Experimental study and modeling of residence time distribution in impinging stream reactor with GDB model

Lijun Ji,Kui Chen,Jiawen Zhu,Bin Wu 한국공업화학회 2010 Journal of Industrial and Engineering Chemistry Vol.16 No.4

Residence time distribution (RTD) in an impinging streams reactor with two or four nozzles was investigated with KCl solution as a tracer. The results showed that the flow pattern in the reactor was close to that in a continuous stirred tank reactor (CSTR). Macromixing process in the reactor was improved obviously when the opposite nozzles were added. Based on the analysis of flow region in the reactor, gamma distributionmodel with bypass (GDB) was applied for study on the RTD of the reactor. It was found that RTD in the impinging streams reactor could be finely described by the model. Also the effects of experimental conditions on parameters of model were analyzed according to the correlated values of the model parameters.

Extended electronic structure inhomogeneity created by double chain layer defects surrounding columnar tracks in heavy-ion irradiated YBa₂Cu₃O_{7−<i>δ</i>}

Kwon, Ji-Hwan,Meng, Yifei,Wu, Lijun,Zhu, Yimei,Zhang, Yifei,Selvamanickam, Venkat,Welp, Ulrich,Kwok, Wai-Kwong,Zuo, Jian-Min IOP 2018 Superconductor science & technology Vol.31 No.10

<P>In YBa<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>7−<I>δ</I> </SUB> (YBCO), heavy-ion irradiation creates continuous amorphous tracks that are highly effective for vortex pinning. However, the electronic structure landscape of defects and consequently their vortex pinning roles are unclear. Here, we show double chain layer (DCL) defects which intersect the columnar tracks are additionally produced by high energy Pb ion irradiation in YBCO. The DCL defects are ∼29 nm long, about three times the columnar defect diameter. The electronic structures of the DCL and columnar track defects were determined using atomic-resolution scanning transmission electron microscopy (STEM) and high resolution electron energy loss spectroscopy (EELS). Results show a decrease in the oxygen and copper content at the interface between the track and the YBCO matrix, resulting in interfacial strain. For the DCL defects, the STEM/EELS study revealed a localized electron doped CuO<SUB>2</SUB> plane next to the DCL defect. The DCL defects thus further extend the electronic inhomogeneity into YBCO.</P>

SOC balance‑based decentralized control strategy for hybrid energy storage in integrated power systems

Xueping Gao,Lijun Fu,Yan Zhang,Feng Ji 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.12

The hybrid energy storage systems (HESSs) in vessel integrated power systems can support pulse load and improve system stability. However, the unbalanced SOC of different energy storage devices can cause over-charge and over-discharge which damages the energy storage devices and affects the stable operation of the entire system, especially when there are multiple groups of HESSs. Therefore, a decentralized control strategy for the HESSs in integrated power systems (IPSs) based on extended droop control combined with SOC balance control is proposed in this paper. In the proposed strategy, SOC recovery control is introduced to the virtual capacitance droop coefficient of the supercapacitor, and SOC equalization control is introduced to the virtual resistance droop coefficient of the lithium battery to adjust the output characteristics of the HESS according to the SOC. Then the frequency response characteristics are analyzed and the stability of the system is calculated. Finally, the hardware in loop simulation is conducted to verify the effectiveness of the proposed strategy. Comparisons show that the proposed strategy can compensate for the pulse load according to the responding characteristics of the HESS and achieve SOC balance between different energy storage devices under various working conditions.

A Demand Side Management Strategy to Reduce the Impact of High Power Pulse Load Integration

Gao Xueping,Zhang Yan,Ji Feng,Fu Lijun 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.5

High pulsed power loads (HPPLs) are highly non-linear and can cause signifi cant stability and power quality issues in a microgrid. Developing alternative methods for controlling and analyzing the microgrid with multiple HPPLs will provide insight into tradeoff s that can be made during the design phase. In this paper, a demand side management strategy of HPPLs in a microgrid is formulated. Firstly, the HPPLs are divided into energy storage connected high power pulse loads (EHPPLs) and direct connected high power pulse loads (DHPPLs) according to the power use of the back-end loads, and the energy management models of both the EHPPLs and the DHPPLs are built. Then the demand side management strategy to minimize the impacts of running HPPLs is proposed. Finally, three typical cases are studied to verify the fl exibility and eff ectiveness of the proposed method. The simulation and experiment results indicate that the proposed strategy can eff ectively reduce the peak power demand of the HPPLs, thus reducing the impact on the microgrid

Endophytic Fungi from Dalbergia odorifera T. Chen Producing Naringenin Inhibit the Growth of Staphylococcus aureus by Interfering with Cell Membrane, DNA, and Protein

Yuan Gao,Yubin Ji,Wenlan Li,Fuling Wang,Fuling Wang,Xiaomeng Zhang,Zhihui Niu,Lulu Zhou,Lijun Yan 한국식품영양과학회 2021 Journal of medicinal food Vol.24 No.2

This study focused on the antibacterial effects of the endophytic fungi producing naringenin from Dalbergia odorifera T. Chen against Staphylococcus aureus. The antibacterial activity was measured by the inhibition diameters, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC). The time-killing curve was also used to evaluate its antibacterial efficacy. The results of antibacterial activity determinations showed that endophytic fungi secondary metabolites can inhibit the growth of five pathogenic bacteria (S. aureus, Escherichia coli, Salmonella enteritidis, Pseudomonas aeruginosa, and Bacillus subtilis) and the most sensitive strain was S. aureus that had the MIC and MBC values of 0.13 and 0.50 mg/mL, respectively. The membrane permeability study was measured by a DNA leakage assay and electrical conductivity assay. Furthermore, the whole-cell protein lysates and DNA fragmentation assay was evaluated. The morphology of S. aureus treated with the endophytic fungi products was observed by scanning electron microscopy (SEM). The probable antibacterial mechanism of endophytic fungi secondary metabolites was the increased membrane permeability that leads to leaks of nucleic acids and proteins. SEM results further confirmed that the extracts can interfere with the integrity of S. aureus cell membrane and further inhibit the growth of bacteria, resulting in the death of bacteria. This study provides a new perspective for the antibacterial functions of endophytic fungi secondary metabolites for biomedical applications.

Use of Long-chain Alcohol in Extraction and Purification of Lincomycin from Fermentation Broth

Wu, Bin,Zhu, Jiawen,Chen, Kui,Ji, Lijun,Guo, Jianguo,Zhao, Jianxi 한국화학공학회 2003 Korean Journal of Chemical Engineering Vol.20 No.2

Low selectivity for lincomycin in butanol extraction process leads to relatively higher content of impurities. A novel process for extraction of lincomycin from fermentation broth was studied in this work. Mixture of n-octanol and n-decanol is used as extractant to replace n-butanol in extraction of lincomycin. Oprimal operation conditions for the process have been studied. Due to higher extraction selectivity for lincomycin A by long-chain alcohol, content of impurity(lincomycin B) in the final product is much lower than that in product by butanol process. Furthemore, the practicability for combination of long-chain alcohol and butanol in purification of linecomycin was investigated.

Distribution and Source of Atmospheric Polycyclic Aromatic Hydrocarbons and Nitropolycyclic Aromatic Hydrocarbons in Tieling City, Liaoning Province, a Typical Local City in Northeast China

Tang, Ning,Araki, Yuki,Tamura, Kenji,Dong, Lijun,Zhang, Xuemei,Liu, Qiuhua,Ji, Ruonan,Kameda, Takayuki,Toriba, Akira,Hayakawa, Kazuichi Korean Society for Atmospheric Environment 2009 Asian Journal of Atmospheric Environment (AJAE) Vol.3 No.1

Airborne particulates were collected in three different size fractions (>7 ${\mu}m$; 2.1-7 ${\mu}m$; < 2.1 ${\mu}m$) by using Andersen low-volume air samplers at three sites in Tieling city, Liaoning Province, a typical local city in northeast China, in every season during the period from July 2003 to May 2004. Nine polycyclic aromatic hydrocarbons (PAHs) and seven nitropolycyclic aromatic hydrocarbons (NPAHs) in the airborne particulates were determined by HPLC with fluorescence and chemiluminescence detection, respectively. The mean total concentrations of the nine PAHs and seven NPAHs were highest at The mixed residential and light industrial site, and lowest at the residential site near the suburbs. At all sites, more than 70% of the total PAHs and more than 60% of the total NPAHs were found in the finest particulate (< 2.1 ${\mu}m$) fraction. Both cluster analysis and several diagnostic ratios showed that the major contributors of PAHs and NPAHs in airborne particulates were coal combustion systems such as domestic stoves and coal boilers in all seasons in Tieling city.

Properties and Reaction Mechanisms of Magnesium Phosphate Cement Mixed with Acetic Acid

Li Jun,Ji Yong-sheng,Huang Guo-dong,Xu Zhan-zhan,Yan Gui-hong 대한토목학회 2018 KSCE Journal of Civil Engineering Vol.22 No.1

Objective: This study aims to improve the coagulation time, strength, and construction cost of magnesium phosphate cement. Methods: We analyzed the microstructure changes in the hardened magnesium phosphate cement paste through qualitative analysis, quantitative test, microscopic examination, and research regarding adding different concentrations of acetic acid on magnesium phosphate cement slurry time, effects of flow resistance, and mechanical properties. Results: When a moderate amount of AA was used, the setting time of MAPC mortar was significantly prolonged but was later reduced as the concentration increased. In the early phase, the degree of MAPC mortar hydration increased, whereas compressive strength significantly increased initially and increased slowly in the later phase. The crystal morphology and size of MAPC hydrates changed, and hardened MAPC became more compact in structure. The AA absorbed some ammonia in the MAPC condensation. Conclusion: Acetic acid can effectively regulate coagulation time, induce early hydration reaction rate, and improve the performance of magnesium phosphate cement, which can reduce the construction cost of magnesium phosphate cement.