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LED灯具温度应力加速老化截止时间的确定 Article

Jian HAO, Lei JING, Hong-liang KE, Yao WANG, Qun GAO, Xiao-xun WANG, Qiang SUN, Zhi-jun XU

《信息与电子工程前沿（英文）》 2017年 第18卷 第10期   页码 1678-1678 doi: 10.1631/FITEE.1500483

摘要： 在LED灯具加速老化过程中，为获得最小截止时间，对其寿命进行快速预估，本文采用5阶滑动平均误差方法分析数据。选用同批次的16个样本，分别进行80℃和85℃应力条件下的加速老化。首先，采用e指数对光通维持率进行拟合，获得每个灯具的加速寿命，进而采用威布尔分布对加速寿命进行拟合，获得中位寿命。其次，采用平均滑动误差方法，可获取不同截止时间下中位寿命预估误差。结果表明：加速老化过程中，存在最小截止时间，该时间可通过滑动平均误差和截止时间的关系确定；当截止时间小于该值时，寿命预估不合理；寿命预估误差随截止时间增加而逐渐减小。对于该类LED灯具，80℃时最小截止时间为1104小时，寿命预估误差为1.15%；85℃时最小截止时间为936小时，寿命预估误差为1.24%。当寿命估计误差约为0.46％时，80 ℃和85 ℃对应的中位寿命分别为7310小时和4598小时。

关键词： LED灯具；加速老化测试；中位寿命；滑动平均误差    

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Erratum to: Determination of cut-off time of accelerated aging test under temperature stress for LED lamps

Jian Hao, Lei Jing, Hong-liang Ke, Yao Wang, Qun Gao, Xiao-xun Wang, Qiang Sun, Zhi-jun Xu,sunq@ciomp.ac.cn

《信息与电子工程前沿（英文）》 2017年 第18卷 第10期   页码 1678-1678 doi: 10.1631/FITEE.15e0483

摘要： Erratum to: , 2017 18(8):1197-1204. doi:

关键词： LED lamp     Accelerated aging test     Medium lifetime     Moving average error    

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Topicmodeling for large-scale text data

Xi-ming LI,Ji-hong OUYANG

《信息与电子工程前沿（英文）》 2015年 第16卷 第6期   页码 457-465 doi: 10.1631/FITEE.1400352

摘要： This paper develops a novel online algorithm, namely moving average stochastic variational inference (MASVI), which applies the results obtained by previous iterations to smooth out noisy natural gradients. We analyze the convergence property of the proposed algorithm and conduct a set of experiments on two large-scale collections that contain millions of documents. Experimental results indicate that in contrast to algorithms named ‘stochastic variational inference’ and ‘SGRLD’, our algorithm achieves a faster convergence rate and better performance.

关键词： Latent Dirichlet allocation (LDA)     Topic modeling     Online learning     Moving average    

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Performance prediction of switched reluctance generator with time average and small signal models

Jyoti KOUJALAGI, B. UMAMAHESWARI, R. ARUMUGAM

《能源前沿（英文）》 2013年 第7卷 第1期   页码 56-68 doi: 10.1007/s11708-012-0216-8

摘要： This paper presents the complete mathematical model and predicts the performance of switched reluctance generator with time average and small signal models. The complete mathematical model is developed in three stages. First, a switching model is developed based on quasi-linear inductance profile. Next, based on the switching behaviour, a time average model is obtained to measure the difference between the excitation and generation time in each switching cycle. Finally, to track control voltage and current wave shapes, a small signal model is designed. The effectiveness of the complete multilevel model combining electrical machine, power converter, load and control with programming language is demonstrated through simulations. A PI controller is used for controlling the voltage of the generator. The results presented show that the controller exhibits accurate tracking control of load voltage under different operating conditions. This demonstrates that the proposed model is able to perform an accurate control of the generated output voltage even in transient situations. The simulation is performed to choose the control parameters and study the performance of switched reluctance generator prior to its actual implementation. Initial experimental results are presented using NI-Data acquisition card to control the output power according to load requirements.

关键词： generator     reluctance     switching model     small signal model     time average model    

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Vibration analysis of a simply supported beam under moving mass based on moving finite element method

Zhuchao YE, Huaihai CHEN,

《机械工程前沿（英文）》 2009年 第4卷 第4期   页码 397-400 doi: 10.1007/s11465-009-0044-7

摘要： In this paper, a moving finite element (MFE) method is proposed to perform the dynamic analysis of a simply supported beam for a moving mass (MM). The MFE method treats the moving mass as a moving part of the entire system, so that the transverse inertial effects caused by the moving mass may easily be taken into account. The solution to the beam’s dynamic behaviors including its displacement is obtained via a Newmark-β method; the effects of the velocity and weight of the MM on the beam’s dynamic behaviors are further discussed. The numerical examples show that the inertial effects of the MM significantly affect the transverse responses of the simply supported beam.

关键词： simply supported beam     moving mass (MM)     transverse vibration     moving finite element (MFE)    

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Chord error constraint based integrated control strategy for contour error compensation

Tie ZHANG, Caicheng WU, Yanbiao ZOU

《机械工程前沿（英文）》 2020年 第15卷 第4期   页码 645-658 doi: 10.1007/s11465-020-0601-7

摘要： As the traditional cross-coupling control method cannot meet the requirements for tracking accuracy and contour control accuracy in large curvature positions, an integrated control strategy of cross-coupling contour error compensation based on chord error constraint, which consists of a cross-coupling controller and an improved position error compensator, is proposed. To reduce the contour error, a PI-type cross-coupling controller is designed, with its stability being analyzed by using the contour error transfer function. Moreover, a feed rate regulator based on the chord error constraint is proposed, which performs speed planning with the maximum feed rate allowed by the large curvature position as the constraint condition, so as to meet the requirements of large curvature positions for the chord error. Besides, an improved position error compensation method is further presented by combining the feed rate regulator with the position error compensator, which improves the tracking accuracy via the advance compensation of tracking error. The biaxial experimental results of non-uniform rational B-splines curves indicate that the proposed integrated control strategy can significantly improve the tracking and contour control accuracy in biaxial contour following tasks.

关键词： cross-coupling controller     contour error     tracking error     position error compensator     feed rate regulator    

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Dynamic prediction of moving trajectory in pipe jacking: GRU-based deep learning framework

《结构与土木工程前沿（英文）》   页码 994-1010 doi: 10.1007/s11709-023-0942-5

摘要： The moving trajectory of the pipe-jacking machine (PJM), which primarily determines the end quality of jacked tunnels, must be controlled strictly during the entire jacking process. Developing prediction models to support drivers in performing rectifications in advance can effectively avoid considerable trajectory deviations from the designed jacking axis. Hence, a gated recurrent unit (GRU)-based deep learning framework is proposed herein to dynamically predict the moving trajectory of the PJM. In this framework, operational data are first extracted from a data acquisition system; subsequently, they are preprocessed and used to establish GRU-based multivariate multistep-ahead direct prediction models. To verify the performance of the proposed framework, a case study of a large pipe-jacking project in Shanghai and comparisons with other conventional models (i.e., long short-term memory (LSTM) network and recurrent neural network (RNN)) are conducted. In addition, the effects of the activation function and input time-step length on the prediction performance of the proposed framework are investigated and discussed. The results show that the proposed framework can dynamically and precisely predict the PJM moving trajectory during the pipe-jacking process, with a minimum mean absolute error and root mean squared error (RMSE) of 0.1904 and 0.5011 mm, respectively. The RMSE of the GRU-based models is lower than those of the LSTM- and RNN-based models by 21.46% and 46.40% at the maximum, respectively. The proposed framework is expected to provide an effective decision support for moving trajectory control and serve as a foundation for the application of deep learning in the automatic control of pipe jacking.

关键词： dynamic prediction     moving trajectory     pipe jacking     GRU     deep learning    

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Design and analysis of the gripper mechanism based on generalized parallel mechanisms with configurable moving

《机械工程前沿（英文）》 2021年 第16卷 第4期   页码 765-781 doi: 10.1007/s11465-021-0655-1

摘要： Generalized parallel mechanisms with a configurable moving platform have become popular in the research field of parallel mechanism. This type of gripper mechanism can be applied to grasp large or heavy objects in different environments that are dangerous and complex for humans. This study proposes a family of novel (5 + 1) degrees of freedom (three translations and two rotations plus an additional grasping motion) gripper mechanisms based on the generalized parallel mechanisms with a configurable moving platform. First, the configurable moving platform, which is a closed loop, is designed for grasping manipulation. The hybrid topological arrangement is determined to improve the stiffness of the manipulator and realize high load-to-weight ratios. A sufficient rule based on Lie group theory is proposed to synthesize the mechanism. The hybrid limb structure is also enumerated. A family of novel gripper mechanisms can be assembled through the hybrid limbs by satisfying the rule. Two examples of the gripper mechanisms with and without parallelogram pairs are shown in this study. A kinematic analysis of the example mechanism is presented. The workspace shows that the mechanism possesses high rotational capability. In addition, a stiffness analysis is performed.

关键词： generalized parallel mechanism     configurable moving platform     gripper mechanism     type synthesis     kinematic analysis    

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Multi-harmonic forced vibration and resonance of simple beams to moving vehicles

《结构与土木工程前沿（英文）》   页码 981-993 doi: 10.1007/s11709-023-0979-5

摘要： This study modeled the moving-vehicle-induced forcing excitation on a single-span prismatic bridge as a multiple frequency-multiplication harmonic load on the modal coordinates of a linear elastic simple Euler–Bernoulli beam, and investigated the forced modal oscillation and resonance behavior of this type of dynamic system. The forced modal responses consist of multiple frequency-multiplication steady-state harmonics and one damped mono-frequency complementary harmonic. The analysis revealed that a moving load induces high-harmonic forced resonance amplification when the moving speed is low. To verify the occurrence of high-harmonic forced resonance, numerical tests were conducted on single-span simple beams based on structural modeling using the finite element method (FEM) and a moving sprung-mass oscillator vehicle model. The forced resonance amplification characteristics of the fundamental mode for beam response estimation are presented with consideration to different end restraint conditions. The results reveal that the high-harmonic forced resonance may be significant for the investigated beams subjected to vehicle loads moving at specific low speeds. For the investigated single-span simple beams, the moving vehicle carriage heaving oscillation modulates the beam modal frequency, but does not induce notable variation of the modal oscillation harmonic structure for the cases that vehicle of small mass moves in low speed.

关键词： forced vibration     linear Euler beam     moving load     harmonic structure     frequency modulation     end restraints    

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A case study on sample average approximation method for stochastic supply chain network design problem

Yuan WANG, Ruyan SHOU, Loo Hay LEE, Ek Peng CHEW

《工程管理前沿（英文）》 2017年 第4卷 第3期   页码 338-347 doi: 10.15302/J-FEM-2017032

摘要： This study aims to solve a typical long-term strategic decision problem on supply chain network design with consideration to uncertain demands. Existing methods for these problems are either deterministic or limited in scale. We analyze the impact of uncertainty on demand based on actual large data from industrial companies. Deterministic equivalent model with nonanticipativity constraints, branch-and-fix coordination, sample average approximation (SAA) with Bayesian bootstrap, and Latin hypercube sampling were adopted to analyze stochastic demands. A computational study of supply chain network with front-ends in Europe and back-ends in Asia is presented to highlight the importance of stochastic factors in these problems and the efficiency of our proposed solution approach.

关键词： supply chain network     stochastic demand     sampling average approximation     Bayesian bootstrap     Latin hypercube sampling    

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Experimental study on average movement characteristics of bed-load particles

Limo TANG, Xingkui WANG,

《结构与土木工程前沿（英文）》 2009年 第3卷 第4期   页码 435-439 doi: 10.1007/s11709-009-0050-1

摘要： The three-dimensional movements of bed-load particles in an open channel with different grain diameters and different specific gravities under the conditions of different hydraulic gradient are measured by means of particle tracking velocimetry (PTV) technique. The average movement characteristics of the particles are analyzed by statistics. The results show that the longitudinal average velocities of the particles neither agree with the law suggested by Einstein nor obey the law assumed by Bagnold. Einstein’s law is that the particle velocity is equal to 11.6 times of shear velocity, and the Bagnold’s law assumes the velocity equal to the difference between flow velocity at corresponding water depth and settling velocity of particle. Two formulas for determining the velocity of particle in the forms of expression given by Einstein and Bagnold are obtained according to the statistical results of experimental data, respectively.

关键词： different     longitudinal     three-dimensional     particle     Bagnold    

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灵活可变的运动图像的分割算法

赵彦玲,张之超,高振,张庆超

《中国工程科学》 2006年 第8卷 第5期   页码 84-87

摘要：

运动图像的分割在基于内容的视频编码及视频检索中占有重要的地位。利用运动图像帧中的时空域信息，提出了一种分割运动对象的方法。其最大的特点是灵活性，可以根据序列的实际情况来选择算法。实验证明分割效果较好并节省了处理时间。

关键词： 时空结合     运动区域     运动对象     形态梯度算子     灵活性    

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Kinematic error separation on five-axis NC machine tool based on telescoping double ball bar

Min WANG, Jianzhong HU, Tao ZAN

《机械工程前沿（英文）》 2010年 第5卷 第4期   页码 431-437 doi: 10.1007/s11465-010-0110-1

摘要： The theory and algorithm of the homogeneous transformation matrix (HTM) method are applied in establishing the kinematic error model of five-axis machining tool with two-axis turntable. Based on this model, a new method for the kinematic error separation in five-axis numerical control (NC) machining tool is proposed. In this study, three types of simultaneous three-axis control motions are designed for each rotary axis to identify the deviations. In the measurement, two translational axes and one rotary axis are simultaneously controlled to keep a constant distance between the tool and the worktable. Telescoping double ball bar is used to measure the relative distance between the spindle and the worktable in the motion of NC machining tool. Finally, the value measured by telescoping double ball bar is substituted into the model to obtain kinematic error of NC machining tool. Comparison has confirmed that the proposed method is high precision and can be applied to effectively and conveniently measure the five-axis machining tool.

关键词： error modeling     error separation     telescoping double ball bar     five-axis numerical control (NC) machining tool    

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Effects of carrier-attached biofilm on oxygen transfer efficiency in a moving bed biofilm reactor

Yanling WEI,Xunfei YIN,Lu QI,Hongchen WANG,Yiwei GONG,Yaqian LUO

《环境科学与工程前沿（英文）》 2016年 第10卷 第3期   页码 569-577 doi: 10.1007/s11783-015-0822-x

摘要： Three laboratory-scale moving bed biofilm reactors (MBBR) with different carrier filling ratios ranging from 40% to 60% were used to study the effects of carrier-attached biofilm on oxygen transfer efficiency. In this study, we evaluated the performance of three MBBRs in degrading chemical oxygen demand and ammonia. The three reactors removed more than 95% of -N at an air flow-rate of 60 L·h . The standard oxygen transfer efficiency (αSOTE) of the three reactors was also investigated at air flow-rates ranging from 60 to 100 L·h . These results were compared to αSOTE of wastewater with a clean carrier (no biofilm attached). Results showed that under these process conditions, αSOTE decreased by approximately 70% as compared to αSOTE of wastewater at a different carrier-filling ratio. This indicated that the biofilm attached to the carrier had a negative effect on αSOTE. Mechanism analysis showed that the main inhibiting effects were related to biofilm flocculants and soluble microbial product (SMP). Biofilm flocs could decrease αSOTE by about 20%, and SMP could decrease αSOTE by 30%–50%.

关键词： carrier     biofilm     oxygen transfer efficiency     moving bed biofilm reactor    

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Robust ensemble of metamodels based on the hybrid error measure

《机械工程前沿（英文）》 2021年 第16卷 第3期   页码 623-634 doi: 10.1007/s11465-021-0641-7

摘要： Metamodels have been widely used as an alternative for expensive physical experiments or complex, time-consuming computational simulations to provide a fast but accurate analysis. However, challenge remains in the prior determination of the most suitable metamodel for a particular case because of the lack of information about the actual behavior of a system. In addition, existing studies on metamodels have largely restricted on solving deterministic problems (e.g., data from finite element models), whereas some real-life engineering problems (e.g., data from physical experiment) are stochastic problems with noisy data. In this work, a robust ensemble of metamodels (EMs) is proposed by combining three regression stand-alone metamodels in a weighted sum form. The weight factor is adaptively determined according to the hybrid error metric, which combines global and local error measures to improve the accuracy of the EMs. Furthermore, three typical individual metamodels that can filter noise are selected to construct the EMs to extend their application in practical engineering problems. Three well-known benchmark problems with different levels of noise and three engineering problems are used to verify the effectiveness of the proposed EMs. Results show that the proposed EMs have higher accuracy and robustness than the individual metamodels and other typical EMs in major cases.

关键词： metamodel     ensemble of metamodels     hybrid error measure     stochastic problem    

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标题 作者 时间 类型 操作

LED灯具温度应力加速老化截止时间的确定

Jian HAO, Lei JING, Hong-liang KE, Yao WANG, Qun GAO, Xiao-xun WANG, Qiang SUN, Zhi-jun XU

期刊论文

Erratum to: Determination of cut-off time of accelerated aging test under temperature stress for LED lamps

Jian Hao, Lei Jing, Hong-liang Ke, Yao Wang, Qun Gao, Xiao-xun Wang, Qiang Sun, Zhi-jun Xu,sunq@ciomp.ac.cn

期刊论文

Topicmodeling for large-scale text data

Xi-ming LI,Ji-hong OUYANG

期刊论文

Performance prediction of switched reluctance generator with time average and small signal models

Jyoti KOUJALAGI, B. UMAMAHESWARI, R. ARUMUGAM

期刊论文

Vibration analysis of a simply supported beam under moving mass based on moving finite element method

Zhuchao YE, Huaihai CHEN,

期刊论文

Chord error constraint based integrated control strategy for contour error compensation

Tie ZHANG, Caicheng WU, Yanbiao ZOU

期刊论文

Dynamic prediction of moving trajectory in pipe jacking: GRU-based deep learning framework

期刊论文

Design and analysis of the gripper mechanism based on generalized parallel mechanisms with configurable moving

期刊论文

Multi-harmonic forced vibration and resonance of simple beams to moving vehicles

期刊论文

A case study on sample average approximation method for stochastic supply chain network design problem

Yuan WANG, Ruyan SHOU, Loo Hay LEE, Ek Peng CHEW

期刊论文

Experimental study on average movement characteristics of bed-load particles

Limo TANG, Xingkui WANG,

期刊论文

灵活可变的运动图像的分割算法

赵彦玲,张之超,高振,张庆超

期刊论文

Kinematic error separation on five-axis NC machine tool based on telescoping double ball bar

Min WANG, Jianzhong HU, Tao ZAN

期刊论文

Effects of carrier-attached biofilm on oxygen transfer efficiency in a moving bed biofilm reactor

Yanling WEI,Xunfei YIN,Lu QI,Hongchen WANG,Yiwei GONG,Yaqian LUO

期刊论文

Robust ensemble of metamodels based on the hybrid error measure

期刊论文