悟

“悟”是一种对客观的事和物的一种感知,是对事和物获取了解、获取知效,是人们求得理解的一种启示、一种认识的过程。一般地说,“我对事和物,意在彻悟”,是指人们得到充分的悟性,特别对意、意义的悟,有的很快领会,有的要耗费时日,有的要经过一定的时间乃至终身。悟性就是理解的     

Pattern analysis of airborne dipole antenna in high-frequency region

The Uniform Geometrical Theory of Diffraction (UTD) has been successfully used in pattern analysis of airborne dipole antenna on the A-5 fighter in high-frequency region. In the analysis, several canonical problems are investigated first, then the complicated problem is calculated with compiling these canonical problems. The numerical results are compared with the experimental data, and good agreement has been seen. The effectiveness and practicality of the present analysis are thus verified.     

双能X射线骨密度仪测定技术研究

以Ｌｕｎａｒ公司ＤＰＸ－Ｌ型双能Ｘ射线骨密度仪为例，研究引起测量误差的主要因素并提出质控措施。用自检模块、腰椎体膜评定仪器的体外测量精度好于１％。对１０位志愿者重复２次测量，体内精度对腰椎，ＭＰＤ（平均百分差）为０．４６，ＣＶ（变异系数）为０．７５；对股骨颈，ＭＰＤ为１．２６、ＣＶ为０．４７；Ｗａｒｄ’ｓ三角区ＭＰＤ为２．０１、ＣＶ为１．１４；大转子ＭＰＤ为１．６６、ＣＶ为０．７２。扫描图像由２位     

Feature Reduction via Generalized Uncorrelated Linear Discriminant Analysis

High-dimensional data appear in many applications of data mining, machine learning, and bioinformatics. Feature reduction is commonly applied as a preprocessing step to overcome the curse of dimensionality. Uncorrelated Linear Discriminant Analysis (ULDA) was recently proposed for feature reduction. The extracted features via ULDA were shown to be statistically uncorrelated, which is desirable for many applications. In this paper, an algorithm called ULDA/QR is proposed to simplify the previous implementation of ULDA. Then, the ULDA/GSVD algorithm is proposed, based on a novel optimization criterion, to address the singularity problem which occurs in undersampled problems, where the data dimension is larger than the sample size. The criterion used is the regularized version of the one in ULDA/QR. Surprisingly, our theoretical result shows that the solution to ULDA/GSVD is independent of the value of the regularization parameter. Experimental results on various types of data sets are reported to show the effectiveness of the proposed algorithm and to compare it with other commonly used feature reduction algorithms.     

Nonregular feedback linearization: a nonsmooth approach

In this note, we address the problem of exact linearization via nonsmooth nonregular feedback. A criterion of nonregular static state feedback linearizability is presented for a class of nonlinear affine systems with two control inputs, and its application to nonholonomic systems is briefly discussed.     

担载型含稀土三组份体系在二氧化碳甲烷化反应中的催化性能

用浸渍法制备了一系列氧化锆担载的含稀土Ⅷ族金属催化剂，对其在二氧化碳甲烷化过程中的催化活性作了研究，并用漫反射紫外可见光谱，ＦＴＩＲ等手段对催化剂作了表征。结果表明，含稀土新型催化剂具有催化活性高，目标产物选择性好等优点；稀土主要以氧化物形式存在于催化剂表面，参与对氢及表面含碳物种的吸附及活化；含稀土三组份催化剂的活性与所添加稀土三价离子的４ｆ电子数有关。     

铝阳极氧化膜颜色的检验和观察法

介绍铝及铝合金阳极氧化膜颜色的概念和描写,对颜色的儿种测量方法进行了比较,重点分析观察法及其在各国标准中的异同。在此基础上,提出了GB8013中的对颜色进行观察的条件和理论根据。     

二氧化硅包覆CsPbI3纳米晶薄膜的制备

卤化钙钛矿型(ABX3)纳米材料是近几年兴起的光电新材料,由于全无机钙钛矿CsPbX3(X=Cl,Br,I)纳米晶体的稳定性差,严重阻碍了实际应用,但因其具有窄带隙,在太阳能电池领域有着重要的应用前景.本研究在CsPbI3纳米晶周围使硅酸四甲酯(TMOS)发生水解反应,形成CsPbI3@SiO2纳米晶体复合材料,促使甲苯悬浮液的稳定性显著提高,发光稳定性可增加到29 d.通过进一步以聚(苯乙烯-乙烯-丁二烯-苯乙烯)三嵌共聚物(SEBS)对复合材料进行包裹,得到具有良好透明性和可拉伸性的SEBS/CsPbI3@SiO2薄膜,在水中有保持24 h稳定荧光现象,在水中12 h能保持原有发光强度的53％,而未经二氧化硅包裹的SEBS/CsPbI3纳米晶薄膜在水中仅8 h就失去荧光.本研究不仅为CsPbX3的表面改性提供了一种新方法,有助于解决稳定性问题,而且以聚合物复合的薄膜具有可拉伸性,也可应用在柔性器件中,具有重要的应用价值.     

风轮模拟试验平台的仿真与研究

分析风力机的特性,在上位机上搭建风力机的模型,通过上位机对变频器输入指令以实现对异步电机的控制,通过光电编码器和USB数据采集卡实现转速采集.设计一套基于LabVIEW的风轮模拟试验平台,为试验室的无风环境提供可控风速.提出一种转速控制方案并实现仿真,便于进行风力发电技术的研究.     

软土地基油罐底板变形分析

分析了造成油罐底板变形的原因、形式及其危害，结合工程实例，提出了减少油罐底板不均匀变形的措施。