Study on creep deformation and energy development of underground surrounding rock under four‐dimensional support

There is an urgent need to develop optimal solutions for deformation control of deep high‐stress roadways,one of the critical problems in underground engineering.The previously proposed four‐dimensional support(hereinafter 4D support),as a new support technology,can set the roadway surrounding rock under three‐dimensional pressure in the new balanced structure,and prevent instability of surrounding rock in underground engineering.However,the influence of roadway depth and creep deformation on the surrounding rock supported by 4D support is still unknown.This study investigated the influence of roadway depth and creep deformation time on the instability of surrounding rock by analyzing the energy development.The elastic strain energy was analyzed using the program redeveloped in FLAC3D.The numerical simulation results indicate that the combined support mode of 4D roof supports and conventional side supports is highly applicable to the stability control of surrounding rock with a roadway depth exceeding 520 m.With the increase of roadway depth,4D support can effectively restrain the area and depth of plastic deformation in the surrounding rock.Further,4D support limits the accumulation range and rate of elastic strain energy as the creep deformation time increases.4D support can effectively reduce the plastic deformation of roadway surrounding rock and maintain the stability for a long deformation period of 6 months.As confirmed by in situ monitoring results,4D support is more effective for the long‐term stability control of surrounding rock than conventional support.

Experimental study of the dynamic mechanical responses and failure characteristics of coal under true triaxial confinements

Investigations on the dynamic mechanical properties and failure mechanisms of coal under in-situ stress is essential for the prevention of dynamic disasters in deep coal mines.Thus,a modified true triaxial Hopkinson bar was employed to explore the dynamic mechanical behaviors of coal at different confining pressures(0–20 MPa)and strain rates(40–220 s^(-1)).The results show that the dynamic peak stress is positively correlated with lateral static pre-stressσy andσz,but negatively correlated with axial static prestressσx.At approximate strain rates,increasing the lateral static pre-stress facilitates increasing the dynamic peak stress,but the minimum lateral static pre-stress is the primary factor limiting a significant increase in dynamic peak stress of coal.Furthermore,the dynamic differential stress is linearly related to the logarithm of strain rate,and the peak strain varies linearly with strain rate.However,there is no significant correlation between confining pressure and peak strain.Moreover,X-ray CT images and photographic fracture observations of coal samples show the failure patterns under uniaxial and triaxial conditions are splitting failure and shear failure,respectively.The device provides a viable approach for fully comprehending the dynamic mechanical behaviors of rock-like material in complex stress conditions.

GRATDet:Smart Contract Vulnerability Detector Based on Graph Representation and Transformer

Smart contracts have led to more efficient development in finance and healthcare,but vulnerabilities in contracts pose high risks to their future applications.The current vulnerability detection methods for contracts are either based on fixed expert rules,which are inefficient,or rely on simplistic deep learning techniques that do not fully leverage contract semantic information.Therefore,there is ample room for improvement in terms of detection precision.To solve these problems,this paper proposes a vulnerability detector based on deep learning techniques,graph representation,and Transformer,called GRATDet.The method first performs swapping,insertion,and symbolization operations for contract functions,increasing the amount of small sample data.Each line of code is then treated as a basic semantic element,and information such as control and data relationships is extracted to construct a new representation in the form of a Line Graph(LG),which shows more structural features that differ from the serialized presentation of the contract.Finally,the node information and edge information of the graph are jointly learned using an improved Transformer-GP model to extract information globally and locally,and the fused features are used for vulnerability detection.The effectiveness of the method in reentrancy vulnerability detection is verified in experiments,where the F1 score reaches 95.16%,exceeding stateof-the-art methods.

遥感用于鄱阳湖区钉螺孳生地的监测(英文)

目的 结合遥感技术和地面生态学调查数据区分钉螺孳生地并监测其变化。 方法 从鄱阳湖共选择10 0个调查点 ,75个为从鄱阳湖 5 74块草洲中随机抽取。根据历史调查 (1982～ 1984 ) ,其中 5 0个有螺 ,2 5个无螺 ,另2 5个为非钉螺孳生地调查点。将每个调查点 (面积 10 0 0 0 m2 )分成 10 0格 ,从中随机抽取 2 0格 ,在每格的中央置钉螺调查框 (4m2 ) ,收集框内所有钉螺。收集与地面调查同期的 TM卫片。采用非监督分类法对卫片进行分类并结合地面调查结果区分钉螺孳生地。 结果 分类的敏感性和特异性分别为 90 .0 %～ 95 .6 %和 6 1.1%～ 6 8.6 %。 1999～ 2 0 0 0年 ,鄱阳湖区估算的钉螺孳生地面积变幅为 6 2 3.4～ 76 2 .8km2。 结论 钉螺孳生地与植被覆盖的区域有关 ,卫片分类能用于区分钉螺孳生地确定其范围并监测其随关键因素的波动而造成的变化。

Mn/beta and Mn/ZSM-5 for the low-temperature selective catalytic reduction of NO with ammonia: Effect of manganese precursors

Two series of Mn/beta and Mn/ZSM‐5catalysts were prepared to study the influence of how different Mn precursors,introduced to the respective parent zeolites by wet impregnation,affected the selective catalytic reduction(SCR)of NO by NH3across a low reaction temperature window of50–350°C.In this study,the catalysts were characterized using N2adsorption/desorption,X‐ray diffraction,X‐ray fluorescence,H2temperature‐programmed reduction,NH3temperature‐programmed desorption and X‐ray photoelectron spectroscopy.As the manganese chloride precursor only partially decomposed this primarily resulted in the formation of MnCl2in addition to the presence of low levels of crystalline Mn3O4,which resulted in poor catalytic performance.However,the manganese nitrate precursor formed crystalline MnO2as the major phase in addition to a minor presence of unconverted Mn‐nitrate.Furthermore,manganese acetate resulted principally in a mixture of amorphous Mn2O3and MnO2,and crystalline Mn3O4.From all the catalysts screened,the test performance data showed Mn/beta‐Ac to exhibit the highest NO conversion(97.5%)at240°C,which remained>90%across a temperature window of220–350°C.The excellent catalytic performance was ascribed to the enrichment of highly dispersed MnOx(Mn2O3and MnO2)species that act as the active phase in the NH3‐SCR process.Furthermore,together with a suitable amount of weakly acidic centers,higher concentration of surface manganese and a greater presence of surface labile oxygen groups,SCR performance was collectively enhanced at low temperature.?2018,Dalian Institute of Chemical Physics,Chinese Academy of Sciences.Published by Elsevier B.V.All rights reserved.

Correlation of Direct Piezoelectric Effect on EAPap under Ambient Factors

Direct piezoelectricity of electro-active papers （EAPap） is analysed in this paper. The test setups for direct effect are designed and determined. Different ambient factors impacting the piezoelectricity of EAPap, such as temperature, humidity, and strain rate, are applied and analyzed. Strong piezoelectricity of EAPap is found on the basis of the test results and in comparison with polyvinylidene fluoride （PVDF） and lead zirconate titanate （PZT）-5H. The maximum piezoelectric constant is achieved to be 504 pC/N. The reason of strong piezoelectricity of EAPap is discussed in this paper. The potential of EAPap as a biomimetic actuator and sensor is also investigated.

Five tips for China to realize its co-targets of climate mitigation and Sustainable Development Goals(SDGs)

In 2018,a total of US$166 billion global economic losses and a new high of 55.3 Gt of CO_(2)equivalent emission were generated by 831 climate-related extreme events.As the world’s largest CO_(2)emitter,we reported China’s recent progresses and pitfalls in climate actions to achieve climate mitigation targets(i.e.,limit warming to 1.5-2°C above the pre-industrial level).We first summarized China’s integrated actions(2015 onwards)that benefit both climate change mitigation and Sustainable Development Goals(SDGs).These projects include re-structuring organizations,establishing working goals and actions,amending laws and regulations at national level,as well as increasing social awareness at community level.We then pointed out the shortcomings in different regions and sectors.Based on these analyses,we proposed five recommendations to help China improving its climate policy strategies,which include:1)restructuring the economy to balance short-term and long-term conflicts;2)developing circular economy with recycling mechanism and infrastructure;3)building up unified national standards and more accurate indicators;4)completing market mechanism for green economy and encouraging green consumption;and 5)enhancing technology innovations and local incentives via bottom-up actions.

“this/these+标示名词”语义功能的学科对比分析

在学术语篇中,标示名词经常与指示代词this或these搭配使用,研究"this/these+标示名词"构式有助于我们系统地考察标示名词的功能与使用情况。本研究主要基于北京外国语大学DEAP语料库中的生物学和应用语言学研究性期刊论文两个子库,对比分析了理工学科和人文学科"this/these+标示名词"构式的语义分布。研究发现,这一构式在理工学科论文中的使用频率显著低于人文学科。从语义分类来看,事实类和论辩类标示名词在两个学科中存在显著差异。从论文内部结构来看,理工学科在"讨论"和"研究结果"部分使用这一构式较频繁,人文学科则是"讨论"和"引言"部分较多使用。本研究对学术话语分析、学术英语写作教学具有启示作用。

Experimental investigation of thermal transfer coefficient by a simplified energy balance of fault arc in a closed air vessel

The themial transfer coefficient that represents the portion of energy heating the surrounding gas of fault arc is a key parameter in evaluating the pressure effects due to fault arcing in a closed electrical installation.This paper presents experimental research on the thermal transfer coefficient in a closed air vessel for Cu,Fe and A1 electrode materials over a currcni range from 1-20 kA with an electrode gap from 10-50 mm and gas pressure from 0.05-0.4 MPa.With a simplified energy balance including Joule heating,arc radiation,ihc energies related to electrode melting,vaporization and oxidation constructed,and the influences of different factors on thermal transfer coefficient are studied and evaluated.This quantitative estimation of the energy components confirmed that the pressure rise is closely related to the change in heat transport process of fault arc.particularly in consideration of the evaluation of Joule healing and radiation.Factors such as the electrode material,arc current,filling pressure and gap length between electrodes have a considerable effect on the thermal transfer coefficient and thus,the pressure rise due to the differences in the energy balance of fault arc.

Measurement of Particle Velocity, Particle Size Distribution and Concentration in Particulate Suspension by Transmission Fluctuation Correlation Spectrometry

In coal-fired power generation industry, parameters such as particle size affect combustion efficiency. Especially in the application of two-phase flow clean energy, the parameters such as particle velocity, particle size distribution and concentration are very important, because the coal particle velocity, concentration or size range have an impact on the whole combustion process. This paper introduces an optical measurement setup based on the transmission fluctuation correlation spectrum measurement technique, which realizes the simultaneous measurement of particle velocity, particle size distribution and concentration. Compared with image method, ultrasonic spectrum method and other methods, the experimental device is simple and low-cost.

Mapping global lake aquatic vegetation dynamics using 10-m resolution satellite observations

Aquatic vegetation is crucial for improving water quality,supporting fisheries and preserving biodiversity in lakes.Monitoring the spatiotemporal dynamics of aquatic vegetation is indispensable for the assessment and protection of lake ecosystems.Nevertheless,a comprehensive global assessment of lacustrine aquatic vegetation is lacking.This study introduces an automatic identification algorithm(with a total accuracy of 94.4%)for Sentinel-2 MSI,enabling the first-ever global mapping of aquatic vegetation distribution in 1.4 million lakes using 14.8 million images from 2019 to 2022.Results show that aquatic vegetation occurred in 81,116 lakes across six continents over the past four years,covering a cumulative maximum aquatic vegetation area(MVA)of 16,111.8 km^(2).The global median aquatic vegetation occurrence(VO,in%)is 3.0%,with notable higher values observed in South America(7.4%)and Africa(4.1%)compared with Asia(2.7%)and North America(2.4%).High VO is also observed in lakes near major rivers such as the Yangtze,Ob,and ParanáRivers.Integrating historical data with our calculated MVA,the aquatic vegetation changes in 170 lakes worldwide were analyzed.It shows that 72.4%(123/170)of lakes experienced a decline in aquatic vegetation from the early 1980s to 2022,encompassing both submerged and overall aquatic vegetation.The most substantial decrease is observed in Asia and Africa.Our findings suggest that,beyond lake algal blooms and temperature,the physical characteristics of the lakes and their surrounding environments could also influence aquatic vegetation distribution.Our research provides valuable information for the conservation and restoration of lacustrine aquatic vegetation.

Elevational distribution of forests and its spatiotemporal dynamics in subtropical China from 2000 to 2019

The subtropical region of China possesses abundant forest resources and features a mountainous terrain.Under the implementation of policies such as natural forest protection,the Grain for Green Project,and other initiatives since the beginning of the 21st century,coupled with climate change,the forest resources in this region have undergone significant changes compared to historical periods.In addition,forest resources distributing mainly in mountainous areas also implies that these changes may vary significantly with elevation.To explore the spatiotemporal dynamics of forest distribution in subtropical China since 2000,especially the trend of changes with elevation,we analyzed the data from two land cover products focusing on forest cover and forest types.We used a hierarchical approach,in which coarse-classification forest cover data with relatively small uncertainties impose constraints on forest type data with larger uncertainties,to achieve a reasonable balance between obtaining more details and reducing data uncertainty.We first divided the forest cover data into‘unchanged'and‘changed'categories.With the constraints by the forest cover results,we further analyzed the‘unchanged'and‘changed'forest types.The results indicated that,since the implementation of ecological engineering and management policies,54%of the area in the subtropical region had maintained unchanged forest cover attributes over the past 20 years,which implied the good state of ecological environment.The results also showed that dynamic conversions existed in the long term between forests and lands for essential production needs like croplands.The elevational variations of forest cover suggested that the dominant changes came from the conversion between forests and croplands in low-elevation regions below 700 m,the conversion between forests and shrublands in mid-elevation regions of 700–1500 m,and the conversion between forests and grasslands in high-elevation regions above 2000 m.In the regions with unchanged forest cover,96%exhibited unchanged forest types as well.Evergreen broad-leaved forests(EBF)were most widely distributed below 1700 m,while evergreen needle-leaved forests(ENF)dominated above 1700 m.There was still a large area of ENF and EBF undergoing dynamic conversions from/to transitional forest types such as mosaic of tree,shrub,and herbaceous cover(T-S-H)and mosaic of natural vegetation and cropland(NV-CRO).ENF almost unidirectionally transformed into T-S-H in low-elevation regions below 1000 m,and transformed from NV-CRO in mid-and high-elevation regions above1000 m.EBF experienced an areal decrease and transformed into T-S-H in low-elevation regions,but the areal increase in mid-to low-elevation regions mainly transformed from NV-CRO.These variations with elevation may involve the impacts of specific human activities and climate change,and will provide a vertical dimension of information and perspectives for an in-depth exploration of the evolving ecosystem services of forest resources in subtropical China.

Data error propagation in stacked bioclimatic envelope models

Stacking is the process of overlaying inferred species potential distributions for multiple species based on outputs of bioclimatic envelope models(BEMs).The approach can be used to investigate patterns and processes of species richness.If data limitations on individual species distributions are inevitable,but how do they affect inferences of patterns and processes of species richness?We investigate the influence of different data sources on estimated species richness gradients in China.We fitted BEMs using species distributions data for 334 bird species obtained from(1)global range maps,(2)regional checklists,(3)museum records and surveys,and(4)citizen science data using presence-only(Mahalanobis distance),presence-background(MAXENT),and presence–absence(GAM and BRT)BEMs.Individual species predictions were stacked to generate species richness gradients.Here,we show that different data sources and BEMs can generate spatially varying gradients of species richness.The environmental predictors that best explained species distributions also differed between data sources.Models using citizen-based data had the highest accuracy,whereas those using range data had the lowest accuracy.Potential richness patterns estimated by GAM and BRT models were robust to data uncertainty.When multiple data sets exist for the same region and taxa,we advise that explicit treatments of uncertainty,such as sensitivity analyses of the input data,should be conducted during the process of modeling.

全球地表覆盖制图有限样本稳定分类的理论与实验

Global land cover(GLC)maps are essential to understanding of Earth surface processes including physical and biogeochemical processes such as carbon and nitrogen cycling,climate and hydrological dynamics,as well as anthropogenic processes such as land use change and disease dispersal.Most land cover maps at the global scale are produced by analyzing satellite images through image classification.In particular,the accessibility of Landsat and Sentinel images has significantly improved mapping resolution from kilometer level to 10–30 m[1,2].

Deforestation in Latin America in the 2000s predominantly occurred outside of typical mature forests

The role of tropical forests in the global carbon budget remains controversial,as carbon emissions from deforestation are highly uncertain.This high uncertainty arises from the use of either fixed forest carbon stock density or maps generated from satellite-based optical reflectance with limited sensitivity to biomass to generate accurate estimates of emissions from deforestation.New space missions aiming to accurately map the carbon stock density rely on direct measurements of the spatial structures of forests using lidar and radar.We found that lost forests are special cases,and their spatial structures can be directly measured by combining archived data acquired before and after deforestation by space missions principally aimed at measuring topography.Thus,using biomass mapping,we obtained new estimates of carbon loss from deforestation ahead of forthcoming space missions.Here,using a high-resolution map of forest loss and the synergy of radar and lidar to estimate the aboveground biomass density of forests,we found that deforestation in the 2000s in Latin America,one of the severely deforested regions,mainly occurred in forests with a significantly lower carbon stock density than typical mature forests.

China's current forest age structure will lead to weakened carbon sinks in the near future

Forests are chiefly responsible for the terrestrial carbon sink that greatly re duces the buildup of CO_(2)concentrations in the atmosphere and alleviates climate change.Current predictions of terrestrial carbon sinks in the future have so far ignored the variation of forest carbon uptake with forest age.Here,we predict the role of China's current forest age in future carbon sink capacity by generating a high-resolution(30 m)forest age map in 2019 over China's landmass using satellite and forest inventory data and deriving forest growth curves using measurements of forest biomass and age in 3,121 plots.As China's forests currently have large proportions of young and middle-age stands,we project that China's forests will maintain high growth rates for about 15 years.However,as the forests grow older,their net primary productivity will decline by 5.0%±1.4%in 2050,8.4%±1.6%in 2060,and 16.6%±2.8%in 2100,indicating weakened carbon sinks in the near future.The weakening of forest carbon sinks can be potentially mitigated by optimizing forest age structure through selective logging and implementing new or improved afforestation.This finding is important not only for the global carbon cycle and climate projections but also for developing forest management strategies to enhance land sinks by alleviating the age effect.

Oridonin inhibits SARS-CoV-2 replication by targeting viral proteinase and polymerase

COVID-19 has become a global public health crisis since its outbreak in China in December 2019.Currently there are few clinically effective drugs to combat SARS-CoV-2 infection.The main protein(M^(pro)),papain-like protease(PL^(pro))and RNA-dependent RNA polymerase(RdRp)of SARS-CoV-2 are involved in the viral replication,and might be prospective targets for anti-coronavirus drug development.Here,we investigated the antiviral activity of oridonin,a natural small-molecule compound,against SARS-CoV-2 infection in vitro.The time-of-addition analysis showed that oridonin efficiently inhibited SARS-CoV-2 infection by interfering with the genome replication at the post-entry stage.Mechanistically,the inhibition of viral replication by oridonin depends on the oxidation activity ofα,β-unsaturated carbonyl.Further experiments showed that oridonin not only effectively inhibited SARS-CoV-2 Mpro activity,but also had some inhibitory effects on PLpro-mediated deubiquitinating and viral polymerase-catalyzed RNA elongation activities at high concentrations.In particular,oridonin could inhibit the bat SARS-like CoV and the newly emerged SARS-CoV-2 omicron variants(BA.1 and BA.2),which highlights its potential as a pan-coronavirus antiviral agent.Overall,our data provide strong evidence that oridonin is an efficient antiviral agent against SARS-CoV-2 infection.

气候变化情景下中国因高温造成的劳动生产力损失预估

气候变化背景下,高温会影响职业人群的工作效率并造成劳动生产力损失.本研究基于区域气候模式并采用本土化的暴露-反应函数,预估了未来气候变化情景下中国因高温造成的劳动时间损失.研究发现,与基线期的213亿小时高温相关劳动时间损失相比,到21世纪末在RCP2.6、RCP4.5和RCP8.5情景下,损失将分别增加-17.8%、10.8%及121.1%.损失主要集中在华南、华中和华东地区,其中广东与河南将占到全国总损失的四分之一.因为这些区域的温度将更高、人口更密集、户外工作者在总人群中的比例较大.与RCP2.6、RCP4.5和RCP8.5情景相比,若能实现1.5℃温控目标,将分别能够避免11.8%、33.7%和53.9%的劳动时间损失,相当于避免了全中国21世纪中叶的0.1%、0.6%及1.4%的年均GDP损失.本研究显示未来气候变化会给中国造成严重的热相关劳动生产力损失,并强调亟需采取因地制宜的气候减缓及适应策略以保护职业人群健康.本研究对其他与中国相似的发展中国家同样具有重要意义.

Unusual substructure conformations observed in crystal structures of a dicistrovirus RNA-dependent RNA polymerase suggest contribution of the N-terminal extension in proper folding

The Dicistroviridae is a virus family that includes many insect pathogens.These viruses contain a positive-sense RNA genome that is replicated by the virally encoded RNA-dependent RNA polymerase(RdRP)also named 3D^(pol).Compared with the Picornaviridae RdRPs such as poliovirus(PV)3D^(pol),the Dicistroviridae representative Israeli acute paralysis virus(IAPV)3D^(pol) has an additional N-terminal extension(NE)region that is about 40-residue in length.To date,both the structure and catalytic mechanism of the Dicistroviridae RdRP have remain elusive.Here we reported crystal structures of two truncated forms of IAPV 3D^(pol),namelyΔ85 andΔ40,both missing the NE region,and the 3D^(pol) protein in these structures exhibited three conformational states.The palm and thumb domains of these IAPV 3D^(pol) structures are largely consistent with those of the PV 3D^(pol) structures.However,in all structures,the RdRP fingers domain is partially disordered,while different conformations of RdRP substructures and interactions between them are also present.In particular,a large-scale conformational change occurred in the motif B-middle finger region in one protein chain of theΔ40 structure,while a previously documented alternative conformation of motif A was observed in all IAPV structures.These experimental data on one hand show intrinsic conformational variances of RdRP substructures,and on the other hand suggest possible contribution of the NE region in proper RdRP folding in IAPV.