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Authors: Su, Yufeng | Zhang, Kun | Ye, Zhitong

Article Type: Research Article

Abstract: To better understand and make use of its characteristics, a diamagnetic levitation structure, which consists of NdFeB permanent magnets and pyrolytic graphite sheets, is studied in this report. Finite element analysis is performed to analyze the influence of floating magnets with different structures and sizes on the equilibrium spacing and movement space of a floating magnet. The key factors that affect the equilibrium spacing and movement space are obtained, and the effectiveness of the simulation is verified experimentally. Compared to the experimental results, the maximum simulation error is less than 10%. A forced vibration model with a single degree of …freedom is used to denote the diamagnetic levitation structure, and the natural frequency is analyzed to be 4.87 Hz for the structure in this study. The nonlinear characteristics of the system are studied to obtain a better understanding of the vibration of the nonlinear system. The diamagnetic levitation structure has great potential in the application of vibration energy harvesters or noncontact sensors and actuators. Show more

Keywords: Diamagnetic levitation, magnet, pyrolytic graphite, nonlinear, movement space, equilibrium position

DOI: 10.3233/JAE-170011

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 55, no. 1, pp. 113-128, 2017

Authors: Zhang, Kun | Shen, Chong | Qian, Gao | Li, Hanwen

Article Type: Research Article

Abstract: In order to solve the frequent communication obstacle problem in multiple-input and multiple-output (MIMO) system communication caused by routing conflicts, it is necessary to quickly locate the optimal nodes for communication, so a fast optimal node locating algorithm for MIMO system communication based on link balance control is proposed in this paper. In this algorithm, a MIMO system communication channel model is constructed through the link balance control method, and interference features of signals are separated by analyzing the spectrum of communication signals based on the model. Simulation results show that this algorithm can provide 100% accuracy in optimal node …locating under signal-to-noise ratio of 80 dB, an average improvement of 13.8% over that in traditional algorithms. The results show that our algorithm can provide high accuracy in locating the optimal nodes for communication, and can ensure high locating efficiency, which effectively improves the communication transmission quality of MIMO system. Show more

Keywords: MIMO system, communication repair, optimal node, locating, Link Balance Control

DOI: 10.3233/WEB-190411

Citation: Web Intelligence, vol. 17, no. 2, pp. 169-176, 2019

Authors: Gong, Qi | Zhang, Weiwei | Su, Yufeng | Zhang, Kun

Article Type: Research Article

Abstract: In this paper, a diamagnetic-airflow hybrid levitation structure is reported, with a floating magnet rotor stably levitated above a diamagnetic disc just using a lifting magnet and airflow. Compared with the typical diamagnetically stabilized structure, the rotation speed of the rotor is increased from 9570 rpm to 16666 rpm, and the levitation gap is increased from 0.3 mm to 0.7 mm when the airflow rate exceeds 2198 sccm under standard temperature and pressure (STP). At the same time, the rotor can be stably levitated at any height from 0.2 mm to 0.8 mm by adjusting the vertical position of the nozzles. With the hybrid levitation structure, it’s …possible to overcome the structural limitation of typical diamagnetically stabilized levitation structure and enhance the working performance of the rotor. This levitation structure is expected to be applied to sensing, energy harvesting and air bearing under actuation of airflow. Show more

Keywords: Diamagnetic, airflow, stabilized levitation, simulation, energy harvesting

DOI: 10.3233/JAE-190081

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 62, no. 2, pp. 341-354, 2020

Authors: Gao, Yan | Liu, Chenchen | Zhao, Liangyu | Zhang, Kun

Article Type: Research Article

Abstract: The q-rung orthopair fuzzy set is a powerful and useful tool to deal with uncertainty, but in actual decision-making process, decision-makers are usually required to analyze the actual problem dynamically. Therefore in this paper, we consider the time-series q-rung orthopair fuzzy decision making. First, we introduce the new cosine similarity measure of q-ROFS which combines the cosine similarity measure and the Euclidean distance measure. Then, we combine the advantages of projection method and grey correlation degree, establishing the nonlinear programming model to calculate the weights of attributes. Furthermore, we use the exponential decay model to get the weights formulas of …q-ROFS at different times. Then we replace the distance function with grey relational projection and extend TOPSIS method. Based on these, we propose a new MAGDM approach to deal with time-series q-rung orthopair fuzzy problem not only from the point of view of geometry but also from the point of view of algebra. Finally, we give a practical example to illustrate effectiveness and feasibility of the new method. Show more

Keywords: q-rung orthopair fuzzy set, time-series, grey correlation degree, cosine distance measure

DOI: 10.3233/JIFS-210841

Citation: Journal of Intelligent & Fuzzy Systems, vol. 41, no. 1, pp. 2161-2170, 2021

Authors: Zhang, Kun | Zhao, Haojie | Feng, Wei | Wu, Zhaoyun | Liu, Baoguo

Article Type: Research Article

Abstract: Diamagnetic levitation is a physical phenomenon that uses the diamagnetism of diamagnetic materials to stably levitate itself in an external strong magnetic field, which has great potential in the areas of sensors, actuators, and biomedicine. In this paper, a typical diamagnetic levitation system composed of a NdFeB permanent magnet array and pyrolytic graphite sheet is built. The levitation mechanism of the diamagnetic levitation system is analyzed theoretically, the main factors affecting the static levitation of the pyrolytic graphite sheet are determined, and the influence of structural parameters on the levitation height of the pyrolytic graphite sheet is studied. Furthermore, the …dynamic and numerical simulation models of the diamagnetic levitation system are established, and the dynamic response characteristics of the pyrolytic graphite sheet are analyzed under different vibration excitation. This study provides a reference for developing applications based on the diamagnetic levitation system. Show more

Keywords: Diamagnetic levitation, static levitation, dynamic response, vibration, collision

DOI: 10.3233/JAE-220066

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 71, no. 2, pp. 133-147, 2023

Authors: Xiao, Yanjun | Li, Shifang | Zhang, Kun | Zhang, Yameng | Xiao, Yanchun

Article Type: Research Article

Abstract: Recovering low-quality waste heat using industrial waste heat is challenging, and the reuse technology needs to erupt. Moreover, the gas source of low-quality waste heat is relatively volatile, which makes it challenging to keep the actual working condition of the plant stable. Therefore, it is inspiring to research the robustness of root-waste heat power generation processed measurement and control system to improve the stability of the plant operation. Hence, in this paper, we have applied uncertainty theory to analyze it and formulate the uncertainty model based on the Bode diagram. We also proposed a control method based on the uncertainty …model, which combines robust control and internal model control to make the roots waste heat power generation system operate stably under the effect of external disturbances and changes of internal structure or parameters in actual operation. Experimental results show that the robust internal model control method has a speed deviation of no more than 7.9 r/min compared with the PID control method. The adjustment time to track the set value does not exceed 73.1 seconds within the allowed fluctuation range. The fluctuation variance is 30.95% of that of the PID controller. The dynamic performance is better, with strong anti-interference capability and significantly improved tracking performance. It ensures the stability of the roots-type waste heat utilization system, which is essential for future intelligent grid-connected power generation. Show more

Keywords: Waste heat power generation, uncertain theory, robust internal model control, roots power machine

DOI: 10.3233/JIFS-234416

Citation: Journal of Intelligent & Fuzzy Systems, vol. 46, no. 4, pp. 7969-7987, 2024

Authors: SUN, Fu-sheng | ZHAN, Zhong-ying | ZHANG, Kun-song | WANG, Yi

Article Type: Research Article

Abstract: In order to reduce the operation time and improve the extraction efficiency, ultrasonic energy by means of ultrasonic bath was used to the modified Tessier sequential extraction for speciation analysis of heavy metals in soil. Extractable contents of Cu, Fe, Mn, Ni, Pb and Zn were measured by atomic absorption spectroscopy (AAS). The merit of the ultrasonic extraction (UE) applied to the modified Tessier method is not only that the operation time for the first 4 fractions was reduced from ca.18 h to 8 h, comparing with conventional extraction (CE), but also the extraction efficiency was higher. The results for …both of UE and CE were consistent. The extractable Cu, Ni and Zn in the sample No.1 were mainly associated with the third fraction (Fe-Mn oxides fraction), and fourth fraction (organic matter fraction) in the sample No.2. The extractable Fe and Mn were all mainly associated with the third fraction, and Pb the fourth fraction in both of the samples. The effects of concentration of hydroxylamine chloride on the capability for the extraction of studied metals were also studied. Show more

Keywords: speciation analysis of heavy metal, sequential extraction, ultrasonic extraction, soil, atomic absorption spectrometry

Citation: Journal of Environmental Sciences, vol. 16, no. 6, pp. 957-961, 2004

Authors: Xu, Jifei | Zhang, Kun | Wang, Hongyan | Cui, Zhenzhen | Wu, Yi | Wang, Wanqin | Wang, Fan

Article Type: Research Article

Abstract: OBJECTIVE: To explore the clinical application of diffusion-weighted magnetic resonance imaging (DWI) in nasopharyngeal carcinoma (NPC) diagnosis, detection of lymph node metastasis, radiotherapy and prognosis. METHODS: Twenty patients with diagnosed NPC in an early stage of radiotherapy were enrolled in our department between May 2010 and May 2013. T1 and T2 weighted magnetic resonance imaging and DWI of the nasopharynx and neck were performed 1 week before radiotherapy, during radiotherapy at a dose of 60 Gy, and 1 month after radiotherapy. Pertinent measurements and related data were recorded. RESULTS: In comparison with that before radiotherapy, the ADC value of the nasopharyngeal …primary lesion increased significantly during radiotherapy at a dose of 60 Gy and at 1 month after radiotherapy (F = 187.160, P  = 0.000). When the dose of radiotherapy reached 60 Gy, the DWI signals from both the neck and the retropharyngeal lymph nodes were significantly lower than those before radiotherapy. CONCLUSION: DWI can be used for sensitive and accurate diagnosis of lymph node metastasis in the neck and retropharyngeal space, monitoring of the radiotherapy effect in early stages of NPC and development of new medical treatment strategies. Show more

Keywords: Magnetic resonance imaging, nasopharyngeal cancer, radiotherapy

DOI: 10.3233/XST-180441

Citation: Journal of X-Ray Science and Technology, vol. 27, no. 2, pp. 297-306, 2019

Authors: Wang, Junlei | Li, Guoping | Jin, Zunlong | Hu, Guobiao | Zhang, Kun | Zhang, Peng

Article Type: Research Article

Abstract: Harvesting energy from wind to supply low-power consumption devices has attracted numerous research interests in recent years. However, a traditional vortex-induced vibration energy harvester can only operate within a limited range of wind speed. Thus, how to broaden the effective wind speed range for energy harvesting is a challenging issue. In this paper, a slotted cylinder bluff body is proposed for being used in the design of a wind energy harvester. The physical prototype is manufactured and the wind tunnel test is performed for evaluating the actual performance of the prototyped energy harvester. The effect of the orientation of the …slot on the performance of the proposed energy harvester is experimentally investigated. As compared to the traditional counterpart without the slot at the lateral side of the bluff body, the proposed energy harvester demonstrates the superiority for realizing broadband energy harvesting. Due to the introduction of the slot, and by carefully tuning the orientation of the slot, both the vortex-induced vibration and the galloping phenomena can be stimulated within two neighboring wind speed ranges, leading to the formation of an extremely broad bandwidth for energy harvesting. Show more

Keywords: Wind energy harvesting, slotted bluff body, vortex-induced vibration, galloping

DOI: 10.3233/JAE-209314

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 64, no. 1-4, pp. 119-127, 2020

Authors: Zhang, Kun | Lin, Jun | Lin, Fan | Wang, Zhongyi | Zhang, Haicheng | Zhang, Shijie | Mao, Ning | Qiao, Guangdong

Article Type: Research Article

Abstract: BACKGROUND: Neoadjuvant chemotherapy (NAC) has been regarded as one of the standard treatments for patients with locally advanced breast cancer. No previous study has investigated the feasibility of using a contrast-enhanced spectral mammography (CESM)-based radiomics nomogram to predict pathological complete response (pCR) after NAC. OBJECTIVE: To develop and validate a CESM-based radiomics nomogram to predict pCR after NAC in breast cancer. METHODS: A total of 118 patients were enrolled, which are divided into a training dataset including 82 patients (with 21 pCR and 61 non-pCR) and a testing dataset of 36 patients (with 9 pCR and 27 non-pCR). The tumor …regions of interest (ROIs) were manually segmented by two radiologists on the low-energy and recombined images and radiomics features were extracted. Intraclass correlation coefficients (ICCs) were used to assess the intra- and inter-observer agreements of ROI features extraction. In the training set, the variance threshold, SelectKBest method, and least absolute shrinkage and selection operator regression were used to select the optimal radiomics features. Radiomics signature was calculated through a linear combination of selected features. A radiomics nomogram containing radiomics signature score (Rad-score) and clinical risk factors was developed. The receiver operating characteristic (ROC) curve and calibration curve were used to evaluate prediction performance of the radiomics nomogram, and decision curve analysis (DCA) was used to evaluate the clinical usefulness of the radiomics nomogram. RESULTS: The intra- and inter- observer ICCs were 0.769–0.815 and 0.786–0.853, respectively. Thirteen radiomics features were selected to calculate Rad-score. The radiomics nomogram containing Rad-score and clinical risk factor showed an encouraging calibration and discrimination performance with area under the ROC curves of 0.906 (95% confidence interval (CI): 0.840–0.966) in the training dataset and 0.790 (95% CI: 0.554–0.952) in the test dataset. CONCLUSIONS: The CESM-based radiomics nomogram had good prediction performance for pCR after NAC in breast cancer; therefore, it has a good clinical application prospect. Show more

Keywords: Breast cancer, neoadjuvant chemotherapy, pathological complete response, radiomics, contrast-enhanced spectral mammography

DOI: 10.3233/XST-221349

Citation: Journal of X-Ray Science and Technology, vol. 31, no. 4, pp. 669-683, 2023