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Joint Beamforming for Intelligent Reflecting Surface Aided Wireless Communication Using Statistical CSI

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China Communications 2020年第8期17卷 147-157页

作者： jian Dang Zaichen Zhang Liang wu National Mobile Communications Research Laboratory Southeast UniversityNanjing 210096China Purple Mountain Laboratories Nanjing 211111China

A joint beamforming algorithm is proposed for intelligent reflecting surface(IRS) aided wireless multiple-input multiple-output(MIMO) communication using statistical channel state information(CSI). The beamforming is done by alternatively optimizing the IRS reflecting coefficients and the covariance matrix of the transmit symbol vector, such that the ergodic rate of the system is maximized. The algorithm utilizes only the second order momentum of the random channel matrices and does assume any specific channel distribution, leading to a general framework for ergodic rate evaluation. A practical channel correlation model is configured to validate the performance gain. It is found that the rate can be enlarged by the joint optimization algorithm, however, the gain over that of randomly deployed reflecting coefficients depends highly on the relative correlation distance of the IRS elements and the spatial position of the IRS. In particular, the results suggest that IRS should be placed in the vicinity of either the transmitter or the receiver. Placing IRS far away from those positions is non-beneficial.

关键词： MIMO beamforming statistical CSI intelligent reflecting surface(IRS) ergodic rate

Anabolic-androgenic steroids and cardiovascular risk

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Chinese Medical Journal 2019年第18期132卷 2229-2236页

作者： jian-Di Liu Yan-Qing wu Department of Cardiology The Second Affiliated Hospital of Nanchang University Nanchang Jiangxi 330006 China

Objective:Anabolic-androgenic steroids (AAS) represents a group of synthetic testosterone derivatives that play an important role in clinical *** drugs are widely abused among the general public to increase lean weight and improve athletic *** has been reported that AAS use can produce many adverse effects,especially the occurrence of cardiovascular *** there are many related studies,there has been no consensus on AAS use and cardiovascular *** present study was to review the effect of AAS on the cardiovascular *** sources:The data in this review were obtained from articles included in PubMed and the National Center for Biotechnology Information *** selection:Original articles,case reports,and systematic reviews about AAS were selected for the ***:The use/abuse of AAS is correlated with higher cardiovascular risks,and many AAS users/abusers had cardiovascular ***,there are many confounding factors in the studies that explored the causality between AAS intake and disease development,and additional studies are required to determine AAS ***:AAS produces toxic effects on the cardiovascular system,and it is necessary to ensure that more people know this about AAS,including medical personnel.

关键词： Anabolic-androgenic steroid Cardiovascular risk Toxicity effects

Synthesis and Crystal Structure of 2-(4’-Methylphenoxy)-5,8,9-trimethyl-3-phenyl Thieno[3′,2′:5,6]pyrido[4,3-d]pyrimidin-4-(3H)-one Hydrochloride

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Chinese Journal of Structural Chemistry 2006年第5期25卷 577-581页

作者： LIU jian-Chao HE Hong-wu DING Ming-wu College of Chemistry Central China Normal University Wuhan 430079 China

The title compound 2-（4＇-methylphenoxy）-5,8,9-trimethyl-3-phenyl thieno[3＇,2＇：5,6] pyrido[4,3-d]pyrimidin-4（3H）-one hydrochloride （C26H23Cl4N3O2S, Mr = 583.33） has been determined by single-crystal X-ray diffraction. The crystal belongs to monoclinic, space group P21/c with a = 14.8442（ 11 ）, b = 11.5131 （8）, c = 17.2010（13） A, β = 113.7250（10）°, V = 2691.3（3） ,A^3, Z = 4, Dc = 1.440 g/cm^3, S = 1.094,μ = 0.547 mm^-1, F（000） = 1200, the final R = 0.0571 and wR = 0.1458. X-ray analysis reveals that the title compound combines with a molecule of dichloromethane by an intramolecular hydrogen bond. The thienopyridine ring is almost coplanar, and the dihedral angle between the thiophene plane and the pyridine plane is 0.6°.

关键词： thieno[3',2':5,6]pyrido[4,3-d]pyrimidin-4(3H)-one,triphenylphosphine iminophosphorane crystal structure

基于最优控制理论的国产光抽运小铯钟频率控制算法

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物理学报 2024年第6期73卷 108-118页

作者：宋会杰董绍武王翔姜萌章宇郭栋张继海中国科学院国家授时中心时间频率基准实验室西安710600 时间基准及应用重点实验室(中国科学院) 西安710600 中国科学院大学天文与空间科学学院北京100049 西安工程大学电子信息学院西安710048 西安科技大学机械工程学院西安710054

原子钟频率控制是时间保持工作中的关键技术.当前守时工作中的频率控制主要针对国外微波钟采用开环控制算法,但由于国产光抽运小铯钟(下称国产钟)的工作原理和性能不同于国外同类型原子钟,因此该算法不能很好适应国产钟.为了提升我国标... 详细信息

原子钟频率控制是时间保持工作中的关键技术.当前守时工作中的频率控制主要针对国外微波钟采用开环控制算法,但由于国产光抽运小铯钟(下称国产钟)的工作原理和性能不同于国外同类型原子钟,因此该算法不能很好适应国产钟.为了提升我国标准时间的自主性和安全性,本文基于国产钟的噪声特性,在最优控制理论的框架下研究了线性二次高斯控制算法,该算法属于闭环控制算法,从同步时间、频率控制准确度和频率控制稳定度方面研究国产钟性能,最后分析了不同控制间隔对国产钟性能的影响.结果表明随着二次损失函数中约束矩阵W_(R)的增大,同步时间延长,控制准确度降低,控制短期稳定度提高.W_(R)相同情况下,随着控制间隔的增大,同步时间延长,控制准确度降低,控制短期稳定度提高,对于W_(R)=1时,控制间隔为1 h的同步时间为5小时,控制准确度为1.83 ns,1 h的Allan偏差为1.81×10^(-13);控制间隔为8 h的同步时间为28 h,控制准确度为4.48 ns,1 h的Allan偏差为1.48×10^(-13).控制国产光抽运小铯钟的中长期稳定度都得到提高.

关键词：原子钟状态模型线性二次高斯控制 Kalman滤波原子钟噪声

数字经济与城乡收入差距:基于创新要素流动视角

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经济问题 2024年第7期 57-64页

作者：周玉兰贺建风陈能军华南理工大学经济与金融学院广东广州510006 南方科技大学广东深圳518055

缩小城乡收入差距是我国实现共同富裕的重要内容。近年来,随着数字经济的不断发展,数字经济对城乡收入差距的影响已成为各界关注的热点。因此,基于2005—2021年的面板数据,采用固定效应模型探究数字经济对城乡收入差距的直接影响,并基... 详细信息

缩小城乡收入差距是我国实现共同富裕的重要内容。近年来,随着数字经济的不断发展,数字经济对城乡收入差距的影响已成为各界关注的热点。因此,基于2005—2021年的面板数据,采用固定效应模型探究数字经济对城乡收入差距的直接影响,并基于创新要素流动视角,探究数字经济对城乡收入差距的间接影响。研究表明,数字经济发展使得城乡收入差距呈现先扩大后缩小的倒“U”型,且存在地区和年份异质性。同时,数字经济会通过创新人力要素流动提升缩小城乡收入差距的阈值效应,使倒“U”型拐点右移,也会通过创新资本要素流动削弱城乡收入差距倒“U”型前半段的正向效应和后半段的负向效应,并使拐点向左移。因此,各地区应依据地区特色和优势,制定数字经济发展差异化策略;通过加大对农村企业的研发经费补贴等措施完善R&D资本市场;通过制定向农村地区倾斜的创新人才政策等措施加速R&D人才向农村流动。

关键词：数字经济城乡收入差距创新要素流动

基于UNet++卷积神经网络的重力异常三维密度反演

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地球物理学报 2024年第2期67卷 752-767页

作者：李柏森鲁宝亮安国强巨鹏朱武苏子旺长安大学地质工程与测绘学院西安710054 海洋油气勘探国家工程研究中心北京100028 长安大学西部矿产资源与地质工程教育部重点实验室西安710054 自然资源部生态地质与灾害防控重点实验室西安710054

三维密度反演是地球物理领域的研究热点,而在大数据及人工智能发展的时代背景下如何快速高效地实现重力数据反演显得更为重要.传统反演方法通常需要存储大型系数矩阵,内存占用大,耗费时间长,同时为约束反演结果而加入的正则化约束项参... 详细信息

三维密度反演是地球物理领域的研究热点,而在大数据及人工智能发展的时代背景下如何快速高效地实现重力数据反演显得更为重要.传统反演方法通常需要存储大型系数矩阵,内存占用大,耗费时间长,同时为约束反演结果而加入的正则化约束项参数难以确定;深度学习可以不依赖先验信息,也不需要计算及存储系数矩阵,使得计算效率大大提高.基于此,本文提出了一种基于UNet++网络的重力异常反演方法.首先将UNet++网络中部分参数进行更改:选择在输入数据绝对值较大时梯度更稳定的LeakyReLU作为激活函数;加入了Batch Normalization层,增强了网络的收敛速度及稳定性.然后为了提高网络的全局最优化能力,引入了基于余弦退火的学习率更新策略,使用梯度的一阶以及二阶矩估计的Adam最优化算法,利用数据集与标签集进行网络训练,实现了重力异常的三维密度反演.通过实验验证了UNet++、LeakyReLU更快速稳定的收敛能力,而余弦退火学习率更新策略具有更强的全局寻优能力.含噪模型实验及实际数据反演结果进一步证明该方法的正确性和有效性,及其良好的泛化能力与抗噪能力.

关键词：密度反演重力异常 UNet++ 余弦退火深度学习

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冰冻地球的进动与章动

大学物理 2024年第1期43卷 51-56页

作者：刘文亮欧建文刘益民庄妮亚李义浩龙光波韶关学院智能工程学院广东韶关512005

基于贾尼别科夫效应网上流传的一些观点认为,当地球南北两极的海冰增加或者减少将导致地球重量分布不平衡,地球将会发生翻转.本文基于简单的刚体地球模型,首先计算了地球南北纬度结冰时导致的地球总转动惯量变化,并利用欧拉动力学方程... 详细信息

基于贾尼别科夫效应网上流传的一些观点认为,当地球南北两极的海冰增加或者减少将导致地球重量分布不平衡,地球将会发生翻转.本文基于简单的刚体地球模型,首先计算了地球南北纬度结冰时导致的地球总转动惯量变化,并利用欧拉动力学方程分析转动惯量变化引起的地球的进动与章动.研究指出,不论是不受外力作用的潘索情况还是考虑了潮汐力的情况,地球在南北纬度30°结冰的情况下旋转最不稳定.此外,即使地球表面冰冻到深度33公里,贾尼别科夫效应也不会在地球上发生.通过本文简单的计算终结了网络流言,并且有利于人们对地球进动和章动的理解.

关键词：贾尼别科夫效应转动惯量欧拉动力学方程进动章动

Mechanism of Mg2+ dissolution from olivine and serpentine: Implication for bioleaching of high-magnesium nickel sulfide ore at elevated pH

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International Journal of Minerals,Metallurgy and Materials 2019年第9期26卷 1069-1079页

作者： jian-zhi Sun jian-kang Wen Bo-wei Chen Biao wu National Engineering Laboratory of Biohydrometallurgy GRINM Group Corporation Limited

To inhibit the dissolution of Mg^2+ during the bioleaching process of high-magnesium nickel sulfide ore, the effect of major bioleaching factors on the dissolution of Mg^2+ from olivine and serpentine was investigated and kinetics studies were carried out. The results indicated that the dissolution rate-controlling steps are chemical reaction for olivine and internal diffusion for serpentine. The most influential factor on the dissolution of Mg^2+ from olivine and serpentine was temperature, followed by p H and particle size. A novel method of bioleaching at elevated pH was used in the bioleaching of Jinchuan ore. The results showed that elevated pH could significantly reduce the dissolution of Mg^2+ and acid consumption along with slightly influencing the leaching efficiencies of nickel and cobalt. A model was used to explain the leaching behaviors of high-magnesium nickel sulfide ore in different bioleaching systems. The model suggested that olivine will be depleted eventually, whereas serpentine will remain because of the difference in the rate-controlling steps. Bioleaching at elevated pH is a suitable method for treating high-magnesium nickel sulfide ores.

关键词： olivine serpentine high-magnesium nickel sulfide ore bioleaching shrinking core model elevated pH

Porous heterostructure of graphene/hexagonal boron nitride as an efficient electrocatalyst for hydrogen peroxide generation

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Carbon Energy 2023年第5期5卷 138-151页

作者： Mengmeng Fan Zeming Wang Yuying Zhao Qixin Yuan jian Cui Jithu Raj Kang Sun Ao Wang Jingjie wu Hao Sun Bei Li Liang Wang jianchun jiang jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources International Innovation Center for Forest Chemicals and MaterialsCollege of Chemical EngineeringNanjing Forestry UniversityNanjingChina Key Lab of Biomass Energy and Material Jiangsu ProvinceJiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest ResourcesInstitute of Chemical Industry of Forest ProductsChinese Academy of ForestryNanjingChina School of Environmental and Chemical Engineering Institute of Nanochemistry and NanobiologyShanghai UniversityShanghaiChina Chemicobiology and Functional Materials Institute Nanjing University of Science and TechnologyNanjingChina Department of Chemical and Environmental Engineering University of CincinnatiCincinnatiOhioUSA

Compared with the traditional heteroatom doping,employing heterostructure is a new modulating approach for carbon-based ***,a facile ball milling-assisted route is proposed to synthesize porous carbon materials composed of abundant graphene/hexagonal boron nitride(G/h-BN)*** Ni powder and nanoscale h-BN sheets are used as a catalytic substrate/hard template and“nucleation seed”for the formation of the heterostructure,***-prepared G/h-BN heterostructures exhibit enhanced electrocatalytic activity toward H_(2)O_(2) generation with 86%-95%selectivity at the range of 0.45-0.75 V versus reversible hydrogen electrode(RHE)and a positive onset potential of 0.79 versus RHE(defined at a ring current density of 0.3 mA cm^(-2))in the alkaline *** a flow cell,G/h-BN heterostructured electrocatalyst has a H_(2)O_(2) production rate of up to 762 mmol g_(catalyst)^(-1) h^(-1) and Faradaic efficiency of over 75%during 12 h testing,superior to the reported carbon-based *** density functional theory simulation suggests that the B atoms at the interface of the G/h-BN heterostructure are the key active *** research provides a new route to activate carbon catalysts toward highly active and selective O_(2)-to-H_(2)O_(2) conversion.

关键词： efficient electrocatalyst graphene H_(2)O_(2)generation hexagonal boron nitride porous heterostructure