Advanced Materials Research Vol. 339

Abstract: With the development of precision guidance ammunitions, more and more parachutes are used for controlling speed and adjusting posture. At the same time, this will increase the complexity of movement for bomb with parachute. This paper created a simulating model of trajectory for bomb with parachute under low altitude condition. By the comparative study on theoretical trajectory and testing, it can determine the parameters and firing table, and it’s very useful for aircraft ammunition on research and development.

Abstract: To obtain more detailed and accurate pore size distribution for cotton fabric, this paper focuses on comparing size distribution between the yarn and fabric. The result shows that there are great difference as well as relationship in size distribution between the yarn and fabric. The size in fabric has 2 orders of magnitude including that in yarn with just 1 order of magnitude. The pore size ratio data also illustrate that the pore in yarn account for 33.3% of that in fabric, suggesting that the pore in yarn has a certain impact on the wicking behavior of fabric. However, the graphic exhibit that the size distribution shape in yarn is different from that in fabric, which may be owing to the fabric weaving configuration, implying that wicking liquid movement is affected not just by capillary effect along the yarn but also by interlacing points and fluid-wall interaction in the complex channels of fabric.

Abstract: License plate holds the very small proportion in the whole vehicle image, and the color, size and location for License plate is also uncertain. Fast and accurate localization for license plate is a difficult problem in the license plate recognition process. This paper presents a geometry license plate localization method based on machine vision. This method has very good compatibility to the gradation linear and nonlinear change, moreover support criterion and angle change. Experimental results indicate that the localization deviation does not surpass 1.0pixel and the angular deviation does not surpass 1.0 degrees under same level test condition. Robustness of this localization is basic consistent with Cognex Visionpro. The license plate localization can adapt the low signal-to-noise ratio, the low contrast gradient, the fuzzy situations and so on., which is also simple, practical and is better than traditional zone location and edge localization method.

Abstract: Virtual methods to assess the fitting of a fracture fixation plate were proposed recently, however with limitations such as simplified fit criteria or manual data processing. This study aims to automate a fit analysis procedure using clinical-based criteria, and then to analyse the results further for borderline fit cases. Three dimensional (3D) models of 45 bones and of a precontoured distal tibial plate were utilized to assess the fitting of the plate automatically. A Matlab program was developed to automatically measure the shortest distance between the bone and the plate at three regions of interest and a plate-bone angle. The measured values including the fit assessment results were recorded in a spreadsheet as part of the batch-process routine. An automated fit analysis procedure will enable the processing of larger bone datasets in a significantly shorter time, which will provide more representative data of the target population for plate shape design and validation. As a result, better fitting plates can be manufactured and made available to surgeons, thereby reducing the risk and cost associated with complications or corrective procedures. This in turn, is expected to translate into improving patients' quality of life.

Abstract: Aiming at life prediction for aircraft components, the life distribution types and the parameter estimation methods were introduced, then a method using grey relational analysis to determine the type of the life distribution was proposed, from which can calculate the remaining life. In this paper, the typical aircraft components were taken as an example to demonstrate the feasibility of the method. It has some certain reference value in the maintenance decision-making.

Abstract: testing stand that is able to imitate the vibration of seeder field surface stirred up is designed to analyse the effect of vibration on the seed metering function of pneumatic seeder. The signal of vibration data is collected by tape recorder on the testing spot in testing process and then the vibration signal is analysed. A conclusion is reached based on the analysis of testing result that: the trait vibration of seeder is an approximate periodic function, which may be approximately simulated with sine exciting signal; the trait vibration frequency of seeder ranges form 0 to 68 Hz, the maximum acceleration of vibration makes 25m/s², and the minimum excited vibration thrust of vibration exciter is 500N. A testing stand for seed metering is designed by taking these parameters as the criterion to simulate field surface excited vibration and analyse the seed metering dynamic characteristic of seed metering device.

Abstract: Italic textAbstract. Industrial Streptomyces avermitilis were irradiated by 80 MeV/u ¹²C⁶⁺ ions whith were provided by the Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou Heavy Ion Accelerator. The high titers of mutants were obtained with different doses. The original strains and the high titers of mutants were detected and analyzed by Random Amplified Polymorphic DNA technology (RAPD). The results show that bands could be got from amplify the original strain by 4 primers of 28 primers and the high titers of mutants were amplified by the 4 primers. The amplified products were analysed by Jaccard formula. After 10 Gy, 30 Gy, 40 Gy, 45 Gy, 50 Gy, 70 Gy isodose irradiation, the similarity index were 0.63, 0.75, 0.71, 0.8, 0.61, 0.73. It was confirmed that at the DNA level, not only the high titers strains and the original mutant strain’s DNA were different, but also the high titers of the different mutants’ DNA were different. Therefore, ion implantation method changed the different Streptomyces avermitilis genetic material which promote the importance trace of avermectin biosynthesis changed, and different high titers of Streptomyces avermitilis were obtained.

Abstract: In order to explore the zoobenthos community composition and the status of water quality in Songhua River in Harbin city, we conducted an investigation on the zoobenthos community structure in spring, summer and autumn 2008. The results showed that 60 species of zoobenthos were found totally, of which 39 species were aquatic insect Larvae, 13 species of mollusks, 7 species of annelid, 7 species of crustacean. Density variation in the scope of 26.67-3521.67 ind./m², biomass variation in the scope of 0.14-549.89g/m². And assessed water quality using the physic-chemical and biological methods, the results showed that water quality of Songhua River in Harbin city was in moderate-severe pollution state.

Abstract: To obtain detailed micron-scaled pore size distribution for cotton-polyester fabric (CPF), this study focus on the influence of wicking liquid properties on size distribution with three kinds of wicking liquid. For three kinds of wicking liquid, the paper reveal that it is difficult to fully characterize the specific pore size distribution with only one wicking liquid. The results illustrate that the surface tension has a significant impact on the pore size distribution as well as mean pore size. It is found that the whole graphics shift towards the large pore size direction and even result in the disappearance of smaller pore size with decreasing the surface tension and with increasing viscosity. The emergence of larger pore size, instead of smaller one, may be due to the wetting expansion by larger viscosity liquid. Meanwhile, it is obvious that the pore in peak area become dominant, accounting for more than 75%.

Abstract: The aim of this study is to determine the appropriate solution treatment temperature and time of semi solid 2024 Al alloy. Solution heat treatment at 450°C and 480 °C for various times, from 4 hours to 16 hrs, were applied followed by artificial aging at 220 °C for 1 hr. Microstructure of the semi solid cast 2024 aluminum alloy mainly showed globular grain structure which consisted of matrix-α (Al) and grain boundary (GB) - eutectic phases (α+Al₂CuMg/Al₂Cu). Eutectic GB phases was found to completely dissolved after solution heat treatment at 480°C for 14 hrs while sample solution treated at 450°C for the same time showed the existence of remaining GB phases. Prolonging heat treatment after 14 hrs at both temperatures resulted in the formation of coarse black particles at the grain boundaries which were identified as Mg₂Si phases. Therefore the suitable solution treatment of the alloy in this study was at 480°C for 14 hrs.