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High-bandwidth nanopositioning via active control of system resonance

Linlin LI, Sumeet S. APHALE, Limin ZHU

《机械工程前沿(英文)》 2021年 第16卷 第2期   页码 331-339 doi: 10.1007/s11465-020-0619-x

摘要: Typically, the achievable positioning bandwidth for piezo-actuated nanopositioners is severely limited by the first, lightly-damped resonance. To overcome this issue, a variety of open- and closed-loop control techniques that commonly combine damping and tracking actions, have been reported in literature. However, in almost all these cases, the achievable closed-loop bandwidth is still limited by the original open-loop resonant frequency of the respective positioning axis. Shifting this resonance to a higher frequency would undoubtedly result in a wider bandwidth. However, such a shift typically entails a major mechanical redesign of the nanopositioner. The integral resonant control (IRC) has been reported earlier to demonstrate the significant performance enhancement, robustness to parameter uncertainty, gua-ranteed stability and design flexibility it affords. To further exploit the IRC scheme’s capabilities, this paper presents a method of actively shifting the resonant frequency of a nanopositioner’s axis, thereby delivering a wider closed-loop positioning bandwidth when controlled with the IRC scheme. The IRC damping control is augmented with a standard integral tracking controller to improve positioning accuracy. And both damping and tracking control parameters are analytically optimized to result in a Butterworth Filter mimicking pole-placement—maximally flat passband response. Experiments are conducted on a nanopositioner’s axis with an open-loop resonance at 508 Hz. It is shown that by employing the active resonance shifting, the closed-loop positioning bandwidth is increased from 73 to 576 Hz. Consequently, the root-mean-square tracking errors for a 100 Hz triangular trajectory are reduced by 93%.

关键词: nanopositioning stage     high-bandwidth     resonant mode control     tracking control     integral resonant control    

Bandwidth-limited active suspension controller for an off-road vehicle based on co-simulation technology

FENG Jinzhi, ZHENG Songlin, YU Fan

《机械工程前沿(英文)》 2008年 第3卷 第1期   页码 111-117 doi: 10.1007/s11465-008-0020-7

摘要: This paper presents the design process of a controller for bandwidth-limited active hydro-pneumatic suspension employed by an off-road vehicle based on co-simulation technology. First, a detailed multi-body dynamic model of the vehicle is established by using the ADAMS/View software package, which is followed by validation using a vehicle field test. Second, a combined PID and fuzzy controller is designed for the bandwidth-limited active suspension system and then programmed by means of S-functions in Matlab/Simulink, to which a data exchange interface with ADAMS/View is also defined. Third, the proposed control algorithm is implemented on the multi-body dynamic vehicle model to enable the co-simulation to run repeatedly until a more practical controller is achieved. In the end, the proposed active suspension system is compared with a conventional passive system. Simulation results show that the proposed active suspension system considerably improves both the ride and handling performance of the vehicle and therefore increases the maximum traveling speeds even on rough roads.

关键词: co-simulation technology     exchange interface     conventional     bandwidth-limited     algorithm    

一种基于模糊逻辑的带宽管理方法

李祖欣,王万良,雷必成,陈惠英

《中国工程科学》 2008年 第10卷 第7期   页码 104-111

摘要:

在网络带宽受限的网络控制系统中,设计了一个基于一维输入输出映射关系的模糊逻辑调节器,对 控制系统的带宽进行动态管理。通过调整该模糊逻辑调节器中的非线性偏移因子可以进一步改善系统的控 制性能和带宽需求。同时利用线性矩阵不等式及资源受限条件来确定带宽动态分配的上下界来保证系的 稳定性。另外,定义了多回路归一化控制质量和归一化带宽需求度性能衡量指标来评价网络控制系统的全 局性能。在此评价方法下,提出的模糊带宽管理方法和采用固定带宽分配方法进行仿真比较。结果表明模 糊带宽管理方法相对于固定带宽分配方法而言在提高系统控制性能的同时也节省了网络带宽。

关键词: 模糊带宽管理     网络控制系统     控制质量     带宽需求    

共享信息的第二类网络

李幼平

《中国工程科学》 2002年 第4卷 第8期   页码 8-11

摘要:

基于Internet的万维网是当代共享信息的原创网络(primary web) ,它是一种隐含冲突的系统,难以摆脱带宽瓶颈的困扰,不支持用户数量的自由增长。提出的第二类信息共享网络(secondary web),通过广播镜像把许多网站的完整内容收存于家庭,然后按内容的语义直接提取满足个性需求的读物。第二类网络支持用户数量自由增长,是一种低成本、无冲突共享知识的新传媒,它不仅没有带宽瓶颈,而且避免了信息垃圾。作者认为,第二类网络将同万维网互补互助,共同构成二元化信息共享架构。

关键词: 万维网     第二类共享网络     内容的语义     带宽瓶颈    

一种高增益、宽频带的毫米波双极化法布里—佩罗天线

郭庆毅,黄衡

《信息与电子工程前沿(英文)》 2021年 第22卷 第4期   页码 599-608 doi: 10.1631/FITEE.2000514

摘要: 随着毫米波无线通信技术日趋成熟,以及2019年世界无线电大会(WRC-19)正式将37–43.5 GHz,47.2–48.2 GHz和66–71 GHz等频段用于国际移动通信(IMT),毫米波通信系统近期将陆续在世界范围内开展大规模商用部署。毫米波存在路径损耗大等不利的传播特性。宽带高增益毫米波天线作为通信传播和电子设备之间的接口,为补偿通信系统的路径损耗、提高数据传输提供了保障。基于部分反射表面的法布里—佩罗天线凭借其结构简单、剖面低、成本低、增益高的特点,在高频段的应用中拥有更高的灵活度和潜力。本文提出一种高增益、宽频带的毫米波双极化法布里—佩罗天线,采用宽带的双极化馈源、近似椭圆抛物面的反射地板以及全对称的集成菲涅尔环的单层部分反射表面,实现了宽带高增益的双极化毫米波法布里—佩罗天线设计,为毫米波天线应用和未来通信系统以及通信方案的创新奠定基础。 所提出的天线结构由宽带双极化馈电源、准抛物面反射面和集成菲涅尔环的部分反射表面组成。宽带馈电源是一个3层介质层结构,具有垂直极化和水平极化的2个馈电端口,其辐射器是一个电磁偶极子。此馈电源采用磁电偶极子的辐射体结构实现宽带的特性,通过十字形馈电缝隙提高两个极化之间的极化隔离度,形成宽带高隔离度的毫米波双极化馈电源。设计了准抛物面的反射地板以形成法布里—佩罗腔体,从而激励多模高斯模式,实现整个腔体的宽带化。最后,采用菲涅尔环集成的部分反射表面,完成对电磁波的相位调控,实现天线的高增益特性。 为验证上述设计方法和理念,对所设计的天线进行加工制造以及测量。测试结果表明,此天线的垂直极化和水平极化的峰值增益分别为18.4和17.6 dBi,两种极化的阻抗匹配带宽为14%。此外,两种极化的隔离度高达40 dB,有效避免了两个端口能量的串扰。这些性能确保所提出的双极化法布里—佩罗天线能有效应用于毫米波频段无线通信系统。

关键词: 双极化;法布里—珀罗腔天线;与菲涅耳带透镜集成的部分反射面;毫米波波段;高增益;宽带    

Structural parameter design method for a fast-steering mirror based on a closed-loop bandwidth

Guozhen CHEN, Pinkuan LIU, Han DING

《机械工程前沿(英文)》 2020年 第15卷 第1期   页码 55-65 doi: 10.1007/s11465-019-0545-y

摘要: When a fast-steering mirror (FSM) system is designed, satisfying the performance requirements before fabrication and assembly is vital. This study proposes a structural parameter design approach for an FSM system based on the quantitative analysis of the required closed-loop bandwidth. First, the open-loop transfer function of the FSM system is derived. In accordance with the transfer function, the notch filter and proportional-integral (PI) feedback controller are designed as a closed-loop controller. The gains of the PI controller are determined by maximizing the closed-loop bandwidth while ensuring the robustness of the system. Then, the two unknown variables of rotational radius and stiffness in the open-loop transfer function are optimized, considering the bandwidth as a constraint condition. Finally, the structural parameters of the stage are determined on the basis of the optimized results of rotational radius and stiffness. Simulations are conducted to verify the theoretical analysis. A prototype of the FSM system is fabricated, and corresponding experimental tests are conducted. Experimental results indicate that the bandwidth of the proposed FSM system is 117.6 Hz, which satisfies the minimum bandwidth requirement of 100 Hz.

关键词: fast-steering mirror     structural parameter     PI controller     bandwidth     notch filter    

基于联邦边缘学习的梯度量化和带宽分配优化策略 Research Article

刘沛西1,3,江甲沫2,朱光旭3,程磊4,5,蒋伟1,罗武1,杜滢2,王志勤2

《信息与电子工程前沿(英文)》 2022年 第23卷 第8期   页码 1247-1263 doi: 10.1631/FITEE.2100538

摘要: 由于边缘设备有限算力和边缘网络有限的无线资源,利用联邦边缘学习(federated edge learning, FEEL)训练机器学习模型通常非常耗时。本文研究了量化FEEL系统中训练时间最小化问题,其中异构边缘设备通过正交信道向边缘服务器发送量化后的梯度。采用随机量化对上传的梯度进行压缩,可减少每轮通信的开销,但可能会增加通信轮数。综合考虑通信时间、计算时间和通信轮数对训练时间进行建模。基于所提出的训练时间模型,描述了通信轮数和每轮延迟之间的内在权衡。具体地,分析了量化FEEL的收敛性。提出一种基于数据模型双驱动的拟合方法以得到精确的最优间隔,并在此基础上得到通信轮数和总训练时间的闭式表达式。在总带宽限制下,将训练时间最小化问题建模为量化级数和带宽分配的优化问题。本文通过交替求解量化优化子问题(通过连续凸近似方法求解)和带宽分配子问题(通过二分查找方法求解)解决这个问题。在不同学习任务和模型下,仿真结果证明了本文分析的有效性和所提优化算法性能接近最优。

关键词: 联邦边缘学习;量化优化;带宽分配;训练时间最小化    

Effect of different high viscosity modifiers on rheological properties of high viscosity asphalt

《结构与土木工程前沿(英文)》 2021年 第15卷 第6期   页码 1390-1399 doi: 10.1007/s11709-021-0775-z

摘要: High viscosity asphalt (HVA) has been a great success as a drainage pavement material. However, the larger porosity of drainage asphalt mixtures weakens the cohesion and adhesion and leads to premature rutting, water damage, spalling and cracking. The purpose of this study was to investigate the rheological properties of HVA prepared using different high viscosity modifiers through conventional tests, Brookfield viscosity tests, dynamic shear rheometer tests and bending beam rheometer tests. The conventional performance results demonstrated SBS + rubber asphalt (SRA-1/2) exhibited excellent elastic recovery and low-temperature flexibility. The 60°C dynamic viscosity results indicated TPS + rubber asphalt (TRA) had the excellent adhesion. The rotational viscosity results and rheological results indicated that SRA-2 not only exhibited excellent temperature stability and workability, as well as excellent resistance to deformation and rutting resistance, but also exhibited excellent low-temperature cracking resistance and relaxation performance. Based on rheological results, the PG classification of HVA was 16% rubber + asphalt for PG76-22, 20% rubber + asphalt for PG88-22, TRA and SRA-1/2 for PG88-28. From comprehensive evaluation of the viscosity, temperature stability and sensitivity, as well as high/low temperature performance of HVA, SRA-2 was found to be more suited to the requirements of drainage asphalt pavement materials.

关键词: high viscosity asphalt     rheological properties     rubber     modifier     viscosity    

Continuous deacylation of amides in a high-temperature and high-pressure microreactor

《化学科学与工程前沿(英文)》 2022年 第16卷 第12期   页码 1818-1825 doi: 10.1007/s11705-022-2182-y

摘要: The deacylation of amides, which is widely employed in the pharmaceutical industry, is not a fast reaction under normal conditions. To intensify this reaction, a high-temperature and high-pressure continuous microreaction technology was developed, whose space-time yield was 49.4 times that of traditional batch reactions. Using the deacylation of acetanilide as a model reaction, the effects of the temperature, pressure, reaction time, molar ratio of reactants, and water composition on acetanilide conversion were carefully studied. Based on the rapid heating and cooling capabilities, the kinetics of acetanilide deacylation at high temperatures were investigated to determine the orders of reactants and activation energy. This microreaction technology was further applied to a variety of other amides to understand the influence of substituents and steric hindrance on the deacylation reaction.

关键词: amide deacylation     microreactor     flow chemistry     reaction intensification    

METAGENOMICS COMBINED WITH HIGH-THROUGHPUT SEQUENCING REVEALS THE METHANOGENIC POTENTIAL OF FRESH CORNSTRAW UNDER THERMOPHILIC AND HIGH OLR

《农业科学与工程前沿(英文)》 2023年 第10卷 第3期   页码 403-423 doi: 10.15302/J-FASE-2022471

摘要:

● Methane production from fresh straw was 7.50% higher than dry straw.

关键词: fresh corn straw     high solid anaerobic digestion     metagenomics     microbial communities     thermophilic    

Localized high-concentration electrolytes for lithium metal batteries: progress and prospect

《化学科学与工程前沿(英文)》 2023年 第17卷 第10期   页码 1354-1371 doi: 10.1007/s11705-022-2286-4

摘要: With the increasing development of digital devices and electric vehicles, high energy-density rechargeable batteries are strongly required. As one of the most promising anode materials with an ultrahigh specific capacity and extremely low electrode potential, lithium metal is greatly considered an ideal candidate for next-generation battery systems. Nevertheless, limited Coulombic efficiency and potential safety risks severely hinder the practical applications of lithium metal batteries due to the inevitable growth of lithium dendrites and poor interface stability. Tremendous efforts have been explored to address these challenges, mainly focusing on the design of novel electrolytes. Here, we provide an overview of the recent developments of localized high-concentration electrolytes in lithium metal batteries. Firstly, the solvation structures and physicochemical properties of localized high-concentration electrolytes are analyzed. Then, the developments of localized high-concentration electrolytes to suppress the formation of dendritic lithium, broaden the voltage window of electrolytes, enhance safety, and render low-temperature operation for robust lithium metal batteries are discussed. Lastly, the remaining challenges and further possible research directions for localized high-concentration electrolytes are outlined, which can promisingly render the practical applications of lithium metal batteries.

关键词: high-concentration electrolyte     localized high-concentration electrolyte     lithium metal battery     solid electrolyte interphase     dendrite    

Approaches to achieve high grain yield and high resource use efficiency in rice

Jianchang YANG

《农业科学与工程前沿(英文)》 2015年 第2卷 第2期   页码 115-123 doi: 10.15302/J-FASE-2015055

摘要: This article discusses approaches to simultaneously increase grain yield and resource use efficiency in rice. Breeding nitrogen efficient cultivars without sacrificing rice yield potential, improving grain fill in later-flowering inferior spikelets and enhancing harvest index are three important approaches to achieving the dual goal of high grain yield and high resource use efficiency. Deeper root distribution and higher leaf photosynthetic N use efficiency at lower N rates could be used as selection criteria to develop N-efficient cultivars. Enhancing sink activity through increasing sugar-spikelet ratio at the heading time and enhancing the conversion efficiency from sucrose to starch though increasing the ratio of abscisic acid to ethylene in grains during grain fill could effectively improve grain fill in inferior spikelets. Several practices, such as post-anthesis controlled soil drying, an alternate wetting and moderate soil drying regime during the whole growing season, and non-flooded straw mulching cultivation, could substantially increase grain yield and water use efficiency, mainly via enhanced remobilization of stored carbon from vegetative tissues to grains and improved harvest index. Further research is needed to understand synergistic interaction between water and N on crop and soil and the mechanism underlying high resource use efficiency in high-yielding rice.

关键词: rice     nitrogen-efficient cultivar     grain fill     harvest index     nitrogen use efficiency     water use efficiency    

A novel high-temperature and high-pressure hydraulic pump based on mononeuron control

Linhui ZHAO, Xin FANG

《机械工程前沿(英文)》 2009年 第4卷 第2期   页码 219-223 doi: 10.1007/s11465-009-0024-y

摘要: Based on structures and characteristics of traditional hydraulic pumps, this paper proposes a novel high-temperature and high-pressure hydraulic pump (HHHP) that can work under 150°C and 28 MPa to overcome problems of traditional high-temperature plunger pumps. The HHHP is designed with the structure of mechanical division and double cylinder parallel. The control signals of two cylinders are two separate triangle waveforms with 90° phase difference. Because the output waveforms of two cylinders have the same characteristics as the control signals, the HHHP can obtain a stable output after two separate waveforms are superposed. A mononeuron self-adaptive PID control algorithm is also improved by modifying parameters and . Two improved controllers are used to control the two cylinders, respectively, making two displacements of plungers match each other. Therefore, reduced fluctuations and stable pressure output is obtained. Besides simulation, tests on the built prototype test system are carried out to verify the performance of HHHP. Results show that the improved control approach can limit fluctuations to a lower level and the HHHP system attains good outputs under different signal periods and different pressures.

关键词: mononeuron PID control     hydraulic pump     pressure fluctuation    

CR-Fuxing high-speed EMU series

《工程管理前沿(英文)》   页码 742-748 doi: 10.1007/s42524-023-0281-1

摘要: CR-Fuxing high-speed EMU series

关键词: CR-Fuxing series     high-speed EMU     innovation     key system     digitalized collaborative design     engineering management    

Value and governance of high-speed railway

Xiaoyan LIN, Zehua ZHANG, Meng WANG

《工程管理前沿(英文)》 2017年 第4卷 第4期   页码 463-482 doi: 10.15302/J-FEM-2017054

摘要: This paper considers multiple perspectives to explore the concept of high-speed railway (HSR), rationally abstract its value formation mechanism, and quantitatively measure its actual performance. This paper analyzes the governance potential of major countries in the high-speed railway value chain and studies the feasible ways and development strategies to enhance the high-speed railway governance in China. Findings of this paper are as follows. First, the government, as the early manager of high-speed railway governance, has given way to Siemens and other integrated enterprises. Second, the high-speed railway standard output has become the core competitiveness that embodies high-speed railway. Third, the global high-speed railway market presents a hierarchical high-speed railway governance model and changes to a modular approach to governance.

关键词: high-speed railway value     communication value     high-speed railway value governance     governance path upgrade    

标题 作者 时间 类型 操作

High-bandwidth nanopositioning via active control of system resonance

Linlin LI, Sumeet S. APHALE, Limin ZHU

期刊论文

Bandwidth-limited active suspension controller for an off-road vehicle based on co-simulation technology

FENG Jinzhi, ZHENG Songlin, YU Fan

期刊论文

一种基于模糊逻辑的带宽管理方法

李祖欣,王万良,雷必成,陈惠英

期刊论文

共享信息的第二类网络

李幼平

期刊论文

一种高增益、宽频带的毫米波双极化法布里—佩罗天线

郭庆毅,黄衡

期刊论文

Structural parameter design method for a fast-steering mirror based on a closed-loop bandwidth

Guozhen CHEN, Pinkuan LIU, Han DING

期刊论文

基于联邦边缘学习的梯度量化和带宽分配优化策略

刘沛西1,3,江甲沫2,朱光旭3,程磊4,5,蒋伟1,罗武1,杜滢2,王志勤2

期刊论文

Effect of different high viscosity modifiers on rheological properties of high viscosity asphalt

期刊论文

Continuous deacylation of amides in a high-temperature and high-pressure microreactor

期刊论文

METAGENOMICS COMBINED WITH HIGH-THROUGHPUT SEQUENCING REVEALS THE METHANOGENIC POTENTIAL OF FRESH CORNSTRAW UNDER THERMOPHILIC AND HIGH OLR

期刊论文

Localized high-concentration electrolytes for lithium metal batteries: progress and prospect

期刊论文

Approaches to achieve high grain yield and high resource use efficiency in rice

Jianchang YANG

期刊论文

A novel high-temperature and high-pressure hydraulic pump based on mononeuron control

Linhui ZHAO, Xin FANG

期刊论文

CR-Fuxing high-speed EMU series

期刊论文

Value and governance of high-speed railway

Xiaoyan LIN, Zehua ZHANG, Meng WANG

期刊论文