Applied Mechanics and Materials Vols. 668-669

Abstract: This paper introduces a simple, E-shaped slot loaded wideband microstrip patch antenna with a metallic cavity. The antenna design is an improvement from previous research and it is simulated using HFSS 13 software. The performance of the designed antenna was analyzed in term of bandwidth, gain, VSWR, and radiation pattern. What does the substrate use is air. The results show the wideband antenna is able to operate from 190MHz to 230MHz frequency band with optimum frequency at 210MHz, and the 3-dB radiation beamwidth of the E and the H plane at the 210MHz are 61° and 51°. However, the 3-dB radiation beamwidth of the E and the H plane at the 210MHz can be adjusted to 70° by using a metallic cavity.

Abstract: The three-dimensional positioning algorithm has become a hot research direction in wireless sensor networks localization algorithms, however the existing 3D positioning algorithms have general shortcomings, such as high complexity, low positioning accuracy, great energy consumption. Aiming at the existing problems of 3D localization algorithm, we propose an decentralized 3D positioning algorithm based on RSSI ranging and free ranging mechanism. The algorithm firstly use measured RSSI to establish beacon node neighborhood. Then the method adopts regional division to obtain initial location information for unknown nodes. Finally, the method use the iterative optimization process to achieve a position information updates. Simulation results demonstrate that proposed algorithm is feasible and has better localization accuracy.

Abstract: In semantic Web, extensive reuse of existing large ontology is one of the central ideas of ontology engineering. Ontology extraction should return relative sub-ontology that covers some sub-vocabulary. The efficiency of the existing ontology extraction algorithm is relatively low when they try to get a suitable ontology module from ontology at run time. This paper proposed a kind of ontology module extraction method. Related concepts and criterions of ontology modules extraction are studied; data structures and identification and evaluation methods of ontology module extraction are discussed; preliminary experimental results and the corresponding analysis are also shown.

Abstract: A web service is a software function provided at a network address over the web or the cloud. Conventional web service is described by WSDL. As for the conventional web services, it has problems of discovering and selecting the most suitable web service. Semantic web service can solve these problems, and it is described by OWL-S. In this paper, we propose a method of automatic generation of documents from WSDL to OWL-S. To accomplish this, we first translate XML document to OWL document through the relationship between XML Schema and the ontology. We use a mapping rule from XML Schema to Schema tree and Element tree. As for the WSDL document is written by XML. And OWL-S document is written by OWL. We translate WSDL document to OWL-S document based on mapping between XML document and OWL document. At present, most of web service is described by WSDL. According to this method, we can not only translate from WSDL document to OWL-S document easily, but also make the generation more efficient. Thus, we provide support for extensive of web services and service composition and discovery. Through the use of an example, the paper verifies the method is feasible and effective.

Abstract: Finding the minimum complete test cases to cover all the behaviors of the protocol by formalized model is the good method to solve protocol testing. A protocol test cases generation method is presented. The method can produce minimum complete test cases. It covers protocol behaviors as much as possible by test cases as little as possible. The basic idea of this method is: express protocol basic test case by Petri net basic process section, combine the test cases by operations such as connection, union and closure, then get the minimum complete test cases. With an example, give the method of producing minimum complete test cases based on LAPD protocol. This method makes the protocol test more accurate and intuitive.

Abstract: In this paper, we present a modified discrete Fourier transform (DFT)-based channel estimator for orthogonal frequency-division multiplexing (OFDM) systems with null carriers. Due to the channel leakage, the conventional DFT-based estimator has the problem of error floor. In order to suppress the leakage, we adopt the optimal leakage suppression method. Moreover, a novel denoising method based on dual-tree complex wavelet is proposed to further improve the performance. Simulation results show that the proposed channel estimator can effectively overcome the performance degradation caused by the leakage and additive-white gaussian noise (AWGN).

Abstract: Wireless sensor and actor networks (WSANs) additionally employ actor nodes within the wireless sensor network (WSN) which can process the sensed data and perform certain actions based on this collected data. In most applications, inter-actor coordination is required to provide the best response. One actor failure may lead to partitioning the inter-actor networks, tolerating the actor failure and restoring the lost connectivity need to be performed while imposing the least overhead on the individual actors autonomously. In this paper, we present a Self-healing Connectivity Recovery Algorithm (SCRA) which is to recover the failure actor. SCRA proactively identifies actors whether is a cut vertex or not to the network connectivity based on the depth-first search algorithm (DFS), and designates a minimal CDS backup nodes. If an actor node suddenly fails, the minimal block backup nodes move and initiate a recovery process until the network is reconnected. Through simulated experiments, the results show that the algorithm is more effective than present algorithms in terms of total travel distance, and total number of messages.

Abstract: With the constant enlargement of the range of application of wireless sensor network, extending wireless sensor network’ life cycle has attracted more and more attention under the circumstances of limited node energy. On account of three-dimensional space background for the environmental monitoring of high buildings, this thesis put forward an improved energy-saving optimum algorithm of LEACH: improving probability of high-energy node elected as cluster head during cluster head election; selecting a network with the minimum communication cost. The simulation experiment indicates that under the layout of three-dimensional space, improving algorithm makes the load of wireless sensor network more balancing, and extending network’ life cycle. what’ s more, simulation result, in a way, serves as theoretical basis for a further study on the life cycle of wireless sensor network.

Abstract: As the conventional satellite simulator has simple function and bad universalness, it cannot adapt the needs of multi-TT&C systems and multi-satellite platforms. In order to solve this problem, a new satellite simulator based on software radio theory is designed that adopts the 70MHz IF digitized approach to suit the needs. This satellite simulator has the advantages of small size, high precision, well stability and easy operation.

Abstract: This Paper based on the research framework of SDN, at the transport layer uses the OFDM technology transfer, namely encapsulate traffic for high speed large capacity transmission in the spectrum. Under the architecture of SDN based on p-cycle of new protection algorithm (EffectiveGrow algorithm) to protect spectrum, and using classic p-cycle algorithm turns compare with it, through the JAVA building the pan-european COST239 network topology, comparison algorithm between the various performance indicators. Finally, the simulation results show that compared with the existing classic algorithm has better performance and is suitable for the SDN capacity and configuration.