滤光片型近红外仪器模型传递的研究

模型传递问题是近红外光谱分析技术中解决数据通用性的关键问题。文章以玉米籽粒近红外光谱图(检测其中水分含量)为例,考察了模型传递的问题。使用斜率截距算法,直接校正法和目标因子分析等算法,在5台滤光片型近红外仪器上实现了模型传递,并比较了各种方法的模型传递效果。研究表明,直接校正法的模型传递效果最好,4台从仪器的平均传递差异度为7.01%。文章还研究了标准样品数量对模型传递效果的影响。作为转换集的标准样品数目越多,模型传递效果越好,一般有20个标准样品就能达到稳定的效果。当转换集小于20时,直接校正法的传递效果急剧下降,而标准样品数量对斜率截距法和目标因子分析法的影响不明显。     

Bi0.8Pb0.2SrCaCuOy超导体中磁通运动引起的内耗峰

在线性增加磁场的条件下,用变频倒扭摆测量了配比成份为(Bi_0.8Pb_0.2)SrCaCu₂O_y的试样在超导态时磁化过程中的低频内耗。测量温度为95K,试样处于零电阻状态,所用频率为0.5-5Hz.在内耗-场强H曲线上观测到内耗峰,它有如下特点:1)峰高随加场速率H的增大而增大,但随测量频率的增大而降低;2)峰值处的场强为4-6mT;3)当H由非零值突然改变至零时,磁化过程特征内耗消失;4)试样处于正常态时,上述特征内耗消失。认为超导体在磁化过程中的上述特征内耗是量子磁通的运动所引起来的。 关键词：     

NaNO2晶体线性和非线性光学系数的计算

使用从头计算平面波赝势方法,计算了NaNO₂晶体电子能带结构,并使用改进的倍频公式计算了它的线性折射率和静态二级非线性系数,所得到的结果和实验值相符.采用实空间原子切割方法分析了阳离子和阴离子基团对光学性质的贡献.计算表明(NO₂)-基团对双折射率和倍频系数的贡献占主要地位,从而进一步验证了阴离子基团理论的正确性 关键词： 电子结构 非线性光学系数 从头计算方法     

Magnetic,Photoluminescent and Semiconductive Properties of a Novel 4f-5d Bromide Compound (La6HgsBr26) [4(HgBr2)l (2Br)

An unprecedented 4f-5d material(La6Hg5Br26)[4(HgBr2)](2Br)(1)was syn-thesized by hydrothermal reactions and structurally characterized by single-crystal X-ray diffraction method.Complex 1 crystallizes in the Pbam space group of orthorhombic system with a=13.0980(10),b=13.6650(9),c=28.010(2)?,V=5013.4(6)?^3,Br36Hg9La6,Mr=5515.53,Z=2,Dc=3.613 g/cm^3,μ(MoKα)=29.457 mm^–1 and F(000)=4598.Compound 1 is characteristic of a two-dimensional(2D)layered structure.The photoluminescent measurements with solid-state samples reveal that compound 1 has a strong emission in the green region of light spectrum.It has remarkable CIE chromaticity coordinates of(0.2499,0.3589).A wide optical band gap of 3.41 eV is discovered by the solid-state UV/vis diffuse reflectance spectrum.The variable-temperature magnetic susceptibility obeys the Curie-Weiss law(cm=c/(T–q))with C=2.48 K and a negative Weiss constantθ=–169.07 K as revealed by the magnetic measurements,indicating the existence of an antiferromagnetic interaction in compound 1.     

NUMERICAL SIMULATION OF THREE-DIMENSIONAL INCOMPRESSIBLE FLOW BY A NEW FORMULATION

A new mathematical formulation, called the pseudovorticity–velocity formulation, of the three-dimensional incompressible Navier–Stokes equations is presented as an alternative to the vorticity–velocity approach. For the model lid-driven cavity flow problem in two and three dimensions, combined with an explicit mixed spectral /finite different numerical scheme the proposed formulation is found to be efficient and very accurate as compared with the results available in the literature. In particular, the simulation results demonstrate an attractive feature of the present formulation compared with the vorticity–velocity approach, namely that the divergence-free condition of the velocity field can always be achieved on a non-staggered mesh.     

Nonexistence of Global Solutions for a Semilinear Double-Wave Equation with Nonlinearity of Derivative Type

In this paper,we study the blow-up of solutions to a semilinear double-wave equation with nonlinearity of derivative type.By using the iteration method and the ...     

轴流式水轮机三维非定常湍流计算及压力脉动预测

水轮机的稳定性研究是目前工程上大型水轮机组流动分析的重要课题,本文以某水电站的大型轴流转桨式水轮机原型为基础建立计算模型,完成了从蜗壳进口到尾水管出口整个流道的非定常湍流计算,预测了固定导叶进口、转轮后、尾水管进口等多个位置的压力脉动,并利用FFT变换进行分析得到了压力脉动的频率和幅值,探讨了水轮机全流道内压力脉动产生和传播的原理．     

5-Br-PADAP分光光度法测定煤灰中微量铀

在pH8.2的三乙醇胺缓冲溶液中,有OP存在下,铀(Ⅵ)与2-(5-溴-2-吡啶偶氮)-5-二乙氨基苯酚(5-Br-PADAP)生成红色络合物,其最大吸收波长为535nm,表观摩尔吸光系数1.0×105L·mol-1·cm-1,在含铀0-7μg/25mL浓度范围符合比耳定律.方法灵敏度高,快速简便,用TBP萃淋树脂分离大量干扰离子,测定了煤灰中微量铀,结果令人满意.     

Sm3+掺杂稀土硼酸盐玻璃的光谱参数计算和荧光光谱分析

制备了具有高效可见荧光发射的Sm3 掺杂稀土硼酸盐(LBLB)玻璃,对玻璃的吸收和荧光光谱展开了测试与分析.根据Judd-Ofelt理论对吸收光谱进行了拟合,求得Sm3 离子的晶场调节参数Ωt=(2,4,6)分别为6.81×10-20,4.43×10-20和2.58×10-20 cm2,并进一步计算出各能级跃迁的谱线强度、自发辐射跃迁概率、辐射寿命和荧光分支比等光谱参数.紫外光激发下,Sm3 掺杂LBLB玻璃发出明亮的橙红色光.激发光谱表明,氩离子激光器是Sm3 掺杂LBLB玻璃有效的激发光源.