Dual-Phase Shifting Strategy for CLLC Resonant Converters

Wang Dangshu,Zhao Licong,Chang Menghu,Yang Yuxuan,Guan Zhimin,Zhang Ruchuan,Wang Xinxia 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.4

The CLLC resonant converter has the advantages of bidirectional power transmission, natural soft switching, and wide range voltage output. However, the gain curve is relatively smooth during high-frequency light-load operation, and it is diffi cult to adjust through frequency conversion; the traditional fundamental harmonic approximation (FHA) method has a large error in calculating the gain at a position away from the resonance point, which brings diffi culties to the design. In order to better design the converter, this paper proposes a dual phase-shift (DPS) control method based on time-domain analysis, which can achieve a wide voltage range output without losing soft switching, and has constant current source output characteristics. Firstly, the time-domain model of the CLLC converter is analyzed, and the output voltage gain and soft switching range under DPS control are solved; then a simulation is built for verifi cation; fi nally, a 200/80 V, rated power 500 W full-bridge CLLC resonant converter experimental prototype is built. The experimental results prove that the converter has good soft switching range and constant current source output characteristics.

Effects of solvent extraction on the microstructure of bituminous coal-based graphite

Wang Lipeng,Yao Zongxu,Guo Zhimin,Shen Xiaofeng,Li Zhiang,Zhou Zhengqi,Wang Yuling,Yang Jian-Guo 한국탄소학회 2022 Carbon Letters Vol.32 No.3

Coal-based graphite has become the main material of emerging industries. The microstructure of coal-based graphite plays an important role in its applications in many fields. In this paper, the effect of carbon disulfide/N-methyl-2-pyrrolidone solvent mixture extraction on the microstructure of bituminous coal-based graphite was systematically studied through preliminary extraction coupled with high-temperature graphitization. The graphitization degree g (75.65%) of the coal residue-based graphite was significantly higher than that of the raw coal-based graphite. The crystallite size La of the coal residue-based graphite was reduced by 47.06% compared with the raw coal-based graphite. The ID/ IG value of the coal residue-based graphite is smaller than that of the raw coal-based graphite. The specific surface area (16.72 m2/g) and total pore volume (0.0567 m3/g) of the coal residue-based graphite are increased in varying degrees compared with the raw coal-based graphite. This study found a carbon source that can be used to prepare coal-based graphite with high graphitization degree. The results are expected to provide a theoretical basis for further clean and efficient utilization of the coal residue resources.

Tractive performance evaluation of seafloor tracked trencher based on laboratory mechanical measurements

Wang, Meng,Wang, Xuyang,Sun, Yuanhong,Gu, Zhimin The Society of Naval Architects of Korea 2016 International Journal of Naval Architecture and Oc Vol.8 No.2

To evaluate the tractive performance of tracked trencher on seafloor surface, a new shear stress-displacement empirical model was proposed for saturated soft-plastic soil (SSP model). To validate the SSP model, a test platform, where track segment shear test can be performed in seafloor soil simulacrum (bentonite water mixture), was built. Series shear tests were carried out. Test results indicate that the SSP model can describe the mechanical behavior of track segment with good approximation in seafloor soil simulacrum. Through analyzing the main external forces applied to seafloor tracked trencher during the uniform linear trenching process, a drawbar pull prediction model was deduced with the SSP model. A tracked walking mechanism of the seafloor tracked trencher prototype was built, and verification tests were carried out. Test results indicate that this prediction model was feasible and effective; moreover, from another side, this conclusion also proved that the SSP model was effective.

Correction to: Effects of solvent extraction on the microstructure of bituminous coal‑based graphite

Lipeng Wang,Zongxu Yao,Zhimin Guo,Xiaofeng Shen,Zhiang Li,Zhengqi Zhou,Yuling Wang,Jian‑Guo Yang 한국탄소학회 2022 Carbon Letters Vol.32 No.3

Tractive performance evaluation of seafloor tracked trencher based on laboratory mechanical measurements

Meng Wang,Xuyang Wang,Yuanhong Sun,Zhimin Gu 대한조선학회 2016 International Journal of Naval Architecture and Oc Vol.8 No.2

To evaluate the tractive performance of tracked trencher on seafloor surface, a new shear stress-displacement empirical model was proposed for saturated soft-plastic soil (SSP model). To validate the SSP model, a test platform, where track segment shear test can be performed in seafloor soil simulacrum (bentonite water mixture), was built. Series shear tests were carried out. Test results indicate that the SSP model can describe the mechanical behavior of track segment with good approximation in seafloor soil simulacrum. Through analyzing the main external forces applied to seafloor tracked trencher during the uniform linear trenching process, a drawbar pull prediction model was deduced with the SSP model. A tracked walking mechanism of the seafloor tracked trencher prototype was built, and verification tests were carried out. Test results indicate that this prediction model was feasible and effective; moreover, from another side, this conclusion also proved that the SSP model was effective.

3D printed MXene (Ti2AlN)/polycaprolactone composite scaffolds for in situ maxillofacial bone defect repair

Zhimin Xu,Yingxin Zhang,Huanyan Dai,Yu Wang,Yujie Ma,Shuang Tan,Bing Han 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.114 No.-

Obtaining a safe and reliable scaffold that can be rapidly fabricated and used for clinical bone defect repairhas always been a challenge. In this study, polycaprolactone (PCL) composite scaffolds with various MXene(Ti2AlN) contents were prepared using 3D printing technology. The effects of different contents of Ti2AlNon the mechanical properties, hydrophilicity, cytocompatibility, and osteogenic differentiation abilitywere systematically studied and analysed. In vitro experiments showed that scaffolds containing 5%Ti2AlN (PCL@5#Ti2AlN) obtained the best cell adhesion and proliferation ability and significantly upregulatedthe alkaline phosphatase (ALP) level. In vivo experiments of tibial defect repair in rats showed thatthe PCL scaffold containing 5% Ti2AlN (PCL@5#Ti2AlN) could significantly promote the formation of newbone, and the experimental results of rabbit maxillofacial bone defect repair further proved that thePCL@5#Ti2AlN scaffold could effectively promote the repair of bone defects. Transcriptome analysis indicatedthat Ti2AlN may promote osteogenic differentiation by the Wnt/b-catenin signaling pathway andcalcium-binding proteins. These findings suggest that Ti2AlN/PCL composite scaffolds with improvedin situ bone repair ability represent an intelligent strategy for bone defect repair.

Fed-batch Cultivation of Escherichia coli YK537 (pAET-8) for Production of phoA Promoter-controlled Human Epidermal Growth Factor

Wang Yonggang,Du Peng,Gan Renbao,Li Zhimin,Ye Qin The Korean Society for Biotechnology and Bioengine 2005 Biotechnology and Bioprocess Engineering Vol.10 No.2

Secretion of the expressed heterologous proteins can reduce the stress to the host cells and is beneficial to their recovery and purification. In this study, fed-batch cultures of Escherichia coli YK537 (pAET-8) were conducted in a 5-L fermentor for the secretory production of human epidermal growth factor (hEGF) whose expression was under the control of alkaline phosphatase promoter. The effects of feeding of glucose and complex nitrogen sources on hEGF production were investigated. When the fed-batch culture was conducted in a chemically de-fined medium, the cell density was 9.68 g/L and the secreted hEGF was 44.7 mg/L in a period of 60 h. When a complex medium was used and glucose was added in pH-stat mode, the secreted hEGF was improved to 345 mg/L. When the culture was fed with glucose at a constant specific rate of $0.25\;gg^{-1}h^{-1}$, hEGF reached 514 mg/L. The effects of adding a solution containing yeast extract and tryptone were further studied. Different rate of the nitrogen source feeding resulted in different levels of phosphate and acetic acid formation, thus affected hEGF expression. At the optimal feeding rate, hEGF production achieved 686 mg/L.

Spinal Tuberculosis: Always Understand, Often Prevent, Sometime Cure

Zhimin Pan,Zujue Cheng,Jeffrey C. Wang,Wei Zhang,Min Dai,Bin Zhang 대한척추신경외과학회 2021 Neurospine Vol.18 No.3

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Characterization of a strong green tissue-specific motif in rice photosystem I gene promoter Ppsak

Zhimin Lin,Jingwan Yan,Huanxin Yan,Feng Wang 한국식물생명공학회 2017 Plant biotechnology reports Vol.11 No.2

Characterization of green tissue-specific promoters helps facilitate genetic improvement in crops. Here, we isolated a novel green tissue-specific expression gene Psak encoding photosystem I protein in rice through RTPCR analysis. The 5′ flanking region from −635 to +60 (transcription start site of Psak as +1) covering parts of Psak gene and its promoter Ppsak was identified as be critical for green tissue-specific expression (including leaves and stems) in rice. Further promoter deletion analyses demonstrated that the promoter region from −559 to −232 was necessary and sufficient for green tissue-specific expression of Psak gene. Histochemical assays showed that the GUS expression of this 267-bp region was highly presented in leaves and stems, but reduced or absent in other tissues examined. The GUS expression level of this core promoter region could be 14.6- to 21.6-fold higher than that of the full-length region of Ppsak promoter in leaves and stems. These results combined with cis-acting elements prediction in Ppsak promoter suggested that the TCT motif located in this promoter played a key role in strong green tissue-specific expression.

An Effective and Green Method for the Extraction and Purification of Aglycone Isoflavones from Soybean

Mengfan Wang,Jian Guo,Wei Qi,Rongxin Su,Zhimin He 한국식품과학회 2013 Food Science and Biotechnology Vol.22 No.3

In this paper, an effective and green strategy was developed to obtain aglycone isoflavones from soybean through the extraction, hydrolysis, and purification steps. Firstly, a novel ethanol-alkaline extraction method was designed and optimized. The high extraction yield (94.34%)of isoflavones was achieved under the optimal extraction conditions of pH 9.0, 70oC, 60 min, ethanol concentration of 65%, and 1:15 of the solid to liquid ratio. Then, the cellulase (GC-220) was used instead of traditional β-glucosidase to hydrolyze the glycoside isoflavones into aglycone isoflavones which gave an excellent conversion of 95%. Finally, the crude aglycone isoflavones have been purified by an environmental-friendly procedure comprised of ethanol precipitation, ethyl acetate extraction, and water rinse. The final amount of aglycone isoflavones obtained was 1.279 mg for every gram of defatted soybean by this strategy, and the final recovery, and purity of aglycone isoflavones could achieve 80.38 and 87.21%, respectively.