Spatiotemporal Coupling Research Articles

Temporal and Spatial Distribution of Food Security Production and Total Water Resources in Western Jilin: Based on Center of the Gravity Model

In recent years, the main grain-producing areas in the west of Jilin have gradually concentrated in the perennial irrigation areas and supplementary irrigation areas in the north, and the stress degree of grain irrigation water resources is gradually increasing. Therefore, this paper selects the arid and semiarid area in the west of Jilin Province as the research area and compares and analyzes the modeling process and simulation accuracy of the temporal and spatial distribution of food security production and total water resources. Based on the center of gravity model, this paper studies the temporal and spatial distribution of food security production and total water resources in Western Jilin. It can be seen that after 2018, rice and wheat show a fluctuating upward trend, and their values rise from 0.612 to 0.786 and 0.356 to 0.612, respectively; the rise of corn is small, showing an inverted “U” trend, which first increases from 0.693 in 2018 to 0.701 in 2019 and then decreases to 0.671 in 2021; By comparing the precipitation statistics in different years, the inverted “U” trend of corn irrigation water efficiency may be related to the sudden increase of precipitation. The center of gravity model is used to analyze the evolution trend of the center of gravity of grain production and water resources in Western Jilin from the national and regional levels, and the spatiotemporal coupling degree of the center of gravity of grain production and water resources is explored through the two-factor center of gravity coupling situation model.

When the timing is right: The link between temporal coupling in dyadic interactions and emotion recognition

Affective states can be understood as dynamic interpersonal processes developing over time and space. When we observe emotional interactions performed by other individuals, our visual system anticipates how the action will unfold. Thus, it has been proposed that the process of emotion perception is not only a simulative but also a predictive process - a phenomenon described as interpersonal predictive coding. The present study investigated whether the recognition of emotions from dyadic interactions depends on a fixed spatiotemporal coupling of the agents. We used an emotion recognition task to manipulate the actions of two interacting point-light figures by implementing different temporal offsets that delayed the onset of one of the agent's actions (+0 ms, +500 ms, +1000 ms or + 2000 ms). Participants had to determine both the subjective valence and the emotion category (happiness, anger, sadness, affection) of the interaction. Results showed that temporal decoupling had a critical effect on both emotion recognition and the subjective impression of valence intensity: Both measures decreased with increasing temporal offset. However, these effects were dependent on which emotion was displayed. Whereas affection and anger sequences were impacted by the temporal manipulation, happiness and sadness were not. To further investigate these effects, we conducted post-hoc exploratory analyses of interpersonal movement parameters. Our findings complement and extend previous evidence by showing that the complex, noncoincidental coordination of actions within dyadic interactions results in a meaningful movement pattern and might serve as a fundamental factor in both detecting and understanding complex actions during human interaction.

In-situ measurement and compensation of complex spatio-temporal couplings in ultra-intense lasers

Diffraction wavefront errors of large-scale Treacy compressors may induce complex spatio-temporal couplings (CSTCs) in chirped pulse amplification and degrade the quality of the pulsed beam in both near and far fields. This problem is particularly pronounced in petawatt laser facilities that require tiled compressor gratings. Here, to the best of our knowledge, we present the first in-situ measurement method named pseudo lateral shearing interferometry (PLSI) for the CSTC wavefront error and manufacture a continuous phase plate (CPP) according to the measurement to reduce the distortion. A Shark-Hartmann wavefront sensor is used to characterize wavefronts of the entire system at two different wavelengths, and the CSTC wavefront error can be reconstructed similarly to lateral shearing interferometry (LSI). Our approach strongly reduces systematic errors and the impact of other optics. The root-mean-square (RMS) value of the resulting error is 40 nm in a single measurement, and the day-to-day repeatability is 55 nm. The employed CPP reduces the peak-to-valley (PV) value of the CSTC wavefront error from 675 to 312 nm, and the focused peak intensity is improved by 51%.

Spatio-temporal ultrafast pulse shaping at the femtosecond-nanometer scale.

Optical pulse shaping is a fundamental tool for coherent control of the light-matter interaction. While such control enables the measurement of ultrafast temporal dynamics, simultaneous spatiotemporal control is required for studying non-local ultrafast charge dynamics at the nanoscale. However, obtaining accurate spatial control at a sub-wavelength resolution with conventional optical elements poses significant difficulty. Here, we use the spatiotemporal coupling naturally arising in a spatial light modulator based pulse shaping apparatus to achieve accurate control with femto-nano spatiotemporal resolution. We experimentally demonstrate spatial steering at the sub-micron scale of second harmonic generation from nanostructures. In addition, we apply an absolute-value spectral phase to achieve controlled double pulses for nanoscale excitation. We introduce a novel, to the best of our knowledge, scheme for accurate tunable spatiotemporal pump-probe experiments. This method offers rich insight into materials with ultrafast transport phenomena at the femtosecond-nanometer regimes.

Spatiotemporal Coupling Effect of Regional Economic Development and De-Carbonisation of Energy Use in China: Empirical Analysis Based on Panel and Spatial Durbin Models

The synergistic development of economic construction and low-carbon transformation of energy systems must be promoted for building a green, low-carbon, and cyclic economic system and achieving the “double carbon” goal in China. Based on the panel data of 30 provincial-level administrative regions in China from 2015 to 2019, the global entropy method, coupling coordination degree model, and spatial statistical analysis methods are applied to analyse the factors affecting the coupling effect. The coordination degree increased in the study period, with Beijing, Shanghai, Tianjin, Jiangsu, and Zhejiang being the regions with the highest values. The spatial distribution of the coupling coordination degree is strongly positively correlated with the eastern provincial-level administrative regions located in the high–high concentration area of the Moran scatterplot and western provincial-level administrative regions concentrated in the low–low concentration area. The spatial association pattern is stable in the study period, with only two provinces exhibiting a transition: Shandong province made the transition to high–high agglomeration areas, and Liaoning province made the transition to low–low agglomeration areas. The level of regional economy, urbanization process, energy consumption structure, and level of investment in science and innovation enhance the coupling coordination degree, whereas the industrial structure deteriorates this degree.

Long-Time-Series Evolution and Ecological Effects of Coastline Length in Coastal Zone: A Case Study of the Circum-Bohai Coastal Zone, China

Under the joint influence of climate change and human production and living activities on land and sea, the morphology and use function of the coastline have undergone notable changes, triggering more significant environmental and ecological effects. In this paper, we quantified the evolution characteristics of the coastline over the past 30 years and measured the possible environmental pollution and ecological degradation by means of spatiotemporal coupling analysis in terms of spatial form and land-use function. The Chinese Bohai Rim region was taken as an example, and the Google Earth Engine was applied to achieve a long time series of interannually continuous land use function classification of the coastal zone. The study shows that: (1) from 1987–2020, the coastline of Bohai Rim showed an overall trend of seaward expansion, with the length of the coastline increasing by 15.6%, most significantly from 2003 to 2011; (2) the proportion of construction function coastline increased from 14.66% to 42.8%, while the proportion of cropland coastline decreased from 52.01% to 18.16% during 2000–2020, with the natural ecological coastline decreasing in the early stage and recovering in the later stage, thus becoming more stable overall; (3) 82.73% of coastal districts and counties showed a linear correlation between changes in coastline function and water quality level, and 77.8% showed a consistent degree of change of coastline function and loss of ecological land, indicating that changes in the coastline have triggered significant problems in terms of environmental pollution and ecological degradation. With the exception of localized areas such as the Yellow River Delta, where coastline change is somewhat more significantly influenced by environmental climate change, most other coastline changes are primarily due to human land-based development; therefore, coastal policy constraints bring obvious mitigation.

Interactive coercive relationship and spatio-temporal coupling coordination degree between tourism urbanization and eco-environment: A case study in Western China

The deteriorating eco-environment is the key to restrict the development of tourism urbanization in the western region. Since the eco-environmental effects caused by tourism urbanization have complex interactions, how to coordinate the relationship between the two has become one of the most severe challenges for the sustainable development of western China and even the whole of China. Previous quantitative studies on the coupling coordination between tourism urbanization and eco-environment are limited because they ignore the interactive coercion relationship between complex systems and the spatial dynamic relationship of coupling coordination. Given this research gap, this research has constructed a new comprehensive evaluation index system of tourism urbanization and eco-environment. The interactive coercion model, the coupling coordination degree model and the gravity model are used to evaluate the interaction relationship, coupling coordination type and spatial connection strength between tourism urbanization and eco-environment in western China from 2005 to 2019. The main conclusions are as follows: (1) The level of tourism urbanization shows a rapid upward trend, and the eco-environment quality shows a fluctuating and low-speed upward trend; (2) The double exponential curve between tourism urbanization and eco-environment is an inverted U-shaped curve, and the empirical analysis confirms the Kuznets hypothesis; (3) The degree of coupling coordination has experienced a development process from “seriously unbalanced” to “superior balanced”, and the interaction type has evolved into superior balanced-eco-environment lag; (4) The spatial connection of coupling coordination shows the characteristics of complication and gradient, and the interaction between provinces produces a pattern of adjacent associations. The results of this study are expected to implement an appropriate tourism urbanization development model in western China and provide decision support for the green and sustainable development of tourism urbanization and eco-environment in western China.

Single-shot compressed optical field topography

Femtosecond lasers are powerful in studying matter’s ultrafast dynamics within femtosecond to attosecond time scales. Drawing a three-dimensional (3D) topological map of the optical field of a femtosecond laser pulse including its spatiotemporal amplitude and phase distributions, allows one to predict and understand the underlying physics of light interaction with matter, whose spatially resolved transient dielectric function experiences ultrafast evolution. However, such a task is technically challenging for two reasons: first, one has to capture in single-shot and squeeze the 3D information of an optical field profile into a two-dimensional (2D) detector; second, typical detectors are only sensitive to intensity or amplitude information rather than phase. Here we have demonstrated compressed optical field topography (COFT) drawing a 3D map for an ultrafast optical field in single-shot, by combining the coded aperture snapshot spectral imaging (CASSI) technique with a global 3D phase retrieval procedure. COFT can, in single-shot, fully characterize the spatiotemporal coupling of a femtosecond laser pulse, and live stream the light-speed propagation of an air plasma ionization front, unveiling its potential applications in ultrafast sciences.

STTG-net: a Spatio-temporal network for human motion prediction based on transformer and graph convolution network

In recent years, human motion prediction has become an active research topic in computer vision. However, owing to the complexity and stochastic nature of human motion, it remains a challenging problem. In previous works, human motion prediction has always been treated as a typical inter-sequence problem, and most works have aimed to capture the temporal dependence between successive frames. However, although these approaches focused on the effects of the temporal dimension, they rarely considered the correlation between different joints in space. Thus, the spatio-temporal coupling of human joints is considered, to propose a novel spatio-temporal network based on a transformer and a gragh convolutional network (GCN) (STTG-Net). The temporal transformer is used to capture the global temporal dependencies, and the spatial GCN module is used to establish local spatial correlations between the joints for each frame. To overcome the problems of error accumulation and discontinuity in the motion prediction, a revision method based on fusion strategy is also proposed, in which the current prediction frame is fused with the previous frame. The experimental results show that the proposed prediction method has less prediction error and the prediction motion is smoother than previous prediction methods. The effectiveness of the proposed method is also demonstrated comparing it with the state-of-the-art method on the Human3.6 M dataset.

Study of the impact of wavefront aberrations on the characterization of ultrashort laser pulses with GRENOUILLE.

In recent years, GRENOUILLE has emerged as a relatively simple technique to fully characterize the electric field of an ultrashort laser pulse in a single shot. It does so by spatially mapping the delays on the transverse spatial coordinate and by mapping the frequencies on the angular coordinate of the orthogonal direction. Because of this spatial mapping, an aberrated wavefront could distort and affect the measurement of the pulse. It is shown here experimentally how these aberrations can affect the measurement using a deformable mirror to induce various aberrations in the wavefront. This can result in distortions of the spectral or temporal profile of the retrieved pulse, and a decrease of the intensity of the second-harmonic signal generated by the nonlinear crystal. Additionally, the signatures of some of the distortions of the trace resemble those previously identified as being caused by pulse-front tilt or spatial chirp and could be interpreted as such while being in fact caused by aberrations. This can complicate the identification of the real source of the distortions, since a purely spatial effect can cause distortions similar to those created by dispersion-based phenomena or other types of spatiotemporal couplings.

Research on the Coordination of Time and Space Coupling Between New Urbanization and Economic Development Based on Cloud Computing

Through in-depth analysis of the definition and connotation of new urbanization quality, a new urbanization indicator system with typical representativeness and quantification is established, and a spatio-temporal coupling coordination model is constructed based on this indicator system, and model input is obtained through urban statistical yearbooks and relevant government year reports Data, complete the temporal-spatial coupling coordination analysis of new urbanization and economic development. Taking a province as an example, it has been experimentally verified that the quality of new urbanization in the province has developed rapidly from 2010 to 2014, and the quality of new urbanization has stagnated from 2014 to 2015. In 2018, the quality of new urbanization in the province has rapidly increased its comprehensive value.

Spatio-temporal coupling controlled laser for electron acceleration

Limited by the difficulty in acceleration synchronization, it has been a long-term challenge for on-chip dielectric laser-based accelerators to bridge the gap between non-relativistic and relativistic regimes. Here, we propose a laser-based accelerators based on a spatio-temporal coupling controlled laser pulse, which enables the acceleration of a non-relativistic electron to a sub-MeV level in a single acceleration structure (chirped spatial grating). It provides high precision temporal and spatial tuning of the driving laser via dispersion manipulation, leading to a synchronous acceleration of the velocity increasing electrons over a large energy range. Additionally, the spatio-temporal coupling scheme is a general method and can be extended to driving fields of other wavelengths such as terahertz pulses. Our results bring possibilities to MeV-scale portable electron sources and table-top acceleration experiments.

Efficient Spatiotemporal Transformer for Robotic Reinforcement Learning

Intense spatiotemporal coupling states frequently appear in robotic tasks, and this coupling enriches the information encapsulated in each state. Taking advantage of historical observations can provide more information about the robot, especially for partially observable Markov decision processes. How to deal with this coupling remains a challenging issue in robotic reinforcement learning (RL), and we allege that the imbalanced processing capability of spatiotemporal details is one of the bottlenecks of the vanilla transformer model in learning robotic policies. To address this problem, we novelly propose an efficient spatiotemporal transformer structure. To our knowledge, this work is the first to improve the transformer with spatiotemporal information in RL. In each attention block, we sequentially execute attention computation twice: the first to process the temporal sequence of the input and the latter to manage the spatial state. This input reconstruction enables sufficient information extraction to promote data efficiency. We also add correlation encoding into the query and key computation of multi-head attention, providing the operability of associating states between and within time steps. We evaluate the proposed approach on several robot tasks, and it outperforms state-of-the-art transformer-based online RL.

Spatio-temporal error coupling and competition in meso-flux construction of discrete unified gas-kinetic scheme

This research systemically studies the numerical characteristics of the discrete unified gas-kinetic scheme (DUGKS) in terms of tracking interface motions driven by prespecified velocity fields. Multiple reconstruction methods have been utilized for the meso-flux construction of DUGKS and the performance of each method is evaluated accordingly. The spatio-temporal error coupling mechanism exhibited in the meso-flux evaluation is identified and analyzed theoretically for the first time. The spatio-temporal error competition mechanism (STECM) appeared during the construction of upwind meso-flux is specifically illustrated and discussed. On the basis of the newly discovered mechanism, we propose a high-resolution DUGKS by employing the fourth-order reconstruction scheme and the one-stage marching technique. Four benchmark tests have been conducted and numerical results have demonstrated the superiority of this high-resolution DUGKS over the lattice Boltzmann method (LBM) in capturing dynamic interfaces. Comparative results have also revealed that the STECM profoundly impacts the overall resolution of DUGKS implemented with different cell-based reconstruction methods. The STECM provides a theoretical understanding of the spatio-temporal characteristics of numerical errors of DUGKS and could serve as helpful guidance for the design of high-resolution DUGKS in future research.

Spatiotemporal Coupling of DNA Supercoiling and Genomic Sequence Organization—A Timing Chain for the Bacterial Growth Cycle?

In this article we describe the bacterial growth cycle as a closed, self-reproducing, or autopoietic circuit, reestablishing the physiological state of stationary cells initially inoculated in the growth medium. In batch culture, this process of self-reproduction is associated with the gradual decline in available metabolic energy and corresponding change in the physiological state of the population as a function of “travelled distance” along the autopoietic path. We argue that this directional alteration of cell physiology is both reflected in and supported by sequential gene expression along the chromosomal OriC-Ter axis. We propose that during the E. coli growth cycle, the spatiotemporal order of gene expression is established by coupling the temporal gradient of supercoiling energy to the spatial gradient of DNA thermodynamic stability along the chromosomal OriC-Ter axis.

Spatiotemporal Evolution and Coupling Pattern Analysis of Urbanization and Ecological Environmental Quality of the Chinese Loess Plateau

Understanding the interactive coupling mechanism between urbanization and eco-environmental quality is crucial to achieve the goal of urban sustainable development. The Chinese Loess Plateau (CLP) was taken as the research object, and the city nighttime light index (CNLI) and remote sensing ecological index with local adaptability (LARSEI) were constructed based on the data from the Defense Meteorological Satellite Program’s Operational Linescan System (DMSP/OLS), National Polar-orbiting Partnership Visible Infrared Imaging Radiometer Suite (NPP/VIIRS), and Moderate Resolution Imaging Spectroradiometer (MODIS). Then, trend analysis, standard deviation ellipse (SDE), coupling degree (C), and coupling coordination degree (CCD) models were used to determine the spatiotemporal variation of urbanization and eco-environmental quality and its coupling relationship. The results show that: (1) the urbanization level of the CLP showed a trend of continuous improvement from 2000 to 2019. A significant increasing trend was found from the CNLI (slopeCNLI = 0.0030 yr−1, p < 0.01), and its value rose from 0.07 in 2000 to 0.14 in 2019. In terms of spatial distribution, a multi-core distribution pattern with provincial capital cities as the core was presented in the CLP. The cities expanded at different degrees and presented a gradual concentrated expansion towards the southeast on the whole. (2) The eco-environmental quality in the CLP greatly increased during 2000 to 2019. An area with an increasing trend in the remote sensing ecological index with local adaptability (LARSEI) accounted for 58.82% and was mainly concentrated in the west and central part of the CLP. (3) The C and CCD between urbanization and eco-environmental quality in the CLP presented a trend of significant increase during 2000 to 2019 (slopeC = 0.0051 yr−1, p < 0.01; slopeCCD = 0.0040 yr−1, p < 0.01). The cities with a higher coupling degree were mainly located in the southeastern and northern parts of the CLP, while those with a higher coordination degree were scattered in the marginal parts of the CLP. The research results can provide suggestions for decision-making to achieve high-quality coordinated development of the cities in the CLP.

Conflict or Coordination? Analysis of Spatio-Temporal Coupling Relationship between Urbanization and Eco-Efficiency: A Case Study of Urban Agglomerations in the Yellow River Basin, China

The coordination and coupling of new urbanization and the ecological environment is of great significance for the high-quality development of the Yellow River basin, China. In this paper, the urbanization efficiency and ecological efficiency of seven urban agglomerations in the Yellow River basin, China, from 2006 to 2019 are calculated at the city level. Spatial correlation analysis between urbanization efficiency and ecological efficiency is carried out by applying the spatial association model. Then, the spatio-temporal coupling relationship is estimated based on the relative development and spatial coupling models. The results show that urbanization efficiency has been rising, from 0.83 in 2006 to 0.91 in 2019. Ecological efficiency first stabilized and then rose from 1.03 in 2006 to 1.23 in 2019. Spatially, cities with high urbanization efficiency development are increasing from west to east. Cities with high eco-efficient developments are increasing from northwest to southeast. The coupling relationship between the two is an N-type relationship, with the trend of first rising, then falling, and then rising. Spatially, the coupling degree of the upper and lower reaches of the Yellow River basin, China, is higher than that of the middle reaches of the Yellow River basin, China. Finally, this paper puts forward policy recommendations on the coordinated and coupling development of urban agglomerations in the Yellow River basin, China, from the perspective of the future differentiated development of different urban agglomerations.

An Online SOC-SOTD Joint Estimation Algorithm for Pouch Li-Ion Batteries Based on Spatio-Temporal Coupling Correction Method

An SOC (state of charge)-SOTD (state of temperature distribution) joint estimation algorithm is established for a pouch lithium-ion battery. This method integrates the first-order RC model, distributed heat generation model, thermal resistance network model, and spatio-temporal coupling correction based on spatial restoration algorithm and dual Kalman filter (DKF). Unlike the traditional 1-D SOT estimation model, the proposed algorithm can accurately estimate the temperature distribution in the battery online by restoring the battery surface temperature distribution, calculating the battery internal temperature distribution, and jointly correcting the SOC and average internal temperature. Then, the proposed method is used for the SOC-SOTD estimation of a 25-Ah pouch battery at the ambient temperatures of 10, 20, and 30 °C under the worldwide light-duty test cycle and new european driving cycle driving cycles, and the estimated values are verified by experiment and 3-D simulation. According to the verification results, calculation errors of SOC are no more than 2.12%, and the maximum average calculation errors are 0.16 °C for the surface temperature and 0.24 °C for the internal temperature. However, the DKF is needed for the SOC-SOTD joint estimation because the single KF can only correct SOC or average internal temperature but cannot handle the inconsistency in temperature distribution.

An innovative digitization evaluation scheme for Spatio-temporal coordination relationship between multiple knowledge driven rural economic development and agricultural ecological environment—Coupling coordination model analysis based on Guangxi

The agricultural ecological environment is the premise and foundation of rural economic development and the rural economy is an important manifestation of the vitality of the agricultural ecological environment. Taking 14 prefecture-level cities in Guangxi as the research object, this paper collects and sorts out the relevant data indicators of rural economy and agricultural ecological environment of them from 2007 to 2019, constructs the evaluation index system, calculates the development index by using the comprehensive index function, and finally uses an innovative digitization evaluation scheme to further evaluate the spatiotemporal coupling and coordination relationship between the rural economy and agricultural ecological environment. The following conclusions are ultimately drawn. First, the comprehensive level index of the rural economy shows linear growth with unbalanced regional development (values from 0.306 to 0.598). Second, the comprehensive index of the agricultural ecological environment shows fluctuating growth with obvious regional differences (values from 0.264 to 0.483). Third, the development of rural economy and agricultural ecological environment is not synchronized, and there is mutual influence. Fourth, the coordination level of the rural economy and agricultural ecological environment is low (coupling values from 0.369 to 0.513). Then, policy inspirations are proposed. First, the investment in agricultural science and technology innovation should be increased and the modern agricultural technology system. Second, agricultural industrial structure should be optimized and the agricultural industrial chain. Third, the construction of agricultural infrastructure should be improved, and the high-quality development of agriculture should be promoted. Fourth, the education of ecological civilization should be strengthened, and awareness of ecological and environmental protection should be established. Fifth, they should strengthen education and training and cultivate new professional farmers. Sixth, they should improve the utilization rate of land and enhance the arable land production capacity.

Source coherence-induced control of spatiotemporal coherency vortices.

A novel method to achieve the coherence control of spatiotemporal coherency vortices of spatially and temporally partially coherent pulsed vortex (STPCPV) beams is proposed. The influence of spatial and temporal coherence of the source on the phase distributions and the positions of spatiotemporal coherency vortices of the STPCPV beams propagating through fused silica is investigated in detail, for the first time to our knowledge. It is found that the coherence width and the coherence time of the incident beam can be regarded as a perfect tool for controlling the phase distribution and position of a spatiotemporal coherency vortex. The results obtained in this paper will benefit a number of applications relating to light-matter interaction, quantum entanglement, quantum imaging, optical trapping and spatiotemporal spin-orbit angular momentum coupling.