Printability disparities in heterogeneous material combinations via laser directed energy deposition:a comparative study

Additive manufacturing provides achievability for the fabrication of bimetallic and multi-material structures;however,the material compatibility and bondability directly affect the parts’formability and final quality.It is essential to understand the underlying printability of different material combinations based on an adapted process.Here,the printability disparities of two common and attractive material combinations(nickel-and iron-based alloys)are evaluated at the macro and micro levels via laser directed energy deposition(DED).The deposition processes were captured using in situ high-speed imaging,and the dissimilarities in melt pool features and track morphology were quantitatively investigated within specific process windows.Moreover,the microstructure diversity of the tracks and blocks processed with varied material pairs was comparatively elaborated and,complemented with the informative multi-physics modeling,the presented non-uniformity in mechanical properties(microhardness)among the heterogeneous material pairs was rationalized.The differences in melt flow induced by the unlike thermophysical properties of the material pairs and the resulting element intermixing and localized re-alloying during solidification dominate the presented dissimilarity in printability among the material combinations.This work provides an in-depth understanding of the phenomenological differences in the deposition of dissimilar materials and aims to guide more reliable DED forming of bimetallic parts.

Optimization of Fixture Number in Large Thin-Walled Parts Assembly Based on IPSO

There are lots of researches on fixture layout optimization for large thin-walled parts.Current researches focus on the positioning problem,i.e.,optimizing the positions of a constant number of fixtures.However,how to determine the number of fixtures is ignored.In most cases,the number of fixtures located on large thin-walled parts is determined based on engineering experience,which leads to huge fixture number and extra waste.Therefore,this paper constructs an optimization model to minimize the number of fixtures.The constraints are set in the optimization model to ensure that the part deformation is within the surface profile tolerance.In addition,the assembly gap between two parts is also controlled.To conduct the optimization,this paper develops an improved particle swarm optimization(IPSO)algorithm by integrating the shrinkage factor and adaptive inertia weight.In the algorithm,particles are encoded according to the fixture position.Each dimension of the particle is assigned to a sub-region by constraining the optional position range of each fixture to improve the optimization efficiency.Finally,a case study on ship curved panel assembly is provided to prove that our method can optimize the number of fixtures while meeting the assembly quality requirements.This research proposes a method to optimize the number of fixtures,which can reduce the number of fixtures and achieve deformation control at the same time.

Development of Fixture Layout Optimization for Thin-Walled Parts:A Review

An increasing number of researchers have researched fixture layout optimization for thin-walled part assembly during the past decades.However,few papers systematically review these researches.By analyzing existing literature,this paper summarizes the process of fixture layout optimization and the methods applied.The process of optimization is made up of optimization objective setting,assembly variation/deformation modeling,and fixture layout optimization.This paper makes a review of the fixture layout for thin-walled parts according to these three steps.First,two different kinds of optimization objectives are introduced.Researchers usually consider in-plane variations or out-of-plane deformations when designing objectives.Then,modeling methods for assembly variation and deformation are divided into two categories:Mechanism-based and data-based methods.Several common methods are discussed respectively.After that,optimization algorithms are reviewed systematically.There are two kinds of optimization algorithms:Traditional nonlinear programming and heuristic algorithms.Finally,discussions on the current situation are provided.The research direction of fixture layout optimization in the future is discussed from three aspects:Objective setting,improving modeling accuracy and optimization algorithms.Also,a new research point for fixture layout optimization is discussed.This paper systematically reviews the research on fixture layout optimization for thin-walled parts,and provides a reference for future research in this field.

Research on intelligent search-and-secure technology in accelerator hazardous areas based on machine vision

Prompt radiation emitted during accelerator operation poses a significant health risk,necessitating a thorough search and securing of hazardous areas prior to initiation.Currently,manual sweep methods are employed.However,the limitations of manual sweeps have become increasingly evident with the implementation of large-scale accelerators.By leveraging advancements in machine vision technology,the automatic identification of stranded personnel in controlled areas through camera imagery presents a viable solution for efficient search and security.Given the criticality of personal safety for stranded individuals,search and security processes must be sufficiently reliable.To ensure comprehensive coverage,180°camera groups were strategically positioned on both sides of the accelerator tunnel to eliminate blind spots within the monitoring range.The YOLOV8 network model was modified to enable the detection of small targets,such as hands and feet,as well as larger targets formed by individuals near the cameras.Furthermore,the system incorporates a pedestrian recognition model that detects human body parts,and an information fusion strategy is used to integrate the detected head,hands,and feet with the identified pedestrians as a cohesive unit.This strategy enhanced the capability of the model to identify pedestrians obstructed by equipment,resulting in a notable improvement in the recall rate.Specifically,recall rates of 0.915 and 0.82were obtained for Datasets 1 and 2,respectively.Although there was a slight decrease in accuracy,it aligned with the intended purpose of the search-and-secure software design.Experimental tests conducted within an accelerator tunnel demonstrated the effectiveness of this approach in achieving reliable recognition outcomes.

A Systematic Review of Computer Vision Techniques for Quality Control in End-of-Line Visual Inspection of Antenna Parts

The rapid evolution of wireless communication technologies has underscored the critical role of antennas in ensuring seamless connectivity.Antenna defects,ranging from manufacturing imperfections to environmental wear,pose significant challenges to the reliability and performance of communication systems.This review paper navigates the landscape of antenna defect detection,emphasizing the need for a nuanced understanding of various defect types and the associated challenges in visual detection.This review paper serves as a valuable resource for researchers,engineers,and practitioners engaged in the design and maintenance of communication systems.The insights presented here pave the way for enhanced reliability in antenna systems through targeted defect detection measures.In this study,a comprehensive literature analysis on computer vision algorithms that are employed in end-of-line visual inspection of antenna parts is presented.The PRISMA principles will be followed throughout the review,and its goals are to provide a summary of recent research,identify relevant computer vision techniques,and evaluate how effective these techniques are in discovering defects during inspections.It contains articles from scholarly journals as well as papers presented at conferences up until June 2023.This research utilized search phrases that were relevant,and papers were chosen based on whether or not they met certain inclusion and exclusion criteria.In this study,several different computer vision approaches,such as feature extraction and defect classification,are broken down and analyzed.Additionally,their applicability and performance are discussed.The review highlights the significance of utilizing a wide variety of datasets and measurement criteria.The findings of this study add to the existing body of knowledge and point researchers in the direction of promising new areas of investigation,such as real-time inspection systems and multispectral imaging.This review,on its whole,offers a complete study of computer vision approaches for quality control in antenna parts.It does so by providing helpful insights and drawing attention to areas that require additional exploration.

“三美论”视角下对比赏析When We Two Parted的汉译本——以查良铮和陈锡麟的译本为例

“三美论”是许渊冲先生提出的翻译理论,所谓的“三美”指的是意美、音美和形美。本文以许渊冲先生的“三美论”为理论指导,对比赏析查良铮和陈锡麟对乔治•戈登•拜伦诗歌When We Two Parted的两个中译本。从意美、音美和形美三个层面,对比赏析两个中译本对原文意境、诗歌节奏和尾韵以及诗歌形式上的再现。在诗歌汉译中,三美难以兼顾,译者在进行翻译时要分清主次,原则是意美大于音美,音美大于形美。

DISCRETIZATION APPROACH USING RAY-TESTING MODEL IN PARTING LINE AND PARTING SURFACE GENERATION

Surface classification, 3D parting line, parting surface generation and demoldability analysis which is helpful to select optimal parting direction and optimal parting line are involved in auto-matic cavity design based on the my-testing model. A new ray-testing approach is presented to classify the part surfaces to core/cavity surfaces and undercut surfaces by automatic identifying the visibility of surfaces. A simple, direct and efficient algorithm to identify surface visibility is developed. The algorithm is robust and adapted to rather complicated geometry, so it is valuable in computer-aided mold design systems. To validate the efficiency of the approach, an experimental program is implemented. Case studies show that the approach is practical and valuable in automatic parting line and parting surface generation.

Geochemistry of Sulfur and Hazardous Elements in Late Paleozoic Coals and Partings from Taozao Coalfield, Shandong Province, China

The analyses of different sulfur forms, the trace elements in pyrites using electron microprobe and the trace elements in coal using INAA (instrumental neutron activation analysis) of the Late Paleozoic coals from the Taozao coalfield in Shandong Province, China, conclude that most sulfur (>75 %) in high-sulfur coal of Taiyuan Formation occurred as pyrite, in which many hazardous elements co-existed and their concentrations varied with their geological origin. The concentrations of hazardous elements in high-sulfur coals from Taiyuan Formation, composing mainly of Cu, As, U, Pb, Mo and Co, are much higher than those in the low-sulfur coals from Shanxi Formation and Shihezi Formation, because the influence of seawater during and after coal accumulation in Taiyuan Formation is stronger than those in Shanxi and Shihezi formations. Moreover, the element As is related to Fe, and both elements exist mainly in the form of pyrite. The element U is richer in the coal influenced by seawater. In addition, the coal affected by the magmatism contains more U, too. When high-sulfur coals are processed with heavy media washing to remove sulfur and minerals, the majority of hazardous elements will also be removed from the coals.

DESIGN TECHNOLOGY FOR INJECTION MOLD PARTING SURFACE BASED ON CASES AND KNOWLEDGE

On the basis of the comprehensive analysis about the automatic generation of the injection mold parting surface, the parting surface design method which introduces knowledge and case-based reasoning （CBR） into the computer-aided design is described by combining with the actual characteristic in injection mold design, and the design process of case-based reasoning method is also given. A case library including the information of parting surface is built with the index of main shape features, The automatic design of the mold parting surface is realized combined with the forward-reasoning method and the similarity solution procedure. The rule knowledge library is also founded including the knowledge, principles and experiences for parting surface design. An example is used to show the validity of the method, and the quality and the efficiency of the mold design are improved.

A Ray-Testing Approach to Automatically Identify Surface Visibility in Parting Line Generation

It is critical to identify core/cavity and undercut surfaces of molds in parting line generation. A new Ray-Testing approach is presented to detect these surfaces by identifying the visibility of surfaces. A simple, direct and efficient algorithm to identify surface visibility is developed. Case studies show that the approach is practical and valuable in automated parting line generation.

Cylindrical coordinate measuring machines: probe offset and workpiece clamping error

A cylindrical coordinate measuring machine for the detection of large-size rotational parts is introduced. The measuring machine can simultaneously measure the geometrical dimensions, form and position errors of the inner and outer surfaces. Since the maximum length of the workpiece can reach 2 000 mm , it is difficult to be clamped and adjusted and easy to produce clamping error. The eccentricity can be up to 1.5 mm, which has an interaction effect with the probe mounting offset. We mainly study the probe offset of the measuring machine and the influence of the workpiece clamping error on the measurement. A method of controlling the offset of the measuring probe is proposed. The effect of the clamping error is eliminated through the space coordinate transformation of the workpiece axis, and the axis is fitted by the least square method. Finally, a common fixture can be realized to meet the clamping requirements of the workpiece.

CAD APPROACH FOR PLASTIC MOULD PARTING DIRECTIONS OPTIMIZATION

A CAD approach which can optimize and automate the parting direction determination is presented. The approach is based on the geometrical and topological information of the solid modelling of the plastic moulded part in order to select a pair of optimal parting directions of a two plate mould which minimizes the number of side cores. The shell of a part is divided into inter influential regions and non influential faces in the mould design point of view. Through analyzing and computing the accessibility direction cones of the inter influential regions, the optimal parting directions can be determined automatically.

A Survey on Deep Learning-Based 2D Human Pose Estimation Models

In this article,a comprehensive survey of deep learning-based(DLbased)human pose estimation(HPE)that can help researchers in the domain of computer vision is presented.HPE is among the fastest-growing research domains of computer vision and is used in solving several problems for human endeavours.After the detailed introduction,three different human body modes followed by the main stages of HPE and two pipelines of twodimensional(2D)HPE are presented.The details of the four components of HPE are also presented.The keypoints output format of two popular 2D HPE datasets and the most cited DL-based HPE articles from the year of breakthrough are both shown in tabular form.This study intends to highlight the limitations of published reviews and surveys respecting presenting a systematic review of the current DL-based solution to the 2D HPE model.Furthermore,a detailed and meaningful survey that will guide new and existing researchers on DL-based 2D HPE models is achieved.Finally,some future research directions in the field of HPE,such as limited data on disabled persons and multi-training DL-based models,are revealed to encourage researchers and promote the growth of HPE research.

AN INTEGRATION BY PARTS FORMULA FOR STOCHASTIC HEAT EQUATIONS WITH FRACTIONAL NOISE

In this paper,we establish the integration by parts formula for the solution of fractional noise driven stochastic heat equations using the method of coupling.As an application,we also obtain the shift Harnack inequalities.

Rapid Manufacturing of Metal Parts

As a key technology of rapid prototyping and manufacturing (RP&M), rapid manufacturing of metal parts is a target of RP&M. Introducing selective laser sintering (SLS), an important branch of RP&M, this paper gives a new method oriented on low power SLS system to fabricate metal parts. With this kind of technology, the mixture of metal and polymer powder is sintered first to get green part, then, after debinding and metal infiltration, dense parts are gotten. In the end, influencing factors of this technology are analyzed. At the same time, some applications are given.

基于价值网的科技金融平台运作模式研究

科技金融平台是金融交易主体与其生存发展的内外环境之间,通过信用流动和货币循环形成的相互关联、相互作用并且能够自动调节的整体运营机制。1归纳了现有协同规则缺乏、策略机制欠缺、运营主体不明、商业模式不足、项目发现滞后5大瓶颈问题;2从价值网视角,重构了科技金融平台,并使用价值网PARTS模型,从科技金融平台参与者和涵盖范围等方面,分析了科技金融平台体系结构;3从平台价值增值过程、参与者耦合规则、参与机构合作竞争策略等方面,重点分析了科技金融平台运作机制。研究表明,应用价值网重构科技金融平台,有利于全面分析平台存在的问题,清楚呈现科技金融平台框架及其运作模式。

不锈钢叶轮五轴联动数控加工中仿真技术应用研究

分析了五轴联动数控中心加工不锈钢叶轮的技术难点,并运用仿真技术加以解决。提出了仿真方法和仿真流程,并基于VERICUT仿真平台,以某型号叶轮的加工过程为例,实际进行了仿真。仿真结果显示加工刀具、加工参数对叶轮质量有重要影响。分析了仿真出现的问题,通过改变刀具、优化加工方案,最终完成了加工。实践证明,仿真技术有利于提高不锈钢叶轮的加工成功率,改进加工质量。

基于正交试验的注塑制件翘曲变形模拟分析

利用模流分析软件Moldflow对注塑制件葡萄筐盖进行翘曲变形分析,基于正交试验对模拟结果数据进行直观分析和方差分析,得出充填压力、保压时间、熔体温度、模具温度对翘曲变形的显著性,并获得试验水平基础上使制件翘曲量最小的最优参数组合以及最优参数组合下的制件翘曲值,并通过试验验证了结论的正确性。

Comparison of Growth of Four Types of Atractylodes Lancea(Thunb.)DC.

[Objective] The research aimed to compare the photosynthetic rates and growth conditions of four types of Atractylodes Lancea（ Thunb.） DC.. [Method] A. Lancea was divided into four types：the saw-tooth-leaf, the ellipse-leaf, the long-ellipse-leaf as well as the sharp-leaf, according to leaf morphology. The photosynthetic rates of four types of A. Lancea were determined by the portable photosynthetic instrument LI-6400 in natural environment. The parameters such as stem width, stem height, leaf area of single plant of aboveground parts were measured periodically. [Result] The photosynthetic rates of four types of A. Lancea were： the saw-tooth-leaf 20. 2 μmol/（ m^2·s）, the ellipse-leaf 18.96 μmol/（m^2·s）, the long-ellipse-leaf 15.6 μmol/（ m^2·s） and the sharp-leaf 17.6 μmol/（m^2·s）, respectively. The photosynthetic rate of the saw-tooth-leaf was higher than the other three types. The growth rate of the saw-tooth-leaf was the highest in the four types at 0.01 level. [Conclusion] The research provided certain theoretic basis for further research on A. Lancea.

基于PARTS战略的应用型本科旅游管理专业实践教学改革探索

文章在旅游应用型人才培养现状与培养定位严重错位的背景下,以提高学生综合职业能力为目标,创新性地将源自战略管理竞合理论中的PARTS战略引入旅游管理专业实践教学改革中,从教学主体、合作利益、合作机制、教学方式、教学内容五个方面对实践教学体系改革进行了探索,以期提高旅游实践教学效果,强化旅游应用人才培养质量。