考虑土、上部结构和桥台相互作用的桥台抗震性能研究

 在以往的桥梁设计中并不考虑基础提离和地基土屈服等土与桥台相互作用对桥台地震反应的影响。因此,为了研究桥台在地震中的抗震性能,采用Newmark时程分析方法对考虑土、上部结构和桥台相互作用的由扩展基础支撑的桥台进行分析。采用离散的质点–弹簧模型对土、上部结构和桥台系统进行建模。利用非线性模型,模拟上部结构和桥台的碰撞反应、桥台背部填土及地基土的弹塑性反应,并采用Winkler地基梁模型模拟地基土与桥台基础的相互作用。分析结果表明,桥台基础的提离作用可以减弱桥梁上部结构及桥台在强烈地震中的反应,减小桥台墙身底部在强震作用下发生的塑性变形,起到一定的减震隔震效果。同时,桥台底部土的屈服减小了传递到桥台底部塑性铰处的弯矩,进一步增强了桥台基础提离的效果。然而,由地基土屈服引起的永久性沉降也造成桥台基础的倾斜。因此,在桥梁的抗震设计中,必须考虑桥台基础的提离和地基土的屈服等土与结构相互作用对桥台抗震性能的影响。     

Detection of moving object by mobile stereo omnidirectional system (SOS)

Moving object detection with a mobile image sensor is an important task in robotics and computer vision, when considering the practical use of robotics in human environments. In this paper, we propose a robust method that detects moving objects in the environment using the omnidirectional depth information obtained by a mobile Stereo Omnidirectional System (SOS). In order to detect only the moving objects within the depth image that are obtained by a sensor in motion, we first estimate the ego‐motion of the sensor, and generate a predicted depth image for the current time from the depth obtained at the previous time by only considering the ego‐motion of the sensor. Then the predicted depth image is compared with the actual one obtained at the current time, and the inconsistent regions are detected as moving objects. When the sensor moves, occlusions will occur in the scene and they will cause false detections. However, these false detections can be suppressed by estimating the occlusion regions using the ego‐motion parameters of the sensor and the jump edges in the depth image. The effectiveness of the method is shown with experimental results for a real environment. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 152(3): 29–38, 2005; Published online in Wiley InterScience ( www.interscience. wiley.com ). DOI 10.1002/eej.20155     

Effects of Size and Distribution of Spheroidized Cementite on Void Initiation in the Punched Surface of Medium-Carbon Steel

Metallurgical and Materials Transactions A - In this study, we investigated the effects of the size and distribution of spheroidized cementite on the characteristics of a punched surface as well as...     

Conductive Cotton Fabrics Coated with Myristic Acid/Zinc Oxide Nanoparticles

This research mainly deals with enhancement of electrical conductivity performance of cotton fabrics using zinc oxide nanoparticles. The application of nano-zinc oxide/myristic acid onto 100% cotton plain fabrics was performed by dipping process. The effect of myristic acid and zinc oxide nanoparticles on cotton fabrics was analyzed by Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. Electrical conductivity, UV protection performance, and hydrophilic properties of the cotton fabrics were also investigated. The surface resistivity of the cotton fabric noticeably dropped off by applying nano-zinc oxide/myristic acid. Furthermore, electrical conductivity of the coated cotton fabrics was maintained till 15 weeks. Surface hydrophilicity of cotton fabrics decreased with increasing myristic acid content. The changes in decomposition temperatures and crystallinity can be ignorable after application of myristic acid/nano-zinc oxide.     

Organic heterojunction ambipolar field effect transistors with asymmetric source and drain electrodes

Ambipolar organic field effect transistors with heterojunction structures have been fabricated using a biphenyl-capped thiophene oligomer (BP2T) and a naphthalene derivative (GS1b) for p-type and n-type organic semiconductors, respectively. Asymmetric electrode structures with Au source and Al-Li drain resulted in better performances than that of a symmetric device due to improved electron injection by the low work-function drain metal.     

Hydrodynamic characteristics of a butterfly valve — Prediction of pressure loss characteristics

Investigation on fluidmechanic performance on a butterfly valve has been carried out. A practical valve model of a given thickness and a hub is used for the loss coefficient theory. A theoretical loss coefficient has been formulated from a contraction factor obtained by applying the generalized Borda mouthpiece theory.

Cavitation stages (such as cavitation inception, supercavitation inception, cavitation damage inception, choking cavitation) have been theoretically predicted from the valve loss coefficient. The cavitation prediction has been carried out by applying the free streamline theory, where the relation between the loss coefficient and the critical cavitation factor has been formulated. The results of the theoretical prediction equations agree well with the experimental results.     

Effects of Smart Charging of Multiple Electric Vehicles in Reducing Power Generation Fuel Cost

The high penetration of variable sources of renewable power generation will lead to operational difficulties in supply/demand balancing in the entire power system. The mass deployment of electric vehicles (EVs) and plug‐in hybrid vehicles (PHEVs) will also cause significant changes in electricity demand. Therefore, controlling and managing the charging time of EVs/PHEVs are effective approaches that are imperative for improving balancing in power system operation. We assumed travel patterns for EVs in a model of the future Tokyo power system and analyzed the power system loads, including the charging load of the EVs, under several charging control scenarios. We verified that charging time controls are substantially effective for reducing the fuel costs in the power system. Further, we found that load leveling under a multicar charging management scenario gave the best results in terms of the fuel costs in all cases.     

Optimum watermark detection of ultrasonic echo medical images

To prevent unauthorized access to a person's medical images, it is widely acknowledged that the security features of confidentiality, availability and integrity should be in place. This paper proposes the watermarking of ultrasonic echo images together with optimal watermark detection, in which pseudorandom noise is added to the images for integrity. The optimum watermark detection is the integration of the generalized Gaussian distribution (ρ‐GGD) and the Cauchy distribution. The results show that the proposed method gives good detection performance. The proposed method not merely achieves optimum detection using the Rao test but also leads to the highest detection probability with JPEG2000 compression. Compared with other detection methods, our proposed method exhibits better watermark detection performance even when the watermark‐to‐document ratio (WDR) is −50 dB. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Nondaily behavior detection monitoring system for elderly people based on bayesian network representation of omnidirectional vision sensor

This paper describes an unusual behavior detection system based on an omnidirectional vision sensor, as one of the important elements in realizing “Sensing and Robotic Support Rooms” for elderly people. Such support rooms are expected to be further developed in the future with advanced abilities to automatically recognize elderly people's actions and behavior patterns, to detect unusual patterns by using sensors, and to support their daily motions by using robotic manipulator control systems. The proposed monitoring system using an omnidirectional vision sensor automatically learns daily behavior patterns and detects unusual behavior patterns and actions by using the Bayesian network approach. The Bayesian network is constructed by using image feature values such as area and center‐of‐gravity values extracted from a captured image sequence, and the respective behavior patterns are represented as conditional probabilities. Unusual behavior patterns can be automatically detected on the basis of the low generation probability values. Experiments based on the investigation of elderly people's typical daily behavior patterns have shown the effectiveness of the proposed system. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 172(3): 42–51, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20990