对数伽玛分布尺度参数的Bayes估计在LINEX与复合LINEX损失函数下的比较

在LINEX损失函数与复合LINEX损失函数下,研究对数伽玛分布尺度参数θ的Bayes估计、E-Bayes估计和多层Bayes估计.给出先验分布为伽玛分布和Jeffreys先验分布时的Bayes估计,进而给出先验分布为伽玛分布时的E-Bayes估计和多层贝叶斯估计.通过数据模拟检验参数的Bayes估计和E-Bayes估计的合理性及优良性,并且发现一些数据表中存在一定的规律.     

Experimental optimum design and luminescence properties of NaY(Gd)(MoO_4)_2:Er~(3+)phosphors

Three-factor orthogonal design(OD) of Er~(3+)/Gd~(3+)/T(calcination temperature) is used to optimize the luminescent intensity of Na Y(Gd)(MoO_4)_2:Er~(3+)phosphor.Firstly,the uniform design(UD) is introduced to explore the doping concentration range of Er~(3+)/Gd~(3+).Then OD and range analysis are performed based on the results of UD to obtain the primary and secondary sequence and the best combination of Er~(3+),Gd~(3+),and T within the experimental range.The optimum sample is prepared by the high temperature solid state method.Photoluminescence excitation and emission spectra of the optimum sample are detected.The intense green emissions(530 nm and 550 nm) are observed which originate from Er~(3+)~2H_(11/2)→~4I_(15/2)and~4S_(3/2)→~4I_(15/2),respectively.Thermal effect is investigated in the optimum NaY(Gd~(3+))(MoO_4)_2:Er~(3+)phosphors,and the green emission intensity decreases as temperature increases.     

弱势群体在公共资源中的协调和一致分配

本文研究了社会弱势群体在公共资源中的分配问题.利用限制对策定义和线性代数方法,获得了一般化的图限制合作对策下的α-协调值(α-Coordination value)和α一致值(α-Consensus value).最后,通过对河流水资源分配问题的求解,推广了协调值和一致值在实际问题中较Myerson值的优越性.     

初中生符号意识形成策略探微

怀特海在《数学原理》一书中曾经说过:由于大量的数学符号,往往数学被认为是一门难懂而又神秘的科学.不能认为这些术语和符号的引入,增加了这些理论的难度.相反地,这些术语和符号的引入,往往是为了理论的易于表达和解决问题.特别是在数学中,只要细加分析,即可发现符号化给数学理论的表述和论证带来极大的方便,甚至是必不可少的.由此可见数学符号语言是学生学习数学必须经历的一门语言,随着2011版数学     

Gd2(MoO4)3:Tb3+荧光粉的固相合成与光谱性质

以MoO3、Gd2O3及Tb4O7为原料,以NH4HF2为助溶剂,在碳粉还原条件下制备了不同Tb3+掺杂浓度的Gd2( MoO4)荧光粉样品.采用X射线衍射(XRD)对样品的晶体结构进行了表征,发现掺杂浓度的改变未对产物的晶体结构产生影响,产物均为单一正交相Gd2( MoO4)3.对样品的激发、发射光谱及荧光衰减特性进...     

超短脉冲谐波截止频率与载波相位关系的研究

采用Lewenstein模型计算了两个不同脉宽的超短脉冲高次谐波截止频率与包络载波相位的关系, 结果显示,其截止频率随载波包络相位的增加先减小后增加。随着脉冲宽度的减小,高次谐波截止频率变化的幅度增加。我们按准经典的三步模型解释所得结果,并讨论了量子辐射效应。     

一类带自相容源的sine-Gordon方程新的显式精确解

文章研究了一类带自相容源的sine-Gordon方程(SGESCSs),利用广义双Darboux变换法,得到了该方程的complexiton解,进一步丰富了这类方程的解. 关键词： sine-Gordon方程 自相容源 广义双Darboux变换 complexiton解     

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介绍了HL-2A装置NBI系统的多极会切场桶式离子源灯丝电阻特性的实验结果,运用一维数值模型对灯丝稳态温度分布进行了数值计算.在不起弧时,计算了不同灯丝加热电流下的灯丝温度分布和对应的灯丝电阻.在起弧时,通过灯丝表面的等离子体鞘层近似,计算了灯丝电源输出电流为120A时不同弧流下的灯丝温度分布及灯丝电阻,给出了钨灯丝熔化对应的极限弧放电电流.最后,分析讨论了计算结果与实验测量结果的偏差.     

组合优化设计制备Y^(3+)/Dy^(3+)共掺Bi_2ZnB_2O_7新型荧光粉的发光性质EI北大核心CSCD

为获得Bi2ZnB2O7:Y3+/Dy3+新型荧光粉材料的最强黄光发光强度,运用均匀设计和二次通用旋转组合设计相结合法对Y3+/Dy3+最佳离子掺杂浓度进行优化研究,得到Y3+和Dy3+离子的最佳掺杂浓度分别为4.498mol%和6.001mol%.采用高温固相法合成最优样品,对样品结构进行表征,测定其激发光谱和发射光谱对Dy3+离子在Bi2ZnB2O7基质中的发光性质,研究发现:样品在452nm激发下,发射光谱主要由(460~500nm)蓝光发射、(550~610nm)黄光发射、(650~700nm)红光发射组成,分别对应于Dy3+的4F9/2→6H15/2、4F9/2→6H13/2及4F9/2→6H11/2跃迁;Bi2ZnB2O7基质为Dy3+提供了非中心对称的晶格格位;最优样品中Dy3+的荧光寿命为0.427ms,与相同浓度Dy3+单掺杂样品相比较可知引入Y3+在一定程度上提高了发光强度.     

On the fluorescence enhancement mechanism of Er3+ in germanate glass containing silver particles

The spectral properties of trivalent erbium ions(Er3+) are systematically studied in a melt-quenched germanate glass(60 GeO2-20PbO-10BaO-10K2O-0.1Ag2O) containing silver(Ag) particles.Thermal treatment of the material leads to the precipitation of Ag particles as observed by transmission electron microscopy and confirmed by absorption spectrum for the obvious surface plasmon resonance peak of Ag particles.The fluorescence from Er3+ in the 10-min-annealed sample with Ag particles is found to be 4.2 times enhanced compared with the unannealed sample excited by 488-nm Ar+ laser.A comparison is made between a spectral study performed on the unannealed Er3+-doped sample and the one annealed for 20 min.The data of absorption cross section and Judd-Ofelt intensity parameters show the agreement between the two samples no matter whether there are Ag particles,indicating that the introduction of Ag particles by post-heat treatment has no effect on the crystal field environment of Er3+ ions.The fluorescence enhancement is attributed to the surface plasmon oscillations of Ag particles in germanate glass.