A Nine-Level Switched-Capacitor Step-Up Inverter with Low Voltage Stress

Wang Yaoqiang,Ye Juncheng,Wang Kaige,Nie Fuquan,Li Gen,Liang Jun 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.2

This paper proposes a nine-level switched-capacitor step-up inverter (9LSUI) which can achieve a quadruple voltage gain with single dc source. Differing from other switched-capacitor inverters, the voltage stress of switches is effectively reduced due to the elimination of H-bridge, and the peak inverse voltage of all switches is kept within 2Vdc. In addition, the proposed inverter is able to integrate inductive load, and the capacitor voltage self-balancing can be achieved without any auxiliary circuits. Moreover, the topology structure can be flexibly extended to raise the output levels, and the peak inverse voltage of switches can remain constant with the increase of sub-modules in the extended structure. Comprehensive comparisons are performed to verify the outstanding advantages of the proposed inverter. Finally, the steady-state and dynamic performance of the proposed inverter is validated through an experimental prototype, and the experimental results are provided to prove the theoretical analysis.

Comparison of in vitro digestibility and chemical composition among four crop straws treated by Pleurotus ostreatus

Nie, Haitao,Wang, Ziyu,You, Jihao,Zhu, Gang,Wang, Hengchang,Wang, Feng Asian Australasian Association of Animal Productio 2020 Animal Bioscience Vol.33 No.1

Objective: The effects of Pleurotus ostreatus on the feed utilization of broad bean stalks (BBS), rape straw (RS), paddy straw (PS), and corn stalk (CS) was examined. Methods: The four roughages were co-cultured with Pleurotus ostreatus. The chemical composition; enzyme activities of laccase, carboxymethylcellulase (CMCase) and xylanase; carbohydrate and protein fractions (based on The Cornell Net Carbohydrate and Protein System [CNCPS]) were assessed at different days after inoculation (7, 14, 21, 28 d) and un-inoculated roughages (control, 0 d). The digestibility of nutrient components and the gas production of roughage with various incubation times were monitored at 0, 2, 4, 6, 9, 12, 24, 36, 48, 60, and 72 h using an in vitro ruminal fermentation method. Results: A higher CMCase activity (0.1039 U/mL) and earlier time to peak (14 d) were detected in Pleurotus ostreatus cultured with CS (p<0.05). Significantly, the incubation length-dependent responses of cumulative gas production were observed from 24 to 72 hours post fermentation (p<0.05), and these incubation length-dependent effects on cumulative gas production of PS and CS appeared earlier (24 h) for PS and CS than those (48 h) for BBS and RS (p<0.05). The fast-degradable carbohydrate (CA) content for all four roughages significantly increased over time (p<0.05). Nonetheless, increased degradation efficiency for CA treated with Pleurotus ostreatus was detected at both 21 and 28 days of incubation (p<0.05). With the exception of PS (p<0.05), there were no significant difference among the roughages (p>0.05) in slowly-degradable carbohydrate (CB2) at different incubation times (p<0.05). Conclusion: Assessment of the alterations in chemical composition, CNCPS system fractions, and the fermentation kinetics after biological pretreatment may yield a valuable database for evaluating the biological pretreatment of Pleurotus ostreatus in ruminant feed.

Effect of Age on Energy Requirement for Maintenance and Growth of Dorper and Hu Crossbred F1 Ewes Weighing 20 to 50 kg

Nie, H.T.,Wan, Y.J.,You, J.H.,Wang, Z.Y.,Lan, S.,Fan, Y.X.,Wang, F. Asian Australasian Association of Animal Productio 2015 Animal Bioscience Vol.28 No.8

This research aimed to define the energy requirement of Dorper and Hu Hybrid $F_1$ ewes 20 to 50 kg of body weight, furthermore to study energy requirement changes with age and evaluate the effect of age on energy requirement parameters. In comparative slaughter trial, thirty animals were divided into three dry matter intake treatments (ad libitum, n = 18; low restricted, n = 6; high restricted, n = 6), and were all slaughtered as baseline, intermediate, and final slaughter groups, to calculate body chemical components and energy retained. In digestibility trial, twelve ewes were housed in individual metabolic cages and randomly assigned to three feeding treatments in accordance with the design of a comparative slaughter trial, to evaluate dietary energetic values at different feed intake levels. The combined data indicated that, with increasing age, the net energy requirement for maintenance ($NE_m$) decreased from $260.62{\pm}13.21$ to $250.61{\pm}11.79kJ/kg^{0.75}$ of shrunk body weight (SBW)/d, and metabolizable energy requirement for maintenance (MEm) decreased from $401.99{\pm}20.31$ to $371.23{\pm}17.47kJ/kg^{0.75}$ of SBW/d. Partial efficiency of ME utilization for maintenance ($k_m$, 0.65 vs 0.68) and growth ($k_g$, 0.42 vs 0.41) did not differ (p>0.05) due to age; At the similar condition of average daily gain, net energy requirements for growth ($NE_g$) and metabolizable energy requirements for growth ($ME_g$) for ewes during late fattening period were 23% and 25% greater than corresponding values of ewes during early fattening period. In conclusion, the effect of age upon energy requirement parameters in the present study were similar in tendency with previous recommendations, values of energy requirement for growth ($NE_g$ and $ME_g$) for Dorper and Hu crossbred female lambs ranged between the NRC (2007) recommendation for early and later maturating growing sheep.

Constructing Hierarchical Porous Bacterial Cellulose Outer Layer for Enhanced SMCs Infiltration in a Double-Layered Vascular Graft

Jie Wang,Weijuan Nie,Ming Wang,Chen Zhang,Jian Li,Honglin Luo,Quanchao Zhang,Zhiwei Yang,Yizao Wan 한국섬유공학회 2023 Fibers and polymers Vol.24 No.11

Natural blood vessels possess a multi-layered structure. Herein, we present a bio-inspired double-layered integrated tubular graft with a compact inner layer and a porous outer layer. The inner layer consists of nanofibrous bacterial cellulose (BC) and microfibrous cellulose acetate (CA), which favors the adhesion and proliferation of endothelial cells (ECs). The outer layer, with hierarchical pores including nano-sized pores from pristine BC, median-sized pores (dozens of microns) created by particle leaching, and a large pore (hundreds of microns) array created by laser ablation, is appropriate for the penetration of vascular smooth muscle cells (SMCs). The in-situ biosynthesis was employed to "suture" the two layers, aiming to achieve an integrated tubular structure. The morphology, mechanical properties, and cell behavior of the tubular grafts were characterized. The in vitro study demonstrates that the unique outer layer possesses enhanced SMC penetration compared to the counterpart without hierarchical pores. Overall, the findings of this study demonstrate the potential of such a biomimetic integrated vascular graft for vascular replacement and regeneration.

A TBM Cutter Life Prediction Method Based on Rock Mass Classification

Ruirui Wang,Yaxu Wang,Jianbin Li,Liujie Jing,Guangzu Zhao,Lichao Nie 대한토목학회 2020 KSCE Journal of Civil Engineering Vol.24 No.9

Cutter life is an important economical index for tunnel boring machines (TBM) excavation, and its prediction is widely concerned. This paper introduces a method for predicting cutter life on the basis of statistics and regression. Traditional researches only evaluate the average mileage or time interval of each cutter change. Differently, the proposed method can accurately predict the mileage position of each cutter relatively, on the premise of knowing the installment radius of each cutter and the rock properties along the tunnel. In this procedure, the influence of the rock classification and rock properties of each cutter passing area on their passing distance is obtained by linear regression. For proposing and verifying the prediction method, totally 1,200 records of cutter changing caused by normal cutter wear are collected from the 4th Section of Water Supply Project from Songhua River. Among them, randomly selected 920 samples are used to determine the regression coefficients involved in the method. The method is verified by the rest 280 samples, and a reliable predicted result is obtained (MAPE = 27%, and R2 = 0.69).

Modeling and Analysis of Harmonic Resonance in Microgrid and Research of Active Harmonic Resistance Method

Cheng Nie,Wanjun Lei,Huajia Wang,Kai Zhang,Yue Wang 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

In the microgrid, the capacitive element such as compensation capacitor may resonance with the line inductance in harmonic frequency, furthermore serious harmonic resonance may endanger the system. In this paper, resonance mode analysis (RMA) method is used to analysis the harmonic resonance in the microgrid. To suppress the amplified of harmonic current near resonance frequency, an improved current control method for active harmonic resistance (AHR) is proposed. Simulation and experimental results reveal that the proposed method can suppress the resonance in the microgrid effectively.

A compression strategy to accelerate LSTM meta-learning on FPGA

NianYi Wang,Jing Nie,JingBin Li,Kang Wang,ShunKang Ling 한국통신학회 2022 ICT Express Vol.8 No.3

Driven by edge computing, how to efficiently deploy the meta-learner LSTM in the resource constrained FPGA terminal equipment has become a big problem. This paper proposes a compression strategy based on LSTM meta-learning model, which combined the structured pruning of the weight matrix and the mixed precision quantization. The weight matrix was pruned into a sparse matrix, then the weight was quantified to reduce resource consumption. Finally, a LSTM meta-learning accelerator was designed based on the idea of hardware–software cooperation. Experiments show that compared with mainstream hardware platforms, the proposed accelerator achieves at least 50.14 times increase in energy efficiency.

Seismic performance of steel columns corroded in general atmosphere

Youde Wang,Tao Shi,Biao Nie,Hao Wang,Shanhua Xu 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.40 No.2

Steel structures exposed to general atmosphere for a long time are highly susceptible to corrosion damage, which would lead to the degradation of service performance of the components and even structures. This article focuses on the effect of corrosion on the seismic performance of steel column. The accelerated corrosion tests in general atmosphere were conducted on 7 H-shaped steel columns and 20 steel plates. Then the obtained plate specimens were subjected to monotonic tensile tests and cyclic loading tests, and the steel columns were subjected to pseudo-static tests, respectively, to study the effects of corrosion on their mechanical properties and seismic performance. Then, a simplified three-dimensional finite element model (FEM) capable of accurately simulating the hysteretic response of corroded steel columns under low-cycle loading was established. Experimental results indicated that the yield strength, tensile strength, elastic modulus and peak strain of corroded steel plate decreased linearly with the proposed corrosion damage parameter Dn, and the energy dissipations under low-cycle loading were significantly reduced. There is a correlation between the cyclic hardening parameters of corroded steel and the yield-tensile strength difference (SD), and then a simplified formula was proposed. Corrosion could result in the premature entrance of each loading stage of corroded columns and the deterioration of buckling deformation range, bearing capacity and energy dissipation, etc. In addition, a larger axial compression ratio (CR) would further accelerate the failure process of corroded columns. The parametric finite element analysis (FEA) indicated that greater damage was found for steel columns with non-uniform corrosion, and hysteretic performance degraded more significantly when corrosion distributed at flanges or foot zone.

Monazites reveal timing and genesis of Nb-REE mineralization in trachyte from the Pingli area, North Daba Mountain, China

Xiao Nie,Zong-qi Wang,Lei Chen,Jingwu Yin,Gang Wang 한국지질과학협의회 2021 Geosciences Journal Vol.25 No.5

In recent years, several Nb-rare-earth-element (REE) deposits have been discovered in trachyte from the Pingli–Zhenping area of the North Daba Mountain. Of these, the Zhujiayuan Nb (-REE) deposit is particularly rich in monazite. In this study, electron probe microanalysis (EPMA) and laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) were used to better understand the genesis of the deposit and constrain the timing of Nb-REE mineralization. The results show that most monazite in the deposit is closely related to various alteration minerals (biotite, sericite, albite, quartz, pyrite, and calcite), and monazite often has a lower ThO2 content (0.09–1.32 wt%), indicating its hydrothermal origin. Monazite and the dominant Nb-bearing mineral (columbite) have a close paragenetic relationship, indicating that Nb and REE were mineralized in the same period. LA-ICP-MS U-Pb dating on hydrothermal monazite grains shows a weighted average 206Pb/238U age of 237.2 ± 7.9 Ma, which represents the timing of REE mineralization. The origin of monazite, in combination with the alteration mineralogy and ore-forming age, suggests that fluid exsolved from the Early Mesozoic alkaline felsic melt induced widespread hydrothermal alteration and the formation of the Zhujiayuan Nb-REE deposit.

Electromagnetic Analysis and Optimization for a Dual-Rotor Switched Reluctance Machine

Xing Wang,Rui Nie,Hao Chen,Haiying Wang,Tong Xu 한국자기학회 2019 Journal of Magnetics Vol.24 No.2

A dual-rotor switched reluctance motor is proposed in this paper. The structure and working principle of the motor are introduced in detail. The structural parameters have great influence on the performance of the motor, so sensitivity analysis of several important structural parameters to the output torque is carried out based on the two-dimensional finite element method, which improves the average torque of the rotor in the outer air gap. Additionally, the performance of the motor with various pole distributions is analyzed and compared. The results show that when the magnetic polarity distribution of the outer stator is NSNSNSNSNSNS and the magnetic polarity distribution of the inner rotor is NSNSNS, the motor has the best performance. The torque of the motor is compared with that of the traditional single-rotor switched reluctance motor. It shows that the performance of the motor proposed in this paper is better.