Hydration and phase relations of grossular-spessartine garnets at P H 2O=2 Kb

The phase relations in the system grossular-spessartine-H₂O were investigated at 2.0 Kb aqueous fluid pressure and at subsolidus temperatures down to 420 ° C. Despite metastable persistence of a compositional gap found in some intermediate members, a complete solid solution between grossular and spessartine exists.Linear relations between the unit cell edge, a ₀, and composition were readily observed down to 620 ° C with a ₀=11.849(2) Å and 11.613(2) Å for grossular and spessartine, respectively. Hydrated garnets began to appear at higher temperature for the Ca-rich members. Grossular and spessartine formed at 420 ° C have a ₀=11.901(2) Å and 11.632(2) Å, indicating the presence of 0.6 and 0.2 mol H₂O, respectively. Intermediate members show varying degrees of hydration. Infrared spectra of the more hydrated members show a major and minor absorption bands at 3,620 cm^–1 and 3,660 cm^–1, respectively, in addition to a broad band around 3,430 cm^–1. All the hydrogarnets formed at 420 ° C were proven to be metastable.The rare occurrence of the intermediate grossular-spessartine garnets may be attributed to the lack of appropriate bulk chemistry of the rock rather than to the P-T conditions to which the rock is subjected. There may be a stability field for hydrogrossular below 420 ° C at 2 Kb, but not for hydrospessartine. Any occurrence of hydrogarnet may be used as a temperature indicator setting the maximum of formation for the hydrogarnet-bearing assemblage below 420 ° C at 2 Kb.     

Precise tidal gravity recorded with superconducting gravimeters at stations Wuhan (China) and Kyoto (Japan)

 Three long series of tidal gravity observations, totalizing approximately 24 years and recorded with three superconducting gravimeters, T004, T008, and T009, at stations Wuhan (China) and Kyoto (Japan), are studied. The tidal amplitude factors and phase differences are determined precisely using Eterna and Nsv techniques. The precision of the main tidal amplitudes is at the same level of 0.01 μGal. The atmospheric gravity signals are corrected using the coefficients determined with a regression method between tidal gravity residual and station air pressure. The oceanic gravity signals are modeled based on five global oceanic models. It is found that the oceanic models developed by the analysis of measurements from Topex/Poseidon altimeters have the best fit to the superconducting gravimeter measurements, since the observed residuals and the discrepancies between the amplitude factors and the theoretical tidal models are reduced more significantly. The long-period gravity variations are dominated by the non-linear drift phenomena of the instruments, and the short-term variations in gravity are due to the background noise at the stations. Received: 20 January 2000 / Accepted: 15 September 2000     

The influence of upstream slope on the local scour at drop structure

The drop structure will fail as a result of local scoring downstream. This paper discusses the influence of a drop structures’ upstream slope to local scour. Empirical equations of the scour hole were developed by laboratory experiment, theoretical assumptions, and regression analysis. These equations include the maximum scour depth and length during the scouring period, the maximum equilibrium scour depth and length, and the unit width scour rate. The four channel slopes (0%, 2%, 4%, and 6%) before the drop structure has been included in the analysis. A series of laboratory experiments were conducted to obtain 48 groups of experiments and 419 scour hole profiles during the scouring period. The material used in the scour section is uniform non-cohesive and with a median diameter of d ₅₀ = 0.5 mm. The results have been used to develop empirical equations via regression analysis to determine the coefficients of theoretical equations. The high correlation coefficient indicates that the equations developed in this study are suitable for verifying the characteristics of a scour hole at drop structure in the sloped channel. The semi-empirical equation is more accurate than the empirical equation. Compared to a horizontal channel, a sloped channel tends to cause a greater equilibrium maximum scour length, shorter equilibrium maximum scour depth, and faster unit-wide scour rate.     

3D building model-based pedestrian positioning method using GPS/GLONASS/QZSS and its reliability calculation

The current low-cost global navigation satellite systems (GNSS) receiver cannot calculate satisfactory positioning results for pedestrian applications in urban areas with dense buildings due to multipath and non-line-of-sight effects. We develop a rectified positioning method using a basic three-dimensional city building model and ray-tracing simulation to mitigate the signal reflection effects. This proposed method is achieved by implementing a particle filter to distribute possible position candidates. The likelihood of each candidate is evaluated based on the similarity between the pseudorange measurement and simulated pseudorange of the candidate. Finally, the expectation of all the candidates is the rectified positioning of the proposed map method. The proposed method will serve as one sensor of an integrated system in the future. For this purpose, we successfully define a positioning accuracy based on the distribution of the candidates and their pseudorange similarity. The real data are recorded at an urban canyon environment in the Chiyoda district of Tokyo using a commercial grade u-blox GNSS receiver. Both static and dynamic tests were performed. With the aid of GLONASS and QZSS, it is shown that the proposed method can achieve a 4.4-m 1σ positioning error in the tested urban canyon area.     

中国夏季风暴之路径与其雨量之分布

作者为明瞭中国温带风暴及台风雨量分布之情形及其与路径之关系,特取民国二十四年夏季(六月至八月)经过中国本部之温带风暴及登陆之台风,逐一分别检讨。先作各日上午六时之风暴路径图,然     

Wave boundary layers in rough turbulent flow

A one-layer time-invariant eddy viscosity model is specified to develop a mathematical model for describing the essential features of the turbulent wave boundary layer over a rough bed. The functional form of the eddy viscosity is evaluated based on a modified one-equation turbulence model in which the eddy viscosity varies in time and space. The present eddy viscosity model simplifies much of the mathematical complexity in many existing models. Predictions from the present model have been compared favorably with a wide range of experimental data. It is found that the eddy viscosity model adopted in the present study is physically reasonable.