Electronics and Communications in Japan最新文献

HF and LF/HF, which are parameters of the frequency domain of the electrocardiogram R-R interval time series, are general index of the autonomic nervous activity balance. Most wristwatch-type heart-rate monitors measure heart rate from sphygmograph and interpolate missing data. These are the causes of reducing the calculation accuracy of LF and HF. The purpose of this study is to propose a method for estimating LF and HF calculated from the ECG R-R interval time series from the heart-rate time series at 1-s intervals measured by a wristwatch-type heart-rate monitor. Six hundred and seventy data-set with a length of 120 s measured simultaneously with an electrocardiogram and a wristwatch-type heart-rate monitor during standing cooking operation, up-right standing, watching slide show in standing posture, and resting supine position were used. Seventy percent dataset were used for modeling, and remaining 30% were used for evaluating model. As a result, the coefficient of determination of LF and HF were 0.441 and 0.467, respectively in the one-variable polynomial regression model. The coefficient of determination of LF and HF were 0.557 and 0.644, respectively in the multivariable regression model, based on Random Forest and time domain indices.

The purpose of this study is to develop a line-of-sight input interface using the eye-glance input method, which uses a glance eye movement and method of estimating the eye-control movement by analyzing the image of the area near the eye-ball. The motion was discriminated by taking an image using the built-in camera of a smartphone to rapidly look at the four corners of the smartphone and calculate the moving distance of the eyeball, which was divided into horizontal and vertical components using the optical flow function in Open CV library. In the experiment, we obtained data by asking the subjects to look at the reciprocate of quick gaze movements at each of the four corners and the center of the screen. As a result of data analysis, characteristics of waveforms were obtained for the movements looking at the four corners, and we could determine which of the four corners the users were looking at. Furthermore, by distinguishing between camera shake and line-of-sight movement using the variance value, the discrimination rate was 90% or more even when held in the hand. It was shown that the Eye Glance movement can be measured with a smartphone as well as a PC.

In this paper, consecutive meals planning is formulated as a multiset iteration permutation problem that determines the optimal meals plan on a period consisting of consecutive days. In this problem, a meal is characterized by some characteristics such as food style, ingredient, cooking method, and so on. The evaluation function is defined by use of information entropy for measuring the appearance order of meal's characteristics on the meals plan. For optimizing this problem, Genetic Algorithms (GAs) with escape from stagnation of search are proposed. It is empirically shown that the proposed GAs with escape operation work better than the conventional permutation GA without escape operation for small and large size optimization problems.

In recent years, the demand for highly nutritious and functional vegetables has been increasing in the agricultural sector. In order to cultivate highly functional vegetables, it is necessary to adjust the nutrients in the soil, such as potassium ions, to an optimal state. Therefore, there is a need for a sensor that can measure soil ion concentration in real time in the field. In this report, we aim to develop an ion concentration sensor using Nuclear Magnetic Resonance (NMR). Since the sensor observes atomic specific behavior, it has the potential to measure the concentration of each ion species in soil where multiple ions exist. In this study, we aim to realize compact NMR and to establish a method for NMR measurement of water ahead of ion measurement. Using an NMR measurement system of our own design, we measured water and air. As a result, NMR signal spectra were obtained only when measuring water under resonance conditions, and resonance frequency of hydrogen atoms were successfully measured. We have established an NMR signal measurement method for measuring ion concentrations using a small NMR sensor that can be installed in the agriculture.

Membrane proteins play a critically important role, especially in molecular and cellular transport processes, which makes them the most prevalent drug targets and also to be a good sensing element for biosensing applications. However, the skill-dependent and manual fashion to form bilayer lipid membranes (BLMs) has limited their use for application purposes. Here, we introduce a fabrication technique of SU-8 microchannel suitable for microfluidic-based BLM formation and show a preliminary step of our ISFET-based BLM sensor. Making notches on the corners of a rectangular through-wafer hole etched in a silicon carrier substrate reduced the gap width between an embedded chip and the carrier as close as possible, leading to the gap depth of 4 μm. SU-8 microchannel on the chip-carrier assembly was directly fabricated by UV exposure through a bonded quartz lid and developing SU-8 through the fluidic ports drilled in the lid, without needing a sealing process typically causes an alignment mismatch or void formation. Finally, the capability to form BLMs was tested and proven by the successfully encapsulated fluorescent dye in microwells fabricated on the embedded chip. This paper is the first report of the successful formation of BLMs on a chip-in-carrier assembly by the microfluidic method.

This paper introduces a pulse-width modulation (PWM) method for a two-motor drive system that reduces the propagation of conduction noise to the power supply. This two-motor drive system consists of two motors with two inverters, each of which is connected to a common DC bus. The proposed method suppresses the common mode voltage ideally to zero by shifting the rise and fall times of the output voltage of each inverter. Our experimental results show that the rise and fall times of the output voltage can be synchronized even when the two inverters are driven at different amplitudes and frequencies. We confirm that the proposed method suppresses the propagation of conduction noise to the power supply.

To solve the last mile problem in rural areas, we deal with compact ride-sharing model. For reducing the computational cost, we use a simple GA method and compared the performance of the parameters. To simplify the problem, our algorithm use a simple linear distance and minimize the total traveling distance. A data set used for GA was based on the Inami area in Nanto City, Toyama Prefecture, that is a real case study region. The performance comparison experiment of the algorithm by changing parameters was carried out. Experimental results show that the algorithm is likely to give correct answers for up to four vehicles. It was also shown that the combination of population size and elite proportion for GA could reduce computational costs while ensuring accuracy. In addition, by ride-sharing was actually carried out using the obtained experimental result, it was shown that it could be applied to the actual route even if the calculation was carried out in the linear distance.

This paper developed a receptor cell model that mimics the receptor cells’ function of living organisms. The receptor cell model converts the signal input of the sensor into an oscillating pulse waveform. The oscillation frequency of the receptor cell model varies according to the sensory input intensity. First, the authors construct the receptor cell model by discrete circuit. The circuit was described using circuit simulation and compared with the experimental result. Also, we measure the frequency characteristics utilizing a pressure sensor and an optical sensor. The result shows that the receptor cell model could vary from 300 to 600 Hz according to the sensory input intensity. Second, the authors propose the receptor cell model by the integrated circuit. Experimental results showed that the receptor cell model's oscillation frequency changed from 370 to 890 Hz. As a result, the proposal receptor cell model could output the oscillating pulse waveform dependent on sensor input intensity.

Frequency characteristics for a converter are necessary to design circuit and control parameters and they are utilized, for example, for stability analysis by the impedance method. This paper proposes an automatic formulation and analysis method, which are based on a general-purpose simulation algorithm for the frequency analysis of an averaged power converter, based on node-connection and model characteristic information of circuit and control elements. The general equation formulation method is extended to be able to include circuits controlled in αβ frame and characteristic expressions with αβ or dq frame. As the first application example, a three-phase grid-following inverter with a digital sinusoidal controller based on the complex vector theory in αβ frame is analyzed for the frequency characteristics of the output admittances. The characteristics are utilized for stability analysis by the impedance method and the inverter is assured to have passive characteristics and to be stable. As the second example, a three-phase inverter is analyzed for its αβ and dq impedances. The proposed method is investigated for the computed results and it is validated.

In this paper, we report the development of time-delay analysis method of inductance and capacitance for microfluidic circuit. The sensor used in this method is composed of the sensing inductor (SI) and the sensing capacitor (SC) with a microfluidic circuit. This sensor measures inductance and capacitance in a time difference by delaying with microfluidic circuit. We confirmed that SI and SC have different responses to conductive and dielectric solution. This research is expected to be applied to the combined analysis of liquid samples.