Advanced Materials Research Vols. 694-697

Abstract: A straight pipe viscometer is proposed, which consists of the measuring sub-system and the data-acquisition and signal processing sub-system. The measuring sub-system include straight pipe, pressure transmitter, Coriolis flow-meter and slurry bump, and the data-acquisition and signal processing sub-system include single-chip processor, A/D converter, digital display, serial output port, drive circuit and so on. The measuring principle and working process of the straight pipe viscometer are analyzed. The measurement data and results are given and compared with test results of rotary viscometer in the same test conditions. The measuring accuracy is 3% at 5-150mPas, and the online measurement of viscosity is implemented.

Abstract: To meet the demand of joint torque measurement for a modular reconfigurable robot, a harmonic drive built-in torque measuring method was proposed. The robot and its joint module and the torque measuring principle were introduced. Based on the two-order ripple model, strains on the flexspline were then analyzed. A new measuing method based on double compensations was proposed. This method cancels out the first order ripples by individual channels, and then cancels out the remain ripples by weighted stacking the signals. The relationship between output signal and torque was given, and a new gain-tuning method was presented. Finally, a simulation was conducted. The simulation proves that the proposed torque measuring method is correct and of high accuracy.

Abstract: This paper presents a thorough review of optical voltage sensors (OVS) based on Pockels effect which contain many design schemes over the last decades. The principle and optical circuit of each scheme are described respectively, such as Integrated-optic Pockels cell, multi-segment OVS, quasi-reciprocal reflective OVS, dual-crystal OVS and OVS with special optical fiber. The main strengths and weaknesses in every scheme are analyzed. Finally, we summarized the remaining problems in OVS and the future research direction as well to improve the performance of OVS based on Pockels effect.

Abstract: As a new type of wavelength modulated fiber optic sensor, Fiber Bragg Grating (FBG) has been widely used in many fields. The majority of FBG demodulation device just detect the absolute wavelength, however, the change of wavelength is often concerned in actual use. For the purpose of realizing the FBG sensing system automated test, using the remote control port of the Q8384 spectrometer and the LabVIEW language to develop the remote automation testing system, and with the friendly interface of FBG sensing test interface. Realized the real-time monitoring and data storage capabilities by the processing of the collecting data and the FBG sensing remote test system is more practical.

Abstract: An artificial neural networks modeling (ANNs) for the nanoparticles of palladium (Pd) in the long period fiber Bragg grating (LPFBG) is proposed. A number of simulations have been performed to investigate the characteristics of the proposed approach. The trained and the predicted transmission are compared with the experimental data. The LevenbergMarquardt algorithm has been chosen as the main algorithm because of the lowest mean square error. The model of 20 neurons in two hidden layers shows a better fitting with the experimental data. A new predicted data at 10% H₂ concentration has been introduced using proposed ANN model.

Abstract: Microcolumn, a miniaturized electron optical system, is a powerful tool in manipulating electron beam for maskless direct e-beam lithography and miniaturized low voltage SEM for surface inspection, testing, and metrology. The basic parts of microcolumn are electron emitter, source lens, deflector, and Einzel lens. There are still several challenges in optimization of each component for better performance of microcolumn for aberration-free high quality imaging and large field of view. For the improvement of microcolumn, we developed a fabrication technique of making thin electrostatic lens using micro-electromechanical systems (MEMS) processes. Two types of microcolumns have been assembled by varying the spaces between Einzel lens-electrodes, and their performance have been evaluated for the comparison. The scan range is found to be increased with reducing the gap between the lenses and increasing working distance. The effect of the spatial gap on the scan range and image is analyzed through simulation study on the electric potential and field strength.

Abstract: Considering the problem of rearview mirror blind spot during driving, the paper studied and designed the blind spot detection system based on MMW radar. Radar was installed at an appropriate position on the detection target signal by transmitting, when another car enter the detecting area, the small alarm light beside A pillar would shine or alarm few times, to remind drivers careful change road. And the effect would not effect by weather or time. For the radar sensor application environment, triangle wave LFMCW can effectively solve the speed from the coupling phenomenon. The paper showed experimental and simulation data.

Abstract: With recent advances in mobile platforms, hybrid sensor networks are becoming very popular technology. Mobile sensors can dynamically move to monitor uncovered areas and thus improve the coverage quality. Due to the obstacles may exist in the monitor fields, mobile sensors need to find an obstacle-free moving path for mobile sensor movement. However, in practical, sensors are difficult to obtain the geographic information of obstacles. Additionally, sensors have resource constraints. Hence, this work proposed an obstacle-free and geographic-free dispatch scheme (OGDS) for mobile sensor navigation with low computational complexity. The moving path for mobile sensor dispatch has obtained by using the Dynamic Source Routing protocol (DSR) protocol. Experimental results reveal that the proposed scheme can be efficiently executed.

Abstract: In order to maintain the stability of precision of marine SAHRS, calibration should be made periodically. The paper proposed an online calibration method aided by star sensor.with the reference frame of boat frame on the beginning of calibration. By using the inertial attitude provided by star sensor as the attitude reference, the gyroscope constant drift can be estimated and attenuated. The difference of the integral of special force and projection of gravity on inertial space taken as the measurements,the zero bias of accelerometer can be calibrated.The method need not the disassembly of system,which is well suitble for online calibration.The computer simulation verify that the method can identify all the constant errors of SAHRS online not only in moorage but also on rocking base.

Abstract: GaN ultraviolet photoelectric detecting technique has important application value in the spacecraft, fire monitoring, ultraviolet communication and other fields. In this paper, p-type GaN samples were obtained after rapid annealing of GaN mixing Mg at 700~800°C. Then, p-i-n type GaN ultraviolet photoelectric detectors were fabricated on Al2O3 substrates by metal organic chemical vapor phase epitaxial deposition method. The devices have better rectifying behavior which can be demonstrated by the I-V curve. The response time of the device is 1.6µs and its higher responsivity is 0.95A/W.