Centering method based on workpiece under test for rotational-scanning-based surface metrology systems

Wenhao Zhang,Bingfeng Ju,Huilin Du,Anyu Sun 한국생산제조학회 2018 한국생산제조시스템학회 학술발표대회 논문집 Vol.2018 No.10

Adaptive Digital Predictive Peak Current Control Algorithm for Buck Converters

Zhang, Yu,Zhang, Yiming,Wang, Xuhong,Zhu, Wenhao The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.3

Digital current control techniques are an attractive option for DC-DC converters. In this paper, a digital predictive peak current control algorithm is presented for buck converters that allows the inductor current to track the reference current in two switching cycles. This control algorithm predicts the inductor current in a future period by sampling the input voltage, output voltage and inductor current of the current period, which overcomes the problem of hardware periodic delay. Under the premise of ensuring the stability of the system, the response speed is greatly improved. A real-time parameter identification method is also proposed to obtain the precision coefficient of the control algorithm when the inductance is changed. The combination of the two algorithms achieves adaptive tracking of the peak inductor current. The performance of the proposed algorithms is verified using simulations and experimental results. In addition, its performance is compared with that of a conventional proportional-integral (PI) algorithm.

Adaptive Digital Predictive Peak Current Control Algorithm for Buck Converters

Yu Zhang,Yiming Zhang,Xuhong Wang,Wenhao Zhu 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.3

Digital current control techniques are an attractive option for DC-DC converters. In this paper, a digital predictive peak current control algorithm is presented for buck converters that allows the inductor current to track the reference current in two switching cycles. This control algorithm predicts the inductor current in a future period by sampling the input voltage, output voltage and inductor current of the current period, which overcomes the problem of hardware periodic delay. Under the premise of ensuring the stability of the system, the response speed is greatly improved. A real-time parameter identification method is also proposed to obtain the precision coefficient of the control algorithm when the inductance is changed. The combination of the two algorithms achieves adaptive tracking of the peak inductor current. The performance of the proposed algorithms is verified using simulations and experimental results. In addition, its performance is compared with that of a conventional proportional-integral (PI) algorithm.

The Effect of Obstacle Number, Shape and Blockage Degree in Flow Field of PEMFC on its Performance

Zongxi Zhang,Xiang Fan,Wenhao Lu,Jian Yao,Zhike Sui The Korean Electrochemical Society 2024 Journal of electrochemical science and technology Vol.15 No.1

Proton exchange membrane fuel cell (PEMFC) has received extensive attention as it is the most common hydrogen energy utilization device. This research not only investigated the effect of obstacle number and shape on PEMFC performance, but also studied the effect of the blockage degree in the channel of PEMFC on its performance. It was found that compared with traditional scheme, longitudinally distributed obstacles scheme can significantly promote reactants transfer to catalyst layer, and the blockage degree in the channel effect PEMFC performance most. The scheme with 10 rectangular obstacles in single channel and 60% channel blockage had the best output performance and the most uniform distribution of reactants and products. Obstacle height distribution can significantly affect PEMFC performance, the blockage degree in the whole basin was large, particularly as the channel was blocked to higher degree in region 2 and region 3, higher net power density and better mass transfer effect can be obtained. Among them, the fuel cell with the blockage degree of 40%, 60% and 60% in region 1, region 2 and region 3 have the best PEMFC output performance and mass transfer, the net power density was 29.8% higher than that of traditional scheme.

Functional profiling of the gut microbiomes in two different populations of the brown planthopper, Nilaparvata lugens

Yunhua Zhang,Tao Tang,Wenhao Li,Tingwei Cai,Jian Hong Li,Hu Wan 한국응용곤충학회 2018 Journal of Asia-Pacific Entomology Vol.21 No.4

Previous studies have demonstrated that gut symbionts are involved in the detoxification metabolism of insect hosts, but the relationship between gut symbionts and host detoxification metabolism of the brown planthopper (Nilaparvata lugens, BPH) remains unclear. In the present study, an indoor population (NlIP) and a field population (NlFP) of the BPH were used to characterize the functional profiling of the gut microbiome based on 16S rDNA sequencing. The results show that the NlIP and NlFP strains of N. lugens had different symbiont compositions, and Proteobacteria, Actinobacteria, and Firmicutes were the dominate phyla, accounting for > 75% of the total symbiont compositions. Additionally, the NlIP strain had more Pantoea and Stenotrophomonas, while the NlFP strain showed a higher Wolbachia, Actinobacteria, and Herbaspirillum relative abundance. Furthermore, functional content of the metagenome predicted by PICRUSt demonstrated no significant difference in metagenomic function between the NlIP and NlFP strains in the principal component analysis (PCA), and only three types of genes, namely, genes involved with metabolic diseases, poorly characterized genes, and genes involved in circulatory systems, were different between the strains based on KEGG pathway analysis, which also speculated that gut symbionts are not directly involved in the detoxification metabolism for insecticides in the BPH. These results will be helpful for further research into the mechanisms of gut symbionts involved in detoxification metabolism in the BPH.

Damage Mechanism of Broad-narrow Joint of CRTSII Slab Track under Temperature Rise

Xiaokai Liu,Wenhao Zhang,Jieling Xiao,Xueyi Liu,Wei Li 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.5

There is two typical damage pattern at broad-narrow joint of CRTSII slab track breakage of narrow joint and fracture at junction between broad joint and narrow joint. This paper aims to study the damage mechanism and develop of broad-narrow joint of CRTSII slab track and put forward the methods to reduce the damage. Based on damaged plasticity model for concrete and cohesive zone model, the damage mechanism and development process of broad-narrow joint are analyzed in this study. The unequal width of broad joint and narrow joint, different concrete strength between broad-narrow joints and slab and slab integrity reducing due to the interface are the main reason for the typical damage. It is suggested to set the same width of broad joint and narrow joint, set the same strength of broad-narrow joint and slab and enhance the integrity of the slab by chipping or adding adhesives, among which the former two methods are more effective. Breakage of narrow joint is a gradual compression damage due to the lower concrete strength than slab. Fracture at the junction between narrow joint and broad joint is a mutational tension damage due to the unequal width of broad joint and narrow joint. The temperature gradient has significant effect on the compression damage, but small to the tension damage, it has the risk of complete destruction under extreme conditions.

A Throughput Improved Path Selection Method Based on Throughput Prediction Model and Available Bandwidth for MPTCP

Xiaomin Jin,Yuanan Liu,Wenhao Fan,Fan Wu,Hongguang Zhang 보안공학연구지원센터 2015 International Journal of Future Generation Communi Vol.8 No.2

Nowadays, many network devices have more than one network interface. Meanwhile, many protocols have been proposed to utilize multiple paths simultaneously. MPTCP (Multipath TCP) is a transport layer protocol that transfers data by multiple paths simultaneously, which is designed to improve the throughput and increase robustness of end to end transmission. However, when we use MPTCP, we find that MPTCP can not improve the throughput but even reduce the throughput in some cases. In this paper, we study this issue. Firstly, we study the effects of path characteristics for throughput of MPTCP, and find that path characteristics especially those bad paths have a great impact on the performance of MPTCP. Secondly, we analyze the reasons why the bad path characteristics have a serious impact on throughput of MPTCP, and propose a path selection method based on throughput prediction model and available bandwidth to improve the throughput. Finally, we validate our path selection method by simulations, and the results show that our method can improve the throughput of MPTCP.

Anaerobic Ammonium-Oxidizing Bacteria in Cow Manure Composting

( Tingting Wang ),( Lijun Cheng ),( Wenhao Zhang ),( Xiuhong Xu ),( Qingxin Meng ),( Xuewei Sun ),( Huajing Liu ),( Hongtao Li ),( Yu Sun ) 한국미생물생명공학회(구 한국산업미생물학회) 2017 Journal of microbiology and biotechnology Vol.27 No.7

Composting is widely used to transform waste into valuable agricultural organic fertilizer. Anaerobic ammonium-oxidizing (anammox) bacteria play an important role in the global nitrogen cycle, but their role in composting remains poorly understood. In the present study, the community structure, diversity, and abundance of anammox bacteria were analyzed using cloning and sequencing methods by targeting the 16S rRNA gene and the hydrazine oxidase gene (hzo) in samples isolated from compost produced from cow manure and rice straw. A total of 25 operational taxonomic units were classified based on 16S rRNA gene clone libraries, and 14 operational taxonomic units were classified based on hzo gene clone libraries. The phylogenetic tree analysis of the 16S rRNA gene and deduced HZO protein sequences from the corresponding encoding genes indicated that the majority of the obtained clones were related to the known anammox bacteria Candidatus “Brocadia,” Candidatus “Kuenenia,” and Candidatus “Scalindua.” The abundances of anammox bacteria were determined by quantitative PCR, and between 2.13 × 10⁵ and 1.15 × 10⁶ 16S rRNA gene copies per gram of compost were found. This study provides the first demonstration of the existence of anammox bacteria with limited diversity in cow manure composting.

Analysis on Steering Capability of a New Bogie with Independently Rotating Wheels

CHI Maoru,ZENG Jing,GUO Wenhao,ZHANG Weihua,JIN Xuesong 한국철도학회 2009 International Journal of Railway Vol.2 No.4

A new scheme about a coupled bogie with Independently Rotating Wheels was put forward firstly. And then it is fund by theoretic analysis that the bogie takes on prominent radial capability on curved track and splendiferous restoring capability on tangent track. Lastly, a dynamic calculating model of the coupled bogie with independently rotating wheels has been established and a dynamic simulation analysis on steering capability of the bogie was made and the simulation results can inosculate foregoing theoretic analysis, which illuminates that the coupled bogie can solve drastically the difficulty about steering problem of independently rotating wheel.

The luminescence properties and thermal stability of a green-blue color tunable Sr2SiO4: Tb3+, Ce3+ phosphor

Tianpeng Yu,Lixi Wang,Xiaojuan Yang,Wenhao Ding,Qitu Zhang 대한금속·재료학회 2019 ELECTRONIC MATERIALS LETTERS Vol.15 No.1

In this paper, green-blue emitting Sr 2 SiO 4 (SSO):0.03Tb 3+ , x Ce 3+ ( x = 0–0.005) materials were synthesized via a solid-statereaction method. The crystal structures, luminescence properties, decay time, and thermal stability were measured in thiswork. The as-prepared phosphors exhibit both an indigo emission of Ce 3+ and green emission of Tb 3+ with considerableintensity ( λ ex = 300 nm). Tb 3+ ion emission was intensifi ed obviously with co-doping Ce 3+ . The luminescence spectra ofSr 2 SiO 4 (SSO):0.03Tb 3+ , Ce 3+ shows characteristic line of Tb 3+ ion transition ( 5 D 4 → 7 F 5 ). Tunable green-blue color canbe obtained by the addition of Ce 3+ ions. An eff ective energy transfer process between Tb 3+ and Ce 3+ was supposed andconfi rmed from decay curves. In addition, the energy transfer mechanism from Ce 3+ to Tb 3+ ions in the Sr 2 SiO 4 (SSO) hostis electric multipolar interaction. Sr 2 SiO 4 (SSO):Tb 3+ , Ce 3+ phosphor exhibits good thermal stability, the quantum yield wasabout 43.67%, indicating a potential candidate for solid-state lighting.