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A new and best approach for early detection of rotor and stator faults in induction motors coupled to

Abderrahim ALLAL,Boukhemis CHETATE

《能源前沿（英文）》 2016年 第10卷 第2期   页码 176-191 doi: 10.1007/s11708-015-0386-2

摘要： Today, induction machines are playing, thanks to their robustness, an important role in world industries. Although they are quite reliable, they have become the target of various types of defects. Thus, for a long time, many research laboratories have been focusing their works on the theme of diagnosis in order to find the most efficient technique to predict a fault in an early stage and to avoid an unplanned stopping in the chain of production and costs ensuing. In this paper, an approach called Park’s vector product approach (PVPA) was proposed which was endowed with a dominant sensitivity in the case in which there would be rotor or stator faults. To show its high sensitivity, it was compared with the classical methods such as motor current signature analysis (MCSA) and techniques studied in recent publications such as motor square current signature analysis (MSCSA), Park’s vector square modulus (PVSM) and Park-Hilbert (P-H) (PVSM ). The proposed technique was based on three main steps. First, the three-phase currents of the induction motor led to a Park’s vector. Secondly, the proposed PVPA was calculated to show the distinguishing spectral signatures of each default and specific frequencies. Finally, simulation and experimental results were presented to confirm the theoretical assumptions.

关键词： induction motor     incipient broken bar     extended Park’s vector approach     spectral analysis     inter-turn short-circuit     Hilbert transform    

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Induction motors variable speed drives diagnosis through rotor resistance monitoring

YAHIA, S. ZOUZOU, F. BENCHABANE

《能源前沿（英文）》 2012年 第6卷 第4期   页码 420-426 doi: 10.1007/s11708-012-0192-z

摘要： Induction motor driven by vector control method makes high performance control of torque and speed possible. The decoupling of flux and electromagnetic torque obtained by field orientation depends on the precision and the accuracy of the estimated states. Rotor asymmetries lead to perturbations of air gap flux patterns in induction machines. These perturbations in flux components affect the electromagnetic torque, as well as stator currents and voltages. This paper first investigates the control of the induction motor using an extended Kalman filter (EKF) for a direct field-oriented control. It then studies the broken rotor bars (BRBs) fault by the monitoring the rotor resistance. The hypothesis on which the detection is based is that the apparent rotor resistance of the motor will increase when a rotor bar breaks. The rotor resistance is estimated and compared with its nominal value to detect BRBs fault. The EKF estimates the rotor flux, speed and rotor resistance on line by using only measurements of the stator voltages and currents. Simulation results show the effectiveness of the proposed method in the cases of load torque perturbation and speed reversion.

关键词： induction motor     vector control     broken rotor bars (BRBs) diagnostic     extended Kalman filter (EKF)    

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A modified neural learning algorithm for online rotor resistance estimation in vector controlled induction

CHITRA,S. HIMAVATHI

《能源前沿（英文）》 2015年 第9卷 第1期   页码 22-30 doi: 10.1007/s11708-014-0339-1

摘要： Online estimation of rotor resistance is essential for high performance vector controlled drives. In this paper, a novel modified neural algorithm has been identified for the online estimation of rotor resistance. Neural based estimators are now receiving active consideration as they have a number of advantages over conventional techniques. The training algorithm of the neural network determines its learning speed, stability, weight convergence, accuracy of estimation, speed of tracking and ease of implementation. In this paper, the neural estimator has been studied with conventional and proposed learning algorithms. The sensitivity of the rotor resistance change has been tested for a wide range of variation from -50% to+50% on the stability of the drive system with and without estimator. It is quiet appealing to settle with optimal estimation time and error for the viable realization. The study is conducted extensively for estimation and tracking. The proposed learning algorithm is found to exhibit good estimation and tracking capabilities. Besides, it reduces computational complexity and, hence, more feasible for practical digital implementation.

关键词： neural networks     back propagation (BP)     rotor resistance estimators     vector control     induction motor    

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An extended thermo-mechanically coupled algorithm for simulation of superelasticity and shape memory

S. HASHEMI,H. AHMADIAN,S. MOHAMMADI

《结构与土木工程前沿（英文）》 2015年 第9卷 第4期   页码 466-477 doi: 10.1007/s11709-015-0300-3

摘要： Thermo-mechanical coupling in shape memory alloys is a very complicated phenomenon. The heat generation/absorption during forward/reverse transformation can lead to temperature-dependent variation of its mechanical behavior in the forms of superelasticity and shape memory effect. However, unlike the usual assumption, slow loading rate cannot guarantee an isothermal process. A two-dimensional thermo-mechanically coupled algorithm is proposed based on the original model of Lagoudas to efficiently model both superelasticity and shape memory effects and the influence of various strain rates, aspect ratios and boundary conditions. To implement the coupled model into a finite element code, a numerical staggered algorithm is employed. A number of simulations are performed to verify the proposed approach with available experimental and numerical data and to assess its efficiency in solving complex SMA problems.

关键词： shape memory alloy     thermo-mechanical coupling     superplasticity     shape memory effect    

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Uncertainty propagation analysis by an extended sparse grid technique

S. WANG, M. H. PING

《机械工程前沿（英文）》 2019年 第14卷 第1期   页码 33-46 doi: 10.1007/s11465-018-0514-x

摘要： In this paper, an uncertainty propagation analysis method is developed based on an extended sparse grid technique and maximum entropy principle, aiming at improving the solving accuracy of the high-order moments and hence the fitting accuracy of the probability density function (PDF) of the system response. The proposed method incorporates the extended Gauss integration into the uncertainty propagation analysis. Moreover, assisted by the Rosenblatt transformation, the various types of extended integration points are transformed into the extended Gauss-Hermite integration points, which makes the method suitable for any type of continuous distribution. Subsequently, within the sparse grid numerical integration framework, the statistical moments of the system response are obtained based on the transformed points. Furthermore, based on the maximum entropy principle, the obtained first four-order statistical moments are used to fit the PDF of the system response. Finally, three numerical examples are investigated to demonstrate the effectiveness of the proposed method, which includes two mathematical problems with explicit expressions and an engineering application with a black-box model.

关键词： uncertainty propagation analysis     extended sparse grid     maximum entropy principle     extended Gauss integration     Rosenblatt transformation     high-order moments analysis    

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LSSVM-based approach for refining soil failure criteria and calculating safety factor of slopes

Shiguo XIAO; Shaohong LI

《结构与土木工程前沿（英文）》 2022年 第16卷 第7期   页码 871-881 doi: 10.1007/s11709-022-0863-8

摘要： The failure criteria of practical soil mass are very complex, and have significant influence on the safety factor of slope stability. The Coulomb strength criterion and the power-law failure criterion are classically simplified. Each one has limited applicability owing to the noticeable difference between calculated predictions and actual results in some cases. In the work reported here, an analysis method based on the least square support vector machine (LSSVM), a machine learning model, is purposefully provided to establish a complex nonlinear failure criterion via iteration computation based on strength test data of the soil, which is of more extensive applicability to many problems of slope stability. In particular, three evaluation indexes including coefficient of determination, mean absolute percentage error, and mean square error indicate that fitting precision of the machine learning-based failure criterion is better than those of the linear Coulomb criterion and nonlinear power-law criterion. Based on the proposed LSSVM approach to determine the failure criterion, the limit equilibrium method can be used to calculate the safety factor of three-dimensional slope stability. Analysis of results of the safety factor of two three-dimensional homogeneous slopes shows that the maximum relative errors between the proposed approach and the linear failure criterion-based method and the power-law failure criterion-based method are about 12% and 7%, respectively.

关键词： slope stability     safety factor     failure criterion     least square support vector machine    

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Governance approach to China’s environmental challenges: Towards a theoretical synthesis

QI Ye, XUE Lan, ZHANG Lingyun

《环境科学与工程前沿（英文）》 2007年 第1卷 第4期   页码 385-400 doi: 10.1007/s11783-007-0066-5

摘要： This paper reviewed recent research in environmental governance as a response to environmental challenges at various spatial, temporal and administrative scales. It documented the shift of approach from regulation to governance, and attempted to provide a comprehensive understanding why and how the transformation occurred. It also described major factors and forces of environmental governance, and discussed research advance in environmental governance theory. Finally, this paper summarized recent research findings on environmental governance in China, and listed policy recommendation for enhancing the governance.

关键词： environmental governance     approach     temporal     regulation     various    

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基于人工智能技术的无人机遥感探测具有感染松材线虫病特征的树木 Article

Mutiara Syifa, Sung-Jae Park, Chang-Wook Lee

《工程（英文）》 2020年 第6卷 第8期   页码 919-926 doi: 10.1016/j.eng.2020.07.001

摘要：

最近，松材线虫病（PWD）导致韩国大量的松树受损。鉴于松树对于韩国人的重要性，PWD被视为一个严重的问题，因此必须妥善处理这个问题。先前我们调查了PWD的历史，发现它已扩散到韩国的一些地区，这些成为了我们的研究领域。必须尽早对PWD进行检测。我们利用无人机遥感技术来探测具有与感染松材线虫病的树木相似症状的树木。之所以使用无人机遥感，是因为它能够生成高质量的图像，并且可以很容易地到达松树的位置。为了区别健康的和感染了PWD的松树，我们利用从Anbi和Wonchang两村采集到的无人机图像制作了一份土地覆盖图（LC），使用两种方法将它们分类，即人工神经网络（ANN）和支持向量机（SVM）。此外，比较了使用无人机和手持设备收集的两类全球定位系统（GPS）数据的准确性，以确定感染PWD的树木的位置。随后，我们将每个研究区域的无人机图像分成6个LC类，发现SVM在区分是否感染PWD的树木时比ANN更准确。在Anbi村，SVM的总体准确率为94.13%，与ANN总体准确率87.43%相比，高出了6.7%。在Wonchang村我们也得到了相似的结果，SVM和ANN的准确率分别为86.59%和79.33%。在GPS数据方面，我们使用了两种手持GPS设备。GPS设备1参照两个位置的基准点来校正，GPS设备2为未校正设备，仅使用GPS的默认设置。在Wonchang，手持GPS设备1采集的数据优于手持GPS设备2。然而，在Anbi，GPS设备2获得的结果优于GPS设备1获得的结果：GPS设备1的数据误差为7.08 m，而GPS设备2的数据误差为0.14 m。总的来说，这两种分类器都能根据LC数据辨别健康树木和患有PWD的树木。LC数据也可以用于其他类型的分类。这两个区域的手持GPS数据集和无人机GPS数据集存在一些差异。
 

关键词： 松材线虫病     无人机遥感     人工神经网络     支持向量机     全球定位系统    

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Current recommendations of managing HBV infection in preconception or pregnancy

null

《医学前沿（英文）》 2014年 第8卷 第2期   页码 158-165 doi: 10.1007/s11684-014-0340-4

摘要：

Hepatitis B remains a leading cause of cirrhosis, hepatocellular carcinoma and liver transplantation worldwide. Management of chronic hepatitis B during pregnancy is challenging. Transmission of hepatitis B to infants still occurs perinatally although immunoprophylaxis is widely available for infants born to mothers with chronic hepatitis B infection. The emerging data suggest that initiation of antiviral therapy in the beginning of the third trimester in highly viremic mothers can prevent immunoprophylaxis failure in their infants. The available drug safety data show that lamivudine, telbivudine and tenofovir are generally safe to be used during the pregnancy. In order to minimize the fetal exposure to the antiviral medication, antiviral therapy during the pregnancy should be limited to a selected group of patients with cirrhosis, high hepatitis B viral load, or prior history immunoprophylaxis failure. An elective Caesarean section may reduce the risk of perinatal transmission. For those females planning for pregnancy or in early stage of pregnancy, communication and follow-up among obstetrician, gastroenterologist, and primary care physician are important. In this article, we will review the features of hepatitis B infection before, during and after the pregnancy; the risk factors that increase mother-to-child transmission; safety data on antiviral drug use during pregnancy; and the potential role of Caesarean section in selected cases.

关键词： antiviral therapy     Caesarean section     cirrhosis     hepatitis B     immunoprophylaxis     mother-to-child transmission     pregnancy     prevention    

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Dynamic characteristics analysis of active constrained layer damping plate with various boundary conditions

Jing LU, Yu XIANG, Qiao NI

《机械工程前沿（英文）》 2011年 第6卷 第4期   页码 449-455 doi: 10.1007/s11465-011-0240-0

摘要：

Considering the direct and converse piezoelectric effect, expressions of piezoelectric membrane internal forces in the piezoelectric constrained layer were given. The control equations of the piezoelectric constrained layer and host plate were obtained in according with the thin plate theory. Based on the layer wised principle, the integrated first order differential equation of an active constrained layer damping (ACLD) plate was derived for the simply supported boundary condition. Then, this method was expanded to the ACLD plate with cantilever boundary condition by virtue of geometric analogy method. Employing the extended homogeneous capacity precision integration approach, a high precision semi-analytical method was proposed to analyze the dynamic characteristics of the ACLD plate with various boundary conditions. The comparison with the literature results has verified the accuracy and effectiveness of the present method.

关键词： active constrained layer damping (ACLD) plate     dynamic characteristics     semi-analytical method     extended homogeneous capacity precision integration approach    

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A novel approach for remanufacturing process planning considering uncertain and fuzzy information

《机械工程前沿（英文）》 2021年 第16卷 第3期   页码 546-558 doi: 10.1007/s11465-021-0639-1

摘要： Remanufacturing, as one of the optimal disposals of end-of-life products, can bring tremendous economic and ecological benefits. Remanufacturing process planning is facing an immense challenge due to uncertainties and fuzziness of recoverable products in damage conditions and remanufacturing quality requirements. Although researchers have studied the influence of uncertainties on remanufacturing process planning, very few of them comprehensively studied the interactions among damage conditions and quality requirements that involve uncertain, fuzzy information. Hence, this challenge in the context of uncertain, fuzzy information is undertaken in this paper, and a method for remanufacturing process planning is presented to maximize remanufacturing efficiency and minimize cost. In particular, the characteristics of uncertainties and fuzziness involved in the remanufacturing processes are explicitly analyzed. An optimization model is then developed to minimize remanufacturing time and cost. The solution is provided through an improved Takagi–Sugeno fuzzy neural network (T-S FNN) method. The effectiveness of the proposed approach is exemplified and elucidated by a case study. Results show that the training speed and accuracy of the improved T-S FNN method are 23.5% and 82.5% higher on average than those of the original method, respectively.

关键词： remanufacturing     uncertain and fuzzy information     process planning     T-S FNN    

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Optimization of WEDM process of pure titanium with multiple performance characteristics using Taguchi’sDOE approach and utility concept

Rupesh CHALISGAONKAR, Jatinder KUMAR

《机械工程前沿（英文）》 2013年 第8卷 第2期   页码 201-214 doi: 10.1007/s11465-013-0256-8

摘要：

This paper describes the development of multi response optimization technique using utility method to predict and select the optimal setting of machining parameters in wire electro-discharge machining (WEDM) process. The experimental studies in WEDM process were conducted under varying experimental conditions of process parameters, such as pulse on time(Ton), pulse off time(Toff), peak current (IP), wire feed (WF), wire tension (WT) and servo voltage (SV) using pure titanium as work material. Experiments were planned using Taguchi’s L27 orthogonal array. Multi response optimization was performed for both cutting speed (CS) and surface roughness (SR) using utility concept to find out the optimal process parameter setting. The level of significance of the machining parameters for their effect on the CS and SR was determined by using analysis of variance (ANOVA). Finally, confirmation experiment was performed to validate the effectiveness of the proposed optimal condition.

关键词： wire electro-discharge machining (WEDM)     Taguchi method     analysis of variance (ANOVA)     utility concept     cutting speed (CS)     surface roughness (SR)    

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Thermal response of steel framing members in open car park fires

Xia YAN; Marion CHARLIER; Thomas GERNAY

《结构与土木工程前沿（英文）》 2022年 第16卷 第9期   页码 1071-1088 doi: 10.1007/s11709-022-0879-0

摘要： For open car park structures, adopting a performance-based structural fire design is often justified and allowed because the fire does not reach flashover. However, this design approach requires an accurate assessment of temperatures in structural members exposed to car fires. This paper describes a numerical study on the thermal exposure on steel framing members in open car park fires. Steel temperatures are computed by the coupling of computational fluid dynamics and finite element modeling, and by analytical models from the Eurocodes. In addition, the influence of galvanization on the steel temperature evolution is assessed. Results show that temperatures in unprotected beams and columns are influenced by the section geometry, car fire scenario, modeling approach, and use of galvanization. Galvanization slightly delays and reduces peak temperature. Regarding the different models, CFD-FEM (CFD: computational fluid dynamics, FEM: finite-element method) coupled models predict lower temperatures than the Hasemi model, because the latter conservatively assumes that the fire flame continuously touches the ceiling. Further, the Hasemi model cannot account for the effect of reduced emissivity from galvanization on the absorbed heat flux. Detailed temperature distributions obtained in the steel members can be used to complete efficient structural fire designs based on the member sections, structure layout, and use of galvanization.

关键词： open car park     localized fire     steel frame     numerical modeling     computational fluid dynamics    

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Thermo-elastic extended meshfree method for fracture without crack tip enrichment

A. ASADPOUR

《结构与土木工程前沿（英文）》 2015年 第9卷 第4期   页码 441-447 doi: 10.1007/s11709-015-0319-5

摘要： This is the first manuscript presenting an extended meshfree method for thermo- elastic fracture which does not exploit a crack tip enrichment. The crack is modeled by partition of unity enrichment of the displacement and temperature field. Only a step function is employed that facilitates the implementation. To ensure that crack tip is at the correct position, a Lagrange multiplier field ahead of the crack tip is introduced along a line. The Lagrange multiplier nodal parameters are discretised with the available meshfree functions. Two benchmark examples illustrate the efficiency of the method.

关键词： meshfree method     thermo-elasticity    

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A Bayesian modeling approach to bi-directional pedestrian flows in carnival events

S. Q. XIE, S. C. WONG, William H. K. LAM

《工程管理前沿（英文）》 2017年 第4卷 第4期   页码 483-489 doi: 10.15302/J-FEM-2017023

摘要： Bi-directional pedestrian flows are common at crosswalks, footpaths, and shopping areas. However, the properties of pedestrian movement may vary in urban areas according to the type of walking facility. In recent years, crowd movements at carnival events have attracted the attention of researchers. In contrast to pedestrian behavior in other walking facilities, pedestrians whose attention is attracted by carnival displays or activities may slow down and even stop walking. The Lunar New Year Market is a traditional carnival event in Hong Kong held annually one week before the Lunar New Year. During the said event, crowd movements can be easily identified, particularly in Victoria Park, where the largest Lunar New Year Market in Hong Kong is hosted. In this study, we conducted a video-based observational survey to collect pedestrian flow and speed data at the Victoria Park Lunar New Year Market on the eve of the Lunar New Year. Using the collected data, an extant mathematical model was calibrated to capture the relationships between the relevant macroscopic quantities, thereby providing insight into pedestrian behavior at the carnival event. Bayesian inference was employed to calibrate the model by using prior data obtained from a previous controlled experiment. Results obtained enhance our understanding of crowd behavior under different conditions at carnival events, thus facilitating the improvement of the safety and efficiency of similar events in the future.

关键词： pedestrian flow model     bi-directional interactions     empirical studies     Bayesian inference    

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标题 作者 时间 类型 操作

A new and best approach for early detection of rotor and stator faults in induction motors coupled to

Abderrahim ALLAL,Boukhemis CHETATE

期刊论文

Induction motors variable speed drives diagnosis through rotor resistance monitoring

YAHIA, S. ZOUZOU, F. BENCHABANE

期刊论文

A modified neural learning algorithm for online rotor resistance estimation in vector controlled induction

CHITRA,S. HIMAVATHI

期刊论文

An extended thermo-mechanically coupled algorithm for simulation of superelasticity and shape memory

S. HASHEMI,H. AHMADIAN,S. MOHAMMADI

期刊论文

Uncertainty propagation analysis by an extended sparse grid technique

S. WANG, M. H. PING

期刊论文

LSSVM-based approach for refining soil failure criteria and calculating safety factor of slopes

Shiguo XIAO; Shaohong LI

期刊论文

Governance approach to China’s environmental challenges: Towards a theoretical synthesis

QI Ye, XUE Lan, ZHANG Lingyun

期刊论文

基于人工智能技术的无人机遥感探测具有感染松材线虫病特征的树木

Mutiara Syifa, Sung-Jae Park, Chang-Wook Lee

期刊论文

Current recommendations of managing HBV infection in preconception or pregnancy

null

期刊论文

Dynamic characteristics analysis of active constrained layer damping plate with various boundary conditions

Jing LU, Yu XIANG, Qiao NI

期刊论文

A novel approach for remanufacturing process planning considering uncertain and fuzzy information

期刊论文

Optimization of WEDM process of pure titanium with multiple performance characteristics using Taguchi’sDOE approach and utility concept

Rupesh CHALISGAONKAR, Jatinder KUMAR

期刊论文

Thermal response of steel framing members in open car park fires

Xia YAN; Marion CHARLIER; Thomas GERNAY

期刊论文

Thermo-elastic extended meshfree method for fracture without crack tip enrichment

A. ASADPOUR

期刊论文

A Bayesian modeling approach to bi-directional pedestrian flows in carnival events

S. Q. XIE, S. C. WONG, William H. K. LAM

期刊论文