针对IPCC评估报告中海洋碳循环的疑问——δ¹³C收支平衡法的验证   总被引：2，自引：0，他引：2  

姜爱军  陈中笑  任慧军  程军  加藤喜久雄  大森保 《气候变化研究进展》2008,4(6):369-375

 通过对比IPCC历次评估报告中全球碳循环的收支发现,尽管评估报告在估算各主要碳库及其间的通量时差别不大,但表层至中深层海水间溶解无机碳通量却存在巨大差异。利用δ¹³C的收支平衡检验了这一通量的适用范围,结果表明：IPCC 1996年和2007年评估报告对此通量估计过大,而1990年和2001年评估报告估计偏小。  相似文献   

Out‐of‐plane stability of buckling‐restrained braces including moment transfer capacity          下载免费PDF全文

Toru Takeuchi  Hitoshi Ozaki  Ryota Matsui  Fatih Sutcu 《地震工程与结构动力学》2014,43(6):851-869

Buckling‐restrained braces (BRBs) are widely used as ductile seismic‐resistant and energy‐dissipating structural members in seismic regions. Although BRBs are expected to exhibit stable hysteresis under cyclic axial loading, one of the key limit states is global flexural buckling, which can produce an undesirable response. Many prior studies have indicated the possibility of global buckling of a BRB before its core yields owing to connection failure. In this paper, BRB stability concepts are presented, including their bending‐moment transfer capacity at restrainer ends for various connection stiffness values with initial out‐of‐plane drifts, and a unified simple equation set for ensuring BRB stability is proposed. Moreover, a series of cyclic loading tests with initial out‐of‐plane drifts are conducted, and the results are compared with those of the proposed equations. © 2013 The Authors. Earthquake Engineering & Structural Dynamics published by John Wiley & Sons Ltd.  相似文献   

Roles of methane and carbon dioxide in geological processes on Mars     

Goro Komatsu  Gian Gabriele Ori  Marco Cardinale  James M. Dohm  Victor R. Baker  David A. Vaz  Ryo Ishimaru  Noriyuki Namiki  Takafumi Matsui 《Planetary and Space Science》2011,59(2-3):169-181

We discuss in this paper possible roles of methane and carbon dioxide in geological processes on Mars. These volatiles in the martian crust may migrate upward from their sources either directly or via various traps (structural, sedimentary, ground ice, gas hydrates). They are then likely emitted to the atmosphere by seepage or through diverse vent structures. Though gas hydrates have never been directly detected on Mars, theoretical studies favor their presence in the crust and polar caps; they could have played an important role as significant gas reservoirs in the subsurface. The martian gas hydrates would possibly be a binary system of methane and carbon dioxide occupying clathrate cavities. Landforms such as mud volcanoes with well-known linkage to gas venting are extensively distributed on Earth, and methane is the primary gas involved. Thus, identification of these landforms on Mars could suggest that methane and possibly carbon dioxide have contributed to geological processes of the planet. For example, we present a newly identified field in Chryse Planitia where features closely resembling terrestrial mud volcanoes occur widely, though with no observable activity. We also present results of a preliminary search for possible recent or present-day, methane-emission zones in the regions over which enrichments of atmospheric methane have been reported.  相似文献   

Large-eddy simulations of convection-driven dynamos using a dynamic scale-similarity model     

Hiroaki Matsui  Bruce A. Buffett 《地球物理与天体物理流体动力学》2013,107(3):250-276

Dynamo simulations require sub-grid scale (SGS) models for the momentum and heat flux, the Lorentz force, and the magnetic induction. Previous large eddy simulations (LES) using the scale similarity model have represented many aspects of the SGS motion. However, discrepancies are observed due to interchanging the order of filtering operation and spatial differentiation. In this study, we implement a correction term for this commutation error specifically for the scale-similarity model. Furthermore, we implement a dynamic scheme to evaluate time-dependent coefficients for the SGS models. We perform dynamo simulations in a rotating plane layer with different spatial resolutions, and compare results for the time dependence of the large-scale magnetic field. Simulations are performed at two different Rayleigh numbers, using constant values for the other dimensionless numbers (Ekman, Prandtl, and magnetic Prandtl numbers). Both cases show that the dynamic LES can accurately represent the large-scale magnetic field, whereas the dynamo failed in the direct simulations without the SGS terms at the same spatial resolutions. We conclude that the dynamic versions of the SGS and commutation error correction are essential for successful dynamos on coarser grids.  相似文献   

原地应力状态三维分布估算方法的发展及初步应用     

Tanno Takeo  Hirano Toru  Matsui Hiroya  詹自敏 《国际地震动态》2011,(1):91-97

日本原子能机构(Japan Atomic Energy Agency)提出了一种方法,即通过地表原地应力测量所得的有限数据精确估算任意一点的实际原地应力状态分布.我们假定实际地应力是由上覆岩层压力和板块构造力的综合作用形成的,并建立了两种模型:三维有限元模型和边界元模型,模型考虑了地质情况的不均匀性,如岩石类型的变化和...  相似文献   

Role of Acoustic Emission for Solving Rock Engineering Problems in Indonesian Underground Mining   总被引：2，自引：0，他引：2  

Suseno Kramadibrata  Ganda Marihot Simangunsong  Kikuo Matsui  Hideki Shimada 《Rock Mechanics and Rock Engineering》2011,44(3):281-289

In situ stress measurement is not well accepted yet in Indonesia due to the unavailability of technology, high costs and because it is impractical in remote regions. Alternatively, the Kaiser effect of acoustic emission (AE) can be used as a method for determining the stress-state at depth, without creating induced stress and is practical in remote areas. This paper is focused on the development of the AE test. The research has started to study the phenomenon of stress memory in a rock sample, the factors influencing the phenomenon, and finally, to determine the in situ stresses around underground excavations by applying the AE method. It is expected that knowledge in gaining the most important input parameters for maintaining the stability of underground excavations can be well understood and be reliably conducted at a reasonable cost.  相似文献   

Periodic response of a rigid block resting on a footing subjected to harmonic excitation     

Kunihito Matsui  Masashi Iura  Toshimi Sasaki  Iku Kosaka 《地震工程与结构动力学》1991,20(7):683-697

This study presents the dynamic behaviour of a rigid block which rests on a footing supported by a spring and a dashpot on a rigid base. The response of the rigid body is examined carefully when the base is excited by a harmonic force. It is found that a periodic motion appears in three different modes: stick-stick, stick-slip and slip-slip. The conditions that initiate the stick-stick and slip-slip modes are derived in explicit forms and the maximum sliding displacement is also obtained analytically. Useful dimensionless parameters are proposed for the presentation of the dynamic behaviour. The accuracy of results is confirmed by the response history computed by the Nigam-Jennings method.  相似文献   

Temporal Variations in the Dissolved Nutrient Stocks in the Surface Water of the Western North Atlantic Ocean     

Insaf S. Babiker  Mohamed A. A. Mohamed  Kaori Komaki  Keiichi Ohta  Kikuo Kato 《Journal of Oceanography》2004,60(3):553-562

Changes in patterns of undetectability and molar ratios of dissolved nutrients in the euphotic zone of the oligotrophic western North Atlantic Ocean were investigated utilizing the Bermuda Atlantic Time-series Study (BATS) data set of the US Joint Global Ocean Flux Study (JGOFS). Our aim was to examine the temporal dynamics of nutrient stocks over a decade (1989∼1998) and to gain insight into the interactions between the different biotic and abiotic factors underlying BATS. Patterns of nutrient undetectability clearly revealed the depleted nature of the nutrients in surface water at the BATS location, particularly phosphorous. The N:P ratio was consistently far above the nominal Redfield ratio (mean, 38.5) but was significantly lower during the 1993∼1994 period (22.1). Over the same period the proportion of samples depleted in N only increased while the proportion of samples depleted in P only decreased. This indicates an overall reduction of N relative to P in the surface water at BATS during the 1993∼1994 period, the reasons for this anomaly, though, are not clear. The correlation analysis between the biotic and abiotic variables at BATS has indicated some interesting relationships that can help understand some of the parameters affecting nutrient stocks in the euphotic zone and their consequent impacts on marine biota. Although nutrient stocks in the oligotrophic environment are limited, they might be subject to interannual variation that may become anomalous in some cases. These variations might underlay significant feedback mechanisms by affecting marine productivity, the prime factor controlling the sequestration of atmospheric CO₂ by the oceans. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Interannual salinity variations in the Tsushima Strait and its relation to the Changjiang discharge   总被引：2，自引：0，他引：2  

Tomoharu Senjyu  Hirofumi Enomoto  Takeshi Matsuno  Sigeaki Matsui 《Journal of Oceanography》2006,62(5):681-692

Interannual salinity variations in the Tsushima Strait are investigated on the basis of historical hydrographic data. The EOF analysis revealed that the most dominant mode is the in-phase salinity variation between the eastern and western channels. The time coefficients of the EOF first mode in summer show a negative correlation with the Changjiang discharge, which indicates that salinity in the Tsushima Strait tends to decrease over summer, related to a large discharge of the Changjiang. The eigenvectors of the first mode are larger in the eastern channel than those in the western channel, though the low salinity water mainly flows through the western channel. This is because the low salinity water spreads into the eastern channel as well as the western channel over summers with a large discharge of the Changjiang. The out-of-phase salinity variation between the channels is extracted as the EOF second mode; this is the predominant variation in the western channel. The time coefficients of the second mode in summer show no significant correlations to the volume transports through the western channel and the transport differences between channels. A relationship between the EOF second mode and variations in the wind stress over the East China Sea is suggested.  相似文献   

Evolutionary tracks of the terrestrial planets     

Takafumi Matsui  Yutaka Abe 《Earth, Moon, and Planets》1987,39(3):207-214

On the basis of the model proposed by Matsui and Abe, we will show that two major factors — distance from the Sun and the efficiency of retention of accretional energy — control the early evolution of the terrestrial planets. A diagram of accretional energy versus the optical depth of a proto-atmosphere provides a means to follow the evolutionary track of surface temperature of the terrestrial planets and an explanation for why the third planet in our solar system is an aqua-planet.  相似文献