Time-domain simulations of transient response in LiFePO4 cathode lithium ion batteries

Xiaoping Xu,Miao Shui,Weidong Zheng,Jie Shu,Lei Hui,Linxia Xu,Liangliang Cheng,Lin Feng,Yuanlong Ren 한국물리학회 2014 Current Applied Physics Vol.14 No.5

The time domain transients of batteries comprised of LiFePO4 cathode material exhibit large nonlinearity with the increasing discharging rates. Hence, the calculated overpotential transients match the experimental determined well only when the discharging current is low enough. The results of electrochemical impedance spectra at different OCV level indicate that the change of the parameters of equivalent circuit or even the circuit architecture are probably responsible for the large discrepancy between the predicted and the measured transient profiles. By taking the change of equivalent circuit model at high discharging current into consideration, we successfully simulate the time domain transients of polarization within the entire discharging current range. Also with the help of circuit analysis, the contribution of the ohmic resistance, charge transfer impedance and solid-state diffusion impedance to total polarization has been differentiated as a function of discharging time.

Investigation on characteristics of pressure fluctuation in a centrifugal pump with clearance flow

Lulu Zheng,Xiaoping Chen,Wei Zhang,Zu-chao Zhu,Jinglei Qu,Mengmeng Wang,Xiaojie Ma,Xueli Cheng 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.9

Clearance flow has great impact on pressure fluctuation of centrifugal pumps. Numerical calculations are performed to study the pressure fluctuation characteristics of centrifugal pump with wear ring clearance, especially in the regions of interaction between main flow and clearance flow (IMC) and clearance. The accuracy of numerical calculations is illustrated by comparing the experiments of performance and pressure fluctuation. Results show that, in clearance region the pressure fluctuation is still governed by blade passing frequency (f BPF ). Its amplitude of dominate frequency of pressure fluctuation becomes larger as the probe approaches the impeller exit. In IMC region, the pressure fluctuation at impeller outlet is dominated by f BPF . However, the dominate frequency at the entrance of impeller is less than f BPF . In addition, as the flow rate increased, the amplitude of dominate frequency of pressure fluctuation increases at impeller entrance, whereas an inverse trend is observed at wear ring clearance region.

The Biotypes, Wing-forms and the Immigration of Brown Planthopper, Nilaparvata lugens Stal, in Zhejiang Province, China

Yu, Xiaoping,Lu, Zhongxian,Wu, Guorui,Tao, Linyong,Chen, Jianming,Zheng, Xusong,Xu, Hongxing Korean Society of Applied Entomology 2001 Journal of Asia-Pacific Entomology Vol.4 No.2

The virulence change (biotype), wing form development and immigration of brown planthopper (BPH) Nilaparvata lugens Stal, population in Zhejiang province was studied as compared to these BPH populations collected from Guangxi and Yunnan province, China and Philippines. The results indicate that the Zhejiang population could successfully infest variety IR26 and Mudgo after 1989, and ASD7 and IR36 after 1998, showing the characters of BPH biotype 2 and biotypes 3. The BPH tropical populations such as Guangxi population, however, adapted the resistant varieties IR26, Mudgo and ASD7 earlier. In 1997, the nymphal survival indices of Guangxi and Yunnan populations on Rathu Heenati (Bph3) were up to 70.9 and 66.7 respectively, higher than Zhejiang population. The Zhejiang populations show low brachupterous rates and have a negative correlation with nymphal density, belonging to the temperate type. The Philippine populations are almost brachypterous, however, the brachypterous rates of BPH males raise with the increase of nymphal density. The Guangxi population has a high brachypterous rate, being similar to the tropical type. On the other hand, tests showed that the lowest survival rate, longer duration of nymphs and the lightest weight of brachypterous female occurred in the $2^{nd}$ generation of BPH after continuously feeding on resistant variety. Physiologically, the highest activities of superoxide dismutase (SOD) and catalase (CAT) were detected in the second generation of the BPH feeding on resistant rice variety.

Effects of clearance flow on the characteristics of centrifugal pump under low flow rate

Lulu Zheng,Xiaoping Chen,Hua-Shu Dou,Wei Zhang,ZuChao Zhu,Xueli Cheng 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.1

The Reynolds averaged Navier-Stokes equations and the shear stress transport k-ω turbulence model are employed to simulate the centrifugal pump with or without clearance flows. The simulation results have been compared with the experimental data and good agreement has been achieved. Results show that clearance flow causes a decrease in the characteristics of the centrifugal pump, particularly in pressure fluctuation. The largest deviation of the amplitude of pressure fluctuation between the centrifugal pump with and without clearance flow is 65.34 %. The numerical results also show that the clearance flow causes collision impact with the mainstream flow and forms a multiple vortex structure at the impeller entrance. Clearance flow greatly affects the pressure distribution in the impeller passage, which is opposite to the volute tongue, especially at the suction side of the blade surface. The wave distribution decreases along the direction of the hub to the shroud, which indicating that the influence of clearance flow weakens along this direction.

Gene microarray analysis revealed a potential crucial gene RACK1 in oral squamous cell carcinoma (OSCC)

Jian-Wei Zheng,Yinshen Yang,Shujuan Yang,Wei Zhou,Hongtian Qiu,Xiaoping Li,Qiuyun Cai,Ting Li,Gang Luo 한국통합생물학회 2018 Animal cells and systems Vol.22 No.2

Oral squamous cell carcinoma (OSCC) is the sixth most common cancer worldwide, which appears as a consequence of multiple molecular genetic events in various chromosomes and genes. In order to unveil the possible mechanisms underlying OSCC tumorigenesis, the OSCC-related gene expression variance and the gene interaction network should be further investigated. Herein, we conducted the NimbleGen Human Gene Expression Microarray to analyze expression heterogeneity between OSCC primary tumor tissue and its adjacent normal tissue from two patients. A total number of 7872 out of 32,448 detected genes are differentially expressed in OSCC. Gene ontology (GO) analysis demonstrated that these differentially expressed transcripts were critical in a series of metabolic processes, cancer-related signal pathways, and biological regulations. KEGG signaling pathway enrichment suggested a number of pathways (metabolic process and immune response) which are frequently enrolled during cancer progression. 15 most differential regulated genes between OSCC tumor and non-tumor were confirmed by quantitative reverse transcription polymerase chain reaction (qRT-PCR). Furthermore, the interaction network analysis of these confirmed genes by STRING database showed the two subunits of RACK1 had direct interaction with 14 differential proteins. This bioinformatics research lends support about the critical role of RACK1 which functions as a key node protein driving OSCC development.

Numerical simulation and analysis of flow characteristics in the front chamber of a centrifugal pump

Yang Wu,Xiaoping Chen,Hua-Shu Dou,Lulu Zheng,ZuChao Zhu,BaoLing Cui,Boo Cheong Khoo 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.11

We performed numerical simulations to study the flow characteristic in a centrifugal pump based on the RANS equations and the RNG k-ε turbulent model. The flow field, including the front and back pump chambers, the impeller wear-ring, the impeller passage, the volute casing, the inlet section and outlet section was calculated to obtain accurate numerical results of fluid flow in a centrifugal pump. The flow characteristic was studied from the internal flow structure in pump chambers, the radial velocity at impeller outlet as well as the pressure inside of the pump, the circumferential velocity and the radial velocity in front pump chamber. The variation of flow parameters in internal flow versus flow rate in the centrifugal pump was analyzed. The results show that the overall performance of the pump is in good agreement with the experimental data. The simulation results show that the distribution of flow field in the front pump chamber is axial asymmetry. The energy dissipation at the impeller outlet is larger than other areas. The distribution of the circumferential velocity and that of radial velocity are similar along the axial direction in the front pump chamber, but the distribution of flow is different along the circumferential and the radial directions. It was also found that the vorticity is large at the impeller inlet compared with other areas.

Kinetic Monte Carlo Simulation of Nucleation at the Initial Stage of Thin Film Growth

Peifeng Zhang,Deyan He,Xiaoping Zheng 한국물리학회 2005 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.46 No.1

Nucleation at the initial stage of thin ¯lm growth has been simulated by using a three-dimensional kinetic Monte Carlo technique. The morphologies of the nucleation were taken by computer-graphic technique. It has been shown that the size of the island nucleation increases with increasing sub- strate temperature. A maximum nucleation density can be obtained for each deposition rate. The temperature Tn at which the nucleation density maximizes is a function of the deposition rate. The nucleation density decreases with decreasing deposition rate at substrate temperatures higher than Tn. A transition from two-dimensional to three-dimensional nucleation was observed at higher substrate temperatures and lower deposition rates.

Genome sequencing and analysis of Kloeckera apiculata strain 34-9, a biocontrol agent against postharvest pathogens in citrus

Chao-an Long,Kai Chen,Xiaoping Yang,Feng Zheng 한국유전학회 2017 Genes & Genomics Vol.39 No.1

Kloeckera apiculata, as the anamorphic state of Hanseniaspora uvarum from the Ascomycota phylum, plays an important role in the inhibition of fungal diseases in plants and spontaneous wine fermentation. This study was performed to sequence and analyze the whole genome of K. apiculata strain 34-9; This analysis provides further genomic features and assists functional research. The complete genome was determined using an Illumina HiSeq 2000 system applying paired-end and mate-pair methods to construct four reads libraries. The data assembly of all the reads resulted in a total genome size of 8.1 Mb, including 106 contigs, which were assembled into 41 scaffolds with a 31.95 % G?C content and a 234X sequence coverage. The performance of the gene prediction and functional annotation revealed that 2724 of 3786 protein- coding genes matched the KOG database, and 1127 genes were classified into GO categories. Further genome features analyses found 1066 microsatellite sites, 71 tRNAs, 3 rRNAs and 3 microRNAs in the genomic DNA. A prediction of the metabolic pathways identified potentially crucial genes for explaining the phenylalanine pathway involved in biocontrol. Comparisons with the typical yeasts Lachancea thermotolerans, Kluyveromyces lactis and Saccharomyces cerevisiae revealed the particularity and difference of K. apiculata strain 34-9. The genome alignments among Hanseniaspora vineae T02/19AF, K. apiculata DSM 2768 and 34-9 indicated numerous homologous regions distributed over the genomes between strain DSM2768 and 34-9. A SSR analysis identified that mono- and tri- nucleotide repeat types were more abundant in all six types, likely affecting the evolution of K. apiculata.

Comparative studies on potential dependent electrochemical impedance spectroscopy of cathode material 0.5Li2MnO3$0.5LiNi0.5Mn0.5O2 for the initial two charging cycles

Chao Chen,Shu Chen,Miao Shui,Xiaoping Xu,Weidong Zheng,Lin Feng,Jie Shu,Yuanlong Ren 한국물리학회 2015 Current Applied Physics Vol.15 No.2

Cathode material 0.5Li2MnO3·0.5LiNi0.5Mn0.5O2 is successfully synthesized by citrate acid assisted sol -gel method and shows pretty good electro-chemical performance. To elucidate the electro-chemical reactions and charge carrier transportation kinetics in the charge-discharge process, series of electrochemical impedance spectra for the first and the second charge process are measured on multiple given state of charges. The rapid augmentation of resistance to electronic conduction and ionic conduction within the voltage range 4.45-4.6 V where the removal of Li2O from Li2MnO3 component takes place gives us more evidence about the complicated “structurally integrated” feature of this material. The relatively large span of the arc responsible for electronic conduction and the extremely large Mn3+ related charge transfer resistance at the beginning of the second charging indicate that after one complete charge-discharge cycle, Li2MnO3 and LiNi0.5Mn0.5O2 domains still reserve its original structure and will keep its structure for the followed cycles.

Simultaneous Determination of Phenobarbital, Pentobarbital, Amobarbital and Secobarbital in Raw Milk via Liquid Chromatography with Electron Spray Ionization Tandem Mass Spectrometry

Huaixiang Tian,Xingxin Zhou,Chen Chen,Yabin He,Haiyan Yu,Xiaoping Zheng 한국축산식품학회 2017 한국축산식품학회지 Vol.37 No.6

A rapid, sensitive and specific liquid chromatography-tandem mass spectrometry (LC-MS/ MS) method was developed for the simultaneous determination of four barbiturates (phenobarbital, pentobarbital, amobarbital and secobarbital) in raw milk. The barbiturates were extracted using liquid-liquid extraction, ultrasonication and centrifugation, and purified on an SPE column. Analytes were separated by HPLC on a CSH C18 column eluted using an acetonitrile- water system with a linear gradient dilution programme, and detected by MS/MS. The recoveries of the barbiturates were 85.0-113.5%, and the intra- and inter-assay RSDs were less than 9.8% and 7.3%, respectively. The limit of detection was 5 ng/mL for all four of the barbiturates. The analytical method exhibited good linearity from 10 to 1000 ng/mL; the correlation coefficient (r2) was greater than 0.9950 for each barbiturate. This method was also applied to the determination of barbiturates in real milk samples and was found to be suitable for the determination of veterinary drug residues in raw milk.