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Optical design of rectangular illumination with freeform lenses for the application of LED road lighting

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Frontiers of Optoelectronics 2017年第4期10卷 353-362页

作者： Chunyun XU Haobo CHENG yunpeng feng China Aerospace Academy of Systems Science and Engineering Beijing 100048 China Joint Research Center for Optomechatronics Engineering School of Optoeleetronics Beijing Institute of Technology Beijing 100081 China Shenzhen Research Institute Beijing Institute of Technology Shenzhen 518057 China

We present a freeform lens for application to light-emitting diodes （LED） road lighting. We propose a simple source-target luminous intensity mapping method based on Snell＇s law and geometric-optics analysis. We calculated different contours of cross-sections to construct a freeform lens with a smooth surface. The computer simulation results show that the lighting performance of a single freeform lens is not sufficient for road lighting. For the road lamp simulation, we adopted an oval arrangement of freeform lenses on a printed circuit board. In addition, we performed tolerance analysis to determine the tolerance limits of manufacturing and installation errors. A road lamp at a height of 12 m can create rectangular illumination with an area of 40 m ~ 12 m, 69.7% uniformity, and average illuminance of 24.6 lux. This lighting performance can fully comply with the urban road lighting design standard.

关键词： light-emitting diodes (LED) nonimagingoptics freeform lens design rectangular illumination

基于渗流-应力-损伤耦合的岩溶地区基坑开挖稳定性

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大连海事大学学报 2024年第2期50卷 168-176页

作者：冯云鹏姜谙男许梦飞虢新平闵庆华大连海事大学道路与桥梁工程研究所辽宁大连116026 中建交通建设集团有限公司北京100142

针对岩溶地区基坑工程施工过程中渗流(H)-应力(M)-损伤(D)耦合导致的岩石失稳问题,建立基于Hoek-Brown强度准则的渗流-应力-损伤耦合模型和算法。首先,根据损伤理论引入损伤因子对H-B准则进行修正,给出应力场、渗流场的控制方程与渗透... 详细信息

针对岩溶地区基坑工程施工过程中渗流(H)-应力(M)-损伤(D)耦合导致的岩石失稳问题,建立基于Hoek-Brown强度准则的渗流-应力-损伤耦合模型和算法。首先,根据损伤理论引入损伤因子对H-B准则进行修正,给出应力场、渗流场的控制方程与渗透性演化方程,实现渗流-应力-损伤的完全耦合。然后,给出该模型的求解算法。与石灰岩三轴室内试验与模拟的计算结果对比表明,两者拟合较好,验证了模型的准确性。最后,将该模型用于大连地铁梭鱼湾南站基坑工程的开挖稳定性分析,分别计算了耦合和非耦合条件下地表沉降和地下连续墙变形,结果表明,考虑耦合的变形值明显大于非耦合的变形值,并且更贴近现场监测数值。同时,为确定围岩最小防突层厚度,分别计算防突层为2 m、4 m、6 m、8 m时的损伤区分布特征,这对实际施工时的风险预测具有一定的意义。

关键词：岩溶地区基坑开挖稳定性渗流-应力-损伤耦合模型

Numerical Investigation of the Effects of Rate-Shaped Main Injection on Combustion and Emission in an OPOC Two-Stroke Diesel Engine

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Journal of Beijing Institute of Technology 2019年第2期28卷 226-233页

作者： Lei Zhang Tiexiong Su yunpeng feng Fukang Ma Yangang Zhang Jun Wang College of Mechatronic Engineering North University of ChinaTaiyuan 030051China School of Energy and Power Engineering North University of ChinaTaiyuan 030051China Beijing Special Vehicle Institute Beijing 100072China

The effects of various split injection strategies on the opposed-piston opposed-cylinder(OPOC)diesel engine combustion and emission characteristics have been studied numerically using AVL-Fire CFD *** five rate-shaped main injections were used in split injection *** results show that ignition delay from a rectangular injection rate is the *** pressure of the trapezoid injection rate is the *** the NOx emission of the rectangular injection rate is the ***,the soot emission of the trapezoid injection rate is the least among the five injection rates.

关键词： opposed-piston opposed-cylinder(OPOC)diesel engine split injection rated-shape main injection:numerical simulation combustion emissions

Smart Gait:A Gait Optimization Framework for Hexapod Robots

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Chinese Journal of Mechanical Engineering 2024年第1期37卷 146-159页

作者： yunpeng Yin feng Gao Qiao Sun Yue Zhao Yuguang Xiao State Key Laboratory of Mechanical System and Vibration School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai 200240China Lenovo Corporation ShanghaiChina AI Institute School of Electronic Information and Electrical EngineeringShanghai Jiao Tong UniversityShanghai 200240China

The current gait planning for legged robots is mostly based on human presets,which cannot match the flexible characteristics of natural *** paper proposes a gait optimization framework for hexapod robots called Smart *** Gait contains three modules:swing leg trajectory optimization,gait period&duty optimization,and gait sequence *** full dynamics of a single leg,and the centroid dynamics of the overall robot are considered in the respective *** Smart Gait not only helps the robot to decrease the energy consumption when in locomotion,mostly,it enables the hexapod robot to determine its gait pattern transitions based on its current state,instead of repeating the formalistic clock-set step *** Smart Gait framework allows the hexapod robot to behave nimbly as a living animal when in 3D movements for the first *** Smart Gait framework combines offline and online optimizations without any fussy data-driven training procedures,and it can run efficiently on board in real-time after *** experiments are carried out on the hexapod robot *** results show that the energy consumption is reduced by 15.9%when in *** gait patterns can be generated spontaneously both in regular and challenge environments,and when facing external interferences.

关键词： Gait optimization Swing trajectory optimization Legged robot Hexapod robot

Magnetorheological finishing of optical surface combined with symmetrical tool function

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Frontiers of Optoelectronics 2010年第4期3卷 408-412页

作者： Haobo CHENG yunpeng feng Tan WANG Zhichao DONG School of Optoelectronics Beijing Institute of Technology Department of Mechanical and Automation Engineering The Chinese University of Hong Kong

This research is aimed at the development of computer-aided polishing technology for optical surfaces using magnetorheological(MR) fluid as medium. The mechanism of a dual-axis polishing wheel and the mathematical model combined with a symmetrical tool function are demonstrated. The effects of speed, gap, time and geometric parameters of the tool have been experimentally evaluated by polishing a parabolic BK7 mirror in120 mm diameter. The surface topography presented an obvious amelioration, and the shape accuracy decreased to 0.067λ from 0.519λ(λ = 632.8 nm, RMS) after 75 min finishing.

关键词： magnetorheological finishing (MRF) material removal symmetrical tool function

Method of optical interference testing error separation

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Frontiers of Optoelectronics 2010年第04期3卷 382-386页

作者： yunpeng feng Xiaoyan QIAO Haobo CHENG Yongfu WEN Ya GAO Huijing ZHANG School of Optoelectronics Beijing Institute of Technology School of Electrical and Electronic Engineering North China Electric Power University

During the testing of aspherical mirrors through the null compensation method, structural parameters observe changes which affect the test results of interference pattern. Several errors are induced due to the maladjustment among compensator, interferometer and the mirror under test. It is important for optical manufacturing,testing and the actual alignment process to distinguish between the aberrations arising from both surface errors and maladjustment of the null compensation testing system. The purpose of this paper is to obtain the real aspheric surface errors during the optical polishing process. In this work, we have established an error separation model to the least square method to separate the errors caused by the maladjustment of the testing system from the test results. Finally, the analysis and simulation results show that high precision figure errors can be obtained by separating the maladjustment errors.

关键词： aspheric mirror interferometric testing adjustment error maladjustment error separation

Investigation of electrorheological fluid for optical finishing

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Frontiers of Optoelectronics 2011年第2期4卷 213-216页

作者： Hui LI Haobo CHENG yunpeng feng H.Y.TAM Yongfu WEN School of Optoelectronics Beijing Institute of Technology Department of Manufacturing Engineering and Engineering Management City University of Hong Kong

Electrorheological（ER） finishing is a promising technique for polishing optical mirrors lenses. Silicone oil-based ER finishing fluid with ceria particles as abrasive was developed, whose dispersed phase was alumina,titanium dioxide, silica, and starch, respectively. Experiments were performed in detail under the voltage of 3000V, after 25 min of polishing a K9 glass. By using the ER fluid developed in this paper, with 47.62% starch, 47.62%silicone oil, and 4.76% ceria, the surface roughness of the K9 glass was reduced from 8.46 nm Rato 3.45 nm Ra. The result verifies the validity of the developed ER fluid.

关键词： electrorheological fluid polishing slurry shear stress

Carbon preservation in sedimentary deposits: Beyond mineral protection

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The Innovation 2024年第2期5卷 5-6页

作者： yunpeng Zhao Juan Jia Chengzhu Liu Xiaojuan feng State Key Laboratory of Vegetation and Environmental Change Institute of BotanyChinese Academy of SciencesBeijing 100093China China National Botanical Garden Beijing 100093China College of Resources and Environment University of Chinese Academy of SciencesBeijing 100049China

The deposition and preservation of organic carbon(OC)in sedimentary environments(including soils and sediments)play major roles in mediating the global carbon *** than 90%of OC burial in the ocean occurs in continental margin sediments,which contributes to the evolution of the Earth’s atmosphere,such as oxygen content,over geological timescales.1 However,how OC escapes mineralization and persists in such sedimentary deposits has long been a *** protection through physicochemical associations of organic matter with minerals and cations is considered to be one of the primary mechanisms contributing to the environmental persistence of sedimentary OC.

关键词： sedimentary mineralization environments

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中国电影中的南京大屠杀话语与创伤焦虑

北京电影学院学报 2019年第12期 34-40页

作者：黎风丰云鹏四川大学文学与新闻学院

20世纪80年代以来,中国电影中的南京大屠杀话语不断在表意实践与民众的记忆情感之间、创伤记忆的"国族"叙事与"人性"叙事之间起伏。同时,这些张力也对电影中受难者与幸存者的发声空间存在重要影响。这种状况既表明电影创作者们试图突破... 详细信息

20世纪80年代以来,中国电影中的南京大屠杀话语不断在表意实践与民众的记忆情感之间、创伤记忆的"国族"叙事与"人性"叙事之间起伏。同时,这些张力也对电影中受难者与幸存者的发声空间存在重要影响。这种状况既表明电影创作者们试图突破创伤叙事的定型化、模式化路径,为创伤记忆提供不同层面的理解与阐述,但也意味着这一沉重的历史记忆在通过电影文化实践进入公共领域时所面临的困境与创伤焦虑。

关键词：南京大屠杀电影创伤焦虑创伤叙事记忆的伦理