Effect of irregular structural configuration on floor acceleration demand in hill‐side buildings     

Mitesh Surana  Yogendra Singh  Dominik H. Lang 《地震工程与结构动力学》2018,47(10):2032-2054

A suite of reinforced‐concrete frame buildings located on hill sides, with 2 different structural configurations, viz step‐back and split‐foundation, are analyzed to study their floor response. Both step‐back and split‐foundation structural configurations lead to torsional effects in the direction across the slope due to the presence of shorter columns on the uphill side. Peak floor acceleration and floor response spectra are obtained at each storey's center of rigidity and at both its stiff and flexible edges. As reported in previous studies as well, it is observed that the floor response spectra are better correlated with the ground response spectrum. Therefore, the floor spectral amplification functions are obtained as the ratio of spectral ordinates at different floor levels to the one at the ground level. Peaks are observed in the spectral amplification functions corresponding to the first 2 modes in the upper portion of the hill‐side buildings, whereas a single peak corresponding to a specific kth mode of vibration is observed on the floors below the uppermost foundation level. Based on the numerical study for the step‐back and split‐foundation hill‐side buildings, simple floor spectral amplification functions are proposed and validated. The proposed spectral amplification functions take into account both the buildings' plan and elevation irregularities and can be used for seismic design of acceleration‐sensitive nonstructural components, given that the supporting structure's dynamic characteristics, torsional rotation, ground‐motion response spectrum, and location of the nonstructural components within the supporting structure are known, because current code models are actually not applicable to hill‐side buildings.  相似文献   

Continuous real‐time analysis of the isotopic composition of precipitation during tropical rain events: Insights into tropical convection          下载免费PDF全文

Shaoneng He  Nathalie F. Goodkin  Dominik Jackisch  Maria Rosabelle Ong  Dhrubajyoti Samanta 《水文研究》2018,32(11):1531-1545

To investigate stable isotopic variability of precipitation in Singapore, we continuously analysed the δ‐value of individual rain events from November 2014 to August 2017 using an online system composed of a diffusion sampler coupled to Cavity Ring‐Down Spectrometer. Over this period, the average value (δ¹⁸O_Avg), the lowest value (δ¹⁸O_Low), and the initial value (δ¹⁸O_Init) varied significantly, ranging from ?0.45 to ?15.54‰, ?0.9 to ?17.65‰, and 0 to ?13.13‰, respectively. All 3 values share similar variability, and events with low δ¹⁸O_Low and δ¹⁸O_Avg values have low δ¹⁸O_Init value. Individual events have limited intraevent variability in δ‐value (Δδ) with the majority having a Δδ below 4‰. Correlation of δ¹⁸O_Low and δ¹⁸O_Avg with δ¹⁸O_Init is much higher than that with Δδ, suggesting that convective activities prior to events have more control over δ‐value than on‐site convective activities. The d‐excess of events also varies considerably in response to the seasonal variation in moisture sources. A 2‐month running mean analysis of δ¹⁸O reveals clear seasonal and interannual variability. Seasonal variability is associated with the meridional movement of the Intertropical Convergence Zone and evolution of the Asian monsoon. El Niño–Southern Oscillation is a likely driver of interannual variability. During 2015–2016, the strongest El Niño year in recorded history, the majority of events have a δ¹⁸O value higher than the weighted average δ¹⁸O of daily precipitation. δ¹⁸O shows a positive correlation with outgoing longwave radiation in the western Pacific and the Asian monsoon region, and also with Oceanic Niño Index. During El Niño, the convection centre shifts eastward to the central/eastern Pacific, weakening convective activities in Southeast Asia. Our study shows that precipitation δ‐value contains information about El Niño–Southern Oscillation and the Intertropical Convergence Zone, which has a significant implication for the interpretation of water isotope data and understanding of hydrological processes in tropical regions.  相似文献   

Surface Geophysical Methods used to Verify the Karst Geological Structure in the Built-up Area: A Case Study of Specific Engineering-Geological Conditions     

Rene PUTISKA  Marian MARSCHALKO  Isik YILMAZ  Dominik NIEMIEC  CHENG Xianfeng  Ivan DOSTAL  Jan KUBAC 《《地质学报》英文版》2021,95(5):1763-1770

This article presents a research study of complex limestone karst engineering-geological conditions in the municipality Valaská near Banská Bystrica in Slovakia. The aim of the study is to demonstrate the impossibility of spatial identification of cave spaces using surface geophysical methods due to the specific engineering-geological conditions of a thick surface layer of anthropogenic fill containing highly heterogeneous anthropogenic material. Its maximum thickness is 3 m. Another specificific condition of the study area is its location in the built-up area, due to which the applicability of geophysical methods was limited. The article contains methodological recommendations to be used in analogous geological conditions with karst structures topped with anthropogenic fill, which complicates the identification of cave spaces. The recommended solution herein is the identification of the cave system using underground mapping of the karst and its projection onto the surface for which surface geophysical methods have been combined.  相似文献   

A reconstruction of the palaeohydrological conditions of a flood‐plain: a multi‐proxy study from the Grabia River valley mire,central Poland          下载免费PDF全文

Dominik Pawłowski  Grzegorz Kowalewski  Krystyna Milecka  Mateusz Płóciennik  Michał Woszczyk  Tomasz Zieliński  Daniel Okupny  Wojciech Włodarski  Jacek Forysiak 《Boreas: An International Journal of Quaternary Research》2015,44(3):543-562

This study investigated the Grabia River valley mire in central Poland to reconstruct its palaeoenvironmental conditions from the Younger Dryas to the present. We analysed sedimentological, biological and geochemical data from the palaeo‐oxbow lake and valley mire to identify the principal hydrological trends, especially episodes of high water level. During the Lateglacial and Holocene, the Grabia River had a meandering channel, and its hydraulic parameters and the channel dimensions changed in response to climatic oscillations and vegetation development. We identified phases of high flood intensity and high groundwater level that correlate with regional and supraregional climatic events. The frequency and timing of palaeohydroclimatic oscillations show strong similarities to records from other sites in Poland and the rest of Europe. We show that various analytical methods, namely, pollen, plant macrofossils, Cladocera, Chironomidae, sedimentological, geochemical and radiocarbon data, can be effective tools for reconstructing past hydroclimatic changes in palaeo‐oxbow lakes and investigating the effects of past climate changes on river environments. The high sensitivity of the biota, especially Cladocera, to changes in water level permits the reconstruction of palaeoecological changes, especially flood episodes that occurred in the river valley. In particular, the increase in the proportion of sediment‐associated Cladocera and pelagic taxa was closely correlated with floods. Through comparisons with the palaeobiological data, geochemical data allowed the identification of humid phases within the fen associated with a rising groundwater table, direct fluvial activity (floods) and alluvial deposition. We also discuss the limitations of palaeohydrological reconstructions based on these proxies, especially on fossil aquatic invertebrates.  相似文献   

Fe and O isotope composition of meteorite fusion crusts: Possible natural analogues to chondrule formation?          下载免费PDF全文

Dominik C. Hezel  Graeme M. Poole  Jack Hoyes  Barry J. Coles  Catherine Unsworth  Nina Albrecht  Caroline Smith  Mark Rehkämper  Andreas Pack  Matthew Genge  Sara S. Russell 《Meteoritics & planetary science》2015,50(2):229-242

Meteorite fusion crust formation is a brief event in a high‐temperature (2000–12,000 K) and high‐pressure (2–5 MPa) regime. We studied fusion crusts and bulk samples of 10 ordinary chondrite falls and 10 ordinary chondrite finds. The fusion crusts show a typical layering and most contain vesicles. All fusion crusts are enriched in heavy Fe isotopes, with δ⁵⁶Fe values up to +0.35‰ relative to the solar system mean. On average, the δ⁵⁶Fe of fusion crusts from finds is +0.23‰, which is 0.08‰ higher than the average from falls (+0.15‰). Higher δ⁵⁶Fe in fusion crusts of finds correlate with bulk chondrite enrichments in mobile elements such as Ba and Sr. The δ⁵⁶Fe signature of meteorite fusion crusts was produced by two processes (1) evaporation during atmospheric entry and (2) terrestrial weathering. Fusion crusts have either the same or higher δ¹⁸O (0.9–1.5‰) than their host chondrites, and the same is true for Δ¹⁷O. The differences in bulk chondrite and fusion crust oxygen isotope composition are explained by exchange of oxygen between the molten surface of the meteorites with the atmosphere and weathering. Meteorite fusion crust formation is qualitatively similar to conditions of chondrule formation. Therefore, fusion crusts may, at least to some extent, serve as a natural analogue to chondrule formation processes. Meteorite fusion crust and chondrules exhibit a similar extent of Fe isotope fractionation, supporting the idea that the Fe isotope signature of chondrules was established in a high‐pressure environment that prevented large isotope fractionations. The exchange of O between a chondrule melt and an ¹⁶O‐poor nebula as the cause for the observed nonmass dependent O isotope compositions in chondrules is supported by the same process, although to a much lower extent, in meteorite fusion crusts.  相似文献   

Low‐cost monitoring of snow height and thermal properties with inexpensive temperature sensors     

Dominik E. Reusser  Erwin Zehe 《水文研究》2011,25(12):1841-1852

Small, self‐recording temperature sensors were installed at several heights along a metal rod at five locations in a case study catchment. For each sensor, the presence or absence of snow cover was determined on the basis of its insulating effect and the resulting reduction of the diurnal temperature oscillations. Sensor coverage was then converted into a time series of snow height for each location. Additionally, cold content was calculated. Snow height and cold content provide valuable information for spring flood prediction. Good agreement of estimated snow heights with reference measurements was achieved and increased discharge in the study catchment coincided with low cold content of the snow cover. The results of the proposed distributed assessment of snow cover and snow state show great potential for (i) flood warning, (ii) assimilation of snow state data and (iii) modelling snowmelt process. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Seagrass as the main food source of Neaxius acanthus (Thalassinidea: Strahlaxiidae), its burrow associates, and of Corallianassa coutierei (Thalassinidea: Callianassidae)     

Dominik Kneer  Harald Asmus  Jan Arie Vonk 《Estuarine, Coastal and Shelf Science》2008,79(4):620-630

Burrows of the thalassinidean shrimps Neaxius acanthus and Corallianassa coutierei are striking aspects in tropical seagrass beds of the Spermonde Archipelago, Indonesia. Burrow construction, behaviour, burrow type and associated commensal community were investigated to clarify the ecological role and food requirements of these shrimps and their commensals. Gut content analysis and stable-isotope data were used to unravel the food sources and the trophic interactions among the commensal community.Individuals of Neaxius acanthus were caught on Bone Batang Island. In narrow aquaria filled with sediment they constructed burrows resembling those found in the field. During burrow construction and maintenance only little sediment was brought to the surface, most was sorted and compacted to create a distinct lining. Maintenance work by single shrimps typically took about 5 min, after which the shrimp walked up to the entrance and rested for a similar period of time. There were no differences in behaviour between day and night. Intrasexual encounters inside the burrow were characterised by a high level of aggression and all resulted in one participant being driven out of the burrow. Intersexual encounters led to coexistence with both animals taking turns in burrow maintenance and guarding the entrance. Offered seagrass leaves were pulled underground, cut into pieces and eventually integrated into the lining. Burrows of Corallianassa coutierei resembled a deep U-shape. Chambers branching off halfway down and at the deepest point contained seagrass fragments. All steep parts of the burrow were lined similar to burrows of N. acanthus.No commensals were found associated with Corallianassa coutierei. However, burrows of Neaxius acanthus in the field typically contained a pair of shrimps, up to 8 individuals of the commensal bivalve Barrimysia cumingii and large numbers of gammarid amphipods. Other animals found associated with the burrow were the goby Austrolethops wardi, a palaemonid shrimp species and two species of tube-building polychaetes, one of which was also found as an epibiont on N. acanthus.Stable-isotope and gut content analyses indicate that the diet of Neaxius acanthus, its commensal Austrolethops wardi, and Corallianassa coutierei is mainly derived from detrital seagrass leaves, with a potential contribution of sediment organic matter and seagrass epiphytes. In contrast the isotopic signature of Barrimysia cumingii suggests the presence of symbiotic sulphide metabolism bacteria. This study underlines that, besides their interactions with the surrounding ecosystem, thalassinid shrimp burrows play an important role as a sub-habitat with a unique associated fauna.  相似文献   

Search for GRB related prompt optical emission and other fast varying objects with “Pi of the Sky” detector     

M. Ćwiok  W. Dominik  K. Małek  L. Mankiewicz  J. Mrowca-Ciułacz  K. Nawrocki  L. W. Piotrowski  P. Sitek  M. Sokołowski  G. Wrochna  A. F. Żarnecki 《Astrophysics and Space Science》2007,309(1-4):531-535

Experiment “Pi of the Sky” is designed to search for prompt optical emission from GRB sources. 32 CCD cameras covering 2 steradians will monitor the sky continuously. The data will be analysed on-line in search for optical flashes. The prototype with 2 cameras operated at Las Campanas (Chile) since 2004 has recognised several outbursts of flaring stars and has given limits for a few GRB.  相似文献   

The Glarus Double Fold: a serious scientific advance in mid nineteenth century Alpine Geology     

Dominik Letsch 《Swiss Journal of Geoscience》2014,107(1):65-80

The Glarus overthrust is one of the best known examples of a thrust fault. Prior to its explanation as the base of an overthrust mass, this anomaly of the stratigraphic column had been explained by the Double Fold model, two recumbent folds facing each other. This model, advocated by Arnold Escher and Albert Heim, has been discredited by later geologists as a tectonically unsound concept which retarded the progress of science in this field of research. This article challenges parts of this view and tries instead to demonstrate that the Double Fold concept, though obviously wrong in retrospect, was a considerable scientific advance compared to the situation around 1850 when it was first proposed. To this end, the article summarizes the development of Swiss Alpine geology between 1800 and 1850 and places the Double Fold into its proper historical context. Earlier tectonic models (mostly proposed by Bernhard Studer) viewed crystalline rocks as the main driver of Alpine orogeny: due to somewhat mysterious metamorphic processes these rocks were supposed to have changed their lithology and physical properties and ascended vertically through small fissures. They uplifted, folded and eventually overflowed their sedimentary cover. The Glarus overthrust was also explained in this manner, probably even by Arnold Escher until the late 1840s. He later changed his mind and proposed the Double Fold concept which can be considered as one of the earliest attempts to apply the global contraction theory to the Alps. The global contraction theory later became the base of the geotectonic model of Eduard Suess and contributed to the final acceptance of large-scale horizontal displacements of rock masses around 1900. From this perspective, the Double Fold can be considered as a first step towards the nappe tectonic revolution and we suggest that its proposal was the expression of a fundamentally new way of thinking in Alpine tectonics.  相似文献   

Reionization and the Cosmic Dawn with the Square Kilometre Array     

Garrelt Mellema  Léon V. E. Koopmans  Filipe A. Abdalla  Gianni Bernardi  Benedetta Ciardi  Soobash Daiboo  A. G. de Bruyn  Kanan K. Datta  Heino Falcke  Andrea Ferrara  Ilian T. Iliev  Fabio Iocco  Vibor Jelić  Hannes Jensen  Ronniy Joseph  Panos Labroupoulos  Avery Meiksin  Andrei Mesinger  André R. Offringa  V. N. Pandey  Jonathan R. Pritchard  Mario G. Santos  Dominik J. Schwarz  Benoit Semelin  Harish Vedantham  Sarod Yatawatta  Saleem Zaroubi 《Experimental Astronomy》2013,36(1-2):235-318

The Square Kilometre Array (SKA) will have a low frequency component (SKA-low) which has as one of its main science goals the study of the redshifted 21 cm line from the earliest phases of star and galaxy formation in the Universe. This 21 cm signal provides a new and unique window both on the time of the formation of the first stars and accreting black holes and the subsequent period of substantial ionization of the intergalactic medium. The signal will teach us fundamental new things about the earliest phases of structure formation, cosmology and even has the potential to lead to the discovery of new physical phenomena. Here we present a white paper with an overview of the science questions that SKA-low can address, how we plan to tackle these questions and what this implies for the basic design of the telescope.  相似文献