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An Improved Method of Maximum Power Point Tracking Strategy for Wind Power Conversion System
CHEN Ran,CHEN Jie,CHEN Jia-wei,CHEN Zhi-hui,GONG Chun-ying,YAN Yang-guang 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5
The turbine speed loop adjustment is the key link of the designing of the controller for the fixed pitch variable speed wind energy conversion systems (WECS). Because of the strong nonlinear, big inertia and mechanical damping characteristics, it’s difficult to designing the controller of the wind power systems. In this paper, a small signal model is present, and based on the analyzing; a wind turbine speed loop regulator is designed. Then, a method of tracking the peak power conversion system is proposed, which is independent of the turbine parameters and air density. At last, simulation system is built, and the results of the simulation experiments show that, the performance of the controller algorithm meet the requirements of the MPPT without wind measurement.
Effect of the Circle-Grid Electrodes on Concentrated GaAs Solar Cell Efficiency
Chen-Chen Chung,Binh Tinh Tran,Ming-Hung Han,Kung-Liang Lin,Hung-Wei Yu,Yen-Teng Ho,Chun-Yen Chang,Edward Yi Chang 대한금속·재료학회 2014 ELECTRONIC MATERIALS LETTERS Vol.10 No.5
In this study, we investigate the effect of the shading factor of the front grid pattern on concentrated solar cell efficiency, taking the trade-off between the series resistance of the electrodes and the amount of incident light into consideration. We examine the thermal effect with regard to five different circle-grid electrode patterns of the front contact. The front contacts with different grid patterns affect the characteristics of light-concentratedtype GaAs single-junction solar cells. The device parameters analyzed include the open-circuit voltage (Voc), short-circuit current (Isc), fill factor (FF) and conversion efficiency (η). The results of our study show that for a concentration ratio greater than 60x with AM1.5G, the device with a shading factor of 7.1% has the best cell efficiency of 27.05%, due to the smaller current crowding at the center spot. The results indicate that the conversion efficiency of solar cells can be improved by establishing a compromise between the shading effect and the series resistance effect.
( Chen-hua Liu ),( Chi-yi Chen ),( Wei-wen Su ),( Chun-jen Liu ),( Ching-chu Lo ),( Ke-jhang Huang ),( Jyh-jou Chen ),( Kuo-chih Tseng ),( Chi-yang Chang ),( Cheng-yuan Peng ),( Yu-lueng Shih ),( Chia 대한간학회 2021 Clinical and Molecular Hepatology(대한간학회지) Vol.27 No.4
Background/Aims: Real-world studies assessing the effectiveness and safety of sofosbuvir/velpatasvir (SOF/VEL) plus ribavirin (RBV) for Child-Pugh B/C hepatitis C virus (HCV)-related cirrhosis are limited. Methods: We included 107 patients with Child-Pugh B/C HCV-related cirrhosis receiving SOF/VEL plus RBV for 12 weeks in Taiwan. The sustained virologic response rates at off-treatment week 12 (SVR<sub>12</sub>) for the evaluable population (EP), modified EP, and per-protocol population (PP) were assessed. The safety profiles were reported. Results: The SVR<sub>12</sub> rates in the EP, modified EP and PP were 89.7% (95% confidence interval [CI], 82.5-94.2%), 94.1% (95% CI, 87.8-97.3%), and 100% (95% CI, 96.2-100%). Number of patients who failed to achieve SVR<sub>12</sub> were attributed to virologic failures. The SVR<sub>12</sub> rates were comparable regardless of patient characteristics. One patient discontinued treatment because of adverse events (AEs). Twenty-four patients had serious AEs and six died, but none were related to SOF/VEL or RBV. Among the 96 patients achieving SVR<sub>12</sub>, 84.4% and 64.6% had improved Child-Pugh and model for endstage liver disease (MELD) scores. Multivariate analysis revealed that a baseline MELD score ≥15 was associated with an improved MELD score of ≥3 (odds ratio, 4.13; 95% CI, 1.16-14.71; P=0.02). Patients with chronic kidney disease (CKD) stage 1 had more significant estimated glomerular filtration rate declines than patients with CKD stage 2 (-0.42 mL/min/1.73 ㎡/month; P=0.01) or stage 3 (-0.56 mL/min/1.73 ㎡/month; P<0.001). Conclusions: SOF/VEL plus RBV for 12 weeks is efficacious and well-tolerated for Child-Pugh B/C HCV-related cirrhosis. (Clin Mol Hepatol 2021;27:575-588)
Chun-Sheng Chen,Fwu-Hsing Liu,Wei-Ren Chen 국제구조공학회 2017 Steel and Composite Structures, An International J Vol.23 No.3
In this paper, thermal effect on the vibration and stability of initially stressed sandwich plates with functionally graded material (FGM) face sheets is analyzed. Material properties of FGM face sheet are graded continuously in the thickness direction. The variation of FGM properties assumes a simple power law distribution in terms of the volume fractions of the constituents. The governing equations of arbitrarily initially-stressed sandwich plates including the effects of transverse shear deformation and rotary inertia are derived. The initial stress is taken to be a combination of a uniaxial extensional stress and a pure bending stress in the examples. The eigenvalue problems are formed to study the vibration and buckling characteristics of simple supported initially stressed FGM/metal/FGM plates. The effects of volume fraction index, temperature rise, initial stress and layer thickness of metal on the natural frequencies and buckling loads are investigated. The results reveal that the volume fraction index, initial stresses and layer thickness of metal have significant influence on the vibration and stability of sandwich plates with FGM face sheets.
Nonlinear vibration of hybrid composite plates on elastic foundations
Wei-Ren Chen,Chun-Sheng Chen,Szu-Ying Yu 국제구조공학회 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.37 No.4
In this paper, nonlinear partial differential equations of motion for a hybrid composite plate subjected to initial stresses on elastic foundations are established to investigate its nonlinear vibration behavior. Pasternak foundation and Winkler foundations are used to represent the plate-foundation interaction. The initial stress is taken to be a combination of pure bending stress plus an extensional stress in the example problems. The governing equations of motion are reduced to the time-dependent ordinary differential equations by the Galerkin's method. Then, the Runge-Kutta method is used to evaluate the nonlinear vibration frequency and frequency ratio of hybrid composite plates. The nonlinear vibration behavior is affected by foundation stiffness, initial stress, vibration amplitude and the thickness ratio of layer. The effects of various parameters on the nonlinear vibration of hybrid laminated plate are investigated and discussed.
Dynamic stability analysis of laminated composite plates in thermal environments
Chun-Sheng Chen,Wei-Ren Chen,Ting-Chiang Tsai,Ching-Long Wei,이재홍,전찬기 국제구조공학회 2013 Steel and Composite Structures, An International J Vol.15 No.1
This paper studies the dynamic instability of laminated composite plates under thermal and arbitrary in-plane periodic loads using first-order shear deformation plate theory. The governing partial differential equations of motion are established by a perturbation technique. Then, the Galerkin method is applied to reduce the partial differential equations to ordinary differential equations. Based on Bolotin's method, the system equations of Mathieu-type are formulated and used to determine dynamic instability regions of laminated plates in the thermal environment. The effects of temperature, layer number, modulus ratio and load parameters on the dynamic instability of laminated plates are investigated. The results reveal that static and dynamic load, layer number, modulus ratio and uniform temperature rise have a significant influence on the thermal dynamic behavior of laminated plates.
Wei-Chun Chen,Hsueh-Chou Lai,Wen-Pang Su,Mahalakshmi Palani,Kuan-Pin Su 대한신경정신의학회 2015 PSYCHIATRY INVESTIGATION Vol.12 No.1
Interferon (IFN)-α therapy for chronic hepatitis C virus (HCV) infection is frequently associated with major depressive episodes. Bupropion, a commonly used antidepressant agent, has recently found to have strong anti-inflammatory effects in animal models. Despite of the theoretical relevancy, the antidepressant effect of bupropion in IFN-alpha-induced depression has never been studied. Ten HCV patients with IFN-α-induced depression were recruited to receive 8-week bupropion treatment and were assessed every 2 weeks for depressive symptoms by the Hamilton rating scale for depression (HAMD) and somatic symptoms by the Neurotoxicity Rating Scale (NRS). Four of the 10 patients met the criteria for remission (total HAMD scores≤7), and 5 patients met the criteria for response (at least 50% reduction in total HAMD scores). In addition, 5 patients had 50% decreases in NRS for neuropsychiatric symptoms. This preliminary open-label study suggests that bupropion is effective in treating IFN-alpha-induced depressive and somatic symptoms.
Nonlinear vibration of hybrid composite plates on elastic foundations
Chen, Wei-Ren,Chen, Chun-Sheng,Yu, Szu-Ying Techno-Press 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.37 No.4
In this paper, nonlinear partial differential equations of motion for a hybrid composite plate subjected to initial stresses on elastic foundations are established to investigate its nonlinear vibration behavior. Pasternak foundation and Winkler foundations are used to represent the plate-foundation interaction. The initial stress is taken to be a combination of pure bending stress plus an extensional stress in the example problems. The governing equations of motion are reduced to the time-dependent ordinary differential equations by the Galerkin's method. Then, the Runge-Kutta method is used to evaluate the nonlinear vibration frequency and frequency ratio of hybrid composite plates. The nonlinear vibration behavior is affected by foundation stiffness, initial stress, vibration amplitude and the thickness ratio of layer. The effects of various parameters on the nonlinear vibration of hybrid laminated plate are investigated and discussed.
Wei Peng,Teng-wei Qiu,Chun-yan Yao,Chen Tang,Wei Zhang 한국정밀공학회 2015 International Journal of Precision Engineering and Vol. No.
This paper proposes a method of free-abrasive wire sawing in the magnetic field. Magnetic abrasive grains are absorbed on surface of the wire by magnetic force, and therefore more magnetic abrasive grains are carried into cutting area. This mechanism is helpful to improve the cutting performance of wire saws. Theoretical modeling of the movement trajectory of magnetic abrasive grains is done in the magnetic field, and it is also verified by observation experiments of movement trajectory of magnetic abrasive grains. Absorption angle, which is used as the indicator of adsorption capacity about magnetic abrasive grain on surface of the wire, is proposed in this paper. The effect of magnetic field intensity on absorption angle is analyzed through computer simulations and observation experiments. Practical experiments and cutting results show that the change of magnetic field intensity has a significant impact on cutting efficiency, surface roughness, and kerf width.