Effects of the Spatial Coupling of Water and Fertilizer on the Chlorophyll Fluorescence Parameters of Winter Wheat Leaves

Wheat is an important agricultural crop in the Loess region of China, where there is drought stress and low availability of soil nitrogen and phosphorus. Using a pulse modulation fluorometer, we studied the effects of water, nitrogen, and phosphorus on the kinetic parameters of chlorophyll fluorescence in winter wheat. The wheat was grown in layered columns of Eum-Orthic Anthrosol （Cinnamon soil）, with the water content and nutrient composition of each layer controlled. The results showed that the kinetic parameters of chlorophyll fluorescence were sensitive to water stress. The basic fluorescence （F0） of leaves was higher in the dry treatment （0-30 cm layer at 40-45% of field capacity, 30-90 cm at 75-80% of field capacity） compared to the wet treatment （entire soil column at 75-80% of field capacity）. The maximal fluorescence （Fm）, the variable fluorescence （Fv）, the photochemical efficiency （Fv/Fm） and potential activites （Fv/F0） of photosystem 2 （PS2） were significantly lower in the dry treatment. Although drought stress impaired PS2 function, this effect was significantly ameliorated by applying P or NP fertilizer, but not N alone. P application increased FJFm, both in well-watered and water stressed plants, especially when fertilizer was applied throughout the column or within the top 30 em of soil. A combined fertilizer improved photosynthesis in well watered plants, with Fm and F,fFm being the highest when fertilizer was applied throughout the columns. For drought stressed, plants FJFm was significantly greater when combined fertilizer was added within the top 30 cm of soil. We concluded that, when growing winter wheat in both arid and semi-arid parts of the Loess region of China, it is important to guarantee the nutrient supply in the top 30 cm of the soil.

An integrated method to calculate the spatial distribution of overburden strata failure in longwall mines by coupling GIS and FLAC^(3D)

The spatial distribution of overburden strata failure is of significant importance to affect the safety of underground mining. Because the traditional methods cannot be applied in all coal mines due to geological conditions or mining structures, a method of coupling FLAC3D with GIS was presented to calculate the spatial distribution of overburden strata failure in longwall coal mines. After building the spatio-temporal database from the calculation results of FLAC3D, the height of the mining-induced fractured zone in the overburden strata can be calculated by using the given height function. The results of case study show that the height of the fractured zone reached the maximum value at the face advance equal to about the panel width. The outcome of the work presented will be helpful in practice to improve safety in the production.

Spatial Coupling Relationship and Driving Mechanism of Population and Economy in Rural Areas in Qinling-Daba Mountains,China

Addressing the issue of the healthy and coordinated development of the population and economic factors in rural areas will not only help consolidate and expand the achievements of poverty alleviation,but will also lay a foundation for comprehensive rural revitalization.In this paper,the spatial coupling relationship between the population and economic factors in rural areas in the QinlingDaba Mountains,China,is explored to provide a reference for rural revitalization and regional sustainable development in poverty areas.Sixty-eight county units in rural areas in the Qinling-Daba Mountains,as well as the population and economic factors in rural areas,are used to study the spatial coupling relationship between population and economy,as well as the driving mechanism,in rural areas in the Qinling-Daba Mountains from 2010 to 2020.The results show that a population contraction phenomenon occurred in the rural areas in the Qinling-Daba Mountains,and the spatial agglomeration trends of the population and economic factors were consistent.The agglomeration was mainly located in the suburban areas of the municipal area,and the agglomeration degree was significantly higher in these areas than in other areas.In terms of the spatial distribution,the economic development level of the rural areas in the northeastern part of the Qinling-Daba Mountains was generally higher than that in the central and western parts,and the unbalanced trends of the population and economic spatial differentiation in the eastern and western regions were significant.The spatial coupling relationship between the population and economy changed from coordinated development to economic advancement.This was mainly due to the mutual restriction and joint actions of the industrial structure,capital situation,natural environment,policies,and institutional regulations,among which the industrial structure and capital status had significant effects.

The spatial coupling characteristics between the construction of Qingzang National Park Cluster and the sustainable development of local communities

The development of Qingzang national park cluster is part of China’s efforts to establish a major ecological civi-lization project in the Qingzang Plateau,in line with global sustainable development goals.Based on preliminary scientific investigation and research in the Qingzang Plateau,the construction of the park cluster will include 21 national parks.To mitigate the conflict between conservation of the national park cluster and the develop-ment of local communities,this study proposes an analysis framework to identify the spatial coupling features between the national park cluster and sustainable development of communities.Four elements were selected to construct the analysis framework,including natural conditions,geographic location,cultural background,and national policies.This framework was applied to the 457 township communities within the 21 national parks.Results show the weak influence of the construction of the national park cluster for approximately 304 township communities,without significant spatial coupling traits,while the remaining 153 communities demonstrated significant spatial coupling features.These latter townships had developed four types of spatial coupling with na-tional parks,including eco-migrants,transportation hubs,characteristic cultures,and border development,which account for 17.4%,35.3%,19.8%,and 27.5%of the 153 townships respectively.A composite type with more than one spatial coupling feature was also found for 14 communities within the 153 townships.This provides a reference for policy making towards four major types of interactive modes between townships and the national park construction for the sustainable development of Qingzang Plateau.

Spatial-temporal coupling between high-quality source rocks and reservoirs for tight sandstone oil and gas accumulations in the Songliao Basin, China

The spatial-temporal relationship between high-quality source rocks and reservoirs is a key factor when evaluating the formation,occurrence,and prospectivity of tight oil and gas reservoirs.In this study,we analyze the fundamental oil and gas accumulation processes occurring in the Songliao Basin,contrasting tight oil sand reservoirs in the south with tight gas sand reservoirs in the north.This is done using geochemical data,constant-rate and conventional mercury injection experiments,and fluid inclusion analyses.Our results demonstrate that as far as fluid mobility is concerned,the expulsion center coincides with the overpressure zone,and its boundary limits the occurrence of tight oil and gas accumulations.In addition,the lower permeability limit of high-quality reservoirs,controlled by pore-throat structures,is 0.1×10^-3μm^2 in the fourth member of the Lower Cretaceous Quantou Formation(K1q^4)in the southern Songliao Basin,and 0.05×10^-3μm^2 in the Lower Cretaceous Shahezi Formation(K1sh)in the northern Songliao Basin.Furthermore,the results indicate that the formation of tight oil and gas reservoirs requires the densification of reservoirs prior to the main phase of hydrocarbon expulsion from the source rocks.Reservoir“sweet spots”develop at the intersection of high-quality source rocks(with high pore pressure)and reservoirs(with high permeability).

Spatial coupling relationships of gas hydrate formation in the Tibetan Plateau

At present, gas hydrates are known to occur in continental high latitude permafrost regions and deep sea sediments. For middle latitude permafrost regions of the Tibetan Plateau, further research is required to ascertain its potential development of gas hydrates. This paper reviewed pertinent literature on gas hydrates in the Tibetan Plateau. Both geological and ge- ographical data are synthesized to reveal the relationship between gas hydrate formation and petroleum geological evo- lution, Plateau uplift, formation of permafrost, and glacial processes. Previous studies indicate that numerous residual basins in the Plateau have been formed by original sedimentary basins accompanied by rapid uplift of the Plateau. Ex- tensive marine Mesozoic hydrocarbon source rocks in these basins could provide rich sources of materials forming gas hydrates in permafrost. Primary hydrocarbon-generating period in the Plateau is from late Jurassic to early Cretaceous, while secondary hydrocarbon generation, regionally or locally, occurs mainly in the Paleogene. Before rapid uplift of the Plateau, oil-gas reservoirs were continuously destroyed and assembled to form new reservoirs due to structural and thermal dynamics, forcing hydrocarbon migration. Since 3.4 Ma B.P., the Plateau has undergone strong uplift and extensive gla- ciation, periglacier processes prevailed, hydrocarbon gas again migrated, and free gas beneath ice sheets within sedi- mentary materials interacted with water, generating gas hydrates which were finally preserved under a cap formed by frozen layers through rapid cooling in the Plateau. Taken as a whole, it can be safely concluded that there is great temporal and spatial coupling relationships between evolution of the Tibetan Plateau and generation of gas hydrates.

Research Advances in Spatio-Temporal Coupling of Water and Fertilizer in Sugarcane

The coupling of water and fertilizer is the only way for high yield, efficiency, sugar on sugarcane. On sugarcane production, the spatial and temporal controlling technology of fertigation is an important direction of the sustainable and healthy development of ecological agriculture in cane area of China. This paper reviews main achievements and advances on the coupling effect of water and fertilizer on sugarcane from time and space at home or abroad in recent years, analyzes the application prospects of the temporal and spatial coupling effect of water and fertilizer on sugarcane and puts forward some problems which need further research in future.

Coupling and coordination of provincial new urbanization and high-quality agricultural development in China, 2004-2018

The construction of a new type of urbanization is a necessary path for the development of modern cities,and a powerful support for coordinating the balanced development of urban and rural areas and promoting high-quality agricultural development.Based on the panel data of 30 provinces in China from 2004 to 2018,the article constructs a new urbanization and agricultural high-quality development evaluation system;then using the coupling coordination degree model and the spatial correlation analysis method,the paper empirically tests the coupling coordination of the two systems degree and its spatial relevance.The results of the study show that the average level of coupling and coordination between new urbanization and high-quality agricultural development in the period under study is at a barely coordinated level,with the highest level being moderately coordinated.There are significant inter-regional differences,with a higher level of coupling and coordination in the eastern regions and more room for improvement in the central and western regions.At this stage,the trend of"club convergence"is remarkable,with highhigh agglomeration and low-low agglomeration coexisting,and the polarization is serious.Therefore,comprehensively promoting the rural revitalization strategy,adhering to the integrated development of urban and rural areas,and enhancing inter-regional collaborative governance are powerful measures to promote the joint progress of new urbanization and high-quality agricultural development.

Describing spatiotemporal couplings in ultrashort pulses using coupling coefficients

Three coupling coefficients are defined to describe spatiotemporal coupling in ultrashort pulses. With these coupling coefficients, the first-order spatiotemporal couplings of Gaussian pulse and beam are described analytically. Also, the first-order and the second-order spatiotemporal couplings caused by angular dispersion elements are studied using these coupling coefficients. It can be shown that these coupling coefficients are dimensionless and normalized, and readily indicate the severity of spatiotemporal coupling.

Spatially nonlocal effects on optical absorption properties in coupled quantum wells with an applied electric field

Based on the microscopic nonlocal optical response theory, the intersubband optical absorption properties in AlGa As/Ga As couple quantum wells（CQWs） are investigated for p-polarized states. The numerical results show that spatial nonlocality of optical responses can induce a radiation shift on optical absorption spectra due to nonlocal effects. The dependence of the radiation shift on the CQW structure and the applied electric field is clarified. It is also demonstrated that the maximal radiation shift and the least optical absorbance can be obtained by adopting an appropriate CQW structure and a suitable applied electric field. This work may provide some methods of designing the nanomaterials with controllable nonlocality and observing the spatial nonlocal effects in experiment.

Rate-compatible spatially coupled repeat-accumulate codes via successive extension

A rate-compatible spatially coupled repeat-accumulate (RC-SC-RA) code is proposed. Its protograph is obtained by extending a given (J, K, L) SC-RA coupled chain (denoted as the mother chain) with extra check nodes and parity bit nodes T times. At each time, the extension is realized via coupling the message bits in the same way as that in the mother chain. Rate-compatibility is achieved by adjusting the extension parameters and applying random puncturing technique. Density evolution analysis shows that the iterative decoding thresholds of all the member codes in the proposed RC-SC-RA code family are very close to Shannon limits over the binary erasure channel. Finite length simulation results are consistent with the thresholds well. Moreover, the proposed RC-SC-RA codes perform better than spatially coupled low density parity check (SC-LDPC) codes in decoding performance especially in lower-rate region.

Coupling and Coordination Characteristics and Influencing Factors of the Livable Environment System for the Elderly in China

The construction of a livable environment for the elderly is an important measure to address the challenges of aging and improve their livelihood and well-being.Based on China’s national conditions and combined with the actual development needs of the cities,it is of great significance to explore the coupling and coordination characteristics and influencing factors within the livable environment system for the elderly for the coordination and stable development.This article was based on the three subsystems of’living service environment,socioeconomic environment and ecological livable environment’,following the research framework of’process-pattern-trend-impact’,constructs an evaluation index system for the livable environment for the elderly.Entropy weight-TOPSIS evaluation model,coupling coordination degree model,center of gravity and standard deviation ellipse model and the geographic detector model were used starting from the evolution of coupling coordination types to study the spatial and temporal pattern and dynamic trend characteristics and influencing factors of internal coupling coordination types in the livable environment system for the elderly from2010 to 2019.The results showed that:1)The coordinated development of life service environment system and ecological livable environment system(LE)and socioeconomic environment system and ecological livable environment system(SE)in the livable environment for the elderly decreased from the intermediate coordination level coordination areas to the low-level quality improvement and optimization areas:coordinated transition type.The overall development level of life service environment system and socioeconomic environment system(LS)was low,and it was always at a low level.2)The coupling degree of livable environment system for the elderly was high,the coupling coordination type shown a gradually decreasing layer structure with Zhejiang,Beijing and Guangdong high-level leading demonstration areas as the axis belt.3)The coupling coordination center of the elderly livable environment system was located in Henan,and the standard deviation ellipse was distributed in the northeast-southwest direction.The development center and the ellipse of the high-level leading demonstration areas and the intermediate coordination level areas were concentrated in the central and eastern regions,while the low-level coordination areas for improving quality and efficiency are mainly located in the western region.4)Urban development,green facilities,infrastructure,government macroscopic regulation and control,economic stimulus,and housing construction were all important factors affecting the coordinated development of the livable environment system for the elderly,exerting a varying degree of effect on the level of coordinated development of various types of systems.

Investigations into Capacity of MIMO Ad Hoc Network Including Effects of Antenna Mutual Coupling

This paper reports on investigations into capacity of ad hoc network whose nodes are equipped with multiple element antennas (MEAs). The investigation of this multi-user Multiple Input Multiple Output (MIMO) system takes into account mutual coupling (MC) in addition to spatial correlation that is present in array antennas. A closed-form expression for an upper bound of mutual information (capacity) of MIMO ad hoc network is derived. An optimal signal transmission scheme is proposed to maximize the MIMO ad hoc network capacity. Simulation results for capacity of non-optimized and optimized cases of signal transmission are presented.

Spatiotemporal differentiation of coupling and coordination relationship of production-living-ecological space in Yellow River Basin

Based on combing the existing research on the production-living-ecological space,the paper quantitatively analyzes the evaluation system-development level-temporal and spatial evolution,future trend-influencing factors of the production-living-ecological functions coupling and coordination in the Yellow River Basin from 2009 to 2018.Through multi-scale analysis and comparison,the paper tries to identify problem areas and put forward corresponding measures.The research results show that:(1)The coupling and coordination degree of the production-living-ecological functions in the Yellow River Basin both show an upward trend,and its future growth trend is relatively slow.(2)The spatial-temporal differential characteristics of the coordinated development level of the production-living-ecological functions are obvious,and gradually develop towards the direction of benign resonance in time,showing a spatial distribution pattern of“high in the northeast and low in the southwest”.(3)There is a big difference in the level of coordinated development of the production-living-ecological functions,and the coordination degree of the“production-living”function is the lowest.(4)Scientific and technological investment,economic development level,government capacity,and urbanization level have a significant positive impact on the spatial effect of the coordinated development of the production-living-ecological functions of the Yellow River Basin,and the same factor has different effects on different regions.

Beam Parameter Product Optimization for High Power SWIR Laser Diode Stack Fiber Coupling

An optimized setup for fiber optic injection of a kilowatt peak power laser diode stack emitting in the SWIR spectral range is proposed. Starting from a fast axis collimated (FAC) and slow axis collimated (SAC) 15 bars, 19 emitters off the shelf laser diode stack, the beam is transformed using spatial beam combining and polarization coupling. Both techniques integrated in a compact design enable to couple the kilowatt level beam into a standard 600 μm core, 0.22 numerical aperture (NA) multimode optical fiber. An application in the field of long range SWIR laser illuminator for gated viewing is presented. A comparison between two illuminators is realized both based on the same laser diode stack but one using beam parameter product (BPP) reduction and one without. It could be demonstrated that BPP reduction is the best way for efficient, narrow divergence and compact semi-conductor based laser illuminators design and realization. The global laser illuminator efficiency could be improved by 75% for the narrowest divergences thanks to this approach.

Coupled effects of climate change and human activities on vegetation dynamics in the Southwestern Alpine Canyon Region of China

The driving effects of climate change and human activities on vegetation change have always been a focal point of research.However,the coupling mechanisms of these driving factors across different temporal and spatial scales remain controversial.The Southwestern Alpine Canyon Region of China(SACR),as an ecologically fragile area,is highly sensitive to the impacts of climate change and human activities.This study constructed a vegetation cover dataset for the SACR based on the Enhanced Vegetation Index(EVI)from 2000 to 2020.Spatial autocorrelation,Theil-Sen trend,and Mann-Kendall tests were used to analyze the spatiotemporal characteristics of vegetation cover changes.The main drivers of spatial heterogeneity in vegetation cover were identified using the optimal parameter geographic detector,and an improved residual analysis model was employed to quantify the relative contributions of climate change and human activities to interannual vegetation cover changes.The main findings are as follows:Spatially,vegetation cover exceeds 60%in most areas,especially in the southern part of the study area.However,the border area between Linzhi and Changdu exhibits lower vegetation cover.Climate factors are the primary drivers of spatial heterogeneity in vegetation cover,with temperature having the most significant influence,as indicated by its q-value,which far exceeds that of other factors.Additionally,the interaction q-value between the two factors significantly increases,showing a relationship of bivariate enhancement and nonlinear enhancement.In terms of temporal changes,vegetation cover shows an overall improving trend from 2000 to 2020,with significant increases observed in 68.93%of the study area.Among these,human activities are the main factors driving vegetation cover change,with a relative contribution rate of 41.31%,while climate change and residual factors contribute 35.66%and 23.53%,respectively.By thoroughly exploring the coupled mechanisms of vegetation change,this study provides important references for the sustainable management and conservation of the vegetation ecosystem in the SACR.

乡村经济韧性与耕地破碎度空间格局及耦合关系研究——以重庆市奉节县为例

耕地破碎严重制约了乡村经济发展。探究乡村经济韧性与耕地破碎度之间的关系,对乡村振兴和土地整治策略制定有重要指导意义。本研究以重庆市奉节县60个村庄为研究对象,综合运用“压力—状态—响应”模型与熵权-TOPSIS法,探究奉节县乡村经济韧性和耕地破碎度的空间格局及二者之间的耦合协调关系。研究发现:①高经济韧性乡村在长江以北围绕奉节县城集聚分布,在长江以南零星分布;②高破碎度耕地呈“一心两翼”格局,奉节县中部和南北两端耕地破碎度较高;③乡村经济韧性与耕地破碎度之间耦合协调度以适度协调和初级协调为主,乡村经济发展处于过渡阶段;④地理加权回归分析显示奉节县西北部乡村耕地破碎度与乡村经济韧性之间呈显著负相关,耕地破碎度越高,乡村经济韧性越低。

Spatial Impact of High-speed Railway on the Urban Scale:An Empirical Analysis from Northeast China

The emergence of rapid transit,primarily represented by high-speed railway(HSR),while reshaping the regional traffic patterns,leads to the reconstruction and redistribution of population and industry.This leads to either shrinkage or expansion of urban scale.However,research on the influence mechanisms of the urban scale has mostly concentrated on historical,economic and social factors.The influence of traffic factors is rarely mentioned in current research.Therefore,this study examines Northeast China,where the change in urban scale is most significant,to discuss the spatial impact of high-speed railway on the urban scale.This is of great significance in terms of enriching current understanding of the factors affecting the urban scale.The results included the following:1)The high-speed railway produced considerable space-time convergence effects,however,simultaneously aggravated the imbalance in traffic development in Northeast China.The increase in accessibility presents attenuation characteristics from the high-speed railway.Additionally,the high-speed railway has changed the mode of cooperation between cities in the provinces,inter-regional and inter-provincial cooperation models gradually become popular.2)The change rate of accessibility and the urban scale present significant spatial coupling phenomena,with the change rate of the Harbin-Dalian trunk lines and its surroundings being more significant.3)There are predominantly four modes of the influence of high-speed railway on the urban scale,which make difference city present expansion or shrinkage.

Over-Constraints and a Unified Mobility Method for General Spatial Mechanisms Part 2:Application of the Principle

The pre-research on mobility analysis presented a unified-mobility formula and a methodology based on reciprocal screw theory by HUANG, which focused on classical and modem parallel mechanisms. However its range of application needs to further extend to general multi-loop spatial mechanism. This kind of mechanism is not only more complex in structure but also with strong motion coupling among loops, making the mobility analysis even more complicated, and the relevant research has long been ignored. It is focused on how to apply the new principle for general spatial mechanism to those various multi-loop spatial mechanisms, and some new meaningful knowledge is further found. Several typical examples of the genera/multi-loop spatial mechanisms with motion couple even strong motion couple are considered. These spatial mechanisms include different closing way： over-constraint appearing in rigid closure, in movable closure, and in dynamic closure as well; these examples also include two different new methods to solve this kind of issue： the way to recognize over-constraints by analyzing relative movement between two connected links and by constructing a virtual loop to recognize over-constraints. In addition, over-constraint determination tabulation is brought to analyze the motion couple. The researches above are all based upon the screw theory. All these multi-loop spatial mechanisms with different kinds of structures can completely be solved by following the directions and examples, and the new mobility theory based on the screw theory is also proved to be valid. This study not only enriches and develops the theory and makes the theory more universal, but also has a special meaning for innovation in mechanical engineering.

Joint 2D-DOA and polarization estimation for sparse nonuniform rectangular array composed of spatially spread electromagnetic vector sensor

In this paper,a sparse nonuniform rectangular array based on spatially spread electromagnetic vector sensor(SNRASSEMVS)is introduced,and a method for estimating 2D-direction of arrival(DOA)and polarization is devised.Firstly,according to the special structure of the sparse nonuniform rectangular array(SNRA),a set of accurate but ambiguous direction-cosine estimates can be obtained.Then the steering vector of spatially spread electromagnetic vector sensor(SSEMVS)can be extracted from the array manifold to obtain the coarse but unambiguous direction-cosine estimates.Finally,the disambiguation approach can be used to get the final accurate estimates of 2DDOA and polarization.Compared with some existing methods,the SNRA configuration extends the spatial aperture and refines the parameters estimation accuracy without adding any redundant antennas,as well as reduces the mutual coupling effect.Moreover,the proposed algorithm resolves multiple sources without the priori knowledge of signal information,suffers no ambiguity in the estimation of the Poynting vector,and pairs the x-axis direction cosine with the y-axis direction cosine automatically.Simulation results are given to verify the effectiveness and superiority of the proposed algorithm.