Masahiro Fujita

Batch fabrication of intravascular forward-looking ultrasonic probe

Abstract An intravascular forward-looking ultrasonic probe has been fabricated using batch fabrication. This probe consists of eight separated elements ring array 1–3 composite transducer and a backing made from conductive epoxy. The conductive epoxy backing works not only acoustic dumping material but also electrical interconnection. Almost same impedance properties and pulse-echo waveform from each of the eight elements have been measured. Reflected pulse-echo by an acrylic plate placed at appropriately 4.5xa0mm front of the probe has been detected from each of the eight transducer elements in water.

Transport efficiency of fission products in IGISOL

Abstract Two types of double-room target chambers were constructed for effective stopping of fission fragments in ion-guide isotope separator on-line (IGISOL). It was found that the efficiencies for the double-room chambers are about three and four times larger than that for the standard one. The yield/μC decreases with an increase of the beam intensity. The decreasing trends for both chambers quite resemble each other. This fact suggests that the plasma effect remains even in the double-room chambers. Using the charge distribution of fission products obtained by IGISOL, the yield of RI beam was estimated for the proton-induced fission of 238U.

Isomeric yield ratios of fission products in proton-induced fission of232Th

Isomeric yield ratios of 11 fission products were measured in the system of 13 MeV proton-induced fission of232Th by an on-line ion-guide isotope separator. It was found that the closed shell structures of primary fragments and their complementary fragments affect the isomeric yield ratios. Isomeric yield ratios of121Cd (11/2−, 3/2+) and135Xe (11/2−, 3/2+) were measured precisely in the proton energy range of 13 to 26 MeV to investigate their energy dependence. It was found that the isomeric yield ratios increased slightly with proton energy. The results were discussed in connection with the deformation of fission fragments and fission modes.

Space charge effects in a thin rectangular proportional counter

Abstract We recently reported on a “twin-peaks effect” found for a thin rectangular proportional counter. In this work we develop a simple model for the space-charge effect during the drift process of primary electrons and simulate the twin-peaks effect for incident α -rays. The “first peak” is thus explained by a time distribution of arrival of the primary electrons at the multiplication region, while the ‘second peak” can be qualitatively explained as a result of competition between diffusion and recombination.

Two axes orthogonal drive transmission for omnidirectional crawler with surface contact

In this paper, we propose an omnidirectional mobile mechanism with surface contact. This mechanism is expected to perform on rough terrain and weak ground at disaster sites. In the discussion on the drive mechanism, we explain how a two axes orthogonal drive transmission system is important and we propose a principle drive mechanism for omnidirectional motion. In addition, we demonstrated that the proposed drive mechanism has potential for omnidirectional movement on rough ground by conducting experiments with prototypes.

High-Spin States in 93Nb

The high-spin states of 93 Nb are studied by the 82 Se( 16 O, p4n) 93 Nb reaction at a beam energy of 100 MeV. The in-beam γ-ray spectroscopic techniques are used. The γt-, γγt-coincidence, γ-ray a...

Planar Omnidirectional Crawler Mobile Mechanism—Development of Actual Mechanical Prototype and Basic Experiments

This letter proposes a planar omnidirectional crawler mobile mechanism. This mechanism is the basis for the mobility of search and rescue robots. A planar omnidirectional crawler aims to facilitate penetration into a narrow path and soft or fragile ground. In this letter, the effectiveness of the proposed transmission mechanism is experimentally determined. In addition, a planar omnidirectional crawler equipped with a transmission mechanism was developed, and its characteristics were investigated through experiments for the pressure applied to the ground.

Concyclic CH-π arrays for single-axis rotations of a bowl in a tube

The hydrogen bond is undoubtedly one of the most important non-covalent interactions. Among the several types of the hydrogen bonds, the CH–π interaction is a relatively new notion that is being recognised in chemistry and biology. Although the CH–π hydrogen bond and conventional hydrogen bonds share common features such as directionality, this weak interaction has played a secondary role in molecular recognition. In this study, we have devised a host–guest complex that is assembled solely by the CH–π hydrogen bonds. Multivalent interactions of a bowl-shaped hydrocarbon with its peripheral hydrogen atoms are made possible via CH–π hydrogen bonds by adopting a tubular hydrocarbon as a host for their enthalpy-driven complexation. Concyclic arrays of weak hydrogen bonds further allow dynamic rotational motions of the guest in the host. Solid-state analysis with crystallographic and spectroscopic methods reveal a single-axis rotation of the bowl in the tube.The weak and directional CH-π hydrogen bond has rarely been exploited in the design of supramolecular complexes and molecular machinery. Here, the authors construct a bowl-in-tube complex stabilized solely by concyclic CH-π hydrogen bonds, and show that the guest exhibits single-axis rotational motion despite tight association with the host.

Development of universal vacuum gripper for wall-climbing robot

Abstract Task performed at a height, such as wall inspections are one of the dangerous tasks for humans. Thus, robotic technology for safety inspection is required. This research focuses on developing robots to climb vertical walls with flat and uneven surfaces, e.g. concrete, tile and riveted structure. To have wall-climbing capability, climbing robots use vacuum pads, claws, magnets, intermolecular force, and adhesive. However, each of these approaches has disadvantages. To achieve wall climbing on an uneven surface without scratching and staining, we have developed a novel vacuum pad named the Universal Vacuum Gripper (UVG), which is based on the Universal Gripper (UG). The UG is a robot hand using jamming transition of coffee powder inside a balloon to grip uneven material. The UVG is a vacuum pad with a deformable skirt based on the UG. If the skirt shape is deformed in accordance with the contact surface, air leaks can be avoided. Moreover, the deformed skirt can be stiffened, thereby working as a gripper. Here, we evaluate the proposed gripper, having both grasping and adhesion force. We also develop a wall-climbing robot with UVGs, and evaluate its performance on uneven surfaces under real-world conditions.

Jamming layered membrane gripper mechanism for grasping differently shaped-objects without excessive pushing force for search and rescue missions

ABSTRACT A gripper comprising a jamming membrane was developed with the capability of grasping collapsible, soft, and fragile objects without applying heavy pressure. In disaster sites, it is necessary for robots to grab various types of objects, such as fragile objects. Deformable grippers that contain bags filled with powder cannot handle collapsible or soft objects without excessive pressure. Changing powder density relatively by changing inner volume is one approach to overcome this problem. By expanding the concept and simplifying the variable inner volume of the gripping mechanism, we developed a jamming membrane comprising the following three layers: outer layer and inner layer made of rubber and a powder layer in between the outer and inner rubber layer. This jamming membrane allows collapsible, soft, or fragile objects to be held securely without applying too much pressure. We designed and developed a prototype of the jamming membrane gripper. Our experiments confirmed the validity of the proposed jamming membrane mechanism. GRAPHICAL ABSTRACT