A Hybrid Modulation Strategy with Reduced Switching Losses and Neutral Point Potential Balance for Three-Level NPC Inverter

Weidong Jiang,Yan Gao,Jinping Wang,Lei Wang 대한전기학회 2017 Journal of Electrical Engineering & Technology Vol.12 No.2

In this paper, carrier-based pulse width modulation (CBPWM), space vector PWM (SVPWM) and reduced switching losses PWM (RSLPWM) for the three-level neutral point clamped (NPC) inverter are introduced. In the case of the neutral point (NP) potential (NPP) offset, an asymmetric disposition PWM (ASPDPWM) strategy is proposed, which can output PWM sequences correctly and suppress the lower order harmonics of the inverter effectively. An NPP balance strategy based on carrier based PWM (CBPWM) is analyzed. A hybrid modulation strategy combining RSLPWM and the NPP balance based on CBPWM is proposed, and hysteresis control is adopted to switch between the two modulation strategies. An experimental prototype of the three-level NPC inverter is built. The effectiveness of the hybrid modulation is verified with a resistance-inductance load and a permanent magnetic synchronous motor (PMSM) load, respectively. The experimental results show that reduced switching losses and an acceptable NPP can be effectively achieved in the hybrid modulation strategy.

A Hybrid Modulation Strategy with Reduced Switching Losses and Neutral Point Potential Balance for Three-Level NPC Inverter

Jiang, Weidong,Gao, Yan,Wang, Jinping,Wang, Lei The Korean Institute of Electrical Engineers 2017 Journal of Electrical Engineering & Technology Vol.12 No.2

In this paper, carrier-based pulse width modulation (CBPWM), space vector PWM (SVPWM) and reduced switching losses PWM (RSLPWM) for the three-level neutral point clamped (NPC) inverter are introduced. In the case of the neutral point (NP) potential (NPP) offset, an asymmetric disposition PWM (ASPDPWM) strategy is proposed, which can output PWM sequences correctly and suppress the lower order harmonics of the inverter effectively. An NPP balance strategy based on carrier based PWM (CBPWM) is analyzed. A hybrid modulation strategy combining RSLPWM and the NPP balance based on CBPWM is proposed, and hysteresis control is adopted to switch between the two modulation strategies. An experimental prototype of the three-level NPC inverter is built. The effectiveness of the hybrid modulation is verified with a resistance-inductance load and a permanent magnetic synchronous motor (PMSM) load, respectively. The experimental results show that reduced switching losses and an acceptable NPP can be effectively achieved in the hybrid modulation strategy.

Filtration and regeneration behavior of polytetrafluoroethylene membrane for dusty gas treatment

Weidong Zhang,Deqiang Jiang,Junteng Liu,Zhongqi Ren,Wang Geng 한국화학공학회 2008 Korean Journal of Chemical Engineering Vol.25 No.4

With micron talcum particles and nano-CaCO3 powder as test dust, a series of experiments have been carried out to systematically study the gas filtration and regeneration behavior of polytetrafluoroethylene membrane, and some comparisons were made with common filter media. The experimental results showed that the PTFE membrane had a filtration efficiency of above 99.99% for micron particles, and excellent regeneration behavior was obtained, though a much higher initial pressure drop existed. Based on the results, it was concluded that the PTFE membrane is an excellent surface-filtration media for micron particles. Effects of operation parameters, including airflow velocity, particle concentration and particle characteristics were also investigated. To better understand the evolution of pressure drop during the filtration process, a mathematical model with operation parameters and characteristics of particles was derived from the gas-solid two-phase flow theories. A novel method on the determination of regeneration period of the filter media was put forward based on the analysis of the pressure drop according to this model

A prevalence survey of Wolbachia in Polytremis fukia (Lepidoptera: Hesperiidae)

Weibin Jiang,Yajuan Wu,Haiyan He,Jianqing Zhu,Weidong Yu 한국응용곤충학회 2016 Journal of Asia-Pacific Entomology Vol.19 No.2

Wolbachia are endosymbiotic bacteria that infect arthropod and nematode hosts. Only a few studies have been made on Wolbachia in butterflies. In this study, we identified and determined the molecular characteristics of Wolbachia strains in Polytremis fukia (Lepidoptera: Hesperiidae), from seven locations in China. We also sequenced three portions of the mitochondrial DNA from the individuals of P. fukia to infer the effect of Wolbachia on host mitochondrial variation. The results show that 47% (15/32) are Wolbachia positive among all specimens. The infection rates in female and male are 69% (11/16) and 25% (4/16). Phylogenetic analysis of variation in the ftsZ gene from the two strains of Wolbachia (wFuk1 and wFuk2) showed they belonged to supergroup A. On the phylogeny of the mitochondrialDNA fromP. fukia, the sequences are split into three clades. Clade I and II are consistent with the distribution of geographical population. Clade III consists of eight females invariably infected with wFuk1which showed aweak association existed between mitochondrial DNA haplotypes andwFuk1 infection status.

PF4V1 affects the progression of oral squamous cell carcinoma by regulating Wnt/ β‑catenin pathway and angiogenesis

Cuiping Li,Weidong Jiang,Yang Zhou,Xuanping Huang,Nuo Zhou 한국응용생명화학회 2020 Applied Biological Chemistry (Appl Biol Chem) Vol.63 No.2

Platelet factor-4 variant 1 (PF4V1) was recently described as a natural non-allelic gene variant of platelet factor-4 (PF4), which has been closely associated with the growth and metastasis of various cancers. Our previous research showed that PF4V1 was related to oral squamous cells carcinoma (OSCC) metastasis. Howerver, it is still not clear about the functional role of PF4V1 in OSCC. In this study, stably transfected cell lines were constructed and the expression level of PF4V1 was verified by real‐time polymerase chain reaction (RT-PCR) and western blot. The effect of PF4V1 on proliferation, migration, invasion, and apoptosis of oral cancer (OC) cells were detected. Moreover, a xenograft tumor model was constructed to evaluate the effect of PF4V1 on OSCC in vivo. Indicators of Wnt/β-catenin, angiogenesis and epithelial-mesenchymal transition (EMT) pathways were also examined. Stable cell lines with overexpression and inhibited expression of PF4V1 were constructed successfully. After stable transfection, PF4V1 significantly promoted the proliferation, migration, and invasion of OC cells in vitro, and their tumor formation in vivo. Furthermore, PF4V1 remarkably promoted the expression of β-catenin, VEGF, and FGF but suppressed the expression of GSK-3β. There was no statistically significant correlation between PF4V1 and EMT pathway. This study provides evidence that PF4V1 promotes the proliferation, migration, invasion and tumor formation of OC cells by regulating the Wnt/β-catenin pathway and angiogenesis. Our findings suggest that PF4V1 could be a very promising target of OSCC therapy in the future.

A Novel Double-Loop Vector Control Strategy for PMSMs Based on Kinetic Energy Feedback

Anbang Wang,Qunjing Wang,Weidong Jiang 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.5

A novel vector control strategy for a permanent magnet synchronous motor (PMSM) based on the kinetic energy stored in the rotor is proposed in this paper. The novel strategy is composed of two closed loops, in which the current loop is the inner loop, and the kinetic energy serves as the outer loop. The theoretical basis and the design procedure of the two loops are given. The feasibility of the proposed control strategy is verified by experimental results. When compared with traditional vector control strategies, the proposed vector control strategy based on energy feedback has better dynamic performance. In addition, an effective estimation solution for the load variation is put forward.

A Novel Double-Loop Vector Control Strategy for PMSMs Based on Kinetic Energy Feedback

Wang, Anbang,Wang, Qunjing,Jiang, Weidong The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.5

A novel vector control strategy for a permanent magnet synchronous motor (PMSM) based on the kinetic energy stored in the rotor is proposed in this paper. The novel strategy is composed of two closed loops, in which the current loop is the inner loop, and the kinetic energy serves as the outer loop. The theoretical basis and the design procedure of the two loops are given. The feasibility of the proposed control strategy is verified by experimental results. When compared with traditional vector control strategies, the proposed vector control strategy based on energy feedback has better dynamic performance. In addition, an effective estimation solution for the load variation is put forward.

Optimization of dyeing parameters of cotton standardized samples for laundry test of dye transfer inhibition program

Mingqi Guo,Li Jiang,Qingbo Yang,Chang Sun,Jianli Liu,Weidong Gao 한국의류학회 2020 Fashion and Textiles Vol.7 No.1

In order to prevent light-colored clothes from being stained by dyes released from dark clothes during the washing process, some new-type washing machines have developed the dye transfer inhibition washing program. However, there is no certified reference materials for the test of dye transfer inhibition function. To this end, cotton fabric and reactive dyes are used as experimental materials to prepare standardized samples to evaluate the dye transfer inhibition function of washing machines. Firstly, the single factor analysis method is used to analyze the significance of the dyeing parameters including dye dosage, dyeing temperature, sodium sulfate dosage and sodium carbonate dosage. Secondly, a 4-factor 5-level experimental design and theoretical prediction of the best dyeing parameters are successively carried out through central composite design and response surface method. Two evaluation indicators, the dye release amount of the standardized sample of dyed fabric and the color difference value of the standardized sample of white fabric after washing, are proposed as the response values for response surface analysis to search the optimal dying parameters in theory. The optimal dyeing parameters obtained through response surface analysis are that the dosage of dye is 5.63% (owf), the dyeing temperature is 60 °C, the dosage of sodium sulfate is 93.60 g/L, and the dosage of sodium carbonate is 15 g/L. Experimental results indicate that the standardized samples prepared with optimal dyeing parameters can effectively distinguish the dye transfer inhibition function of washing machines.

Hsp20 Promotes Endothelial Progenitor Cell Angiogenesis via Activation of PI3K/Akt Signaling Pathway under Hypoxia

Han Zhiqi,He Xuan,Feng Yuan,Jiang Weidong,Zhou Nuo,Huang Xuanping 한국조직공학과 재생의학회 2022 조직공학과 재생의학 Vol.19 No.6

BACKGROUND: Mandibular distraction osteogenesis (MDO) is a kind of endogenous tissue engineering technology that lengthens the jaw and opens airway so that a patient can breathe safely and comfortably on his or her own. Endothelial progenitor cells (EPCs) are crucial for MDO-related angiogenesis. Moreover, emerging evidence suggests that heat shock protein 20 (Hsp20) modulates angiogenesis under hypoxic conditions. However, the specific role of Hsp20 in EPCs, in the context of MDO, is not yet known. The aim of this study was to explore the expression of Hsp20 during MDO and the effects of Hsp20 on EPCs under hypoxia. METHODS: Mandibular distraction osteogenesis and mandibular bone defect (MBD) canine model were established. The expression of CD34, CD133, HIF-1a, and Hsp20 in callus was detected by immunofluorescence on day 14 after surgery. Canine bone marrow EPCs were cultured, with or without optimal cobalt chloride (CoCl2) concentration. Hypoxic effects, caused by CoCl2, were evaluated by means of the cell cycle, cell apoptosis, transwell cell migration, and tube formation assays. The Hsp20/KDR/PI3K/Akt expression levels were evaluated via immunofluorescence, RT-qPCR, and western blot. Next, EPCs were incorporated with either Hsp20-overexpression or Hsp20-siRNA lentivirus. The resulting effects were evaluated as described above. RESULTS: CD34, CD133, HIF-1a, and Hsp20 were displayed more positive in the callus of MDO compared with MBD. In addition, hypoxic conditions, generated by 0.1 mM CoCl2, in canine EPCs, accelerated cell proliferation, migration, tube formation, and Hsp20 expression. Hsp20 overexpression in EPCs significantly stimulated cell proliferation, migration, and tube formation, whereas Hsp20 inhibition produced the opposite effect. Additionally, the molecular mechanism was partly dependent on the KDR/PI3K/Akt pathway. CONCLUSION: In summary, herein, we present a novel mechanism of Hsp20-mediated regulation of canine EPCs via Akt activation in a hypoxic microenvironment.

Tensile Behaviors of Laser-Discrete-Quenched Substrate/Nickel Coating of Electroplated Grinding Wheel

Cong Mao,Yujie Zhong,Yongle Hu,Weidong Tang,Z. M. Bi,Zhaohong Lei,Changchun Jiang,Aimin Tang 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.9 No.5

Electroplated grinding wheel has significant advantages, such as longer service life, higher removal rate, reduction of preparation work, reapplication of the wheel bub. Then it is an efficient, green and eco-friendly abrasive tool. In order to reveal the mechanism that the service life of the electroplated grinding wheel is increased by pre-quenched substrate, the tensile behavior and interfacial stresses of the laser-discrete-quenched substrate/nickel coating were studied through tensile experiment and simulation. The results show that random initial cracks appear in the nickel coating over the unquenched zone before the tensile experiment. There is an inter-diffusion region at the interface of steel substrate and nickel coating; in comparison with the unquenched zone, the size of the inter-diffusion region in the laser-quenched zone was decreased significantly (e.g., 1.2 μm in comparison with 2.6 μm). In tensile testing, the coating over the pre-quenched specimen remains bonded with the substrate firmly even the fracture occurs. In contrast, the damages in the forms of blistering, stripping and exfoliating occurred in the coating over the unquenched specimen. When a fracture occurs, there is a significant difference of the ultimate strains of quenched and unquenched zones; the ultimate strain of quenched zone is 0.0714, while that of the unquenched zone is 0.1667. At the bonding interface, the pre-quenched specimen ensured the overall shear stress and the maximum normal stress, which are lower than those of unquenched specimen. The initial cracks in pre-quenched specimen propagate during stretching, the effect of the absorbed strain energy reduces strain mismatch between the substrate and coating at the interface, and this improves the bonding strength at the interface of the laser-discrete-quenched specimen significantly.