Applied Mechanics and Materials Vols. 336-338

Abstract: Study has shown that clustering in Wireless Sensor Networks can provide well scalability and robustness. Recently, mobile collector (MC) is exploited to achieve energy saving and reduced latency. In this paper, we propose a mobile data gathering protocol using clustering and controlled mobility techniques. First, we formalize the clustering based approach and its requirement, and then propose a heuristic algorithm aimed at minimizing the number of clusters. After the cluster heads (CHs) are determined, protocol produces MC’s tour along which MC gathers cashed data in CHs in sequence. Simulation analysis shows that the number of CHs is less than other similar schemes and the tour length is shortened, accordingly.

Abstract: Traditional events in WSN monitoring are usually localized based on beacon nodes. But due to the cost of this kind of node is hundreds times more than an ordinary one’s, localization algorithms can't ignore the sparse beacon nodes problem. In this paper, a novel event localization method based on mobile agent is proposed. By using the mobile agent which can dynamically enter and exit a network and autonomously clone and migrate themselves in response to environmental events, the proposed algorithm moves the processing function to the nodes in event area and identifies the boundary of the area by two-neighbor graph algorithm. Then the accurate location of event can be got and the approximate location where the event happens will be reported. Extensive simulation shows that the proposed method exhibits better performance in terms of energy consumption and the packet delivery ratio.

Abstract: The pressure responding theoretical models are got for two intrinsic Fabry-Perot interferometric fiber pressure sensors fabricated by single mode and multimode fibers with different diameters. The pressure response curves are simulated by Matlab programs. The analysis showed that the sensitivity changing situation is different for two structures. The big size structure has a critical point of sensitivity. Higher sensitivity can be got by two structures, but the small size structure is more attractive than the big size structure.

Abstract: In order to solve the problems that measuring efficiency is low and measuring precision is low dependent on the maintenance man to test by manual work, a universal high precision tester of attack and slide angle sensor is proposed. The measuring efficiency has improved through the electronic spirit level that measures the attack and slide angle fast and automatically and reads data automatically. The universal property and expansibility is realized by the design method that the software and test data are designed separately. The tester in this paper is fit for the fast maintenance requirement of the attack and slide in the army, and this method has certain reference to construct other electronics tester.

Abstract: The combination of Inertial Navigation System (INS) and Global Positioning System (GPS) provides superior performance in comparison with either a stand-alone INS or GPS. However, the positioning accuracy of INS/GPS deteriorates with time in the absence of GPS signals. A least squares support vector machines (LS-SVM) regression algorithm is applied to INS/GPS integrated navigation system to bridge the GPS outages to achieve seamless navigation. In this method, LS-SVM is trained to model the errors of INS when GPS is available. Once the LS-SVM is properly trained in the training phase, its prediction can be used to correct the INS errors during GPS outages. Simulations in INS/GPS integrated navigation showed improvements in positioning accuracy when GPS outages occur.

Abstract: A novel horizontal sensitive inertial micro-switch with low g value was proposed and simulated in ANSYS, and was fabricated on quartz substrate based on non-silicon surface micromaching technology. Due to this special design, the micro-switch has a very good horizontal unidirectional sensitivity. The contact effect is improved by a modification of the traditional design. The flexible contact between the proof mass electrode and fixed electrode prolongs the contact time and reduces the rebound effect. The contact time is about 100μs under a half-sine wave shock with a12g peak value.

Abstract: The high power and low frequency electroacoustic transducer plays a very important role in the underground acoustic telemetry system used for petroleum industry. How to realize electroacoustic conversion technology with the giant magnetostrictive materials was studied in this paper. The principles and methods of how to design it were proposed and the experimental verification was achieved. Results show that the electroacoustic transducer based on giant magnetostrictive materials features high-power and low-frequency output, high conversion efficiency, high temperature resistance, and excellent performance. It can completely meet the needs of the downhole acoustic telemetry system.

Abstract: In a solar MCAO system, the formula of isoplanatic angle gain multiples was derived and the best conjugate height of Hefei region was thoughtfully discussed. The results show that the isoplanatic angle gain varies with the conjugate height and the seasons. The isoplanatic angle gain of the three conjugated system is much superior than that of the double conjugated system.

Abstract: In order to thoroughly reflect the underground deformation of rock mass, in this article, a sensor system which study on the landslide is invented and the reliable fitting formula based on the experimental data is produced. In first part, we briefly introduce the fundamental principles and measuringways of the instrument, then describe the whole effective monitoring process, and in the data processing, finally obtain the efficacious fitting formula by analyzing basic steps of Levenberg-Marquardt algorithm and utilizing this algorithm to fit experimental data. The experiment demonstrates that the real-time underground displacement measurement is practical and can be applied to analyze early deformation of rock mass and warn the unstable situation.

Abstract: To apply vector hydrophone to deep-sea detection, a calibration test of the vector hydrophone under different hydrostatic pressure was taken in the national defence underwater acoustics calibration laboratory. The effect of the relative sensitivity changes between channels on the vector hydrophones direction finding and zero-inhibition performance is explored, and the principle model for the influence of the directivity deviation on vector direction measuring is established. Meantime, the phase compensation between channels is found to be frequency-independent. The omnidirectional method is proposed to compensate the directional rotation. As a result, the influences of the hydrostatic pressure on direction finding are effectively reduced.