Coastal wetlands are rapidly disappearing worldwide, which is posing a substantial threat to the integrity of coastal ecosystems. In addition to the direct area reduction caused by reclamation, coastal wetlands experience natural changes due to sediment transport in coastal regions. Arguably, the reclamation rates must be less than the net accretion rate to guarantee the restoration of coastal wetlands. By applying an automatic and replicable shoreline algorithm to all available Landsat imagery from 1984 to 2015 using the Google Earth Engine Cloud Platform, we developed distribution maps of coastal wetlands and reclamation in China's Yellow Sea (CYS) at 4‐ or 5‐year intervals. In addition, we divided coastal wetlands into saltmarshes and mudflats and analysed their trends separately. Over the past 30 years, the area of coastal wetlands decreased by 53% (from 6,463 to 3,036 km2), including a 67% decrease in saltmarshes (from 1,471 to 489 km2) and a 49% decrease in mudflats (from 4,992 to 2,547 km2). Meanwhile, the reclaimed area was 7,696 km2 (including 1,276 km2 of saltmarshes and 3,002 km2 of mudflats), which exceeded the area of newly formed coastal wetlands (852 km2). The natural state of mudflats gradually changed from accretion to erosion, but without considering the natural state of coastal wetlands, reclamation will continue at a high rate in CYS according to China's national marine functional zoning (MFZ) for 2010–2020. In view of their important ecological services, there is an urgent need to revise the national MFZ to achieve ‘no net loss’ of coastal wetlands.
Phase diagrams reflect the possible kinetic routes and guide various applications such as the designed assembly and synthesis of functional materials. Two-dimensional (2D) materials have been a focus of ongoing research due to their wide applications; therefore, researchers are highly motivated to discover the general principles that control the assembly of such materials. In this study, we map the 2D phase diagrams of short-and long-range attractive colloids at single-particle resolution by video microscopy. Phase boundaries, including (meta)critical or triple points and corresponding real-space configurations, are precisely specified. Profiles of 2D phase diagrams with attractive interactions resemble their 3D counterparts. For short-range systems, by measuring the deepest achievable supercooled states on the phase diagram, a "crater" structure surrounding the metastable fluid-fluid critical point indicates an enhanced nucleation rate within the crater and further suggests a local minimum of the free-energy barrier for crystallization in this area. During a dense fluid-mediated two-step crystallization process, we observe that multiple crystallites could form within a single dense fluid cluster, partly due to its highly amorphous shape. This highly amorphous shape is found for all observed well-developed dense fluid clusters. It is a supplement to the multistep nucleation process. For long-range systems, equilibrium vapor-liquid coexistence is observed, which paves the way for the exploration of critical behaviors. Rigidity percolation of crystallites, and bulk fluid-solid coexistence which provide clear evidence of a possible first-order transition for 2D melting, are observed for both systems. Our experiments reveal the general features of phase behaviors shared by 2D attractive systems including graphene, protein membranes, and adsorbed nanocrystals.
Abstract:The purpose of this study is to propose a GIS-based mechanism for diagnosing karst rocky desertification (KRD) ecosystem health. Using the Huajiang Demonstration Area in Guizhou Province as a case study, this research offers a multi-factor indicator system for diagnosing KRD ecosystem health. A set of geologic, environmental, and socio-economic health indicators were developed based on remote sensing images from field-investigation, hydrological, and meteorological monitoring data. With the use of grid GIS technology, this study gives an indicator for diagnosing the spatial expression of desertification at a 5 m × 5 m grid scale. Using spatial overlaying technology based on grid data, the temporal and spatial dynamics of ecosystem health in the Huajiang Demonstration Area were tracked over a 10 year time span. The results of the analysis indicate that ecosystem health in the Huajiang Demonstration Area varies regionally, and has overall improved over time. The proportion of healthy area increased from 3.7% in 2000 to 8.2% in 2010. However, unhealthy and middle-health areas still accounted for 78.7% of the total area by 2010. The most obvious improvement of ecosystem health was in an area where comprehensive control measures for curbing KRD were implemented. These results suggest that comprehensive control of KRD can effectively mitigate ecosystem deterioration and improve ecosystem health in karst regions of South China.
Wireless sensor-actuator networks (WSANs) are gaining momentum in industrial process automation as a communication infrastructure for lowering deployment and maintenance costs. In traditional wireless control systems the plant controller and the network manager operate in isolation, which ignore the signi cant in uence of network reliability on plant control performance. To enhance the dependability of industrial wireless control, we propose a holistic cyber-physical management framework that employs run-time coordination between the plant control and network management. Our design includes a holistic controller that generates actuation signals to physical plants and recon gures the WSAN to maintain desired control performance while saving wireless resources. As a concrete example of holistic control, we design a holistic manager that dynamically recon gures the number of transmissions in the WSAN based on online observations of physical and cyber variables. We have implemented the holistic management framework in the Wireless Cyber-Physical Simulator (WCPS). A systematic case study has been presented based on two 5-state plants sharing a 16-node WSAN. Simulation results show that the holistic management design has signi cantly enhanced the resilience of the system against both wireless interferences and physical disturbances, while e ectively reducing the number of wireless transmissions. With the adoption of industrial wireless standards such asWirelessHART [15] and ISA100 [37], wireless sensoractuator networks (WSANs) are being deployed in process industries world wide. However, existing WSAN in process industries are usually used for monitoring applications. ere remain signi cant challenges in supporting feedback control systems over WSAN due to concerns about dependability of wireless control systems (WCS). A wireless control system (WCS) employs a WSAN as the communication infrastructure for one or more feedback control loops, where the sensors, controllers and actuators communicate over the WSAN. Despite considerable e orts to enhance the reliability of industrial WSAN, data loss is inevitable in open and hash operating environments, which may lead to severe degradation of control performance, or even system instabilities. A dependable WCS therefore must maintain system stability and acceptable control performance under both physical disturbance and wireless interference. A WCS is particularly vulnerable when signi cant data loss coincides with the plant experiencing a poor physical state. eFig. 1. Traditional design (le ) vs. holistic co-design (right) of wireless process control systems. challenge to utilize the WSAN for feedback control prevents the process industries from exploiting the full potential of wireless technologies, forcing plants to maintain extensive wired infrastructure despite the existence of the WSAN. erefore, it is critical to develop WCS that are dependable under challenging cyber and physical conditions. Although the control system performance is heavily in uenced by WSAN reliabilit...
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