Tuning effect of silicon substitution on magnetic and high frequency electromagnetic properties of R2Fe17 and their composites

In this work, we report the tuning effect of the Si substitution on the magnetic and high frequency electromagnetic properties of R₂Fe₁₇ compounds and their paraffin composites. It is found that the introduction of Si can remarkably improve the magnetic and electromagnetic properties of the R₂Fe₁₇ compounds, making the R₂Fe_17–xSi_x-paraffin composites excellent microwave absorption materials (MAMs). By introducing the Si element, their saturation magnetizations decrease slightly, while much higher Curie temperatures are obtained. Furthermore, better impedance match is reached due to the decrease of the high-frequency permittivity ε′ by about 40%–50%, which finally enhances the performance of the microwave absorption. The peak frequency (f_RL) of the reflection loss (RL) curve moves toward high frequency domain and the qualified bandwidth (QB, RL ≤ ?10 dB) increases remarkably. The maximum QB of 3.3 GHz (12.0–15.3 GHz) is obtained for the Sm_1.5Y_0.5Fe₁₅Si₂-paraffin composite (d = 1.0 mm) and the maximum RL of ?53.6 dB is achieved for Nd₂Fe₁₅Si₂-paraffin composite (d = 2.2 mm), both surpassing most of the reported MAMs. Additionally, a distinguished dielectric microwave absorption peak is observed, which further increases the QB in these composites.     

大长径比自旋弹箭横向自振特性的有限元计算方法与结果分析

本文研究大长径比自旋弹箭在飞行时横向振动的自振特性。本文将转子动力学应用于弹道学 ,采用有限元法 ,建立自旋弹箭横向振动自振特性方程。同时给出了计算方法。利用该方程和该方法 ,开发了相应的计算程序。通过数值计算 ,可给出细长旋转弹箭飞行时的进动转速和临界转速 ,以及相应的位移和角度振型。利用该程序 ,进行了实例计算和分析。     

光缆CATV用DFB激光器发射组件

介绍了国内首次研制的光缆ＣＡＴＶ用１．３μｍＤＦＢ激光器组件。组件工作频带达到１ＧＨｚ，带内起伏〈１ｄＢ，组件的ＲＩＮ〈－１５３ｄＢ／Ｈｚ；出纤光功率〉２ｍＷ，载噪比ＣＮＲ〉５０ｄＢ。首次实现用低反射尖锥端光纤的ＤＦＢ激光器耦合。     

配网侧接入电源对负荷建模的影响

研究了配网侧接入电源对负荷建模的影响。发现当配网侧电源的发电容量逐渐增大时，原有的感应电动机并联恒阻抗、恒电流、恒功率（ZIP）模型的负荷模型将不再能很好地反映该区域的负荷特性，进而提出了一种新的负荷模型结构———异步发电机并联ZIP模型。通过仿真计算，验证了该新负荷模型的有效性，并进一步统一了上述2种负荷模型，称为异步机并联ZIP负荷模型。     

住宅建筑结构中隔震技术的应用和经济评价

对当前隔震系统做了简单介绍 ,介绍了基础隔震的技术和施工方法等。讨论在住宅结构中推广隔震技术的方法 ,对各种类型的住宅结构做经济评价 ,讨论推广的可能性和难点。     

集成基础结构中应用服务器的研究与开发

通过对集成基础结构中应用服务器的功能需求分析，采用面向对象方法、矩阵理论和Ｐｅｔｒｉ网技术研究了应用服务器系统的实现策略，并依据智能工程理论给出了应用服务器的系统结构。     

贮存稳定的聚氨酯干式复合胶粘剂的研究

研制了一种具有高固含量、低粘度的干式复合用双组分聚氨酯胶粘剂，考察了聚酯多元醇，扩链剂丙三醇／乙二醇（摩尔比）、NCO／OH（摩尔比），双组分胶配比以及缓凝剂等因素对该胶粘剂性能的影响，并用红外光谱对胶的固化过程进行了表征。结果表明，该胶粘剂具有较高的粘接强度，优良的低温流动性和贮存稳定性。     

Numerical simulation of 3-D wing flutter with fully coupled fluid-structural interaction

A numerical methodology coupling Navier-Stokes equations and structural modal equations for predicting 3-D transonic wing flutter is developed in this paper. A dual-time step implicit unfactored Gauss-Seidel iteration with the Roe scheme is employed for the flow solver. A modal approach is used for the structural response. The flow and structural solvers are fully coupled via successive iterations within each physical time step. The mesh-deformation strategy is described. The accuracy of the modal approach is validated with ANSYS. The results indicate that the first five modes are sufficient to accurately model the wing-structure response for the studied case of this paper. The computed flutter boundary of AGARD wing 445.6 at free stream Mach numbers ranging from 0.499 to 1.141 agrees well with the experiment.     

沥青基高比表面积活性碳的物理及化学结构

本文用ＡＳＡＰ２０００吸附仪测定了吸附性能优异的沥青基高比表面积新型活性碳（ＰＨＡＣ）的ＢＥＴ比表面积、用ＢＪＨ和ＤＲＳ法分析了其孔隙结构参数，用ＸＰＳ测定了ＰＨＡＣ的表面元素组成及含氧官能团，对ＰＨＡＣ的表面形态结构进行了ＳＥＭ和ＴＥＭ观察。研究表明：ＰＨＡＣ具有高度发达且均匀的微孔结构，其表面含有一定量的Ｃ－Ｏ－Ｃ、Ｃ－ＯＨ、Ｃ＝Ｏ、Ｏ＝Ｃ－Ｏ等多种类型的含氧官能团。     

电磁搅拌对ZA-27合金凝固组织的影响

研究了保温电磁搅拌和间断性电磁搅拌对ZA27合金组织的影响，在保温凝固过程中进行电磁搅拌时，晶粒细化效果更明显。保湿搅拌温度存在搅拌效果最理想的临界值Tc。间断性电磁搅拌使得枝晶显著粒化，晶粒分布更加均匀。