An evaluation of surface asperity profile changes in truncation processes using optical interferometric microscope

The truncation process as running-in wear was applied to evaluate surface asperity changes as removal at the top of its asperity profile. The measurement was done using an optical interferometric microscope. Whole surface profile was measured by the microscope supported by the stitching technique. The specimen was relocated on the microscope utilizing Hirth coupling as a hardware technique. Data obtained from a truncated specimen were precisely relocated to the original untruncated specimen by computer software in three dimensions. Then the profile change was obtained by deducting truncated data from the original data. The profile change was calculated as removed volume. The volume changes are plotted against a sliding length. As the software relocation technique needs the unchanged profile of a valley part, the evaluation is limited to where the truncation height is higher than −1.28 sigma (the standard deviation of untruncated original profile height). The present research can detect very little volume change that cannot be measured by other conventional methods, such as the gravimetric method. The advantages of the present method are as follows. It is possible to compare the truncated surface profile with the original untruncated surface profile in three dimensions. Thus, the inclination of the truncation surface can be evaluated and any other local changes can also be assessed. From this information the profiles of truncated surfaces will be linked to functions, and new parameters for truncation profile will be presented.     

Theoretical analysis of atomic-scale friction in frictional-force microscopy

We perform a theoretical analysis of frictional-force microscopy(FFM) images of a cleaved graphite surface. The Tomlinson model with a single-atom tip is powerful for reproducing experimental FFM images. A mapping relation between the tip atom position and the cantilever basal position obtained by a stable equilibrium condition, gives a clear explanation of the physical meaning of FFM image patterns. This revised version was published online in June 2006 with corrections to the Cover Date.     

A Microcomputer System for Spatiotemporal Visual Receptive Field Analysis

A microcomputer system was developed to measure visual spatiotemporal receptive fields. The system performs three functions: 1) generation of a binary spatiotemporal white-noise stimulus, 2) acquisition of spike discharges from retinal ganglion cells, and 3) extraction of the linear part of the spatiotemporal receptive flelds by cross correlating the input against the output. We have applied this system to the measurement of the spatiotemporal receptive fields of cat and catfish retinal ganglion cells.     

The fracture energy and acoustic emission of a short carbon fiber reinforced nylon 66 composite

Two knee points which are found in the cumulative plotting of acoustic emission (AE) events on a semi-log sheet in a monotonically increasing tensile load system of the center notched carbon fiber reinforced nylon 66 composite (FRTP) are applied to the estimation of the energy value required for the beginning of the stable crack propagation, the one for the stable crack propagation and also the one for the final fracture. They have been examined with regard to the dependence of some mechanical properties of the material on the gauge length, the fiber content and the crack length to width ratio of the specimen. Correlations between the AE characteristic nature such as AE activity (the number of AE events per unit area) and the above energy values are also investigated with regard to the results of the fractographic measurement of the fracture surface. It has been found that the energy required for the stable crack propagation decreases with an increase in the crack length to width ratio and increases with an increase in the gauge length. However, for an unstable crack propagation, it decreases with an increase in the fiber content. The dependence of the energy value on crack length to width ratio disappears in the results for a 30% specimen and this value becomes constant.     

Evaluation method to determine radial accuracy of high-precision rotating spindle units

In this paper, the authors present a new technique, called the vector indication method, which computes and illustrates the radial error motion of a rotating spindle as the instantaneous vectors on a plane normal to a spindle axis. The radial error motion is measured by two sensors located perpendicularly to each other. A new algorithm is developed to obtain the instantaneous vectors of spindle axis displacement by digital processing. It is revealed that the behavior of displacement of spindle axis can be more precisely known by the vector indication method than by “the Lissajous' figure,” which is one of the conventional methods.     

High-speed and large noise margin tolerance E/D logic gates withLDD structure DMTs fabricated using selective RIE technology

The authors describe a novel design concept for enhancement (E) and depletion (D) mode FET formation using i-AlGaAs/n-GaAs doped-channel hetero-MISFET (DMT) and a novel self-aligned gate process technology for submicrometer-gate DMT-LSIs based on E/D logic gates. 0.5-μm gate E-DMTs (D-DMTs) with a lightly doped drain (LDD) structure show an average V_t of 0.18 (-0.46) V, a V_t standard deviation of 22.6 (24.9) mV, and a maximum transconductance of 450 (300) mS/mm. The V_t shift is less than 50 mV with a decrease in gate length down to 0.5 μm. The gate forward turn-on voltage V_f is more than 0.9 V, i.e. about 1.6 times that for MESFETs. This superiority in V _f, preserved in the high-temperature range, leads to an improvement in noise margin tolerance by a factor of three. In addition, 31-stage ring oscillators operate with a power consumption of 20 (1.0) mW/gate and a propagation delay of 4.8 (14.5) ps/gate. Circuit simulation based on the experimental data predicts 140 ps/gate and 1 mW/gate for DMT direct-coupled FET logic circuits under standard loading conditions. DMTs and the technology developed here are very attractive for realizing low-power and/or high speed LSIs     

Interior structure of a quality control center at the low‐voltage side considering power conditioning by SMES

The authors have proposed FRIENDS—Flexible, Reliable and Intelligent Electrical eNergy Delivery System—as a future electric power distribution system. The most important idea of FRIENDS is to install new facilities called Quality Control Centers (QCCs) between the distribution substation and customers. By controlling QCCs appropriately, various purposes of FRIENDS can be achieved. It is indispensable to design the concrete interior structure of QCC in order to realize FRIENDS. This paper proposes the interior structure and control methods of QCC from the viewpoint of power conditioning functions by energy storage system in QCC. In this paper, it is assumed that SMES is used as the energy storage system in QCC. The proposed interior structure is based on the concept of UPS (Uninterruptable Power Supply). In this paper, SMES is installed in the DC side of UPS. Further, this paper proposes control methods of SMES and PWM converters. The proposed control methods are used to satisfy various purposes, such as load fluctuation compensation, load leveling, and cooperation with dispersed‐type generator. Finally, the validity of these control methods is confirmed through transient analysis PSCAD/EMTDC. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 143(3): 20–28, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10056     

Effect of small cue–response separation on pattern discrimination in macaques (Macaca fuscata and M. mulatta).

Three studies with 17 macaque and 6 rhesus monkeys examined the effect of small cue–response separations on Ss' pattern discriminations. When training on a pattern discrimination with a cue–response separation was discontinued during performance at the chance level, there was no saving on the rate of learning a 2nd task (with identical cues but a different cue–response separation) relative to the performance of naive control Ss. By contrast, when training was discontinued at a performance level a little better than chance, there was significant saving on learning a 2nd task. After learning the 2nd task, a 3rd task with new pattern cues was learned, with marked saving on the duration of performance at the chance level. Results indicate that during the initial stage of performance at the chance level, monkeys do not attend to cues if there is even a small separation between the cue and the response site. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)