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A Novel Inverter Topology and its Power Balancing Optimization
Xue Bo,Gong Renxi,Liu Jianfeng,Zhang Zhiang 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.3
Aiming at the problems of poor quality of the output voltage waveform of the existing multi-level inverters and many switching devices and DC power supplies, a novel cascadable basic unit topology is proposed. The proposed topology consists of three input DC power supplies and eight switches, forming an H half-bridge and an auxiliary bidirectional switch by adding 2 DC power supplies in the traditional H-bridge topology. The advantage of this topology is that it can be used in symmetric and asymmetric voltage source configurations, which can effectively extend the life of the inverters and reduce the production cost. The basic unit topology is cascaded in series to form a multilevel inverter topology to generate higher voltage levels, and its power balance strategy is proposed. The strategy can be described as follows: Firstly, several groups of pulse signals are generated by the traditional LS-PWM modulation strategy in which the modulation wave is compared with several groups of carriers, then a logic operation on the pulse signals is performed to obtain the drive signal of each switch, and the inverter is driven to achieve output power balance. A lot of Simulation and experiments verify the viability of the proposed topology and the effectiveness of the equalization strategy.
Sun, Xue-Bo,Gong, Chi,Liu, Peng 사회혁신기업연구원 2023 혁신기업연구 Vol.8 No.4
Competition among enterprises is becoming more and more intense, equity incentives as one of the main ways of corporate governance, is the most commonly used incentives, equity incentives is the enterprise in order to motivate and retain the core talent and the implementation of long-term incentives for employees. It is of great significance to the development of enterprises. In this paper, we use CiteSpace software to visualise and analyse the domestic research on equity incentives, mainly from the number of articles, authors, keyword clustering and keyword co-occurrence of four aspects of analysis and discussion. It is found that: the number of articles shows an upward trend; there is a lack of close cooperation between core authors; the research hotspots related to equity incentives are mainly the form of incentives, listed companies, corporate governance and corporate performance, etc. The future direction of the research is tilted towards the themes of corporate innovation and investment to explore the impact of the equity incentive approach on corporate innovation and R&D investment.
Chemical Constituents from the Aerial Parts of Isodon coetsa and their Cytotoxicity
Wei Zhao,Jian Xin Pu,Xue Du,Yong Zhao,Fei He,Hai Bo Zhang,Yong Bo Xue,Wei Lie Xiao,Han Dong Sun,Ying Li Wu,Guo Qiang Chen 대한약학회 2011 Archives of Pharmacal Research Vol.34 No.12
Three new compounds (1-3), including a neolignan, a triterpenoid, and a diterpenoid, together with twenty known compounds (4-23), were isolated from the aerial parts of Isodon coetsa. Their structures and relative configurations were elucidated on the basis of spectroscopic data. Compounds 1, 3, 5-9, 11-13, 16-17, and 19-23 were evaluated for their cytotoxicity against HT-29, BEL-7402, and SK-OV-3 human tumor cell lines. Compound 7 showed significant inhibitory effects on all three types of cells, with IC50 values of 2.52, 3.06, 2.14 μM, respectively.
( Xue Feng Han ),( Bo Kun Lin ),( Gan Ji Ru ),( Zhi Biao Zhang ),( Yan Liu ),( Zhong Hu ) 한국미생물 · 생명공학회 2014 Journal of microbiology and biotechnology Vol.24 No.2
Enteromorpha polysaccharides (EP) extracted from green algae have displayed a wide variety of biological activities. However, their high molecular weight leads to a high viscosity and low solubility, and therefore, greatly restrains their application. To solve this problem, bacteria from the surface of Enteromorpha were screened, and an Alteromonas macleodii strain B7 was found to be able to decrease the molecular weight of EP in culture media. Proteins harvested from the supernatant of the A. macleodii B7 culture were subjected to native gel electrophoresis, and a band corresponding to the Enteromorpha polysaccharide lyase (EPL) was detected by activity staining. The enzyme identity was subsequently confirmed by MALDI-TOF/TOF mass spectrometry as the putative α-amylase reported in A. macleodii ATCC 27126. The amylase gene (amySTU) from A. macleodii B7 was cloned into Escherichia coli, resulting in highlevel expression of the recombinant enzyme with EP-degrading activity. AmySTU was found to be cold-adapted; however, its optimal enzyme activity was detected at 40oC. The α-amylase was highly stable over a broad pH range (5.5-10) with the optimal pH at 7.5-8.0. The highest enzyme activity was detected when NaCl concentration was 2%, which dropped by 50% when the NaCl concentration was increased to 16%, showing an excellent nature of halotolerance. Furthermore, the amylase activity was not significantly affected by tested surfactants or the presence of some organic solvents. Therefore, the A. macleodii strain B7 and its α-amylase can be useful in lowering EP molecular weight and in starch processing.
MICROWAVE-ASSISTED SYNTHESIS AND CATALYTIC PERFORMANCE OF HIERARCHICAL Cu2O NANOSTRUCTURES
XUE-YUN GONG,YU-PENG GAO,LI-BO WANG,PENG-FEI GUO 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2013 NANO Vol.8 No.5
Hierarchical Cu2O nanostructures have been successfully fabricated on a large scale using copper acetate and glucose as starting reactants, CTAB as an additive via a microwave-assisted process. The influences of CTAB dosage and reaction time on the morphology of the products were investigated. The resulting Cu2O nanostructures were characterized by means of X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). FESEM images show that the Cu2O nanostructures are microsphere, which are composed of nanoparticles. The concentration of CTAB plays a key role in the growth of Cu2O nanostructures under experimental conditions. The possible formation mechanism of these hierarchical Cu2O nanostructures has been proposed. Meanwhile, the catalytic performances of these Cu2O microspheres for thermal decomposition of ammonium perchlorate (AP) were investigated using DSC. The results revealed that Cu2O have a great influence on the thermal decomposition of AP. The additions of Cu2O powders lower the high decomposition temperature of AP.
PARALLEL IMAGE RECONSTRUCTION FOR NEW VACUUM SOLAR TELESCOPE
Xue-Bao Li,Feng Wang,Yong Yuan Xiang,Yan-Fang Zheng,Ying Bo Liu,Hui Deng,Kai-fan Ji 한국천문학회 2014 Journal of The Korean Astronomical Society Vol.47 No.2
Many advanced ground-based solar telescopes improve the spatial resolution of observation images using an adaptive optics (AO) system. As any AO correction remains only partial, it is necessary to use post-processing image reconstruction techniques such as speckle masking or shift-and-add (SAA) to reconstruct a high-spatial-resolution image from atmospherically degraded solar images. In the New Vacuum Solar Telescope (NVST), the spatial resolution in solar images is improved by frame selection and SAA. In order to overcome the burden of massive speckle data processing, we investigate the possibility of using the speckle reconstruction program in a real-time application at the telescope site. The code has been written in the C programming language and optimized for parallel processing in a multi-processor environment. We analyze the scalability of the code to identify possible bottlenecks, and we conclude that the presented code is capable of being run in real-time reconstruction applications at NVST and future large aperture solar telescopes if care is taken that the multi-processor environment has low latencies between the computation nodes.
Abnormal Crowd Behavior Detection Using Size-Adapted Spatio-Temporal Features
Bo Wang,Mao Ye,Xue Li,Fengjuan Zhao 제어·로봇·시스템학회 2011 International Journal of Control, Automation, and Vol.9 No.5
Abnormal crowd behavior detection is an important research issue in computer vision. However, complex real-life situations (e.g., severe occlusion, over-crowding, etc.) still challenge the effectiveness of previous algorithms. Recently, the methods based on spatio-temporal cuboid are popular in video analysis. To our knowledge, the spatio-temporal cuboid is always extracted randomly from a video sequence in the existing methods. The size of each cuboid and the total number of cuboids are determined empirically. The extracted features either contain the redundant information or lose a lot of important information which extremely affect the accuracy. In this paper, we propose an improved method. In our method, the spatio-temporal cuboid is no longer determined arbitrarily, but by the in-formation contained in the video sequence. The spatio-temporal cuboid is extracted from video se-quence with adaptive size. The total number of cuboids and the extracting positions can be determined automatically. Moreover, to compute the similarity between two spatio-temporal cuboids with different sizes, we design a novel data structure of codebook which is constructed as a set of two-level trees. The experiment results show that the detection rates of false positive and false negative are significantly reduced.
( Xue Hong Zhang ),( Hong Bo Hu ),( Yong Lian Tang ),( Rui Shan Huang ),( Jiu Fu Luo ),( Byung Ki Hur ) 한국미생물 · 생명공학회 2002 Journal of microbiology and biotechnology Vol.12 No.3
A neutral polysaccharide, GP, was isolated from a fermentation broth of Ganoderma lucidum. Acid hydrolysis and a paper chromatography analysis indicated that the polysacchride was composed of glucose, xylose, and mannose. The molecular weight was estimated to be 2.9×10(4). The oral administration of GP to mice showed that it can inhibit liver damage induced by GalN and CCl4.
A Sliding Sector Approach to Quantized Feedback Variable Structure Control
Bo-Chao Zheng,Yan-Mei Xue 제어·로봇·시스템학회 2013 International Journal of Control, Automation, and Vol.11 No.6
This paper is concerned with the quantized feedback quadratic stabilization problem for linear time-invariant systems. Sliding sector based quantized state feedback variable structure control schemes are established. The main benefit of the sliding sector technique is that it can avoid chattering caused by the utilization of variable structure control strategy. With the proposed discrete on-line adjustment of the quantization parameter, it is shown that the proposed sliding sector based sliding mode controllers can tackle state quantization and guarantee quadratic stability of the closed-loop system. Simulation results are given to verify the effectiveness of the proposed method.