Applied Mechanics and Materials Vols. 303-306

Abstract: This paper introduces the architecture of wireless sensor networks, compares several typical routing protocols of wireless sensor network, and focuses on the research of directed diffusion(DD) protocol and geograohic and energy aware routing(GEAR) protocol. GEAR selects the next hop nodes based on the neighbor node location information, limiting the information diffused in the network in the appropriate location of region, which can effectively reduce the maintaining routing information needed for overhead, and form the energy efficient data transmission path, to achieve the purpose of extending the life cycle of the network. Related research work provides the reference for the future network construction.

Abstract: Sitting postures affect their safety in wheelchair for persons with the disability or the ender people. In this paper, it is explored the relationship between the pressure distributions and sitting posture; using density-based clustering methods establish the evaluation model. Real instance verify that the model can accurately predict the relations between pressure distribution and sitting postures.

Abstract: Recently, three-dimensional (3D) measurement technology has achieved a high level of satisfaction in various fields such as medical and engineering fields. However, most of three-dimensional measurement systems have some disadvantages. Once the geometric configuration of the system has been determined, the configuration must be maintained until the measurements have been completed. Another disadvantage is the existence of immeasurable area that inherently exists in a single image taken from a fixed angle. In this paper, a handheld three-dimensional thermo-sensing measurement system is presented. This system is composed of a three-dimensional measurement device and a thermographic device. To realize the handy scanning measurement, 3D magnetic sensor is attached on the image capturing devices. Since the movement of the image capturing devices is detected in real-time by the magnetic sensor, the immeasurable area can be reduced by free movement of the image capturing devices. On the basis of the presented mathematical model, this system is possible to detect not only the three-dimensional shape but also the temperature distribution of an object. Experimental results show the feasibility of the measurement system.

Abstract: Pyroelectric sensors based on PVDF polymers have great potentialities in the practical areas because of their great merits in the high converting efficiency from caloric or kinetic energy to the electric signal, as well as light-weight and flexibility. This work emphasized on the simulation of the PVDF pyroelectric sensor on the circuit level. The presented equivalent circuit model was simulated with the combination of the whole testing circuit in the environment of Multisim, so the simulated data could be comparable with the measured ones. And the validity of this PVDF sensor’s Multisim model was testified by the comparison with experimental data. Moreover, thermoelectric energy conversion was discussed by the extracted parameters in the equivalent circuit.

Abstract: Design and implement a distributed platform based on wireless temperature sensor network via mass data storage of distributed platform, distributed computing and machine learning etc., while using a wide range of WCDMA network system and the 3G network’s quickly transmission rate, the advantages of stable signal.The system include the distributed computing storage platform based on hadoop,Using WCDMA DTU and embedded technology to develope wireless remote temperature sensor module, design and implement the temperature data of prison acquisition platform based on web. The results show that using distributed storage platform and WCDMA network to develop temperature sensor module and using web to develop temperature acquisition system that solve the problem of low efficiency, slowly computation speed cause by mass data storage and large data analysis in the temperature sensor network.These all meet the current new requirements of data expansion.

Abstract: The photoelectric encoder can not be applied to the harsh environments with intensive vibration, moisture, oil and dust, and has the disadvantages of complex manufacturing crafts and high cost. To solve the problems above, a hall effect based tracking position sensor is proposed. Firstly, the magnetic signal reflecting the shaft velocity and position is converted into an electrical signal with the hall component. Then, the resolver-to-digital conversion is carried out by arctangent. And finally, the signals of shaft position and velocity are obtained.

Abstract: A digital closed-loop control quartz accelerometer with new structures is performed, which overcomes the disadvantages of restriction of measurement range and sensitivity of QVBA (quartz vibrating beam accelerometer). It has not only the same precision as QVBA in theory, but also large measurement range without reducing the sensitivity. The accelerometer is proposed to be used in large range and high-precision measurement of acceleration.

Abstract: A smart marine corrosion sensor, as a ship carried equipment, was developed by the authors to measure corrosion potential and corrosion current of materials in seawater. Measuring principle and characteristics of the corrosion sensor are described in the paper. This corrosion sensor, named FS-1, developed by the authors under the aid of 863 research project, had been used to investigate the seawater’s corrosivity in the autumn open cruise, which was performed by Science I Research Vessel in November 2009.

Abstract: This paper introduces the omnidirectional vibration sensor based on MEMS three accelerometer, which is used to solve the problem that the tradition vibration sensor cannot acquire multidimensional vibration signal effectively, on the background of underground distributed passive localization.It has MEMS accelerometer as the core detection unit, including three dimensional vibration detection unit, signal conditioning unit and power supply unit. It adopts the spherical shape ,which consists of Aluminum shell、Potting material of Epoxy resin and Multilayer circuit board. By means of finite element analysis and Field test, it shows that this sensor can effectively get omnidirectional vibration signal vector information, and the engineering application value is great.

Abstract: To improve the temperature stability, response speed and sensitivity of surface acoustic wave (SAW) gas sensor, the relationship between the sensing region of the resonator for SAW gas sensor and the sensitivity of sensor is studied, a specific resonator with big space topology structure is proposed. A SAW resonator with high temperature stability is investigated from the viewpoint of piezoelectric material, cut type and fabrication process. A nano-wire bundle based SAW gas sensor with big specific-surface-area is proposed.