High-Nb hawaiite–mugearite and high-Mg calc-alkaline lavas from northeastern Iran: Oligo-Miocene melts from modified mantle wedge     

Parham Ahmadi  Massimo Coltorti  Takeshi Kuritani  Yue Cai  Anna Maria Fioretti 《International Geology Review》2019,61(2):150-174

Tertiary volcanic rocks in northwestern Firoozeh, Iran (the Meshkan triangular structural unit), constitute vast outcrops (up to 250 km²) of high-Mg basaltic andesites to dacites that are associated with high-Nb hawaiites and mugearites. Whole-rock ⁴⁰Ar/³⁹Ar ages show a restricted range of 24.1 ± 0.4–22.9 ± 0.5 Ma for the volcanic rocks. The initial ratios of ⁸⁷Sr/⁸⁶Sr and ¹⁴³Nd/¹⁴⁴Nd vary from 0.703800 to 0.704256 and 0.512681 to 0.512877, respectively, in the high-Mg basaltic andesites–dacites. High-Th contents (up to 11 ppm) and Sr/Y values (27–100) and the isotopic composition of the subalkaline high-Mg basaltic andesites–dacites indicate derivation from a mantle modified by slab and sediment partial melts. Evidence such as reverse zoning and resorbed textures and high Ni and Cr contents in the evolved samples indicate that magma mixing with mafic melts and concurrent fractional crystallization lead to the compositional evolution of this series. The high-Nb hawaiites and mugearites, by contrast, have a sodic alkaline affinity and are silica undersaturated; they are also enriched in Nb (up to 47 ppm) and a wide range of incompatible trace elements, including LILE, LREE, and HFSE. Geochemistry and Sr–Nd isotopic compositions of the high-Nb hawaiites and mugearites suggest derivation from a mantle source affected by lower degrees of slab melts. Post-orogenic slab break-off is suggested to have prompted the asthenospheric upwelling that triggered partial melting in mantle metasomatized by slab-derived melts.  相似文献   

Bayesian and Neural Network Approaches to Estimate Deep Temperature Distribution for Assessing a Supercritical Geothermal System: Evaluation Using a Numerical Model     

Ishitsuka  Kazuya  Kobayashi  Yosuke  Watanabe  Norihiro  Yamaya  Yusuke  Bjarkason  Elvar  Suzuki  Anna  Mogi  Toru  Asanuma  Hiroshi  Kajiwara  Tatsuya  Sugimoto  Takeshi  Saito  Ryoichi 《Natural Resources Research》2021,30(5):3289-3314

The temperature distribution at depth is a key variable when assessing the potential of a supercritical geothermal resource as well as a conventional geothermal resource. Data-driven estimation by a machine-learning approach is a promising way to estimate temperature distributions at depth in geothermal fields. In this study, we developed two methodologies—one based on Bayesian estimation and the other on neural networks—to estimate temperature distributions in geothermal fields. These methodologies can be used to supplement existing temperature logs, by estimating temperature distributions in unexplored regions of the subsurface, based on electrical resistivity data, observed geological/mineralogical boundaries, and microseismic observations. We evaluated the accuracy and characteristics of these methodologies using a numerical model of the Kakkonda geothermal field, Japan, where a temperature above 500 °C was observed below a depth of about 3.7 km. When using geological and geophysical knowledge as prior information for the machine learning methods, the results demonstrate that the approaches can provide subsurface temperature estimates that are consistent with the temperature distribution given by the numerical model. Using a numerical model as a benchmark helps to understand the characteristics of the machine learning approaches and may help to identify ways of improving these methods.

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Reducing global GHG emissions by replicating successful sector examples: the ‘good practice policies’ scenario     

Mark Roelfsema  Hanna Fekete  Niklas Höhne  Michel den Elzen  Nicklas Forsell  Takeshi Kuramochi 《Climate Policy》2018,18(9):1103-1113

This article shows the potential impact on global GHG emissions in 2030, if all countries were to implement sectoral climate policies similar to successful examples already implemented elsewhere. This assessment was represented in the IMAGE and GLOBIOM/G4M models by replicating the impact of successful national policies at the sector level in all world regions. The first step was to select successful policies in nine policy areas. In the second step, the impact on the energy and land-use systems or GHG emissions was identified and translated into model parameters, assuming that it would be possible to translate the impacts of the policies to other countries. As a result, projected annual GHG emission levels would be about 50 GtCO₂e by 2030 (2% above 2010 levels), compared to the 60 GtCO₂e in the ‘current policies’ scenario. Most reductions are achieved in the electricity sector through expanding renewable energy, followed by the reduction of fluorinated gases, reducing venting and flaring in oil and gas production, and improving industry efficiency. Materializing the calculated mitigation potential might not be as straightforward given different country priorities, policy preferences and circumstances.

Key policy insights

• Considerable emissions reductions globally would be possible, if a selection of successful policies were replicated and implemented in all countries worldwide.

• This would significantly reduce, but not close, the emissions gap with a 2°C pathway.

• From the selection of successful policies evaluated in this study, those implemented in the sector ‘electricity supply’ have the highest impact on global emissions compared to the ‘current policies’ scenario.

• Replicating the impact of these policies worldwide could lead to emission and energy trends in the renewable electricity, passenger transport, industry (including fluorinated gases) and buildings sector, that are close to those in a 2°C scenario.

• Using successful policies and translating these to policy impact per sector is a more reality-based alternative to most mitigation pathways, which need to make theoretical assumptions on policy cost-effectiveness.

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A new, automatic hydrothermal fluid sampler using a shape-memory alloy   总被引：2，自引：0，他引：2  

Takeshi Naganuma  Masanori Kyo  Tatsuhiko Ueki  Kazuhiko Takeda  Jun-ichiro Ishibashi 《Journal of Oceanography》1998,54(3):241-246

A new hydrothermal fluid sampler has been developed to provide more maneuverability in underwater operation. The sampler characteristically employs a shape-memory alloy, which senses high temperature and actuates the suction mechanism. A shape-memory alloy is also used to switch the intake valve of the sampler, the intention being to avoid missampling when the inlet is in low temperature water. Prototype samplers were designed to collect the fluids hotter than 80°C. Test sampling was performed at hydrothermal vents (1372–1374 m deep) in the submarine volcano, Suiyo Seamount, Izu-Bonin Arc, northwestern Pacific. Observed fluid temperature was between 138 and 298°C, while the ambient seawater temperature was 3.1°C. Each prototype collected about 100 ml fluid as designed. The magnesium concentration in the samples indicated a seawater content of 47.5–90.8%, which indicates the entrainment of ambient seawater. Microscopic observatinn revealed the occurrence of microorganisms in the sample fluids at a population density of 10⁵ to 10⁶ cells ml⁻¹, which is 2–3 orders of magnitude higher than those in seawater at that depth. The use of the newly developed fluid sampler will greatly facilitate the collection of vent-associated microorganisms, which are of potential biological and biotechnological interest.  相似文献   

A Continuous and Mechanistic Representation of Calcite Reaction-Controlled Kinetics in Dilute Solutions at 25°C and 1 Atm Total Pressure     

Takeshi Arakaki  Alfonso Mucci 《Aquatic Geochemistry》1999,5(2):225-225

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Metamorphic condition of a regional metamorphic complex in the Omuta district in northern Kyushu,southwest Japan          下载免费PDF全文

Takeshi Ikeda  Kazuhiro Miyazaki  Hirohisa Matsuura 《Island Arc》2017,26(5)

A high‐temperature (T) metamorphic complex occurs in the Omuta district, northern Kyushu, Japan. Three metamorphic zones are defined based on pelitic mineral assemblage, i.e. chlorite–biotite zone, muscovite–andalusite zone and sillimanite–K‐feldspar zone with ascending metamorphic grade from north to south. Two isograds trend approximately east–west, which is oblique to the boundary between the metamorphic complex and the Tamana Granodiorite located on the southeast. The metamorphic condition of two pelitic rocks that occur in the muscovite–andalusite zone and sillimanite–K‐feldspar zone are estimated as 510 ±30 °C, 300 ±60 MPa and 720 ±30 °C, 620 ±60 MPa, respectively. Thermodynamic consideration reveals that use of the same geothermobarometer enables precise determination of the difference in pressure between the samples as 320 ±10 MPa. This indicates that the pelitic samples were metamorphosed at different depth by 11–12 km that is significantly larger than the geographic distance of 6.8 km between the sample localities. This also suggests that crustal thinning took place after the high‐T metamorphism. The high‐T metamorphic complex is, therefore, not of static contact metamorphism but of dynamic regional metamorphism. The present result combined with petrological and chronological similarities implies that this complex suffered the regional Ryoke metamorphism.  相似文献   

<Emphasis Type="Italic">Clostridium difficile</Emphasis> infection incidence prediction in hospitals (CDIIPH): a predictive model based on decision tree and fuzzy techniques     

Gyan?Chhipi-ShresthaEmail author  Julie?Mori  Kasun?Hewage  Rehan?Sadiq 《Stochastic Environmental Research and Risk Assessment (SERRA)》2017,31(2):417-430

Several risk factors associated with the increased likelihood of healthcare-associated Clostridium difficile infection (CDI) have been identified in the literature. These risk factors are mainly related to age, previous CDI, antimicrobial exposure, and prior hospitalization. No model is available in the published literature that can be used to predict the CDI incidence using healthcare administration data. However, the administrative data can be imprecise and may challenge the building of classical statistical models. Fuzzy set theory can deal with the imprecision inherent in such data. This research aimed to develop a model based on deterministic and fuzzy mathematical techniques for the prediction of hospital-associated CDI by using the explanatory variables controllable by hospitals and health authority administration. Retrospective data on CDI incidence and other administrative data obtained from 22 hospitals within a regional health authority in British Columbia were used to develop a decision tree (deterministic technique based) and a fuzzy synthetic evaluation model (fuzzy technique based). The decision tree model had a higher prediction accuracy than that of the fuzzy based model. However, among the common results predicted by two models, 72 % were correct. Therefore, this relationship was used to combine their results to increase the precision and the strength of evidence of the prediction. These models were further used to develop an Excel-based tool called C. difficile Infection Incidence Prediction in Hospitals (CDIIPH). The tool can be utilized by health authorities and hospitals to predict the magnitude of CDI incidence in the following quarter.  相似文献   

Dynamic loading tests and seismic response analysis of a stud-type damper composed of multiple friction units with disc springs     

Takeshi Sano  Kazutaka Shirai  Yasumasa Suzui  Yoshikazu Utsumi 《地震工程与结构动力学》2020,49(13):1259-1280

This paper presents an experimental study on the performance of a shear-sliding stud-type damper composed of multiple friction units with high-tension bolts and disc springs. A numerical evaluation of the response reduction effects achieved by the stud-type damper is also presented. In dynamic loading tests, the behavior of stud-type multiunit friction damper specimens was investigated. Three different full-scale damper specimens, which were composed of five, six, or seven friction units with two or four sliding surfaces, were incorporated into loading devices for testing. The stud-type friction dampers demonstrated stable rigid-plastic hysteresis loops without any remarkable decrease in the sliding force even when subjected to repetitive loading, in addition to showing no unstable behavior such as lateral buckling. The damper produced a total sliding force approximately proportional to the number of sliding surfaces and friction units. The total sliding force of the stud-type damper can thus be estimated by summing the contributions of each friction unit. In an earthquake response simulation, the control effects achieved by stud-type dampers incorporated into an analytical high-rise building model under various input waves, including long-period, long-duration and pulse-like ground motions, were evaluated. A satisfactory response reduction was obtained by installing the developed stud-type dampers into the main frame without negatively impacting usability and convenience in terms of building planning.  相似文献   

An ethnoarchaeological study of chemical residues in the floors and soils of Q'eqchi' Maya houses at Las Pozas,Guatemala     

Fabin G. Fernndez  Richard E. Terry  Takeshi Inomata  Markus Eberl 《Geoarchaeology》2002,17(6):487-519

This ethnoarchaeological study at the Q'eqchi' Maya village of Las Pozas, Guatemala, aimed to refine the understanding of the relationship between soil chemical signatures and human activities for archaeological applications. The research involved phosphorus, exchangeable ion (calcium, potassium, magnesium, sodium), and trace element analysis of soils and earth floors extracted by Mehlich II, ammonium acetate, and DTPA chelate solutions, respectively. The results showed high levels of phosphorus, potassium, magnesium, and pH in food preparation areas, as well as high phosphorus concentrations and low pH in food consumption areas. The traffic areas exhibited low phosphorus and trace element contents, whereas refuse disposal areas were enriched. These results provide important information for the understanding of space use in ancient settlements. © 2002 Wiley Periodicals, Inc.  相似文献   

Simulation analyses of buildings damaged in the 1995 Kobe,Japan, earthquake considering soil–structure interaction     

Yasuhiro Hayashi  Kazuo Tamura  Masafumi Mori  Ikuo Takahashi 《地震工程与结构动力学》1999,28(4):371-391

A series of studies was conducted on three buildings of steel reinforced concrete structures with RC shear walls damaged in the 1995 Hyogo-ken Nanbu earthquake. These buildings are located in an area where structural damage centred around. Two of these buildings suffered severe damage, while the third was not structurally damaged. Our studies deal with site inspections, including micro-tremor measurement of buildings, the evaluation of input motions, and the response analyses considering soil–structure interaction. The results of simulation analyses of the two severely damaged buildings correspond to their actual damage state. From the response analyses of the one slender building with no structural damage, it was concluded that uplifting is the main reason it did not suffer any structural damage. Through these studies, the importance of soil–structure interaction and effective input motion is fully understood. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献