Electronics and Communications in Japan最新文献

We have demonstrated a wide range of hydrogen gas detection from 200 ppm to 100% at room temperature by using optical cavity type of sensor elements with polarization interference. This explosion-proof type of sensor element provides a hydrogen monitoring system in flammable environments for gaseous fuels.

Cancer has been the leading cause of death among Japanese since 1981, and many people die from it every year worldwide. While various measures have been taken to reduce the mortality rate of cancer, circulating tumor cells (CTCs) in the blood have been attracting attention in recent years. In the past, CTCs were detected by visual inspection by a physician or by an expensive machine, but these methods required much effort by the physician and required only EpCAM-expressing cells to be detected. In addition, detection by image processing has been used, but it has the problem that the area of interest is only a part of the area and there are many false positives. In this paper, we propose a two-step classification method that focuses on the shape and surface of cells. In the proposed method, multiple shape and surface features are obtained for four types of cells in blood images: Clusters, CTCs, Normal Cells, and Vertical Cells. Based on the features, cells are classified using a two-step Random Forest and their accuracy is evaluated. Furthermore, the effectiveness of the proposed method is demonstrated by comparing it with conventional methods.

A method for banknote identification has been developed. As a prerequisite for this process, an ATM stores records captured from accepted banknotes, including customer's information for identification. The proposed method is implemented when a counterfeit banknote is detected. The ATM identifies a record corresponding to the counterfeit banknote among the stored records, assisting in the identification of the customer who used it. This identification is carried out by exploiting characteristic differences between counterfeit and genuine banknotes. These differences are defined in terms of positions and magnitudes of variations. An experiment using simulated banknotes was conducted to assess the effectiveness of the proposed method. Additionally, another experiment involving digitally synthesized banknotes was conducted to determine the performance limits of the proposed method.

Single-walled carbon nanotubes (CNTs) are carbon materials with unique thermal, optical, mechanical, and electrical properties, with hollow cylindrical structures of a few nanometers in diameter. CNTs cut to about 10 nm (Ultrashort CNTs, US-CNTs) can spontaneously insert into lipid bilayers. Therefore, applications have been proposed to combine CNTs with lipid bilayers to give the membranes the properties of CNTs. However, CNTs interact with membranes to induce morphological changes in the membranes, which may hinder these applications. In this study, to investigate the effects, US-CNTs are exposed to lipid bilayer vesicles (giant unilamellar vesicles, GUVs), which are used as a model for cell membranes, and the changes in membrane morphology with each US-CNT concentration were evaluated by fluorescence microscopy. As a result, GUVs show morphological changes upon exposure to US-CNTs, eventually transforming into a multiple vesicle-linked shape. This result suggests an increase in the area and asymmetry of the GUV membrane. Based on these results, we have proposed a hypothesis regarding the mechanism of morphological changes induced in the GUV membranes by US-CNTs exposure.

Exposure to time-varying, low-frequency and high-intensity magnetic field (MF) induce electric field (EF) inside the human body, producing stimulus effects such as nerve fiber excitation or synaptic modulation. To measure such stimulus effects by low-frequency MF exposure in real-time, we developed a fluorescent recording system using optical fibers that is neither affected by the MF nor affects the MF distribution. In this study, a numerical calculation model composed of voxels with a 6.25 µm spatial resolution was developed. Using this numerical model, we evaluated the distribution of the EF generated inside three-dimensional neuronal tissue called neural spheroid, under 50 Hz sinusoidal wave, 300 mT (root mean square) uniform MF exposure. We also investigated the influence of the optical fiber on the electric field distribution in neural spheroid. As a result, MF produced an induced EF in the neural spheroid of more than 4 V/m, well above the theoretical threshold of synaptic modulation. These results indicated that our experimental system was suitable for the evaluation of the threshold of stimulus effects using neural spheroid.

A method for evaluating the degradation of edible oils using a contactless quartz-based capacitive detector is reported herein. Oils easily oxidize, resulting in loss of flavor and nutritional value. Therefore, it is necessary to determine oil degradation. We attempted to evaluate the degradation of edible oils by heat and light using this sensor. The results showed the degradation of heated and irradiated oil could be detected. This is due to the compound was formed during heating and irradiation.

Plasma behavior in cesium-seeded argon (Ar/Cs) and xenon-seeded argon (Ar/Xe) disk-shaped MHD generators are compared under almost the same working conditions using r-θ two-dimensional simulation. For both working gases, uniform plasma occurs at the optimum load resistance, and the power outputs are the same under an identical inlet ionization degree. For Ar/Cs, plasma is stable and uniform in the range of electron temperature of 4300–5800 K basically according to the linear perturbation theory. In the actual plasma in the MHD generator, however, the uniform plasma still can be maintained even at higher electron temperatures due to the low three-body recombination coefficient of Ar. For Ar/Xe, on the other hand, uniform plasma is maintained when the characteristic time of the electron number density is longer than the residence time of the working gas where the electron temperature is around 4300–8600 K, even though unstable plasma is suggested from the linear perturbation theory.

An electronic nose prototype based on the novel temperature-modulation technique is developed, where the heater voltage changes its amplitude and frequency periodically. The system comprises a sensor analog front end and a digital processing part including a heater voltage generator and a sensor data transmitter, where the digital part was implemented by a field programmable gate array. The fabricated prototype successfully generated the modulated heater waveform and synchronously acquired sensor responses at a sampling rate of 10 kHz. Whereby, sensor responses to the test gases of volatile organic compounds were collected. Gas classification was achieved with an accuracy of 99.6% based on the data obtained by the prototype, demonstrating the promising properties of the prototype as a compact and highly precise electronic nose.

The growth and development of embryophytes is deeply influenced by environmental stimuli, such as light, temperature, and soil nutrients. Understanding the mechanisms underlying the growth response of plants to environmental stimuli is crucial for agriculture. In this study, we examined the morphology of a flowering plant, Arabidopsis thaliana, using microfocus X-ray computed tomography (µCT), which enables non-destructive analysis of the external and internal structures of plants. Three-dimensional (3D) images of the plant, which were reconstructed from X-ray scanned data, clearly showed the shapes of its leaves, stems, and buds from any angle. At a higher magnification, the µCT also revealed the small hair-like structures called trichomes on the Arabidopsis leaf epidermis. However, motion artifacts found in the 3D-reconstructed images indicated that plant's growth rate was faster than scanning speed. Thus, scan parameters must be accordingly optimized. Additionally, CT-based 3D printing can be used to design micro devices that can be further used to monitor plant growth. These results suggest that µCT is a useful technique for analyzing morphology of growing plants.

A transformer plays a key role in electric power distribution system; therefore, when the transformer fails, several electrical components may get affected. As a result, diagnosing the deterioration of transformers is important for the management of electric power distribution system. The furfural content in the insulating oil of a transformer is widely used as an indicator of deterioration because furfural is generated by the decomposition of insulating paper. However, analyzing the furfural content is time consuming because of the requirement of a professional and the complexity of the diagnosis process. In this study, we propose a novel method for analyzing the amount of furfural in the insulating oil based on near-infrared spectroscopic data obtained using the developed portable spectrometer, which can be used for the on-site analysis at transformer installation sites. We selected wavenumbers with high correlation coefficients between the furfural content of oil and the spectroscopic data and estimated the furfural content by partial least squares regression. The results suggest that the furfural content can be analyzed in a few minutes using a small amount of oil through a portable diagnostic device.