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Research and industrialization of near-net rolling technology used in shaft parts

Zhenghuan HU, Baoyu WANG, Zhenhua ZHENG

《机械工程前沿（英文）》 2018年第13卷第1期页码 17-24 doi: 10.1007/s11465-018-0480-3

摘要：

Shaft part rolling is an efficient and green near-net shaping technology offering many advantages, including high production efficiency, high material utilization rate, high product quality, and excellent production environment. In this paper, the features of shaft part rolling are introduced along with the working principles of two main shaft part rolling technologies, namely, cross wedge rolling (CWR) and skew rolling (SR). In relation to this technology, some R&D achievements gained by the University of Science and Technology Beijing are summarized. Finally, the latest developments in shaft part rolling are presented, including SR steel balls, precise forming of camshaft blank by CWR, SR phosphorous copper balls at room temperature, and CWR hollow axle sleeve. Although the shaft part rolling technology has been widely used in China, it only accounts for about 15% of applicable parts at present. Nevertheless, this technology has broad application prospects.

关键词： cross wedge rolling skew rolling near-net rolling shaft part

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Special issue: Near-net shaping technology

Dequn LI, Dongming GUO, Qingxue HUANG, Yanchun LOU

《机械工程前沿（英文）》 2018年第13卷第1期页码 1-2 doi: 10.1007/s11465-018-0497-7

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Determining casting defects in near-net shape casting aluminum parts by computed tomography

Jiehua LI, Bernd OBERDORFER, Daniel HABE, Peter SCHUMACHER

《机械工程前沿（英文）》 2018年第13卷第1期页码 48-52 doi: 10.1007/s11465-018-0493-y

摘要：

Three types of near-net shape casting aluminum parts were investigated by computed tomography to determine casting defects and evaluate quality. The first, second, and third parts were produced by low-pressure die casting (Al-12Si-0.8Cu-0.5Fe-0.9Mg-0.7Ni-0.2Zn alloy), die casting (A356, Al-7Si-0.3Mg), and semi-solid casting (A356, Al-7Si-0.3Mg), respectively. Unlike die casting (second part), low-pressure die casting (first part) significantly reduced the formation of casting defects (i.e., porosity) due to its smooth filling and solidification under pressure. No significant casting defect was observed in the third part, and this absence of defects indicates that semi-solid casting could produce high-quality near-net shape casting aluminum parts. Moreover, casting defects were mostly distributed along the eutectic grain boundaries. This finding reveals that refinement of eutectic grains is necessary to optimize the distribution of casting defects and reduce their size. This investigation demonstrated that computed tomography is an efficient method to determine casting defects in near-net shape casting aluminum parts.

关键词： near-net shape casting aluminum parts casting defects low pressure die casting die casting semi-solid casting computed tomography

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A rolling 6U parallel mechanism

Zhihuai MIAO, Yanan YAO

《机械工程前沿（英文）》 2011年第6卷第1期页码 96-98 doi: 10.1007/s11465-011-0214-2

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Novel probabilistic rolling regular tetrahedron mechanism

Yonghan GUAN, Yan’an YAO, Chao LIU, Ruiming LI

《机械工程前沿（英文）》 2021年第16卷第2期页码 363-378 doi: 10.1007/s11465-020-0628-9

摘要： With recent relevant publications on stochastic motion robots in , , and other journals, research on such robots has gained increasing attention. However, theoretical and applied research on stochastic motion in the field of robotics and mechanisms face many challenges due to the uncertainty of stochastic motion. Currently, a large gap remains in the research of stochastic motion mechanism. In this study, a novel mechanism that can conduct probabilistic rolling is proposed to reach a designated position and achieve overlying movement over a particular area. The mechanism consists of a regular tetrahedron frame, a central node, and four connecting linear actuators. According to mobility and kinematic analyses, the mechanism can implement probabilistic rolling. Each rolling gait has three probable rolling directions, and the mechanism rolls in one of the three directions in probability. A kinematic simulation is conducted, and a control method is proposed on the basis of the moving path analysis. Furthermore, the mathematical principle of probabilistic rolling is revealed in terms of probability theory and statistics. Lastly, a prototype is fabricated. To achieve the rolling function, the design of the linear actuators is improved, and the extension ratio is increased from 0.58 to 1.13. Then, tests are conducted. In a 4 m test site, the mechanism makes 11 moves to reach the target position and covers 29.25% of the site.

关键词： mobile mechanism probabilistic motion rolling mechanism stochastic motion

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A rolling 3-UPU parallel mechanism

Zhihuai MIAO, Yan’an YAO, Xianwen KONG

《机械工程前沿（英文）》 2013年第8卷第4期页码 340-349 doi: 10.1007/s11465-013-0282-6

摘要：

A novel rolling mechanism is proposed based on a 3-UPU parallel mechanism in this paper. The rolling mechanism is composed of two platforms connected by three UPU (universal-prismatic-universal) serial-chain type limbs. The degree-of-freedom of the mechanism is analyzed using screw theory. Gait analysis and stability analysis are presented in detail. Four rolling modes of the mechanism are discussed and simulated. The feasibility of the rolling mechanism is verified by means of a physical prototype. Finally, its terrain adaptability is enhanced through planning the rolling gaits.

关键词： parallel mechanism rolling mechanism screw theory

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Study on the Path of “Near-zero Emission” Coal-based Clean Energy Ecosystem Development

Zhang Yu-zhuo

《工程管理前沿（英文）》 2014年第1卷第1期页码 37-41 doi: 10.15302/J-FEM-2014007

摘要： Developing a "near-zero emission" coal-based clean energy ecosystem bears great significance for the sustainable development of clean energy in China and the world at large. This article delves into the development strategy, implementation pathways and key priorities of China's "near-zero emission" coal-based clean energy ecosystem, and in turn proposes specific measures to underpin the development and implementation of such system.

关键词： near-zero emission clean energy ecosystem study on the path

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板带轧制工艺控制理论概要

张进之

《中国工程科学》 2001年第3卷第4期页码 46-55

摘要：

以最小阻力定律、体积不变条件和秒流量相等条件为内容的经典轧制理论，经试验、演绎形成了较完整的轧制应用技术科学体系，这种体系所反映的是静态规律。在轧制理论发展中引入控制论、信息论、计算机科学等高新技术，对轧制过程进行控制。在轧制理论发展史上，弹跳方程建立之前是以力学为基础建立的经典轧制理论，之后为以力学和控制论为基础建立的基本轧制工艺控制理论。文章提出工艺控制理论概念，是在基本轧制工艺控制理论的基础上建立的新的理论体系，主要内容包括：在连轧张力理论中反映了张力的负反馈，建立了连轧张力理论体系；在厚控过程中，解决扰动的检测问题；在板形理论中，定义了对偶参数，确立了与厚控理论相似的板形理论体系。

关键词：连轧过程控制连轧张力厚度控制板形刚度轧机弹跳方程综合等储备负荷分配

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Rolling-element bearings in China: From ancient times to the 20th century

Lie SUN,Ang LI

《机械工程前沿（英文）》 2016年第11卷第1期页码 33-43 doi: 10.1007/s11465-016-0373-2

摘要：

The development of rolling-element bearings in China has spanned a long period. Based on several typical and important cases, the present article reconstructs the history of rolling-element bearings in China by dividing it into four stages according to the various characteristics of the bearings. The first stage represents the origin of rolling bearings in China, which remains controversial because of several suspected races and cages that were likely the components of bearings more than a millennium ago. At the second stage, a type of simple roller bearing was used for astronomical instruments not later than the 13th century based on clear philological and physical evidence. A similar bearing was also applied to an abridged armillary in the 17th century. Another type of spherical thrust bearings with rolling elements, which is a key component of a traditional Chinese windmill, could support a rotating shaft that moves rotationally and at an angle. At the third stage, the Chinese began studying and using the so-called European-style bearing since the 17th century. Moreover, over the last 100 years, the modern rolling bearing industry was gradually established in China, particularly because of the technology transfer from the Soviet Union in the 1950s. At the fourth stage, the Chinese government initiated the relatively rapid development of bearing technology. The government launched the “bearing movement” from the 1950s to the 1960s to establish the modern bearing industry and to promote rolling bearings as replacement for traditional sliding bearings. Furthermore, a number of large professional factories and institutions in China have continually introduced advanced technology and equipment. At present, these companies and institutions play a significant role in the international bearing industry.

关键词： bearing movement rolling-element bearing China early rolling bearings technology transfer

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simulation and analysis of periodically oscillating pressure characteristics of inviscid flow in a rolling

Yan GU, Yonglin JU

《能源前沿（英文）》 2012年第6卷第1期页码 21-28 doi: 10.1007/s11708-012-0173-2

摘要： Floating liquefied natural gas (LNG) plants are gaining increasing attention in offshore energy exploitation. The effects of the periodically oscillatory motion on the fluid flow in all processes on the offshore plant are very complicated and require detailed thermodynamic and hydrodynamic analyses. In this paper, numerical simulations are conducted by computational fluid dynamics (CFD) code combined with user defined function (UDF) in order to understand the periodically oscillating pressure characteristics of inviscid flow in the rolling pipe. The computational model of the circular pipe flow is established with the excitated rolling motion, at the excitated frequencies of 1–4 rad/s, and the excitated amplitudes of 3°–15°, respectively. The influences of flow velocities and excitated conditions on pressure characteristics, including mean pressure, frequency and amplitude are systematically investigated. It is found that the pressure fluctuation of the inviscid flow remains almost constant at different flow velocities. The amplitude of the pressure fluctuation increases with the increasing of the excitated amplitude, and decreases with the increasing of the excitated frequency. It is also found that the period of the pressure fluctuation varies with the excitated frequency. Furthermore, theoretical analyses of the flow in the rolling circular pipe are conducted and the results are found in qualitative agreement with the numerical simulations.

关键词： pressure fluctuation rolling floating production storage and offloading unit for liquefied natural gas (LNG-FPSO) offshore

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Chemisorption solid materials for hydrogen storage near ambient temperature: a review

Yiheng ZHANG, Shaofei WU, Liwei WANG, Xuefeng ZHANG

《能源前沿（英文）》 2023年第17卷第1期页码 72-101 doi: 10.1007/s11708-022-0835-7

摘要： Solid chemisorption technologies for hydrogen storage, especially high-efficiency hydrogen storage of fuel cells in near ambient temperature zone defined from −20 to 100°C, have a great application potential for realizing the global goal of carbon dioxide emission reduction and vision of carbon neutrality. However, there are several challenges to be solved at near ambient temperature, i.e., unclear hydrogen storage mechanism, low sorption capacity, poor sorption kinetics, and complicated synthetic procedures. In this review, the characteristics and modification methods of chemisorption hydrogen storage materials at near ambient temperature are discussed. The interaction between hydrogen and materials is analyzed, including the microscopic, thermodynamic, and mechanical properties. Based on the classification of hydrogen storage metals, the operation temperature zone and temperature shifting methods are discussed. A series of modification and reprocessing methods are summarized, including preparation, synthesis, simulation, and experimental analysis. Finally, perspectives on advanced solid chemisorption materials promising for efficient and scalable hydrogen storage systems are provided.

关键词： hydrogen storage capacity chemisorption near-ambient-temperature modification methods alloy hydrides

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Factors influencing near infrared spectroscopy analysis of agro-products: a review

Xiao XU, Lijuan XIE, Yibin YING

《农业科学与工程前沿（英文）》 2019年第6卷第2期页码 105-115 doi: 10.15302/J-FASE-2019255

摘要：

The near infrared (NIR) spectroscopy technique has wide applications in agriculture with the advantages of being nondestructive, sensitive, safe and rapid. However, there are still more than 40 error sources influencing the robustness and accuracy of its calibration and operation. Environmental, sample and instrument factors that influence the analysis are discussed in this review, including temperature, humidity and other factors that introduce uncertainty. Error sources from livestock products, fruit and vegetables, which are the most common objects in the field of NIR analysis, are also emphasized in the second part. In addition, studies utilizing different instruments, spectral pretreatments, variable selection methods, wavelength ranges, detection modes and calibration methods are tabulated to illustrate the complications they introduce and how they influence NIR analysis. It is suggested that large scale of data with abundant varieties can be used to build a more robust calibration model, in order to improve the robustness and accuracy of the NIR analytical model, and overcome problems caused by confining analysis to too many uniform samples.

关键词： agro-product error source influence factor near infrared spectroscopy

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Implementation of sinh method in integration space for boundary integrals with near singularity in potential

Guizhong XIE,Dehai ZHANG,Jianming ZHANG,Fannian MENG,Wenliao DU,Xiaoyu WEN

《机械工程前沿（英文）》 2016年第11卷第4期页码 412-422 doi: 10.1007/s11465-016-0396-8

摘要：

As a widely used numerical method, boundary element method (BEM) is efficient for computer aided engineering (CAE). However, boundary integrals with near singularity need to be calculated accurately and efficiently to implement BEM for CAE analysis on thin bodies successfully. In this paper, the distance in the denominator of the fundamental solution is first designed as an equivalent form using approximate expansion and the original sinh method can be revised into a new form considering the minimum distance and the approximate expansion. Second, the acquisition of the projection point by Newton-Raphson method is introduced. We acquire the nearest point between the source point and element edge by solving a cubic equation if the location of the projection point is outside the element, where boundary integrals with near singularity appear. Finally, the subtriangles of the local coordinate space are mapped into the integration space and the sinh method is applied in the integration space. The revised sinh method can be directly performed in the integration element. A verification test of our method is proposed. Results demonstrate that our method is effective for regularizing the boundary integrals with near singularity.

关键词： computer aided engineering (CAE) boundary element method (BEM) near singularity sinh method coordinate transformation integration space

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Review of the damage mechanism in wind turbine gearbox bearings under rolling contact fatigue

Yun-Shuai SU, Shu-Rong YU, Shu-Xin LI, Yan-Ni HE

《机械工程前沿（英文）》 2019年第14卷第4期页码 434-441 doi: 10.1007/s11465-018-0474-1

摘要： Wind turbine gearbox bearings fail with the service life is much shorter than the designed life. Gearbox bearings are subjected to rolling contact fatigue (RCF) and they are observed to fail due to axial cracking, surface flaking, and the formation of white etching areas (WEAs). The current study reviewed these three typical failure modes. The underlying dominant mechanisms were discussed with emphasis on the formation mechanism of WEAs. Although numerous studies have been carried out, the formation of WEAs remains unclear. The prevailing mechanism of the rubbing of crack faces that generates WEAs was questioned by the authors. WEAs were compared with adiabatic shear bands (ASBs) generated in the high strain rate deformation in terms of microstructural compositions, grain refinement, and formation mechanism. Results indicate that a number of similarities exist between them. However, substantial evidence is required to verify whether or not WEAs and ASBs are the same matters.

关键词： rolling contact fatigue (RCF) white etching area (WEA) white etching crack (WEC) adiabatic shear band (ASB)

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Modeling of oil near-infrared spectroscopy based on similarity and transfer learning algorithm

Yifei Wang, Kai Wang, Zhao Zhou, Wenli Du

《化学科学与工程前沿（英文）》 2019年第13卷第3期页码 599-607 doi: 10.1007/s11705-019-1807-2

摘要： Near-infrared spectroscopy mainly reflects the frequency-doubled and total-frequency absorption information of hydrogen-containing groups (O‒H, C‒H, N‒H, S‒H) in organic molecules for near-infrared lights with different wavelengths, so it is applicable to testing of most raw materials and products in the field of petrochemicals. However, the modeling process needs to collect a large number of laboratory analysis data. There are many oil sources in China, and oil properties change frequently. Modeling of each raw material is not only unfeasible but also will affect its engineering application efficiency. In order to achieve rapid modeling of near-infrared spectroscopy and based on historical data of different crude oils under different detection conditions, this paper discusses about the feasibility of the application of transfer learning algorithm and makes it possible that transfer learning can assist in rapid modeling using certain historical data under similar distributions under a small quantity of new data. In consideration of the requirement of transfer learning for certain similarity of different datasets, a transfer learning method based on local similarity feature selection is proposed. The simulation verification of spectral data of 13 crude oils measured by three different probe detection methods is performed. The effectiveness and application scope of the transfer modeling method under different similarity conditions are analyzed.

关键词： near-infrared spectroscopy transfer learning similarity modeling