铌酸钾钠基透明上转换陶瓷材料制备及性能

采用热压烧结工艺, 以LiBiO₃作为烧结助剂, 制备了铌酸钾钠基透明上转换陶瓷K_0.5(1-y)Na_0.5(1-y)Li_yNb_1-yBi_yO₃- Er_0.005Yb_0.005x(Er³⁺/Yb³⁺:KNNLB, x=0~3, y=0~0.09)。并对其微观结构、光学透光率和上转换效应等进行了研究。结果表明该透明陶瓷具有正交钙钛矿型结构, 晶粒尺寸约0.5 μm, 致密度较高。该材料在红外区和可见光区有良好的透明性, 但是随着铒镱掺杂量的增加, 可见光区透光率呈明显的下降趋势。当y=0.06、x=0时, 在可见光范围内透过率可达到45%(样品厚度为0.5 mm), 红外光区域透过率达到95%以上。铒镱共掺杂透明陶瓷实现了在波长900 nm氙灯光源激发下的上转换效应。     

In situ formed two-phase metallic glass with surface fractal microstructure

The alloy La_27.5Zr_27.5Al₂₅Cu₁₀Ni₁₀ was found to phase separate during quenching from the melt into (La–Cu)-rich and (Zr–Ni)-rich glassy phases with compositions close to those of Zr–Ni–Al and La–Cu–Al bulk metallic glasses. As-quenched samples consist of two amorphous phases in spherical shape with a wide range of length scales from tens of micrometers to a few nanometers. Several self-similar generations of spheres in spheres were observed using scanning electron microscopy and transmission electron microscopy. Small angle X-ray scattering results show an exponential dependence to the power of −3.4 of the intensity on the scattering vector, indicating a surface fractal microstructure of dimension 2.6. The selected area diffraction patterns obtained from two-phase regions show two clearly distinguishable halo rings and the high resolution electron microscope image shows isotropic maze patterns with two different length scales corresponding to the difference in the average atomic distance of the two amorphous phases.     

自组织特征映射网络在建筑工程分类中的应用

针对传统建筑工程造价估算方法耗时量大、计算繁琐、误差频出的问题,提出了一种用自组织特征映射(SOFM)网络对建筑工程量样本量化后的值进行聚类的方法。该方法不需要手动标识训练数据集就可以实现不同类型的建筑样本自动分类,有助于提高传统建筑工程造价估算的效率。最后,通过实例验证了该方法的实用性和有效性。实验结果表明,改进的方法用于建筑工程造价估算较传统方法而言具有更高的准确率和更低的误报率。     

开关功率变换器中的间歇现象 ——仿真与实验

 文章从电路耦合滤波的角度考虑,分析了一类间歇分谐波与间歇混沌现象产生的原理,确定耦合电路传导和辐射干扰是产生该现象的根源,并构造了一个开关变换器模型作为研究对象,仿真与实验均得到了相似的非线性现象,同时对不同的电路参数集,讨论并分析了其对间歇现象产生所起的不同影响,为变换器的稳定设计提供信息.该研究方法也可推广到其他非线性电路系统的类似研究中.     

A generalized counter scheme

The transposition heuristic is a common method used to improve the performance of accessing records in a linked list. After the list has reached a steady state for the transposition heuristic, we begin to keep a frequency count for each record. A method of re-arranging the records, called the generalized counter scheme, is introduced and is shown to be optimal among all possible methods of re-arrangement based on the counts. The scheme is applicable even when the count is small.The usual counter scheme is also shown to be optimal for any finite count.     

F-P半导体激光器中的串扰现象

研究应用F-P半导体激光器的两个模式时,在不同输入功率和失谐波长下的各种串扰现象.发现对已实现注入锁定的模式,注入功率越大,串扰现象越小;失谐波长越大,串扰现象越小.     

预制外墙外保温装饰板材的研制

开发了一种具有保温装饰双重效果的外墙外保温板,介绍了板材结构设计和板材组成材料的选择方法。测试了板材性能,该板材具有优越的保温性能,与传统外墙外保温施工相比,生产效率高,装饰效果好。     

PDA-SVM Hybrid: A Unified Model for Kernel-Based Supervised Classification

For most practical supervised learning applications, the training datasets are often linearly nonseparable based on the traditional Euclidean metric. To strive for more effective classification capability, a new and flexible distance metric has to be adopted. There exist a great variety of kernel-based classifiers, each with their own favorable domain of applications. They are all based on a new distance metric induced from a kernel-based inner-product. It is also known that classifier’s effectiveness depends strongly on the distribution of training and testing data. The problem lies in that we just do not know in advance the right models for the observation data and measurement noise. As a result, it is impossible to pinpoint an appropriate model for the best tradeoff between the classifier’s training accuracy and error resilience. The objective of this paper is to develop a versatile classifier endowed with a broad array of parameters to cope with various kinds of real-world data. More specifically, a so-called PDA-SVM Hybrid is proposed as a unified model for kernel-based supervised classification. This paper looks into the interesting relationship between existing classifiers (such as KDA, PDA, and SVM) and explains why they are special cases of the unified model. It further explores the effects of key parameters on various aspects of error analysis. Finally, simulations were conducted on UCI and biological data and their performance compared.     

计算圆环天线的麦克斯韦电路理论

本文以麦克斯韦电路理论为基础对圆环天线加以分析,得到圆环天线的表面电流分布.经比对发现本文计算结果与矩量法计算结果一致,证明了本文方法的有效性和正确性.通过对圆环天线二阶MC方程的深入研究,得到了圆环天线表面电流的解析表达式,该式适于计算任意大小圆环天线的表面电流分布.本文成果对求解复杂电磁结构问题具有一定参考意义.     

3种不同导电纤维的大应变传感特性的比较研究

针对不同基体纤维,即PA6、Lycra和XLA,研究了3种具有PPy(聚吡咯)涂层的柔性导电纤维的大应变传感特性.导电纤维样品由化学气相沉积法制得;纤维的大应变传感特性实验在拉伸试验机下进行,同时记录下电阻随应变的变化.借助于SEM观测手段,得到了3种纤维的截面形状及纤维在加载条件下表面涂层形貌的微观图像,为分析纤维的...