检索范围：

排序： 展示方式：

Heng NIAN,Yi-peng SONG

《信息与电子工程前沿（英文）》
2015年
第16卷
第4期
页码 321-334
*doi:*
*10.1631/FITEE.1400170*

摘要：
This paper presents a multiple target implementation technique for a doubly fed induction generator (DFIG) under unbalanced and distorted grid voltage based on direct power control (DPC). Based on the mathematical model of DFIG under unbalanced and distorted voltage, the proportional and integral (PI) regulator is adopted to regulate the DFIG average active and reactive powers, while the vector PI (VPI) resonant regulator is used to achieve three alternative control targets: (1) balanced and sinusoidal stator current; (2) smooth instantaneous stator active and reactive powers; (3) smooth electromagnetic torque and instantaneous stator reactive power. The major advantage of the proposed control strategy over the conventional method is that neither negative and harmonic sequence decomposition of grid voltage nor complicated control reference calculation is required. The insensitivity of the proposed control strategy to DFIG parameter deviation is analyzed. Finally, the DFIG experimental system is developed to validate the availability of the proposed DPC strategy under unbalanced and distorted grid voltage.

关键词： Direct power control Doubly fed induction generator Unbalanced and distorted grid voltage Vector proportional and integral resonant regulator Parameter deviation

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

LU Yanjun, HEI Di, WANG Yuan, DAI Rong, LU Yanjun, LIU Heng, YU Lie

《机械工程前沿（英文）》
2008年
第3卷
第2期
页码 193-199
*doi:*
*10.1007/s11465-008-0023-4*

摘要：
The stability and coupling dynamic behavior of a journal active electromagnetic bearing rotor system are analyzed. The gyroscopic effect is considered in the rotor model. The system equations are formulated by combining equations for rotor motion and decentralized proportional integral differential (PID) controllers. A method combining the predictor-corrector mechanism and the Netwon-Raphson method is presented to calculate the critical speed at the corresponding Hopf bifurcation point of the system. For periodic motions, a continuation method combining the predictor-corrector mechanism and shooting method is presented. Nonlinear unbalanced periodic motions and their stability margins are obtained using the shooting method and established continuation method for periodic motions. With the change of control parameters, the system local stability and bifurcation behaviors are obtained using the Floquet theory. The numerical examples show that the schemes not only significantly save computing cost, but also have high precision.

关键词： proportional integral bifurcation corresponding integral differential predictor-corrector mechanism

Control algorithm of a servo platform

Shouyong XIE, Xiwen LI, Shuzi YANG, Mingjin YANG,

《机械工程前沿（英文）》
2010年
第5卷
第3期
页码 353-355
*doi:*
*10.1007/s11465-010-0098-6*

摘要：
According to the characteristics of the movement of a special-purpose three-axis servo platform, this paper presents an improved grey prediction proportional integral derivative (PID) control algorithm. Different weights at different time are given to different sampling moments in the algorithm, and the time meanings of the sample data are paid more attention. Simulation results show that the performance of response and stability of the platform of the improved algorithm is better than that of the traditional one. The control algorithm meets all requirements of the control system of the special-purpose three-axis servo platform.

关键词： grey prediction proportional integral derivative (PID) control improved algorithm weight servo platform

Proportional directional valve based automatic steering system for tractors

Jin-yi LIU,Jing-quan TAN,En-rong MAO,Zheng-he SONG,Zhong-xiang ZHU

《信息与电子工程前沿（英文）》
2016年
第17卷
第5期
页码 458-464
*doi:*
*10.1631/FITEE.1500172*

摘要：
Most automatic steering systems for large tractors are designed with hydraulic systems that run on either constant flow or constant pressure. Such designs are limited in adaptability and applicability. Moreover, their control valves can unload in the neutral position and eventually lead to serious hydraulic leakage over long operation periods. In response to the problems noted above, a multifunctional automatic hydraulic steering circuit is presented. The system design is composed of a 5-way-3- position proportional directional valve, two pilot-controlled check valves, a pressure-compensated directional valve, a pressurecompensated flow regulator valve, a load shuttle valve, and a check valve, among other components. It is adaptable to most open-center systems with constant flow supply and closed-center systems with load feedback. The design maintains the lowest pressure under load feedback and stays at the neutral position during unloading, thus meeting the requirements for steering. The steering controller is based on proportional-integral-derivative (PID) running on a 51-microcontroller-unit master control chip. An experimental platform is developed to establish the basic characteristics of the system subject to stepwise inputs and sinusoidal tracking. Test results show that the system design demonstrates excellent control accuracy, fast response, and negligible leak during long operation periods.

关键词： Automatic steering system Hydraulic circuit Proportional directional valve Proportional-integral-derivative (PID) control

Convergence performance comparisons of PID, MRAC, and PID+MRAC hybrid controller

Dan ZHANG,Bin WEI

《机械工程前沿（英文）》
2016年
第11卷
第2期
页码 213-217
*doi:*
*10.1007/s11465-016-0386-x*

摘要：

This study proposes a hybrid controller by combining a proportional-integral-derivative (PID) control and a model reference adaptive control (MRAC), which named as PID+MRAC controller. The convergence performances of the PID control, MRAC, and hybrid PID+MRAC are also compared. Through the simulation in Matlab, the results show that the convergence speed and performance of the MRAC and the PID+MRAC controller are better than those of the PID controller. In addition, the convergence performance of the hybrid control is better than that of the MRAC control.

关键词： proportional-integral-derivative (PID) control model reference adaptive control hybrid control convergence speed comparison

High-precision gyro-stabilized control of a gear-driven platform with a floating gear tension device

《机械工程前沿（英文）》
2021年
第16卷
第3期
页码 487-503
*doi:*
*10.1007/s11465-021-0635-5*

摘要：
This study presents an improved compound control algorithm that substantially enhances the anti-disturbance performance of a gear-drive gyro-stabilized platform with a floating gear tension device. The tension device can provide a self-adjustable preload to eliminate the gap in the meshing process. However, the weaker gear support stiffness and more complex meshing friction are also induced by the tension device, which deteriorates the control accuracy and the ability to keep the aim point of the optical sensors isolated from the platform motion. The modeling and compensation of the induced complex nonlinearities are technically challenging, especially when base motion exists. The aim of this research is to cope with the unmeasured disturbances as well as the uncertainties caused by the base lateral motion. First, the structural properties of the gear transmission and the friction-generating mechanism are analyzed, which classify the disturbances into two categories: Time-invariant and time-varying parts. Then, a proportional-integral controller is designed to eliminate the steady-state error caused by the time-invariant disturbance. A proportional multiple-integral-based state augmented Kalman filter is proposed to estimate and compensate for the time-varying disturbance that can be approximated as a polynomial function. The effectiveness of the proposed compound algorithm is demonstrated by comparative experiments on a gear-drive pointing system with a floating gear tension device, which shows a maximum 76% improvement in stabilization precision.

关键词： inertially stabilized platform floating gear tension device nonlinear friction disturbance compensation proportional multiple-integral observer

Akhil GUPTA,Saurabh CHANANA,Tilak THAKUR

《能源前沿（英文）》
2014年
第8卷
第4期
页码 464-479
*doi:*
*10.1007/s11708-014-0307-9*

摘要：
Dynamic voltage restorer (DVR) is used to protect sensitive loads from voltage disturbances of the distribution generation (DG) system. In this paper, a new control approach for the 200 kW solar photovoltaic grid connected system with perturb and observe maximum power point tracking (MPPT) technique is implemented. Power quality improvement with comparison is conducted during fault with proportional integral (PI) and artificial intelligence-based fuzzy logic controlled DVR. MPPT tracks the actual variable DC link voltage while deriving the maximum power from a photovoltaic array and maintains DC link voltage constant by changing modulation index of the converter. Simulation results during fault show that the fuzzy logic based DVR scheme demonstrates simultaneous exchange of active and reactive power with less total harmonic distortion (THD) present in voltage source converter (VSC) current and grid current with fast tracking of optimum operating point at unity power factor. Standards (IEEE-519/1547), stipulates that the current with THD greater than 5% cannot be injected into the grid by any distributed generation source. Simulation results and validations of MPPT technique and operation of fuzzy logic controlled DVR demonstrate the effectiveness of the proposed control schemes.

关键词： fuzzy logic maximum power point tracking (MPPT) proportional integral (PI) control voltage restorer

Power quality investigation of a solar PV transformer-less grid- connected system fed DVR

Akhil GUPTA,Saurabh CHANANA,Tilak THAKUR

《能源前沿（英文）》
2014年
第8卷
第2期
页码 240-253
*doi:*
*10.1007/s11708-014-0322-x*

摘要：
This paper presents a single stage transformer-less grid-connected solar photovoltaic (PV) system with an active and reactive power control. In the absence of active input power, the grid-tied voltage source converter (VSC) is operated in a reactive power generation mode, which powers the control circuitry, and maintains a regulated DC voltage to the VSC. A data-based maximum power point tracking (MPPT) control scheme which performs power quality control at a maximum power by reducing the total harmonic distortion (THD) in grid injected current as per IEEE-519/1547 standards is implemented. A proportional-integral (PI) controller based dynamic voltage restorer (DVR) control scheme is implemented which controls the grid side converter during single-phase to ground fault. The analysis includes the grid current THD along with the corresponding variation of the active and reactive power during the fault condition. The MPPT tracks the actual variable DC link voltage while deriving the maximum power from the solar PV array, and maintains the DC link voltage constant by changing the modulation index of the VSC. Simulation results using Matlab/Simulink are presented to demonstrate the feasibility and validations of the proposed novel MPPT and DVR control systems under different environmental conditions.

关键词： data-based maximum power point tracking (MPPT) total harmonic distortion (THD) proportional integral control voltage restorer pulse width modulation

Louar FATEH,Ouari AHMED,Omeiri AMAR,Djellad ABDELHAK,Bouras LAKHDAR

《能源前沿（英文）》
2016年
第10卷
第2期
页码 155-163
*doi:*
*10.1007/s11708-016-0410-1*

摘要：
The interest for the use of renewable energies has increased, because of the increasing concerns of the environmental problems. Among renewable energies, wind energy is now widely used. Wind turbines based on an asynchronous generator with a wound rotor present the inconvenience of requiring a system of rings and brooms and a multiplier, inferring significant costs of maintenance. To limit these inconveniences, certain manufacturers developed wind turbines based on synchronous machines with large number of pairs of poles coupled directly with the turbine, avoiding using the multiplier. If the generator is equipped with permanent magnets, the system of rings and brooms is eliminated. The control of the permanent magnet synchronous generator (PMSG) can be affected with the implementation of various techniques of control. This paper presented a new approach mainly based on the control strategy of power production system based on the PMSG. In fact, a mathematical model that simulates the Matlab chain was established with the introduction of control techniques, such as direct control of the torque (DTC) to control the load side converter (LSC), the control of the speed of the turbine and the DC-bus voltage ensured by PI regulators. To show the performance of the correctors used, some simulation results of the system were presented and analyzed.

关键词： wind turbine permanent magnet synchronous generator (PMSG) converter proportional-integral (PI) control direct control of the torque (DTC) regulation

刘德盛,张群

《中国工程科学》 2000年 第2卷 第2期 页码 68-73

摘要：

目前我国海带养殖面积约1.5万hm^{2}，年产干品27t，占世界海藻总产量的50%。三十烷醇（TA）乳粉可显著提高海带的产量和品质，海带苗经2mg/L TA浸泡2h后放养，能促进假根生长，提高保苗率，增加叶绿素、岩藻黄素含量，促进碳、氮代谢，增加干物质积累。处理比对照平均增收干品6.57t/hm^{2},增产率为35%。同时，海带可比对照增收碘24.24kg/hm^{2}、褐藻胶1.665t/hm^{2}、甘露醇1.278t/hm^{2}。TA乳粉属国内外首创，具有无毒、高效、成本低、不变质及贮运方便等优点，已在全国海带上推广1.6万hm^{2},创经济效益3亿多元。

基于多模型融合驱动的锂离子动力电池荷电状态和容量联合估计研究 Article

熊瑞, 王榘, Weixiang Shen, 田金鹏, 穆浩

《工程（英文）》
2021年
第7卷
第10期
页码 1471-1484
*doi:*
*10.1016/j.eng.2020.10.022*

摘要：

锂离子动力电池（LIB）已成为各种电动载运工具的首选电源系统，包括电动汽车、电动轮船、电动火车和电动飞机。在全气候全寿命周期运行的电动载运工具中，锂离子电池的能量管理需要实时准确估计电池的荷电状态（SOC）和容量。本文提出了一种多阶段模型融合算法可协同估计SOC和容量。首先，基于正态分布假设，利用模型在不同老化状态下的残差均值和方差计算权重，建立参数稳定的融合模型。其次，将具有预测性的微分增益引入比例-积分观测器（PIO）以提高收敛速度。再次，将多阶段融合模型与比例-积分-微分观测器（PIDO）结合，建立了一种融合算法，可实现复杂应用环境下SOC和容量的协同估计。然后，讨论了融合算法的收敛性和抗噪性能。最后，搭建硬件在环平台，验证了融合算法的性能。不同老化状态和温度下的验证结果表明，融合算法可以实现SOC和容量的高精度协同估计，误差分别在2%和3.3%以内。

关键词： 荷电状态 容量估计 模型融合 比例-积分-微分观测器 硬件在环

Fibroblast growth factor 21: a novel metabolic regulator from pharmacology to physiology

null

《医学前沿（英文）》
2013年
第7卷
第1期
页码 25-30
*doi:*
*10.1007/s11684-013-0244-8*

摘要：

Fibroblast growth factor 21 (FGF21) is a member of the fibroblast growth factor family. It actually functions as endocrine hormones but does not regulate cell growth and differentiation. It is demonstrated that FGF21 acts on multiple tissue to coordinate carbohydrate and lipid metabolism, including enhancing insulin sensitivity, decreasing triglyceride concentrations, causing weight loss, ameliorating obesity-associated hyperglycemia and hyperlipidemia. Moreover, FGF21 also plays important roles in some physiological processes, such as fasting and feeding, growth hormone axis and thermogenic function of brown adipose tissue. Clinical relevance of FGF21 in humans is still unclear, and the basis and consequences of increased FGF21 in metabolic disease remain to be determined. Both the pharmacological actions and physiological roles make FGF21 attractive drug candidates for treating metabolic disease, but some questions remain to be answered. This article concentrates on recent advances in our understanding of FGF21.

关键词： FGF21 metabolism pharmacology physiology clinical relevance

Development of a novel two-stage proportional valve with a pilot digital flow distribution

Qiang GAO, Yuchuan ZHU, Changwen WU, Yulei JIANG

《机械工程前沿（英文）》
2021年
第16卷
第2期
页码 420-434
*doi:*
*10.1007/s11465-020-0622-2*

摘要：
Pilot two-stage proportional valves are widely used in high-power hydraulic systems. For the purpose of improving the dynamic performance, reliability, and digitization of the traditional proportional valve, a novel two-stage proportional valve with a pilot digital flow distribution is proposed from the viewpoint of the dual nozzle-flapper valve’s working principle. In particular, the dual nozzle-flapper is decoupled by two high-speed on/off valves (HSVs). First, the working principle and mathematical model of the proposed valve are determined. Then, the influences of the control parameters (duty cycle and switching frequency) and structural parameters (fixed orifice’s diameter and main valve’s spring) on the main valve’s motion are analyzed on the basis of theory, simulation, and experiment. In addition, in optimizing the value of the fixed orifice’s diameter, a new design criterion that considers the maximum pressure sensitivity, flow controllability, and flow linearization is proposed to improve the balance between the effective displacement and the displacement fluctuation of the main valve. The new scheme is verified by simulations and experiments. Experimental results of the closed-loop displacement tracking have demonstrated that the delay time of the main valve is always within 3.5 ms under different working conditions, and the tracking error can be significantly reduced using the higher switching frequency. The amplitude–frequency experiments indicate that a ‒3 dB-frequency of the proposed valve can reach 9.5 Hz in the case of±50% full scale and 15 Hz in the case of 0%–50% full scale. The values can be further improved by increasing the flow rate of the pilot HSV.

关键词： two-stage proportional valve digital flow distribution high-speed on/off valve position tracking characteristic dynamic performance

Autoimmune regulator regulates autophagy in THP-1 human monocytes

Liang SHI, Li-Hua HU, Yi-Rong LI

《医学前沿（英文）》
2010年
第4卷
第3期
页码 336-341
*doi:*
*10.1007/s11684-010-0096-4*

摘要：
The autoimmune regulator (AIRE) is a crucial factor for the induction of central tolerance, and mutations in this gene lead to abnormal immune responses. However, the role of AIRE in autophagy in immune cells, especially in monocytes, is obscure. In the present study, we found that overexpression of AIRE in THP-1 human monocytes resulted in increased endogenous light chain 3 (LC3)-II level and elevated LC3 positive vesicles. Moreover, an autophagy inhibitor or knockdown of AIRE by small interference RNA attenuated these effects. In contrast, the expression of p62/SQSTM1 remained unchanged in THP-1 cells after the corresponding treatment. Our findings indicate that AIRE plays a role in the regulation of autophagy in THP-1 human monocytes.

关键词： autoimmune regulator autophagy monocytes light chain 3 (LC3)

标题 作者 时间 类型 操作

Multiple target implementation for a doubly fed induction generator based on direct power control under unbalanced and distorted grid voltage

Heng NIAN,Yi-peng SONG

期刊论文

High-bandwidth nanopositioning via active control of system resonance

Linlin LI, Sumeet S. APHALE, Limin ZHU

期刊论文

Stability and coupling dynamic behavior of nonlinear journal active electromagnetic bearing rotor system

LU Yanjun, HEI Di, WANG Yuan, DAI Rong, LU Yanjun, LIU Heng, YU Lie

期刊论文

Proportional directional valve based automatic steering system for tractors

Jin-yi LIU,Jing-quan TAN,En-rong MAO,Zheng-he SONG,Zhong-xiang ZHU

期刊论文

Convergence performance comparisons of PID, MRAC, and PID+MRAC hybrid controller

Dan ZHANG,Bin WEI

期刊论文

High-precision gyro-stabilized control of a gear-driven platform with a floating gear tension device

期刊论文

THD reduction with reactive power compensation for fuzzy logic DVR based solar PV grid connected system

Akhil GUPTA,Saurabh CHANANA,Tilak THAKUR

期刊论文

Power quality investigation of a solar PV transformer-less grid- connected system fed DVR

Akhil GUPTA,Saurabh CHANANA,Tilak THAKUR

期刊论文

Modeling and control of a permanent magnet synchronous generator dedicated to standalone wind energy conversion system

Louar FATEH,Ouari AHMED,Omeiri AMAR,Djellad ABDELHAK,Bouras LAKHDAR

期刊论文

Development of a novel two-stage proportional valve with a pilot digital flow distribution

Qiang GAO, Yuchuan ZHU, Changwen WU, Yulei JIANG

期刊论文