Complex response analysis of shells of revolution including uniform base translation and rocking     

Bor-Jen Lee  Phillip L. Gould 《地震工程与结构动力学》1984,12(4):507-519

A complex response algorithm for the dynamic analysis of axisymmetric thin shells supported on an interactive foundation is developed. The substructure deletion method is employed through the utilization of a dynamic boundary system at the contact area between the superstructure and the substructure. A new mathematical formulation in conjunction with the shell behaviour is developed to deal with rigid body motions due to the negation of the fixed base assumption. Four foundation conditions, that is, a fixed base, two pile foundation cases and a flexible base, are to examine the effect of base flexibility on the seismic response of cooling towers. Also, excellent comparative results between the frequency domain solution and a time domain solution are obtained.  相似文献   

Thermodynamic and Turbulence Characteristics of the Southern Great Plains Nocturnal Boundary Layer Under Differing Turbulent Regimes     

Timothy A. Bonin  William G. Blumberg  Petra M. Klein  Phillip B. Chilson 《Boundary-Layer Meteorology》2015,157(3):401-420

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Movement Patterns and Distributional Shifts of Dungeness Crab (Metacarcinus magister) and English Sole (Parophrys vetulus) During Seasonal Hypoxia     

Halley E. Froehlich  Timothy E. Essington  Anne H. Beaudreau  Phillip S. Levin 《Estuaries and Coasts》2014,37(2):449-460

Hypoxia (dissolved oxygen?<?2 mg L^–1) has emerged as a worldwide threat to coastal and estuarine ecosystems. Beyond direct mortality, secondary ecological impacts caused by hypoxia-driven distributional shifts may be equally important. From July–November 2009 and June–September 2010, we quantified the movement patterns of Dungeness crab (Metacarcinus magister) and English sole (Parophrys vetulus) in Hood Canal, Washington USA, a seasonally hypoxic estuary. Although highly mobile (mean cumulative distance?±?SD?=?11.0?±?25.6 km, N?=?60), there was little evidence of either species exhibiting large-scale directional movement out of the hypoxic region. However, Dungeness crab showed significant shifts towards shallower waters and elevation in activity in the hypoxic region, potentially increasing their vulnerability to crabbing and other indirect ecological consequences. Our findings suggest hypoxia could have a more localized impact on the mobile fauna in Hood Canal. However, more detailed information concerning the local-scale oxygen dynamics and responses of these species, such as English sole vertical movement, is essential for grasping the population and community level effects of hypoxia.  相似文献   

An organic geochemical investigation of the practice of manuring at a Minoan site on Pseira Island,Crete     

Ian D. Bull  Richard P. Evershed  Phillip P. Betancourt 《Geoarchaeology》2001,16(2):223-242

Lipid components in a soil profile developed in an agricultural terrace at a Minoan site on Pseira Island, Crete, were analyzed to determine whether the practice of manuring in antiquity, as inferred by distributional and temporal sherd scatter, could be confirmed through the use of biomarker compounds as proxies for manuring. Analysis of total organic carbon and the abundance of n‐alkyl lipids (n‐alkanols and fatty acids) demonstrated that while the upper part of the soil profile had received more recent inputs of vegetation‐derived organic matter, the deeper archaeological strata remained essentially undisturbed. Further analysis of 5β‐stanols, sterol components which may be utilized as fecal biomarkers, revealed a signal indicative of manuring, with human or porcine‐derived fecal material, in the lower 15 cm of the profile. Additional appraisal of epicoprostanol abundance inferred the possible practice of composting in later periods. This study represents a detection of manuring, in the oldest samples to date, using organic geochemical methods. © 2001 John Wiley & Sons, Inc.  相似文献