Applied Mechanics and Materials Vol. 441

Abstract: Indoor temperature model is one of the large time-delay controlled object, and the response performance of system get worse. In consideration of the Fuzzy PID controllers strong robustness, this article adopts a Fuzzy PID-Smith control method ,and the control effect proves to be good.

Abstract: The timing synchronization methods for dc-biased optical OFDM system are different from wireless OFDM system because dc-biased optical OFDM system use intensity modulation/direct detection. Existing synchronization methods cant be used directly in dc-biased optical OFDM system. Therefore, the new timing synchronization method for dc-biased optical OFDM system is presented. The simulation results show that this timing synchronization method increasingly improves the estimated accuracy of dc-biased optical OFDM system.

Abstract: In this paper, a Gradual Compressive spectrum sensing method is presented for collaborated users in wideband cognitive radio (CR) network. By taking the advantage of compressive sensing (CS), we can reconstructs the wideband spectrum using sub-Nyquist samples. Furthermore, we employ gradual signal acquisition and recovery that can terminate the process once the result of spectral recovery converge. This proposed method is flexible for different wideband signal sparsity and signal to noise ratio, leading to enhanced network throughput. Simulations testify the effectiveness of the proposed method in CR networks.

Abstract: Based on the analysis of ultraviolet single scattering channel model, the attenuation model of fog and its impact on signal attenuation is investigated. Under foggy environment, the study on the performance of ultraviolet communications is carried, simulation results show that the fog will not only make ultraviolet communication system BER performance deterioration, but also make information transmission rate substantially lowered. In addition, to guarantee a certain system performance indicators, the average transmitted optical power will have higher requirements.

Abstract: System software program of ARM11-based vehicle mobile terminal is put forward in the paper, the program is in the core of AGPS technology and implements vehicle position. And it can communicate between the vehicle and control center through the GPS and LTE technology. The experimental results show that the program achieved a new vehicle applications and there is seamless connectivity between the vehicle and sensors devices, it has a good feasibility and reliability.

Abstract: Wiki system is an important application using Wiki technology for knowledge sharing on internet nowadays. Existing Wikipedia system have been developed with distributed collaboration ability, which most of them cant support mobile and real-time collaboration. In this paper, a novel real-time mobile collaboration WiKi system based on cloud was presented. At first, the real-time request of user group in cloud-based mobile collaboration WiKi system was discussed, and group pattern for mobile collaboration Wiki system (GPMCW) was constructed in mobile cloud environment. After that, the multiple layered Web architecture oriented mobile cloud environment was proposed. Then, the instance of cloud-based real-time mobile collaboration WiKi system (RMCWS) was given. To demonstrate the feasibility of system, a prototype system named mobile group collaboration supporting platform (MGCSP) has been constructed based on it. Practice shows that RMCWS is robust and efficient for supporting real-time mobile group collaboration, and has a good ability to idea-sharing and knowledge communication for the people.

Abstract: In terms of absolute value encoder applications, SSI communication protocol, as an earlier implementation of communication protocol, has been widely used recently. Many companies, including both domestic and overseas, have introduced encoder communication interfaces with the SSI absolute value. In this paper, based on the features of SSI protocol communication, we propose a low cost of SSI protocol communication interface design scheme for the absolute value encoder whose output is asynchronous or parallel. The experiment shows that this kind of communication interface is stable, reliable and makes the absolute value encoder with asynchronous serial or parallel output interface meet the SSI protocol specification of communication function.

Abstract: Energy efficiency is especially important for the cluster of the wireless sensor network (WSN). This paper studies how to increase availability and survivability of WSN by selecting a suitable cluster head. For this purpose, we propose a passive distributed clustering scheme (PDCS), to promote the efficiency of energy utilization. In PDCS, both the relative distance and the residual energy are taken into consideration for cluster head selection. Simulation results present that PDCS has better performance than the well-known LEACH scheme.

Abstract: In this paper, the optimization based on energy efficiency in a relay assisted wireless multicast system, where a single source communicates with multiple destinations with the help of an amplify-and-forward relay, is proposed. We assume that the source cannot reach the destinations directly, and thus the relay forwards the signal in two hops. Under the performance objective of maximizing the number of bits that the source sends to all destinations per Joule of the total energy spent, we formulate the optimization problem based on high SNR approximation, and prove that the problem can be extended to a standard Geometric Programming (GP) problem, which is a well-studied class of nonlinear and nonconvex optimization and has regular solutions. Finally, we provide a set of numerical results to illustrate energy efficiency corresponding to different channel conditions.

Abstract: The paper introduced the method and technology of how to implement a Integrated Manufacturing, each CNC machining equipment is equipped with a special communication unit, each communication unit are directly connected with the DNC main control computers on the Internet, effect of special communication unit is mainly data buffer and protocol conversion, the TCP/IP protocol is used between communication unit and DNC main control Internet computer, and used serial communication protocol communication between communication unit and NC equipment. Using this technology, all kinds of CNC machining equipment and DNC system can be easily with the CAD/CAM/CAE system, digital profile measurement system, fault diagnosis and error compensation of intelligent system integration, providing good technical conditions for further information of various advanced manufacturing environment integration.