Advanced Materials Research Vols. 468-471

Abstract: This study developed a porous nano anodic aluminum oxide (AAO) based gas microsensor for detecting process carbon monoxide (CO) at room temperature. The small sensing microdevice has stable response with high sensitivity which includes porous AAO structures, gas sensing membrane, interdigitated sensing electrode, heater and temperature sensor. The tungsten oxide (WO3) sensing membrane covers AAO to enlarge total gas sensing surface area to enhance gas sensing response. The Pt interdigitated sensing electrode can also improve the sensitivity. The experimental results showed that the CO gas concentration sensitivity is proportional to temperature. As compared with the sensor without AAO, the concentration range of CO sensed by this microsensor is 100~1000 ppm, the gas sensing resistance change rate can be increased by 87.4 %.

Abstract: Mechanical properties of the joints have impacted on the whole mechanical characteristics. Coupling the joint characteristics in the modeling of the machine tool is an important problem in machine mechanics analysis. In order to solve the joint modellings in the assembled structure, this paper presents a new method to creat beam elements between two symmetrical nodes on the contact surface of the joint. The stiffness and damping matrices of the elements are valuated according to the characteristics of the joint. To validate the accuracy of the proposed method, the modeling of an assembled structure with and without the joints is obtained and some corresponding experimental investigations are implemented. The error between the simulated and experimental results of the finite element model is less than 8.8%, while the error of the contact model often used in the existing literatures is one times bigger than the proposed model.

Abstract: This paper introduces the components and structure characteristics of Loading arms Emergency Release Device(ERD). It establishes mathematic model and carried on theory analysis and test analysis of the ERD. The theory analysis is identical with test results so that it can provide the theory basis for optimum design.

Abstract: Urbanization in Southwest China, an extensive mountainous region, has been unprecedentedly rapid in the past two decades, particularly with the implementation of “Great West Development”. However, most present studies on urbanization of Chinese cities are limited to coastal area. Little is known about the urbanization pattern and underlying mechanism in this region. The main purpose of this research is to analyze the process of rapid urbanization and its impact on mountain environment, using Chongqing, the well known “mountain city” in China, as an example. Four time-series satellite images were employed to extract the landscape data. The result was assessed by several “landscape metrics”. The research also investigated how complex natural factors as well as socio-economic factors exerted influence on the urbanization. Based on examination of present landscape, a planning model which was believed suitable for mountain urban development was proposed.

Abstract: The intent of this survey is to provide general design and operating considerations for the safe and dependable operation of remotely operated hot cell equipment. Hot cell is an isolated shielded room that provides a controlled environment for containing highly radioactive and contaminated material and equipment. Operations within the hot cell are accomplished using master-slave manipulators and overhead crane or electro-mechanical manipulator systems.

Abstract: A type of closed-loop system model for capacitive MEMS accelerometer, with simple working clock , is presented in this paper. After establishing the force-feedback model and disgussing the magnitude of the feedback voltage, the readout interface IC for closed-loop detection is designed and the layout area of the ciruit is only 1435×2543 um². Post simulation results indicated that the circuit has large detection range, high accuracy and linearity, giving evidence for the validity of our model.

Abstract: This paper proposed a method to improve encryption card performance by multi-buffer mode. Compare original single-buffer mode, multi-buffer mode can reduce the time wasted that data transmission in PCI bus, can make encryption chip work at full capacity, can maximize the efficiency of encryption chip, and can improve performance of encryption card greatly. This paper also gives the scheduling algorithm to achieve multi-buffer mode. Finally, the result of comparing test proved that multi-buffer mode can indeed greatly improve the performance encryption card.

Abstract: In is paper precipitated silica is used in coated paper coating. It shows that the effect of different silica on properties of pigment dispersion is different. The dosage of silica influences the properties of pigment dispersion too. The viscosity of coating is higher than the corresponding pigment dispersion. The higher the viscosity of pigment dispersion is, the higher the corresponding viscosity of coating is. The more the dosage of silica is and the littler the particle size of silica is, the larger water retention value of coating is. When the precipitated silica is used in coated paper coating, the viscosity of coating is increasing. If precipitated silica coat paper, the whiteness of coated paper increases by 1%-2%

Abstract: Due to the shortcomings of long training time and slow convergence of BP neural network, this paper presents a new improved method that weight is no longer a constant but turned into a function of adjustable parameters. After the training of the improved BP neural network is completed, the network can map the nonlinear relationship between motor current, flux and rotor position. Based on the analysis of the unique structural properties of switched reluctance motor, this paper also proposes a method of greatly reducing the sample data to save computing time. Simulation results show that this method simplifies the complexity of the control system and improve detection accuracy, thus realize position sensorless detection of the switched reluctance motor.

Abstract: Isothermal fatigue (IF) tests were carried out on the gamma-TiAl alloy in the temperature of 500°C, 650°C and 800°C under mechanical strain control in order to evaluate its cyclic deformation behaviors at elevated temperature. Cyclic deformation curves, stress-strain hysteresis loops under different temperature-strain cycles were analyzed and dislocations configurations were also observed by TEM. The mechanism of cyclic hardening or softening during IF tests was also discussed. Results show that during the IF tests, The hysteresis loops were almost symmetrical above 600 °C, such as 650 °C and 800 °C; The hysteresis loops at the temperature of 500 °C generated two apparent asymmetry, one was zero asymmetry, the other was tensile and compressive asymmetry; Dislocation configuration and slip behaviors are contributed to cyclic hardening or cyclic softening.