Predicting Soil-Water and Soil-Air Transport Properties and Their Effects on Soil-Vapor Extraction Efficiency   总被引：1，自引：0，他引：1  

Tjalfe G. Poulsen  Per Moldrup  Toshiko Yamaguchi  Per Schjønning  Jens Aage Hansen 《Ground Water Monitoring & Remediation》1999,19(3):61-70

Accurate prediction of water and air Iran sport parameters in variably saturated soil is necessary for modeling of soil-vapor extraction (SVE) at soil sites contaminated with volatile organic chemicals (VOCs). An expression for predicting saturated water permeability (k_l,s) in undisturbed soils from the soil total porosity and the field capacity soil-water content was developed by fitting a tortuous-tube fluid flow model to measured water permeability and gas diffusivity data. The new k_l,s expression gave accurate predictions when tested against independent k_l,s data. The k_l,s expression was implemented in the Campbell relative water permeability model to yield a predictive model for water permeability in variably saturated, undisturbed soil. The water permeability model, together with recently developed predictive equations for gas permeability and gas diffusivity, was used in a two-dimensional numerical SVE model that also included non-equilibrium mass transfer of VOC from a separate phase (nonaqueous phase liquid [NAPL]) to the air phase. SVE: calculations showed that gas permeability is likely the most important factor controlling VOC migration and vapor extraction efficiency. Water permeability and gas diffusivity effects became significant at water contents near and above field capacity. The NAPL-air mass transfer coefficient also had large impacts on simulated vapor extraction efficiency. The calculations suggest that realistic SVE models need to include predictive expressions for both conveciive, diffusive. and phase-partitioning processes in natural, undisturbed soils.  相似文献   

Bidirectional shaking table tests of a low-cost friction sliding system with flat-inclined surfaces     

Miguel B. Brito  Mitsuyoshi Akiyama  Yoshitaka Ichikawa  Hiroki Yamaguchi  Riki Honda  Naomitsu Ishigaki 《地震工程与结构动力学》2020,49(8):817-837

A novel low-cost friction sliding system for bidirectional excitation is developed to improve the seismic performance of reinforced concrete (RC) bridge piers. The sliding system is a spherical prototype developed by combining a central flat surface with an inclined spherical segment, characterized by stable oscillation and a large reduction in response accelerations on the flat surface. The inclined part provides a restoring force that limits the residual displacements of the system. Conventional steel and concrete are employed to construct a flat-inclined spherical surface atop an RC pier. The seismic forces are dissipated through the frictions generated during the sliding movements; hence, the seismic resilience of bridges can be ensured with a low-cost design solution. The proposed system is fabricated utilizing a mold created by a three-dimensional printer, which facilitates the use of conventional concrete to construct spherical shapes. The concrete surface is lubricated with a resin material to prevent abrasion from multiple input ground motions. To demonstrate the effectiveness of the system, bidirectional shaking table tests are conducted in the longitudinal and transverse directions of a scaled bridge model. The effect of the inclination angle and the flat surface size is investigated. The results demonstrate a large decrease in response acceleration when the system exhibits circular sliding displacement. Furthermore, the inclination angle that generates the smallest residual displacement is identified experimentally.  相似文献   

The Kellwasser events in the Upper Devonian Frasnian to Famennian transition in the Toc Tat Formation,northern Vietnam     

Toshifumi Komatsu  Ryota Urakawa  Toshitaka Inada  Kazuki Yamauchi  Takumi Maekawa  Reishi Takashima  Mark Williams  Phong D. Nguyen  Hung D. Doan  Minh T. Nguyen  Shuji Niko  Gengo Tanaka  Tatsuhiko Yamaguchi 《Island Arc》2019,28(1)

Upper Devonian carbonates of the Toc Tat Formation in the Si Phai Pass area of Dong Van District, northern Vietnam were deposited in carbonate platform, slope, and basin environments. These carbonates yield abundant conodonts indicative of the Palmatolepis nasuta, Pa. linguiformis and Pa. triangularis zones, the Frasnian–Famennian stage boundary being identified by the first occurrence of Pa. triangularis. Two positive carbon isotope excursions are recognized, the lower excursion peaking in the interval of the lower to middle Pa. nasuta Zone, whilst the upper excursion peaks just above the local Frasnian–Famennian boundary. Based on the biostratigraphy, these excursions equate to the Lower and Upper Kellwasser events. Locally, tentaculitoid taxa (Nowakia, Styliolina, Homoctenus, and Metastyliolina?) are abundant in the interval of the Pa. nasuta Zone, but show a drastic decline in abundance before the Lower Kellwasser Event, and only two taxa survived into the Famennian.  相似文献   

The Ganges and Brahmaputra rivers in Bangladesh: basin denudation and sedimentation     

Mohammad Rezwanul Islam  Syeda Fahliza Begum  Yasushi Yamaguchi  Katsuro Ogawa 《水文研究》1999,13(17):2907-2923

Every year the Ganges and Brahmaputra rivers in Bangladesh transport 316 and 721 million tonnes of sediment, respectively. These high loads of suspended sediment reflect the very high rate of denudation in their drainage basins. The average mechanical denudation rate for the Ganges and Brahmaputra basins together is 365 mm 10³ yr⁻¹. However, the rate is higher in the Brahmaputra Basin than that in the Ganges Basin. Several factors, including mean trunk channel gradient, relief ratio, runoff, basin lithology and recurring earthquakes are responsible for these high denudation rates. Of the total suspended sediment load (i.e. 1037 million tonnes) transported by these rivers, only 525 million tonnes (c. 51% of the total load) are delivered to the coastal area of Bangladesh and the remaining 512 million tonnes are deposited within the lower basin, offsetting the subsidence. Of the deposited load, about 289 million tonnes (about 28% of the total load) are deposited on the floodplains of these rivers. The remaining 223 million tonnes (about 21% of the total load) are deposited within the river channels, resulting in aggradation of the channel bed at an average rate of about 3·9 cm yr⁻¹. Although the Brahmaputra transports a higher sediment load than the Ganges, the channel bed aggradation rate is much higher for the Ganges. This study also documents a wide range of interannual, seasonal and daily variation in suspended sediment transport and water discharge. Interannual variation in sediment deposition within the basin is also suggested. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

A new tree-ring date for the “floating island” lava flow,Mount St. Helens,Washington     

David K Yamaguchi  Richard P Hoblitt  Donald B Lawrence 《Bulletin of Volcanology》1990,52(7):545-550

Anomalously narrow and missing rings in trees 12 m from Mount St. Helens' floating island lava flow, and synchronous growth increases in trees farther from the flow margin, are evidence that this andesitic flow was extruded between late summer 1799 and spring 1800 a.d., within a few months after the eruption of Mount St. Helens' dacitic layer T tephra. For ease of reference, we assign here an 1800 a.d. date to this flow. The new date shows that the start of Mount St. Helens' Goat Rocks eruptive period (1800–1857 a.d.) resembled the recent (1980–1986) activity in both petrochemical trends and timing. In both cases, an initial explosive eruption of dacite was quickly succeeded by the eruption of more mafic lavas; dacite lavas then reappeared during an extended concluding phase of activity. This behavior is consistent with a recently proposed fluid-dynamic model of magma withdrawal from a compositionally zoned magma chamber.  相似文献   

Extracellular release of photosynthetic products by a pelagic blue-green alga,Trichodesmium thiebautii     

Sooji Shimura  Yukuya Yamaguchi  Yusho Aruga  Yoshihiko Fujita  Shun-ei Ichimura 《Journal of Oceanography》1978,34(5):181-188

Extracellular release of photosynthetic products by a pelagic blue-green alga,Trichodesmium thiebautii, was scrutinized in relation to pre-treatments in¹⁴C-method for measuring the primary productivity.The extracellular release increased markedly by the pre-treatments with such strong fixative solutions as formaldehyde and mercuric chloride. In such a case, the amount of extracellular fraction reached even almost 78 % of the total photosynthates. The extracellular release of photosynthates was dependent both on light intensity and on physiological state of algal cells. When photosynthesis was terminated by a fixative, the extracellular release was noticed even just after the fixation, and it increased with time. Thus, it appears to be difficult to deduce the real photosynthetic production capacity from the amount of cellular fraction only.The amount of extracellular fraction for unfixed samples filtered immediately after the incubation was less than 8 % of the total photosynthetic products inT. thiebautii. This value is nearly comparable to the amount of excretion reported in many cultured algae.  相似文献   

A Continuous Mapping of Tidal Current Structures in the Kanmon Strait   总被引：1，自引：0，他引：1  

Keisuke?Yamaguchi  Ju?Lin  Arata?KanekoEmail author  Tokuo?Yayamoto  Noriaki?Gohda  Hong-Quang?Nguyen  Hong?Zheng 《Journal of Oceanography》2005,61(2):283-294

Tidal current structures at the Hayatomono-Seto of the Kanmon Strait are mapped continuously during March 17 to 20, 2003, including a spring tide, by the eight coastal acoustic tomography (CAT) systems distributed on both the sides of the strait. Detailed structures of strong tidal currents and their associated vortices are well reconstructed by the inverse analysis of travel-time difference data obtained from the reciprocal sound transmission between the paired CAT systems located at both sides of the strait mainly. The results are well compared to the shipboard acoustic Doppler current profiler (ADCP) data at the correlation rate of 0.84/0.82 and the RMS difference of 0.47/0.48 ms⁻¹ for the east-west/north-south current after the selection of good data. During the observation period, the maximum hourly mean volume transport for the upper 7 m layer across the strait reached 13,314 m³ s⁻¹ for the eastward and 5,547 m³ s⁻¹ for the westward. The daily mean transport is directed to the eastward and estimated 1,470 m³ s⁻¹ and 2,140 m³ s⁻¹ for March 18 and 19, respectively, when a spring tide occurs.  相似文献   

Induction of female‐to‐male sex change in a large protogynous fish,Choerodon schoenleinii          下载免费PDF全文

Taku Sato  Masato Kobayashi  Takayuki Takebe  Narisato Hirai  Koichi Okuzawa  Sayumi Sawaguchi  Takahiro Matsubara  Tomofumi Yamaguchi  Rihito Shinoda  Masahiko Koiso  Kazuhisa Teruya 《Marine Ecology》2018,39(1)

Most behavioral studies on hermaphroditic fishes have focused on small‐sized species, which are tractable for research. Although many species of large hermaphroditic fishes are important fishery resources, their proximate mechanisms (visual, chemical and/or behavioral cues) in the social regulation of sex change have not been determined. Determination of these would inform resource management and aquaculture. In order to get closer to understanding the proximate mechanisms underlying the social regulation of female‐to‐male sex change in large hermaphroditic fishes, this study reports situations that induced female‐to‐male sex change in black‐spot tuskfish, Choerodon schoenleinii, a species of large protogynous fish, in massive laboratory tanks. The situations differed in the possibility of male‐to‐female tactile contact and in the group sex ratio, enabling us to infer plausible proximate mechanisms underlying sex change induction. Tactile contact between individuals is suspected to be closely related to the incidence of female‐to‐male sex change in C. schoenleinii. Visual and chemical cues alone may be insufficient to inhibit such sex changes. Male‐to‐female tactile contact may have an important influence on female‐to‐male sex change, i.e., inhibition of this sex change, in this species. The effect of sex ratio of a social group on the incidence of sex change may be due to the relative frequency and intensity of male tactile contact with each female, which may vary with the number of females. In the absence of a dominant male, tactile contact among females may affect the incidence of sex change, as well as determine which individuals change sex.  相似文献   

The Meteoritical Bulletin,No. 96, September 2009     

Michael K. Weisberg  Caroline Smith  Gretchen Benedix  Christopher D. K. Herd  Kevin Righter  Henning Haack  Akira Yamaguchi  Hasnaa Chennaoui Aoudjehane  Jeffrey N. Grossman 《Meteoritics & planetary science》2009,44(9):1355-1397

Abstract— The Meteoritical Bulletin No. 96 contains a total of 1590 newly approved meteorite names with their relevant data. These include 12 from specific locations within Africa, 76 from northwest Africa, 9 from the Americas, 13 from Asia, 1 from Australia, 2 from Europe, 950 from Antarctica recovered by the Chinese Antarctic Research Expedition (CHINARE), and 527 from the American Antarctic program (ANSMET). Among these meteorites are 4 falls, Almahata Sitta (Sudan), Sulagiri (India), Ash Creek (United States), and Maribo (Denmark). Almahata Sitta is an anomalous ureilite and is debris from asteroid 2008 TC3 and Maribo is a CM2 chondrite. Other highlights include a lunar meteorite, a CM1 chondrite, and an anomalous IVA iron.  相似文献   

Space-continuous measurements on ocean current and chemicalproperties with the intelligent towed vehicle “Flying Fish”     

Koterayama  W. Yamaguchi  S. Yokobiki  T. Jong-Hwan Yoon Hase  H. 《Oceanic Engineering, IEEE Journal of》2000,25(1):130-138

A research project to develop observation systems for heat, momentum, and material circulation in the ocean and atmosphere was carried out from 1992 to 1997. A pitch, roll, and depth controllable towed vehicle called “Flying Fish” was developed which houses an acoustic Doppler current profiler, CO₂ analyzer, and sensors for measuring temperature, salinity, dissolved oxygen, pH, turbidity, and chlorophyll. The length of the vehicle is 3.84 m, the breadth is 2.26 m, the height is 1.4 m, the weight in air is 1400 kg, and the weight in water is roughly 0 kg. Flying Fish enables us to obtain space-continuous data of physical and chemical properties efficiently in the upper mixed layer of the ocean, From 1994 to 1997, the vehicle was used for observations in the northern, southern, and central parts of the Japan Sea in a collaborative study by Japan, Korea, and Russia. Examples of data obtained are shown in this paper and the results of current velocities are compared with those taken by other observation systems  相似文献