Three-dimensional analysis of groundwater flow in neogene rocks at the Rokkasho low-level radioactive waste disposal center, Japan

As a preliminary step for predicting groundwater flow in a plateau 30–50 m above sea level, a model for three-dimensional analysis of groundwater flow was formulated and its validity was verified. The plateau consists of Neogene sedimentary rocks and a Quaternary deposit. Most of the groundwater originates in precipitation, with the groundwater table lying in the Quaternary deposit. Steady-state analysis was conducted by using the finite element method. The results of pore-water pressure measurement and water examination were useful in verifying the validity of the model. In constructing the model, reducing the hydraulic conductivity according to the depth on the basis of the results of the actual measurement was important.     

Estimation of Response Spectra in the Severely Damaged Area During the 1995 Hyogo-Ken Nambu Earthquake

We calculated theoretical acceleration response spectra at the ground surface in the region near the 1995 Hyogo-ken Nambu earthquake source based on the spectral moment method. To estimate earthquake motion on the ground surface, a formula of earthquake motion at base rock level was derived. The amplification effect of the ground was introduced by using multiple reflection theory. Theoretically estimated response spectrum were modified by the response spectra calculated using observed earthquake motions.     

Estimating the spatial distribution of dredged material disposed of at sea using particle-size distributions and metal concentrations

We present a method to estimate the spatial distribution of dredged material disposed of at sea. Using both dredged sediments and samples of sea-bed sediment from near the Rame Head disposal site, Plymouth, UK, we applied entropy analysis to the <63 μm sediment fraction and combined the results with the trace metal data in the same fraction, to form a series of groups. We interpret the distribution of sediments in one group (F1) to approximate the distribution of material affected by the disposal site. This distribution includes locations close to the disposal site, and also locations <4 km to the SE and SW, <6 km to the NW and <2 km to the N. This approach demonstrates the feasibility of using trace metal analysis of particular grain size fractions to reduce uncertainty in interpreting the spatial distribution of impacts of dredge disposal.     

Study of the structure of silica film by infrared spectroscopy and electron diffraction analyses

Amorphous silicon oxide films have been studied on the basis of electron diffraction (ED) analyses and infrared (IR) spectroscopy in order to elucidate the relationship between the structures. After the heat treatment of the film in air at 300 and 500°C, the ED pattern showed halo rings, and the IR spectra clearly changed. Intensity analysis of the ED pattern provided evidence for the structural change of the amorphous film. It was concluded that the spectral changes in the ranges of 9.2–10.2, 12.5–13.5 and 19.5–22.5 μm were the result of phase transitions of the microcrystallites of α-cristobalite to β-cristobalite, and α- or β-quartz. Astrophysical implications have been discussed.     

白鱀豚哨叫声的研究

于1996年1月,在中国科学院水生生物研究所白暨豚馆人工饲养池和湖北省石首市天鹅洲长江故道,使用频响范围分别为0－100kHz和0－16kHz的磁带记录系统,记录了一头成年雄性和一头成年雌性白暨豚的哨叫声。采用计算机信号分析系统详细分析了哨叫声的结构和声谱图,并与其它鲸类哨叫声进行比较。结果表明,白暨豚哨叫声的最大和最小频率平均值分别为5841Hz和4975Hz,频率变化幅度一般小于1000Hz。哨叫声平均持续时间为907ms。频率随时间变化不连续,且较平缓,起伏很少,有部分重叠现象。白暨豚哨叫声的结构与另一种淡水豚─—亚河豚相近,但相对于一些海洋性种类（如宽吻海豚）则呈现较大的差异,表现出对环境的高度适应性。