光纤抗干扰技术在计算机中的应用

介绍了用光纤传输计算机信号的必要性和优越性 ,以及具体的实施办法和出现问题、难点的解决方法。     

An overview of analytical methodologies for the determination of antibiotics in environmental waters

The widespread occurrence of antibiotics as contaminants in the aquatic environment has increased attention in the last years. The concern over the release of antibiotics into the environment is related primarily to the potential for the development of antimicrobial resistance among microorganisms. This article presents an overview of analytical methodologies for the determination of quinolone (Qs) and fluoroquinolone (FQs), macrolide (MLs), tetracycline (TCs), sulfonamide (SAs) antibiotics and trimethoprim (TMP) in different environmental waters. The analysis of these antibiotics has usually been carried out by high-performance liquid chromatography (HPLC) coupled to mass spectrometry (MS) or tandem mass spectrometry (MS/MS) and to a lesser extent by ultraviolet (UV) or fluorescence detection (FD). A very important step before LC analysis is sample preparation and extraction leading to elimination of interferences and prevention of matrix effect and preconcentration of target analytes.     

SMT solder joint's semi-experimental fatigue model

The low-cycle fatigue induced by thermal cycling is the major concern in the reliability of surface mounted technology (SMT) for electronic packaging; however, dynamic loading effects to solder joint fatigue life have not been thoroughly investigated. In fact, the high-cycling fatigue induced by vibration can also contribute a significant effect. In certain circumstances it can become the dominant failure case when semiconductor devices are used in a vibration environment. In this paper, according to random vibration theory, a random fatigue semi-experimental model of SMT solder joint in random vibration condition is created and a series of vibration fatigue experimental vehicles including PBGA256 assembly were conducted. Compared with random vibration test results, its results are good enough to predict solder joints' fatigue.     

基于彩色图像分割技术的SMT焊点质量检测

图像分割的策略和方法是SMT焊点图像处理的一项关键技术,也一直是SMT焊点计算机质量检测的瓶颈;以SMT焊点的颜色和几何特征作为分析对象,在灰度图像分割所用二维阈值化的分割方法的基础上,提出一种从颜色直方图的量化级数和二维直方图概率密度不均匀化两个方面改进后的适用于HSV彩色空间图像分割技术,并将其应用于SMT焊点的质量检测;通过其得到SMT片式元器件焊点的图像,对其进行形态学处理后,利用Matlab软件将SMT焊点成功地从PCB板上分离出来,为三维重建提供良好的基础。     

Three-dimensional thermal deformations observed in SMT assembly during power cycling

The three-dimensional displacement fields of thermal-force coupling fatigue in a surface mounted plastic-quad-flat-pack (PQFP) assembly during power cycling by using the combination of holographic interferometry and high sensitivity moire interferometry is presented in this paper. Detailed in-plane and out-of-plane whole-field displacement data of the top and bottom ends of gull wing leads and their distributions along the edge of PQFP are provided. It was found that the maximum deformations of gull wing leads occur at the four corners of PQFP. The result presented herein should be useful in the evaluation of thermal fatigue damage mechanism of surface mount assemblies.     

Recent advances in sample preparation techniques and methods of sulfonamides detection – A review

Sulfonamides (SAs) have been the most widely used antimicrobial drugs for more than 70 years, and their residues in foodstuffs and environmental samples pose serious health hazards. For this reason, sensitive and specific methods for the quantification of these compounds in numerous matrices have been developed. This review intends to provide an updated overview of the recent trends over the past five years in sample preparation techniques and methods for detecting SAs. Examples of the sample preparation techniques, including liquid–liquid and solid-phase extraction, dispersive liquid–liquid microextraction and QuEChERS, are given. Different methods of detecting the SAs present in food and feed and in environmental, pharmaceutical and biological samples are discussed.     

Shortened screening method for phosphorus fractionation in sediments: A complementary approach to the standards, measurements and testing harmonised protocol

The SMT protocol, a sediment phosphorus fractionation method harmonised and validated in the frame of the standards, measurements and testing (SMT) programme (European Commission), establishes five fractions of phosphorus according to their extractability. The determination of phosphate extracted is carried out spectrophotometrically. This protocol has been applied to 11 sediments of different origin and characteristics and the phosphorus extracted in each fraction was determined not only by UV-Vis spectrophotometry, but also by inductively coupled plasma-atomic emission spectrometry. The use of these two determination techniques allowed the differentiation between phosphorus that was present in the extracts as soluble reactive phosphorus and as total phosphorus. From the comparison of data obtained with both determination techniques a shortened screening method, for a quick evaluation of the magnitude and importance of the fractions given by the SMT protocol, is proposed and validated using two certified reference materials.     

Analytical phosphorus fractionation in sewage sludge and sediment samples

The Standards, Measurements and Testing (SMT) harmonized procedure for phosphorus fractionation in freshwater sediments (SMT protocol), which was developed within the framework of the Standards, Measurements and Testing (SMT) Programme of the European Commission, has been applied to different environmental samples such as sewage sludge, river and marine sediments. The phosphorus contents in the extracts were spectrophotometrically determined; the measurement conditions and the matrix effects were evaluated for each fraction. The partitioning patterns obtained for sewage sludge and sediment samples reveal that the distribution between inorganic and organic phosphorus forms is independent of the matrix composition of the samples. In addition, a higher available phosphorus content was found in sewage sludges due to the higher percentages of labile phosphorus forms, which suggests possible internal phosphorus release. Finally, one simplified pseudototal microwave digestion method was performed for total phosphorus determination which was validated by its application to the reference material BCR-684.