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Journal articles on the topic 'Propagation spatial'

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Author: Grafiati

Published: 7 July 2024

Last updated: 7 July 2024

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1

Haiyan Chen, Haiyan Chen, Meng Wang Meng Wang, Cong Chen Cong Chen, Lilin Chen Lilin Chen, Qi Li Qi Li, and Kaiqiang Huang Kaiqiang Huang. "Analogy of light propagation in spatial and temporal domains." Chinese Optics Letters 12, s1 (2014): S12601–312602. http://dx.doi.org/10.3788/col201412.s12601.

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2

Sogo, Takushi, Hiroshi Ishiguro, and Toru Ishida. "Spatial constraint propagation for identifying qualitative spatial structure." Systems and Computers in Japan 31, no. 2 (February 2000): 62–71. http://dx.doi.org/10.1002/(sici)1520-684x(200002)31:2<62::aid-scj7>3.0.co;2-o.

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3

Maleev, I. D., and G. A. Swartzlander, Jr. "Propagation of spatial correlation vortices." Journal of the Optical Society of America B 25, no. 6 (May 14, 2008): 915. http://dx.doi.org/10.1364/josab.25.000915.

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4

Chakraborty, Arindam, and Ravi S. Nanjundiah. "Space–Time Scales of Northward Propagation of Convection during Boreal Summer." Monthly Weather Review 140, no. 12 (December 1, 2012): 3857–66. http://dx.doi.org/10.1175/mwr-d-12-00088.1.

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Abstract This study uses precipitation estimates from the Tropical Rainfall Measuring Mission to quantify the spatial and temporal scales of northward propagation of convection over the Indian monsoon region during boreal summer. Propagating modes of convective systems in the intraseasonal time scales such as the Madden–Julian oscillation can interact with the intertropical convergence zone and bring active and break spells of the Indian summer monsoon. Wavelet analysis was used to quantify the spatial extent (scale) and center of these propagating convective bands, as well as the time period associated with different spatial scales. Results presented here suggest that during a good monsoon year the spatial scale of this oscillation is about 30° centered around 10°N. During weak monsoon years, the scale of propagation decreases and the center shifts farther south closer to the equator. A strong linear relationship is obtained between the center/scale of convective wave bands and intensity of monsoon precipitation over Indian land on the interannual time scale. Moreover, the spatial scale and its center during the break monsoon were found to be similar to an overall weak monsoon year. Based on this analysis, a new index is proposed to quantify the spatial scales associated with propagating convective bands. This automated wavelet-based technique developed here can be used to study meridional propagation of convection in a large volume of datasets from observations and model simulations. The information so obtained can be related to the interannual and intraseasonal variation of Indian monsoon precipitation.

5

Sabín, Carlos. "Light Propagation through Nanophotonics Wormholes." Universe 4, no. 12 (November 29, 2018): 137. http://dx.doi.org/10.3390/universe4120137.

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We consider the propagation of light along a 3D nanophotonic structure with the spatial shape of a spacetime containing a traversable wormhole. We show that waves experience significant changes of phase and group velocities when propagating along this curved space. This experiment can be realized with state-of-the-art nanophotonics technology.

6

Dzieciuch, Matthew, and T. G. Birdsall. "Spatial matched processing for multipath propagation." Journal of the Acoustical Society of America 82, S1 (November 1987): S73. http://dx.doi.org/10.1121/1.2024961.

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7

Wang, Kaifa, and Wendi Wang. "Propagation of HBV with spatial dependence." Mathematical Biosciences 210, no. 1 (November 2007): 78–95. http://dx.doi.org/10.1016/j.mbs.2007.05.004.

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8

Kazemzadeh, Ali, and Ilia Laali Niyat. "Spatial modelling of railway noise propagation." Journal of Geospatial Information Technology 7, no. 1 (May 1, 2019): 145–68. http://dx.doi.org/10.29252/jgit.7.1.145.

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9

Katragadda, Satya, Jian Chen, and Shaaban Abbady. "Spatial hotspot detection using polygon propagation." International Journal of Digital Earth 12, no. 7 (June 18, 2018): 825–42. http://dx.doi.org/10.1080/17538947.2018.1485754.

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10

Evers, Frederic M., Willi H. Hager, and Robert M. Boes. "Spatial Impulse Wave Generation and Propagation." Journal of Waterway, Port, Coastal, and Ocean Engineering 145, no. 3 (May 2019): 04019011. http://dx.doi.org/10.1061/(asce)ww.1943-5460.0000514.

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11

Nikitenko, A. S., Yu V. Fedorenko, J. Manninen, O. M. Lebed, and E. B. Beketova. "Modeling of the auroral hiss spatial structure and comparison with the observed results." Известия Российской академии наук. Серия физическая 87, no. 1 (January 1, 2023): 134–40. http://dx.doi.org/10.31857/s0367676522700259.

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We present the results of the auroral hiss propagation modeling from the source region to the ground and its comparison with the observed results. We analyzed propagation conditions explaining locality of the auroral hiss illuminated area observed on the ground. It is shown that quasielectrostatic waves with random amplitudes, phases and wavenormals directions representing the auroral hiss propagating to the ground form two wave beams in the meridional plane. The scattering of these waves at altitudes of 800–1300 km can cause the observed locality of the illuminated area.

12

Noh, Sun-Kuk, and DongYou Choi. "Propagation Model in Indoor and Outdoor for the LTE Communications." International Journal of Antennas and Propagation 2019 (June 16, 2019): 1–6. http://dx.doi.org/10.1155/2019/3134613.

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Rapidly rising demand for radio communication and the explosion in the number of mobile communications service subscribers have led to the need for optimization in the development of fifth-generation (5G) mobile communication systems. Previous studies on the development of propagation models considering a propagation environment in the existing microwave band have been mainly focused on analyzing the propagation characteristics with regard to large-scale factors such as path losses, delay propagation, and angle diffusions. In this paper, we investigated the concept of spatial and time changes ratios in the measurement of wave propagations and measured RSRP of Long Term Evolution (LTE) signals at three locations considering the time rate of 1% and 50%. We confirmed the concept of spatial and time changes rate based on the results of analyzing the signal data measured and proposed the propagation models 1 and 2 in microcell downtown. The forecast results using proposed models 1 and 2 were better than the COST231 model in both indoor and outdoor measured places. It was predicted between a time rate of 1% and 50% indoor within 400m and outdoor within 200m. In the future, we will study the propagation model of 5G mobile communication as well as the current 4G communication using artificial intelligence technology.

13

Liu, Mao, and Fujian Zhou. "Spectro-spatial analysis of elastic wave propagation in nonlinear elastic metamaterial systems with damping." Chaos: An Interdisciplinary Journal of Nonlinear Science 32, no. 11 (November 2022): 113124. http://dx.doi.org/10.1063/5.0098536.

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Different from the linear counterpart, elastic wave propagation in nonlinear elastic metamaterials with damping (EMD) systems has much more novel behaviors. It is little work that reveals the nonlinear wave propagation mechanism in the nonlinear EMD in the literature. In this paper, nonlinear EMD systems with different configurations for the nonlinear elements are constructed to study the nonlinear wave propagation characteristics based on the analytical formulation. Nonlinear wave propagation attenuation characteristics in nonlinear EMD systems are studied in the frequency-domain. Spectro-spatial characteristics of nonlinear traveling wave packet in space- and time-domain are also analyzed to reveal space frequency-domain characteristics. Influences of different configurations for the nonlinear elements on wave propagation in nonlinear EMD systems are discussed. Results shown that locations of band structures can be tuned by changing intensities of nonlinearities in the nonlinear EMD systems, which are not found in the linear system. Moreover, different configurations for the nonlinear elements can lead to localization feature emerged in a nonlinear EMD system, which indicates solitary waves causing from the interaction between dispersion and nonlinearity exist in the nonlinear systems. This interesting wave propagating properties can be used to design new devices for acoustic switches, energy harvesting, and broadband vibration control.

14

Buller, A. S., Yu V. Zelenetskaya, R. V. Litvinov, and N. R. Melikhova. "Modulation instability of two TE modes in a thin left-handed film on a nonlinear right-handed substrate." Quantum Electronics 51, no. 11 (November 1, 2021): 1030–37. http://dx.doi.org/10.1070/qel17647.

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Abstract The intramode wave beams in a thin left-handed film on a Kerr substrate are considered at a frequency near zero mode group velocity. Four coupled (1 + 1)-dimensional nonlinear Schrödinger equations, describing the interaction of forward and backward propagating beams with positive and negative group velocities, are derived. It is shown that self- and cross-phase modulation for four simultaneously propagating modes is possible only at strictly matched perturbations of their propagation constants, which is due to the contribution of spatial parametric mixing. The modulation instability of only two waveguide modes is analysed for different versions of their propagation. The specific features of modulation instability, related to the propagation of modes with negative group velocities, are investigated.

15

Chervin, R. D., P. A. Pierce, and B. W. Connors. "Periodicity and directionality in the propagation of epileptiform discharges across neocortex." Journal of Neurophysiology 60, no. 5 (November 1, 1988): 1695–713. http://dx.doi.org/10.1152/jn.1988.60.5.1695.

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1. The horizontal propagation of epileptiform discharges has been studied in slices of neocortex treated with high concentrations of bicuculline methiodide, an antagonist of the inhibitory transmitter gamma-aminobutyric acid (GABA). The cortical areas examined were: primary somatosensory (SmI) and motor (MI), and primary (area 17) and secondary (area 18) visual areas of rats, and area 17 of cats. In all of these areas an electrical stimulus evoked single, all-or-none paroxysmal field potentials (PFPs) that propagated across the entire width of the slice without decrement. 2. The velocity of PFP propagation was approximately 0.06-0.09 m/s when averaged over cortical distances of several millimeters. PFP propagation occurred equally well in both directions across a slice. 3. Measurement of PFP propagation at higher spatial resolution (100-180 micron intervals) revealed that velocity was not homogeneous within rat SmI, rat area 18 and cat area 17, but instead varied manyfold as horizontal position changed. In these areas of cortex, propagation patterns were spatially periodic; power spectra reveal that the dominant spatial frequencies were centered about 1 mm-1, with negligible contributions above 2 mm-1. Occasionally PFP propagation was discontinuous, skipping over a small region of cortex and arriving distally before propagating into the more proximal region. 4. In those cortices with periodic propagation patterns, PFP velocity was also strongly direction-dependent. Propagation patterns measured in opposite directions across the same strip of cortex displayed similar periodicities, but in many slices they were negatively correlated, i.e., the propagation pattern in one direction was antiphasic compared to that in the other direction. 5. In contrast, propagation velocity across the center of area 17 of the rat was relatively constant and not directional. Near the boundaries of areas 17 and 18, however, PFP velocity changed abruptly and became periodic within area 18. Similarly, velocity within rat MI was more constant and less directional than in the adjacent SmI. 6. The patterns of PFP propagation velocity are often spatially periodic, directionally asymmetric, and depend upon cortical area. We suggest that the periodic patterns reflect systematic variations in the length or density of horizontal excitatory connections. Alternatively, or concurrently, periodicities could arise from the patchy distributions of intrinsic connections that have been observed anatomically in many areas of neocortex.

16

Basham, Andrew, Adam D. Kingsley, and Brian E. Anderson. "Improving the super resolution focusing above a two-dimensional Helmholtz resonator array using particle velocity decomposition of time reversal focusing." Journal of the Acoustical Society of America 153, no. 3_supplement (March 1, 2023): A56. http://dx.doi.org/10.1121/10.0018146.

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Super resolution is possible using resonators placed in the near field of time reversal focusing. This presentation addresses the problem that a two-dimensional Helmholtz resonator array in a three-dimensional reverberant environment has limited ability to produce a high-resolution spatial focus in the time reversal focusing of audible sound. Acoustic waves propagating out-of-plane with the resonator array are not as strongly modified by the resonators, partially negating the effect of the resonators. The use of a two-dimensional waveguide limits the out-of-plane propagation, leading to improved resolution. It is also shown that post processing using an orthogonal particle velocity decomposition of a spatial scan of the focusing can limit out-of-plane particle motion in the near field of the array, which bypasses the effect of the unwanted third spatial dimension of propagation. Each of these techniques results in a pressure field focus reconstruction that has a higher spatial resolution.

17

Sultana, Parvin, Takahiro Matsumoto, and Makoto Tomita. "Fourier Analysis of Slow and Fast Image Propagation through Single and Coupled Image Resonators." International Journal of Optics 2012 (2012): 1–9. http://dx.doi.org/10.1155/2012/960985.

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We applied Fourier space analysis to a comprehensive study of the propagation of pulsed two-dimensional images through single and coupled image resonators. The Fourier method shows that the image can propagate through the resonator successfully as long as the spatial and temporal Fourier components of the image are within the bandwidth of the amplitude and phase transfer functions. The relevant steep dispersion of the cavity can yield delayed or advanced images. The Fourier method reproduces characteristic aspects of the experimental observations of the image propagation, and also predicts new aspects, such as the spatial image profile dependence on the observation time and the coupling strength. To demonstrate the time evolution of the experiment, space- and time-resolved image propagations were performed using a streak camera.

18

Wang Hong-Cheng, Wang Xiao-Sheng, She Wei-Long, Ren Guo-Bin, Wang Zhi, Lou Shu-Qin, and Jian Shui-Sheng. "Effect of spatial phase modulation on propagation of photovoltaic spatial solitons." Acta Physica Sinica 53, no. 8 (2004): 2595. http://dx.doi.org/10.7498/aps.53.2595.

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19

Li, Hui, Guimin Huang, Cheng Li, Jun Li, and Yabing Wang. "Adaptive Spatial–Temporal and Knowledge Fusing for Social Media Rumor Detection." Electronics 12, no. 16 (August 15, 2023): 3457. http://dx.doi.org/10.3390/electronics12163457.

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With the growth of the internet and popularity of mobile devices, propagating rumors on social media has become increasingly easy. Widespread rumors may cause public panic and have adverse effects on individuals. Recently, researchers have found that external knowledge is useful for detecting rumors. They usually use statistical approaches to calculate the importance of different knowledge for the post. However, these methods cannot aggregate the knowledge information most beneficial for detecting rumors. Second, the importance of propagation and knowledge information for discriminating rumors differs among temporal stages. Existing methods usually use a simple concatenation of two kinds of information as feature representation. However, this approach lacks effective integration of propagation information and knowledge information. In this paper, we propose a rumor detection model, Adaptive Spatial-Temporal and Knowledge fusing Network (ASTKN). In order to adaptively aggregate knowledge information, ASTKN employs dynamic graph attention networks encoding the temporal knowledge structure. To better fuse propagation structure information and knowledge structure information, we introduce a new attention mechanism to fuse the two types of information dynamically. Extensive experiments on two public real-world datasets show that our proposal yields significant improvements compared to strong baselines and that it can detect rumors at early stages.

20

Phillips, Donald L., and Danny G. Marks. "Spatial uncertainty analysis: propagation of interpolation errors in spatially distributed models." Ecological Modelling 91, no. 1-3 (November 1996): 213–29. http://dx.doi.org/10.1016/0304-3800(95)00191-3.

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21

Swearingen, Michelle E., Ross E. Alter, Sarah McComas, and Mihan H. McKenna Taylor. "Spatial-resolution impacts on local infrasound propagation." Journal of the Acoustical Society of America 152, no. 2 (August 2022): 1090–105. http://dx.doi.org/10.1121/10.0013508.

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The accuracy of input meteorological data can significantly impact the successful prediction of infrasound propagation at local to near-regional distances. These meteorological inputs are often derived from weather model simulations when event-specific measurements are not available, but the ideal spatial resolutions of these simulations have not been determined. This study seeks to identify the ideal horizontal resolutions for input meteorological data via infrasound simulations conducted with both range-dependent and -independent inputs. Outputs from the Weather Research and Forecasting (WRF) model at 1, 3, 5, and 15 km horizontal resolutions enable these investigations. The parabolic equation propagation model is used to calculate transmission loss for an impulsive signal and is compared against experimental data obtained from a series of 1 lb spherical, suspended C4 shots recorded on the infrasound array on the Waterways Experiment Station in Vicksburg, MS, occurring throughout the diurnal cycle with an overall propagation distance of 14.5 km. Simulations for morning and nighttime correctly predict signal detection and non-detection. Transitional times of day (dawn, evening) were partially successful. Changing horizontal resolutions in WRF incurred greater differences in prediction results than use of range-dependence vs -independence. No clear picture emerged regarding the optimal horizontal resolution for meteorological inputs.

22

Kamrath, Matthew J., Vladimir Ostashev, D. Keith Wilson, Michael J. White, Carl R. Hart, and Anthony Finn. "Spatial coherence of vertical atmospheric sound propagation." Journal of the Acoustical Society of America 151, no. 4 (April 2022): A185. http://dx.doi.org/10.1121/10.0011043.

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Atmospheric turbulence causes the amplitude and phase of sound waves to fluctuate, which reduces the coherence of acoustic signals. Spatial coherence describes the similarity of two signals at different points in space, and a better understanding of acoustic coherence could lead to improved target detection, tracking, and identification. This presentation compares theoretical predictions and measurements of the acoustic spatial coherence. The theoretical coherence is derived by combining sound propagation theory with turbulence models that include the effects of atmospheric shear and buoyancy instabilities. To be applicable to vertical and slanted propagation, the turbulence models use height-dependent variances and length scales for the fluctuations in temperature, shear-produced velocity, and buoyancy-produced velocity. Instrumentation on a 135-m meteorological tower at the National Wind Technology Center (Boulder, CO) provided the required model input data. The coherence measurements used a ground-based source and nine microphones attached to the same meteorological tower. Overall, the theoretical model accurately approximated the measured spatial coherences, especially when the atmospheric turbulence was fully developed (e.g., in the afternoon on sunny days). The largest disagreement occurred for measurements taken at dawn. For a source frequency of 3.4 kHz and microphones that are 130 m high and 1.5 m apart, the measured coherence was 0.3–0.6 for sunny conditions and 0.8–0.9 for cloudy conditions.

23

Lin, Yuankai, Tao Cheng, Qi Zhong, Wending Zhou, and Hua Yang. "Dynamic Spatial Propagation Network for Depth Completion." Proceedings of the AAAI Conference on Artificial Intelligence 36, no. 2 (June 28, 2022): 1638–46. http://dx.doi.org/10.1609/aaai.v36i2.20055.

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Image-guided depth completion aims to generate dense depth maps with sparse depth measurements and corresponding RGB images. Currently, spatial propagation networks (SPNs) are the most popular affinity-based methods in depth completion, but they still suffer from the representation limitation of the fixed affinity and the over smoothing during iterations. Our solution is to estimate independent affinity matrices in each SPN iteration, but it is over-parameterized and heavy calculation.This paper introduces an efficient model that learns the affinity among neighboring pixels with an attention-based, dynamic approach. Specifically, the Dynamic Spatial Propagation Network (DySPN) we proposed makes use of a non-linear propagation model (NLPM). It decouples the neighborhood into parts regarding to different distances and recursively generates independent attention maps to refine these parts into adaptive affinity matrices. Furthermore, we adopt a diffusion suppression (DS) operation so that the model converges at an early stage to prevent over-smoothing of dense depth. Finally, in order to decrease the computational cost required, we also introduce three variations that reduce the amount of neighbors and attentions needed while still retaining similar accuracy. In practice, our method requires less iteration to match the performance of other SPNs and yields better results overall. DySPN outperforms other state-of-the-art (SoTA) methods on KITTI Depth Completion (DC) evaluation by the time of submission and is able to yield SoTA performance in NYU Depth v2 dataset as well.

24

Chamorro-Posada, P., G. S. McDonald, and G. H. C. New. "Propagation properties of non-paraxial spatial solitons." Journal of Modern Optics 47, no. 11 (September 2000): 1877–86. http://dx.doi.org/10.1080/09500340008232440.

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25

Cheng, Xinjing, Peng Wang, and Ruigang Yang. "Learning Depth with Convolutional Spatial Propagation Network." IEEE Transactions on Pattern Analysis and Machine Intelligence 42, no. 10 (October 1, 2020): 2361–79. http://dx.doi.org/10.1109/tpami.2019.2947374.

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26

Schoonover, Robert W., Brynmor J. Davis, Randy A. Bartels, and P. Scott Carney. "Propagation of spatial coherence in fast pulses." Journal of the Optical Society of America A 26, no. 9 (August 14, 2009): 1945. http://dx.doi.org/10.1364/josaa.26.001945.

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27

Liu, Chu-heng. "Spatial patterns of sound propagation in sand." Physical Review B 50, no. 2 (July 1, 1994): 782–94. http://dx.doi.org/10.1103/physrevb.50.782.

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28

van der Drift, J. H. M., and C. J. M. Heemskerk. "Propagation of Spatial Uncertainties Between Assembly Primitives." IFAC Proceedings Volumes 23, no. 3 (September 1990): 677–81. http://dx.doi.org/10.1016/s1474-6670(17)52638-5.

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29

Tóth, Ágota, Dezső Horváth, and Kenichi Yoshikawa. "Unidirectional wave propagation in one spatial dimension." Chemical Physics Letters 345, no. 5-6 (September 2001): 471–74. http://dx.doi.org/10.1016/s0009-2614(01)00903-4.

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Hao Wu, R. M. Fujimoto, G. F. Riley, and M. Hunter. "Spatial Propagation of Information in Vehicular Networks." IEEE Transactions on Vehicular Technology 58, no. 1 (January 2009): 420–31. http://dx.doi.org/10.1109/tvt.2008.923689.

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31

Skinner, S. R., G. R. Allan, D. R. Andersen, and A. L. Smirl. "Dark spatial soliton propagation in bulk ZnSe." IEEE Journal of Quantum Electronics 27, no. 9 (1991): 2211–19. http://dx.doi.org/10.1109/3.135180.

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32

Serdyukova, Nora. "Spatial adaptation in heteroscedastic regression: Propagation approach." Electronic Journal of Statistics 6 (2012): 861–907. http://dx.doi.org/10.1214/12-ejs693.

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33

Jones, R. D., and T. R. Scott. "Error propagation in laser beam spatial parameters." Optical and Quantum Electronics 26, no. 1 (January 1994): 25–34. http://dx.doi.org/10.1007/bf00573898.

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Dewachter, Hans, Romain Houssa, and Priscilla Toffano. "Spatial propagation of macroeconomic shocks in Europe." Review of World Economics 148, no. 2 (February 10, 2012): 377–402. http://dx.doi.org/10.1007/s10290-012-0118-1.

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LIÑARES, JESÚS, DAVID BARRAL, and MARÍA C. NISTAL. "SPATIAL PROPAGATION OF QUANTUM LIGHT IN NONLINEAR WAVEGUIDING DEVICES: THEORY AND APPLICATIONS." Journal of Nonlinear Optical Physics & Materials 21, no. 03 (September 2012): 1250032. http://dx.doi.org/10.1142/s0218863512500324.

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We present the main theoretical results on spatial propagation of quantum light in nonlinear waveguiding devices together with a few applications. We show that the quantization of the classical momentum provides a consistent quantum mechanical formulation of both the linear and the nonlinear quantum light propagation in waveguiding devices. The momentum operator allows us to derive the correct spatial Heisenberg's equations for the forward and backward absorption and emission operators and consequently to analyze the spatial propagation in the multimode optical-field strength space. For that purpose we use the Feynman's path integral method in order to derive the quantum spatial optical propagators of different nonlinear waveguiding devices and accordingly to calculate the spatial propagation of the optical-field strength probability amplitude of quantum states in these nonlinear devices. Likewise, we present a preliminary and heuristic formulation of quantum dissipation in order to take into account the losses under spatial quantum propagation in lossy nonlinear waveguiding devices. It must be stressed that these optical-field strength probabilities have the advantage of being measured by homodyne techniques and therefore their theoretical analysis is of a remarkable interest in the optical characterization of quantum states obtained under linear and nonlinear propagation in waveguiding devices.

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Zhang, Ruihui, Ming Zhang, Zhen Dong, Fei Wang, Yangjian Cai, and Yahong Chen. "Synthesis of Robust Full Poincaré Polarization States via Spatial Coherence Engineering." Photonics 11, no. 4 (March 22, 2024): 286. http://dx.doi.org/10.3390/photonics11040286.

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The full Poincaré (FP) beam, encompassing all possible polarization states in its beam cross-section, has demonstrated advantages in various applications. However, conventional FP beams are typically considered as spatially fully coherent, rendering them sensitive to disturbances in the propagation path and susceptible to speckle effects. In this work, we propose an alternative approach to synthesize the optical beam with a FP polarization state through the spatial coherence engineering of a partially coherent beam. In this process, the FP polarization state is initially encoded into the spatial coherence structure of the beam source. We demonstrate that during the encoding process, the vector nature of the beam transitions from the FP polarization state to the spatial coherence structure of the source. However, during the propagation of the partially coherent beam, the vectorness reverts to the polarization state, resulting in the re-emergence of the encoded FP polarization in the output plane. We illustrate that the synthesized FP polarization state, achieved through spatial coherence engineering, is highly robust against obstructions in the propagation path. Furthermore, we examine the effect of the spatial coherence area of the beam on the quality of the recovered FP polarization state. The findings of this work can have valuable applications in optical trapping and optical imaging in complex environments.

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Bravington, Mark V., David L. Miller, and Sharon L. Hedley. "Variance Propagation for Density Surface Models." Journal of Agricultural, Biological and Environmental Statistics 26, no. 2 (February 23, 2021): 306–23. http://dx.doi.org/10.1007/s13253-021-00438-2.

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AbstractSpatially explicit estimates of population density, together with appropriate estimates of uncertainty, are required in many management contexts. Density surface models (DSMs) are a two-stage approach for estimating spatially varying density from distance sampling data. First, detection probabilities—perhaps depending on covariates—are estimated based on details of individual encounters; next, local densities are estimated using a GAM, by fitting local encounter rates to location and/or spatially varying covariates while allowing for the estimated detectabilities. One criticism of DSMs has been that uncertainty from the two stages is not usually propagated correctly into the final variance estimates. We show how to reformulate a DSM so that the uncertainty in detection probability from the distance sampling stage (regardless of its complexity) is captured as an extra random effect in the GAM stage. In effect, we refit an approximation to the detection function model at the same time as fitting the spatial model. This allows straightforward computation of the overall variance via exactly the same software already needed to fit the GAM. A further extension allows for spatial variation in group size, which can be an important covariate for detectability as well as directly affecting abundance. We illustrate these models using point transect survey data of Island Scrub-Jays on Santa Cruz Island, CA, and harbour porpoise from the SCANS-II line transect survey of European waters. Supplementary materials accompanying this paper appear on-line.

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Hupeng, Wu, Jian Kang, and Jin Hong. "Effects of urban street spatial parameters on sound propagation." Environment and Planning B: Urban Analytics and City Science 46, no. 2 (June 14, 2017): 341–58. http://dx.doi.org/10.1177/2399808317714799.

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Many studies have demonstrated that the effect of urban street spatial shape on sound propagation cannot be ignored. Most previous studies are based on idealised spatial models and but not systematically and comprehensively examine the real and complex street space. This paper takes the actual streets of a high-density city as research objects, select reliable spatial parameters, obtain the acoustic propagation data using computer simulation, identify the sound propagation characteristics and establish sound propagation models of urban streets. In total, 144 samples have been tested, 13 spatial parameters, including the width information, height information, section information and plan information of streets, have been selected, and three acoustic indices, which include the sound attenuation, reverberation time and early decay time, have been analysed in this paper. The sound propagation in the urban street is consistent with the propagation characteristics of the semi-free sound field, i.e. the sound attenuation is linearly correlated with the logarithm of the sound propagation distance. This linear correlation becomes more pronounced for the greater Plan enclosure degree and more even distribution of façades. The trend of sound attenuations decreases with the increasing Cross-sectional enclosure degree, increasing Plan enclosure degree in the Near Zone or decreasing Vehicle lane width. Reverberation time is primarily distributed between 1.0 s and 3.0 s and tends to be stable when the propagation distance increases. The mean reverberation time increases with the increasing Mean façade height, Sidewalk width, Cross-sectional enclosure degree in the Near Zone or Standard deviation of Plan enclosure degree in the Near Zone. The typical early decay time distribution curve is clearly divided into two areas along the propagation direction. In the first area, the early decay time value is notably small and nearly equals zero. With a sudden increase, the early decay time maintains at a relatively stable value in the second area (stable area) of 0 to 3.0 s. The mean early decay time in the stable area increases with the increasing Vehicle lane width, increasing Cross-sectional enclosure degree or decreasing Standard deviation of Plan enclosure degree in the Near Zone.

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Palkar, Grishma, Jian-young Wu, and Bard Ermentrout. "The inhibitory control of traveling waves in cortical networks." PLOS Computational Biology 19, no. 9 (September 5, 2023): e1010697. http://dx.doi.org/10.1371/journal.pcbi.1010697.

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Propagating waves of activity can be evoked and can occur spontaneously in vivo and in vitro in cerebral cortex. These waves are thought to be instrumental in the propagation of information across cortical regions and as a means to modulate the sensitivity of neurons to subsequent stimuli. In normal tissue, the waves are sparse and tightly controlled by inhibition and other negative feedback processes. However, alterations of this balance between excitation and inhibition can lead to pathological behavior such as seizure-type dynamics (with low inhibition) or failure to propagate (with high inhibition). We develop a spiking one-dimensional network of neurons to explore the reliability and control of evoked waves and compare this to a cortical slice preparation where the excitability can be pharmacologically manipulated. We show that the waves enhance sensitivity of the cortical network to stimuli in specific spatial and temporal ways. To gain further insight into the mechanisms of propagation and transitions to pathological behavior, we derive a mean-field model for the synaptic activity. We analyze the mean-field model and a piece-wise constant approximation of it and study the stability of the propagating waves as spatial and temporal properties of the inhibition are altered. We show that that the transition to seizure-like activity is gradual but that the loss of propagation is abrupt and can occur via either the loss of existence of the wave or through a loss of stability leading to complex patterns of propagation.

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Tokarev, Alexey, Anastasia Mozokhina, and Vitaly Volpert. "Competition of SARS-CoV-2 Variants in Cell Culture and Tissue: Wins the Fastest Viral Autowave." Vaccines 10, no. 7 (June 22, 2022): 995. http://dx.doi.org/10.3390/vaccines10070995.

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Replication of viruses in living tissues and cell cultures is a “number game” involving complex biological processes (cell infection, virus replication inside infected cell, cell death, viral degradation) as well as transport processes limiting virus spatial propagation. In epithelial tissues and immovable cell cultures, viral particles are basically transported via Brownian diffusion. Highly non-linear kinetics of viral replication combined with diffusion limitation lead to spatial propagation of infection as a moving front switching from zero to high local viral concentration, the behavior typical of spatially distributed excitable media. We propose a mathematical model of viral infection propagation in cell cultures and tissues under the diffusion limitation. The model is based on the reaction–diffusion equations describing the concentration of uninfected cells, exposed cells (infected but still not shedding the virus), virus-shedding cells, and free virus. We obtain the expressions for the viral replication number, which determines the condition for spatial infection progression, and for the final concentration of uninfected cells. We determine analytically the speed of spatial infection propagation and validate it numerically. We calibrate the model to recent experimental data on SARS-CoV-2 Delta and Omicron variant replication in human nasal epithelial cells. In the case of competition of two virus variants in the same cell culture, the variant with larger individual spreading speed wins the competition and eliminates another one. These results give new insights concerning the emergence of new variants and their spread in the population.

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Yang, Fei, Huan Wang, and Zhong Jin. "A fusion network for road detection via spatial propagation and spatial transformation." Pattern Recognition 100 (April 2020): 107141. http://dx.doi.org/10.1016/j.patcog.2019.107141.

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Gorman, Arthur D. "Space-time caustics." International Journal of Mathematics and Mathematical Sciences 9, no. 3 (1986): 531–40. http://dx.doi.org/10.1155/s0161171286000662.

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The Lagrange manifold (WKB) formalism enables the determination of the asymptotic series solution of linear differential equations modelling wave propagation in spatially inhomogeneous media at caustic (turning) points. Here the formalism is adapted to determine a class of asymptotic solutions at caustic points for those equations modelling wave propagation in media with both spatial and temporal inhomogeneities. The analogous Schrodinger equation is also considered.

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Basham, Andrew, Brian E. Anderson, and Adam D. Kingsley. "Restricting angles of incidence to improve super resolution in time reversal focusing that uses metamaterial properties of a resonator array." Journal of the Acoustical Society of America 155, no. 5 (May 1, 2024): 3233–41. http://dx.doi.org/10.1121/10.0025987.

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Focusing waves with a spatial extent smaller than a half wavelength (i.e., super resolution or sub diffraction limit) is possible using resonators placed in the near field of time reversal (TR) focusing. While a two-dimensional (2D) Helmholtz resonator array in a three-dimensional reverberant environment has limited ability to produce a high-resolution spatial focus in the TR focusing of audible sound, it is shown that acoustic waves propagating out-of-plane with the resonator array are not as strongly affected by the smaller effective wavelength induced by the resonator array, partially negating the effect of the resonators. A physical 2D waveguide is shown to limit the out-of-plane propagation, leading to improved resolution. It is also shown that post processing using an orthogonal particle velocity decomposition of a spatial scan of the focusing can filter out-of-plane particle motion in the near field of the array, which bypasses the effect of the unwanted third spatial dimension of propagation. The spatial resolution in a reverberant environment is shown to improve in the presence of a 2D Helmholtz resonator array and then further improve by adding a 2D waveguide. The resolution among the resonator array is better still without using a waveguide and instead using the partial-pressure reconstruction.

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Evers, Frederic M., and Willi H. Hager. "GENERATION AND SPATIAL PROPAGATION OF LANDSLIDE GENERATED IMPULSE WAVES." Coastal Engineering Proceedings, no. 35 (June 23, 2017): 13. http://dx.doi.org/10.9753/icce.v35.currents.13.

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Large subaerial mass wasting into water may generate large waves along coast lines and in bays. Hazard assessment of such an events is based on the decay rate of these impulse waves along their propagation path to populated areas and infrastructure along the shoreline. The spatial propagation processes of impulse waves generated by deformable slides was investigated in a wave basin. A videometric measurement approach allowed for a detailed tracking of the free water surface and key wave characteristics during the experimental runs including the wave height. Based on selected tests, the slide width effect on spatial wave propagation is discussed.

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DOELMAN, ARJEN, BJÖRN SANDSTEDE, ARND SCHEEL, and GUIDO SCHNEIDER. "Propagation of hexagonal patterns near onset." European Journal of Applied Mathematics 14, no. 1 (February 2003): 85–110. http://dx.doi.org/10.1017/s095679250200503x.

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For a pattern-forming system with two unbounded spatial directions that is near the onset to instability, we prove the existence of modulated fronts that connect (i) stable hexagons with the unstable trivial pattern, (ii) stable hexagons with unstable roll solutions, (iii) stable hexagons with unstable hexagons, and (iv) stable roll solutions with unstable hexagons. Our approach is based on spatial dynamics, bifurcation theory, and geometric singular perturbation theory.

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Blom, Philip S. "Regional and global scale propagation simulations of infrasonic signals." Journal of the Acoustical Society of America 153, no. 3_supplement (March 1, 2023): A218. http://dx.doi.org/10.1121/10.0018708.

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Infrasonic signals are frequently observed at large propagation distances of 100s to 1000s of kilometers from the source and, in extreme cases, signals have been observed to circle the globe. Simulating acoustic propagation at these large scales requires a framework that not only accounts for 3D propagation effects including along- and cross-path winds, but also for the non-Cartesian geometry of the atmospheric layer surrounding the globe. Furthermore, interaction of propagating infrasonic energy with terrain features is known to have a notable impact on signals, particularly when the wavelength of the signals is comparable to the terrain scale. Finally, spatial variations in the atmospheric structure beyond simple stratification can have significant impacts on propagation paths. Numerical tools for acoustic ray tracing that account for these and other complications will be detailed and demonstrated using several recent infrasonic events of interest.

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MOSQUERA, J., M. GÓMEZ-GESTEIRA, V. PÉREZ-MUÑUZURI, A. P. MUÑUZURI, and V. PÉREZ-VILLAR. "ELECTRIC FIELD INFLUENCE ON TRAVELING WAVE PROPAGATION AND STATIONARY PATTERN FORMATION." International Journal of Bifurcation and Chaos 05, no. 03 (June 1995): 797–807. http://dx.doi.org/10.1142/s0218127495000582.

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The electric field influence on pattern formation and traveling wave propagation is investigated in the framework of the Oregonator model. When an electric field is applied to a system that can suffer spatial instabilities, Turing and Turing-like patterns (traveling fronts that become stationary patterns when reaching a zero-flux boundary) are observed. On the other hand, when an electric field is applied to a system that cannot become unstable by spatial terms and where wavefronts are propagating in the absence of electric fields, the velocity of these wavefronts is modified and can even be reversed. This is in good agreement with previous experimental results.

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Liu, Ruixian, Peter Gerstoft, Michael J. Bianco, and Bhaskar D. Rao. "Recovery of spatially varying acoustical properties via automated partial differential equation identification." Journal of the Acoustical Society of America 153, no. 6 (June 1, 2023): 3169. http://dx.doi.org/10.1121/10.0019592.

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Observable dynamics, such as waves propagating on a surface, are generally governed by partial differential equations (PDEs), which are determined by the physical properties of the propagation media. The spatial variations of these properties lead to spatially dependent PDEs. It is useful in many fields to recover the variations from the observations of dynamical behaviors on the material. A method is proposed to form a map of the physical properties' spatial variations for a material via data-driven spatially dependent PDE identification and applied to recover acoustical properties (viscosity, attenuation, and phase speeds) for propagating waves. The proposed data-driven PDE identification scheme is based on ℓ1-norm minimization. It does not require any PDE term that is assumed active from the prior knowledge and is the first approach that is capable of identifying spatially dependent PDEs from measurements of phenomena. In addition, the method is efficient as a result of its non-iterative nature and can be robust against noise if used with an integration transformation technique. It is demonstrated in multiple experimental settings, including real laser measurements of a vibrating aluminum plate. Codes and data are available online at https://tinyurl.com/4wza8vxs.

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Ge, Haimiao, Liguo Wang, Haizhu Pan, Yuexia Zhu, Xiaoyu Zhao, and Moqi Liu. "Affinity Propagation Based on Structural Similarity Index and Local Outlier Factor for Hyperspectral Image Clustering." Remote Sensing 14, no. 5 (February 28, 2022): 1195. http://dx.doi.org/10.3390/rs14051195.

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In hyperspectral remote sensing, the clustering technique is an important issue of concern. Affinity propagation is a widely used clustering algorithm. However, the complex structure of the hyperspectral image (HSI) dataset presents challenge for the application of affinity propagation. In this paper, an improved version of affinity propagation based on complex wavelet structural similarity index and local outlier factor is proposed specifically for the HSI dataset. In the proposed algorithm, the complex wavelet structural similarity index is used to calculate the spatial similarity of HSI pixels. Meanwhile, the calculation strategy of the spatial similarity is simplified to reduce the computational complexity. The spatial similarity and the traditional spectral similarity of the HSI pixels jointly constitute the similarity matrix of affinity propagation. Furthermore, the local outlier factors are applied as weights to revise the original exemplar preferences of the affinity propagation. Finally, the modified similarity matrix and exemplar preferences are applied, and the clustering index is obtained by the traditional affinity propagation. Extensive experiments were conducted on three HSI datasets, and the results demonstrate that the proposed method can improve the performance of the traditional affinity propagation and provide competitive clustering results among the competitors.

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Xu, Wen-Bing, Wan-Tong Li, and Shigui Ruan. "Spatial propagation in nonlocal dispersal Fisher-KPP equations." Journal of Functional Analysis 280, no. 10 (May 2021): 108957. http://dx.doi.org/10.1016/j.jfa.2021.108957.

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