Electronics and Communications in Japan最新文献

In this paper, we propose data-driven control for the case of that the structure of the ideal controller is unknown. In this case, it is natural to implement FIR typed controller. Here, we utilize FRIT for the case of FIR typed inverse controller. In general, FIR might have unnecessarily large number of its taps. To prevent it, we also utilize LASSO regression so as to realize FIR typed inverse controller in as less numbers of the tap as possible. Moreover, we also utilize data-driven prediction to determine hyper parameters required in LASSO regression. The validity of our proposed method is verified by using experiments.

In this paper, input-oriented virtual internal model tuning (VIMT) is expanded to non-minimum phase systems. Proposed method can tune the feedback controller and the desired transfer function. Compared to Fictitious Reference Iterative Tuning (FRIT), the proposed method can realize good controllers even when the time constant of the desired transfer function is small. The validity of the proposed method is verified via numerical simulation.

In this study, in an electret capacitor sensor (ECS), which is an electromechanical exchange device consisting of an electret sandwiched between two electrodes, ridges as spacers and grooves as gaps were formed in the PTFE (polytetrafluoroethylene) layer of the insulating electrode by laser ablation. The ECSs were then fabricated using PTFE electrets, and the charge retention and airborne ultrasonic wave transmitting and receiving characteristics were investigated. The charge retention characteristics of the ECS with laser-patterned insulating electrodes were slightly lower than those of the silica-aggregate electret. As the thickness of the insulating layer increased or the groove width decreased, the transmitting and receiving sensitivity increased significantly and then peaked and degraded at the measurements of transmitting and receiving. The ECS with the highest peak sensitivity obtained by laser patterning had a bandwidth comparable to that of the conventional ECS with silica aggregate electret, but the peak sensitivity was improved by up to 8 dB. Therefore, laser patterning could contribute to the improvement of ECS performance.

A wrist-watch type biosensing system for real-time sweat lactic acid (LA) monitoring was fabricated and tested. The system consists of a microfluidic LA biosensor, a carrier-flow supplying device, and a sampling device for transporting whole secretions at the skin surface to the biosensor by continuous flow of phosphate-buffered saline (PBS). The perfusion test of PBS onto the skin surface by using the sampling device resulted in less than 1% leakage frequency at the collection site. The carrier-flow supplying device was able to feed PBS regardless of the body angle. When the subject wearing the device performed resistance training (lateral raise, 20 repetitions, 12.5 kg dumbbells), the LA secretion increased from 2 µg/cm²/min to 16 µg/cm²/min in response to the exercise, and then recovered to the baseline. The setup time for the measurement was less than 60 s. This indicates that the wrist-watch device can readily measure LA dynamics on the skin surface under conditions of the subject.

This study aimed to test the efficacy of a mint-flavored mouthwash when it is used at bedtime for subsequent sleep in a field study setting, using a wristwatch-type heart rate (HR) monitoring devise. Using a within-subject experimental design, twenty healthy adults used three types of mouthwash having a different intensity of mint sensation (or water as a control) per one experiment night just before going to bed at their home environment, in a counterbalanced order. As for results, irrespective of the intensity of mint-flavored mouthwashes, the subjective score for “fatigue” and “refreshing” before sleep was decreased and increased, respectively. In addition, although a significant inhibition of HR decline in the sleep initiation period (0–30 min after bedtime) was observed with the use of mint-flavored mouthwashes compared with the control, the trend reversed subsequently as HR trended lower than for the control during 2–6 h after the bedtime. These findings suggest that the using mint-flavored mouthwashes at bedtime induces a positive mood before sleep and may improve physiological sleep. Moreover, this study illustrated the possible application and significant advantage of the use of wristwatch-type HR monitoring devise in a context of field study.

In this study, we developed a capacitive seating analysis sensor using a conductive textile for evaluating a Seating Motion. Physical burden on caregivers is a common problem at nursing care sites. Developing long-term caregiving skills can help reduce the physical burden on amateur caregivers. Several quantitative evaluation studies have focused on the skills of caregivers. However, such evaluation is highly expensive and require huge area because it involves the use of motion capture systems with several 3D cameras for dynamic motion analysis. In our previous study, we developed a conductive textile sensor for measuring the seating position of a care recipient in a wheelchair. The sensor could measure either seating body pressure or distance between the buttocks and the seat. The system can measure the care recipient's motion without requiring any motion capture system. We recommend using the sensor to evaluate the skills of caregivers; the sensor output can be used to determine the seating speed of the care recipient on the chair. Herein, we report the validity of the measurement system comprising a conductive textile–based capacitive seating analysis sensor for evaluating seating in nursing care.

We found that some signs of mild cognitive impairment (MCI) might be presented in a structure of a sentence and a relation between sentences talked by a man, and develop a neural network model which has an analogy with the hierarchical structure of speakers, topics, sentences and words in Japanese. We build our model based on 2-layered bi-directional LSTM, corresponding to words-sentences and sentences-topics hierarchy. As a layer corresponding to speakers, we use a linear classifier with self-attention. The test result shows a largely improved AUC, compared with another test by using the normal 2-layered bi-directional LSTM with TBPTT. The result also indicates that there are some characteristic patterns in a talk by an elderly person with MCI. We classify the character vectors of topics generated from our model through learning into clusters whose number is 1/10 of the number of persons in our data. Since these clusters have almost less than 10% or more than 90% rate of positive share, we conclude that we can develop a screening method based on a talk in Japanese by an elderly person in the near future.

In this study, we focused on acoustic emission (AE) as a method for quantitative evaluation of fermentation. Since bubbling in the culture medium and detachment of the medium during fermentation are considered to be phenomena similar to corrosion, AE could be expected to be detected. Therefore, we conducted AE measurements using ECS during fermentation of yeast in sucrose solution, fermentation of yeast during sake brewing, and fermentation of sawdust in a hot bath facility, and investigated the possibility of evaluation of fermentation process using electret sensor (ECS). AE was detected during the fermentation of yeast. The peak frequency of AE detected during yeast fermentation was widely distributed. Cumulative number of AE, however, showed a strong correlation with the decrease in sugar content during fermentation, indicating the possibility of quantitative evaluation of the fermentation state by AE measurement if a time lag is considered. In the measurement of AE from the fermentation of sake malt, a large amount of AE was detected from the lower part of the tank immediately after brewing, and the number of AE gradually increased in the upper part of the tank. These AE measurements suggested that even in top fermentation, the initial fermentation may occur in the lower part of the tank. In the fermentation and warm bath facility, AE during fermentation could be detected even in powdered media. Although the durability of the ECS needs to be improved under high temperature and high humidity conditions, it is expected to be able to monitor the fermentation process better than temperature measurements.

This paper describes the deposition of Nb doped vanadium dioxide (VO₂) films on a glass substrate by metal organic decomposition (MOD) and their thermochromic properties. The difference in thermochromic properties of VO₂ thin films on a glass substrate was investigated with and without a buffer layer of Hf0.5Zr0.5O2 (HZO). The phase transition temperature of VO₂ thin film successfully reduced from 83°C to 43°C on a glass substrate with a buffer layer of HZO. Without a buffer layer of HZO, the thermochromic properties of VO₂ thin films deteriorated comparing with a buffer layer of HZO. HZO buffer layer effectively suppresses the miniaturization of VO₂ crystallite size of thin film due to Nb doping. Moreover, it would block out the diffusion of Al, Na, and Ca impurity ions from a glass substrate and the partial oxidation of VO₂ thin films judging from XPS O1s spectra and XPS depth profile analysis. We conclude that the insertion of the HZO buffer layer is a useful technique for controlling the transition temperature of VO₂ for the smart window applications by MOD.

As a nonlinear control approach, a database-driven PID (DD-PID) controller has been proposed that uses distance calculations of an initial database to tune PID parameters. However, sorting operations are required in extracting neighborhood data from the database, which imposes a large computational load. Therefore, it is impossible to finish this computation within a restricted sampling period in control systems with fast response time and insufficient memory capacity. On the other hand, the cerebellar model articulation controller (CMAC) has advantages for these problems and has similar constructs to the DD approach. Therefore, this paper combines advantages of these two approaches, and proposes a CMAC-PID controller design based on off-line optimization of a database. Finally, a comparison with conventional off-line CMAC-PID controller and DD-PID controller through simulations are considered.