The intelligent controller based on fuzzy logic neural networks ( FLNNs )

Wang Zhenfeng,Jin Dongming,Li Zhijian 대한전자공학회 1994 ICONIP : International Conference On Neural Inform Vol.3 No.2

Contact characteristics and interfacial motion states during sphere oblique impact with initial spin

Qingpeng Wang,Kai Zhang,Zhenfeng Wang,Heng Wang,Yufeng Sun,Xiankun Gao,Guangyin Xu 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.5

The impact between a sphere and flat surface plays a significant role in the granular handling process. A method is proposed to investigate the evolution of interfacial states for the sphere oblique impact with initial spin. Firstly, the sphere with irregular surface structures is applied, and the imprinted surfaces are recorded with a thin carbon paper. Then the interfacial characteristics are analyzed in cases of impact angle, contact material and drop height, etc. The geometrical parameters decrease exponentially with impact angle and include three main stages: plateau, slow decrease and sharp decrease. The motional ratio corresponds to slow increase, steady state and sharp increase. For the no pre-spin, it goes through five interfacial states with impact angle. Comparatively, the forward spin decreases the critical angle, and the backward spin decreases the number of states. Furthermore, the parameters increase linearly with drop height, while the effect on interfacial states is very little.

Facial Synthesis of Zn-Doped Fe3O4 with Enhanced Electromagnetic Wave Absorption Performance in S and C Bands

Zhenfeng Liu,Honglong Xing,Lei Wang,Dexin Tan,Ying Gan,Xiaoli Ji,Guocai Xu 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.8

In this study, Zn-doped Fe3O4 nanoparticles were successfully synthesized by a facile solvothermal method in the presence of sodium dodecyl sulfate (SDS). The morphology, magnetic properties and electromagnetic wave absorbing properties of these materials were characterized. Results showed that Zn2+ played a significant role in the formation of Zn-doped Fe3O4. With the protection of SDS, highly dispersed Fe3O4 nanoparticles were obtained. The nanoparticle size decreased after Zn2+ doping, and the dispersity deteriorated with increasing Zn2+ doping concentration. Zndoped Fe3O4 exhibited excellent electromagnetic wave absorbing property, which resulted in magnetic loss and dielectric loss at an appropriate doping concentration. The minimum reflection loss (RL) was approximately -27.2 dB at 16.9 GHz. As the coating layer thickness increased to 4.0 mm, the bandwidth was approximately 5.0 GHz corresponding to RL below -10 dB, which nearly covered the entire S band (2–4 GHz) and C band (4–8 GHz). The peak frequency of RL and the number of peaks matched the quarter-wave thickness criteria. It was believed that the Zndoped Fe3O4 could be a potential electromagnetic wave absorbing material in S and C bands.

Synthesis and Excellent Microwave Absorption Properties of ZnO/Fe3O4/MWCNTs Composites

Lei Wang,Honglong Xing,Zhenfeng Liu,Ziyao Shen,Xiang Sun,Guocai Xu 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.12

ZnO nanocrystals were introduced into Fe3O4/MWCNTs composites to improve the impedance matching and electromagnetic (EM) wave attenuation of the system. The as-synthesized ZnO/ Fe3O4/MWCNTs composites were characterized by X-ray diffraction, vibrating sample magnetometer, field-emission scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy. SEM and TEM images showed that Fe3O4 microspheres 100–200 nm in size connected MWCNTs. Analysis of EM parameters revealed that the impedance matching of the ZnO/Fe3O4/MWCNTs composites was considerably improved after ZnO nanocrystals were introduced. The ZnO/Fe3O4/MWCNTs composites exhibited a highly efficient microwave absorption (MA) capacity within the tested frequency range of 2–18 GHz. The optimal reflection loss of EM waves was -38.2 dB at 6.08 GHz with an absorber thickness of 3.5 mm. The excellent MA properties of the composites could be attributed to the improved impedance matching, interfacial polarization, and combined effects of dielectric and magnetic losses.

Models and Experiments for the Main Topologies of MRC-WPT Systems

Yang, Mingbo,Wang, Peng,Guan, Yanzhi,Yang, Zhenfeng The Korean Institute of Power Electronics 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.6

Models and experiments for magnetic resonance coupling wireless power transmission (MRC-WPT) topologies such as the chain topology and branch topology are studied in this paper. Coupling mode theory based energy resonance models are built for the two topologies. Complete energy resonance models including input items, loss coefficients, and coupling coefficients are built for the two topologies. The storage and the oscillation model of the resonant energy are built in the time domain. The effect of the excitation item, loss item, and coupling coefficients on MRC systems are provided in detail. By solving the energy oscillation time domain model, distance enhancing models are established for the chain topology, and energy relocating models are established for the branch topology. Under the assumption that there are no couplings between every other coil or between loads, the maximum transmission capacity conditions are found for the chain topology, and energy distribution models are established for the branch topology. A MRC-WPT experiment was carried out for the verification of the above model. The maximum transmission distance enhancement condition for the chain topology, and the energy allocation model for the branch topology were verified by experiments.

Models and Experiments for the Main Topologies of MRC-WPT Systems

Mingbo Yang,Peng Wang,Yanzhi Guan,Zhenfeng Yang 전력전자학회 2017 JOURNAL OF POWER ELECTRONICS Vol.17 No.6

Models and experiments for magnetic resonance coupling wireless power transmission (MRC-WPT) topologies such as the chain topology and branch topology are studied in this paper. Coupling mode theory based energy resonance models are built for the two topologies. Complete energy resonance models including input items, loss coefficients, and coupling coefficients are built for the two topologies. The storage and the oscillation model of the resonant energy are built in the time domain. The effect of the excitation item, loss item, and coupling coefficients on MRC systems are provided in detail. By solving the energy oscillation time domain model, distance enhancing models are established for the chain topology, and energy relocating models are established for the branch topology. Under the assumption that there are no couplings between every other coil or between loads, the maximum transmission capacity conditions are found for the chain topology, and energy distribution models are established for the branch topology. A MRC-WPT experiment was carried out for the verification of the above model. The maximum transmission distance enhancement condition for the chain topology, and the energy allocation model for the branch topology were verified by experiments.

Structure and Microwave Absorption Properties of Polyaniline/Zn Ferrite Composites

Honglong Xing,Ye Liu,Zhenfeng Liu,Huan Wang,Hanxiao Jia 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.09

Polyaniline (PANI)/Zn ferrite composites were fabricated by simple two-step method. The crystal phase, particle size, morphology, thermal stability and conductivity were characterized. Electromagnetic parameters of PANI/Zn ferrite composites were measured at room temperature in the frequency of 2–18 GHz. The prepared composite had an amorphous fluffy structure, Zn ferrite nanoparticles with diameters ranging from 20 nm to 30 nm are encapsulated in PANI or on PANI surface, and the thermal stability of the composite is poor. But Zn ferrite content plays a key role in influencing this structure and regulating microwave attenuation capability. The PANI/Zn ferrite composites showed an enhanced microwave absorption performance in Ku band at thin coating thickness which corresponds to RL value below - 10 dB and the minimum reflection loss (RL) is - 54.4 dB at 17.6 GHz with the coating thickness of 1.4 mm.

Excellent Microwave Absorption Behaviors of Polyaniline Composites Containing CeO2 Nanorods in the X-Band

Honglong Xing,Qing Yin,Zhenfeng Liu,Lei Wang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2017 NANO Vol.12 No.4

Conductive polyaniline/CeO2 nanocomposite powders (PANI/CeO2) were prepared by an in situ polymerization method. The effects of CeO2 content on the microwave absorption properties of composites were investigated. The phase composition, morphological characteristics, electromagnetic parameters and microwave absorption properties of the composites were characterized through X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and vector network analysis. Results show that CeO2 nanorods are coated with PANI to form a well-defined hierarchical structure. CeO2 is wellincorporated into the PANI matrix. CeO2/PANI exhibits excellent microwave absorption properties at 2–18 GHz. As the CeO2 content increases to 30 wt.%, an optimal reflection loss (RL) of -40 dB (99.99% of electromagnetic wave absorption) is observed at 8.8 GHz with a thickness of 3.0 mm. The frequency bandwidth corresponding to 90% of electromagnetic wave absorption crosses the X-band. Therefore, PANI/CeO2 can be used as an advantageous candidate for a new type of microwave absorptive material.

Diffusion-Weighted MR Imaging of Unicystic Odontogenic Tumors for Differentiation of Unicystic Ameloblastomas from Keratocystic Odontogenic Tumors

Yifeng Han,Xindong Fan,Lixin Su,Zhenfeng Wang 대한영상의학회 2018 Korean Journal of Radiology Vol.19 No.1

Objective: Differentiating unicystic ameloblastomas from keratocystic odontogenic tumors (KCOT) is necessary for the planning of different treatment strategies; however, it is difficult based on conventional CT and MR sequences alone. The purpose of this study was to investigate the utility of diffusion-weighted imaging (DWI) and apparent diffusion coefficients (ADCs) in the differentiation of the two tumors. Materials and Methods: We prospectively studied 40 patients with odontogenic cysts and tumors of the maxillomandibular region using conventional MR imaging and DWI. ADCs were measured using 2 b factors (500 and 1000). Results: Unicystic ameloblastomas (n = 11) showed free diffusion on DWI and a mean ADC value of 2.309 ± 0.17 x 10-3 mm2/s. KCOT (n = 15) showed restricted diffusion on DWI with a mean ADC value of 0.923 ± 0.20 x 10-3 mm2/s. The ADC values of unicystic ameloblastomas were significantly higher than those of KCOT (p < 0.001, Mann-Whitney U-test). An ADC cut-off value of 2.0 x 10-3 mm2/s to differentiate KCOT and unicystic ameloblastomas resulted in a 100% sensitivity and 100% specificity. Dentigerous cysts (n = 3) showed restricted diffusion on DWI and similar ADC values (1.257 ± 0.05 x 10-3 mm2/s) to those of KCOT. Conclusion: Diffusion-weighted imaging and ADC determination can be used as an adjuvant tool to differentiate between unicystic ameloblastomas and KCOT, although the ADC values of dentigerous cysts overlap with those of KCOT.

State Observers for Suspension Systems with Interacting Multiple Model Unscented Kalman Filter Subject to Markovian Switching

Zhang Zipeng,Xu Nan,Chen Hong,Wang Zhenfeng,Li Fei,Wang Xinyu 한국자동차공학회 2021 International journal of automotive technology Vol.22 No.6

This paper presents a novel model-based observer algorithm to address issues associated with nonlinear suspension system state estimation using interacting multiple model unscented Kalman Filters (IMMUKF) under various road excitation. Due to the fact that practical working condition is complex for the suspension system, e.g. additional load. Meanwhile, the changed sprung mass parameter will induce model changed of suspension system, and it can lead to state transition between various models. To tackle the mentioned issue, the models of road profile and suspension system are first established to describe the nonlinear suspension dynamics. Then, considering the variation of sprung mass under various movement conditions, an unscented Kalman Filter (UKF) algorithm is proposed to identify the sprung mass. Based on the interacting multiple model (IMM) and Markov Chain Monte Carlo (MCMC) theory, a novel IMMUKF observer is developed to estimate the movement state of suspension system. The stability conditions for the proposed observer is calculated using the stochastic stability theory. Finally, simulations and validations are performed on a quarter vehicle suspension system under various ISO road excitations, to validate the UKF and IMMUKF algorithms for acquiring suspension system states, and results illustrate that the maximum root mean square error of state estimation for the proposed algorithm is less than 7.5 %.