Formation of Al2O3–GdAlO3 eutectic ceramics with a fine anisotropic structure in a flash event

An Al₂O₃–GdAlO₃ (GAP) composite with a fine eutectic microstructure was obtained through local melting and rapid solidification during a flash event. An AC field of 1 kV/cm at a frequency of 1 kHz was applied to a calcined Al₂O₃–GAP body at a furnace temperature of 1400°C to induce the flash event. The Al₂O₃–GAP body exhibited local melting through the current path. Solidification proceeded with the maximum cooling rate of about 140°C/s just after the power supply was turned off. Using this flash treatment, a refined eutectic structure with rodlike GAP phases in the Al₂O₃ matrix was obtained within 1 min. The interphase spacing of the obtained structure was approximately 170 nm, comparable with the finest Al₂O₃–GAP eutectic material obtained in previous studies. A flash event and subsequent rapid cooling can contribute to forming fine eutectic ceramics with a relatively low furnace temperature and short processing time.     

A framework for a feedback process to analyze and personalize a document vector space in a feature extraction model

In this paper, we present a framework for a feedback process to implement a highly accurate document retrieval system. In the system, a document vector space is created dynamically to implement retrieval processing. The retrieval accuracy of the system depends on the vector space. When the vector space is created based on a specific purpose and interest of a user, highly accurate retrieval results can be obtained. In this paper, we present a method for analyzing and personalizing the vector space according to the purposes and interests of users. In order to optimize the document vector space, we defined and implemented functions for the operations of adding, deleting and weighting the terms that were used to create the vector space. By exploiting effectively and dynamically the classified-document information related to the queries, our methods allow users to retrieve relevant documents for their interests and purposes. Even if the search results of the initial retrieval space are not appropriate, by applying the proposed feedback operations, our proposed method effectively improves the search results. We also implemented an experimental search system for semantic document retrieval. Several experimental results including comparisons of our method with the traditional relevance feedback method is presented to clarify how retrieval accuracy was improved by the feedback process and how accurately documents that satisfied the purpose and interests of users were extracted.     

On-chip polymerase chain reaction microdevice employing a magnetic droplet-manipulation system

An on-chip polymerase chain reaction (PCR) device employing a magnetic beads-droplet-handling system was developed. Actuation with a magnet offers a simple system for droplet manipulation that allows separation and fusion of droplets containing magnetic beads by handling with a magnet. The device consists of a reaction chamber channel and two magnet-handling channels for the manipulation of micro-droplets containing magnetic beads. Micro-droplets were placed inside a reaction chamber filled with oil and manipulated with a magnet. When a droplet containing NaOH and magnetic beads was manipulated towards a droplet containing phenol red, a color change was observed after fusion. Sample preparation was performed by fusion of droplets containing a forward primer, reverse primer, template DNA and PCR mixture, using a droplet containing magnetic beads. PCR amplification or RT-PCR was also successfully performed, with efficiency comparable to manual methods that use this device by placing it on a thermal cycler for amplification. With a magnetic beads-manipulation step, purification of amplified DNA was also accomplished by using magnetic beads as the carrier. The amplified DNA was captured on streptavidin conjugated magnetic beads using a biotinylated primer, purified by washing and digested for separation of the target DNA.     

Special purpose computer system with highly parallel pipelines for flow visualization using holography technology

We have designed a PC cluster system with special purpose computer boards for visualization of fluid flow using digital holographic particle tracking velocimetry (DHPTV). In this board, there is a Field Programmable Gate Array (FPGA) chip in which is installed a pipeline for calculating the intensity of an object from a hologram by fast Fourier transform (FFT). This cluster system can create 1024 reconstructed images from a 1024×1024-grid hologram in 0.77 s. It is expected that this system will contribute to the analysis of fluid flow using DHPTV.     

Continuous monitoring of aluminum corrosion process in deaerated water

A device was developed for the continuous measurement of the open circuit corrosion rate of aluminum in deaerated water from hydrogen pressure, resulted from the cathodic reaction. Corrosion rate of aluminum coated by the passive oxide film was examined with respect to the corrosion phenomena using this device. From the results, it was found that the corrosion rate was dependent not only on the deterioration of the film, but also on the formation of pits and of corrosion products on the film. Furthermore, the deterioration of the film was independent on the pH of the water. The pits were most probably formed by the evolution of hydrogen gas at the cathode underneath the film followed by the formation of .     

Oscillator-controlled bipedal walk with pneumatic actuators

The development of an oscillator controller for a bipedal robot with antagonistic pairs of pneumatic actuators is reported. Periodic motions of the legs switch between the swinging and supporting stages based on the phase of the oscillators. The oscillators receive touch sensor signals at the end of the legs as feedback when the leg touches the ground and compose a steady limit cycle of the total periodic dynamics of bipedal locomotion. The effectiveness and performance of the proposed controller were evaluated with numerical simulations and experiments with the hardware.     

双盘叶片轮水泥抹光装置结构设计

基于库伦摩擦定律,设计并建立了双盘叶片轮水泥抹光装置的三维模型,通过有限元软件Workbench对其进行静力学分析和模态分析,获得双盘叶片轮水泥抹光装置的整体应力云图、整体应变云图及前六阶固有频率和相应振型。结果显示:应力主要集中在与叶片轮相连接的主轴处、主轴和摆动装置连接的轴承箱处以及支撑轴处,最大应力集中在靠近伺服电机侧的配电箱中心处,最大值为59.534 MPa,远小于材料屈服强度235 MPa;水泥抹光装置工作频率在31.510、62.957和140.870 Hz时振幅最大。在此基础上,完成样机制作并进行了测试,样机实现了边行走边抹光功能,为后续结构优化提供了理论依据。