An Improved Model Predictive Direct Speed Control with Synchronous Prediction and Weight Factor Optimization for PMSM Application

Chen Zhangyong,Xiao Fangbo,Chen Yong,Tang Weihan,Chen Zhiyuan 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.6

In permanent magnet synchronous motor (PMSM) application, model predictive direct speed control is usually utilized to eliminate cascade loop structure existed in traditional vector control. However, asynchronous prediction equation (ASPE) with one-step delay is mostly required to achieve optimal voltage vector to drive the PMSM motors, which exist the problem of asynchronous prediction of speed and current. It is shown that in this paper the synchronous prediction equation (SPE) does not have the prediction delay, but it cannot realize the speed tracking control. Aim to solve the above problems, an improved PMSM model predictive direct speed control with synchronous prediction and Weight factor optimization is proposed in this paper. Firstly, the Taylor synchronization prediction equation (TSPE) is used to realize the speed and current prediction synchronization and the speed tracking control. Secondly, in order to improve the response speed of the system, a quadratic cost function considering the weight factor optimization is used for cost evaluation, and the Lyapunov direct method is used to design the weight factor with taking into account the stability and rapidity of the system. Finally, in order to verify the effectiveness of the proposed method, the MATLAB simulation and hardware-in-the-loop experiments are carried out. The results show that the proposed control method achieves predictive synchronous between speed and current, fast and stable speed tracking control, and the setting time is faster than the ASPE, and the TSPE without considering the weight factor.

Weak fault detection method of rolling bearing based on testing signal far away from fault source

Zhiyuan He,Guo Chen,Tengfei Hao,Chunyu Teng,Minli Hou,Zhenjie Chen 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.3

In some cases, because of the complex internal structure of the machines, the positions of the vibration sensors are far away from the rolling bearings, such as in an aeroengine, causing the fault features to become extremely weak, which brings great challenge to the detection of rolling bearings. To address this problem, an integrated detection method is proposed. First, a method named MEDL is proposed to determine the optimal filter length in minimum entropy deconvolution (MED) to enhance the periodic fault impulse component in the weak signal, which accuracy is 1. After that, the MEDL is combined with variational mode decomposition (VMD) and autocorrelation to extract fault features from strong background noise. A series of fault simulation experiments for rolling bearings were conducted by using an aeroengine rotor experimental rig with casing. The results verify that the accuracy of the integrated detection method is 100 % in different measuring points, speeds and fault types. At the same time, it compared with spectral kurtosis (SK) and empirical wavelet transform (EWT). It proves that the integrated detection method is more robust in extracting the weak fault characteristic of rolling bearings from the casing signals effectively.

Clone refactoring inspection by summarizing clone refactorings and detecting inconsistent changes during software evolution : Clone refactoring inspection by summarizing clone refactorings and detecting inconsistent changes during software evolution

Chen, Zhiyuan,Kwon, Young-Woo,Song, Myoungkyu Wiley Blackwell (John Wiley Sons) 2018 Journal of software Vol.30 No.10

Network-level Optimization of Bus Stop Placement in Urban Areas

Jingxu Chen,Shuaian Wang,Zhiyuan Liu,Xuewu Chen 대한토목학회 2018 KSCE Journal of Civil Engineering Vol.22 No.4

Bus stops provide accessibility to public transit service, whereas they also influence the efficiency of mobility due to the extradwell time. The decision of bus stop locations is a tradeoff between access coverage and mobility. This paper formulates a biobjectiveoptimization model of bus stop placement problem at the network level. Two objectives are pertinent to the improvement ofmobility: minimization of total dwell time at stops and minimization of total number of bus stops. Access coverage is constrained toensure a certain level of accessibility. The issue of stop congestion and its effect on road traffic flow is also considered in the model. The model is applied to a case study of the bus network in urban areas of Yancheng, China. The results show that the proposed modelcan be efficiently solved by CPLEX to obtain Pareto optimal solutions for real-case problems.

Тhe use of aluminium and magnesium alloys in automotive lightweight technologies

Zhiyuan Hao,Yao Ju,Lingxiang Chen 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.9

This paper presents comparative characteristics of the aluminum and magnesium alloys in the context of their utilization in the metallurgical and automotive industry. The studies carried out in our work help to solve the problem of reducing the weight of automotive devices to reduce fuel consumption through the use of aluminum-magnesium alloys. The originality of our article lies in a comprehensive study of the stated problem: development of a research methodology, testing of the alloys under study for uniaxial tension, quantitative analysis of the Portevin-Le Chatelier effect, development of a mathematical model for optimizing parts, computer simulation of the viscoplastic properties of a model sample. Analysis of the obtained strength parameters demonstrates that the flow characteristics of the two-phase alloy of aluminum and magnesium exceed the ultimate tensile strength by 50 %. Rate of extension was inversely proportional to the intensity of the Portevin-Le Chatelier effect.

In Situ Fabrication of TiO2/Bi3.64Mo0.36O6.55 Nanocomposite with High Visible-Light-Driven Photocatalytic Efficiency

Zhiyuan Yang,Junjie Wang,Lu Chen,Mengjun Liang,Yulin Xu,Chentao Zou,Xiaoxia Liu,Shuijin Yang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2017 NANO Vol.12 No.5

In this work, we developed a simple hydrothermal method toward the fabrication of TiO2/ Bi3.64Mo0.36O6.55 heterostructure, which had superior photocatalytic performance for degrading of RhB under visible light irradiation. The as-prepared samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), high-resolution transmission electron microscopy (HRTEM), UV-Vis diffuse reflectance spectroscopy (DRS) and photoelectrochemical measurements. The optimal composite with 15 wt.% TiO2/Bi3.64Mo0.36O6.55 (TBMO3) exhibits a much higher photocatalytic activity than that of Bi3.64Mo0.36O6.55 and P25 by degradation of RhB under visible light irradiation within 20 min. The enhanced performance of TBMO3 is predominantly attributed to the synergistic effect both in the higher surface area and the improved separation of photogenerated charge carriers between the two semiconductors. Recycling experiments indicated that TiO2/Bi3.64Mo0.36O6.55 photocatalysts had excellent cycle performance and stability. The photocatalytic mechanism of nanocomposite photocatalysts was proposed, which is confirmed by the active species trapping experiments and photoluminescence tests.

Genetic Diversity and Population Structure of the Xanthomonas campestris pv. campestris Strains Affecting Cabbages in China Revealed by MLST and Rep-PCR Based Genotyping

Guo Chen,Congcong Kong,Limei Yang,Mu Zhuang,Yangyong Zhang,Yong Wang,Jialei Ji,Zhiyuan Fang,Honghao Lv 한국식물병리학회 2021 Plant Pathology Journal Vol.37 No.5

Xanthomonas campestris pv. campestris (Xcc) is the causal agent of black rot for cruciferous vegetables worldwide, especially for the cole crops such as cabbage and cauliflower. Due to the lack of resistant cabbage cultivars, black rot has brought about considerable yield losses in recent years in China. Understanding of the pathogen features is a key step for disease prevention, however, the pathogen diversity, population structure, and virulence are largely unknown. In this study, we studied 50 Xcc strains including 39 Xcc isolates collected from cabbage in 20 regions across China, us- ing multilocus sequence genotyping (MLST), repetitive DNA sequence-based PCR (rep-PCR), and pathogenicity tests. For MLST analysis, a total of 12 allelic profiles (AP) were generated, among which the largest AP was AP1 containing 32 strains. Further cluster analysis of rep-PCR divided all strains into 14 DNA groups, with the largest group DNA I comprising of 34 strains, most of which also belonged to AP1. Inoculation tests showed that the representative Xcc strains collected from diverse regions performed differential virulence against three brassica hosts compared with races 1 and 4. Interestingly, these results indicated that AP1/DNA I was not only the main pathotype in China, but also a novel group that differed from the previously reported type races in both genotype and virulence. To our knowledge, this is the first extensive genetic diversity survey for Xcc strains in China, which provides evidence for cabbage resistance breeding and opens the gate for further cabbage-Xcc interaction studies.

Micromechanical investigation for the probabilistic behavior of unsaturated concrete

Qing Chen,Zhiyuan Zhu,Fang Liu,Haoxin Li,Zhengwu Jiang 사단법인 한국계산역학회 2020 Computers and Concrete, An International Journal Vol.26 No.2

There is an inherent randomness for concrete microstructure even with the same manufacturing process. Meanwhile, the concrete material under the aqueous environment is usually not fully saturated by water. This study aimed to develop a stochastic micromechanical framework to investigate the probabilistic behavior of the unsaturated concrete from microscale level. The material is represented as a multiphase composite composed of the water, the pores and the intrinsic concrete (made up by the mortar, the coarse aggregates and their interfaces). The differential scheme based two-level micromechanical homogenization scheme is presented to quantitatively predict the concrete’s effective properties. By modeling the volume fractions and properties of the constituents as stochastic, we extend the deterministic framework to stochastic to incorporate the material’s inherent randomness. Monte Carlo simulations are adopted to reach the different order moments of the effective properties. A distribution-free method is employed to get the unbiased probability density function based on the maximum entropy principle. Numerical examples including limited experimental validations, comparisons with existing micromechanical models, commonly used probability density functions and the direct Monte Carlo simulations indicate that the proposed models provide an accurate and computationally efficient framework in characterizing the material’s effective properties. Finally, the effects of the saturation degrees and the pore shapes on the concrete macroscopic probabilistic behaviors are investigated based on our proposed stochastic micromechanical framework.

Analysis on Self-breakdown Statistics Properties for a Spark Switch

Mo, Chen,Guofu, Li,Qinxiao, Dong,Zhifang, Liu,Zhiyuan, Li 대한전기학회 2014 The Journal of International Council on Electrical Vol.4 No.2

According to the working characteristics of over-voltage protective device for series compensation, the principle and structure of spark switch were introduced in this paper briefly. Special test loop and HV fast switch-off device were designed to evaluate the performance of spark swich in trials. Test data and mathematic statistic results revealed that the self-breakdown probability of spark switch obeyed the normal distribution and the cumulative distribution of spark switch self-breakdown had been less affected by different enviroment temperature. The number of trials was restricted to the characteristics of insulated gas and the electrode surface state in the practical application. Reasonable choice of test number can keep estimation error at a relatively low level, particularly for parameter estimation by using small sample of self-breakdown voltage. The conclusion is instructive to the development and engineering application of spark switch for over-voltage protective equipment of series compensation.

TGF-β1/IL-11/MEK/ERK signaling mediates senescence-associated pulmonary fibrosis in a stress-induced premature senescence model of Bmi-1 deficiency

Haiyun Chen,Jialong Liang,Xin Gu,Jiawen Zhou,Chunfeng Xie,Xianhui Lv,Rong Wang,Qing Liu,Zhiyuan Mao,Haijian Sun,Guoping Zuo,Dengshun Miao,Jianliang Jin 생화학분자생물학회 2020 Experimental and molecular medicine Vol.52 No.-

To study whether TGF-β1/IL-11/MEK/ERK (TIME) signaling mediates senescence-associated pulmonary fibrosis (SAPF) in Bmi-1-deficient (Bmi-1−/−) mice and determines the major downstream mediator of Bmi-1 and crosstalk between p16INK4a and reactive oxygen species that regulates SAPF, phenotypes were compared among 7-week-old p16INK4a and Bmi-1 double-knockout, N-acetylcysteine (NAC)-treated Bmi-1−/−, Bmi-1−/−, and wild-type mice. Pulmonary fibroblasts and alveolar type II epithelial (AT2) cells were used for experiments. Human pulmonary tissues were tested for type Ι collagen, α-smooth muscle actin (α-SMA), p16INK4a, p53, p21, and TIME signaling by using enzyme-linked immunosorbent assay (ELISA). Our results demonstrated that Bmi-1 deficiency resulted in a shortened lifespan, ventilatory resistance, poor ventilatory compliance, and SAPF, including cell senescence, DNA damage, a senescence-associated secretory phenotype and collagen overdeposition that was mediated by the upregulation of TIME signaling. The signaling stimulated cell senescence, senescence-related secretion of TGF-β1 and IL-11 and production of collagen 1 by pulmonary fibroblasts and the epithelial-to-mesenchymal transition of AT2 cells. These processes were inhibited by anti-IL-11 or the MEK inhibitor PD98059. NAC treatment prolonged the lifespan and ameliorated pulmonary dysfunction and SAPF by downregulating TIME signaling more than p16INK4a deletion by inhibiting oxidative stress and DNA damage and promoting ubiquitinproteasome degradation of p16INK4a and p53. Cytoplasmic p16INK4a accumulation upregulated MEK/ERK signaling by inhibiting the translocation of pERK1/2 (Thr202/Tyr204) from the cytoplasm to the nucleus in senescent fibroblasts. The accumulation of collagen 1 and α-SMA in human lungs accompanied by cell senescence may be mediated by TIME signaling. Thus, this signaling in aging fibroblasts or AT2 cells could be a therapeutic target for preventing SAPF.