An Improved Active Damping Method with Capacitor Current Feedback

Yi-Wen Geng,Ya-Wen Qi,Hai-Wei Liu,Fei Guo,Peng-Fei Zheng,Yong-Gang Li,Wen-Ming Dong 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.2

Proportional capacitor current feedback active damping (CCFAD) has a limited valid damping region in the discrete time domain as (0, fs/6). However, the resonance frequency (fr) of an LCL-type filter is usually designed to be less than half the sampling frequency (fs) with the symmetry regular sampling method. Therefore, (fs/6, fs/2) becomes an invalid damping region. This paper proposes an improved CCFAD method to extend the valid damping region from (0, fs/6) to (0, fs/2), which covers all of the possible resonance frequencies in the design procedure. The full-valid damping region is obtained and the stability margin of the system is analyzed in the discrete time domain with the Nyquist criterion. Results show that the system can operate stably with the proposed CCFAD method when the resonance frequency is in the region (0, fs/2). The performances at the steady and dynamic state are enhanced by the selected feedback coefficient H and controller gain Kp. Finally, the feasibility and effectiveness of the proposed CCFAD method are verified by simulation and experimental results.

An Improved Active Damping Method with Capacitor Current Feedback

Geng, Yi-Wen,Qi, Ya-Wen,Liu, Hai-Wei,Guo, Fei,Zheng, Peng-Fei,Li, Yong-Gang,Dong, Wen-Ming The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.2

Proportional capacitor current feedback active damping (CCFAD) has a limited valid damping region in the discrete time domain as (0, $f_s/6$. However, the resonance frequency ($f_r$) of an LCL-type filter is usually designed to be less than half the sampling frequency ($f_s$) with the symmetry regular sampling method. Therefore, ($f_s/6$, $f_s/2$) becomes an invalid damping region. This paper proposes an improved CCFAD method to extend the valid damping region from (0, $f_s/6$ to (0, $f_s/2$), which covers all of the possible resonance frequencies in the design procedure. The full-valid damping region is obtained and the stability margin of the system is analyzed in the discrete time domain with the Nyquist criterion. Results show that the system can operate stably with the proposed CCFAD method when the resonance frequency is in the region (0, $f_s/2$). The performances at the steady and dynamic state are enhanced by the selected feedback coefficient H and controller gain $K_p$. Finally, the feasibility and effectiveness of the proposed CCFAD method are verified by simulation and experimental results.

Continuous Conversion of Rice Starch Hydrolysate to 2-keto-D-gluconic Acid by Arthrobacter globiformis C224

Wen-Hua Teng,Wen-Jing Sun,Bin Yu,Fengjie Cui,Jing-Ya Qian,Jingze Liu,Liang Wang,Xiang-Hui Qi,Hua Wei 한국생물공학회 2013 Biotechnology and Bioprocess Engineering Vol.18 No.4

A continuous conversion process of rice starch hydrolysate to 2-keto-D-gluconic acid (2KGA) by Arthrobacter globiformis C224 was developed. Its feasibility for industrial application was also evaluated. Results showed that the initial cell concentration exceeding 1.25 g/L met the continuous 2KGA production at a stable dilution rate and media composition, while the dilution rate and feeding glucose concentration had a significant effect on 2KGA production performance. The optimal operating parameters were obtained as: 0.090/h of dilution rate and 171.0 g/L of feeding glucose concentration. Under these conditions, the steady state had a produced 2KGA concentration of 124.74 g/L, average volumetric productivity of 11.23 g/L/h,and yield of 0.97 g/g. In conclusion, continuous 2KGA production by the A. globiformis C224 strain would be a superior industrial process for the production of 2KGA in terms of its high 2KGA productivity and yield.

Effect of Different Pressing Processes and Density on Dimensional Stability and Mechanical Properties of Bamboo Fiber-based Composites

( Ya-hui Zhang ),( Yu-xiang Huang ),( Hong-xia Ma ),( Wen-ji Yu ),( Yue Qi ) 한국목재공학회 2018 목재공학 Vol.46 No.4

In this study, the dimensional stability and mechanical properties of bamboo fiber-based composites (BFBCs) were studied at two pressing manufacturing processes, i.e., hot- and cold- pressing, and were compared with three density parameters (1.0, 1.1, and 1.2 kg/㎥). Width swelling ratio (WSR), thickness swelling ratio (TSR), and water absorption ratio (WAR) were calculated for water immersions of 4 and 28 h. WSR, TSR, and WAR for specimens immersed for 28 h were higher than those for 4 h treatment, which shows that the immersion time has a significant influence on the dimensional stabilities of BFBCs. Moreover, the positive linear relations between density and dimensional were observed at both the pressing ways, indicating that the WSR, TSR, and WAR decreased with an increase in the density of BFBCs. The compressive strength, shear strength, modulus of rupture (MOR), and modulus of elasticity (MOE) were determined. The compressive strength, MOR, and MOE of hot-pressed specimens were significantly higher than those for the cold-pressed specimens, which are also directly proportional to density. Moreover, the samples with the highest density of 1.2 kg/㎥ performed high values on mechanical properties in both the manufacturing methods.

QTLs of Cold Tolerance-Related Traits at the Booting Stage for NIL-RILs in Rice Revealed by SSR

Ya Wen Zeng,Shu Ming Yang,Hong Cui,Xiao Juan Yang,Li Ming Xu,Juan Du,Xiao Ying Pu,Zi Chao Li,Zai Quan Cheng,Xing Qi Huang 한국유전학회 2009 Genes & Genomics Vol.31 No.2

QTLs for cold tolerance-related traits at the booting stage using balanced population for 1525 recombinant inbred lines of near-isogenic lines (viz. NIL-RILs for BC5F3 and BC5F4 and BC5F5) over 3 years and two locations by backcrossing the strongly cold-tolerant landrace (Kunmingxiaobaigu) and a cold-sensitive cultivar (Towada) was analyzed. In this study, 676 microsatellite markers were employed to identify QTLs conferring cold tolerance at booting stage. Single marker analysis revealed that 12 markers associated with cold tolerance on chromosome 1, 4 and 5. Using a LOD significance threshold of 3.0, compositive interval mapping based on a mixed linear model revealed eight QTLs for 10 cold tolerance-related traits on chromosomes 1, 4, and 5. They were tentatively designated qCTB-1-1, qCTB-4-1, qCTB-4-2, qCTB-4-3, qCTB-4-4, qCTB-4-5, qCTB-4-6, and qCTB-5-1. The marker intervals of them were narrowed to 0.3-6.8 cM. Genetic distances between the peaks of the QTL and nearest markers varied from 0 to 0.04 cM. We were noticed in some traits associated cold tolerance, such as qCTB-1-1 for 5 traits (plant height, panicle exsertion, spike length, blighted grains per spike and spikelet fertility), qCTB-4-1 for 8 traits (plant height, node length under spike, leaf length, leaf width, spike length, full grains per spike, total grains per spike and spikelet fertility), qCTB-4-2 for 3 traits (spike length, full grains per spike and spikelet fertility), qCTB-5-1 for 5 traits (plant height, panicle exsertion, blighted grains per spike, full grains per spike and spikelet fertility). The variance explained by a single QTL ranged from 0.80 to 16.80%. Three QTLs (qCTB-1-1, qCTB-4-1, qCTB-4-2) were detected in two or more trials. Our study sets a foundation for cloning cold-tolerance genes and provides opportunities to understand the mechanism of cold tolerance at the booting stage.

Influence of a Novel Mold Inhibitor on Mechanical Properties and Water Repellency of Bamboo Fiber-based Composites

( Yue Qi ),( Yu-Xiang Huang ),( Hong-Xia Ma ),( Wen-Ji Yu ),( Nam-Hun Kim ),( Ya-Hui Zhang ) 한국목재공학회 2019 목재공학 Vol.47 No.3

Effects of a novel mold inhibitor specifically for bamboo, on the properties of composite products have been confirmed in this study. The mechanical and dimensional stability properties of bamboo fiber-based composites (BFBCs) from different bamboo species were also investigated. The results showed that Burmanica Gamble possessed the highest values of modulus of elasticity (MOE) of 33.2 GPa, modulus of rupture (MOR) of 286.9 MPa, compressive strength of 182.6 MPa and shear strength of 24.0 MPa. By contrast, Phyllostochys heterocycla among all of species showed the lowest MOE of 16.3 GPa, MOR of 170.3 MPa and compressive strength of 128.9 MPa were the lowest among all of species. Moreover, there is a remarkable variation in the swelling and water absorption between the samples with 4 h and 28 h water immersion treatment, especially Phyllostachys iridenscens. Overall, the results suggested that TCIT (Tebuconazole and 3(2H)-isothiazolone) had no significant effect on the mechanical properties compared with the control condition, and it would be utilized as an antimould of BFBCs manufacturing.

Response Surface Optimized Extraction of Flavonoids from Mimenghua and Its Antioxidant Activities In vitro

Lei Guo,Wen-Cheng Zhu,Ya-Ting Liu,Jiu-Yu Wu,An-Qi Zheng,Yan-Li Liu 한국식품과학회 2013 Food Science and Biotechnology Vol.22 No.5

The optimized extraction conditions of total flavonoids from mimenghua were determined by the Box-Behnken design and response surface methodology. The optimal conditions to achieve the maximum yield of flavonoids were determined as follows: ethanol concentration 68%(v/v), extraction temperature 72.4oC, liquid/material ratio 48:1mL/g, and extraction time 2 h. Under the optimized conditions, the extraction ratio of flavonoids was 15.44%. The crude extract was then purified by AB-8 macroporous adsorption resin, the flavonoids content in the purified extract increased to 90.43%. The antioxidant activities of the purified flavonoids were evaluated in vitro by scavenging capabilities of DPPH radical, hydroxyl radical and superoxide radical, reducing power and total antioxidant capacity. The results showed that the flavonoids have significant antioxidant activities, which can be used as a source of potential antioxidant.

Glycerol steam reforming over Ni/γ-Al2O3 catalysts modified by metal oxides

Cheng-Hua Xu,Zun-Yu Huang,Chuan-Qi Liu,Hui-Wen Xiao,Jun Chen,Yong-Xiang Zhang,Ya-Cong Lei 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.3

The metal oxides modified Ni/γ-Al2O3 catalysts for glycerol steam reforming were prepared by impregnation. Characterization results of fresh catalysts indicated that the molybdates modification abated the acidity and the stronger metal-support interaction of Ni/γ-Al2O3 catalysts, leading to a stable catalytic activity. Especially, NiMoLa-CaMg/γ-Al2O3 (NiMoLa/CMA) catalyst exhibited no deactivation along with glycerol complete conversion to stable gaseous products containing 69% H2, 20% CO and 10% CO2 during time-on-stream of 42 h. TPO of spent Ni/γ-Al2O3catalysts modified by different components showed that the carbon deposit on acidic sites and NiAl2O4 species led to catalysts deactivation. A lower reforming temperature and a higher LHSV and glycerol content were helpful to the production of syngas from GSR over NiMoLa/CMA; the reverse conditions would improve the formation of H2.