Electronics and Communications in Japan最新文献

Sign-indefinite linear quadratic differential game for stochastic systems by means of static output feedback (SOF) strategy is investigated. First, the saddle point equilibrium condition of external disturbance and control strategy is established based on stochastic cross-coupled algebraic matrix equations (SCCAMEs). Second, the numerical algorithms for solving the SCCAMEs are discussed. In particular, the difference between the existing algorithm and the proposed one is addressed. In order to show the validity for the several algorithms, a modified practical numerical example is demonstrated. In particular, it is shown that the optimality for the cost functional cannot be attained via the existing algorithm. Furthermore, it is claimed that the new proposed algorithm by combining the numerical algorithm that consist of stochastic Ricatti and Lyapunov equations with the Newton method is useful and reliable because the setting of the initial condition is quite easy task and fast convergence is attained.

The direction of magnetization in which the magnetic field becomes the strongest in the x-axis direction in the spherical coordinate system is used. Its magnetic field depends on the φ direction in the spherical coordinate system, that is, strongest at the top (φ = 0) and the bottom (φ = π), and the side (φ = π⁄2) becomes the weakest. Therefore, when segmenting, it was divided to include the top and the bottom parts. In addition, in order to make it an optimal segmentation, it is effective to make the range of the top and bottom divisions wide, the sides narrow, and the direction of magnetization close to the top and the bottom directions. By optimizing in this way, the magnetic field is larger than the equal division. For example, it was about 1.09 times stronger in three divisions. This was confirmed by the experiment. However, there is a problem that the demagnetic field in the center becomes strong by optimizing. The type of division which is strong in this problem is also introduced.

The purpose of this study was to clarify the effect of the presence or absence of upper limb movement on the propulsion direction body velocity (TPV) leaving the platform at kick start. The first trial (Standard trial) is a normal kick start, and the second trial (Lower trial) is the same as a normal kick start. The force from the upper limb movement at the time was set so that the start table was not applied, and the start movement calculated the 3D coordinates of the marker attached to the body by 3D movement analysis. As a result, in the movement speed at the time of leaving the platform, the standard trial had a significantly higher value in the propulsion direction and a significantly lower value in the vertical movement speed than the lower trial. In addition, since the standard trial had a significantly lower value in the jumping angle when leaving the platform, the role of the upper limb movement in kick start is to promote by making the jumping angle closer to the horizontal when leaving the platform. It was suggested that it may affect the directional velocity.

In recent years, the number of websites has been increasing, and with it, the number of similar services. As a result, UX is becoming more and more important to measure the differentiation of a website from its competitors, and UI plays a major role in improving UX. Website developers implement a development process called HCD to improve UI. However, in HCD, there is a gap between the perception of the evaluator and the developer, resulting in a lot of man-hours. In this paper, we propose a method for evaluating web pages using GUI operations to solve this problem. We let the evaluator of the web page edit the web page by mouse operation from the browser, and feedback the result directly to the developer. As a result of the experiment, we were able to discover problems with the web pages that could not be obtained by the conventional questionnaire. It also made it easier to design improvement plans, leading to a reduction in man-hours.

In this study, the electrical conductivity of low-volume samples was measured using a prototype microfluidic chip with electrodes. We were able to show the difference of electrical conductivity in the samples of saline solution (0.9w/v% NaCl solution) with sucrose. The correlation between the electrical conductivity and the viscosity evaluated by the capillary method was shown. This correlation was shown that it is possible to evaluate viscosity based on the Walden's rule with our chip.

Recently, gallium arsenide (GaAs)-based resonant tunneling diode (RTD) oscillators and indium phosphorus (InP)-based Schottky barrier diode (SBD) receivers have been studied in the terahertz (THz) band. The THz devices for practical use should operate at room temperature, be small in size, and have high output power. Therefore, this study was focused on gallium nitride (GaN), which possesses excellent material properties, such as wide bandgap characteristics and heteroepitaxy on Si substrates. The GaN-based oscillators and receivers are expected to be compact, operate at room-temperature, and act as a high-power device for the THz-band devices. However, GaN has crystal defects, which can cause instability in device operations. A double dielectric structure patch antenna composed of Silicon Nitride (SiN) and Benzo Cyclo Butene (BCB) with different dielectric constants was proposed to realize a GaN-based THz transmitter and receiver. The antenna characteristics were investigated using the Finite Difference Time Domain (FDTD) method. The results showed that the SiN has little effect on the radiation, whereas the BCB is strongly responsible for the radiation. Comparing the absolute gain between the double dielectric structure and the conventional structure using the SiN, it was confirmed that the double dielectric structure can improve the absolute gain.

This paper proposes a three-phase wireless power transfer (WPT) system with a three-phase-to-three-phase matrix converter. The proposed system directly converts power from an AC grid to high-frequency AC for WPT. The three-phase WPT system with the matrix converter is effectively expands the lifetime of the WPT system. A novel hybrid commutation method, which is suitable for the WPT system with a resonant characteristic, is proposed to avoid the commutation failure of the matrix converter. The strategy of the proposed hybrid commutation is based on an estimation of the current direction considering the resonant characteristics and elimination of commutation in the critical area. The proposed commutation method achieves an AC input-current total harmonic distortion (THD) of 4.7% with the resonant three-phase load without a current sensor on the high-frequency side. Furthermore, the proposed WPT system achieves a system efficiency of 88.2% at a load of 4 kW.

Epitaxial thin films of a ferroelectric perovskite-type oxide grown on single-crystalline SrTiO₃ (100) were transferred onto a flexible printed circuit (FPC). In the case that the thin films were directly adhered onto FPC using a copper foil double-coated conductive adhesive tape (Cu double-sided tape), serious cracking and exfoliation occurred during the transfer process. To avoid these damages, we have tried to insert a metal buffer layer with excellent ductility between the ferroelectric oxide thin film and the Cu double-sided tape. The platinum buffer layer was found to be appropriate to establish a crack- and exfoliation-free transfer process.

Information on fabric material is necessary in washing and ironing clothing. However, indication on a care tag may peel off or the tag may come off due to deterioration over time. Discrimination of the material from the fabric itself is not easy for a general person. Estimating the material of an object is one of the challenging tasks in computer vision. This paper deals with the identification of cloth materials using computer vision. We studied a method to discriminate the fabric material from the image of clothing taken by a smartphone camera. First, we investigated the relationship between image resolution and discrimination accuracy using a convolutional neural network (CNN). As a result, we observed that the accuracy changes with resolution and that the resolution at which the accuracy is highest differs depending on the material. Based on these results, we proposed a fabric material discrimination method using multi-resolution images by combining two CNNs. As a result of the evaluation experiment, the proposed method discriminated six kinds of fabric materials with 87.1% accuracy, and the accuracy was significantly higher than that of the comparison method without using multi-resolution images.

This paper reports a microfluidic device that allows us to measure the effect of local differentiation stimulation on embryoid bodies for the purpose of elucidating the role of the cell-cell interaction of iPS cells in differentiation induction. We developed the local stimulation device having two chambers separated by thin polydimethyl siloxane (PDMS) membrane with through-holes of the diameter smaller than single cell. Embryoid bodies of iPS cells are formed on the membrane and seal the holes, separating the aqueous environments of two chambers without leakage. This configuration brings localized exposure to chemicals for differentiation induction at the area defined by the holes. In this paper, we demonstrated the function of local stimulation using fluorescent solution.