Handheld pocket-size Fourier transform profilometry using projector-enabled smartphone

ABSTRACT

Surface Fourier transform profilometry (FTP) is a technique used for reconstructing three-dimensional (3-D) surface topography using light. It has been widely used in machine vision for biomedical and biometric automations, providing solutions beyond conventional 2-D imaging. This paper proposes an implementation of the handheld pocket-size FTP for 3-D surface profile imaging using a projector-enabled Samsung Galaxy Beam smartphone. In the implementation, a crossed-optical-axes geometry of the FTP is formed by using a mirror positioned over the phone’s projector via an adjustable tilt mounting bracket. Experimental proof-of-concept of the proposed profilometry is done by implementing conventional and non-phase shifting FTPs with different diffuse test objects. The experimental results obtained by using the non-phase shifting technique are in good agreement with those of the direct contact measurement. Besides having superiority of compactness, the proposed profilometry paves the way for the development of real-time 3-D profiling and printing through internet or Bluetooth interconnection.     

Building 3-D Human Data Based on Handed Measurement and CNN

3-dimension (3-D) printing technology is growing strongly with many applications, one of which is the garment industry. The application of human body models to the garment industry is necessary to respond to the increasing personalization demand and still guarantee aesthetics. This paper proposes a method to construct 3-D human models by applying deep learning. We calculate the location of the main slices of the human body, including the neck, chest, belly, buttocks, and the rings of the extremities, using pre-existing information. Then, on the positioning frame, we find the key points (fixed and unaltered) of these key slices and update these points to match the current parameters. To add points to a star slice, we use a deep learning model to mimic the form of the human body at that slice position. We use interpolation to produce sub-slices of different body sections based on the main slices to create complete body parts morphologically. We combine all slices to construct a full 3-D representation of the human body.     

基于FBG的三维编织复合材料制件状态健康监测研究

介绍了将FBG嵌入三维编织复合材料的方法,提出了三维编织复合材料状态健康监测方法,分析了材料在拉伸承载下的内部应变与FBG变化关系,提出了信号采集和处理方式。实验结果表明,FBG传感器具有优异的传感特性,复合材料的编织角对FBG的信号有一点影响,植入光纤对复合材料的力学性能影响不大。本课题的研究为先进智能复合材料的研发与应用提供了依据。     

三维编织复合材料力学行为研究进展

随着三维编织复合材料力学行为研究工作的开展,这种材料在很多领域得到越来越广泛的应用。本文从细观结构几何模型、力学行为的理论研究、实验研究三个方面综述了三维编织复合材料力学行为的研究现状,并提出了当前工作存在的问题,对今后研究的趋势进行了展望。     

Fracture analysis of cracks in magneto-electro-elastic solids by the MLPG

A meshless method based on the local Petrov–Galerkin approach is proposed for crack analysis in two-dimensional (2-D) and three-dimensional (3-D) axisymmetric magneto-electric-elastic solids with continuously varying material properties. Axial symmetry of geometry and boundary conditions reduces the original 3-D boundary value problem into a 2-D problem in axial cross section. Stationary and transient dynamic problems are considered in this paper. The local weak formulation is employed on circular subdomains where surrounding nodes randomly spread over the analyzed domain. The test functions are taken as unit step functions in derivation of the local integral equations (LIEs). The moving least-squares (MLS) method is adopted for the approximation of the physical quantities in the LIEs. The accuracy of the present method for computing the stress intensity factors (SIF), electrical displacement intensity factors (EDIF) and magnetic induction intensity factors (MIIF) are discussed by comparison with numerical solutions for homogeneous materials.     

Microscopic Analysis of Continuous Fiber 3D Printing with Oblique Axis for Process Optimization

This article presents a self-developed continuous fiber 3D printing device that incorporates a tilted printing axis. By positioning the print nozzle axis at an obtuse angle to the printing plane, the device effectively prevents the common issue of fiber damage during the 90° extrusion of continuous fibers. This improvement is substantiated through tensile strength experiments. Additionally, the pretreatment stage includes the twisting of continuous fibers to enhance friction along their length. This twisting process enables better retention of the matrix during impregnation, thereby improving impregnation performance. The cross-section of the printed sample is observed by scanning electron microscope, and the microscopic effects of different process parameters on the continuous fiber structure are analyzed. Consequently, a link from process parameters to the mechanical properties of continuous fiber 3D printed specimens is established. This link serves as a foundation for predicting and optimizing the properties of continuous fiber-reinforced materials.     

机械产品三维CAD软件平台

计算机辅助二维设计是相对于手工绘图的进步,参数化技术又使二维CAD富有灵巧性.但是无论进行何种平面几何数据的操作.均无法创立三维产品.CAD的深入发展必将要求与工程分析、真实感造型、数控加工、数据管理和信息流控制等技术集成为一体.长期以来,面向制造业的CAD/CAM软件均基于UNIX工作站平台.其软硬件价格及复杂程度使人望而生畏.随着微机技术的发展,世界著名的Autodesk公司最近新推出基于微机的三维CAD软件平台,为广大机械工程技术人员提供强有力的CAD/CAM手段.本文详细地介绍这一最新软件的功能及用途.     

BiOBr three-dimensional micromaterials in a solvothermal system and their photocatalytical property under visible-light irradiation

In this paper, BiOBr micromaterials with three-dimensional (3-D) microstructures were synthesised in a solvothermal system through modulation of surfactant polyethylene glycol or polyvinylpyrrolidone molecules. The transformation of the 3-D structures to two-dimensional (2-D) microplates along the reaction time was observed. The possible formation mechanism of the 3-D structures was discussed. The BiOBr micromaterials have shown excellent photocatalytical property toward bleaching of methyl blue under visible-light irradiation. The synthetic method would have potential applications in preparing other 3-D microstructures and 2-D microplates.     

Current status of 4D printing technology and the potential of light-reactive smart materials as 4D printable materials

The onset of multi-material 3D printing and the combination of smart materials into the printable material has led to the development of an exciting new technology called 4D printing. This paper will introduce the background and development into 4D printing, discuss water reactive 4D printing methods and temperature reactive 4D printing, modelling and simulation software, and future applications of this new technology. Smart materials that react to different external stimuli are described, along with the benefits of these smart materials and their potential use in 4D printing applications; specifically, existing light-reactive smart materials. 4D printing has the prospective to simplify the design and manufacturing of different products and the potential of automating actuation devices that naturally react to their environment without the need for human interaction, batteries, processors, sensors, and motors.     

三维五向编织复合材料纵向性能的实验研究

通过对具有不同编织结构参数的三维五向编织复合材料试件的纵向拉伸和压缩实验,分析了该类材料的纵向拉、压刚度和强度随编织工艺参数的变化规律以及材料的失效形式.三维五向编织复合材料在破坏前基本保持线弹性,纵向拉、压破坏具有脆性特征,拉伸模量和压缩模量比较接近,但拉伸强度远大于压缩强度.编织角和纤维体积含量对材料性能的影响显著,纱线粗细的影响不大.提高第五向纱线的比例,可提高材料的纵向性能.此外,研究中采用短标距薄板试件,以避免试件产生整体屈曲和端部纤维束开裂破坏.     

一种三维纺织复合材料的本构关系及其性能分析

本文对一种三维增强纤维复合材料的结构与性能进行了研究.通过对手工纺织的三向纤维增强复合材料的分析,建立了其细观力学模型,并在此基础上导出了反映其宏观力学性能的本构关系,同时采用具有相同纺织结构的试件进行试验,对本文的理论结果进行了验证.此外,通过对三维复合材料与层合板的力学性能进行对比试验,说明三维增强复合材料的综合性能,尤其是层间剪切性能得到了很大的改善和提高.     

基于OpenGL的机械制图三维真实感仿真软件研究

介绍了利用OpenGL和Visualc＋＋开发机械制图三维真实感交互式仿真软件的方法,研究了结合面向对象技术和三维可视化技术在机械制图教学的应用,实践表明所开发的三维图形仿真软件可为学生提供高真实感的模型演示和充分发挥学生的想象力。     

On non-linear transformations for the integration of weakly-singular and Cauchy Principal Value integrals

The mathematical foundations of the application of non-linear transformations to the numerical integration of weakly singular and Cauchy Principal Value (CPV) integrals are revised in this paper. This approach was firstly introduced to compute the singular kernels appearing in the Boundary Element Method (BEM) for 2-D (two-dimensional) problems. Here, the mathematical requirements for a consistent application of these methods both for the 2-D and 3-D cases and both for collocation points located in the interior of a typical boundary element and located on its boundary are established. From them, it is shown why some of the transformations proposed in previous papers work while others do not, and also why some of the latter ones work only for the particular examples presented in those papers. Finally, some non-linear transformations for 2-D and 3-D problems that fulfill the mentioned mathematical requirements are here introduced, including a complete numerical study of their accuracy. © 1997 by John Wiley & Sons, Ltd.     

Simulation of seawater intrusion in coastal aquifers: Some typical responses

Seawater intrusion in coastal aquifers is generally three dimensional (3-D) in nature. In the literature, there is a general lack of reported results on 3-D simulations. This paper presents some typical example simulations of 3-D seawater intrusion process for a specified hypothetical study area. The simulation results presented in this paper are based on the density-dependent miscible flow and transport modelling approach for simulation of seawater intrusion in coastal aquifers. A nonlinear optimization-based simulation methodology was used in this study. Various steady state simulations are performed for a specified study area. Response evaluations consider the effects of vertical recharge on seawater intrusion, effects of boundary conditions, and effects of spatially varying pumping from the aquifer. The 3-D simulations demonstrate the viability of using a planned strategy of spatially varying withdrawals from the aquifer to manage seawater intrusion. It is demonstrated that series of pumps near the ocean-face boundary induce a hydraulic head distribution that can be effectively used for controlling seawater intrusion.     

Recent advances in 3D printing of porous ceramics: A review

3D printing, alongside the rapidly advancing field of porous ceramics, is quickly expanding the horizon of what is going to be possible in the future. In this paper, 3D printing technology is evaluated for its compatibility with porous ceramic materials, due to its competitive process in terms of speed and specific tooling, especially for good quality fabrication. The paper reviews the capabilities of these new technology techniques for the fabrication of porous ceramic. The basic technology is the 3D printing techniques, which are used to fabricate porous green ceramic parts that are later sintered. Different ceramic materials are evaluated and the classification of different powders according to their 3D printing quality as well as material aspects is examined. The evaluation of 3D printing process in terms of the powders’ physical properties such as particle size, flowability and wettability is also discussed. The relationship between the different 3D printing parameters and the final printing outcome are assessed.     

采用标记条纹跟踪的冲击过程三维轮廓术

针对在冲击、爆轰等快变化过程的三维轮廓术中,CCD拍摄速度低于物体的运动速度而导致对动态条纹的时间采样不足和物体表面发生破裂而分成数块的动态过程,提出一种采用标记条纹进行跟踪的动态过程三维轮廓术.以傅里叶变换轮廓术为基础,通过采用标记条纹进行跟踪锁定变形条纹中同级次条纹的变化以及Gerchberg迭代算法在破裂区域迭代生成伪条纹,对破裂表面分块进行处理,有效地解决了在快变化动态过程的三维重建中因时间采样不足和条纹断裂对三维相位场的展开所带来的问题,获得了物体正确的面形分布.实验证实了此种方法的正确性.     

连续纤维增强热塑性复合材料3D打印研究进展

连续纤维增强热塑性复合材料(Continuous Fiber Reinforced Thermoplastic Composites,CFRTPCs)具有强度高、寿命长、耐腐蚀和绿色可回收等优点,广泛应用于航空航天、交通运输和高精密加工装备等领域.传统复合材料制造工艺较为复杂、生产周期长且成本较高,先进的3D打印技术可...     

Recent Advances on 3D Printing Technique for Thermal‐Related Applications

Advances in ink formulation and printing techniques make producing material systems with new and versatile characteristics and functionalities possible. Additive manufacturing or 3D printing enables fabricating complex structures at a faster production rate using different types of materials for various applications. Recently, 3D printing methods are being studied for thermal‐related applications. In this paper, the authors review recent progress of materials and printing techniques for thermal application devices using composite materials.

     

3D printing with particles as feedstock materials

3D printing has been applied in numerous research fields ranging from biomedical, mechanical engineering and chemistry to material science. 3D printing applications have driven innovations in particle technology, especially through tackling particle-related issues arising from the development of particle-based printing feedstocks across such application areas. Therefore, in this review, established 3D printing processes are described to include their prototyping mechanisms, advantages and limitations. Various particulate systems, including dry and wet systems, as printing feedstock materials are introduced. The main motivation for this paper is to outline the current state of particulate feedstock systems and to attempt to outline future directions for enhancing these particle applications. This paper would be valuable for individuals, researchers and companies who need adequate and comparative information regarding the state of particle applications in the AM industry.