Maritime Targets Tracking in Heavy-tailed Clutter With Unknown and Time-varying Density

Liwei Shi,Yu Kuang,Miaomiao He 제어·로봇·시스템학회 2024 International Journal of Control, Automation, and Vol.22 No.4

In order to solve the problem of maritime targets tracking in heavy-tailed sea clutter with unknown and time-varying clutter density, a multi-scan clutter sparsity estimator based amplitude-aided probability hypothesis density (MCSE-APHD) method is proposed in this paper. Firstly, the proposed method eliminates the targetoriginated measurements from multi-scan cumulative measurement set and estimates the spatial distribution density of clutter online. And the estimated clutter density parameter is fed to the tracker. Secondly, the amplitude-aided likelihood function as well as the estimated clutter parameter is established to update the Gaussian mixture posterior intensity of the state using the probability hypothesis density algorithm. The simulation results verify the effectiveness of the proposed algorithm.

Research on 3/6-phase Winding Switching Integrated Starter Generator for Range Extender Electric Vehicles

Guo Yingzhi,Shi Liwei,Zhang Wenchao,Chai Wenping,Kwon Byung-il 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

To improve the output current of an Integrated Starter Generator (ISG) with stable windings at high speed, a 3/6-phase winding switching permanent magnet (PM) machine is proposed this paper. At low-speed starting mode, large number of coils are series connected as conventional three-phase windings to keep the starting performance in starting the engine. At high-speed generating mode, the coils are connected as six-phase winding to generate greater current. Finite element analysis software was utilized to verify the EMF and output current performance of 3/6-phase winding switching of ISG with consequent-pole rotor, which was designed for Range Extender Electric Vehicles (REEV). The experimental results verified that the proposed ISG increased the output current by six-phase windings in generating mode.

Characteristics and Optimization of New Combined Magnetic Pole Negative-Salient Permanent Magnet Motor

Wang Wenqiang,Shi Liwei,Qiao Zhiwei,Zhu Yingjie,Ding Hongshan 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.3

With a wide speed range, high overload capacity and preventing permanent magnet demagnetization, negative-salient permanent magnet motors have a wide range of applications in the feld of electric vehicles. In view of the multiple operating conditions of the electric vehicle drive motor, this paper proposes a new type of combined magnetic pole negative-salient permanent magnet motor considering the driving conditions. Firstly, the optimization parameters of the motors are determined according to the analysis of the mathematical model. The design parameters are layered by the comprehensive sensitivity analysis, and the response surface Box-Behnken Design method and multi-objective genetic algorithm-II are used for optimization. Then, the electromagnetic performance of the proposed motor and the traditional interior permanent magnet motors are compared and analyzed through the fnite element simulation. Finally, a prototype is manufactured and the rationality of the proposed motor structure is verifed by experiments.

Analysis and Optimization of Asymmetric Hybrid Permanent Magnet Motor for Electric Vehicle

Liu Kaiwen,Shi Liwei,Liu Zhengwei,Wang Wenqiang,Ding Hongshan 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.5

An asymmetric hybrid permanent magnet motor (AHPMM) is proposed for the traditional permanent magnet motor (TPMM) with a large amount of rare earth materials and high cogging torque. The equivalent magnetic circuit model of the motor is established and the factors affecting the fluctuation of cogging torque are analyzed. With the objective of reducing the torque ripple and cogging torque of the AHPMM, the motor is parametrically modeled and analyzed, and multi-objective hierarchical optimization of the motor parameters is carried out using a hybrid algorithm combining the response surface algorithm and the single scan method, which ultimately determines the optimal combination of motor dimensional parameters. The electromagnetic performance of the AHPMM compared to the TPMM is analyzed using the finite element method. The results show that, without any decrease in output torque, the use of rare-earth materials is reduced by 18.5%, the cogging torque and the total harmonic distortion of the No-load back EMF waveform are reduced by 0.78 Nm and 4.7% respectively compared to the TPMM. Finally, a prototype motor is manufactured and the validity of the theoretical analysis and design of the AHPMM is verified through experiments.

Optimization and Pole-Slot Analysis of a New Type Permanent Magnet Hybrid Pole Motor for Electric Vehicles

Lv Bingchang,Shi Liwei,Liu Kaiwen,Li Lintao,Ding Hongshan 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.5

To reduce the use of rare earth materials and improve the performance of the motor, a new hybrid pole structure is proposed. The equivalent air-gap magnetic density model is established, and the N-th harmonic analytical expression of the air-gap magnetic density under the hybrid pole is derived; The optimal parameters of the hybrid pole structure are obtained by using sensitivity analysis to stratify the optimized parameters, using a mixture of Box-Behnken Design (BBD) method and Multi-Objective Genetic Algorithm-II (MOGA-II) for the first level parameters, and Central Composite Design (CCD) method for the second level parameters. The electromagnetic performance of the motor under different slots was analyzed based on the finite element method, and the results showed that the cogging torque and the no-load back electromotive force total harmonic distortion of the 48-slot compared to the 12-slot motor under the hybrid pole structure decreased by 45.2 and 47.3%, respectively. At the same time, the hybrid pole structure uses 19% less-rare-earth compared to the conventional structure.

Synergistic catalysis of bifunctional polyacrylonitrile fiber for the synthesis of (E)-α,β-unsaturated esters from aldehydes by decarboxylative Doebner–Knoevenagel reaction

Pengyu Li,Liwei Mi,Yuanyuan Liu,Wenqin Zhang,Xian-Lei Shi 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.81 No.-

A series of monofunctional and bifunctional polyacrylonitrilefiber catalysts have been successfullyprepared to catalyze the decarboxylative Doebner–Knoevenagel reaction of aldehydes and monoethylmalonate for the syntheses of the (E)-α,β-unsaturated esters. Among which, the catalyst PANPDFII/I showsthe best synergistic catalytic activity with high yields (89–96%), stereoselectivities (Z:E > 99:1) andreusability (up to 8 times). The influences of the N position on aminopyridine moiety, solvent andtemperature on the catalytic system were investigated in detail. This catalytic system can process well inhigher or lower polar organic solvents instead of moderate polar solvents, which is an interestingphenomenon in organic catalysis, and the reasons are explained in this work. Furthermore, a DMAP (4-dimethylaminopyridine) and piperazine synergistic catalytic mechanism in the micro-environment ofthefiber catalyst has been conceived to explain the high catalytic performance of this catalytic system. Besides, thefiber catalyst PANPDFII/I shows high application potential in industry for its good performancein scaled-up experiment, as well as its advantages of the easy preparation, high mechanical strength,flexibility and high stability in air.

Variable Winding Analysis and Optimization of Dual-mode Starter-Generator for Micro HEV Applications

Xiao Dong,Shi Liwei,An Junhao,Xing Fuzhen 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

To satisfy the requirement of high torque in starting state and accurate voltage regulation in generating state, a Dual-Mode Starter Generator (DMSG) with variable winding is proposed in this paper. Firstly, the influence of winding parameters on the performance of DMSG is analyzed by establishing the mathematical model of equivalent turns. Next, the cause of circulating current in starting state is analyzed. In order to solve the problem of circulating current between parallel branches, this paper presents a method that adding directional diode in main power circuit. The correctness of this method is verified by simulation. Then, the optimal matching relationship between the field winding and armature winding with multi-objective optimization is determined. At last, the FEA and prototype experiments verify the feasibility and performance of starter mode and generator mode of the DMSG.

Associations of racial and ethnic discrimination with adverse changes in exercise and screen time during the COVID-19 pandemic in the United States

Xia Tong,Gee Gilbert C.,Jian Li,Liu Xinyue,Dai Jin,Shi Lu,Zhang Donglan,Chen Zhuo,Han Xuesong,Li Yan,Li Hongmei,Wen Ming,Su Dejun,Chen Liwei 한국역학회 2023 Epidemiology and Health Vol.45 No.-

Objectives: During the coronavirus disease 2019 (COVID-19) pandemic, a growing prevalence of racial and ethnic discrimination occurred when many Americans struggled to maintain healthy lifestyles. This study investigated the associations of racial and ethnic discrimination with changes in exercise and screen time during the pandemic in the United States (US). Methods: We included 2,613 adults who self-identified as non-Hispanic White, non-Hispanic Black, non-Hispanic Asian, or Hispanic from the Health, Ethnicity, and Pandemic (HEAP) study, a cross-sectional survey conducted among a nationally representative sample of US adults between October and November 2020. We assessed self-reported racial and ethnic discrimination by measuring COVID-19-related racial and ethnic bias and examined its associations with changes in exercise and screen time using multivariable logistic regression models. We analyzed data between September 2021 and March 2022.Results: COVID-19-related racial and ethnic bias was associated with decreased exercise time among non-Hispanic Asian (odds ratio [OR]=1.46; 95% confidence interval [CI], 1.13–1.89) and Hispanic people (OR=1.91; 95% CI, 1.32–2.77), and with increased screen time among non-Hispanic Black people (OR=1.94; 95% CI, 1.33–2.85), adjusting for age, gender, education, marital status, annual household income, insurance, and employment status. Conclusions: Racial and ethnic discrimination may have adversely influenced exercise and screen time changes among racial and ethnic minorities during the COVID-19 pandemic in the US. Further studies are needed to investigate the mechanisms through which racial and ethnic discrimination can impact lifestyles and to develop potential strategies to address racial and ethnic discrimination as a barrier to healthy lifestyles.

Numerical calculation and optimization designs in engine cooling water pump

Li Wei,Wang Chuan,Shi Weidong,Zhao Xiaofan,Yang Yongfei,Pei Bing 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.5

The cavitation damage in the Engine cooling water pump (ECWP) is the key factor that shortens the lifespan of automobile cooling systems, and causes vibration and noise. To improve cavitation performance and external characteristics of ECWP, three optimized models were designed on the basis of WP7 diesel ECWP. The whole flow fields in three models and the prototype pump were numerically simulated, employing the time averaged Navier-Stokes equation, the standard k-ε turbulent model and Zwart-Gerber-Belamri multiphase flow model by ANSYS-CFX software. Pressure distribution, turbulent kinetic energy distribution, bubble volume fraction distribution, external characteristics and cavitation performance of the prototype pump and optimized models were compared and analyzed. The results show that the external characteristics and cavitation performance of the optimized models are significantly better than that in the prototype pump. Through decreasing the inlet blade angle and wrap angle, extending the blade to inlets and extending a certain inclination in the blade, shock loss in blade inlet was reduced and so, the performance of pump will be improved. The flow condition at blade inlet will also be improved greatly, which in turn improves cavitation performance. When reducing the quantity of blades, the excretion coefficient will drop, flow area of blade inlet becomes bigger, but head has a little drop. And the pump optimized by reducing the quantity of blades has the optimal cavitation performance among three optimized models. With the decrease of impeller diameter, the absolute pressure in the critical cavitation point becomes bigger, the inlet bubble volume fraction at the same absolute pressure increases while cavitation performance gets worse. The obtained numerical results were compared with the experimental ones, and the outcome showed the same tendency between the two along with acceptable error.

Licochalcone A Protects Vaginal Epithelial Cells Against Candida albicans Infection Via the TLR4/NF-κB Signaling Pathway

Li Wei,Yin Yujun,Li Taoqiong,Wang Yiqun,Shi Wenyin 한국미생물학회 2024 The journal of microbiology Vol.62 No.7

Vulvovaginal candidiasis (VVC) is a prevalent condition affecting a significant portion of women worldwide. Licochalcone A (LA), a natural compound with diverse biological activities, holds promise as a protective agent against Candida albicans (C. albicans) infection. This study aims to investigate the potential of LA to safeguard vaginal epithelial cells (VECs) from C. albicans infection and elucidate the underlying molecular mechanisms. To simulate VVC in vitro, VK2-E6E7 cells were infected with C. albicans. Candida albicans biofilm formation, C. albicans adhesion to VK2-E6E7 cells, and C. albicansinduced cell damage and inflammatory responses were assessed by XTT reduction assay, fluorescence assay, LDH assay, and ELISA. CCK-8 assay was performed to evaluate the cytotoxic effects of LA on VK2-E6E7 cells. Western blotting assay was performed to detect protein expression. LA dose-dependently hindered C. albicans biofilm formation and adhesion to VK2-E6E7 cells. Furthermore, LA mitigated cell damage, inhibited the Bax/Bcl-2 ratio, and attenuated the secretion of pro-inflammatory cytokines in C. albicans-induced VK2-E6E7 cells. The investigation into LA’s impact on the Toll-like receptor 4 (TLR4)/nuclear factor-kappa B (NF-κB) pathway revealed that LA downregulated TLR4 expression and inhibited NF-κB activation in C. albicans-infected VK2-E6E7 cells. Furthermore, TLR4 overexpression partially abated LA-mediated protection, further highlighting the role of the TLR4/NF-κB pathway. LA holds the potential to safeguard VECs against C. albicans infection, potentially offering therapeutic avenues for VVC management.