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81.
Multiple Walsh-function generators are used in signal multiplexing. A new design is proposed which is less limited by the finite response time of digital components and is hence capable of producing functions of higher sequencies. 相似文献
82.
The effects of zinc and copper salts on the survival of the two species of freshwater fish, common carp, Cyprinus carpio, and grass carp, Ctenopharyngodon idellus, were investigated. It was discovered that the levels of tolerance to the concentration of the metals were species-specific. Cyprinus carpio was found to be more susceptible to copper, whereas Ctenopharyngodon idellus was more susceptible to zinc. In general, copper was more toxic than zinc, as revealed by the survival times. The body and the gills of dead fish seemed to be covered by a veil-like film which looked like coagulated mucus and which was formed by the heavy-metal ions reacting with some constituents of the mucus and which was formed by the heavy-metal ions reacting with some constituents of the mucus secreted by the gill. The histopathological assessment of the gill and liver of Cyprinus carpio was also carried out. Particles were observed around the gills of the dead fish treated with zinc and copper salts, although no other major changes were found in the gill. Several histopathological changes were observed in the livers, including the presence of particles. The symptoms of the liver suggested that the internal injury was also an important feature of the intoxicants. 相似文献
83.
84.
Andrew J. Woods Ka Lun Yuen Kai S. Karvinen 《Journal of the Society for Information Display》2007,15(11):889-898
Abstract— In 1853, William Rollman developed the inexpensive and easy to use anaglyph method for displaying stereoscopic images. Although it can be used with nearly any type of full‐color display, the anaglyph method compromises the accuracy of color reproduction, and it often suffers from crosstalk (or ghosting) between the left‐ and right‐eye image channels. Crosstalk degrades the ability of the observer to fuse the stereoscopic image, and hence reduces the quality of the 3‐D image. Crosstalk is present in various levels with most stereoscopic displays; however, it is often particularly evident with anaglyphic 3‐D images. This paper summarizes the results of two projects that characterized the presence of anaglyphic crosstalk due to spectral issues on 13 LCD monitors, 14 plasma displays, and a CRT monitor when used with 25 different pairs of anaglyph 3‐D glasses. A mathematical model was used to predict the amount of crosstalk in anaglyphic 3‐D images when different combinations of displays and glasses are used, and therefore highlight displays, glasses, and combinations thereof which exhibit lower levels of crosstalk when displaying anaglyphic 3‐D images. 相似文献
85.
86.
Ever since the 9/11 terrorist attack, many countries are considering the use of smart national identity card (SNIC) which has the ability to identify terrorists due to its biometric verification function. However, there are many ergonomics issues in the use of SNIC, e.g. card credibility. This research presents a case study survey of Malaysian users. Although most citizens (>96%) own MyKad (Malaysia SNIC), many do not carry it around and use its applications. This defeats one of its main purposes, i.e. combating terrorism. Thus, the research investigates ergonomics issues affecting the citizens’ Intention to Use (ITU) MyKad for homeland security by using an extended technology acceptance model. Five hundred questionnaires were collected and analysed using structural equation modelling. Results show that perceived credibility and performance expectancy are the key issues. The findings provide many countries with insights into methods of addressing ergonomics issues and increasing adoption of SNIC for homeland security. 相似文献
87.
A method of computing the input impedance for the probe fed circular microstrip antenna with thick dielectric substrate is presented. Utilizing the framework of the cavity model, the fields under the microstrip patch are expanded in a set of modes satisfying the boundary conditions on the eccentrically located probe, as well as on the cavity magnetic wall. A mode-matching technique is used to solve for the electric field at the junction between the cavity and the coaxial feed cable. The reflection coefficient of the transverse electromagnetic (TEM) mode incident in the coaxial cable is determined, from which the input impedance of the antenna is computed. Measured data are presented to verify the theoretical calculations. Results of the computation of various losses for the circular printed antenna as a function of substrate thickness are also included. 相似文献
88.
M. M. F. Yuen S. T. Tan K. Y. Hung 《International journal for numerical methods in engineering》1991,32(3):501-525
A point-based two-stage hierarchical method for automatic finite element mesh generation from a solid model is presented. Given the solid model of a component and the required nodal density distribution, nodes are generated according to the hierarchy—vertex, edge, face and solid. At the vertices, nodes are established naturally. Nodes on the edges, faces and inside the solid model are generated by recursive subdivision. The nodes are then connected to form a valid and well-conditioned finite element mesh of tetrahedron elements using modified Delaunay Triangulation. Checks are conducted to ensure the compatibility of geometry and topology between the solid model and the mesh. 相似文献
89.
This paper describes a fuzzy multiobjective optimization approach for determining the set‐points of the injection molding processing parameters to minimize the defects formed on the molded parts. The severities of the defects are represented by membership functions using the fuzzy set theory. The minimization of these membership functions, which is a multiobjective optimization problem, is transformed into a substitute problem. The preference function in the substitute problem is original and is proposed specifically for characterizing the quality requirements of the injection molding defects. The formulated optimization problem is solved with design of experiments, in which the process behavior is approximated empirically by a set of quadratic polynomials that can be easily optimized. Experimental results are presented to emphasis the workability of the proposed methodology. 相似文献
90.