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Sub-seafloor exploration is an important area of biological and geological research, and often requires samples of seafloor mud to be recovered. The minerals and marine sediments trapped in this mud are also potentially valuable resources. However, seabed exploration has been limited by the complexity and cost of the traditional equipment used. Wide area exploration can be made possible by deploying...
We present a comprehensive study of electro-optical frequency mapping (EOFM) and probing (EOP) on NAND and NAND-like structures with different sizes. Our main objective was to find out, if it is possible to detect single dysfunctional transistors in a NAND structure smaller than the laser spot just by means of the optical signal. We further investigate the impact of parasitic laser voltage signals...
In this study, we developed a wall-climbing robot for airplane body inspection. To move on airplane body, the robot needs to move on walls and curved surfaces. A traveling-wave-type, omnidirectional wall-climbing robot that uses magnetic force to adhere could move on such a wall and curved surface. However, magnetic force cannot be used to adhere to airplane body. Therefore, we developed a wall-climbing...
In this study, we developed a 4-degrees of freedom (DOF) force feedback device independent of its operational component comprising pneumatic artificial muscles and magnetorheological clutches. Research and development of force feedback devices is becoming popular in fields such as entertainment, remote operation, and rehabilitation. These areas of research are related to virtual reality and augmented...
In recent years, ventilation equipment has been installed in various structures to draw in outdoor air and circulate indoor air. These ventilation installations have pipes (ducts) through which air flows. If dust accumulates in a duct, it will be carried indoors by the airflow. Dust adversely affects human health, and so these ducts must be cleaned regularly. However, the existing cleaning methods...
We have developed an excavation robot for lunar-subsurface exploration. This robot moves using a mechanism based on the peristaltic crawling of earthworms, which can move stably. In our previous study, we demonstrated that the robot can excavate down to 938 mm using this technique. However, it can only excavate in a straight configuration. If it can excavate while curving, its exploration range would...
If pipes with narrow diameters are not well inspected, preventing accidents become difficult. Therefore, we developed a pneumatically powered earthworm-type robot for Half-inch pipes (each having an inner diameter of approximately 16 mm); these pipes are extremely difficult to inspect. When the robot travels for a long distance, its speed significantly decreases. When the movement distance of one...
Ultrashort pulse fiber lasers (FLs) are required to have higher power to achieve high quality laser processing of difficult-to-cut materials such as carbon fiber reinforced plastics (CFRPs). Our present work develops an all-fiber coherent addition system to achieve a high power ultrashort pulse FL beyond pulse-power limits due to nonlinear effects in rare-earth-doped fiber [1]. Coherent addition is...
SiC devices are expected to operate at much higher temperature than Si devices. However, commercially available SiC devices are limited to the temperature almost same as Si devices. In order to operate SiC devices at high temperature, it is necessary to improve package technology and to design SiC devices properly for high temperature. In this study, robustness against thermal runaway of SiC-SBD is...
The transients generated by drives based on pulse width modulation (PWM) have adverse effects on the insulation system of rotating machines, especially the stress grading (SG) system used in the endturn region. The surface corona inception voltage on SG system under repetitive impulse, 1kHz sinusoidal, and 1kHz square voltages was measured using a photomultiplier connected to optical fiber bundle,...
Ultraviolet nanoimprint lithography (UV-NIL) has become one of advanced pattering methods for fabrication of micro- and nano-structures over several inches by replication with designed mold patterns at high throughput and low cost. For practical application of UV-NIL, it is essential to eliminate bubble defects and to make residual layer thicknesses (RLTs) of a fabricated resist pattern uniform after...
We have developed an earthworm-type 25A pipe inspection robot using a pneumatic drive. However, the developed robot had a low locomotion speed. This was due to the fact that the contraction amount of the pneumatic artificial muscle used for driving the actuator of the robot was small. To resolve the problem and increase the amount of movement of the robot, an extension actuator to extend in the axial...
To investigate the miniband and carrier transport properties in the superlattice structure embedded in the p-i-n GaAs solar cells, photoreflectance, photoluminescence, and photothermal spectroscopies were adopted. Two critical energies corresponding to the energy differences between mini-Brillouin zone edges were estimated for thinnest quantum barrier thickness sample by PR. From the PPT and PL, only...
Excessive heat generation and occurrence of partial discharge have been observed in end-turn stress grading (SG) system in form-wound machines under PWM voltage. In this paper, multi-winding stress grading (SG) system is proposed as a method to change resistance of SG per length. Although the maximum field at the edge of stator and CAT are in a trade-off relationship, analytical results suggest that...
A ceramic-insulated ball-anode (CiB) element that consists of a ceramic insulator, cathode lines, ball-shaped anodes, and anode lines was developed, and an irradiation experiment was performed using a Cf-252 neutron source. An electric field simulation of CiB element was conducted and strong electric fields of more than 107 V/m was obtained by the calculation using the finite element method. The neutron-induced...
We have developed a position-sensitive tubular scintillation neutron detector as an alternative to a 3He gas based detector. The detector comprises a number of individual neutron-sensitive elements, where a pair of wound wavelength-shifting fiber coils is sandwiched with two rolled ZnS/6LiF scintillator screens in each element. Position-dependent neutron sensitivity within the scintillator / wavelength-shifting...
We've developed a novel low-noise frontend LSI architecture with chopper stabilization technique combined with noise shaping ADC at chopping frequency for a capacitive MEMS accelerometer. Key features of the architecture are (1) a doubly modulated differential carrier input to MEMS, (2) a 2nd order sigma-delta ADC having a notch in its noise transfer function (NTF) at chopping frequency, and (3) a...
In this study, we have proposed an ingestible sensor platform utilizing gastric acid battery for daily healthcare. This platform has a fundamental application to precisely measure core body temperature as one of the most useful vital signs for health check. It also has the expandability to add various biosensors such as pH, pressure sensors etc‥ The architecture without a conventional battery is essential...
We have been developing an excavation robot for lunar subsurface investigations. The robot locomotion is based on the peristaltic crawling of an earthworm, which enables stable movement. The robot comprises three units: propulsion, excavation, and discharging units. In our previous research, we demonstrated that the propulsion and excavation units can excavate down to 650 mm without the discharging...
In recent years, powdered materials have been often used in various industries. Among the various uses of powders, we focused on the conveyance of the developer in the printers. Screw conveyors are commonly used in the printer for the conveyance of the developer. However, this presents the problems such as the condensation of the developer by the shearing force and the temperature rise. Thus, low...
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