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- 저자 : Yanjun Hu (검색결과 5 건)
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Impedance Coordinative Control for Cascaded Converter in Bidirectional Application
Yanjun Tian,Fujin Deng,Zhe Chen,Xiaofeng Sun,Yanting Hu 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
Two stage cascaded converters are widely used in bidirectional applications, but the negative impedance may cause system instability. Actually the impedance interaction is much different between forward power flow and reversed power flow, which will introduce more uncertainty to the system stability. This paper proposes a control method for the constant power controlled converter in cascaded system, and consequently it can change the negative impedance of constant power converter into resistive impedance, which will improve the cascaded system stability, as well as merge the impedance difference between forward and reversed power flow. This paper addresses the analysis with the topology of cascaded dualactive - bridge converter (DAB) with inverter, and the proposed control method can also be implemented in unidirectional applications and other general cascaded converter system. The effectiveness has been validated by both simulation and experimental results.
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Impedance Interaction Modeling and Analysis for Bidirectional Cascaded Converters
Yanjun Tian,Fujin Deng,Zhe Chen,Xiaofeng Sun,Yanting Hu 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
For the cascaded converter system, the output impedance of source converter interacts with the input impedance of load converter, and the interaction may cause the system instability. In bidirectional applications, when the power flow is reversed, the impedance interaction also varies, which brings more uncertainty to the system stability. An investigation is performed here for showing that the forward and reverse interactions are prominently different in terms of dynamics and stability even though the cascaded converter control remains unchanged. An important guideline has been drawn for the control of the cascaded converter. That is when voltage mode converter working as the load converter; the constant power mode converter as the source converter, the system is more stable. The concluded findings have been verified by simulation and experimental results.
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Energy Efficient Feedback Design for Coordinated Multi-Point Transmission in Downlink
Yi Wang,Yanjun Hu,Yiqing Zhou 보안공학연구지원센터 2015 International Journal of Signal Processing, Image Vol.8 No.6
Coordinated multi-point (CoMP) has been raised to increase the average cell throughput and the cell-edge user throughput. However, the energy consumption of mobile stations (MSs) is a key problem restricting the wide application of CoMP systems. Considering the energy consumption of feeding back channel state information (CSI) by MSs and the influence of CSI accuracy on the throughput of system, it is proposed to measure the relationship between feedback energy consumption and throughput with energy efficiency feedback utility (EEFU) function which can adapt to different application scenes by adjusting utilization coefficient. The feedback utilization of two precoders in CoMP systems is analyzed respectively, including the optimization allocation of feedback bits with utility function. The complete EEFU optimized expression and the optimizing flow path satisfying the actual application demands of CoMP systems are then derived. The simulation results illustrate the practicability and necessity of the EEFU function and verify the performance of EEFU with different precoders.
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Zhiyu Zhou,Yanjun Hu,Jiangfei Ji,Yaming Wang,Zefei Zhu,Donghe Yang,Ji Chen 한국인터넷정보학회 2022 KSII Transactions on Internet and Information Syst Vol.16 No.8
Visual servoing (VS) based on the Kalman filter (KF) algorithm, as in the case of KF-based image-based visual servoing (IBVS) systems, suffers from three problems in uncalibrated environments: the perturbation noises of the robot system, error of noise statistics, and slow convergence. To solve these three problems, we use an IBVS based on KF, African vultures optimization algorithm enhanced extreme learning machine (AVOA-ELM), and fuzzy logic (FL) in this paper. Firstly, KF online estimation of the Jacobian matrix. We propose an AVOA-ELM error compensation model to compensate for the sub-optimal estimation of the KF to solve the problems of disturbance noises and noise statistics error. Next, an FL controller is designed for gain adaptation. This approach addresses the problem of the slow convergence of the IBVS system with the KF. Then, we propose a visual servoing scheme combining FL and KF-AVOA-ELM (FL-KF-AVOA-ELM). Finally, we verify the algorithm on the 6-DOF robotic manipulator PUMA 560. Compared with the existing methods, our algorithm can solve the three problems mentioned above without camera parameters, robot kinematics model, and target depth information. We also compared the proposed method with other KF-based IBVS methods under different disturbance noise environments. And the proposed method achieves the best results under the three evaluation metrics.
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Fenghu Li,Fan Mei,Shuishui Yin,Yanjun Du,Lili Hu,Wei Hong,Jiehui Li 대한부인종양학회 2024 Journal of Gynecologic Oncology Vol.35 No.1
Objective: To compare the efficacy and safety of neoadjuvant chemotherapy combined withconcurrent chemoradiotherapy (NACT+CCRT) vs. concurrent chemoradiotherapy (CCRT) inlocally advanced cer vical cancer (LACC) patients with large tumor masses. Methods: LACC patients with localized tumor diameter >4 cm, were randomly allocated in anunblinded 1:1 ratio to NACT+CCRT or CCRT groups. Patients in the NACT+CCRT group weregiven paclitaxel combined with cisplatin (TP) NACT ever y 3 weeks for 2 cycles, followed byCCRT, with the chemotherapy regimen the same as for NACT. CCRT group were given CCRTwith the same as for NACT. Results: From March 1, 2019, to June 30, 2021, 146 patients were included in the finalanalysis. Sixty-eight (93.2%) patients in the NACT+CCRT group and 66 (90.4%) patientsin the CCRT group completed the expected treatment course. The complete response (CR)rate in the NACT+CCRT group was significantly higher than in the CCRT group (87.7% vs. 67.6%, χ2=54.540, p=0.000). In the NACT+CCRT group, the 1- and 2-year overall sur vival(OS) rates were significantly higher than those in the CCRT group (96% vs. 89% and 89%vs. 79%, χ2=5.737, p=0.017). Additionally, the rate of recurrences and distant metastaseswas significantly lower in the NACT+CCRT group than in the CCRT group (4.11% vs. 7.35%,χ 2=4.059, p=0.021). Most treatment-related adverse events in both groups were grade 3. Conclusion: Compared to CCRT, NACT+CCRT might improve the treatment completionrate, increase CR rate and 1- and 2-year OS rates, and reduce distant metastases rate for LACCpatients with large tumor masses.
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