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Numerical Simulation of Fluid Flow and Heat Transfer in Funnel Shaped Mold of Thin Slab Continuous Caster

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Journal of Iron and Steel Research International 2005年第6期12卷 14-19页

作者： ZHU miao-yong WANG jun ZHANG Ying Northeastern University Shenyang 110004 China

Thin slab casting is used widely in the world. The control of molten steel flow and solidification in the mold is difficult due to the high casting speed and complicated configuration of the mold. Numerical simulation was carried out to study the fluid flow and heat transfer in the funnel shaped mold. The influence of nozzle design, casting speed and nozzle submersion depth on the flow and temperature fields in the mold was investigated, and guidance for selecting configurations of submerged nozzle was obtained.

关键词： thin slab continuous casting fluid flow heat transfer numerical simulation

Synergistic Effects of Aluminum Hypophosphite on Intumescent Flame Retardant Polypropylene System

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Chinese Journal of Polymer Science 2015年第2期33卷 318-328页

作者： miao-jun Xu Jing Wang Yue-hang Ding 李斌 Heilongjiang Key Laboratory of Molecular Design and Preparation of Flame Retarded Materials College of ScienceNortheast Forestry University

The effects of aluminum hypophosphite（AHP） as a synergistic agent on the flame retardancy and thermal degradation behavior of intumescent flame retardant polypropylene composites（PP/IFR） containing ammonium polyphosphate（APP） and triazine charring-foaming agent（CFA） were investigated by limiting oxygen index（LOI）, UL-94 measurement, thermogravimetric analysis（TGA）, cone calorimeter test（CONE）, scanning electron microscopy（SEM） and X-ray photoelectron spectroscopy（XPS）. It was found that the combination of IFR with AHP exhibited an evident synergistic effect and enhanced the flame retardant efficiency for PP matrix. The specimens with the thickness of 0.8 mm can pass UL-94 V-0 rating and the LOI value reaches 33.5% based on the total loading of flame retardant of 24 wt%, and the optimum mass fraction of AHP/IFR is 1：6. The TGA data revealed that AHP could change the degradation behavior of IFR and PP/IFR system, enhance the thermal stability of the IFR and PP/IFR systems at high temperatures and promote the char residue formation. The CONE results revealed that IFR/AHP blends can efficiently reduce the combustion parameters of PP, such as heat release rate（HRR）, total heat release（THR）, smoke production rate（SPR） and so on. The morphological structures of char residue demonstrated that AHP is of benefit to the formation of a more compact and homogeneous char layer on the materials surface during burning. The analysis of XPS indicates that AHP may promote the formation of sufficient char on the materials surface and improve the flame retardant properties.

关键词： Synergistic effect Intumescent flame retardant Aluminum hypophosphite Thermal degradation Polypropylene

Preparation of Poly(phosphoric acid piperazine) and Its Application as an Effective Flame Retardant for Epoxy Resin

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Chinese Journal of Polymer Science 2018年第5期36卷 655-664页

作者： miao-jun Xu Si-Yu Xia Chuan Liu Bin Li Heilongjiang Key Laboratory of Molecular Design and Preparation of Flame Retarded Materials College of Science Northeast Forestry University

A phosphorus-nitrogen containing flame retardant additive of poly（phosphoric acid piperazine）, defined as PPAP, was synthesized by the salt-forming reaction between anhydrous piperazine and phosphoric acid, and the dehydration polymerization under heating in nitrogen atmosphere. Its chemical structure was well characterized by Fourier transform infrared（FTIR） spectroscopy, ^（13）C and ^（31）P solid-state nuclear magnetic resonance measurements. The synthesized PPAP and curing agent m-phenylenediamine were blended into epoxy resin（EP） to prepare flame retardant EP thermosets. The effects of PPAP on the fire retardancy and thermal degradation behavior of cured EP/PPAP composites were investigated by limiting oxygen index（LOI）, vertical burning（UL-94）, thermogravimetric analysis/infrared spectrometry（TG-IR） and cone calorimeter tests. The morphologies and chemical compositions of char residues for cured epoxy resin were investigated by scanning electron microscopy（SEM） and X-ray photoelectron spectroscopy（XPS）, respectively. The results demonstrated that the flame retardant EP thermosets successfully passed UL-94 V-0 flammability rating and the LOI value was as high as 30.8% when incorporating 5 wt% PPAP into the EP thermosets. The TGA results indicated that the synthesized PPAP flame retardant additive possessed high thermal stability and excellent charring capability. Meanwhile, the incorporation of PPAP stimulated the epoxy resin matrix to decompose and charring ahead of time due to its catalytic decomposition effect, which led to a higher char yield at high temperature. The morphological structures and the analysis results of XPS for char residues of EP thermosets revealed that the introduction of PPAP benefited the formation of a sufficient, more compact and homogeneous char layer containing phosphorus-nitrogen flame retardant elements on the material surface during combustion. The formed char layer with high quality effectively prevented the heat transmission and d

关键词： Synthesis Poly(phosphoric acid piperazine) Flame retardant Epoxy resin thermosets Thermal degradation

Characteristics and implications of stress state in a gold mine in Ludong area, China

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International Journal of Minerals,Metallurgy and Materials 2018年第12期25卷 1363-1372页

作者： Peng Li Mei-feng Cai Qi-feng Guo Sheng-jun miao School of Civil and Resource Engineering University of Science and Technology Beijing Key Laboratory of High-Efficient Mining and Safety of Metal Mines (Ministry of Education of China) University of Science and Technology Beijing Beijing Key Laboratory of Urban Underground Space Engineering University of Science and Technology Beijing

In this study, we obtained information from twenty-one measurement points on the stress magnitudes and orientations of a gold mine in the Ludong area. We used the overcoring technique with an improved hollow inclusion strain gauge and then analyzed the distribution characteristics of the in situ stress field. The results indicate that the stress field is characterized by σH > σh > σv and σH > σv > σh(where σH, σh, and σv are the maximum horizontal, minimum horizontal, and vertical principal stresses, respectively). The regional stress field is dominated by horizontal principal stress. The σH, σh, and σv values show a gradual increasing trend with depth. The σH is predominantly oriented in the NWW–SEE or near-EW direction. We also confirmed the correspondence between the measured stress field and the regional geological structure. In addition, based on the measured stress data, we discuss the implications of the in situ stress with respect to fault activity in the mine area.

关键词： in situ stress measurement improved hollow inclusion strain gauge stress field geological structure fault activity

Simulation experiment of AE-based localization damage and deformation characteristic on covering rock in mined-out area

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International Journal of Minerals,Metallurgy and Materials 2009年第3期16卷 255-260页

作者： Sheng-jun miao Xing-ping Lai Xing-guang Zhao Fen-hua Ren School of Civil ＆ Environmental Engineering University of Science and Technology Beijing Beijing 100083 China School of Energy Engineering Xi＇an University of Science and Technology Xi＇an 710054 China

The localization damage and deformation characteristics of multiple rock in mined-out area under thick soil layer were investigated by acoustic emission （AE）-based physical similar simulation experiment and damage test combined with the AE theory on rock damage. During different mining courses, the degree of wall rock suffered from mining disturbed process in mined-out area was different, so did the AE density of initial damage and fracture. Some characteristic parameters, including large events, total events, and energy rate, presented fluctuations with temporal and spatial change and take on a certain extent statistic relation. Subsequently, the percent of damage degree was defined and divided into 4 stages, and the localization damage and deformation characteristics of surrounding rock in mined-out area and coal pillars were analyzed quantitatively.

关键词： acoustic emission soil layer underground mine rock damage in-site monitoring

Effect of annealing atmosphere on magnetic properties of pure ZnO and Na:ZnO films

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Rare Metals 2012年第1期31卷 27-30页

作者： Wu, Kai Xu, Xiaoguang Yang, Hailing Zhang, Jianli miao, jun Jiang, Yong State Key Laboratory for Advanced Metals and Materials School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China

Pure ZnO and Zn0.96Na0.04O films were grown on quartz substrates by sol-gel *** XRD analysis revealed that all thin films had hexagonal wurtzite structure and obvious c-axis preferred *** was precisely measured by an alternating gradient magnetometer (AGM).To explore the nature original ferromagnetism,the effect of annealing atmosphere on magnetic properties of the films was *** with pure ZnO,magnetic hysteresis loops showed that doping Na atoms enhanced saturation *** mag-netism of the films annealed in the air atmosphere was significantly better than that in the O2 *** photoluminescence (PL) spec-trum analysis suggested that the ferromagnetism was due to the defects in the films.

关键词： pure ZnO Na-doped ZnO anneal sol-gel

Online prediction of EEG based on KRLST algorithm

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High Technology Letters 2021年第4期27卷 357-364页

作者： Lian Zhaoyang Duan Lijuan Chen juncheng Qiao Yuanhua miao jun Faculty of Information Technology Beijing University of TechnologyBeijing 100124P.R.China Beijing Key Laboratory of Trusted Computing Beijing 100124P.R.China National Engineering Laboratory for Key Technologies of Information Security Level Protection Beijing 100124P.R.China Faculty of Sciences Beijing University of TechnologyBeijing 100124P.R.China Beijing Key Laboratory of Internet Culture and Digital Dissemination Research School of Computer ScienceBeijing Information Science and Technology UniversityBeijing 100101P.R.China

Kernel adaptive algorithm is an extension of adaptive algorithm in nonlinear,and widely used in the field of non-stationary signal *** the distribution of classic data sets seems relatively regular and simple in time *** distribution of the electroencephalograph(EEG)signal is more randomness and non-stationarity,so online prediction of EEG signal can further verify the robustness and applicability of kernel adaptive ***’s more,the purpose of modeling and analyzing the time series of EEG signals is to discover and extract valuable information,and to reveal the internal relations of EEG *** time series prediction of EEG plays an important role in EEG time series *** this paper,kernel RLS tracker(KRLST)is presented to online predict the EEG signals of motor imagery and compared with other 13 kernel adaptive *** experimental results show that KRLST algorithm has the best effect on the brain computer interface(BCI)dataset.

关键词： brain computer interface(BCI) kernel adaptive algorithm online prediction of electroencephalograph(EEG)

A Synchrotron in situ X-ray Study on the Multiple Melting Behaviors of Isomorphous Poly(3-hydroxybutyrate-co-3-hydroxyvalerate)(P(HB-co-HV))with Middle HV Content

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Chinese Journal of Polymer Science 2020年第9期38卷 1015-1024,I0008页

作者： Hao Zhu You Lv Dan Shi Yi-Guo Li Wei-jun miao Zong-Bao Wang Ningbo Key Laboratory of Specialty Polymers State Key Laboratory Base of Novel Functional Materials and Preparation ScienceFaculty of Materials Science and Chemical EngineeringNingbo UniversityNingbo 315211China

The multiple endothermic peaks without observable recrystallization phenomenon of isomorphous poly(3-hydroxybutyrate-co-3-hydroxyvalerate)[P(HB-co-HV)]with the middle HV content of 19.4 mol%and 28.7 mol%were confirmed by differential scanning calorimetry(DSC),and the evolutions of crystal structure and lamellar morphology in the heating and melting process were tracked by in situ synchrotron wide angle X-ray diffraction(WAXD)and small angle X-ray scattering(SAXS)*** emergence of asymmetric features of both the diffraction peaks and scattering curves indicates the coexistence of different lamellar crystals with varied unit cell *** on the in situ WAXD and SAXS measurements,we calculated the evolutions of the unit cell parameters a and b as well as the long period and lamellar thickness upon *** comparative analysis of WAXD and SAXS data confirms that the multiple endothermic peaks of P(HB-co-19.4%HV)and P(HB-co-28.7%HV)result from the melting of different lamellae rather than the melting/*** thinner,unstable uniform lamellae with HV counits total inclusion melt first and the thicker,stable sandwich lamellae with HV counits partial inclusion melt *** addition,the large second melting peak in P(H B-co-19.4%HV),differing from that of samples with HV content of 28.7 mol%and 36.2 mol%,is due to the unique state of HV content leading to a transition of sandwich lamellae to uniform *** present study establishes the relationship between the different lamellae structure and multiple melting behaviors of isomorphous copolymer.

关键词： P(HB-co-HV) Isomorphous Middle HV content Synchrotron radiation

Robust interface-induced unusual anomalous Hall effect in Mn_(3)Sn/Pt bilayers

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Rare Metals 2022年第9期41卷 3012-3018页

作者： jun-Jie Liu Kang-Kang Meng Ji-Kun Chen Yong Wu jun miao Xiao-Guang Xu Yong Jiang School of Materials Science and Engineering University of Science and Technology BeijingBeijing100083China

Interface-driven magnetic phenomena related to spin-orbit coupling and intrinsic symmetry breaking are of great significance to the development of spintronics materials and ***_(3)Sn is a natural antiferromagnetic material with a non-collinear magnetic structure,and its anomalous Hall effect(AHE)has been reported to have high crystal anisotropy and temperature dependent ***,a large unusual anomalous Hall effect(UAHE)in the(0001)c-axis orientation Mn_(3)Sn/Pt bilayers in the whole temperature range from 5 to 300 K is reported,which is absent in single MnSn film.

关键词： film. unusual effect