Trees have been a pillar of our lives not just for human but for all the species living in the earth. Despite of its blessings for our lives, the heaps of problems around forestry have not been solved. One of the major problems in this field is that most of the forest are not been sorted into an organized database. Detailed natural data have never been provided even in famous map applications, Google earth for instance, induced from its difficulty. The forest database has been demanded in many regions as it provides beneficial information for both industrial and environmental aspects. It even helps many divisions such as CG animations to simulate not only a tree itself but also the mountain or the forest as a whole depending on given natural conditions.
The performance of a large-area, monolithic Hamamatsu multi-pixel photon counter (MPPC) was tested consisting of a 2 ×2 array of 3 ×3 mm 2 pixels. MPPC is a novel type of semiconductor photodetector comprising multiple avalanche photodiode (APD) pixels operated in Geiger mode. Despite its great advantage of signal multiplication comparable to that achieved with the photomultiplier tube (PMT), the detection of weak scintillation light signals is quite difficult due to the severe contamination of dark counts, which typically amounts to ≃1 Mcps/3 ×3 mm 2 at room temperature. In this study, a coincidence technique was applied for scintillation detectors to improve the detection efficiency for low energy gamma-rays. The detector consisted of a 10 ×10 ×10 mm 3 crystals of GSO, BGO, and Pr:LuAG optically coupled with the 2 ×2 MPPC-array. With this technique, we demonstrated that the contamination of dark counts was reduced with a rejection efficiency of more than 99.8%. As a result, 22.2 keV gamma-rays were successfully detected with a GSO scintillator as measured at +20 °C.
We are proposing a novel design for a module with depth of interaction (DOI) capability for gamma rays by measuring the pulse-height ratio of double-sided Multi-Pixel Photon Counters (MPPCs) coupled at both ends of a scintillation crystal block. Thanks to newly developed monolithic MPPC arrays consisting of 4 × 4 channels with a three-side buttable package, the module is very thin and compact, thereby enabling less dead space between each module when arranged into a fully designed gantry. To demonstrate our concept of a DOI measuring technique, we first made a 1-D crystal array consisting of five Ce-doped Gd 3 Al 2 Ga 3 O 12 (Ce:GAGG) cubic crystals measuring 3×3×3 mm 3 in size, separated by a layer of air approximately 10 μm-thick. When the light signals output from both ends are read with the 3×3 mm 2 MPPCs, the position of each crystal is clearly distinguished. The same measurements were also made using Ce-doped (Lu,Y) 2 (SiO 4 )O (Ce:LYSO), achieving a similarly good separation. We then fabricated thin Ce:GAGG 2-D crystal arrays consisting of two types: [A] 4 × 4 matrix of 3×3×3 mm 3 pixels, and [B] 10 × 10 matrix of 0.8×0.8×5 mm 3 pixels, with each pixel divided by a BaSO 4 reflector 0.2 mm-thick. Then four arrays are laid on top of each other facing the DOI direction through a layer of air 10 μm-thick. We demonstrated that the 3-D position of each Ce:GAGG pixel is clearly distinguished in both the 2-D and DOI directions for type A and B when illuminated by 662 keV gamma rays. Average energy resolutions of 9.8 ± 0.8% and 11.8 ± 1.3% were obtained for types A and B, respectively. These results suggest that our proposed method is simple and offers promise in achieving both excellent spatial and energy resolutions for future medical imaging, particularly in positron emission tomography (PET).
Change in zeta potential of non‐magnetic colloid particles by imposition of weak AC magnetic field was observed. This effect has frequency dependence that the change appeared remarkably in a specific frequency at several kHz. It is considered to be due to the specific adsorption of ions on the colloids surface by the effect of induction electric field (E = −dB/dt) instead of the magnetic field itself.
Abstract The present study aims to assess the effect of the hip flexion angle on the shear modulus of the adductor longus (AL) muscle associated with passive hip abduction and rotation. Sixteen men participated in the study. For the hip abduction task, the hip flexion angles used were − 20, 0, 20, 40, 60, and 80°, and the hip abduction angles were 0, 10, 20, 30, and 40°. For the hip rotation task, the hip flexion angles used were − 20, 0, 20, 40, 60, and 80°, hip abduction angles were 0 and 40°, and hip rotation angles were 20° internal rotation, 0° rotation, and 20° external rotation. The shear modulus at 20° extension was significantly higher than that at 80° flexion for the 10, 20, 30 and 40° hip abduction (i.e., P < 0.05). The shear modulus at 20° internal rotation and 20° extension was significantly higher than that at 0° rotation and 20° external rotation, regardless of the hip abduction angle (i.e., P < 0.05). The mechanical stress of the AL muscle associated with hip abduction was higher in the extended position. Furthermore, the mechanical stress could increase with internal rotation only at the hip-extended position.
After the Japanese nuclear disaster in 2011, a large amount of radioactive isotopes was released and still remains a serious problem in Japan. To help identify radiation hotspots and ensure effective decontamination operation, we are developing a novel Compton camera weighing only 1.9 kg and measuring just 14×14×15 cm 3 in size. Despite its compactness, the camera realizes a wide 180° field of vision, Δθ ~ 10°(FWHM) angular resolution, and offers excellent sensitivity that can image a hotspot producing a 5 μSv/h dose at a distance of three meters, every 10 sec. Our key technology using 3D position-sensitive scintillators coupled with thin monolithic MPPC arrays has made this innovation possible for the first time. In this paper, we present the detailed optimization and simulation of the Compton camera currently under production with Hamamatsu Photonics.
In this study, riding comfort of an autonomous robotic vehicle is evaluated by KANSEI-words questionnaire. On the autonomous robotic vehicle, where the automatic traveling to the driver-specified destination is available, the cruising characteristics such as speed and turning radius have significant influence on the riding quality. Fundamental strategy for the design and the tuning of the autonomous traveling control system can be provided by clarifying their relationship. The questionnaire survey regarding the riding quality for several automatic test running is conducted based on KASEI words, which are compiled via a preliminary survey, against more than 40 participates. In this paper, the relation among the riding comfort and the cruising characteristics is clarified, and also the strategy of designing the automatics vehicle control is discussed.
