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5G的频谱利用 预览
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作者 钟旻 《数字通信世界》 2019年第9期1-2,9,共3页
在本节讲座中,介绍了5G从低频段到高频段的应用,频谱共享的概念和原理,为实现频谱共享所采用的软件定义无线电和认知无线电技术。
关键词 频谱 频谱共享 频谱管理 软件定义无线电 认知无线电
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TMAHS:a truthful multi-unit double auction framework for heterogeneous spectrum in secondary market
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作者 Li Xin Xie Gang Gao Jinchun 《中国邮电高校学报:英文版》 EI CSCD 2019年第1期82-94,共13页
Auction was widely used to tackle spectrum allocation and sharing in the secondary market under the condition of spectrum scarcity.In real communication system,such as broadband communication,the utilization of spectr... Auction was widely used to tackle spectrum allocation and sharing in the secondary market under the condition of spectrum scarcity.In real communication system,such as broadband communication,the utilization of spectrum resource is various because of different requirements and complex application scenarios.So,these schemes cannot be directly applied to the above wireless communication system.To solve this problem,a new model where sellers/buyers can sell/buy multi-unit for heterogeneous spectrum was proposed and a truthful multi-unit double auction framework was designed for heterogeneous spectrum trading.A valuation function is first applied to represent the buyer's true valuation of the sub-band and reflect the buyer's satisfaction degree and a novel concept termed'virtual player'was introduced.Then the buyer group was constructed based on the conflict graph to reuse the same spectruin among interference-free buyers in both spatial and temporal domains.The winner determination strategy and algorithm of clearing price were designed elaborately.According to the theoretical analysis,the scheme can satisfy three critical economic properties:truthfulness,individual rationality,and budget balance.Finally,simulation results show that the proposed scheme can achieve better user satisfaction,auction efficiency and spectrum reuse rate for the real communication system.The proposed auction framework is practical and effective. 展开更多
关键词 SPECTRUM AUCTION double AUCTION SPECTRUM REUSE HETEROGENEOUS SPECTRUM MULTI-UNIT VALUATION function
Optimal Energy-Efficient Transmission for Hybrid Spectrum Sharing in Cooperative Cognitive Radio Networks 预览
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作者 Linna Hu Rui Shi +3 位作者 Minghe Mao Zhiyu Chen Hongxi Zhou Weiliang Li 《中国通信:英文版》 SCIE CSCD 2019年第6期150-161,共12页
In order to improve the energy efficiency(EE)in cognitive radio(CR),this paper investigates the joint design of cooperative spectrum sensing time and the power control optimization problem for the secondary user syste... In order to improve the energy efficiency(EE)in cognitive radio(CR),this paper investigates the joint design of cooperative spectrum sensing time and the power control optimization problem for the secondary user systems to achieve the maximum energy efficiency in a cognitive network based on hybrid spectrum sharing,meanwhile considering the maximum transmit power,user quality of service(QoS)requirements,interference limitations,and primary user protection.The optimization of energy efficient sensing time and power allocation is formulated as a non-convex optimization problem.The Dinkelbach’s method is adopted to solve this problem and to transform the non-convex optimization problem in fractional form into an equivalent optimization problem in the form of subtraction.Then,an iterative power allocation algorithm is proposed to solve the optimization problem.The simulation results show the effectiveness of the proposed algorithms for energy-efficient resource allocation in the cognitive network. 展开更多
关键词 cognitive radio networks COOPERATIVE SPECTRUM SENSING ENERGY-EFFICIENCY HYBRID SPECTRUM sharing power control SENSING time optimization
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Observational constraints on running vacuum model
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作者 张进军 Chung-Chi Lee 耿朝强 《中国物理C:英文版》 SCIE CAS CSCD 2019年第2期132-137,共6页
We investigate the power spectra of the CMB temperature and matter density in the running vacuum model(RVM) with the time-dependent cosmological constant of A=3 vH2+ Λ0, where H is the Hubble parameter. In this model... We investigate the power spectra of the CMB temperature and matter density in the running vacuum model(RVM) with the time-dependent cosmological constant of A=3 vH2+ Λ0, where H is the Hubble parameter. In this model, dark energy decreases in time and decays to both matter and radiation. By using the Markov chain Monte Carlo method, we constrain the model parameter v as well as the cosmological observables. Explicitly, we obtain v ≤1.54× 10-4(68% confidence level) in the RVM with the best-fit χRVM2 =13968.8, which is slightly smaller thanχΛCDM2= 13969.8 in the ΛCDM model of v = 0. 展开更多
关键词 MATTER power SPECTRUM running VACUUM MODEL CMB temperature SPECTRUM COSMOLOGICAL constant
宝兰高铁列车运行所致桥路隧过渡段黄土场地地面振动实测与分析 预览
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作者 牛富航 严武建 +2 位作者 宿文姬 郑海忠 吴志坚 《北京交通大学学报》 CAS CSCD 北大核心 2019年第3期89-97,共9页
为研究宝兰高铁桥路隧过渡段黄土场地振动特性和放大效应,对宝兰高铁通道里程K1491+202段马营隧道、路基和桥梁桥路隧过渡段黄土场地地面进行现场振动测试,通过采用频谱分析和反应谱分析方法研究高铁列车对桥路隧过渡段临近黄土场地地... 为研究宝兰高铁桥路隧过渡段黄土场地振动特性和放大效应,对宝兰高铁通道里程K1491+202段马营隧道、路基和桥梁桥路隧过渡段黄土场地地面进行现场振动测试,通过采用频谱分析和反应谱分析方法研究高铁列车对桥路隧过渡段临近黄土场地地面振动特征、频谱特征和加速度反应谱特征.结果表明:针对桥墩点振源和路基线振源,黄土斜坡场地地面峰值加速度均比平坦黄土场地大;地面振动持续时间与列车荷载呈正相关关系,黄土斜坡场地持时比平坦黄土场地持时更长;运行列车引起的地面振动频率集中在5~50Hz之间,车速对地面水平向振动的频率有一定影响;能量谱峰值与列车运行速度及轮轴载荷均呈正相关性,振源方式对加速度能量谱有重要影响;加速度反应谱表现为单峰型,能量主要集中在中低频范围内,衰减迅速.同时,该研究结果也可为黄土场地效应提供现场实测依据. 展开更多
关键词 宝兰高铁 振动测试 黄土场地 频谱 加速度反应谱
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Selective flotation separation of andalusite and quartz and its mechanism 预览
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作者 Yan-ping Niu Chuan-yao Sun +3 位作者 Wan-zhong Yin Xing-rong Zhang Hong-feng Xu Xu Zhang 《矿物冶金与材料学报:英文版》 SCIE EI CAS CSCD 2019年第9期1059-1068,共10页
The separation of andalusite and quartz was investigated in the sodium oleate flotation system, and its mechanism was studied by solution chemical calculation, zeta-potential tests, Fourier transform infrared spectros... The separation of andalusite and quartz was investigated in the sodium oleate flotation system, and its mechanism was studied by solution chemical calculation, zeta-potential tests, Fourier transform infrared spectroscopic(FTIR), and X-ray photoelectron spectroscopic(XPS). The flotation tests results show that FeCl3·6H2O has a strong activation effect on andalusite and quartz and citric acid has a strong inhibitory effect on activated quartz, thus increasing the floatability difference between quartz and andalusite when the pulp p H is approximately 8. The FTIR, Zeta potential, and XPS analyses combined with the chemical calculation of flotation reagent solutions demonstrate that Fe forms hydroxide precipitates on the surface of andalusite and quartz and that oleate anions and metal ions adsorb onto the surface of the minerals. The elements Al and Fe can be chemically reacted. The anions in citric acid have different degrees of dissolution of Fe on the andalusite and quartz surfaces, thereby selectively eliminating the activation of the elemental Fe on andalusite and quartz and increasing the floatability of andalusite, leading to a better separation effect between andalusite and quartz. 展开更多
关键词 ANDALUSITE QUARTZ flotation MECHANISM zeta potential Fourier infrared SPECTRUM ANALYSIS X-ray PHOTOELECTRON energy SPECTRUM ANALYSIS
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A Dynamic Distributed Spectrum Allocation Mechanism Based on Game Model in Fog Radio Access Networks 预览
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作者 Yao Yu Shumei Liu +1 位作者 Zhongshi Tian Siyu Wang 《中国通信:英文版》 SCIE CSCD 2019年第3期12-21,共10页
With the explosive growth of highspeed wireless data demand and the number of mobile devices,fog radio access networks(F-RAN)with multi-layer network structure becomes a hot topic in recent research.Meanwhile,due to t... With the explosive growth of highspeed wireless data demand and the number of mobile devices,fog radio access networks(F-RAN)with multi-layer network structure becomes a hot topic in recent research.Meanwhile,due to the rapid growth of mobile communication traffic,high cost and the scarcity of wireless resources,it is especially important to develop an efficient radio resource management mechanism.In this paper,we focus on the shortcomings of resource waste,and we consider the actual situation of base station dynamic coverage and user requirements.We propose a spectrum pricing and allocation scheme based on Stackelberg game model under F-RAN framework,realizing the allocation of resource on demand.This scheme studies the double game between the users and the operators,as well as between the traditional operators and the virtual operators,maximizing the profits of the operators.At the same time,spectrum reuse technology is adopted to improve the utilization of network resource.By analyzing the simulation results,it is verified that our proposed scheme can not only avoid resource waste,but also effectively improve the operator’s revenue efficiency and overall network resource utilization. 展开更多
关键词 FOG radio access networks(F-RAN) game theory SPECTRUM REUSE technology base station DYNAMIC COVERAGE SPECTRUM PRICING and allocation
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基于Unity 3D的光谱实验教学系统研究 预览
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作者 刘钊 徐富新 《计算机技术与发展》 2019年第6期119-124,共6页
在教学中运用虚拟现实技术是当今的一个热门话题。教育正在进入网络的时代,这既是一种趋势,也是教育的未来。对实验室进行虚拟化技术的研发,通过先进的计算机技术以更好地满足对教学的需求。文中将建模软件3DMax和虚拟仿真软件Unity3D... 在教学中运用虚拟现实技术是当今的一个热门话题。教育正在进入网络的时代,这既是一种趋势,也是教育的未来。对实验室进行虚拟化技术的研发,通过先进的计算机技术以更好地满足对教学的需求。文中将建模软件3DMax和虚拟仿真软件Unity3D应用于物理实验教学,结合虚拟现实的特点,设计了光栅光谱虚拟仿真实验系统,给出了系统的整体结构和部分实现的关键技术,模拟一个真实的实验环境。该系统采用基于Bmob后端云服务器,以节约成本,提高开发效率。实验内容结合了3D和互动仿真的两大优点,界面直观、操作简单,通过对MVC登录设计、实验操作交互技术、动态光谱图技术的研究,结合实验实际需求,使得光学实验变得简单。学生能够更快掌握原理,熟悉实验操作来缩短真实实验周期,提高实验教学的效率,达到良好的实验教学效果。 展开更多
关键词 3DMax UNITY3D 虚拟仿真 物理实验 光谱
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蓝光与眼睛 预览
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作者 成知函 John Hayes(指导) 《中国眼镜科技杂志》 2019年第3期110-112,共3页
蓝光是光谱中波长为400nm~500nm的可见光。蓝光可分为短波蓝光即有害蓝光,和长波蓝光即有益蓝光。短波蓝光危害人们的视力,并导致特定疾病,而长波蓝光则有助于人们维护正常的生理功能,调节生物节律,并治疗特定疾病。目前防控蓝光的方法... 蓝光是光谱中波长为400nm~500nm的可见光。蓝光可分为短波蓝光即有害蓝光,和长波蓝光即有益蓝光。短波蓝光危害人们的视力,并导致特定疾病,而长波蓝光则有助于人们维护正常的生理功能,调节生物节律,并治疗特定疾病。目前防控蓝光的方法正在逐渐发明与完善中。 展开更多
关键词 短波蓝光 长波蓝光 光谱 视力
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Expected energy spectrum of cosmic ray protons and helium below4 PeV measured by LHAASO
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作者 尹丽巧 张寿山 +9 位作者 曹臻 毕白洋 王翀 刘佳丽 马玲玲 杨明洁 Tiina Suomijarvi 张勇 游智勇 宗子召 《中国物理C:英文版》 SCIE CAS CSCD 2019年第7期86-96,共11页
The Large High Altitude Air Shower Observatory(LHAASO) is a composite cosmic ray observatory consisting of three detector arrays: kilometer square array(KM2 A), which includes the electromagnetic detector array and mu... The Large High Altitude Air Shower Observatory(LHAASO) is a composite cosmic ray observatory consisting of three detector arrays: kilometer square array(KM2 A), which includes the electromagnetic detector array and muon detector array, water Cherenkov detector array(WCDA) and wide field-of-view Cherenkov telescope array(WFCTA). One of the main scientific objectives of LHAASO is to precisely measure the cosmic rays energy spectrum of individual components from 10^14 eV to 10^18 eV. The hybrid observation will be employed by the LHAASO experiment, in which the lateral and longitudinal distributions of extensive air shower can be observed simultaneously. Thus, many kinds of parameters can be used for primary nuclei identification. In this paper, high purity cosmic ray simulation samples of the light nuclei component are obtained using multi-variable analysis. The apertures of 1/4 LHAASO array for pure proton and mixed proton and helium(H&He) samples are 900 m^2 Sr and1800 m^2 Sr, respectively. Prospect of obtaining proton and H&He spectra from 100 TeV to 4 PeV is discussed. 展开更多
关键词 LHAASO hybrid measurement energy SPECTRUM COMPOSITION TMVA
Spectrum evolution of Rayleigh backscattering in one‐dimensional waveguide 预览
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作者 Fuhui Li Tianyi Lan +3 位作者 Ligang Huang Iroegbu Paul Ikechukwu Wuming Liu Tao Zhu 《光电进展(英文)》 2019年第8期2-8,共7页
Despite the tremendous awareness of Rayleigh scattering characteristics and its considerable research interest for numerous fields,no report has been documented on the dynamic characteristics of spectrum evolution(SpE... Despite the tremendous awareness of Rayleigh scattering characteristics and its considerable research interest for numerous fields,no report has been documented on the dynamic characteristics of spectrum evolution(SpE)and physical law for Rayleigh scattering from a micro perspective.Herein,the dynamic characteristics of the SpE of Rayleigh scattering in a one-dimensional waveguide(ODW)is investigated based on the quantum theory and a SpE-model of Rayleigh backscattering(RBS)source is established.By means of simulation,the evolution law which represents the dynamic process of the spectrum linewidth at a state of continuous scattering is revealed,which is consistent with our previous experimental observation.Moreover,an approximate theoretical prediction of the existing relationship between the spectrum linewidth of RBS source and the transmission length in ODW is proposed,which theoretically provides the feasibility of constructing functional devices suitable to ascertain laser linewidth compression.The designed experimental scheme can be implemented provided the assumptions are fulfilled.In addition,a theoretical model of the micro-cavity structure to realize the deep compression of laser linewidth is proposed. 展开更多
关键词 SCATTERING RAYLEIGH spectrum evolution LINEWIDTH functional device
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橙皮素电场作用的分子结构和红外光谱理论研究 预览
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作者 王新强 葛浩然 +4 位作者 李桂琴 叶松 汪杰君 甘永莹 王方原 《光谱学与光谱分析》 SCIE EI CAS CSCD 北大核心 2019年第8期2395-2402,共8页
橙皮素(HES)是一种二氢黄酮药物,为研究在外电场(EEF)作用下, HES的分子结构和光谱的变化,利用密度泛函理论(DFT)以及6-311G(d,p)基组,在C2—C1方向施加EEF(-0.005~0.010 a.u.)并优化HES分子的基态几何构型,研究了分子总能量、键长、红... 橙皮素(HES)是一种二氢黄酮药物,为研究在外电场(EEF)作用下, HES的分子结构和光谱的变化,利用密度泛函理论(DFT)以及6-311G(d,p)基组,在C2—C1方向施加EEF(-0.005~0.010 a.u.)并优化HES分子的基态几何构型,研究了分子总能量、键长、红外光谱(IR)、偶极矩(DM)和HOMO-LUMO能隙。在优化结构的基础上,采用含时密度泛函理论(TDDFT),探究不同EEF对紫外可见吸收光谱(UV-Vis)、激发态(ES)的影响。结果显示,无EEF时, HES分子中C1—O18和C2—C26间的单键都优化成了双键,转变为烯醇式结构,这样分子中更多的基团构成一个共轭体系,形成最稳定的结构。随着EEF的增强,分子总能量先升后降, DM则先降后增,键长的变化复杂。当正向负向EEF都增强时,由于HES分子中不同化学键的振动产生的IR吸收峰(AP),相应地出现了不同的频谱移动,各个AP的强度也有不同的变化。无EEF时, UV-Vis在223.6和262 nm处有2个AP,分别处于E 2带、 K带。 223.6 nm处的AP随着EEF的增大出现了蓝移(BS),当EEF大于0.002 5 a.u.谱峰消失;262 nm处的AP在正向EEF下出现红移(RS),吸收强度随EEF的增强呈现衰弱趋势,当EEF为0.01 a.u.时,谱峰RS至283 nm,强度达到最小值5 889.64 L·mol^-1 ·cm^-1;在负向EEF下出现BS,且吸收强度均增强,在EEF为-0.002 5 a.u.时,谱峰BS至261 nm,强度增至最大值为12 500.36 L·mol^-1 ·cm^-1 。当正向负向EEF都增强时,分子的能隙和激发态能量(EE)均呈现减小趋势,说明HES分子易被激发而处于活跃状态。在无EEF时, OS均大于零,表明能够被激发。当不断加强正向EEF时, ES的OS均先升高再降低;在负向EEF下OS有复杂的变化。分析EEF下物质的分子结构和光谱,将为探究橙皮素的药效对其进行电场解离提供理论参考。 展开更多
关键词 橙皮素(HES) 外电场(EEF) 分子结构 光谱
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Structure and Luminescence of Carboxylic Acid Samarium and Europium Complexes 预览
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作者 王丽 沈芝 +3 位作者 兰青 罗保民 杨浩 赵强 《结构化学》 SCIE CAS CSCD 2019年第7期1182-1187,共6页
Two crystals,[Sm(Hcpna)(cpna)·3 H2O]n(1) and [Eu(Hcpna)(cpna)·2 H2O]n(2),have been synthesized by solvothermal method based on Sm3+ and Eu3+ with multiple acid ligands5-(4-carboxyphenoxy)nicotinic acid(H2cpn... Two crystals,[Sm(Hcpna)(cpna)·3 H2O]n(1) and [Eu(Hcpna)(cpna)·2 H2O]n(2),have been synthesized by solvothermal method based on Sm3+ and Eu3+ with multiple acid ligands5-(4-carboxyphenoxy)nicotinic acid(H2cpna), and the new complexes have been characterized by single-crystal X-ray diffraction, elemental analysis, IR spectroscopy, thermogravimetric analysis and fluorescence analysis. Complex 1 exhibits a 1 D chain structure. It crystallizes in the triclinic system, space group P1 with a = 5.9738(11), b = 12.528(2), c = 18.021(4)?,α= 93.156(3)o,β=98.067(3)o,γ= 92.692(3)o, V = 1331.3(4) A3, Z = 2, S = 1.069, F(000)= 702, R = 0.0277 and wR =0.0688(I > 2σ(I)). Complex 2 shows a two-dimensional network structure, which crystallizes in monoclinic system, space group C2/c with a = 13.6733(19), b = 18.422(3), c = 10.4307(15) A,β=93.881(2)o, V= 2621.4(7) A3, Z = 4, S = 1.110, F(000)= 1372, R = 0.0302 and wR = 0.0811(I >2σ(I)). The solid-state fluorescent test results show tcomplex 1 has weaker fluorescence intensity than the ligand. However, complex 2 has excellent fluorescence properties, and can emit bright red light under the irradiation of ultraviolet lamp. 展开更多
关键词 crystal STRUCTURE samarium(Ⅲ) europium(Ⅲ) THERMOGRAVIMETRIC analysis fluorescence spectrum
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Carbon deposition in porous nickel/yttria-stabilized zirconia anode under methane atmosphere 预览
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作者 Zhi-yuan Chen Li-jun Wang +3 位作者 Xiao-jia Du Zai-hong Sun Fu-shen Li Kuo-Chih Chou 《矿物冶金与材料学报:英文版》 SCIE EI CAS CSCD 2019年第3期350-359,共10页
A commercial solid oxide fuel cell with a Ni/YSZ anode was characterized under a pure methane atmosphere. The amount of deposited carbon increased with an increase in temperature but decreased when the temperature exc... A commercial solid oxide fuel cell with a Ni/YSZ anode was characterized under a pure methane atmosphere. The amount of deposited carbon increased with an increase in temperature but decreased when the temperature exceeded 700℃. The reactivity of carbon decreased with increasing deposition temperature. Filamentous carbon was deposited from 400 to 600℃, whereas flake carbon was deposited at 700 and 800℃. With increasing temperature, the intensity ratio of the D band over the sum of the G and D bands was constant at the beginning and then decreased with the transformation of the carbon morphology. The crystallite size increased from 2.9 to 13 nm with increasing temperature. The results also indicated that the structure of the deposited carbon was better ordered with increasing deposition temperature. In comparison with pure Ni powders, the interaction between the YSZ substrate and Ni particles could not only modify the carbon deposition kinetics but also reduce the temperature effect on the structure and reactivity variation of carbon. 展开更多
关键词 solid oxide FUEL cell COKING RAMAN spectrum HYDROCARBON FUEL ANODE
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Influence of rooftop telecommunication tower on set back-step back building resting on different ground slopes 预览
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作者 Amit Thakur Deepankar Kumar Ashish Surender Kumar Verma 《地震工程与工程振动:英文版》 SCIE EI CSCD 2019年第2期351-362,共12页
In the hilly region due to scarcity of the plain area, buildings like set back-step back are more often used and also as a big surge in the telecommunication industries, rooftop tower adaptation is very common story n... In the hilly region due to scarcity of the plain area, buildings like set back-step back are more often used and also as a big surge in the telecommunication industries, rooftop tower adaptation is very common story nowadays. In the present study an analogy has been drawn to find out the influence of the rooftop telecommunication tower on the setback-step back building resting on ground at 20° and 30° slopes. A dynamic analysis has been performed and compared on the 4 legged angled section telecommunication tower which is located on the roof top of set back-step back building by varying positions of tower with the existing host structure built up on ground slope of 20° and 30° in both directions(X and Y). 展开更多
关键词 rooftop telecommunication tower SET back-step BACK BUILDING response spectrum analysis steel RC frame earthquake SAP2000
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移动边缘计算环境下的动态资源分配策略 预览
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作者 朱新峰 张智浩 王彦凌 《计算机工程与科学》 CSCD 北大核心 2019年第7期1184-1190,共7页
在通讯设备爆炸式增长的时代,移动边缘计算作为5G通讯技术的核心技术之一,对其进行合理的资源分配显得尤为重要。移动边缘计算的思想是把云计算中心下沉到基站部署(边缘云),使云计算中心更加靠近用户,以快速解决计算资源分配问题。但是... 在通讯设备爆炸式增长的时代,移动边缘计算作为5G通讯技术的核心技术之一,对其进行合理的资源分配显得尤为重要。移动边缘计算的思想是把云计算中心下沉到基站部署(边缘云),使云计算中心更加靠近用户,以快速解决计算资源分配问题。但是,相对于大型的云计算中心,边缘云的计算资源有限,传统的虚拟机分配方式不足以灵活应对边缘云的计算资源分配问题。为解决此问题,提出一种根据用户综合需求变化的动态计算资源和频谱分配算法(DRFAA),采用“分治”策略,并将资源模拟成“流体”资源进行分配,以寻求较大的吞吐量和较低的传输时延。实验仿真结果显示,动态计算资源和频谱分配算法可以有效地降低用户与边缘云之间的传输时延,也可以提高边缘云的吞吐量。 展开更多
关键词 移动边缘计算 分治法 资源分配 频谱 吞吐量 传输时延
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宽光谱大面积多阶梯光场光谱感光仪 预览
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作者 李超洋 黄元申 +1 位作者 盛斌 庄松林 《光电工程》 CAS CSCD 北大核心 2019年第2期65-72,共8页
研制了一种新型光谱感光仪,其特点是宽光谱(340nm~900nm),大曝光面(202mm×90.5mm),且面上具有多阶梯光强;制备具有18级光密度值的高精密阶梯光楔板,每个台阶的光密度值误差不大于0.01;根据光源的光谱特性镀制滤光膜,消除光栅二级... 研制了一种新型光谱感光仪,其特点是宽光谱(340nm~900nm),大曝光面(202mm×90.5mm),且面上具有多阶梯光强;制备具有18级光密度值的高精密阶梯光楔板,每个台阶的光密度值误差不大于0.01;根据光源的光谱特性镀制滤光膜,消除光栅二级光谱。自动控制采集系统采用LabVIEW与PLC一体机开发,水平方向采用光栅位移传感器构成闭环控制,波长定位偏差小于0.05nm;竖直方向采用线性补偿方法,高度位置偏差小于0.05mm。仪器能够自动测量光楔板上不同波长不同光强区域的单位面积光功率,用快门控制曝光时间,在宽光谱范围内对感光材料进行一次曝光。在显影定影后,用光密度计测量其光密度值,根据国标(GB10557-89)绘制出感光材料某一确定光密度值的光谱灵敏度曲线。 展开更多
关键词 光谱灵敏度 光密度 光谱 光强 阶梯光楔板
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高架桥下方高铁地震信号频谱特征研究 预览
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作者 蒋一然 鲍铁钊 +1 位作者 宁杰远 张献兵 《北京大学学报:自然科学版》 CAS CSCD 北大核心 2019年第5期829-838,共10页
使用北京大学架设的临时台阵中11个高铁高架桥下的短周期台站11天记录到的由951列高铁激发的共10461条地震记录,利用K-Means聚类算法,研究其频谱如何随列车的速度、模型、铁轨和路基变化而变化。近匀速运动的高铁所产生的高铁地震波的... 使用北京大学架设的临时台阵中11个高铁高架桥下的短周期台站11天记录到的由951列高铁激发的共10461条地震记录,利用K-Means聚类算法,研究其频谱如何随列车的速度、模型、铁轨和路基变化而变化。近匀速运动的高铁所产生的高铁地震波的频谱主要由等间隔的峰组成,其基频等于速度与车厢长度的比值。通过调整基频来降低列车速度的影响,可使频谱模式更稳定,便于比较。聚类结果表明,高铁地震的频谱在相同车型、铁轨和路基条件下,表现出稳定的模式;这种稳定的频谱模式随车型、铁轨和路基条件的变化而显著变化。对这种稳定的频谱特征的监测,可用于高速铁路的安全监控。 展开更多
关键词 高铁 震源 频谱 聚类
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NIR光谱法快速预测小麦籽粒干物质含量 预览
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作者 何鸿举 王玉玲 +5 位作者 乔红 欧行奇 刘红 王慧 蒋圣启 王魏 《海南师范大学学报:自然科学版》 CAS 2019年第1期33-38,共6页
通过采集百农201、百农207、百农307、百旱207、AK-58、冠麦1号、周麦18等7个不同品种完整小麦籽粒的近红外光谱(900~1700 nm)信息,经高斯滤波平滑(Gaussian Filtering Smoothing,GFS)、标准化校正(Normalization Correction)和卷积平滑... 通过采集百农201、百农207、百农307、百旱207、AK-58、冠麦1号、周麦18等7个不同品种完整小麦籽粒的近红外光谱(900~1700 nm)信息,经高斯滤波平滑(Gaussian Filtering Smoothing,GFS)、标准化校正(Normalization Correction)和卷积平滑(Savitzky-Golay Convolution Smoothing,SGCS)三种预处理后,利用偏最小二乘回归(Partial Least Squares Regression,PLSR)算法寻找光谱信息与小麦籽粒干物质含量之间的定量关系。结果显示,经GFS预处理的近红外光谱(100个波长)构建的全波段PLSR模型(PLSR)预测相关系数(RP)为0.952,预测误差(RMSEP)为0.158%,RMSEC与RMSEP绝对值差(ΔE)为0.082,预测效果优于其他两种预处理光谱。从GFS光谱中经PLSR-β法筛选获得17个最优波长,构建的优化模型(O-PLSR)RP为0.928,RMSEP为0.191%,ΔE为0.049,其预测效果接近于PLSR模型。试验表明,利用900~1700 nm光谱可被潜在用于快速无损预测小麦籽粒干物质含量。 展开更多
关键词 光谱 检测 小麦 干物质
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一致可逆性质与Weyl定理的判定
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作者 刘萤 曹小红 《山东大学学报:理学版》 CAS CSCD 北大核心 2019年第6期112-117,共6页
令 H 表示无限维复可分的 Hilbert 空间,B( H)为 H 上有界线性算子的全体。对算子 T∈B( H)而言,若对于任意算子S∈B( H),TS 和 ST 同时可逆或同时不可逆,则称算子 T 为一致可逆算子。本文根据算子的一致可逆性质,给出了算子 T 与其算... 令 H 表示无限维复可分的 Hilbert 空间,B( H)为 H 上有界线性算子的全体。对算子 T∈B( H)而言,若对于任意算子S∈B( H),TS 和 ST 同时可逆或同时不可逆,则称算子 T 为一致可逆算子。本文根据算子的一致可逆性质,给出了算子 T 与其算子演算满足 Weyl 定理的充要条件。 展开更多
关键词 WEYL 定理 一致可逆性质
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