期刊文献+
共找到4,947篇文章
< 1 2 248 >
每页显示 20 50 100
Cellular interplay to 3D in vitro microphysiological disease model:cell patterning microbiota-gut-brain axis 被引量:1
1
作者 Kamare Alam Lakshmi Nair +6 位作者 Souvik Mukherjee Kulwinder Kaur Manjari Singh Santanu Kaity Velayutham Ravichandiran Sugato Banerjee Subhadeep Roy 《Bio-Design and Manufacturing》 SCIE EI CAS CSCD 2024年第3期320-357,共38页
The microbiota-gut-brain axis(MGBA)has emerged as a key prospect in the bidirectional communication between two major organ systems:the brain and the gut.Homeostasis between the two organ systems allows the body to fu... The microbiota-gut-brain axis(MGBA)has emerged as a key prospect in the bidirectional communication between two major organ systems:the brain and the gut.Homeostasis between the two organ systems allows the body to function without disease,whereas dysbiosis has long-standing evidence of etiopathological conditions.The most common communication paths are the microbial release of metabolites,soluble neurotransmitters,and immune cells.However,each pathway is intertwined with a complex one.With the emergence of in vitro models and the popularity of three-dimensional(3D)cultures and Transwells,engineering has become easier for the scientific understanding of neurodegenerative diseases.This paper briefly retraces the possible communication pathways between the gut microbiome and the brain.It further elaborates on three major diseases:autism spectrum disorder,Parkinson’s disease,and Alzheimer’s disease,which are prevalent in children and the elderly.These diseases also decrease patients’quality of life.Hence,understanding them more deeply with respect to current advances in in vitro modeling is crucial for understanding the diseases.Remodeling of MGBA in the laboratory uses many molecular technologies and biomaterial advances.Spheroids and organoids provide a more realistic picture of the cell and tissue structure than monolayers.Combining them with the Transwell system offers the advantage of compartmentalizing the two systems(apical and basal)while allowing physical and chemical cues between them.Cutting-edge technologies,such as bioprinting and microfluidic chips,might be the future of in vitro modeling,as they provide dynamicity. 展开更多
关键词 Microbiota-gut-brain axis Neurodegeneration 3D disease model Organoid Transwell system
下载PDF
Mo掺杂对笼目超导体CsV_(3)Sb_(5)结构和电磁性能的影响
2
作者 李映 向峻杰 +1 位作者 杨帆 陈永亮 《广州化工》 CAS 2024年第8期115-118,141,共5页
新型笼目金属AV_(3)Sb_(5)(A=K, Rb, Cs)作为一个具有多种电子序耦合与竞争的平台,其丰富的物理特性备受关注。本文用新开发的以CsCl为辅助熔剂制备了不同掺Mo含量的Cs(V_(1-x)Mo_(x))3Sb5多晶样品,并通过对XRD数据进行Rietveld分析获... 新型笼目金属AV_(3)Sb_(5)(A=K, Rb, Cs)作为一个具有多种电子序耦合与竞争的平台,其丰富的物理特性备受关注。本文用新开发的以CsCl为辅助熔剂制备了不同掺Mo含量的Cs(V_(1-x)Mo_(x))3Sb5多晶样品,并通过对XRD数据进行Rietveld分析获得了其晶格结构信息,通过测量各样品的磁化强度及电阻率随温度变化关系,对其磁性和电输运性质进行了表征和分析。结果表明,随着Mo的掺入,母相CsV_(3)Sb_(5)的晶格常数a和晶胞体积略微增大,锑烯层中的Sb2原子会逐渐偏离笼目层。同时,体系的超导电性被抑制,而电荷密度波转变温度却增大,二者呈相互竞争关系。 展开更多
关键词 笼目金属 cs(V_(1-x)Mo_(x))_(3)Sb_(5) 晶格结构 电磁性质
下载PDF
3D bioprinting of in vitro porous hepatoma models:establishment,evaluation,and anticancer drug testing
3
作者 Xiaoyuan Wang Zixian Liu +7 位作者 Qianqian Duan Boye Zhang Yanyan Cao Zhizhong Shen Meng Li Yanfeng Xi Jianming Wang Shengbo Sang 《Bio-Design and Manufacturing》 SCIE EI CAS CSCD 2024年第2期137-152,共16页
Traditional tumor models do not tend to accurately simulate tumor growth in vitro or enable personalized treatment and are particularly unable to discover more beneficial targeted drugs.To address this,this study desc... Traditional tumor models do not tend to accurately simulate tumor growth in vitro or enable personalized treatment and are particularly unable to discover more beneficial targeted drugs.To address this,this study describes the use of threedimensional(3D)bioprinting technology to construct a 3D model with human hepatocarcinoma SMMC-7721 cells(3DP-7721)by combining gelatin methacrylate(GelMA)and poly(ethylene oxide)(PEO)as two immiscible aqueous phases to form a bioink and innovatively applying fluorescent carbon quantum dots for long-term tracking of cells.The GelMA(10%,mass fraction)and PEO(1.6%,mass fraction)hydrogel with 3:1 volume ratio offered distinct pore-forming characteristics,satisfactorymechanical properties,and biocompatibility for the creation of the 3DP-7721 model.Immunofluorescence analysis and quantitative real-time fluorescence polymerase chain reaction(PCR)were used to evaluate the biological properties of the model.Compared with the two-dimensional culture cell model(2D-7721)and the 3D mixed culture cell model(3DM-7721),3DP-7721 significantly improved the proliferation of cells and expression of tumor-related proteins and genes.Moreover,we evaluated the differences between the three culture models and the effectiveness of antitumor drugs in the three models and discovered that the efficacy of antitumor drugs varied because of significant differences in resistance proteins and genes between the three models.In addition,the comparison of tumor formation in the three models found that the cells cultured by the 3DP-7721 model had strong tumorigenicity in nude mice.Immunohistochemical evaluation of the levels of biochemical indicators related to the formation of solid tumors showed that the 3DP-7721 model group exhibited pathological characteristics of malignant tumors,the generated solid tumors were similar to actual tumors,and the deterioration was higher.This research therefore acts as a foundation for the application of 3DP-7721 models in drug development research. 展开更多
关键词 3D bioprinting Hepatoma tumor models Drug screening Antitumor drug development
下载PDF
3D Road Network Modeling and Road Structure Recognition in Internet of Vehicles
4
作者 Dun Cao Jia Ru +3 位作者 Jian Qin Amr Tolba Jin Wang Min Zhu 《Computer Modeling in Engineering & Sciences》 SCIE EI 2024年第2期1365-1384,共20页
Internet of Vehicles (IoV) is a new system that enables individual vehicles to connect with nearby vehicles,people, transportation infrastructure, and networks, thereby realizing amore intelligent and efficient transp... Internet of Vehicles (IoV) is a new system that enables individual vehicles to connect with nearby vehicles,people, transportation infrastructure, and networks, thereby realizing amore intelligent and efficient transportationsystem. The movement of vehicles and the three-dimensional (3D) nature of the road network cause the topologicalstructure of IoV to have the high space and time complexity.Network modeling and structure recognition for 3Droads can benefit the description of topological changes for IoV. This paper proposes a 3Dgeneral roadmodel basedon discrete points of roads obtained from GIS. First, the constraints imposed by 3D roads on moving vehicles areanalyzed. Then the effects of road curvature radius (Ra), longitudinal slope (Slo), and length (Len) on speed andacceleration are studied. Finally, a general 3D road network model based on road section features is established.This paper also presents intersection and road section recognition methods based on the structural features ofthe 3D road network model and the road features. Real GIS data from a specific region of Beijing is adopted tocreate the simulation scenario, and the simulation results validate the general 3D road network model and therecognitionmethod. Therefore, thiswork makes contributions to the field of intelligent transportation by providinga comprehensive approach tomodeling the 3Droad network and its topological changes in achieving efficient trafficflowand improved road safety. 展开更多
关键词 Internet of vehicles road networks 3D road model structure recognition GIS
下载PDF
Rainfall-triggered waste dump instability analysis based on surface 3D deformation in physical model test
5
作者 LI Hanlin JIN Xiaoguang +2 位作者 HE Jie XUE Yunchuan YANG Zhongping 《Journal of Mountain Science》 SCIE CSCD 2024年第5期1549-1563,共15页
Landslide is the second largest natural disaster after earthquake. It is of significance to study the evolution laws and failure mechanism of landslides based on its surface 3D deformation information. Based on the ra... Landslide is the second largest natural disaster after earthquake. It is of significance to study the evolution laws and failure mechanism of landslides based on its surface 3D deformation information. Based on the rainfall-triggered waste dump instability model test, we studied the failure mechanisms of the waste dump by integrating surface deformation and internal slope stress and proposed novel parameters for identifying landslide stability. We developed a noncontact measurement device, which can obtain millimeter-level 3D deformation data for surface scene in physical model test;Then we developed the similar materials and established a test model for a waste dump. Based on the failure characteristics of slope surface, internal stress of slope body and displacement contours during the whole process, we divided the slope instability process in model test into four stages: rainfall infiltration and surface erosion, shallow sliding, deep sliding, and overall instability. Based on the obtained surface deformation data, we calculated the volume change during slope instability process and compared it with the point displacement on slope surface. The results showed that the volume change can not only reflect the slow-ultra acceleration process of slope failure, but also fully reflect the above four stages and reduce the fluctuations caused by random factors. Finally, this paper proposed two stability identification parameters: the volume change rate above the slip surface and the relative velocity of volume change rate. According to the calculation of these two parameters in model test, they can be used for study the deformation and failure mechanism of slope stability. 展开更多
关键词 Waste dump stability Physical model test Surface 3D deformation Stability identification
下载PDF
Exploring mechanism of hidden,steep obliquely inclined bedding landslides using a 3DEC model:A case study of the Shanyang landslide in Shaanxi Province,China
6
作者 Jia-yun Wang Zi-long Wu +3 位作者 Xiao-ya Shi Long-wei Yang Rui-ping Liu Na Lu 《China Geology》 CAS CSCD 2024年第2期303-314,I0001-I0003,共15页
Catastrophic geological disasters frequently occur on slopes with obliquely inclined bedding structures(also referred to as obliquely inclined bedding slopes),where the apparent dip sliding is not readily visible.This... Catastrophic geological disasters frequently occur on slopes with obliquely inclined bedding structures(also referred to as obliquely inclined bedding slopes),where the apparent dip sliding is not readily visible.This phenomenon has become a focal point in landslide research.Yet,there is a lack of studies on the failure modes and mechanisms of hidden,steep obliquely inclined bedding slopes.This study investigated the Shanyang landslide in Shaanxi Province,China.Using field investigations,laboratory tests of geotechnical parameters,and the 3DEC software,this study developed a numerical model of the landslide to analyze the failure process of such slopes.The findings indicate that the Shanyang landslide primarily crept along a weak interlayer under the action of gravity.The landslide,initially following a dip angle with the support of a stable inclined rock mass,shifted direction under the influence of argillization in the weak interlayer,moving towards the apparent dip angle.The slide resistance effect of the karstic dissolution zone was increasingly significant during this process,with lateral friction being the primary resistance force.A reduction in the lateral friction due to karstic dissolution made the apparent dip sliding characteristics of the Shanyang landslide more pronounced.Notably,deformations such as bending and uplift at the slope’s foot suggest that the main slide resistance shifts from lateral friction within the karstic dissolution zone to the slope foot’s resistance force,leading to the eventual buckling failure of the landslide.This study unveils a novel failure mode of apparent dip creep-buckling in the Shanyang landslide,highlighting the critical role of lateral friction from the karstic dissolution zone in its failure mechanism.These insights offer a valuable reference for mitigating risks and preventing disasters related to obliquely inclined bedding landslides. 展开更多
关键词 LANDSLIDE Steep obliquely inclined bedding slope Failure mode Failure mechanism Apparent dip creep-buckling Lateral friction 3DEC model Landslide numerical model Geological hazards survey engineering
下载PDF
Multi-scale Modeling and Finite Element Analyses of Thermal Conductivity of 3D C/SiC Composites Fabricating by Flexible-Oriented Woven Process
7
作者 Zheng Sun Zhongde Shan +5 位作者 Hao Huang Dong Wang Wang Wang Jiale Liu Chenchen Tan Chaozhong Chen 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2024年第3期275-288,共14页
Thermal conductivity is one of the most significant criterion of three-dimensional carbon fiber-reinforced SiC matrix composites(3D C/SiC).Represent volume element(RVE)models of microscale,void/matrix and mesoscale pr... Thermal conductivity is one of the most significant criterion of three-dimensional carbon fiber-reinforced SiC matrix composites(3D C/SiC).Represent volume element(RVE)models of microscale,void/matrix and mesoscale proposed in this work are used to simulate the thermal conductivity behaviors of the 3D C/SiC composites.An entirely new process is introduced to weave the preform with three-dimensional orthogonal architecture.The 3D steady-state analysis step is created for assessing the thermal conductivity behaviors of the composites by applying periodic temperature boundary conditions.Three RVE models of cuboid,hexagonal and fiber random distribution are respectively developed to comparatively study the influence of fiber package pattern on the thermal conductivities at the microscale.Besides,the effect of void morphology on the thermal conductivity of the matrix is analyzed by the void/matrix models.The prediction results at the mesoscale correspond closely to the experimental values.The effect of the porosities and fiber volume fractions on the thermal conductivities is also taken into consideration.The multi-scale models mentioned in this paper can be used to predict the thermal conductivity behaviors of other composites with complex structures. 展开更多
关键词 3D C/SiC composites Finite element analyses Multi-scale modeling Thermal conductivity
下载PDF
Tidal modeling based on satellite altimetry observations of TOPEX/ Poseidon, Jason1, Jason2, and Jason3 with high prediction capability: A case study of the Baltic Sea
8
作者 Alireza A.Ardalan Asiyeh Hashemifaraz 《Geodesy and Geodynamics》 EI CSCD 2024年第4期404-418,共15页
This research aims to optimize the utilization of long-term sea level data from the TOPEX/Poseidon,Jason1,Jason2,and Jason3 altimetry missions for tidal modeling.We generate a time series of along-track observations a... This research aims to optimize the utilization of long-term sea level data from the TOPEX/Poseidon,Jason1,Jason2,and Jason3 altimetry missions for tidal modeling.We generate a time series of along-track observations and apply a developed method to produce tidal models with specific tidal constituents for each location.Our tidal modeling methodology follows an iterative process:partitioning sea surface height(SSH)observations into analysis/training and prediction/validation parts and ultimately identi-fying the set of tidal constituents that provide the best predictions at each time series location.The study focuses on developing 1256 time series along the altimetry tracks over the Baltic Sea,each with its own set of tidal constituents.Verification of the developed tidal models against the sSH observations within the prediction/validation part reveals mean absolute error(MAE)values ranging from 0.0334 m to 0.1349 m,with an average MAE of 0.089 m.The same validation process is conducted on the FES2014 and EOT20 global tidal models,demonstrating that our tidal model,referred to as BT23(short for Baltic Tide 2023),outperforms both models with an average MAE improvement of 0.0417 m and 0.0346 m,respectively.In addition to providing details on the development of the time series and the tidal modeling procedure,we offer the 1256 along-track time series and their associated tidal models as supplementary materials.We encourage the satellite altimetry community to utilize these resources for further research and applications. 展开更多
关键词 Satellitealtimetry Baltic Sea Ocean tide modeling Jason3 Jason2 Jason1 TOPEX/POSEIDON EOT20 FES2014
下载PDF
UAV-based transient electromagnetic 3D forward modeling and inversion and analysis of exploration capability
9
作者 WEI Laonao LIU Yunhe ZHANG Bo 《Global Geology》 2024年第3期154-166,共13页
Unmanned aerial vehicle transient electromagnetic(UAV-TEM)is a novel airborne exploration method that offers advantages such as low cost,simple operation,high exploration efficiency and suitability for near-surface ex... Unmanned aerial vehicle transient electromagnetic(UAV-TEM)is a novel airborne exploration method that offers advantages such as low cost,simple operation,high exploration efficiency and suitability for near-surface exploration in complex terrain areas.To improve the accuracy of data interpretation in this method,the authors conducted a systematic three-dimensional(3D)forward modeling and inversion of the UAV-TEM.This study utilized the finite element method based on unstructured tetrahedral elements and employed the second-order backward Euler method for time discretization.This allowed for accurate 3D modeling and accounted for the effects of complex terrain.Based on these,the influence characteristics of flight altitudes and the sizes,burial depths,and resistivities of anomalies are compared and analyzed to explore the UAV-TEM systems’exploration capability.Lastly,four typical geoelectrical models of landslides are designed,and the inversion method based on the Gauss-Newton optimization method is used to image the landslide models and analyze the imaging effect of the UAV-TEM method on landslide geohazards.Numerical results showed that UAV-TEM could have better exploration resolution and fine imaging of nearsurface structures,providing important technical support for monitoring,early warning,and preventing landslides and other geological hazards. 展开更多
关键词 UAV 3D forward modeling transient electromagnetic 3D inversion landslide model
下载PDF
基于CS5463的用电器监测装置的设计与实现
10
作者 李家乐 邱达 +1 位作者 刘嵩 聂小金 《机电工程技术》 2024年第4期303-306,311,共5页
由于用电器种类和数量的急剧增加,人们在使用时往往会轻视用电的安全性,带来较大的安全隐患,为了解决这一问题,设计了一种用电器监测装置,使用ESP32-S3作为主控单元,CS5463作为用电器电能参数的采集芯片。ZMPT107-1电压互感器、ZHTM104... 由于用电器种类和数量的急剧增加,人们在使用时往往会轻视用电的安全性,带来较大的安全隐患,为了解决这一问题,设计了一种用电器监测装置,使用ESP32-S3作为主控单元,CS5463作为用电器电能参数的采集芯片。ZMPT107-1电压互感器、ZHTM104F电流互感器和外围采样电路将大电压和大电流处理成小电流和小电压,处理后小电流和小电压再传送到CS5463,在CS5463中经过增益放大器进行放大、调制器进行采样、数字滤波器进行滤波、功率计算引擎计算,最后将处理完成的电能参数通过串行口发送到ESP32-S3中,ESP32-S3对电能参数再进行读取和存储,最后通过天线发射器或者串口转以太网模块将处理完成的电能参数发送给服务器。系统测试时,使用DH18615可调电源来模拟市电,DH28603可调负载来模拟各种类型的负载,CA8230电能质量分析来校正和检验电路板测量的电能参数。校正完成后检验电能参数测量准确度,结果表明电压、电流、功率3个参数的误差值在±2%以内,功率因数的误差值在±3%以内,并且系统能够稳定运行,说明设计的用电器监测装置安全可靠,精度高,可应用于现阶段的大部分用电器监测的场景中。 展开更多
关键词 用电器监测 cs5463 电能参数 ESP32-S3
下载PDF
Review of Artificial Intelligence for Oil and Gas Exploration: Convolutional Neural Network Approaches and the U-Net 3D Model
11
作者 Weiyan Liu 《Open Journal of Geology》 CAS 2024年第4期578-593,共16页
Deep learning, especially through convolutional neural networks (CNN) such as the U-Net 3D model, has revolutionized fault identification from seismic data, representing a significant leap over traditional methods. Ou... Deep learning, especially through convolutional neural networks (CNN) such as the U-Net 3D model, has revolutionized fault identification from seismic data, representing a significant leap over traditional methods. Our review traces the evolution of CNN, emphasizing the adaptation and capabilities of the U-Net 3D model in automating seismic fault delineation with unprecedented accuracy. We find: 1) The transition from basic neural networks to sophisticated CNN has enabled remarkable advancements in image recognition, which are directly applicable to analyzing seismic data. The U-Net 3D model, with its innovative architecture, exemplifies this progress by providing a method for detailed and accurate fault detection with reduced manual interpretation bias. 2) The U-Net 3D model has demonstrated its superiority over traditional fault identification methods in several key areas: it has enhanced interpretation accuracy, increased operational efficiency, and reduced the subjectivity of manual methods. 3) Despite these achievements, challenges such as the need for effective data preprocessing, acquisition of high-quality annotated datasets, and achieving model generalization across different geological conditions remain. Future research should therefore focus on developing more complex network architectures and innovative training strategies to refine fault identification performance further. Our findings confirm the transformative potential of deep learning, particularly CNN like the U-Net 3D model, in geosciences, advocating for its broader integration to revolutionize geological exploration and seismic analysis. 展开更多
关键词 Deep Learning Convolutional Neural Networks (CNN) Seismic Fault Identification U-Net 3D model Geological Exploration
下载PDF
Contribution to the Full 3D Finite Element Modelling of a Hybrid Stepping Motor with and without Current in the Coils
12
作者 Belemdara Dingamadji Hilaire Mbaïnaïbeye Jérôme Guidkaya Golam 《Journal of Electromagnetic Analysis and Applications》 2024年第2期11-23,共13页
The paper presents our contribution to the full 3D finite element modelling of a hybrid stepping motor using COMSOL Multiphysics software. This type of four-phase motor has a permanent magnet interposed between the tw... The paper presents our contribution to the full 3D finite element modelling of a hybrid stepping motor using COMSOL Multiphysics software. This type of four-phase motor has a permanent magnet interposed between the two identical and coaxial half stators. The calculation of the field with or without current in the windings (respectively with or without permanent magnet) is done using a mixed formulation with strong coupling. In addition, the local high saturation of the ferromagnetic material and the radial and axial components of the magnetic flux are taken into account. The results obtained make it possible to clearly observe, as a function of the intensity of the bus current or the remanent induction, the saturation zones, the lines, the orientations and the magnetic flux densities. 3D finite element modelling provide more accurate numerical data on the magnetic field through multiphysics analysis. This analysis considers the actual operating conditions and leads to the design of an optimized machine structure, with or without current in the windings and/or permanent magnet. 展开更多
关键词 modelLING 3D Finite Elements Magnetic Flux Hybrid Stepping Motor
下载PDF
Electrostatic Attraction and Repulsion Explained and Modelled Mathematically Using Classical Physics—A Detailed Mechanism Based on Particle Wave Functions
13
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
下载PDF
3D forward modeling and response characteristics of low-resistivity overburden of the CFS-PML absorbing boundary for ground-well transient electromagnetic method
14
作者 Lijuan Zhao Mingzhong Gao +3 位作者 Nengzhong Lei Hongfei Duan Weizhong Qiu Zhaoying Chen 《International Journal of Mining Science and Technology》 SCIE EI CAS CSCD 2023年第12期1541-1550,共10页
This study used the stable and convergent Dufort-Frankel method to differentially discretize the diffusion equation of the ground-well transient electromagnetic secondary field.The absorption boundary condition of com... This study used the stable and convergent Dufort-Frankel method to differentially discretize the diffusion equation of the ground-well transient electromagnetic secondary field.The absorption boundary condition of complex frequency-shifted perfectly matched layer(CFS-PML)was used for truncation so that the low-frequency electromagnetic wave can be better absorbed at the model boundary.A typical three-dimensional(3D)homogeneous half-space model was established and a low-resistivity cube model was analyzed under the half-space condition.The response patterns and drivers of the low-resistivity cube model were discussed under the influence of a low-resistivity overburden.The absorption boundary conditions of CFS-PML significantly affected the low-frequency electromagnetic waves.For a low-resistivity cube around the borehole,its response curve exhibited a single-peak,and the extreme point of the curve corresponded to the center of the low-resistivity body.When the low-resistivity cube was directly below the borehole,the response curve showed three extreme values(two high and one low),with the low corresponding to the center of the low-resistivity body.The total field response of the low-resistivity overburden was stronger than that of the uniform half-space model due to the low-resistivity shielding effect of electromagnetic waves.When the receiving-transmitting distance gradually increased,the effect of the low-resistivity overburden was gradually weakened,and the response of the low-resistivity cube was strengthened.It was affected by the ratio of the overburden resistivity to the resistivity of the low-resistivity body. 展开更多
关键词 Ground-well transient electromagnetic method CFS-PML boundary condition 3D forward modeling Low-resistivity overburden
下载PDF
Mathematical Wave Functions and 3D Finite Element Modelling of the Electron and Positron
15
作者 Declan Traill 《Journal of Applied Mathematics and Physics》 2024年第4期1134-1162,共29页
The wave/particle duality of particles in Physics is well known. Particles have properties that uniquely characterize them from one another, such as mass, charge and spin. Charged particles have associated Electric an... The wave/particle duality of particles in Physics is well known. Particles have properties that uniquely characterize them from one another, such as mass, charge and spin. Charged particles have associated Electric and Magnetic fields. Also, every moving particle has a De Broglie wavelength determined by its mass and velocity. This paper shows that all of these properties of a particle can be derived from a single wave function equation for that particle. Wave functions for the Electron and the Positron are presented and principles are provided that can be used to calculate the wave functions of all the fundamental particles in Physics. Fundamental particles such as electrons and positrons are considered to be point particles in the Standard Model of Physics and are not considered to have a structure. This paper demonstrates that they do indeed have structure and that this structure extends into the space around the particle’s center (in fact, they have infinite extent), but with rapidly diminishing energy density with the distance from that center. The particles are formed from Electromagnetic standing waves, which are stable solutions to the Schrödinger and Classical wave equations. This stable structure therefore accounts for both the wave and particle nature of these particles. In fact, all of their properties such as mass, spin and electric charge, can be accounted for from this structure. These particle properties appear to originate from a single point at the center of the wave function structure, in the same sort of way that the Shell theorem of gravity causes the gravity of a body to appear to all originate from a central point. This paper represents the first two fully characterized fundamental particles, with a complete description of their structure and properties, built up from the underlying Electromagnetic waves that comprise these and all fundamental particles. 展开更多
关键词 ELECTRON POSITRON Wave Function Solution Electromagnetic Spin Mass Charge Proof Fundamental Particle Properties Quantum Mechanics Classical Physics Computer 3D model Schrödinger Equation RMS KLEIN GORDON Electric Magnetic Lorentz Invariant Hertzian Vector Point Potential Field Density Phase Flow Attraction REPULSION Shell Theorem Ehrenfest VIRIAL Normalization Harmonic Oscillator
下载PDF
InGaAs光电阴极的Cs/NF_(3)激活 被引量:2
16
作者 王自衡 李诗曼 +2 位作者 石峰 钱芸生 张益军 《光学精密工程》 EI CAS CSCD 北大核心 2023年第9期1277-1284,共8页
为了提高InGaAs光电阴极的光电发射性能,探究新型激活工艺,采用Cs/NF_(3)和Cs/O两种激活方式对InGaAs样品进行激活实验。对同一结构的InGaAs阴极样品,分别进行了激活实验、衰减实验、光谱响应测试和表面成分分析,分别从白光光电流、衰... 为了提高InGaAs光电阴极的光电发射性能,探究新型激活工艺,采用Cs/NF_(3)和Cs/O两种激活方式对InGaAs样品进行激活实验。对同一结构的InGaAs阴极样品,分别进行了激活实验、衰减实验、光谱响应测试和表面成分分析,分别从白光光电流、衰减稳定性、光谱响应和表面成分等角度测试并分析了不同激活工艺下阴极的性能参数。通过对比Cs/NF_(3)和Cs/O两种激活方式的实验结果可知:Cs/NF_(3)激活后的InGaAs光电阴极在白光光电流、截止波长和光谱响应方面明显优于Cs/O激活后的样品,光谱响应的增强效果在近红外波段尤为明显,在1064 nm处Cs/NF_(3)激活后阴极光谱响应是Cs/O激活后的4.7倍;然而,与GaAs光电阴极Cs/NF_(3)激活能够获得更高的阴极稳定性这一现象不同,Cs/O激活的InGaAs光电阴极的稳定性明显优于Cs/NF_(3)激活,Cs/NF_(3)激活在截止波长和光谱响应方面的优势在连续光照衰减后消失。 展开更多
关键词 InGaAs光电阴极 cs/NF_(3)激活 cs/O激活 稳定性 光谱响应
下载PDF
Fe_(3)O_(4)/CS/EDTA对水溶液中Cu^(2+)和Ni^(2+)的吸附研究
17
作者 秦润华 周洋 赵雲胤 《金陵科技学院学报》 2023年第1期58-63,共6页
分析了自制的Fe_(3)O_(4)/CS/EDTA纳米粒对水溶液中的重金属离子Cu^(2+)和Ni^(2+)的吸附性能和吸附机理。研究了pH值、溶液初始浓度、反应时间等对吸附性能的影响,结合红外、XPS和比表面分析结果确定了参与吸附配位的功能基团及可能发... 分析了自制的Fe_(3)O_(4)/CS/EDTA纳米粒对水溶液中的重金属离子Cu^(2+)和Ni^(2+)的吸附性能和吸附机理。研究了pH值、溶液初始浓度、反应时间等对吸附性能的影响,结合红外、XPS和比表面分析结果确定了参与吸附配位的功能基团及可能发生的络合反应。结果表明:Fe_(3)O_(4)/CS/EDTA对Cu^(2+)和Ni^(2+)的吸附等温线均符合Langmuir模型,对Cu^(2+)的吸附效果要优于Ni^(2+),这可能与Ni^(2+)的离子半径较Cu^(2+)小以及Ni^(2+)与吸附剂形成的金属螯合物的稳定性较Cu^(2+)低有关;Fe_(3)O_(4)/CS/EDTA对Cu^(2+)和Ni^(2+)的吸附机理类似于N·O型螯合剂,并非一般的物理吸附,而是一种以金属离子为中心的吸附螯合。 展开更多
关键词 Fe_(3)O_(4)/cs/EDTA 吸附性能 吸附机理 Cu^(2+) Ni^(2+)
下载PDF
沈阳市O_(3)与PM_(2.5)关系及污染主控因素分析
18
作者 洪也 马雁军 +5 位作者 苏枞枞 王扬锋 任万辉 王继康 王东东 徐晓斌 《环境科学研究》 CAS CSCD 北大核心 2024年第3期455-468,共14页
PM_(2.5)与O_(3)的协同控制是空气质量持续改善的关键所在,厘清PM_(2.5)与O_(3)的关系,识别O_(3)主控因素以及量化气象和人为排放贡献是实施二者协同控制的基础.本研究基于沈阳市大气复合立体超级站2019−2022年地面观测数据,分析PM_(2.5... PM_(2.5)与O_(3)的协同控制是空气质量持续改善的关键所在,厘清PM_(2.5)与O_(3)的关系,识别O_(3)主控因素以及量化气象和人为排放贡献是实施二者协同控制的基础.本研究基于沈阳市大气复合立体超级站2019−2022年地面观测数据,分析PM_(2.5)和O_(3)协同关系及成因;利用逐步回归模型得到影响O_(3)变化的主控因素,并估算各气象因素对O_(3)的贡献.结果表明:①沈阳市2019−2022年夏季PM_(2.5)浓度与O_(3)浓度呈正相关,有明显的协同增长效应,其余三季均呈明显负相关.究其原因,主要是由于夏季高温和高太阳辐射条件利于大气光化学反应,促进了O_(3)、PM_(2.5)中二次无机成分〔主要是硫酸盐(SO_(4)^(2−))、硝酸盐(NO_(3)−)和铵盐(NH_(4)^(+)),简称“SNA”〕共同增长所致;而冬季高排放和高大气稳定度等气象条件利于SNA和二次有机碳(SOC)非均相生成,但弱太阳辐射和低温等条件不利于O_(3)光化学生成,加之高NO的滴定效应,使SNA和SOC浓度均与O_(3)浓度呈负相关.②在观测的相关污染物和气象因子中,过氧乙酰硝酸酯(PAN)与O_(3)浓度的关系最为密切,尤其在夏季.③气象因素中,O_(3)浓度与气温高度相关,与风速也呈正相关,而与相对湿度则在各季节均呈负相关.冬、春、秋三季PM_(2.5)均对O_(3)起抑制作用,冬季尤为突出.在高浓度O_(3)污染(O_(3)浓度>160μg/m^(3))过程中,主控因素中气温和风速的抬升促进O_(3)浓度升高,而高NO2和相对湿度(RH)则有利于降低O_(3)浓度.在2019−2022年高浓度O_(3)污染过程中,气象因素对沈阳市O_(3)浓度变化的贡献高于O_(3)前体物排放的贡献,总贡献为57μg/m^(3),对污染形成起着主导作用. 展开更多
关键词 PM_(2.5) O_(3) PM_(2.5)与O_(3)协同作用 气象因素 逐步回归模型
下载PDF
基于MCS-SBL算法的配电网故障定位方法
19
作者 周群 刘梓琳 +2 位作者 冷敏瑞 印月 何川 《电力系统及其自动化学报》 CSCD 北大核心 2024年第3期30-38,共9页
配电网拓扑结构复杂,传统方法往往需要大量测点信息且难以实现快速有效的故障定位,本文提出基于少量测点信息的故障定位方法。首先,利用等效原理建立一个欠定的故障节点电压方程;其次,利用多重测量向量模型的贝叶斯压缩感知算法求解方程... 配电网拓扑结构复杂,传统方法往往需要大量测点信息且难以实现快速有效的故障定位,本文提出基于少量测点信息的故障定位方法。首先,利用等效原理建立一个欠定的故障节点电压方程;其次,利用多重测量向量模型的贝叶斯压缩感知算法求解方程,根据重构稀疏电流矩阵的非零元素位置求解故障区域,实现故障定位;最后,在IEEE33节点配电系统上进行仿真实验,结果表明,所提方法仅需要少量测点的故障前后正序电压分量便可有效定位故障,计算速度较快,并且基本不受故障类型、过渡电阻的影响,同时适用于单故障和多重故障的场景,具有较强的抗噪能力。 展开更多
关键词 配电网 故障定位 多重测量向量模型 稀疏电流 压缩感知
下载PDF
3D打印实物模型在颈椎疾患住院医师规范化培训教学中的应用和探讨
20
作者 王玉强 许建中 +6 位作者 谭洪宇 鲍恒 李宇 刘会范 王秀玲 马陶然 花卉 《中国毕业后医学教育》 2024年第5期369-372,共4页
目的探讨3 D打印实物模型在提高颈椎疾患住院医师规范化培训(简称住培)教学效果中的作用。方法选取参加骨科住培的颈椎疾患学习的住院医师80名为研究对象,随机分为两组,观察组(40人)以幻灯讲解加3 D打印实物模型教学,对照组(40人)采用... 目的探讨3 D打印实物模型在提高颈椎疾患住院医师规范化培训(简称住培)教学效果中的作用。方法选取参加骨科住培的颈椎疾患学习的住院医师80名为研究对象,随机分为两组,观察组(40人)以幻灯讲解加3 D打印实物模型教学,对照组(40人)采用幻灯讲解教学。课后即时和课后1月分别对住院医师的知识掌握情况和诊疗技术进行现场测试,利用问卷的形式对住院医师的满意度和参与兴趣(10分法)进行调查。结果课后即时观察组的知识掌握情况和对照组相当(P>0.05),但是观察组的诊疗技术测试成绩显著高于对照组(P<0.05),观察组的满意度和参与兴趣评分均显著高于对照组,两者对比差异有统计学意义(均P<0.05);课后1月时,观察组的知识掌握情况和诊疗技术测试成绩均显著高于对照组(均P<0.05)。结论3 D打印实物模型应用于颈椎疾患住培的带教中,可显著提高教学效果,提升住院医师的满意度和参与兴趣,值得在住培教学中推广。 展开更多
关键词 3D打印 实物模型 颈椎 教学 住院医师规范化培训
下载PDF
上一页 1 2 248 下一页 到第
使用帮助 返回顶部