Vibration analysis and dynamic performance improvement of high-frequency injection method

Peng, Wei,Qiao, Mingzhong,Jiang, Chao,Lu, Xihao,Zhu, Peng The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.2

This paper analyzes and compares the typical rotating high-frequency voltage injection (RTHF) method and the typical pulsating high-frequency voltage injection (PSHF) method in terms of torque ripple and vibration. Analysis and experiment results indicate that the PSHF performs better when it comes to torque pulsation and vibration. In addition, it is more suitable for rim motors which have strict restrictions on vibration. However, the estimated rotor position in PSHF has multiple convergence points. In addition, the filters used in PSHF can degrade the dynamic response of the PMSM sensorless field oriented control (SLFOC) system. An improved PSHF method compensated by Hall signals is proposed to accelerate the estimation process and improve the system stability in the presence of sudden load disturbances. The improved method is verified on an 11 kW rim motor experimental platform.

Visual Monitoring of Industrial Operation States Based on Kernel Fisher Vector and Self-organizing Map Networks

Wei-Peng Lu,Xue-Feng Yan 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.6

As industrial process becomes increasingly complicated and the correlation between industrial process variables tends to exhibit strong nonlinear characteristics, how to effectively and visually monitor industrial operation states is challenging. A method based on kernel Fisher vector and self-organizing map networks (KFV-SOM) is proposed to improve the visualization of process monitoring. In KFV-SOM, kernel Fisher discriminant analysis is first employed to map data into high-dimensional space by using a nonlinear function, and the optimal Fisher feature vector, which can represent industrial operation states fittingly, is extracted. That is, the normal state and different kinds of faults can be distinguished well in the Fisher feature vector space. The topological structure of the Fisher feature vector space is then visualized intuitively on the two-dimensional output map of self-organizing map (SOM) with the Fisher feature vector as the input of the SOM network. Thus, the KFV-SOM can effectively realize the visualization of monitoring. Continuous stirred tank reactor process is applied to illustrate the capability of KFV-SOM. Result shows that KFV-SOM can effectively visualize monitoring, and it is better in showing the operation states of normal state and different kinds of faults on the output map of the SOM network than SOM, SOM integrated with principal component analysis, SOM integrated with correlative component analysis, SOM integrated with Fisher discriminant analysis, and SOM integrated with canonical variable analysis.

Time-dependent Nonlinear Theory and Numerical Simulation of Folded Waveguide Traveling Wave Tubes

Wei Feng Peng,Zhong Hai Yang,Yu Lu Hu,Zan Cao,Yin-Fu Hu,Jin-Jun Feng,Xian-Ping Wu 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.6

In this paper, a time-dependent nonlinear theory including the generalized time-dependent radiofrequency (RF) field equations is presented to simulate the beam and wave interaction (BWI) of folded waveguide (FWG) traveling wave tubes (TWTs). The analytical RF fields in FWG TWTs are replaced by digitized RF field profiles obtained from electromagnetic simulations. A W-band FWG TWT is studied by using a self-consistent one-dimensional code based on the theory. The numerical results show good predictions when compared with the experimental tests.

In Situ Growth of MOF-Derived NaCoPO4@Carbon for Asymmetric Supercapacitive and Water Oxidation Electrocatalytic Performance

Peng Guo,Zhaojie Wang,Hongyu Chen,Shaohui Ge,Chen Chen,Haowei Wang,Jinbao Zhang,Minglei Hua,Shuxian Wei,Xiaoqing Lu 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.15 No.01

The increasing energy crisis promotes the study on novel electrode materials with high performance for supercapacitive storage and energy conversion. Transition metal phosphates have been reported as a potential candidate due to the unique coordination and corresponding electronic structure. Herein, we adopted a facile method for preparing NaCoPO4@C derived from a metal organic framework (MOF) as a bifunctional electrode. ZIF-67 was synthesized before a refluxing process with Na2HPO4 to form a precursor, which is transformed into the final product via calcination in different atmospheres. Specifically, the resultant NaCoPO4@C exhibits a high specific capacitance of 1178.7 F g -1 at a current density of 1 A g -1 for a supercapacitor. An asymmetric supercapacitor (ASC) assembled with active carbon displays a high capacitance of 163.7 F g -1 at 1 A g -1. In addition, as an oxygen evolution reaction (OER) catalyst, the NaCoPO4@C electrode requires only 299 mV to drive a current density of 10 mA cm -2. These results suggest that the rational design of MOF-derived NaCoPO4@C provides a variety of practical applications in electrochemical energy conversion and storage.

Coring Damage Extent of Rock Cores Retrieved from High In-situ Stress Condition: A Case Study

Peng Yan,Qi He,Wenbo Lu,Yanli He,Wei Zhou,Ming Chen 대한토목학회 2017 KSCE JOURNAL OF CIVIL ENGINEERING Vol.21 No.7

The distribution of damage in deep rock cores is critical for assessing its influence on rock mechanical characteristics. This paper presents a case study on estimating the coring damage extent induced by the stress redistribution through a combined method of numerical simulation and X-ray Computed Tomography (CT) scanning. Rock cores are taken at 1900 m depth from the test tunnel at Jin-ping Second Stage Hydropower Station (JPII) in China. Firstly, the stress path experienced by the rock core during coring has been examined by the numerical simulation, and the distribution of tensile zone in the cross-section of rock core is also discussed. Then two kinds of samples, collected from the same position under different stress levels, are scanned to obtain CT images, and a special CT value analysis strategy was adopted to evaluate coring damage intensities of these samples. The result indicates that the stress state can be regarded as the principal factor for the distribution of coring damage. During coring in the Test Tunnel of JPII under the quasi-hydrostatic stress condition, high tensile stresses (over 5 MPa) are observed at the exterior edge of rock cores, which may lead to the nucleation of microcracks around the core boundary, and the coring damage then propagates to the core centre. The CT scanning also illustrates that the coring damage zone may cover approximately 70~80% of the entire cross-section from the outside inside (stress level of 50 MPa), and that the central part of the core is less damaged or eventually undisturbed. Thus, intact rock samples can be expected to be obtained by overcoring the original rock cores. However, the applicability of the overcoring method seems to be largely dependent on the state of in-situ stress at the coring site. The whole core may be damaged if the lateral stress coefficient reaches a critical value (e.g. greater than 3.0), in which case a special coring equipment should be adopted to improve the stress state during coring.

Generation of Buffalo Mammary Epithelial Cells with Targeted Knockout of 18s rDNA by a CRISPR/Cas9 Adenovirus System

Peng Zhu,An-Qin Duan,Ting-Xian Deng,Xing-Rong Lu,Xiao-Ya Ma,Sha-Sha Liang,Chun-Ying Pang,Xian-Wei Liang 한국생물공학회 2017 Biotechnology and Bioprocess Engineering Vol.22 No.5

In recent years, CRISPR/Cas9 has rapidly become one of the most promising genome editing tools because it is simple and easy to use and cost effective. However, the large size of Cas9 sequences limits its application in clinically promising vectors and it also impacts non-viral transfection. In this study, CRISPR/Cas9 adenovirus vectors that target the buffalo 18s rDNA gene were constructed, transfected into 293 cells for adenovirus packaging, and the adenovirus was used to knockout the 18s rDNA gene in buffalo mammary epithelial cells. The results demonstrated that the CRISPR/Cas9 adenovirus vectors for the buffalo 18s rDNA gene could efficiently target the sites as revealed by the fluorescence reporter system. After amplification, the adenovirus titer of Sn458- 18s1 and Sn458-18s2 reached 1.03 × 109PFU/mL and 1.05 × 109 PFU/mL, respectively. For buffalo mammary epithelial cell infection, the efficiency was 100% when the multiplicity of infection (MOI) 100 PFU/mL. There were 9 mutational clones found in the 20 clones, and the gene mutagenesis rate reached 45%. Of these, 2 clones were 35-bp deleted and 7 clones were 12-bp deleted. These results suggested that the adenovirus system overcame the low transfection efficiency of the buffalo mammary epithelial cells associated with using lipid-based methods or electroporation. Moreover, we preliminary developed an efficient technique for multiple-locus gene targeting at repeated sequences of the buffalo genome.

Development of Parallel Plate Avalanche Counter for heavy ion collision in radioactive ion beam

Wei, Xianglun,Guan, Fenhai,Yang, Herun,Wang, Yijie,Zhang, Junwei,Ma, Peng,Diao, Xinyue,Lu, Chengui,Li, Meng,Guan, Yuanfan,Duan, Limin,Hu, Rongjiang,Zhang, Xiuling,Xiao, Zhigang Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.3

We have developed a position-sensitive Parallel Plate Avalanche Counter (PPAC) to detect the fission fragments and reconstruct the fission reaction plane in the experiment of studying nuclear equation of state (nEOS) by means of heavy ion collision (HIC). This experiment put forward high requirements for the performances of PPAC, such as the time resolution, efficiency and position resolution. According to these requirements we designed the PPAC with an active area of 240 mm × 280 mm working at low gas pressure. The results show that time resolution could be less than 300 ps. Position resolution is consistent with the theoretical calculation about 1.35 mm. Detection efficiency could be approaching 100% gradually with the voltage increasing in different gas pressures. The performances of PPAC have also been verified in beam experiment. Each set of anode wires can be accurately separated in the position spectrum. In the beam experiment, we also got the back-to-back correlation of fission fragments which is one of the direct signals characterizing binary decay.

A Substation-Oriented Approach to Optimal Phasor Measurement Units Placement

Wei Bao,Rui-Peng Guo,Zhen-Xiang Han,Li-Yue Chen,Min Lu 대한전기학회 2015 Journal of Electrical Engineering & Technology Vol.10 No.1

State Estimation (SE) is the basis of a variety of advanced applications used in most modern power systems. An SE problem formed with enough phasor measurement units (PMUs) data is simply a linear weighted least squares problem requiring no iterations. Thus, designing a minimumcost placement of PMUs that guarantees observability of a power system becomes a worthy challenge. This paper proposes an equivalent integer linear programming method for substation-oriented optimal PMU placement (SOOPP). The proposed method uses an exhaustive search to determine a globally optimal solution representing the best PMU placement for that particular power system. To obtain a more comprehensive model, contingencies and the limitation of the number of PMU measurement channels are considered and embodied in the model as changes to the original constraints and as additional constraints. The proposed method is examined for applicability using the IEEE 14-bus, 118-bus and 300-bus test systems. The comparison between SOOPP results and results obtained by other methods reveals the excellence of SOOPP. Furthermore, practical large-scale power systems are also successfully analyzed using SOOPP.

Radiotherapy combined with chemotherapy increases the risk of herpes zoster in patients with gynecological cancers: a nationwide cohort study

Peng-Yi Lee,Jung-Nien Lai,Shang-Wen Chen,Ying-Chun Lin,Lu-Ting Chiu,Yu-Ting Wei 대한부인종양학회 2021 Journal of Gynecologic Oncology Vol.32 No.2

Objective: This study aimed to determine the effect of radiotherapy (RT) on the risk of herpeszoster (HZ) in patients with gynecological cancers via a nationwide population-based study. Methods: Based on patient data obtained from the National Health Insurance ResearchDatabase, 1928 gynecological cancer patients were identified with 1:1 matching for RT andnon-RT cohorts by age, index date, and cancer type. Another cohort consisting of 964 non cancer individuals matched was used as normal control. The incidence of HZ was comparedbetween cancer patients with and without RT. Age, comorbidities, cancer-related surgery andchemotherapy (CT), and cancer type were adjusted as confounders. Results: The risk of HZ in cancer patients was higher than that of non-cancer individuals(14.23 versus 8.34 per 1,000 person-years [PY], the adjusted hazard ratio [aHR]=1.38,p=0.044). In the cancer population, the incidence of HZ for the RT and non-RT cohorts was20.55 versus 10.23 per 1,000 PY, respectively (aHR=1.68, p=0.009). Age >50 years was anindependent factor for developing HZ. The 5-year actuarial incidence for patients receivingneither RT nor CT, RT alone, CT alone, and combined modalities was 5.4%, 6.9%, 3.7%,and 9.9%, respectively (p<0.001). In the RT cohort, the risk rose rapidly in the first year,becoming steady thereafter. Conclusion: This population-based study showed that gynecological cancer patientsreceiving RT combined with CT had the highest cumulative risk of HZ. Health careprofessionals should be aware of the potential toxicities.

Biochemical mechanism of rice nitrogen promoting the resistance development of Nilaparvata lugens (Stål) to buprofezin

Lu Wencai,Liao Dunxiu,Wei Peng,Ma Lianjie,Zhang Hui,Niu Ying 한국응용곤충학회 2021 Journal of Asia-Pacific Entomology Vol.24 No.3

Overusing nitrogen fertilizer not only pollute farmlands, but also make Nilaparvata lugens (Stål) less susceptible to pesticides. The current study investigated the relationship between nitrogen fertilizer application and bupro fenzin resistance in N. lugens in rice by conducting a series of field efficacy tests and laboratory bioassays. The results showed that the efficacy of buprofezin decreased significantly with high level of nitrogen fertilizer application, compared to those with low or no nitrogen application in rice fields. In the laboratory, the resistance ratios of N. lugens to buprofezin, assayed at three concentrations of nitrogen (0, 1.0, 3.0 mmol/L), have devel oped to 14.05-, 18.40- and 25.81-fold after 20 generations of resistance selection, respectively. Meanwhile, the resistance ratios of N. lugens without buprofezin treated were 1.00-, 3.30- and 4.67-fold after 20 generations as the nitrogen concentrations increased. The enzymatic assays revealed that the activities of P450 and esterase increased significantly after resistance selection with buprofezin and nitrogen, especially on the esterase activity in N. lugens under the condition of nitrogen treatment. These results suggested that nitrogen fertilizer application contributed to the resistance development in N. lugens to buprofezin by enhancing the activity of esterase.