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Acta Mathematica Sinica,English Series 2020年第6期36卷 631-637页

作者： János KOLLáR chen yang xu Princeton University Princeton NJ 08544-1000USA MIT CambridgeMA 02139-4307USA

We prove that the irreducible components of the moduli space of polarized Calabi–Yau pairs are projective.

关键词： Polarized Calabi–Yau stable pairs Moduli spaces

Semi-stable Extensions Over 1-dimensional Bases

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Acta Mathematica Sinica,English Series 2018年第1期34卷 103-113页

作者： Janos KOLLAR Johannes NICAISE chen yang xu Department of Mathematics Princeton University Department of Mathematics Imperial CollegeSouth Kensington Campus Beijing International Center of Mathematics Research

Given a family of Calabi-Yau varieties over the punctured disc or over the field of Laurentseries, we show that, after a finite base change, the family can be extended across the origin while keeping the canonical class trivial. More generally, we prove similar extension results for families whose log-canonical class is semi-ample. We use these to show that the Berkovich and essential skeleta agree for smooth varieties over C（（t）） with semi-ample canonical class.

关键词： Semi-stable extension Laurent series essential skeleton

Effect of Al2O3 on the viscosity of CaO-SiO2-Al2O3-MgO-Cr2O3 slags

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International Journal of Minerals,Metallurgy and Materials 2021年第5期28卷 797-803页

作者： chen-yang xu Cui Wang Ren-ze xu Jian-liang Zhang Ke-xin Jiao School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing 100083China State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China

We investigated the effect of Al2O3 content on the viscosity of CaO-SiO2-Al2O3-8wt%MgO-1wt%Cr2O3(mass ratio of CaO/SiO2 is 1.0,and Al2O3 content is 17wt%-29wt%)*** results show that the viscosity of the slag increases gradually with increases in the Al2O3 content in the range of 17wt%to 29wt%due to the role of Al2O3 as a network former in the polymerization of the aluminosilicate structure of the *** increases in the Al2O3 content from 17wt%to 29wt%,the apparent activation energy of the slags also increases from 180.85 to 210.23 kJ/mol,which is consistent with the variation in the critical *** Fourier-transform infrared spectra indicate that the degree of polymerization of this slag is increased by the addition of *** application of Iida’s model for predicting the slag viscosity in the presence of Cr2O3 indicates that the calculated viscosity values fit well with the measured values when both the temperature and Al2O3 content are at relatively low levels,i.e.,the temperature range of 1673 to 1803 K and the Al2O3 content range of 17wt%-29wt%in CaO-SiO2-Al2O3-8wt%MgO-1wt%Cr2O3 slag.

关键词： slag viscosity high aluminium oxide apparent activation energy structure viscosity prediction

Random projection method for ultra wideband signal acquisition

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The Journal of China Universities of Posts and Telecommunications 2011年第6期18卷 14-21页

作者： LIN Jie SHI Guang-ming chen xu-yang ZHANG Li School of Electronic Engineering Xidian University Xi＇an 710071 China

High-speed high-resolution analog-to-digital （A/D） conversion demanded by ultra wideband （UWB） signal processing is a very challenging problem. This paper proposes a parallel random projection method for UWB signal acquisition. The proposed method can achieve high sampling rate, high resolution and technical feasibility of hardware implementation. In the proposed method, an analog UWB signal is projected over a set of random sign functions. Then the low-rate high-resolution analog-to-digital convertors （ADCs） are used to sample the projection coefficients. The signal can be reconstructed by simple linear calculation with the sampling matrix, without complying with optimization algorithm and prior knowledge. In other aspects, unlike other approaches that need to utilize an accurate time-shift at extremely high frequency, or design a hybrid filter bank, or generate specific basis functions or work for signals with prior knowledge, the proposed method is a universal sampling approach and easy to apply. The simulation results of signal to noise ratio （SNR） and spurious-free dynamic range （SFDR） validate the efficiency of the proposed method for UWB signal acquisition.

关键词： random projection high speed high resolution data acquisition UWB signal

Direct electrochemistry and electrocatalysis of horseradish peroxidase in MnO_2 nanosheet film

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Chinese Science Bulletin 2008年第8期53卷 1152-1156页

作者： XIAO Han WU JinLing chen xu yang WenSheng State Key Laboratory of Chemical Resource Engineering Beijing University of Chemical Technology Beijing 100029 China

A novel material MnO2 nanosheet has been used as the support matrix for the immobilization of horseradish peroxidase (HRP). HRP entrapped in MnO2 nanosheet film exhibits facile direct electron transfer with the electron transfer rate constant of 6.86 s-1. The HRP/MnO2 nanosheet film gives a re- versible redox couple with the apparent formal peak potential (E0′) of -0.315 V (vs. Ag/AgCl) in pH 6.5 phosphate buffer solution (PBS). The formal potential E0′ of HRP shifts linearly with pH with a slope of -53.75 mV·pH-1, denoting that an electron transfer accompanies single-proton transportation. The immobilized HRP shows an electrocatalytic activity to the reduction of H2O2. The response time of the biosensor for H2O2 is less than 3 s, and the detection limit is 0.21 μmol·L-1 based on signal/noise = 3.

关键词：过氧化物酶 HRP 二氧化锰纳米薄片直流电化学过氧化氢

A quantitative investigation on consolidation of titanium-containing pellets during roasting process

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Journal of Iron and Steel Research International 2023年第1期30卷 40-50页

作者： Yao-zu Wang Jian-liang Zhang Zhi-hui chen Zheng-jian Liu chen-yang xu Yu-meng Li Li-ming Ma Institute of Artificial Intelligence University of Science and Technology BeijingBeijing 100083China School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing 100083China College of Artificial Intelligence North China University of Science and TechnologyTangshan 063210HebeiChina

The measurement method and quantitative indexes of iron ore consolidation characteristic temperature(CCT)during roasting,including consolidation starting temperature,highest consolidation rate temperature,and consolidation termination temperature,were improved based on previous *** mineral properties of V-Ti magnetite(Panzhihua)were analyzed,and the CCT of V-Ti magnetite was *** investigate the effect of mineral types on CCT,a series of trials were carried out by using various ores,including high-grade magnetite ore,high silicon iron ore,and V-Ti magnetite *** greatest shrinkage of V-Ti magnetite was 6.7%,the consolidation starting temperature was 991℃,and the termination temperature was 1384℃.The results of X-ray diffraction analysis indicated that the V-Ti magnetite ore was composed of titanomagnetite,peridotite,and other minerals,which is more complicated than conventional *** a result,the temperature at the maximum rate of consolidation and the temperature at the termination of consolidation are the ***_(3) and MgFe_(2)O_(4) in V-Ti magnetite may inhibit the creation of sinter necks between hematite *** phase occurs inside the pellet when the temperature surpasses 1250℃,which may accelerate particle growth and the formation of a sintering neck within the pellets.

关键词： Consolidation index Iron ore pellet Mineralogical characteristics V-Ti magnetite

Effect of organic binders on the activation and properties of indurated magnetite pellets

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International Journal of Minerals,Metallurgy and Materials 2021年第7期28卷 1145-1152页

作者： Cui Wang chen-yang xu Zheng-jian Liu Yao-zu Wang Rong-rong Wang Li-ming Ma State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing 100083China Department of Ferrous Metallurgy RWTH Aachen UniversityIntzestraße 152072 AachenGermany

In the ironmaking process,the addition of an organic binder to replace a portion of bentonite has the potential to improve the per-formance of *** interaction between original bentonite(OB)and organic binder was *** indicated that the micromor-phology of organic composite bentonite(OCB)became porous and the infrared difference spectrum exhibited a curved *** addition,the residual burning rates of OB and organic binder were determined to be 82.72%and 2.30%,***,the influence of OCB on the properties of pellets was *** compressive strength of OCB-added green pellets(14.7 N per pellet)was better than that of OB-ad-ded pellets(10.3 N per pellet).Moreover,the range of melting temperature of OCB-added green pellets(173℃)was narrower than that of OB-added pellets(198℃).The compressive strength of OCB-added green pellets increased from 2156 to 3156 N per pellet with the increase in roasting temperature from 1200 to 1250℃.

关键词： pellets organic composite bentonite softening-melting property interaction behavior

Propagation of shock waves in dry and wet sandstone:Experimental observations,theoretical analysis and meso-scale modeling

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Defence Technology（防务技术） 2018年第5期14卷 513-521页

作者： Chuang Liu yang Wu Xian-feng Zhang Jia-jie Deng chen-yang xu Wei Xiong Meng-ting Tan School of Mechanical Engineering Nanjing University of Science and TechnologyNanjingXiaolingwei 200NanjingChina NO.208 Reseach Institute of China Ordnance Industries BeijingChina

Methods of experimental observations, theoretical analysis and meso-scale modeling were used to study the propagation processes of shock waves in dry and wet sandstone under dynamic impact in this *** to the results from the dynamic impact experiments with velocity of 0.2-0.5 km/s, it was found that the velocity of shock wave increases linearly with water content. Additionally, the velocity of the shock wave in the sandstone showed a linearly increased regularity with the increasement of the impact velocity, which was proved by theory in this paper. Furthermore, meso-scale simulation models were performed and the simulation results showed that sandstone's porosity reduced the shock waves velocity compared to nonporous materials. Pore space filled with water counteracts the effects of porosity, resulted in larger shock wave velocity.

关键词： Dynamic impact Shock wave Meso-scale simulation Sandstone

A broadband metamaterial cylindrical lens antenna

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Chinese Science Bulletin 2010年第19期55卷 2066-2070页

作者： MA HuiFeng chen Xi yang XinMi xu HongSheng chenG Qiang CUI TieJun State Key laboratory of MiUimeter Waves School of lnformation Science and Engineering Southeast University Nanjing 210096 China

We present a Luneberg-like cylindrical lens antenna experimentally using *** cylindrical lens antenna with a broad bandwidth is made up of the non-resonant I-shaped metamaterial *** near-field distributions of the metamaterial lens antenna are measured using a two-dimensional near-field microwave scanning apparatus,and agree well with the simulation *** far-field radiation patterns of the antenna are also presented to show the high-gain performance in the broad bandwidth.

关键词：透镜天线圆柱材料宽带介质结构带宽性能二维近场近场分布

Softening–melting behavior of mixed burden based on low-magnesium sinter and fluxed pellets

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International Journal of Minerals,Metallurgy and Materials 2021年第4期28卷 621-628页

作者： Gui-lin Wang Jian Kang Jian-liang Zhang Yao-zu Wang Zhi-yu Wang Zheng-jian Liu chen-yang xu School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing 100083China School of Chemical Engineering The University of QueenslandSt LuciaQLD 4072Australia Institute of Artificial Intelligence University of Science and Technology BeijingBeijing 100083China Baosteel Zhanjiang Iron and Steel Co. Ltd.Zhanjiang 524072China

A low MgO content in sinter is conducive to reduce the MgO content in blast furnace *** study investigated the effect of MgO content in sinter on the softening–melting behavior of the mixed burden based on fluxed *** the MgO content increased from 1.31 wt% to 1.55 wt%, the melting temperature of sinter increased to 1521℃.Such an increase was due to the formation of the high-meltingpoint slag *** reduction degradation index of sinter with 1.31 wt% MgO content was better than that of *** initial softening temperature of the mixed burden increased from 1104 to 1126℃ as MgO content in sinter increased from 1.31 wt% to 1.55 wt%, and the melting temperature decreased from 1494 to 1460℃.The permeability index(S-value) of mixed burden decreased to 594.46 kPa·℃ under a high MgO content with 1.55 wt%, indicating that the permeability was *** slag phase composition of burden was mainly akermarite(Ca_(2)MgSiO_(7)) when the MgO content in sinter was 1.55 wt%.The melting point of akermarite is 1450℃, which is lower than other phases.

关键词： magnesia softening–melting behavior low-magnesium sinter fluxed pellets slag