Actual seismic response controlled building with semi-active damper system

This paper presents the first application of a semi-active damper system to an actual building. The Semi-active Hydraulic Damper (SHD) can produce a maximum damping force of 1000 kN with an electric power of 70 W. It is compact, so a large number of them can be installed in a single building. It is thus possible to control the building's response during a severe earthquake, because a large control force is obtained in comparison with a conventional active control system. This paper outlines the building, the control system configuration, the SHD, the control method using a Linear Quadratic Regulator, the response analysis results of the controlled building, and the dynamic loading test results of the actual SHD. The simulation analysis shows that damage to buildings can be prevented in a severe earthquake by SHD control. The dynamic loading test results of the SHD are reported, which show that the specified design values were obtained in the basic characteristic test. The control performance test using simulated response time histories, also shows that the damping force agrees well with the command. Finally, it is confirmed that the semi-active damper system applied to an actual building effectively controls its response in severe earthquakes. Copyright © 1999 John Wiley & Sons Ltd.     

达拉布特蛇绿岩带镁铁质岩的地球化学

达拉布特蛇绿岩带的镁铁质岩属亚碱性和碱性系列,可能是弧后盆地火册活动的产物。根据镁铁质岩的层位关系、岩浆来源和微量元素特征,可将该盆地的地质演化概括为扩张阶段和封闭阶段。盆地扩张阶段早、中期喷发的镁铁质岩具有低的稀土和不相容元素丰度,而在盆地封闭阶段晚期喷发的碱性玄武岩,其特点是稀土和大多数不相容元素丰度极大增高,其稀土元素分布模式为轻稀土元素强烈富集型。     

Density Current Descending along Continental Slope and the Associated Deep Water Formation: Two-Dimensional Numerical Experiments with a Nonhydrostatic Model

Numerical experiments with a two-dimensional nonhydrostatic ocean model have been carried out to investigate the dynamical process of descending density current on a continental slope. The associated deep water formation has been also examined by tracking labeled particles. The descending flow along the continental slope occurs in the bottom Ekman layer. The net pressure gradient determining the volume transport consists of not only the pressure gradient due to density deviation but also the surface pressure gradient due to the depth-mean alongshore flow. Since these constituents have the opposite signs and strengthen each other, the oscillation with an alternation of intense up- and downslope flows appears around the shelf break. This temporal variation of the flow field causes the effective mixing on the slope between descending shelf and interior waters and forms the deep water as a mixture of them at a ratio of about 1:3. The present result is applied to the slope current around Antarctica, using velocity and density fields calculated by an ocean general circulation model. The Ekman volume transport is estimated at 0.97 Sv (1 Sv = 10⁶ m³s^–1) in the Weddell Sea, 0.35 Sv in the Ross Sea, and 1.8 Sv in total. About 70% of them is attributed to the depth-mean alongshore flow, such as the East Wind Drift and the Weddell Gyre driven by the wind. This suggests that the pressure gradient due to other factors than density deviation may play an important role in the deep and bottom water formation in the actual oceans.     

The Monsoon in the Arabian Sea: Implications From Radiolarian Fluxes to the Deep Sea

THE MONSOON IN THE ARABIAN SEA:IMPLICATIONS FROM RADIOLARIAN FLUXES TO THE DEEP SEA     

TeV γ-rays from old supernova remnants

We study the emission from an old supernova remnant (SNR) with an age of around 10⁵ yr and that from a giant molecular cloud (GMC) encountered by the SNR. When the SNR age is around 10⁵ yr, proton acceleration is efficient enough to emit TeV γ-rays both at the shock of the SNR and that in the GMC. The maximum energy of primarily accelerated electrons is so small that TeV γ-rays and X-rays are dominated by hadronic processes,  π⁰  -decay and synchrotron radiation from secondary electrons, respectively. However, if the SNR is older than several 10⁵ yr, there are few high-energy particles emitting TeV γ-rays because of the energy-loss effect and/or the wave-damping effect occurring at low-velocity isothermal shocks. For old SNRs or SNR–GMC interacting systems capable of generating TeV γ-ray emitting particles, we calculated the ratio of TeV γ-ray (1–10 TeV) to X-ray (2–10 keV) energy flux and found that it can be more than  ∼10²  . Such a source showing large flux ratio may be a possible origin of recently discovered unidentified TeV sources.     

In-situ dissolution experiment of radiolaria in the central North Pacific ocean

Monospecific phaeodarian radiolarian assemblages of Castanidium longispinum were suspended in plastic cages built with 225 μm nylon mesh at different water depths from 378 to 5582 m in the central North Pacific. Weight losses of these samples after a suspension period of 61 days were used to determine dissolution rates. The highest weight losses were observed at 378 m where samples lost ～90% of their initial weight. Through the main thermocline weight losses decreased from 90 to 60% and reached a constant value of 40% below it. These weight losses are roughly an order of magnitude higher than those reported by earlier workers. The higher weight losses can be attributed in part to the more soluble nature of the phaeodarian radiolarian skeletons and in part to the improved experimental technique. Kinetic considerations show that temperature is the major factor that controls silica dissolution rates in the ocean. Using an Arrehnius plot for the apparent rate constants, it can be shown that in surface water dissolution rats should be two orders of magnitude higher than in deep water below the main thermocline.     

Stoichiometric control of crystal/liquid single-component partition coefficients

Single-component (e.g., single-element) partition coefficients for silicate melts and the minerals that crystallize from them typically show large variations with temperature and melt composition. It is shown that, in particular cases, these variations can be calculated from two-component distribution coefficients that are practically constants, given the structural formula of the mineral and the melt composition.     

1991年江淮特大暴雨的降水性质与对流活动

从计算大尺度热源和分析ＴＢＢ资料两个方面，阐述了１９９１年江淮梅雨期间降水性质与对流活动的季节性演变特征。结果表明：梅雨期间江淮上空３个强上升运动时段分别形成了３场暴雨，由暴雨释放的热量使江淮大气出现了３个时段的强加热；３场暴雨的降水性质呈显著的季节性演变，由第１场暴雨以锋面性降水为主发展到第３场暴雨异常强的对流性降水。文中详细分析了热源和水汽汇的时空分布特征，并从大气运动场和热力结构讨论了盛夏强对流降水期间积云对流以涡动形式对热量和水汽的强铅直输送作用。江淮地区ＴＢＢ值能很好地反映降水状况，雨期一致地对应于ＴＢＢ低于２５０Ｋ的时段。梅雨中后期东亚地区对流活动季节性地增强，带状对流区（特别是ＴＢＢ高负距平区）与雨带位置相符。对流带位置及对流活动强弱与西南暖湿气流活动密切相关，它很好地表征了东亚地区的低空急流（给积云输送热带对流大气）。梅雨期间对流带主要出现在江淮流域，但可在东亚范围内飘移，它落在江淮与否则决定了江淮暴雨的维持与中断     

P-T history of a mantle diapir: the Horoman peridotite complex,Hokkaido, northern Japan

The Horoman peridotite complex, Hokkaido, Japan is divided into Lower and Upper zones on the basis of contrasting geological features. The complex recorded a consecutive decompression history in chemical zoning of pyroxenes and plagioclase in plagioclase lherzolite, which is interpreted to have been derived from garnet lherzolite by subsolidus decompression reactions. In the Lower Zone, and earlier decompression history is clearly preserved in large pyroxene porphyroclasts, which show marked M-shaped Al zoning characterized by low Al concentration at the core (Al=0.12/6 oxygens), gradual increase toward the marginal region, and rapid decrease toward the rim. The Ca content in the core is nearly constant (Ca=0.03/6 oxygens) with slight increase toward the margin followed by abrupt decrease toward the rim. The Al and Ca contents in the core of orthopyroxene in plagioclase lherzolite from the Upper Zone (Al=0.22, Ca=0.055/6 oxygens) are much higher than those for the Lower Zone, and the Al content typically decreases monotonously from the core to the rim with several exceptions that show poorly developed M-shaped zoning profiles. The earliest P-T conditions, inferable from the core compositions of pyroxenes are 900–950°C and 20 kbar for the Lower Zone and 1100–1150°C and 20 kbar for the Upper Zone. The increase of Al from the core to the margin is inferred to have resulted from nearly adiabatic decompression from these conditions into spinel peridotite facies. The complex experienced further decompression from the spinel stability field into the plagioclase stability field, which is inferred from plagioclase zoning in fine-grained aggregates composed mostly of plagioclase, chromite spinel, and olivine with minor pyroxenes. The Na-Ca ratio of each plagioclase grain decreases from the core to the rim, suggesting continuous decompression reaction producing olivine and plagioclase from pyroxenes and spinel. The sharp increase in Ca content toward the rim indicates that fairly rapid cooling associated with decompression is necessary to form and preserve the marked zoning. The sharp decrease in Al and Ca contents toward the rim of orthopyroxene was also formed during this final ascent of the complex. The systematic changes of the mineralogic and petrographic features that are gradational between the Lower and Upper zones suggest that the Horoman complex retains a temperature variation from the upper mantle. The Upper Zone is interpreted to have followed a higher temperature decompression path than the Lower Zone and probably represents a relatively hotter portion of a mantle diapir ascending from a depth greater than 60 km in the upper mantle.     

The distribution of chlorophylla,protein, RNA and DNA in the North Pacific Ocean

Chla, protein, RNA and DNA were measured in 400 samples taken from the surface down to 5,000 m at 27 oceanographical stations in the North Pacific Ocean. Two section diagrams of these cellular constituents were given along 155°E and 155°W meridians, and several vertical profiles of the four constituents were also given at some stations near Japan. The average concentration ranges of Chla, protein, RNA and DNA obtained in this study area were 0.025–0.862, 11.4–88.1, 1.36–35.3 and 0.13–5.24g/l, respectively. Chla was distributed mostly in the photic zone as we would expect. However protein, RNA were in high concentrations within the photic zone and sometimes extremely high concentrations in the deep aphotic zone.