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The complex roles of m^(6)A modifications in neural stem cell proliferation, differentiation, and self-renewal and implications for memory and neurodegenerative diseases
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作者 Yanxi Li Jing xue +8 位作者 Yuejia Ma Ke Ye xue Zhao Fangliang Ge Feifei Zheng Lulu Liu xu gao Dayong Wang Qing Xia 《Neural Regeneration Research》 SCIE CAS 2025年第6期1582-1598,共17页
N6-methyladenosine(m^(6)A), the most prevalent and conserved RNA modification in eukaryotic cells, profoundly influences virtually all aspects of mRNA metabolism. mRNA plays crucial roles in neural stem cell genesis a... N6-methyladenosine(m^(6)A), the most prevalent and conserved RNA modification in eukaryotic cells, profoundly influences virtually all aspects of mRNA metabolism. mRNA plays crucial roles in neural stem cell genesis and neural regeneration, where it is highly concentrated and actively involved in these processes. Changes in m^(6)A modification levels and the expression levels of related enzymatic proteins can lead to neurological dysfunction and contribute to the development of neurological diseases. Furthermore, the proliferation and differentiation of neural stem cells, as well as nerve regeneration, are intimately linked to memory function and neurodegenerative diseases. This paper presents a comprehensive review of the roles of m^(6)A in neural stem cell proliferation, differentiation, and self-renewal, as well as its implications in memory and neurodegenerative diseases. m^(6)A has demonstrated divergent effects on the proliferation and differentiation of neural stem cells. These observed contradictions may arise from the time-specific nature of m^(6)A and its differential impact on neural stem cells across various stages of development. Similarly, the diverse effects of m^(6)A on distinct types of memory could be attributed to the involvement of specific brain regions in memory formation and recall. Inconsistencies in m^(6)A levels across different models of neurodegenerative disease, particularly Alzheimer's disease and Parkinson's disease, suggest that these disparities are linked to variations in the affected brain regions. Notably, the opposing changes in m^(6)A levels observed in Parkinson's disease models exposed to manganese compared to normal Parkinson's disease models further underscore the complexity of m^(6)A's role in neurodegenerative processes. The roles of m^(6)A in neural stem cell proliferation, differentiation, and self-renewal, and its implications in memory and neurodegenerative diseases, appear contradictory. These inconsistencies may be attributed to the timespecific nature of m^(6)A and its varying effects on distinct brain regions and in different environments. 展开更多
关键词 Alzheimer's disease cell self-renewal central nervous system MEMORY MICROGLIA nerve regeneration neurodegenerative diseases NEUROGENESIS RNA methylation
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压缩空气储能盐穴储气库技术及其智能建造工艺技术研究 被引量:1
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作者 徐高 谢芳毅 +4 位作者 曹振瑞 赵星源 崔建华 韩少峰 何青 《热力发电》 CAS CSCD 北大核心 2024年第9期48-59,共12页
当前,盐穴型储气库建造技术已较为成熟,并朝着智能化方向发展。根据盐穴储气库技术现状,对盐穴储气库当前建造技术进行分析;从全生命周期管理角度,将盐穴储气库智能建造划分为智能选址、智能设计、智能施工、智能运维4个阶段,并对每个... 当前,盐穴型储气库建造技术已较为成熟,并朝着智能化方向发展。根据盐穴储气库技术现状,对盐穴储气库当前建造技术进行分析;从全生命周期管理角度,将盐穴储气库智能建造划分为智能选址、智能设计、智能施工、智能运维4个阶段,并对每个阶段涉及的关键技术进行研究;提出盐穴储气库智能建造工艺技术框架及其具体内容;最后,从系统、技术、理论、模型4个方面,提出并总结盐穴储气库智能建造未来研究重点。相关技术在应城300 MW级压缩空气储能示范工程上得到有效应用。 展开更多
关键词 压缩空气储能 盐穴储气库 智能建 工艺 全生命周期管理
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油相组成对W/O型Pickering乳液稳定性和流变性能的影响
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作者 张聚媛 台秀梅 +3 位作者 刘慧民 马晓原 高续 罗毅 《日用化学工业(中英文)》 CAS 北大核心 2024年第8期879-886,共8页
以二甲基甲硅烷基化硅石为乳化剂,采用均质乳化法制备W/O型Pickering乳液,通过偏光显微镜、表面张力仪、接触角测量仪和流变仪研究了油脂的极性、流变改性剂对W/O型Pickering乳液稳定性及流变性能的影响。结果表明,相比于非极性油脂,极... 以二甲基甲硅烷基化硅石为乳化剂,采用均质乳化法制备W/O型Pickering乳液,通过偏光显微镜、表面张力仪、接触角测量仪和流变仪研究了油脂的极性、流变改性剂对W/O型Pickering乳液稳定性及流变性能的影响。结果表明,相比于非极性油脂,极性油脂制备出来的W/O型Pickering乳液液滴更小,稳定性能更优,其中霍霍巴油制备的Pickering乳液粒径分布较窄,形状均一,稳定性好;添加流变改性剂后,Pickering乳液的粒径有一定的下降,常温稳定性和低温稳定性均有小幅度提升,对于不同的油脂,与之结构上存在相似性的流变改性剂对粒径的降低及稳定性的提高效果较好。不同油脂制备的W/O型Pickering乳液均为非牛顿流体,随着剪切速率的增大,Pickering乳液的黏度降低,并且所有Pickering乳液的弹性模量(G')高于黏性模量(G''),均为凝胶乳液,线性黏弹区为0.001%~0.100%,添加流变改性剂后,Pickering乳液的黏度上升,剪切稀化现象基本不变,但线性黏弹区增大,可能与Pickering乳液的粒径和油水界面能的变化有关。 展开更多
关键词 W/O型Pickering乳液 乳液液滴粒径 稳定性 流变性能
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Excess non-COVID-19-related mortality among inflammatory bowel disease decedents during the COVID-19 pandemic 被引量:1
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作者 Sarah Rotondo-Trivette Xin-Yuan He +9 位作者 Jamil S Samaan Fan Lv Emily Truong Michaela Juels Anthony Nguyen xu gao Jian Zu Yee Hui Yeo Fan-Pu Ji Gil Y Melmed 《World Journal of Gastroenterology》 SCIE CAS 2024年第20期2677-2688,共12页
BACKGROUND The coronavirus disease 2019(COVID-19)pandemic disrupted healthcare in the United States.AIM To investigate COVID-19-related and non-COVID-19-related death and characteristics associated with excess death a... BACKGROUND The coronavirus disease 2019(COVID-19)pandemic disrupted healthcare in the United States.AIM To investigate COVID-19-related and non-COVID-19-related death and characteristics associated with excess death among inflammatory bowel disease(IBD)decedents.METHODS We performed a register-based study using data from the National Vital Statistics System,which reports death data from over 99%of the United States population,from January 1,2006 through December 31,2021.IBD-related deaths among adults 25 years and older were stratified by age,sex,race/ethnicity,place of death,and primary cause of death.Predicted and actual age-standardized mortality rates(ASMRs)per 100000 persons were compared.RESULTS 49782 IBD-related deaths occurred during the study period.Non-COVID-19-related deaths increased by 13.14%in 2020 and 18.12%in 2021[2020 ASMR:1.55 actual vs 1.37 predicted,95%confidence interval(CI):1.26-1.49;2021 ASMR:1.63 actual vs 1.38 predicted,95%CI:1.26-1.49].In 2020,non-COVID-19-related mortality increased by 17.65%in ulcerative colitis(UC)patients between the ages of 25 and 65 and 36.36%in non-Hispanic black(NHB)Crohn’s disease(CD)patients.During the pandemic,deaths at home or on arrival and at medical facilities as well as deaths due to neoplasms also increased.CONCLUSION IBD patients suffered excess non-COVID-19-related death during the pandemic.Excess death was associated with younger age among UC patients,and with NHB race among CD patients.Increased death at home or on arrival and due to neoplasms suggests that delayed presentation and difficulty accessing healthcare may have led to increased IBD mortality. 展开更多
关键词 Inflammatory bowel disease Ulcerative colitis Crohn’s disease COVID-19 Excess death Race SEX DISPARITIES
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Associations of daily sedentary behavior,physical activity,and sleep with irritable bowel syndrome:A prospective analysis of 362,193 participants 被引量:1
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作者 xu gao Sifan Tian +2 位作者 Ninghao Huang Gang Sun Tao Huang 《Journal of Sport and Health Science》 SCIE CSCD 2024年第1期72-80,共9页
Background:Irritable bowel syndrome(IBS)substantially affects quality of life and requires early prevention.This study aimed to elucidate the relationships between IBS and daily behaviors,including sedentary behavior(... Background:Irritable bowel syndrome(IBS)substantially affects quality of life and requires early prevention.This study aimed to elucidate the relationships between IBS and daily behaviors,including sedentary behavior(SB),physical activity(PA),and sleep.In particular,it seeks to identify healthy behaviors to reduce IBS risk,which previous studies have rarely addressed.Methods:Daily behaviors were retrieved from self-reported data of 362,193 eligible UK Biobank participants.Incident cases were determined by self-report or health care data according to RomeⅣcriteria.Results:A total of 345,388 participants were IBS-free at baseline,during a median follow-up of 8.45 years,19,885 incident IBS cases were recorded.When examined individually,SB and shorter(≤7 h/day)or longer(>7 h/day)sleep duration were each positively associated with increased IBS risk,and PA was associated with lower IBS risk.The isotemporal substitution model suggested that replacing SB with other activities could provide further protective effects against IBS risk.Among people sleeping≤7 h/day,replacing 1 h of SB with equivalent light PA,vigorous PA,or sleep was associated with 8.1%(95%confidence interval(95%CI):0.901-0.937),5.8%(95%CI:0.896-0.991),and 9.2%(95%CI:0.885-0.932)reduced IBS risk,respectively.For people sleeping>7 h/day,light and vigorous PA were associated with a 4.8%(95%CI:0.926-0.978)and a 12.0%(95%CI:0.815-0.949)lower IBS risk,respectively.These benefits were mostly independent of genetic risk for IBS.Conclusion:SB and unhealthy sleep duration are risk factors for IBS.A promising way to mitigate IBS risk for individuals sleeping≤7 h/day and for those sleeping>7 h/day appears to be by replacing SB with adequate sleep or vigorous PA,respectively,regardless of the genetic predisposition of IBS. 展开更多
关键词 Irritable bowel syndrome Isotemporal substitution model Physical activity Sedentary behavior SLEEP
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基于大涡模拟方法的三维旋转爆轰流场结构研究
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作者 雷特 武郁文 +3 位作者 徐高 邱彦铭 康朝辉 翁春生 《兵工学报》 EI CAS CSCD 北大核心 2024年第1期85-96,共12页
为研究环形燃烧室中边界层、黏性、湍流模拟方法对旋转爆轰流场结构的影响,采用开源计算流体动力学软件OpenFOAM,以氢气为燃料、空气为氧化剂,基于大涡模拟(Large Eddy Simulation,LES)方法、RANS方法、Euler方法,分别结合滑移和无滑移... 为研究环形燃烧室中边界层、黏性、湍流模拟方法对旋转爆轰流场结构的影响,采用开源计算流体动力学软件OpenFOAM,以氢气为燃料、空气为氧化剂,基于大涡模拟(Large Eddy Simulation,LES)方法、RANS方法、Euler方法,分别结合滑移和无滑移边界,对三维旋转爆轰发动机模型进行数值模拟,分析对比不同计算方法下旋转爆轰流场结构。着重讨论以LES方法得到的流场结构。研究结果表明:当采用滑移边界时内、中、外截面的流场温度无太大差异,当采用无滑移边界时内外壁面温度高于中间截面,边界层会影响近壁区域气体的流动速度,导致内外壁面爆轰波高度低于中间截面,还会影响燃烧产物的流动状态轴向截面上爆轰波波头产生变形;不同湍流计算方法得到的旋转爆轰流场结构存在相似性,黏性是影响旋转爆轰流场结构的主要原因。研究结果对于揭示边界层和黏性对旋转爆轰的影响机制具有一定的科学意义。 展开更多
关键词 大涡模拟 旋转爆轰燃烧室 数值模拟 流场结构
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A telomere-to-telomere genome assembly of Hongyingzi,a sorghum cultivar used for Chinese Baijiu production
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作者 Yanqing Ding Yilin Wang +12 位作者 Jianxia xu Feng Jiang Wenzhen Li Qiaoling Zhang Longping Yang Zhenyu Zhao Bin Cheng Ning Cao xu gao Xin Zhang Guihua Zou Fan Yang Liyi Zhang 《The Crop Journal》 SCIE CSCD 2024年第2期635-640,共6页
Sorghum(Sorghum bicolor(L.)Moench)is a world cereal crop used in China for producing Baijiu,a distilled spirit.We report a telomere-to-telomere genome assembly of the Baijiu cultivar Hongyingzi,HYZ-T2T,using ultralong... Sorghum(Sorghum bicolor(L.)Moench)is a world cereal crop used in China for producing Baijiu,a distilled spirit.We report a telomere-to-telomere genome assembly of the Baijiu cultivar Hongyingzi,HYZ-T2T,using ultralong reads.The 10 chromosome pairs contained 33,462 genes,of which 93%were functionally annotated.The 20 telomeres and 10 centromeric regions on the HYZ-T2T chromosomes were predicted and two consecutive large inversions on chromosome 2 were characterized.A 65-gene reconstruction of the metabolic pathway of tannins,the flavor substances in Baijiu,was performed and may advance the breeding of sorghum cultivars for Baijiu production. 展开更多
关键词 SORGHUM Telomere-to-telomere assembly Hongyingzi(HYZ) Chinese Baijiu-making cultivar
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Defects evolution in n-type 4H-SiC induced by electron irradiation and annealing
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作者 Huifan Xiong xuesong Lu +5 位作者 xu gao Yuchao Yan Shuai Liu Lihui Song Deren Yang Xiaodong Pi 《Journal of Semiconductors》 EI CAS CSCD 2024年第7期77-83,共7页
Radiation damage produced in 4H-SiC by electrons of different doses is presented by using multiple characterization techniques. Raman spectra results indicate that SiC crystal structures are essentially impervious to ... Radiation damage produced in 4H-SiC by electrons of different doses is presented by using multiple characterization techniques. Raman spectra results indicate that SiC crystal structures are essentially impervious to 10 Me V electron irradiation with doses up to 3000 kGy. However, irradiation indeed leads to the generation of various defects, which are evaluated through photoluminescence(PL) and deep level transient spectroscopy(DLTS). The PL spectra feature a prominent broad band centered at 500 nm, accompanied by several smaller peaks ranging from 660 to 808 nm. The intensity of each PL peak demonstrates a linear correlation with the irradiation dose, indicating a proportional increase in defect concentration during irradiation. The DLTS spectra reveal several thermally unstable and stable defects that exhibit similarities at low irradiation doses.Notably, after irradiating at the higher dose of 1000 kGy, a new stable defect labeled as R_(2)(Ec-0.51 eV) appeared after annealing at 800 K. Furthermore, the impact of irradiation-induced defects on SiC junction barrier Schottky diodes is discussed. It is observed that high-dose electron irradiation converts SiC n-epilayers to semi-insulating layers. However, subjecting the samples to a temperature of only 800 K results in a significant reduction in resistance due to the annealing out of unstable defects. 展开更多
关键词 4H-SIC deep level transient spectroscopy(DLTS) photoluminescence(PL) DEFECTS
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Current status and prospects of research on safety situation awareness of high speed railway operation environment
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作者 Tianyun Shi Zhoulong Wang +4 位作者 Jia You Pengyue Guo Lili Jiang Huijin Fu xu gao 《Railway Sciences》 2024年第4期453-468,共16页
Purpose–The safety of high-speed rail operation environments is an important guarantee for the safe operation of high-speed rail.The operating environment of the high-speed rail is complex,and the main factors affect... Purpose–The safety of high-speed rail operation environments is an important guarantee for the safe operation of high-speed rail.The operating environment of the high-speed rail is complex,and the main factors affecting the safety of high-speed rail operating environment include meteorological disasters,perimeter intrusion and external environmental hazards.The purpose of the paper is to elaborate on the current research status and team research progress on the perception of safety situation in high-speed rail operation environment and to propose directions for further research in the future.Design/methodology/approach–In terms of the mechanism and spatio-temporal evolution law of the main influencing factors on the safety of high-speed rail operation environments,the research status is elaborated,and the latest research progress and achievements of the team are introduced.This paper elaborates on the research status and introduces the latest research progress and achievements of the team in terms of meteorological,perimeter and external environmental situation perception methods for high-speed rail operation.Findings–Based on the technical route of“situational awareness evaluation warning active control,”a technical system for monitoring the safety of high-speed train operation environments has been formed.Relevant theoretical and technical research and application have been carried out around the impact of meteorological disasters,perimeter intrusion and the external environment on high-speed rail safety.These works strongly support the improvement of China’s railway environmental safety guarantee technology.Originality/value–With the operation of CR450 high-speed trains with a speed of 400 kmper hour and the application of high-speed train autonomous driving technology in the future,new and higher requirements have been put forward for the safety of high-speed rail operation environments.The following five aspects of work are urgently needed:(1)Research the single factor disaster mechanism of wind,rain,snow,lightning,etc.for high-speed railways with a speed of 400 kms per hour,and based on this,study the evolution characteristics of multiple safety factors and the correlation between the high-speed driving safety environment,revealing the coupling disastermechanism ofmultiple influencing factors;(2)Research covers multi-source data fusion methods and associated features such as disaster monitoring data,meteorological information,route characteristics and terrain and landforms,studying the spatio-temporal evolution laws of meteorological disasters,perimeter intrusions and external environmental hazards;(3)In terms of meteorological disaster situation awareness,research high-precision prediction methods for meteorological information time series along high-speed rail lines and study the realization of small-scale real-time dynamic and accurate prediction of meteorological disasters along high-speed rail lines;(4)In terms of perimeter intrusion,research amulti-modal fusion perception method for typical scenarios of high-speed rail operation in all time,all weather and all coverage and combine artificial intelligence technology to achieve comprehensive and accurate perception of perimeter security risks along the high-speed rail line and(5)In terms of external environment,based on the existing general network framework for change detection,we will carry out research on change detection and algorithms in the surrounding environment of highspeed rail. 展开更多
关键词 High-speed rail operating environment Situation awareness Meteorological disasters Perimeter invasion External environment
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一种基于红外图像特征融合的高温铝液模拟泄漏监测算法 被引量:6
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作者 张永明 王克威 +3 位作者 张启兴 徐高 王文佳 霍一诺 《安全与环境学报》 CAS CSCD 北大核心 2020年第2期518-523,共6页
高温熔融铝液泄漏是炼铝工业最严重的危害之一。借助FLIR A310红外热像仪开展试验研究,搭建了高温铝液泄漏模拟试验平台,建立模拟泄漏标准数据集,提出了一种基于红外图像特征融合的高温铝液模拟泄漏监测算法。利用HOG和LSS描述子分别提... 高温熔融铝液泄漏是炼铝工业最严重的危害之一。借助FLIR A310红外热像仪开展试验研究,搭建了高温铝液泄漏模拟试验平台,建立模拟泄漏标准数据集,提出了一种基于红外图像特征融合的高温铝液模拟泄漏监测算法。利用HOG和LSS描述子分别提取图像梯度边缘和相似形状等几何特征并进行特征向量融合,弥补HOG单一特征检测的不足,将融合的特征向量送入训练好的RBF核函数支持向量机分类识别。融合算法试验性能最优,测试集的查准率、查全率和F1分别为94.31%、93.52%和93.91%。LSS的高维特征向量影响监测时间,步长为15、维度为5280时,可以实现特征降维与识别准确率的平衡。最后,探究了特征融合描述子对相机距离的敏感性,3.5 m可实现最佳识别效果;200张图片的监测时间稳定在48.59 s左右。 展开更多
关键词 安全工程 方向梯度直方图 局部自相似描述子 特征融合 铝液泄漏监测
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人工智能图像识别在水利行业的应用进展 被引量:18
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作者 李涛 徐高 +3 位作者 梁思涵 李英睿 王敏 李冰 《人民黄河》 CAS 北大核心 2022年第11期163-168,共6页
图像识别作为人工智能的关键技术之一,被广泛应用于各个行业,水利数字化、智能化的发展离不开人工智能图像识别技术的应用。首先概述图像识别技术的发展过程,再详细介绍传统的图像识别技术(统计法、句法识别法和几何变换法),以及引入神... 图像识别作为人工智能的关键技术之一,被广泛应用于各个行业,水利数字化、智能化的发展离不开人工智能图像识别技术的应用。首先概述图像识别技术的发展过程,再详细介绍传统的图像识别技术(统计法、句法识别法和几何变换法),以及引入神经网络算法的图像识别技术(深度置信网络、卷积神经网络、循环神经网络和图卷积神经网络),并对这些技术的优缺点进行比较,最后从河道流速测量、遥感水体识别、水位监测和三维预测4个方面综述人工智能图像识别在水利行业的应用进展,提出提高技术场景适配能力、兼容性和识别精度等将是人工智能图像识别在水利行业应用的发展方向。 展开更多
关键词 人工智能 图像识别 深度学习 神经网络 水利行业
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井下环境固井水泥环射孔冲击破坏实验研究 被引量:3
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作者 逄铭玉 许高 +2 位作者 唐英才 朱秀星 薛世峰 《测井技术》 CAS 2019年第4期348-354,共7页
非常规油气资源开发中,高强度聚能射孔完井导致的油气井水泥环层间封隔与完整性破坏问题严重。设计一种新型柱状水泥环砂岩射孔靶试件,研究井下围压和温度环境工况下射孔水泥环结构破环机理。设计9组靶试样,实验研究水泥材质、水泥厚度... 非常规油气资源开发中,高强度聚能射孔完井导致的油气井水泥环层间封隔与完整性破坏问题严重。设计一种新型柱状水泥环砂岩射孔靶试件,研究井下围压和温度环境工况下射孔水泥环结构破环机理。设计9组靶试样,实验研究水泥材质、水泥厚度、固井缺陷、装药量、射孔弹型号等参数对水泥环结构破坏的影响,采用CT技术分析射孔水泥环结构破坏形式与程度。结果表明,水泥环结构抗射孔冲击能力主要受控于固井缺陷、水泥环材料组织、射孔弹型号和井筒爆轰压力变化。在实验研究基础上将射孔冲击载荷分为射孔侵彻压力和井眼爆轰压力。高速射孔侵彻压力载荷引起射孔周边局部塑性流动损伤、微裂纹和压实,而井筒爆轰压力载荷导致水泥环结构宏观径向裂纹,对结构强度与层间封隔有致命影响。相关的实验数据和认识对理解射孔水泥环结构破坏机理,指导射孔工艺实践具有重要意义。 展开更多
关键词 射孔 水泥环 爆炸冲击载荷 柱状水泥环砂岩靶 破环失效机理
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考虑燃料雾化的气液两相连续旋转爆轰数值模拟 被引量:6
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作者 徐高 翁春生 +2 位作者 康楠 武郁文 郑权 《推进技术》 EI CAS CSCD 北大核心 2022年第1期175-183,共9页
为研究气液两相连续旋转爆轰发动机燃烧室内爆轰波的传播特性,以汽油为燃料,富氧空气为氧化剂,建立了欧拉-拉格朗日模型进行二维数值仿真,其中气相方程采用时空守恒元与求解元方法求解,液相方程采用标准四阶龙格库塔法求解。在两相旋转... 为研究气液两相连续旋转爆轰发动机燃烧室内爆轰波的传播特性,以汽油为燃料,富氧空气为氧化剂,建立了欧拉-拉格朗日模型进行二维数值仿真,其中气相方程采用时空守恒元与求解元方法求解,液相方程采用标准四阶龙格库塔法求解。在两相旋转爆轰模型还考虑了液滴雾化破碎过程。计算结果表明:起爆后形成的初始爆轰波经过初始燃料填充区域后逐渐衰减,随后入口附近新生成的压力波经过一系列发展形成了自持稳定传播的旋转爆轰波;旋转爆轰波的传播模态受燃料与氧化剂的喷注压力和氧化剂填充比影响,在不同工况下旋转爆轰波呈现出4种传播模态,即稳定单波模态、稳定双波模态、不稳定双波模态和不稳定单波模态;在双波模态工况下,燃烧室内初始只形成1个爆轰波,后由入口附近局部爆炸产生的压力波发展为新的爆轰波,转化为双波模态后爆轰波的强度略有下降,但燃烧室整体推力更加平稳。 展开更多
关键词 连续旋转爆轰发动机 两相爆轰 欧拉-拉格朗日模型 雾化 时空守恒元与求解元方法 传播模态
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气相与液相两相连续旋转爆轰发动机二维数值模拟 被引量:3
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作者 徐高 翁春生 +2 位作者 武郁文 郑权 白桥栋 《兵工学报》 EI CAS CSCD 北大核心 2020年第S01期21-29,共9页
为了研究气相与液相两相连续旋转爆轰发动机爆轰波传播特性及内流场结构,建立气相与液相两相爆轰欧拉-拉格朗日模型,模型中考虑了液态燃料的喷射雾化过程。采用时空守恒元与求解元方法和标准4阶Runge-Kutta法分别求解气相和液相控制方程... 为了研究气相与液相两相连续旋转爆轰发动机爆轰波传播特性及内流场结构,建立气相与液相两相爆轰欧拉-拉格朗日模型,模型中考虑了液态燃料的喷射雾化过程。采用时空守恒元与求解元方法和标准4阶Runge-Kutta法分别求解气相和液相控制方程,并对计算得到的燃烧室内流场参数分布进行分析。计算结果表明:最终在燃烧室入口附近形成了连续传播的旋转爆轰波;爆轰波和斜激波分别造成了入口边界和出口边界上的参数间断;旋转爆轰波在传播过程中强度会不断变化。 展开更多
关键词 连续旋转爆轰发动机 气相与液相两相 喷射雾化 时空守恒元与求解元方法 欧拉-拉格朗日模型
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基于边界图卷积的机器人行驶路障场景解析 被引量:1
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作者 徐高 周武杰 叶绿 《浙江科技学院学报》 CAS 2023年第5期402-411,共10页
【目的】为了使地面机器人行驶过程中能准确识别出路障以避免发生碰撞,提出一种边界图卷积双向监督网络(boundary-graph convolution bidirectional supervised network,B-GCBSNet)的场景解析算法。【方法】首先使用统一变换器(unified ... 【目的】为了使地面机器人行驶过程中能准确识别出路障以避免发生碰撞,提出一种边界图卷积双向监督网络(boundary-graph convolution bidirectional supervised network,B-GCBSNet)的场景解析算法。【方法】首先使用统一变换器(unified transformer,UniFormer)作为主干网络分别对输入的RGB(red,green,blue,红绿蓝)图像和深度图像进行特征提取;其次利用设计的多模态上下文融合模块(multimodal context fusion module,MCFM)将深度图包含的丰富空间信息补充给RGB图以提取更丰富的语义特征,在解码阶段设计了双向监督模块(bidirectional supervision module,BSM);再次,将含有更多全局信息的低级特征进行边缘化处理以得到边界信息,并通过二分类交叉熵损失函数(binary cross entropy loss,BCELoss)进行监督,而包含更多局部信息的高级特征,则通过图卷积来补充特征的全局上下文,以弥补传统卷积神经网络(convolutional neural network,CNN)提取高级特征时忽略局部位置信息的不足,并通过多分类交叉熵损失函数(cross entropy loss,CELoss)进行监督;最后将边界特征和分割特征进行整合得到最终的场景解析结果。【结果】在机器人行驶路障场景数据集(ground mobile robot perception,GMRP)上进行了试验,与已有的先进方法相比,B-GCBSNet的平均交并比(mean intersection over union,MIoU)达到了93.54%,平均类别准确率(mean classification accuracy,mAcc)达到了98.89%,像素准确率(pixel accuracy,PA)达到了98.85%。【结论】B-GCBSNet能较为准确地识别障碍物及可行驶道路,从而为地面机器人行驶过程中障碍物的识别研究提供了参考。 展开更多
关键词 场景解析 边界监督 多尺度 上下文 图卷积
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二十世纪二十年代中美两国的“反赤化”问题研究 被引量:2
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作者 徐高 《中共党史研究》 CSSCI 北大核心 2020年第2期60-75,共16页
1917年俄国十月革命后,革命思想主要通过中俄边境传入中国内地,引发意识形态领域的分化。从长远看,其结果不仅威胁到北京政府的统治,也对美国在东亚地区建立的华盛顿体系构成了挑战。20世纪20年代后期,随着南方革命势力的兴起,中国北方... 1917年俄国十月革命后,革命思想主要通过中俄边境传入中国内地,引发意识形态领域的分化。从长远看,其结果不仅威胁到北京政府的统治,也对美国在东亚地区建立的华盛顿体系构成了挑战。20世纪20年代后期,随着南方革命势力的兴起,中国北方军阀开始在“反赤化”的旗帜下联合起来。与此同时,美国在国内镇压“赤色恐怖”行动,在国际上以“反赤化”所裹挟着的国家利益为借口联合英国、日本等国阻止中国的“赤化”,维护华盛顿体系。北伐前夕,北京政府与美国从各自利益出发,以“反赤化”为意识形态的共同诉求,将实际政治、经济利益加持其中,造成这一时期中美关系呈现前所未有的复杂面相。 展开更多
关键词 北京政府 “反赤化” 中美关系 华盛顿体系
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旋转爆轰燃烧室壁面传热特性数值模拟 被引量:1
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作者 邱彦铭 武郁文 +4 位作者 康朝辉 雷特 李群 徐高 翁春生 《推进技术》 EI CAS CSCD 北大核心 2023年第10期140-152,共13页
为研究旋转爆轰燃烧室的壁面传热特性,对H2/Air旋转爆轰燃烧室进行了三维共轭传热模拟研究。建立了带壁面的燃烧室模型,采用密度基求解非稳态RANS方程,选用标准k-ε湍流模型,利用能量方程和流固界面的Interface边界条件实现壁面耦合传热... 为研究旋转爆轰燃烧室的壁面传热特性,对H2/Air旋转爆轰燃烧室进行了三维共轭传热模拟研究。建立了带壁面的燃烧室模型,采用密度基求解非稳态RANS方程,选用标准k-ε湍流模型,利用能量方程和流固界面的Interface边界条件实现壁面耦合传热,研究了旋转爆轰燃烧室非稳态流场及壁面传热特性分布。结果表明,流场中温度升高的原因包括化学反应和流体压缩两种机制。燃烧室头部附近壁面存在环形高温带,壁面温度沿轴向先上升后下降,爆轰波与斜激波交汇处附近温度最高。壁面热流密度则在头部最高,沿轴向逐渐降低。在除头部以外的其他部分,壁面换热系数沿轴向下降,进一步说明了壁面热流密度受燃烧室内部压力的影响。预混条件下,当量比越接近1.0、质量流量越大,燃烧室壁面温度越高且越集中于头部,高热流密度区域的轴向深度越短,极限热流密度越高。 展开更多
关键词 旋转爆轰燃烧室 热环境 热流密度 换热系数 共轭传热模拟
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Analytical solutions for characteristic radii of circular roadway surrounding rock plastic zone and their application 被引量:17
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作者 Xiaofei Guo Zhiqiang Zhao +2 位作者 xu gao Xiangye Wu Nianjie Ma 《International Journal of Mining Science and Technology》 SCIE EI CSCD 2019年第2期263-272,共10页
In the non-uniform stress field, the surrounding rock plastic zone of the circular roadway shows different shapes under the different confining pressure conditions. Based on the boundary shape characteristics of the p... In the non-uniform stress field, the surrounding rock plastic zone of the circular roadway shows different shapes under the different confining pressure conditions. Based on the boundary shape characteristics of the plastic zone, the characteristic radii of the plastic zone were proposed, namely the horizontal,longitudinal and medial axis radii, which could reflect the plastic zone shapes characteristics and classify the sizes of the key parts. On the theoretical basis of elastic-plastic mechanics, analytical solutions for the characteristic radii were obtained by theoretical deduction, and the relationships between the characteristic radii and key influencing factors were analyzed. Finally, the evaluation criterion of the circular roadway surrounding rock plastic zone shapes, evaluation criterion of the location of potential hazards caused by the roadway surrounding rock and evaluation critical points of roadway dynamic disasters based on characteristic radii were proposed. This work could provide a theoretical basis for stability analysis of the surrounding rock, support design, and guide the prevention and control of dynamic roadway disasters. 展开更多
关键词 INHOMOGENEOUS stress field Analytical solutions CHARACTERISTIC RADII Morphological identification Disaster area
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Prostate cancer in Asia:A collaborative report 被引量:39
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作者 Rui Chen Shancheng Ren +44 位作者 Ming Kwong Yiu Ng Chi Fai Wai Sam Cheng Lap Hong Ian Seiji Naito Tadashi Matsuda Elijah Kehinde Ali Kural Jason Yichun Chiu Rainy Umbas Qiang Wei Xiaolei Shi Liqun Zhou Jian Huang Yiran Huang Liping Xie Lulin Ma Changjun Yin Danfeng xu Kexin xu Zhangqun Ye Chunxiao Liu Dingwei Ye Xin gao Qiang Fu Jianquan Hou Jianlin Yuan Dalin He Tiejun Pan Qiang Ding Fengshuo Jin Benkang Shi Gongxian Wang Xiuheng Liu Dongwen Wang Zhoujun Shen Xiangbo Kong Wanhai xu Yaoliang Deng Haibo Xia Alexa NCohen xu gao Chuanliang xu Yinghao Sun 《Asian Journal of Urology》 2014年第1期15-29,共15页
The incidence of prostate cancer(PCa)within Asian population used to be much lower than in the Western population;however,in recent years the incidence and mortality rate of PCa in some Asian countries have grown rapi... The incidence of prostate cancer(PCa)within Asian population used to be much lower than in the Western population;however,in recent years the incidence and mortality rate of PCa in some Asian countries have grown rapidly.This collaborative report summarized the latest epidemiology information,risk factors,and racial differences in PCa diagnosis,current status and new trends in surgery management and novel agents for castration-resistant prostate cancer.We believe such information would be helpful in clinical decision making for urologists and oncologists,health-care ministries and medical researchers. 展开更多
关键词 Prostate cancer Asian population EPIDEMIOLOGY Risk factors Racial differences Surgery management
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矿物地球化学勘查方法在鄂东南地区深部找矿中的初步应用 被引量:2
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作者 许高 张世涛 +4 位作者 陈华勇 金尚刚 魏克涛 张宇 李书涛 《资源环境与工程》 2018年第4期681-687,共7页
矿物地球化学勘查是目前国际上新兴的矿产勘查方法之一,主要运用于斑岩型和浅成低温热液矿床以及火山成因块状硫化物矿床(VMS)中,而在其它类型矿床中运用较少。鄂东南地区是中国东部著名的矽卡岩型铜铁金成矿密集的大型矿集区,区内产有... 矿物地球化学勘查是目前国际上新兴的矿产勘查方法之一,主要运用于斑岩型和浅成低温热液矿床以及火山成因块状硫化物矿床(VMS)中,而在其它类型矿床中运用较少。鄂东南地区是中国东部著名的矽卡岩型铜铁金成矿密集的大型矿集区,区内产有铜绿山、鸡冠咀、程潮、铁山、铜山口、金山店、阮家湾等大型矽卡岩矿床。简要介绍铜绿山铜铁金矿床和鸡冠咀铜金矿床近年来的深部勘查进展,通过野外钻孔岩芯编录、蚀变矿物SWIR填图及光谱特征参数以及绿泥石化学成分组成等研究,初步建立铜绿山矿床和鸡冠咀矿床的新矿物勘查标志体系,并初步应用于铜绿山矿区深部矿体的勘查和验证工作,取得了良好的效果,认为在鄂东南地区大型矿区深部和边部,沿着有利的控矿构造部位,特别是矽卡岩化和粘土矿化蚀变增强的空间位置仍具有较大找矿潜力。 展开更多
关键词 蚀变矿物 勘查标志 矽卡岩型矿床 深部找矿 鄂东南矿集区
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