Spatiotemporal Coupling Research Articles

From the Fifth to the Seventh National Population Census in China：The Spatio-temporal Coupling of Population Distribution and Economic Growth as well as the Regional Balanced Development

From the Fifth to the Seventh National Population Census in China：The Spatio-temporal Coupling of Population Distribution and Economic Growth as well as the Regional Balanced Development

Investigating the value of spatiotemporal resolutions and feedback loops in water-energy nexus modeling

Modeling the interactions between water and energy is crucial to managing holistically these resources. Here, we simulate water allocations and energy dispatch in the metropolitan region of Phoenix, Arizona in 2008–2017 using the WEAP and LEAP models under different spatiotemporal resolutions and coupling configurations. We find that increasing the temporal resolution from annual to monthly allows capturing seasonal demands, which improves the simulation of water allocations from supply sources to all demand nodes; the simulation of energy fluxes is instead less sensitive to the model time step. Representing the domain with higher spatial granularity enhances the ability to model the correct water portfolio of the power plants. Finally, coupling the models to capture two-way feedbacks between water and energy systems improves the simulations of electricity generation and, in turn, of water fluxes. While related to Phoenix, our findings provide useful insights to improve water-energy nexus modeling at other sites.

Propagation-invariant space-time caustics of light.

Caustics are responsible for a wide range of natural phenomena, from rainbows and mirages to sparkling seas. Here, we present caustics in space-time wavepackets, a class of pulsed beams featuring strong coupling between spatial and temporal frequencies. Space-time wavepackets have attracted much attention with their propagation-invariant intensity profiles that travel at tunable superluminal and subluminal group velocities. These intensity profiles, however, have been largely restricted to an X-shape or similar pattern. We show that space-time caustics combine the propagation invariance of space-time wavepackets with the flexible design of caustics, allowing for customizable intensity patterns in space-time wavepackets. Our method directly provides the phase distribution needed to realize user-designed caustic patterns in space-time wavepackets. We show that space-time caustics can feature in a broad range of intriguing optical phenomena, including backward traveling caustics formed from purely forward propagating waves, and nondiffracting beams that evolve with time. Our findings should open the doors to an even wider range of structured light with spatiotemporal coupling.

Finer-scale spatiotemporal coupling coordination model between socioeconomic activity and eco-environment: A case study of Beijing, China

Urbanization demands finer coordinated development of the urban human-earth relationship with high quality. Although a large number of studies have explored the long-term and large-scale coupling effect of urbanization and eco-environment, there is a lack of finer spatiotemporal method and assessment. Therefore, this paper proposes a monthly-scale pixel-based coupling coordination degree (CCD) model, aiming to explore the relationship between urban socioeconomic activity intensity (SAI) and regional eco-environment (REE) in Beijing during the period of January 2018 to May 2020 based on nighttime light data and MODIS images. The results show that the SAI in Beijing has shown a trend of increasing, and the overall REE was relatively stable during the investigated period. The CCD between SAI and REE in Beijing has been improving both spatially and quantitatively. Until May 2020, more than 50% of the human activity areas were in a state of high-level coordinated, and the mean CCD reached a basic-coordinated level. A schematic model is further built to explain the characteristics and process of coupling coordinated interactions between socioeconomic activity and eco-environment. The inner-annual micro-scale analysis and assessment provide theoretical support for fine-scale monitoring and high-quality urban development planning and policies from decision-makers.

Spatio-temporal analysis of the coupling relationship between urbanization and eco-environment in backward regions of China.

The strategy of the Silk Road Economic Belt in China has promoted the urban development of the backward regions in the west, but it might also cause serious eco-environmental concerns. Studying the coupling relationship between urbanization and the eco-environment (UEE) is essential to promote the sustainable development in backward regions. This study developed a combined method of coupling coordination degree (CCD) model, linear regression, and gray relational analysis (GRA) model to investigate the spatio-temporal coupling relationship and the influencing factors between UEE in Ningxia Hui Autonomous Region (NHAR), a typical backward region along the Silk Road Economic Belt. Results show that (1) the economic urbanization and eco-environmental pressure made the largest contribution to the system of urbanization and eco-environment, respectively. (2) The overall CCD in NHAR showed a linear upward trend from 2001 to 2018, while the CCD of each district presented significant spatial difference. The CCDs in the more developed northern regions were generally higher than those in southern mountainous regions. (3) Furthermore, population factors were the main mechanism imposing stress on the eco-environment, and the factors of eco-environmental status had higher restrictive effect on urban development in NHAR. This study could provide theoretical basis for investigating the interaction between UEE in backward regions, which might enable policymakers to formulate targeted sustainable development plans.

Exploring the coordination between physical space expansion and social space growth of China’s urban agglomerations based on hierarchical analysis

Rapid urbanization in China has led to weak internal coordination among demographic, economic, and social urbanization. Urban spatial expansion determines the urban pattern and is an important element of territorial spatial exploitation. Quantifying the coupling coordination relationship between socioeconomic growth and urban spatial expansion is needed. Using remote sensing data and socioeconomic statistics, we used the coupling coordination degree model (CCDM) and an index system to quantify the spatiotemporal trend and coupling coordination relationship between urban spatial expansion (USE) and socioeconomic growth (SEG) for seven urban agglomerations from 2000 to 2015 at urban agglomeration scale and city scale respectively. The results showed that the three world-class urban agglomerations had the largest urban sprawl, along with the highest degrees of coupling coordination at the urban agglomeration scale. However, USE was slower than SEG in national-level urban agglomerations. At city scale, the provincial capitals and municipalities such as Wuhan, Changsha, Nanchang, Zhengzhou and Changchun had higher coupling coordination degrees than the surrounding cities. The study also found that the coupling coordination degree of the Yangtze River Delta and Jing-Jin-Ji urban agglomeration was higher than all the individual cities, indicating that the integration effect should be taken into consideration in urban agglomeration studies and collaborative development among cities was more conducive to the improvement of the overall coupling coordination degree of urban agglomerations. This study quantified the process of USE and SEG at two scales, identified their complicated coupling coordination relationship among the subsystems of urbanization in different periods, and provided specific policy-relevant suggestions, which will be helpful to the regional planning of China’s urban agglomerations in future.

Adaptive optics with spatio-temporal lock-in detection for temporal focusing microscopy.

Wavefront distortion in temporal focusing microscopy (TFM) results in a distorted temporal profile of the excitation pulses owing to spatio-temporal coupling. Since the pulse duration is dramatically changed in the excitation volume, it is difficult to correct the temporal profile for a thick sample. Here, we demonstrate adaptive optics (AO) correction in a thick sample. We apply structured illumination microscopy (SIM) to an AO correction in wide-field TFM to decrease the change in the pulse duration in the signal detection volume. The AO correction with SIM was very successful in a thick sample for which AO correction with TFM failed.

Integrated spatiotemporal modeling and mixed-integer approximate dynamic programming for ASP flooding

Alkali–surfactant–polymer (ASP) flooding holds a critical position in oil development. This paper is concerned with the distributed parameter system (DPS) modeling and development scheme optimization of ASP flooding. Owing to the neglect of coupling among three-dimensional (3-D) spatial information, most of the existing data-driven modeling methods fail to provide a high-precision model for this type of strongly nonlinear and spatiotemporal coupling 3-D DPS. To overcome this shortcoming, an integrated spatiotemporal modeling method (ISM) is proposed, which reconstructs temporal–spatial relationship to avoid spatial mapping distortion based on canonical polyadic decomposition (CPD), and a spatiotemporal MSSO-LS-SVM algorithm is presented to compensate the nonlinear dynamics and decrease truncation error. Moreover, the synchronous optimization of ASP injection strategy and oil wells switching scheduling is an urgent industry requirement of intelligent oilfield decision system, which can be described a mixed-integer optimal control/dynamic programming problem. This paper first puts forward a mixed-integer approximate dynamic programming (MIADP) algorithm, dedicated for solving this class of optimal control problem with integer control subset requirements. In the MIADP, a parallel mixed-integer policy improvement framework is developed, where (i) the continuous control weight updates by the temporal difference (TD) error, (ii) the quantum evolution mechanism is designed to learn the integer control, and (iii) the two parts share information interactively and iterate to approach the optimal mixed-integer policy. At last, a case study on ASP flooding is taken, and the superior performance metrics illustrate the effectiveness of the proposed ISM method and MIADP algorithm.

Noether\u2019s theorem in statistical mechanics

Noether’s calculus of invariant variations yields exact identities from functional symmetries. The standard application to an action integral allows to identify conservation laws. Here we rather consider generating functionals, such as the free energy and the power functional, for equilibrium and driven many-body systems. Translational and rotational symmetry operations yield mechanical laws. These global identities express vanishing of total internal and total external forces and torques. We show that functional differentiation then leads to hierarchies of local sum rules that interrelate density correlators as well as static and time direct correlation functions, including memory. For anisotropic particles, orbital and spin motion become systematically coupled. The theory allows us to shed new light on the spatio-temporal coupling of correlations in complex systems. As applications we consider active Brownian particles, where the theory clarifies the role of interfacial forces in motility-induced phase separation. For active sedimentation, the center-of-mass motion is constrained by an internal Noether sum rule.

Spatiotemporal coupling measurement of industrial wastewater discharge and industrial economy in China.

With the industrial-level panel data on total output and wastewater discharge over the period of 1997 to 2018, this paper employs GIS and ESDA methods to empirically investigate the spatial relationship between industrial total output and wastewater discharge. In this paper, we empirically examine whether and how industrial wastewater discharge in a particular province may affect the wastewater discharge in its neighboring provinces. Results suggest that provinces (municipalities) with large-scale industrial sewage discharge are located along riversides and coastal areas and these discharges then gradually distribute to coastal, central, and western areas. Results also show a strong spatial autocorrelation of industrial wastewater discharge between the observed local province and its neighboring provinces which is increasing over time. In addition, there is also a significant spatial spillover effect of industrial wastewater discharge among neighboring provinces in China's eastern and central regions, indicating a structural convergence of high-pollution industries.

Hanbury Brown and Twiss effect in the spatiotemporal domain II: the effect of spatiotemporal coupling

Spatiotemporal coupling is present when the electric fields of any pulsed beams fail to separate into a product of purely spatial and temporal factors, and it affects ultimately on the propagation of the light. Here we study the effect of spatiotemporal coupling on the Hanbury Brown and Twiss (HBT) effect for the first time, with the help of our recent developed method [Opt. Express 28, 32077 (2020)10.1364/OE.405726], by assuming the Gaussian statistics of partially coherent spatiotemporal pulsed sources containing the intensity and correlation coupling effect between the spatial and temporal domain. The generalized results for the spatiotemporal coupling HBT effect are investigated and through a nontrivial two-dimensional case, we numerically illustrate the influence of the spatiotemporal coupling on the HBT effect. It observes that even a very tiny coupling effect will strongly change the HBT effect at longer distances. This work will be potentially useful for the study of the HBT effect (intensity-intensity correlations) with dynamic sources having spatiotemporal coupling in both optics and other branches of physics.

Coupling Coordination Relationship and Driving Mechanism between Urbanization and Ecosystem Service Value in Large Regions: A Case Study of Urban Agglomeration in Yellow River Basin, China.

Mastering the coupling and coordination relationship and driving mechanism of urbanization and ecosystem service value (ESV) is of great significance to ecological protection and regional sustainable development. In this paper, the coupling coordination model, geographic detector and GWR model are used to analyze the spatio-temporal coupling interaction between urbanization and ESV and the spatial differentiation characteristics of influencing factors from 1995 to 2018. The results of the study are as follows: (1) During the study period, cities in the Yellow River Basin experienced accelerated urban expansion, and the ESV of forests, water and wetlands increased, which offset the reduction in ESV due to the expansion of construction land and farmland and grassland. (2) The degree of coupling and coordination between the two gradually improved, but the overall situation showed a low-level coupling and coordination process. Mild coupling coordination gradually increased, reaching an increase of 38.10%; severe imbalance types tended to disappear, decreasing by 52.38%, and coupling subtypes developed from lagging urbanization to ESV backward types. The high-value areas of the coupling coordination degree are distributed in the high-value areas of ESV in the north of the upper reaches, and the low-value areas are distributed in the cities of Henan and Shandong with high urbanization levels in the downstream and most resource-based cities in the middle reaches. (3) In addition, the spatial intensity of the effect of each dominant factor on the degree of coupling coordination is different. Economic growth, technological development, environmental regulations and the proportion of forest land have positive and belt-shaped alienation characteristics for the coupling and coordination of the two, and infrastructure and temperature show negative driving characteristics. Therefore, the coupling and coordination relationship between ESV and urbanization should be clarified to help future urban planning. On the basis of determining the regional environmental carrying capacity and the adjustment direction of the rational planning of land resources, the impact of urban barriers formed by administrative boundaries and natural geographical conditions on the development of urban agglomerations should be broken to achieve the overall high-quality and coordinated development of the basin.

Spatio-spectral characterization of ultrashort laser pulses with a birefringent delay line

We utilize a birefringent delay line to perform spatially-resolved Fourier transform spectroscopy at multiple planes around the focus of an ultrashort laser pulse. Combining these measurements at multiple planes with phase-retrieval, i.e. the INSIGHT technique, allows for the determination of the three-dimensional laser field, in both amplitude and phase, lacking only the knowledge of a spatially-uniform spectral phase. We use the device to simultaneously measure two low-order spatio-temporal couplings resulting from a misaligned chromatic lens doublet. Besides being a new implementation of spatio-spectral characterization of ultrashort pulses, this technique allows for more accuracy and stability in spatio-spectral characterization and a push to shorter wavelengths, and may ultimately enable sparse measurements.

Formation of lake dunes in an intramontane basin: A case study from Cuona Lake, on the Qinghai-Tibetan Plateau

Although lake dunes are widespread in drylands, their formation, influenced by complex aeolian-fluvial interactions, remains unclear. This study focuses on the dunes around Cuona Lake on the Qinghai-Tibetan Plateau. By combining wind simulation and flow calculation with physical and chemical analyses of the sediments (grain size parameter statistics, elemental composition), we infer the processes of lake dune formation in this semi-arid intramontane basin. Meteorological data were used to resolve the temporal variations in wind and precipitation, and sediment transport pathways were identified from simulations based on wind and topographic data. Grain size and elemental analyses of sediment samples were used to characterize the physical and chemical composition of the Cuona Lake Basin dunes and related sediments. Our results show that dune formation in the Cuona Lake Basin occurs under the alternating control of wind and water processes. Dunes form mainly from sediment transported from the lake beach by westerly winds in the winter and spring; rivers flowing in the opposite direction (eastward) in the summer transport dune sand back to the lake beach. This process accounts for the recycling of sand in the landscape. This spatiotemporal coupling between hydrodynamic and wind transport pathways provides a continuous sediment supply for dune formation around the lake.

Altered Sleep-Related Consolidation and Neurocognitive Comorbidity in CECTS.

Our aim is to use neurophysiological sleep-related consolidation (SRC) phenomena to identify putative pathophysiological mechanisms in CECTS linked to diffuse neurocognitive deficits. We argue that there are numerous studies on the association between seizure aspects and neurocognitive functioning but not as many on interictal variables and neurocognitive deficits. We suggest two additional foci. First, the interictal presentation in CECTS and second, neuronal oscillations involved in SRC processes. Existing data on mechanisms through which interictal epileptiform spikes (IES) impact upon SRC indicate that they have the potential to: (a) perturb cross-regional coupling of neuronal oscillations, (b) mimic consolidation processes, (c) alter the precision of the spatiotemporal coupling of oscillations, and (d) variably impact upon SRC performance. Sleep spindles merit systematic study in CECTS in order to clarify: (a) the state of the slow oscillations (SOs) with which they coordinate, (b) the precision of slow oscillation-spindle coupling, and (c) whether their developmental trajectories differ from those of healthy children. We subsequently review studies on the associations between IES load during NREM sleep and SRC performance in childhood epilepsy. We then use sleep consolidation neurophysiological processes and their interplay with IES to help clarify the diffuse neurocognitive deficits that have been empirically documented in CECTS. We claim that studying SRC in CECTS will help to clarify pathophysiological mechanisms toward diverse neurocognitive deficits. Future developments could include close links between the fields of epilepsy and sleep, as well as new therapeutic neurostimulation targets. At the clinical level, children diagnosed with CECTS could benefit from close monitoring with respect to epilepsy, sleep and neurocognitive functions.

The Coupling Coordinated Development of Urban Environment Towards Sustainable Urbanization: An Empirical Study of Shandong Peninsula, China

Rapidly expanding urban areas urgently need to transform into sustainability-oriented developments. In this study, we manage to establish a spatio-temporal coupling coordinated development (CCD) model for urban environments by exploring the relationship between the quality of the built environment and environmental pressure. We empirically analyze the status of Shandong Peninsula, one of such urbanized regions, using national statistical data from 2008 to 2017. The results show that improving the CCD level of an urban environment is conducive to maintaining sustainable urbanization. Although the level of coupling and coordination in all cities of Shandong Peninsula has shown a trend of continuous improvement, nearly half of the cities are still in a transitional or imbalanced development state. This overall spatial pattern shows that the degree of coupling and coordination of coastal cities is significantly better than that of inland cities, which means there is uneven development across the region. Moreover, pressure on the environment is increasing due to excessive resource consumption and pollution with continued urban construction as the central cause. With this, countermeasures targeting the performance of different cities were discussed, including phased high-quality infrastructure, enhancing urban attractiveness, improving resource utilization efficiency, optimizing treatment and recycling technologies, etc. It is recommended that decision-makers establish an inter-city complementary system through regional planning to build an active cooperative relationship and achieve sustainable urbanization throughout the entire region.

Spatio-temporal coupling suitability of solar energy resources and distributed photovoltaic power generation projects in Beijing

Distributed photovoltaic power generation projects contribute to the coordinated and sustainable development of “energy—economy—environment”. The spatio-temporal coupling relationship between regional solar resources and distributed photovoltaic power generation projects is studied. Taking Beijing area as the research object, a variety of spatial analysis methods are proposed to explore the relationship between solar resources and distributed photovoltaic power generation projects from a new perspective of spatial geography. The spatio-temporal coupling suitability of regional solar energy resources and distributed photovoltaic power generation project development area was scientifically evaluated. The research results can provide suggestions and decision support for optimizing the timing of regional development of photovoltaic power generation, and also provide reference for planning and layout optimization of photovoltaic power generation projects in the Beijing-Tianjin-Hebei region and other regions.

Construction of a spatio-temporal coupling model for groundwater level prediction: a case study of Changwu area, Yangtze River Delta region of China

Abstract Dynamic monitoring data of groundwater level is an important basis for understanding the current situation of groundwater development and for the utilization and planning of sustainable exploitation. Dynamic monitoring data of groundwater level are typical spatio-temporal sequence data, which have the characteristics of non-linearity and strong spatio-temporal correlation. The trend of dynamic change of groundwater level is the key factor for the optimal allocation of groundwater resources. However, most of the existing groundwater level prediction models are insufficient in considering temporal and spatial factors and their spatio-temporal correlation. Therefore, construction of a space–time prediction model of groundwater level considering space–time factors and improving the prediction accuracy of groundwater level dynamic changes is of considerable theoretical and practical importance for the sustainable development of groundwater resources utilization. Based on the analysis of spatial–temporal characteristics of groundwater level of the pore confined aquifer II of Changwu area in the Yangtze River Delta region of China, the wavelet transform method was used to remove the noise in the original data, and the K-nearest neighbor (KNN) method was used to calculate the water level. The spatial–temporal dataset and the long short-term memory (LSTM) were reconstructed by screening the spatial correlation of the monitoring wells in the study area. A spatio-temporal KNN-LSTM prediction model for groundwater level considering spatio-temporal factors was also constructed. The reliability and accuracy of KNN-LSTM, LSTM, support vector regression (SVR), and autoregressive integrated moving average (ARIMA) model were evaluated by a cross-validation algorithm. Results showed that the prediction accuracy of KNN-LSTM is 20.68%, 46.54%, and 55.34% higher than that of the other single prediction models (LSTM, SVR, and ARIMA, respectively).

Data-driven two-stage stochastic optimization model for short-term hydro-thermal-wind coordination scheduling based on the dynamic extreme scenario set

A data-driven two-stage stochastic optimization model for solving short-term hydro-thermal-wind coordination scheduling problem with complicated time-coupled and space-related characteristics is proposed in this paper. The generation, emission and power fluctuation costs in the day-ahead scheduling stage and power regulation costs by hydro-thermal units, wind curtailment and load shedding costs in the real-time scheduling stage is formulated as the objective function of proposed model. Moreover, a dynamic extreme scenario generation and reduction method is introduced to deal with wind power uncertainty. The relationship between hydropower output, volume, inflow, discharge and upstream water for the multi-reservoir cascaded hydro plants is converted into a series of linear constraints, and the practical constraints of prohibited operation zones for thermal units are taken into account. As a result, the proposed model can be transformed into a mixed-integer linear programming problem to solve. Finally, case studies are carried out on the modified IEEE 24-bus system comprising of six thermal units, a multi-chain cascade of four hydro plants and one wind farm, and simulation results verify the effectiveness of the proposed coordination scheduling model and method. • Two-stage stochastic optimization for hydro-thermal-wind system is proposed. • Dynamic extreme scenario set is constructed to describe wind power uncertainty. • Spatio-temporal coupling characteristics of cascaded hydro plants is considered. • A mixed-integer linear programming is built for solving the scheduling problem.

Reciprocating propagation of laser pulse intensity in free space

Constant-speed straight-line propagation in free space is a basic characteristic of light, and spatiotemporal couplings recently were used to control light propagation. In the method of flying focus, where temporal chirp and longitudinal chromatism were combined, tunable-velocities and even backward-propagation were demonstrated. We studied the transverse and longitudinal effects of the flying focus in space-time and found in a specific physics interval existing an unusual reciprocating propagation that was quite different from the previous result. By increasing the Rayleigh length in space and the temporal chirp in time, the created flying focus can propagate along a longitudinal axis firstly forward, secondly backward, and lastly forward again, and the longitudinal spatial resolution improves with increasing the temporal chirp. When this light is applied in a radiation pressure simulation, a reciprocating radiation-force can be produced accordingly. This finding extends the control of light and might enable important potential applications.