电弧超声焊缝跟踪的试验研究

利用声发射探头接收的电弧超声信号进行焊缝跟踪检测。结果表明：对称位置接收到的声发射信号的相位差和幅值差可以作为电弧超声焊缝跟踪的依据。     

Electric contacts inspection using machine vision

Machine vision is an excellent tool for inspecting a variety of industrial items such as textiles, printed circuit boards, electric components, labels, integrated circuits (IC), machine tools and fruits. In this paper, we propose machine vision-based inspection system for electric contact (EC), which are popularly used in switches, breakers and relays, and are important components in the electrical industry. The proposed system consists of three sub-systems, which inspect the top, side, and bottom surfaces of electric contact for different types of defects respectively. The system acquires the digital image of three views and classifies the surface defects including cracks, breaks, and scratches. For each view, this study develops different image pre-processing and feature extraction methods to enhance and detect the surface defects. The proposed system was implemented and verified using 229 samples collected from the EC production lines. Experimental results show the proposed system is effective and efficient in identifying EC defects.     

Intelligent maintenance prediction system for LED wafer testing machine

Achieving high quality production of light-emitting diode (LED) wafers requires robust monitoring and the use of a stable test machine. In many factories, production continues 24 h a day. Stopping the manufacturing process at a factory is often difficult. Therefore, reducing inspection time and ensuring the stability of test machines are important. Traditionally, LED wafer factories examine their test machines during periodic maintenance. Standard lamp adjustments are performed to ensure their accuracy. This process interrupts the manufacturing process and requires extra manpower. It reduces productivity and increases production cost. Additionally, the accurate assessment of the aging of the components of the machine requires an experienced engineer. Correctly timing the maintenance and replacing the aging components of the LED wafer test machine are important. This work performed feature extraction to identify the working attributes of an LED wafer test machine. The intelligent maintenance prediction system then uses the radial basis function neural network and variability of the working attributes to predict the maintenance times and aging of the LED wafer test machines. Experimental results reveal that the accuracy of proposed system in predicting maintenance times exceeds 98 %.     

Optimized Heat Treatment Enhances the Anti-Inflammatory Capacity of Ginger

This study aims to investigate the relationship between constituent contents and anti-inflammatory activities of heat processed gingers, and to optimize heat process to enhance ginger’s anti-inflammatory capacity. After 3 h of heat treatment at 75, 100, and 125°C, the gingerols content was reduced by 6.8, 12.6, and 42.7%, respectively, and the shogaols content was increased by 2.95, 4.85, and 9.34 fold, respectively. After 3 h of heat treatment at 150°C, the gingerols content was dramatically reduced by 89.5% and the increased shogaols content was even lower than treatment at 125°C. The tumor necrosis factor-α-, prostaglandin E2, and nitric oxide-inhibitory capacities of ginger could be increased by heat treatment. However, at high temperature, the enhanced ability would be decreased. The enhanced tumor necrosis factor-α-, prostaglandin E2-, and nitric oxide-inhibitory capacities of ginger was attenuated after 40, 60, and 180 min of heat treatment at 150°C, respectively. The results indicated that the TNF-α-inhibitory capacity of ginger was the most susceptible to heat. Only the prostaglandin E2-inhibitory capacity correlated with the shogaols content, which implies that heat derived shogaols contributed primarily to the prostaglandin E2-inhibitory capacity enhancement. We suggest that the optimal heat process condition is 125°C for 40–60 min for ginger to reach the maximum tumor necrosis factor-α-, prostaglandin E2-, and nitric oxide-inhibitory capacities.     

Effects of some Chinese medicinal plant extracts on five different fungi

Chinese medicinal plant extracts were screened against some fungal strains, such as Aspergillus niger, Botrytis cinerea, Fusarium moniliforme, Glomerella cingulata, and Phyllosticta caricae. Plants were extracted with hot water, 80% methanol or acetone. Aliquots of the extracts at variable concentrations were then incubated with different fungal strains, and the minimum inhibitory concentrations (MICs) of each plant extract determined. In this study, the methanol extracts of Cinnamomum cassia had MIC values of 13.3 mg ml⁻¹, when tested against F. moniliforme and P. caricae. The acetone extracts of C. cassia had MIC values of 8.3 mg ml⁻¹ and 10 mg ml⁻¹ respectively, when tested against B. cinerea and G. cingulata. The hot water extracts of C. cassia inhibited significantly the growth of A. niger, B. cinerea, F. moniliforme, and P. caricae with MIC values at 10, 11.7, 5, and 6.7 mg ml⁻¹ respectively. The acetone extracts of Curcuma longa inhibited effectively P. caricae with the MIC value at 6.7 mg ml⁻¹. To determine the stability, various plant extracts were stored at 4 and 25 °C over a period of one month and their effects on fungal growth examined. Results show that the acetone extracts of Cu. longa and Coptidis rhizoma maintained their activity against fungal strains when stored at 4 °C, but not at 25 °C. The methanol extracts of C. cassia lost a great portion of inhibitory activities but not all, after stored at 4 °C and 25 °C for one month. The effect of various combinations of these extracts on antimicrobial activity has also been examined. The combinations of herb extracts showed higher inhibitory effect towards tested fungi than that of individual extract. Results from these findings suggest that these herbal extracts may be used as natural antifungal agents to inhibit growth of foodborne pathogen.     

Φ6M赤道式射电望远镜控制系统

本系统已运行于Φ6M厘米波赤道式射电望远镜。这里给出其设计思想及研制方法。     

Comparison of Peroxynitrite-Scavenging Capacities of Several Citrus Fruit Peels

Citrus fruit peels contain a large variety of bioactive components and are considered as potential sources of functional components. The purpose of this study was to evaluate the peroxynitrite-scavenging activities of different citrus fruit peels. The peroxynitrite-scavenging activities of methanolic extracts of nine dried citrus fruit peels were evaluated as determined by their ability to attenuate the peroxynitrite-mediated nitrotyrosine formation in albumin. The results showed that all of the tested citrus fruit peels had the ability to attenuate the formation of nitrotyrosine. The total phenolics contents highly correlated with the peroxynitrite-scavenging activities. The results also indicated that the peroxynitrite-scavenging activity of citrus fruit peels was mainly attributed to the total phenolics.     

System dynamics model of high-power LED luminaire

Optical properties of LEDs are sensitive to junction temperature. From the principle of solid-state lighting, the luminance of LED is induced from two physical mechanisms: energy effect and optoelectronic effect. Both effects are related to junction temperature. The understanding of system dynamic behavior in junction temperature is quite important for lighting control design.The system dynamics model of a high-power LED fixture for energy effect was derived and identified in the present study using step response method. Both theoretical and experimental analyses have shown that the thermal system dynamics model of the LED fixture is 4th-order with three zeros and can be reduced to a first-order biproper system. The instantaneous jump of junction temperature dominates the thermal behavior of LED at the beginning of the step input. The optoelectronic effect was induced mainly from the current input and the junction temperature. Combining the two physical effects, an electric-heat-optical system dynamics model of LED luminaire was finally proposed which is the basic system dynamics model for LED luminance control.     

基于小波系数块的运动补偿

提出基于小波系数块的运动补偿算法.所谓小波系数块是指图像的部分小波系数,它们只与图像的某个局部相关.该文提出的算法先在时空域进行运动估计,得到预测块的运动矢量.然后利用小波系数的局部空频特性,在小波变换域用参考块的小波系数块对预测块的小波系数块进行补偿.在时空域进行运动估计,可以充分利用视频编码多年来在运动估计方面的研究成果.在小波变换域上进行运动补偿,则避免了产生额外的频率成分.文中的理论分析和实验结果都表明,所提出的算法要优于常用的小波视频编码算法.     

Fast and simple algorithms to count the number of vertex covers in an interval graph

This study provides the following fast and simple algorithms for an interval graph: (1) an algorithm for counting the number of vertex covers, and (2) an algorithm for counting the number of minimal vertex covers.