Applied Mechanics and Materials Vols. 433-435

Abstract: Contrast sensitivity measurement is widely used in clinical ophthalmology to evaluate visual function of the human eye, and of great significance for early diagnosis and identification of ophthalmic diseases. On the basis of contrast sensitivity definition, current measurement method was analyzed. By analyzing the existing principles and shortcomings of the human eye contrast sensitivity methods, a new method for generating observation targets of contrast sensitivity was proposed. By using double optical path design idea with integrating sphere and self-developed brightness adjustment systems, two beams of uniform light with specific luminance could be produced. With subsequent reuse of the optical path, accurate measurement of eye contrast sensitivity could be achieved, and calibration of contrast sensitivity tester widely used in clinical practice could be solved by developing assistant transfer tools. Moreover, output parameters of this method could be precisely adjusted according to the need as a result it ccould achieve real-time control and calibration. The research result has set the foundation for future establishment of visual threshold measuring device which is especially suitable for scientific and experimental research in clinical ophthalmology and metrology.

Abstract: A method for the uncertainty estimation of probe calibrations using the power flux density (PFD) system of (18~26.5) GHz recently developed at the National Institute of Metrology, China is presented. A measurement model is developed first, and then the sources of uncertainty and the corresponding evaluation procedures are explained. The method is used to estimate the uncertainty of the calibration factor of a FP7050 probe at 18 GHz obtained by the PFD system. The good agreement between the calibration results from two PFD systems validates the method.

Abstract: This paper presents a field programmable gate array (FPGA) prototype of a four-by-four keypad arbitrary-key-entry detector design for entering any arbitrary set of the 4x4 keypad keys. The number of the valid keys was defined by a multiple-bit mask input. The character code of the prohibited key would not be generated after a key stroke. A valid-key stroke caused the detector circuit to generate a 4-bit hexadecimal character code and a sampling tick for the next-stage device to capture the pressed key information. The detector design and the testing circuitry were implemented on an Atlys Spartan-6 FPGA Development Board. The design itself can be incorporated into a wide variety of key-entry tools on electronic instruments, mechanical devices, medical apparatus, and more, to improve the key-stroke filtering and ease the interface connection.

Abstract: In this paper, an effective method for detecting the cold weld defects in the thermal fusion weld of high-density polyethylene (HDPE) pipeline based on microwave technique is proposed. Using a microwave testing system, HDPE piping welds were examined in a proper position by frequency sweep within the range of 9.3-9.9 GHz. At a frequency that was most sensitive to the cold weld defects, the measured reflection coefficient S₁₁ exhibited significantly different values between the good weld and those containing cold weld defects. The readily detectable differences in S₁₁ value make identification of the cold weld defects possible. This work provides a basis for inspection of defects in HDPE piping welds.

Abstract: Against the question of mobile terminal collaboration resources and its constraints in mobile collaborative environment, a multi-level fuzzy mobile collaboration performance measurement model was proposed, which can take advantage of these limited resources effectively and improve the cooperation efficiency of mobile group. At first, the basic concepts, theory and patterns of mobile collaborative performance evaluation system were analyzed. Then, a mobile collaborative performance evaluation system was built based on them using the analytic hierarchy process and fuzzy comprehensive evaluation to evaluated the collaborative performance, and finally put forward countermeasures and suggestions to improve the group cooperation..

Abstract: An automatic none destructive apparatus for measuring the magnetic permeability of cylinder ferrimagnetic sample is introduced. Based on Faraday’s law and demagnetizing factor iteration formula, the device consists solenoid, induction coils, Lock-in amplifier 7265 and a computer for controlling the applied magnetic field and permeability calculation. Five high-resistivity iron alloy rod are chosen as samples and typical material permeability is compared with previous work.

Abstract: Cognitive radio (CR) is an intelligent spectrum sharing technology. It can improve the spectrum utilization by sensing spectrum environment, learning intelligently and adjusting the transmission parameters. The discussion is focused on spectrum detecting technology in cognitive radio. Spectrum detecting algorithms are analyzed and compared .The centralized cooperative spectrum detection method, distributed cooperative spectrum sensing method and relay cooperative spectrum detection method are analyzed also.

Abstract: This paper presents the research of several key technologies during the implementation of cold-rolling aluminum surface defect detection system, including the difficulty of achieving these key technologies and the improvement of image processing algorithm. Through the installation and commissioning on actual production line, summarize and analyze the requirements of the hardware and software design for highly reflective aluminum plate, to achieve the control of product quality at present.

Abstract: Rencently, due to the increasing vehicles and traffic accidents, the demand of vehcile automation is growing fast, and the traditional vehicle control strategy cant meet the requirement of security. In this paper, we propose a novel vehicle reversing speed control based on obstacle detection. The main components of the system consist of three parts. Firstly, a binocular-cameras system aims to detect the obstacles behind the vehicle rear and measure the distance of them. Then, the framework of particle filter and the sparse representation is indtroduced to track and identify the main obstacles such as human beings, vehicles and any other obstacles. Finally, we send the obstacles signal to our Electronic Control Unit (ECU) to control the electronic throttle and Anti-lock Brake System (ABS) so as to make reversing speed under a safe speed range.The last performance evaluation demonstrates the validity of the proposed vehicle reversing speed control based on obstacle detection.

Abstract: Collision detection is the key technology in the visual simulation system for bridge cranes. According to analyse the collision between hook and virtual objects in visual simulation system for bridge cranes, collision detection method of visual simulation system for bridge cranes is determined based on the collision detection principle. First of all, LOS intersection vector method is chosen based on the principle of collision detection in Vega. Hook is designed for the collision target using Isector module in Lynx and the same intersection vector masks in Isector Class are guaranteed. Then, the BUMP collision detection for hook is created by calling vgIsector functions in VC++ and BUMP detection method of hook is bounded with hook. Finally, conditional statements which ensure hook to move without collision are compiled. Therefore, the virtual scene around the hook is detected in real time. The results show that the phenomenon of passing through by mistake for the hook can be avoided applying the BUMP collision detection method in Vega software in visual simulation system for bridge cranes, and the accuracy for BUMP method detecting the goods is improved using LOS collision detection method.