Coupled Cross-correlation Neural Network Algorithm for Principal Singular Triplet Extraction of a Cross-covariance Matrix

This paper proposes a novel coupled neural network learning algorithm to extract the principal singular triplet (PST) of a cross-correlation matrix between two high-dimensional data streams. We firstly introduce a novel information criterion (NIC), in which the stationary points are singular triplet of the crosscorrelation matrix. Then, based on Newton's method, we obtain a coupled system of ordinary differential equations (ODEs) from the NIC. The ODEs have the same equilibria as the gradient of NIC, however, only the first PST of the system is stable (which is also the desired solution), and all others are (unstable) saddle points. Based on the system, we finally obtain a fast and stable algorithm for PST extraction. The proposed algorithm can solve the speed-stability problem that plagues most noncoupled learning rules. Moreover, the proposed algorithm can also be used to extract multiple PSTs effectively by using sequential method.      

参数控制反问题的求解及其在坝工渗流中的应用

采用脉冲谱技术求解抛物型方程参数控制反问题和边界元-优化法求解Poisson方程参数控制反问题;推导了算式,给出了计算程式,并分别采用这两种方法反演了非均质矩形土坝的渗透系数和某重力坝坝基帷幕区补强前后的渗透系数.计算结果表明,用脉冲谱法和边界元-优化法求解参数控制反问题是行之有效的,应用于岩土渗流计算,可基本解决坝体和地基渗透系数的反演问题,其优点是所需附加信息量少,无需大面积的钻孔取样工作,可节省大量投资.     

新型PST铁电薄膜的制备及其电性能研究

PST铁电薄膜是一种具有优良铁电、热释电和介电等性能的铁电材料.该材料在红外探测器、红外焦平面阵列、热成像器件、非易失性铁电存储器和大容量电容器等方面具有广泛的应用.PST铁电薄膜的制备方法多种多样,各具优缺点,不同的制备工艺对薄膜的性能有影响.叙述了PST铁电薄膜的制备技术、电性能和在热释电红外探测器方面的应用.     

相量分析方法在差动保护调试中的运用

差动保护是变压器的主要保护,差动保护在变压器投运后,需带负荷校验极性并保证接线正确。通过带负荷时作出各侧电流的相量图,具体分析差动接线不正确的原因,并提出相应的解决办法。     

全片层TiAl合金临界屈服应力及影响因素的细观研究

基于PST晶体的微结构和γ相及α2相普通位错和孪晶滑移启动，结合细观力学方法，通过数值模拟两相中的各滑移系上的分切应力，得出PST晶体屈服应力和外加载荷与片层之间夹角θ的关系；详细讨论了γ相中孪晶与普通位错的临界切应力之差异对PST晶体屈服应力的影响。对单轴和双轴加载的情况分别进行了计算，得到的结论与已有的一些实验结果相吻合。     

Piezo- and pyroelectric properties of lead scandium tantalate thin films

Abstract

This paper discusses the piezo- and pyroelectric properties of lead scandium tantalate thin films prepared by modified sol-gel technology. Films were deposited on Pt/Ti/SiO₂/Si-sub-strates at 530–630 °C. The quality of the thin films was optimized by design of both the deposition conditions and the solution chemistry. These approaches include spin coating speed, drying plus crystallization temperature and time, drying atmosphere, the use of rapid thermal annealing, PST sol composition, Pb-excess concentration and mixing method. The finished thin films were characterized by optical microscopy, X-ray diffraction, atomic force microscopy, and pyroelectric measurements at 30°C under a DC-bias. Piezo-response AFM was conducted on PST to monitor various piezoelectric responses, which depend on the micro-structure of the film. The maximum pyroelectric figure-of-merit F_D was 3.85×10^?5 Pa^?1/2 at 30°C and 1 kHz under a 35 V DC-bias.     

PST技术在阿尔及利亚东西高速公路中的应用

以阿尔及利亚东西高速公路为工程背景,简要介绍了PST的概念及设计形式,阐述了PST技术的材料界定、分析以及PST施工、验收的详细过程,以期为同类工程在实施过程中提供参考与借鉴。     

Effect of Lamellar Orientation on Crack Paths in PST Crystals of -TiAl Based Alloys

The effect of lamellar orientation on crack paths in PST crystals of -TiAl based alloys was investigated by in-situ SEM technique. The results indicate that the crack paths in PST crystals of -TiAl based alloys are strongly dependent on lamellar orientation of PST crystals, and the differently oriented PST crystals show different nucleation and propagation mechanisms of crack, resulting in different levels of fracture toughness.     

ORIENTATION EFFECTS ON CREEP OF A LAMELLAR TiAl ALLOY

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二次合成法制备(Pb1-xSrx)TiO3铁电陶瓷的性能

采用二次合成的方法,即第一次按陶瓷制备工艺分别合成PbTiO_3与SrTiO_3粉体,第二次将PbTiO_3与SrTiO_3粉体按所需比例混合,成功地制备了性能较好的(Pb_(1-x)Sr_x)TiO_3铁电陶瓷。测试表明,其介电特性较好,介电常数可达10~4量级,介电损耗可低于1.0%;其铁电效应普遍较强,室温附近饱和极化强度可超过10μC/cm~2,矫顽场强可低于100 kV/m,热释电系数达10~(-1)μC/cm~2K量级。