Research on 3D Laser Scanning Reconstruction of Ancient Buildings Combined with BIM Technology

After more than 30 years of scientific and social development, surveying and mapping technology by leaps and bounds, engineering surveying technology has undergone tremendous changes. In the process of protecting ancient buildings, it is necessary to obtain the precise dimensions of architectural details. In this study, the path of 3D laser scanning combined with BIM technology is explored. Taking the observation and protection of the ancestral hall of the Liu family as an example, this study aims to draw drawings that reflect the relevant information about the ancient buildings, the accurate three-dimensional model of ancient buildings is established with BIM technology, which provides new methods and ideas for the research and protection of ancient buildings. .

Slope excavation quality assessment and excavated volume calculation in hydraulic projects based on laser scanning technology

Slope excavation is one of the most crucial steps in the construction of a hydraulic project. Excavation project quality assessment and excavated volume calculation are critical in construction management. The positioning of excavation projects using traditional instruments is inefficient and may cause error. To improve the efficiency and precision of calculation and assessment, three-dimensional laser scanning technology was used for slope excavation quality assessment. An efficient data acquisition, processing, and management workflow was presented in this study. Based on the quality control indices, including the average gradient, slope toe elevation, and overbreak and underbreak,cross-sectional quality assessment and holistic quality assessment methods were proposed to assess the slope excavation quality with laserscanned data. An algorithm was also presented to calculate the excavated volume with laser-scanned data. A field application and a laboratory experiment were carried out to verify the feasibility of these methods for excavation quality assessment and excavated volume calculation. The results show that the quality assessment indices can be obtained rapidly and accurately with design parameters and scanned data, and the results of holistic quality assessment are consistent with those of cross-sectional quality assessment. In addition, the time consumption in excavation quality assessment with the laser scanning technology can be reduced by 70%e90%, as compared with the traditional method. The excavated volume calculated with the scanned data only slightly differs from measured data, demonstrating the applicability of the excavated volume calculation method presented in this study.

Research on wind erosion processes and controlling factors based on wind tunnel test and 3D laser scanning technology

The study of wind erosion processes is of great importance to the prevention and control of soil wind erosion.In this study,three structurally intact soil samples were collected from the steppe of Inner Mongolia Autonomous Region,China and placed in a wind tunnel where they were subjected to six different wind speeds(10,15,17,20,25,and 30 m/s)to simulate wind erosion in the wind tunnel.After each test,the soil surfaces were scanned by a 3D laser scanner to create a high-resolution Digital Elevation Model(DEM),and the changes in wind erosion mass and microtopography were quantified.Based on this,we performed further analysis of wind erosion-controlling factors.The study results showed that the average measurement error between the 3D laser scanning method and weighing method was 6.23%for the three undisturbed soil samples.With increasing wind speed,the microtopography on the undisturbed soil surface first became smooth,and then fine stripes and pits gradually developed.In the initial stage of wind erosion processes,the ability of the soil to resist wind erosion was mainly affected by the soil hardness.In the late stage of wind erosion processes,the degree of soil erosion was mainly affected by soil organic matter and CaCO_(3)content.The results of this study are expected to provide a theoretical basis for soil wind erosion control and promote the application of 3D laser scanners in wind erosion monitoring.

Application of Three-dimensional Laser Scanning Technology in the Teaching Practice of Surveying and Mapping of Ancient Buildings

Based on the study of the application of three-dimensional laser scanning technology in ancient building surveying and mapping,this paper briefly describes the working principle and flow of three-dimensional laser scanning technology.Based on the practical application,this paper puts forward the discussion of related problems and matters needing attention.This has a certain reference significance for the study of new technology in surveying and mapping of ancient buildings.

The Research Application of 3D Laser Scanning Technology in the Deformation Detection of Large Cylindrical Oil Tank

In order to ensure the safety in using a large cylindrical storage tank,it is necessary to regularly detect its defonnatioii.The traditional total station method has high accuracy in determining the deformation,however,it has a low measxirement efficiency.Long-term observation means,there are more risks in the petrochemical plant,therefore,this paper proposes the usage of the 3D laser scanner,replacing the traditional total station to determine the defbnnation of a large cylindrical storage tank.The Matlab program,is compiled to calculate the point cloud data,while the tank deformation is analyzed from two different points which are,the local concave convex degree and the ovality degree.It is concluded that,the difference between the data obtained by 3D laser scanning,and total station is within the range of oil tank deformation limit,therefore,3D laser scanner can be used for oil tank deformation detection.

Research of Board-Level BIT Technology Based on Boundary-Scan Architecture

The boundary scan architecture and its basic principle of board level built in test(BIT) technology are presented. A design for board level built in test and the method to implement test tool are brought forward.

THE GROWTH OF MONOCRYSTALLINE SILICON THIN FILM ON INSULATOR (SOI) BY SCANNING ELECTRON BEAM

An experiment for preparation of SOI films by using the scanning electron beam to modify the polycrystalline silicon on SiO2 is presented. This method takes on the epitaxial lateral growth of liquid phase with the crystallon to form monocrystalline silicon films. The effects of the beam power density, scanning velocity, temperature of the substrates and the construction of samples on the quality of the monocrystalline silicon films were discussed. A good experimental result has been obtained, the monocrystalline silicon zone is nearly 200×25μm2.

Study of Scanning Dose Optimization on Chest and Abdomen Enhanced CT Imaging

Objective: To investigate the correlation between radiation dose and radiation risk when patients are scanned by 64-slice spiral CT. Materials and Methods: SPSS 17.0 is used statistically for analyzing the patient’s scanning parameters, radiation dose of monitoring and examining the patients who are scanning of their abdomen, chest and pelvic in our affiliated hospital. Results: SPSS statistical analysis shows that the factor related to radiation dose is scanning layer;the basic characteristics such as height and heart rate don’t affect the patient’s scan dose directly. Conclusion: Increasing the delay time after injection can reduce the scan numbers and monitoring layers of the machine, thus reduce the patient’s radiation dose and tube’s exposure time.

Innovations in Retinal Laser Technology

Retinal laser photocoagulation is a proven, effective treatment for various retinal disorders, including diabetic retinopathy, retinal vein occlusions, and sickle cell retinopathy. To minimize iatrogenic retinal damage while maintaining therapeutic effects, retinal laser technology has evolved significantly since its introduction in ophthalmology more than half a century ago. These innovations have included both optimizations of laser parameters in addition to the development of novel laser delivery systems. This review summarizes recent innovations in retinal laser technology, including subthreshold micropulse laser, selective retinal therapy and nanosecond laser, innovative modes of laser delivery including pattern scanning laser, endpoint management, navigated laser, and newly described photo-mediated ultrasound therapy.

基于X-CT扫描的石油地质岩心储层渗透率估算

渗透率估算可以为石油地质岩心储层渗流能力分析提供数据支撑,为提高石油地质岩心储层的渗流能力,提出了基于X-CT扫描的石油地质岩心储层渗透率估算方法。根据油在两相共渗区的渗透率与水在两相共渗区的渗透率之比,引入Buckley-Leverett方程,计算岩心储层水驱油的分流率,利用X-CT扫描技术,扫描石油地质岩心的分布情况,计算出岩心储层含水饱和度。基于渗透区在井眼与地层之间出现的流体流动现象,计算出岩心储层中泥浆的体积模量和地层的剪切模量,利用斯通利波时差实测值与弹性斯通利波时差之间的差值,计算流体移动指数。根据等效孔隙度与流体移动指数之间的相关性和等效孔隙度与渗透率的相关性,估算出石油地质岩心储层的渗透率。实验结果表明该方法的估算精度可达到90%以上,对估算石油地质岩心储层渗透率具有重要意义。

数字化口内扫描技术专家共识

数字化口内扫描是近年口腔数字化技术的研究热点,成为口腔正畸、修复、种植的重要技术。数字化口内扫描的精确度和数据资料采集拼接的准确性是保证数字印模成功和加工制作效果的关键;而扫描仪特性、成像原理以及操作者扫描方式、扫描对象、口腔组织特殊性、修复设计方案等均会影响数据采集的准确性。仍有诸多操作者对于如何鉴别不同修复设计的扫描策略、扫描轨迹、如何减少数字化扫描误差等认识不足,且目前国内外学者关于数字化口内扫描技术尚未形成统一标准与共识。为了更好地帮助操作者应对口内扫描中遇到的难题,提高数字化扫描质量,本文集合了参与专家的共同意见,通过对现有证据的归纳鉴别,阐述数字化口内扫描误差的原因与应对方法,掌握不同口腔印模需求下的扫描策略。本专家共识认为,基于影响数字化口内扫描精度及扫描图像重现效果受诸多因素的影响,采用正确的扫描轨迹可缩短临床操作时间,提高扫描的精确性,扫描轨迹主要包括E字法、分段法和S型法等。①进行固定义齿修复时,建议先扫描基牙及前后两个邻牙,再把基牙区域挖出洞型,最后在基牙预备完成后补扫洞型缺口处,既可满足临床实际需求,同时也能得到最可靠的精度。②全口无牙颌行全口义齿修复时,在牙槽嵴底黏膜组织设定标记点、一次性捕获前庭区域的图像、采用不同类型的扫描路径如“Z”形、“S”形、颊腭、腭颊路径、分段扫描牙弓等策略,可以减少扫描误差和改善图像拼接以及重叠的问题。③对于种植修复,当进行种植体支持的单冠修复与小跨度上部结构修复时,建议先预扫所需牙弓,再把基牙区域挖出洞型,最后安装好种植扫描杆后再补扫洞型缺口处;当进行骨水平种植体冠修复时,可通过改良的间接扫描方法,将扫描过程分为三步:首先在口内扫描临时修复体和相邻两个牙位的牙齿与牙龈组织,然后在种植体上安装标准扫描杆并扫描全牙弓,最后在口外扫描临时修复体,以获取种植体颈部穿龈轮廓的三维形态,从而增加种植体周软组织扫描的稳定性,提高扫描还原度;对于牙列缺失种植固定桥修复,黏膜具有活动度增加了扫描难度,扫描仪难以分辨形态大小相同的扫描杆,易造成图像叠加错误,可以通过更改扫描杆的几何形状改变光学曲率半径,获得更高的种植数字化印模精确度。共识认为,随着扫描牙弓的范围越大,数据拼接次数增加,扫描精度随之下降;尤其是行全口种植修复印模时,由于口内存在不稳定、不平整的黏膜形态,且无相对明显、固定的参照物,易增加图像拼接处理的难度,造成精度不足,针对此类进行修复设计时,应谨慎选择数字化口内扫描方式获取模型数据,在缺失牙大于5颗时不宜使用数字化印模。

保偏光纤制备及其参数测试原理

为了研制工作波长为1310 nm的保偏光纤,采用改进的化学气相沉积工艺制备了保偏光纤预制捧和应力棒,经加工、拼接、清洗、拉丝工艺后,得到几何尺寸精确的高质量保偏光纤;同时搭建了高效测试系统,采用折射近场法、远场扫描法、视频灰度技术(传输近场),分别测量了预制棒的折射率分布和几何尺寸,保偏光纤模场直径、数值孔径、几何尺寸等关键参数。结果表明,此标准化测试系统操作流程简单、结果精确;模场直径为6.26μm,数值孔径为0.23,包涂直径80μm/135μm/165μm(精度±0.7μm);终检测试合格的光纤成品随机抽样16.25%,高低温老化实验后拍长、串音变化小。所研制的保偏光纤性能稳定,几何尺寸精确、结构均匀、损耗低,具有优良保偏性能,已广泛应用于实际生产中。

成型工艺对水泥稳定碎石性能的影响

为研究不同成型工艺对水泥稳定碎石宏观性能的影响,基于骨架密实和悬浮密实2种级配,分别采用强制搅拌静压成型、强制搅拌振动压实、振动搅拌静压成型、振动搅拌振动压实4种工艺制备了8种水泥稳定碎石,采用7 d无侧限抗压试验、28 d单轴贯入试验、7 d温缩试验和7 d干缩试验对水泥稳定碎石宏观性能进行了研究,同时结合扫描电子显微镜微观手段,分析了水泥稳定碎石宏观性能变化机理。结果表明:振动搅拌振动压实工艺下骨架密实级配的水泥稳定碎石力学性能最优,其7 d无侧限抗压强度和28 d单轴压缩模量较强制搅拌静压成型分别提升了169.5%、97.2%。采用振动搅拌振动压实工艺可以促使水泥水化产物生成量增多、结构完善,整体均匀性提高,进而改善水泥稳定碎石宏观性能。

三维激光扫描技术在建筑变形监测中的应用

三维激光扫描技术是通过利用高速激光扫描测量的方法,复建出1∶1三维点云模型的一种全新技术手段。在广西壮族自治区某商务主楼钢结构变形监测中,通过运用三维激光扫描技术获取建筑信息,并结合点云处理软件、CAD插件等软件,进行数据全面分析,完成对该超高层建筑物钢框架主体水平方向的变形监测。由此总结出三维激光扫描技术在建筑变形监测中的应用流程,为未来建筑的变形监测提供借鉴参考。

三维激光扫描技术在历史建筑测绘中的应用——以闽清县历史建筑测绘建档项目为例

历史建筑作为城市的文脉,承载着一座城市的历史,受各种因素影响遭受不断的侵蚀甚至灭失,其保护形势越来越严峻。文章以闽清县历史建筑保护测绘为例,采用三维激光扫描技术,结合无人机倾斜摄影技术,对历史建筑真彩色三维点云模型建设进行了探索研究,为历史建筑的测绘资料建档和文物保护工作积累了宝贵的技术经验。结语对该技术进行了总结分析,认为三维激光扫描技术不仅能大幅提升工作效率和测量成果精度,还可实现历史建筑三维可视化,具有广阔的应用前景。

三维激光扫描与BIM技术融合的城市轨道交通地下建筑物三维建模方法

本文将三维激光扫描技术与BIM技术相结合,实现了城市轨道交通地下车站、隧道及附属设施的三维建模。通过激光扫描仪获取点云数据,利用点云处理软件进行预处理,包括拼接、去噪和精简等操作;然后利用特征点云提取方法结合BIM建模软件和可视化编程技术,有效解决了传统测绘方法无法获取和处理复杂地下建筑物信息及BIM模型中信息孤岛问题。本文方法对未来城市轨道交通工程建设和运维管理的信息化和三维可视化具有重要意义。

循环加载下碎石层细观孔隙结构演化分析

列车荷载作用下路基翻浆冒泥的实质是路基土体细颗粒迁移,细颗粒迁移会改变路基上覆碎石层孔隙结构,影响上覆碎石层力学及水力学性质。为此,采用自主研发的路基翻浆冒泥试验模型进行试验,结合X射线计算机断层(computed tomography, CT)扫描技术,分析循环荷载作用下路基土体细颗粒迁移对上覆碎石层细观孔隙结构的影响。结果表明:循环荷载作用下,碎石层孔隙的压缩作用及路基土体细颗粒迁移至碎石层的堵塞作用,不仅改变碎石层面孔隙率的分布特性,还减小碎石层孔隙率及孔隙连通度;孔隙尺寸分布特性不受加载影响,加载前后,碎石孔隙均呈现小孔隙多、大孔隙少的特点,孔隙分布特征曲线满足对数正态分布,但随着循环荷载的施加,碎石层内孔隙总数量减小;孔隙的形状参数(细长比和扁平度)均呈正态分布,细长比随循环荷载作用次数无明显变化规律,而加载后碎石层孔隙扁平度的分布更加均匀;碎石层孔隙具有明显的分形特性,加载前孔隙三维分形维数为2.40~2.50,随着循环荷载的施加,孔隙三维分形维数逐渐减小。

面向卫星通信与导航的下一代多址接入

面向卫星通信与导航(SCAN)系统多样复杂的应用场景,下一代多址接入(NGMA)技术可以提供更高的通信速率、更多的接入数量和更广的覆盖面积。面向SCAN系统,对基于多功能NGMA、基于多资源NGMA和基于多技术NGMA展开研究,分析了现有的NGMA技术对SCAN系统的性能增益。最后,总结SCAN-NGMA面临的挑战,展望了未来发展的方向,为SCAN-NGMA架构的进一步演进提供了参考依据。

MRI与CT评价上腔静脉切除置换术后患者人工血管通畅度的对比研究

目的探讨MRI在上腔静脉切除人工血管置换术后患者人工血管通畅度复查中的应用价值。方法收集2021年1月—2022年10月于四川大学华西医院行上腔静脉切除人工血管置换术后返院复查的患者42例,均施行MRI检查(MRI组)和上腔静脉CT血管成像(CTA组)。对MRI血管图像进行主观评价和客观评价。以CTA图像为参照标准,测量人工血管的血管长度,人工血管端口、中部和尾端的血管直径宽度,采用Bland-Altman图对两种扫描方法的测量值进行一致性分析。结果42例患者共置换人工血管52根。MRI组的图像质量平均评分稍低于CTA组[(4.53±0.50)分vs(4.94±0.24)分,χ^(2)=13.14,P=0.002];Bland-Altman图所得MRI和CT两种方法的差值服从正态分布,两种方法具有较好的一致性。结论与CTA相比,MRI无辐射、无需对比剂就能获得良好的人工血管成像,对人工血管是否通畅具有重要的临床应用价值。

蔡司Axio Scan.Z1全自动数字玻片扫描系统的应用

全自动切片扫描技术优势大,应用范围广,已逐步成为形态学和病理学研究的一种变革性辅助手段。本文介绍了蔡司AxioScan.Z1切片扫描系统的配置参数(光学系统、物镜、分辨率、扫描速度、相机等)和成像特点,阐述了蔡司AxioScan.Z1在大批量全组织扫描、组织病理学、神经生物学等研究领域的重要应用。总结了仪器在使用过程中遇到的问题,分析了原因并提出解决方案,为科研工作提供更好的共享服务。