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.

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。

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。

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。

三维逆向重构技术在地质教学中的应用——以节理面力学性质教学为例

讲授岩石结构面的力学性质,是地质专业人才培养的必要环节。然而,传统的教学方式如板书教学、图片展示、动画制作等,都不足以让学生深刻全面地了解结构面在岩石强度中的影响机理。随着计算机技术的发展,三维逆向重构技术使高精度复刻结构面成为可能。为更加充分地满足课程教学需求,使学生能够在实践中对结构面抗剪机理有更加深入的了解,该文将三维光学扫描技术、计算机模型构建技术、3D打印技术用于课堂教学实践,对传统教育方法做进一步改进。

基于三维激光扫描技术的智能制造生产线目标检测研究

智能制造生产线目标图像数据采集过程受到噪声、光照变化等问题,导致输入图像的质量不佳,进而影响目标检测的准确性,对此,设计一种基于三维激光扫描技术的智能制造生产线目标检测方法。首先,采用三维激光扫描仪获取待检测目标点云数据,通过点云变换准则计算数据之间的拓扑关联,生成完整三维激光图像。然后,利用杂交小波变换对三维激光目标图像进行去噪处理。最后,使用能量、熵、对比度、相关性4种参数提取图像纹理特征并采取归一化处理,创建最优分类函数,并运用支持向量机算法划分生产线目标样本图像数据,完成智能制造生产线目标检测工作。实验结果表明,所提方法的交并比值最高时达到0.97,F1值最高时达到0.96,平均检测耗时仅为0.53 s,说明所提方法的检测精度高、效率快,鲁棒性强,在实际操作中具备相当的可用性,为智能制造产业提供技术支持。

基于CT扫描研究颗粒形状对砂土力学性质的影响

为了探究颗粒形状对砂土力学性质的影响,选取玻璃珠、石英砂、玻璃渣3种颗粒形状差异较大的砂土作为研究对象。首先通过计算机断层(computed tomography,CT)扫描重构了3种砂土的三维结构,选取了伸长率(EI)、扁度(FI)、球度(S)3个表征颗粒形状参数的均值作为砂土颗粒整体形状参数(overall regularity,OR),并对整体形状参数OR进行统计分析。然后配制7种不同形状参数的砂土进行了常规三轴压缩试验得到了其力学强度参数,研究砂土颗粒形状对其力学强度的影响规律。结果表明:7种砂土的应力-应变曲线均为应变软化型,都呈现出先剪缩后剪胀的特性;整体形状参数OR能较好反映砂土的力学特征,即随着整体形状参数OR的减小,应变软化现象变得不明显,但其峰值偏应力呈增大的趋势;砂土的内摩擦角随整体形状参数OR的减小呈线性增长,表观黏聚力急剧增大,但最大剪胀角随OR的减小而减小。此外,将临界内摩擦角与整体形状参数OR进行线性拟合,得到了两者较好的线性关系。

三维激光扫描技术在建筑数字化中的研究

针对传统的单点测量效率低、工作量大、监测结果存在片面性的问题,该研究提出了基于三维激光扫描技术的建筑物模型重构方法,先用地面三维扫描系统获取建筑物三维模型,提取目标特征点,再将RANSAC算法与欧式聚类方法相结合分割建筑物立面,满足建筑数字化的要求。该研究在对三维数据预处理后进行半自动滤波去噪和平面拟合,能准确地提取建筑物立面信息。实验结果表明,本文模型产生噪声少,平面拟合优越性高,精度约在99%左右,能达到建筑物精细化建模的目的。

MR动态增强扫描减影技术评估肝癌肝动脉栓塞化疗和射频消融术疗效价值研究

目的:探讨MR动态增强扫描减影技术评估肝癌肝动脉栓塞化疗(TACE)和射频消融术(RFA)疗效价值。方法:选取2020年12月-2023年11月于我院进行治疗的40例肝癌患者,依据治疗方式的不同分为观察组与对照组,每组各20例。对照组患者和观察组患者均进行MR检查,对照组患者行TACE治疗方法,观察组患者行RFA治疗方法,对比两组患者的临床疗效、不良反应发生情况、肿瘤灭活率、肝功能以及AFP水平。结果:观察组的总有效率为100.00%,对照组的总有效率为75.00%,经过对比,有显著性差异(P<0.05);对照组不良反应发生率为30.00%,观察组不良反应发生率为5.00%,经过对比,有显著性差异(P<0.05);观察组的肿瘤灭活率为92.86%,对照组的肿瘤灭活率为78.95%,经过对比,有显著性差异(P<0.05);治疗之后,两组患者的ALT和AST均高于治疗之前,观察组显而易见低于对照组,AFP水平低于治疗之前,并且观察组显而易见低于对照组,有显著性差异(P<0.05)。结论:对使用MR动态增强扫描减影技术来进行评估的肝癌患者运用RFA进行治疗,能够显著提高患者的临床治疗效果、降低不良反应发生率、提高肿瘤灭活的几率,以及能够明显改善患者肝功能和提高患者的生活质量与水平,值得在临床进行推广。

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。