基于mRMR-GRU的变速恒频风电机组图像识别算法

为了精准识别变速恒频风电机组的运行状态,提出基于mRMR-GRU的变速恒频风电机组图像识别算法。通过分析变速恒频风电机组机械动态结构,获取整体变速恒频风电机组运行的重要控制部分;基于物联网技术,集成智能终端传感设备在特定结构中采集变速恒频风电机组图像;分析风电机组特定结构,生成变速恒频风电机组原始图像;基于直方图均衡方法对变速恒频风电机组图像进行增强处理,输出高分辨率采集图像;基于mRMR算法,定义特征变量的互信息,获得最具代表性和相关性的特征子集;融合GRU单元与mRMR值生成mRMR-GRU算法,优化图像识别网络结构,输出的风机图像状态识别结果。实验结果表明:设计算法MAPE值为4.46,RMSE值为3.57,图像识别准确度最高值为0.98,能够有效调节图像的特征变量,有效识别变速恒频风电机组图像存在的异常情况,且具有明显的图像像素点均衡效果与图像增强识别效果。

机械结构动态优化设计及其相关技术

在科学技术发展带动作用下,机械产品更新速度也在不断的提升。企业为了增强自身市场竞争实力,提高市场占有份额,不断的进行产品质量优化研究,加快产品设计速度,在这种竞争激励的背景下,动态优化设计应运而生。所谓的机械结构动态优化设计就是将工程设计同数学理论进行一定的融合,并以此为基础寻找最优化的设计方案。工程设计与数学理论的结合一方面加快了研发的速度,另一方面对产品质量的提升也有积极的影响。文章将对机械结构动态优化设计的相关内容进行阐述,并对与其相关的技术应用进行分析,已为今后参考使用。

A CASE STUDY ON CONCENTRATION AND DECENTRALIZATION:BEHAVIOR AND DYN AMIC MECHANISM OF SPATIAL EVOLUTION IN METROPOLITAN AREA,NANJING,CHINA

In rapid socio-economic developme nt,the process of concentration and dispersal of various elements tends to be more dramatic,tremendously in fluencing the shaping and transform ation of the space in metropolitan area.Survey of spatial concentration and decent ralization has thus become a basic me thod in examining metropolitan spatial evolution.In this research,three elements were selected as the essential indicato rs of the process:demographic density distribu-tion,employment density distribut ion and business office location.Performance of these elements in Nanji ng City was exam-ined historically.As Nanjing City c ould be regarded as a representative of metropolitan areas in China,its s ituation large-ly suggestes the general characteristics in similar areas of China.Hence based on the investigation of Nanji ng City,four general implications were highligh ted.First,metropolitan areas inChina are in a violentprocess and shift of spatialconcentra-tion and decentralization.Second,from now to at least the near future,c oncentration will continue to be the central fea-ture.Third,the landscape of metrop olitan areas basically exhibits a dual structure character.The gap in en vironmental and ecological qualities among different districts will continue for a l ong time.Fourth,Central Business District(CBD)is playing an important role in helpi ng to convert the traditionally single-centered city structure into a polycentric one.

Finite element analysis of dynamic response and structure borne noise of gearbox

A dynamic finite element method combined with finite element mixed formula for contact problem is used to analyze the dynamic characteristics of gear system. Considering the stiffness excitation, error excitation and meshing shock excitation, the dynamic finite element model is established for the entire gear system which includes gears, shafts, bearings and gearbox housing. By the software of I-DEAS, the natural frequency, normal mode, dynamic time-domain response, frequency-domain response and one-third octave velocity grade structure borne noise of gear system are studied by the method of theoretical modal analysis and dynamic response analysis. The maximum values of vibration and structure borne noise are occurred at the mesh frequency of output grade gearing.

Dynamic deformation behavior of a face-centered cubic FeCoNiCrMn high-entropy alloy

In this study, mechanical tests were conducted oil a face-centered cubic FeCoNiCrMn high-entropy alloy, both in tension and compression, in a wide range of strain rates （10^-4-10^4 s^-1） to systematically investigate its dynamic response and underlying deformation mechanism. Materials with different grain sizes were tested to understand the effect of grain size, thus grain boundary volume, on the mechanical prop-erties. Microstructures of various samples both before and after deformation were examined using elec-tron backscatter diffraction and transmission electron microscopy. The dislocation structure as well as deformation-induced twins were analyzed and correlated with the measured mechanical properties. Plastic stability during tension of the current high-entropy alloy （HEA）, in particular, at dynamic strain rates, was discussed in lights of strain-rate sensitivity and work hardening rate. It was found that, under dynamic conditions, the strength and uniform ductility increased simultaneously as a result of the mas-sive formation of deformation twins. Specifically, an ultimate tensile strength of 734 MPa and uniform elongation of-63% are obtained at 2.3×10^3 s^-1, indicating that the alloy has great potential for energy absorption upon impact loading.

Experimental investigation on dynamic mechanical characteristics and microstructure of steam-cured concrete

Steam-cured concrete is widely used to manufacture prefabricated units of high-speed railway foundation structure such as girder and track slab.The dynamic mechanical property of steam-cured concrete is one of the key properties affecting service performance of high-speed railway foundation structure.In the present paper,serial macro/micro-experiments were carried out to investigate the dynamic elastic modulus,shear modulus,damping ratio,and microstructure of steam-cured concrete.The relationships between compositions,curing regime,microstructure,and dynamic properties of steam-cured concrete as well as the corresponding mechanisms were discussed.The results indicate that steam-cured concrete in early age has a larger dynamic elastic modulus and shear modulus as well as a smaller damping ratio compared with standard-cured concrete.On the contrary,at a later age a slightly smaller dynamic elastic modulus and a larger damping ratio of steam-cured concrete are observed.Addition of mineral admixture results in a bit lower dynamic elastic modulus and damping ratio of concrete than that of the control specimen without mineral admixtures.The achievements can provide some fundamental suggestions for materials parameters selection during structural design of steam-cured concrete precast element.