Polar-coordinate line-projection light-curing continuous 3D printing for tubular structures

3D printing techniques offer an effective method in fabricating complex radially multi-material structures.However,it is challenging for complex and delicate radially multi-material model geometries without supporting structures,such as tissue vessels and tubular graft,among others.In this work,we tackle these challenges by developing a polar digital light processing technique which uses a rod as the printing platform.The 3D model fabrication is accomplished through line projection.The rotation and translation of the rod are synchronized to project and illuminate the photosensitive material volume.By controlling the distance between the rod and the printing window,we achieved the printing of tubular structures with a minimum wall thickness as thin as 50 micrometers.By controlling the width of fine slits at the printing window,we achieved the printing of structures with a minimum feature size of 10 micrometers.Our process accomplished the fabrication of thin-walled tubular graft structure with a thickness of only 100 micrometers and lengths of several centimeters within a timeframe of just 100 s.Additionally,it enables the printing of axial multi-material structures,thereby achieving adjustable mechanical strength.This method is conducive to rapid customization of tubular grafts and the manufacturing of tubular components in fields such as dentistry,aerospace,and more.

Projected Changes in the Climate Zoning of Côte d’Ivoire

This study assesses the projected changes in the climate zoning of Côte d’Ivoire using the hierarchical classification of principal components (HCPC) method applied to the daily precipitation data of an ensemble of 14 CORDEX-AFRICA simulations under RCP4.5 and RCP8.5 scenarios. The results indicate the existence of three climate zones in Côte d’Ivoire (the coastal, the centre and the north) over the historical period (1981-2005). Moreover, CORDEX simulations project an extension of the surface area of drier climatic zones while a reduction of wetter zones, associated with the appearance of an intermediate climate zone with surface area varying from 77,560 km2 to 134,960 km2 depending on the period and the scenario. These results highlight the potential impacts of climate change on the delimitation of the climate zones of Côte d’Ivoire under the greenhouse gas emission scenarios. Thus, there is a reduction in the surface areas suitable for the production of cash crops such as cocoa and coffee. This could hinder the country’s economy and development, mainly based on these cash crops.

Construction Cost Control Strategy of Finished House Based on BIM-5D

Building Information Modeling(BIM)technology can not only achieve project refinement management of the construction process based on a 3D model but also form a BIM-5D model based on the fusion of progress data and cost data to achieve the dynamic control of the whole process of project cost.This paper discusses the application of BIM-5D in the cost control of finished house construction,aiming to provide technical reference for China’s finished house project units,so that they can master how to realize the construction of cost control system based on BIM,the monitoring of the key coefficients of the cost,corrective action,to ensure that the project cost deviation is within the controllable range,and to make an effective guarantee for the economic benefits of the project construction.

Research on Automatic Elimination of Laptop Computer in Security CT Images Based on Projection Algorithm and YOLOv7-Seg

In civil aviation security screening, laptops, with their intricate structural composition, provide the potential for criminals to conceal dangerous items. Presently, the security process necessitates passengers to individually present their laptops for inspection. The paper introduced a method for laptop removal. By combining projection algorithms with the YOLOv7-Seg model, a laptop’s three views were generated through projection, and instance segmentation of these views was achieved using YOLOv7-Seg. The resulting 2D masks from instance segmentation at different angles were employed to reconstruct a 3D mask through angle restoration. Ultimately, the intersection of this 3D mask with the original 3D data enabled the successful extraction of the laptop’s 3D information. Experimental results demonstrated that the fusion of projection and instance segmentation facilitated the automatic removal of laptops from CT data. Moreover, higher instance segmentation model accuracy leads to more precise removal outcomes. By implementing the laptop removal functionality, the civil aviation security screening process becomes more efficient and convenient. Passengers will no longer be required to individually handle their laptops, effectively enhancing the efficiency and accuracy of security screening.

New algorithm for solving 3D incompressible viscous equations based on projection method

A new algorithm based on the projection method with the implicit finite difference technique was established to calculate the velocity fields and pressure.The calculation region can be divided into different regions according to Reynolds number.In the far-wall region,the thermal melt flow was calculated as Newtonian flow.In the near-wall region,the thermal melt flow was calculated as non-Newtonian flow.It was proved that the new algorithm based on the projection method with the implicit technique was correct through nonparametric statistics method and experiment.The simulation results show that the new algorithm based on the projection method with the implicit technique calculates more quickly than the solution algorithm-volume of fluid method using the explicit difference method.

Research and development of fringe projection-based methods in 3D shape reconstruction

This paper discusses current research and development of fringe projection-based techniques. A system based on Fourier transform profilometry (FTP) is proposed for three-dimensional (3D) shape recovery. The system improves the method of phase unwrapping to gain accurate 3D shapes of objects. The method uses a region-growing algorithm for the path prediction guided by the quality map to increase the recovering accuracy and provides a fast and simple tool for 3D shape recovery. The shape measurement and data recovery are integrated to offer a new method of 3D modelling. Examples are presented to verify the feasibility of the proposed method.

Uncertainty Theory Based Novel Multi-Objective Optimization Technique Using Embedding Theorem with Application to R &D Project Portfolio Selection

This paper introduces a novice solution methodology for multi-objective optimization problems having the coefficients in the form of uncertain variables. The embedding theorem, which establishes that the set of uncertain variables can be embedded into the Banach space C[0, 1] × C[0, 1] isometrically and isomorphically, is developed. Based on this embedding theorem, each objective with uncertain coefficients can be transformed into two objectives with crisp coefficients. The solution of the original m-objectives optimization problem with uncertain coefficients will be obtained by solving the corresponding 2 m-objectives crisp optimization problem. The R & D project portfolio decision deals with future events and opportunities, much of the information required to make portfolio decisions is uncertain. Here parameters like outcome, risk, and cost are considered as uncertain variables and an uncertain bi-objective optimization problem with some useful constraints is developed. The corresponding crisp tetra-objective optimization model is then developed by embedding theorem. The feasibility and effectiveness of the proposed method is verified by a real case study with the consideration that the uncertain variables are triangular in nature.

Projection micro stereolithography based 3D printing and its applications

Projection micro stereolithography(PμSL)is a high-resolution(up to 0.6μm)3D printing technology based on area projection triggered photopolymerization,and capable of fabricating complex 3D architectures covering multiple scales and with multiple materials.This paper reviews the recent development of the PμSL based 3D printing technologies,together with the related applications.It introduces the working principle,the commercialized products,and the recent multiscale,multimaterial printing capability of PμSL as well as some functional photopolymers that are suitable to PμSL.This review paper also summarizes a few typical applications of PμSL including mechanical metamaterials,optical components,4D printing,bioinspired materials and biomedical applications,and offers perspectives on the directions of the further development of PμSL based 3D printing technology.

DIRECT VOXEL-PROJECTION FOR VOLUMETRIC DATA RENDERING IN MEDICAL IMAGERY

The volumetric rendering of 3 D medical image data is very effective method for communication about radiological studies to clinicians. Algorithms that produce images with artifacts and inaccuracies are not clinically useful. This paper proposed a direct voxel projection algorithm to implement volumetric data rendering. Using this algorithm, arbitrary volume rotation, transparent and cutaway views are generated satisfactorily. Compared with the existing raytracing methods, it improves the projection image quality greatly. Some experimental results about real medical CT image data demonstrate the advantages and fidelity of the proposed algorithm.

Three-Dimensional Visual Analysis for Construction Layout of Reservoir Project

It is difficult to analyze the inter-relationship for the construction layout of a reservoir project scientifically and intuitively.According to the characteristics of broad field and huge information,the modeling methods of digital terrain and solid model as well as the techniques of texture mapping and scene navigation are adopted.The simulation system is developed by C program language,which includes the functions of the interactive navigation of 3D scene,the visual inquiry of project digital model information,the storage and management of project information.A certain reservoir is taken as a case.The 3D visual analysis for the construction layout and engineering information are obtained.The proposed system is of great advantages in dealing with large amount of information and the method provides a theoretical basis and technical support for the construction layout of a reservoir project.

R & D project's investment evaluation based on real option and its value at risk

The authors looked upon it as real options and applied the VaR(Value at Risk) method to the evaluation of its risk value based on the analysis of R & D project investment characteristics,and advanced the evaluation model of the project’s return and risk according to financial theories.This paper expounded the two dimension evaluation model of project,and divided it into five decision making regions.

Introduction to the scientific——achievements of construction machinery for thermal power and T■D projects

The Construction Machinery Division (CMD) in the Re-search Institute of Electric Power Construction (EPCRI) isa R&D organization specialized on construction machinery andtechnology for thermal power station and transmission & distributionprojects.It was established in 1964.There are now 45 scientific re-

Time and Cost Planning of a Housing Construction Project Using Building Information Modelling

Conventional ways of building construction process lack proper task scheduling and planning of the project work at the site resulting in poor monitoring of the whole process.Building information modelling(BIM)creates a platform where all the information of every single element of the construction process can be virtually integrated.The integration of 3D elements of a building model with its scheduled time and cost parameters results in 5D BIM.This feature enables the visualization,scheduling,planning,and monitoring and clash detection of all pre-construction,construction and post-construction processes of a building.The present study used the information of a live project of a traditionally built residential building which was remodeled using 5D BIM technique.The purpose of this study was to compare and analyses the impact of 5D BIM on time and cost parameters of the live project.

LEAPS IN G.D.-H.K. COOPERATION FOLLOWING RETURN——Report on Guangdong High New Technology Projects Investment Symposium '97

Hongkong’s smooth return creates vast prospect and numerous opportunities for Guangdong-Hongkong economic cooperation. Over the past decade the cooperation has gone a long way, from non-governmental to governmental, from processing trade to high technology. Presently, it has become a highprofile activity which covers various areas.More than 20,000 representatives from 5,063 corporations participated the symposium. And 1,559 agreements, involving $ 13.159 billion, were signed. Of the investment, $8.7851 billion, or 66.8 per cent is from overseas investors. Of the agreements, 810 or 65 per cent, are high new

Origin of Magnetic Fields of Stellar Objects in the Universe Based on the 5D Projection Theory

Beginning with a 5D homogeneous universe [1], we have provided a plausible explanation of the self-rotation phenomenon of stellar objects previously with illustration of large number of star samples [2], via a 5D-4D projection. The origin of such rotation is the balance of the angular momenta of stars and that of positive and negative charged e-trino pairs, within a 3D ⊗1D?void of the stellar object, the existence of which is based on conservation/parity laws in physics if one starts with homogeneous 5D universe. While the in-phase e-trino pairs are proposed to be responsible for the generation of angular momentum, the anti-phase but oppositely charge pairs necessarily produce currents. In the 5D to 4D projection, one space variable in the 5D manifold was compacted to zero in most other 5D theories (including theories of Kaluza-Klein and Einstein [3] [4]). We have demonstrated, using the Fermat’s Last Theorem [5], that for validity of gauge invariance at the 4D-5D boundary, the 4th space variable in the 5D manifold is mapped into two current rings at both magnetic poles as required by Perelman entropy mapping;these loops are the origin of the dipolar magnetic field. One conclusion we draw is that there is no gravitational singularity, and hence no black holes in the universe, a result strongly supported by the recent discovery of many stars with masses well greater than 100 solar mass [6] [7] [8], without trace of phenomena observed (such as strong gamma and X ray emissions), which are supposed to be associated with black holes. We analyze the properties of such loop currents on the 4D-5D boundary, where Maxwell equations are valid. We derive explicit expressions for the dipolar fields over the whole temperature range. We then compare our prediction with measured surface magnetic fields of many stars. Since there is coupling in distribution between the in-phase and anti-phase pairs of e-trinos, the generated mag-netic field is directly related to the angular momentum, leading to the result that the magnetic field can be expressible in terms of only the mechanical variables (mass M, radius R, rotation period P)of a star, as if Maxwell equations are “hidden”. An explanation for the occurrence of this “un-expected result” is provided in Section (7.6). Therefore we provide satisfactory answers to a number of “mysteries” of magnetism in astrophysics such as the “Magnetic Bode’s Relation/Law” [9] and the experimental finding that B-P graph in the log-log plot is linear. Moreover, we have developed a new method for studying the relations among the data (M, R, P) during stellar evolution. Ten groups of stellar objects, effectively over 2000 samples are used in various parts of the analysis. We also explain the emergence of huge magnetic field in very old stars like White Dwarfs in terms of formation of 2D Semion state on stellar surface and release of magnetic flux as magnetic storms upon changing the 2D state back to 3D structure. Moreover, we provide an explanation, on the ground of the 5D theory, for the detection of extremely weak fields in Venus and Mars and the asymmetric distribution of magnetic field on the Martian surface. We predict the equatorial fields B of the newly discovered Trappist-1 star and the 6 nearest planets. The log B?−?log P graph for the 6 planets is linear and they satisfy the Magnetic Bode’s relation. Based on the above analysis, we have discovered several new laws of stellar magnetism, which are summarized in Section (7.6).

全尺寸3D打印概念车DB Project问世

概念车通常是手工打造的,造价高昂且非常耗时。3D打印可大幅缩短设计时间。日本设计师与MARIE3D公司合作,共同打造了全球首款全尺寸3D打印概念车,名为DB Project。尽管该概念车是由MASSIVit 18003D打印机制造的,但它看起来更像一个雕刻作品。从不同角度看,其车身外部展现了不同的外观。MASSIVit为大尺寸3D打印机提供了凝胶点胶印刷(GDP)技术。该技术可利用紫外线使凝胶材料快速固化。

国外R&D项目测度与评价研究述评

为培育核心技术能力和维持持续竞争优势 ,企业不仅越来越重视R&D ,而且日益关注R&D项目的测度与评价。本文在回顾R&D项目评价的发展历程和主要流派的基础上 ,评述了国外R&D项目评价的理论与方法 。

改进的基于多依赖性的R＆D项目组合选择模型

复杂产品开发企业往往拥有多个产品线开发项目和公用技术平台开发项目.由于资源的稀缺性,企业决策者不得不面临着R&D项目组合选择的难题.针对复杂产品开发过程中存在的多项目间混合依赖特性,采用关联性分配矩阵定量化描述三个及以上项目共同作用时的相互依赖程度;综合考虑项目间的收益依赖、资源依赖和技术依赖等关联特征,构建一种新颖的面向研发项目组合选择问题的非线性规划模型;并设计和实现了基于模拟退火的相关求解算法.最后将本文提出的方法应用于国内某汽车公司的研发项目组合管理实践中,实验结果证明了该方法的合理性与有效性.

R&D项目管理的模式及其高标定位研究

加强R&D项目管理对于提高企业的创新能力和获取持续竞争优势具有十分重要的意义。本文对RodCoombs等人提出的R&D项目管理审计模型进行了改进 ,提出了R&D项目管理多阶段交互模式及其高标定位模板 ,这种模式是以获取持续竞争优势为目的的核心能力的培育和提高。同时 ,指出了不同目标和环境下的R&D项目管理应有不同的审计标准。

国内外R&D项目评价研究述评

为培育核心技术能力和维持持续竞争优势 ,企业不仅越来越重视 R& D,而且日益关注 R& D项目的测度与评价。在回顾 R& D项目评价的发展历程和主要流派的基础上 ,评述了国外 R& D项目评价的理论与方法 ,并介绍了目前 R& D项目评价的新趋势。