Study of Ablation of Arc Contacts and Dynamic Contact Resistance in High Current Breaker

Licheng Xing,Xiaodong Zhang,Qingbin Tong,Gaoqi Xing 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.3

The fault of power circuit breaker (PCB) can lead very serious problems, especially in high voltage–power grid. The structure of contacts may be composed of main contacts and arc contacts, and this structure can avoid ablation of main contacts efciently. It is necessary to study the eroded state of the arc contacts and the dynamic contact resistance of arc contacts to estimate the operating state of the PCB. The wear of contacts contains arc ablation and mechanical wear through the characteristics of contacts. The arc ablation is caused by the high temperature of the arc and the mechanical wear is caused by the mechanical friction of static and movable contacts. Some experiments have been done under diferent size of contacts and diferent current through them. The results show that the mechanical wear increases, sometimes heavier, with the increase of the size of fxed contacts and the decrease of the size of movable ones because the force between fxed and movable contacts becomes larger. The results also show that the ablation of arc contacts increases with the increase of current, especially when the current is up to 20 kA. With the high temperature of arc reaching the hardness point of copper, the arc ablation and mechanical erosion are increasing obviously since the contacts become soft and easy to wear. Another result of the study shows it is important to choose the material of contacts and the force between movable and fxed contacts. The harder and less resistance the material of contacts, the better the operating situation. To monitor the operating situation of the breaker, the dynamic contact resistance was measured 25 times. As a result, the dynamic contact resistance is sensitive to the current and increasing with the increase of continuous experiment time because of the increasing of metal ions. Furthermore, if the SF6 in the PCB is changes, the dynamic contact resistance would be changed. The dynamic contact resistance in this experiment varies substantially within the range of 80–250 μΩ at the current of 20 kA.

Identification of QTLs associated with the anaerobic germination potential using a set of Oryza nivara introgression lines

Licheng Liu,Xiaoxiang Li,Sanxiong Liu,Jun Min,Wenqiang Liu,Xiaowu Pan,Baohua Fang,Min Hu,Zhongqi Liu,Yongchao Li,Haiqing Zhang 한국유전학회 2021 Genes & Genomics Vol.43 No.4

Background Rice (Oryza sativa L.) is an important crop and a staple food for half of the population around the world. The recent water and labor shortages are encouraging farmers to shift from traditional transplanting to direct-seeding. However, poor germination and slow elongation of the coleoptile constrains large-scale application of direct-seeding. Objective Thisstudy was aimed to investigate the genetic basis of the anaerobic germination(AG) potential using a set of Oryza nivara (O. nivara) introgressionlines (ILs). Methods Inthis study, a total of 131 ILs were developed by introducing O. nivara chromosomesegments into the elite indica rice variety 93-11 through advanced backcrossingand repeated selfng. A high-density genetic map has been previouslyconstructed with 1,070 bin-markers. The seeds of ILs were germinated and usedto measure coleoptile length under normal and anaerobic conditions. QTLsassociated with AG potential were determined in rice. Results Basedon the high-density genetic map of the IL population, two QTLs, qAGP1 and qAGP3 associated with AG tolerance were characterized and locatedon chromosomes 1 and 3, respectively. Each QTL explained 15% of the phenotypic variance.Specifcally, the O. nivara-derived chromosomesegments of the two QTLs were positively tolerance to anaerobic condition byincreasing coleoptile length. In a further analysis of public transcriptomedata, a total of 26 and 36 genes within qAGP1 and qAGP3 were transcriptionallyinduced by anaerobic stress, respectively. Conclusions Utilizationof O. nivara-derived alleles at qAGP1 and qAGP3 can potentially enhance tolerance to anaerobic stress at thegermination stage in rice, thereby accelerating breeding of rice varieties tobe more adaptative for direct-seeding.

Semisupervised Particle Swarm Optimization for Classification

Zhang, Xiangrong,Jiao, Licheng,Paul, Anand,Yuan, Yongfu,Wei, Zhengli,Song, Qiang Hindawi Limited 2014 Mathematical problems in engineering Vol.2014 No.-

<P>A semisupervised classification method based on particle swarm optimization (PSO) is proposed. The semisupervised PSO simultaneously uses limited labeled samples and large amounts of unlabeled samples to find a collection of prototypes (or centroids) that are considered to precisely represent the patterns of the whole data, and then, in principle of the “nearest neighborhood,” the unlabeled data can be classified with the obtained prototypes. In order to validate the performance of the proposed method, we compare the classification accuracy of PSO classifier, k-nearest neighbor algorithm, and support vector machine on six UCI datasets, four typical artificial datasets, and the USPS handwritten dataset. Experimental results demonstrate that the proposed method has good performance even with very limited labeled samples due to the usage of both discriminant information provided by labeled samples and the structure information provided by unlabeled samples.</P>

Analysis and Development of the CFRP Boring Bar for Stability Improvement

Licheng Lu,Can Ni,Gang Liu,Bo Qian,Qinglong An,Zhenzhen Cao,Liqiang Zhang,Junli Li 한국섬유공학회 2023 Fibers and polymers Vol.24 No.12

Boring bars with a large length-to-diameter ratio have become increasingly indispensable for deep hole machining. However, the dynamic performance of conventional boring bars may be inadequate, resulting in vibrations. In this paper, a novel boring bar with composites and a constrained layer damping structure was fabricated to suppress vibrations during the boring operation. Initially, the configuration of the CFRP boring bar was proposed based on theoretical analysis, and then the modal parameters were calculated using the bending strain energy method and cantilever beam theory. Subsequently, the geometric design parameters were optimized analytically using the finite element method. Modal and cutting tests were then conducted to evaluate the cutting stability of a CFRP boring bar with a length-to-diameter ratio of 8.4. The modal parameters, vibration signals, and cutting force signals were measured and compared with a carbide boring bar. The experimental results indicated that there was a significant improvement in the cutting stability of the CFRP boring bar.

Real-time structural health monitoring system based on streaming data

Qilin Zhang,Siyuan Sun,Bin Yang,Roland Wüchner,Licheng Pan,Haitao Zhu 국제구조공학회 2021 Smart Structures and Systems, An International Jou Vol.28 No.2

In this paper, a novel real-time structural health monitoring (SHM) system based on streaming data is proposed. In contrast to a traditional SHM system, the proposed system implements a series of optimizations for data transmission and processing to reduce the latency and better satisfy the real-time requirement. The concept of the watermark in the streaming system is adopted to address the problem of when to trigger the time window calculation under the real-time requirement. Moreover, a well-designed parallel mechanism is used to satisfy the multistage computation requirement in the parallel data stream. A case study in which the proposed system is applied to the Shanghai Tower is presented. The peak picking method is used as an example in the test environment to track the latency of each main operation under different parallelism schemes. The results show that computing in parallel effectively reduces the latency and provides a reference for integrating the random decrement technique (RDT), stochastic subspace identification (SSI), or other more complex but effective algorithms in parallel into the system in the future. The total latency under the test environment from data generation to data transmission to the web server is approximately only 200-400 ms, which indicates the excellent real-time performance of the system.

Mechanism and process for the extraction of lithium from the high magnesium brine with N,N-bis(2-ethylhexyl)-2-methoxyacetamide in kerosene and FeCl3

Lianmin Ji,Licheng Zhang,Dong Shi,Xiaowu Peng,Jinfeng Li,Yuze zhang,Taoshan Xu,Lijuan Liao 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.113 No.-

The degradation of TBP has become a stumbling block to the industrial continuous production of lithiumchloride extraction from brines with high Mg/Li ratio by solvent extraction. To develop a more stable andmore efficient extraction system, a novel amide system, containing newly synthesized extractant N,N-bis(2-ethylhexyl)-2-methoxyacetamide (NBEHMOA), FeCl3 6H2O and sulfonated kerosene, was proposed inthis work. Compared with TBP and N523, NBEHMOA extracted Li+ and H+ in the sequence of TBP ˃NBEHMOA ˃ N523 and N523 ˃ TBP ˃ NBEHMOA respectively. The solution containing 5.5 mol/L LiCland 0.5 mol/L HCl was used as the eluent in the scrubbing process. A Li+ extraction efficiency of 96.7%and 22.31 g/L Li+ in the stripping solution were achieved by the whole process with counter-currenttwelve stages. The extraction mechanism investigated via FT-IR spectroscopy illustrated that the metalions Fe3+ and Li+ were mainly coordinated by the carbonyl C = O in NBEHMOA. This novel amide systemcan successfully achieve the cascade extraction effect for lithium, Li/Mg separation and avoid the generationof phase interface objects through counter-current extraction of lithium from brine at a lower acidity. This work provided a novel extraction system to recover lithium from the higher magnesium/lithiumratio brines.

Optical Cavity-Enhanced Localized Surface Plasmon Resonance for High-Quality Sensing

Chen, Jing,Zhang, Qian,Peng, Cheng,Tang, Chaojun,Shen, Xueyang,Deng, Licheng,Park, Gun-Sik IEEE 2018 IEEE photonics technology letters Vol.30 No.8

<P>We report an effective strategy to enhance the localized surface plasmon resonances (LSPRs) of metallic nanoparticles by introducing a Fabry–Pérot (FP) cavity for high-quality sensing. The concept is based on the combined excitation of LSPRs in metallic nanoparticles and optical cavity modes supported by the FP cavities, whose strong interactions result in two ultra-narrowband hybridized plasmon modes with a huge electric field enhancement. A high-quality double-band plasmonic nanosensor, with the refractive index sensitivity approaching 600 nm/RIU and a figure of merit exceeding 28 is achieved here, which suggests that the cavity-coupling strategy could offer new perspectives for achieving ultra-compact efficient biosensors.</P>

SERVICE-ORIENTED ARCHITECTURE EXPANDS THE WEB-BASED INTERACTIVE EDUCATION SYSTEM

Huawei Zhai,Weishi Zhang,Licheng Cui,Ganna Liu 한국멀티미디어학회 2006 한국멀티미디어학회 국제학술대회 Vol.2006 No.-

This paper introduces the process of using net in teaching course of 'foundation of multimedia application', and stresses on the research, development and application instances of the network education system, finally it shows a service-oriented architecture of the net teaching system, in order to integrate heterogeneous net teaching resource quickly and conveniently.

A Study of Leveraging Memory Level Parallelism for DRAM System on Multi-Core Architecture

Yuxuan Wang,Yingping Zhang,Xiaotian Zhang,Jian Yin,Licheng Chen 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.4

DRAM system has been more and more critical on modern multi-core architecture where the Moore’s law has been made effect on increasing the number of cores integrated in a processor chip. The performance of DRAM system is usually measured in term of bandwidth and latency, which are regarded as inherently depending on Row Buffer Hit Rate (RBHR) according to previous studies. In this paper, we find that Memory Level Parallelism (MLP) exhibits a stronger correlation with the performance of DRAM system on multi-core/many-core architecture than RBHR, and promoting MLP significantly improves DRAM system performance. In order to exploit the MLP, we have evaluated various approaches including multi-bank, multi-row-buffers, multi-memory-controllers and the obsolete Virtual Channel Memory (VCM). The experimental results show that VCM is a better alternative to traditional DRAM chip on multicore/many-core architecture than the other three approaches because VCM has almost all the advantages of the others: 1) it can improve homogeneous workloads’ IPC by 2.21X on a 16-core system with 32 virtual channels due to leveraging unexploited MLP. 2) It can also promote Quality-of-Service (QoS) of DRAM system by removing unfairness while memory controllers serve memory requests. 3) It can save energy and has low area costs. Unfortunately, VCM, which was proposed in the late 1990s, faded away before multi-core/manycore became dominated. Therefore, we suggest memory chip vendors reconsider the VCM technology for multi-core architecture.

The Influence of Dispersion State of Graphene Sheets on the Microstructure and Thermal Conductivity of Free-Standing Reduced Graphene Oxide Films

Xiaorui Wang,Shuangling Jin,Rui Zhang,Yan Liu,Jiangcan Wang,Zhen Hu,Wangzhao Lu,Shuo Yang,Minglin Jin,Wenming Qiao,Licheng Ling 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.3

Reduced graphene oxide (rGO) aqueous dispersions were synthesized from GO suspensions with hydrazine as reducing agent via a microwave-hydrothermal process in ammonia solution. The rGO films were fabricated by vacuum filtration of above dispersions. When the weight ratio of hydrazine to GO (R N2H4/GO) increases from 0.125 to 9, the dispersion stability of rGO nanosheets in hydrazine/ammonia solution degrades gradually, the surfaces of resultant films become rough from smooth and large interspaces turn up in the transverse section. With the increasing of R N2H4/GO, the C/O atomic ratio and orientation degree of (002) plane of rGO films increase, and the in-plane thermal conductivity also increases, achieving a maximum value of 1056 W/m K when R N2H4/GO is 3.375, then decreases because large interspaces in the rGO film with higher reduction degree greatly limit the thermal transport due to the severe phonon scatterings at the sheets boundaries.