检索结果-南通市图书馆

Design of A Novel Wheel-Legged Robot with Rim Shape Changeable Wheels

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2023年第6期36卷 62-72页

作者： Ze Fu Hao Xu Yinghui li Weizhong guo State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong UniversityShanghai 200240China

The wheel-legged hybrid structure has been utilized by ground mobile platforms in recent years to achieve good mobility on both flat surfaces and rough ***,most of the wheel-legged robots only have one-directional obstacle-crossing *** the motion,most of the wheel-legged robots’centroid fluctuates violently,which damages the stability of the ***’s more,many designs of the obstacle-crossing part and transformation-driving part of this structure are highly coupled,which limits its optimal performance in both *** paper presents a novel wheel-legged robot with a rim-shaped changeable wheel,which has a bi-directional and smooth obstacle-crossing *** on the kinematic model,the geometric parameters of the wheel structure and the design variables of the driving four-bar mechanism are optimized *** kinetostatics model of the mobile platform when climbing stairs is established to determine the body length and angular velocity of the driving wheels.A pro-totype is made according to the optimal *** show that the prototype installed with the novel transformable wheels can overcome steps with a height of 1.52 times of its wheel radius with less fluctuation of its centroid and performs good locomotion capabilities in different environments.

关键词： Mobile platform Transformable wheel-legged robot Kinematics analysis Mechanical design Obstacle

热等静压对一种激光增材制造镍基高温合金组织与性能的影响

在线全文

学校读者我要写书评

暂无评论

铸造 2024年第7期73卷 908-914页

作者：陈爽杨彦红郭志强梁静静李金国周亦胄沈阳工业大学材料科学与工程学院辽宁沈阳110870 中国科学院金属研究所辽宁沈阳110016

以ZGH451合金为研究对象,利用OM、SEM、EBSD等手段研究了热等静压前后的微观组织和力学性能。结果表明,经热等静压工艺处理后,ZGH451合金试样熔池消失,微观组织仍为柱状晶,晶粒尺寸和方向基本和沉积态试样保持一致,未出现再结晶和晶粒... 详细信息

以ZGH451合金为研究对象,利用OM、SEM、EBSD等手段研究了热等静压前后的微观组织和力学性能。结果表明,经热等静压工艺处理后,ZGH451合金试样熔池消失,微观组织仍为柱状晶,晶粒尺寸和方向基本和沉积态试样保持一致,未出现再结晶和晶粒长大现象。合金显微缺陷大量减少,微孔体积分数由0.226 5%下降至0.000 512 5%,有效直径由80μm下降至13.5μm。随着热等静压处理温度的升高,位错密度逐渐降低。经热等静压工艺处理后,残余应力从拉应力变为压应力,抗拉强度未发生明显改变;维氏硬度和断后拉伸率大幅上升,HIP1180工艺处理的ZGH451合金维氏硬度从HV 411上升至HV 430,增加了4.7%;断后伸长率提高了35.29%。经过合适的热等静压工艺处理后,使ZGH451合金获得了良好的拉伸性能。

关键词：镍基高温合金增材制造热等静压拉伸性能

Electrical characteristics of laminar propane flame during head-on quenching

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2020年第8期63卷 1497-1508页

作者： guo li ZHAI Ming ZHANG YiChi DONG Peng School of Energy Science and Engineering Harbin Institute of TechnologyHarbin 150001China

The electrical characteristics of laminar propane flame during head-on quenching were investigated experimentally and computationally.A variable small electric field was applied between the burner and the quenching plate,which recorded flame current as a function of the height of the quenching plate,for both polarities,different premixed-air volume,and quenching plate *** detailed information of flame,such as the distribution of OH radical and main charged species(H3O+and e-)were obtained by using numerical *** results showed that during the head-on quenching,the resistance of the propane flame is on the order of 108Ω,the flame current increases with the increase of the premixed-air volume,and the effect of the quenching plate materials on the flame current is *** addition,it is found that the direction of the electric field has a significant influence on the flame current,indicating the"rectifier"characteristics of the ***,it is interestingly found that the trend of flame current for burner-(burner is negative)is more consistent with the trend of the maximum OH mole concentration than for burner+(burner is positive),which indicates that the trend of flame current for burner-can more accurately reflect the combustion state during head-on *** it would be a better choice to use burner as the negative electrode when diagnosing the combustion state with an applied electric field.

关键词： electrical characteristics laminar propane flame head-on quenching

基于非线性空气弹簧模型的整车仿真与主客观评价

在线全文

学校读者我要写书评

暂无评论

汽车安全与节能学报 2024年第1期15卷 20-28页

作者：邬明宇郭沛林李耀超王仕伟侯杰危银涛清华大学智能绿色车辆与交通全国重点实验室(原汽车安全与节能国家重点实验室)北京100084 中国第一汽车股份有限公司研发总院长春130013 汽车振动噪声与安全控制综合技术国家重点试验室长春130013

应用非线性空气弹簧模型,研究了空气悬架整车的动力学仿真和主观评价。结合空气弹簧频率、振幅相关性模型与Simulink仿真,给出了空气悬架整车7自由度模型,对比了不同路面情形下悬架动行程和簧上加速度的均方根值和功率谱密度。从时域和... 详细信息

应用非线性空气弹簧模型,研究了空气悬架整车的动力学仿真和主观评价。结合空气弹簧频率、振幅相关性模型与Simulink仿真,给出了空气悬架整车7自由度模型,对比了不同路面情形下悬架动行程和簧上加速度的均方根值和功率谱密度。从时域和频率2个角度分析了不同速度、路面及减振器阻尼情形下空气悬架整车的动态特性。对装有不同空气弹簧的整车进行主、客观试验测试。结果表明:悬架动行程预测误差小于7%,簧上位置加速度共振峰值预测误差小于6%,共振频率预测误差小于6%;从而验证了所提模型的普适性和精确性;反映了带空气悬架整车的动态特性,解释了平顺性主客观试验的机理。

关键词：车辆结构空气弹簧模型空气悬架动态特性平顺性主客观评价

在线全文

学校读者我要写书评

暂无评论

一种超细铁粉的研发与制备

粉末冶金工业 2024年第3期34卷 97-100页

作者：张立军李晏春郭玉峰刘辉山东泰东新材料有限公司山东济南271100

采用氢气还原法,以钢厂酸洗废料氧化铁红为原料生产超细铁粉产品,成本低于羰基法生产超细铁粉的1/3。产品指标达到TFe大于等于98.5%,松装密度为0.80~1.20 g/cm^(3),粒度D_(50)≤16.5μm,比表面积不小于2.10 m^(2)/g,该产品广泛应用于超... 详细信息

采用氢气还原法,以钢厂酸洗废料氧化铁红为原料生产超细铁粉产品,成本低于羰基法生产超细铁粉的1/3。产品指标达到TFe大于等于98.5%,松装密度为0.80~1.20 g/cm^(3),粒度D_(50)≤16.5μm,比表面积不小于2.10 m^(2)/g,该产品广泛应用于超硬金刚石工具、粉末冶金注射成形材料、高规格软磁材料、吸附材料、航空材料、食品等领域。

关键词：超细铁粉氢气还原焙烧还原羰基松装密度粒度

Experimental Investigation of Flow Patterns in a Pump Intake with Different CWL(Critical Water Level)and Back-Wall Clearance

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2021年第6期30卷 2150-2163页

作者： guo Miao TANG Xuelin li Xiaoqin WANG Fujun College of Water Resources and Civil Engineering China Agricultural UniversityBeijing 100083China Beijing Engineering Research Centre of Safety and Energy Saving Technology for Water Supply Network System China Agricultural UniversityBeijing 100083China

In this study,influence of back-wall clearance,CWL(Critical Water Level)and air content in water on flow patterns in a pump intake has been investigated experimentally and theoretically for different *** statistical data show that CWL for a two-phase flow is lower than that in the case of a single-phase flow at a relatively low flow rate,and as the flow rate increases,this trend turns out to be completely *** experimental data obtained under conditions of subcritical,critical and supercritical flow rates have revealed that the larger the back-wall clearance is,the more vortices exist and the higher the vorticity of free-surface vortices *** the smallest back-wall clearance,the flow coming through the inlet occupies most space under the pipe bell,and both this flow and the inflow coming from the back wall are asymmetric relative to a certain vertical line other than the *** the larger and the largest back-wall clearances,the flows coming from the inlet and from the back wall are almost symmetrical relative to the vertical axis of the pipe *** velocity distributions on two PIV measurement lines for different back-wall clearance magnitudes indicate that the smallest back-wall clearance influences the flow around the pipe bell.

关键词： Critical Water Level(CWL) back-wall clearance air content in water pump intake

Human-machine interactive streaming anomaly detection by online self-adaptive forest

在线全文

学校读者我要写书评

暂无评论

Frontiers of Computer Science 2023年第2期17卷 145-156页

作者： Qingyang li Zhiwen YU Huang XU Bin guo School of Computer Science Northwestern Polytechnical UniversityXi'an 710129China

At nomaly detectors are used to distinguish differences between normal and abnormal data,which are usually implemented by evaluating and ranking the anomaly scores of each instance.A static unsupervised streaming anomaly detector is difficult to dynamically adjust anomaly score *** real scenarios,anomaly detection often needs to be regulated by human feedback,which benefits adjusting anomaly *** this paper,we propose a human-machine interactive streaming anomaly detection method,named ISPForest,which can be adaptively updated online under the guidance of human *** particular,the feedback will be used to adjust the anomaly score calculation and structure of the detector,ideally attaining more accurate anomaly scores in the *** main contribution is to improve the tree-based streaming anomaly detection model that can be updated online from perspectives of anomaly score calculation and model *** approach is instantiated for the powerful class of tree-based streaming anomaly detectors,and we conduct experiments on a range of benchmark *** results demonstrate that the utility of incorporating feedback can improve the performance of anomaly detectors with a few human efforts.

关键词： anomaly detection human-machine interaction human feedback random space tree ensemble method

Composition optimization, high-temperature stability, and thermal cycling performance of Sc-doped Gd_(2)Zr_(2)O_(7) thermal barrier coatings: Theoretical and experimental studies

在线全文

学校读者我要写书评

暂无评论

Journal of Advanced Ceramics 2022年第3期11卷 454-469页

作者： Lei guo Bowen li Yuxian CHENG Lu WANG School of Materials Science and Engineering Tianjin UniversityTianjin 300072China Tianjin Key Laboratory of Advanced Joining Technology Key Lab of Advanced Ceramics and Machining Technology of Ministry of EducationTianjin 300072China AECC Shenyang liming Aero-Engine Co. Ltd.Shenyang 110043China

Sc was doped into Gd_(2)Zr_(2)O_(7) for expanding the potential for thermal barrier coating (TBC) applications. The solid solution mechanism of Sc in the Gd_(2)Zr_(2)O_(7) lattice, and the mechanical and thermophysical properties of the doped Gd_(2)Zr_(2)O_(7) were systematically studied by the first-principles method, based on which the Sc doping content was optimized. Additionally, Sc-doped Gd_(2)Zr_(2)O_(7) TBCs with the optimized composition were prepared by air plasma spraying using YSZ as a bottom ceramic coating (Gd-Sc/YSZ TBCs), and their sintering behavior and thermal cycling performance were examined. Results revealed that at low Sc doping levels, Sc has a large tendency to occupy the lattice interstitial sites, and when the doping content is above 11.11 at%, Sc substituting for Gd in the lattice becomes dominant. Among the doped Gd_(2)Zr_(2)O_(7), the composition with 16.67 at% Sc content has the lowest Pugh’s indicator (G/B) and the highest Poisson ratio (σ) indicative of the highest toughness, and the decreasing trends of Debye temperature and thermal conductivity slow down at this composition. By considering the mechanical and thermophysical properties comprehensively, the Sc doping content was optimized to be 16.67 at%. The fabricated Gd-Sc coatings remain phase and structural stability after sintering at 1400 ℃ for 100 h. Gd-Sc/YSZ TBCs exhibit excellent thermal shock resistance, which is related to the good thermal match between Gd-Sc and YSZ coatings, and the buffering effect of the YSZ coating during thermal cycling. These results revealed that Sc-doped Gd_(2)Zr_(2)O_(7) has a high potential for TBC applications, especially for the composition with 16.67 at% Sc content.

关键词： thermal barrier coating(TBC) first-principles calculation solid solution mechanism high-temperature stability thermal cycling

时效前预拉伸处理对TiB_(2)/7056复合材料组织与性能的影响

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

中南大学学报（自然科学版） 2024年第8期55卷 3072-3082页

作者：郭子龙王邓彪陈送义蒋日鹏李昉陈庚张晨陈康华中南大学极端服役性能精准制造全国重点实验室湖南长沙410083 中南大学轻合金研究院湖南长沙410083 中南大学粉末冶金研究院湖南长沙410083

采取扫描电镜、透射电镜等显微组织表征方法并结合室温拉伸、室温摆锤冲击实验和应力腐蚀等测试手段,研究时效前预拉伸处理对TiB_(2)/7056复合材料组织与性能的影响。研究结果表明:随着时效前预拉伸量增加,TiB_(2)/7056复合材料的位错... 详细信息

采取扫描电镜、透射电镜等显微组织表征方法并结合室温拉伸、室温摆锤冲击实验和应力腐蚀等测试手段,研究时效前预拉伸处理对TiB_(2)/7056复合材料组织与性能的影响。研究结果表明:随着时效前预拉伸量增加,TiB_(2)/7056复合材料的位错密度显著增加,经时效热处理后的晶内析出相直径增大,晶界析出相形貌由链状转变为粗大不连续状,无沉淀析出带宽化;TiB_(2)/7056复合材料的强度先增大后减小,冲击韧性能与延伸率降低;与无预拉伸相比,预拉伸的TiB_(2)/7056复合材料的应力腐蚀抗力显著提升(扩展速率降低1个量级),其主要原因是不连续粗大的晶界析出相阻断了应力腐蚀裂纹的扩展。

关键词： TiB_(2)铝基复合材料 7056铝合金预拉伸显微组织应力腐蚀