Key Engineering Materials Vols. 480-481

Abstract: A calibrated plate will be placed on the spot before digital pictures are taken to calculate all kinds of useful data with a distance measure system of traffic based on single view. Depressed pavement area such as groove, gasoline stained etc. can be measured based on a single view, a method which employs region growing and boundary tracking was given in this paper. Firstly a closed boundary can be achieved with algorithm of region growing and boundary tracking, furthermore the pixels within the target closed area can be calculated. Finally the practical area can be calculated through the ratio relationship between the area and the calibrate plate. The experiment shows that the method has low time complexity and high robust．

Abstract: In this paper, a novel incremental conductance (INC) maximum power point tracking (MPPT) method based on extension theory is developed to make full use of photovoltaic (PV) array output power. The proposed method can adjust the step size to track the PV array’s maximum power point (MPP) automatically. Compared with the conventional fixed step size INC method, the presented approach is able to effectively improve the dynamic response and steady state performance of a PV system simultaneously. A theoretical analysis and the design principle of the proposed method are described in detail. Some simulation results are performed to verify the effectiveness of the proposed MPPT method.

Abstract: This article presents a shield’s earth-pressure-balance (EPB) simulation device based on fluid power transmission principle. The device was developed according to the mathematic model of shield’s EPB system. It is composed of load simulation subsystem and screw-conveyor speed control subsystem. With the regulations of the hydraulic parameters in the subsystems, the device is capable of simulating the situations of earth input and output in cutter chamber, as well as the changes of earth property and shield propulsive velocity. Experimental results proved that the working principle of the device is right, the regulation of hydraulic parameters is convenient, and the enhancement of experiment strength is feasible. Therefore, the experiment research expense on shield's EPB system is reduced and the experiment efficiency is increased. The developed device can provide an economical and effective means for the scheme design and characteristics analysis of shield's EPB system.

Abstract: Aiming at the runner design feature of injection mold of combinational cavities laid in non-natural balance, the design method of multi-objective runner optimization is put forward based on Kriging model. At fist, the basic theory of Kriging approximate model is proposed, and aiming at the feature of combinational cavities, the multi-objective optimum model of runner system is proposed also. In the solving multi-objective optimum model, the multi-objective ant colonies algorithm with crossover and mutation based on Pareto optimization is proposed. The given method is testified by a runner design instance of top and down cover of mouse, and it has a good application in engineering. The optimum result shows that the multi-objective ant colonies algorithm with crossover and mutation has good algorithmic performance.

Abstract: A shapefile to SWF conversion software was mainly introduced. By converting the traditional GIS files such as ESRI Shapefile to the Shock Wave Flash (SWF) file format, the GIS data was highly compressed and suitable for the Internet publication. The generation of SWF files provided a complement for the current WebGIS technology and by using the converted SWF map files, an extended example of flash-based application in multi-level analysis to the socio-economic data was constructed. The example demenstrated its easy configuration and powerful potential ablities. More powerful applications based on SWF will be continued in the future work.

Abstract: For those large-scale and complex mechanical products, considering economy and applicability, these products are impossible to be discarded as soon as they take place malfunction. Generally, they can be reused again and again after be repaired repeatedly, that is, they usually have multi-lifespan. Accordingly, it is very necessary to establish a kind of proper reliability evaluation mode for these complex repairable products. In this paper, the treatment procedure of the reliability test data for these repairable products is researched based on the repairable reliability theory, and the method of model identification about failure distributions law is proposed. In addition, how to reasonably determine or predict product lives by using random process model is also introduced. Finally, an analysis case for putting this mean into practice is expounded. This method for product reliability analysis is suitable to most large-scale and complex mechanical products.

Abstract: In this paper, we present the design and implementation of OTP-DEF, a kernel extension to protect web servers against application layer DDoS attacks. OTP-DEF provides authentication by using OTP-based tests, which is different from other systems that use graphical tests. First of all, according to the load of web server, an OTP-DEF web-server should fall into one of three following modes: normal, suspected attack or confirmed attack mode, and the OTP-DEF authentication mechanism shall only be activated when web-server is in suspected attack mode. Secondly, we use OTP as our puzzle, which can automatically change at the certain time interval. It makes our proposal can defend socially-engineered attack, copy attacks, replay attacks and Brute-Force Attack. Thirdly, OTP-DEF uses an intermediate stage to identify the IP addresses that ignore the test, and persistently bombard the server with requests despite repeated failures at solving the puzzles. These machines are zombies because their intent is to congest the server. Once these machines are identified, OTP-DEF blocks their requests, turns the tests off, and allows access to legitimate users who are unable or unwilling to solve tests. Finally, OTP-DEF requires no modifications to client software.

Abstract: The area of robust detection in the presence of partly unknown useful signal or interference is a widespread task in many signal processing applications. In this paper, we consider the robustness of a matched subspace detector in additive white Gaussian noise, under the condition that the noise power is known under null hypothesis, and unknown under alternative hypothesis when the useful signal triggers an variation of noise power, and we also consider the mismatch between the signal subspace and receiver matched filter. The test statistic of this detection problem is derived based on generalized likelihood ratio test, and the distribution of the test statistic is analysis. The computer simulation is used to validate the performance analysis and the robustness of this algorithm at low SNR, compared with other matched subspace detectors.

Abstract: In this paper, we conducted the research on RFID technology in the application of parking management system. The system adopts the scheme of RFID technology combined with background application software, whose foreground uses Visual basic 6.0 to carry on the application procedure development, and background carries on the data administration work with access database. It collects ID information by RFID module, and then uses computer software technology to charge fees even though vehicles do not stop. In that way the system achieves the automation of management and charge. In addition, this paper has also introduced RFID hardware components, operating principle, installation method of readers and control equipment (PC) in the parking site, system software design, development processes of software data acquisition in detail.

Abstract: The limiting facts of driving the Hall element by the pulsed power supply and sampling when the peak value coming are studied. The equivalent relation of temperature rising between the DC and pulsed power supply is given. When the electric field intensity inside the Hall element rises to about 1850V/cm, the linear relationship between the Hall output voltage and the input voltage will be affected by the decrease of the mobility. The thermal-power consumption almost does not affect the use of the Hall element. The above problem could be overcome by enlarging the die dimension.