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Journal articles on the topic 'Spatio-Temporal properties'

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Published: 7 July 2024

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1

Chung, Susana T. L. "Spatio-temporal properties of letter crowding." Journal of Vision 16, no. 6 (April 18, 2016): 8. http://dx.doi.org/10.1167/16.6.8.

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2

Rokszin, Alice, Zita Márkus, Gábor Braunitzer, Antal Berényi, Marek Wypych, Wioletta Waleszczyk, György Benedek, and Attila Nagy. "Spatio-temporal visual properties in the ascending tectofugal system." Open Life Sciences 5, no. 1 (February 1, 2010): 21–30. http://dx.doi.org/10.2478/s11535-009-0065-6.

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AbstractOur study compares the spatio-temporal visual receptive field properties of different subcortical stages of the ascending tectofugal visual system. Extracellular single-cell recordings were performed in the superficial (SCs) and intermediate (SCi) layers of the superior colliculus (SC), the suprageniculate nucleus (Sg) of the posterior thalamus and the caudate nucleus (CN) of halothane-anesthetized cats. Neuronal responses to drifting gratings of various spatial and temporal frequencies were recorded. The neurons of each structure responded optimally to low spatial and high temporal frequencies and displayed narrow spatial and temporal frequency tuning. The detailed statistical analysis revealed that according to its stimulus preferences the SCs has markedly different spatio-temporal properties from the homogeneous group formed by the SCi, Sg and CN. The SCs neurons preferred higher spatial and lower temporal frequencies and had broader spatial tuning than the other structures. In contrast to the SCs the visually active SCi, as well as the Sg and the CN neurons possessed consequently similar spatio-temporal preferences. These data support our hypothesis that the visually active SCi, Sg and CN neurons form a homogeneous neuronal population given a similar spatio-temporal frequency preference and a common function in processing of dynamic visual information.
3

Nameda, Naoyoshi, and Hitoshi Ohzu. "Spatio-temporal Frequency Properties according to Ages." JOURNAL OF THE ILLUMINATING ENGINEERING INSTITUTE OF JAPAN 70, Appendix (1986): 77. http://dx.doi.org/10.2150/jieij1980.70.appendix_77.

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4

Campbell, Keith. "Unit Properties, Relations, and Spatio-Temporal Naturalism." Modern Schoolman 79, no. 2 (2002): 151–62. http://dx.doi.org/10.5840/schoolman2002792/39.

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5

Baek, Seung-Hwan, and Felix Heide. "Polarimetric spatio-temporal light transport probing." ACM Transactions on Graphics 40, no. 6 (December 2021): 1–18. http://dx.doi.org/10.1145/3478513.3480517.

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Light emitted from a source into a scene can undergo complex interactions with multiple scene surfaces of different material types before being reflected towards a detector. During this transport, every surface reflection and propagation is encoded in the properties of the photons that ultimately reach the detector, including travel time, direction, intensity, wavelength and polarization. Conventional imaging systems capture intensity by integrating over all other dimensions of the incident light into a single quantity, hiding this rich scene information in these aggregate measurements. Existing methods are capable of untangling these measurements into their spatial and temporal dimensions, fueling geometric scene understanding tasks. However, examining polarimetric material properties jointly with geometric properties is an open challenge that could enable unprecedented capabilities beyond geometric scene understanding, allowing for material-dependent scene understanding and imaging through complex transport, such as macroscopic scattering. In this work, we close this gap, and propose a computational light transport imaging method that captures the spatially- and temporally-resolved complete polarimetric response of a scene, which encodes rich material properties. Our method hinges on a novel 7D tensor theory of light transport. We discover low-rank structure in the polarimetric tensor dimension and propose a data-driven rotating ellipsometry method that learns to exploit redundancy of polarimetric structure. We instantiate our theory with two imaging prototypes: spatio-polarimetric imaging and coaxial temporal-polarimetric imaging. This allows us, for the first time, to decompose scene light transport into temporal, spatial, and complete polarimetric dimensions that unveil scene properties hidden to conventional methods. We validate the applicability of our method on diverse tasks, including shape reconstruction with subsurface scattering, seeing through scattering media, untangling multi-bounce light transport, breaking metamerism with polarization, and spatio-polarimetric decomposition of crystals.
6

Rodríguez Berrio, Juan F., Francisco J. Rodríguez-Cortes, Jorge Mateu, and Giada Adelfio. "On Some Statistical Properties of the Spatio-Temporal Product Density." Revista Colombiana de Estadística 44, no. 1 (January 15, 2021): 23–42. http://dx.doi.org/10.15446/rce.v44n1.84779.

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We present an extension of the non-parametric edge-corrected Ohser-type kernel estimator for the spatio-temporal product density function. We derive the mean and variance of the estimator and give a closed-form approximation for a spatio-temporal Poisson point process. Asymptotic properties of this second-order characteristic are derived, using an approach based on martingale theory. Taking advantage of the convergence to normality, confidence surfaces under the homogeneous Poisson process are built. A simulation study is presented to compare our approximation for the variance with Monte Carlo estimated values. Finally, we apply the resulting estimator and its properties to analyse the spatio-temporal distribution of the invasive meningococcal disease in the Rhineland Regional Council in Germany.
7

Zhang, Zijian, Xiangyu Zhao, Hao Miao, Chunxu Zhang, Hongwei Zhao, and Junbo Zhang. "AutoSTL: Automated Spatio-Temporal Multi-Task Learning." Proceedings of the AAAI Conference on Artificial Intelligence 37, no. 4 (June 26, 2023): 4902–10. http://dx.doi.org/10.1609/aaai.v37i4.25616.

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Spatio-temporal prediction plays a critical role in smart city construction. Jointly modeling multiple spatio-temporal tasks can further promote an intelligent city life by integrating their inseparable relationship. However, existing studies fail to address this joint learning problem well, which generally solve tasks individually or a fixed task combination. The challenges lie in the tangled relation between different properties, the demand for supporting flexible combinations of tasks and the complex spatio-temporal dependency. To cope with the problems above, we propose an Automated Spatio-Temporal multi-task Learning (AutoSTL) method to handle multiple spatio-temporal tasks jointly. Firstly, we propose a scalable architecture consisting of advanced spatio-temporal operations to exploit the complicated dependency. Shared modules and feature fusion mechanism are incorporated to further capture the intrinsic relationship between tasks. Furthermore, our model automatically allocates the operations and fusion weight. Extensive experiments on benchmark datasets verified that our model achieves state-of-the-art performance. As we can know, AutoSTL is the first automated spatio-temporal multi-task learning method.
8

Steadman, Liam, Nathan Griffiths, Stephen Jarvis, Mark Bell, Shaun Helman, and Caroline Wallbank. "k D-STR: A Method for Spatio-Temporal Data Reduction and Modelling." ACM/IMS Transactions on Data Science 2, no. 3 (May 17, 2021): 1–31. http://dx.doi.org/10.1145/3439334.

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Analysing and learning from spatio-temporal datasets is an important process in many domains, including transportation, healthcare and meteorology. In particular, data collected by sensors in the environment allows us to understand and model the processes acting within the environment. Recently, the volume of spatio-temporal data collected has increased significantly, presenting several challenges for data scientists. Methods are therefore needed to reduce the quantity of data that needs to be processed in order to analyse and learn from spatio-temporal datasets. In this article, we present the - Dimensional Spatio-Temporal Reduction method ( D-STR ) for reducing the quantity of data used to store a dataset whilst enabling multiple types of analysis on the reduced dataset. D-STR uses hierarchical partitioning to find spatio-temporal regions of similar instances, and models the instances within each region to summarise the dataset. We demonstrate the generality of D-STR with three datasets exhibiting different spatio-temporal characteristics and present results for a range of data modelling techniques. Finally, we compare D-STR with other techniques for reducing the volume of spatio-temporal data. Our results demonstrate that D-STR is effective in reducing spatio-temporal data and generalises to datasets that exhibit different properties.
9

Huang, Huang, and Ying Sun. "Visualization and assessment of spatio-temporal covariance properties." Spatial Statistics 34 (December 2019): 100272. http://dx.doi.org/10.1016/j.spasta.2017.11.004.

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10

Liu, Liang, Bin Chen, Wangchun Jiang, Lingnan He, and Xiaogang Qiu. "Spatio-temporal dynamics of web pages diffused in WeChat." Information Discovery and Delivery 45, no. 3 (August 21, 2017): 139–48. http://dx.doi.org/10.1108/idd-05-2017-0044.

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Purpose WeChat is the largest acquaintance social networking platform in China, in which users can view and reshare web pages shared by friends. This paper aims to analyze the spatio-temporal dynamics of web pages diffused in WeChat and advice on commercials. Design/methodology/approach A large number of web pages diffused in WeChat are collected and exclusively divided into four categories according to their titles, including advertisements, news bulletins, holiday greetings and emotional essays. For each web page, an information cascade (tree structure) is constructed to describe the diffusion trace. Based on the categories, the spatio-temporal popularity is characterized; the topological, temporal and spatial properties are examined; and the spatio-temporal diffusion velocity is explored. Findings Through comparative analysis, different categories of pages show diversity. For spatio-temporal popularity, there is no significant difference in cascade size; holiday greetings usually last for a relatively short time on average; emotional essays are more likely to spread to more provinces. For topological, temporal and spatial characteristics, the diffusion process of advertisements is more likely to be broadcasting than other categories; news bulletins and holiday greetings have an obvious bursty; the number of viewing behavior decreases from east to west in general. For spatio-temporal diffusion velocity, emotional essays diffuse the fastest in topological and spatio-temporal dimensions. Originality/value These findings contribute to promoting products and providing support for data driven modeling of information diffusion and human activity in spatio-temporal dimensions.
11

Corpas-Burgos, Francisca, and Miguel A. Martinez-Beneito. "An Autoregressive Disease Mapping Model for Spatio-Temporal Forecasting." Mathematics 9, no. 4 (February 14, 2021): 384. http://dx.doi.org/10.3390/math9040384.

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One of the more evident uses of spatio-temporal disease mapping is forecasting the spatial distribution of diseases for the next few years following the end of the period of study. Spatio-temporal models rely on very different modeling tools (polynomial fit, splines, time series, etc.), which could show very different forecasting properties. In this paper, we introduce an enhancement of a previous autoregressive spatio-temporal model with particularly interesting forecasting properties, given its reliance on time series modeling. We include a common spatial component in that model and show how that component improves the previous model in several ways, its predictive capabilities being one of them. In this paper, we introduce and explore the theoretical properties of this model and compare them with those of the original autoregressive model. Moreover, we illustrate the benefits of this new model with the aid of a comprehensive study on 46 different mortality data sets in the Valencian Region (Spain) where the benefits of the new proposed model become evident.
12

Tominac, Philip A., Weiqi Zhang, and Victor M. Zavala. "Spatio-temporal economic properties of multi-product supply chains." Computers & Chemical Engineering 159 (March 2022): 107666. http://dx.doi.org/10.1016/j.compchemeng.2022.107666.

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13

Le Cain, A., G. Riazuelo, and J. M. Sajer. "Statistical spatio-temporal properties of the Laser MegaJoule speckle." Physics of Plasmas 19, no. 10 (October 2012): 102704. http://dx.doi.org/10.1063/1.4757221.

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14

Yang, Yongjian, Yuanbo Xu, Jiayu Han, En Wang, Weitong Chen, and Lin Yue. "Efficient traffic congestion estimation using multiple spatio-temporal properties." Neurocomputing 267 (December 2017): 344–53. http://dx.doi.org/10.1016/j.neucom.2017.06.017.

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15

Huber, Reinhold, Christoph Nowak, and Bernhard Spatzek. "Image acquisition using aperture controladapted to spatio-temporal properties." Machine Vision and Applications 15, no. 4 (October 2004): 204–15. http://dx.doi.org/10.1007/s00138-004-0154-5.

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16

KANG, HUNSEOK. "SPATIO-TEMPORAL CHAOS IN A DISCRETE TURING MODEL." International Journal of Bifurcation and Chaos 20, no. 11 (November 2010): 3741–52. http://dx.doi.org/10.1142/s0218127410028008.

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In this paper, we present a study of a discrete version of a reaction–diffusion system which corresponds to the Turing model of morphogenesis. We present a review on spatio-temporal chaos in lattice systems, and then show that the discrete version possesses a hyperbolic property displaying spatio-temporal chaos. Finally, some numerical computation will be performed to observe the hyperbolic properties of the system.
17

Gatti, Alessandra, Lucia Caspani, Tommaso Corti, Enrico Brambilla, and Ottavia Jedrkiewicz. "Spatio–temporal entanglement of twin photons: An intuitive picture." International Journal of Quantum Information 12, no. 02 (March 2014): 1461016. http://dx.doi.org/10.1142/s0219749914610164.

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We draw an intuitive picture of the spatio–temporal properties of the entangled state of twin photons, where they are described as classical wave-packets. This picture predicts a precise relation between their temporal and transverse spatial separations at the crystal output. The space-time coupling described by classical arguments turns out to determine in a precise way the spatio–temporal structure of the quantum entanglement, analyzed by means of the biphotonic correlation and of the Schmidt dimensionality of the entanglement.
18

Miralles, André, François Pinet, and Yvan Bédard. "Describing Spatio-Temporal Phenomena for Environmental System Development." International Journal of Agricultural and Environmental Information Systems 1, no. 2 (July 2010): 68–84. http://dx.doi.org/10.4018/jaeis.2010070104.

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This paper is composed of two parts dealing with the modeling of environmental phenomena. The first part presents the traditional ER and OO formalisms dedicated to geographic information modeling. These languages focus mainly on representing the spatial and temporal properties of this type of information. Many of these languages express these properties visually by using pictograms. After a quick historical presentation of the languages, the authors show the various types of spatiality and temporality usually encountered in these languages. Often qualified as primitive, some of these spatialities and temporalities are simple. Others, which are more complex, result from combinations of simple spatialities and simple temporalities. Still others are used in very specific situations encountered during the development of geographical information systems. These different spatialities and temporalities are presented via examples provided in the field of environmental dynamics.
19

Chen, Qiaoling. "A variational principle for fractal Klein-Gordon equation." Thermal Science 27, no. 3 Part A (2023): 1803–10. http://dx.doi.org/10.2298/tsci2303803c.

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This paper studies the Klein-Gordon equation and two modifications in an infinite Cantor set and a fractal space-time. Their variational formulations are established and discussed, and the spatio-temporal discontinuity requires both spatio-fractal derivative and temporal fractal derivative for practical applications. Some basic properties of the local fractional derivative and the two-scale fractal derivative are elucidated, and the derivation of the Euler-Lagrange equation is illustrated.
20

Goldstein, Joshua, Jaewoo Park, Murali Haran, Andrew Liebhold, and Ottar N. Bjørnstad. "Quantifying spatio-temporal variation of invasion spread." Proceedings of the Royal Society B: Biological Sciences 286, no. 1894 (January 9, 2019): 20182294. http://dx.doi.org/10.1098/rspb.2018.2294.

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— The spread of invasive species can have far-reaching environmental and ecological consequences. Understanding invasion spread patterns and the underlying process driving invasions are key to predicting and managing invasions. — We combine a set of statistical methods in a novel way to characterize local spread properties and demonstrate their application using simulated and historical data on invasive insects. Our method uses a Gaussian process fit to the surface of waiting times to invasion in order to characterize the vector field of spread. — Using this method, we estimate with statistical uncertainties the speed and direction of spread at each location. Simulations from a stratified diffusion model verify the accuracy of our method. — We show how we may link local rates of spread to environmental covariates for two case studies: the spread of the gypsy moth ( Lymantria dispar ), and hemlock woolly adelgid ( Adelges tsugae ) in North America. We provide an R-package that automates the calculations for any spatially referenced waiting time data.
21

Grace, Miriam, and Marc-Thorsten Hütt. "Predictability of spatio-temporal patterns in a lattice of coupled FitzHugh–Nagumo oscillators." Journal of The Royal Society Interface 10, no. 81 (April 6, 2013): 20121016. http://dx.doi.org/10.1098/rsif.2012.1016.

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In many biological systems, variability of the components can be expected to outrank statistical fluctuations in the shaping of self-organized patterns. In pioneering work in the late 1990s, it was hypothesized that a drift of cellular parameters (along a ‘developmental path’), together with differences in cell properties (‘desynchronization’ of cells on the developmental path) can establish self-organized spatio-temporal patterns (in their example, spiral waves of cAMP in a colony of Dictyostelium discoideum cells) starting from a homogeneous state. Here, we embed a generic model of an excitable medium, a lattice of diffusively coupled FitzHugh–Nagumo oscillators, into a developmental-path framework. In this minimal model of spiral wave generation, we can now study the predictability of spatio-temporal patterns from cell properties as a function of desynchronization (or ‘spread’) of cells along the developmental path and the drift speed of cell properties on the path. As a function of drift speed and desynchronization, we observe systematically different routes towards fully established patterns, as well as strikingly different correlations between cell properties and pattern features. We show that the predictability of spatio-temporal patterns from cell properties contains important information on the pattern formation process as well as on the underlying dynamical system.
22

OKABE, Takumi, Ryuichi YANAGAWA, Shin-ichi AOKI, and Shigeru KATO. "Spatio-temporal Properties of Currents off the Tenryu River Mouth." Journal of Japan Society of Civil Engineers, Ser. B2 (Coastal Engineering) 67, no. 2 (2011): I_336—I_340. http://dx.doi.org/10.2208/kaigan.67.i_336.

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23

Huang, P. C., D. H. Baker, and R. F. Hess. "Interocular suppression in normal and amblyopic vision: Spatio-temporal properties." Journal of Vision 12, no. 11 (October 31, 2012): 29. http://dx.doi.org/10.1167/12.11.29.

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24

Pereira, Tiago M. D., Bart De Pontieu, and Mats Carlsson. "THE EFFECTS OF SPATIO-TEMPORAL RESOLUTION ON DEDUCED SPICULE PROPERTIES." Astrophysical Journal 764, no. 1 (January 28, 2013): 69. http://dx.doi.org/10.1088/0004-637x/764/1/69.

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25

Chia, Kohleth, and Morgan Sangeux. "Undesirable properties of the dimensionless normalisation for spatio-temporal variables." Gait & Posture 55 (June 2017): 157–61. http://dx.doi.org/10.1016/j.gaitpost.2017.04.014.

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26

Vissat, Ludovica Luisa, Michele Loreti, Laura Nenzi, Jane Hillston, and Glenn Marion. "Analysis of Spatio-temporal Properties of Stochastic Systems Using TSTL." ACM Transactions on Modeling and Computer Simulation 29, no. 4 (December 17, 2019): 1–24. http://dx.doi.org/10.1145/3326168.

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27

Pang, J. C., P. A. Robinson, and K. M. Aquino. "Response-mode decomposition of spatio-temporal haemodynamics." Journal of The Royal Society Interface 13, no. 118 (May 2016): 20160253. http://dx.doi.org/10.1098/rsif.2016.0253.

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The blood oxygen-level dependent (BOLD) response to a neural stimulus is analysed using the transfer function derived from a physiologically based poroelastic model of cortical tissue. The transfer function is decomposed into components that correspond to distinct poles, each related to a response mode with a natural frequency and dispersion relation; together these yield the total BOLD response. The properties of the decomposed components provide a deeper understanding of the nature of the BOLD response, via the components' frequency dependences, spatial and temporal power spectra, and resonances. The transfer function components are then used to separate the BOLD response to a localized impulse stimulus, termed the Green function or spatio-temporal haemodynamic response function, into component responses that are explicitly related to underlying physiological quantities. The analytical results also provide a quantitative tool to calculate the linear BOLD response to an arbitrary neural drive, which is faster to implement than direct Fourier transform methods. The results of this study can be used to interpret functional magnetic resonance imaging data in new ways based on physiology, to enhance deconvolution methods and to design experimental protocols that can selectively enhance or suppress particular responses, to probe specific physiological phenomena.
28

Cecconi, Vittorio, Vivek Kumar, Alessia Pasquazi, Juan Sebastian Totero Gongora, and Marco Peccianti. "Nonlinear field-control of terahertz waves in random media for spatiotemporal focusing." Open Research Europe 2 (August 1, 2022): 32. http://dx.doi.org/10.12688/openreseurope.14508.2.

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Controlling the transmission of broadband optical pulses in scattering media is a critical open challenge in photonics. To date, wavefront shaping techniques at optical frequencies have been successfully applied to control the spatial properties of multiple-scattered light. However, a fundamental restriction in achieving an equivalent degree of control over the temporal properties of a broadband pulse is the limited availability of experimental techniques to detect the coherent properties (i.e., the spectral amplitude and absolute phase) of the transmitted field. Terahertz experimental frameworks, on the contrary, enable measuring the field dynamics of broadband pulses at ultrafast (sub-cycle) time scales directly. In this work, we provide a theoretical/numerical demonstration that, within this context, complex scattering can be used to achieve spatio-temporal control of instantaneous fields and manipulate the temporal properties of single-cycle pulses by solely acting on spatial degrees of freedom of the illuminating field. As direct application scenarios, we demonstrate spatio-temporal focusing, chirp compensation, and control of the carrier-envelope-phase (CEP) of a CP-stable, transform-limited THz pulse.
29

Cecconi, Vittorio, Vivek Kumar, Alessia Pasquazi, Juan Sebastian Totero Gongora, and Marco Peccianti. "Nonlinear field-control of terahertz waves in random media for spatiotemporal focusing." Open Research Europe 2 (March 8, 2022): 32. http://dx.doi.org/10.12688/openreseurope.14508.1.

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Controlling the transmission of broadband optical pulses in scattering media is a critical open challenge in photonics. To date, wavefront shaping techniques at optical frequencies have been successfully applied to control the spatial properties of multiple-scattered light. However, a fundamental restriction in achieving an equivalent degree of control over the temporal properties of a broadband pulse is the limited availability of experimental techniques to detect the coherent properties (i.e., the spectral amplitude and absolute phase) of the transmitted field. Terahertz experimental frameworks, on the contrary, enable measuring the field dynamics of broadband pulses at ultrafast (sub-cycle) time scales directly. In this work, we provide a theoretical/numerical demonstration that, within this context, complex scattering can be used to achieve spatio-temporal control of instantaneous fields and manipulate the temporal properties of single-cycle pulses by solely acting on spatial degrees of freedom of the illuminating field. As direct application scenarios, we demonstrate spatio-temporal focusing, chirp compensation, and control of the carrier-envelope-offset of a transform-limited THz pulse.
30

Cecconi, Vittorio, Vivek Kumar, Alessia Pasquazi, Juan Sebastian Totero Gongora, and Marco Peccianti. "Nonlinear field-control of terahertz waves in random media for spatiotemporal focusing." Open Research Europe 2 (February 13, 2023): 32. http://dx.doi.org/10.12688/openreseurope.14508.3.

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Controlling the transmission of broadband optical pulses in scattering media is a critical open challenge in photonics. To date, wavefront shaping techniques at optical frequencies have been successfully applied to control the spatial properties of multiple-scattered light. However, a fundamental restriction in achieving an equivalent degree of control over the temporal properties of a broadband pulse is the limited availability of experimental techniques to detect the coherent properties (i.e., the spectral amplitude and absolute phase) of the transmitted field. Terahertz experimental frameworks, on the contrary, enable measuring the field dynamics of broadband pulses at ultrafast (sub-cycle) time scales directly. In this work, we provide a theoretical/numerical demonstration that, within this context, complex scattering can be used to achieve spatio-temporal control of instantaneous fields and manipulate the temporal properties of single-cycle pulses by solely acting on spatial degrees of freedom of the illuminating field. As direct application scenarios, we demonstrate spatio-temporal focusing, chirp compensation, and control of the carrier-envelope-phase (CEP) of a CP-stable, transform-limited THz pulse.
31

Vidal, J. P., E. Martin, N. Kitova, J. Najac, and J. M. Soubeyroux. "Evolution of spatio-temporal drought characteristics: validation, projections and effect of adaptation scenarios." Hydrology and Earth System Sciences Discussions 9, no. 2 (February 3, 2012): 1619–70. http://dx.doi.org/10.5194/hessd-9-1619-2012.

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Abstract. Drought events develop in both space and time and they are therefore best described through summary joint spatio-temporal characteristics, like mean duration, mean affected area and total magnitude. This paper addresses the issue of future projections of such characteristics of drought events over France through three main research questions: (1) are downscaled climate projections able to reproduce spatio-temporal characteristics of meteorological and agricultural droughts in France over a present-day period? (2) How such characteristics will evolve over the 21st century? (3) How to use standardized drought indices to represent theoretical adaptation scenarios? These questions are addressed using the Isba land surface model, downscaled climate projections from the ARPEGE General Circulation Model under three emissions scenarios, as well as results from a previously performed 50-yr multilevel and multiscale drought reanalysis over France. Spatio-temporal characteristics of meteorological and agricultural drought events are computed using the Standardized Precipitation Index and the Standardized Soil Wetness Index, respectively, and for time scales of 3 and 12 months. Results first show that the distributions of joint spatio-temporal characteristics of observed events are well reproduced by the downscaled hydroclimate projections over a present-day period. All spatio-temporal characteristics of drought events are then found to dramatically increase over the 21st century, with stronger changes for agricultural droughts. Two theoretical adaptation scenarios are eventually built based on hypotheses of adaptation to evolving climate and hydrological normals, either retrospective or prospective, and by taking advantage of the statistical properties of the standardized drought indices. The perceived spatio-temporal characteristics of drought events derived from these theoretical adaptation scenarios show much reduced changes, but they call for more realistic scenarios at both the catchment and national scale in order to accurately assess the combined effect of local-scale adaptation and global-scale mitigation.
32

Lin, Jimmy, Junkai Li, Jiasi Gao, Weizhi Ma, and Yang Liu. "Jointly Modeling Spatio-Temporal Features of Tactile Signals for Action Classification." Proceedings of the AAAI Conference on Artificial Intelligence 38, no. 12 (March 24, 2024): 13817–25. http://dx.doi.org/10.1609/aaai.v38i12.29288.

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Tactile signals collected by wearable electronics are essential in modeling and understanding human behavior. One of the main applications of tactile signals is action classification, especially in healthcare and robotics. However, existing tactile classification methods fail to capture the spatial and temporal features of tactile signals simultaneously, which results in sub-optimal performances. In this paper, we design Spatio-Temporal Aware tactility Transformer (STAT) to utilize continuous tactile signals for action classification. We propose spatial and temporal embeddings along with a new temporal pretraining task in our model, which aims to enhance the transformer in modeling the spatio-temporal features of tactile signals. Specially, the designed temporal pretraining task is to differentiate the time order of tubelet inputs to model the temporal properties explicitly. Experimental results on a public action classification dataset demonstrate that our model outperforms state-of-the-art methods in all metrics.
33

Pérez-Torres, Rafael, César Torres-Huitzil, and Hiram Galeana-Zapién. "A Spatio-Temporal Approach to Individual Mobility Modeling in On-Device Cognitive Computing Platforms." Sensors 19, no. 18 (September 12, 2019): 3949. http://dx.doi.org/10.3390/s19183949.

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The increased availability of GPS-enabled devices makes possible to collect location data for mining purposes and to develop mobility-based services (MBS). For most of the MBSs, determining interesting locations and frequent Points of Interest (POIs) is of paramount importance to study the semantic of places visited by an individual and the mobility patterns as a spatio-temporal phenomenon. In this paper, we propose a novel approach that uses mobility-based services for on-device and individual-centered mobility understanding. Unlike existing approaches that use crowd data for cloud-assisted POI extraction, the proposed solution autonomously detects POIs and mobility events to incrementally construct a cognitive map (spatio-temporal model) of individual mobility suitable to constrained mobile platforms. In particular, we focus on detecting POIs and enter-exits events as the key to derive statistical properties for characterizing the dynamics of an individual’s mobility. We show that the proposed spatio-temporal map effectively extracts core features from the user-POI interaction that are relevant for analytics such as mobility prediction. We also demonstrate how the obtained spatio-temporal model can be exploited to assess the relevance of daily mobility routines. This novel cognitive and on-line mobility modeling contributes toward the distributed intelligence of IoT connected devices without strongly compromising energy.
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Christie, John, Matthew D. Hilchey, and Raymond M. Klein. "Spatio-temporal properties of oculomotor activation by multiple, simultaneous peripheral stimuli." Vision Research 188 (November 2021): 251–61. http://dx.doi.org/10.1016/j.visres.2021.07.010.

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Xiao, Chao. "Spatio-temporal properties of pulse propagation in a graphene quantum system." Laser Physics 32, no. 2 (December 31, 2021): 025202. http://dx.doi.org/10.1088/1555-6611/ac4470.

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Abstract In this paper we have theoretically studied the spatial-temporal evolution of electromagnetic light propagation through a four-level graphene quantum system by using density matrix method and perturbation theory. The four-level graphene quantum medium interacted by an elliptical polarized coupling and a weak probe lights, respectively. We present the analytical solution for solving the Maxwell–Bloch equations for graphene and electromagnetic field in space and time domains. Then, we have analyzed the dynamic control of pulse propagation and optical dual switching in such a laser-driven quantum system. Our theoretical findings show that by adjusting the optical parameters such as elliptical angle i.e. phase difference between right-and-left circularly polarized, one can easily control the absorption spectrum and pulse propagation of the probe light in graphene medium. Our results may have potential applications in designing the new quantum devices for usage in quantum information processing.
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Chia-Chin Chong and D. I. Laurenson. "Spatio-temporal correlation properties for the 5.2 GHz indoor propagation environments." IEEE Antennas and Wireless Propagation Letters 2 (2003): 114–17. http://dx.doi.org/10.1109/lawp.2003.815284.

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37

Hooge, Ignace Th C., and Maarten A. Frens. "Inhibition of saccade return (ISR): spatio-temporal properties of saccade programming." Vision Research 40, no. 24 (October 2000): 3415–26. http://dx.doi.org/10.1016/s0042-6989(00)00184-x.

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38

Gelli, G., D. Mattera, and L. Paura. "Blind wideband spatio-temporal filtering based on higher-order cyclostationarity properties." IEEE Transactions on Signal Processing 53, no. 4 (April 2005): 1282–90. http://dx.doi.org/10.1109/tsp.2005.843733.

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39

Huang, J. Y., and I. S. Ko. "Spatio-temporal measurement of beam properties in the PLS diagnostic beamline." Journal of Synchrotron Radiation 5, no. 3 (May 1, 1998): 642–44. http://dx.doi.org/10.1107/s090904959702013x.

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A diagnostic beamline is being constructed in the PLS storage ring for measurement of electron- and photon-beam properties. It consists of two 1:1 imaging systems: a visible-light imaging system and a soft X-ray imaging system. In the visible-light imaging system, the transverse beam size and beam position are measured with various detectors: a CCD camera, two photodiode arrays and a photon-beam position monitor. Longitudinal bunch structure is also investigated with a fast photodiode detector and a picosecond streak camera. On the other hand, the soft X-ray imaging system is under construction to measure beam sizes with negligible diffraction-limited error. The X-ray image optics consist of a flat cooled mirror and two spherical focusing mirrors.
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Tanimura, Akihiko, Akiko Shitara, and Yosuke Tojyo. "Diversity and Spatio-Temporal Properties of Calcium Responses in Salivary Ducts." Journal of Oral Biosciences 53, no. 1 (January 2011): 48–56. http://dx.doi.org/10.1016/s1349-0079(11)80035-6.

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41

Inui, Norio, and Makoto Katori. "Statistical Properties of Trajectories of Friendly Walkers on Spatio-Temporal Plane." Journal of the Physical Society of Japan 70, no. 1 (January 15, 2001): 78–85. http://dx.doi.org/10.1143/jpsj.70.78.

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42

Watanabe, Kazuhiko, Jun-ichi Wakita, Hiroto Itoh, Hirotoshi Shimada, Sayuri Kurosu, Takemasa Ikeda, Yoshihiro Yamazaki, Tohey Matsuyama, and Mitsugu Matsushita. "Dynamical Properties of Transient Spatio-Temporal Patterns in Bacterial Colony ofProteusmirabilis." Journal of the Physical Society of Japan 71, no. 2 (February 15, 2002): 650–56. http://dx.doi.org/10.1143/jpsj.71.650.

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43

Timofeev, Igor, Sarah F. Schoch, Monique K. LeBourgeois, Reto Huber, Brady A. Riedner, and Salome Kurth. "Spatio-temporal properties of sleep slow waves and implications for development." Current Opinion in Physiology 15 (June 2020): 172–82. http://dx.doi.org/10.1016/j.cophys.2020.01.007.

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44

Solovyova, O., L. B. Katsnelson, P. Konovalov, O. Lookin, A. S. Moskvin, Yu L. Protsenko, N. Vikulova, P. Kohl, and V. S. Markhasin. "Activation sequence as a key factor in spatio-temporal optimization of myocardial function." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 364, no. 1843 (April 11, 2006): 1367–83. http://dx.doi.org/10.1098/rsta.2006.1777.

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Using one-dimensional models of myocardial tissue, implemented as chains of virtual ventricular muscle segments that are kinematically connected in series, we studied the role of the excitation sequence in spatio-temporal organization of cardiac function. Each model element was represented by a well-verified mathematical model of cardiac electro-mechanical activity. We found that homogeneous chains, consisting of identical elements, respond to non-simultaneous stimulation by generation of complex spatio-temporal heterogeneities in element deformation. These are accompanied by the establishment of marked gradients in local electro-mechanical properties of the elements (heterogeneity in action potential duration, Ca 2+ transient characteristics and sarcoplasmic reticulum Ca 2+ loading). In heterogeneous chains, composed of elements simulating fast and slow contracting cardiomyocytes from different transmural layers, we found that only activation sequences where stimulation of the slower elements preceded that of faster ones gave rise to optimization of the system's electro-mechanical function, which was confirmed experimentally. Based on the results obtained, we hypothesize that the sequence of activation of cardiomyocytes in different ventricular layers is one of the key factors of spatio-temporal organization of myocardium. Moreover, activation sequence and regional differences in intrinsic electro-mechanical properties of cardiac muscle must be matched in order to optimize myocardial function.
45

Kargapolova, N. "Stochastic simulation of the spatio-temporal field of the average daily heat index in Southern Russia." Climate Research 82 (December 17, 2020): 149–60. http://dx.doi.org/10.3354/cr01623.

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Numerical models of the heat index time series and spatio-temporal fields can be used for a variety of purposes, from the study of the dynamics of heat waves to projections of the influence of future climate on humans. To conduct these studies one must have efficient numerical models that successfully reproduce key features of the real weather processes. In this study, 2 numerical stochastic models of the spatio-temporal non-Gaussian field of the average daily heat index (ADHI) are considered. The field is simulated on an irregular grid determined by the location of weather stations. The first model is based on the method of the inverse distribution function. The second model is constructed using the normalization method. Real data collected at weather stations located in southern Russia are used to both determine the input parameters and to verify the proposed models. It is shown that the first model reproduces the properties of the real field of the ADHI more precisely compared to the second one, but the numerical implementation of the first model is significantly more time consuming. In the future, it is intended to transform the models presented to a numerical model of the conditional spatio-temporal field of the ADHI defined on a dense spatio-temporal grid and to use the model constructed for the stochastic forecasting of the heat index.
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MORESCO, P., and J. J. HEALEY. "Spatio–temporal instability in mixed convection boundary layers." Journal of Fluid Mechanics 402 (January 10, 2000): 89–107. http://dx.doi.org/10.1017/s002211209900676x.

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In this work we analyse the stability properties of the flow over an isothermal, semi-infinite vertical plate, placed at zero incidence to an otherwise uniform stream at a different temperature. Near the leading edge the boundary layer resembles Blasius flow, but further downstream it approaches that of pure buoyancy-driven flow. A coordinate transformation that describes in a smooth way the evolution between these two limiting similarity states, where the viscous and buoyancy forces are respectively dominant, is used to calculate the basic flow. The stability of this flow has been investigated by making the parallel flow approximation, and using an accurate spectral method on the resulting stability equations. We show how the stability modes discussed by other authors can be followed continuously between the forced and free convection limits; in addition, new instability modes not previously reported in the literature have been found. A spatio–temporal stability analysis of these modes has been carried out to distinguish between absolute and convective instabilities. It seems that absolute instability can only occur when buoyancy forces are opposed to the free stream and when there is a region of reverse flow. Model profiles have been used in this latter case beyond the point of boundary layer separation to estimate the range of reverse flows that support absolute instability. Analysis of the Rayleigh equations for this problem suggests that the absolute instability has an inviscid origin.
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Wei, Xiujie, Yinfeng Li, Ranran Shang, Chang Ruan, and Jingzhang Xing. "Airport Cluster Delay Prediction Based on TS-BiLSTM-Attention." Aerospace 10, no. 7 (June 22, 2023): 580. http://dx.doi.org/10.3390/aerospace10070580.

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To conduct an accurate and reliable airport delay prediction will provide an important basis for the macro control of an airspace delay situation and the dynamic allocation of airspace system capacity balance. Accordingly, a method of delay prediction for target airports based on the spatio-temporal delay variables of adjacent airports is proposed in this paper. First, by combining the complex network theory, we first extract the topology of the airport network and create airport clusters with comparable network properties. Second, we develop the TS-BiLSTM-Attention mode to predict the delay per hour for airports in the cluster. As the spatio-temporal feature variables, the arrival delay of airport cluster-associated airports and the delay time series of landing airports are utilized to reach the conclusion. The experimental results indicate that the delay prediction predicated on clusters is superior to that based on data from a single airport. This demonstrates that the delay propagation law derived from cluster data based on spatio-temporal feature extraction can generalize the delay propagation characteristics of airports within clusters.
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Geoga, Christopher J., Charlotte L. Haley, Andrew R. Siegel, and Mihai Anitescu. "Frequency–wavenumber spectral analysis of spatio-temporal flows." Journal of Fluid Mechanics 848 (June 8, 2018): 545–59. http://dx.doi.org/10.1017/jfm.2018.366.

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We propose a fully spatio-temporal approach for identifying spatially varying modes of oscillation in fluid dynamics simulation output by means of multitaper frequency–wavenumber spectral analysis. One-dimensional spectrum estimation has proven to be a valuable tool in the analysis of turbulence data applied spatially to determine the rate of energy transport between spatial scales, or temporally to determine frequencies of oscillatory flows. It also allows for the quantitative comparison of flow characteristics between two scenarios using a standard basis. It has the limitation, however, that it neglects coupling between spatial and temporal structures. Two-dimensional frequency–wavenumber spectral analysis allows one to decompose waveforms into standing or travelling variety. The extended higher-dimensional multitaper method proposed here is shown to have improved statistical properties over conventional non-parametric spectral estimators, and is accompanied by confidence intervals which estimate their uncertainty. Multitaper frequency–wavenumber analysis is applied to a canonical benchmark problem, namely, a direct numerical simulation of von Kármán vortex shedding off a square wall-mounted cylinder with two inflow scenarios with matching momentum-thickness Reynolds numbers $Re_{\unicode[STIX]{x1D703}}\approx 1000$ at the obstacle. Frequency–wavenumber analysis of a two-dimensional section of these data reveals that although both the laminar and turbulent inflow scenarios show a turbulent $-5/3$ cascade in wavenumber ($\unicode[STIX]{x1D708}$) and frequency ($f$), the flow characteristics differ in that there is a significantly more prominent discrete harmonic oscillation near $(f,\unicode[STIX]{x1D708})=(0.2,0.21)$ in wavenumber and frequency in the laminar inflow scenario than the turbulent scenario. This frequency–wavenumber pair corresponds to a travelling wave with velocity near one near the centre path of the vortex street.
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Winklmayr, Claudia, Albert B. Kao, Joseph B. Bak-Coleman, and Pawel Romanczuk. "Collective decision strategies in the presence of spatio-temporal correlations." Collective Intelligence 2, no. 1 (February 7, 2023): 263391372211486. http://dx.doi.org/10.1177/26339137221148675.

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Background: Models of collective decision-making typically assume that individuals sample information independently and decide instantaneously. In most natural and sociological settings, however, decisions occur over some timescale in which group members gather information—often from multiple sources. Information sources may persist for varying lengths of time or be viewed concurrently and identically by multiple group members. These tendencies introduce spatio-temporal correlations in gathered information with poorly understood consequences. Research Design: Here, we develop a collective decision-making model in which individuals’ access and switch between two conflicting cues that differ in their spatio-temporal properties. Results: Our model reveals that spatially and temporally correlated cues can profoundly affect collective decisions. Specifically, we observe that spatially correlated cues are dominant when individuals rarely switch between sources of information. Temporally correlated cues, on the other hand, have the strongest impact when individuals frequently switch between information sources. We also discuss how much the usage of independent information must be increased to counter the impact of correlation. Conclusions: The present model represents a first step toward more accurately capturing the complex mechanisms underlying collective decision-making in natural systems and reveals multiple ways in which the properties of environmental cues can impact collective behavior.
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Yang, Xianglin, Yun Lin, Ruofan Liu, Zhenfeng He, Chao Wang, Jin Song Dong, and Hong Mei. "DeepVisualInsight: Time-Travelling Visualization for Spatio-Temporal Causality of Deep Classification Training." Proceedings of the AAAI Conference on Artificial Intelligence 36, no. 5 (June 28, 2022): 5359–66. http://dx.doi.org/10.1609/aaai.v36i5.20473.

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Understanding how the predictions of deep learning models are formed during the training process is crucial to improve model performance and fix model defects, especially when we need to investigate nontrivial training strategies such as active learning, and track the root cause of unexpected training results such as performance degeneration. In this work, we propose a time-travelling visual solution DeepVisualInsight (DVI), aiming to manifest the spatio-temporal causality while training a deep learning image classifier. The spatio-temporal causality demonstrates how the gradient-descent algorithm and various training data sampling techniques can influence and reshape the layout of learnt input representation and the classification boundaries in consecutive epochs. Such causality allows us to observe and analyze the whole learning process in the visible low dimensional space. Technically, we propose four spatial and temporal properties and design our visualization solution to satisfy them. These properties preserve the most important information when projecting and inverse-projecting input samples between the visible low-dimensional and the invisible high-dimensional space, for causal analyses. Our extensive experiments show that, comparing to baseline approaches, we achieve the best visualization performance regarding the spatial/temporal properties and visualization efficiency. Moreover, our case study shows that our visual solution can well reflect the characteristics of various training scenarios, showing good potential of DVI as a debugging tool for analyzing deep learning training processes.

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