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期刊论文 33

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2023 4

2022 2

2021 3

2020 2

2019 3

2017 4

2015 1

2014 1

2012 7

2010 1

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2007 2

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关键词

CP);符号间干扰(inter symbol interference, ISI);载波间干扰(inter carrier interference 1

ICI);最大似然估计(maximum likelihood estimation 1

MLE) 1

OFDM);快速傅立叶变换(Fast Fourier transform, FFT);循环前缀(cyclic prefix 1

万维网 1

中断模型;k-可靠性;对偶;线性规划松弛;互补松弛型 1

内容的语义 1

农业 1

医院中子照射器 1

半旱地 1

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 1

可见光通信;游程长度受限码;有限状态机;最小汉明距离 1

四旋翼飞行器;无人机;运动规划 1

带宽瓶颈 1

带宽需求 1

折减 1

控制质量 1

有限补灌 1

模型试验 1

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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    

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    

Emergent limited perioperative transesophageal echocardiography: should new guidelines exist for limited

null

《医学前沿(英文)》 2012年 第6卷 第3期   页码 332-337 doi: 10.1007/s11684-012-0212-8

摘要:

Bedside limited echocardiography, or focused cardiac ultrasound, continues to gain popularity in many emergency rooms, intensive care units, and operating rooms as a rapid method of assessing unstable patients. Effective monitoring of cardiovascular function in conditions like cardiac arrest or near-arrest is the crucial step to guide successful resuscitative efforts. Transesophageal echocardiography (TEE) has emerged as one of the preferred cardiac diagnostic and monitoring modalities in the intraoperative setting due to the fact that it is less invasive than many other monitors, is immediately accessible, and allows for continuous real-time monitoring of cardiac function. However, the minimum training requirements needed for the anesthesia provider to obtain the competency, knowledge, and skills for basic certification in perioperative TEE far exceed those developed for other medical specialties. We believe there is an urgent need to develop (1) practical guidelines for emergent perioperative TEE use for anesthesiologists and (2) a requisite educational curriculum to teach the basic skills necessary to aid in the diagnosis and treatment of cardiac arrest or near-arrest scenarios. The measures elucidated in this report summarize the efforts of the Department of Anesthesiology at the University of Florida in establishing the necessary steps to make this process not only practical, but accessible to all trainees. We hope that these collective efforts will provide more trainees the confidence in utilizing TEE to aid in establishing a diagnosis in critical situations.

关键词: transesophageal echocardiography     curriculum     competency training     hemodynamic instability    

Highlights of special issue on ‘Agriculture in Water-Limited Areas’

Pute WU

《农业科学与工程前沿(英文)》 2017年 第4卷 第2期   页码 123-125 doi: 10.15302/J-FASE-2017147

Two-stage scheduling on batch and single machines with limited waiting time constraint

Zhongshun SHI, Zewen HUANG, Leyuan SHI

《工程管理前沿(英文)》 2017年 第4卷 第3期   页码 368-374 doi: 10.15302/J-FEM-2017034

摘要: This study addresses the problem of two-stage scheduling on batch and single machines with limited waiting time constraint; thus, the makespan is minimized. A mixed-integer linear programming model is proposed for this problem. Three tight lower bounds and a heuristic algorithm are developed. The worst-case performance of the proposed algorithm is discussed. A hybrid differential evolution algorithm is also developed to improve the solution quantity. Numerical results show that the hybrid algorithm is capable of obtaining high-quality solutions and exhibits a competitive performance

关键词: batch machine     flow shop     makespan     limited waiting time    

Adaptation of Chinese and German maize-based food-feed-energy systems to limited phosphate resources—a

null

《农业科学与工程前沿(英文)》 2019年 第6卷 第4期   页码 313-320 doi: 10.15302/J-FASE-2019282

摘要:

Phosphate is supplied to agriculture by mining and fertilizer production, followed by different steps of phosphate utilization, including primary production, feed and food consumption, and conversion of biomass, with accumulation in soils, but little recycling and severe environmental losses. Phosphate is a limited essential nutrient, however, with very uneven distribution worldwide. Closing the cycle and reducing primary phosphate consumption are fundamental future challenges. Maize has a relatively high phosphate requirement. China and Germany together cover the whole range of maize production systems. The new Sino-German international research training group “Adaptation of Chinese and German maize-based food-feed-energy systems to limited phosphate resources” (AMAIZE-P) was initiated in 2018 as a joint venture of the China Agricultural University (Beijing, China) and the University of Hohenheim (Stuttgart, Germany). The interdisciplinary and complementary research is driven by the hypothesis that under phosphate limited conditions, high productivity and high phosphate use efficiency can be achieved simultaneously by adapting phosphate cycling and availability (sources) to the multipurpose phosphate demands (sinks) in maize-based food-feed-energy systems. The educational program for doctoral researchers in China and Germany includes joint block seminars, thematic field trips, case studies, methodological courses, doctoral researchers’ conferences, intercultural training sessions and personal training.

关键词: international research training group     limited resources     maize     phosphate    

Non-convex sparse optimization-based impact force identification with limited vibration measurements

《机械工程前沿(英文)》 2023年 第18卷 第3期 doi: 10.1007/s11465-023-0762-2

摘要: Impact force identification is important for structure health monitoring especially in applications involving composite structures. Different from the traditional direct measurement method, the impact force identification technique is more cost effective and feasible because it only requires a few sensors to capture the system response and infer the information about the applied forces. This technique enables the acquisition of impact locations and time histories of forces, aiding in the rapid assessment of potentially damaged areas and the extent of the damage. As a typical inverse problem, impact force reconstruction and localization is a challenging task, which has led to the development of numerous methods aimed at obtaining stable solutions. The classical 2 regularization method often struggles to generate sparse solutions. When solving the under-determined problem, 2 regularization often identifies false forces in non-loaded regions, interfering with the accurate identification of the true impact locations. The popular 1 sparse regularization, while promoting sparsity, underestimates the amplitude of impact forces, resulting in biased estimations. To alleviate such limitations, a novel non-convex sparse regularization method that uses the non-convex 12 penalty, which is the difference of the 1 and 2 norms, as a regularizer, is proposed in this paper. The principle of alternating direction method of multipliers (ADMM) is introduced to tackle the non-convex model by facilitating the decomposition of the complex original problem into easily solvable subproblems. The proposed method named 12-ADMM is applied to solve the impact force identification problem with unknown force locations, which can realize simultaneous impact localization and time history reconstruction with an under-determined, sparse sensor configuration. Simulations and experiments are performed on a composite plate to verify the identification accuracy and robustness with respect to the noise of the 12-ADMM method. Results indicate that compared with other existing regularization methods, the 12-ADMM method can simultaneously reconstruct and localize impact forces more accurately, facilitating sparser solutions, and yielding more accurate results.

关键词: impact force identification     inverse problem     sparse regularization     under-determined condition     alternating direction method of multipliers    

Full-field dynamic strain reconstruction of an aero-engine blade from limited displacement responses

《机械工程前沿(英文)》 2023年 第18卷 第1期 doi: 10.1007/s11465-022-0731-1

摘要: Blade strain distribution and its change with time are crucial for reliability analysis and residual life evaluation in blade vibration tests. Traditional strain measurements are achieved by strain gauges (SGs) in a contact manner at discrete positions on the blades. This study proposes a method of full-field and real-time strain reconstruction of an aero-engine blade based on limited displacement responses. Limited optical measured displacement responses are utilized to reconstruct the full-field strain. The full-field strain distribution is in-time visualized. A displacement-to-strain transformation matrix is derived on the basis of the blade mode shapes in the modal coordinate. The proposed method is validated on an aero-engine blade in numerical and experimental cases. Three discrete vibrational displacement responses measured by laser triangulation sensors are used to reconstruct the full-field strain over the whole operating time. The reconstructed strain responses are compared with the results measured by SGs and numerical simulation. The high consistency between the reconstructed and measured results demonstrates the accurate strain reconstructed by the method. This paper provides a low-cost, real-time, and visualized measurement of blade full-field dynamic strain using displacement response, where the traditional SGs would fail.

关键词: aero-engine blade     displacement response     dynamic strain reconstruction     mode shape     strain gauge    

dynamics of polymer solar cells probed by a transient photocurrent nearby the regime of the space charge-limited

Boa Jin, Hyunmin Park, Yang Liu, Leijing Liu, Jongdeok An, Wenjing Tian, Chan Im

《化学科学与工程前沿(英文)》 2021年 第15卷 第1期   页码 164-179 doi: 10.1007/s11705-020-1976-z

摘要: To understand the complex behaviors of photogenerated charge carriers within polymer-based bulk-heterojunction-type solar cells, the charge-carrier photogeneration and extraction dynamics are simultaneously estimated using a transient photocurrent technique under various external-bias voltages, and a wide range of excitation intensities are analyzed. For this purpose, conventional devices with 80 nm thick active layers consisting of a blend of representative P3HT and PTB7 electron-donating polymers and proper electron-accepting fullerene derivatives were used. After the correction for the saturation behavior at a high excitation-intensity range nearby the regime of the space charge-limited current, the incident-photon-density-dependent maximum photocurrent densities at the initial peaks are discussed as the proportional measures of the charge-carrier-photogeneration facility. By comparing the total number of the extracted charge carriers to the total number of the incident photons and the number of the initially photogenerated charge carriers, the external quantum efficiencies as well as the extraction quantum efficiencies of the charge-carrier collection during a laser-pulse-induced transient photocurrent process were obtained. Subsequently, the charge-carrier concentration-dependent mobility values were obtained, and they are discussed in consideration of the additional influences of the charge-carrier losses from the device during the charge-carrier extraction that also affects the photocurrent-trace shape.

关键词: charge-carrier photogeneration     transient photocurrent     polymer solar cells     charge-carrier extraction     space charge-limited current    

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    

北方缺水地区半旱地农业有限补灌模式探讨

李英能

《中国工程科学》 2012年 第14卷 第3期   页码 41-45

摘要:

以降水利用和灌溉程度为依据,对半旱地农业进行了研究,着重讨论了与半旱地农业涵义有关的问题,论述了在北方缺水地区发展半旱地农业的意义,给出了半旱地农业有限补灌技术模式。针对北方缺水地区的特点,提出了不同类型区半旱地农业有限补灌发展模式,并探讨了北方缺水地区半旱地农业发展有限补灌的策略。

关键词: 半旱地     农业     有限补灌     模式    

Industrial Structure Adjustment of Shaanxi Province under the Limited Water Resources Condition

Xiao-jun Liu,Zhen-yu Guo,Chao Ding,Han-liang Fu

《工程管理前沿(英文)》 2014年 第1卷 第4期   页码 378-384 doi: 10.15302/J-FEM-2014057

摘要: Shaanxi Province is a region poor of water resources in China, and the lack of water resources is becoming a key factor which restricts the social and economic development of Shaanxi Province. In the perspective of efficient utilization of water resources, Shaanxi Province is committed to the transformation of the economic growth and the industrial structure, and treats these measures as important guarantees for the future development of Shaanxi Province. This paper focuses on building multi-objective programming model of industrial structure optimization under the limited water resources condition, indicates the direction of the industrial transformation and water consumption structural adjustment by solving the model, and furthermore points out the key factors that affect the development of Shaanxi Province in the future. Finally, the authors give some advices of promoting the reasonable and effective utilization of water resources of Shaanxi Province.

关键词: water resources     capacity of water resources     industrial transformation     multi-objective programming    

手机直连卫星,未来可期

Mitch Leslie

《工程(英文)》 2023年 第28卷 第9期   页码 4-6 doi: 10.1016/j.eng.2023.07.003

Monte Carlo simulation of the diffusion-limited aggregating process of particle suspension systems

Jiajing XU, Lin ZHANG, Yongjian TANG, Wei DAI, Wenwen SHAN,

《化学科学与工程前沿(英文)》 2010年 第4卷 第3期   页码 270-274 doi: 10.1007/s11705-009-0273-7

摘要: The aggregating process of particle suspension systems is a very universal phenomena and crucial for various processes both in nature and in industry. In this paper, the aggregating process was simulated with off-lattice diffusion-limited cluster-cluster aggregation (DLCA) Monte Carlo programs. The self-similar fractal structures of aggregates have been clearly demonstrated by the statistical analysis of gyration radius distribution and the existence of a scaling distribution of the reduced cluster size. The fractal dimension determined from the relationship between mass and gyration radius of aggregates was 1.80 or so. The fractal dimension of the aggregates drawn from the radial distribution function and structure factor of a single aggregate is about 1.90–2.10. It was also showed that, along with the increasing of particle volume fraction, the fractal dimension will increase in a nearly square root manner, and the spatial range of the fractal structure appearing becomes narrower. Also, the gelation transition can only occur in a particle suspension system where the particle volume fraction is greater than a critical value.

关键词: cluster-cluster aggregation     distribution function     relationship     process     universal    

Comments on “Adaptation of Chinese and German maize-based food-feed-energy systems to limited phosphate

null

《农业科学与工程前沿(英文)》 2019年 第6卷 第4期   页码 443-444 doi: 10.15302/J-FASE-2019288

标题 作者 时间 类型 操作

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

High-bandwidth nanopositioning via active control of system resonance

Linlin LI, Sumeet S. APHALE, Limin ZHU

期刊论文

Emergent limited perioperative transesophageal echocardiography: should new guidelines exist for limited

null

期刊论文

Highlights of special issue on ‘Agriculture in Water-Limited Areas’

Pute WU

期刊论文

Two-stage scheduling on batch and single machines with limited waiting time constraint

Zhongshun SHI, Zewen HUANG, Leyuan SHI

期刊论文

Adaptation of Chinese and German maize-based food-feed-energy systems to limited phosphate resources—a

null

期刊论文

Non-convex sparse optimization-based impact force identification with limited vibration measurements

期刊论文

Full-field dynamic strain reconstruction of an aero-engine blade from limited displacement responses

期刊论文

dynamics of polymer solar cells probed by a transient photocurrent nearby the regime of the space charge-limited

Boa Jin, Hyunmin Park, Yang Liu, Leijing Liu, Jongdeok An, Wenjing Tian, Chan Im

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

北方缺水地区半旱地农业有限补灌模式探讨

李英能

期刊论文

Industrial Structure Adjustment of Shaanxi Province under the Limited Water Resources Condition

Xiao-jun Liu,Zhen-yu Guo,Chao Ding,Han-liang Fu

期刊论文

手机直连卫星,未来可期

Mitch Leslie

期刊论文

Monte Carlo simulation of the diffusion-limited aggregating process of particle suspension systems

Jiajing XU, Lin ZHANG, Yongjian TANG, Wei DAI, Wenwen SHAN,

期刊论文

Comments on “Adaptation of Chinese and German maize-based food-feed-energy systems to limited phosphate

null

期刊论文