Papers by Keyword: Sensitivity

Abstract: Based on computer simulation, a new measurement pipe design with locally shrunk cross section is proposed for electromagnetic flow transducer. The efficiency of the magnetic field excitation circuit is effectively enhanced. The sensitivity of the transducer is increased. The transducer design is adopted in a battery powered electromagnetic flow meter prototype to reduce the power consumption. The prototype was tested. The feasibility of the proposed design was proved.

Abstract: Reliability of laminate structure is deeply influenced by uncertainties such as fiber properties, loads and design sizes. It is very difficult to evaluate the reliability and sensitivity of laminate structure because that laminate structure is anisotropic and the limit state function (LSF) is a high nonlinear function. In this paper, reliability and sensitivity are evaluated by using first order reliability method (FORM), response surface method (RSM) and Monte Carlo simulation (MCS). The study aims to find a numerical method to evaluate the reliability and sensitivity of laminate structures efficiently and accurately. An example of laminate with a large number of variables is analyzed. The results obtained by using different methods are compared in terms of efficiency and accuracy. It is shown that FORM is not accuracy, and RSM has a very good accuracy and efficient in terms of reliability, but the accuracy of sensitivity obtained by using RSM is not good enough.

Abstract: Structure damage identification is a hot research area internationally in recent years. Two damage identification methods based on sensitivity analysis are concluded. A three-tier steel frame structure model is established through utilizing ANSYS10.0, the software of finite element analysis. Through modal analysis of finite element, the frequency and formation before and after damage are obtained. The position of damage of the model is fixed by applying two damage indexes. It is indicated from the results that these two methods are effective for damage identification of the space structure of steel frame.

Abstract: A parametric model of a kind of low-voltage circuit breaker was set up by virtual prototyping technology software ADAMS, and the simulation of the low-voltage circuit breaker system’s dynamic characteristics was successfully run to confirm the parametric model. Because it was easy for contact heads to produce arc during closing, the power spring system was designed and researched in order to obtain the parametric sensitivities. Based on the difference of parametric sensitivities, the rotational angular velocity of the moving contact heads was regarded as the objective function, and the optimization design of circuit breaker power system was completed. Optimized system ensured reliable contact and shortened the arc time of the static and dynamic contact heads during closing, avoiding phenomenon as rebound repeatedly beating of the contact heads, continued arcing and temperature sharp rising, etc. The analysis had guide significance for improving the safe reliability and operating life of the low-voltage circuit breaker, and provided a good platform for the further produce development and optimization design.

Abstract: A novel evanescent field optical fiber sensor based on a solid-core photonic crystal fiber with large holes has been introduced and successfully fabricated. Experiments show that the ethanol solution of unit concentration causes 0.461dB attenuation of absorbance. The finite element numerical simulation of the grapefruit photonic crystal fiber has been performed. The energy overlap factor is 0.0039 when holes are filled with air, and that is 0.012 when holes are filled with water for the different effective refractive index of the holes. Besides, the relationship between the maximum power transmission and the refractive index is also studied and analyzed. This research provides helpful instructions to the study of evanescent field sensing based on the solid-core photonic crystal fiber with large holes especially for biochemical detection.

Abstract: We investigated sensing properties on NOx (g) of single tellurium (Te) nanoribbon-based nanodevices. The synthesized Te nanoribbons were aligned at well-defined locations using a lithographically patterned nanowire electrodeposition (LPNE) technique. The shape and length were feasibly modified by the designed lithographical pattern, and the width was tailored by the applied electrochemical parameters. Temperature-dependent electrical resistance was analyzed with as-synthesized and annealed Te nanoribbons in the temperature ranging from 15 K to 300 K, where the calculated thermal activation energies of as-synthesized and annealed Te nanoribbons were 35.7 meV and 19.2 meV, respectively. Room-temperature sensor performance of as-synthesized and annealed single Te nanoribbons on detecting NOx (g) was investigated as a function of the tailored concentration of NOx (g). Compared to a sensitivity of 16±2.9% on detecting NOx (g) of 10 ppm in the as-synthesized single Te nanoribbon sensor aligned between Au/Cr electrodes, the sensitivity of 21±3.2% on detecting NOx (g) of 10 ppm at room temperature was demonstrated by single Te nanoribbon-based sensor annealed at 200oC for 1 hour in 5 % H2/N2 (g). The effects of annealing on sensing properties have demonstrated the improved sensitivity in the annealed Te nanoribbons..

Abstract: The acetone gas sensor can be applied in the fields of the occupational safety, the prevention of fire accident and explosion in plants and the diabetic patients breathe analysis. The properties of the sensing materials and the sensing characteristics of the acetone gas sensors based on polyaniline (PANI)/Au/porous ceramic plate prepared by the microfabrication technologies and the electrochemical methods are studied in this work. PANI with stable sensing performance is prepared by a three-stage chronopotentiometric method onto Au/porous ceramic plate. The PANI nanowires are uniformly distributed on Au interdigitated electrode surface characterized by field emission scanning electron microscopy (FESEM).The sensitivity and the response time of the resistive acetone gas sensor are obtained to be 4.0×10^-3 % ppm^-1 and 3 min when using N₂ as carrier gas. Based on the same sensing electrode, the sensitivities of the gas sensor to mixed gas containing acetone are measured.Key words: gas sensor; acetone; polyaniline; sensitivity; selectivity

Abstract: In this work, we investigate the influence of position of electrodes on the sensitivity of hydrogen gas sensors based on TiO₂ thin films. We have prepared two types of sensors with platinum comb-like electrodes deposited on top and under the TiO₂ layer. Response of these sensors to hydrogen gas in the concentration range of 0 10 000 ppm at temperature of 350 °C has been studied. The sensors with electrodes placed under the TiO₂ layer showed two orders of magnitude lower sensitivity for 10 000 ppm compared to sensors with electrodes on top of the layer, but it was considerably increased when thickness of the TiO₂ layer was lowered. This gives a possibility to improve the sensitivity of gas sensors in which the electrodes must be placed below the sensing layer for their protection from harsh environment.

Abstract: The parameter modeling for the front double-wishbone independent suspension of a vehicle is set up in the development environment of ADAMS, and then, the kinematics simulation analysis for original design parameters are processed. The contribution of design parameters to the sensitivity of the double-wishbone independent suspension is analyzed and the influence of design parameters on the performance of the suspension such as the wheel alignment parameters is investigated. The optimal design for the suspension is carried on by using the experiment design method, which not only realizes the requirement for good wheel alignment parameters, but also improves the sideways displacement of wheel obviously.

Abstract: The evolutionary structural optimization (ESO) is used to optimize constrained damping layer structure. Considering the vibration and energy dissipation mode of the plate with constrained layer damping treatment, the elements of constrained damping layers and modal loss factor are considered as design variable and objective function, while damping material consumption is considered as a constraint. The sensitivity of modal loss factor to design variable is further derived using modal strain energy analysis method. Numerical example is used to demonstrate the effectiveness of the proposed topology optimization approach. The results show that vibration energy dissipation of the plates can be enhanced by the optimal constrained layer damping layout.