Image denoising method based on non-local Markov-chain Monte Carlo sampling and low rank approximation

Combining non-local Markov-chain Monte Carlo sampling and low-rank approximation of the matrix method, an approach for image noise removal is presented. The cluster of similar patches is searched by using Markov-chain Monte Carlo sampling. The cluster matrix of similar patches is decomposed by the singular value decomposition method,and the image noise is suppressed by applying the low rank structure from decomposing. Simulation results show that the proposed method outperforms the BM3D and the non-local means (NLM)method in computational-complexity. The proposed method has a better performance in protecting image details compared with the NLM method, and has some advantages over the BM3D method in terms of visual quality.     

一种双重正则化支持向量机的改进算法

针对L1范数支持向量机和L2范数支持向量机在分析部分小样本、高维数、变量高相关的数据时效果不理想的问题,在综合利用这2种支持向量机优点的基础上,提出一种双重正则化支持向量机的改进算法。通过正号函数和二次多项式损失函数将问题转化为可微的无条件约束优化问题,便于采用多种优化算法进行运算。实验结果证明,该改进算法可取得较好的分类准确率。     

UML建模在高校社团管理系统中的应用

利用UML建模工具对高校社团管理系统的功能模型进行详细分析,给出面向对象系统的分析方法和模型,为应用UML建模技术进行面向对象软件开发提供参考范例和借鉴。     

One-step conversion of syngas to light olefins over bifunctional metal-zeolite catalyst

Light olefins(C_2–C_4) are fundamental building blocks for the manufacture of polymers, chemical intermediates,and solvents. In this work, we realized a composite catalyst, comprising Mn_xZr _yoxides and SAPO-34 zeolite,which can convert syngas(CO + H_2) into light olefins. Mn_xZr_yoxide catalysts with different Mn/Zr molar ratios were facilely prepared using the coprecipitation method prior to physical mixing with SAPO-34 zeolite. The redox properties, surface morphology, electronic state, crystal structure, and chemical elemental composition of the catalysts were examined using H_2-TPR, SEM, XPS, XRD, and EDS techniques, respectively. Tandem reactions involved activation of CO and subsequent hydrogenation over the metal oxide catalyst, producing methanol and dimethyl ether as the main reaction intermediates, which then migrated onto SAPO-34 zeolite for light olefins synthesis. Effects of temperature, pressure and reactant gas flow rate on CO conversion and light olefins selectivity were investigated in detail. The Mn_1Zr_2/SAPO-34 catalyst(Mn/Zr ratio of 1:2) attained a CO conversion of 10.8% and light olefins selectivity of 60.7%, at an optimized temperature, pressure and GHSV of 380 °C, 3MPa and 3000 h~(-1) respectively. These findings open avenues to exploit other metal oxides with CO activation capabilities for a more efficient syngas conversion and product selectivity.     

基于NRC和多模态残差神经网络的肺部肿瘤良恶性分类

针对深度卷积神经网络训练时的网络退化、特征表达能力不强等问题,提出一种基于非负表示分类和多模态残差神经网络的肺部肿瘤(residual neural network-non negative representation classification, resnet-NRC)良恶性分类方法。使用迁移学习将预训练残差神经网络模型初始化参数;分别用CT、PET和PET/CT 3个模态的数据集训练残差神经网络,提取全连接层的特征向量;采用非负表示分类器(non-negative representation classification, NRC)对特征向量进行非负表示,求解非负系数矩阵;利用残差相似度进行肺部肿瘤良恶性分类。通过AlexNet、GoogleNet、ResNet-18/50/101模型进行对比试验,试验结果表明,ResNet-NRC分类效果优于其它模型,且特异性和灵敏度等各项评价指标也较高,该方法具有较好的鲁棒性和泛化能力。     

基于FX2N的液压回转工作台顺序控制方法

利用顺序功能图和梯形图来编制用户程序,以实现单台设备或生产过程的顺序控制,是PLC的主要功能之一.以液压回转工作台的顺序控制为例,论述了三菱FX2N系列PLC的用户程序设计方法;通过比较,指出了各种方法的应用特点.     

The corrosion of INCONEL alloy 740 in simulated environments for pulverized coal-fired boiler

The corrosion of a new nickel base superalloy, INCONEL alloy 740, has been studied at 550 and 700 °C on exposure to the synthetic coal ash/flue gas environments by means of XRD, SEM, and EDX. Low temperature hot corrosion of the new alloy occurred at two temperatures. The corrosion started to form the thin Cr₂O₃ scale on the alloy at 550 °C and developed as pitting attack resulted from sulfidation. The frontal attack at 700 °C consisted of two successive stages in which the corrosion mechanism started from the sulfidation and ended up in the fluxing of oxide. The compact and protective Cr₂O₃ scale formed and the internal sulfidation took place during the initial stage. The severe hot corrosion occurred due to the presence of the molten CoSO₄ during the propagation stage. The loose and porous outer layer and the compact inner layer consisted of spinels and oxides, respectively. The sulfides of Cr, Ti, and Nb formed on the front of oxide scale and in Cr-depletion zone. The rapid degradation of corrosion resistance of the alloy can be attributed to the dissolution of both cobalt and cobalt oxide on the surface. The alloy of 25% Cr exhibited better resistance to coal ash/flue gas corrosion as compared to the alloy of 23% Cr in the present case.     

银川市人口的灰色预测

根据GM(1,1)模型的建模机理,建立了银川市人口预测模型,通过模型对"十一.五"期间银川市人口进行了预测,依据人口的发展特点提出银川市未来在人口与水资源方面的建议与对策,为建设大银川的人口发展规划提供了科学的依据.     

PLC在真空压力设备控制系统中的应用

通过对真空压力浸漆设备(VPI)的结构及工作原理的分析,重点叙述了西门子公司S7-300型可编程控制器(PLC)在浸漆设备中的应用。     

简易手动液压胶接强度试验机的设计制作

基于胶接工艺特点及胶接强度实验要求,设计制作了结构简单、制作容易、操作简捷的简易手动液压胶接强度试验机.其主体采用上下两个框架构成试验机机架及传力部件;液压系统及工作部件设计均选用成熟技术和廉价产品,如液压油缸、液压泵均选用汽车液压制动泵和液压离合器泵改制而成,避开精密部件加工制作技术要求高、工艺复杂、制造成本高的难题,做到了经济实用;试件设计则是按胶接面典型破坏形式进行设计的;试件破坏力通过换算系统压强获得.结果表明,试验机技术指标符合要求.