Key Engineering Materials Vols. 467-469

Abstract: In this paper, an improved threshold segmentation algorithm based on isoperimetric ratio for infrared imaging object is proposed. The segmentation weight matrix is constructed by computing the similarity among the pixies with 4 adjoining points and stored in a sparse matrix. The isoperimetric ratio is obtained after the indicator vectors are formed with 255 gray levels. The proposed algorithm selects the minimum isoperimetric ratio confined in conditions as the best partition criterion instead of the traditional minimum isoperimetric ratio. By analyzing the variation of isoperimetric ratio with the gray levels, the proposed method can find the optimum threshold to segment infrared imaging object. Experimental results show that compared with the traditional methods, the proposed algorithm can reach a higher segmentation rate and is more robust in different kinds of infrared images.

Abstract: Larch lumbers were tested by using modal analysis technology and Frequency response functions (FRF) were derived. Modal parameters, including first 4 intrinsic frequency and first 3 modal shape, were distinguished by single modal method. Research shows that the intrinsic frequency of hole-defect lumbers is little lower than standard lumbers’ and the change rate of frequency is becoming larger gradually with the diameter of hole-defect. However, it can not judge the position of the hole-defect by the change rate of frequency. The modal shape of the node near the hole-defect always jumps abruptly, so it can estimate the particular position of hole-defect in the lumber. The variation of modal shape is becoming larger gradually with the diameter of hole-defect. It can make qualitative and quantitative estimate to the hole-defect in the lumber by considering intrinsic frequency and modal shape together.

Abstract: Implied volatility estimation is one of the fundamental tasks for asset pricing and risk management. In this paper, we investigate the applicability of semi-supervised regression techniques to estimate an implied volatility surface from the real market option data. Specifically, we employ a transductive Gaussian field regression method since it is able to predict a distribution of the implied volatilities for unlabelled data using only partially labeled data. We've conducted simulation on S&P 500 index data before and after the global financial crisis with discussions of the observed empirical properties of the method.

Abstract: Due to the well-developed technology and its variety of applications, the Radio Frequency Identifications (RFIDs) are widespread in a broad range of markets. In many applications, the RFID systems need security service such as authentication mechanism to identify tag and resist possible attacks. In 2008, Song et al. proposed a RFID authentication protocol for low-cost tags. Their protocol has the merits of privacy and security properties, and it can stand tag impersonation attack, replay attack, and backward/forward traceability. In this article, we show that their protocol cannot resist server impersonation attack as they declared. An adversary can successfully impersonate as a server to send fake message for verification. We also present countermeasures to fix the flaw. The performance of the improved mechanisms is the same as that of Song et al.’s protocol while the server impersonation attack is avoided.

Abstract: In order to make concrete production more stable and efficient, a weighing and monitoring system is constituted which provides visualization of process and a powerful Human-Machine Interface by SIMATIC WinCC. After WinCC configuration software has connected with PLC effectively, data can be transmitted to and received from PLC through communication by HMI screen. Then, PLC can control the field devices independently rely on its high reliability and high anti-jamming capability. This kind of monitoring system is more efficient than other non-automatic control systems, and it improves accuracy and reduces the production time. Monitoring concrete production through WinCC can save manpower, reduce raw material waste, improve the level of automation and production efficiency. It provides a new control method for concrete production.

Abstract: Simple multimeter can not measure True RMS of power frequency if there mixed harmonic components. In order to solve this problem, a method is adopted to design a measurement system by using STC Single Chip Microcomputer (SCM). It changes current into voltage by using I/V conversion circuit. Then analog signal turns into digital signal through AD converter. Finally, the Single Chip Microcomputer treats and calculates the data by the RMS algorithm. Sampling frequency of the system is set as 6400sps by Single Chip Microcomputer. This kind of designment uses software instead of hardware and reduces the costs. The realization of the system shows the validation and transportability of the algorithm. The testing data show that this system can measure True RMS of power frequency. The relative full scale error is smaller than 1.284%.

Abstract: The finite element model of track roller assembly of the Pc200-7 hydraulic excavator were established by the finite element software ANSYS. According to the actual working conditions of excavators, two working status of track roller assembly were summarized. Then, the structure linear static analysis to the different operating models was respectively carried on. The stress distribution situation and maximum value stress of the track roller assembly were obtained. At the same time, from the friction and wear properties, the effect of wearing on service life of the track roller was analyzed. And the improvement scheme to the easy wear parts is also proposed in the paper. The valuable reference dates is provided to the design and optimize problems and their internal friction and wear behaviors about track roller assembly of the crawler-type.

Abstract: The sludge dehydration plays a very important role in the modern sewage treatment process. In this paper the process of the sludge dehydration and the design of the control system are introduced, in which the control system consists of process control layer and remote access layer. Process control layer is realized using Siemens S7-1200 PLC and a wireless route is added for remote accessing which utilizes Ethernet and VPN technologies. The functions of the system are described, and the key points of design and implementation methods are presented. The application of this system shows that the cost of sludge treatment is reduced and the reliability of equipment is improved.

Abstract: In this paper, the effect of information sharing on the dynamics of a two-stage supply chain is investigated by switched system theory and discrete system control theory. The supply chain consists of one retailer and one distributor with a kind of order-up-to policy as the control law, and where the retailer’s forecasted demands are shared with the distributor, inventory constraint is considered too. The stability area of the different modes of the supply chain is given theoretically, and bifurcation diagram are used to describe the dynamics of the system by simulations. It is pointed that information sharing can make the supply chain more stable by weaken the bullwhip effect, however, the supply chain is apt to be unstable if the retailer choose to adjust its inventory unbalance radically, if so, the distributor should take a more conservative attitude to adjust its inventory unbalance. And it is also deduced that the stock level of the distributor has the critical effect on the dynamics of the supply chain.

Abstract: This paper analyzes the working process of current-mode controlled Boost converter and finds that the system will produce the physical phenomenon of intermittency chaos when the converter works in the period windows of chaos zone and external noise reaches certain intensity. It can observe the phenomenon of noise-induced intermittent chaos and it also analyzes the relationship between noise intensity and induced intermittent chaos, the relationship between the noise intensity threshold and circuit parameters in resulting intermittent chaos from the perspective of numerical simulation. The research has an important theoretical and practical significance to nonlinear science and it can provide a reliable theoretical reference for the stable design of switching power converters.