基于LTCC技术射频传输线的设计

本文介绍了射频传输线及LTCC技术的概念和特点,建立了基于LTCC技术的射频传输线模型,推导了传输线模型特征参数提取公式;并对传输线模型进行三维电磁仿真,得到了仿真参数。通过分析传输线性能,提出了优化设计的一定方法     

Fabrication of (Ca + Yb)- and (Ca + Sr)-stabilized α-SiAlON by combustion synthesis

In this paper, (Ca + Yb)- and (Ca + Sr)-stabilized α-SiAlON powders were fabricated by combustion synthesis. The influence of Ca²⁺ incorporation on the phase composition and grain morphology of combustion products was discussed. The experimental results showed that with the incorporation of Ca²⁺ well-developed rod-like (Ca + Yb) α-SiAlON crystals could be produced. It was also found that, when only Sr²⁺ was used as stabilizing cation, the reaction product was (α + β)-SiAlON composite, in which β-SiAlON was the predominant phase and the relative content of α-SiAlON was low. With the incorporation of Ca²⁺, however, both the relative content and the lattice parameters of α-SiAlON were clearly increased. These results indicated that the incorporation of Ca²⁺ could assist Sr²⁺ into the α-SiAlON lattice structure.     

A novel green emitting phosphor Ca2GeO4:Tb3+

A novel green emitting phosphor, Tb³⁺-doped Ca₂GeO₄ was prepared for the first time by a solid-state reaction. The phosphor showed prominent luminescence in green due to the magnetic dipole transition of ⁵D₄ → ⁷F₅. Structural characterization of the luminescent material was carried out with X-ray powder diffraction (XRD) analysis and field emission scanning electron microscopy (FE-SEM). Luminescence properties were analyzed by measuring the excitation and photoluminescence spectra. Photoluminescence measurements indicated that the phosphor exhibited bright green emission at about 541 and 550 nm under UV excitation. In addition, Al³⁺ or Li⁺ co-doping enhances the green emission from Ca₂GeO₄:Tb³⁺ by about 18 and 4 times, respectively, under UV excitation. The excellent luminescence properties make it a possible candidate for flat panel display application.     

Lithium solubility limit in ZnGa2O4:Bi0.0013+,Li+ phosphor

The lithium solubility limit, photoluminescence (PL) and photoluminescence excitation (PLE) properties of lithium ion co-activated ZnGa₂O₄:Bi³⁺,Li⁺ phosphor have been investigated. A LiGaO₂ second phase began to appear from 3 mol% Li⁺ ion co-activated ZnGa₂O₄:Bi³⁺,Li⁺ phosphor. The enhanced brightness of blue (λ_ex = 254 nm) and white (λ_ex = 315 nm) colors of bismuth ions doped ZnGa₂O₄:Bi³⁺,Li⁺ phosphor was assigned to the formation of LiGaO₂. Bi³⁺ activated lithium zinc gallate phosphor showed a more enhanced PLE peak around 315 nm than that of lithium zinc gallate phosphor when λ_em = 520 nm. Thus, we observed that the PL intensity of ZnGa₂O₄:Bi³⁺,Li⁺ phosphor with λ_em = 520 nm was much greater than that of ZnGa₂O₄:Li⁺ phosphor. Also, ZnGa₂O₄:Bi³⁺,Li⁺ phosphor exhibited a shorter decay time than that of ZnGa₂O₄:Li⁺ phosphor by about a factor of about 2.     

企业资产管理系统中通信模型的研究与实现

为了改善企业资产管理(EAM)系统在用户体验、模块间数据传输效率及耦合度等方面的不足,构建了基于Sil-verlight与WCF技术研究与实现EAM系统中的通信模型。利用Silverlight构建客户端提升了用户体验;使用WCF服务封装业务逻辑。客户端Silverlight应用程序通过代理调用WCF服务,提高了数据传输效率,降低了系统模块间的耦合性。     

数字信号处理的时频分析方法综述

现代数字信号处理方法众多,时频分析在此领域应用广泛并仍然具有发展潜力。介绍了数字信号处理的时频分析方法的发展,从短时傅里叶变换,到Wigner-Ville分布,小波变换,希尔伯特-黄变换,EEMD,分别论述了5种方法的原理以及优缺点。     

基于语义的智能信息处理技术的研究

智能信息处理是模拟人或者自然界其他生物处理各种信息的行为,是当前信息处理技术向多样化、集成化与智能化方向的发展,具有很高的理论研究和应用价值.经过多年的研究和探索,智能信息处理技术已经取得较大的发展,但在实际应用中还存在许多问题需要解决和完善.分析了基于概念图的语义研究在智能信息处理中的应用,并设计与实现了一个基于概念图的智能答疑系统CGQAS,通过实验结果验证了基于概念图的智能信息处理的可行性和有效性.     

Application of hydrophobic and magnetic plastic particles for enhanced flotation recovery

The effect of hydrophobic and magnetic plastic particles having a contact angle of around 83° on flotation performance was evaluated using coal particles of varying degrees of floatability. The magnetic plastic material were recovered by a low intensity magnetic separator and recycled back to the flotation feed for re-use. Flotation rate tests conducted on coal using a conventional cell proved that combustible recovery and flotation rate were significantly enhanced with the addition of the plastic particles, especially for difficult-to-float coals, which was corroborated by flotation column tests. Carrying capacity and particle size-by-size flotation tests further showed that the magnetic plastic particles preferentially increased the recovery of coarse particles by as much as 35 absolute percentage points due to froth stabilization which reduced the selective detachment of coarse and/or weakly hydrophobic particles. The enhanced flotation recovery was attributed to the influence on liquid drainage rate in the froth zone, froth stability, bubble coalescence and flotation rates.     

Enhanced luminescence of CaSb2O6:Bi3+ blue phosphors by efficient charge compensation

This paper reported an enhanced photoluminescence of CaSb₂O₆:Bi³⁺ by efficient charge compensation. Charge compensated CaSb₂O₆:Bi³⁺,M⁺ (M=Li, Na and K) phosphors were prepared using a co-precipitation technique followed by heat-treatment. The structure and morphology of the as-prepared CaSb₂O₆:Bi³⁺,M⁺ samples were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The results revealed that the obtained CaSb₂O₆:Bi³⁺,M⁺ samples are hexagonal crystal structure and this structure was retained regardless of co-doping by Li⁺, Na⁺ or K⁺. All samples showed sphere-like shape with particle size of 40–80 nm. The optical properties of products were studied by UV–vis diffuse reflectivity, photoluminescence spectra and luminescence decay measurements. Under the excitation of 336 nm light, all of the samples exhibited a strong blue emission peaking around 437 nm, which is attributed to the ³P₁–¹S₀ transition of the Bi³⁺ ion. It was found that the charge compensation has significant effect on the photoluminescence properties of CaSb₂O₆:Bi³⁺ and the best luminescence properties have been achieved for CaSb₂O₆:0.75Bi³⁺,0.75 Na⁺. The mechanism for the enhancement of the blue emission has also been studied in detail. Our results suggested that the optical properties of oxide nanostructures can be tailored through co-doping with aliovalent ions and the favorable luminescence properties of CaSb₂O₆:Bi³⁺,Na⁺ make it potential for lighting and display applications.     

基于复杂网络理论的宝鸡公交网络构建与分析

选取陕西省宝鸡市的43条公交线路和344个公交站点,以公交站点作为节点,相邻站点之间存在公交线路作为连边,基于复杂网络理论构建了宝鸡公交网络模型。对网络的统计性质与拓扑特征分析表明,公交网络是稀疏的,具有无标度特性以及部分小世界性质,网络度分布服从幂律分布,少数枢纽节点在网络中起重要的作用,对应于城市的关键站点或主要换乘站点。公交网络同时存在鲁棒性与脆弱性,网络稳定性的研究可为城市公交网络的优化及交通规划提供一定的理论依据。