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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.
Chen, Nai-Zhi,Zhang, Xiu-Qing,Wei, Peng-Cheng,Chen, Qi-Jun,Ren, Fei,Chen, Jia,Wang, Xue-Chen Korean Society for Biochemistry and Molecular Biol 2007 Journal of biochemistry and molecular biology Vol.40 No.6
The HAP complex has been found in many eukaryotic organisms. HAP recognizes the CCAAT box present in the promoters of 30% of all eukaryotic genes. The HAP complex consists of three subunits - HAP2, HAP3 and HAP5. In this paper, we report the biological function of the AtHAP3b gene that encodes one of the HAP3 subunits in Arabidopsis. Compared with wild-type plants, hap3b-1 and hap3b-2 mutants exhibited a delayed flowering time under long-day photoperiod conditions. Moreover, the transcription levels of FT were substantially lower in the mutants than in the wild-type plants. These results imply that AtHAP3b may function in the control of flowering time by regulating the expression of FT in Arabidopsis. In a subsequent study, AtHAP3b was found to be induced by osmotic stress. Under osmotic stress conditions, the hap3b- 1 and hap3b-2 mutants flowered considerably later than the wild-type plants. These results suggest that the AtHAP3b gene plays more important roles in the control of flowering under osmotic stress in Arabidopsis.
( Na Chen ),( Min Jin ),( Hong Mei Qu ),( Zhi Qiang Chen ),( Zhao Li Chen ),( Zhi Gang Qiu ),( Xin Wei Wang ),( Jun Wen Li ) 한국미생물 · 생명공학회 2012 Journal of microbiology and biotechnology Vol.22 No.2
A strain of bacterium producing antifungal antibiotic was isolated and identification of the strain was attempted. We could identify the bacterium as being a Bacillus sp., based on morphological observation, physiological characteristics, and 16S rDNA sequence analysis, thus leading us to designate the strain as Bacillus sp. AH-E-1. The strain showed potent antibiotic activity against phytopathogenic and human pathogenic fungi by inducing mycelial distortion and swelling and inhibiting spore germination. The antibiotic metabolite produced by the strain demonstrated excellent thermal and pH (2-11) stability, but was labile to autoclaving. From these results, we could find a broader antifungal activity of Bacillus genus. Isolation and characterization of the active agent produced by the strain are under progress.
Zhi Chen,Pingyi Fan,Dapeng Oliver Wu,Khaled Ben Letaief 한국통신학회 2017 Journal of communications and networks Vol.19 No.6
In this work, a multiple-input multiple-output (MIMO)broadcast channel under the energy harvesting (EH) constraintand the peak power constraint is investigated. The transmitteris equipped with a hybrid energy storage system consisting of aperfect super capacitor (SC) and an inefficient battery, where bothelements are with limited energy storage capacities. In addition,the effect of data processing circuit power consumption is also addressed. To be specific, two extreme cases are studied here, wherethe first assumes ideal/zero circuit power consumption and the secondconsiders a positive constant circuit power consumption wherethe circuit is always operating at its highest power level. Theperformance of these two extreme cases hence serve as the upperbound and the lower bound of the system performance in practice,respectively. In this setting, the offline scheduling with idealand maximum circuit power consumption models are investigated. Their corresponding optimization problems are formulated andsolved in terms of weighted sum-throughput. Further, we extendto a general circuit power consumption model. To complement thiswork, some intuitive online policies are presented for all cases. Interestingly,for the case with maximum circuit power consumption,a close-to-optimal online policy is presented and its performance isshown to be comparable to its offline counterpart in the numericalresults.
RASAL1 Attenuates Gastric Carcinogenesis in Nude Mice by Blocking RAS/ERK Signaling
Chen, Hong,Zhao, Ji-Yi,Qian, Xu-Chen,Cheng, Zheng-Yuan,Liu, Yang,Wang, Zhi Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.3
Recent studies have suggested that the RAS protein activator like-1 (RASAL1) functions as a tumor suppressor in vitro and may play an important role in the development of gastric cancer. However, whether or not RASAL1 suppresses tumor growth in vivo remains to be determined. In the present study, we investigated the role of RASAL1 in gastric carcinogenesis using an in vivo xenograft model. A lentiviral RASAL1 expression vector was constructed and utilized to transfect the human poorly differentiated gastric adenocarcinoma cell line, BGC-823. RASAL1 expression levels were verified by quantitative real-time RT-PCR and Western blotting analysis. Then, we established the nude mice xenograft model using BGC-823 cells either over-expressing RASAL1 or normal. After three weeks, the results showed that the over-expression of RASAL1 led to a significant reduction in both tumor volume and weight compared with the other two control groups. Furthermore, in xenograft tissues the increased expression of RASAL1 in BGC-823 cells caused decreased expression of p-ERK1/2, a downstream moleculein the RAS/RAF/MEK/ERK signal pathway. These findings demonstrated that the over-expression of RASAL1 could inhibit the growth of gastric cancer by inactivation of the RAS/RAF/MEK/ERK pathway in vivo. This study indicates that RASAL1 may attenuate gastric carcinogenesis.
Distortion Minimization for Relay Assisted Wireless Multicast
Zhi Chen,Pin-Han Ho,Limei Peng 한국통신학회 2018 Journal of communications and networks Vol.20 No.1
The paper studies the scenario of wireless multicast witha single transmitter and a relay that deliver scalable source symbolsto the receivers in a decode-and-forward (DF) fashion. Withthe end-to-end mean square error distortion (EED) as performancemetric, we firstly derive the EED expression for the L-resolutionscalable source symbol for any receiver. An optimization problemin minimizing the weighted EED is then formulated for finding thepower allocations for all resolution layers at the transmitter andthe relay. Due to nonlinearity of the formulations, we solve the formulatedoptimization problems using a generalized programmingalgorithm for obtaining good sub-optimal solutions. Case studiesare conducted to verify the proposed formulations and solution approaches. The results demonstrate the advantages of the proposedstrategies in the relay-assisted wireless networks for scalable sourcemulticast.