Earticle

Security data aggregation plays an important role in reducing the amount of data transmission and prolonging the life of wireless sensor networks (WSN). When the security of the aggregation nodes is threatened, the networks can generate many aggregated data errors, leading to trouble in a security measure. In this paper, we propose an energy-efficient reliable trust-based data aggregation protocol for WSN called the ERTDA protocol. Based on the observations of the nodal behavior, the ERTDA protocol calculates, monitors and evaluates the trust values of the nodes; it also detects and excludes the compromised nodes in a timely manner. The simulation results illustrate that the ERTDA protocol can effectively improve the accuracy of the aggregation, reduce the nodal mortality rate, reduce the nodal energy consumption, improve the reliability of the data transmission and extend the life of the networks.

Wireless sensor networks are normally utilized for monitoring and controlling of specific environments. They are made out of a large number of low-cost sensor nodes which are densely separated in distributed environments. The information collected by sensors should be transmitted to a base station. Recent developments indicate that the interest in applications of wireless sensor networks has increased and expanded on a large scale. One of the most important issues in this type of networks is limited energy. Clustering is a suitable method for increasing network lifetime that protects the limited sensor resources by energy saving. Meta-heuristic algorithms have been widely used for clustering of wireless sensor networks. In most complicated problems, it is required to evaluate a multitude of possible modes, to determine an accurate answer. Meta-heuristic algorithms can provide an answer in acceptable time constraints. They play an effective role in solving such problems by optimizing the energy consumption of the networks that has a significant impact on the network lifetime. In this paper, the application of clustering algorithms in wireless sensor networks has been investigated. The selected clustering methods are based on the meta-heuristic algorithms.

It is critical to locate facilities in the retail operations, especially in competitive environment. In most competitive location models available in the literatures, demand is assumed to be fixed or random regardless of market conditions. However, demand is related to the number of facilities, service capacity or the distance from the facility to the customer, which is considered in few literatures. In this paper, a competitive multi-facility location model with fixed demand is established and then market expansion is taken into account in the model. The Plant Growth Simulation Algorithm (PGSA) is put forward to solve the two models and then a small numerical example is given. Compared to the problem with fixed demand, the optimum solution of facility location is variable and the profit increases obviously with market expansion considered.

Switch open fault characteristics and simple diagnosis scheme in a permanent magnet synchronous generator (PMSG) based variable-speed grid-connected wind power conversion are presented. In the back-to-back converter, the failure in switching devices may occur either in a machine side converter (MSC) or in a grid side converter (GSC), which decreases the generator output power and degrades the stability in wind power generation system. To detect such a fault, a monitoring scheme for the second-order harmonic components in the q-axis current is proposed, where the harmonic values are simultaneously observed in the MSC as well as in the GSC to monitor abnormal operation of system. To determine the harmonic values irrespective of operating conditions, the normalized currents are employed for the harmonic calculation. To verify the effectiveness of the proposed fault diagnosis scheme, the comparative simulation results are presented. As a result, an on-line simple diagnosis scheme which monitors the condition of generation system can be realized without requiring any additional hardware equipment.

A fiber access communication system is developed to cater for the need of network communications industry. In this paper, the basic framework of the system is described; with regards to the characteristics of the system, firstly the electromagnetic interference approaches of the whole system are discussed. Emphasis is laid on the engineering analysis and discussion of the interference sources of electromagnetic emission, with solutions thereof suggested; meanwhile, analysis and discussion are conducted on the electromagnetic immunity of the system in view of electromagnetic coupling paths, with corresponding solutions put forward as well. Lastly, the EMC testing results of the system is presented. Practice has proven that this approach is specially favorable for EMC design and comprehension throughout the system development process, which is also effective for the communication industry in EMC design and verification.

According to the structure of the mainstream modern airborne radar warning receiver, a modeling method of radar warning receiver simulation system is presented in this paper, and it realized under the condition of SystemVue. The system consist of radar signal interception, parameter estimation and signal sorting, pulse description words can be obtained at last. The application of parameter estimation method, based on cyclic correlation, and the sorting method, based on detection of single source point, improve the robustness of whole simulation system. Finally, experiment results verify the feasibility of the scheme.

In the last two decades, there has been significant advancement in heuristics for inducing Bayesian belief networks for the purpose of automatic distillation of knowledge from masses of data with target concepts. However, there are various circumstances where we are confronted to fix a set of most influencing variables in modeling of class variable. This arises in provision of confidence measures on set of variables used in the structure learning of data. In this study, we have tweaked empirical as well as theoretical aspects of various feature selection evaluators, their corresponding searching methods under six well known scoring functions in K2 which is a notable structure learning technique in Bayesian belief network. We have come up with some useful findings for overall computationally efficient approach among eleven evaluators. This analysis is useful in inducing better structure from the given dataset in imparting improved performance metric useful in the domain of control and automation.

In the collaborative evolution of biomedical ontology, participants are a sizeable, balanced mix of scholars and physicians, all of whom are experienced in the biomedical domain and who represent diverse viewpoints, experiences, and backgrounds. In the field of collaborative evolution of biomedical ontology on large-scale ontology, there exists inevitable conflicts, which may cause the inconsistent ontology. In this paper, a new method to detect conflicts in ontology evolution is presented, which classifies conflicts as three groups: internal inconsistencies conflicts in change sequence, direct conflicts between the sequences and Inconsistent conflict between the sequences. For different conflict, high effective detecting algorithms are presented with evaluation. Before the conflicts detecting, semantic extended rules are employed to depict the evolution requirements of the participants. In particular, we discuss the situation where maximum consistent changing subsequence is needed if there are inconsistent conflicts between changing subsequences. We also show how detecting algorithms could be taken in the collaborative evolution of medicine ontology. As a result, internal and mutual inconsistencies can be detected from change sequences. And if there are conflicts between the sequences, the algorithm will provide the maximum consistent changing subsequence as the evolution basis. The designed experiments verify our approach and achieve the expected results.