微带型Wilkinson功分器设计与实现

小型低功耗器件是射频电路设计的研究热点,而微带技术具有小型化低功耗的优点,为此在介绍微带型Wilkin-son功分器工作原理的基础上,使用基于矩量法的ADS软件设计、仿真和优化计算相关数据参数,并制作了一个微带功分器实例,最后对加工的样品进行实测,获得与仿真值吻合较好的预期结果。     

羧酸系列集油剂的水面集油性能

研究了十二烷酸、十四烷酸、十六烷酸和十八烷酸在淡水中的集油能力。结果表明，这4种羧酸在淡水表面的表面膜压随其分子中碳数的增加而增大。其中后两者的表面膜压高达45～50mN／m，显著高于各类油膜膜压，满足集油剂对表面活性物质膜压的要求。4种脂肪羧酸在淡水中使柴油油膜的收缩率在1min时达到最大值，分别为80．0％、81．8％、83．8％和88．2％。它们的己醇、正庚醇、正辛醇、仲辛醇溶液的集油持续性，总体上随羧酸分子碳数增加而增大。其中十六烷酸和十八烷酸集油能力非常接近，它们的正庚醇、正辛醇和仲辛醇溶液使柴油膜面积收缩率在120h后仍保持在66．0％～70．2％。该类集油剂毒性低，易为生物降解，有实际应用前景。     

Finite element piezothermoelasticity analysis and the active control of FGM plates with integrated piezoelectric sensors and actuators

 An efficient finite element model is presented for the static and dynamic piezothermoelastic analysis and control of FGM plates under temperature gradient environments using integrated piezoelectric sensor/actuator layers. The properties of an FGM plate are functionally graded in the thickness direction according to a volume fraction power law distribution. A constant displacement-cum-velocity feedback control algorithm that couples the direct and inverse piezoelectric effects is applied to provide active feedback control of the integrated FGM plate in a closed loop system. Numerical results for the static and dynamic control are presented for the FGM plate, which consists of zirconia and aluminum. The effects of the constituent volume fractions and the influence of feedback control gain on the static and dynamic responses of the FGM plates are examined. Received: 13 March 2002 / Accepted: 5 March 2003 The work described in this paper was supported by a grant awarded by the Research Grants Council of the Hong Kong Special Administrative Region, China (Project No. CityU 1024/01E).     

Experimental evidence of a relationship between monomer plasma residence time and carboxyl group retention in acrylic acid plasma polymers

Decreasing carboxyl retention in deposits from the glow region of an acrylic acid plasma was measured by X-ray photoelectron spectroscopy and chemical derivatisation as the collection distance from the monomer vapour inlet was increased. Volatilisation of plasma polymerised acrylic acid was detected after trifluoroethanol derivatisation; this is correlated with evaporation of low molecular weight components observed previously.     

Development of geometrically exact new shell elements based on general curvilinear co‐ordinates

In the present study first‐order shear deformable shell finite elements based on general curvilinear co‐ordinates are proposed. For the development of the present shell elements, a partial mixed variational functional with independently assumed strains is provided in order to avoid the severe locking troubles known as transverse shear and membrane lockings. Bubble functions are included in the shape function of displacement to improve the performance of the developed element. The proposed assumed strain four‐ and nine‐node elements based on the general tensor shell theory provide an efficient linkage framework for shell surface modelling and finite element analysis. In the several benchmark problems, the present shell elements with exact geometric representations demonstrate their performance compared to previously reported results. Copyright © 2002 John Wiley & Sons, Ltd.     

在广西全面开展悬移质泥沙简测的可行性和重要性

通过对百色等水文站泥沙资料分析 ,并结合广西河流及泥沙特性和社会对泥沙资料的精度要求 ,得出了在广西实行悬移质泥沙简测的可行性。为满足广西国民经济可持续发展需要 ,提出了在广西改革悬移质泥沙测验方式的必要性和紧迫性     

Preparation and properties of nano-sized SnO2 powder

1　INTRODUCTIONSnO2isoneofthemainmaterialsusedingassensor.Becauseofthehumidityandgassensingfunction,itattractsmoreandmoreattentions.Butthepresentproblemishowtoimprovethestabilityandsensibilityofgassensor.Researchershavetakenmanymeasurestoresolvethisproble…     

HNO3和有机介质中U（Ⅳ）的稳定性研究

研究了ＨＮＯ＿３和ＴＢＰ－煤油介质中Ｕ（Ⅳ）的稳定性。测定了两种介质中Ｕ（Ⅳ）、ＨＮＯ＿３、ＴＢＰ浓度和气相中氧浓度对Ｕ（Ⅳ）氧化速率的影响。Ｕ（Ⅳ）的氧化速率都随温度提高而明显增加．其表观活化能分别为９１ｋＪ／ｍｏｌ（ＨＮＯ＿３介质）和４２ｋＪ／ｍｏｌ（ＴＢＰ－煤油介质）。对两种介质中Ｕ（Ⅳ）的氧化速率规律进行了比较。     

声光效应拉曼-内斯方程矩阵级数解法及声光调制器优化设计

提出一种求解正常声光相互作用拉曼 内斯 (Raman Nath)方程的矩阵级数解法 ,该解法直观方便且具有普遍性。计算结果表明 ,对Q =4 1π ,Bragg衍射的效率只有 97 5 % ;对非对称入射 ,以往的Raman Nath近似解误差较大 ;指出提高Bragg衍射效率的有效途径在于提高声光频率比并给出计算声光器件最优长度的计算公式。