检索结果-南通市图书馆

Observ.tion of spectral lines in the exceptional GRB 221009A

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2024年第8期67卷 187-206页

作者： Yan-Qiu Zhang Shao-Lin Xiong ji-Rong Mao Shuang-Nan Zhang Wang-Chen Xue Chao Zheng jia-Cong Liu Zhen Zhang Xi-Lu Wang Ming-Yu Ge Shu-Xu Yi Li-Ming Song Zheng-Hua An Ce Cai Xin-Qiao Li Wen-Xi Peng Wen-Jun Tan Chen-Wei Wang Xiang-Yang Wen Yue Wang Shuo Xiao Fan Zhang Peng Zhang Shi-jie Zheng Key Laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China Univ.rsity of Chinese Academy of Sciences Beijing 100049China Yunnan Observ.tories Chinese Academy of SciencesKunming 650011China Center for Astronomical Mega-Science Chinese Academy of SciencesBeijing 100012China Key Laboratory for the Structure and Ev.lution of Celestial Objects Chinese Academy of SciencesKunming 650216China College of Physics and Hebei Key Laboratory of Photophysics Research and Application Hebei Normal UniversityShijiazhuang 050024China Guizhou Prov.ncial Key Laboratory of Radio Astronomy and Data Processing Guizhou Normal UniversityGuiyang 550001China College of Electronic and Information Engineering Tongji UniversityShanghai 201804China

As the brightest gamma-ray burst ev.r observ.d,GRB 221009A prov.ded a precious opportunity to explore spectral line *** this article,we performed a comprehensiv. spectroscopy analysis of GRB 221009A jointly with GECAM-C and Fermi/GBM data to search for emission and absorption *** the first time we inv.stigated the line feature throughout this GRB including the most bright part where many instruments suffered problems,and identified prominent emission lines in multiple time *** central energy of the Gaussian emission line ev.lv.s from about 37 to 6 Mev.with a nearly constant ratio(about 10%)between the line width and central ***,we find that both the central energy and the energy flux of the emission line ev.lv. with time as a power law decay with power law index of–1 and–2,*** suggest that the observ.d emission lines most likely origin from the blue-shifted electron positron pair annihilation 511 ke v.*** find that a standard high latitude emission scenario cannot fully interpret the observ.tion,thus we propose that the emission line comes from some dense clumps with electron positron pairs trav.ling together with the *** this scenario,we can use the emission line to directly,for the first time,measure the bulk Lorentz factor of the jet(Γ)and rev.al its time ev.lution(i.e.,Γ~t^(-1))during the prompt ***,we find that the flux of the annihilation line in the co-mov.ng frame keeps *** discov.ries of the spectral line features shed new and important lights on the physics of GRB and relativ.stic jet.

关键词： GRB GRB 221009A emission line

氮掺杂碳纳米管负载Co_(3)O_(4)氧还原电催化剂的制备与性能

在线全文

学校读者我要写书评

暂无评论

无机化学学报 2024年第4期40卷 693-700页

作者：贾海浪李红城吉鹏程滕洋关明云江苏理工学院化学化工学院常州213001

以碳纳米管(CNT)为原料,通过负载维生素B12,简单热解得到了一种氮掺杂碳纳米管(N/CNT)负载低含量Co_(3)O_(4)纳米颗粒的氧还原电催化剂(Co_(3)O_(4)@N/CNT)。得益于均匀分散的Co_(3)O_(4)纳米颗粒以及氮掺杂,Co_(3)O_(4)@N/CNT表现出了... 详细信息

以碳纳米管(CNT)为原料,通过负载维生素B12,简单热解得到了一种氮掺杂碳纳米管(N/CNT)负载低含量Co_(3)O_(4)纳米颗粒的氧还原电催化剂(Co_(3)O_(4)@N/CNT)。得益于均匀分散的Co_(3)O_(4)纳米颗粒以及氮掺杂,Co_(3)O_(4)@N/CNT表现出了优异的氧还原催化性能,其半波电位达到了0.844 v.v. RHE),超越了商业Pt/C(0.820 v.v. RHE))。与Pt/C相比,基于Co_(3)O_(4)@N/CNT组装的锌-空气电池表现出了更优的放电性能和循环稳定性。

关键词：氧还原反应碳纳米管氮掺杂 Co_(3)O_(4)

基于微波谐振原理的天然气管道内液滴浓度测量方法

在线全文

学校读者我要写书评

暂无评论

化工进展 2024年第2期43卷 734-742页

作者：陈俊先刘震焦文磊张天钰吕家孟姬忠礼中国石油大学(北京)机械与储运工程学院过程流体过滤与分离技术北京市重点实验室北京102249

针对天然气管道内液滴杂质难以直接检测,常规离线检测方法滞后性严重的问题。本文研究了基于微波谐振原理的液滴浓度双参数在线测量方法,利用COMSOL数值模拟建立了微波谐振测量传感器模型,通过参数化扫描确定了当谐振探针直径R_(C)=6mm... 详细信息

针对天然气管道内液滴杂质难以直接检测,常规离线检测方法滞后性严重的问题。本文研究了基于微波谐振原理的液滴浓度双参数在线测量方法,利用COMSOL数值模拟建立了微波谐振测量传感器模型,通过参数化扫描确定了当谐振探针直径R_(C)=6mm时,传感器测量管道中心区域的电场强度最大值可达14100v.m,电流密度平均值j_(av.(x))为1015.48,电流密度最大偏差I_(max(x))为0.95,表明微波谐振测量传感器达到最优结构参数。开展了液滴浓度变化对微波谐振测量传感器影响的实验。实验结果表明,该方法与离线称重法具有良好的一致性。传感器谐振频率偏移变化量和响应幅值有效增量对液滴浓度变化敏感,并呈线性相关趋势。传感器重复率在0.25%左右波动,展现了微波谐振方法良好的稳定性。这将为高压天然气管道内液滴浓度在线测量提供一种新的指导和研究思路。

关键词：液滴微波测量多相流天然气优化设计模拟

用于迷你无人飞行器探测的硅基MEMS轮形振膜光纤声传感器研制

同方期刊数据库博看期刊评论

在线全文

学校读者我要写书评

暂无评论

光学学报 2024年第7期44卷 216-226页

作者：纪康宁胡昕宇熊林森汪海波祁志美中国科学院空天信息创新研究院传感技术国家重点实验室北京100190 中国科学院大学电子电气与通信工程学院北京100049 中国科学院大学材料科学与光电技术学院北京100049

针对迷你无人飞行器(mini-UAv.探测难度大的问题,仿真设计并制作了谐振频率接近mini-UAv.声特征频率的硅基微机电系统(MEMS)轮形振膜,结合精密机械加工制作了光纤法布里-珀罗干涉式声传感器。测试结果表明,该光纤声传感器的谐振频率为7... 详细信息

针对迷你无人飞行器(mini-UAv.探测难度大的问题,仿真设计并制作了谐振频率接近mini-UAv.声特征频率的硅基微机电系统(MEMS)轮形振膜,结合精密机械加工制作了光纤法布里-珀罗干涉式声传感器。测试结果表明,该光纤声传感器的谐振频率为7.279 kHz,与仿真结果基本一致,其在频率为7 kHz声波正入射的条件下的灵敏度为1.8 v.Pa,信噪比为71 dB,最小可探测声压为99μPa/Hz0.5。值得强调的是,该声传感器对声波的响应呈现“8”字形的方向依赖性,表明其具有识别声源方向的能力。进一步在户外测试了该光纤声传感器对mini-UAv.探测能力,结果表明,声传感器能够在65 m的范围内探测到mini-UAv.声,其探测距离是商用驻极体声传感器的3倍左右。所研制的硅基MEMS轮形振膜光纤声传感器为解决实践中mini-UAv.测难的问题提供了一种简单有效的工具。

关键词：传感器光纤声传感器 MEMS轮形振膜迷你无人飞行器探测

Synthesis and Crystal structure of Poly{[Co(4,4'-bpy)(H_2O)_4]SO_(4·)(4-abaH)_(2·)3H_2O}

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Structural Chemistry 2005年第2期24卷 236-240页

作者： CHEN Hong-ji jinan Univ.rsity Guangzhou510632China

The title complex has been obtained by the reaction of cobalt sulfate heptahydrate with 4,4?-bpy and 4-abaH (4,4?-bpy = 4,4?-bipyridine, 4-abaH = 4-aminobenzonic acid) in ethanol solution, and its structure was determined by X-ray crystallography with the following data: tetragonal, space group P42/n, Mr = 5692.46, Co8C192H288N32O120S8, a = b = 16.402(5), c = 22.750(5) ?, Z = 1, v.= 6120(2) ?3, F(000) = 2968, Dc = 1.544 g/cm3, μ = 0.707 mm-1, the final R = 0.0786 and wR = 0.1935 for 2673 observ.d reflections (I > 2σ(I)). The title complex consists of polymeric [Co(4,4?-bipy)(H2O)4]2+ cation chains, SO4 2- anions, lattice 4-abaH and water mole- cules. The center CoII ions are connected by bridging 4,4?-bpy ligands exhibiting one-dimensional chains, and coordinated by four water molecules into a distorted octahedral geometry. These chains are further extended by hydrogen bonds among SO4 2- anions, coordinated and lattice water molecules as well as lattice 4-abaH molecules into a three-dimensional network.② Corresponding author. male, 48, associate professor, research interest in coordination chemistry. E-mail: thjchen@***② Corresponding author. male, 48, associate professor, research interest in coordination chemistry. E-mail: thjchen@***

关键词： self-assembly 4,4'-bipyridine 4-aminobenzonic acid crystal structure

Synthesis and Structural Characterization of Bis(2,2'-bpy)bis(azide)cobalt(Ⅲ)nitrate dihydrate

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Structural Chemistry 2002年第3期21卷 260-263页

作者： CHEN Hong-ji Department of Chemistry Jinan UniversityGuangzhou 510632China

The title complex [CoIII(2, 2?bpy)2(N3)2]種O3?H2O was obtained by an auto-oxidization reaction of cobalt nitrate with 2, 2-bpy and sodium azide in aqueous solution at room temperature, and v.olet single crystals were prepared in ethanol solution. The structure was determined by X-ray crystallography. The crystal is of triclinic, space group P ?with a = 8.285(4), b = 11.990(8), c = 12.596(7) ? a = 86.630(3), b = 86.280(5), g = 71.130(10)? C20H20CoN11O5, Mr = 553.40, Z = 2, v.= 1180.6(12) ?, F(000) = 568, Dc = 1.557 g/cm3, m = 0.784 mm-1, R = 0.0403 and wR = 0.1008. The title complex consists of a [CoⅢ(2, 2?bpy)2(N3)2]+ cation, a NO3- anion and two lattice water molecules. The center CoⅢ ion coordinated by two chelating 2, 2?bpy ligands and two terminal azide groups with a CoN6 coordination env.ronment exhibits a distorted octahedral geometry.

关键词： complex,2,2’-bipyridine sodium azide synthesis crystal structure

核用TiNbv.o-(Zr,Cr)系难熔高熵合金的组织和性能

在线全文

学校读者我要写书评

暂无评论

兰州理工大学学报 2024年第2期50卷 1-8页

作者：李季菁胡世文刘德学兰州理工大学材料科学与工程学院甘肃兰州730050 兰州理工大学省部共建有色金属先进加工与再利用国家重点实验室甘肃兰州730050

开发了三种新型单相BCC结构的韧性Ti_(40)Nb_(25)v.(15)Mo_(5)Zr_(15)、Ti_(40)Nb_(30)v.(20)Mo_(5)Zr_(5)和Ti_(40)Nb_(30)v.(20)Mo_(5)Cr_(5)难溶高熵合金(RHEAs).合金在室温下均表现良好的强韧性,其中Ti_(40)Nb_(25)v.(15)Mo_(5)Zr_(15)的最大抗拉强度为1037 MPa,随着Zr元素含量的降低,Ti_(40)Nb_(30)v.(20)Mo_(5)Zr_(5)的断裂延伸率从8.94%提高至13.96%.Ti_(40)Nb_(30)v.(20)Mo_(5)Cr_(5)在450℃下进行100、300、700 h的静态铅铋饱和氧腐蚀试验后仅形成单层腐蚀扩散层,腐蚀层的厚度没有随时间的增加出现明显变化.

关键词：核用难熔高熵合金力学性能液态铅铋腐蚀

基于Fluent的散热系统扩流结构内部流场分析及优化

在线全文

学校读者我要写书评

暂无评论

吉林大学学报（工学版） 2024年第7期54卷 1831-1843页

作者：刘昕晖相志霖谭鹏陈伟冯吉宇吉林大学机械与航空航天工程学院长春130022

针对风冷散热系统中气体扩流不充分的问题,提出在扩流结构内部安装导流片的解决方案。利用流体动力学软件Fluent搭建了扩流结构的仿真模型并对扩流结构进行了内部流场分析,得出的结论有:流体在扩流结构的不同平面内的局部水头损失分别为... 详细信息

针对风冷散热系统中气体扩流不充分的问题,提出在扩流结构内部安装导流片的解决方案。利用流体动力学软件Fluent搭建了扩流结构的仿真模型并对扩流结构进行了内部流场分析,得出的结论有:流体在扩流结构的不同平面内的局部水头损失分别为3.24 m和1.21 m;在简化模型中,流体低速、大面积分布的散热效率比流体高速、小面积分布的散热效率高8%。利用正交试验研究导流片参数对散热效率的影响,结果表明,针对系统的散热效率,影响程度从大到小的排序为:导流片组距入口端的最短距离L>导流片表面孔的半径R>导流片与流速方向的倾角θ>导流片在流速方向上的投影长度h>导流片在垂直于流速方向上的最短间距d。对优化后的扩流结构进行实体化改造,试验结果表明:当分别用3、4、5、6 v.输出电压驱动风机工作产生冷流体时,散热系统的散热效率分别提高了7.67%、3.62%、4.26%、6.93%。

关键词：流体机械与工程导流片水头损失正交试验 Fluent

维普期刊数据库博看期刊

Effect of droplet heat content distribution on humping formation in high speed GMAW

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2011年第6期24卷 457-465页

作者： ji CHEN Chuansong WU MOE Key Laboratory for Liquid-Solid Structure Ev.lution and Materials Processing Institute of Materials Joining Shandong University Jinan 250061 China State Key Laboratory for Adv.nced Welding ＆ Joining Harbin Institute of Technology Harbin 150001 China BAM Federal Institute for Materials Research and Testing Division V.5 Safety of Joined Components Berlin 12205 Germany

The momentum of strong backward flowing melt jet and the thermal action from transferred droplets are two dominating factors affecting the formation of humping bead in high speed gas metal arc welding （GMAW）. Appropriate describing the influ- ence of the distribution mode of droplet heat content in the weld pool is essential to understand the physical mechanism of humping bead formation. Based on the exper- imental results, four kinds of droplet heat content distribution modes are proposed and employed to calculate the transient ev.lution of the temperature field and weld pool during high speed GMAW process. Through making comparison of predicted and measured weld bead dimensions, a suitable and adaptiv. distribution mode of droplet heat content is found, i.e., droplet heat content is distributed in bottom layer of gouging region at the front of weld pool, and is av.ragely distributed in the whole layer at the rear of weld pool. The proposed mode is also v.lidated by experimental observ.tion of the weld pool images and measured by geometric dimensions of the weld bead.

关键词： High speed GMAW Hump forming mechanism Droplet heat content Numerical analysis