Advanced Materials Research Vols. 317-319

Abstract: Six-axis force sensors based on Stewart platform necessitate highly accurate, sensitivity and dynamic response. In response to this need, errors analysis and compensation of the force sensor are essential. In this paper, the measurement error generated by the upper platform deformation is discussed and evaluated. Furthermore, in order to improve the precision, a real-time compensation algorithm is proposed depending on the external force applied on the force sensor. Finally, a numerical simulation example is presented, which indicates that the precision is related to the stiffness of limbs directly and improved obviously by the compensation algorithm.

Abstract: The present work investigates diffusivity of hydrogen (H) in palladium-silver (Pd/Ag) over 300～1100K temperature range for Pd_100-xAg_x, X=0%～40% by using the Sievert Law. The silver in the Pd/Ag alloy has significantly higher diffusion as compared to pure Pd for hydrogen sensor, the addition of Ag reduces the critical temperature of α→Β phase transformations and also increases the solubility of H, and provides longer operational lifetime for hydrogen sensor. It was found that the diffusion coefficient of H in Pd/Ag alloy decreases with increasing Ag and with increasing temperature, the calculated diffusion coefficient of H in the Pd/Ag alloys were found to have a maximum at 24%～25% Ag.

Abstract: To manage the cotton field effectively, the quantitative classification method for cotton growth conditions would be researched based on LAI from remote sensing inversion in the field scale. The experiment was carried out in 2006-2007 in Xinjiang, China, and the eighteen cotton fields were selected as the standard observation station, the 255 quadrats data about LAI were obtained, and three vegetation indexes, including NDVI, PVI, and EVI, were used to estimate LAI by the correlativity between remote sensing and field measurement. The ideal LAI were proposed by the cotton cultivation experts when the cotton filed would realize the high yield, LAI from 2.8 to 3.2 was applicable at the first flowering stage in the research region. All of R2 on LAI estimation from three vegetation indexes got through the extremely significance test but the two models from PVI and EVI had the more excellent estimation ability when LAI was more than 3.0, and the overall estimation level of EVI is highest, RMSE and REPE is 0.67 and 0.12 respectively, and so LAI was retrieved by EVI in the paper. Through LAI inversed by the remote sensing data, the cotton growth conditions was quantitatively translated into three types of small population, classic population, and big population with LAI expert knowledge. The method classifying the cotton growth conditions was demonstrated in the research region in 2006 and 2007. The research results would contribute to the precision management on the cotton filed.

Abstract: In building a new On-line Multi-factor Monitoring System (OMMS) of Water Accidental Pollution Events (WAPE) based on the behavioral responses (BR) of aquatic organisms, the effects of physi-chemical factors (PF) such as temperature (T), turbidity (TUB) and pH on BR of Daphnia magna and medaka (Oryzias latipes) were discussed with Biological Early Warning System (BEWS). The results suggested that when T was lower than 5°C, BR of D. magna and medaka would be inhibited in 5 hours. If TUB was more than 50NTU, the behavior strength (BS) of D. magna would decrease to about 0.3 after 10h exposure, the effects on medaka would be much weaker in 24h than D. magna. If pH is lower than 5.5 or higher than 9, negative effects on BR of both aquatic organisms would happen in 15h. Therefore, a new OMMS was built for the purpose of environmental management of WAPE, which included BEWS and PF Monitoring System (PFMS).

Abstract: A sine wave with high frequency and high voltage is a key driving signal for EMCCD to realize electron multiplication. According to signal requirements, DDS technique based on FPGA is employed and then sine-formed code-stream is converted to low-voltage sine wave by a digital/analog device. Afterwards, filtering and high-voltage amplification are used to acquire the sine wave with high frequency and high voltage. For the high-voltage amplification, the transfer function of the circuit system is used to correct the circuit parameters, and at last linear amplified sine wave signal with the functions of phase adjusting and amplitude controlling is obtained. By using the sine-wave to drive the EMCCD, low light level imaging is well acquired by the camera and the relationship between sine-wave amplitude and multiplication gain is tested.

Abstract: Rocking-Mass Gyroscope (RMG) is a dual-axial symmetry vibrating mass gyroscope, whose operational modes are completely uniform, and values of frequency are equal. RMG has the potential to be the gyroscope with high sensitivity. Predicting the frequencies for the operational modes of RMG is critical. The natural frequency analytical formula of RMG is developed by using the assumed modal method and vector composition method. The FEM simulations and experiments validate the analytical formula. The sensitivities of natural frequency to different parameters are also analyzed. The presented results provide references for optimization design of RMG.

Abstract: The Sensor and Circuit of testing fabric infiltrate characteristic are designed. By testing capacitance variation ΔC between the sensor and two plates. It can detect the spread of area of the fabric seepage ΔS and determine the seepage rate of the tested fabric. The Calibration testing has been achieved for the Sensor and Circuit. The data is given out. The linear distortion of the testing Sensor and Circuit is smaller than 5%.It can meet the technical requirements of the testing seepage characteristics of textile products.

Abstract: This paper establishes a 3-D localization model and based on this model, it proposes a collaborative localization framework. In this framework, node that observes the object sends its attitude information and the relative position of the object's projection in its camera to the cluster head. The cluster head adopts an algorithm proposed in this paper to select some nodes to participate localization. The localization algorithm is based on least square method. Because the localization framework is based on a 3-D model, the size of the object or other prerequisites is not necessary. At the end of this paper, a simulation is taken on the numbers of nodes selected to locate and the localization accuracy. The result implies that selecting 3~4 nodes is proper. The theoretical analysis and the simulation result also imply that a const computation time cost is paid in this framework with a high localization accuracy (in our simulation environment, a 0.01 meter error).

Abstract: The temperature characteristics of semiconductor will make the zero point and sensitivity of the piezoresistive pressure sensor drift with the temperature,that is the main factor of the measurement error caused by pressure sensor.For high precision pressure detecting system, temperature drift has become the important obstacles when needing to increase the performance of the system,especially in the domain where the environment temperature changes greatly . Based on comparing the advantages and disadvantages with other methods ,this paper puts forward a kind of temperature compensation method which combines polynomial curve fitting and cubic spline interpolation, it can improve the performance of the system well.

Abstract: This paper presents the design and modeling of a permanent magnet spherical actuator which consists of a rotor with eight cylindrical permanent magnet (PM) poles and a stator with twenty-four air-core coils. Torque and dynamic model of this PM spherical actuator are formulated analytically. An optimal design procedure is proposed to achieve a high torque output, and significant design parameters of the actuator are discussed. As there is no effective method for three dimensional orientation measurement of the spherical actuator currently, a novel orientation measurement system is proposed. Finally, experimental works are carried out, and the experiment results demonstrate the effectiveness of the proposed orientation measurement system.