采场覆岩空间破裂与采动应力场的微震探测研究

介绍了用微地震定位监测技术揭示的采场覆岩空间破裂与采动应力场的关系。认为存在 4种由采动引起的岩体破裂类型。展示了 3种典型采动边界条件下覆岩破裂与采动应力场的关系。提出了由微震事件分布推断区段煤柱稳定性的方法。

微地震监测揭示的采场围岩空间破裂形态

中澳联合课题组采用微地震定位监测技术,观测和研究了煤矿长壁工作面围岩的空间破坏规律,分析得出:地层进入充分采动阶段前,岩层的破裂高度近似为采空区短边长度的一半;证实了采空区"见方"时顶板破裂高度达到最大值,且采场顶板容易来大压(异常压力),解释了国内外部分综采、综放采场支架压坏的岩层运动机理;根据微地震监测结果,提出了工作面长度为200～250m时底板破裂深度的估计曲线以及岩层离层与破裂的微地震显现的差异;初步描述了采场围岩空间破裂的形态,即在采空区周围顶、底板及四周煤体破裂后形成的三维空间破裂形态.

微震监测技术在矿井岩层破裂监测中的应用

介绍了澳大利亚联邦科学工业研究院勘探采矿局 (CSIRO)开发的用于岩层破裂监测的微震监测系统 ,为能将之应用于中国深井灾害的监测 ,提出了对软硬件改造和开发井下智能化、自动化和可视化微震监测系统的初步方案 。

Protective effects of organic extracts of Alpinia oxyphylla against hydrogen peroxide-induced cvtotoxicitv in PC12 cells

Alpinia oxyphylla,a traditional herb,is widely used for its neuroprotective,antioxidant and memory-improving effects.However,the neuroprotective mechanisms of action of its active ingredients are unclear.In this study,we investigated the neuroprotective effects of various organic extracts of Alpinia oxyphylla on PC12 cells exposed to hydrogen peroxide-induced oxidative injury in vitro.Alpinia oxyphylla was extracted three times with 95%ethanol(representing extracts 1–3).The third 95%ethanol extract was dried and resuspended in water,and then extracted successively with petroleum ether,ethyl acetate and n-butanol(representing extracts 4–6).The cell counting kit-8 assay and microscopy were used to evaluate cell viability and observe the morphology of PC12 cells.The protective effect of the three ethanol extracts(at tested concentrations of 50,100 and 200μg/mL)against cytotoxicity to PC12 cells increased in a concentration-dependent manner.The ethyl acetate,petroleum ether and n-butanol extracts(each tested at 100,150 and 200μg/mL)had neuroprotective effects as well.The optimum effective concentration ranged from 50–200μg/mL,and the protective effect of the ethyl acetate extract was comparatively robust.These results demonstrate that organic extracts of Alpinia oxyphylla protect PC12 cells against apoptosis induced by hydrogen peroxide.Our findings should help identify the bioactive neuroprotective components in Alpinia oxyphylla.

Classification of clustered microseismic events in a coal mine using machine learning

Discrimination of seismicity distributed in different areas is essential for reliable seismic risk assessment in mines.Although machine learning has been widely applied in seismic data processing,feasibility and reliability of applying this technique to classify spatially clustered seismic events in underground mines are yet to be investigated.In this research,two groups of seismic events with a minimum local magnitude(ML) of-3 were observed in an underground coal mine.They were respectively located around a dyke and the longwall face.Additionally,two types of undesired signals were also recorded.Four machine learning methods,i.e.random forest(RF),support vector machine(SVM),deep convolutional neural network(DCNN),and residual neural network(ResNN),were used for classifying these signals.The results obtained based on a primary dataset showed that these seismic events could be classified with at least 91% accuracy.The DCNN using seismogram images as the inputs reached the best performance with more than 94% accuracy.As mining is a dynamic progress which could change the characteristics of seismic signals,the temporal variance in the prediction performance of DCNN was also investigated to assess the reliability of this classifier during mining.A cascaded workflow consisting of database update,model training,signal prediction,and results review was established.By progressively calibrating the DCNN model,it achieved up to 99% prediction accuracy.The results demonstrated that machine learning is a reliable tool for the automatic discrimination of spatially clustered seismicity in underground mining.

地下气化火区燃烧波位态的微地震监测技术初析

在研究分析了地下气化火区燃烧波位态的探测方法基础上,探讨了地下气化火区燃烧波位态的微地震监测技术可行性和必要性,提出了地下气化火区微地震监测系统构建方法。

Procedural modeling applied to the 3D city model of Bogota:A case study

Background Computer Generated Animations(CGA),when applied to three-dimensional(3D)city models(3DCM),can be used as powerful tools to support urban decision-making.This leads to a new paradigm,based on procedural modeling,that allows the integration of known urban structures.Methods This paper introduces a new workflow for the development of high-quality approximations of urban models in a short time and enables facilities to be imported from other cities into a given city model,following specific generation rules.Results Thus,this workflow provides a very simple approach to observe,study,and simulate the implementation of models already developed in other cities,in a city where they are not yet adopted.Examples of these models include all types of mobility systems and urban infrastructure.Conclusions This allows us to perceive the environmental impact of certain decisions in the real world,as well as to carry out simple simulations to determine the changes that can occur in the flows of people,traffic,and other city activities.

Meeting 24-h Movement Guidelines is Related to Better Academic Achievement:Findings from the YRBS 2019 Cycle

This research is designed to investigate the relationship between the 24-h movement guidelines(24-HMG)and self-reported academic achievement(AA)using nationally representative data derived from the 2019 U.S.National Youth Risk Behaviour Survey.A multiple-stage cluster sampling procedure has been adopted to ensure a representative sample(N=9127 adolescents;mean age=15.7 years old;male%=49.8%).Logistic regression has been adopted to obtain the odds ratio(OR)regarding the associations between adherence to 24-HMG and AA while controlling for ethnicity,body mass index,sex and age.The prevalence of meeting the 24-h movement guidelines in isolation and combination varied greatly(physical activity=23.3%,screen time=32.5%,sleep=22.3%,and 24-HMG=2.8%),while the percentage of highest-class AA was 42.5%.Compared with the situation when none of 24-HMG is met,the achievement of any of the combined guidelines(except for meeting the physical activity guidelines)was significantly associated with higher odds of achieving first-class AA.Meeting the sleep guideline had 1.42 times increased likelihood to achieve highest-class AA as compared with not meeting the sleep guideline.Meeting screen time guidelines and physical activity guidelines,respectively,were 1.32 and 1.13 times more likely to report first-class AA;but meeting the guidelines of physical activity was not significantly related to AA.Meeting the 24-HMG had the highest odds of achieving first-class AA(OR=2.01,95%CI:1.47-2.73).In both sexes,adolescents who met 24-HMG self-reported better AA(boys OR=2.05,95%CI:1.34-3.15;girls OR=2.26,95%CI:1.36-3.76).Significant relationships were observed in adolescents from 9-10th grade,but not higher grades.Our research findings suggest that optimal movement behaviours can be seen as an important element to better academic achievement among U.S.adolescents.Future studies can adopt our discoveries to promote adolescents’academic achievement through implementing optimal 24-h movement behaviour patterns.

Association between Meeting 24-Hour Movement Guidelines and Psychological Features of Chinese Emerging Adults

Background:Emerging adulthood is a pivotal life stage,presenting significant psychological and social changes,such as decreased sociability,depression,and other mental health problems.Previous studies have associated these changes with an unhealthy lifestyle.The 24-h movement guidelines for healthy lifestyles have been developed to promote appropriate health behaviors and improve individual wellness.However,the relationship between adherence to the 24-h movement guidelines and different characteristics of Chinese emerging adults is yet to be explored.This cross-sectional study aimed to investigate the association between adherence to the 24-h movement guidelines and four characteristics(self-exploration,instability,possibilities,and responsibility)of Chinese emerging adults.Methods:Overall,1,510 Chinese emerging adults aged 18–29 years were included in this study.Each participant completed a self-administered questionnaire that included questions on adherence to the 24-h movement guidelines(physical activity,sedentary behavior,and sleep)and the inventory of dimensions of emerging adulthood.Multivariable logistic regression analysis was employed to investigate the associations between adherence to the 24-h movement guidelines and each of the four characteristics.Results:The proportion of participants who adhered to the 24-h movement guidelines was 31.72%.Multiple regression analysis revealed a significantly negative relationship between adhering to more guidelines and instability(β=−0.51,p<0.001).A statistically significant association was observed between instability and meeting only sedentary behavior(β=−1.27,95%confidence interval[CI]:[−2.32,−0.24],p=0.02),sedentary behavior+sleep(β=−1.30,95%CI:[−2.24,−0.35],p<0.01),and physical activity+sedentary behavior(β=−1.08,95%CI:[1.94,−0.21],p=0.02)guidelines.Further,positive and significant associations were observed between possibilities and meeting the guidelines for only physical activity(β=0.70,95%CI:[0.14,1.27),p=0.01),only sleep(β=0.61,95%CI:[0.01,1.21],p=0.04),physical activity+sedentary behavior(β=0.56,95%CI:[0.04,1.07),p=0.01),and physical activity+sleep(β=0.76,95%CI:[0.23,1.27],p=0.01).Conclusions:These findings suggest that adherence to the 24-h movement guidelines was associated with instability in Chinese emerging adults.Future studies are warranted to verify our findings to highlight the importance of maintaining a heath lifestyle to promote health in emerging adulthood.

Production of glass-ceramics using Municipal solid waste incineration fly ash

Municipal solid waste incineration(MSWI) fly ash is a by-product from municipal waste incineration.According to incomplete statistics, each year more than one million tons MSWI fly ash was produced in China. Owing to high heavy elements content, widely used disposal methods of landfill are not suitable for MSWI fly ash treatment. In this study, by using MSWI fly ash as raw materials, glassceramics was synthesized for the solidification of heavy metals and waste recycle. Process parameters, including composition, heat treatment temperature and time, were studied and optimized. Under optimizing conditions, the product has good properties of density of 3.42 g·cm^(-3) and Vickers hardness of 6.91 GPa. Moreover, the leaching concentration of heavy metal elements meets allowable values of toxicity characteristic leaching procedure(TCLP).This study offers an alternative for MSWI fly ash recycle.