液压机械复合传动阶跃输入恒转速输出双前馈模糊PID控制

针对液压机械复合传动系统在阶跃转速输入时输出转速稳定性差、不易控制等问题,该文提出了一种基于液压子系统、机械子系统和液压机械复合传动系统的输入双前馈+模糊PID转速复合控制方法,以系统输出转速恒定为控制目标,将2个子系统转速扰动量折算到变量马达转速变化量,通过排量补偿调节实现对系统输出转速波动控制,最终实现输出转速恒定控制。仿真与试验结果表明:在系统不同初始输入转速基础上,施加特定的阶跃转速扰动,该控制方法具有良好的控制精度和鲁棒性,相比于传统PID控制方法,系统输出转速最大超调量平均降低39.8%,稳定调整时间平均缩短35.53%,系统输出转速平均稳态误差控制在±0.7%之间。该文所提出的双前馈+模糊PID转速复合控制方法,对液压机械复合传动系统阶跃输入扰动引起的输出波动具有抑制作用,控制效果明显,增强系统在非线性输入复杂工况下转速输出的稳定性,可为液压机械复合传动系统在农业机械领域的设计和应用提供参考。     

Light-microscopy evaluation of zonular fiber morphology in dogs with glaucoma: secondary to lens displacement

Lens displacement resulting in secondary glaucoma is common in terrier breeds. This study was carried out to evaluate whether light microscopy was useful in detecting abnormal patterns in zonular fiber protein. Eyes from 63 dogs with glaucoma secondary to lens displacement were evaluated for the presence of abnormal zonular fiber morphology using the following stains: hematoxylin and eosin, periodic acid Schiff (PAS), Masson's trichrome and Verhoeff's elastin stains. Two distinct forms of abnormal zonular fiber morphology were recognized and designated as zonular fiber dysplasia (ZFD) and zonular fiber collagenization (ZFC). ZFD protein morphology was characterized by being tightly adherent to the nonpigmented ciliary body epithelium, exhibiting a distinct lamellar and cross-hatched pattern and staining strongly positive with PAS and trichrome stains, and staining negative with elastin stains. ZFD was predominant in terrier breeds (18 of 29) and Shar-Pei dogs (4 of 29). ZFC abnormality was characterized by excessive zonular fiber that was not tightly adherent to the ciliary body epithelium and staining positive with PAS, trichrome (blue for collagen) and elastin stains. Only 7 of 19 dogs with ZFC changes were terrier breeds, and there was no pattern in the breeds affected. Fifteen of the 63 dogs used in the study had normal appearing zonular fibers. The staining pattern in these dogs matched normal controls by staining positive with PAS and Verhoeff's elastin stains and had only minimal positive staining with Masson's trichrome stain. Results suggest that light microscopy is useful in detecting breed-related changes in zonular fiber morphology in cases of glaucoma secondary to lens displacement. These changes may correlate with the presence of abnormal zonular fiber proteins and might be important in the pathogenesis of primary lens displacement in terrier and Shar-Pei dogs.     

Comparison Analysis of Calculation Methods of Seismic Displacement for the Isolation System Based on Pure Rolling

With the isolation system based on pure rolling as the object of study, the computer program was develeped to calculate its seismic displacement based on its characteristics. And then, experiment method and theory analysis method were adopted to analyze the new computer program and the traditional calculation method’s rationality in contrast. It is shown that the computer program is reasonable, and its results are relatively accurate and conservative. The traditional calculation method based on the rigid-plastic relation of force and displacement is illogical, and its results are relatively small. When subjected to earthquakes, the structures maximum relative displacement would be larger than the earths maximum absolute displacement.     

Experimental Analysis of Extension Length of Shape Steel in SRC-RC Transfer Column

Seismic performance of SRC-RC transfer column was analyzed based on experiment of 12 specimens of transfer columns and 1 RC specimen under low cyclic reversed loading, which mainly focused on the extension length of shape steel. Analysis and comparison on skeleton curves of specimens was carried out. Analysis was completed for ductility, bearing capacity, energy dissipation capacity and degeneration ratio of strength. Displacement ductility changes with the increase of extension length of shape steel, enhancing at first, then reducing, and reaching peak value when extension length is close to three fifths of column height. Extension length of shape steel has little effect on bearing capacity. Energy dissipation capacity of transfer columns has relationship with many factors. Three fifths of column height is rational for extension length of shape steel, and specimens have not only advanced performance of energy dissipation but also good stability of stiffness and strength in this condition. The bond performance between concrete and shape steel decreases with the increment of extension length of shape steel, and hence stability of strength decreases.     

An improved localization algorithm based on RSSI for landslide monitoring

In order to overcome the existing problems of low automation, high cost and difficult to implement in the area of landslide monitoring, this paper presents a new method of RSSI (Received Signal Strength Indicator)based positioning technology without any one-off instruments to monitor landslide surface displacement. By adding weighted factors, the improved positioning algorithm can estimate the parameters of the path loss model dynamically and calculates the communication distance of network nodes in real-time, which can improve positioning precision and reduce the impact of environmental changes on it. The MATLAB experiments show that, compared with the traditional RSSI based localization algorithm using fixed pass loss model, the improved algorithm could significantly reduce the average error.     

扰动状态概念模型在三峡大坝3#坝段稳定性分析中的应用

采用扰动状态概念模型分析三峡大坝3#坝段的稳定性.材料的本构模型采用扰动状态概念本构模型,其中岩石和混凝土的模型参数可根据所提供的材料基本参数及单向压缩试验和常规三轴压缩试验求得;而断层的扰动状态概念模型参数则根据位移反分析法反演,反演时采用遗传算法进行优化.分析大坝稳定性时,采用强度储备法进行追踪计算,采用VC 与Matlab混合编程的方法编制了三维有限元程序进行数值计算,把控制点位移出现拐点确定为坝段的抗滑安全系数,以此得到合理的安全系数.     

Solving Method for Soil Spring Stiffness of Shallow Shield Tunneling

Based on complex variable theory in plane elasticity, the equivalent spring stiffness is derived from the analytical solution by means of simplifying shallow shield tunneling to semi-infinite plane with hole, which is applied to response displacement method. The performances of the analytical solution are evaluated and compared with that of the deep shield tunneling through a series of selected various tunnel depths and soil Poisson's ratios. The relation of compression and shear spring stiffness is discussed. Meanwhile, two factors affected soil spring stiffness, tunnel depth and soil Poisson's ratio, are also analyzed. It is shown that soil spring stiffness of shallow shield tunneling is different from that of deep shield tunneling, and the ratio of compression and shear spring stiffness varies along shallow shield tunneling. It is also found that the value and distribution law of soil spring stiffness of shallow shield tunneling greatly depend on tunnel depth and soil Poisson's ratio.     

Radiographic and radiological assessment of laminitis

Radiographic studies are an essential component in evaluation of horses with laminitis. The standard radiographs that should be obtained to aid assessment of horses with laminitis are the lateromedial, horizontal dorsopalmar and dorsal 45° proximal palmarodistal oblique views. This article will summarise the assessment of these 3 projections in the laminitic horse as well as discuss the prognostic significance of common radiological abnormalities in horses with laminitis.     

Case series: Persistent dorsal displacement of the soft palate in eight horses

Persistent dorsal displacement of the soft palate (pDDSP) is a relatively rare equine disorder. This case series reports histories and clinical findings in 8 cases of pDDSP, and outcome after treatment of concurrent epiglottic entrapment (n = 3), laryngeal tie‐forward (n = 6) ± laser staphylectomy (n = 2), and/or sectioning of mucosa ventral to the epiglottis and the hyoepiglotticus muscles (n = 2). Four of 6 horses that underwent tie‐forward ± laser staphylectomy had complete resolution of pDDSP and returned to their previous level of work, as did one horse that had a subepiglottic releasing incision. Correction of concurrent epiglottic entrapment in 3 horses with pDDSP did not result in resolution of pDDSP in any case. Previous laryngeal surgery including laryngoplasty and ventriculocordectomy appear to be risk factors for the development of pDDSP.     

Study on the Iterative Methods in the Nonlinear Full_RangeAnalysis of Concrete Structures

Based on the extensive study of various iterative methods, a simple but practical way of the iterative route search and acceleration is introduced into the normal displacement and arc-length methods to fit the nonlinear full-range analysis of concrete structures, by which the convergence of iteration is much improved.