Advanced Materials Research Vols. 846-847

Abstract: For the scene where there is a toxic gas leak, in order to detect the gas quickly and safely and make the effective solutions, the project of monitoring toxic gases in a remote wireless way and the process of the development is proposed in this paper. The device developed in this paper includes several wireless sensor network (WSN) nodes and one hand-held terminal, and the sensor module of WSN node is composed of several chemical gas sensors. The nodes will be sent to the scene by ground robots or unmanned aerial vehicles and make up the WSN monitoring system automatically, to achieve an aim of monitoring the toxic gas in real time. The experiment results show that the device can deal with the emergencies about the leak of toxic gas efficiently. And it has the advantages of low power consumption, high cost performance, self-forming network, anti-interference. Its suitable to monitor the toxic gas in various environments of industrial production and chemical scene of accident and unexpected occasions where there is a leak of toxic gas.

Abstract: Traditional theatre dispatch platform, which is designed by circuit switching technology, has its limitation and disadvantages. So this paper proposed an effective intercom system for stage dispatch console based on IP network. We analysed its functional requirements, hardware and software framework, and the key technologies during IP communication. Various network technologies can be synthetically used, so as to realize IP integration for the whole system. Our study is of great significance in providing stage manager with fast and centralized information, which can help improving the stage performance.

Abstract: The damage threshold for different terminals is obtained by a direct injection of electromagnetic pulse (EMP) of different magnitudes to different terminals of 54LS series gate circuit, using an electrostatic discharge (ESD) simulator. The test shows that the most sensitive terminal is the output end. The correlation coefficient of damage voltage value of ESD injection and square wave injection is 0.75, which is a high relevance.

Abstract: This paper discusses the soft switching circuit—Boost-ZVT converter, and studies the role of Boost-ZVT converter in the factor correction circuit(PFC). Distinguished from the past Boost converter, the Boost-ZVT converter implements the main switch of the soft turn-off, reducing switching losses and improving the system efficiency. At last, Matlab software is carried out the main circuit simulation. The simulation results show that Boost-ZVT circuit has a good effect in PFC circuit design, and has a wide application in practical circuit design.

Abstract: In this paper, a global sliding mode control scheme is proposed for a helicopter with input time delay and disturbance. We proposed a new method for integral sliding surface. By the design of dynamic nonlinear sliding mode function, the controller has the advantage of eliminating the reaching movement of traditional sliding mode control, overcoming the effect of the disturbance and time delay. The system state variables reached the sliding surface at the very beginning by means of designing a dynamic nonlinear sliding mode function, and moved to the expected state under the control of control law. The efficiency of the proposed method is demonstrated by simulation results.

Abstract: Several subjects including hoisting, derricking and slewing of boom, extending and contracting of boom, setting down and retracting of outriggers, have to be carried out in truck crane operating reliability test according to native standard. It is a laborious and time consuming work which repeats hundreds or even ten hundreds times. In this paper, a Wireless Sensor Network (WSN) based system was built to automatically count the number of each test item. To achieve counting numbers of status change of telescopic boom, extending length or hoisting height were measured by one pair of wireless ranging sensor nodes adopting Chirp Spread Spectrum technique. The status change of outriggers and boom was monitored by detecting signals from a group of hall sensors. The data were then transmitted to main software by ZigBee wireless sensor network based on star topology. The software was developed for further data processing and storage by Labwindows/CVI. Preliminary experiments that included simulation and on-the-spot test were conducted. The results show that the count is in accordance with actual number. It is helpful and practical to reduce labor intensity as well as kinds of resources investment.

Abstract: The fault diagnosis technology have emerged and developed rapidly with the development of wireless sensor networks and requirements of applications improve. This paper describes two commonly used sensor network fault modeling. What is more, in order to solve this problem that sensor nodes are vulnerable and therefore produce wrong data, the paper proposes a distributed fault detecting algorithm based on spatio-temporal correlation among data of adjacent nodes. The simulation experiment shows that the algorithm can efficiently detect errors in the network and very few errors are introduced.

Abstract: The high-density randomly deployment of nodes in Wireless Sensor Networks results in a large number of redundant nodes due to the overlap of sensing areas. A scheduling algorithm for redundant nodes is proposed to effectively prolong the lifetime of WSN. The algorithm focuses on employing different scheduling strategies on border nodes and internal nodes to avoid contraction of the network boundary by judging whether a node is on the network boundary according to the number of working nodes in its neighbor table. The simulation results show that the algorithm can effectively prolong the lifetime of the network.

Abstract: A technique is employed to reduce the size of planar dipole. The technique is consists of adding short-ended microstrip line at the top of the dipole, making the structure be inductive load, and as a result, increase the effective length. A design example for the ISM band is presented. The configuration reduces the resonance frequency of the planar dipole by 25.8% without degrading influence on antenna performance. The antenna comprising of only a single layer planar in additional to the microstrip feed line offers over a S11<-10dB bandwidth from 2.4GHz to 2.4835GHz which is wide enough to cover WLAN, BLUETOOTH, RFID, and WIFI communication bands. With this reduced size and omnidirectional pattern, it is very suitable for narrow band systems such as: WCDMA, WiMAX, among others.

Abstract: Synthetically considering the special environment underground, we combined the wireless sensor network with the existing cable mine monitoring system, forming a new monitoring system based on Ethernet and WSN, and then we put forward a layer based energy-balanced reliable routing (LBEBR) protocol for WSN to solve the spot problem in zonal area of coal mine and to ensure the reliability of data transmission. The working face was divided into several equal rectangular layers. According to the optimal cluster radius calculated before, different numbers of nodes constituted clusters of different sizes in each layer. In the stage of data transmission, using the reliability evaluation of nodes and considering three factors, the residual energy of nodes, the distance between nodes and the reliability of nodes, to select the best next-hop node. Simulation results show that the protocol can not only balance the energy of the network, but also elude problem nodes effectively to increase the reliability of data transmission.