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At present, the fault diagnosis of pumping units in major oil fields in China is time-consuming and inefficient, and there is no universal problem for high requirements of hardware resources. In this study, a fault fusion diagnosis method of pumping unit based on improved Fourier descriptor (IDF) and rapid density clustering RBF (RDC-RBF) neural network is proposed. Firstly, the minimum inertia axis of the center of gravity of the indicator diagram is obtained. The farthest point of the intersection of the inertial axis and the contour is determined as the starting point. Then Fourier transform is performed on the contour boundary of the graph to obtain the feature vector. Then, combining with the idea of fast density clustering algorithm, the number of hidden layer neurons of RBF is determined by finding the point with the highest density and using it as the hidden layer neuron. At the same time, the characteristics of Gaussian function are introduced to ensure the activity of hidden layer neurons. Finally, through dynamic adaptive cuckoo search (DACS), the step size is automatically adjusted according to the convergence speed of the objective function of RBF, and the efficiency and accuracy of RBF in different search stages are balanced. The optimal parameters such as the width and weight of RBF are determined, and the optimal RDC-RBF fault diagnosis model is established. The model is applied to the diagnosis of different fault types of pumping units, and compared with the current mainstream models. The average detection accuracy of the fusion RDC-RBF fault diagnosis method proposed in this paper reaches 96.3%. The measured results have high accuracy and short time. At the same time, this method is currently applied to oil production sites such as Shengli Oilfield in China, which greatly reduces the human resources required for fault diagnosis of pumping units in the past. [ABSTRACT FROM AUTHOR]

Tea (Camellia sinensis L.), as one of the most important cash crops in China, plays an important role in increasing farmers' incomes and guaranteeing a high quality of life. Tea production has been greatly influenced by both climate change and economic development in China. However, without a scientific understanding of the interaction mechanism of climate change and the impetus from rapid economic development on tea production practices in China, it is difficult to take adaptive actions to meet the climate change challenges for the tea industry. In this paper, we firstly assessed the potential impacts of climate change on tea climate suitability by empirical formula calculation using meteorological data; then, the effects from the additional climatic stress due to warming on tea production were detected with the annual statistical tea yield record on a municipal level. The contribution of socioeconomic development to the tea industry was evaluated with the comparison of the movement of China's national economy's and tea industry's gravity center during the period of 1987–2017. Finally, a conceptual adaptation framework was built to demonstrate the interaction mechanisms between climate change, tea production, and the economic development. The results showed that there was a negative impact of climate change on tea production in mainland China, with the percentage of high tea climate suitability (>0.9) areas dropping by 45% to 32%, while opportunities of enlarging the tea cultivating area emerged in the north tea production region where the tea climate suitability increased. We found that the tea planting area expanded northwards from 33° N in 1987 to 35° N in 2017 to take advantage of the favorable climatic resources due to warming, and tea planting decreased at an altitude of 100–400 m while increasing to higher altitude of 400–2000 m to avoid hot temperature damage and seek the optimum environment in high mountainous areas for tea production. In addition, the tea production moved westward along the longitude, decreasing obviously at 117–121° E while increasing significantly at 98–104° E and 107–110° E. Meanwhile, the tea production gravity center showed a westward movement consistent with the national economic gravity center moving trend, which means that tea industry development was driven by multiple socioeconomic factors and climatic forcings. A conceptual framework was built in this paper, aiming to show a robust adaptation mechanism for the tea system to maximize the benefits and minimize the damages from the altered climatic resources under rapid economic development in mainland China. The results in this study would help deepen the understanding of the adaptation process and practices for tea production in mainland China. [ABSTRACT FROM AUTHOR]

With the ability to detect low-frequency gravitational waves (GWs), space-borne detectors will play an important role in exploring the universe in the future. The TianQin project proposed in China participates in this challenge by aiming to detect millihertz GWs. The TianQin GW detector consists of three spacecraft forming a triangular constellation. Each spacecraft carries a pair of test masses (TM) which, inside shielding cages, are left to free fall along the local geodesic. In this way, a pair of TMs on two separate spacecraft can be each other aligned to become the gravitational references of the GW detector, made by an inter-satellite laser interferometer. Each free-falling TM is limited by parasitic forces to be appropriately bounded. The relevant acceleration bound has been fixed to 10−15 m/s2/ Hz within the TianQin measurement bandwidth (MBW) ranging from 0.1 mHz to 0.1 Hz. In turn, TM to cage fluctuations must be kept below 4nm/ Hz to limit the stiffness coupling with the spacecraft displacement caused by non-gravitational disturbances, such as solar radiations and the thruster noise. Suppression of such disturbances calls for a challenging drag-free control technology, since the center of mass (CoM) of a single spacecraft cannot track the separated CoMs of two TMs simultaneously, and consequently tracking must be limited to three degrees of freedom (DoF): two non-orthogonal sensitive axes (one for each TM) and the perpendicular direction to their plane. Control design and simulated tests of this paper will be restricted to the drag-free control along the sensitive axes. The remaining nine DoFs of the two TMs (position and attitude) are controlled by electrostatic suspensions, not to be treated here, but accounted for in the simulated trials. The design of the two-DoF drag-free control relies on a model-based control methodology, the Embedded Model Control (EMC), capable of predicting and suppressing unknown disturbances within the required bandwidth and of decoupling the TM dynamics along the non-orthogonal sensitive axes. The paper starts with the nonlinear model of the TM to cage dynamics, followed by the relevant EMC design, restricted to the sensitive axes. Numerical simulations are employed to validate closed-loop performance and robust stability. Simulated results show that the residual TM to cage fluctuations can be kept below 3nm/ Hz , which leaves a margin within the required spectral bound. The EMC methodology discussed in the paper can provide a reference for future developments and implementations. • Test mass dynamics can be decoupled by 'thruster coupling' or 'sensor coupling'. • Embedded Model Control predicts and compensates unknow disturbances. • Reference generator smooths test mass centering process. • Test mass to cage displacement has satisfied TianQin requirement. • Monte Carlo trails have validated the closed-loop robust stability. [ABSTRACT FROM AUTHOR]

China is a large country with rapid economic expansion and high energy consumption, which implies that the country's overall carbon emissions are enormous. It is vital to increase urban low-carbon economy efficiency (ULEE) to achieve sustainable development of China's urban economy. Digital finance is a significant tool to boost ULEE by providing a convenient and effective funding channel for urban low-carbon economic transformation. Analyzing the coupled and coordinated relationship between ULEE and digital finance is of vital importance for the sustainable development of the urban economy. This paper selects panel data of 100 cities in China's Yangtze River Economic Belt (YEB) in 2011-2019, and analyzes the research methods such as the Global Malmquist-Luenberger index model, coupling coordination degree (CCD) model, standard deviation ellipse model, gray model, and geographic detector by The spatial and temporal distribution, dynamic evolution characteristics and influencing factors of the CCD between ULEE and digital finance are analyzed. The study shows that: (1) the CCD of ULEE and digital finance grows by 3.42% annually, reflecting the increasingly coordinated development of the two systems; (2) The CCD of ULEE and digital finance shows a distribution pattern of gradient increase from the upstream region of Yangtze River to the downstream region, meanwhile, the spatial center of gravity moves mainly in the midstream region; (3) The spatial center of gravity of CCD of ULEE and digital finance is expected to move 22.17 km to the southwest from 2019 to 2040; (4) In terms of influencing factors, the influence of informatization and industrial structure on the CCD increases over time, while the influence of factors such as population development, greening, transportation, and scientific research decreases over time. Finally, this paper proposes policy recommendations for improving the CCD of ULEE and digital finance based on the empirical results. [ABSTRACT FROM AUTHOR]

With the rapid development of urbanization construction in China, population and industries are rapidly gathering in cities, bringing about economic development and also causing a large number of environmental problems, among which PM2 s is the most concerned. In this paper, a spatial gravity center model was used to systematically analyze the spatiotemporal distribution characteristics of PM, s and population scale in China from 1999 to 2016. Conclusions were as below; (1) there were significant regional differences in PM2 s pollution from 1999 to 2016, characterized by a spatial distribution of "high in the north and low in the south, and high in the inland and low in the coastal areas". (2) Nationwide, there was a significant spatial mismatch between the gravity center of PM2 s pollution and the gravity center of population scale, with the two centers showing a trend of reverse dislocation development. [ABSTRACT FROM AUTHOR]

Landslide failure near a reservoir generates impulse waves, greatly increasing casualties and property losses. This paper presents a field investigation and potential impulse wave simulation analysis of the Wulipo (WLP) landslide, which deformed after the initial impoundment of the Baihetan Hydropower Station, China. According to geological surveys, the WLP landslide is a weak base-type, weathered, fragmented rockslide with soft rock in the lower portion and hard rock in the upper portion. The deformation and failure mechanism under the action of reservoir water consist of compression, fracturing, and shearing. The periodic fluctuation of reservoir water may cause overall high-speed slip failure of the WLP landslide. According to the inferred failure mode of the WLP landslide, the impulse waves caused by the overall failure of the landslide at the highest (825 m) and lowest (765 m) water levels are predicted. Due to the significant height difference between the center of gravity of the landslide and the reservoir water level, the wave height and fluctuation degree of the overall failure of the WLP landslide for 765 m are significantly greater than those for 825 m. However, the wave flood area for 825 m is larger than that for 765 m. Although the impulse waves triggered by the overall landslide at either water level will not destroy the nearby Menggu community, at 765 m, impulse waves will overflow the bridge deck of Ganhu Road. Therefore, engineering measures such as reducing the landslide volume can lower the secondary disaster risk posed by WLP landslides. This study provides insights into landslide disaster risk in the Baihetan Reservoir region and similar areas worldwide. [ABSTRACT FROM AUTHOR]

The Central Plains has a long history, rich culture, unique geographical advantages, and profound cultural heritage. The occurrence of ancient cities in the Central Plains marks the formation of Chinese state-level societies. The number, size, and distribution of ancient cities have changed greatly from the late Yangshao to the Xia and Shang Dynasties, which reflects the evolution of settlement and social organization. In this study, Geographic Information System (GIS) spatial database technology was used to establish a spatiotemporal database of ancient cities in the late Yangshao, Longshan, as well as Xia and Shang Dynasties in the Central Plains. This paper uses GIS spatial analysis technology to analyze the relationship between the ancient city distribution and the geographical environment, as well as the evolution of ancient city's shapes and sizes. Furthermore, by using the method of the nearest neighbor distance and gravity center analysis, this paper discusses the agglomeration characteristics and gravity center evolution of ancient cities. The results show that: (1) Most of the ancient cities were distributed in areas below 500 m and within 3 km from the river during the time interval from the late Yangshao to Xia and Shang Dynasties; (2) The shape of the ancient cities gradually changed from circles to squares in the Central Plains, which became a unified model for the later ancient city design; (3) The sizes of the 18 ancient cities in the Yangshao period shared high similarity, with an average area of 20 hectares. The sizes of 24 ancient cities in the Longshan period increased significantly, with an average of 39 hectares. During the Xia and Shang Dynasties, there were 22 ancient cities with an average size of 340 hectares, and the grade of sizes became obvious, marking the entrance into Chinese state-level societies; (4) Cities were scattered in the decentralized pattern during the late Yangshao and Longshan periods, whereas they became agglomerative in Xia and Shang Dynasties. This reflects the evolution of the spatial scopes and social organizational forms; and (5) From the late Yangshao to Xia and Shang Dynasties, the gravity center of ancient cities moved around the Songshan Mountain from the northwest to the southeast and again to the northeast. [ABSTRACT FROM AUTHOR]

Based on the research of spatial pattern dynamic evolution algorithm and optimization model construction and driving mechanism of provincial tourism eco-efficiency in China under the background of cloud computing, this paper takes 30 provinces in mainland China (excluding Tibet, Hong Kong, Macao, and Taiwan) as the research object and scientifically constructs the measurement index system of tourism eco-efficiency. The Super-SBM-Undesirable model is used to measure the tourism eco-efficiency of each province from 2004 to 2017, and the algorithm and model are optimized. This paper explores the spatial evolution trajectory and path of tourism eco-efficiency by using the barycentric standard deviation ellipse method and constructs a dynamic panel model to identify the factors affecting the evolution trajectory and their driving mechanisms by using the SYS-GMM method. The results show that China's tourism eco-efficiency is at a high level and the eastern region is higher than the central and western regions. From the moving track of the center of gravity, the center of gravity of China's tourism eco-efficiency is located in Henan province, which has experienced a process of moving from southeast to northwest. From the standard deviation ellipse, the spatial distribution direction of China's tourism eco-efficiency presents a "northeast-southwest" pattern, and there is a further strengthening trend of deviation. There is a significant positive correlation between tourism eco-efficiency and tourism industrial structure upgrading, tourism industrial structure rationalization, tourism technology level, and tourism human capital, as well as a significant negative correlation between tourism eco-efficiency and tourism economic development level, environmental regulation intensity, and the degree of opening to the outside world, while the relationship between urbanization and tourism eco-efficiency is relatively vague. [ABSTRACT FROM AUTHOR]

Accelerating the promotion of high-quality development of tourism (HQDT) is of great significance to the sustainable development of tourism. This paper defined the concept of HQDT, and then built an evaluation system for HQDT measurement to analyze the spatio-temporal evolution characteristics of China's HQDT based on provincial panel data from 2010 to 2019, using Geodetector to explore the similarities and differences between driving factors of HQDT and tourism development scale (TDS). The results show that: 1) Taking the development concepts of innovation, coordination, green, openness and sharing as the guidance, and considering the organic unity of quantity and quality, the evaluation index system of the HQDT consists of six dimensions of economic stability, innovation driving, coordination and linkage, green and sustainability, openness and cooperation, and sharing and harmony, which respectively represent the basis, momentum, means, orientation, direction and purpose of the HQDT; 2) The level of China's HQDT shows an upward trend, presenting the characteristics of eastern region > central region > western region > northeastern region in 2019. The regional differences in China's HQDT show a downward trend, and the intra-regional differences have replaced the inter-regional differences as the main source of regional differences; 3) China's HQDT shows the characteristics of higher in the east and lower in the west along the Hu line, while the improvement speed of HQDT shows the characteristics of faster in the west and slower in the east, making the decline of east-west differentiation of China's HQDT and the movement of the gravity center towards southwest; 4) Both HQDT and TDS are obviously driven by tourism capital investment and regional consumption. In terms of differences, the HQDT is more driven by government guidance, innovation driving force, and opening up, while the main driving factors of TDS are more biased toward capital elements and hardware facilities, including informatization, tourism resource, traffic, and eco-environment. [ABSTRACT FROM AUTHOR]

Urban economic development is crucial to regional economy and people's life, and enhancing the efficiency of urban economic development is of great significance to boost sustainable and healthy economic and social development. In this paper, from the perspective of sustainable development, data of 104 cities in China's Yangtze River Economic Belt (YREB) from 2004 to 2019 are selected, and the urban resource consumption index and urban pollutant emission index are synthesized as new input-output indicators using the Time Series Global Principal Component Analysis (GPCA), combined with the Global Malmquist-Luenberger (GML) Index Model, Standard Deviation Ellipse (SDE) Model to measure the total factor productivity index of urban economic development in China's YREB and analyze its spatial and temporal evolution. The results show that from 2004 to 2019, the total factor productivity index of urban economic development in China's YREB showed an overall fluctuating upward trend with an average annual growth of 5.8%, and the analysis by decomposing indicators shows that the growth of total factor productivity of urban economic development in China's YREB is mainly influenced by the growth of technological progress. Meanwhile, there are obvious regional differences in the efficiency of urban economic development in China's YREB, with the largest difference in the middle reaches of the Yangtze River, the second largest in the upper reaches, and the smallest in the lower reaches. From 2004 to 2019, the efficiency center of gravity of urban economic development efficiency in the YREB has always been located in the middle reaches of the Yangtze River region. The spatial distribution pattern of urban economic development efficiency in the YREB is dominated by the northeast-southwest direction and tends to be concentrated in the study time period. [ABSTRACT FROM AUTHOR]

The combination of knowledge innovation and technology innovation provides vitality for social science and technology innovation. China leaps into the front ranks of the world in the 2021 Global Innovation Index (GII). Therefore, this research takes China's theoretical-application innovation as the research object and empirically analyzes measure the innovation efficiency of knowledge innovation dominated by universities and technological innovation dominated by enterprises in China, as well as the gravity-center migration trajectory. The results show that the ranking of overall efficiency of theoretical innovation-application innovation is eastern region > central region > western region. Knowledge innovation presents a drag on overall efficiency, while technology innovation offers a contribution to overall efficiency. In the analysis of PIE (R&D personnel of industrial enterprises above a designated size) variables, the efficiency value is relatively low. The peak value of kernel density increases in the eastern, central and western regions, namely the concentration degree of theoretical innovation-application innovation effi- ciency in China has risen. The gravity center of each stage migrates to the eastern region, meaning the efficiency value of China's theoretical innovation and application innovation increases more significantly in the eastern region. From the perspective of knowledge innovation and technology innovation, this paper puts forward suggestions for China and provides some references for other developing countries. [ABSTRACT FROM AUTHOR]

National nature reserves are an important part of classification management on ecological protection in China. Taking the national nature reserves of Jilin Province as examples, this paper introduced the stability index by referring to the intensity model of land-use and land-cover change (LUCC), and analyzed the overall stability of land-use and land-cover (LULC) in the study area from the time interval level and land category level. The stability of LULC in different types of nature reserves was tracked and identified by extracting land-use change trajectory, and the land-use change trajectory was divided into three types: stable type, sub-stable type and unstable type. The impact of LUCC on regional ecosystem services was studied by using hotspot analysis and gravity center analysis. The results showed that: 1) The LULC in the study area was stable on the whole, and the proportion of stable land area reached 86.08%. The intensity of LUCC showed an increasing trend in recent 20 years, and the conversion of cultivated land and construction land was active in continuous time interval. 2) The stability of LULC in forest ecological reserves and wildlife reserves in the eastern part of Jilin Province was the highest, while that in inland wetland reserves and geological relic reserves in the central and western part of Jilin Province was lower. 3) The LUCC in national nature reserves not only changed the value of its own ecosystem service function, but also affected the ecosystem service function of the whole region. The combination of intensity analysis and land-use change trajectory was used to identify the characteristics of stability of LULC in nature reserves, which was conducive to deeply understand the process of LUCC in national nature reserves and provided reasonable suggestions for regional ecological protection. [ABSTRACT FROM AUTHOR]

Since the Ming Dynasty, the flood disaster has been one of the important natural disasters affecting our country. However, relatively few studies on the evolution law of flood disaster at large spatial–temporal scales have been reported. Based on the datasets of flood stations from 1470 to 2000, this paper quantitatively analyzes and discusses the spatial and temporal evolution pattrens of floods in China in the past 500 years by using regional gravity center model, wavelet analysis, Daniel index, and M–K test, and predicts the trend of flood disasters in the future. The results show that: (1) Since 1470, there has been an increasing trend of flood intensity index in China;(2) From 1470 to 2000, there were two high centers of flood disaster in 1560 and 1925, respectively, and one low center appeared in 1745; (3) Flood risk changes from easy occurrence in the eastern coastal area to uniform spatial distribution over the whole study region; (4) In the past 500 years, the graver center of flood disaster is located in Baokang County, Hubei Province, and the gravity center of flood disaster shows a trend of moving to northwest both at time scales of 50-year and 100 year; (5) The flood disaster in the studied area will still show an overall upward trend in the future.The research can provide decision support for the precise prevention and control of flood disasters in China. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to analyze the characteristics of spatio-temporal dynamics and the evolution of land use change is essential for understanding and assessing the status and transition of ecosystems. Such analysis, when applied to Horqin sandy land, can also provide basic information for appropriate decision-making. Design/methodology/approach: By integrating long time series Landsat imageries and geographic information system (GIS) technology, this paper explored the spatio-temporal dynamics and evolution-induced land use change of the largest sandy land in China from 1983 to 2016. Accurate and consistent land use information and land use change information was first extracted by using the maximum likelihood classifier and the post-classification change detection method, respectively. The spatio-temporal dynamics and evolution were then analyzed using three kinds of index models: the dynamic degree model to analyze the change of regional land resources, the dynamic change transfer matrix and flow direction rate to analyze the change direction, and the barycenter transfer model to analyze the spatial pattern of land use change. Findings: The results indicated that land use in Horqin sandy land during the study period changed dramatically. Vegetation and sandy land showed fluctuating changes, cropland and construction land steadily increased, water body decreased continuously, and the spatial distribution patterns of land use were generally unbalanced. Vegetation, sandy land and cropland were transferred frequently. The amount of vegetation loss was the largest. Water body loss was 473.6 km2, which accounted for 41.7 per cent of the total water body. The loss amount of construction land was only 1.0 km2. Considerable differences were noted in the rate of gravity center migration among the land use types in different periods, and the overall rate of construction land migration was the smallest. Moreover, the gravity center migration rates of the water body and sandy land were relatively high and were related to the fragile ecological environment of Horqin sandy land. Originality/value: The results not only confirmed the applicability and effectiveness of the combined method of remote sensing and GIS technology but also revealed notable spatio-temporal dynamics and evolution-induced land use change throughout the different time periods (1983-1990, 1990-2000, 2000-2010, 2010-2014, 2014-2016 and 1983-2016). [ABSTRACT FROM AUTHOR]

• A conceptual framework and model of microagroecosystems were constructed. • Assessed the degree of landscape ecological risk in microagroecosystems. • The human activity gravity of microagroecosystems shifted to lower altitudes. • The ecological vitality of microagroecosystems is increasing. • Clarified micro-spatial human-land relations and development directions. Micro-spatial agroecosystem (AES) changes in karst mountain areas are a response to the human-land relationship of the human activity center. However, the changes and linkages between AESs and landscape ecological risks (LER) from a micro perspective in karst mountain areas (KMA) have not yet attracted in-depth attention from the academic community. This paper proposes the concept of microagroecosystems (MAESs) and constructs the MAES model based on the landscape development intensity (LDI) to evaluate the systematic landscape evolution rules and the LER intensity, which reflects the human-land relationship in KMA. We used the buffer ring with a 200 m cultivation range interval to categorize the MAES model into six models, namely, High-Mid-Low, High-Low-Medium, Medium-High-Low, Medium-Low-High, Medium-High-High, Low-Medium-High and Low-Medium-High, and the different models not only reflect the regional conditions but also represent the different stages of the evolution of AESs in KMAs. We found that AESs in karst mountainous areas are transforming from traditional food crop systems to economic fruit forest ecosystems, and at the same time, the gravity center of human activities is migrating from high to low altitude areas, and the ecological vitality of MAESs is showing a trend of enhancement. In addition, the regions with high altitudes and steep slopes in karst mountainous areas have a single landscape structure and are dominated by traditional food cultivation, while the regions with low altitudes and gentle slopes have a diverse landscape structure and are dominated by modern and sustainable agricultural development. Finally, we reveal that the LER in KMAs shows a trend of initial increase followed by subsequent decrease, the influence of the human-land relationship on the LER in the micro perspective is significant, and the coordination and trade-off between agricultural development and environmental protection is the key direction of development in the future. The study results can provide a reference for the rational allocation of landscape, ecological environment restoration, and optimization of regional human-land relationships in KMAs worldwide. [ABSTRACT FROM AUTHOR]

Understanding the historical change trajectory of Land Use/Land Cover Change (LUCC) is helpful to analyze the land use trends under the interference of human activities and changes in the natural environment, thereby helping decision makers to eliminate the negative impact of unreasonable land use patterns to the greatest extent. Yellow River Basin is the fifth longest river in the world, its ecological environment continues to deteriorate due to the rapid population growth and urban expansion, which has become one of the regions with the most serious soil erosion in China. Aiming to promote the ecological quality and high-quality development of social economy under the human interference and natural environment change, we analyzed the spatiotemporal dynamic of the LUCC in the Yellow River Basin (Henan section) from the watershed scale and proposed policy recommendations. We introduced the chord diagram visualization model to intuitively show the flow, direction and diversity of land cover changes, which would enrich the visual research method system of the land cover quantity transfer trajectory. The land use change index, chord diagram model and gravity center transfer model were used in this paper to analyze the spatial-temporal evolution trajectory and policy implications of the land use pattern in the Yellow River Basin (Henan section) in the past 30 years based on the land use remote sensing data in 1990, 2000, 2010 and 2018. The results showed that: 1) Ecological conservation land (35%) was mainly concentrated in the mountainous areas with higher elevation in the middle reaches; food security land (55%) and production and living land (10%) were mainly distributed in the central and eastern plains. 2) The outflows and inflows of dry land from 1990 to 2018 showed significant dominance; paddy field, water and grassland were dominated by outflow; urban land, rural settlements and other construction land were dominated by inflow. 3) The land use change in central cities had significant regional driving effects throughout the period. 4) The gravity center of food security land and ecological conservation land moved to the West and the area showed a decreasing trend, which proved that the high-quality cultivated land in the plain area in the lower reaches decreased and the ecosystem service function gradually weakened; The shift of gravity center of urban land to the East indicated that the social and economic development in the lower reaches were gradually active. The shift of gravity center of rural residential and other construction land to the West indicated that the population scale in the middle reaches was gradually increasing. [ABSTRACT FROM AUTHOR]

Water, energy, and food (WEF) are essential material bases for mankind's survival and development. At the same time, water and energy, as necessary inputs for food production, are of great significance to food security. Scientific understanding of the water-energy-food nexus (WEF Nexus) in food production is conducive to ensuring food security and sustainable utilization of basic resources. However, current research linking the WEF Nexus with food production is lacking. Therefore, we took the WEF Nexus as an entry point to quantify China's food production efficiency and considered the direct and indirect inputs of water and energy in food production in this paper. First, we constructed an evaluation index system of food production efficiency based on the perspective of input-output and used the stochastic frontier production function model to measure the absolute efficiency values of food production. Then, GIS spatial analysis, spatial autocorrelation analysis, and the gravity center model were used to reveal the spatial-temporal pattern, spatial autocorrelation characteristics and barycenter trajectory, respectively. Finally, the Tobit model was applied to analyze the main factors which influenced the spatial pattern changes of food production efficiency. The research results indicated that China's food production efficiency was on the rise and there were spatial differences between provinces. Per capita GDP, natural disaster losses and irrigated areas of food crops were the main factors influencing China's food production efficiency. This paper contributed a new theoretical reference to the study of food production efficiency, and provided a decision-making reference for regional resource management to ensure basic resource security and sustainable development in the future. [Display omitted] • Taking WEF Nexus as an entry point to quantify China's food production efficiency based on SFA model. • Analyzing the temporal and spatial characteristics and influencing factors of China's food production efficiency. • China's food production efficiency was on the rise and there are spatial differences between provinces from 2000 to 2018. • The paper made reasonable policy recommendations in view of China's food production efficiency current situation. [ABSTRACT FROM AUTHOR]

Starting in 1997 with the 5th International Conference on Slags and Fluxes, a survey on research on slags has been carried out for every conference on slags and fluxes. Trends from 1980, the year of the first conference in Halifax, Canada, have been traced and discussed. For the ninth conference in the series, the survey is focused on research on molten slags and fluxes published from 2000 to 2010. In these 10 years, the center of gravity of the metals industry has shifted eastwards towards China, and the slags and fluxes literature follows this geographical shift with reference to numbers of papers published per annum. The increased attention on sustainable metals production (including recycling of valuable metals and reuse of slags as cement or construction material) is reflected in the type of research on slags. Minimization of slag production per unit of metal produced is another trend triggering innovative production process development. An in-depth analysis is given of papers published in 2010 in selected journals from China, Europe and USA in terms of slag systems, type of research and geographical origin. [ABSTRACT FROM AUTHOR]

To grasp the characteristics of CO 2 emissions across provinces in China and to determine changes in the centre of gravity of CO 2 emissions over the 2000–2014 period, a gravity model is first used to examine the spatial distribution and centre of gravity of energy-related CO 2 emissions. Then, to explore the main factors driving CO 2 emission changes and to uncover feasible ways to reduce CO 2 emissions, this paper decomposes changes in energy-related CO 2 emissions into a population effect ( Δ C P ), an economic output effect ( Δ C Q ), an industrial structure effect ( Δ C S ), an energy intensity effect ( Δ C I ), an energy structure effect ( Δ C M ) and a carbon dioxide emission coefficient effect ( Δ C U ) at both the national and provincial levels based on the Log-Mean Divisia Index (LMDI) method. The results indicate that (1) energy-related CO 2 emissions rose by approximately 5.46 billion tonnes during the 2000–2014 period, with secondary industry accounting for approximately 80% of total CO 2 emissions. (2) Economic output ( Q ) was the dominant positive driving factor, and energy intensity ( I ) was the dominant negative driving factor. The population changes had a weak positive effect on CO 2 emissions, but the industrial structure effect and energy structure effect varied considerably over the years without showing clear trends. (3) Over multiple spatial scales, the contribution ratios of the factors varied significantly across provinces; in general, the positive driving effects outweighed the negative inhibiting effects. Based on these empirical findings, policy recommendations to further reduce CO 2 emissions are provided. The Chinese central and local governments should make full use of the important inhibiting factors, i.e., energy intensity and energy structure, and strive for breakthroughs in secondary sector. [ABSTRACT FROM AUTHOR]

• The GSE-EBM model is used to measure GIE. • Spatial character and distributional evolution of China's urban GIE is analyzed. • The spatial heterogeneity of China's urban GIE's influencing factors is investigated by the GWR model. • A variety of valuable and targeted policy implications are presented. Based on employing the global super efficiency epsilon-based measure (GSE-EBM) model to evaluation the green innovation efficiency (GIE) of 285 prefecture-level or above cities in China during the period 2004–2018, this paper combines the approaches of kernel density estimation, cold hot spot analysis and standard deviation ellipse to intuitively describe GIE's spatiotemporal pattern evolution features, and then utilizes the geographical weighted regression (GWR) model to explore the spatial heterogeneity of GIE's affecting factors. The results show that: (1) China's urban GIE displayed a fluctuating increasing trend, revealing clearly regional disparities, and gradually decreased from the Eastern coastal region to the Central, the Western and the Northeast region. (2) The spatial difference of China's urban GIE exhibited the characteristics of expansion, polarization, and spatial agglomeration with the center of gravity gradually shifting to the Southeast region. (3) In the analysis of socio-economic factors of China's urban GIE, the GWR model effectively identified the spatial heterogeneity, and improved the explanatory ability compared to ordinary least squares (OLS) model. (4) The GWR model analysis indicate that population density, economic development, transportation infrastructure, openness and industrial structure played significant impacts on China's urban GIE, and there exists significant spatial heterogeneity in the impact of each influencing factor. The findings of this study can provide valuable references for urban green transformation and high-quality development in China. [ABSTRACT FROM AUTHOR]

• Spatial pattern and evolution trends of four kinds of residential energy consumption in China are investigated. • Spatial difference in the distribution of gravity centers of residential energy consumption is depicted. • Standard deviational ellipse demonstrates the dynamic evolution patterns of residential energy consumption. • Coupling coordination degree between residential energy consumption and the economic indicator is investigated. • Electricity should be taken into further consideration in the development of residential energy improvement. The residential energy consumption in China shows diversity and complexity in space. This paper aims to investigate the spatial pattern and evolution trends of four kinds of residential energy consumption (electricity, coal, oil, and natural gas) through gravity center modeling and standard deviational ellipse modeling. Further, their relations to economic growth are probed by using the coupling and coordination degree model. Panel data at the provincial level in China are collected from 2000 to 2019. Our results show that the most drastic movement trend of gravity centers is coal, natural gas, followed by oil, whereas electricity moved slightly in space. Further, the standard deviational ellipse of electricity exhibits relatively stable patterns than the other three residential energy consumption during the study period. In addition, the coupling coordination degree between residential energy consumption and the economic growth is examined, and the results indicate that the total residential electricity consumption shows the highest coupling coordination degree, followed by residential gas, oil, and coal. It demonstrates lower coupling coordination degrees in rural areas than in urban areas in the total and sectoral residential energy consumption. In sum, several policy implications can be demonstrated based on our findings, i.e., the development of electricity consumption in the residential energy structure may improve the energy stability in space in China, and ensuring access to electricity should be taken into further consideration in the development of residential energy improvement to achieve a better coordination level to economic development. [ABSTRACT FROM AUTHOR]

Some literature has documented ambient fine particulate matter (PM 2.5) pollution and corresponding health burden in China, however, the knowledge of spatial disequilibrium of PM 2.5 and PM 2.5 -induced disease burden is scarce. With the help of gravity center model, spatial autocorrelation analysis as well as the region-specific exposure-response coefficient and ground-based PM 2.5 daily concentrations over 336 cities in China from January 2016 to December 2017, this paper provides a completive assessment for spatial disequilibrium of PM 2.5 -induced health burden. Improving PM 2.5 concentrations and declining PM 2.5 -induced health burden were found in China. The 2-year city-average concentration of the 336 cities was 45 ± 17μg/m3 with a range from 11μg/m3 to 128μg/m3. PM 2.5 -related deaths from stroke, ischemic heart disease, chronic obstructive pulmonary disease, hypertensive heart disease and lower respiratory infection amounted to 0.766 million in 2016 and 0.720 million in 2017. Much higher but decreasing PM 2.5 -induced mortality happened in the west, while higher and increasing PM 2.5 -induced deaths existed in the south. Strong spatial autocorrelation of PM 2.5 and PM 2.5 -induced disease burden existed among cities, illustrated by high-high (HH) clusters with significant spatial homogeneity and spatial spillover effect. The cities included in PM 2.5 concentration HH cluster had average PM 2.5 concentration 68.5 μg/m3, about 1.5 times higher than the national average; the cities involved in combined mortality HH cluster had mortality 90.5/105, 1.8 times as much as the national city-average level; about 46.4% of PM 2.5 -induced combined deaths happened in HH cluster cities. The cities embraced in the HH clusters of PM 2.5 concentration, population, deaths and mortality simultaneously, mostly located in Hebei, Shandong and Henan provinces, should be the top priorities for joint air pollution control. This paper provides important implications for policymakers regarding priority areas of joint air pollution control in China. Image 1 • PM 2.5 pollution contributed to around 0.74 million premature deaths per year. • Improving PM 2.5 levels and declining PM 2.5 -induced health burden were found. • Strong spatial disequilibrium and autocorrelation existed. • Much higher but decreasing PM 2.5 -induced mortality happened in west. • Cities overlapped in HH clusters should be the top priorities for joint control. [ABSTRACT FROM AUTHOR]

Soil wind erosion is an important ecological environmental problem that is widespread in arid and semi-arid regions. Currently, related studies are mainly focused on spatiotemporal characteristics or analysis of effector mechanisms, and they do not facilitate direct servicing of management decisions. In this paper, we used the Xilingol typical steppe in Inner Mongolia, China, as a study site to develop a decision framework for a comprehensive understanding of soil wind erosion and to promote sustainable management of steppes. In this study, we used the Revised Wind Erosion Equation model to simulate soil wind erosion. We combined this model with linear trend analysis to evaluate the ecological effects of soil wind erosion and wind erosion intensity, and delineated the gravity center migration path. We used the constraint line method to reveal the mechanisms by which climatic factors affected soil wind erosion, achieved the spatial visualization of wind-breaking and sand-fixing service flow, and proposed decision-based regional sustainable development suggestions. The results showed that long-term soil wind erosion will lead to soil coarsening and loss of soil nutrients. Soil wind erosion in the study site showed worsening trends and risks, and as such, ecological environment conservation and management are urgently required. The study framework promotes a clear understanding of the complex relationship of human–earth systems. The study results will aid in the ecological remediation of steppe landscapes and the prevention of desertification and will provide a foundation for win–win management of ecological conservation and economic development in arid and semi-arid regions. • A decision-oriented management framework was developed from the perspective of soil wind erosion prevention and control. • Long-term soil wind erosion will lead to soil coarsening and loss of soil nutrients. • The constraint line method can help to reveal the complex effects of meteorological factors on soil wind erosion. • The study achieved spatial visualization of wind-breaking and sand-fixing service flow in grassland ecosystem. [ABSTRACT FROM AUTHOR]

In order to better achieve the goal of carbon emissions, this paper combined the theory of gravity center and Logarithmic Mean Divisia Index (LMDI) model to analyze the regional emission differences in China. Researches have shown that the difference in economic development levels between the eastern and western regions is an important factor that causes the shift of the center of gravity of carbon emission and its intensity to the west. In decomposition effects, the economic output effect has the largest contribution (56%) to emissions, and the energy intensity effect has the best effect in suppressing emissions. Except for some industries in the East and Central South of China, energy structure in other regions is still dominated by high-carbon energy. In the energy intensity effect, the suppression effects in the East and Central South of China have reached −83,440 Mt and −78,850 Mt respectively, while the Northeast and Northwest of China areas are not significant. Vigorously developing low-carbon technologies and promoting clean energy can effectively reduce carbon intensity. It is recommended to implement the policy of adapting to local conditions according to the current situation of the region, and gradually phase out high energy-consuming industries under the guidance of the government, so as to strive to implement the emission reduction target. • Industrial energy consumption difference between regions were analyzed for China. • Economic output has the largest effect to emission. • Center of gravity theory is used to analyze emission. • The adjustment of industrial structure has a lagging effect on carbon emissions. [ABSTRACT FROM AUTHOR]

Zhan, L., 2020. Spatial pattern evolution and mechanism of coastal economic zone based on accessibility. In: Yang, Y.; Mi, C.; Zhao, L., and Lam, S. (eds.), Global Topics and New Trends in Coastal Research: Port, Coastal and Ocean Engineering. Journal of Coastal Research, Special Issue No. 103, pp. 521–525. Coconut Creek (Florida), ISSN 0749-0208. With the globalization of the world economy and the acceleration of urbanization in China, the spatial pattern of provinces and cities is changing with each passing day. This essay analyzes the evolution of spatial pattern based on accessibility in J province, an economically developed city in the Yangtze river delta economic belt of China, firstly establishes a measure model of urban accessibility, and then evaluates the spatial relative pattern characteristics of this province. After the empirical analysis found that the southern province of high-strength contacts significantly more than the northern parts of the city space, high strength and space contact center of gravity to the southeast coastal areas in city. According to the city space contact membership change, we found that J province's southern and northern city development level difference is significant. The research of this paper can provide some guidance for the spatial pattern adjustment of J province, promote the urbanization process of this region, and provide references for regional traffic layout. [ABSTRACT FROM AUTHOR]

Since the implementation of the great western development strategy in 2000, the ecological environment in the western region of China has been significantly improved. In order to explore the temporal and spatial characteristics of vegetation coverage in the western region, this paper adopted the method of Maximum Value Composite (MVC) to obtain the mean Normalized Difference Vegetation Index (NDVI) of vegetation on the basis of the Moderate-resolution Imaging Spector audiometer (MODIS) data of 2000/2005/2010/2015/2018. Thereafter, the spatio-temporal differentiation characteristics of vegetation in western China were analyzed. The results show that: (1) According to the time characteristics of vegetation coverage in the western region, the average annual NDVI value of vegetation coverage in the growing season in the western region fluctuated between 0.12 and 0.15, among which that of 2000 to 2010 fluctuated more greatly but did not show obvious change trend. (2) Based on Sen trend and Mann-Kendall test analysis, the area of vegetation coverage improvement in the western region from 2000 to 2018 was larger than that of significant vegetation degradation. (3) From the perspective of global autocorrelation coefficient, Moran's I values were all positive from 2000 to 2018, which indicates that the vegetation coverage in the west showed strong positive autocorrelation in each period. According to the average value and coefficient of variation of vegetation coverage, the vegetation coverage was lower in 2000, its internal variation was smaller, and the vegetation coverage increased with time. According to the local spatial autocorrelation analysis, the vegetation coverage levels in different regions varied greatly. (4) The standard deviation ellipse method was used to study the spatial distribution and directional transformation of vegetation. It makes the result more intuitive, and the three levels of gravity center shift, direction shift, and angle shift were considered: the vegetation growth condition in the spatial aggregation area improved in 2015; the standard deviation ellipses in 2000 and 2018 overlapped and shifted eastward, which indicates that the vegetation coverage conditions in the two years were similar and got ameliorated. [ABSTRACT FROM AUTHOR]