Electronics and Communications in Japan最新文献

The effect of sheet- and film-type electromagnetic noise suppressors on differential mode (DM) and common mode (CM) transmission characteristics in two parallel lines was investigated. Simple two parallel microstrip lines with a Co-Zr-Nb film were used as a test bench. The transmission characteristics of DM and CM were measured by four-port network analyzer. The ferromagnetic resonance (FMR) and eddy current losses generated in the Co-Zr-Nb film were calculated by 3D full wave simulator, and the effects of these losses on the transmission characteristics were estimated. The results show that the transmission characteristics are different in DM and CM because the frequency characteristics of the losses are different according to the different FMR frequency in each mode. Furthermore, the feasibility of the application of the magnetic film as a frequency-selective CM filter is demonstrated by using the difference in frequency characteristics of loss of DM and CM.

This paper presents a formulation of an optimization of uncertain systems and the solution technique. The optimization under uncertainties is formulated as an optimization problem which includes unknown variables in equality constraints called system equations as well as in an objective function and inequality constraints. As countermeasures against the uncertainties, a min-max criterion is applied to the objective function and robustness criteria are introduced to the inequality constraints. By differentiating state variables satisfying the equality constraints from the decision variables, we reformulate the optimization problem based on the worst-case scenario of the state variables corresponding to the uncertain variables and we propose a “constraints-relaxation procedure” based method considering the equality constraints to solve the reformulated problem. In this method, a constraints-relaxed problem is solved corresponding to a finite number of samples of uncertain variables. Furthermore, a new sample of uncertain variables is sequentially generated corresponding to the inequality constraint which the solution violates most, together with state variables satisfying the system equations at the new worst-case scenario. Finally, the effectiveness of the proposed method is illustrated by numerical examples including robust AC optimal power flow considering distributed energy resources.

We have developed a tactile stimulation system that can apply air puffs locally to any two points on a skin's surface. This system consists of an air output device and a reaction recording device, both controlled by dedicated software. The air output device is equipped with a microcontroller ESP32, which can produce an airflow from two ports by controlling the intensity of the compressed air, the duration of its output, and the inter-trial time interval between applications. The reaction recording device is equipped with a push-button to record the subject's response when the air is applied to the skin. We verified the applicability of this system by a two-point discrimination test. In 14 healthy human subjects, the shortest distance at which they correctly answered that the given air was at two points was 35 mm. When we applied the air at 30 mm, the majority of the human subjects answered incorrectly that the air was only at one point when in fact it was at two points. This result was in close agreement with previously reported results obtained by direct skin stimulation methods.

Electrets were prepared by spin-coating the dispersion of fine silica powders, and their charge retention characteristics were investigated. Finer silica aggregates were formed on the PTFE surface layer by spin-coating the dispersed solution of fine silica powder than those formed by spray-coating colloidal silica. Electrets using fine silica powder also showed better charge retention characteristics than those using colloidal silica. Such an improvement in the charge retention might be due to the suppression of discharge in the excessive gap caused by coarse silica aggregates. Then, ECSs were fabricated using the prepared electrets, and their transmitting and receiving characteristics of airborne ultrasound were also investigated. The peak sensitivity of the ECS using a spin coating of fine powdered silica dispersion was slightly improved from those using spray coating of colloidal silica. On the other hand, the peak frequency and frequency band were greatly improved using spin coating of fine powdered silica dispersion. Therefore, ECS using fine silica powder is expected to be applied as a broadband airborne ultrasonic sensor.

Due to the optical fiber have a small diameter and it can propagate light efficiently, it is possible to realize ultra-compact remote sensors. We have invented to the fiber-optic pressure sensor utilizes magneto-optical effect with polarized light, ring-type interferometer and a magnetic material, in order to propose the pressure measurement system which can measure in vivo or in harsh environments. We have confirmed that the prototype sensor based on magneto-optical effect was possible to detect pressures in range of −4 to +40 kPa.

This paper addresses physical and chemical resistance evaluation of tactile sensors. We have developed cantilevertype MEMS tactile sensors embedded in the elastomer. In this work, we used a combination of silicone elastomer with excellent mechanical properties and fluoroelastomer with excellent chemical resistance. As a new embedding method for the sensor, we devised a method of embedding with PDMS with low creep and coating with a fluoroelastomer for surface protection. We further performed three evaluations to demonstrate the physical and chemical resistance of sensors. Consequently, using the devised method, we have demonstrated that the sensor with both physical and chemical resistance are feasible.

In this study, we have developed a new pen-type pulse wave measurement system to evaluate heart failure treatment based on cardiovascular information. In order to acquire minute pathological changes in diseases such as heart failure, the pen-type pulse wave measurement system is equipped with a high-resolution MEMS tactile sensor that achieves a displacement resolution of 0.4 μm and an input resolution of 50μN. This measurement system consists of a small sensor package, a pen-type measurement system, and a glass sensor package to enable physicians to measure the radial artery of men and women of all ages in a minimally invasive, rapid, and precise manner. Realizing this measurement system, simple and precise pulse wave measurement by direct measurement and measurement of pulse wave characteristics for individual differences has been possible.

It can be difficult for clinicians to correctly determine histological classifications of masses on breast ultrasonographic images. The purpose of this study was to develop a computerized classification method for histological classification of masses on breast ultrasonographic images using convolutional neural networks (CNN) with a ROI pooling that analyzes feature maps focusing on the mass region. Our dataset consisted of 585 breast ultrasonographic images obtained from 585 patients. It included 288 malignant masses (218 invasive and 70 noninvasive carcinomas) and 297 benign masses (115 cysts and 182 fibroadenomas). In this study, we developed a modified CNN model based on ResNet-18, in which the ROI pooling and two fully connected layers with a softmax function were introduced after the second and fourth residual block on ResNet-18, respectively. The proposed CNN model was employed to distinguish among four different types of histological classifications for masses. A three-fold cross validation method was used for training and testing the proposed CNN model. The average accuracy, sensitivity, specificity, positive predictive value and negative predictive value for the proposed CNN model were 81.7%, 91.0%, 91.2%, 91.0%, and 91.2%, respectively. Those results were substantially greater than those with ResNet-18 (70.3%, 83.0%, 87.2%, 86.3%, and 84.1%).

Since the nuclear disaster in Fukushima, Japanese soil scientists have tackled soil contamination problems due to radioactive cesium. For the radiation education based on the research results and outreach activities, we published a comic book and developed a digital application using iOS Xcode for Apple iPhone and tablet devices. This allows students to quickly understand why clay soil absorbed cesium and how to remove contaminated soil using educational mini-games. Through radiation education seminars and a conference, our application was evaluated and revised by school teachers.

Flattop beams are in high demand for a variety of applications, including uniform surface treatment, interference laser processing, repairing and skin therapy. In this experiment, we optimized the direction of phase grating to spatially separate the beam into extracted and residual components in the Fourier plane, and spatially filtered the components to form a square or hexagonal flattop beam with no wave-like structure inside and high edge steepness.