Automatic feature extraction algorithm for porphyrin sensor array images

A feature extraction algorithm for porphyrin sensor array (PSA) images is presented. At the first step, it achieves an automatic tilt correction for PSA images based on radon transform. Then automatic mesh generation is applied to PSA images based on the method of combining projection binarization and mathematical statistics. The areas of porphyrin spots are locating by local threshold segmentation for the images which have achieved mesh generation. Finally, feature values of porphyrin spots are extracted by radius ratio method from the porphyrin spot areas. The algorithm solves the problem that identification of weak signal spots is quite difficult, and the extracted feature values are the maximum point to reflect the information of porphyrin spots. By ammonia, isoprene, aldehydes and other gases tests, the results show that the algorithm can effectively extract feature values of porphyrin spots in PSA images.     

榆木顺纹压缩弯曲技术

木材从力学角度上看是一种粘弹性材料 ,从结构上看又是一种多孔材料 ,木材的这个特性 ,可以使其进行简单的弯曲 ,但是要获得较小的弯曲曲率半径 ,首先应强化木材软化机理的研究 ,增大木材的塑性 ;其次研究木材软化处理后的顺纹压缩机理和压缩技术 ,使木材在顺纹压力的作用下 ,细胞壁中微纤丝之间产生滑移 ,导致木材细胞壁的壁层纵向产生褶皱 ,木材在弯曲力矩的作用下 ,弯曲时的受压面形成褶皱 ,受拉面形成展皱 ,在允许的形变范围内获得较小的弯曲曲率半径。本文研究结果表明 ,试件尺寸为 2 80mm× 1 6 5mm× 1 6 6mm时 ,经过水热软化处理后 ,顺纹压缩率达到 2 4 % ,试件回弹后的长度最小为 2 6 1 74mm时 ,弯曲的曲率半径最小为 4 2 5mm ,测试的试件平均值为 5 6 94mm。     

简单离子晶体离子半径比的计算

介绍了关于简单离子晶体中离子半径比的计算方法,给出了一个适用于各种类型简单离子晶体的一般公式,具有简便直观,易掌握之优点.     

Flow resistance and hydraulic capacity of water courses with aquatic weed growth. Part 2

The flow resistance is generally derived from fieldmeasurements, using the total wetted area of the cross-section.Less attention has been paid to the aquatic weed growth stageand often different resistance have been derived. In this paperthe flow resistance required in the Manning formula wascalculated from laboratory experiments and field data. A goodsolution appeared to be using the unobstructed part of the cross-section only and excluding the part covered by weeds. Apractical solution was found using the relative weed obstructionin the water courses to represent the weed growth. Weedobstruction was measured throughout the growing season. Thedata were obtained from water courses without any weedcontrol and also in sections where weeds were cleared twiceduring the growing season.     

Algorithm of Circle Analyse in Image Processing

To detect circles fast and correctly has wide application prospect in the field of computer vision and automatic inspection. The conventional Hough transform has the limitation of using too much computation and memory space, and restricted extracting parameter. Aiming at this problem, the authors bring forward a new detection method in allusion to the real-time requirement of detecting circle in simple, image. When the image does not intersect each other, they transform the image into binary image and then perform edge detection to it. After that the chain code of the image is acquired. Basing on that, the circularity of the image and radius of the circle more quickly are calculated and a satisfactory result is gotten.     

A PRELIMINARY STUDY ON THE FRACTAL DEMENSIONS OF LIME SAND CONCRETE

Fractal geometry is a branch of applied mathmatics in 1975,and it is used to describe the surface character of irregular bodies. This paper applies fractal demension to study the micropores structures of lime sand concrete,and concludes that it can be used to describe the microp-ores. Their radii are less than 100A. The fractal demensions of lime sand concrete are measured by MlP(mean indicated pressure) technique. The results have shown that the stronger the autoclaving schedules,the less the fractal demensions of lime sand concrete;the larger the water solid ratio(W/S),the larger the fractal demensions,and the calcium silicate ratio(C/S) has the effect on the fractal demensions of lime sand concrete. A pore structure parameter, mean pore radius is also proposed.     

Verification of impermeable barrier depth and effective radius for drain spacing using exact solution of the steady state flow to drains

The steady-state drainage equation ofHooghoudt (1940) has adrawback that tables for the determination of the so-calledequivalentlayer, d_e are needed. These calculations arecumbersome as d_e is dependenton the unknown spacing. Moreover, additional head islost due to theconvergence of stream lines towards the finite numberof perforations withinthe pipe wall. Therefore, corrections are required byreplacing the actualdrain radius by its effective radius. The designers inEgypt assume that thedepth of impermeable layer is infinity which resultsin an over estimationof drain spacing that will affect the ability of thedrainage system.Van der Molen and Wesseling (1991) have developed aseries solution toreplace the Hooghoudts approximation method for theequivalent depth by anexact solution. A comparison between this solution andthose of Lovell andYoungs (1984) and Hooghoudt (1940) showed that theexact solution proved tobe very accurate and efficient solution. The mainobjective of this study isto verify an accurate depth of the impermeable barrierand an effectiveradius of drain pipes which should be used in thedesign process using theexact solution.A field investigation was conducted in a study area of33,138 ha in theNorthern Delta of Egypt within Daqahliya Governorate.The results indicatethat a 5 m depth instead of infinity for theimpermeable layer in Nile Deltaand an effective radius of 90 mm should be used in thedesign process. Theuse of the exact solution for equivalent depth is acrucial issue especiallywith the high rate of on-going drainage projects inEgypt.     

园艺型耕耘机刀辊半径设计方法的研究

 刀辊半径是耕耘机设计中的一个基本的设计参数。提出耕耘机的刀辊半径设计的两种方法,并比较了它们的特点,最后针对园艺型耕耘机独特的结构和工作原理,确定最短切土长度时功耗最低理论为设计耕耘机刀辊半径的合理方法。     

变射程喷头在坡地喷灌中的应用

传统单喷头在坡地上进行喷灌时,水量分布会发生改变。为提高坡地上喷洒均匀性,采用一种压力/流量调节装置与20型全射流喷头结合,使上坡射程增大,下坡射程减小,从而改善坡地上单喷头的水量分布。根据喷头的旋转均匀性满足行业标准要求,平地喷洒形成的射程差符合上、下坡射程差的要求,以及调节装置形成的压力损失不能太大三个约束条件,对调节装置的关键尺寸,调节片基本开孔半径进行了优化,结果表明半径选择3 mm合适。坡地上径向水量分布以及射程的试验数据表明,这种变射程喷头适合大约10°坡度的调节,具有改善水量分布的作用,在坡地组合喷灌中具有优势。     

Theoretical Analysis and Numerical Simulation of Variable Curvature Friction Pendulum Isolation Bearing

The basic structure of Variable Curvature Friction Pendulum Isolation Bearing (VCFP) is introduced. Based on the principle of mechanical equilibrium, theoretical analysis on two types of VCFP which are Variable Frequency Pendulum Isolation Bearing (VFPI) and Conical Friction Pendulum Bearing (CFPI) are conducted. The stiffness of each VCFP is derived, and the recovery characteristics were discussed and the computing formula of maximum residual displacement was deduced as well. Moreover, with the use of ABAQUS software, the models with solid element of each VCFP are built, and the hysteresis property under low cyclic loading and recovery characteristic are simulated. The comparative analysis of VCFP and Friction Pendulum Bearing (FPB) are also conducted. The results show that: 1) the numerical simulation results are identical to the theoretical analysis; 2) according to its plump hysteresis loops, the hysteresis property of VCFP is favorable, further more, its effective viscous damping ratio and coefficient of energy dissipation are higher than FPB, which indicates its greater ability in energy dissipation; 3) the stiffness of the VCFP is determined by curvature radius, that is, sliding surface function. And its stiffness decreases with the increase of bearing displacement through rational design. And then its isolation period increases as the displacement increases and the low frequency resonance problem of isolated structures can be well solved; 4) compared with FPB, the softening mechanism of stiffness can make the shear force transferred to superstructure decrease; 5) the maximum stress of bearing appears when the bearing reaches its designed displacement, and in general it may situate in the edge of ball joint surface of slider or bearing plate 6) the maximum residual displacement of VCFP depends on both friction coefficient and the parameters of sliding surface function, therefore, parametric design based on analysis or simulation is necessary so as to control the maximum value in an acceptable range in engineering.