基于鲁棒稀疏表示的人脸识别算法

提出了一种基于LBP算子和鲁棒稀疏表示的人脸识别方法。首先,提取训练样本和测试样本的LBP特征。其次,在原有稀疏表示分类器(SRC)的基础上添加一个权值矩阵W来解决l1正则化最小二乘问题。最后,利用鲁棒稀疏表示分类器(RSRC)分类测试人脸图像所属类别。在ATT人脸库上进行实验的结果表明,此方法是优于其他经典算法的。     

1.5kW户用光伏高频逆变器研制

分析了一种具有中间储能环节的高频隔离逆变拓扑结构,该电路能实现前后级解耦,适用于光伏发电系统。前级DC/DC高频升压电路基于有限双极性调制,实现升压功能;后级采用双极性SPWM逆变技术,结合电压平均值反馈使输出电压稳定。详细介绍了高频变压器和LC滤波电路的设计方法,最后搭建了1.5k W高频逆变实验平台,实验结果显示,逆变器具有输出电压稳定,波形畸变小等优点。     

异构网络中基于Savitzky-Golay滤波的垂直切换算法

为了实现异构网络中的无缝链接和准确地判断网络状态,需加强确定移动台(MS)的位置信息,以及减少不利的衰落效应。本文提出了一种基于Savitzky-Golay滤波(即S-G滤波)的垂直切换算法,该算法能够使MS准确地判断网络的覆盖范围。仿真结果表明,该算法可以减少衰落效应,从而有效地减少了乒乓效应,提高了网络的性能。     

烟草工业控制系统安全防护分析与对策

随着工业控制系统在制造行业过程控制中的大量运用,不可避免的带来了系统安全的各类风险和威胁。本文将从烟草工业控制系统实际面临的威胁出发,对烟草工业控制系统中所可能遇到的威胁进行实例分析,并提出合理、有效的解决防护思路,以达到抛砖引玉作用,希望能在烟草行业信息安全发展方向中探寻出一种新的发展思路和方向。     

Advanced research into the growth mechanism and optical properties of wurtzite ZnSe quantum dots

Zinc selenide (ZnSe) quantum dots (QDs) with the hexagonal wurtzite structure were successfully prepared using a safe, controllable ethylenediamine-mediated solvothermal method in the absence of surfactants. This new synthesis process of the wurtzite ZnSe QDs was described and the growth mechanism of QDs was proposed. The room-temperature photoluminescence (PL) spectrum of the wurtzite ZnSe QDs (about 4 nm) showed a strong near-band-edge emission peak at 422 nm. The near-band-edge emission peak was blue-shifted compared to that of the bulk ZnSe due to the quantum confinement effects; the peak also displayed a progressive red-shift with increasing the excitation power and an associated reduction in peak energy of up to 300 meV. Band gap renormalization in the electron–hole plasma regime might be used to explain this phenomenon. No previous published research regarding the observed excitation-power-dependent PL properties of the wurtzite ZnSe QDs had been found. Our experimental results contributed valuable insights into the optical properties of the wurtzite ZnSe QDs; with potential applications in optoelectronics and other areas where advanced uniformly-structured nanocrystalline semiconductor materials were finding increased use.     

Structural and magnetic properties of spinel (Co,Cu)Fe2O4 ferrites prepared via a hydrothermal and sintering process

Spinel Co–Cu ferrites with the nominal composition Co_1?x Cu _x Fe₂O₄ ferrites (x = 0.0–0.4 with steps of 0.1) were prepared by a hydrothermal and sintering process, and the structural and magnetic properties of as-synthesized and sintered powder specimens were compared by using X-ray diffractometry, scanning electron microscopy, energy dispersive spectrometry and vibrating sample magnetometer analyses. It is found that all the as-synthesized and sintered specimens are single phase, and only suitable amount of Cu²⁺ substitution (x ≤ 0.3) is favorable for the growth of grains at high sintering temperature. In addition, with the increase of x, the saturation magnetization of both the as-synthesized and sintered powders decreases continuously, while the coercivity exhibits a first increasing but then decreasing tendency.     

Effect of Co doping on the structure,optical and magnetic properties of LaAlO3 thin films

LaAl_1?x Co _x O₃ (x = 0, 0.05 and 0.10) thin films were fabricated on quartz substrates by sol–gel method. X-ray diffraction data indicate that all thin films belong to perovskite LaAlO₃, and there is no secondary phase. Two obvious Raman peaks are observed in the Raman spectra, and the 113 cm^?1 peak is assigned to A₁ mode of perovskite LaAlO₃ while the 696 cm^?1 peak is caused by the Co–O stretching vibration. The band gap of the films decreases from 5.66 to 5.40 eV with the Co composition increasing from 0 to 10 %. The magnetization of the films was investigated, and it enhances significantly with increase of the Co content.     

两步法聚酰亚胺纳滤膜的制备——凝胶化过程对膜结构与性能的影响

采取两步法制备了聚酰亚胺(PI)纳滤膜。由于固液相转化法是制备纳滤膜最为广泛应用的方法,为改善加工工艺,文中在固液相转化前首先进行了凝胶化处理,然后再经过相转化制备了一系列聚酰胺酸(PAA)纳滤膜,最后通过化学亚胺化形成PI纳滤膜。XRD结果显示,PAA膜在19°左右显示出较尖锐的反射峰,不同溶剂对PAA诱导结晶产生凝胶结构的能力不同,其诱导PAA结晶的能力强弱关系为N-甲基吡咯烷酮(NMP)>N,N-二甲基乙酰胺(DMAc)>N,N-二甲基甲酰胺(DMF),此步中凝胶强弱会导致其膜结构与性能的很大变化。使用NMP为溶剂并经过凝胶化处理的PAA膜具有最高通量和截留率,分别为98 L/(m2·h)和98%。化学亚胺化会使膜结构前后发生改变,PI膜的皮层变致密,并导致通量变小。     

NCP-400L数控车床的工业设计改进研究

我国很多机电产品在技术上已接近世界先进水平,但对于工业设计的重视不够,直接影响了我国产品在国内外市场上的竞争力.通过NCP-400L数控车床工业设计改进的设计实践,探讨了如何在保持产品基本结构和原有工艺装备不变的前提下进行工业设计改进的方法.运用形态比例调整、色彩表现和人机交互设计等手段,实现产品的视觉形象与内在质量的和谐统一.     

石松子粉尘爆炸危险性及抑爆研究

为了研究粒径对石松子粉尘爆炸危险性的影响,采用Godbert-Greenwald(G-G)炉和20 L球爆炸装置对石松子粉尘云进行了试验,分析了粒径对爆炸特性的影响,并探讨了Si O2和NH4H2PO4对石松子粉的抑爆效果。结果表明:粒径越小的粉尘着火温度越低,潜在危险性更大;粒径小于48μm的粉尘,在质量浓度为750 g/m3时达到最大爆炸指数22.61 MPa·m/s,其爆炸危险性为Ⅱ级,相比于粒径小于75μm的粉尘,爆炸危险性更高;添加Si O2和NH4H2PO4后,能够显著降低石松子粉的爆炸压力和爆炸指数;与Si O2相比,NH4H2PO4具有更好的抑爆效果。