spread of neo-religious churches, currents and trends. Most of them are mentally rooted, are spread predominantly owing to the activity of foreign missionaries. Therefore, given the local origin and social resonance, the Great White Brotherhood's phenomenon, whose propagation of faith was carried out and had some success in most of the post-Soviet countries, needs special attention.

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43

Safargaleev, V. V. "Estimation of the Propagation Time of the Solar Wind Pressure Pulse between a Shock Wave and the Magnetopause Based on Simultaneous Satellite and Ground-Based Observations". Geomagnetism and Aeronomy 62, n.º 6 (diciembre de 2022): 694–703. http://dx.doi.org/10.1134/s0016793222060123.

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Abstract The propagation of solar wind inhomogeneities through the transition region between the bow shock front and the daytime magnetopause is an important link in the chain of solar-terrestrial connections. We analyzed a unique situation when two THEMIS satellites were near the bow shock during the solar wind pressure pulse, and the favorable location of the ground-based magnetometric equipment made it possible to determine the time of the solar wind impact on the magnetopause with greater accuracy than it was done previously. Based on the measurements, the propagation time of sudden impulse (SI) in the magnetosheath was estimated. The obtained value (~1 min) agrees with model calculations, but turns out to be 2–3 times less than that previously obtained by other authors also from satellite and ground-based observations. The propagation velocity of the solar wind in the magnetosheath (~280 km/s), the displacement velocity of the bow shock front to the Earth (~80 km/s), and the thickness of the magnetosheath at the location of the satellites (2.6–3.9RE) are determined.

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44

Kim, Si-Hong, Mewuleddeg Zebro, Dong-Cheol Jang, Jeong-Eun Sim, Han-Kyeol Park, Kyeong-Yeon Kim, Hyung-Min Bae, Shimeles Tilahun y Sung-Min Park. "Optimization of Plant Growth Regulators for In Vitro Mass Propagation of a Disease-Free ‘Shine Muscat’ Grapevine Cultivar". Current Issues in Molecular Biology 45, n.º 10 (22 de septiembre de 2023): 7721–33. http://dx.doi.org/10.3390/cimb45100487.

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This study addresses the propagation challenges faced by ‘Shine Muscat’, a newly introduced premium grapevine cultivar in South Korea, where multiple viral infections pose considerable economic loss. The primary objective was to establish a robust in vitro propagation method for producing disease-free grapes and to identify effective plant growth regulators to facilitate large-scale mass cultivation. After experimentation, 2.0 µM 6-benzyladenine (BA) exhibited superior shoot formation in the Murashige and Skoog medium compared with kinetin and thidiazuron. Conversely, α-naphthaleneacetic acid (NAA) hindered shoot growth and induced callus formation, while indole-3-butyric acid (IBA) and indole-3-acetic acid (IAA) demonstrated favorable root formation, with IBA showing better results overall. Furthermore, inter simple sequence repeat analysis confirmed the genetic stability of in vitro-cultivated seedlings using 2.0 μM BA and 1.0 μM IBA, validating the suitability of the developed propagation method for generating disease-free ‘Shine Muscat’ grapes. These findings offer promising prospects for commercial grape cultivation, ensuring a consistent supply of healthy grapes in the market.

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45

Sugar, Mitchell y Paul Slaboch. "Directivity of sound propagation from an commercial supersonic engine inlet". INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, n.º 2 (1 de agosto de 2021): 4211–18. http://dx.doi.org/10.3397/in-2021-2633.

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The effects of mean flow variations on sound propagation from an axisymmetric commercial supersonic engine inlet were studied using numerical methods. A finite element model of the inlet was constructed in Ansys Fluent and used to solve for flow fields given by different initial conditions. Results from this model were fed into the aeroacoustic solver, Actran, and used to calculate far field radiated noise as well as the directivity of that noise. The acoustic source of this noise was a plane wave of a known strength placed at the fan face. In addition to assessing the effects of mean flow on the radiated noise transfer functions, the duct modes of the model were compared across different flow regimes. Relationships between mean flow parameters and the directivity of duct modes are developed. The results of this study will be used in further studies to gain a deeper understanding of how the underlying physics which govern the system create favorable or unfavorable directivity patterns.

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46

Seo, Kyong-Hwan, Jae-Kyung E. Schemm, Wanqiu Wang y Arun Kumar. "The Boreal Summer Intraseasonal Oscillation Simulated in the NCEP Climate Forecast System: The Effect of Sea Surface Temperature". Monthly Weather Review 135, n.º 5 (1 de mayo de 2007): 1807–27. http://dx.doi.org/10.1175/mwr3369.1.

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Abstract Observational evidence has indicated the important role of the interaction of the atmosphere with the sea surface in the development and maintenance of the tropical intraseasonal oscillation (ISO). However, improvements in ISO simulations with fully coupled atmosphere–ocean general circulation models are limited and model dependent. This study further examines the effect of air–sea coupling and the basic-state sea surface temperature (SST) associated with the boreal summer intraseasonal oscillation (BSISO) in a 21-yr free run with the recently developed NCEP coupled Climate Forecast System (CFS) model. For this, the CFS run is compared with an Atmospheric Model Intercomparison Project–type long-term simulation forced by prescribed SST in the NCEP Global Forecast System (GFS) model and flux-corrected version of CFS (referred to as CFSA). The GFS run simulates significantly unorganized BSISO convection anomalies, which exhibit an erroneous standing oscillation. The CFS run with interactive air–sea coupling has limited improvements, including the generation of intraseasonal SST variation preceding the convection anomaly by ∼10 days. However, this simulation still does not show the observed continuous northward propagation over the Indian Ocean due to a cold model bias. The CFSA run removes the cold bias in the Indian Ocean and the simulation of the development and propagation of BSISO anomalies are significantly improved. Enhanced and suppressed convection anomalies exhibit the observed quadrupole-like configuration, and phase relationships between precipitation and surface dynamic and thermodynamic variables for the northward propagation are shown to be coherent and consistent with the observations. It is shown that the surface meridional moisture convergence is an important factor for the northward propagation of the BSISO. On the other hand, both the GFS and CFS runs do not realistically simulate an eastward-propagating equatorial mode. The CFSA run produces a more realistic eastward-propagation mode only over the Indian Ocean and Java Sea due to the improved mean state in SST, low-level winds, and vertical wind shear. Reasons for the failure of farther eastward propagation into the west Pacific in CFSA are discussed. This study reconfirms the significance of air–sea interactions. More importantly, however, the results suggest that in order for the influence of the coupled air–sea interaction to be properly communicated, the mean state SST in the coupled model should be reasonably simulated. This is because the basic-state SST itself acts to sustain BSISO convection and it makes the large-scale dynamical environment (i.e., easterly vertical wind shear or low-level westerly zonal wind) more favorable for the propagation of the moist Rossby–Kelvin wave packet.

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47

Petersen, Andrew P., Nathan Cho, Davi M. Lyra-Leite, Jeffrey W. Santoso, Divya Gupta, Nethika R. Ariyasinghe y Megan L. McCain. "Regulation of calcium dynamics and propagation velocity by tissue microstructure in engineered strands of cardiac tissue". Integrative Biology 12, n.º 2 (febrero de 2020): 34–46. http://dx.doi.org/10.1093/intbio/zyaa003.

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Abstract Disruptions to cardiac tissue microstructure are common in diseased or injured myocardium and are known substrates for arrhythmias. However, we have a relatively coarse understanding of the relationships between myocardial tissue microstructure, propagation velocity and calcium cycling, due largely to the limitations of conventional experimental tools. To address this, we used microcontact printing to engineer strands of cardiac tissue with eight different widths, quantified several structural and functional parameters and established correlation coefficients. As strand width increased, actin alignment, nuclei density, sarcomere index and cell aspect ratio decreased with unique trends. The propagation velocity of calcium waves decreased and the rise time of calcium transients increased with increasing strand width. The decay time constant of calcium transients decreased and then slightly increased with increasing strand width. Based on correlation coefficients, actin alignment was the strongest predictor of propagation velocity and calcium transient rise time. Sarcomere index and cell aspect ratio were also strongly correlated with propagation velocity. Actin alignment, sarcomere index and cell aspect ratio were all weak predictors of the calcium transient decay time constant. We also measured the expression of several genes relevant to propagation and calcium cycling and found higher expression of the genes that encode for connexin 43 (Cx43) and a subunit of L-type calcium channels in thin strands compared to isotropic tissues. Together, these results suggest that thinner strands have higher values of propagation velocity and calcium transient rise time due to a combination of favorable tissue microstructure and enhanced expression of genes for Cx43 and L-type calcium channels. These data are important for defining how microstructural features regulate intercellular and intracellular calcium handling, which is needed to understand mechanisms of propagation in physiological situations and arrhythmogenesis in pathological situations.

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48

Bisognin, Dilson Antônio. "Breeding vegetatively propagated horticultural crops". Crop Breeding and Applied Biotechnology 11, spe (junio de 2011): 35–43. http://dx.doi.org/10.1590/s1984-70332011000500006.

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Horticulture is an important part of agriculture with many important crops being vegetatively propagated. The objectives of this work were to discuss some of the most important characteristics of vegetatively propagated crops and the breeding strategies to develop and propagate new cultivars. Vegetative propagation enables to fix favorable combinations of important traits, very specific chemical compositions, superior genetic variance interactions and high levels of heterozygosity. Breeding new cultivars involve few possibilities of genetic recombination by sexual reproduction and many generations of selection and vegetative propagation. Marker assisted selection should be useful for genotyping and selecting complementary parents for crossing and for identifying superior genotypes at early stages of selection. The tissue culture technique enables to get disease free stock plants and to maximize its multiplication rate, having an important role in yield and quality of these crops.

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Nguyen, Hai T., Son T. Dinh, Thao T. Ninh, Hue T. Nong, Tam T. T. Dang, Quyet V. Khuat, Anh T. P. Dang, My T. Ly, Rima N. Kirakosyan y Elena A. Kalashnikova. "In Vitro Propagation of the Dendrobium anosmum Lindl. Collected in Vietnam". Agronomy 12, n.º 2 (26 de enero de 2022): 324. http://dx.doi.org/10.3390/agronomy12020324.

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Hoa Binh province is one of the best places for orchids in Vietnam. The climate and environment of Hoa Binh province are favorable for the development of orchids, especially rare indigenous ones. Dendrobium anosmum Lindl., which stands out because of the unique fragrance and colors, is one of the most popular varieties in Hoa Binh province. To meet the increasing demands of the industrial market as well as to contribute to the preservation and development of genetic resources of Dendrobium sp. in Hoa Binh province, propagating D. anosmum Lindl. is a crucial step. Plant tissue culture, which has been applied to improve reproducibility of orchids for many years, is still an effective method, especially for large-scale propagation. Studies on in vitro propagation of D. anosmum Lindl. from Hoa Binh province showed that growth regulators (BA, kinetin, α-NAA) did not have a significant effect on protocorm initiation because D. anosmum Lind. from Hoa Binh province already has a high rate of regeneration. However, MS medium + 1.0 mg/L kinetin + 0.5 mg/L α-NAA + 30 g sucrose + 8.0 g agar per liter, pH 5.7–5.8 was the optimal medium to increase shoot length. The MS medium + 1.0 g activated charcoal + 30 g sucrose + 8.0 g agar per liter, pH 5.7–5.8 was the most suitable medium for shoot growth—after 6 weeks of culture, the average shoot length was 1.09 cm, the average number of leaves was 6.13, the average number of roots was 3.17, and the average root length was 1.11 cm—about 3.3, 4.17, 3.41, and 1.67 times higher, respectively, than in the control (without activated charcoal).

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50

Mitrano, Matteo, Sangjun Lee, Ali A. Husain, Luca Delacretaz, Minhui Zhu, Gilberto de la Peña Munoz, Stella X. L. Sun et al. "Ultrafast time-resolved x-ray scattering reveals diffusive charge order dynamics in La2–xBaxCuO4". Science Advances 5, n.º 8 (agosto de 2019): eaax3346. http://dx.doi.org/10.1126/sciadv.aax3346.

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Charge order is universal among high-Tc cuprates, but its relation to superconductivity is unclear. While static order competes with superconductivity, dynamic order may be favorable and even contribute to Cooper pairing. Using time-resolved resonant soft x-ray scattering at a free-electron laser, we show that the charge order in prototypical La2−xBaxCuO4 exhibits transverse fluctuations at picosecond time scales. These sub–millielectron volt excitations propagate by Brownian-like diffusion and have an energy scale remarkably close to the superconducting Tc. At sub–millielectron volt energy scales, the dynamics are governed by universal scaling laws defined by the propagation of topological defects. Our results show that charge order in La2−xBaxCuO4 exhibits dynamics favorable to the in-plane superconducting tunneling and establish time-resolved x-rays as a means to study excitations at energy scales inaccessible to conventional scattering techniques.

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