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The shear wave velocity in surficial marine sediment is important evaluating the physical properties of such sediment. In this study, the dispersion of the shear wave velocity is investigated using the Biot–Stoll model. Next, the shear wave velocities of air- and water-saturated beach sands are measured at a low overburden stress, and the shear moduli of these sands are derived. The relationships of the shear wave velocity or shear modulus with the porosity are investigated. Also, the relationship between the shear wave velocities in the air- and water-saturated sands are obtained and investigated. The same investigation is performed for these shear moduli. Finally, the shear wave velocity of water-saturated clay is measured, and an empirical equation for the relationship between the shear wave velocity and the porosity is obtained.

In this study, the acoustic wave reflection characteristics from the surface of water-saturated and air-saturated sediments are calculated using the Biot-Stoll model. These sediments are silt and medium sand. The calculated results for the water-saturated and the air-saturated silt and medium sand are compared. Additionally the reflection characteristics from the surface of sediments with the top transition layer are obtained using OASES (Biot-Stoll model). The effects of the transition layer depending on the frequency are investigated. Moreover, the effects of the slow wave in the air-saturated sediment on the reflection characteristics are considerd.

Iron ore sinter constitutes the major component of the iron-bearing burden in blast furnaces, and its reduction mechanism is one of the keys to improving the productivity of ironmaking. Iron ore sinter is composed of multiple iron oxide phases and calcium ferrites (CFs), and their heterogeneous reduction was investigated in terms of changes in iron chemical state: FeIII, FeII, and Fe0 were examined macroscopically by 2D X-ray absorption and microscopically by 3D transmission X-ray microscopy (TXM). It was shown that the reduction starts at iron oxide grains rather than at calcium ferrite (CF) grains, especially those located near micropores. The heterogeneous reduction causes crack formation and deteriorates the mechanical strength of the sinter. These results help us to understand the fundamental aspects of heterogeneous reduction schemes in iron ore sinter.

The three partial structural functions of molten copper halides CuX (X = Br, I) have been estimated from anomalous x-ray scattering (AXS) measurements coupled with the reverse Monte Carlo (RMC) simulation technique. For both cases of molten CuBr and CuI, the Cu-Cu partial structure factor of a CuCu (Q ) was found to be rather structureless and the closest Cu-Cu distance was significantly smaller than that for X-X, indicating like-ion penetration into the first unlike-ion coordination shell, similar to the molten CuCl case. We then suggest a disordered close packing of anions where Cu ions meander so as to take a strongly disordered distribution by penetrating through the tetrahedral holes.

Iron-ore sinters constitute the major component of the iron-bearing burden in blast furnaces, and the mechanism of their reduction is one of the key processes in iron making. The heterogeneous reduction of sintered oxides was investigated by the combination of X-ray fluorescence and absorption fine structure, X-ray diffraction, and computed tomography. Two - dimensional mapping of the chemical states (CSs) was performed. The iron CSs FeIII, FeII, and Fe0 exhibited a heterogeneous distribution in a reduced sinter. The reduction started near micro pores, at iron-oxide grains rather than calcium-ferrite ones. The heterogeneous reduction among grains in a sinter may cause the formation of micro cracks. These results provide fundamental insights into heterogeneous reduction schemes for iron-ore sinters.

A rapid decrease in Jc with elevating temperature was recently observed in melt-processed Y-Ba-Cu-O at low temperatures. This suggests an existence of weak links in this material. In order to investigate weak link property in this material, the history effect of Jc and Jc in the longitudinal field geometry were measured. These measurements suggest that weak link property in this material is quite different from those at grain boundaries in polycrystalline materials.

In situ QXAFS studies of the reduction of α-Fe2O3 and CaFe2O4 were conducted to determine their reduction kinetics and mechanisms. The reduction of α-Fe2O3 involved two steps, the first being a very fast process in which Fe3+ was reduced to Fe2+ and the second being the reduction of Fe2+ to Fe metal over a longer period. In contrast, the reduction of Fe in CaFe2O4 was a single first-order reaction, although an induction period was clearly observed at the beginning of the reduction process. The reduction processes were successfully studied using a combination of in situ QXAFS spectra at the Ca and Fe K-edges.

We investigated the change in structures during reduction and oxidation of a new type of Pd on Sr-Fe-O catalyst for exhaust emission. In situ DXAFS techniques have shown changes in palladium states and oxygen concentration simultaneously during reduction and oxidation reactions. Quantitative analysis has shown that palladium atoms change their states between Pd(II*) and Pd(0) reversibly according to the gas atmosphere accompanying changes in the oxygen concentration. This reaction explains the high performance of the catalyst.

In this study, the value of the grain bulk modulus of marine sediment has been investigated. Glass beads are used for the sand model. The value of the grain bulk modulus for glass beads is obtained from the measured values of longitudinal and shear wave velocities in glass beads. The value of the grain bulk modulus is also estimated from the measured values of the longitudinal wave velocity in a heavy liquid suspension of glass beads. From the above results, it is seen that the measured values of the grain bulk modulus are nearly the same as Stoll's value of the grain modulus. Moreover, it is suggested that the unjacketed bulk modulus may not be the same as the grain bulk modulus.

In this study, the acoustic wave velocities of gel-clay mixtures and gel-saturated porous media are studied. First the longitudinal and shear wave velocities of these media are measured. In the case of gel-diatomite mixture, the longitudinal wave velocity rapidly decreases, as the diatomite weight percent increases over 10%. Finally it is found that the gel-diatomite mixture with the longitudinal wave velocity of about 250 m/s and the shear wave velocity of about 8 m/s, can be obtained.

Scholte waves propagating between seawater and marine sediment exhibit velocity dispersion if the shear wave velocity of the sediment under the seabed surface depends on the depth. Therefore, the velocity dispersion of Scholte waves can be used to determine the shear wave velocity profile of marine sediment. In this study, group velocity dispersion characteristics are derived from data from Scholte waves obtained in Jervis Bay and Hunters Bay, Australia, using a multiple filter method. Shear wave velocity profiles are then obtained from the group velocity dispersion characteristics of Scholte waves using an inversion method.

In this study, the coupling characteristics between a geophone and three kinds of ground models are measured, and the results of resonant frequency and damping factor measurements are investigated. In particular, the shear wave velocities calculated from the equation, which relates the resonant frequency of the coupling to the shear wave velcoity in ground models, is compared with the measured shear wave velocities.

In this study, the depth dependence of shear wave velocity in dry glass beads and sands is measured, and the empirical equations for shear wave velocity as a function of depth are obtained.

In this study,in situexperiments of Scholte waves between seawater and marine sediment are conducted in Jervis Bay and Hunters Bay, Australia, and velocity dispersion characteristics are obtained using the multiple filter method.

Si-based coatings were formed on iron surfaces by low pressure chemical vapor deposition of pure SiH4 and He-diluted SiH4 under the following conditions: temperature of 350 to 850°C, gas flow rate of 0.1 to 100 sccm, gas composition of pure or He-diluted SiH4, pressure of 0.01 to 600 Torr and deposition time of 2 to 20 min. Coatings are essentially overlay type, with more than 30 at.% Si, for temperatures between 350 to 650°C regardless of other conditions. When the temperature exceeds 650°C, low gas flow rates (

In this study, the sound velocity and the attenuation constant of marine sediments with partial gas saturation are obtained using white's model, and the effect of gas on those characteristics are investigated. Next, the sound velocities of sediment model are measured. And those experimental values are compared with the calculated values.

Trapped magnetic flux density of melt-grown YBaCuO bulk superconductors was evaluated. A single-grained disc-shaped bulk sample with a size of 45 mmφ×15 mm trapped very high magnetic flux density after field cooling. One disc trapped a maximum surface flux density of 0.72 T, while the maximum of double-piled discs was 1.35 T after 100 seconds. A polygrained sample showed a much lower maximum. The pinning potential of this single-grained disc was 0.17 eV, and the overall critical current density estimated from the trapped flux density was about 7×103 A/cm2. Since these values are lower than those of a small-sized sample, weak links are still expected to exist even in the single-grained sample. Domain structure within a grain is a strong candidate for this weak link.

Critical current densities in superconducting Y-Ba-Cu-O specimens with different sizes of 211 particles prepared by the melt process were measured under various magnetic fields and temperatures. Discussion is given on the flux pinning properties by 211 particles and background pinning centers. At temperatures above 60 K, 211 particles are expected to be dominant pinning centers. A rapid degradation of the critical current density with elevating temperature at low temperatures below 25 K seems to be attributed to weak links in specimens.

In this study, we obtain the sound velocity and the attenuation constant of high porosity marine sediments using Biot's theory and Yamamoto's modified equations, and investigate the effect of the grain size and grain size distribution on the frequency characteristics. Next, we show that the experimental values of the attenuation constant of Black sediment measured by Hampton nearly agree with the calculated values.

An apparatus for the precise measurement of electron intensity diffracted from gas molecules has been constructed. Care has been taken to define camera distances precisely by installing a table, to which the nozzle and the photographic plate can be fixed firmly, and to eliminate extraneous scattering by designing a suitable electron-optical system and by inserting a brass ring with a folded wall covered with soot into the sector race. A critical examination by the use of carbon dioxide has shown that the structure can be determined with the accuracy of one thousandth of an angstrom with the present apparatus.