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131.
The two conventional methods currently employed for the evaluation of image resolution in scanning electron microscopy are the gap method and a fast Fourier transform (FFT) method. These can be highly dependent on personal expertise on the distinction between signal information and noise contained in a micrograph. Hence, the present paper proposes an alternative method (referred to as a contrast-to-gradient (CG) method) that can determine the image resolution of a micrograph without requiring personal expertise on the judgment of noise. The image resolution in the CG method is defined as a weighted harmonic mean of the local resolution, which is proportional to the quotient of the threshold contrast divided by the local gradient. The local gradient is calculated from the quadratic function that best fits the local pixel intensities over 5 x 5 pixels. It has been shown that the CG method, compared with the FFT method, has a broader range of applications for various types of images, such as low-contrast, noise-containing, filter-processed, highly directional, and quasi-periodic feature images. 相似文献
132.
This paper deals with the examination of specifications to improve the performance of a pivot bearing with two degrees of freedom by finite element method (FEM). As the target of estimation for performance of the bearing, we evaluated the contact pressure and the stiffness. As the results of FEM considering the number of grooves and the contact angle of the planetary ball, a large effect was obtained in the case that the number of rows of planetary balls was 2. The effect was confirmed by measuring axial displacement. 相似文献
133.
Hiroyuki Nabae Morizo Hemmi Yoshiharu Hirota Tohru Ide Koichi Suzumori Gen Endo 《Advanced Robotics》2018,32(9):524-534
AbstractOne of the most important missions for robots is to operate in severe environments, and these situations require robots to have ‘toughness’ which can overcome large shocks, degraded communication quality, unexpected condition, and other critical accidents. Although there are many kinds of approaches to realize tough robotic systems, developing a tough actuators is one of the key technologies for them. We focus on hydraulic actuators and attempt to develop a tough robotic actuator with greater toughness than the electromagnetic actuators used in conventional robotic systems. In general, hydraulic actuators have enough toughness for severe environments, but their controllability and lightness are insufficient for robot systems. Herein, we propose novel hydraulic actuators that realizes lightweight with a multidirectional-forging magnesium alloy and have high controllability by low friction pistons. Prototypes were developed to examine the fundamental characteristics of the actuators and compare the two approaches for the low-friction pistons: one is based on a packing mechanism using an elastic restoring pressure, and the other utilizes a fluid-bearing technology. After basic experiments, the prototype was applied to a robotic leg to verify their potential in actual robotic systems. The robotic leg successfully jumped 260 mm in height with 21 MPa. 相似文献
134.
A novel low‐power gate driver architecture for large 8 K 120 Hz liquid crystal display employing IGZO technology
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Yasuaki Iwase Akira Tagawa Yohei Takeuchi Takuya Watanabe Satoshi Horiuchi Yoshihiro Asai Kaoru Yamamoto Tohru Daitoh Takuya Matsuo 《Journal of the Society for Information Display》2018,26(5):304-313
A novel low‐power gate driver architecture was developed for large 8 K 120 Hz liquid crystal display panel. For this application, not only high‐speed driving but also low power consumption is required. We employed a high mobility In‐Ga‐Zn‐O, dual VGL level driving method, and gate driver circuit driven by DC supply. The simulation results show that our proposals meet 8 K 120 Hz driving requirements. Also, we have fabricated a prototype panel and confirmed both high‐speed driving and low power consumption. 相似文献
135.
Guoqing Wang Yoshitsugu Akiyama Naoki Kanayama Tohru Takarada Mizuo Maeda 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(44)
Directed assemblies of anisotropic metal nanoparticles exhibit attractive physical and chemical properties. However, an effective methodology to prepare differently directed assemblies from the same anisotropic nanoparticles is not yet available. Gold nanorods (AuNRs) region‐selectively modified with different DNA strands can form side‐by‐side (SBS) and end‐to‐end (ETE) assemblies in a non‐crosslinking manner. When the complementary DNA is hybridized to the surface‐bound DNA, stacking interaction between the blunt ends takes place in the designated regions. Such AuNRs assemble into highly ordered structures, assisted by capillary forces emerging on the substrate surface. Moreover, insertion of a mercury(II)‐mediated thymine–thymine base pair into the periphery of the DNA layer allows selective formation of the SBS or ETE assemblies from the strictly identical AuNRs with or without mercury(II). 相似文献
136.
Masanobu Kamitakahara Eri Tatsukawa Yasuaki Shibata Shota Umemoto Taishi Yokoi Koji Ioku Tohru Ikeda 《Journal of materials science. Materials in medicine》2016,27(5):97
In addition to calcium phosphate-based ceramics, glass-based materials have been utilized as bone substitutes, and silicate in these materials has been suggested to contribute to their ability to stimulate bone repair. In this study, a silicate-containing α-tricalcium phosphate (α-TCP) ceramic was prepared using a wet chemical process. Porous granules composed of silicate-containing α-TCP, for which the starting composition had a molar ratio of 0.05 for Si/(P + Si), and silicate-free α-TCP were prepared and evaluated in vivo. When implanted into bone defects that were created in rat femurs, α-TCP ceramics either with or without silicate were biodegraded, generating a hybrid tissue composed of residual ceramic granules and newly formed bone, which had a tissue architecture similar to physiological trabecular structures, and aided regeneration of the bone defects. Supplementation with silicate significantly promoted osteogenesis and delayed biodegradation of α-TCP. These results suggest that silicate-containing α-TCP is advantageous for initial skeletal fixation and wound regeneration in bone repair. 相似文献
137.
Xinwen Zhu Fengqiu Tang Tohru S. Suzuki Yoshio Sakka 《Journal of the American Ceramic Society》2003,86(1):189-191
The role of the initial degree of ionization (αi ) of polyethylenimine (PEI) in the dispersion of SiC nanopartilces in water was investigated by sedimentation and rheological measurements. The ionization of PEI was characterized by potentiometric titration, which indicated a pH-dependent conformational transition. The dispersion of SiC particles in the presence of PEI was found to strongly depend on the αi . In the presence of 0.4% by weight PEI, the 23.8% SiC by volume (ΦSiC = 23.8) slurries showed a Newtonian behavior for αi = 0.12–0.4 values, whereas a shear-thinning behavior was observed for αi > 0.4 in the optimal pH range of around pH 4. The rheological behavior of the slurries exhibited a strong dependence on the concentration of PEI of αi = 0.12–0.4 and the slurry showed a Newtonian behavior at an optimal concentration of 0.4% by weight. The stabilization may be dominated by an electrosteric effect arising from the adsorbed PEI of αi = 0.12–0.4. The flocculation mechanism of the slurries with PEI of αi > 0.4 is also discussed. 相似文献
138.
En-Hai Sun Takafumi Kusunose Tohru Sekino Koichi Niihara 《Journal of the American Ceramic Society》2002,85(6):1430-1434
The formation mechanism of ZrSiO4 in the cordierite-ZrO2 system was studied in the temperature range of 1250° to 1400°C by X-ray diffraction analysis and discussed by analyzing experimental data using some reported reaction models. Nuclei growth models were found to describe the reaction well, and a satisfactory fit was obtained by applying the Avrami equation to estimate the reaction rate constant κ. Different values of the time exponent m were obtained at different temperatures: 0.32 at 1250°C, 0.34 at 1300°C, 0.39 at 1350°C, and 0.49 at 1400°C. The results indicate that there is a progressive change in reaction mechanism. 相似文献
139.
Machinability of Silicon Nitride/Boron Nitride Nanocomposites 总被引:4,自引:0,他引:4
Takafumi Kusunose Tohru Sekino Yong-Ho Choa Koichi Niihara 《Journal of the American Ceramic Society》2002,85(11):2689-2695
The machinability and deformation mechanism of Si3 N4 /BN nanocomposites were investigated in the present work. The fracture strength of Si3 N4 /BN microcomposites remarkably decreased with increased hexagonal graphitic boron nitride ( h -BN) content, although machinability was somewhat improved. However, the nanocomposites fabricated using the chemical method simultaneously had high fracture strength and good machinability. Hertzian contact tests were performed to clarify the deformation behavior by mechanical shock. As a result of this test, the damage of the monolithic Si3 N4 and Si3 N4 /BN microcomposites indicated a classical Hertzian cone fracture and many large cracks, whereas the damage observed in the nanocomposites appeared to be quasi-plastic deformation. 相似文献
140.
Chang Yeoul Kim Tohru Sekino Koichi Niihara 《Journal of the American Ceramic Society》2003,86(9):1464-1467
(Bi1/2 Na1/2 )TiO3 (BNT) is a prominent candidate for a lead-free piezoelectric material. In this study, BNT was synthesized using the solution/sol–gel method, in which a solution of Bi2 O3 and Na2 CO3 was dissolved in HNO3 as starting materials. The solution then was mixed with ethylene glycol and titanium tetraisopropoxide. The obtained BNT powder was analyzed using FT-IR, DTA-TG, Raman spectroscopy, and high-temperature XRD. Results showed that BNT crystallization occurred above 600°C. TEM investigation showed that 100–200 nm BNT particles were formed by heat-treating the sol–gel-derived BNT sol at 700°C for 6 h. 相似文献