Improvement of Data Readout Disturbance Effect in 1T2C-Type Ferroelectric Memory

The data disturbance effect in readout operation was investigated in a 1T2C-type FeRAM cell array. Based on the analysis, a method for reducing the data disturbance effect is proposed and verified by SPICE simulation as well as experimental results. Current on/off ratio of about two orders of magnitude which is sufficient to distinguish stored binary data was maintained even under the maximum disturbance condition.     

Evaluation of progressive collapse potential of steel moment frames considering catenary action

This study investigated the effect of catenary action on the progressive collapse potential of steel moment framed structures. Non‐linear static and dynamic analyses of three‐ and six‐story model structures with and without bracing were carried out following the alternate path method recommended by the General Services Administration 2003. According to the non‐linear static push‐down analysis results, the contribution of catenary action and the progressive collapse potential of structures increased as the number of story and the number of bay increased. The effect of catenary action increased significantly in braced frames, in which the movement of beam–column joints were fully restrained until the tensile capacity of beams located both sides of the removed column reached their maximum values. The non‐linear dynamic analyses showed that the maximum deflection caused by sudden removal of a column decreased when the catenary action was taken into account. Copyright © 2008 John Wiley & Sons, Ltd.     

Progressive collapse resisting capacity of tube‐type structures

In this study, the progressive collapse potential of tube‐type buildings, such as diagrid and tubular structures, composed of lateral load‐resisting perimeter frames and internal pin‐connected gravity frames, was evaluated by nonlinear static and dynamic analyses. To this end, 36‐ and 54‐storey structures were designed as analysis models and progressive collapse analyses were carried out by removing first‐storey columns. According to the analysis results, the progressive collapse of tube‐type analysis model buildings occurred when perimeter columns corresponding to more than 11% of all member cross‐sectional areas were removed from one side of the structures. When the diagonals located around a corner were removed, the ratio was reduced to 8%. It was observed that the corner columns in the diagrid system helped prevent the propagation of member failure all around the perimeter. Copyright © 2009 John Wiley & Sons, Ltd.     

Special Wide Area Path Planning Method of an Autonomous Mobile Robot Using GPS

Using sensor and GPS to make a trajectory planning for the stationary obstacle,autonomous mobile robot can assume that it is placed at the center of the map,and from the distance information between autonomous mobile robot and obstacles.But in case of active moving obstacle,many components and information need to process since their moving trace should be considered in real time.This paper proposes mobile robot’s driving algorithm of unknown dynamic environment in order to drive intelligently to destination using ultrasonic and Global Positional System(GPS).Sensors adjusted the placement dependment on driving of robot,and the robot plans the evasion method according to obstacle which are detected by sensors.The robot saves GPS coordinate of complex obstacle.If there are many repeated driving,robot creates new obstacles to the location by itself.And then it drives to the destination resolving a large range of local minimum point.If it needs an intelligent circumstantial decision,a proposed algorithm is suited for effective obstacle avoidance and arrival at the destination by performing simulations.     

难处理金矿浸出预处理过程的FeS2-FeAsS-H2O系电位-pH图

难处理金矿中,金为微细浸染型嵌布在黄铁矿和毒砂的晶格中而不能被充分浸出.本文通过热力学计算绘制了298.15KFeS2-FeAsS-H2O系的电位-pH图,由图可知黄铁矿和毒砂均可以被O2等氧化剂分解.FeAsS的稳定区完全包含在FeS2的稳定区范围内,说明在酸性条件下毒砂比黄铁矿的稳定性差,更容易被分解.当电位及酸度...     

Microwave Properties of Mn Doped (Ba1 - x,Srx)TiO3Thin Films for Tunable Phase Shifter

Ferroelectric Mn doped Ba_0.5Sr_0.5TiO₃ (Mn-BST) films with/without BaTiO₃ (BT) buffer layer have been grown on (001) MgO substrates by a pulsed laser deposition to investigate electrical tunability at microwave frequencies. Structural properties and surface morphologies of the films were investigated using an X-ray diffractometer and a scanning electron microscope, respectively. Microwave dielectric properties of Mn-BST thin films with BT buffer were studied for reduction of dielectric loss and improvement of electrical tunability. Distributed analog phase shifters have been designed and fabricated on Mn-BST films with/without BT buffer layer to understand microwave dielectric properties. The differential phase shift of the phase shifter fabricated on Mn-BST film was 22° at 10 GHz with 80 V of applied dc bias voltage. In comparison, phase shifter fabricated on Mn-BST/BT multilayers exhibit 41° of differential phase shift at the same condition. This suggests that a BT buffer layer is for microwave tunable device applications. The phase shifter fabricated on Mn-BST/BT multilayers exhibit a low insertion loss (S₂₁) of ?1.1 dB, and a low return loss (S₁₁) of ?14 dB with a bias voltage of 80 V.     

EFFECT OF SILICON CARBIDE PASSIVATION FILM ON THE RESONANCE CHARACTERISTICS OF CANTILEVER

ABSTRACT

We have used silicon carbide (SiC) thin films as an insulating material of the PZT micro cantilevers for electrical and biological passivation. The use of SiC thin films as a passivation layer of the PZT microcantilevers is also seemingly viable to insure the high mass sensitivity as well as the stable passivation. In this study, we report the effect of SiC passivation layer on the performance of the PZT microcantilevers. The micromachined PZT microcantilevers having a structure of SiN_x/Ta/Pt/PZT/Pt were fabricated through MEMS processes. In order to improve the mass sensitivity and the passivation, SiC thin films of the high elasticity material were deposited on the cantilever using plasma enhanced chemical vapor deposition (PECVD) at the temperature of 400°C. Plane-strain modulus of SiC thin film was measured by nanoindentation. We observed that SiC thin films showed higher Young's modulus than Si and SiO₂. Before and after the deposition of SiC thin films, the end-tip deflection and the resonant frequency change of microcantilevers were measured by a confocal microscope and an impedance analyzer. It was confirmed that end-tip deflection of microcantilever was reduced by 13～18% through the deposition of SiC thin films, indicating the stress relaxation of the microcantilevers.     

Unbalance Response of a Super-Critical Rotor Supported by Foil Bearings—Comparison with Test Results©

This article compares theoretical and experimental results on the unbalance response of a super-critical rotor supported by two kinds of gas foil bearings. Analysis of the super-critical rotor is performed with viscoelastic foil bearings (VEFB) and conventional bump foil bearings and compared with early published experimental data. The vibration orbits obtained by theoretical investigation on the viscoelastic foil bearings (VEFB) and the conventional bump foil bearings are compared with the experimental vibration orbits of the super-critical rotor supported by both foil bearings. A numerical analysis program can calculate the static and dynamic characteristics of the elastically supported gas foil bearing using the measured stiffness and damping of the elastic foundation. After the stiffness and damping of both foil bearings are calculated using the perturbation method, vibration orbits of the flexible rotor modeled by the finite element method are calculated. Vibration orbits calculated by numerical analysis agree well with experimental data when the vibration amplitude is small and the rotating speed is below the bending critical speed. The numerical results also show that the enhanced structural damping of the elastic foundation reduces vibration near the bending critical speed.     

Friction and Wear Characteristics of TiN Coated Vane for the Rotary Compressor in a R410A Refrigerant©

HFC is a potential alternative refrigerant for CFC, which depletes the ozone layer. The rotary compressor has been widely used for refrigeration and air-conditioning systems due to its compactness and high-speed operation. R410A, an HFC refrigerant, is used in a refrigerator compressor, but its frictional characteristic is not established. In this study, the influence of R410A refrigerant on the roller-vane surfaces was studied, and friction and wear characteristics of the TiN coated vane were investigated. The friction and wear data were obtained with a specially designed high-pressure wear tester. A testing environment charged with HFC refrigerant more closely simulates the operating conditions of a real rotary compressor. In pure oil without R410A, wear of the TiN coated vane was larger than that of the uncoated vane. But when the refrigerant was dissolved in oil, wear of the uncoated vane was larger than that of the TiN coated vane. This showed that a TiN coated vane is good relative to wear resistance in the refrigerant/lubricant mixed environment. As the rotating speed of the frictional motion increased, wear increased. But in the high-velocity region, wear decreased because the boundary lubrication is changed into the mixed lubrication in the lubrication region. As the pressure grew larger, wear volume and coefficient of friction became larger. This is because the amount of the refrigerants dissolved in oil increased and the viscosity of oil dropped as the pressure increased.     

Effective color correction method employing HSV color model

This paper suggests a new algorithm to solve problems of the current retinex algorithm such as distortion of grey out and color noise due to the individual treatment of RGB channel and log function,and halo effect occurred by use of the Gaussian filter.The current retinex algorithm treats each channel in RGB space that brings a phenomenon to change the rate of RGB.To improve this phenomenon,the color information was fixed in the HSV color space,and retinex treatment was conducted against the V value,a luminance feature.Linear treatment was carried out to remove color noise occurred by the use of log function.S value,a saturation value was compensated in proportion to the change of V value in luminance to obtain a clearer image.The proposed algorithm was evaluated against the landscape images that had strong backlit phenomena,and it is proved to have a better performance than the current retinex algorithm,multiscale retinex with cdor restoration(MSRCR).