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Shadow obstacle model for realistic corner-turning behavior in crowd simulation

Gao-qi HE,Yi JIN,Qi CHEN,Zhen LIU,Wen-hui YUE,Xing-jian LU

《信息与电子工程前沿（英文）》 2016年第17卷第3期页码 200-211 doi: 10.1631/FITEE.1500253

摘要： This paper describes a novel model known as the shadow obstacle model to generate a realistic corner-turning behavior in crowd simulation. The motivation for this model comes from the observation that people tend to choose a safer route rather than a shorter one when turning a corner. To calculate a safer route, an optimization method is proposed to generate the corner-turning rule that maximizes the viewing range for the agents. By combining psychological and physical forces together, a full crowd simulation framework is established to provide a more realistic crowd simulation. We demonstrate that our model produces a more realistic corner-turning behavior by comparison with real data obtained from the experiments. Finally, we perform parameter analysis to show the believability of our model through a series of experiments.

关键词： Corner-turning behavior Crowd simulation Safety awareness Rule-based model

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Detection for transverse corner cracks of steel plates’ surface using wavelet

Qiong ZHOU, Qi AN

《机械工程前沿（英文）》 2009年第4卷第2期页码 224-227 doi: 10.1007/s11465-009-0017-x

摘要： An algorithm is presented for detecting transverse corner cracks at a steel plate surface using wavelet transform. According to characteristics of transverse corner crack images, the wavelet transform is used for the multi-scale analysis of detecting the image edges and disintegrating the image into four directions at the same time. The proper threshold value is chosen to segment the image into vertical components to obtain the final detection result. The experiment shows that transverse corner cracks of steel plates can be more effectively extracted by the proposed method than the other two common methods.

关键词： transverse corner cracks defect detection multi-scales wavelet analysis

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Renewable synthetic fuel: turning carbon dioxide back into fuel

《能源前沿（英文）》 2022年第16卷第2期页码 145-149 doi: 10.1007/s11708-022-0828-6

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P60钢轨鱼鳞伤萌生寿命

石嵘,范志毅,何越磊

《中国工程科学》 2008年第10卷第8期页码 65-68

摘要：

上海轨道交通1号线锦江乐园至莘庄路段P60钢轨使用至今已出现不同程度伤损。曲线路段的部分钢轨外轨内侧出现鱼鳞伤，严重的鱼鳞伤甚至向下发展导致核伤。鱼鳞伤在疲劳裂纹的初期发展缓慢，随着疲劳荷载次数增加，裂纹深度扩展速率dh/dN发生转折。定义裂纹深度扩展速率发生转折时对应的疲劳荷载的次数为鱼鳞伤萌生寿命。

关键词：钢轨鱼鳞伤疲劳裂纹裂纹深度扩展速率萌生寿命

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墙角火灾环境下钢构件温度分布及响应行为的实验研究

陈长坤,姚斌,杨昀,蔡昕,张和平,万玉田

《中国工程科学》 2005年第7卷第9期页码 70-75

摘要：

利用ISO9705标准火灾实验系统，模拟墙角火灾环境，以薄壁方管钢梁为研究对象，对钢构件在热、力耦合作用下的行为进行实验研究。对火灾的热释放速率与室内温度场，钢构件及其表面气体的温度、构件在火灾作用下的挠度进行测量，分析真实火灾下钢构件温升及温度分布的特点与火灾发展对构件挠度的影响。研究结果表明钢构件在长向上存在着很大的温差，而构件的挠度变化也并不对称，这说明以往研究中往往假设钢构件在长向上温度一致并不恰当，这种非均匀温度场对构件的行为有着重要影响，它使得构件高温区部分更易发生局部屈服而失效，在相同规模的火灾环境下，与均匀温度场相比，这种墙角火灾所导致的非均匀温度场更不利于钢构件的安全。

关键词： ISO标准火灾实验系统钢构件墙角火温度分布

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Prediction of cutting force in turning of UD-GFRP using mathematical model and simulated annealing

Meenu GUPTA, Surinder Kumar GILL

《机械工程前沿（英文）》 2012年第7卷第4期页码 417-426 doi: 10.1007/s11465-012-0343-2

摘要：

Glass fiber reinforced plastics (GFRPs) composite is considered to be an alternative to heavy exortic materials. According to the need for accurate machining of composites has increased enormously. During machining, the obtaining cutting force is an important aspect. The present investigation deals with the study and development of a cutting force prediction model for the machining of unidirectional glass fiber reinforced plastics (UD-GFRP) composite using regression modeling and optimization by simulated annealing. The process parameters considered include cutting speed, feed rate and depth of cut. The predicted values radial cutting force model is compared with the experimental values. The results of prediction are quite close with the experimental values. The influences of different parameters in machining of UD-GFRP composite have been analyzed.

关键词： UD-GFRP ANOVA radial cutting force PCD tool Taguchi method regression analysis simulated annealing multi objective techniques

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室内装饰材料的标准房间/墙角火实验研究进展

杨昀,张和平,刘激扬

《中国工程科学》 2003年第5卷第4期页码 55-60

摘要：

标准房间/墙角火实验是一种全尺度火灾实验研究方法，主要用来研究室内装饰材料的火灾特性。介绍了ISO 9705房间/墙角火实验方法的原理和实验装置，以及国内外利用该方法对装饰材料火灾特性进行研究的进展情况，包括对材料热释放速率、烟气产生和室内火蔓延方面的研究。分析了其研究成果在室内装饰材料的分类及火灾危险性评估中的实际应用情况，并结合作者目前的工作对未来的研究内容做了一些展望。

关键词：装饰材料全尺度 ISO 9705 房间/墙角火实验

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Application of high-turning bowed compressor stator to redesign of highly loaded fan stage

LI Shaobin, SU Jiexian, WANG Zhongqi

《能源前沿（英文）》 2008年第2卷第4期页码 534-540 doi: 10.1007/s11708-008-0066-6

摘要： A redesign of a highly loaded fan stage by using high-turning bowed compressor stator was conducted. The original tandem stator was replaced by the highly loaded bowed stator which was applicable to highly subsonic flow conditions. 3D contouring technique and local modification of blade were applied to the design of the bowed blade in order to improve the aerodynamic performance and the matching of the rotor and stator blade rows. Performance curves at different rotating speeds and performances at different operating points for both the original fan stage and redesigned fan stage were obtained by numerical simulations. The results show that the highly loaded bowed stator can be used not only to improve the structure and the aerodynamic performances at various operating points of the compressor stage but also to provide high performances at off-design conditions. It is believed that the highly loaded bowed stator can advance the design of high-performance compressor.

关键词： off-design different numerical contouring technique high-performance compressor

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Research on the dynamic mechanical characteristics and turning tool life under the conditions of excessivelyheavy-duty turning

Genghuang HE, Xianli LIU, Fugang YAN

《机械工程前沿（英文）》 2012年第7卷第3期页码 329-334 doi: 10.1007/s11465-012-0303-x

摘要：

The dynamic mechanical characteristics of excessively heavy-duty cutting were analyzed based on the cutting experiments with 2.25Cr-1Mo-0.25V steel used in hydrogenated cylindrical shells. By investigating the influence of dynamic mechanical characteristics on the tools’ failure in limited heavy-duty cutting processes, the model of dynamic shearing force in the cutting area was established. However, the experimental results showed that the dynamic shear flow stress in the cutting area greatly influenced the tools’ fatigue. The heavy-duty cutting tool was damaged in the form of a shearing fracture. Through a comprehensive analysis of the theory, the critical condition of the tools’ fracture under extreme loading was established.

关键词： extreme loading cutting shear flow stress dynamic cutting force fatigue fracture

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Effect of magneto rheological damper on tool vibration during hard turning

P. Sam PAUL, A. S. VARADARAJAN

《机械工程前沿（英文）》 2012年第7卷第4期页码 410-416 doi: 10.1007/s11465-012-0341-4

摘要：

Recently, the concept of hard turning has gained considerable attention in metal cutting as it can apparently replace the traditional process cycle of turning, heat treating, and finish grinding for assembly of hard wear resistant steel parts. The present investigation aims at developing a magneto rheological (MR) fluid damper for suppressing tool vibration and promoting better cutting performance during hard turning. The magneto rheological Fluid acts as a viscoelastic spring with non-linear vibration characteristics that are controlled by the composition of the magneto rheological fluid, the shape of the plunger and the electric parameters of the magnetizing field. Cutting experiments were conducted to arrive at a set of electrical, compositional and shape parameters that can suppress tool vibration and promote better cutting performance during turning of AISI 4340 steel of 46 HRC with minimal fluid application using hard metal insert with sculptured rake face. It was observed that the use of MR fluid damper reduces tool vibration and improves the cutting performance effectively. Also commercialization of this idea holds promise to the metal cutting industry.

关键词： tool vibration magneto rheological damper hard turning surface finish tool wear

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Sub-nanometer finishing of polycrystalline tin by inductively coupled plasma-assisted cutting

《机械工程前沿（英文）》 2023年第18卷第3期 doi: 10.1007/s11465-023-0751-5

摘要： Polycrystalline tin is an ideal excitation material for extreme ultraviolet light sources. However, the existence of grain boundary (GB) limits the surface roughness of polycrystalline tin after single-point diamond turning (SPDT). In this work, a novel method termed inductively coupled plasma (ICP)-assisted cutting was developed for the sub-nanometer finishing of polycrystalline tin. The relationship between ICP power, processing time, and modification depth was established by thermodynamic simulation, and the fitted heat transfer coefficient of polycrystalline tin was 540 W/(m²·K). The effects of large-thermal-gradient ICP treatment on the microstructure of polycrystalline tin were studied. After 0.9 kW ICP processing for 3.0 s, corresponding to the temperature gradient of 0.30 K/µm, the grain size of polycrystalline tin was expanded from a size of approximately 20–80 μm to a millimeter scale. The Taguchi method was used to investigate the effects of rotational speed, depth of cut, and feed rate on SPDT. Experiments conducted based on the ICP system indicated that the plasma-assisted cutting method promoted the reduction of the influence of GB steps on the finishing of polycrystalline tin, thereby achieving a surface finish from 8.53 to 0.80 nm in Sa. The results of residual stress release demonstrated that the residual stress of plasma-assisted turning processing after 504 h stress release was 10.7 MPa, while that of the turning process without the ICP treatment was 41.6 MPa.

关键词： plasma-assisted cutting polycrystalline tin single-point diamond turning surface roughness

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Nanoparticle-enhanced coolants in machining: mechanism, application, and prospects

《机械工程前沿（英文）》 2023年第18卷第4期 doi: 10.1007/s11465-023-0769-8

摘要： Nanoparticle-enhanced coolants (NPECs) are increasingly used in minimum quantity lubrication (MQL) machining as a green lubricant to replace conventional cutting fluids to meet the urgent need for carbon emissions and achieve sustainable manufacturing. However, the thermophysical properties of NPEC during processing remain unclear, making it difficult to provide precise guidance and selection principles for industrial applications. Therefore, this paper reviews the action mechanism, processing properties, and future development directions of NPEC. First, the laws of influence of nano-enhanced phases and base fluids on the processing performance are revealed, and the dispersion stabilization mechanism of NPEC in the preparation process is elaborated. Then, the unique molecular structure and physical properties of NPECs are combined to elucidate their unique mechanisms of heat transfer, penetration, and anti-friction effects. Furthermore, the effect of NPECs is investigated on the basis of their excellent lubricating and cooling properties by comprehensively and quantitatively evaluating the material removal characteristics during machining in turning, milling, and grinding applications. Results showed that turning of Ti‒6Al‒4V with multi-walled carbon nanotube NPECs with a volume fraction of 0.2% resulted in a 34% reduction in tool wear, an average decrease in cutting force of 28%, and a 7% decrease in surface roughness Ra, compared with the conventional flood process. Finally, research gaps and future directions for further applications of NPECs in the industry are presented.

关键词： nanoparticle-enhanced coolant minimum quantity lubrication biolubricant thermophysical properties turning milling grinding

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Study on Big Data-based Behavior Modification in Metro Construction

Lie-yun Ding,Sheng-yu Guo

《工程管理前沿（英文）》 2015年第2卷第2期页码 131-136 doi: 10.15302/J-FEM-2015037

摘要： With the rapid development of metro construction in China, construction accidents frequently happen, which are significantly attributable to workers’ unsafe behavior. Behavior-based safety (BBS) is an effective method to modify workers’ unsafe behavior. This paper introduces the study on big data-based metro construction behavior modification, aiming to solve the problem of current research without consideration of workers’ personal characters. First, the behavior modification pushing mechanism based on content-based personalized recommendation is studied. Secondly, the development of behavior modification system of metro construction (BMSMC) is introduced. Thirdly, BMSMC practical applications using the unsafe behavior rate, as a measuring indicator is implemented. Observations at one metro construction site in Wuhan indicate that the unsafe behavior rate of modified scaffolders at this work place decreased by 69.3%. At the same time, as of unmodified scaffolders at another work place for comparison, the unsafe behavior rate decreased by 56.9%, which validates the effectiveness of this system.

关键词： big data unsafe behavior behavior modification behavior-based safety (BBS) unsafe behavior rate

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Flow behavior of non-spherical particle flowing in hopper

He TAO,Wenqi ZHONG,Baosheng JIN

《能源前沿（英文）》 2014年第8卷第3期页码 315-321 doi: 10.1007/s11708-014-0331-9

摘要： Ellipsoidal particles flowing in the hopper were simulated by using the discrete element method (DEM), and described by the multi-element method. The contact detection algorithm and equations for ellipsoidal particle motion in hopper were developed. And the simulation results were confirmed by experiment. Additionally, the mass flow rate, pressure distribution and velocity distribution of two kinds of particles were examined. The results show that the mass flow rate of ellipsoidal particles is smaller than that of spherical particles. There is a maximum value of pressure drop at the top of the junction. Besides, the pressure drop decreases with the discharging time increasing. The velocity of spherical particle is larger than that of ellipsoidal.

关键词： discrete element method ellipsoidal particle flow behavior hopper

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A simplified method for investigating the bending behavior of piles supporting embankments on soft ground

《结构与土木工程前沿（英文）》页码 1021-1032 doi: 10.1007/s11709-023-0952-3

摘要： In recent years, concrete and reinforced concrete piles have been widely used to stabilize soft ground under embankments. Previous research has shown that bending failure, particularly during rapid filling on soft ground, is the critical failure mode for pile-supported embankments. Here, we propose an efficient two-stage method that combines a test-verified soil deformation mechanism and Poulos’ solution for pile–soil interaction to investigate the bending behavior of piles supporting embankments on soft ground. The results reveal that there are three possible bending failure scenarios for such piles: at the interface between the soft and firm ground layers, at mid-depths of the fan zone, and at the boundary of the soil deformation mechanism. The location of the bending failure depends on the position and relative stiffness of the given pile. Furthermore, the effect of embedding a pile into a firm ground layer on the bending behavior was investigated. When the embedded length of a pile exceeded a critical value, the bending moment at the interface between the soft and firm ground layers reached a limiting value. In addition, floating piles that are not embedded exhibit an overturning pattern of movement in the soft ground layer, and a potential failure is located in the upper part of these piles.

关键词： bending behavior pile embankment soil−structure interaction failure mode