Simplified SVPWM that Integrates Overmodulation and Neutral Point Potential Control

Rong-Wu Zhu,Xiao-Jie Wu 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.5

A simplified and effective space vector pulse-width modulation (SVPWM) algorithm with two and three levels for three-phase voltage-source converters is proposed in this study. The proposed SVPWM algorithm only uses several linear calculations on three-phase modulated voltages without any complicated trigonometric calculations adopted by conventional SVPWM. This simplified SVPWM also avoids choosing the vector sector required by conventional SVPWM. A two-level overmodulation scheme is integrated into the proposed two-level SVPMW to generate the output voltage that increases from a linear region to a six-step state with a smoothly linear transition characteristic and a simple overmodulation process without a lookup table and complicated nonlinear functions. The three-level SVPWM with a proportional-integral controller effectively balances the neutral point potential of the neutral point clamped converter. Results from the simulation in MATLAB/Simulink and the experiment based on a digital signal processor are provided to clearly demonstrate the validity and effectiveness of the proposed strategies.

Simplified SVPWM that Integrates Overmodulation and Neutral Point Potential Control

Zhu, Rong-Wu,Wu, Xiao-Jie The Korean Institute of Power Electronics 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.5

A simplified and effective space vector pulse-width modulation (SVPWM) algorithm with two and three levels for three-phase voltage-source converters is proposed in this study. The proposed SVPWM algorithm only uses several linear calculations on three-phase modulated voltages without any complicated trigonometric calculations adopted by conventional SVPWM. This simplified SVPWM also avoids choosing the vector sector required by conventional SVPWM. A two-level overmodulation scheme is integrated into the proposed two-level SVPMW to generate the output voltage that increases from a linear region to a six-step state with a smoothly linear transition characteristic and a simple overmodulation process without a lookup table and complicated nonlinear functions. The three-level SVPWM with a proportional-integral controller effectively balances the neutral point potential of the neutral point clamped converter. Results from the simulation in MATLAB/Simulink and the experiment based on a digital signal processor are provided to clearly demonstrate the validity and effectiveness of the proposed strategies.

Whole Cell-mediated Biocatalytic Synthesis of Helicid Cinnamylate and Its Biological Evaluation as a Novel Tyrosinase Inhibitor

Rong-ling Yang,Xi Chen,Yu-ye Song,Qian-lin Zhu,Muhammad Bilal,Yu Wang,Zheng Tong,Ting-ting Wu,Zhao-Yu Wang,Hong-zhen Luo,Xiang-jie Zhao,Ting-ting He 한국생물공학회 2022 Biotechnology and Bioprocess Engineering Vol.27 No.3

Tyrosinase inhibitors are clinically effective for treating some dermatological disorders related to melanin hyperpigmentation. Accordingly, the discovery and development of tyrosinase inhibitors have great value in the pharmaceutical and cosmetic industry. Here, a novel tyrosinase inhibitor, 6′-O-cinnamoyl-helicid (helicid cinnamylate) was successfully synthesized by a simple and effective biocatalytic approach with Aspergillus oryzae cells. Investigation of the effects of several key variables on helicid cinnamylate synthesis found that the reaction conversion, reaction rate and regioselectivity reached 99%, 9.40 mM/h and > 99%, respectively, at the optimal conditions with anhydrous acetone as the solvent, whole-cell concentration of 40 mg/mL, and the molar ratio of vinyl cinnamate to helicid of 10 at 45°C. The whole-cells retained 68.87% of its initial activity after reusing for seven batches, indicating a potent application potential in non-aqueous biocatalytic systems. It was worth noting that helicid cinnamylate demonstrated a more potent tyrosinase inhibitory activity with an IC50 value of 3.55 mM than helicid (IC50 = 4.48 mM) and arbutin (IC50 = 5.48 mM), which suggest that helicid cinnamylate could be developed as a more potential tyrosinase inhibitor. In conclusion, this study provides a novel whole-cell catalytic approach for the synthesis of helicid cinnamylate and insight into its application as a tyrosinase inhibitor.

NANOSCALE POROUS SILICON MICROCAVITY BIOSENSOR FOR NOVEL LABEL-FREE TUBERCULOSIS ANTIGEN–ANTIBODY DETECTION

BAO WU,GUOGUANG RONG,JUNWEI ZHAO,SHULIN ZHANG,YONGXIN ZHU,BOYONG HE 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2012 NANO Vol.7 No.6

One third of the world population is estimated to have Mycobacterium tuberculosis infection. It is urgent to develop a rapid, inexpensive and convenient diagnostic method for detection of tuberculosis. Porous silicon material has taken more and more attention in recent years for biosensing applications and some useful results have been obtained. In this paper, we report the feasibility of applying porous silicon microcavity biosensor in a novel and relatively rapid serodiagnostic approach. Nowadays, most of serodiagnostic tests are based on labeled detection. Applying label-free detection methods can help develop fast and e±cient tuberculosis diagnostic tools, which can meet the current demand. In this study, we use this label-free sensing platform (i.e., porous silicon microcavity) to detect the interaction between 16 kDa antigen and anti-16 kDa antibody. Through a series of experiments, we verify the speci¯city and examine the sensitivity of this new diagnostic technique. The results show that it is feasible to apply porous silicon microcavity in the tests of tuberculosis.

Indoor Air Quality in Kitchens in Rural China

Xiang, Rong-Biao,Song, Jia-Bei,Zhu, Ying,Guang, Wu Mary Ann Liebert 2016 ENVIRONMENTAL ENGINEERING SCIENCE Vol.33 No.9

Optimization for Relay-Assisted Broadband Power Line Communication Systems with QoS Requirements Under Time-varying Channel Conditions

( Xiaolin Wu ),( Bin Zhu ),( Yang Wang ),( Yue Rong ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.10

The user experience of practical indoor power line communication (PLC) applications is greatly affected by the system quality-of-service (QoS) criteria. With a general broadcast- and-multi-access (BMA) relay scheme, in this work we investigate the joint source and relay power optimization of the amplify-and-forward (AF) relay systems used under indoor broad- band PLC environments. To achieve both time diversity and spatial diversity from the relay- involved PLC channel, which is time-varying in nature, the source node has been configured to transmit an identical message twice in the first and second signalling phase, respectively. The QoS constrained power allocation problem is not convex, which makes the global optimal solution is computationally intractable. To solve this problem, an alternating optimization (AO) method has been adopted and decomposes this problem into three convex/quasi-convex sub-problems. Simulation results show the fast convergence and short delay of the proposed algorithm under realistic relay-involved PLC channels. Compared with the two-hop and broadcast-and- forward (BF) relay systems, the proposed general relay system meets the same QoS requirement with less network power assumption.

Flow blockage analysis for fuel assembly in a lead-based fast reactor

Wang, Chenglong,Wu, Di,Gui, Minyang,Cai, Rong,Zhu, Dahuan,Zhang, Dalin,Tian, Wenxi,Qiu, Suizheng,Su, G.H. Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.10

Flow blockage of the fuel assembly in the lead-based fast reactor (LFR) may produce critical local spots, which will result in cladding failure and threaten reactor safety. In this study, the flow blockage characteristics were analyzed with the sub-channel analysis method, and the circumferentially-varied method was employed for considering the non-uniform distribution of circumferential temperature. The developed sub-channel analysis code SACOS-PB was validated by a heat transfer experiment in a blocked 19-rod bundle cooled by lead-bismuth eutectic. The deviations between the predicted coolant temperature and experimental values are within ±5%, including small and large flow blockage scenarios. And the temperature distributions of the fuel rod could be better simulated by the circumferentially-varied method for the small blockage scenario. Based on the validated code, the analysis of blockage characteristics was conducted. It could be seen from the temperature and flow distributions that a large blockage accident is more destructive compared with a small one. The sensitivity analysis shows that the closer the blockage location is to the exit, the more dangerous the accident is. Similarly, a larger blockage length will lead to a more serious case. And a higher exit temperature will be generated resulting from a higher peak coolant temperature of the blocked region. This work could provide a reference for the future design and development of the LFR.

Self-mixing gas leakage detection of tank based on Er3þ eYb3þ codoped Distributed Bragg Reflector fiber laser

Wenhua Zhang,Rong Xiang,Shuang Wu,Bo Yang,Yu Liu,Jun Zhu,Huaqiao Gui,Jianguo Liu,Liang Lu,Benli Yu 한국물리학회 2014 Current Applied Physics Vol.14 No.5

In this paper we present a novel method of gas leakage detection based on self-mixing interference with an extremely compact Er3þ eYb3þ codoped Distributed Bragg Reflector (EYDBR) fiber laser. According to the simulation and theoretical analysis of gas leakage of tank, we infer that the vibration frequency peak of tank caused by gas leakage increases with the internal pressure. In the experiment, the results agree with the theoretical prediction and the relevance of polynomial fitting about the spectrum peak of tank vibration and internal pressure is 0.99725. Thus, we can get the internal pressure of tank by measuring the vibration frequency peak of tank. Moreover, it has important significance in the prevention of the accident of flammable or explosive gas leakage.

H₂O₂ Inhibits Proliferation and Mediates Suppression of Migration via DLC1/RhoA Signaling in Cancer Cells

Ma, Long,Zhu, Wen-Zhen,Liu, Ting-Ting,Fu, Hui-Ling,Liu, Zhao-Jun,Yang, Bing-Wu,Song, Tai-Yu,Li, Guo-Rong Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.4

Background: RhoGTPase-activating proteins (RhoGAPs) regulate RhoGTPases in cells, but whether individual reactive oxygen species (ROS) regulate RhoGAPs is unknown. Our previous published papers have shown that deleted in liver cancer 1 (DLC1) inhibits cancer cell migration by its RhoGAP activity. The present study was designed to explore the role of $H_2O_2$ in regulation of DLC1. Materials and Methods: We treated cells with $H_2O_2$ for 24h and phenotypic changes were analyzed by MTT, RT-PCR, Western blotting, immunofluorescence staining and wound healing assays. Results: $H_2O_2$ downregulated cyclin D1 and cyclin E to inhibit proliferation, and upregulated BAX to induce apoptosis in MCF-7 cells. Compared with non-tumorigenic cells, $H_2O_2$ increased expression of DLC1 and reduced activity of RhoA in cancer cells. Stress fiber production and migration were also suppressed by $H_2O_2$ in MDA-MB-231 cells. Conclusions: Our study suggests that $H_2O_2$ inhibits proliferation through modulation of cell cycle and apoptosis-related genes, and inhibits migration by decreasing stress fibers via DLC1/RhoA signaling.

Facile Fabrication of Non-fluorinated Durable Superhydrophobic Cotton Fabric

Guolin Zheng,Yuhe Wu,Dan Zhang,Shuai Liu,Zhu Long,Rong Li 한국섬유공학회 2020 Fibers and polymers Vol.21 No.11

The superhydrophobic surface is easy to lose the superhydrophobicity in the practical applications, due to the factthat the micro- and nanoscale rough structure is easily damaged. Therefore, it is one of the challenges to endow solid surfacewith durable superhydrophobic property. In this work, the environment-friendly superhydrophobic cotton fabric was preparedby dip-coating methodology. Meanwhile, the cotton fabric was endowed with durable superhydrophobicity. Herein, theoctadecylamine was utilized to reduce the surface free energy of cotton fabric. However, octadecylamine was only adsorbedon the fabric surface. Therefore, the hydrophobic resin was employed to supply enough adhesion force. As a result, thelimitation that traditional methods frequently utilize additional nanoparticles to construct hierarchical rough surfaces wasbroken. The water contact angles of the coated cotton fabric at room temperature and 70 oC reached 154.4±0.6 o and120±1.1 o, respectively. Moreover, the coated cotton fabric still reserved superhydrophobic property after 30th cycle’sabrasion and exhibited excellent hydrophobicity after 500th cycle’s abrasion. In addition, the surface free energy of originalcotton fabric reduced by 54.7 % so that the coated cotton fabric had outstanding repellency to hydrochloric acid, sodiumhydroxide solution, coffee and sodium chloride solution, respectively.