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Electrostatic Attraction and Repulsion Explained and Modelled Mathematically Using Classical Physics—A Detailed Mechanism Based on Particle Wave Functions
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作者 Declan Traill 《Journal of Applied Mathematics and Physics》 2024年第4期1050-1062,共13页
The phenomenon of electrical attraction and repulsion between charged particles is well known, and described mathematically by Coulomb’s Law, yet until now there has been no explanation for why this occurs. There has... The phenomenon of electrical attraction and repulsion between charged particles is well known, and described mathematically by Coulomb’s Law, yet until now there has been no explanation for why this occurs. There has been no mechanistic explanation that reveals what causes the charged particles to accelerate, either towards or away from each other. This paper gives a detailed explanation of the phenomena of electrical attraction and repulsion based on my previous work that determined the exact wave-function solutions for both the Electron and the Positron. It is revealed that the effects are caused by wave interactions between the wave functions that result in Electromagnetic reflections of parts of the particle’s wave functions, causing a change in their momenta. 展开更多
关键词 ELECTROSTATIC Electron POSITRON COULOMB Force ATTRACTION REPULSION Wave Function Electric Magnetic Radiation Pressure Shell THEOREM 3D Computer Model Quantum
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The in situ observation of modelled sea ice drift characteristics in the Bohai Sea 被引量:4
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作者 Yu Yan Wei Gu +1 位作者 Yingjun Xu Qian Li 《Acta Oceanologica Sinica》 SCIE CAS CSCD 2019年第3期17-25,共9页
Sea ice drift is mainly controlled by ocean currents, local wind, and internal ice stress. Information on sea ice motion, especially in situ synchronous observation of an ice velocity, a current velocity, and a wind s... Sea ice drift is mainly controlled by ocean currents, local wind, and internal ice stress. Information on sea ice motion, especially in situ synchronous observation of an ice velocity, a current velocity, and a wind speed, is of great significance to identify ice drift characteristics. A sea ice substitute, the so-called "modelled ice", which is made by polypropylene material with a density similar to Bohai Sea ice, is used to complete a free drift experiment in the open sea. The trajectories of isolated modelled ice, currents and wind in the Bohai Sea during non-frozen and frozen periods are obtained. The results show that the currents play a major role while the wind plays a minor role in the free drift of isolated modelled ice when the wind is mild in the Bohai Sea. The modelled ice drift is significantly affected by the ocean current and wind based on the ice–current–wind relationship established by a multiple linear regression. The modelled ice velocity calculated by the multiple linear regression is close to that of the in situ observation, the magnitude of the error between the calculated and observed ice velocities is less than12.05%, and the velocity direction error is less than 6.21°. Thus, the ice velocity can be estimated based on the observed current velocity and wind speed when the in situ observed ice velocity is missing. And the modelled ice of same thickness with a smaller density is more sensitive to the current velocity and the wind speed changes. In addition, the modelled ice drift characteristics are shown to be close to those of the real sea ice, which indicates that the modelled ice can be used as a good substitute of real ice for in situ observation of the free ice drift in the open sea, which helps solve time availability, safety and logistics problems related to in situ observation on real ice. 展开更多
关键词 Bohai SEA modelled ICE in SITU observation SEA ICE DRIFT
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Analysis of Observed and Modelled Near-Surface Wind Extremes over the Sub-Arctic Northeast Pacific 被引量:1
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作者 Alexander Kislov Vladimir Platonov 《Atmospheric and Climate Sciences》 2019年第1期146-158,共13页
Wind speed extremes in the sub-Arctic realm of the North-East Pacific region were investigated through extreme value analysis of wind speed obtained from wind simulations of the COSMO-CLM (Consortium for Small-scale M... Wind speed extremes in the sub-Arctic realm of the North-East Pacific region were investigated through extreme value analysis of wind speed obtained from wind simulations of the COSMO-CLM (Consortium for Small-scale Modelling, climate version) mesoscale model, as well as using observed data. The analysis showed that the set of wind speed extremes obtained from observations is a mixture of two different subsets each neatly described by the Weibull distribution. Using special metaphoric terminology, they are labelled as “Black Swans” and “Dragons”. The “Dragons” are responsible for strongest extremes. It has been shown that both reanalysis and GCM (general circulation model) data have no “Dragons”. This means that such models underestimate wind speed maxima, and the important circulation process generating the anomalies is not simulated. The COSMO-CLM data have both “Black Swans” and “Dragons”. This evidence provides a clue that an atmospheric model with a detailed spatial resolution (we used in this work the data from domain with 13.2 km spatial resolution) does reproduce the special mechanism responsible for the generation of the largest wind speed extremes. However, a more thorough analysis shows that the differences in the parameters of the cumulative distribution functions are still significant. The ratio between the modelled Dragons and Black Swans can reach up to only 10%. It is much less than 30%, which was the level established for observations. 展开更多
关键词 EXTREME WIND SPEED ANALYSIS modelled EXTREME WIND SPEED Arctic and SUB-ARCTIC Circulation
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Beam Approximation for Dynamic Analysis of Launch Vehicles Modelled as Stiffened Cylindrical Shells 被引量:2
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作者 Siyang Piao Huajiang Ouyang Yahui Zhang 《Computer Modeling in Engineering & Sciences》 SCIE EI 2020年第2期571-591,共21页
A beam approximation method for dynamic analysis of launch vehicles modelled as stiffened cylindrical shells is proposed.Firstly,an initial beam model of the stiffened cylindrical shell is established based on the cro... A beam approximation method for dynamic analysis of launch vehicles modelled as stiffened cylindrical shells is proposed.Firstly,an initial beam model of the stiffened cylindrical shell is established based on the cross-sectional area equivalence principle that represents the shell skin and its longitudinal ribs as a beam with annular cross-section,and the circumferential ribs as lumped masses at the nodes of the beam elements.Then,a fine finite element model(FE model)of the stiffened cylindrical shell is constructed and a modal analysis is carried out.Finally,the initial beam model is improved through model updating against the natural frequencies and mode shapes of the fine FE model of the shell.To facilitate the comparison between the mode shapes of the fine FE model of the stiffened shell and the equivalent beam model,a weighted nodal displacement coupling relationship is introduced.To prevent the design parameters used in model updating from converging to incorrect values,a pre-model updating procedure is added before the proper model updating.The results of two examples demonstrate that the beam approximation method presented in this paper can build equivalent beam models of stiffened cylindrical shells which can reflect the global longitudinal,lateral and torsional vibration characteristics very well in terms of the natural frequencies. 展开更多
关键词 Finite element method model updating stiffened shell beam approximation model reduction.
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Spatio-temporal Changes and Associated Uncertainties of CENTURYmodelled SOC for Chinese Upland Soils, 1980-2010
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作者 LIU Xiaoyu ZHAO Yongcun +3 位作者 SHI Xuezheng WANG Shihang FENG Xiang YAN Fang 《Chinese Geographical Science》 SCIE CSCD 2021年第1期126-136,共11页
Detailed information on the spatio-temporal changes of cropland soil organic carbon(SOC) can significantly contribute to the improvement of soil fertility and mitigate climate change. Nonetheless, information and know... Detailed information on the spatio-temporal changes of cropland soil organic carbon(SOC) can significantly contribute to the improvement of soil fertility and mitigate climate change. Nonetheless, information and knowledge on the national scale spatio-temporal changes and the corresponding uncertainties of SOC in Chinese upland soils remain limited. The CENTURY model was used to estimate the SOC storages and their changes in Chinese uplands from 1980 to 2010. With the Monte Carlo method, the uncertainties of CENTURY-modelled SOC dynamics associated with the spatial heterogeneous model inputs were quantified. Results revealed that the SOC storage in Chinese uplands increased from 3.03(1.59 to 4.78) Pg C in 1980 to 3.40(2.39 to 4.62) Pg C in 2010. Increment of SOC storage during this period was 370 Tg C, with an uncertainty interval of –440 to 1110 Tg C. The regional disparities of SOC changes reached a significant level, with considerable SOC accumulation in the Huang-Huai-Hai Plain of China and SOC loss in the northeastern China. The SOC lost from Meadow soils, Black soils and Chernozems was most severe, whilst SOC accumulation in Fluvo-aquic soils, Cinnamon soils and Purplish soils was most significant. In modelling large-scale SOC dynamics, the initial soil properties were major sources of uncertainty. Hence, more detailed information concerning the soil properties must be collected. The SOC stock of Chinese uplands in 2010 was still relatively low, manifesting that recommended agricultural management practices in conjunction with effectively economic and policy incentives to farmers for soil fertility improvement were indispensable for future carbon sequestration in these regions. 展开更多
关键词 soil organic carbon(SOC) CENTURY model uncertainty analysis heterogeneous model input data spatio-temporal change
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Dynamic properties of structures with dampers modelled using fractional order derivatives
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作者 Zdzislaw Pawlak Roman Lewandowski 《Open Journal of Applied Sciences》 2012年第4期138-142,共5页
The focus of this paper is on determination of the dynamic parameters of structural systems with viscoelastic (VE) dampers described by Maxwell rheological models. Such parameters could be obtained after solving the a... The focus of this paper is on determination of the dynamic parameters of structural systems with viscoelastic (VE) dampers described by Maxwell rheological models. Such parameters could be obtained after solving the appropriately defined nonlinear eigenvalue problem for frames with VE dampers. The solution to the nonlinear eigenvalue problem is obtained by equating to zero the determinant of the considered system of equations. Apart from complex conjugate eigenvalues, the real ones occurred when dampers that are described by the classic Maxwell model, are also determined. 展开更多
关键词 viscoelastic damper rheological model fractional derivative nonlinear eigenvalue problem dynamic properties
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酒精性肝病中医病机治法及中药防治规律的多维度分析
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作者 张金保 杨宗慧 +5 位作者 其乐木格 吴月 段海婧 陈红刚 赵文龙 王倩 《中国中医药科技》 CAS 2024年第2期373-378,F0003,共7页
目的:分析酒精性肝病(alcoholic liver disease,ALD)中医病机、治法及中药防治规律。方法:筛选CNKI、维普网、万方数据库中有关中医药治疗ALD的文献,并建立数据库。通过Excel、GraphPad Prism、VOS viewer和SPSS Modeler软件进行数据统... 目的:分析酒精性肝病(alcoholic liver disease,ALD)中医病机、治法及中药防治规律。方法:筛选CNKI、维普网、万方数据库中有关中医药治疗ALD的文献,并建立数据库。通过Excel、GraphPad Prism、VOS viewer和SPSS Modeler软件进行数据统计,分别从ALD中医病机、治法及用药规律3个维度可视化分析。结果:共检索得到相关文献1890篇,根据纳排标准筛选后,最终纳入文献312篇。分析显示偏嗜饮酒、瘀血、痰饮是引发ALD的主要病因,气滞血瘀、肝郁脾虚、痰凝水停、湿热内蕴、湿困脾胃是该病的主要病机,应采取行气活血、疏肝健脾、化痰利水、清热解毒、化湿醒脾等治法。按疾病发展阶段分析可知,初期过度饮酒,酒毒湿热内蕴致脾失健运、肝气郁结,治宜解毒化湿、健脾疏肝;中期气滞日久,血行不畅,瘀血内停,气血湿热酒毒相互搏结,治宜行气活血、解毒利湿;末期气血湿热酒毒相互搏结日久,气滞、血瘀、水停,久病及肾,肝脾肾同病,治宜扶正祛邪、攻补兼施。用药规律分析显示,丹参、茯苓、柴胡、葛根、甘草及山楂等应用频次较高,配伍较多的是补益、利水渗湿、活血化瘀、解表、清热及理气等功效类药。关联规则分析显示,关联度最高的两药组合是葛花和砂仁,三药组合是丹参、山楂和泽泻,四药组合为丹参、山楂、柴胡和泽泻。结论:本研究全面分析了ALD中医病机及治法,并揭示了中药防治配伍规律,可为深入开展中医药防治ALD研究提供一定借鉴。 展开更多
关键词 酒精性肝病 中医药 病机 治法 用药规律 数据挖掘 VOS viewer SPSS Modeler
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采用STAMP-24Model的多组织事故分析
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作者 曾明荣 秦永莹 +2 位作者 刘小航 栗婧 尚长岭 《安全与环境学报》 CAS CSCD 北大核心 2024年第7期2741-2750,共10页
安全生产事故往往由多组织交互、多因素耦合造成,事故原因涉及多个组织。为预防和遏制多组织生产安全事故的发生,基于系统理论事故建模与过程模型(Systems-Theory Accident Modeling and Process,STAMP)、24Model,构建一种用于多组织事... 安全生产事故往往由多组织交互、多因素耦合造成,事故原因涉及多个组织。为预防和遏制多组织生产安全事故的发生,基于系统理论事故建模与过程模型(Systems-Theory Accident Modeling and Process,STAMP)、24Model,构建一种用于多组织事故分析的方法,并以青岛石油爆炸事故为例进行事故原因分析。结果显示:STAMP-24Model可以分组织,分层次且有效、全面、详细地分析涉及多个组织的事故原因,探究多组织之间的交互关系;对事故进行动态演化分析,可得到各组织不安全动作耦合关系与形成的事故失效链及管控失效路径,进而为预防多组织事故提供思路和参考。 展开更多
关键词 安全工程 系统理论事故建模与过程模型(STAMP) 24Model 多组织事故 原因分析
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基于改进24Model-ISM-SNA建筑工人不安全行为关联路径研究
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作者 赵平 刘钰 +1 位作者 靳丽艳 王佳慧 《工业安全与环保》 2024年第7期37-40,共4页
建筑施工现场环境复杂,为有效控制不安全行为发生,基于行为安全“2-4”模型对360份具有代表性的建筑安全事故调查报告进行分析,提取出22个不安全行为的主要影响因素。利用灰色关联分析方法(GRA)改进的集成ISM-SNA模型,将不安全行为风险... 建筑施工现场环境复杂,为有效控制不安全行为发生,基于行为安全“2-4”模型对360份具有代表性的建筑安全事故调查报告进行分析,提取出22个不安全行为的主要影响因素。利用灰色关联分析方法(GRA)改进的集成ISM-SNA模型,将不安全行为风险因素划分为表层、过渡层与深层,然后对风险因素进行可视化分析、中心度分析及凝聚子群分析,揭示了各致因因素间的关联关系和传导路径。结果表明,建筑工人不安全行为影响因素可划分成7级3阶的多级递阶结构,安全意识、现场监管、外部环境是建筑工人不安全行为的关键影响因素,同时现场监管和隐患排查到位能有效降低不安全行为的发生。 展开更多
关键词 建筑工人 不安全行为 24Model 解释结构模型(ISM) 社会网络分析(SNA)
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复杂系统视角下洞室施工人员安全认知仿真研究
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作者 江新 张腾飞 +3 位作者 陈婧 赵力 邱国坤 王辉 《中国安全科学学报》 CAS CSCD 北大核心 2024年第2期22-30,共9页
为制定有效的安全认知提升策略及减少安全事故的发生,需深入探究洞室施工人员安全认知的演化过程和特征。首先,基于复杂社会技术系统和“2-4”模型(24Model)等相关知识,识别安全认知影响因素,构建洞室施工人员安全认知指标体系;然后,通... 为制定有效的安全认知提升策略及减少安全事故的发生,需深入探究洞室施工人员安全认知的演化过程和特征。首先,基于复杂社会技术系统和“2-4”模型(24Model)等相关知识,识别安全认知影响因素,构建洞室施工人员安全认知指标体系;然后,通过Super Decisions软件计算指标权重;随后利用系统动力学(SD)理论,明确各因素间的相互关系,建立包含组织安全管理等4个子系统的SD仿真模型,将以安全投入为基础的认知纠偏机制应用到SD仿真模型;最后,结合实际工程算例开展SD仿真以及敏感性分析。研究表明:随着工程进展,通过增加安全投入,并发挥认知纠偏机制作用,施工人员的整体安全认知由下降趋势转变为缓慢上升趋势;组织安全管理对洞室施工人员安全认知影响程度最大,结果与24Model的基本假设一致,从而验证了SD仿真模型的科学性和有效性。 展开更多
关键词 复杂系统 洞室施工人员 安全认知 “2-4”模型(24Model) 系统动力学(SD)
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基于24Model-D-ISM的地铁站火灾疏散影响因素研究
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作者 孙世梅 张家严 《中国安全科学学报》 CAS CSCD 北大核心 2024年第4期153-159,共7页
为预防地铁站火灾事故,深入了解地铁站火灾人员疏散影响因素间的内在联系与层次结构,基于第6版“2-4”模型(24Model)分析63起地铁站火灾疏散事故,充分考虑各个因素之间的交互作用,提取19个影响地铁站人员疏散的关键因素,建立地铁站火灾... 为预防地铁站火灾事故,深入了解地铁站火灾人员疏散影响因素间的内在联系与层次结构,基于第6版“2-4”模型(24Model)分析63起地铁站火灾疏散事故,充分考虑各个因素之间的交互作用,提取19个影响地铁站人员疏散的关键因素,建立地铁站火灾人员疏散影响因素指标体系;采用算子客观赋权法(C-OWA)改进决策试验与评价实验法(DEMATEL),确定地铁站火灾人员疏散的重要影响因素;在此基础上,采用解释结构模型(ISM)分析各个因素间的层次结构及相互作用路径,构建地铁站火灾人员疏散影响因素的多级递阶结构模型。研究结果表明:疏散引导、恐慌从众行为、人员拥挤为地铁站火灾人员疏散的关键影响因素;地铁站火灾人员疏散受表层因素、中间层因素、深层因素共同作用的影响,其中,疏散教育与培训、设施维护与检查、疏散预案等因素是根源影响因素,重视根源影响因素的改善有利于从本质上预防和控制事故的发生。 展开更多
关键词 “2-4”模型(24Model) 决策试验与评价实验法(DEMATEL) 解释结构模型(ISM) 地铁站 火灾疏散 影响因素
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基于综合对抗解释结构模型的煤矿透水事故致因分析
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作者 李琰 刘紫莹 《煤炭技术》 CAS 2024年第1期119-123,共5页
为了更加科学高效地对煤矿透水事故致因进行辨识和分类管理,以2021年丰源煤矿“4·10”重大透水事故为例,运用24Model法对事故致因进行分类提取,采用综合对抗解释结构模型(简称TAISM),对致因进行层级结构划分和因果关系分析。通过... 为了更加科学高效地对煤矿透水事故致因进行辨识和分类管理,以2021年丰源煤矿“4·10”重大透水事故为例,运用24Model法对事故致因进行分类提取,采用综合对抗解释结构模型(简称TAISM),对致因进行层级结构划分和因果关系分析。通过计算得到了该起事故致因的1组7层对抗型有向拓扑层级图。研究结果表明:监督机构监督检查不力、当地政府安全发展意识不强是造成此次事故发生的最根本原因。此外,在事故致因层级图中出现了2个回路,而同一个回路中的不同事故致因存在较强的关联性,应对其进行一体化控制,最大限度减少煤矿安全事故的发生。为今后煤矿事故致因分析提供了新的思路。 展开更多
关键词 煤矿安全 透水事故 致因分析 24Model 综合对抗解释结构模型
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基于Revit平台的隔震支座快速建模模块开发与应用
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作者 陈泽云 陈鑫 +3 位作者 谈丽华 刘涛 唐柏鉴 孙勇 《科学技术与工程》 北大核心 2024年第2期706-714,共9页
随着隔震技术的推广应用以及建筑业信息化水平的持续提升,在隔震工程中对隔震层建筑信息模型(building information modeling, BIM)建模的需求逐渐增长,然而针对性的研究工作相对较少。为此,围绕隔震支座BIM模型的高效建模方法和应用模... 随着隔震技术的推广应用以及建筑业信息化水平的持续提升,在隔震工程中对隔震层建筑信息模型(building information modeling, BIM)建模的需求逐渐增长,然而针对性的研究工作相对较少。为此,围绕隔震支座BIM模型的高效建模方法和应用模块开展了研究。首先,综合隔震支座应用情况和力学特性,可将其分为橡胶隔震支座、滑移摩擦隔震支座和其他类型隔震支座,据此提出了隔震支座BIM快速建模模块基本架构;随后,基于Revit和Visual Studio平台开发了三类隔震支座BIM模型的快速建模功能,并实现了连接节点参数化建模和支座批量/手动布置的操作功能;最后,开展了某化工公司的库房隔震加固项目的隔震层BIM模型建模实践,结果表明:利用快速建模模块可将隔震层BIM建模操作从7个步骤降低至2个步骤,且使用过程中对隔震支座构造细节的认知要求相对较低。同时,建成后的BIM模型与实际工程在建筑信息的多个方面具有较好的一致性。相关研究可为建筑和桥梁隔震工程的BIM建模提供参考和借鉴。 展开更多
关键词 隔震结构 建筑信息模型(building information modeling BIM) REVIT 二次开发 自动化建模
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Effects of mesenchymal stem cell on dopaminergic neurons,motor and memory functions in animal models of Parkinson's disease:a systematic review and meta-analysis 被引量:3
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作者 Jong Mi Park Masoud Rahmati +2 位作者 Sang Chul Lee Jae Il Shin Yong Wook Kim 《Neural Regeneration Research》 SCIE CAS CSCD 2024年第7期1584-1592,共9页
Parkinson’s disease is chara cterized by the loss of dopaminergic neurons in the substantia nigra pars com pacta,and although restoring striatal dopamine levels may improve symptoms,no treatment can cure or reve rse ... Parkinson’s disease is chara cterized by the loss of dopaminergic neurons in the substantia nigra pars com pacta,and although restoring striatal dopamine levels may improve symptoms,no treatment can cure or reve rse the disease itself.Stem cell therapy has a regenerative effect and is being actively studied as a candidate for the treatment of Parkinson’s disease.Mesenchymal stem cells are considered a promising option due to fewer ethical concerns,a lower risk of immune rejection,and a lower risk of teratogenicity.We performed a meta-analysis to evaluate the therapeutic effects of mesenchymal stem cells and their derivatives on motor function,memory,and preservation of dopamine rgic neurons in a Parkinson’s disease animal model.We searched bibliographic databases(PubMed/MEDLINE,Embase,CENTRAL,Scopus,and Web of Science)to identify articles and included only pee r-reviewed in vivo interve ntional animal studies published in any language through J une 28,2023.The study utilized the random-effect model to estimate the 95%confidence intervals(CI)of the standard mean differences(SMD)between the treatment and control groups.We use the systematic review center for laboratory animal expe rimentation’s risk of bias tool and the collaborative approach to meta-analysis and review of animal studies checklist for study quality assessment.A total of 33studies with data from 840 Parkinson’s disease model animals were included in the meta-analysis.Treatment with mesenchymal stem cells significantly improved motor function as assessed by the amphetamine-induced rotational test.Among the stem cell types,the bone marrow MSCs with neurotrophic factor group showed la rgest effect size(SMD[95%CI]=-6.21[-9.50 to-2.93],P=0.0001,I^(2)=0.0%).The stem cell treatment group had significantly more tyrosine hydroxylase positive dopamine rgic neurons in the striatum([95%CI]=1.04[0.59 to 1.49],P=0.0001,I^(2)=65.1%)and substantia nigra(SMD[95%CI]=1.38[0.89 to 1.87],P=0.0001,I^(2)=75.3%),indicating a protective effect on dopaminergic neurons.Subgroup analysis of the amphetamine-induced rotation test showed a significant reduction only in the intracranial-striatum route(SMD[95%CI]=-2.59[-3.25 to-1.94],P=0.0001,I^(2)=74.4%).The memory test showed significant improvement only in the intravenous route(SMD[95%CI]=4.80[1.84 to 7.76],P=0.027,I^(2)=79.6%).Mesenchymal stem cells have been shown to positively impact motor function and memory function and protect dopaminergic neurons in preclinical models of Parkinson’s disease.Further research is required to determine the optimal stem cell types,modifications,transplanted cell numbe rs,and delivery methods for these protocols. 展开更多
关键词 ANIMAL animal experimentation mesenchymal stem cells models Parkinson’s disease stem cell transplantation
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结合SAM视觉分割模型与随机森林机器学习的无人机影像盐沼植被“精灵圈”提取
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作者 周若彤 谭凯 +2 位作者 杨建儒 韩江涛 张卫国 《海洋学报》 CAS CSCD 北大核心 2024年第5期116-126,共11页
“精灵圈”是海岸带盐沼植被生态系统中的一种“空间自组织”结构,对盐沼湿地的生产力、稳定性和恢复力有重要影响。无人机影像是实现“精灵圈”空间位置高精度识别及解译其时空演化趋势与规律的重要数据源,但“精灵圈”像素与背景像素... “精灵圈”是海岸带盐沼植被生态系统中的一种“空间自组织”结构,对盐沼湿地的生产力、稳定性和恢复力有重要影响。无人机影像是实现“精灵圈”空间位置高精度识别及解译其时空演化趋势与规律的重要数据源,但“精灵圈”像素与背景像素在色彩信息和外形特征上差异较小,如何从二维影像中智能精准地识别“精灵圈”像素并对识别的单个像素形成个体“精灵圈”是目前的技术难点。本文提出了一种结合分割万物模型(Segment Anything Model,SAM)视觉分割模型与随机森林机器学习的无人机影像“精灵圈”分割及分类方法,实现了单个“精灵圈”的识别和提取。首先,通过构建索伦森-骰子系数(S?rensen-Dice coefficient,Dice)和交并比(Intersection over Union,IOU)评价指标,从SAM中筛选预训练模型并对其参数进行优化,实现全自动影像分割,得到无属性信息的分割掩码/分割类;然后,利用红、绿、蓝(RGB)三通道信息及空间二维坐标将分割掩码与原图像进行信息匹配,构造分割掩码的特征指标,并根据袋外数据(Out of Bag,OOB)误差减小及特征分布规律对特征进行分析和筛选;最后,利用筛选的特征对随机森林模型进行训练,实现“精灵圈”植被、普通植被和光滩的自动识别与分类。实验结果表明:本文方法“精灵圈”平均正确提取率96.1%,平均错误提取率为9.5%,为精准刻画“精灵圈”时空格局及海岸带无人机遥感图像处理提供了方法和技术支撑。 展开更多
关键词 盐沼植被 精灵圈 segment anything model(SAM) 无人机影像 机器学习
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一种街景图像中建筑物高度估算方法
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作者 戈士博 刘纪平 +1 位作者 王勇 车向红 《遥感信息》 CSCD 北大核心 2024年第3期1-6,共6页
建筑物高度信息是城市三维建模的基础数据,但已有的建筑物高度估算研究多采用LiDAR和SAR等遥感影像。随着计算机和互联网的快速发展,街景数据因采集容易和成本低等特点成为了一种新兴的建筑物高度估算数据源。文章提出一种街景图像中建... 建筑物高度信息是城市三维建模的基础数据,但已有的建筑物高度估算研究多采用LiDAR和SAR等遥感影像。随着计算机和互联网的快速发展,街景数据因采集容易和成本低等特点成为了一种新兴的建筑物高度估算数据源。文章提出一种街景图像中建筑物高度估算方法,首先利用segment anything model实现图像中建筑物像素高度提取;然后利用图像元数据和电子地图数据获取建筑物与相机之间的距离、图像焦距,根据街景图像与建筑物实体的几何关系改进针孔相机模型,构建建筑物高度估算方法;最后选取北京、柏林的Mapillary街景图像开展实验验证。结果表明,与改进前相比,改进后针孔相机模型明显提升了高度估算准确度,RMSE降低了11.31 m,R^(2)提高了0.4,具备实用价值。 展开更多
关键词 街景图像 建筑物高度估算 针孔相机模型 segment anything model Mapillary
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Cell reprogramming therapy for Parkinson’s disease 被引量:4
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作者 Wenjing Dong Shuyi Liu +1 位作者 Shangang Li Zhengbo Wang 《Neural Regeneration Research》 SCIE CAS CSCD 2024年第11期2444-2455,共12页
Parkinson’s disease is typically characterized by the progressive loss of dopaminergic neurons in the substantia nigra pars compacta.Many studies have been performed based on the supplementation of lost dopaminergic ... Parkinson’s disease is typically characterized by the progressive loss of dopaminergic neurons in the substantia nigra pars compacta.Many studies have been performed based on the supplementation of lost dopaminergic neurons to treat Parkinson’s disease.The initial strategy for cell replacement therapy used human fetal ventral midbrain and human embryonic stem cells to treat Parkinson’s disease,which could substantially alleviate the symptoms of Parkinson’s disease in clinical practice.However,ethical issues and tumor formation were limitations of its clinical application.Induced pluripotent stem cells can be acquired without sacrificing human embryos,which eliminates the huge ethical barriers of human stem cell therapy.Another widely considered neuronal regeneration strategy is to directly reprogram fibroblasts and astrocytes into neurons,without the need for intermediate proliferation states,thus avoiding issues of immune rejection and tumor formation.Both induced pluripotent stem cells and direct reprogramming of lineage cells have shown promising results in the treatment of Parkinson’s disease.However,there are also ethical concerns and the risk of tumor formation that need to be addressed.This review highlights the current application status of cell reprogramming in the treatment of Parkinson’s disease,focusing on the use of induced pluripotent stem cells in cell replacement therapy,including preclinical animal models and progress in clinical research.The review also discusses the advancements in direct reprogramming of lineage cells in the treatment of Parkinson’s disease,as well as the controversy surrounding in vivo reprogramming.These findings suggest that cell reprogramming may hold great promise as a potential strategy for treating Parkinson’s disease. 展开更多
关键词 animal models ASTROCYTES AUTOLOGOUS cell reprogramming cell therapy direct lineage reprogramming dopaminergic neurons induced pluripotent stem cells non-human primates Parkinson’s disease
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Converting TREx-RGB green-channel data to 557.7 nm auroral intensity:Methodology and initial results 被引量:2
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作者 Jun Liang D.M.Gillies +1 位作者 E.Spanswick E.F.Donovan 《Earth and Planetary Physics》 EI CSCD 2024年第1期258-274,共17页
The recently deployed Transition Region Explorer(TREx)-RGB(red-green-blue)all-sky imager(ASI)is designed to capture“true color”images of the aurora and airglow.Because the 557.7 nm green line is usually the brightes... The recently deployed Transition Region Explorer(TREx)-RGB(red-green-blue)all-sky imager(ASI)is designed to capture“true color”images of the aurora and airglow.Because the 557.7 nm green line is usually the brightest emission line in visible auroras,the green channel of a TREx-RGB camera is usually dominated by the 557.7 nm emission.Under this rationale,the TREx mission does not include a specific 557.7 nm imager and is designed to use the RGB green-channel data as a proxy for the 557.7 nm aurora.In this study,we present an initial effort to establish the conversion ratio or formula linking the RGB green-channel data to the absolute intensity of 557.7 nm auroras,which is crucial for quantitative uses of the RGB data.We illustrate two approaches:(1)through a comparison with the collocated measurement of green-line auroras from the TREx spectrograph,and(2)through a comparison with the modeled green-line intensity according to realistic electron precipitation flux measurements from low-Earth-orbit satellites,with the aid of an auroral transport model.We demonstrate the procedures and provide initial results for the TREx-RGB ASIs at the Rabbit Lake and Lucky Lake stations.The RGB response is found to be nonlinear.Empirical conversion ratios or formulas between RGB green-channel data and the green-line auroral intensity are given and can be applied immediately by TREx-RGB data users.The methodology established in this study will also be applicable to the upcoming SMILE ASI mission,which will adopt a similar RGB camera system in its deployment. 展开更多
关键词 TREx RGB green-line aurora auroral transport model
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Evolutionary Decision-Making and Planning for Autonomous Driving Based on Safe and Rational Exploration and Exploitation 被引量:2
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作者 Kang Yuan Yanjun Huang +4 位作者 Shuo Yang Zewei Zhou Yulei Wang Dongpu Cao Hong Chen 《Engineering》 SCIE EI CAS CSCD 2024年第2期108-120,共13页
Decision-making and motion planning are extremely important in autonomous driving to ensure safe driving in a real-world environment.This study proposes an online evolutionary decision-making and motion planning frame... Decision-making and motion planning are extremely important in autonomous driving to ensure safe driving in a real-world environment.This study proposes an online evolutionary decision-making and motion planning framework for autonomous driving based on a hybrid data-and model-driven method.First,a data-driven decision-making module based on deep reinforcement learning(DRL)is developed to pursue a rational driving performance as much as possible.Then,model predictive control(MPC)is employed to execute both longitudinal and lateral motion planning tasks.Multiple constraints are defined according to the vehicle’s physical limit to meet the driving task requirements.Finally,two principles of safety and rationality for the self-evolution of autonomous driving are proposed.A motion envelope is established and embedded into a rational exploration and exploitation scheme,which filters out unreasonable experiences by masking unsafe actions so as to collect high-quality training data for the DRL agent.Experiments with a high-fidelity vehicle model and MATLAB/Simulink co-simulation environment are conducted,and the results show that the proposed online-evolution framework is able to generate safer,more rational,and more efficient driving action in a real-world environment. 展开更多
关键词 Autonomous driving DECISION-MAKING Motion planning Deep reinforcement learning Model predictive control
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基于SAM&ImageJ图像处理的堆石混凝土坝层面露石率研究
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作者 安宇 徐小蓉 +2 位作者 尹志刚 金峰 张喜喜 《水资源与水工程学报》 CSCD 北大核心 2024年第1期154-161,共8页
堆石混凝土坝层面的外露块石为上下层提供了重要的啮合作用,其投影面积比例是科学评价层间抗剪性能的重要指标。采用国际最新Meta AI模型segment anything model(SAM)对层面外露堆石进行自动图像分割,并基于ImageJ软件对SAM识别后的图... 堆石混凝土坝层面的外露块石为上下层提供了重要的啮合作用,其投影面积比例是科学评价层间抗剪性能的重要指标。采用国际最新Meta AI模型segment anything model(SAM)对层面外露堆石进行自动图像分割,并基于ImageJ软件对SAM识别后的图片进行再加工与图像计算,利用平滑、差分算法、中值滤波等方法精准标定外露堆石,二值化后计算得到层面露石率。结果表明:SAM图像预分割可识别约90%的外露堆石,经过ImageJ二次图像处理后可有效提高小粒径堆石的识别精度,对比手动标注结果误差在±3%以内。以贵州省两座水库的工程应用为例,对浇筑仓面进行分区预处理,结果发现靠近上游、中部、下游不同区域的露石率差别较大,计算得到的层面露石率以10%~30%居多,其中堆石入仓运输通道区域的露石率较低。研究内容与结论可为堆石混凝土结构层间界面抗剪力学性能和大坝蓄水安全稳定的研究提供参考与借鉴。 展开更多
关键词 堆石混凝土坝 segment anything model(SAM) 图像处理技术 露石率 层间抗剪性能
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