Tools and concepts on ecological quality of coastal and estuarine environments     

Ducrotoy JP  Yanagi T 《Marine pollution bulletin》2008,57(1-5):1-2

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Evaluation of Vector Winds Observed by NSCAT in the Seas around Japan     

Harunobu Masuko  Kohei Arai  Naoto Ebuchi  Masanori Konda  Masahisa Kubota  Kunio Kutsuwada  Teruko Manabe  Akira Mukaida  Tetsuo Nakazawa  Atsushi Nomura  Akira Shibata  Yoshihiko Tahara 《Journal of Oceanography》2000,56(5):495-505

In order to validate wind vectors derived from the NASA Scatterometer (NSCAT), two NSCAT wind products of different spatial resolutions are compared with observations by buoys and research vessels in the seas around Japan. In general, the NSCAT winds agree well with the wind data from the buoys and vessels. It is shown that the root-mean-square (rms) difference between NSCAT-derived wind speeds and the buoy observations is 1.7 ms^–1, which satisfies the mission requirement of accuracy, 2 ms^–1. However, the rms difference of wind directions is slightly larger than the mission requirement, 20°. This result does not agree with those of previous studies on validation of the NSCAT-derived wind vectors using buoy observations, and is considered to be due to differences in the buoy observation systems. It is also shown that there are no significant systematic trends of the NSCAT wind speed and direction depending on the wind speed and incidence angle. Comparison with ship winds shows that the NSCAT wind speeds are lower than those observed by the research vessels by about 0.7 ms^–1 and this bias is twice as large for data observed by moving ships than by stationary ships. This result suggests that the ship winds may be influenced by errors caused by ship's motion, such as pitching and rolling.  相似文献   

Seasonal variation in the behavior of tailing wastes in Buyat Bay, Indonesia     

Prisetiahadi K  Yanagi T 《Marine pollution bulletin》2008,57(1-5):170-181

Seasonal variations in temperature, salinity, sigma-t and light transmittance were investigated in Buyat Bay, Indonesia, related to the dumping activity there. More than 2000 tons per day of tailings were disposed through a Submarine Tailing Disposal (STD) method at 82 m depth in Buyat Bay. An 80 m depth of the assumed pycnocline was not well confirmed. The seasonal variability of temperature, salinity and sigma-t showed the pycnocline of 40 m to 135 m at the deepest observation station (140 m) during 1997. Furthermore, the Mixed Layer Depth was in good agreement with the wind stress, and the wind stress affected the spreading of tailings there. The outlet of submarine tailing disposal must be below 135 m in Buyat Bay.  相似文献   

ASTE observations of the massive-star forming region Sgr B2: a giant impact scenario     

Tetsuo Hasegawa  Takaaki Arai  Nobuyuki Yamaguchi  Fumio Sato 《Astrophysics and Space Science》2008,313(1-3):91-94

We report mapping observations of a 35 pc × 35 pc region covering the Sgr B2 molecular cloud complex in the ¹³CO (3-2) and the CS (7-6) lines using the ASTE 10 m telescope with high angular resolution. The central region was mapped also in the C¹⁸O (3-2) line. The images not only reproduce the characteristic structures noted in the preceding millimeter observations, but also highlight the interface of the molecular clouds with a large velocity jump of a few tens of km s⁻¹. These new results further support the scenario that a cloud–cloud collision has triggered the formation of massive cloud cores, which form massive stars of Sgr B2. Prospects of exciting science enabled by ALMA are discussed in relation to these observations.  相似文献   

Effects of soil-structure interaction on seismic response of PC cable-stayed bridge     

Jingzhe Zheng  Tetsuo Takeda 《Soil Dynamics and Earthquake Engineering》1995,14(6):427-437

This paper attempts to assess the effects of dynamic soil-structure interaction (SSI) on the seismic behavior of a PC cable-stayed bridge placed on a moderately deep soil stratum overlying rigid bedrock, and to evaluate the applicability of a simple mass-spring model in evaluating SSI. Parametric analysis is performed to investigate the significance of SSI under various stiffness, foundation depth conditions using finite element methods. The applicability of a mass-spring model is discussed by comparison with FEM. The results of analysis reveal the influence of SSI on the seismic behavior of bridge-soil system, and recommendations for aseismic design are provided. The mass-spring model proves to be promising for representing the seismic behavior of the bridge-soil system, and the mechanism is interpreted in detail.  相似文献   

Effects of environmental gradients concerning water qualities on the structure of the phytoplankton community in the coastal sea     

Tetsuo Mukai  Kazuto Takimoto 《Estuarine, Coastal and Shelf Science》1985,20(2):169-181

The effects on the structure of the phytoplankton community of in situ environmental gradients concerning water qualities, formed during the mixing process of coastal with oceanic waters, were investigated on macro scale over a wide area of the Seto Inland Sea, Japan.The community structure of the phytoplankton varied almost constantly along the in situ environmental gradients in the community, which was shown by use of the diversity index rather than a mere listing of the phytoplankton community. These observations were considered to be the result of the direct or indirect response of the phytoplankton community to environmental gradients which occur in situ, which mean a series of variations of the habitat of the phytoplankton community. Their effects were reflected not in biomass but in the structure of the phytoplankton community. It was difficult to establish quantitatively the extent of their effects because of the variability in the degree of the environmental gradients which occur in situ.  相似文献   

Kurosegawa zone and its bearing on the development of the Japanese Islands     

Shigenori Maruyama  Shohei Banno  Tetsuo Matsuda  Takashi Nakajima 《Tectonophysics》1984,110(1-2)

The Kurosegawa zone in southwest Japan is a 600 km long serpentinite mélange in the Chichibu terrains. It runs generally E-W but is slightly oblique to the subparallel arrangement of the Ryoke, Sanbagawa and Chichibu belts of Southwest Japan. A variety of geological units occurs in the Kurosegawa zone:

1. (1) granodiorite, gneiss and amphibolite of ca. 400 Ma,

2. (2) Siluro-Devonian formations,

3. (3) Upper Carboniferous to Jurassic formations,

4. (4) Upper Jurassic to Lower Cretaceous formations,

5. (5) serpentinite and

6. (6) low- to medium-grade metamorphic rocks of various baric types (ages, 220, 320, 360 and 420 Ma by K-Ar).

The most widespread is a high-pressure intermediate group of metamorphic rocks. Serpentinite is emplaced along the faults between and within the constituent units.Rocks of the Kurosegawa zone represent a mature orogenic belt along a continental margin or an island arc. Its original site as constrained by paleomagnetism was near the equatorial area. Here, 400 Ma old paired metamorphism and related magmatism took place. The island arc or microcontinent migrated northward to collide with the Eurasia plate during Late Jurassic, thus consuming the intervening ocean.  相似文献   

Stability field of knorringite Mg₃Cr₂Si₃O₁₂ at high pressure and its implication to the occurrence of Cr-rich pyrope in the upper mantle     

Tetsuo Irifune  Eiji Ohtani  Mineo Kumazawa 《Physics of the Earth and Planetary Interiors》1982,27(4):263-272

The stability field of knorringite (Mg₃Cr₂Si₃O₁₂) is studied experimentally. Knorringite is stable at pressures above 10.5 GPa at 1200°C and 11.8 GPa at 1400°C. Below these pressures, knorringite decomposes to enstatite + eskolaite. A phase diagram of the pyrope-knorringite system is described based on the available experimental data. The solubility of the knorringite molecule in pyrope is essentially dependent only on pressure, and the Cr/Cr+Al value of garnet is considered to be an indicator of the minimum pressure of equilibration. Consideration of the genesis of Cr-rich pyrope and other peridotitic inclusions in diamonds indicates that the fractionation process should have taken place, at least at depths to ca. 240 km, to give rise to the Cr-rich complement of Cr-poor upper mantle materials such as undepleted lherzolite. The knorringite-rich peridotitic suite in diamond will be identified with this complement, which may be the material constituting the deep upper mantle.  相似文献   

A model tank test using artificial ground freezing — with an in-ground lng storage tank in view     

Tetsuo Akiyama  Mizuhito Iguro   《Engineering Geology》1981,18(1-4):395-408

As a clean form of energy able to replace oil, the demand for LNG (Liquefied Natural Gas) has been increasing. LNG must be stored in a cryogenic temperature of —162°C. The storage tanks now existing throughout the world can be divided into above-ground and inground types. In the Tokyo area, there are now 22 in-ground LNG storage tanks, either in operation or under construction, which are constructed with primary consideration given to safety and earthquake-proof design because of the circumstances around the LNG terminals.

In the feasibility study of a very large-scale, in-ground LNG storage tank, comparative preliminary studies were made of various construction methods. Among them, the method using artificial ground freezing was proposed, in which it was planned to utilize the frozen soil as the means of ground water control and the temporary retaining wall. To confirm the feasibility of the design, a model tank test was conducted by freezing the actual tank yard. The yard ground, composed of sand and silt layers, was artificially frozen 10 m in diameter and 50 m in depth; in the frozen soil a shaft of 4 m in diameter was sunk to a depth 26 m below the ground level for various tests and measurements. The purpose of the test was mainly to confirm the construction method and to examine the agreement between theory and practice.

Although this construction method has not been adopted in the actual tank work, the feasibility of the method itself has been confirmed as a result of the test. In this paper, the outline and major results of the test and analysis are described.  相似文献   

Trace element composition and degree of partial melting of pelitic migmatites from the Aoyama area, Ryoke metamorphic belt, SW Japan: Implications for the source region of tourmaline leucogranites   总被引：1，自引：1，他引：0  

Tetsuo Kawakami  Tomoyuki Kobayashi 《Gondwana Research》2006,9(1-2):176

Degree of partial melting of pelitic migmatites from the Aoyama area, Ryoke metamorphic belt, SW Japan is determined utilizing whole-rock trace element compositions. The key samples used in this study were taken from the migmatite front of this area and have interboudin partitions filled with tourmaline-bearing leucosome. These samples are almost perfectly separated into leucosome (melt) and surrounding matrix (solid). This textural feature enables an estimate of the melting degree by a simple mass-balance calculation, giving the result of 5–11 wt.% of partial melting. Similar calculations applied to the migmatite samples, which assume average migmatite compositions to be the residue solid fraction, give degree of melt extraction of 12–14 wt.% from the migmatite zone. The similarity of the estimated melting degree of 5–11 wt.% with that in other tourmaline–leucogranites, such as Harney Peak leucogranite and Himalayan leucogranites, in spite of differences in formation process implies that the production of tourmaline leucogranites is limited to low degrees of partial melting around 10 wt.%, probably controlled by the breakdown of sink minerals for boron such as muscovite and tourmaline at a relatively early stage of partial melting. Because the amount of boron originally available in the pelitic source rock is limited (on average 100 ppm), 10 wt.% of melting locally requires almost complete breakdown of boron sink mineral(s) in the source rock, in order to provide sufficient boron into the melt to saturate it in tourmaline. This, in turn, means that boron-depleted metapelite regions are important candidates for the source regions of tourmaline leucogranites.  相似文献