刨花板动态抗弯弹性模量的无损检测

利用弯曲振动试验，纵波传播试验，纵波共振试验测定刨花板的动态弯弹性模量，并分析了各所得结果之间的关系，结果表明，不同方法测得的弹性模量值不同，但它们之间存在着一定的内在联系。     

The efficacy of air, sound and acoustic bubble screens in deflecting Atlantic salmon, Salmo salar L., smolts in the River Frome, UK

Atlantic salmon, Salmo salar L., smolts are vulnerable to entrainment in a variety of man-made structures as they migrate downstream. The ability of acoustic bubble screens to deflect smolts from potential hazards was assessed. Screens were deployed, in turn, across one of the two identical channels through which the millstream of the River Frome flowed and the efficiency of these screen systems was tested by counting smolts by video recording in each channel. It was concluded that these screens deflected a significant number of smolts. Efficiencies were greater at night than in daylight because of smolt behaviour.     

林区公路测设中的局部改线与断链

列举实例说明林区公路测设中局部改线的方法，以及由此而产生的断链处理。     

The effect of rotation speed on the power consumption and cutting accuracy of guided circular saw: Experimental measurement and analysis of saw critical and flutter speeds

ABSTRACT

This paper investigates the effect of rotation speed and vibration response of a circular saw on the sawing process of Douglas-fir wood. An idling test was conducted on a guided circular saw to determine its stable operation speeds and vibration behavior. Short-time Fourier transform analysis was performed on saw idling test data, and variation of excited frequencies of the blade as a function of rotation speed was obtained. The saw blade critical speeds and the rotation speeds that correspond to saw flutter instability were identified. Then experimental cutting tests were conducted at different cutting conditions and the effect of rotation speed and saw vibration response on cutting power consumption and sawing accuracy was investigated. The results showed that conducting a saw idling test and vibration response analysis can identify the saw critical and flutter speeds, which is essential for identifying the optimum rotation speed of circular saw. There was a significant increase in power consumption when cutting at super-critical and super-flutter speed. The effect of rotation speed on sawing accuracy is complex and nonlinear. This effect interacts with feed speed, which makes it difficult to generalize sawing accuracy versus rotation speed in the circular sawing process.     

喷雾机器人重喷漏喷问题研究

喷雾机器人在行走过程中由于两驱动电机的不一致性和地面不平整等因素,会偏离航线产生“跑偏”现象,从而造成重喷和漏喷区域。为了解决这一问题,运用模糊控制方法,在机器人偏离预定行驶轨迹时改变两轮的转速,以实时地控制机器人及时调整和消除“跑偏”现象。仿真结果表明,此方法的效果良好。     

A SOLUTION TO THE DEFLECTION OF STEPW1SE BEAM WITH SINGULAR FUNCTION AND LAPLACE'' S TRANSFORMATION

The singular function is combined with Laplace' s transformation to calculate the deflection of stepwise beam. In this way the deflection equation of the beam is conveniently determined. This method is suited for both statically determinate and indeterminete stepwise beams and can simplify the calculation.     

Analysis on the Illumination and Contrast of Imaging Deflection Measuring System

The principle of photoelectric imaging deflection measurement system are presented. The calculation of the image plane's illuminance and contrast are discussed. The relationship among the system's parameters are analyzed. The feasibility of high reflectivital material replacing the system's source are also discussed when illuminance on the ground is high. The result contributes to selecting the parameters of photoelectric imaging deflection measurement system and achieves the long online of deflection.     

AREA-VECTOR METHOD CALCULATJJNG THE DISPLACEMENTS OF BEAMS AND FRAMES

A new method with which to calculat the displacements of beams and frames is presented. The areas of tending moment diagram of beam or frame and the slope at the origin of the elastic curve are treated as some rotatable vectors with this method. Angular displacement and in-line displacement can be calculated by using the projection and moment of these vectors. This method can be used to calculate displacement of the bar and the bar syttem ( including three dimensional forms. ) , which made from linear or ncnlinear elastic materials. The cross section of the bar is changeable.     

小变形条件下竹胶合板弯曲力学特性研究

对小变形条件下竹席竹帘胶舍板的弯曲力学特性进行研究,构建了竹席竹帘胶合板纵、横向载荷与应力、应变及挠度之间关系的数学模型,与实际数据拟合较好.这对解决竹席竹帘胶合板在实际应用中的弯曲变形问题具有一定的指导作用,也为深入研究竹席竹帘胶合板的力学特性提供了一定的实验基础.     

索道大挠度与小挠度分界的研究

本文论证抛物线算法挠度的最大误差在上支点,在此基础上讨论索道大挠度与小挠度的分界限,提出应根据索道的倾角分别确定大小挠度界限的观点。