Abstract: In this paper, a long cylindrical multimode optical fiber sensor (OFS) based on multiple total internal reflections in heterodyne interferometry is proposed. The cladding of the sensing portions of the fiber sensors is removed, but dont be coated with any metal films. With the OFS the phase shift difference due to the multiple total internal reflections (MTIRs) effect between the p-and s-polarizations can be measured by using the heterodyne interferometry. Substituting the phase shift difference into Fresnels equations, the refractive index for the tested medium can be calculated. According to numerical simulations and experimental results, the long cylindrical OFS is with the best resolution of 0.0000028 refractive index unit (RIU). However, the OFS could be valuable for chemical, biological and biochemical sensing. It has some merits, such as, high sensitivity, high resolution, stability, small size and in real-time measurement.
Abstract: This research proposes a novel wireless RFID-based thermal convection type inclinometer by using non-floating structure without a cavity in the substrate. Four new ideas are presented. The first one is to make the device on a flexible substrate, thus it can save more energy than the traditional silicon. The second one is to integrate both an inclinometer and a wireless RFID antenna on the same substrate, such that it is a wireless device and very convenient for usage. The third idea is to fill xenon gas in the chamber with hemi-spherical or hemi-cylindrical shape instead of the previous one with carbon dioxide and rectangular shape. Because the xenon gas would not produce oxidization effect to the heater, so it would be more reliable. The fourth idea is to use non-floating structure instead of the floating one. The results by using floating structure with xenon and CO2 gases are studied the first; but the sensitivity performances are not good. Note that the sensitivities for the proposed non-floating structure by using hemi-spherical chamber filled with xenon and CO2 gases are better, and the one of the former is better than the latter by 70 %. On the other hand, the response speed (step-input of tilted angle) by using hemi-cylindrical chamber with xenon gas is the quickest, the average response time is 545μs, while the rectangular chamber filled with CO2 is the slowest, and the average response time is 848μs.
Abstract: In the applications based on Wireless Sensor Networks (WSNs) , localization is one of the most fundamental and important technologies if the accurate location information cant be determined, these application cant be accomplished. Then main idea in localization algorithms is that every unknown node in WSN can localize itself by position information from the landmarks or other nodes. in the last years localization is still a hot field and some new algorithms are proposed. In this paper, the localization algorithms are classified on the basis of the way to get position information, and a simple analysis is present. the paper are ended by discussing some open issues.
Abstract: Middleware supports programming abstract which facilitate the programmer task and bridge the gap between the application and the hardware. Middleware for wireless sensor networks (WSNs) can help bridge the gap and remove impediments. This paper designs GWSN, a middleware WSNs, whose architecture is composed of runtime support, application development kits, and software development kits. Runtime support in GWSN is the core of WSNs middleware and supports executing and maintenance of WSNs applications. Application development kits includes many basic function kits, such as display editor, rule editor, and workflow editor, which support the application development of WSNs. Software development kits provides easy-to-use application programming interface.
Abstract: This paper based on the principle of ammonia nitrogen is sensitive to the light which wavelength is 664nm, that is to say, there are, in statistic sense, significant linear relationships between these two parameters, design an ammonia nitrogen sensor based on LED and photomultiplier which is a new method for fast and simple Ammonia nitrogen detection.
Abstract: The piezoresistive silicon pressure sensor used in this work is developed by Technical University Berlin. It is mainly composed of a silicon-membrane and four implanted piezoresistors connected in form of a Wheatstone bridge. After wire bonding, the sensor was evaluated in a climate cabinet at different temperatures and pressures. The characteristic curve of the sensor shows its good linearity and strong dependence on the temperature. The sensor ́s temperature coefficient of sensitivity and zero shift were compensated using ASIC MLX90308. The experimental results show that this method of compensation accurately solved the sensors temperature dependence problems.
Abstract: FBG concentration chenical sensor with three layer structure is proposed in this paper. And through experimental study and reasoning calculation to verify the three layer structure of the optical waveguide model, so the sensitivity characteristic of the Bragg wavelength to the refractive index of chemical solution is obtained. And the relationships between the concentration and the shift of Bragg wavelength of sucrose, ethanol, and Nacl solution are achieved. Finally the shifts of the Bragg wavelength with the external concentration are obtained by experiments.
Abstract: Magnetoelectric (ME) materials have attracted continuous attention due to their potential applications in the fields of sensors, actuators, and transducers. A large ME coupling originated from a clamping structure was reported. ME coefficient of 0.95V cm1 Oe1 was obtained without amplifier at the planar acoustic frequency 60 KHz. The results show that large ME coupling can be obtained in the clamping structure through normal stress, and longitudinal ME effect could be better than transverse ME effect.
Abstract: One-step process of poly(styrene-co-maleic acid)(PS-PMA) nanofibers/QCM combination system was proposed as a novel ammonia detection in this study. Nano-sized PS-PMA fibers were deposited on the QCM electrodes via electrospinning technique directly, which can retain the original high specific surface area of PS-PMA nanofibers, and simplify NH3 detection process significantly. Experimental results showed that this new PS-PMA nanofibers/QCM sensor exhibited excellent ammonia sensing performances, such as rapid response and good reproducibility. Moreover, the carboxyl content on the surface of PS-PMA membranes was also determined as well as the specific surface area in order to study the structure-properties relationships.