三峡水电站“充水保压”钢蜗壳外围混凝土结构三维有限元分析

本文介绍三峡水电站蜗壳结构三维有限元计算结果，结果表明：三峡水电站钢蜗壳选用充水保压浇筑外围混凝土的埋置方式是合适的；采用78～88m保压水头值比较合适；蜗壳结构各截面最大拉应力值出现在不同荷载组合情况下，在配置钢筋时应引起重视。     

电子商务对企业集团营销手段的影响

介绍了电子商务，以及目前电子商务的发展趋势及对社会的影响，特别阐述了蓬勃发展的电子商务对企业集团的经营环境与手段的影响。     

基于无监督深度图像生成的盲降噪模型

鉴于有监督神经网络降噪模型的数据依赖缺陷,提出了一种基于无监督深度生成（UDIG）的盲降噪模型。首先,利用噪声水平评估（NLE）算法测定给定噪声图像中的噪声水平值并输入到主流FFDNet降噪模型中,所得到降噪后的图像（称为初步降噪图像）作为UDIG降噪模型的输入。其次,选用编码器—解码器架构作为UDIG模型的骨干网络并用UDIG模型的输出图像（即生成图像）分别与初步降噪图像、噪声图像之间的均方误差之和构建混合loss函数;再次,以loss最小化为优化目标,通过随机梯度下降（SGD）网络训练算法调整网络模型的参数值从而获得一系列生成图像;最后,当残差图像（噪声图像与生成图像之间）的标准差逼近之前NLE算法所测定的噪声水平估计值时及时终止网络迭代训练过程,从而确保生成图像（作为降噪后图像）的图像质量最佳。实验结果表明：与现有的主流降噪模型（算法）相比,UDIG降噪模型在降噪效果上具有显著优势。     

含三维内裂纹透明类岩石材料破坏红外热像试验研究

由于目前针对含三维内裂纹的岩石破坏红外热像特征的研究较少,本文基于预埋浇注法制作含内裂纹类岩石试件,开展了单轴压缩块体试验和巴西圆盘劈拉试验,得到含内裂纹的岩石破坏过程,监测内裂纹扩展及试件破坏过程中的红外热像特征,得到以下结论:(1)含三维内裂纹的块体试件在单轴压缩下,在预制内裂纹面上发生剪切破坏;(2)块体试件在单轴压缩作用下红外热像特征明显,在破坏时,在预制内裂纹面处急剧升温;(3)含三维内裂纹巴西圆盘试件在预制内裂纹尖端发生翼型裂纹扩展,边缘带有针刺状Ⅲ型裂纹参与特征,最终翼型裂纹与上下表面贯穿;(4)巴西圆盘试验的红外热像特征与块体单轴压缩不同,在断裂面处未发生明显变化。研究结果为研究三维内裂纹的扩展规律及内裂纹扩展破裂的红外热像规律可提供一定的试验参考。     

New results on robust output regulation of nonlinear systems with a nonlinear exosystem

The global robust output regulation problem for nonlinear plants subject to nonlinear exosystems has been a challenging problem and has not been well addressed. The main difficulty lies in finding a suitable internal model. The existing internal model for handling the nonlinear exosystem is not zero input globally asymptotically stable, and can only guarantee a local solution for the output regulation problem. In this paper, we first propose a new class of internal models, which is guaranteed to exist under the generalized immersion condition. An advantage of this internal model is that it is zero input globally asymptotically stable. This fact will greatly facilitate the global stabilization of the augmented system associated with the given plant and the internal model. Then we will further utilize this class of internal models to solve the global robust output regulation problem for output feedback systems with a nonlinear exosystem. Copyright © 2011 John Wiley & Sons, Ltd.     

Internal-oxide-band formation during oxidation of Ag-Mg alloys

Ag-3a/oMg was oxidized in air over the range of 400–900°C. Internal-oxide bands of MgO formed approximately parallel to the surface, the first band appearing at some finite, but irregular depth below the surface. The region between the surface and the first band appeared to be free of precipitates, but TEM showed that very small clusters, about 50 Å in diameter, formed in the PFZ, causing significant hardness (greater than 300 VHN). The clusters contain more oxygen than that corresponding to stoichiometric MgO. The hardness between oxide bands was also high, but not as high as in the PFZ. The kinetics of thickening of the internal-band region followed the parabolic rate law between 400 and 700° C, with departures from the parabolic law occurring at higher temperatures. The activation energy for the parabolic rate constants was 19.4 Kcal/mol, a value less than the total for oxygen diffusion and oxygen dissolution. The reaction front was planar and parallel to the surface prior to band formation at temperatures of 400–600° C. Nucleation of the first band resulted in nonplanar and nonparallel oxide. Little or no correlation existed between grain boundaries and oxide formation. Nodules of virtually pure silver formed on the surface initially at grain boundaries and subsequently within grains. Nodule formation is attributed to stress-enhanced (resulting from strains associated with precipitation) diffusion of silver to the surface via dislocation pipes. Internal-band formation is discussed in terms of prior data in the literature and various models. It is thought that stress effects (induced by precipitation), nucleation, and clustering of oxygen with Mg play significant roles in causing internal-band formation.     

应用函数链神经网络测量管道内壁缺陷尺寸

基于图像测量管道内壁缺陷尺寸时,图像上单位像素所代表的实际尺寸与很多因素有关,如摄像机的内部、外部参数以及摄像机到管壁的距离等,是一个复杂的非线性关系。在摄像机参数固定的条件下,采用函数链神经网络来逼近图像上单位像素所代表的实际尺寸与管道内径之间的非线性关系,进而实现了无需标定摄像机参数的管道内壁缺陷尺寸测量。实验结果表明,这种方法具有易于实现、误差小等特点。     

一种三自由度串级控制的仿真研究

关于优化控制系统性能问题,由于控制系统中存在非线性滞后各种干扰因素,严重影响响应和稳定性。为实现在线独立调节副回路设定响应与扰动抑制响应,增强主回路的抗干扰能力,改善系统性能,提出一种新的三自由度串级控制方法。在副回路中采用两自由度内模控制,主回路采用单位反馈控制结构,并根据闭环最优灵敏度函数方法确定主控制器,从而保证系统的整体性能。对各个控制器的解析建模设计,对每个控制器都可以进行单参数调节和优化,并对主回路和副回路存在的乘性不确定性进行仿真。仿真结果表明,新的控制方法具有较好的设定值跟踪性能和抗干扰能力,提高了系统的鲁棒稳定性。     

180kA大型铝电解槽力场测试与分析

阐述了１８０ｋＡ大型铝电解槽槽壳的位移现场测试手段、槽壳表面位移特征和槽壳所受内力的计算方法，并对槽壳结构优化设计做了分析     

Mechanical properties of nano SiO2 filled gypsum particleboard

Nano SiO2 was filled into gypsum particleboard. Effect of the amount of nano SiO2 particles filled, ultrasonic dissipating duration and treating the nano particles with different coupling agents on the mechanical properties of the board were studied respectively. The results show that nano SiO2 is helpful for the improvement of the properties. Adding 3%（mass fraction） nano SiO2 is the best for the improvement of both modulus of rupture（MOR） and modulus of elasticity（MOE） of the boards formed at 30 ℃ or 40 ℃. For the boards formed at 30 ℃, their MOR and MOE can be improved by 8.77% and 12.24%, and MOR and MOE of the boards formed at 40 ℃ can be improved by 44.44% and 108.38%.3% is also the best addition proportion to improve internal bond（IB） of the boards formed at 30 ℃, while 5% is the best for that of the boards formed at 40 ℃. At room temperature, dissipating nano Si02 into flake by ultrasonic has better effect on the properties of the final products. Through ultrasonic treating for 1 h and the best treating duration, the MOR and MOE can be increased by 41.99% and 47.80%. In addition, different coupling agents have different effects on the final properties too, and silane coupling agent KH570 is better for the improvement of properties of the boards formed at room temperature.