In the industrial production, as an important transmission part, the screw thread is applied extensively in many automation equipments. The traditional measurement methods of screw thread parameter, including integrated test methods of multiparameters and the single parameter measurement method, belong to contact measurement method. In practical the contact measurement exists some disadvantages, such as relatively high time cost, introducing easily human error and causing thread damage. In this paper, as a new kind of real-time and non-contact measurement method, a screw thread parameter measurement system based on image processing method is developed to accurately measure the outside diameter, inside diameter, pitch diameter, pitch, thread height and other parameters of screw thread. In the system the industrial camera is employed to acquire the image of screw thread, some image processing methods are used to obtain the image profile of screw thread and a mathematics model is established to compute the parameters. The C++Builder 6.0 is employed as the software development platform to realize the image process and computation of screw thread parameters. For verifying the feasibility of the measurement system, some experiments were carried out and the measurement errors were analyzed. The experiment results show the image measurement system satisfies the measurement requirements and suitable for real-time detection of screw thread parameters mentioned above. Comparing with the traditional methods the system based on image processing method has some advantages, such as, non-contact, easy operation, high measuring accuracy, no work piece damage, fast error analysis and so on. In the industrial production, this measurement system can provide an important reference value for development of similar parameter measurement system.
Sand dust aerosol is the main component of aerosol in troposphere atmosphere of East Asia, which
can produce the extensive influence on the ecosystem, atmosphere environment and atmosphere chemistry
through intensive sand dust weather process. For investigation of the aerosol optical depth (AOD) and its
temporal-spatial evolution over this area, a series of observation experiments were carried out by a sun
photometer CE-318 located at Beifang University of Nationality( 106°E, 38°29'N ), Yinchuan Ningxia
province of China from September 2012 to April 2013 and many direct solar radiation datum were obtained.
The experiments results were analyzed in detail and some conclusions are obtained as follows: (1) For daily
evolution of AOD, the variation trend are divided into four types: ①the AOD values are relatively steady in
whole day; ② the AOD values increase from morning to afternoon; ③ the AOD values are greater at noon
than that in the morning and afternoon; ④there is a peak in the variation trends of AOD from 9:00~12:00 in
the morning, but it is small at other time. (2) For month evolution, the minimum AOD average value appears
in September and the maximum one appears in April. (3) For the seasonal changes trend, the average AOD
values in the April are bigger than that in the autumn. (4) In addition, during the observation period, one dust
weather process was observed and the change characteristic of AOD of dust aerosol was obtained and