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Dong, Qi,Lu, Chunyuan,Tulugan, Kelimu,Jin, Chunzi,Yoon, Soo Jong,Park, Yeong Min,Kim, Tae Gyu American Scientific Publishers 2016 Journal of nanoscience and nanotechnology Vol.16 No.2
<P>Multi wall carbon nanotubes (MWCNTs) and diamond are renowned as superlative material due to their relatively high thermal conductivity and hardness while comparing with any bulk materials. In this research, polyacrylonitrile (PAN) solution incorporated with MWCNTs at an alteration of mass fractions (0 wt%, 0.6 wt%, 1 wt%, 2 wt%) were fabricated via electrospinning under optimized parameters. Dried composite nanofibers were stabilized and carbonized, after which water base polytrafluorethylene (PTFE) mixed with nano diamond powder solution was spin coated on them. Scanning electron microscopy, Raman spectroscopy, X-ray scattering and Laserflash thermal conductivity were used to characterize the composite nanofiber sheets. The result shows that the thermal conductivity increased to 4.825 W/m K from 2.061 W/mK. The improvement of thermal conductivities is suggesting the incorporation of MWCNTs.</P>
Dong, Qi,Bao, Han,Lee, Byunghong,Kim, Jeong Wan,Bae, Mun Ki,Park, Yeong Min,Choi, Hyun-Kuk,Yoon, Su Jong,Kim, Tae Gyu American Scientific Publishers 2016 Journal of nanoscience and nanotechnology Vol.16 No.11
<P>In this study, a series of PAN nanofibers with MWCNTs contents range from 1.96 wt% to 5.66 wt% were successfully prepared by electrospinning technique, and thermal conductivity and electrical resistivity were investigated. Firstly, the nanofibers were electrospun, and stabilization and carbonization reactions then occurred by a tube furnace at 280 degree and 1000 degree. The structural features of the obtained composite carbon nanofibers were characterized using scanning electron microscopy (SEM), X-ray diffractometer system (XRD), and Raman spectroscopy. The average thermal diffusivity was measured by using a Laser Flash Analyzer (LFA). The electrical resistivity was evaluated via Sheet Resistance Measurement. With the increasing the mass fraction of MWCNTs to 5.66 wt%, thermal conductivity was conspicuously increased by 33% and electrical resistivity was decreased 80 times.</P>
Investigation on the Temperature Characteristics of Water Inner-Cooled Stator Coil of HTS Motor
Dong Qi,Zhao Junjie,Zhou Yong,Fu Xiaoli 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.6
This study investigates the temperature characteristics of water inner-cooled stator coil based on Litz wire for high temperature superconducting (HTS) motor. Rich experience in transposed Litz bundle windings is accumulated by manufacturing scaled-down water inner-cooled coil prototypes for high-capacity HTS motors. On this basis, the temperature rise test and calculation simulation are carried out. The maximum relative error between the two results is only 5.13%, which verified the rationality of the numerical temperature field calculation method. Subsequently, the effects of pipe blockage and epoxy thermal conductivity changes on the coil temperature are further explored. Thus, a relatively complete method for evaluating the temperature characteristics of water inner-cooled windings is formed, which can greatly help guide the design and manufacture of future high-capacity HTS motors.
Dongqi Liao,Jianjun Li,Duanfang Sun,Meiying Xu,Taicheng An,Guo-Ping Sun 한국생물공학회 2015 Biotechnology and Bioprocess Engineering Vol.20 No.4
A pilot-scale biotrickling filter (BTF) was designed to treat volatile organic compounds (VOCs) emitted from a typical waste printed circuit board (WPCB) pyrolysis workshop. Measured by gas chromatography-mass spectrometry (GC-MS), the main components of VOCs and their concentrations were benzene, toluene, chlorobenzene, ethyl-benzene, xylene, styrene, benzaldehyde, and trimethyl-benzene. The removal efficiencies of the BTF for these compounds ranged from 81.1 to 97.8% after 90 days of operation. The maximum elimination capacity of 25.94 g/m3 h was obtained with the inlet loading of 30.72 g/m3 fixed the fixed empty-bed residence time (EBRT) of 9.80 sec. Hazard ratio index based on threshold limit value for time weighted average (TLV-TWA) and VOCs concentrations indicated that the cancer risk of VOCs was significantly reduced after the BTF treatment. The microbial community analysis revealed initial inoculum and some emerging bacteria played crucial roles in the improvement of BTF performance with the biodegradation of this kind of VOCs by the polymerase chain reactiondenaturing gradient gel electrophoresis (PCR-DGGE) technique and pyrosequencing analyses indicated that proteobacteria phylum was the dominant in the BTF. All above results indicated that VOCs with multicomponent and fluctuant concentrations from a typical waste printed circuit board pyrolysis workshop were removed efficiently and in an environmentally friendly way by the biofiltration method.
Dongqi Jiang,Huamin Li,Shuyang Sun 한국식품과학회 2020 Food Science and Biotechnology Vol.29 No.12
The search for enzymes with histamine-degradingactivity is of great interest, since it has great potential inthe way of solving the problem of high histamine levels infood. In this study, the gene of a novel histamine-degradingenzyme, i.e., glyceraldehyde-3-phosphate dehydrogenase(GAPDH) from Lactobacillus plantarum was cloned andsuccessfully expressed in Escherichia coli DH5a, with therecombinant host determined as histamine-degradingactive. The recombinant GAPDH was then purified tohomogeneity by ammonium sulfate fraction and gel filtration. The optimum pH and temperature were 5.5 and 40 Cand it was strongly resistant to SO2 and ethanol. Afterwards,the histamine degradative activity of partiallypurified GAPDH in actual wine environments (grape andcherry wines) was examined by incubating the enzymes inthe middle, near the end and completion of malolacticfermentation, and histamine in the correspondingcontaminated wines was decreased by 36.8–52.4%,59.6–66.9% and 83.1–85.5%, respectively.
Trend-GRU Model based Time Series Data Prediction in Melt Transport Process
Dongqi Zhao,Kuangrong Hao,Lei Chen,Bing Wei,Xue-Song Tang,Xin Cai,Lihong Ren 제어로봇시스템학회 2019 제어로봇시스템학회 국제학술대회 논문집 Vol.2019 No.10
Temperature and pressure are two important performance indicators during the melt transport of polyester fiber production, which can affect the overall properties of the melt. Therefore, the accurate prediction of these two indicators is crucial for the control of melt properties. This paper proposes a data prediction model, Trend-GRU (Gated Recurrent Unit), which can extract the feature of unstable change of the melt data. On the premise that the model is not over-complicated, a new structure is designed to extract the feature of unstable change to improve the prediction accuracy. Two data sets on temperature and pressure collected from the actual production process of a spinning factory are used for comparative experiments. The results show that the accuracy of the data prediction of the proposed model is better than the original one.
Error-immune Algorithm for Absolute Testing of Rotationally Asymmetric Surface Deviation
Yanwei Zhang,Dongqi Su,Le Li,Yongxin Sui,Huaijiang Yang 한국광학회 2014 Current Optics and Photonics Vol.18 No.4
Based on Zernike polynomial fitting, we propose an algorithm believed to be new for interferometric measurements of rotationally asymmetric surface deviation of optics. This method tests and calculates each angular surface by choosing specified rotation angles with lowest error. The entire figure can be obtained by superimposing these sub-surfaces. Simulation and experiment studies for verifying the proposed algorithm are presented. The results show that the accuracy of the proposed method is higher than single-rotation algorithm and almost comparable to the rotation-averaging algorithm with fewer rotation measurements. The new algorithm can achieve a balance between the efficiency and accuracy.