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Microstructure evolution and mechanical properties of a large-sized ingot of Mg–9Gd–3Y–1.5Zn–0.5Zr(wt%) alloy after a lower-temperature homogenization treatment

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International Journal of Minerals,Metallurgy and Materials 2017年第3期24卷 271-279页

作者： Zhi-yong xue yue-juan Ren Wen-bo Luo Yu Ren ping xu Chao xu School of Energy Power and Mechanical EngineeringNorth China Electric Power University School of Materials Science and Engineering University of Science and Technology Beijing College of Science Rocket Force University of Engineering

In this paper,a large-sized ingot of Mg–9Gd–3Y–1.5Zn–0.5Zr(wt%) alloy with a diameter of 600 mm was successfully prepared by the semi-continuous casting *** alloy was subsequently annealed at a relatively low temperature of 430°C for 12 h as a homogenization *** microstructure and room-temperature mechanical properties of the alloy were investigated *** results show that the as-cast alloy contained a mass of discontinuous lamellar-shaped 18 R long-period stacking ordered(LPSO) phases with a composition of Mg10 Zn Y and an α-Mg matrix,along with net-shaped Mg5(Y,Gd) eutectic compounds at the grain *** of the eutectic compounds dissolved after the homogenization ***,the amount and dimensions of the lamellar-shaped LPSO phase obviously increased after the homogenization *** structure of the phase transformed into 14H-type LPSO with composition Mg12Zn(Y,Gd).The mechanical properties of the heat-treated large-sized alloy ingot are *** ultimate tensile strength(UTS) and tensile yield strength(TYS) of the alloy reached 207.2 MPa and 134.8 MPa,respectively,and the elongation was 3.4%.The high performances of the large-sized alloy ingot after the homogenization treatment is attributed to the strengthening of the α-Mg solid solution and to the plentiful LPSO phase distributed over the α-Mg matrix.

关键词： magnesium alloys ingots homogenization microstructural evolution mechanical properties

Interference management with adaptive fractional frequency reuse for LTE-A femtocells networks

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The Journal of China Universities of Posts and Telecommunications 2013年第2期20卷 86-91页

作者： ZHANG Wei-dong WANG Ying xu Ming-yue ZHANG ping Wireless Technology Innovation Institute Beijing University of Posts and Telecommunications

This paper presents a novel interference management strategy, to adaptively choose the best fractional frequency reuse （FFR） scheme for macro and femto networks. The strategy aims to maximize the system throughput taking into account a number of system constraints. Here, the system constrains consist of the outage constraints of two-tier users and macrocell spectral efficiency requirement. The detailed procedures of our proposed strategy are： 1） A reference signal received power （RSRP） based selection algorithm is presented to adaptively select the optional FFR schemes satisfying the outage constraints. 2） Considering the macrocell spectral efficiency, the optimal FFR scheme is selected from the optional FFR schemes at MeNB side, to achieve the maximum system throughput in two-tier femtocell networks. We study the efficacy of the proposed strategy using an long term evolution advanced （LTE-A） system level simulator. Simulation results show that our proposed interference management strategy can select the best FFR scheme to maximize the system throughput, and the FFR schemes derived by using RSRP-based selection algorithm can be the effective solutions to deploy femtocells in macrocells.

关键词： femtocell FFR outage probability spectral efficiency RSRP

Three-dimensional tracking of GLUT4 vesicles in TIRF microscopy

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2008年第2期9卷 232-240页

作者： Xiang-ping WU Jie-yue LI Ying-ke xu Ke-di xu Xiao-xiang ZHENG Department of Biomedical Engmeermg Zhejiang University Hangzhou 310027 China College of Information Engineering China Jiliang University Hangzhou 310018 China

TIRF microscopy has provided a means to view mobile granules within 100 nm in size in two *** quantitative analysis of the position and motion of those granules requires an appropriate tracking *** this paper,we present a new tracking algorithm combined with the unique features of *** a fluorescence correction procedure was processed to solve the problem of fluorescence bleaching over *** granules were then segmented from a time-lapse image stack by an adaptive background subtraction *** filter was introduced to estimate and track the granules that allowed reducing searching range and hence greater reliability in tracking *** the tracked granules were located in x-y plane,the z-position was indirectly inferred from the changes in their *** the experiments the algorithm was applied in tracking GLUT4 vesicles in living adipose *** results indicate that the algorithm has achieved robust estimation and tracking of the vesicles in three dimensions.

关键词： GLUT4 Total internal reflection fluorescence (TIRF) microscopy Adaptive background subtraction Kalman filter Fluorescence correction

A Delayed HIV Infection Model with the Homeostatic Proliferation of CD4^(+)T Cells

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Acta Mathematicae Applicatae Sinica 2022年第2期38卷 441-462页

作者： Qiang-hui xu Ji-cai HUANG yue-ping DONG Yasuhiro TAKEUCHI School of Mathematics and Statistics and Hubei Key Laboratory of Mathematical Sciences Central China Normal UniversityWuhan 430079China College of Science and Engineering Aoyama Gakuin UniversityKanagawa 252-5258Japan

In this paper,we investigate a delayed HIV infection model that considers the homeostatic prolif-eration of CD4^(+)T *** existence and stability of uninfected equilibrium and infected equilibria(smaller and larger ones)are studied by analyzing the characteristic equation of the *** intracellular delay does not affect the stability of uninfected equilibrium,but it can change the stability of larger positive equilibrium and Hopf bifurcation appears inducing stable limit ***,direction and stability of Hopf bifur-cation are well investigated by using the central manifold theorem and the normal form *** numerical simulation results show that the stability region of larger positive equilibrium becomes smaller as the increase of time ***,when the maximum homeostatic growth rate is very small,the larger positive equilibrium is always *** the contrary,when the rate of supply of T cells is very small,the larger positive equilibrium is always unstable.

关键词： HIV infection and persistence T cell homeostatic proliferation delayed model dynamics analysis Hopf bifurcation

Simulation of the Direct Radiative Effect of Mineral Dust and Sea Salt Aerosols in a Doubled Carbon Dioxide Climate

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Atmospheric and Oceanic Science Letters 2013年第5期6卷 343-348页

作者： yue xu LIAO Hong TANG Jin-ping Climate Change Research Center Chinese Academy of Sciences (CAS) Nansen-Zhu International Research Center Institute of Atmospheric Physics (IAP) School of Engineering and Applied Sciences Harvard University State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC) Key Laboratory of Middle Atmosphere and Global Environment Observation University of CAS

The authors examine the equilibrium climatic response to the direct radiative effect （DRE） of mineral dust and sea salt aerosols in a doubled-CO2 climate with two-way coupling of aerosol-climate *** response to the drier and windier conditions,dust emissions increase by 26％ in the Sahara Desert and by 18％ on the global scale relative to present *** salt emissions increase in high latitudes （＞60°） but decrease in middle latitudes （30°-60°） of both hemispheres due to the poleward shift of westerlies,leading to a 3％ decrease in global *** burdens of dust and sea salt increase by 31％ and 7％ respectively,because reductions in rainfall over the tropical oceans increase the lifetime of particles in the warmer *** higher aerosol loading in the doubled-CO2 climate reinforces aerosol DRE by -0.2 W m-2,leading to an additional cooling of 0.1℃ at the surface compared with the climatic effects of aerosols in present *** additional cooling from changes in natural aerosols compensates for up to 15％ of the regional warming induced by doubled CO2.

关键词： mineral dust sea salt aerosol direct radiative effect

Structural,electronic,and magnetic properties of vanadium atom-adsorbed MoSe2 monolayer

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Chinese Physics B 2017年第2期26卷 392-398页

作者： ping Llu Zhen-Zhen Qin Yun-Liang yue xu Zuo College of Electronic Information and Optical Engineering Nankai University Tianjin 300071 China

Using the first-principles calculations, we study the structural, electronic, and magnetic properties of vanadium adsorbed MoSe_2 monolayer, and the magnetic couplings between the V adatoms at different adsorption concentrations. The calculations show that the V atom is chemically adsorbed on the MoSe_2 monolayer and prefers the location on the top of an Mo atom surrounded by three nearest-neighbor Se atoms. The interatomic electron transfer from the V to the nearestneighbor Se results in the polarized covalent bond with weak covalency, associated with the hybridizations of V with Se and Mo. The V adatom induces local impurity states in the middle of the band gap of pristine MoSe_2, and the peak of density of states right below the Fermi energy is associated with the V- dz^2 orbital. A single V adatom induces a magnetic moment of 5 μBthat mainly distributes on the V-3d and Mo-4d orbitals. The V adatom is in high-spin state, and its local magnetic moment is associated with the mid-gap impurity states that are mainly from the V-3d orbitals. In addition,the crystal field squashes a part of the V-4s electrons into the V-3d orbitals, which enhances the local magnetic *** magnetic ground states at different adsorption concentrations are calculated by generalized gradient approximations（GGA） and GGA＋U with enhanced electron localization. In addition, the exchange integrals between the nearest-neighbor V adatoms at different adsorption concentrations are calculated by fitting the first-principle total energies of ferromagnetic（FM） and antiferromagnetic（AFM） states to the Heisenberg model. The calculations with GGA show that there is a transition from ferromagnetic to antiferromagnetic ground state with increasing the distance between the V adatoms. We propose an exchange mechanism based on the on-site exchange on Mo and the hybridization between Mo and V, to explain the strong ferromagnetic coupling at a short distance between the V adatoms. However, the ferromagneti

关键词： V-adatom MoSe2 monolayer magnetic moment magnetic coupling first-principles calculation

Olfactory ensheathing cells promote nerve regeneration and functional recovery after facial nerve defects

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Neural Regeneration Research 2019年第1期14卷 124-131页

作者： Jian Gu He xu Ya-ping xu Huan-Hai Liu Jun-Tian Lang Xiao-ping Chen Wei-Hua xu yue Deng Jing-ping Fan Department of Otolaryngology Shanghai Ninth People's Hospital Shanghai Jiao Tong University School of Medicine Department of Otolaryngology Head and Neck Surgery Changzheng Hospital Second Military Medical University Department of Otolaryngology Head and Neck Surgery Gongli Hospital Second Military Medical University

Olfactory ensheathing cells from the olfactory bulb and olfactory mucosa have been tbund to increase axonal sprouting and pathfinding and promote the recovery of vibrissae motor performance in facial nerve transection injured rats. However, it is not yet clear whether olfactory ensheathing cells promote the reparation of facial nerve defects in rats. In this study, a collagen sponge and silicone tube neural conduit was implanted into the 6-mm defect of the buccal branch of the facial nerve in adult rats. Olfactory ensheathing cells isolated from the olfactory bulb of newborn Sprague-Dawley rats were injected into the neural conduits connecting the ends of tile broken nerves, the morphology and function of the regenerated nerves were compared between the rats implanted with olfactory ensheathing cells with the rats injected with saline. Facial paralysis was assessed. Nerve electrography was used to measure facial nerve-induced action potentials. Visual inspection, anatomical microscopy and hematoxylin-eosin staining were used to assess the histomorphology around the trans planted neural conduit and the morphology of the regenerated nerve. Using fluorogold retrograde tracing, toluidine blue staining and lead uranyl acetate staining, we also measured the number of neurons in the anterior exterior lateral f：acial nerve motor nucleus, the number of myelinated nerve fibers, and nerve fiber diameter and myelin sheath thickness, respectively. After surgery, olfactory ensheathing cells de- creased facial paralysis and the latency of the facial nerve-induced action potentials. There were no differences in the general morphology of the regenerating nerves between the rats implanted with olfactory ensheathing cells and the rats injected with saline. Between-group results showed that olfactory ensheathing cell treatment increased the number of regenerated neurons, improved nerve fiber morphology, and increased the number of myelinated nerve fibers, nerve fiber diameter, and myel

关键词： nerve regeneration facial nerve defects olfactory ensheathing cells nerve fibers myelination neurons nerve muscle action potentials facial nerve motor nucleus neural regeneration

Knowledge-enhanced semantic communication system with OFDM transmissions

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Science China(Information Sciences) 2023年第7期66卷 266-282页

作者： Xiaodong xu Huachao XIONG Yining WANG yue CHE Shujun HAN Bizhu WANG ping ZHANG State Key Laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications Department of Broadband Communication Peng Cheng Laboratory

As a promising technology to enable effective multi-modal transmission over wireless channels,semantic communication has attracted a lot of attention from academics and industries. Different from Shannon’s information theory, based on common background knowledge provided by the knowledge base, the goal of semantic communication is transmitting intended useful information from the transmitter and recovered by the receiver at the semantic level. However, the existing studies on semantic communication rarely emphasize the essence and the usage of the knowledge base. In this paper, we propose a knowledge-enhanced semantic communication(KESC) system, where the knowledge base is cloud-edge-device collaborative cached. To solve the problem that float-type symbols are difficult to transmit directly through a radio frequency(RF)system, we adopt orthogonal frequency division multiplexing(OFDM) to transmit semantic vectors directly without some traditional signal processing techniques in semantic information transmission, and the semantic pilot is designed to assist semantic reception. Furthermore, we formulate a multi-encoder transformer based neural network model for the KESC system to support text transmission(KESC-T), where the decoder is implemented with a knowledge graph to enhance the performance of semantic decoding. Besides, we define knowledge-enhanced efficiency(KEE) to measure the gain in semantic recovery accuracy brought by per unit of knowledge. Simulation results demonstrate that the recovery accuracy of our proposed KESC outperforms the compared scheme, especially in low signal-to-noise ratio(SNR) or resource-constrained scenarios.

关键词： semantic communication knowledge graph OFDM transformer deep learning

Nature-inspired Three-dimensional Au/Spinach as a Binder-free and Self-standing Cathode for High-performance Li-O_(2) Batteries

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Chemical Research in Chinese Universities 2022年第1期38卷 200-208页

作者： WANG yue WANG Xiaoxue SHE ping GUAN Dehui SONG Lina xu Jijing State Key Laboratory of Inorganic Synthesis&Preparative Chemistry Jilin UniversityChangchun 130012P.R.China International Center of Future Science Jilin UniversityChangchun 130012P.R.China

Design and fabrication of functional porous air cathode materials with superior catalytic activity is still the key point for non-aqueous lithium-oxygen(Li-O2) batteries. Herein, inspired by the self-standing three-dimensional(3D) structure of the natural spinach leaves, a unique binder-free and self-standing porous Au/spinach cathode for high-performance Li-O2 batteries has been developed. The carbonized spinach leaves serve as a superconductive current collector and an ideal porous host for accommodating catalysts. The Au/spinach cathode could offer enough spaces for accommodating the discharge products, shorten the distance of the oxygen and electrolyte diffusion, and promote the oxygen reduction reaction(ORR) and oxygen evolution reaction (OER) processes. This optimized Au/spinach cathode achieved a high specific area capacity of 7.23 mA‧h/cm2 at a current density of 0.05 mA/cm2 and exhibited excellent stability(280 cycles at 0.05 mA/cm2 with a fixed capacity of 0.2 mA‧h/cm2). The superior performance encourages the construction of more advanced cathode architectures by the use of bio-composites for Li-O2 batteries.

关键词： Li-O_(2)battery Carbon derivation Nature-inspired structure Natural spinach leaf Superior performance