Search | Engineering

订阅投稿

首页工程期刊工程焦点工程成就工程前沿关于我们 English

资源类型

期刊论文 180

会议视频 1

年份

2023 12

2022 9

2021 12

2020 6

2019 3

2018 14

2017 15

2016 5

2015 6

2014 10

2013 11

2012 7

2011 5

2010 3

2009 11

2008 15

2007 12

2006 6

2005 2

2004 3

展开︾

关键词

动力学 2

多输入多输出 2

CDMA 1

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

GPS 1

HeNe激光器 1

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

ISO 18186 1

KTP 1

LM331型电压-频率转换器 1

MLE） 1

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

PID控制 1

P波 1

QRS-T复合波 1

RLC网络；谐振性质；振荡特性；幅频特性 1

Visual Basic 6.0 1

WEM法 1

WiFi多频天线 1

展开︾

检索范围：

排序：展示方式：

Control of wind-induced vibration of long-span bridges and tall buildings

GU Ming

《结构与土木工程前沿（英文）》 2007年第1卷第1期页码 51-62 doi: 10.1007/s11709-007-0005-3

摘要： With the rapid increase in scales of structures, research on controlling wind-induced vibration of large-scale structures, such as long-span bridges and super-tall buildings, has been an issue of great concern. For wind-induced vibration of large-scale structures, vibration frequencies and damping modes vary with wind speed. Passive, semiactive, and active control strategies are developed to improve the wind-resistance performance of the structures in this paper. The multiple tuned mass damper (MTMD) system is applied to control vertical bending buffeting response. A new semiactive lever-type tuned mass damper (TMD) with an adjustable frequency is proposed to control vertical bending buffeting and torsional buffeting and flutter in the whole velocity range of bridge decks. A control strategy named sinusoidal reference strategy is developed for adaptive control of wind-induced vibration of super-tall buildings. Multiple degrees of freedom general building aeroelastic model with a square cross-section is tested in a wind tunnel. The results demonstrate that the proposed strategies can reduce vibration effectively, and can adapt to wind-induced vibration control of large-scale structures in the uncertain dynamic circumstance.

关键词： torsional buffeting large-scale semiactive adjustable frequency building aeroelastic

HTML PDF 收藏

Impact drive rotary precision actuator with piezoelectric bimorphs

ZHANG Hongzhuang, ZENG Ping, HUA Shunming, CHENG Guangming, YANG Zhigang

《机械工程前沿（英文）》 2008年第3卷第1期页码 71-75 doi: 10.1007/s11465-008-0008-3

摘要： An impact drive rotary precision actuator with end-loaded piezoelectric cantilever bimorphs is proposed. According to finite element analysis and experiments of the dynamic characteristics of end-loaded piezoelectric cantilever bimorphs, a specific fixed-frequency and adjustable-amplitude is confirmed to control the actuator. The results show that an actuator excited by fixed-frequency and the adjustable-amplitude ramp voltage waveform works with a large travel range (180°), high resolution (1 ?rad), speed (0.2 rad/min) and heavy-load ability (0.02 Nm). With advantages of high-precision positioning ability, simple structure and only one percent the cost of traditional impact drive mechanisms, the actuator is expected to be widely used in precision industries.

关键词： specific fixed-frequency waveform piezoelectric cantilever mechanisms adjustable-amplitude

HTML PDF 收藏

Characteristics of force acting on adjustable axial flow pump blade

WEI Peiru, CHEN Hongxun, LU Wei

《能源前沿（英文）》 2008年第2卷第4期页码 508-513 doi: 10.1007/s11708-008-0054-x

摘要： The internal three-dimensional turbulent flow of adjustable axial-flow pump arrangement was simulated, and the force acting on the blade surface was calculated under different operating conditions. Based on the calculated results, finite element method (FEM) was adopted to analyze stress and strain distributions of the adjustment blade in different operations. Hydraulic moment, centrifugal moment and friction moment which must be conquered by adjusting the blades were also calculated.

关键词： three-dimensional adjustable axial-flow calculated FEM centrifugal

HTML PDF 收藏

Restoration of hyper-eutrophic water with a modularized and air adjustable constructed submerged plant

Jinzhong LI, Xueju LI, Shujuan SUN, Xuegong LIU, Suiliang HUANG

《环境科学与工程前沿（英文）》 2011年第5卷第4期页码 573-584 doi: 10.1007/s11783-011-0363-x

摘要： A modularized and air adjustable constructed submerged plant bed (CSPB) which can be used to restore the eutrophic water is introduced in this paper. This plant bed helps hydrophyte grow under poor conditions such as frequently changed water depth, impaired water transparency, algae bloom and substantial duckweed in summer, which are not naturally suitable for growing hydrophyte. This pilot study in Waihuan River of Tianjin, China, revealed that reduction of Chemical Oxygen Demand (COD), Total Nitrogen (TN) and Total Phosphorus (TP) by the use of CSPB could be reached 30%–35%, 35%–40%, 30%–40% respectively in the growing season (from March to October) and 5%–10%, 5%–15%, 7%–20% respectively in the winter (from November to February) when the detention time was 6 d. The relationships between the concentration of COD, TN, TP and the detention time fit the first-order kinetic equation well and the coefficients of determination ( ) were all above 0.9. The attenuation coefficients k of the kinetic equation were a function of the water temperature. When the water temperature was quite low or quite high, was not significantly changed with increasing or decreasing water temperature. While when the temperature was in a moderate range, an increase or decrease of water temperature would lead to a rapid increase or decrease in .

关键词： modularized and air adjustable constructed submerged plant bed water purification eco-restoration techniques aquatic plants eutrophication

HTML PDF 收藏

频率脉宽实时独立调节的脉冲种子源 Research Articles

杨志伟1,2,吴旭1,2,欧阳德钦2,张恩诚2,孙慧斌1,阮双琛1,2

《信息与电子工程前沿（英文）》 2021年第22卷第10期页码 1379-1389 doi: 10.1631/FITEE.2000294

摘要：研制了一套基于嵌入式芯片的半导体激光器脉冲种子源，光脉冲频率和脉宽能独立实时调节，可在线从增益开关模式切换到准连续运行模式，以实现特定应用所需最佳光参数。为探讨半导体激光光源物理机制，对描述半导体激光腔内光子载流子瞬态变化的速率方程进行数值模拟与分析。之后，确定在设计驱动电路时需要考虑的问题。系统性能评估结果表明，光脉冲频率调节范围是250 Hz至42 MHz，光脉冲输出最窄脉宽为80 ps。脉冲种子源可驱动不同中心波长(1064、1550和1970 nm)半导体激光器，并可同时驱动两台半导体激光器，输出双频光脉冲。该脉冲种子源可作为一般高功率光学系统种子源，具有良好应用价值和广阔市场前景。

关键词：电参数控制；电子设计自动化及方法；光脉冲产生；光控制

HTML PDF 收藏

Design and experimental study of a passive power-source-free stiffness-self-adjustable mechanism

Yuwang LIU, Dongqi WANG, Shangkui YANG, Jinguo LIU, Guangbo HAO

《机械工程前沿（英文）》 2021年第16卷第1期页码 32-45 doi: 10.1007/s11465-020-0604-4

摘要： Passive variable stiffness joints have unique advantages over active variable stiffness joints and are currently eliciting increased attention. Existing passive variable stiffness joints rely mainly on sensors and special control algorithms, resulting in a bandwidth-limited response speed of the joint. We propose a new passive power-source-free stiffness-self-adjustable mechanism that can be used as the elbow joint of a robot arm. The new mechanism does not require special stiffness regulating motors or sensors and can realize large-range self-adaptive adjustment of stiffness in a purely mechanical manner. The variable stiffness mechanism can automatically adjust joint stiffness in accordance with the magnitude of the payload, and this adjustment is a successful imitation of the stiffness adjustment characteristics of the human elbow. The response speed is high because sensors and control algorithms are not needed. The variable stiffness principle is explained, and the design of the variable stiffness mechanism is analyzed. A prototype is fabricated, and the associated hardware is set up to validate the analytical stiffness model and design experimentally.

关键词： variable stiffness mechanism stiffness self-regulation bionic robot modeling

HTML PDF 收藏

双级驱动半主动隔振系统的可调反共振频率控制器 Research Articles

赵勃1,2,史维佳1,2,王丙泉1,2,谭久彬1,2

《信息与电子工程前沿（英文）》 2021年第22卷第10期页码 1390-1401 doi: 10.1631/FITEE.2000373

摘要：在半导体制造业中，被控对象的动态模型通常是在运动控制前通过扫频方法获得。然而，现有隔离器不能很好隔离扫频时惯性力（频率在0 Hz和固有频率之间）对平台基座的干扰。本文提出一种用于双级驱动半主动隔振系统的可调反共振频率控制器。双级驱动半主动隔振系统具有显著的反共振特性，在一个特定频率——即所谓反共振频率——振幅可降至接近零。本控制器的设计目的是增加一个可调的控制器反共振频率，以充分利用这种独特的反共振特性。实验结果表明了本方案的可行性，闭环传递率从0 Hz到初始反共振频率小于−15 dB。此外，在附加反共振频率附近，闭环传递率小于−30 dB，可通过改变控制器参数实现附加反共振频率在0 Hz至初始反共振频率之间的调节。当平台基座受到脉冲扰动时，使用本文提出的控制器，有效载荷扰动幅度从4 mm/s衰减至0.5 mm/s，降低87.5%。同时，通过跟踪扫频干扰，系统可实时调整反共振频率点，获得良好隔振性能。这表明双级驱动半主动隔振系统和所提控制器可应用于保证超低振动环境，特别是在半导体制造业的扫频工作中。

关键词：半主动隔振；双级驱动；动态吸振；可调反共振频率控制器

HTML PDF 收藏

大中功率节能调速传动的合理电压等级

马小亮

《中国工程科学》 2001年第3卷第11期页码 80-84

摘要：

大中功率风机和泵采用变频调速可节约大量电能，大部分功率在0.2～2 MW范围中。我国现在200 kW以上的电机多是中压，现行中压电网多为10 kV，选用10 kV直接变频从技术和经济角度看都不太合理。由于变频器输入侧都有变压器，因此电机和变频器没有必要和电网一致。文章讨论不同功率段的合理电压等级以及在电机电压和电网电压不同情况下当变频器出现故障时如何实现旁路工作。

关键词：大中功率节能调速合理电压等级低压变频中压变频旁路

HTML PDF 收藏

New refrigeration system using CO vapor-solid as refrigerant

HUANG Dongping, DING Guoliang, QUACK Hans

《能源前沿（英文）》 2008年第2卷第4期页码 494-498 doi: 10.1007/s11708-008-0070-x

摘要： A refrigerant must be in the vapor-liquid phase in a vapor-compression refrigeration system, therefore, CO cannot be used as a refrigerant for temperatures lower than -56°C because solid CO will form under the triple point temperature of -56°C. A refrigeration system with CO vapor-solid particles as refrigerant is put forward, by which a temperature lower than the triple point is achieved. An adjustable nozzle, a sublimator, a high-pressure regulating valve and a low-pressure regulating valve are used to replace the conventional evaporator. Theoretical cycle analysis of the refrigeration system shows that its COP can be 50% higher than that of the conventional one.

关键词： refrigerant adjustable temperature vapor-compression refrigeration sublimator

HTML PDF 收藏

A frequency error estimation for isogeometric analysis of Kirchhoff–Love cylindrical shells

《结构与土木工程前沿（英文）》 doi: 10.1007/s11709-023-0006-x

摘要： A frequency error estimation is presented for the isogeometric free vibration analysis of Kirchhoff–Love cylindrical shells using both quadratic and cubic basis functions. By analyzing the discrete isogeometric equations with the aid of harmonic wave assumption, the frequency error measures are rationally derived for the quadratic and cubic formulations for Kirchhoff–Love cylindrical shells. In particular, the governing relationship of the continuum frequency for Kirchhoff–Love cylindrical shells is naturally embedded into the frequency error measures without the need of explicit frequency expressions, which usually are not trivial for the shell problems. In accordance with these theoretical findings, the 2nd and 4th orders of frequency accuracy are attained for the isogeometric schemes using quadratic and cubic basis functions, respectively. Numerical results not only thoroughly verify the theoretical convergence rates of frequency solutions, but also manifest an excellent magnitude match between numerical and theoretical frequency errors for the isogeometric free vibration analysis of Kirchhoff–Love cylindrical shells.

关键词： isogeometric analysis Kirchhoff–Love cylindrical shell free vibration frequency error convergence

HTML PDF 收藏

Calculation of collision frequency function for aerosol particles in free molecule regime in presence

Xiaowei LUO, Yannick BENICHOU, Suyuan YU

《能源前沿（英文）》 2013年第7卷第4期页码 506-510 doi: 10.1007/s11708-013-0275-5

摘要： The collision frequency function for aerosol particles has already been calculated for the free molecule regime and for the continuum range. The present work, taking into account the influence of internal force fields such as magnetic force, electric force and molecular forces, created by particles themselves, recalculated the collision frequency in the case of particles much smaller than the mean free path of the gas (free molecule regime). Attractive forces increase naturally the collision frequency, while repulsive forces decrease it. The calculation was performed for all types of central forces deriving from a potential, including Coulomb forces and Van der Waals forces.

关键词： aerosol particles collision frequency function coagulation

HTML PDF 收藏

Fuel variability effect on flickering frequency of diffusion flames

Jizhao LI, Yang ZHANG

《能源前沿（英文）》 2009年第3卷第2期页码 134-140 doi: 10.1007/s11708-009-0034-9

摘要： It is known that fuel variability of different gas suppliers may cause combustion instability in a gas turbine combustor. Mechanisms that control the time scale of the heat release oscillations and acoustic pressure perturbations are both physical and chemical in nature, and thus can be influenced by changes in fuel composition. The intent of this study is to investigate the fuel variability on the flickering frequency of diffusion flames in the hope of understanding some of the fundamental aspects of fuel variability effect on the dynamics of combustion. Experiments were conducted at atmospheric pressure with a matrix of methane and propane blends. An optical fibre system was applied to capture simultaneously the flame flickering at two different light frequencies (430 nm and 516 nm), which provided a means of comparing the chemistry change. It was found that the low frequency oscillation of flow and flame structures depended only weakly on the exit velocities of the fuel, while ambient conditions had a significant effect on flickering frequencies and spectrum. The results of using CH and C H as test fuels at different flow rates showed very little variations, with peak frequencies at 11-13 Hz. When the jet flame was not disturbed, harmonics to at least the third mode were obtained in most of these cases. However, the cases which included CH /C H splits of 90/10, 85/15 and 80/20 by volume showed that unstable flickering frequencies and flame harmonics were not observed. When a mixture of methane/propane at a ratio of 1:1 was used the peak flickering frequency was around 6 Hz, and slight disturbance in the environment would cause the harmonics to disappear. Mechanisms thought to produce changes in the dynamic response and frequency harmonics were discussed.

关键词： fuel variability flickering frequency diffusion flames dynamics of combustion

HTML PDF 收藏

Capacity limitation of nuclear units in grid based on analysis of frequency regulation

Yiping DAI, Pan JIANG, Lin GAO, Weimin KAN, Xiaoqing XIAO, Ge JIN

《能源前沿（英文）》 2012年第6卷第2期页码 148-154 doi: 10.1007/s11708-012-0174-1

摘要： The increasing capacity of nuclear units in power grid poses threat to system stability and security. Load disturbance may cause overspeed of the units and trigger the overspeed protection controller (OPC). Repeating actions of valves have a strong impact on the security of the equipment and may result in a collapse of the power system. Based on the analysis of frequency regulation, mathematic models for nuclear units in the grid are established in this paper to simulate the dynamic process when load disturbance occurs. The critical action of the OPC is proposed as the constraint of safe operation for the units. The relationship between different styles of frequency regulation and the allowable capacity of the nuclear units in the grid is discussed. This research can help to estimate the capacity limitation of nuclear units in the grid.

关键词： nuclear units capacity overspeed primary frequency control (PFC) second frequency control (SFC)

HTML PDF 收藏

Oscillation frequency of simplified arterial tubes

Hui AN, Fan HE, Lingxia XING, Xiaoyang LI

《机械工程前沿（英文）》 2009年第4卷第3期页码 300-304 doi: 10.1007/s11465-009-0038-5

摘要： To construct the spatial kinetic equation of an arterial tube and obtain its radial natural frequency, a linear-elastic and small deformation condition is assumed. The theoretical analysis is first presented and the finite element method is then used to numerically simulate the spatial kinematics. The results show that the first-order frequency is 15.8 Hz and the obtained exact analytical solutions agree well with numerical solutions, which proves that the theoretical analysis and numerical simulation are both correct.

关键词： spatial kinematics natural frequency finite element method

HTML PDF 收藏

Parameter identification of interconnected power system frequency after trip-out of high voltage transmission

Xuzhan ZHOU,Shanshan LIU,Mingkun WANG,Yiping DAI,Yaohua TANG

《能源前沿（英文）》 2014年第8卷第3期页码 386-393 doi: 10.1007/s11708-014-0323-9

摘要： Accurate modeling and parameters of high voltage (HV) grid are critical for stability research of system frequency. In this paper, simulation modeling of the system frequency was conducted of an interconnected power system with HV transmission lines in China. Based on recorded tripping data of the HV transmission lines, system parameters were identified by using genetic algorithm (GA). The favorable agreement between simulation results and recorded data verifies the validity of gird models and the accuracy of system parameters. The results of this paper can provide reference for the stability research of HV power grid.

关键词： high voltage (HV) grid frequency stability parameter identification primary frequency regulation (PFR)