Effect of deformation parameters on the austenite dynamic recrystallization behavior of a eutectoid pearlite rail steel

Understandings of the effect of hot deformation parameters close to the practical production line on grain refinement are crucial for enhancing both the strength and toughness of future rail steels.In this work,the austenite dynamic recrystallization(DRX)behaviors of a eutectoid pearlite rail steel were studied using a thermo-mechanical simulator with hot deformation parameters frequently employed in rail production lines.The single-pass hot deformation results reveal that the prior austenite grain sizes(PAGSs)for samples with different deformation reductions decrease initially with an increase in deformation temperature.However,once the deformation temperature is beyond a certain threshold,the PAGSs start to increase.It can be attributed to the rise in DRX volume fraction and the increase of DRX grain with deformation temperature,respectively.Three-pass hot deformation results show that the accumulated strain generated in the first and second deformation passes can increase the extent of DRX.In the case of complete DRX,PAGS is predominantly determined by the deformation temperature of the final pass.It suggests a strategic approach during industrial production where part of the deformation reduction in low temperature range can be shifted to the medium temperature range to release rolling mill loads.

Dynamic mechanical properties and wave propagation of composite rock-mortar specimens based on SHPB tests

Filled inclusions in rock discontinuities play a key role in the mechanical characteristics of the rock and thereby influence the stability of rock engineering. In this study, a series of impact tests were performed using a split Hopkinson pressure bar system with high-speed photography to investigate the effect of interlayer strength on the wave propagation and fracturing process in composite rock-mortar specimens.The results indicate that the transmission coefficient, nominal dynamic strength, interlayer closure, and specific normal stiffness generally increase linearly with increasing interlayer stiffness. The cement mortar layer can serve as a buffer during the deformation of composite specimens. The digital images show that tensile cracks are typically initiated at the rock-mortar interface, propagate along the loading direction, and eventually result in a tensile failure regardless of the interlayer properties. However, when a relatively weaker layer is sandwiched between the rock matrix, an increasing amount of cement mortar is violently ejected and slight slabbing occurs near the rock-mortar interface.

CMIP6 Evaluation and Projection of Precipitation over Northern China:Further Investigation

Based on 20 models from phase 6 of the Coupled Model Intercomparison Project(CMIP6),this article explored possible reasons for differences in simulation biases and projected changes in precipitation in northern China among the allmodel ensemble(AMME),“highest-ranked”model ensemble(BMME),and“lowest-ranked”model ensemble(WMME),from the perspective of atmospheric circulations and moisture budgets.The results show that the BMME and AMME reproduce the East Asian winter circulations better than the WMME.Compared with the AMME and WMME,the BMME reduces the overestimation of evaporation,thereby improving the simulation of winter precipitation.The three ensemble simulated biases for the East Asian summer circulations are generally similar,characterized by a stronger zonal pressure gradient between the mid-latitudes of the North Pacific and East Asia and a northward displacement of the East Asian westerly jet.However,the simulated vertical moisture advection is improved in the BMME,contributing to the slightly higher performance of the BMME than the AMME and WMME on summer precipitation in North and Northeast China.Compared to the AMME and WMME,the BMME projects larger increases in precipitation in northern China during both seasons by the end of the 21st century under the Shared Socioeconomic Pathway 5-8.5(SSP5-8.5).One of the reasons is that the increase in evaporation projected by the BMME is larger.The projection of a greater dynamic contribution by the BMME also plays a role.In addition,larger changes in the nonlinear components in the BMME projection contribute to a larger increase in winter precipitation in northern China.

CMIP6 Evaluation and Projection of Temperature and Precipitation over China

This article evaluates the performance of 20 Coupled Model Intercomparison Project phase 6(CMIP6)models in simulating temperature and precipitation over China through comparisons with gridded observation data for the period of 1995–2014,with a focus on spatial patterns and interannual variability.The evaluations show that the CMIP6 models perform well in reproducing the climatological spatial distribution of temperature and precipitation,with better performance for temperature than for precipitation.Their interannual variability can also be reasonably captured by most models,however,poor performance is noted regarding the interannual variability of winter precipitation.Based on the comprehensive performance for the above two factors,the“highest-ranked”models are selected as an ensemble(BMME).The BMME outperforms the ensemble of all models(AMME)in simulating annual and winter temperature and precipitation,particularly for those subregions with complex terrain but it shows little improvement for summer temperature and precipitation.The AMME and BMME projections indicate annual increases for both temperature and precipitation across China by the end of the 21st century,with larger increases under the scenario of the Shared Socioeconomic Pathway 5/Representative Concentration Pathway 8.5(SSP585)than under scenario of the Shared Socioeconomic Pathway 2/Representative Concentration Pathway 4.5(SSP245).The greatest increases of annual temperature are projected for higher latitudes and higher elevations and the largest percentage-based increases in annual precipitation are projected to occur in northern and western China,especially under SSP585.However,the BMME,which generally performs better in these regions,projects lower changes in annual temperature and larger variations in annual precipitation when compared to the AMME projections.

Performance of RegCM4 over Major River Basins in China

A long-term simulation for the period 1990–2010 is conducted with the latest version of the International Centre for Theoretical Physics＇ Regional Climate Model（RegCM4）, driven by ERA-Interim boundary conditions at a grid spacing of 25 km. The Community Land Model（CLM） is used to describe land surface processes, with updates in the surface parameters,including the land cover and surface emissivity. The simulation is compared against observations to evaluate the model performance in reproducing the present day climatology and interannual variability over the 10 main river basins in China,with focus on surface air temperature and precipitation. Temperature and precipitation from the ERA-Interim reanalysis are also considered in the model assessment. Results show that the model reproduces the present day climatology over China and its main river basins, with better performances in June–July–August compared to December–January–February（DJF）.In DJF, we find a warm bias at high latitudes, underestimated precipitation in the south, and overestimated precipitation in the north. The model in general captures the observed interannual variability, with greater skill for temperature. We also find an underestimation of heavy precipitation events in eastern China, and an underestimation of consecutive dry days in northern China and the Tibetan Plateau. Similar biases for both mean climatology and extremes are found in the ERA-Interim reanalysis, indicating the difficulties for climate models in simulating extreme monsoon climate events over East Asia.

Influence of Human Activities on Wintertime Haze-Related Meteorological Conditions over the Jing–Jin–Ji Region

This work analyzes and discusses the influence of human activities on the meteorological conditions related to winter haze events in Beijing,Tianjin,and Hebei(i.e.,the Jing-Jin-Ji region)during 1961-2016,using the results of two numerical simulation experiments based on the Community Atmosphere Model version 5.1.1(http://www.cesm.ucar.edu/models/cesm1.0/cam/docs/ug5_1_1/book1.html)used in the international Climate Variability and Predictability Programme(CLIVAR)Climate of the 20th Century Detection and Attribution Project(C20C+D&A).The results show that,under the influence of human activities,the changes in dynamical and thermal meteorological conditions related to winter haze events in the Jing–Jin–Ji region are conducive to the formation and accumulation of haze,and prevent the diffusion of pollutants.The dynamical conditions mainly include the obvious weakening of the East Asian winter monsoon(EAWM)and the enhancement of the near-surface anomalous southerly wind.The thermal conditions include the obvious increase in surface temperature,and the enhancement of water vapor transport and near-surface inversion.The relative contribution of dynamical and thermal conditions to the variation of haze days in the Jing-Jin-Ji region is analyzed using statistical methods.The results show that the contribution of human activities to the increase of haze days in the Jing-Jin-Ji region is greater than that of natural forcing for the study period.To be specific,the dynamical meteorological factors contribute more to the haze days than the thermal meteorological factors.The contribution of thermal meteorological factors is basically the same in both scenarios.

Feature Extraction to Polar Image

Some algorithms of feature extraction in existing literature studied for image processing was the gray image with one-dimensional parameter. However, some feature points’ extraction for three-dimensional color of polar image, such as the color edge extraction, inflection points, and so on, was urgently to be solved a polar color problem. For achieving quickly and accurately the color feature extraction to polar image, this paper proposed a similar region of color algorithm. The algorithm was compared to polar image, and the effect to color extraction was also described by the combination of the proposed and existing algorithms. Moreover, this paper gave the comparison of the proposed algorithm and an existing classical algorithm to extraction of color feature. These researches in this paper provided a powerful tool for polar image classification, color feature segmentation, precise recognition, and so on.

Nutritional Status of Students in Poverty-Stricken Areas

Objective: In this study, we aim to understand the nutritional status of students in poverty-stricken areas of Inner Mongolia and their links with academic performance and to provide a scientific basis for the designated nutrition intervention and health education in students. Methods: In Zhalaiteqi County students’ physical health survey data and learning achievement scores from 2012 to 2013 were selected as research data, and the nutritional status of the students was judged by statistical analysis of physical data. Results: The malnutrition rate was 22.21%, the overweight rate was 6.0%, and the obesity rate was 3.81% in 2012. The detection rate of the male normal group was 80.22%, and the detection rate of the female normal group was 75.63%. The difference was statistically significant (χ2 = 27.036 P Conclusion: The nutritional status of students in poverty-stricken areas in Inner Mongolia cannot be neglected. Weight loss and obesity have a negative impact on students’ academic performance. Effective measures should be taken to control the present situation.

Application of Fuzzy Automata Decision-Making System in Target Control

In order to perform better in target control, this paper proposed a decision-making system method based on fuzzy automata. The decision-making system first preprocessed the signal and then performed a two-level decision on the target to achieve optimal control. The system consisted of four parts: signal preprocessing, contrast decision-making, comprehensive judgment of decision-making and decision-making result. These decision algorithms in target control were given. A concrete application of this decision-making system in target control was described. Being compared with other existing methods, this paper used both global features and local features of target, and used the decision-making system of fuzzy automata for the target control. Simulation results showed that the control effect based on the decision-making system was better than that of the other existing methods. Not only it was faster, but also its correct control rate was higher to be 95.18% for the target control. This research on the control system not only developed the FA theory, but also strengthened its application scope in the field of control engineering.

Application of Union of Fuzzy Automata on Target Tracking

For better applications of fuzzy automata on target tracking, this paper presents an associated method of fuzzy automata by discussing the relation between fuzzy automata. The equivalence is mainly discussed regarding these fuzzy automata. The target tracking based on the associated method of fuzzy automata is given. Moreover, the simulation result shows that the associated method is better than single fuzzy automaton relatively. The development of these researches in this paper in turn can quicken the applications of the fuzzy automata in various fields.

Application of FRS on Target Recognition

In order to let machine better imitate thinking method of people to perform recognition and classification for fuzzy and uncertain thing, this paper puts forward a fuzzy and rough association method to deal with the problem. However, the application of fuzzy rough sets (FRS) will be introduced mainly on pattern recognition. Some related theories on FRS would be discussed, and some fuzzy rough mathematical methods on pattern-recognition will be given. Then, concrete applications of FRS on image processing and recognition will be introduced. Simulation result signifies that this fuzzy and rough association method is not only fast but also closer to nature attribute of thing for processing and recognizing image by comparing with the single neural network and other recognition device. The recognition rate is about 95.78%.

Temperature field characteristics of CF/PEEK thermoplastic composites formed by automated fiber placement using hot gas torch with slit structure nozzle

In-situ consolidation forming of high-performance thermoplastic composites by Automated Fiber Placement(AFP)is of significant interest in aerospace.During the laying process,the heating temperature has a great influence on the quality of the formed components.A threedimensional heat transfer finite element model of Carbon Fiber(CF)/Polyether Ether Ketone(PEEK)heated by Slit Structure Nozzle Hot Gas Torch(SSNHGT)assisted AFP is proposed.The influence of gas flow rate,heat transfer distance,and laying speed on heating temperature is analysed.The results show that the overall temperature increases and then decreases as the gas flow rate increases.With the increase in heat transfer distance and laying speed,the overall temperature decreases.Meanwhile,the gas flow rate has the greatest influence on the temperature of CF/PEEK being heated,followed by the laying speed and finally the heat transfer distance.Furthermore,the model can also be extended to other fiber-reinforced polymer composites formed by hot gas torch assisted AFP,which can guide the optimization of process parameters for subsequent heating temperature control.

Effect of variable-angle trajectory structure on mechanical performance of CF/PEEK laminates made by robotic fiber placement

In comparison to the traditional fixed-angle trajectory,the variable-angle trajectory has a greater design space.However,it is a challenge to determine which common design curve structure is the most effective for improving mechanical performance.This work explores the effects of various design curves such as fixed-angle curve,linear curve,arc curve,sine curve,Bezier curve,and cubic polynomial curve trajectories on mechanical performance of laminates,including vibration modal performance and buckling performance.Genetic algorithm and improved NSGA-II algorithm are then used to optimize various curve structures.The results are confirmed utilizing thermoplastic Carbon Fiber(CF)/Polyether-Ether-Ketone(PEEK)laminates made by robotic fiber placement experiments.The relationship model between different mechanical performance and curve design variables is established.The optimization of variable-angle structure with mechanical properties as input variables is achieved.Meanwhile,a full-process angle-variable laying software platform from trajectory planning(CAD),trajectory optimization to manufacturing(CAM)is developed for facilitating the fiber placement application.

3D bioprinting of tumor models and potential applications

Cancer is the most common cause of human mortality and has created an unbridgeable health gap due to its unrestrained aberrant proliferation,rapid growth,metastasis,and high heterogeneity.Conventional two-dimensional cell culture and animal models for tumor diagnostic and therapeutic studies have extremely low clinical translation rates due to their intrinsic limitations.Appropriate tumor models are therefore required for cancer research.Engineered human three-dimensional(3D)cancer models stand out for their ability to better replicate the spatial organization,cellular resources,and microenvironmental features(e.g.,hypoxia,necrosis,and delayed proliferation)of actual human tumors.Further,the fabrication of these models can be achieved by an emerging technology known as 3D bioprinting,which allows for the fabrication of living structures by precisely regulating the spatial distribution of cells,biomolecules,and matrix components.The aim of this paper is to review the current technologies and bioinks associated with 3D bioprinted cancer models for glioma,breast,liver,intestinal,cervical,ovarian,and neuroblastoma,as well as,advances in the applications of 3D bioprinted-based tumor models in the fields of tumor microenvironment,tumor vascularization,tumor stem cells,tumor resistance and therapeutic drug screening,tumorimmunotherapy,and precision medicine.

中国及其屏障区柯本气候分类的RegCM4集合预估

区域气候模式RegCM4分别在CSIRO-Mk3-6-0、EC-EARTH、HadGEM2-ES、MPI-ESM-MR和NorESM1-M五个全球气候模式驱动下,进行了水平分辨率为25 km的东亚区域气候变化试验.基于该试验的集合结果,在对结果进行误差订正的基础上,本文预估了RCP4.5温室气体排放路径下21世纪末期(2069~2098年)中国及其国家生态安全屏障区的柯本-特里瓦沙气候分类的变化.结果表明,相比当代(1981~2010年),21世纪末期中国的气候型发生变化的面积比例为22%,其中青藏高原和秦岭-淮河一带变化明显,青藏高原地区苔原气候(FT)的范围大幅度收缩,中国半干旱(BS)和冬干温暖气候(Cw)的范围扩展,其中BS面积较当代扩张近20%;国家生态安全屏障区的气候型变化更明显一些,总面积的24%将发生改变,其中以青藏高原和川滇-黄土高原的变化最大(40%左右),东北森林带次之,气候变化将导致这些地区的生态脆弱性加大.

Fractal Design Boosts Extrusion-Based 3D Printing of Bone-Mimicking Radial-Gradient Scaffolds

Although extrusion-based three-dimensional(EB-3D)printing technique has been widely used in the complex fabrication of bone tissue-engineered scaffolds,a natural bone-like radial-gradient scaffold by this processing method is of huge challenge and still unmet.Inspired by a typical fractal structure of Koch snowflake,for the first time,a fractal-like porous scaffold with a controllable hierarchical gradient in the radial direction is presented via fractal design and then implemented by EB-3D printing.This radial-gradient structure successfully mimics the radially gradual decrease in porosity of natural bone from cancellous bone to cortical bone.First,we create a design-to-fabrication workflow with embedding the graded data on basis of fractal design into digital processing to instruct the extrusion process of fractal-like scaffolds.Further,by a combination of suitable extruded inks,a series of bone-mimicking scaffolds with a 3-iteration fractal-like structure are fabricated to demonstrate their superiority,including radial porosity,mechanical property,and permeability.This study showcases a robust strategy to overcome the limitations of conventional EB-3D printers for the design and fabrication of functionally graded scaffolds,showing great potential in bone tissue engineering.

Improved decadal climate prediction in the North Atlantic using EnOI-assimilated initial condition

Decadal prediction experiments of Beijing Climate Center climate system model version 1.1 （BCC- CSM1.1） participated in Coupled Model Intercomparison Project Phase 5 （CMIPS） had poor skill in extratropics of the North Atlantic, the initialization of which was done by relaxing modeled ocean temperature to the Simple Ocean Data Assimilation （SODA） reanalysis data. This study aims to improve the prediction skill of this model by using the assimilation technique in the initialization. New ocean data are firstly generated by assimilating the sea surface temperature （SST） of the Hadley Centre Sea Ice and Sea Surface Temperature （HadlSST） dataset to the ocean model of BCC-CSM1.1 via Ensemble Optimum Interpolation （EnOI）. Then a suite of decadal reforecasts launched annually over the period 1961- 2005 is carried out with simulated ocean temperature restored to the assimilated ocean data. Comparisons between the re-forecasts and previous CMIP5 forecasts show that the re-forecasts are more skillful in mid-to-high latitude SST of the North Atlantic. Improved prediction skill is also found for the Atlantic multi-decadal oscillation （AMO）, which is consistent with the better skill of Atlantic meridional overturning circulation （AMOC） predicted by the re-forecasts. We conclude that the EnOl assimilation generates better ocean data than the SODA reanalysis for initializing decadal climate prediction of BCC-CSM1.1 model.

Climate Services for Water Resource Management in China: The Case Study of Danjiangkou Reservoir

The efficiencies and effectiveness of water resource management are inextricably linked to climate services. This study demonstrates a climate information service for Danjiangkou Reservoir, which is the largest artificial lake in Asia, facing mounting challenges for flood control, water storage, and water diversion. Unlike traditional water resource management on the basis of short-term weather forecast and runoff monitoring, subseasonal to seasonal(S2S)and annual climate predictions as well as long-term climate change projections were well used to support the decision makers in Danjiangkou Reservoir. The National Climate Center(NCC) has projected the changes of future climate and extreme events by dynamically downscaling the Coupled Model Intercomparison Project phase 5(CMIP5)projections to 25-km resolution for the long-term planning of water resource management in Danjiangkou Reservoir.Real-time climate predictions based on climate models and downscaling interpretation and application methods at different timescales were also provided to meet the specific needs of earlier predictions and spatial refinement for the short-term diversion of the reservoir. Our results show that such climate services facilitated the Diversion Center of Danjiangkou Reservoir(DCDR) to reasonably control the operational water level, increased the ecological water supply to the northern portion of China by 844 million m^(3), and reduced as much as 1.67 billion m^(3) of abandoned water in 2019. In the future, it is necessary to develop climate prediction methods to increase spatial and temporal resolutions and prediction skills, and enhance interactions between providers and users.

Fractal Design Boosts Extrusion-Based 3D Printing of Bone-Mimicking Radial-Gradient Scaffolds

Although extrusion-based three-dimensional(EB-3D)printing technique has been widely used in the complex fabrication of bone tissue-engineered scaffolds,a natural bone-like radial-gradient scaffold by this processing method is of huge challenge and still unmet.Inspired by a typical fractal structure of Koch snowflake,for the first time,a fractal-like porous scaffold with a controllable hierarchical gradient in the radial direction is presented via fractal design and then implemented by EB-3D printing.This radial-gradient structure successfully mimics the radially gradual decrease in porosity of natural bone from cancellous bone to cortical bone.First,we create a design-to-fabrication workflow with embedding the graded data on basis of fractal design into digital processing to instruct the extrusion process of fractal-like scaffolds.Further,by a combination of suitable extruded inks,a series of bone-mimicking scaffolds with a 3-iteration fractal-like structure are fabricated to demonstrate their superiority,including radial porosity,mechanical property,and permeability.This study showcases a robust strategy to overcome the limitations of conventional EB-3D printers for the design and fabrication of functionally graded scaffolds,showing great potential in bone tissue engineering.