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基于分级缓存加速的高可靠高速星载固存设计 预览
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作者 李欣 禹霁阳 +2 位作者 牛跃华 李宗凌 汪路元 《计算机测量与控制》 2019年第10期186-191,共6页
星上模块在模式切换过程会因为星载固态存储器启动过程缓慢而导致无法快速访问固存;分级缓存系统设计采用片内缓存结合小容量非易失存储器(MRAM)的硬件架构,通过在MRAM中存储文件对象头索引以及Nand Flash块元数据区索引等流程优化来加... 星上模块在模式切换过程会因为星载固态存储器启动过程缓慢而导致无法快速访问固存;分级缓存系统设计采用片内缓存结合小容量非易失存储器(MRAM)的硬件架构,通过在MRAM中存储文件对象头索引以及Nand Flash块元数据区索引等流程优化来加速文件系统启动操作;该设计通过数据建模和仿真实验来分析性能,并在硬件板卡上进行算法实现和测试验证,以对象为索引的启动方式耗时3.12ms,以块元数据区为依据的启动方式耗时143.47ms;对比传统设计架构下的耗时170.35s的启动操作,基于分级缓存加速的系统具有高可靠性同时大大缩短了固存启动时间;其系统性能提升为卫星在轨管控优化提供技术基础。 展开更多
关键词 高可靠 高速 分级缓存 星上数据管理系统
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Deformation characteristics and safety assessment of a high-speed railway induced by undercutting metro tunnel excavation 预览
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作者 Wangping Qian Taiyue Qi +2 位作者 Yunjian Zhao Yizhou Le Haiyang Yi 《岩石力学与岩土工程学报:英文版》 CSCD 2019年第1期88-98,共11页
Stratum deformation(settlement)is a challenging issue in tunnel engineering,especially when construction of metro tunnels has to undercut high-speed railway.For this purpose,we used the FLAC3D software to analyze the ... Stratum deformation(settlement)is a challenging issue in tunnel engineering,especially when construction of metro tunnels has to undercut high-speed railway.For this purpose,we used the FLAC3D software to analyze the stratum settlement characteristics of high-speed railway at different crossing angles intersected by metro tunnel,in terms of ground settlement trough,stratum slip line and irregularity of ballastless tracks.According to the evolution of the stratum settlement at different angle regions,an optimized angle is proposed for the actual project design.In order to reduce the influence of stratum settlement on the safety of high-speed railway,an approach of safety assessment is proposed for the shield engineering undercutting high-speed railway,as per Chinese specifications using numerical results and on-site conditions.A case study is conducted for the shield tunnel section crossing the Wuhan e Guangzhou High-speed Railway between the Guangzhou North Railway Station and the Huacheng Road Station,which represents the first metro tunnel project passing below a high-speed railway in China.A series of measures is taken to ensure the safe excavation of the shield tunnel and the operation of the high-speed railway.The results can provide a technical support for performing a safety evaluation between high-speed railways and metro tunnels. 展开更多
关键词 METRO TUNNEL EXCAVATION High-speed railway SETTLEMENT characteristics Safety assessment Numerical simulation Case application
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Aerodynamic characteristics of rigid coaxial rotor by wind tunnel test and numerical calculation
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作者 Jinghui DENG Feng FAN +2 位作者 Ping'an LIU Shuilin HUANG Yongfeng LIN 《中国航空学报:英文版》 SCIE EI CAS CSCD 2019年第3期568-576,共9页
Focusing on aerodynamic characteristics of rigid coaxial rotor of a high-speed helicopter in hover and forward flight, a wind tunnel test is conducted in the 8 m×6 m low-speed straightflow wind tunnel of China Ae... Focusing on aerodynamic characteristics of rigid coaxial rotor of a high-speed helicopter in hover and forward flight, a wind tunnel test is conducted in the 8 m×6 m low-speed straightflow wind tunnel of China Aerodynamics Research and Development Center. In the experiment,a 4 m diameter composite model rigid coaxial rotor is designed and manufactured, and firstorder flapping frequency ratio of the blade is 1.796 to ensure sufficient stiffness at the blade root.Rotor aerodynamic performance is measured under hovering and high advance ratio conditions.Also, the numerical method is used to calculate aerodynamic characteristics in typical states of the rigid coaxial rotor for analysis purpose. The rotor lift-drag ratio and lateral lift offset in the experiment are emphatically analyzed for the rigid coaxial rotor. The results indicate that in forward flight condition, the rotor lift-drag ratio first increases and then decreases with the increment of advance ratio and lift offset. When advance ratio remains constant, with the increment of lift offset, the lift-drag ratio of rigid coaxial rotor first increases and then decreases. 展开更多
关键词 Aerodynamic characteristics High-speed HELICOPTER Lateral LIFT OFFSET RIGID COAXIAL ROTOR Wind tunnel test
高速水润滑机械密封的两相流热振动现象
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作者 张国渊 党佳琦 +1 位作者 赵伟刚 赵洋洋 《航空学报》 EI CAS CSCD 北大核心 2019年第3期275-284,共10页
处在高速、快速启动、低黏度介质润滑下的低温高速涡轮泵轴端机械密封性能与常规密封的性能发生了显著的变化,主要因素在于高速的振动影响、低黏度介质下的较差润滑性。以水为模拟介质,研究了低黏度介质下高速机械密封的运转性能,特别... 处在高速、快速启动、低黏度介质润滑下的低温高速涡轮泵轴端机械密封性能与常规密封的性能发生了显著的变化,主要因素在于高速的振动影响、低黏度介质下的较差润滑性。以水为模拟介质,研究了低黏度介质下高速机械密封的运转性能,特别是气液两相流问题,实验过程中发现了两相流介质诱发的热振动问题,其机理可能在于受压缩有限空间内的流体可压缩性的变化导致。测试结果表明,在水润滑升速工况下,机械密封虽能够保持好的密封性能,但其性能变化规律较为复杂;在接触端面从接触到非接触状态的转变过程以及稳定运转过程中均存在两相流状态,密封端面温升和摩擦力存在明显的低频振荡,温度振荡可达30℃;出现汽化两相流的情况下,理论计算的结果与试验结果在升速时误差可达到50%以上。随着密封闭合力的增加,密封会出现明显的两相流现象,相变引起的温度和摩擦力的振荡可归结为一类流体密封的自激振动现象。 展开更多
关键词 机械密封 高速 水润滑 两相流 热振动 涡轮泵
截流板式减摇系统在高速船上的应用 预览
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作者 夏敬停 马雪泉 +1 位作者 李传庆 张亚楠 《中国航海》 CSCD 北大核心 2019年第3期71-75,共5页
高速船由于结构特性易受风浪影响,其摇荡特性又直接影响航行安全和航速指标,故高速船的减摇问题一直是研究重点之一。提出一种针对高速船的新型截流板式减摇系统,该减摇系统可预测船舶摇荡并通过主动拦截来流实现减摇,可有效减弱其在行... 高速船由于结构特性易受风浪影响,其摇荡特性又直接影响航行安全和航速指标,故高速船的减摇问题一直是研究重点之一。提出一种针对高速船的新型截流板式减摇系统,该减摇系统可预测船舶摇荡并通过主动拦截来流实现减摇,可有效减弱其在行进时的纵摇和横摇。通过模型试验验证该减摇系统的可行性,并在某高速艇上进行海上试验验证,试验结果表明:该减摇系统运行稳定、操作简单、减摇效率高,适用于高速船全工况下的减摇作业。 展开更多
关键词 减摇系统 截流板 预测减摇 主动减摇 高速船
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A sensorless efficiency test system for a high-speed permanent magnet synchronous motor 预览
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作者 Li JI Yixiang SHAO Sujie GAO 《现代电力系统与清洁能源学报(英文)》 CSCD 2019年第2期390-399,共10页
We present a sensorless efficiency test system with energy recovery for a high-speed permanent magnet synchronous motor(PMSM). In the system, two identical high-speed PMSMs are used as the motor under test(MUT)and the... We present a sensorless efficiency test system with energy recovery for a high-speed permanent magnet synchronous motor(PMSM). In the system, two identical high-speed PMSMs are used as the motor under test(MUT)and the load machine(LM),respectively.A new sensorless vector control(VC) method based on a hypothetical reference frame is presented to control both the MUT and the LM.Also,a regenerating unit is used to implement energy circulation to save energy.Experiments were carried out on a prototype, with a digital controller based on the TMS320 F28335, to verify the adequacy of the sensorless VC method.As a result,the efficiency test system achieves the load test at the speed of 21000 r/min without any reduction equipment. During the test, the energy regenerated by the LM could be fed back to the MUT by the regenerating unit, and 81.31% electrical power was saved.In addition, with the proposed sensorless VC method,both the MUT and the LM can work at i_d = 0 without a position sensor. 展开更多
关键词 Distributed generation HIGH-SPEED PERMANENT MAGNET SYNCHRONOUS motor(PMSM) SENSORLESS control Energy SAVING
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Condition Recognition of High-Speed Train Bogie Based on Multi-View Kernel FCM
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作者 Qi Rao Yan Yang Yongquan Jiang 《大数据挖掘与分析(英文)》 2019年第1期1-11,共11页
Monitoring the operating status of a High-Speed Train(HST) at any moment is necessary to ensure its security. Multi-channel vibration signals are collected by sensors installed on bogies and beneficial information are... Monitoring the operating status of a High-Speed Train(HST) at any moment is necessary to ensure its security. Multi-channel vibration signals are collected by sensors installed on bogies and beneficial information are extracted to determine the running condition. Based on multi-view clustering and considering different views of complementary information, this study proposes a Multi-view Kernel Fuzzy C-Means(MvKFCM) model for condition recognition of the HST bogie. First, fast Fourier transform coefficients of HST vibration signals of all channels are extracted. Then, the fuzzy classification coefficient of every channel is calculated after clustering to select the appropriate channels. Finally, the selected channels are used to cluster by MvKFCM and the conditions of HST are determined. Experimental results show that the selection is effective to maintain rich feature information and remove redundancy. Furthermore, the condition recognition rate of MvKFCM is higher than that of single-view and four other multiple-view clustering algorithms. 展开更多
关键词 HIGH-SPEED Train(HST) CONDITION RECOGNITION MULTI-VIEW CLUSTERING fuzzy CLUSTERING
Spatial relationship of high-speed transportation construction and land-use efficiency and its mechanism:Case study of Shandong Peninsula urban agglomeration
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作者 CUI Xuegang FANG Chuanglin +1 位作者 WANG Zhenbo BAO Chao 《地理学报:英文版》 SCIE CSCD 2019年第4期549-562,共14页
Land-use efficiency is low for the urban agglomeration of China.High-speed transportation construction has been an important factor driving land use change.It is criti?cally importa nt to explore the spatial relati on... Land-use efficiency is low for the urban agglomeration of China.High-speed transportation construction has been an important factor driving land use change.It is criti?cally importa nt to explore the spatial relati on ship between the high-speed transportation su?periority degree and land-use efficie ncy.We built a model to evaluate the ben efits of con?venient high-speed transportation using the relative density of highways and the distanee from high-speed rail stations and airports as a metric.We used 42 coun ties of the Shan dong Peninsula urban agglomeration as an example.Land?use efficiency was calculated by a DEA model with capital,labor,economic ben efits and envir on mental ben efits as input and output factors.We examined the spatial relati on ships betwee n high-speed tran sport superiority degree and land-use efficiency and obtained the following results.First,there are significant spatial differe nces in the relati on ships betwee n the high-speed transportati on superiority degree and land-use efficiency.Taking the two major cities of Jinan and Qingdao as the hubs,the core surrounding counties show significant spatial relationship between land-use efficiency and the high-speed transportation superiority degree.Spatial correlation declines as the distance from the hubs in creases.Land-use efficiency is less tha n high-speed tran sportation convenience in areas along the transportation trunks that are distant from the hub cities.Correlation is low in areas that are away from both hub cities and transportation trunk routes.Second,high-speed transportation has a positive relationship with land?use efficiency due to the mechanism of element agglomeration exogenous growth.Third,high-speed transportation facilitates the flow of goods,services and tech no logies between core cities and peripheral cities as space spillover(the hub effect).This alters the spatial pattern of regional land-use efficiency.Fin ally,the short-board effect caused by decreased high-speed tran sport corn struction can be balaneed by h 展开更多
关键词 HIGH-SPEED TRANSPORTATION SUPERIORITY degree DEA land-use EFFICIENCY spatial relationship Shandong PENINSULA urban AGGLOMERATION
Cavitation performance of high-speed centrifugal pump with annular jet and inducer at different temperatures and void fractions 预览
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作者 Jin Jiang Yan-hui Li +4 位作者 Chong-yan Pei Lin-lin Li You Fu Hong-gui Cheng Qiang-qiang Sun 《水动力学研究与进展:英文版》 SCIE EI CSCD 2019年第1期93-101,共9页
The cavitation is very common in a centrifugal pump,especially when the speed is very high,and it seriously influences the centrifugal pump performance.In this investigation,the RNG k-ε turbulence model and the cavit... The cavitation is very common in a centrifugal pump,especially when the speed is very high,and it seriously influences the centrifugal pump performance.In this investigation,the RNG k-ε turbulence model and the cavitation model with consideration of the mass transferring are first used to simulate the cavitation performance of the high-speed centrifugal pump without taking any measure for improving the pump cavitation performance.The calculation results reveal that a number of bubbles appear in the centrifugal pump flow channel,and the head as well as the flow rate of the high-speed centrifugal pump are far from its design condition.The cavitation performance can be improved effectively by arranging a variable pitch inducer and adopting an annular nozzle scheme.The flow field analysis of the pump is conducted to obtain the suitable working temperature distribution at different void fractions.On one hand,with the same void fraction,the head of the centrifugal pump drops slowly with the increase of temperature.However,when the temperature exceeds 90°C,the head of the pump drops rapidly.On the other hand,at the constant temperature,the higher the void fraction,the worse the cavitation performance.This research conducted under different temperatures and void fractions provides some guidance for designing an effective high-speed centrifugal pump. 展开更多
关键词 High-speed CENTRIFUGAL pump CAVITATION performance INDUCER ANNULAR NOZZLE VOID fraction
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Development of readout electronics for bunch arrival-time monitor system at SXFEL 预览
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作者 Jin-Guo Wang Bo Liu 《核技术:英文版》 SCIE CAS CSCD 2019年第5期113-121,共9页
A bunch arrival-time monitor (BAM) system, based on electro-optical intensity modulation scheme, is under study at Shanghai Soft X-ray Free Electron Laser. The aim of the study is to achieve high-precision time measur... A bunch arrival-time monitor (BAM) system, based on electro-optical intensity modulation scheme, is under study at Shanghai Soft X-ray Free Electron Laser. The aim of the study is to achieve high-precision time measurement for minimizing bunch fluctuations. A readout electronics is developed to fulfill the requirements of the BAM system. The readout electronics is mainly composed of a signal conditioning circuit, field-programmable gate array (FPGA), mezzanine card (FMC150), and powerful FPGA carrier board. The signal conditioning circuit converts the laser pulses into electrical pulse signals using a photodiode. Thereafter, it performs splitting and low-noise amplification to achieve the best voltage sampling performance of the dual-channel analog-to-digital converter (ADC) in FMC150. The FMC150 ADC daughter card includes a 14-bit 250 Msps dual-channel high-speed ADC, a clock configuration, and a management module. The powerful FPGA carrier board is a commercial high-performance Xilinx Kintex-7 FPGA evaluation board. To achieve clock and data alignment for ADC data capture at a high sampling rate, we used ISERDES, IDELAY, and dedicated carry-in resources in the Kintex-7 FPGA. This paper presents a detailed development of the readout electronics in the BAM system and its performance. 展开更多
关键词 BUNCH arrival-time monitor (BAM) Shanghai Soft X-ray Free Electron Laser (SXFEL) Fieldprogrammable gate array (FPGA) Signal CONDITIONING High-speed analog-to-digital converter (ADC)
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Interactive effects of high-speed rail on nodal zones in a city:Exploratory study on China
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作者 Guo LIU Kunhui YE 《工程管理前沿:英文版》 2019年第3期327-335,共9页
The arrival of the high-speed rail(HSR)era has accelerated the pace of urban development,but its broad socioeconomic impact remains subject to intense debates.This research aims to propose a model for measuring the im... The arrival of the high-speed rail(HSR)era has accelerated the pace of urban development,but its broad socioeconomic impact remains subject to intense debates.This research aims to propose a model for measuring the impact of HSR operation on HSR stations and the surrounding areas,which this research call the HSR丒 based nodal zone(HNZ).The proposed model is composed of two variables(i.e.,transportation situation and vitality)and three subsystems(i.e.,economic,societal,and environmental).Data were collected in China through questionnaire survey.Results indicate that the effects of HSR operation on HNZ are multidimensional,transportation vitality has an intermediary role in the effects,and the effects on the physical environment are negative.This study presents an early examination of the impact of HSR operation on the HSR stations and relevant areas and contributes new evidence to academic debates on the contribution of HSR to urban development.Accordingly,urban development policies should be built on the mechanism of HSR in driving the growth of HNZ. 展开更多
关键词 high-speed RAIL NODAL zone INTERACTIVE effects sustainable URBANIZATION China
高速弹体对钢筋混凝土靶的侵彻/贯穿效应实验研究 预览
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作者 戴湘晖 周刚 +6 位作者 沈子楷 李鹏杰 初哲 王可慧 段建 胡玉涛 杨慧 《高压物理学报》 CAS CSCD 北大核心 2019年第5期136-144,共9页
为了研究高速弹体对钢筋混凝土靶的侵彻/贯穿效应,以100 mm口径滑膛炮作为发射平台,驱动10 kg级卵形弹体以820~1195 m/s速度撞击强度为31.0~43.6 MPa的钢筋混凝土靶,获得了弹体侵彻/贯穿钢筋混凝土靶的终点弹道实验数据,并对弹体的侵彻... 为了研究高速弹体对钢筋混凝土靶的侵彻/贯穿效应,以100 mm口径滑膛炮作为发射平台,驱动10 kg级卵形弹体以820~1195 m/s速度撞击强度为31.0~43.6 MPa的钢筋混凝土靶,获得了弹体侵彻/贯穿钢筋混凝土靶的终点弹道实验数据,并对弹体的侵彻/贯穿深度、靶板侧面自由面效应、弹体的变形进行了详细分析。结果表明:弹体的侵彻/贯穿深度为2.2~2.8 m,部分经验公式预估的侵彻/贯穿深度与实验结果吻合较好;当靶面相对尺寸较小且弹速较高时,靶板侧面自由面效应比较明显;当弹速达到1195 m/s时,弹体开始由刚体向半流体转变。 展开更多
关键词 高速 弹体 钢筋混凝土 侵彻 贯穿 自由面效应
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High-speed target tracking system based on multi-interconnection heterogeneous processor and multi-descriptor algorithm
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作者 Jiaqing WANG Yongxing YANG +1 位作者 Liyuan LIU Nanjian WU 《中国科学:信息科学(英文版)》 SCIE EI CSCD 2019年第6期168-170,共3页
Dear editor,Target tracking has been a subject of intense scholarly research in past decades. Many parallel processors [1–4] and efficient tracking algorithms based on feature extraction [3–5] have been proposed to ... Dear editor,Target tracking has been a subject of intense scholarly research in past decades. Many parallel processors [1–4] and efficient tracking algorithms based on feature extraction [3–5] have been proposed to meet the requirements of high-speed tracking. However. 展开更多
关键词 LBP RP MPU PE HOG High-speed target tracking system based on multi-interconnection HETEROGENEOUS PROCESSOR and multi-descriptor ALGORITHM
High-speed Rail and Urban Economic Growth in China after the Global Financial Crisis
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作者 Shujie Yao Fan Zhang +1 位作者 Feng Wang Jinghua Ou 《中国与世界经济:英文版》 2019年第2期44-65,共22页
High-speed rail(HSR)has been an important driver of China s economic expansion over the last decade.Using data of 285 prefecture-level cities over 2010-2014,this paper proposes an endogenous economic growth model to e... High-speed rail(HSR)has been an important driver of China s economic expansion over the last decade.Using data of 285 prefecture-level cities over 2010-2014,this paper proposes an endogenous economic growth model to explain how and why HSR may have propelled China s economic growth by reducing the time-space between cities.The research results show that HSR has a potent effect on urban economic growth and regional convergence.Ceteris paribus,HSR appears to have accelerated economic growth by more than 0.6 percent and the pace of regional economic convergence by approximately 2 percent per annum over the data period.Our research findings have important policy implications for the sustainability of China s economic development,backed by HSR. 展开更多
关键词 China ECONOMIC growth HIGH-SPEED RAIL REGIONAL CONVERGENCE
Vibration and acoustic radiation of bogie area under random excitation in high-speed trains 预览
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作者 Dongzhen Wang Jianmin Ge 《现代交通学报:英文版》 2019年第2期120-128,共9页
Based on the experiments on a platform with real vehicle structure and finite element simulation, the vibration and interior acoustic radiation under random excitations of high-speed trains’ bogie area were studied. ... Based on the experiments on a platform with real vehicle structure and finite element simulation, the vibration and interior acoustic radiation under random excitations of high-speed trains’ bogie area were studied. Firstly, combined with line tests, a vehicle body with a length of 7 m was used as the research object. By comparing the results of experiment and simulation, the accuracy of the finite element model was verified. Secondly, the power spectral density curves at typical measuring points in bogie area were obtained by processing and calculating the line test data, which was measured when the vehicle ran at high speeds, and the standard vibration spectrum of the bogie area was obtained by the extreme envelope method. Furthermore, the random vibration test and simulation prediction analysis of the real vehicle structure were carried out to further verify the accuracy of the noise and vibration prediction model. Finally, according to the vibration and acoustic radiation theory, the indirect boundary element method was adopted to predict the acoustic response of the real vehicle. The analysis shows that the simulated power spectral density curves of acceleration and sound pressure level are highly consistent with the experimental ones, and the error between the simulated prediction and the experimental result is within the allowable range of 3 dB. 展开更多
关键词 HIGH-SPEED TRAINS Standard vibration spectrum Indirect boundary element method RANDOM EXCITATION ACOUSTIC radiation
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高转速条件下轴向柱塞泵配流副摩擦磨损特性 预览
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作者 王正磊 吴玉程 黄家海 《液压与气动》 北大核心 2019年第8期27-32,共6页
结合轴向柱塞泵配流副实际受力与运动形式,使用盘-环试验机在L-HM46抗磨液压油润滑条件下,研究轴向柱塞泵配流副(38CrMoAl-CuPb15Sn5)在高转速(1800r/min)的摩擦磨损特性并分析磨损机理。实验结果表明:与中低转速相比,高转速测试条件下... 结合轴向柱塞泵配流副实际受力与运动形式,使用盘-环试验机在L-HM46抗磨液压油润滑条件下,研究轴向柱塞泵配流副(38CrMoAl-CuPb15Sn5)在高转速(1800r/min)的摩擦磨损特性并分析磨损机理。实验结果表明:与中低转速相比,高转速测试条件下的配流副更易发生粘着磨损;38CrMoAl经调质、渗氮处理后与CuPb15Sn5组成的配流副在高转速工况下摩擦磨损性能良好,其磨损率比38CrMoAl未经热处理和只渗氮处理配流副分别降低69%和57%;调质热处理可改善38CrMoAl的表面特性,减少摩擦过程中CuPb15Sn5在其表面的附着继而改善配对副摩擦特性,将有助于提高配流副的工作寿命。 展开更多
关键词 轴向柱塞泵 配流副 高转速 摩擦磨损
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基于LabVIEW的高速多通道航天器通用测试系统设计 预览
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作者 高延超 梁克 仪德英 《计算机测量与控制》 2019年第7期59-62,69共5页
传统“微处理器+AD组件”的实现方式,在采集控制及数据处理等方面已很难满足多通道高速并行测试的需求;随着航天器系统及其设备复杂程度的逐渐提高,为满足航天器系统中多状态高速并行测试的要求,提出了一种基于LabVIEW的高速多通道航天... 传统“微处理器+AD组件”的实现方式,在采集控制及数据处理等方面已很难满足多通道高速并行测试的需求;随着航天器系统及其设备复杂程度的逐渐提高,为满足航天器系统中多状态高速并行测试的要求,提出了一种基于LabVIEW的高速多通道航天器通用测试系统设计方案;该系统硬件架构采用PXI机箱、采集板卡、指令控制板卡及处理器板卡,同时基于LabVIEW平台进行系统软件开发,实现了多通道高速并行数据采集控制、数据实时显示、数据存储、数据回放及指令控制等功能;通过测试验证,该测试系统能够支持同时128通道在总采样率1 KHz下的高速并行采集控制及后续数据处理,并能够支持64通道的指令配置及控制;通过长时间累积测试试验,结果表明本系统工作稳定可靠且通用性良好,具有很好的实用价值。 展开更多
关键词 航天器 LABVIEW 高速 多通道 并行采集
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Pulse-burst laser-based 10kHz Thomson scattering measurements
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作者 Zichen HE Cary SMITH +4 位作者 Zhili ZHANG Theodore M BIEWER Naibo JIANG Paul S HSU Sukesh ROY 《等离子体科学与技术:英文版》 SCIE EI CAS CSCD 2019年第10期83-90,共8页
Thomson scattering (TS), as a popular and reliable diagnostic technique, has successfully measured electron temperatures and electron number densities of plasmas for many years. However, conventional TS techniques usi... Thomson scattering (TS), as a popular and reliable diagnostic technique, has successfully measured electron temperatures and electron number densities of plasmas for many years. However, conventional TS techniques using Nd:YAG lasers operate only at tens of hertz. Here, we present the development of a high-repetition-rate TS instrument based on a high-speed, pulse-burst laser system to greatly increase the temporal resolution of measurements. Successful instrument prototype testing was carried out by collecting TS light from laboratory helium and argon plasmas at 10 kHz. Calibration of the instrument detection sensitivity using nitrogen/ oxygen rotational Raman scattering signal is also presented. Quantitative electron number densities and electron temperatures of the plasma were acquired at 10 kHz, for stable plasma discharges as, respectively,~0.9 eV and ~5.37×10^21 m^-3 for the argon plasma, and ~1 eV and ~6.5×10^21 m^-3 for the helium plasma. 展开更多
关键词 THOMSON SCATTERING HIGH-SPEED pulse-burst LASER
高速电铸镍的研究 预览
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作者 郑元伟 符容 +1 位作者 张晓雨 朱增伟 《电镀与环保》 CAS CSCD 北大核心 2019年第4期30-33,共4页
使用氨基磺酸盐型电铸液进行了高速电铸镍实验。研究了温度、搅拌速率及电流密度对铸镍层性能的影响。结果表明:工艺参数影响铸镍层的表面形貌,进而影响铸镍层的性能。在温度为40~50℃、搅拌速率为900 r/min、电流密度为10~12 A/dm^2的... 使用氨基磺酸盐型电铸液进行了高速电铸镍实验。研究了温度、搅拌速率及电流密度对铸镍层性能的影响。结果表明:工艺参数影响铸镍层的表面形貌,进而影响铸镍层的性能。在温度为40~50℃、搅拌速率为900 r/min、电流密度为10~12 A/dm^2的条件下,能够得到表面质量良好且显微硬度较高的铸镍层。 展开更多
关键词 电铸镍 高速 电流密度
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An Optimal Feed Interpolator Based on G^2 Continuous Bézier Curves for High-Speed Machining of Linear Tool Path 预览
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作者 Yongqiao Jin Sheng Zhao Yuhan Wang 《中国机械工程学报:英文版》 SCIE EI CAS CSCD 2019年第3期109-118,共10页
A numerical control (NC) tool path of digital CAD model is widely generated as a set of short line segments in machining. However, there are three shortcomings in the linear tool path, such as discontinuities of tange... A numerical control (NC) tool path of digital CAD model is widely generated as a set of short line segments in machining. However, there are three shortcomings in the linear tool path, such as discontinuities of tangency and curvature, huge number of line segments, and short lengths of line segments. These disadvantages hinder the development of high speed machining. To smooth the linear tool path and improve machining efficiency of short line segments, this paper presents an optimal feed interpolator based on G^2 continuous Bézier curves for the linear tool path. First, the areas suitable for fitting are screened out based on the geometric characteristics of continuous short segments (CSSs). CSSs in every area are compressed and fitted into a G^2 Continuous Bézier curve by using the least square method. Then a series of cubic Bézier curves are generated. However, the junction between adjacent Bézier curves is only G^0 continuous. By adjusting the control points and inserting Bézier transition curves between adjacent Bézier curves, the G^2 continuous tool path is constructed. The fitting error is estimated by the second-order Taylor formula. Without iteration, the fitting algorithm can be implemented in real-time environment. Second, the optimal feed interpolator considering the comprehensive constraints (such as the chord error constraint, the maximum normal acceleration, servo capacity of each axis, etc.) is proposed. Simulation and experiment are conducted. The results shows that the proposed method can generate smooth path, decrease the amount of segments and reduce machining time for machining of linear tool path. The proposed research provides an effective method for high-speed machining of complex 2-D/3-D profiles described by short line segments. 展开更多
关键词 G^2 CONTINUOUS path Least square method HIGH-SPEED MACHINING CONTINUOUS short SEGMENTS Optimal FEED INTERPOLATOR Data compression
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