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1. An Ensemble Learning Prognostic Method for Remaining Useful Life Prediction of Aircraft Engines | |||
Hongwei Liu,Qiang Wang | |||
Engineering and Technological Science 27 October 2020 | |||
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Abstract:Data-driven models have been widely used to predict the remaining useful life (RUL) of many engineering systems, e.g. aircraft engines. However, two shortcomings exist: (i) single algorithm has performance limitations for the specific application and (ii) reliably tracking the degraded performance of aircraft engines remains challenging. In this paper, a new ensemble learning prognostic method is proposed, which considers the effects of performance degradation on RUL. First, the overall degradation process is divided into multiple degradation stages, which present the performance of aircraft engines. Then, in each degradation stage, the higher prediction accuracy the base learner obtains, the higher weight is assigned to the base leaner. Finally, based on the obtained weights, the predicted results of all base learners are combined to predict the RUL of aircraft engines. The experimental results of aircraft engines verify the effectiveness and practical value of the proposed method. The results show that the proposed method has a good predictive effect and fits the degradation curve of the aircraft engines well. | |||
TO cite this article:Hongwei Liu,Qiang Wang. An Ensemble Learning Prognostic Method for Remaining Useful Life Prediction of Aircraft Engines[OL].[27 October 2020] http://en.paper.edu.cn/en_releasepaper/content/4752991 |
2. Rescheduling of Flexible Manufacturing Production Considering Uncertain Environment | |||
Zhang Yaping,Liao Wenzhu | |||
Engineering and Technological Science 29 April 2020 | |||
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Abstract:This paper establishes a centralized combined rescheduling model that combines machine failure, order changes, fuzzy processing time and machine maintenance. It discusses a rescheduling problem based on monitoring condition information for flexible manufacturing in an uncertain environment to maximize customer satisfaction and minimize production cost under the delivery time window. According to various conditions in an uncertain environment, a rescheduling strategy and a rescheduling method is provided. In the face of multiple factors and multiple goals, as it is difficult for traditional scheduling methods to obtain the optimal scheduling solution quickly, this paper proposes an improved Non-dominated Sorting Genetic Algorithm II (NSGA-II) algorithm combined with initialization rules. Then, the decision-making scheduling schemes are simulated and analyzed in 8 cases. The computational results show the feasibility and effectiveness of this rescheduling method, and could well support real production rescheduling problem. | |||
TO cite this article:Zhang Yaping,Liao Wenzhu. Rescheduling of Flexible Manufacturing Production Considering Uncertain Environment[OL].[29 April 2020] http://en.paper.edu.cn/en_releasepaper/content/4751832 |
3. A HYBRID-TYPE VIBRATION ENERGY HARVESTER | |||
HU Junhui,LIU Pengzhan | |||
Engineering and Technological Science 13 June 2016 | |||
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Abstract:In this paper, a novel hybrid-type vibration energy harvester utilizing electromagnetic induction and piezoelectricity has been presented. The device consists of one electromagnetic module and two piezoelectric modules. The electromagnetic induction module consists of two pairs of permanent magnets and one enameled copper coil. The two piezoelectric modules utilize the impact and impact-induced structural vibration, respectively.The apparent size of the device is 55mm (length)*35mm(width)*50mm(height). It was experimentally found that electrical power generated by the electromagnetic induction module is the maximum of the three modules, and total electrical power generated can be up to 0.23 mW when the device has a vibration amplitude of 4.5 mm and vibration frequency of 13 Hz. | |||
TO cite this article:HU Junhui,LIU Pengzhan. A HYBRID-TYPE VIBRATION ENERGY HARVESTER[OL].[13 June 2016] http://en.paper.edu.cn/en_releasepaper/content/4697908 |
4. FEM-Source Integral Boundary Conditions for Computation of the Open-Boundary Electrostatic Fields | |||
LI Shiqiong,WANG Zezhong | |||
Engineering and Technological Science 08 March 2014 | |||
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Abstract:This paper extends a method to solve the unbounded electrostatic fields. The method is based on the evaluation of the potential on some fictitious boundaries enclosing each part of the conductors and dielectrics, according to the charge lying on their surface, or the dipole lying in the dielectrics volume. The major advantage of this method lies in its high efficiency of computing the electrostatic field in which sources and materials spread out at a relatively long distance.????? | |||
TO cite this article:LI Shiqiong,WANG Zezhong. FEM-Source Integral Boundary Conditions for Computation of the Open-Boundary Electrostatic Fields[OL].[ 8 March 2014] http://en.paper.edu.cn/en_releasepaper/content/4588008 |
5. Edge preserving filtering of micro-structured surfaces | |||
ZHANG Xiangchao,Xu Min | |||
Engineering and Technological Science 28 May 2013 | |||
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Abstract:Micro optical elements are more and more widely used in precision engineering. Characterisation of the surface topography of these surfaces is very difficult due to the existence of sharp edges and complex features. The Gaussian filter will ruin the sharp features of structured surfaces. In this paper a Gaussian bilateral filter is developed. It uses two kernel functions. When implementing filtering, the weights of the neighbouring data points are assigned not only based on the spatial closeness, but also according to the signal similarity. Thus at the regions of sharp edges, large weighting values are assigned only to the data points that are similar to the current data values, and the sharp features can be preserved successfully. Numerical validations are presented to compare the behaviours of conventional Gaussian filter and the bilateral filter. The results demonstrated that the developed Gaussian bilateral filter shows remarkable superiority on filtering non-smooth micro-structured surfaces. | |||
TO cite this article:ZHANG Xiangchao,Xu Min. Edge preserving filtering of micro-structured surfaces[OL].[28 May 2013] http://en.paper.edu.cn/en_releasepaper/content/4545572 |
6. Low-temperature growth of highly c-oriented GaN films on Ag substrates with ECR-PEMOCVD | |||
WANG Shuai,QIN Fuwen | |||
Engineering and Technological Science 01 April 2013 | |||
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Abstract:Highly-preferred GaN films are deposited on Ag prepared on siliconchip substrates using the electron cyclotron resonance plasma enhanced metal organic chemical vapor deposition (ECR-PEMOCVD). Trimethylgallium (TMGa) and N2 are employed as the source of Ga and N, respectively, and high purity H2 is used as carrier gas. The effect of deposition temperature on the as-grown GaN films is systematically investigated by in-situ reflection high energy electron diffraction(RHEED), x-ray diffraction(XRD) and scanning electron microscope(SEM). The results show that high-quality GaN films with high preferred orientation and smooth surface were successfully achieved on Ag at the proper deposition temperature of 485℃. | |||
TO cite this article:WANG Shuai,QIN Fuwen. Low-temperature growth of highly c-oriented GaN films on Ag substrates with ECR-PEMOCVD[OL].[ 1 April 2013] http://en.paper.edu.cn/en_releasepaper/content/4531543 |
7. Modeling rockfall process using numerical manifold method and discontinuous deformation analysis | |||
Ning Youjun,An Xinmei,Lü Qing,Ma Guowei | |||
Engineering and Technological Science 24 December 2012 | |||
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Abstract:The recently developed numerical manifold method (NMM) provides a promising technology for modeling whole rockfall process, involving opening/sliding of pre-existing discontinuities, fracturing in intact rock bridges to form persistent failure surfaces and subsequent motions of the generated rock blocks. However, the NMM suffers one limitation, i.e., unexpected material domain area change occurs in rotation modelling. This problem cannot be easily solved because the rigid body rotation is not represented explicitly in NMM. The discontinuous deformation analysis (DDA) is specially developed for modeling discrete block systems. The rotation-induced material area change in DDA models can be avoided conveniently since the rigid body rotation is represented in an explicit form. In this paper, a transition technique is proposed and implemented to convert a NMM model to a DDA model so as to simulate whole rockfall process entirely by means of above two methods, in which NMM is adopted to model the early fracturing as well as the transition from continua to discontinua, while DDA is adopted to model the subsequent motion of the generated rock blocks. Such a numerical approach also improves the simulation efficiency greatly compared with a single NMM approach. The fracturing of a rock slab with pre-existing non-persistent joints located on a slope crest and the induced rockfall process are simulated. The validity of the modeling transition from NMM to DDA is verified and the applicability of the proposed numerical approach is illustrated. | |||
TO cite this article:Ning Youjun,An Xinmei,Lü Qing, et al. Modeling rockfall process using numerical manifold method and discontinuous deformation analysis[OL].[24 December 2012] http://en.paper.edu.cn/en_releasepaper/content/4505044 |
8. Correction Factors of the Mindlin Plate Equations with the Consideration of Electrodes | |||
Du Jianke,CHEN Guijia,WANG Wenjun,WU Rongxing,MA Tingfeng,WANG Ji | |||
Engineering and Technological Science 09 April 2012 | |||
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Abstract:The Mindlin plate theory has been playing a role vital in the analysis of high frequency vibrations of quartz crystal resonators at the thickness-shear mode. The coupled equations with infinite number of vibration modes have been truncated to retain essential ones with strong couplings for simplified analysis, and correction factors have been introduced to ensure exact solutions at cut-off frequencies as part of the validation procedure. Starting form plates without complications, correction factors have also been modified to include electrodes for their mass effect. Such results have been important to higher-order correction factors to ensure accurate consideration of electrodes in the AT-cut quartz crystal plates. The findings in factors systematic study are readily available for the analytical equations with selected modes with strong couplings, and equally convenient for the implementation of the finite element analysis with the Mindlin plate equations. | |||
TO cite this article:Du Jianke,CHEN Guijia,WANG Wenjun, et al. Correction Factors of the Mindlin Plate Equations with the Consideration of Electrodes[OL].[ 9 April 2012] http://en.paper.edu.cn/en_releasepaper/content/4474774 |
9. Study and Realization of SVPWM Algorithm on Two -level Converter | |||
Wang Zheng,Liu Meng | |||
Engineering and Technological Science 11 September 2010 | |||
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Abstract:Inverter is one of the main components of a power system, and SVPWM algorithm is the key part. The principle and algorithm of SVPWM are introduced. The scheme can easily determine the location of the reference vector and calculate the on-times. It uses the corresponding switching sequence to generate gating signals for the inverter. On this basis, the simulation model with the Matlab / simulink as platform was established. Simulation results is consistent with the theoretical analysis. | |||
TO cite this article:Wang Zheng,Liu Meng. Study and Realization of SVPWM Algorithm on Two -level Converter[OL].[11 September 2010] http://en.paper.edu.cn/en_releasepaper/content/4385352 |
10. Effects of Symmetry and Number of Compositional Elements on Chinese Users’ Aesthetic Ratings of Interfaces | |||
Luzheng Bi,Xinan Fan,Guixin Zhang,Yili Liu,Zhilong Chen | |||
Engineering and Technological Science 24 March 2009 | |||
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Abstract:This paper investigates the effects of symmetry and number of compositional elements on interface aesthetics rating of Chinese users with abstract black-and-white geometric images as experimental stimuli. The two independent variables each has three levels. The dependent variable is subjective ratings of aesthetic appeal. The experimental results show that symmetry of compositional elements significantly affects aesthetic ratings of Chinese users, whereas neither the number of compositional elements nor gender has a significant effect on aesthetic ratings. The difference between the present results and the results from previous studies with American users and some possible explanations of the results are discussed. | |||
TO cite this article:Luzheng Bi,Xinan Fan,Guixin Zhang, et al. Effects of Symmetry and Number of Compositional Elements on Chinese Users’ Aesthetic Ratings of Interfaces[OL].[24 March 2009] http://en.paper.edu.cn/en_releasepaper/content/30637 |
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