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APPLICATION OF INTEGRATION ALGORITHEMS FOR ELASTO-PLASTICITY CONSTITUTIVE MODEL FOR ANISOTROPIC SHEET MATERIALS

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Chinese Journal of Mechanical Engineering 2006年第4期19卷 554-557页

作者： LIU Yanfang SHI Fazhong xu xiangyang Department of Automotive Engineering Beihang University Beijing 100083 China School of Mechanical Engineering and Automation Beihang University Beijing 100083 China Department of Automotive Engineering Beihang University Beijing 100083 Chine

Two algorithms of computing stress increment by using the elasto-plasticity constitutive model are firstly formulated, which are the Euler integration method and the radial return method. Hill＇48 anisotropic yield criterion is used. The Euler integration method can not obtain more accurate computation of the stress increment as the radial return method unless enough subintervals are taken,by which the Euler integration method will take excessive computing time. Without docreasing any accuracy, the radial return method can save much time. Finally, a square cup deep drawing from NUMISHEET＇93 benchmarks is simulated with a self-developed code SheetForrn in order to investigate the accuracy and efficiency of the radial return method.

关键词： Finite element method Sheet metal forming Anisotropy Elasto-plasticityIntegration algorithm

Vibration performance discrete optimization of a gear system featuring confluence transmission used in marine gearbox

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International Journal of Modeling, Simulation, and Scientific Computing 2017年第1期8卷 165-178页

作者： Zeyin He Tao Deng xiangyang xu School of Mechantronics and Vehicle EngineeringChongqing Jiaotong University Chongqing 400074P.R.China State Key Laboratory of Mechanical Transmission Chongqing University Chongqing 400030P.R.China

A dynamic model of gear transmission system which includes time-varying meshing stiffness,meshing damp and transmission error is ***,the analytical solution of the vibration response would be obtained by solving the dynamic model based on the harmonic balance *** on this basis,a dynamic performance discrete optimization model of transmission sub-system would be constructed,which sets objective function up from vibration acceleration and the total mass of transmission sub-system,treats the module,number of teeth and helix angle as design variables,and takes gear strength and assembly relationship as ***,the optimal solution of design variables could be obtained through the multivariable mixed discrete optimization program which based on the branch-bound *** results show that the vibration acceleration and the total mass of transmission sub-system reduce by 34.6%and 6.8%,respectively.

关键词： Gear transmission system dynamic model vibration performance discrete optimization

The best detection conditions for pulsars in the Galactic disk

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Science China(Physics,Mechanics & Astronomy) 2011年第3期54卷 552-557页

作者： xu xiangyang WANG Chen HAN JinLin HU Lin College of Science Guizhou University Guiyang 550025 China National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China

Radio detection of pulsars in the Galactic disk is strongly affected by the dispersion and scattering effect of the interstellar medium and the Galactic background radio emission. In order to know the best conditions for discovery of pulsars, we select and simulate pulsar samples in the Galactic disk, and calculate the detection probability with various observation conditions (such as observational frequency, telescope aperture, receiver bandwidth and integration time). We have found that the detection fraction increases with the telescope aperture, receiver bandwidth and integration time. To detect pulsars in the nearer half of the Galactic disk, the observation frequency should be in the range of 1-2 GHz, while for pulsars in the farther half of the disk, the frequency should be in the range of 3.5-4.5 GHz. Due to the strong influence of scattering, the short period pulsars are hard to be detected, especially for pulsars in the farther half of the Galactic disk.

关键词： pulsars neutron stars radio telescopes scattering of electromagnetic radiation in plasmas

Study on the Modification of Nanodiamond with DN-IO

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Journal of Materials Science & Technology 2007年第5期23卷 599-603页

作者： Yongwei ZHU Feng xu Jianliang SHEN Baichun WANG xiangyang xu Jianbin SHAO Jiangsu Key Laboratory of Precision and Micro-manufacturing Technology Nanjing University of Aeronautics and Astronautics Jiangsu 210016 China R ＆： D Centre Changsha Research Institute of Mining and Metallurgy Hunan 410012 China

Fourier transform infrared spectroscopy （FT-IR） and ζ-potential were introduced to study the effect of different modification parameters on the surface properties of nanodiamond （ND）. Results showed that under stirring grinding grinding conditions, ND hard aggregates were smashed and some active spots on them reacted with surfactant molecules, which led to the increase in its ζ-potential and stability. Different models of surface modification were also given in this study.

关键词： Surface modification FT-IR q-potential Nanodiamond

Development of a Low-cost Hardware-in-the-loop Simulation System as a Test Bench for Anti-lock Braking System

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Chinese Journal of Mechanical Engineering 2011年第1期24卷 98-104页

作者： ZHANG Wei DING Nenggen CHEN Moran YU Guizhen xu xiangyang School of Transportation Science and Engineering Beihang University Beijing100191 China China Academy of Transportation Sciences of Ministry of Communications Beo＇ing 100029 China

Nowadays validation of anti-lock braking systems（ABS） relies mainly on a large amount of road *** alternative means with higher efficiency is employing the hardware-in-the-loop simulation（HILS） system to substitute part of road tests for designing,testing,and tuning electronic control units（ECUs） of *** HILS systems for ABS use expensive digital signal processor hardware and special purpose software,and some fail-safe functions with regard to wheel speeds cannot be evaluated since artificial wheel speed signals are usually *** this paper,a low-cost ABS HILS test bench is developed and used for validating the anti-lock braking performance and tuning control parameters of ABS *** important merit of the proposed test bench is that it can comprehensively evaluate the fail-safe functions with regard to wheel speed signals since real tone rings and sensors are integrated in the bench.A 5-DOF vehicle model with consideration of longitudinal load transfer is used to calculate tire forces,wheel speeds and vehicle *** of the four real-time wheel speed signal generators consists of a servo motor plus a ring gear,which has sufficient dynamic response ability to emulate the rapid changes of the wheel speeds under strict braking conditions of very slippery *** simulation of braking tests under different road adhesion coefficients using the HILS test bench is run,and results show that it can evaluate the anti-lock braking performance of ABS and partly the fail-safe *** HILS system can also be used in such applications as durability test,benchmarking and comparison between different *** test bench developed not only has a relatively low cost,but also can be used to validate the wheel speed-related ECU design and all its fail-safe functions,and a rapid testing and proving platform with a high efficiency for research and development of the automotive ABS is therefore provided.

关键词： hardware-in-the-loop simulation(HILS) anti-lock braking systems(ABS) electronic control units(ECU)

Preface for Special Issue on Electric Drive System for Vehicles

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Automotive Innovation 2021年第1期4卷 1-2页

作者： xiangyang xu Guangyu Tian Hui Liu School of Transportation and Science Engineering Beihang UniversityBeijing 102206China Ningbo Institute of Technology Beihang UniversityNingbo 315832China School of Vehicle and Mobility Tsinghua UniversityBeijing 100084China Department of Vehicle Engineering Beijing Institute of TechnologyBeijing 100081China

What is the biggest challenge when vehicles move towards electrification?Electric drive system responds positively to this question,which plays a key role in terms of energy sav-ing and carbon emission ***,it is required to provide excellent driving performance,therefore becoming a hot topic in the automotive *** Automotive Innova-tion proposed this special issue.

关键词： reduction. driving becoming

Security research with Square attack to a variant Camellia cipher

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Frontiers of Electrical and Electronic Engineering in China 2010年第4期5卷 482-487页

作者： xiangyang xu Guangsheng ZHANG Department of Computer Science and Technology Changsha UniversityChangsha 410003China School of Computer National University of Defense TechnologyChangsha 410073China

This paper investigates the relation between the choice of S-boxes and Square attack.A variant Camellia,which uses only a single S-box instead of four,is *** security of the variant Camellia against Square attack is studied in *** shows that it needs only 28 chosen plaintexts to recover a byte of the 6th round-key of variant Camellias,while the original Camellia needs either 28 chosen plaintexts to recover a byte of the 6th round-key and a byte of some constant or 216 chosen plaintexts to recover a byte of the 6th ***,Square attacks on other round-reduced variant Camellia are proposed,and the time complexity of 11-round attack is reduced from 2^(250)to 2^(225.5).The weaker variant Camellia indicates that the choice of S-box and the order of different S-boxes have influence on Square attack.

关键词： block cipher Camellia Square attack

Progress in Automotive Transmission Technology

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Automotive Innovation 2018年第3期1卷 187-210页

作者： xiangyang xu Peng Dong Yanfang Liu Hui Zhang School of Transportation and Science Engineering Beihang UniversityBeijing 100191China Beijing Key Laboratory for High-efficient Power Transmission and System Control of New Energy Resource Vehicle Beihang UniversityBeijing 100191China

Much progress has been made in the development of automotive transmissions over the past 20 years,e.g.,an increased speed number,expanded ratio spread and improved efficiency and shift *** transmissions are moving toward electrification in response to stringent legislation on emissions and the pressing demand for better fuel *** paper reviews progress in automotive transmission *** by computer-aided programs,new transmission schemes are constantly being *** therefore first introduce the synthesis of the transmission scheme and parameter *** then discuss the progress in the transmission technology of a conventional internal combustion engine vehicle in terms of new layouts;improved efficiency;noise,vibration and harshness technology;and the shifting strategy and control *** the major development trend,transmission electrification is subsequently discussed;this discussion includes the configuration design,energy management strategy,hybrid mode shifting control,single-speed and multi-speed electric vehicle transmission and distributed electric ***,a summary and outlook are presented for conventional automotive transmissions,hybrid transmissions and electric vehicle transmissions.

关键词： Automotive transmission Hybrid transmission Electric vehicle transmission Distributed electric drive Scheme synthesis Electrification

Morphological characteristics of tree crowns of Cunninghamia lanceolata var. Luotian

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Journal of Forestry Research 2020年第3期31卷 837-856页

作者： Yezhou xu Chaoqun Du Guowei Huang Zhenfang Li xiangyang xu Jingjin Zheng Chu Wu Hubei Academy of Forestry Wuhan 430075People’s Republic of China Forestry Bureau of Luotian County Huanggang 438000People’s Republic of China College of Horticulture and Gardening Yangtze UniversityJingzhou 434025HubeiPeople’s Republic of China

The structural characteristics of the tree crowns of Cunninghamia lanceolata var. Luotian(herein, Luotian), a natural variety of C. lanceolata(Chinese-fir, herein Lanceolata) in China, were analyzed using trunk and branch measurements and biomass determinations. Samples from two typical cultivated varietal populations were collected, including twenty-six 15–23-year-old trees of Luotian from a plantation, and nine 16–23-year-old trees of Lanceolata. Our results show that Luotian and Lanceolata samples differed significantly in crown structure, morphological indices, and biomass:(1) the oldest live branches on Luotian trees were 5–6 years old and 8–11 years old on Lanceolata. The ages of the live branches were not affected by the ages of the Luotian trees, while live branch ages increased with ages of Lanceolata trees;(2) the maximumbranching order of Luotian was level two. Compared to Lanceolata, the average number of first-order lateral branches(i.e., branches emerging from the trunk) and the number of first-order lateral branch whorls per sample tree were 12.9% and 32.2% lower, respectively, in ***, the average number of branches within a single whorl was 21.8% greater in Luotian;the average number of branch whorls at crown height was 51.1% greater. Thus,the Luotian variety has thicker branches;(3) the average lateral branch angles in Luotian and Lanceolata sample trees were 105.2° and 61.4°, respectively. The branch angles in 53.0% of lateral branches on Luotian ranged from105° to 135°, but 30° to 90° in 96% of the lateral branches on Lanceolata. Within the same crown layer, the average branch angle was 1.6–2.2 times greater in Luotian, and the angle was directly proportional to crown thickness;(4) the average base diameter and branch length on Luotian were1.3 cm and 75.8 cm, respectively, and 1.6 cm and112.2 cm for Lanceolata. For individual trees, branch growth differed significantly(p < 0.01) between Luotian and Lanceolata. However, the lateral bran

关键词： Cunninghamia lanceolata var Luotian Cunninghamia lanceolata Tree crown Morphological characteristics Variation