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81.
China Ocean Engineering - Conventional design of pier structures is based on the assumption of fully rigid joints. In practice, the real connections are semi-rigid that cause changes in dynamic... 相似文献
82.
83.
Airborne radiometric survey and field studies outlined a large, elongate, high‐level plutonic suite within the Richardson pluton south of the Contact Lake Belt in the Great Bear Magmatic Zone, Northwest Territories, Canada. In terms of content of radioactive elements, the Richardson pluton is composed of two distinct granite types, low heat production (LHP) and high heat production (HHP). Uranium content in the LHP and HHP granites ranges from 3.0 to 4.9 ppm and 6.5 to 24.6 ppm, respectively, showing similarity of the LHP granite to average granites. Geochemical studies indicate that there is a genetic relationship between these two types of granite; the LHP granite was the early product of magma crystallization, whereas the HHP granite is the result of extensive crystal fractionation of biotite, plagioclase and apatite. The presence of magmatic fluorite in granite suggests that high fluorine content lowered the liquidus temperature of magma causing lower temperature fractionation during ascent to high crustal levels, which increased U and Th concentrations in the resultant HHP granite. Weak U mineralization occurs locally as discontinuous quartz ± hematite ± pitchblende veins and veinlets within the HHP granite. Stronger U mineralization (U ± Ag ± Ni ± Co ± Cu) occurred in the past‐producing Contact Lake and Port Radium deposits. It appears that such mineralization may have had a spatial and temporal genetic‐paragenetic relationship with the HHP granite. 相似文献
84.
Multi-sensor approach to settlement analysis of earth dams 总被引:1,自引:0,他引:1
In this paper, a fusion method for the settlement study of the earth dams based on geodetic and geotechnical data is developed.
The developed method can be algorithmically explained as follows: (a) interpolation of the geotechnical data to the epoch
of geodetic observations by four degree polynomial fitting, which serves as a low-pass filter. (b) Conversion of the initial
observations into time series of the dam heights at the geodetic and geotechnical stations. (c) Fusion of the data from the
two sources at different fusion levels. (d) Final decision based on the deformation parameters derived from fused data. The
significant innovation of the proposed method centered upon its ability to incorporate geodetic and geotechnical observation
types into a one integrated solution through fusion. The method is numerically tested for the Karkhe earth dam by using geodetic
and geotechnical data from 1997 till 2009. The numerical evaluation at 229 check points indicates more than 70% improvement
in the settlementmodeling based on the fusion of the geodetic and geotechnical data, as compared to the settlement modeling
based on geotechnical data alone. 相似文献
85.
Alireza Hassanzadegan Guido Blöcher Harald Milsch Luca Urpi Günter Zimmermann 《Rock Mechanics and Rock Engineering》2014,47(2):421-434
A porosity change influences the transport properties and the elastic moduli of rock while circulating water in a geothermal reservoir. The static and dynamic elastic moduli can be derived from the slope of stress–strain curves and velocity measurements, respectively. Consequently, the acoustic velocities were measured while performing hydrostatic drained tests. The effect of temperature on static and dynamic elastic moduli and porosity variations of Flechtinger sandstone was investigated in a wide range of confining pressure from 2 to 55 MPa. The experiments were carried out in a conventional triaxial system whereas the pore pressure remained constant, confining pressure was cycled, and temperature was increased step wise (25, 60, 90, 120, and 140 °C). The porosity variation was calculated by employing two different theories: poroelasticity and crack closure. The porosity variation and crack porosity were determined by the first derivative of stress–strain curves and the integral of the second derivative of stress–strain curves, respectively. The crack porosity analysis confirms the creation of new cracks at high temperatures. The porosity variation was increasing with an increase in temperature at low effective pressures and was decreasing with a rise in temperature at high effective pressures. Both compressional and shear wave velocities were increasing with increasing pressure due to progressive crack closure. Furthermore, the thermomechanical behavior of Flechtinger sandstone was characterized by an inversion effect where the sign of the temperature derivative of the drained bulk modulus changes. 相似文献
86.
Alireza Owji Isa Esfandiarpour Boroujeni Ardavan Kamali Seyed Javad Hosseinifard Mohsen Bagheri Bodaghabadi 《Arabian Journal of Geosciences》2014,7(4):1491-1499
Soil texture is an important physical soil property that may contribute to variations in many soil functions as well as nutrient storage and availability, water retention, and soil erosion. Although several methods for determining the texture classes of soil particles have been proposed, differences among hydrometer reading times have presented challenges in determining the precise soil texture classes. Therefore, this study was conducted to evaluate the effects of hydrometer reading time on the spatial variability of soil textures in the Rafsanjan area, southeast Iran. To accomplish this, 77 soil samples were collected on a 500-m square sampling grid from depths of 0–40, 40–80, and 80–120 cm, and their particle sizes were determined through analysis for 40 s, 2 h, 6.5 h, and 8 h using the Bouyoucos hydrometer method. The results showed a strong spatial correlation in the soil particles among sampling soil layers and across the study area. Moreover, the differences among hydrometer reading times did not have a significant impact on determination of coarse soil texture classes, although they did influence determination of the finer classes. Although the 8 h reading time provided the most accurate response with respect to mechanical analysis of a soil, after 6.5 h the hydrometer could also largely (more than 80.0 %, on average) achieve this goal. Additionally, the 2 h hydrometer reading time could also be useful for the initial assessment or general overview of the soil texture in a certain region; however, it is not recommended for precision agriculture or site-specific management. 相似文献
87.
Abradat Mafi Ebrahim Ghasemi-Nejad Alireza Ashouri Mohammad Vahidi-Nia 《Arabian Journal of Geosciences》2014,7(9):3683-3692
The Binalud Mountains of NE Iran represent the easternmost extension of the Alborz Range. After the Mid-Cimmerian orogenic event and rapid subsidence, the deep marine sediments of the Dalichai Formation were deposited. A well-preserved section of the formation was sampled for palynological purposes. The study revealed diverse and nearly well-preserved dinoflagellate cyst assemblages. Thirty-six dinoflagellate cyst species identified lead to identification of four biozones: Cribroperidinium crispum (Late Bajocian), Dichadogonyaulax sellwoodii (Bathonian to Early Callovian), Ctenidodinium continuum (Early to Late Callovian), and Ctenidodinium tenellum (Early Oxfordian) biozones. The close similarities of dinoflagellate cyst assemblages between Binalud Mountains, NE Iran, with those of Alborz Mountains (Northern Iran) during Middle Jurassic confirm the connection between two sedimentary basins during this time in Iran. Meanwhile, this biozonation corresponds largely to that established in Northwest Europe and reveals the marine connection between NE and North of Iran with Northwest Europe and the Northwestern Tethys during the Late Bajocian to Early Oxfordian. 相似文献
88.
The decisions made by agricultural households to adjust to climate change(CC)in Iran are not well known.This study is intended to investigate the influence of perceptions and socioeconomic,institutional features on farmers’adaptation decisions about CC,which constitute the hypothetical statements of the study.We undertook a survey of 200 farm householders from 31 villages of Ilam Province,situated in the western Iran,as randomly selected.The result discloses that the proposed discriminant model matches the dataset well,with a strong effect size of partial eta-squared(η2=0.38).The analysis further signals that adapters are younger and more welleducated than non-adapters.Adapters are also knowledgeable about CC risks and institutional policy barriers.The adapters have subsidiary work,better access to credit,and have good contacts with expansion agents and specialists.The paper concludes that government authorities should provide farmers with the enriched capabilities and competencies enabling them to adapt to CC. 相似文献
89.
Ocean Science Journal - Metal concentrations were measured in predominant coastal fauna of the Caspian Sea including six macro-invertebrates (Mnemiposis leidyi, Balanus improvisus, Pontogammarus... 相似文献
90.
This paper studies one of the most important problems of dry countries that are confronted with water deficit and the competition of rivals to allocate water. Some common methods have been investigated for computing the minimum water requirement to save a river's biological activity. After a discussion of the currently used method in Iran (the Tenant Method), the application of some other methods, which are known as Hydraulic and Hydrological Methods, is illustrated. The case study is a river in the northern part of Iran and this research addresses the critical situation of this river in near future regarding the planned anthropogenic alteration and its consequences. It has been shown that the application of environmental water allocation methods that have no background in a region could be misleading. The first proposed method is the Texas Method, in which flexibility in water allocation helps to develop an integrated river management paradigm in the study area. The second preferred method is a Hydraulic Method, by which the implementation of morphological parameters or flow geometrical properties could sustain physical habitat within an acceptable range in terms of depth, width, velocity, and bed shear stress. In the case study, the Maximum Curvature Method was superior to the Slope Method. The investigation revealed that using a widely recommended slope of 1 for the discharge‐wetted perimeter function can lead to an overestimated and unacceptable discharge. The Tenant Method in respect to minimum environmental flow requirement yielded the weakest result, and it has been illustrated that its application might impose irrecoverable shock to the ecosystem. The Flow Duration Curve Method (the Q95 Method), in spite of its subjectivity, showed more compatibility with the river's condition in comparison with the Tenant Method. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献