Mixing of two liquids injected simultaneously in a micro-mixer with a simple Y-shape flow path was clearly visualized by utilizing a chemical reaction of phenolphthalein to a strong alkali. When a thin aqueous solution of tetra methyl ammonium hydroxide and a thin ethanol solution of phenolphthalein were mixed in a micro-mixer, the color of mixed parts changed from transparent to red. For this reason, the mixed parts were clearly distinguished. Because the flow paths were narrow and Reynolds number was small, flows were laminar, and were not mixed easily. However, it was clarified that the laminar parallel flows of two liquids were gradually mixed by diffusion. By analyzing the differential equation of diffusion mixing, a simple relationship between the time and the diffusion distance was obtained. When this relationship was fitted to the mixing experiments, the fitting curves were well assigned to the experimental results. The diffusion coefficients calculated using the fitting curves almost agreed with data shown in literatures. Thus, two liquid mixing in a micro-mixer was clarified specifically.
Measurement instruments that can measure radio signal using high frequency band tend to be higher cost and lower resolution. This system using under-sampling measures radio signal using high frequency band by low sampling frequency and converts it to image signal of low frequency. In the result, measurement instruments that can measure radio signal using high frequency could be expected to be lower cost and higher resolution. In this paper, we show simulation results of wireless communication evaluation system using under-sampling at low frequency band. As a result, simulation result by real time sampling and it by under-sampling are good agreement.
This research aims at active detection of fog and smoke composed of micrometer/sub-micrometer order particles. Fog scatters light and causes poor visibility of the driver. Since poor visibility can cause serious traffic accidents, detection and measurement of fog is an important technique in road traffic. Detection of smoke constituted by particles as well as mist is also an important technique for rapid extinguishing of fire. In this paper, we focused attention on the phenomenon that particles composing fog and smoke scatter and attenuate near infrared light. And we examined active detection combining discrete near infrared light and a near infrared camera. As a result, it was shown that detection is possible in both fog and smoke.
This paper describes new phase noise measurement techniques in fully digital phase noise measurement system. In the conventional fully digital phase noise measurement method using one reference oscillator, the phase noise characteristic of the reference oscillator had to be superior to that of the DUT oscillator. Our method uses two reference oscillators and calculate cross-spectrum so that it is possible to accurately measure the phase noise of the DUT oscillator even if the phase noise performance of the reference oscillators are worse than that of the DUT. We show the proposed method is better than conventional method in the phase noise measurement.
Typical reflectometers have their own standards for measurement values, and they cannot evaluate a certain index each other because of lack of common understanding. Recently there is great demand to measure an absolute value of small reflection in optical communication field. We developed a specialized TD-OCT to evaluate an absolute value of reflection. TD type can evaluate the reflection value directly and linearly. The rotating optical path scanner was installed into the specialized TD-OCT to generate the optical path change of 20 mm. We specially arranged the 4-stage amplifier for the sensitivity of 100 dB. As a result, we got its good linearity of the reflection measurement results within the deviation of +/-3 dB in the range between 10 to 100 dB.
These days, no one can live without electricity and the power company must deliver the electricity both safely and continuously. In addition, power electronics technologies are adopted in many electric machines. With using the technologies, one can easily control the industrial electric machinery including the consumer electronics like televisions, is looking forward to saving energy, and can contribute to solving environmental problems. However, they have a point at issue that will generate the higher harmonics and give serious damages to the stationary devices, including the transformers and the capacitors for improvement of power factor, over the power delivery systems. Then, it is necessary to develop the system, which measures the power factor and harmonics and analyzes them. In this paper, the authors developed an analyzer for measuring power factor and harmonics in the power delivery system using a low cost single-board computer. Experiments have been carried out using the proposed system, and it is confirmed that the proposed analyzer has effectiveness.
A filter bank consisting of switches and band-pass filters is one method for configuring a spectrum analyzer pre-selector. A long-life switch with high isolation is key to this development. We propose a novel horizontal-moving waveguide switch designed for easy addition of ports compared to commercial rotating switches. The switch has a small gap between the fixed and moving parts with the gap surrounded by chokes. This configuration offers high isolation and long life. It also reduces the size of the filter bank. This paper describes two proposed switch prototypes for frequency ranges from 90 to 140 GHz and from 255 to 315 GHz. The measured switch isolation is better than 50 dB and the insertion loss is less than 3 dB for both prototypes.
I have observed sea clutter including a target (small ship) using an S-band radar with a frequency of 3.05GHz, a beamwidth of 1.8°, a pulsewidth of 0.5µs, and a pulse-repetition frequency of 1,600Hz. To investigate the sea clutter amplitude statistics, I introduce the Akaike Information Criterion (AIC). I have found that the sea clutter amplitudes obey the log-normal distribution with the shape parameter of σ = 0.385 for entire data and the log-normal, Weibull, and log-Weibull distributions with the shape parameters of σ = 0.379 to 0.505, c = 2.92 to 4.81, and c = 12.33 to 15.28, respectively, for data within the beam width of an antenna. The number of the smallest AIC (MAIC) of the log-normal, Weibull, and log-Weibull distributions to data are 3, 5, and 4, respectively, from 12 range sweep numbers. I have used the Weibull/CFAR (Constant False Alarm Rate) circuit which is modified a Cell-Averaging (CA) LOG/CFAR circuit. It is found that small ship is detected and sea clutter is suppressed with improvement of 24.83dB by Weibull/CFAR.
I have observed sea clutter using an X-band radar with a frequency of 9.41GHz, a beamwidth of 1.0°, a pulsewidth of 0.5µs, and a pulse-repetition frequency of 1,600Hz. To investigate sea clutter amplitude statistics, I introduce three-parameter Weibull distribution and the Minimum Description Length (MDL) principle, which is more rigorous comparison between the distributions with parameters of different number than the Akaike Information Criterion (AIC). I have found that the sea clutter amplitude obey the log-Weibull distribution with the shape parameter of c = 13.36 for entire data and the Weibull, three-parameter Weibull, and log-Weibull distributions with the shape parameters of c = 3.18 to 3.96, c = 4.44 to 6.68, and c = 8.70 to 20.48, respectively, for data within the beam width of an antenna. The number of best fit of the Weibull, three-parameter Weibull, and log-Weibull distributions to data are 6, 9, and 6, respectively, from 21 range sweep numbers.
We have observed ground clutter from rolled topography using an X-band radar with a frequency of 9.41GHz, a beamwidth of 1.0°, a pulsewidth of 0.5µs, and a pulse-repetition frequency of 1,600Hz. To investigate such ground clutter amplitude statistics, we introduce a compound distribution and the Akaike Information Criterion (AIC). We have found that the ground clutter amplitude obey the compound log-Weibull distribution with the shape parameters of c1 = 9.19, c2 = 12.37 for entire data and the compound log-normal, Weibull, log-Weibull, and gamma distributions with the shape parameters of σ1 = 0.544, σ2 = 0.139, c1 = 2.94 to 3.05, c2 = 3.15 to 3.48, c1 = 8.23 to 9.61, c2 = 12.81 to 59.60, and α1 = 4.32 to 4.99, α2 = 24.56 to 70.19, respectively, for data within the beam width of an antenna. The number of the smallest AIC (MAIC) of the compound log-normal, Weibull, log-Weibull, and gamma distributions are 1, 2, 17, and 3, respectively, from 23 range sweep numbers.
In stormy weather due to typhoon hitting the Kanto district, I have observed sea and weather clutter including a target (ship) using an S-band radar with a frequency of 3.05GHz, a beamwidth of 1.8°, a pulsewidth of 0.5µs, and a pulse-repetition frequency of 1,600Hz. To analyze the sea and weather clutter amplitude statistics, I have proposed new partial Q-Q plot, which is more rigorous fit of the distribution to the data than conventional Q-Q plot. The partial Q-Q plot is as follows : locate the maximum value on the histogram of observed data and find the point on Q-Q plot corresponding to the maximum value. Fit the approximate line to this point and the nearest ones on both sides by least squares method. Adding a point nearest these ones, fit it similarly. Repeat them and select the approximate line giving the smallest RMSE (Root Mean Square Error). I have found that the sea and weather clutter amplitudes obey the Weibull distribution with the shape parameters of c = 2.88 for entire data and c = 2.68 to 4.08 for data within the beam width of an antenna.
In recent years, because of increased carbon dioxide emissions problem, the air pollution has been attracting attention. For example, the exhaust fumes produce nitrogen oxide and sulfur oxide. Therefore, these gases should be detected and measured. In this paper, we propose a novel moisture-insensitive sensor consisting of a comb-shaped electrode on a Si substrate. We also suggest a new measurement method, using complex impedances, for distinguishing between NO2 and SO2 at low-concentrations. It is shown that propose oxidizing-gas sensor, fabricated on a Si substrate, is moisture-insensitive for humidity of 40% to 80%. Furthermore, we determine that it is possible to measure mixed gases in the range of 0.1-0.9 ppm for nitrogen dioxide and 0.6-1.4 ppm for sulfur dioxide owing to the difference in the complex-impedance change pattern.
The complex relative permittivity of distilled water selected as a material with a large relative dielectric constant is measured at C band using a condensing metal plate lens antenna and compared with the measurement value of the coaxial probe method. As a result, it is shown the possibility of measuring the relative dielectric constant up to 70.
Polymeric insulating materials such as epoxy resin are commonly used to electric power equipment. And additives and fillers are traditionally used to improve the mechanical, thermal properties, and sometimes electrical properties. To understand electric treeing properties, the time to breakdown is measured using a CCD camera. The average tree propagation speed in the sample with silica filler of 80 µm in size decreased with the increase of the filler occupancy ratio. On the other hand, the average tree propagation speed in the sample with silica filler of 48 µm in size increased with the increase of the filler occupancy ratio. It was considered that the increase in the effective length between electrodes and the field relaxation of tree tip were caused by the bigger filler size in the sample with silica filler of 80 µm in size. In the case of the sample with silica filler of 48 µm in size, it was considered that the tree propagation effect at the interface between the filler and epoxy which brought to faster tree propagation speed became dominant.
The performance of surface ionic conduction single chamber fuel cell (SIC-SCFC) prepared by the sol gel method was studied on electric characteristics due to the differences of the operating temperature and humidity, the electrode distance and electrolyte film depth, and multiple cells with the series and parallel connections. The SIC-SCFC was arranged the both anode of Pt and cathode of Au on the boehmite electrolyte. The open circuit voltage (OCV) of single cell achieved a maximum of 530mV in the dry gas mixtures of O2/H2=50% in room temperature operation, and but it became decrease as over 60%. The OCV was maintained the constant value between operating temperatures of 30℃ to 80℃, and but it was decreased sharply at over 90℃ because a humidity on the cell became lower as increasing operating temperature. Then, the cell property was improved to 120℃ by adding to the humidity of 70% using a humidifier. The electrode distance and the electrolyte film depth of SIC-SCFC found to be contributed to the reductions of the cell resistance and the surface roughness on the electrode, respectively. Moreover, the power property of SIC-SCFC was significantly improved by cell stacks comprised of the series or parallel connection of a cell.