Analysis of total nitrogen and total phosphorus in soil using laser-induced breakdown spectroscopy

Laser-induced breakdown spectroscopy(LIBS) is used to determine the total nitrogen(TN) and total phosphorus(TP) in soil.Quantitative determinations are conducted using the line intensity of the analyte element and element concentration.Calibration models are obtained using ten samples for TN and seven samples for TP.The rest samples are used to validate the results.Strong linear correlations are obtained from the determined TN and TP concentrations.LIBS is a powerful tool for analyzing soil samples to determine nutrient elements by selecting calibration and validation samples with similar matrix composition.     

汽车生产中大功率激光器的应用研究

介绍在国内首次将国产HJ-3千瓦横流CO_2激光器应用于汽车发动机生产过程中,试验总结出的该器件在实际生产中的运行规律,提出了解决器件的实用性、可靠性的     

SGSNPOOL技术方案研究

SGSNPOOL是3GPP组织提出的一种组网方案,有着诸多优点。本文从实际应用出发,着重分析了SGSNPOOL的关键技术及组网方案,以期为SGSNPOOL的部署提供参考。     

氧离子导体La1.9Y0.1Mo2O9细晶粒陶瓷的制备和电学性质研究

采用溶胶凝胶法合成的La_1.9Y_0.1Mo₂O₉纳米晶粉体, 结合微波烧结技术制备出不同晶粒度的La_1.9Y_0.1Mo₂O₉块体样品. 利用X射线衍射仪(XRD)、高分辨透射显微镜(HRTEM)、场扫描显微镜(SEM)对粉体及陶瓷块体的物相、 形貌进行了表征, 利用交流阻抗谱仪测试了样品不同温度下的电导率. 实验结果表明, 掺Y的La_1.9Y_0.1Mo₂O₉能将高温立方β 相稳定到室温; 块体样品致密均匀, 平均晶粒度范围在60 nm–4 μm之间; 致密度高的样品表现出高的电导率, 其中900 ℃烧结样品的电导率600 ℃时高达0.026 S/cm, 比固相反应法制备的La_1.9Y_0.1Mo₂O₉样品高出约1倍. 总结认为样品的致密性对电导率影响较大, 是通过影响晶界电导率来影响总电导率的, 样品的晶粒度(在60 nm–4 μm范围内)对电导率的影响还不能确定. 关键词： 氧离子导体 1.9Y_0.1Mo₂O₉')" href="#">La_1.9Y_0.1Mo₂O₉ 细晶粒陶瓷 微波烧结     

WLAN认证方案研究

近年来,数据业务高速增长,WLAN网络建设也日益被电信运营商所重视.而传统的WLAN认证方案,每次登陆均需要输入用户名和密码,这给用户带来了诸多不便.为了提升用户体验,业界相继提出了多种解决方案.文章从WLAN认证原理入手,并结合不同的终端类型,对各种WLAN认证方案进行了分析和比较,以期对WLAN网络的下一步建设提供参考.     

Correlation of Lithium Ionic Diffusion with Nb Concentration in Li7-xLa3Zr2-xNbxO12 Evaluated by an Internal Friction Method

Solid lithium-ion conductors Li7-xLa3Zr2-xNbxO12（x =0.25, 0.5, 1, 1.5） with cubic garnet structure are suc- cessfully prepared by a solid state reaction method, and the effects of Nb concentration on lithium ion diffusion are investigated by means of internal friction （IF） technique. A prominent relaxation-type IF peak （actually composed of two components） is observed in each Nb doped LiTLa3Zr2012 compound： with apeak PL at lower temperature and a peak PH at higher temperature. The mechanisms of the two components are suggested to be associated with two diffusion processes of lithium ions via vacancies： 48g ←→ 48g and 489 ←→ 24d. The relaxational strength of the IF peak gradually decreases, which is accompanied by the activation energy increasing from 0.45 eV to 0.64 eV with the increasing Nb doping level. The corresponding mechanism is ascribed to originate from lattice contraction as well as the lower concentration of diffusion ions induced by the substitution of Zr4＋ by Nb5＋.     

EPC引入初期分组域核心网组网方式浅析

随着EPS标准的不断完善与LTE规模试验范围的进一步扩大,分组域核心网向EPC架构的演进势在必行。本文通过分析EPC系统架构,比较了其与GPRS系统的不同,对国内运营商引入EPC初期的核心网组网方式提出了建议。     

改进型四脊波导正交模转换器的设计与测量

为满足上海65m射电望远镜C波段接收机需求,在传统四脊波导OMT(Orthomode Transducer)基础上设计了一种小尺寸、高性能的宽带四脊波导正交模转换器。介绍了该OMT的结构和工作原理,讨论了设计要点,给出了有限元法(FEM)和时域有限积分法(FIT)的仿真结果,分析了OMT的容差性能,最后实际加工了实验样机。实验结果表明,改进型四脊波导OMT具有尺寸小、频带宽、高性能的特点,能够满足射电天文制冷接收机需求。     

Phase Transition and Oxygen Ion Diffusion in (La1-xLnx)2Mo2O9 (Ln=Nd, Gd, x=0.05-0.25) Using Dielectric Relaxation Method

采用介电弛豫方法研究了氧离子导体(La1-xRex)2Mo2O9(Re=Nd, Gd, x=0.05-0.25)中氧离子扩散和相变行为. 观察到了两个介电损耗峰：第一个峰Pd在600 K附近,第二个峰Ph在720 K左右.Pd峰为弛豫型介电损耗峰,是由氧离子的短程扩散导致的. 随着频率增加,Ph峰基本上不随频率移动,但是峰高随着频率显著的下降.Ph峰表现出非弛豫型的本质,对应于氧离子和氧空位的分布从静态无序到动态无序的转变过程. 随着掺杂浓度的增加,Pd峰和Ph峰的峰高先是增加,在15%的掺杂量达到最高后开始降低. 与此对应,电导率也在此掺杂浓度下出现最大值.