基于P-K滤波的X波段雷达雨衰补偿研究

X波段天气雷达的回波信号经过降雨区时会存在偏振参量的衰减现象,偏正参量的衰减对雨量估计和气象天气分类等会产生影响,针对这一问题,本文提出一种结合了粒子滤波和卡尔曼滤波的方法（P-K滤波）。该方法首先对天气雷达回波数据中的差分传播相移参量利用P-K滤波算法进行滤波处理,进而利用订正的结果采用自适应算法对水平反射率因子进行衰减订正。利用P-K滤波算法和其他算法对相同的雷达数据进行处理对比,其结果表明,P-K滤波算法能够更有效地对差分传播相移进行衰减订正,其处理结果的平滑性和准确性更高,进而对水平反射率因子的衰减订正效果更好。     

基于EMD方法的X波段双偏振雷达衰减订正

针对X波段双偏振雷达信号在降雨路径中的衰减现象,本文提出经验模式分解（Empirical Mode Decomposition,EMD）方法进行X波段双偏振雷达衰减订正,首先对总差分传播相移进行EMD分解得到有限个基本模式分量（Intrinsic Mode Function,IMF）,并基于皮尔逊相关系数准则将IMF分为噪声IMF和信号IMF两类,然后对信号IMF进行有效重构得到差分传播相移,再将差分传播相移通过最小二乘法拟合得到差分传播相移率,最后对求得的差分传播相移与差分传播相移率采用自适应约束方法进行反射率衰减订正。利用EMD方法和其他方法进行对比分析,其结果表明,EMD方法能够有效地消除X波段双偏振雷达回波数据中后向散射的影响,在保留真实的气象信息的同时,有效地抑制差分传播相移的显著波动,进而衰减订正效果更好。     

PET瓶回收料的增粘工艺研究

对PET瓶回收料的物理增粘、化学增粘工艺进行了研究。结果表明,这两种工艺均能有效提高PET瓶回收料的粘度;以增粘后的PET瓶回收料制备的阻燃增强复合材料,其力学性能明显高于未增粘的PET瓶回收料;物理增粘PET的特性粘度与各掺混组分的粘度呈加和法则关系;环氧树脂类扩链剂的化学增粘效果优于恶唑啉类扩链剂。     

Changes in the Expression and Functional Activities of C-X-C Motif Chemokine Ligand 13 (CXCL13) in Hyperplastic Prostate

Background: C-X-C motif chemokine ligand 13 (CXCL13), a member of the CXC subtype in chemokine superfamily, affects numerous biological processes of various types of cells and the progress of a great number of clinical diseases. The purpose of the current study was to reveal the internal mechanism between CXCL13 and benign prostatic hyperplasia (BPH). Methods: Human serum, prostate tissues and human prostate cell lines (BPH-1, WPMY-1) were utilized. The effect of recombinant human CXCL13 (rHuCXCL13) protein and the influences of the knockdown/overexpression of CXCL13 on two cell lines were studied. Rescue experiments by anti-CXCR5 were also conducted. In vivo, rHuCXCL13 was injected into the ventral prostate of rats. Additionally, a tissue microarray of hyperplastic prostate tissues was constructed to analyze the correlations between CXCL13 and clinical parameters. Results: CXCL13 was highly expressed in the prostate tissues and upregulated in the BPH group. It was observed that CXCL13 modulated cell proliferation, apoptosis, and the epithelial–mesenchymal transition (EMT) through CXCR5 via AKT and the ERK1/2 pathway in BPH-1, while it contributed to inflammation and fibrosis through CXCR5 via the STAT3 pathway in WPMY-1. In vivo, rHuCXCL13 induced the development of rat BPH. Additionally, CXCL13 was positively correlated with the prostate volume and total prostate specific antigen. Conclusions: Our novel data demonstrated that CXCL13 modulated cell proliferation, cell cycle, the EMT of epithelial cells, and induced the fibrosis of prostatic stromal cells via a variety of inflammatory factors, suggesting that CXCL13 might be rediscovered as a potential therapeutic target for the treatment of BPH.     

Atomically Dispersed Fe/N4 and Ni/N4 Sites on Separate-Sides of Porous Carbon Nanosheets with Janus Structure for Selective Oxygen Electrocatalysis

Dual single atoms catalysts have promising application in bifunctional electrocatalysis due to their synergistic effect. However, how to balance the competition between rate-limiting steps (RDSs) of reversible oxygen reduction and oxygen evolution reaction (OER) and fully expose the active centers by reasonable structure design remain enormous challenges. Herein, Fe/N₄ and Ni/N₄ sites separated on different sides of the carbon nanosheets with Janus structure (FeNi_jns/NC) is synthesized by layer-by-layer assembly method. Experiments and calculations reveal that the side of Fe/N₄ is beneficial to oxygen reduction reaction (ORR) and the Ni/N₄ side is preferred to OER. Such Janus structure can take full advantage of two separate-sides of carbon nanosheets and balance the competition of RDSs during ORR and OER. FeNi_jns/NC possesses superior ORR and OER activity with ORR half-wave potential of 0.92 V and OER overpotential of 440 mV at J = 10 mA cm⁻². Benefiting from the excellent bifunctional activities, FeNi_jns/NC assembled aqueous Zn–air battery (ZAB) demonstrates better maximum power density, and long-term stability (140 h) than Pt/C+RuO₂ catalyst. It also reveals superior flexibility and stability in solid-state ZAB. This work brings a novel perspective for rational design and understanding of the catalytic mechanisms of dual single atom catalysts.     

虚拟现实技术应在建筑类艺术设计专业教学中广泛使用

虚拟现实技术随着计算机硬件与软件功能的增强飞速发展,它对建筑设计产生了重大的影响。虚拟现实技术所具有的优点,使它成为满足现代建筑设计要求的关键技术。在建筑学专业的教学中,我们应当引入虚拟现实的教学,让学生掌握虚拟现实技术。     

I形坡口焊缝检测LOG-Hough方法研究

对于间隙小于0．5mm的焊缝,在强烈弧光干扰环境下实现精确检测较为困难。文中就对不开坡口的细小焊缝提取做了试验研究,为精确检测细小焊缝提供一种新方法。在焊接过程中使用CCD视觉传感器获取焊接过程的图片信息,在对图像进行中值滤波后,采用LOG边缘检测算子检测出焊缝的边缘、再用Hough变换方法识别焊缝,找出焊缝位置,计算出焊缝宽度和焊缝中心。试验表明,使用LOG—Hough算法能准确地得出焊缝宽度和焊缝中心,并且具有较强的抗干扰能力。     

基于Struts框架的在线考试系统

介绍了Struts概念和体系结构,阐述了Struts的工作原理,给出了在线考试系统各个功能模块以及整个系统基于Struts的开发流程,并通过一个应用示例,介绍Struts框架在系统开发中的应用。     

电子束选区熔化成形TC4合金的显微组织及硬度

采用电子束选区熔化成形技术制备不同尺寸(?8 mm×25 mm,?25 mm×8 mm)TC4合金试样,研究了2种试样在粉末堆积方向的显微组织及硬度变化.结果表明:尺寸?8 mm×25 mm试样的显微组织主要由原始β柱状晶界处的针状α集束组织和晶内针状α相互相交错形成的网篮状魏氏组织组成,原始β柱状晶主轴平行于堆积方向...     

氢化物—原子荧光法测定乳粉中的微量硒

采用氢化物原子荧光光度法测定乳粉中的硒含量。样品经ＴＣ－Ⅱ型快速消化器用硝酸高氯酸混合酸消化后，直接上机测定，取得了较满意的结果。本方法具有操作简单、分析速度快、灵敏度高的特点。其最低检出限为０．５０ｎｇ／ｍｌ，回收率９０．２０％￣１０７．５％，线性范围为１．０￣２５０．０ｎｇ／ｍｌ，相当系数≥０．９９９７。