A New Support Vector Machine Model Based on Improved Imperialist Competitive Algorithm for Fault Diagnosis of Oil-immersed Transformers

Yiyi Zhang,Hua Wei,Ruijin Liao,Youyuan Wang,Lijun Yang,Chunyu Yan 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.2

Support vector machine (SVM) is introduced as an effective fault diagnosis technique based on dissolved gases analysis (DGA) for oil-immersed transformers with maximum generalization ability; however, the applicability of the SVM is highly affected due to the difficulty of selecting the SVM parameters appropriately. Therefore, a novel approach combing SVM with improved imperialist competitive algorithm (IICA) for fault diagnosis of oil-immersed transformers was proposed in the paper. The improved ICA, which is proved to be an effective optimization approach, is employed to optimize the parameters of SVM. Cross validation and normalizations were applied in the training processes of SVM and the trained SVM model with the optimized parameters was established for fault diagnosis of oil-immersed transformers. Three classification benchmark sets were studied based on particle swarm optimization SVM (PSOSVM) and IICASVM with four multiple classification schemes to select the best scheme for transformer fault diagnosis. The results show that the proposed model can obtain higher diagnosis accuracy than other methods. The comparisons confirm that the proposed model is an effective approach for classification problems.

A New Support Vector Machine Model Based on Improved Imperialist Competitive Algorithm for Fault Diagnosis of Oil-immersed Transformers

Zhang, Yiyi,Wei, Hua,Liao, Ruijin,Wang, Youyuan,Yang, Lijun,Yan, Chunyu The Korean Institute of Electrical Engineers 2017 Journal of Electrical Engineering & Technology Vol.12 No.2

Support vector machine (SVM) is introduced as an effective fault diagnosis technique based on dissolved gases analysis (DGA) for oil-immersed transformers with maximum generalization ability; however, the applicability of the SVM is highly affected due to the difficulty of selecting the SVM parameters appropriately. Therefore, a novel approach combing SVM with improved imperialist competitive algorithm (IICA) for fault diagnosis of oil-immersed transformers was proposed in the paper. The improved ICA, which is proved to be an effective optimization approach, is employed to optimize the parameters of SVM. Cross validation and normalizations were applied in the training processes of SVM and the trained SVM model with the optimized parameters was established for fault diagnosis of oil-immersed transformers. Three classification benchmark sets were studied based on particle swarm optimization SVM (PSOSVM) and IICASVM with four multiple classification schemes to select the best scheme for transformer fault diagnosis. The results show that the proposed model can obtain higher diagnosis accuracy than other methods. The comparisons confirm that the proposed model is an effective approach for classification problems.

A Facile and Controllable Approach for Surface Modification of Wool by Micro-dissolution

Yiyi Zhang,Nan Zhang,Qiang Wang,Yuanyuan Yu,Ping Wang,Jiugang Yuan 한국섬유공학회 2020 Fibers and polymers Vol.21 No.6

Most modifications of wool focused on its surface due to the existence of the cuticle scales. For instance,chlorination, oxidation and protease treatments were used to break down or remove the scales. However, these modificationsusually severely damaged the internal structure of wool. In this paper, a novel approach based on surface micro-dissolutionwas employed to modify the surface of wool to minimize the internal damage of wool, and improve the surface-relatedproperties of wool. The micro-dissolution system used NaHSO3/urea to dissolve the scale layer of wool. After being microdissolvedwith NaHSO3/urea system, scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS),fluorescence microscopy, Fourier transform infrared spectroscopy (FTIR), and the Allwörden reaction were utilized tocharacterize the treated wool. Furthermore, felting shrinkage, strength loss and wettability of the treated wool weredetermined. The results showed that NaHSO3/urea system could dissolve the scale layer from outside to inside. Thefluorescence microscopic images further indicated that low concentration of NaHSO3/urea system can dissolve the surface ofwool without the serious damage of internal structure. Moreover, the micro-dissolution system can be controlled to dissolvethe scale layer on the surface of wool slightly by adjusting the reaction conditions. The presented method is simple, easy tooperate, and economical, thereby can open up new directions for the surface modification of wool.

Performance investigation of nanoscale thermal cloak by the perforated silicon film

Zhang Jian,Zhang Haochun,Zhang Dong,Sun Wenbo,Li Yiyi 한국물리학회 2022 Current Applied Physics Vol.35 No.-

In recent years, nanoscale thermal cloak, as a representative of nanoscale heat flux regulation devices, has attracted a lot of attention from researchers. However, the existing design methods are relatively complicated and all adopt constant temperature boundaries, the temperature changes constantly in the real environment, which greatly hinders its engineering applications. In this paper, inspired by phonon localization theory, we construct a nanoscale thermal cloak by a perforated silicon membrane and evaluate its cloaking performance and dynamic response. Results show that when the perforated area is fixed, the more the number of holes, the better the cloaking performance. In addition, the nanoscale thermal cloak still exhibits good cloaking performance in the dynamic environment. Finally, the cloaking mechanism is analyzed by calculating the phonon density of states (PDOS) and mode participation rate (MPR), and the reduction of thermal conductivity in the functional region is attributed to phonon localization.

Acinetobacter chinensis, a novel Acinetobacter species, carrying blaNDM-1, recovered from hospital sewage

Yiyi Hu,Yu Feng,Jiayuan Qin,Xiaoxia Zhang,Zhiyong Zong 한국미생물학회 2019 The journal of microbiology Vol.57 No.5

Two strains of the genus Acinetobacter, named WCHAc- 010005 and WCHAc010052, were isolated from hospital sewage at West China Hospital in Chengdu, China. The two strains were found to be resistant to carbapenems due to the presence of carbapenemase gene blaNDM-1. Based on the comparative analysis of the rpoB sequence, the two strains formed a strongly supported and internally coherent cluster (intracluster identity of 98.7%), which was clearly separated from all known Acinetobacter species (≤ 83.4%). The two strains also formed a tight and distinct cluster based on the genuswide comparison of whole-cell mass fingerprints generated by MALDI-TOF mass spectrometry. In addition, the combination of their ability to assimilate malonate but not benzoate, and the inability to grow at 37°C could distinguish the two strains from all known Acinetobacter species. The two strains were subjected to whole genome sequencing using both short-read Illumina HiSeq2500 platform and the longread MinION sequencer. The average nucleotide identity and in silico DNA-DNA hybridization value between the genomes of WCHAc010005 and WCHAc010052 was 96.69% and 74.3% respectively, whereas those between the two genomes and the known Acinetobacter species were < 80% and < 30%, respectively. Therefore, the two strains represent a novel species of the genus Acinetobacter, for which the name Acinetobacter chinensis sp. nov. is proposed, and the type strain is WCHAc- 010005T (= GDMCC 1.1232T = KCTC 62813T).

Management strategy for Spodoptera frugiperda (Lepidoptera:Noctuidae) in mountain maize planting areas in China

Yao Yao,He Yanyan,Zhang Lilan,Wang Kun,Li Bin,Du Guangzu,Zhu Chunyue,Yi Xiaocui,Liu Yiyi,Zi Shengjiang,Chen Bin,Xiao Guanli 한국응용곤충학회 2023 Journal of Asia-Pacific Entomology Vol.26 No.4

The fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae), is a major maize pest worldwide and has caused huge economic loss. To explore the control tactics of S. frugiperda in mountain maize planting fields, studies were performed in China from 2020 to 2021 for screening the S. frugiperda-resistant maize variety, seed coating agents, chemical insecticides, and biological agents. The results showed that 75 g/hm 2 Emamectin benzoate had better controlling efficacy (with a control efficacy of 91.05% at 1d) than other chemicals, so it was recommended in the high incidence period of pests. Compared with other seed coating treatments, 50% Lumi ngwei TM625FS (with a control efficacy of 76.19% at 10d) was the best seed coating against S. frugiperda. The biological control “Telenomus remus + Picromerus lewisi” and “T. remus + Eocanthecona furcellata” had good control efficacy on S. frugiperda with 76.01%, 64.10% at 20d, respectively. Additionally, there were lower numbers of S. frugiperda in maize variety GuiDan6, BaoYu9, and YanBaiYu8. In summary, this research rec ommended four effective pest management strategies (GuiDan6-resistant maize variety, 50% Lumingwei TM625FS-seed coating agents, 5% emamectin benzoate-chemical pesticide, and “T. remus + P. lewisi”-biological control) in mountain maize planting fields. The study provided effective control strategies for

Experimental Investigation on Fatigue Behavior of Steel Reinforced Concrete Composite Beam-to-Girder Joints

Le-Wei Tong,Qingjun Xian,Liying Zhou,Yiyi Chen,Yunfeng Zhang 한국강구조학회 2012 International Journal of Steel Structures Vol.12 No.4

Fatigue behavior and failure mechanism of steel reinforced concrete (SRC) beam-to-girder joints is discussed in this paper,which is intended for use in high-speed railway station structures due to their high stiffness and load capacity. Three identical SRC beam-to-girder joint specimens were designed and tested under static loading and two stages of fatigue loading. In the first stage of fatigue loading, the specimens were subjected to design fatigue load for 2 million cycles, while during the second stage, the specimens were loaded to failure under increased fatigue loading amplitude in order to know its fatigue strength and failure mechanism. The constructional details of SRC beam-to-girder joint specimen and the method of loading and testing are presented. The comparison in structural behavior of the joint is made between under static and fatigue loading. Fatigue failure characteristics of the joint are described in detail. It is found that the SRC beam-to-girder joints remained in their elastic range and the concrete surface crack did not exceed 0.1 mm when subjected to design static loading and 2 million cycles of design fatigue loading. There was no significant difference in structural behavior of each component of SRC composite beam between static and fatigue loading. Fatigue failure occurred after these joints were applied higher-level fatigue loading for another 0.70to 0.91 million cycles. Fatigue crack was initiated at the tension flange of I-shape steel of beam connected by welding to the flange of I-shape steel of girder or at the hole in tension flange of I-shape steel of beam, and then the crack propagated along flange width and web height of the I-shape steel in beam until the I-shape steel lost loading capacity due to lack of enough cross section. The fatigue behavior of constructional detail of the I-shape steel played a key role in the fatigue strength of the SRC beam-to-girder joints. Discussions on improving the fatigue strength of SRC beam-to-girder joints and future research aspects are presented finally.

Transient Stability Simulation Analysis of Multi Node Power Network with Variable Speed Pumped Storage Units

Zhao Chong,Wang Longze,Ma Yiyi,Xiang Pengfei,Jiang Siyu,Chen Weidong,Zhang Yan,Li Meicheng 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.4

The output characteristics of variable speed pumped storage are different from conventional hydropower and constant speed pumped storage units. The continuous increase of installed capacity of variable speed pumped storage, poses a severe challenge to the safe and stable operation of the local power grid. Proposed in this paper is a kind suitable for multi-node containing variable speed pump machine storage unit electric power network transient stability method, considering the variable speed pumped storage units by the end of the instantaneous failure prone to sudden drop transient power, the power network with more nodes each busbar voltage stable operation as the goal, according to the regional power grid data under typical operation modes, Based on the power system analysis software package, an electromechanical simulation model of the 7-node power grid with variable speed pumped storage unit was established. The influence on the transient stability of a 7-node power grid is analyzed by removing variable speed pumped-storage units and three-phase short-circuit faults. The transient stability of the power grid can be maintained under the conditions of removing variable speed pumped-storage units and three-phase short-circuit faults, but some bus voltages are higher than the specified voltage upper limit. The reactive power compensation device is installed to improve the voltage stability of the power grid system, which can prevent the overvoltage accident caused by the fault of the communication system, achieve the purpose of multi-node power network stability, and improve the safety and stability of the regional power system when the fault occurs.

A multifunctional lactic acid based plasticizer used for plasticizing PVC and PLA: Endowing PLA elastic restore capability

Minjia Lu,Pingping Jiang,Pingbo Zhang,Shan Feng,Zhixuan Cui,Qingkui Song,Yong Zhao,Jingxian Shen,Yiyi Fan,Huixian Lu 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.128 No.-

A novel multifunctional plasticizer, cyclohexyl triethylene glycol oligo-lactate (CTLE) was designed by atwo-step esterification reaction using green non-toxic biomass lactic acid as raw material. Its structurewas characterized by 1H NMR, FT-IR and TOF-MS. Thermogravimetric analysis (TGA), tensile test andleaching test were used to evaluate the plasticizer effect of PVC or PLA blends. Compared with commercialplasticizers, CTLE showed more outstanding thermal stability, flexibility and migration stability. Under the same condition with the addition of 50 phr plasticizer, the CTLE plasticized PVC film hadthe lowest glass transition temperature (TgCTLE-50 = 24.6 C) and the highest initial decomposition temperature(TiCTLE-50 = 265.4 C). In PLA blends, only the CTLE plasticized PLA film could recover after fracture,and the stress relaxation test results showed that the stress value of PLA-CTLE-20 drops sharply to anon-zero value, showing elastic characteristics. We estimate that the excellent plasticity of CTLE is due toits molecular structure. Among them, a large number of polar groups form intermolecular forces withPVC chain segments to make the binding tight, and the ring structure increases the free volume betweenPVC chain segments.

Investigation on Oil-paper Degradation Subjected to Partial Discharge Using Chaos Theory

Gao, Jun,Wang, Youyuan,Liao, Ruijin,Wang, Ke,Yuan, Lei,Zhang, Yiyi The Korean Institute of Electrical Engineers 2014 Journal of Electrical Engineering & Technology Vol.9 No.5

In this paper, oil-paper samples composed of transformer windings were used to investigate the insulation degradation process subjected to partial discharge (PD), with artificial defects inside to simulate the PD induced insulation degradation. To determine appropriate test voltages, the breakdown time obtained through a group of accelerated electrical degradation tests under high voltages was firstly fitted by two-parameter Weibull model to acquire the average breakdown time, which was then applied to establish the inverse power law life model to choose advisable test voltages. During the electrical degradation process, PD signals were synchronously detected by an ultra-high frequency (UHF) sensor from inception to breakdown. For PD analysis, the whole degradation process was divided into ten stages, and chaos theory was introduced to analyze the variation of three chaotic parameters with the development of electrical degradation, namely the largest Lyapunov exponent, correlation dimension and Komogorov entropy of PD amplitude time series. It is shown that deterministic chaos of PD is confirmed during the oil-paper degradation process, and the obtained results provide a new effective tool for the diagnosis of degradation of oil-paper insulation subjected to PD.