Applied Mechanics and Materials Vols. 135-136

Abstract: Neighborhood based broadcasting methods for Mobile Ad Hoc Networks (MANETs) is a kind of simple and efficient broadcasting methods. Many neighborhood based broadcasting methods have been proposed in recent years, but there has been no comparison. How to select an appropriate broadcasting method is still a problem. The performances of three typical neighborhood based broadcasting methods (Flooding with Self Pruning, Scalable Broadcasting Approach and Ad Hoc Broadcast Protocol) were compared using Qualnet. Various scenarios with different network load and mobility were designed to evaluate these three methods. Delivery rate of packets, the number of rebroadcasting nodes and end-to-end delay were considered as the performance measures. The comparison charts show that Ad Hoc Broadcast Protocol is a good choice for the heavy load MANETs with low mobility, and Scalable Broadcasting Approach is more appropriate to the high mobility MANETs. The results can give a reference for the practical construction of MANETs.

Abstract: This paper introduces the concept of pervasive computing, architecture, outlines the key technology of pervasive computing, including: middleware, context-aware technology, database technology, user interface technology, embedded systems technology and adaptive Technology, points out the major issues facing pervasive computing.

Abstract: According to precise servo tracking system, proposes the establishment iterating control structure mode correspond to Taylor’s approximation valuation formula, make the system control structure to adapt to the accuracy of the system. On the basis of this structure, based on the analysis of the error transfer function, application error parameters determination and estimate the system accuracy.

Abstract: Based on the theory of diffusion, dynamic market environment is incorporated in the classical Bass diffusion model. The model which assumes that dynamic market environment variables simultaneously influenced the product diffusion at different level is proposed to examine the impact of dynamic market environment on product diffusion. The results of China mini passenger vehicle in recent 11 years indicate that the market environment acts an important role in product diffusion．Meanwhile，the empirical results also validate the effectiveness of incorporating dynamic market environment variables in diffusion model．

Abstract: The main goal of data-aggregation algorithms in wireless sensor networks (WSNs) is to gather and aggregate data in an energy efficient manner so that network lifetime is enhanced. In this article, we focus on QoS-based data-aggregation problems in WSNs. Firstly, we provide a definition of the different QoS parameters for data aggregation, such as energy efficiency, network lifetime, data latency and data quality. Then, we compare the different algorithms on each QoS parameter, describe the main features of each algorithm, and highlight the trade-offs between each parameter. Finally, we conclude with possible future research directions on QoS-based data aggregation in WSNs.

Abstract: In this paper, we propose a set of reduction rules of graphical representation in a workflow process model called RTWD net. The concept of synchronization processes is introduced for reducing net structure, and an algorithm of abstracting synchronization processes is presented. We can clarify the main structure of RTWD net model through reduction rules and abstracting its synchronization processes. Finally, the feasibility of the method is illustrated by a case study.

Abstract: The pavement image has three features: the background has similar statistical properties; cracks have less brightness than the background; cracks are connected to linear structure with much bigger area than impurities in the same image. Using these features, we present an algorithm comprising of image segment, breaking region connecting, and acreage comparison to extract pavement crack. Firstly, image segmentation using k-means clustering is implemented, and then the region with the minimum mean gray value is set as the initial extracted crack. The eight-connectivity cracks with small area are excluded to suppress interference and improve detection accuracy rate. Secondly, the minimum distance of every two non-connected crack regions is computed. When the distance is smaller than a given threshold, connect the two regions in the shortest possible path. Finally, morphology method is adopted to extract skeleton. Experimental results testify the effectiveness of the proposed algorithm in extracting pavement image cracks.

Abstract: The safety of the pipeline in use is tightly linked with the resident life and belongings. Reliable structural integrity and safety of gas pipelines under various service pressure events including defects should be warily evaluated. The reliability evaluation of gas pipelines is necessary to prevent risk. In this paper, Markov chain Monte Carlo is proposed to analyze the reliability of factors affecting gas pipeline operational condition in consideration of the character of historical data, the calculating processes of reliability prediction are provided in view of performance degradation characteristics of the factors.This paper takes corrosion as important factor affecting pipeline operation for example, calculates the reliability indexes of gas pipeline, studies the relation of failure rate and length/depth of corrosion pit ,operation time,etc. seeks weak links of system, and brings forward concrete and reliable measures to improve system reliability.

Abstract: The positioning accuracy can bring a great impact on inspecting defect for Aero-engine blade. The high or low pressure rotor of engine is generally driven by manual when blade’s defect is inspected. Frequently，False detection and missed happens due to match failure between two persons. Adopting a high-resolution, high-accuracy algorithm based on FPGA to design automotive equipment for high or low rotor . The Frequency range to step motor is 1Hz / s to 65536Hz / s, resolution is 1Hz,and positioning accuracy for blade can be up to 1mm.Resolving the questions of missing detectable rates made by manual during inspection in the paper, and increasing efficiency for inspection and the reliability of the experimental result. Experiment results show that this equipment can meet the challenge of the high-accuracy regulating speed for blade’s inspection.

Abstract: RT（X-Radiography Testing） is a very import inspection method for detecting engine blade crack, and the defect is identified by person distinguishing the film for traditional RT. The traditional method is involved in high mistake and missed examining rate and low efficiency. It is great significance to blade integrity and flight safety that the crack can be quickly distinguished. In the paper, adopting a adaptive segmenting algorithm based on OTSU to quickly distinguish the crack on the blade image, and it can definite the threshold facing different gray image, and can reliably inspect the cracks which detection rate was 98%. The recognition accuracy for crack can reach 0.16mm Simulation result verify that the method is very effective on adaptively segmenting the blade image according to the threshold for crack inspection