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81.
Field emission properties from diamond particles (DPs) are studied. The DPs with thin chemically vapor deposited (CVD) diamond overcoat, dispersed onto metal substrate, essentially exhibit negative electron affinity (NEA). Field emission, approximately 1mA/cm(2) under a macroscopic electric field of 3.5kV/mm are observed. Microscopic electrical properties were studied by scanning tunneling microscopy/spectroscopy. Most parts of the DP surface exhibit narrow gap and p-type characteristics. The localized regions, which have wide gap like bulk diamond properties, are randomly distributed near the top of DP. The field emission current distribution depicted by scanning field emission microscopy (SFEM) show that the electron emission is originating from a localized region on the selected DPs. We found, through SFEM measurement, some favorable field emission spots ("hot spots") where measured emission current is several orders higher than that of the other DPs ("normal spots"). Field emission spectroscopy (FES) results suggest that a poorly conducting layer is present along the electron path from the metal electrode to vacuum.We propose two models for field emission from "hot spots", which involve two main mechanisms. One is electron injection from the metal substrate to the DP, which is attributed to the electric field enhancement at intrinsic non-doped diamond (i-diamond) layer sandwiched between the metal substrate and the surface conductive layer (p-diamond) of the CVD diamond overcoat on the DP. The other is electron emission at the top site of NEA DP through the local i-diamond region or the depletion region of the p-diamond, which is caused by the applied electric field. 相似文献
82.
ABSTRACT Using several line powders (particle size 15-65 μ m). the rheological parameters of tensile strength ( σf,mb) and plastic deformation coefficient (Y) were experimentally measured at ambient and elevated temperatures. In order to be aeratable. the rheological parameters of a specific powder should satisfy the equation of σf,mb = 0.11Y0 89.The formation of agglomerates or dead zones can be predicted. By introducing the “Quasi porous solid body model,” the theoretical derivation of the criterion characteristic curve was accomplished using solid fracture theory. 相似文献
83.
84.
Hiroyuki Kono Tomohito Ichiki Hideharu Mori Hisayuki Nakatani Minoru Terano 《Polymer International》2001,50(5):568-571
Block copolymerization of propene and 1,5‐hexadiene was carried out by a modified stopped‐flow polymerization method with an MgCl2‐supported Ziegler catalyst. The resulting polymer, polypropene‐block‐poly(methylene‐1,3‐cyclopentane‐co‐propene) (PP‐b‐(PMCP‐co‐PP)), in which the crystallizable PP part was linked with the non‐crystallizable PMCP‐co‐PP part, was characterized by optical microscopy, differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and tensile testing. The block copolymer having a chemical linkage between PP and PMCP‐co‐PP showed properties different from those of homopolymer, random copolymer and blend polymer. © 2001 Society of Chemical Industry 相似文献
85.
In this article, equations of motion of a closed-type manipulator, whose mechanism can easily be made lighter, are derived
in consideration of the characteristics of the driving source. Considering the final condition of angular displacement and
angular velocity in throwing motion, trajectories of velocity for saving energy are calculated by iterative dynamic programming,
and the dynamic characteristics of manipulator control based on the trajectory for saving energy are analyzed theoretically
and investigated experimentally.
This work was presented in part at the 11th International Symposium on Artificial Life and Robotics, Oita, Japan, January
23–25, 2006 相似文献
86.
Kimitoshi Sato Ji-Guang Li Hidehiro Kamiya Takamasa Ishigaki 《Journal of the American Ceramic Society》2008,91(8):2481-2487
Aggregation and dispersion behavior of nanometer and submicrometer scale TiO2 particles in aqueous suspension were investigated using three kinds of mechanical dispersion methods: ultrasonic irradiation, milling with 5-mm-diameter balls, and milling with 50 μm beads. Polyacrylic acids with molecular weights ranging from 1200 to 30 000 g/mol were used as a dispersant, and the molecular weight for each dispersion condition was optimized. Viscosities and aggregate sizes of the submicrometer powder suspensions were not appreciably changed in the ultrasonic irradiation and 5-mm-ball milling trials. In contrast, in the trials in which nanoparticle suspension was used, ultrasonic irradiation produced better results than 5-mm-ball milling. Use of ultrasonication enabled dispersion of aggregates to primary particle sizes, which was determined based on the specific surface area of the starting TiO2 powders, even for relatively high solid content suspensions of up to 15 vol%. Fifty-micrometer-bead milling was also able to disperse aggregates to the same sizes as the ultrasonic irradiation method, but 50-μm-bead milling can be used only in relatively low solid content suspensions. It was concluded that the ultrasonic dispersion method was a useful way to prepare concentrated and highly dispersed nanoparticle suspensions. 相似文献
87.
Nico A. Gaida Steeve Gréaux Yoshio Kono Hiroaki Ohfuji Hideharu Kuwahara Norimasa Nishiyama Oliver Beermann Takuya Sasaki Ken Niwa Masashi Hasegawa 《Journal of the American Ceramic Society》2021,104(1):635-644
Material properties, such as elasticity data at wide-ranging conditions of pressure and temperature, attract increasing attention for material and earth sciences. In particular, polycrystalline ceramics for next-generation photonic applications are nowadays fabricated by advanced syntheses techniques operating under elevated pressures and temperatures. Herein, the elastic properties of a synthetic transparent and reinforced aluminosilicate nanoceramic composed of triclinic kyanite with minor amounts of trigonal α-alumina crystals are investigated using in situ synchrotron X-ray diffraction and ultrasonic techniques at high-pressure (up to 11 GPa) and high-temperature (300-1500 K) conditions. This not only enables the determination of the equation of state (EoS) parameters by applying the pressure-volume-temperature (P-V-T) data to the high-temperature Birch-Murnaghan EoS but also yields the elastic moduli together with their P and T derivatives from the fit of the compressional and shear wave velocities to a finite strain EoS: KS0,300 = 186(2) GPa, K′S0,300 = 7.2(6), (∂KS0,300/∂T)P = −0.023(2) GPa K−1, G0,300 = 125(1) GPa G′0,300 = 2.3(2), (∂G0,300/∂T)P = −0.017(1) GPa K−1. On the basis of our acquired results, we propose to predict the elastic moduli of aluminosilicate ceramics by a linear function of the ratio of AlO6 octahedra and SiO4 tetrahedra within the constituting phases. 相似文献
88.
D. G. Rees I. Kuroda C. A. Marrache-Kikuchi M. H?fer P. Leiderer K. Kono 《Journal of Low Temperature Physics》2012,166(3-4):107-124
We present transport measurements of electrons on the surface of liquid helium in a microchannel device in which a constriction may be formed by a split-gate electrode. The surface electron current passing through the microchannel first decreases and is then completely suppressed as the split-gate voltage is swept negative. The current decreases in a steplike manner, due to changes in the number of electrons able to pass simultaneously through the constriction. We investigate the dependence of the electron transport on the AC driving voltage and the DC potentials applied to the sample electrodes, in order to understand the electrostatic potential profile of the constriction region. Our results are in good agreement with a finite element modeling analysis of the device. We demonstrate that the threshold of current flow depends not only on the applied potentials but also on the surface electron density. The detailed understanding of the characteristics of such a device is an important step in the development of mesoscopic experiments with surface electrons on liquid helium. 相似文献
89.
Phan Huy Dong Kimitoshi Hayano Yoshiaki Kikuchi Hidenori Takahashi Yoshiyuki Morikawa 《Soils and Foundations》2011,51(4):611-624
Cement Treat Granulate Soil (CTGS), a new artificial granular material, has been developed recently by mixing the dredged marine clay with appropriate amounts of cement and polymer. The CTGS particles are crushable and deformable, thus forming a compressible material. Besides being a lightweight material, CTGS is a granular material, and is therefore expected to be applied in reclamations or as a back fill or subsoil materials. This study investigates the deformation and crushing of the CTGS particles and their effects on the stress-strain behaviors. The comprehensive investigation of the principle of treatment, the micro-structure of particles, triaxial stress-strain behaviors, induced particle crushing and particle deformation are first presented via the experimental work done on two types CTGS produced from a lean-mixture design of cement and polymer. Subsequently, the results of X-ray Computer Topography (CT) scanners along with triaxial CD tests on CTGS and conventional gravel having rigid particles are presented. The test results reveal local failure mechanisms between the individual particles of the CTGS and gravel, from which the failure models of the granular materials formed by deformable and crushable grains and non-crushable grains are interpreted. 相似文献
90.
Kimitoshi Kono 《Journal of Low Temperature Physics》2010,158(1-2):288-300
A review of recent investigations of transport properties of surface state electrons on superfluid 3He is given. The surface state electrons in this temperature region form the Wigner solid (WS), a triangular lattice of electrons with a typical lattice constant of 1 μm. The WS is accompanied with a shallow corrugation of He surface commensurate with the WS. A model is introduced to interpret the observed WS resistivity. The model takes into account specular quasiparticle (QP) reflection from the moderately corrugated free surface, and treats the QP as if it is a quasiclassical particle. After adopting anisotropic properties of superfluid 3He order parameter and QP energy, the model provides satisfactory account of the observed properties. Preliminary results of mobility measurements of ions trapped below superfluid 3He-B are also given. 相似文献