利用C#Web Service应用程序的开发

通过一个Windows客户端/服务器程序,对数据库Web服务的调用进行了实例介绍。     

Dielectric Relaxation of La3+-Modified Bi3TiNbO9 Aurivillius Phase Ceramics

Single Aurivillius phase Bi_{3− x} La _x TiNbO₉ (LBTN- x , x =0.00, 0.50, 0.75, and 1.00) ceramics were prepared by the conventional solid-state reaction method. When x ≤0.50, the ceramics are normal ferroelectrics, while LBTN-0.75 and LBTN-1.00 showed typical relaxor behavior, which could probably be attributed to the disordering induced by the La³⁺ partly substituting for Bi³⁺ in Bi₂O₂ layers. The dielectric relaxation of LBTN-0.75 and LBTN-1.00 were fitted using the Vögel–Fulcher relationship, and the results suggest that both of them are analogous to a spin glass with thermally activated polarization fluctuations above a freezing temperature.     

铸造镍基合金焊接液化裂纹

本文用金相、相分析、电镜,特别是扫描电镜、电子探针等手段对铸造镍基合金焊接液化裂纹、焊接热影响区晶界经受焊接高温过程的变化进行了综合研究。提出了某些铸造镍基合金液化裂纹产生的机理:①在焊接高温下,沿晶界及晶界附近的γ γ′共晶及其反应前缘富Zr 等低熔物熔化;④沿晶界及晶界附近的TiC 全部或部分溶解、产生“组分液化”;③这些液相沿晶界漫流形成液化晶界的部分在焊接收缩应力下开裂。根据上述裂纹产生机理调整了某铸造镍基合金成分,合金的液化裂纹倾向性得到了改善。根据液化裂纹成因,采取了防止措施,在产品焊接上取得了良好效果。     

Orientation dependence of dielectric and relaxor behaviour in Aurivillius phase BaBi2Nb2O9 ceramics prepared by spark plasma sintering

Grain-oriented Aurivillius phase BaBi₂Nb₂ O₉ ceramics were fabricated using Spark Plasma Sintering (SPS). Their relaxor behaviour was confirmed by a strong frequency dispersion of the dielectric response. The dielectric behaviour has been fitted using different relaxor models. The relaxor parameters are isotropic, while the dielectric constants are highly anisotropic. The piezoelectric constant d ₃₃ is zero perpendicular and parallel to the hot pressing direction, and the P–E response is dominated by losses. The inability to pole the samples at room temperature is consistent with the T _f temperature (∼ ∼115 K) estimated from fitting the experimental data to the Vogel–Fulcher model. This suggests that it may be possible to observe piezoelectric and ferroelectric properties at very low temperatures.     

关于加强电能质量管理的几个问题

结合国内外电能质量的现状和动向，论述了在电力市场体制下加强电能质量管理的几个问题，包括提高对电能质量重要性的认识，建立、健全电能质量监督管理体系，完善电能质量标准体系以及电能质量的测量和治理等问题。     

醋酸类除冰盐侵蚀沥青混合料机理研究

使用醋酸类除冰盐除冰雪后,沥青路面出现沥青软化、沥青膜剥落、混合料松散等新型病害而导致沥青路面耐久性下降.针对新型除冰盐侵蚀破坏沥青混合料问题,提出了以TSR/D作为技术指标的浸没间接拉伸试验方法(ITT),试验结果表明醋酸类除冰盐侵蚀破坏沥青混合料的程度与除冰盐溶液的浓度呈正相关性.研究同时从沥青软化及除冰盐溶液-沥青界面特性二个角度开展除冰盐溶液侵蚀机理试验分析.采用动力粘度试验研究沥青粘度变化规律,结果表明:沥青经过高浓度除冰盐溶液浸泡后,沥青粘度明显降低,浸泡溶液浓度越高、浸泡时间越长沥青软化现象越显著;采用核磁共振试验研究除冰盐溶液-沥青界面特性,结果表明,随着除冰盐浓度的增加,除冰盐溶液表面张力降低、除冰盐密度增加,除冰盐液滴渗入沥青膜内部的速度明显增加,进而加速沥青路面的损坏.     

Crystallographic Structure and Ferroelectricity of (AxLa1−x)2Ti2O7 (A = Sm and Eu) Solid Solutions with High Tc

The solubility and ferroelectric properties of (A_xLa_1?x)₂Ti₂O₇ (A = Sm and Eu) solid solutions were investigated. The crystallographic structure of the solid solutions was studied using X‐ray diffraction and Raman spectroscopy. The solubility limits of Eu and Sm in (A_xLa_1?x) ₂Ti₂O₇ were found to be greater than x = 0.5 and 0.8, respectively. The solid solutions had a monoclinic perovskite‐like layered structure (PLS), similar to that of the pure La₂Ti₂O₇, when x was less than the solubility limit. When x was above the solubility limit the materials were biphase. The biphases of (Sm_xLa_1?x)Ti₂O₇ (x = 0.9) consisted of (Sm_xLa_1?x)₂Ti₂O₇ with PLS and pure Sm₂Ti₂O₇ with pyrochlore structure, and the biphases of (Eu_xLa_1?x)Ti₂O₇ (x = 0.6, 0.7, and 0.8) consisted of (Eu_xLa_1?x)₂Ti₂O₇ with PLS structure and La³⁺ doped Eu₂Ti₂O₇ with pyrochlore structure. The effect of A‐site substitution on the properties of La₂Ti₂O₇ was investigated by measuring the dielectric permittivity and loss at different frequencies and temperatures. The highest piezoelectric constant d₃₃ was 2.8 pC/N for (Sm_0.1La_0.9)Ti₂O₇.     

关注电能质量提高国民经济总体效益

论述电能质量对国民经济总体效益的影响,介绍北京地区2004年对用户进行电能质量的初步调查情况(针对负荷结构、常见电能质量问题及其造成的影响、造成电能质量问题的原因等),说明我国电能质量领域存在的一些问题,并建议如何有效、经济地解决用户中广泛存在的电能质量问题的若干对策。     

Preparation and electrical properties of bismuth layer-structured ceramic Bi3NbTiO9 solid solution

Bi₃NbTiO₉ (BNT) ceramic materials with the density ratios of 95-97% to the theoretical density were prepared by the conventional mixed-oxide method. The Curie temperature (T_c), 914 °C was found to be almost the highest one among those of all the ceramics known to date. The crystal structure of the ceramic was investigated by X-ray diffraction method. Anisometric plate-like crystalline grains were observed, which revealed the layered structure of the material. The temperature dependence of the electrical resistivity was measured. For the first time the dielectric properties of Bi₃NbTiO₉ in the vicinity of its transition temperature were measured. Finally, the hysteresis (P-E) loop measurement showed a good ferroelectricity in the Bi₃NbTiO₉ ceramics, and the piezoelectric constant (d₃₃) was found to be 7 pC/N.