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991.
针对极区经线迅速收敛于极点造成的传统惯导机械编排在极区不适用问题,提出了CGCS2000地球椭球体模型下基于横向地球坐标的惯性导航方法。在构建横向坐标系及伪经纬网的基础上,给出了横向惯导与传统惯导间导航参数的转换关系,推导了横向地理坐标系机械编排,建立了系统误差模型,并以某型船舶为例,通过系统性能的静基座、动基座仿真分析,研究了基于横向地球坐标的惯性导航方法在极区的适用性。仿真分析表明,基于横向地球坐标的惯性导航方法可以克服传统惯导在极区存在的问题,在极点处不存在计算溢出,并可为载体穿越极点时提供高精度的姿态、位置信息,适用于极区。 相似文献
992.
上世纪80年代以后进行的1∶20万水系沉积物扫面,个别元素分析质量不稳定,达不到设计要求,如镉、钴、铜、镧.利用大型分析仪器为手段,建立了稀有、稀散、稀土和铂族元素的测试方法,分析数据符合地球化学填图的要求,为地质找矿工作新的突破做出贡献. 相似文献
993.
《Ultrasonics sonochemistry》2014,21(6):1994-2009
Degradation of five textile dyes, namely Reactive Red 141 (RR 141), Reactive Blue 21 (RB 21), Acid Red 114 (AR 114), Acid Blue 113 (AB 113) and Basic Violet 16 (BV 16) in aqueous solution has been carried out with ultrasound (US) and in combination with rare earth ions (La3+ and Pr3+). Kinetic analysis of the data showed a pseudo-first order degradation reaction for all the dyes. The rate constant (k), half life (t1/2) and the process efficiency (φ) for various processes in degradation of dyes under different experimental conditions have been calculated. The influence of concentrations of dyes (16–40 mg/L), pH (5, 7 and 9) and rare earth ion concentration (4, 12 and 20 mg/L) on the degradation of dyes have also been studied. The degradation percentage increased with increasing rare earth amount and decreased with increasing concentration of dyes. Both horn and bath type sonicators were used at 20 kHz and 250 W for degradation. The sonochemical degradation rate of dyes in the presence of rare earths was related to the type of chromophoric groups in the dye molecule. Degradation sequence of dyes was further examined through LCMS and Raman spectroscopic techniques, which confirmed the sonochemical degradation of dyes to non-toxic end products. 相似文献
994.
In contrast with B0-ˉB0, Bs-ˉBs mixing where the standard model(SM) contributions overwhelm that of the new physics beyond standard model(BSM), a measured relatively large D0-ˉD0mixing where the SM contribution is negligible, definitely implies the existence of the new physics BSM. It is natural to consider that the rare decays of D meson might be more sensitive to new physics, and the decay mode D0→μ+μ-could be an ideal area to search for new physics because it is a flavor changing process. In this work we look for a trace of the new physics BSM in the leptonic decays of D0. Concretely we discuss the contributions of unparticle or an extra gauge boson Z while imposing the constraints set by fitting the D0-ˉD0mixing data. We find that the long-distance SM effects for D0→lˉl still exceed those contributions of the BSM under consideration, but for a double-flavor changing process such as D0→μ±e, the new physics contribution would be significant. 相似文献
995.
用熔融急冷法制备了系列不同Er3+离子掺杂浓度的Ge-Ga-S-KBr硫卤玻璃,测试了样品折射率、吸收光谱、中红外荧光光谱。通过吸收光谱计算了Er3+离子吸收谱线的振子强度,应用Judd-Ofelt理论计算分析了Er3+离子在Ge-Ga-S-KBr硫卤玻璃中的强度参数Ωi ( i = 2 , 4 , 6) 、自发辐射跃迁几率A、荧光分支比?和辐射寿命?rad等光谱参数。研究了808nm激光泵浦下样品中红外荧光特性与掺杂浓度之间变化关系,并用Futchbauer-Ladenburg公式分别计算了2.8?m处的受激发射截面。结果表明,在808nm 激光泵浦下观察到了2.8?m中红外荧光,分别对应于Er3+: 4I11/2?4I13/2跃迁,当Er3+离子掺杂浓度从0.4wt%增加到1.0wt%时,中红外荧光强度都随相应增加,计算的Er3+:4I11/2?4I13/2跃迁多声子驰豫速率分别为37 s-1。 相似文献
996.
Clustering of rare-earth dopants in GeAs sulfide glasses was studied by fluorescence spectroscopy of Pr-doped glasses and by EPR measurements of Gd-doped samples. The linewidth of the g 2 resonance of Gd3+, as well as the relative intensity of emission from the 1D2 level of Pr3+, was used as a relative measure of rare-earth clustering. Rare earths were found to have low solubility in uncodoped GeAs sulfide glasses, which also displayed poor fluorescence efficiency due to severe clustering. Codoping such glasses with Ga greatly enhanced rare-earth solubility and dispersal, particularly for Ga:rare earth ratios ≥ 10:1, as evidenced by the narrower EPR resonances and more intense luminescence of Gd- and Pr-doped glasses, respectively. In, P and Sn were also observed to ‘decluster’ rare earths, although less efficiently than Ga, whereas codoping with I was found to have no effect on clustering. These phenomena are explained by a structural model in which (1) rare-earth dopants and codopants are spatially associated and (2) rare-earth dispersal is accomplished by a statistical distribution of codopants in tetrahedral network sites. 相似文献
997.
Microwave absorption properties regulation and bandwidth formula of oriented Y2Fe17N3-δ@SiO2/PU composite synthesized by reduction-diffusion method 下载免费PDF全文
As concepts closely related to microwave absorption properties, impedance matching and phase matching were rarely combined with material parameters to regulate properties and explore related mechanisms. In this work, reduction-diffusion method was innovatively applied to synthesize rare earth alloy Y$_{2}$Fe$_{17}$. In order to regulate the electromagnetic parameters of absorbers, the Y$_{2}$Fe$_{17}$N$_{3-\delta }$ particles were coated with silica (Y$_{2}$Fe$_{17}$N$_{3-\delta }$@SiO$_{2}$) and absorbers with different volume fractions were prepared. The relationship between impedance matching, matching thickness, and the strongest reflection loss peak (${\rm RL}_{\rm min}$) was presented obviously. Compared to the microwave absorption properties of Y$_{2}$Fe$_{17}$N$_{3-\delta }$/PU absorber, Y$_{2}$Fe$_{17}$N$_{3-\delta }$@SiO$_{2}$/PU absorbers are more conducive to the realization of microwave absorption material standards which are thin thickness, light weight, strong absorbing intensity, and broad bandwidth. Based on microwave frequency bands, the microwave absorption properties of the absorbers were analyzed and the related parameters were listed. As an important parameter related to perfect matching, reflection factor ($\sqrt {ărepsilon_{\rm r}/\mu_{\rm r}}$) was discussed combined with microwave amplitude attenuation. According to the origin and mathematical model of bandwidth, the formula of EAB (${\rm RL}<-10$ dB) was derived and simplified. The calculated bandwidths agreed well with experimental results. 相似文献
998.
Two kinds of novel styryl chemosensory 2‐FMNC and 3‐FMNC, were designed and synthesized by an apporiate introduction of 9‐benzylidene‐9H‐fluorene group as fluorophore with the aim at avoiding photoisomerisation. These 9‐benzylidene‐9H‐fluorene derivatives showed the similar selectivity and sensitivity upon addition of metal ions. The sensitivity of FMNC to alkaline earth metal ions was Ba2+>Sr2+>Ca2+≈Mg2+. 相似文献
999.
1000.
通过溶剂热-溶液挥发法合成得到了2个基于依诺沙星(HEx)的稀土配合物[Ce(Ex)4].39H2O(1)和[Sm2(Ex)4(HEx)2(ox)].24H2O(2),并运用红外光谱、元素分析和X-射线单晶衍射等研究手段表征了它们的结构。研究结果表明:配合物1为单核配合物;配合物2为双核配合物。紫外滴定和荧光滴定研究结果表明:它们均能以插入的方式作用于小牛胸腺DNA,结合常数(Kb)分别为4.45×104和6.56×104mol-1.L;抗菌实验结果表明它们对革兰氏菌和真菌的活性均要优于依诺沙星配体本身。 相似文献