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Cross-subcarrier precoder design for massive MIMO-OFDM downlink with symplectic optimization

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Science China(Information Sciences) 2025年

作者： Yu-Xuan ZHANG An-An LU Xiang-Gen XIA Xi-qi GAO National Mobile Communications Research Laboratory Southeast University Purple Mountain Laboratories Department of Electrical and Computer Engineering University of Delaware

We propose a cross-subcarrier precoder design(CSPD) for massive multiple-input multiple-output(MIMO) orthogonal frequency division multiplexing(OFDM) downlink. This work aims to significantly improve the channel estimation and signal detection performance by enhancing the smoothness of the frequency domain effective channel. This is accomplished by designing a few vectors known as the transform domain precoding vectors(TDPVs), which are then transformed into the frequency domain to generate the precoders for a set of subcarriers. To combat the effect of channel aging, the TDPVs are optimized under imperfect channel state information(CSI). The optimal precoder structure is derived by maximizing an upper bound of the ergodic weighted sum-rate(WSR) and utilizing the a posteriori beam-based statistical channel model(BSCM). To avoid the large-dimensional matrix inversion, we propose an algorithm with symplectic optimization. Simulation results indicate that the proposed cross-subcarrier precoder design significantly outperforms conventional methods.

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Metal nanoparticles decorated CoFe-(oxy)hydroxysulfides nanosheets fabricated by a general strategy for electrocatalytic water splitting

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Journal of Energy Chemistry 2025年第1期100卷 26-38页

作者： Xiaodong Yang Haochen Shen Xiaoming Xiao Zhichao Li qi Zhou Wei Yang Bin Jiang Yongli Sun Luhong Zhang Zhenhua Yan School of Chemical Engineering and Technology Tianjin University Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education) Nankai University

This study presents a novel method to fabricate metal-decorated,sulfur-doped layered double hydroxides （M/SLDH） through spontaneous redox and sulfurization *** developed Ag/SLDH and Pt/SLDH catalysts with abundant heterogeneous interfaces and hierarchical nanostructures demonstrated outstanding oxygen evolution reaction （OER） and hydrogen evolution reaction （HER） performance,achieving low overpotentials of 212 and 35 mV at 10 mA cm-2in 1 M KOH,*** both anode and cathode in water splitting,they required only 1.47 V to reach 10 mA cm-2and exhibited high structural robustness,maintaining stability at 1000 mA cm-2for 300 ***-situ Raman analysis revealed that the synergistic effects of metal nanoparticles and S doping significantly promote the transformation into the S-Co1-xFexOOH layer,which serves as the active phase for water ***,ultraviolet photoelectron spectroscopy （UPS） and density functional theory （DFT） analyses indicated that incorporating metal nanoparticles and S doping increase electron density near the Fermi level and reduce reaction energy barriers,thus enhancing intrinsic OER and HER *** study provides a scalable strategy for synthesizing high-performance electrocatalysts for water splitting,with promising potential for broader applications.

关键词： Ultraviolet photoelectron spectroscopy

Tribology behaviors of Ti-Ni51.5 at% shape memory alloy with different microstructures and textures

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Rare Metals 2021年第12期40卷 3616-3626页

作者： Rui Yang song Li Nan Zhang chao Wang Ting-Mei Wang qi-Hua Wang Key Laboratory of Science and Technology on Wear and Protection of Materials Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China

The microstructure characteristics of TiNi alloy were investigated to elucidate the active deformation mechanisms during hot rolling and the corresponding tribology *** deformation was mainly dominated by a combination of mechanical twinning involving the {114}_(B2) and {112}_(B2) twins,dislocations,and stacking faults during the manufacturing ***,various heat treatments were performed to differentiate the discrepancies in tribological behaviors of hot-rolled and heattreated ***-rolled microstructures with high defect density approximate to nanoscale precipitates through aging as the wear resistance of the alloy improves,albeit it is softer compared to the aged *** demonstrated by the X-ray diffraction(XRD) results of the wear tracks,microstructures undergo the stress-induced martensitic(SIM) transformation during dry *** differential scanning calorimetry(DSC) analysis,the martensitic transformation temperature is lowered by defects in the austenite *** activation of the SIM transformation can be a sluggish process owing to the effect of twinning,where both primary and secondary twins are ***,a reversible transformation that is related to pseudoelasticity causes a decrease in wear volume at room temperature,which is higher than the austenite finish ***,abrasive wear advances toward ***,the hot-rolled sheet with y fiber-{111}//ND(normal direction) exhibits better wear resistance compared to the sheet with α fiber-{100}//ND.

关键词： B2 twin Texture Precipitates Tribology performance Ti-Ni51.5 at%

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带电高空接过引线自动手臂电源系统仿真设计

仪表技术 2011年第11期 64-66页

作者：韩维建王志吴崇勇叶露宋起超马成哈尔滨第二电业局黑龙江哈尔滨150001 黑龙江工程学院黑龙江哈尔滨150050

文章利用Pspice电路仿真软件对带电高空接过引线自动手臂反激式高压电源进行了分析,并利用Pspice对设计的电源进行了仿真模拟。通过改变电路元件参数,对比仿真输出结果的差异,分析了元件参数的不同对电源实际性能的影响程度,进而给实际... 详细信息

文章利用Pspice电路仿真软件对带电高空接过引线自动手臂反激式高压电源进行了分析,并利用Pspice对设计的电源进行了仿真模拟。通过改变电路元件参数,对比仿真输出结果的差异,分析了元件参数的不同对电源实际性能的影响程度,进而给实际开关电源的设计指出了方向。

关键词：高压电线 PWM Pspice 反激式电源

Effects of CeO_2 on the XPS valence band spectra of coal under the combustion initialization stage at 400℃

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International Journal of Minerals,Metallurgy and Materials 2013年第4期20卷 338-344页

作者： Cheng-lin qi Jian-liang Zhang chao Ma Gen-sheng Feng Zhong-ping song State Key Laboratory of Advanced Metallurgy University of Science and Technology Beijing Shougang Research Institute of Technology

In order to get the catalytic mechanism of CeO2 on graphite and coal at 400℃, the morphologies of coal, graphite, and CeO2 before and after combustion were analyzed through X-ray photoelectron spectroscopy （XPS）. It is found that the particle size of coal is mostly between 11.727 and 64.79 μm, while the particle size of CeO2 is between 1.937 and 11.79 μm. The agglomeration of coal and CeO2 can be seen by scanning electron microscopy （SEM） after reaction. XPS results show that with the addition of CeO2, the intensity of binding energy gets stronger, but there is no energy peak transition. Comparing the character of coal with and without the addition of CeO2, it can be seen that the C C bond fractures first at 400℃, while the C-H energy-band takes electrons at the same time to be far away from the Fermi level, and the O 2s, O 2p, and C sp hybrid orbitals are all excited. Adding CeO2 can enhance the activity of the whole coal. In addition, through XPS analysis, combined with the oxygen transfer theory and the electron transfer theory, the catalytic mechanism of CeO2 for pulverized coal combustion could be obtained.

关键词： coal combustion cerium oxide valence bands catalysis binding energy X-ray photoelectron spectroscopy pulverized fuel

Propagation Characteristics of Plane Explosion Wave in Layered Concrete Media

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兵工学报 2015年第S1期36卷 228-232页

作者： DONG Yong-xiang song qi LU Zhi-chao CUI Miao FENG Shun-shan State Key Laboratory of Explosion Science and Technology Beijing Institute of Technology

Layered concrete media with different wave impedance materials under one-dimensional strain are studied by numerical simulation. The four typical prototypes are analyzed,including concrete foam,air,steel plate and concrete as the middle layer,and the upper and lower layers are concrete materials. The propagation characteristics of plane blast wave in the concrete structure are illustrated,including the propagation and attenuation of stress wave across the different interlayers,the wave reflection and transmission at layered interfaces,the peak value of stress in the lower concrete and the total energy distribution in various medium layers. The result shows that the role of soft interlayer in concrete structure is mainly due to its low wave impedance,the waveform of incident wave is changed,the stress wavelength is pull wide,the radial diffusion of energy is enhanced,and the stress amplitude of and the energy input into the third layer are reduced. Meanwhile,it has been also proved that the air interlayer is able to reduce the peak value of explosion wave which is obviously different from that of foamed material. As a result,it should be concerned about stress amplitude and energy in order to get the best protective structure.

关键词： explosion wave layered concrete wave impedance numerical simulation

Development of a general circumferentially nonuniform heat transfer fuel rod model for subchannel analysis and application to helical fuel rods

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Science China Technological Sciences 2025年

作者： Junsen FU Junlong LI Xiaowen WANG qi ZHANG Yao XIAO Hanyang GU School of Mechanical Engineering Shanghai Jiao Tong University Key Laboratory of Nuclear Power Systems and Equipment of the Ministry of Education Shanghai Jiao Tong University National Key Laboratory of Nuclear Reactor Technology Nuclear Power Institute of China State Key Laboratory of Nuclear Power Safety Technology and Equipment Shanghai Jiao Tong University

The subchannel analysis method is one of the most crucial transient safety analysis methods in the thermal design of nuclear reactors. The nonuniformity of circumferential heat transfer is slight in conventional pressurized water reactor (PWR)cores, but it is significant in advanced reactors with wire-wrapped or helical fuel rods. Predicting circumferentially nonuniform heat transfer behavior can be challenging owing to the complex geometry of helical fuel rods. In this study, a general circumferentially nonuniform heat transfer fuel rod (GCNF) model is developed to predict the fuel central temperature and circumferential heat flux and wall temperature. This model incorporates a refined two-dimensional fuel conduction model and circumferential nonuniform shape factor, addressing the dual factors contributing to the circumferential nonuniformity of helical fuel rods. An empirical correlation for the nonuniform shape factor is developed based on the computational fluid dynamics (CFD) results, and it is implemented to the subchannel code. The newly developed model is applied to a helical fuel annulus and validated by comparing the prediction results with CFD data. The maximum wall temperature predicted by the code is 1.15°C lower than the value calculated through CFD. In terms of the heat flux, the maximum value at the inner corner is22 kW lower than that obtained from the CFD prediction. The accurate prediction of circumferentially nonuniform heat transfer in helical fuel, concerning the surface heat flux and cladding temperature, addresses existing shortcomings in helical fuel subchannel analysis methods. Additionally, the capability to predict the fuel central temperature is essential for the safety analysis to determine whether fuel rods are melting. The generality of the model framework allows it to be used for the prediction of circumferential nonuniform heat transfer behavior in other types of fuel assemblies.

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Visible-light-responsive homologous heterostructure of oxynitrides constructed to boost charge separation and water splitting

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Science China Chemistry 2025年第01期 186-191页

作者： Hai Zou Yunfeng Bao Xueshang Xin Yu qi Tengfeng Xie Fuxiang Zhang State Key Laboratory of Catalysis Dalian National Laboratory for Clean Energy Dalian Institute of Chemical Physics Chinese Academy of Sciences School of Chemistry and Chemical Engineering Liaoning Normal University College of Chemistry Jilin University

Constructing type II heterostructures represents a widely recognized strategy for enhancing charge separation and photocatalytic efficiency,but it remains challenging to fabricate homologous heterostructures based on visible-light-responsive semiconductors,especially for popularly investigated （oxy）nitrides with low thermal ***,we synthesized a homologous heterostructure （denoted as YTON＿H） based on the oxynitrides of YTaO4-xNyand YTa *** heterostructure exhibits type II band structure alignment and intimate interface achieved through a magnesium （Mg） powder-assisted nitridation *** with widely reported heterologous heterostructures,the as-obtained YTON＿H homologous heterostructure could similarly exhibit enhanced charge separation as well as photocatalytic water splitting performance with respect to its counterparts(YTaO4-xNyand YTaON2).Meanwhile,detailed structural characterizations and spectroscopy analysis have been made to confirm the formation of heterostructure and promotion of spatial charge separation.

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克希霍夫三维偏移中的反假频技术

内蒙古石油化工 2005年第4期31卷 99-101页

作者：马建波王锡文孙丽萍朱武宋启潮中原油田分公司物探研究院中原油田分公司采油厂中原油田对外经济贸易总公司河南濮阳457001

克希霍夫三维偏移过程中,由于受假频的影响,偏移成像结果的质量往往会降低。针对这一现象,主要探讨了算子反假频问题。其思路是首先获取相关的算子假频准则,然后通过对地震道进行局部的三角形滤波,从而实现对偏移算子进行反假频处理。... 详细信息

克希霍夫三维偏移过程中,由于受假频的影响,偏移成像结果的质量往往会降低。针对这一现象,主要探讨了算子反假频问题。其思路是首先获取相关的算子假频准则,然后通过对地震道进行局部的三角形滤波,从而实现对偏移算子进行反假频处理。通过实际资料的应用可看出,与常规孔径加权法相比,基于三角形滤波的反假频技术能够有效地去除算子假频。

关键词：三维偏移克希霍夫假频技术偏移成像三角形算子地震道加权法滤波