检索结果-南通市图书馆

同方期刊数据库

Design and experiment of the pneumatic pressure control device for no-till planter

在线全文

学校读者我要写书评

暂无评论

International Journal of Agricultural and Biological Engineering 2023年第3期16卷 37-46页

作者： xinpeng cao Qingjie Wang Hongwen Li Jin He Caiyun Lu Dijuan Xu Xiuhong Wang College of Engineering China Agricultural UniversityBeijing 100083China Cultivated Land Conservation Agricultural Science Observation and Experiment Station Northern Hebei ProvinceMinistry of Agriculture and Rural AffairsBeijing 100083China Beijing Vocational College of Agriculture Beijing 100083China

An adequate and uniform press wheel pressure is crucial for the homogeneous development of a crop,as it affects actual seeding depth and germination *** problems of uneven compaction of seed furrow and consistency of seeding depth can be caused by the pressure fluctuation of the coil-spring pressure control device(CPCD)when the no-till planter is working on the unplowed *** this study,a pneumatic pressure control device(PPCD)was designed for the no-till planter,the key structural parameters of air spring for press wheel pressure(PWP)stability were determined by theoretical analysis and parameter *** the gas-structure coupling finite element simulation method(FESM),the piston radius,piston angle,and cord angle of the air spring are selected as the test factors,and the vertical stiffness was used as the test index to carry out the quadratic rotation orthogonal combination test to establish the regression model of test index and *** bench test of the PPCD was carried out under the optimal parameter combination,piston radius of 27.2 mm,piston angle of 11.7°,and cord angle of 30.0°.The vertical stiffness verification test showed that the simulation test was consistent with the bench test result,the vertical stiffness simulation error was 7.1%,and the internal air pressure simulation error was 3.0%;The control response test showed that the average response time of the air spring inflating and deflating was 0.80 s,the maximum overshoot was 4.33%during inflation,and no pressure overshoot during deflation;Under the condition of-40-40 mm surface relief height,the PPCD could effectively reduce the pressure fluctuation compared with the CPCD,and the average reduction of the pressure fluctuation was about 25.1%.

关键词： air spring no-till planter pressure control finite element analysis

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

单晶镍拉伸行为的分子动力学仿真

锻压技术 2024年第4期49卷 202-213页

作者：耿永祥吴荣达吴韦莉郑海忠李贵发肖怡新曹新鹏易嘉豪南昌航空大学南昌市耐磨耐损构件先进表面激光处理重点实验室江西南昌330063 南昌航空大学材料科学与工程学院江西南昌330063

为了研究单晶镍的拉伸行为,采用LAMMPS分子动力学软件模拟分析了拉伸温度(300、600和900 K)、晶向([100]、[110]、[111])以及孔洞的缺陷数量(0、1、3)和直径(0.2a、0.4a、0.6a)对单晶镍拉伸行为的影响规律。结果表明:拉伸温度和晶向影... 详细信息

为了研究单晶镍的拉伸行为,采用LAMMPS分子动力学软件模拟分析了拉伸温度(300、600和900 K)、晶向([100]、[110]、[111])以及孔洞的缺陷数量(0、1、3)和直径(0.2a、0.4a、0.6a)对单晶镍拉伸行为的影响规律。结果表明:拉伸温度和晶向影响单晶镍的塑性变形方式,而孔洞的缺陷数量和直径影响单晶镍的力学性能。随着拉伸温度的增加,单晶镍的塑性变形方式由相变和层错为主转变为单一的层错变形方式;在[100]晶向上,单晶镍的塑性变形方式以相变和层错为主,而在[110]和[111]晶向上,则以层错为主;与孔洞缺陷数量相比,孔洞缺陷直径对单晶镍的力学性能影响较大,孔洞缺陷的存在致使单晶镍主要以层错形式发生塑性变形,且层错沿与拉伸方向成45°或135°的方向扩展。

关键词：单晶镍分子动力学拉伸行为晶向孔洞缺陷

在线全文

学校读者我要写书评

暂无评论

肥料形状特征精密测量仪及测定方法

农业装备与车辆工程 2024年第5期62卷 1-8页

作者：许珺烁王敬王金星曹鑫鹏傅生辉刘双喜孙林林张宏建山东农业大学机械与电子工程学院山东泰安271018 山东园艺机械设备重点实验室山东泰安271018 山东农业智能装备实验室山东泰安271018

针对人工测量精度低、工作量大以及高精度测量仪器成本高、操作复杂等问题,提出一种精密测量肥料形状特征的仪器及方法,通过图像采集、灰度和伽玛校正以及边缘检测计算肥料形状特征。测量仪以间歇采集模式工作,可同时获取肥料的顶部和... 详细信息

针对人工测量精度低、工作量大以及高精度测量仪器成本高、操作复杂等问题,提出一种精密测量肥料形状特征的仪器及方法,通过图像采集、灰度和伽玛校正以及边缘检测计算肥料形状特征。测量仪以间歇采集模式工作,可同时获取肥料的顶部和侧面图像;然后对顶部和侧面灰度图像进行伽玛校正,以提高图像对比度;最后基于方向梯度的边缘检测算法准确提取肥料的顶部和侧面轮廓图像,并根据轮廓图像计算形状特征。利用三维扫描法和本文提出的方法测量了复合肥、有机肥和生物肥的形状特征,通过Grubbs检验、F检验和t检验评估2种方法之间的显著性差异。结果表明,2种测定方法的肥料形状特征无显著差异,提出的测量仪器和方法可以快速、准确测量肥料的形状特征,为肥料生产和质量检验奠定坚实的基础。

关键词：肥料形状特征测量仪器测量方法双目视觉

同方期刊数据库

Quantitative phase imaging based on holography:trends and new perspectives

在线全文

学校读者我要写书评

暂无评论

Light(Science & Applications) 2024年第7期13卷 1235-1277页

作者： Zhengzhong Huang Liangcai cao Department of Precision Instrument Tsinghua UniversityBeijing 100084China

In 1948,Dennis Gabor proposed the concept of holography,providing a pioneering solution to a quantitative description of the optical *** 75 years of development,holographic imaging has become a powerful tool for optical wavefront measurement and quantitative phase *** emergence of this technology has given fresh energy to physics,biology,and materials *** holography(DH)possesses the quantitative advantages of wide-field,non-contact,precise,and dynamic measurement capability for *** has unique capabilities for the propagation of optical fields by measuring light scattering with phase *** offers quantitative visualization of the refractive index and thickness distribution of weak absorption samples,which plays a vital role in the pathophysiology of various diseases and the characterization of various *** provides a possibility to bridge the gap between the imaging and scattering *** propagation of wavefront is described by the complex *** complex-value in the complex-domain is reconstructed from the intensityvalue measurement by camera in the ***,we regard the process of holographic recording and reconstruction as a transformation between complex-domain and real-domain,and discuss the mathematics and physical principles of *** review the DH in underlying principles,technical approaches,and the breadth of *** conclude with emerging challenges and opportunities based on combining holographic imaging with other methodologies that expand the scope and utility of holographic imaging even *** multidisciplinary nature brings technology and application experts together in label-free cell biology,analytical chemistry,clinical sciences,wavefront sensing,and semiconductor production.

关键词： holographic phase precise

Dynamic Setting Method of Assessment Indicators for Power Curves of Renewable Energy Sources Considering Scarcity of Reserve Resources

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Modern Power Systems and Clean Energy 2024年第1期12卷 101-114页

作者： Minghao cao Jilai Yu the Department of Electrical Engineering Harbin Institute of TechnologyHarbinChina

With the increasing proportion of renewable energy sources(RESs)in power grid,the reserve resource(RR)scarcity for correcting power deviation of RESs has become a potential ***,the power curve of RES needs to be more rigorously *** RR scarcity varies during different time periods,so the values of assessment indicators should be dynamically *** assessment indicators in this paper include two aspects,i.e.,deviation exemption ratio and penalty ***,this paper proposes a method for dynamically calculating the supply capacity and RR cost,primarily taking into account the operating status of thermal units,forecast information of RES,and load ***,after clarifying the logical relationship between the degree of RR scarcity and the values of assessment indicators,this paper establishes a mapping function between *** on this mapping function,a dynamic setting method for assessment indicators is *** the future,RES will generally be equipped with battery energy storage systems(BESSs).Reasonably utilizing BESSs to reduce the power deviation of RESs can increase the expected income of ***,this paper proposes a power curve optimization strategy for RESs considering self-owned *** case study demonstrates that the dynamic setting method of assessment indicators can increase the revenue of RESs while ensuring that the penalty fees paid by RESs to the grid are sufficient to cover the RR ***,the power curve optimization strategy can help RESs further increase income and fully utilize BESSs to reduce power deviation.

关键词： Renewable energy battery energy storage system(BESS) power curve assessment reserve service parameter setting

Zeros of Complete Symmetric Polynomials over Finite Fields

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2024年第4期37卷 1772-1788页

作者： cao Wei School of Mathematics and Statistics Minnan Normal UniversityZhangzhou 363000China

Wan and Zhang(2021) obtained a nontrivial lower bound for the number of zeros of complete symmetric polynomials over finite fields,and proposed a problem whether their bound can be *** this paper,the author improves Wan-Zhang's bound from three *** proposed results are based on the estimates related to the number of certain permutations and the value sets of non-permutation polynomials associated to the complete symmetric *** the author believes that there are still possibilities to improve the bounds and hence Wan-Zhang's bound.

关键词： Complete symmetric polynomial finite field permutation polynomial value set

Bioinspired Closed-loop CPG-based Control of a Robotic Manta for Autonomous Swimming

在线全文

学校读者我要写书评

暂无评论

Journal of Bionic Engineering 2024年第1期21卷 177-191页

作者： Yiwei Hao Yonghui cao Yingzhuo cao Xiong Mo Qiaogao Huang Lei Gong Guang Pan Yong cao School of Marine Science and Technology Northwestern Polytechnical UniversityXi'an 710072China Unmanned Vehicle Innovation Center Ningbo Institute of NPUNingbo 315103China Key Laboratory of Unmanned Underwater Vehicle Technology of Ministry of Industry and Information Technology Xi'an 710072China

Fish in nature exhibit a variety of swimming modes such as forward swimming,backward swimming,turning,pitching,etc.,enabling them to swim in complex scenes such as coral *** is still difficult for a robotic fish to swim autonomously in a confined area as a real ***,we develop an untethered robotic manta as an experimental platform,which consists of two flexible pectoral fins and a tail fin,with three infrared sensors installed on the front,left,and right sides of the head to sense the surrounding *** generate multiple swimming modes of the robotic manta and online switching of different modes,we design a closed-loop Central Pattern Generator(CPG)controller based on distance information and use a combination of phase difference and amplitude of the CPG model to achieve stable and rapid adjustment of yaw *** verify the autonomous swimming ability of the robotic manta in complex scenes,we design an experimental scenario with a concave *** experimental results show that the robotic manta can achieve forward swimming,backward swimming,in situ turning within the concave obstacle,and finally exit from the area safely while relying on the perception of external obstacles,which can provide insight into the autonomous exploration of complex scenes by the biomimetic robotic ***,the swimming ability of the robotic manta is verified by field tests.

关键词： Biomimetic robotic manta Central Pattern Generator Closed-loop control Backward swimming

Multi-scenario land use prediction and layout optimization in Nanjing Metropolitan Area based on the PLUS model

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Geographical Sciences 2024年第7期34卷 1415-1436页

作者： cao Ji cao Weidong cao Yuhong WANG Xuewei ZHANG Yizhen MA Jinji School of Geography and Tourism Anhui Normal UniversityWuhuAnhui241002China School of Ecology and Environment Anhui Normal UniversityWuhuAnhui241002China

The metropolitan area is a crucial spatial element in promoting new urbanization in *** possesses theoretical and empirical value in the determination of the evolutionary patterns and development trends necessary for regional integration and high-quality *** study focused on Nanjing Metropolitan Area,the first national metropolitan area in China,and established three development scenarios by combining ecological–economic spatial conflict(EESC)zones and national key ecological functional *** scenarios simulate the spatial distribution of future land use and land cover change(LUCC)using the development zone planning function of the patch generation land use simulation(PLUS)*** results show that:(1)Between 2000 and 2020,the most prominent characteristics of land use change were largely the massive expansion of built-up land and the significant decline of farmland,while changes in the area of ecological land were less evident.(2)EESC areas experienced significant changes over the past 20 years,but the overall level of conflict was *** land was the main land use type in the lowest-conflict area,while built-up land was the main land use type in the highest-conflict area.(3)From 2030 to 2050,further expansion of built-up areas is expected,with continued decrease of *** regulation of these land use changes can be achieved through different development zone *** economic development scenario had the largest built-up land area,while the ecological protection scenario had the largest farmland *** study simulates the spatial pattern changes in the metropolitan area based on spatial conflict patterns and national main functional area planning process,providing a scientific reference for future spatial planning and management.

关键词： land use change spatial conflict patch-generating simulation land use prediction Nanjing Metropolitan Area

Pt nanodendrites with a PtIr alloy surface structure exhibit excellent stability toward acidic hydrogen evolution reaction

在线全文

学校读者我要写书评

暂无评论

Nano Research 2024年第6期17卷 4844-4849页

作者： Chang Liu Zongnan Wei Minna cao Rong cao State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China University of Chinese Academy of Sciences Beijing 100049China Fujian Science and Technology Innovation Laboratory for Optoelectronic Information of China Fuzhou 350108China

The development of effective and stable electrocatalysts for the hydrogen evolution reaction(HER)in acidic electrolytes is a significant *** this work,homogeneous Pt nanodendrites(Pt NDs)with a PtIr shell were successfully synthesized by a two-step wet chemical *** open three-dimensional(3D)dendritic structure exhibited exceptional electrocatalytic characteristics,exposing as many active sites as ***,by alloying Ir with Pt on the surface,catalytic activity was greatly enhanced while ensuring extremely high *** surface-enriched platinum nanodendritic catalysts(Pt@PtIr NDs)outperformed the control samples and the commercial *** acidic HER test,Pt@PtIr NDs had a lower overpotential(22 mV)than Pt NDs(26 mV)and commercial Pt/C(31 mV)at 10 mA/cm^(2),and the activity of Pt@PtIr NDs remained consistent even after undergoing a continuous durability test for at least 168 h,which was much superior to the performance of commercial Pt/C(10 h)under identical test *** study revealed that the application of 3D Pt dendritic metal alloys may offer a chance for the development of enhanced electrocatalysts in acidic HER.

关键词： Pt nanodendrites iridium high stability hydrogen evolution reaction alloy