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Secure resource allocation against colluding eavesdropping in a user-centric cell-free massive multiple-input multiple-output system

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Frontiers of Information Technology & Electronic Engineering 2024年第4期25卷 500-512页

作者： Na LI Yuanyuan GAO Kui XU Xiaochen XIA Huazhi HU Yang LI Yueyue zhang College of Communication Engineering Army Engineering University of PLANanjing 210007China

We investigate the resource allocation problem of a cell-free massive multiple-input multiple-output system under the condition of colluding eavesdropping by multiple passive *** address the problem of limited pilot resources,a scheme is proposed to allocate the pilot with the minimum pollution to users based on access point selection and optimize the pilot transmission power to improve the accuracy of channel *** at the secure transmission problem under a colluding eavesdropping environment by multiple passive eavesdroppers,based on the local partial zero-forcing precoding scheme,a transmission power optimization scheme is formulated to maximize the system’s minimum security spectral *** results show that the proposed scheme can effectively reduce channel estimation error and improve system security.

关键词： Cell-free Colluding eavesdropping Limited pilot resources Access point selection Security rate

Partial aging can counter-intuitively couple with sulfidation to improve the reactive durability of zerovalent iron

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Frontiers of Environmental Science & Engineering 2024年第2期18卷 1-11页

作者： Yiwei Liu Kaili Gu Jinhua zhang Jinxiang Li Jieshu Qian Jinyou Shen Xiaohong Guan Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse School of Environmental and Biological EngineeringNanjing University of Science and TechnologyNanjing 210094China School of Ecological and Environmental Sciences East China Normal UniversityShanghai 200241China

Sulfated zero-valent iron(SZVI)has shown promising applications in wastewater ***,the rapid decline in the reactivity of SZVI with time limits its real *** mediate this problem,partial aging was proposed to improve the reactive durability of *** Cr(VI)as the target contaminant,we found that the aged ZVI(AZVI)gradually lost reactivity as aging time increased from 0.5 to 2 ***-intuitively,the partially aged SZVI(ASZVI)showed greater reactivity than SZVI when exposed to oxygenated water for a period ranging from 0.5 to 14 *** addition,the ASZVI with 0.5 d of aging time(ASZVI-0.5)not only maintained reactivity in successive runs but also increased the Cr(VI)removal capacity from 9.1 mg/g by SZVI to 19.1 mg/g by *** analysis further revealed that the electron transfer from the Fe0 core to the shell was mediated by the conductive FeS and FeS2 in the subshell of ***,the lepidocrocite and magnetite on the surface of ASZVI facilitated Cr(VI)adsorption and subsequent electron transfer for Cr(VI)***,the iron(hydr)oxide shell could retain the conductive FeS and FeS2 in the subshell,allowing ASZVI to reduce Cr(VI)efficiently and *** general,partial aging can enhance the reactive durability of ZVI when coupled with sulfidation and this synergistic effect will be beneficial to the application of SZVI-based technology for wastewater treatment.

关键词： Zerovalent iron Sulfidation Partial aging Interface reconstruction Electron transfer

Distribution and bioavailability of mercury in size-fractioned atmospheric particles around an ultra-low emission power plant in Southwest China

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Journal of Environmental Sciences 2024年第4期138卷 141-152页

作者： Wei zhang Jinjuan Li Hao Qiu Xingqiang Guo Zhijun Fei Yi Xing Deliang Yin College of Resources and Environmental Engineering Guizhou UniversityGuiyang 550025China College of Resources and Environmental Engineering Guizhou Institute of TechnologyGuiyang 550003China Key Laboratory of Karst Georesources and Environment(Guizhou University) Ministry of EducationGuiyang 550025China School of Energy and Environmental Engineering University of Science&Technology BeijingBeijing 100083China

Ultra-low emission(ULE)technology retrofits significantly impact the particulate-bound mercury(Hg)emissions from coal-fired power plants(CFPPs);however,the distribution and bioavailability of Hg in size-fractioned particulate matter(PM)around the ULE-retrofitted CF-PPs are less ***,total Hg and its chemical speciation in TSP(total suspended particles),PM_(10)(aerodynamic particle diameter≤10μm)and PM_(2.5)(aerodynamic particle diameter≤2.5μm)around a ULE-retrofitted CFPP in Guizhou Province were *** PM_(2.5)concentration was higher around this ULE-retrofitted CFPP than that in the intra-regional urban cities,and it had higher mass Hg concentration than other sizefractioned *** Hg concentrations in PM had multifarious sources including CFPP,vehicle exhaust and biomass combustion,while they were significantly higher in autumn and winter than those in other seasons(P40%).Mass concentrations of exchangeable,HCl-soluble,elemental,and residual Hg in PM_(2.5)were higher than those in other size-fractioned PM,and were markedly elevated in autumn and winter(P<0.05).In PM_(2.5),HCl-soluble Hg presented a significantly positive relationship with elemental Hg(P<0.05),while residual Hg showed the significantly positive relationships with HCl-soluble Hg and elemental Hg(P<0.01).Overall,these results suggested that atmospheric PM-bound Hg around the ULE-retrofitted CFPP tends to accumulate in finer PM,and has higher bioavailable fractions,while has potential transformation between chemical speciation.

关键词： Size-fractioned particles Mercury Chemical speciation Coal-fired power plant Ultra-low emission

Mechanism of acupuncture for limb spasm of post-stroke spasticity based on GABA and BDNF/Trkb-KCC2 signaling pathway

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Traditional Medicine Research 2024年第7期9卷 42-48页

作者： Qiong-Shuai zhang Yi Li Yu zhang Yu-Feng Wang Bai-Lin Song Department of Rehabilitation The First Affiliated Hospital of Zhengzhou UniversityZhengzhou 450000China. Graduate School Changchun University of Chinese MedicineChangchun 130000China. College of Acupuncture-Moxibustion and Tuina Changchun University of Chinese MedicineChangchun 130117China.

Background:To investigate the effects of acupuncture on post-stroke limb spasm model rats and the underlying ***:A total of 50 Sprague-Dawley rats were randomly divided into three groups,Control group(10),Model group(20)and Zhishen Tiaoxing(ZSTX)acupuncture group(20).Middle cerebral artery occlusion was conducted in SD rats to establish post-stroke limb spasm rats,which were treated with ZSTX *** assays were determined by the Narrow ally test,the limb muscle tension was detected by the BL-420S test system,and infarct volume was assessed after the cerebral infarction by 2,3,5-triphenyltetrazolium chloride *** neurotransmitterγ-aminobutyric acid(GABA)and its receptors GABAA and GABAB in the cerebral cortex of the infarct area were determined by immunofluorescence *** release of Trkb and K-Cl cotransporter isoform 2 was detected by an immunofluorescence double labeling *** Blot was utilized to measure the expression of BDNF and ***:The results showed that the behavioral assays in post-stroke limb spasm rats were significantly improved by the treatment of ZSTX acupuncture.14 days of ZSTX acupuncture can effectively inhibit muscle tone and decrease Infarct volume,which was measured with BL-420S biological function experiment system and triphenyltetrazolium ***,the results of Double-Label Immunofluorescence Assays showed that ZSTX acupuncture improved the expression of GABA,GABAA,GABAB,BDNF,and K-Cl cotransporter isoform ***-Label Immunofluorescence Assays and WB results showed that 14 days ZSTX acupuncture declined the expression of ***:Our results suggest that 14 days of ZSTX acupuncture can significantly improve post-stroke limb ***,the pathogenesis of post-stroke limb spasm and the efficacy of ZSTX acupuncture involve metabolic pathways of neurotransmitters,and electro-acupuncture can treat post-stroke limb spasm by regulating BDNF/Trkb-KCC2 signal

关键词： acupuncture scalp acupuncture limb spasm of post-stroke

A statistical analysis of the Kappa-type energy spectrum distribution of radiation belt electrons observed by Van Allen Probes

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Earth and Planetary Physics 2024年第2期8卷 368-374页

作者： LuHuai Jiao Xin Ma YuanNong zhang TaiFeng Jin Song Fu BinBin Ni Department of Space Physics School of Electronic InformationWuhan UniversityWuhan 430072China

The energy spectrum of energetic electrons is a key factor representing the dynamic variations of Earth’s Van Allen radiation *** measurements have indicated that the commonly used Maxwellian and Kappa distributions are inadequate for capturing the realistic spectral distributions of radiation belt *** we adopt the Kappa-type(KT)distribution as the fitting function and perform a statistical analysis to investigate the radiation belt electron flux spectra observed by the Van Allen *** calculating the optimal values of the key KT distribution parameters(i.e.,κandθ2)from the observed spectral shapes,we fit the radiation belt electron fluxes at different L-shells under different geomagnetic *** this manner,we obtain typical values of the KT distribution parameters,which are statistically feasible for modeling the radiation belt electron flux profiles during either geomagnetically quiet or active periods.A comparison of the KT distribution model results with those using the Maxwellian or Kappa distribution reveals the advantage of the KT distribution for studying the overall properties of the radiation belt electron spectral distribution,which has important implications for deepening the current understanding of the radiation belt electron dynamics under evolving geomagnetic conditions.

关键词： radiation belt electron Kappa-type distribution fitting geomagnetic storm

星载合成孔径雷达构像方程及其应用于轨道精化的研究

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遥感学报 2007年第6期11卷 771-777页

作者：张永红张继贤刘明军林宗坚中国测绘科学研究院北京100039

星载合成孔径雷达构像方程是地理编码、立体测量、影像定位等几何处理的基础。本文首先讨论了构像方程的参数选择,在充分考虑轨道物理模型及摄动力影响的基础上,提出了一套改进的轨道模型参数。从距离方程及多普勒方程出发,详细推导了... 详细信息

星载合成孔径雷达构像方程是地理编码、立体测量、影像定位等几何处理的基础。本文首先讨论了构像方程的参数选择,在充分考虑轨道物理模型及摄动力影响的基础上,提出了一套改进的轨道模型参数。从距离方程及多普勒方程出发,详细推导了包含轨道模型参数及成像处理参数的星载SAR构像方程。作为构像方程的一个具体应用,本文研究了星载SAR影像的轨道精化问题。将构像方程线性化,对每个地面控制点列出误差方程,可以用类似于航空影像的空间后方交会的方式精确求解轨道模型参数。试验中从1∶5万地形图上量取了5个地面控制点,对一景Radarsat SAR影像进行了轨道精化。比较发现,头文件提供的轨道与精化的轨道之间有约2km的位置差异,用精化的轨道数据得到了高精度的几何校正结果。它间接地表明了轨道精化算法的正确可行。

关键词：星载合成孔径雷达构像方程轨道模型参数轨道精化

Particle size dependence of the microsegregation and microstructure in the atomized Ni-based superalloy powders:Theoretical and experimental study

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Journal of Materials Science & Technology 2024年第4期171卷 54-65页

作者： Jikang Li Mingsheng Yang Yunfei Cai Yuanyuan zhang Qingshuai Feng Jiantao Liu Tong Liu Key Laboratory of Aerospace Materials and Performance(Ministry of Education)School of Materials Science and Engineering Beihang UniversityBeijing 100191China Central Iron and Steel Research Institute Beijing 100081China

The microstructure and microsegregation of atomized powder,which depend on their sizes,are of great importance to the mechanical properties of the consolidated bulk ***,it is necessary to reveal the relationship between particle size and powder *** effects of particle size on the so-lidification characterization of the atomized Ni-based superalloy powders were studied via finite element *** on the simulations,a model was developed to predict the microsegregation and mi-crostructure of atomized powders with different sizes and study the influence of thermal history on the powder attributes during the atomization *** radiation heat transfer and temperature gradi-ent within the rapid solidification alloy powders were taken into account in this *** validating the accuracy of the model,the predictions of the present model were compared with the microsegregation and microstructure of the specific size powder close to the screen mesh *** results showed that mi-crostructure depended primarily on the temperature gradient within the powder,while the solidification rate had a more significant effect on the *** model predicted microstructure features in agreement with the experiment,and for microsegregation,the deviations of prediction for most ele-ments were less than 10%.This work provides a new model to precisely predict the microsegregation and microstructure of the atomized alloy powders and sets a foundation to control the powder features for various engineering applications.

关键词： Particle size Solidification microstructure Microsegregation Numerical simulation

Supersonic expansion and condensation characteristics of hydrogen gas under different temperature conditions

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Chinese Journal of Chemical Engineering 2024年第5期69卷 220-226页

作者： Xinyue Duan Zeyu zhang Ziyuan Zhao Yang Liu Liang Gong Xuewen Cao Jiang Bian College of New Energy China University of Petroleum(East China)Qingdao 266580China College of Pipeline and Civil Engineering China University of Petroleum(East China)Qingdao 266580China

This paper introduced supersonic expansion liquefaction technology into the field of hydrogen *** mathematical model for supersonic condensation of hydrogen gas in a Laval nozzle model was *** supersonic expansion and condensation characteristics of hydrogen gas under different temperature conditions were *** simulation results show that the droplet number rises rapidly from 0 at the nozzle throat as the inlet temperature increases,and the maximum droplet number generated is 1.339×10^(18)kg^(-1)at inlet temperature of 36.0 *** hydrogen nucleation occurs,the droplet radius increases significantly and shows a positive correlation with the increase in the inlet temperature,and the maximum droplet radii are 6.667×10^(-8)m,1.043×10^(-7)m,and 1.099×10^(-7)m when the inlet temperature is 36.0 K,36.5 K,and 37.0 K,*** maximum nucleation rate decreases with increasing inlet temperature,and the nucleation region of the Laval nozzle becomes *** liquefaction efficiency can be effectively improved by lowering the inlet *** is because a lower inlet temperature provides more subcooling,which allows the hydrogen to reach the thermodynamic conditions required for large-scale condensation more quickly.

关键词： Hydrogen Liquefaction Supersonic Condensation Laval nozzle Computational fluid dynamics

Tube Model Predictive Control Based Cyber-attack-resilient Optimal Voltage Control Strategy in Wind Farms

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CSEE Journal of Power and Energy Systems 2024年第2期10卷 530-538页

作者： Zhenming Li Minghao Wang Yunfeng Yan Donglian Qi Zhao Xu Jianliang zhang Zezhou Wang College of Electrical Electronic Engineering Zhejiang UniversityHangzhou 310058China Department of Electrical Engineering The Hong Kong Polytechnic UniversityKowloonHong KongChina Haiyan power supply company of State Grid Zhejiang Electric Power Co. LtdHangzhouChina

Optimal voltage controls have been widely applied in wind farms to maintain voltage stability of power *** order to achieve optimal voltage operation,authentic grid information is widely needed in the sensing and actuating ***,this may induce system vulnerable to malicious *** this end,a tube model predictive control-based cyber-attack-resilient optimal voltage control method is proposed to achieve voltage stability against malicious *** proposed method consists of two cascaded model predictive controllers(MPC),which outperform other peer control methods in effective alleviation of adverse effects from cyber-attacks on actuators and sensors of the ***,efficiency of the proposed method is evaluated in sensor and actuator cyber-attack cases based on a modified IEEE 14 buses system and IEEE 118 buses *** Terms-Attack-resilient control,optimal voltage control,tube-based model predictive control,wind farm-connected power system.

关键词： Attack-resilient control optimal voltage control tube-based model predictive control wind farm-connected power system