Evolution In Different Regions Research Articles

Variations of Terrestrial Net Ecosystem Productivity in China Driven by Climate Change and Human Activity from 2010 to 2020

Net ecosystem productivity (NEP) plays an important role in the quantitative evaluation of carbon source/sinks in terrestrial ecosystems. This study used Theil–Sen median trend analysis, the Mann–Kendall method, and the Geodetector model to analyze the variation patterns and its dominant factors of NEP from 2010 to 2020. The results showed the following: (1) During 2010–2020, the spatial distribution of carbon sinks in China’s terrestrial ecosystems showed a pattern of high in the southeast and low in the northwest. The area with NEP < 0 accounted for 44.74% of the total area, while the area with NEP > 0 accounted for 55.26%. (2) The northwest region belonged to the significant carbon source, while the other regions belonged to significant carbon sinks. (3) The annual average NEP in different sub-regions showed an increasing trend. During 2010–2020, the overall NEP in China showed a trend in shifting from low-level to high-level, indicating that the NEP of terrestrial ecosystems in China increased during the past 11 years. (4) The NEP gravity center in Northeast China showed a trend in moving southward and then northward, while that of the NEP gravity center in East China showed a circular migration trend of ‘northwest-southwest–northeast–southeast’. The gravity center of NEP in Northwest China was moving northeastward. The migration trajectory of the NEP gravity center in Southwest China presented a “Z” shape. The change in the gravity center of NEP in the central and southern regions had a strong circuitous nature, and the overall trend was to migrate southward. (5) The combined actions of climate change and human activities were the main reason for the change in NEP in China’s terrestrial ecosystem from 2010 to 2020. (6) There were obvious differences in the dominant driving factors of NEP evolution in different regions and different periods in the past 40 years.

Electrochemical behavior and microstructural characterization of nano-SiC particles reinforced aluminum matrix composites prepared via friction stir processing

The present work aims to elucidate the mechanism of microstructural evolution in different regions of nano-SiC particles reinforced aluminum matrix composites prepared by friction stir processing (FSP) on its electrochemical behavior. Electron backscatter diffraction technique (EBSD) and transmission electron microscopy (TEM) were employed to characterize the microstructure evolution of stir zone (SZ), advancing side thermomechanically affected zone (AS-TMAZ), retreating side thermomechanically affected zone (RS-TMAZ) and base metal (BM). The electrochemical behaviors of the above zones were investigated using electrochemical tests. A homogeneous and fine microstructure is formed in SZ, not only the nano-SiC is homogeneously distributed within the grains with an average grain size of 3.5 μm, but also the recrystallized grains account for the highest percentage of 85 %. The potentiodynamic polarization curve indicates that the corrosion current densities of the BM, RS-TMAZ, AS-TMAZ and SZ are 0.89, 0.39, 0.85 and 0.36 μA/cm2, respectively, while the polarization impedances are 33.40, 51.42, 48.72 and 73.79 kΩ cm2, respectively. Combining the Nyquist and Bode plots analysis, the optimal electrochemical corrosion resistance is in SZ. The fine and homogeneous recrystallized grains in SZ significantly improve its electrochemical corrosion resistance. This is mainly ascribed to the increase in crystal defects as a result of the increase in grain boundaries, elevating the electron scattering. Simultaneously, the increase in high-energy state grain boundaries is beneficial to the rapid formation of a thicker passivation film.

Climate and sea-level fluctuations on the western coast of Bohai Bay during the 4.2 ka event: Multi-proxy evidence from the Nandagang area of Cangzhou, China

The 4.2 ka event was an important climatic event during the mid–late Holocene, with significant effects on the ecological environment and climatic evolution of different regions. Coastal wetlands, as a transitional ecosystem between land and sea, are sensitive to changes in climate and sea level; hence, research on coastal wetlands is important for reconstructing past climate and sea-level changes and for predicting future changes. However, little research has been conducted on the characteristics of the 4.2 ka event on the western coast of Bohai Bay in China. We analyzed the pollen assemblages (214 samples), grain size, and geochemical element contents of a mid–late Holocene sedimentary sequence from the Nandagang (NDG) wetland on Bohai Bay, with the chronology based on 13 AMS 14C dates. The results revealed the history of climate and sea-level changes on the western coast of Bohai Bay during the interval of 5000–3600 cal yr BP. High sedimentary arboreal pollen concentrations indicated that the NDG area had a relatively dense cover and humid climate during 5000–4450 cal yr BP. During the 380-year interval of 4450–4070 cal yr BP, corresponding to the 4.2 ka event, the decreased representation of arboreal pollen indicated a decrease in the regional forest cover and an arid climate. The internal structure of the 4.2 ka event recorded in core NDG showed a dry-wet-dry temporal structure during the intervals of 4450–4290 cal yr BP, 4290–4170 cal yr BP, and 4170–4070 cal yr BP, respectively, together with a relatively low sea level. Comparison of the relative sea level (RSL) record of the NDG wetland with similar records from other coastal regions in East Asia during the 4.2 ka event revealed contrasting trends. During 4070–3600 cal yr BP, the tree pollen concentration increased again, indicating that the forest vegetation coverage increased and the climate became wetter. Overall, our results suggest that the 4.2 ka event, as recorded in Bohai Bay, was related to the reduced influence of the western Pacific Ocean Warm Pool and the more frequent occurrence of the El Niño–Southern Oscillation.

Microstructure characteristics and failure mechanisms of hybrid manufacturing of FGH96 and IC10 bimetal component using laser directed energy deposition

Hybrid manufacturing technology combines the cost advantage of traditional manufacturing with the flexibility benefit of additive manufacturing, thus providing an effective solution for creating gradient components. In this work, we deposit IC10 alloy powders on the FGH96 hot isostatic pressing substrates to prepare nickel-based gradient materials. A detailed analysis of the microstructural evolution in different regions is provided. The influence of thermal cycles on the heat-affected zone (HAZ) causes the γ′ phase to transform from a multimodal structure formed by hot isostatic pressing to a uniform spherical shape. The grain morphology changes from the ultrafine equiaxed grains of the substrate to fine equiaxed grains in the HAZ, then transforms into fine columnar grains in the gradient region, and finally changes to coarse columnar grains in the deposited zone. Moreover, the influence of grain orientation on the ability of epitaxial growth is investigated, and a grain orientation-dependent growth model is developed to predict the growth direction of columnar grains in the deposited layer. Such a non-uniform microstructure results in mechanical performance, including hardness and tensile strength, with distinctive heterogeneity along the building direction. The hybrid manufactured sample with higher yield strength than the pure alloys was primarily influenced by factors such as grain sizes, the sizes and distributions of the γ′ phases, as well as dislocation densities. However, due to the liquation crack in HAZ, the tensile elongation of the hybrid manufactured sample is lower than the pure alloy.

Finite element modelling and microstructural correlation of hot forged Al-Zn-Mg-Cu alloy (T6) using DEFORM-3D

Thermomechanical processing is a globally practised method for upgraded microstructural and mechanical characteristics. But the varying strain during thermomechanical processing results in a varying microstructural characteristic throughout the specimen. Thus understanding the impact of strain and microstructural evolution in different regions with a deformed specimen is vital. The presented study discusses the finite element modelling of hot forged Al-Zn-Mg-Cu alloy mapped with microstructural evolution in different regions at an optimum working condition of 450 °C-0.001 s−1. The finite element analysis of the deformed specimens in the optimum working region has indicated a large effective strain variation (0 to 1.75) throughout the deformed specimens. The effective strain distribution delineated very high strain values at the edges and least on the centre region (cross-sectional area). The FEM simulation also indicated an increased chance of damage near the edges of the specimens. Further progressing within the deformed specimen, the effective strain increased towards the specimen's core. The microstructural correlation using EBSD IPF analysis indicated the high angle grain boundary (HAGB) fraction of 62% in the centre region and 50.5% in the longitudinal ends of the specimen. The GOS map indicated a dominantly recrystallized microstructure. A higher extent of DRX was observed in the centre region (93%) compared to the end region (78%). The microstructural evolution is due to cDRX, and the microstructural evolution is well correlated with the strain variation.

(Online First)Applying high-resolution visible imagery to satellite melt pond fraction retrieval: A neural network approach

During summer, melt ponds have a significant influence on Arctic sea-ice albedo. The melt pond fraction (MPF) also has the ability to forecast the Arctic sea-ice in a certain period. It is important to retrieve accurate melt pond fraction (MPF) from satellite data for Arctic research. This paper proposes a satellite MPF retrieval model based on the multi-layer neural network, named MPF-NN. Our model uses multi-spectral satellite data as model input and MPF information from multi-site and multi-period visible imagery as prior knowledge for modeling. It can effectively model melt ponds evolution of different regions and periods over the Arctic. Evaluation results show that the MPF retrieved from MODIS data using the proposed model has an RMSE of 3.91% and a correlation coefficient of 0.73. The seasonal distribution of MPF is also consistent with previous results.

Comparative study on the formability and microstructure evolution of different tempered Al–Cu–Li alloy sheets during room and cryogenic temperature forming process

High strength aluminum alloy sheets with excellent formability are necessary for the successful fabrication of complex-shaped components in order to prevent cracking during the forming process. To address this issue, this study investigated the formability of annealed (O) and water-quenched (WQ) Al–Cu–Li alloys at both room and cryogenic temperatures. Our results reveal a significant increase in the forming limit curve, with a 40% enhancement observed as the forming temperature decreased from 298 K to 113 K. Additionally, a 30% increase in formability was observed when transitioning from the O temper to the WQ temper. Thickness measurements reveal that WQ pre-treatment and cryogenic forming promoted continuous work hardening, thus improving deformation homogeneity. The mechanism responsible for the higher work hardening ability was elucidated by examining the microstructure evolution in different regions of the components. The results show that coarse particles in the O tempered alloys accelerated cross slip, resulting in the formation of recovered microstructures (i.e., dislocation cells and Cube texture) while simultaneously hindering dislocation movement and inducing local stress concentration. Conversely, for the WQ tempered alloy deformed at cryogenic temperature, the dissolution of particles and decreased stacking fault energy at low temperature suppressed cross slip and resulted in well-arranged dislocations within the slip system. Consequently, the combination of WQ pre-treatment and cryogenic forming demonstrates enhanced formability in high strength aluminum alloys, offering a novel method for manufacturing complex-shaped components.

Hot deformation behavior and new grain size model of hot extruded FGH4096 superalloy during hot compression

The deformation behavior and grain size models of hot extruded (HEXed) FGH4096 superalloy at the temperature of 1040–1130 ℃ and the strain rate of 0.001–1 s−1 were investigated by hot compression. On the basis of the corrected flow stress curves, the constitutive equation considering the strain variable and hot working maps were established. The dynamic recrystallization (DRX) behaviors and microstructure evolution in different regions in hot working map superimposing the hot working instability maps were also analyzed. Discontinuous dynamic recrystallization (DDRX) occurs simultaneously with continuous dynamic recrystallization (CDRX) in the HEXed FGH4096 superalloy at low temperature, while only DDRX is activated at high deformation temperature. The wedge cracks, voids, and intergranular cracks are the main causes of flow instability. An optimal hot working window of deformation temperature = 1102–1130 ℃ and strain rate = 10−1.26–10−0 s−1 was obtained by combining the hot working maps and microstructure evolution. An established new grain size model by extending the Z parameter can predict the average grain size more accurately.

Tectonic evolution of the Qinling Orogenic Belt, Central China – new evidence from geochemical, zircon (U-pb) geochronology and HF isotopes

The paper deals with a review of tectonic evolution in different regions of China with the help of different techniques and models. Tectonic evolution shows that in the shallow layers of China the structural impact is not solid, and huge structural zones are deficient within the list and incline zones where the principal wretchedness and delicate slant zones framed. The Qinling Orogenic Belt (QOB) situated between the North China Craton (NCC) and the Yangtze Craton (YZC) is made from the Northern Qinling Belt (NQB) and the Southern Qinling Belt (SQB). The Hf isotopic creations of zircons from the different rocks recommend that the NQB most likely created on the cellar of the southern NCC. The stones in the SQB show zircon age spectra and Hf-isotope structures like those in the northern YZC, recommending a nearby proclivity. We thusly decipher the SQB to have created on the cellar of the northern YZC. Incorporating the new information in this investigation with those from past works, we propose another structural model for the development and advancement of the QOB during late Mesoproterozoic to early Paleozoic including the accompanying significant occasions: (1) Late Mesoproterozoic to early Neoproterozoic (Grenvillian) toward the north subduction of the Songshugou Ocean; Early-center Neoproterozoic (870-800 Ma) bidirectional subduction and impact; Middle Neoproterozoic (∼800-710 Ma) post-crash expansion; Middle-late Neoproterozoic (710-600 Ma) inside plate augmentation; Late Neoproterozoic-early Paleozoic (600-520 Ma) opening of the Shangdan Ocean; and Early Paleozoic (520-420 Ma) subduction-crash. We accordingly follow in any event two unmistakable Wilson cycles in the QOB.

Effect of heterogeneous microstructure on the mechanical properties and deformation behavior of rotating backward extruded ZK61 alloy

The rotating backward extrusion (RBE), as a novel severe plastic deformation process, has prosperous industrial application prospect. However, the capability and potential of the RBE process to prepare samples with different heterogeneous microstructures has not attracted attention. In order to explore the relationship between different microstructural compositions and mechanical properties of tubular component prepared by RBE process, the grain size distribution, grain orientation and mechanical properties of a ZK61 Mg alloy tubular component prepared by the RBE process in different regions (along the wall thickness and height directions) were investigated. The results show that the microstructure evolution in different regions is closely related to the equivalent strain distribution. The grain refinement effect is positively correlated with the equivalent strain, but a higher applied strain also leads to a strong basal orientation and high residual stress. Furthermore, the tensile deformation behavior of different samples revealed that samples with preferentially microstructural compositions (volume fraction of fine grains: 40∼60%) have better work hardening capability and strong-toughness synergy. This is mainly attributed to more effective coordinated deformation between different regions (fine grain region and coarse grain region), which can relieve local stress concentration and accommodate more dislocations. In contrast, an excessively high volume fraction of fine grains in samples limits their ability to store dislocations that saturate rapidly with increasing strain, while an excessively low volume fraction of fine grains in samples has difficulty accommodating the high density dislocations transferred from the coarse grain region, resulting in accumulation of high local stress at the interfaces of different regions (fine grain region and coarse grain region). Both of the above can deteriorate the work hardening ability and comprehensive performance, causing the sample to fail before sufficient work hardening occurs.

Using Multi-Platform Satellite Observations to Study the Atmospheric Evolution of Brown Carbon in Siberian Biomass Burning Plumes

A bulk of evidence from in situ observations and lab experiments suggests that brown carbon (light-absorbing organic compounds in particles) can provide a significant yet highly variable contribution to the overall light absorption by aerosol particles from biomass burning (BB). Partly stemming from the complexity of the atmospheric evolution of organic aerosol (OA), the variability in brown carbon (BrC) absorption makes it difficult to partition the radiative effects of BrC and black carbon (BC) in atmospheric and climate models; as such, there are calls for satellite-based methods that could provide a statistical characterization of BrC absorption and its evolution in different regions of the world, especially in remote BB regions, such as Siberia. This study examined the feasibility of the statistical characterization of the evolution of BrC absorption and related parameters of BB aerosol in smoke plumes from intense wildfires in Siberia through the analysis of a combination of data from three satellite instruments: OMI (Ozone Monitoring Instrument), MISR (Multi-Angle Imaging SpectroRadiometer), and MODIS (Moderate Resolution Imaging Spectroradiometer). Using a Monte Carlo method, which related the satellite retrievals of the absorption and extinction aerosol optical depths to Mie theory calculations of the optical properties of BB aerosol, we found that the BrC absorption, as well as the imaginary refractive index for the OA, decreased significantly in Siberian BB smoke plumes during about 30 h of the daylight evolution, nevertheless remaining considerable until at least 70 h of the daylight evolution. Overall, the study indicated that the analysis of multi-platform satellite observations of BB plumes can provide useful insights into the atmospheric evolution of BrC absorption and the partitioning of BrC and BC contributions to the total light absorption by BB aerosol.

Seawater Intrusion-Retreat Processes and Groundwater Evolution in Intruded Coastal Aquifers with Land Reclamation: A Case Study of Eastern Jiangsu, China

Abstract The hydrogeochemical analysis and numerical simulation were conducted to explore the impact of land reclamation on submarine groundwater discharge and groundwater evolution in the seawater intrusion-retreat processes in eastern Jiangsu, China. The hydrogeochemical results indicated that the origin of salt in most groundwater is saltwater mixing, and weathering-dissolution of minerals enriches the salt in fresh groundwater. The evolution path of coastal groundwater in Jiangsu is Ca-Na-HCO3-Cl → Ca-Na-Cl-HCO3 → Na-Ca-Cl-HCO3 → Na-Mg-HCO3 → Na-Mg-HCO3-Cl → Na-Cl-HCO3 → Na-Cl, and the difference in groundwater evolution in different regions is obvious. The numerical simulation revealed that the land reclamation has blocked groundwater exchange and restrained the seawater intrusion. The sensitive analysis indicated that the permeability and the slope of the land reclamation have dominated the salinity distribution. And the aquifer heterogeneity promotes groundwater evolution and leads to the irregular salinity distribution of the groundwater. Moreover, the groundwater evolution in the shallow aquifer with the land reclamation shows that the residual seawater is gradually desalinating and discharged into the sea. The land reclamation is salinized by saltwater discharge and seawater intrusion together and then subsides into a stable saltwater wedge. The groundwater salinity distribution in Jiangsu is not fit seawater intrusion, which is caused by the coastline changes due to anthropogenic land reclamation and natural activities.

Grain size and misorientation evolution in linear friction welding of additively manufactured IN718 to forged superalloy AD730™

Selective Laser Melted (SLM) Inconel718 (IN718) superalloy was linear friction welded (LFWed) to forged AD730™ Nickel-based superalloy. Successful joints free of micro-porosity, micro-cracking, and oxides were obtained. Microstructure variations across the weld line developed during LFW were examined using different techniques, including laser confocal microscopy, scanning electron microscopy, energy dispersive spectroscopy (EDS) and electron backscatter diffraction (EBSD). The microstructure was also evaluated, particularly in terms of Grain size and misorientation changes were determined and correlated with microhardness evolution in different regions of the weld joint. The characteristics of the microstructure on both sides of the weld joint was analyzed and related to the deformation and temperature paths imposed during the LFW process. Dynamic recrystallization (DRX) occurred on both sides of the dissimilar weld line and it was found that Discontinuous DRX (DDRX) and Continuous DRX (CDRX) took place in the WZ and in the TMAZ, respectively. In order to study the influence of the starting microstructure in the LFW experiments, LFW of a homogenized SLM IN718 sample was analyzed and compared with the non-homogenized sample. A clear change in the size and grain misorientation levels of the heat and thermomechanical affected zones were observed between the two conditions. The differences were related to a greater degree of strain induced in homogenized sample and the increasing effect of the solid solution strengthening mechanism caused by a partial dissolution of the second-phase strengthening particles in the matrix.

A Method for Extracting Some Key Terrain Features from Shaded Relief of Digital Terrain Models

Detection of terrain features (ridges, spurs, cliffs, and peaks) is a basic research topic in digital elevation model (DEM) analysis and is essential for learning about factors that influence terrain surfaces, such as geologic structures and geomorphologic processes. Detection of terrain features based on general geomorphometry is challenging and has a high degree of uncertainty, mostly due to a variety of controlling factors on surface evolution in different regions. Currently, there are different computational techniques for obtaining detailed information about terrain features using DEM analysis. One of the most common techniques is numerically identifying or classifying terrain elements where regional topologies of the land surface are constructed by using DEMs or by combining derivatives of DEM. The main drawbacks of these techniques are that they cannot differentiate between ridges, spurs, and cliffs, or result in a high degree of false positives when detecting spur lines. In this paper, we propose a new method for automatically detecting terrain features such as ridges, spurs, cliffs, and peaks, using shaded relief by controlling altitude and azimuth of illumination sources on both smooth and rough surfaces. In our proposed method, we use edge detection filters based on azimuth angle on shaded relief to identify specific terrain features. Results show that the proposed method performs similar to or in some cases better (when detecting spurs than current terrain features detection methods, such as geomorphon, curvature, and probabilistic methods.

Inferring Tumor Proliferative Organization from Phylogenetic Tree Measures in a Computational Model.

We use a computational modeling approach to explore whether it is possible to infer a solid tumor's cellular proliferative hierarchy under the assumptions of the cancer stem cell hypothesis and neutral evolution. We work towards inferring the symmetric division probability for cancer stem cells, since this is believed to be a key driver of progression and therapeutic response. Motivated by the advent of multiregion sampling and resulting opportunities to infer tumor evolutionary history, we focus on a suite of statistical measures of the phylogenetic trees resulting from the tumor's evolution in different regions of parameter space and through time. We find strikingly different patterns in these measures for changing symmetric division probability which hinge on the inclusion of spatial constraints. These results give us a starting point to begin stratifying tumors by this biological parameter and also generate a number of actionable clinical and biological hypotheses regarding changes during therapy, and through tumor evolutionary time. [Cancer; evolution; phylogenetics.].

Effects of recent morphodynamic evolution on flood regimes in the Pearl River Delta

Both the river network and the regions outside the estuary mouths in the Pearl River Delta (PRD) of China experienced significant changes from 1999 to 2014. A validated hydrodynamic model across the entire PRD and adjacent regions outside the estuary mouths is employed to simulate both present (circa 2014) and past conditions (circa 1999). The total net water flux of the PRD decreased. The flow division of the West River is increasing, with values of 3.63% and 4.66% for the Makou and Denglongshan sections, respectively. The flood flow division of the North River is correspondingly decreasing. The value of the flood levels significantly decreased (more than 2 m) in the upper portion of the PRD, moderately decreased in the middle of the PRD (more than 1.1 m) and slightly decreased in the bottom part of the PRD (less than 0.22 m). In addition, the effects of morphodynamic evolution in different regions (i.e., the river network, coastline and bathymetry changes outside the estuary mouth) on floods are quantified. The results indicate that the decreased net water flux was caused by the increased channel’s capacity and the gentler water-level profile from the downcutting riverbed of the river network. The uneven morphodynamic evolution of the riverbed of the river network was primarily responsible for changes in the flood flow division in the PRD, and morphological evolution outside the estuary mouth was primarily responsible for reallocation within the outlets. The downcutting riverbed in the river network was primarily responsible for the lower flood levels in the upper and middle portion of the PRD. Reclamation seemed to have barely affected the flood level. The deepening bathymetry outside the estuary mouth was mainly responsible for the decrease in the flood level in the bottom portion of the PRD. The downcutting riverbed may decrease the stability of the riverbank, increasing the flood risk. The morphodynamic evolution of both the river network and the regions outside the estuary mouth should be considered to avoid unwanted side effects when designing local projects and flood mitigation strategies for the PRD.

Competitiveness and sustainable development in public services

Abstract The last years were of profound transformation in public services that knows more or less the challenge from the private sector. A second dimension of competitiveness for the public services staring from 2007 was the free access of the citizens to at least education and health services in European Union. The paper aims to show the evolution of the cohabitation of the public and private sectors on the services of public interest, their development and evolution in different regions. Identifying and highlighting the key issues in competitiveness and quality of the services provided, will give us the main lines for the further development and public policies that should be considered. Considering the cohesion policy of European Union, an analysis of the public and private sectors in public services in Romanian counties could drive us to a conclusion about the affordability and the quality of the services. Using the statistics it can be show the regional distribution of the service providers especially for education, health, water supply and other services. The integrated analysis we offer a global picture of the regional potential and development. Based on the findings the public decision makers could better set up the sectorial public policies and the public spending. Never the less, the European support could be also directed to increase the quality and efficiency of the public services.

Spatio-temporal evolution of the early-warning status of cultivated land and its driving factors: A case study of Heilongjiang Province, China

Scientific identification of the early-warning status in relation to cultivated land system security (CLSS) is essential for future food security and sustainable development. It is important to establish the early-warning status of cultivated land as it may signal forthcoming problems and even large-scale environmental catastrophes as an effective means to understand both the current status and future development trends of the CLSS. However, the systematic assessment of the early-warning of status of CLSS has not been previously been conducted at the municipal level, and an in-depth study and discussion of its fundamental driving factors is lacking. Thus, we introduce the biological immunity mechanism by way of analogy and demonstrate the feasibility of its application in the early-warning of CLSS. A novel conceptual early-warning index system is developed and this framework applied to 12 cities in Heilongjiang Province of northeast China using adopting fourteen possible indicators. The spatiotemporal evolution of the early-warning status had been explored over the period 1995–2014 using rescaled range (R/S) analysis. Furthermore, the fundamental factors of the early-warning were explored by establishing a rational panel data model. The results indicate that 1) CLSS early-warning status initially rose and then decreased over the last 20 years. 2) The severe level warning areas are mainly found in the southeast and west of the region, while the secure and relatively secure areas are mainly concentrated in the middle-north and southern areas. 3) The observed patterns indicate that, with the exception of Yichun and Suihua, the early-warning status of the province will develop in the future along the same lines as it did so historically. 4) The results of regression analysis indicate that rational panel data model construction should be verified so as not to produce pseudo-regression and that four main driving factors (natural population growth rate, agricultural waste load per unit area of cultivated land, natural disasters index, and industrial wastewater load per unit area of cultivated land) are significantly positively correlated with the early-warning status; one factor (forest cover) is negatively correlated. Policy-makers need to consider the key factors affecting the early-warning status of cultivated land and its spatiotemporal evolution in different regions to formulate appropriate measures in order to mitigate against future threats.

Effect of workpiece size on microstructure evolution of different regions for TA15 Ti-alloy isothermal near-β forging by local loading

The microstructure evolution and mechanical properties in different loading regions during isothermal near-β local forging were investigated using three TA15 Ti-alloy workpieces of different sizes, namely, a cylindrical sample, a quadrate billet, and a bulkhead component. Reasons for differences in the microstructure and mechanical properties were determined. Fine primary equiaxed α and clustered acicular secondary α were obtained for the small cylindrical sample, and the different loading regions exhibited good uniformity in microstructural morphology and size. Significant differences in microstructure existed between the first and second loading regions for the quadrate billet and bulkhead component, especially in the secondary lamellar α, which resulted in different mechanical properties. Specifically, coarse primary equiaxed α and straight and thin clustered lamellar α existed in the first loading region, and less coarse primary equiaxed α and thickened and globularized secondary lamellar α with short rod-like or equiaxed shape existed in the second loading region. The holding time and different cooling rates caused by the workpiece sizes resulted in differences in their primary equiaxed α and secondary lamellar α size. The combined effects of strain history, holding time, and cooling rate led to microstructural differences in different regions for the quadrate billet and bulkhead component, whereas the effect of strain history was reduced for the cylindrical sample because of the short holding time and fast cooling rate, and little difference existed between the first and second loading regions.

A model study of the effect of climate and sea-level change on the evolution of the Antarctic Ice Sheet from the Last Glacial Maximum to 2100

Due to a scarcity of observations and its long memory of uncertain past climate, the Antarctic Ice Sheet remains a largely unknown factor in the prediction of global sea level change. As the history of the ice sheet plays a key role in its future evolution, in this study we model the Antarctic Ice Sheet from the Last Glacial Maximum (21 kyr ago) until the year 2100 with the ice-dynamical model ANICE. We force the model with different temperature, surface mass balance and sea-level records to investigate the importance of these different aspects for the evolution of the ice sheet. Additionally, we compare the model output from 21 kyr ago until the present with observations to assess model performance in simulating the total grounded ice volume and the evolution of different regions of the Antarctic Ice Sheet. Although there are some clear limitations of the model, we conclude that sea-level change has driven the deglaciation of the ice sheet, whereas future temperature change and the history of the ice sheet are the primary cause of changes in ice volume in the future. We estimate the change in grounded ice volume between its maximum (around 15 kyr ago) and the present-day to be between 8.4 and 12.5 m sea-level equivalent and the contribution of the Antarctic Ice Sheet to the global mean sea level in 2100, with respect to 2000, to be −22 to 63 mm.