Acceleration response modification factors for nonstructural components attached to inelastic moment‐resisting frame structures

A statistical analysis of the peak acceleration demands for nonstructural components (NSCs) supported on a variety of stiff and flexible inelastic regular moment‐resisting frame structures with periods from 0.3 to 3.0 s exposed to 40 far‐field ground motions is presented. Peak component acceleration (PCA) demands were quantified based on the floor response spectrum (FRS) method without considering dynamic interaction effects. This study evaluated the main factors that influence the amplification or decrease of FRS values caused by inelasticity in the primary structure in three distinct spectral regions namely long‐period, fundamental‐period, and short‐period region. The amplification or decrease of peak elastic acceleration demands depends on the location of the NSC in the supporting structure, periods of the component and building, damping ratio of the component, and level of inelasticity of the supporting structure. While FRS values at the initial modal periods of the supporting structure are reduced due to inelastic action in the primary structure, the region between the modal periods experiences an increase in PCA demands. A parameter denoted as acceleration response modification factor (R_acc) was proposed to quantify this reduction/increase in PCA demands. Copyright © 2007 John Wiley & Sons, Ltd.     

Solar limb darkening in the wings of the CaII H and K lines

The method for measuring solar limb darkening has been proposed, and the formulas, describing the law of solar limb darkening in the wings of the CaII H (396.849 nm) and K (393.369 nm) lines, have been derived. To operate at arbitrary points on the Sun’s surface, it is necessary to know the law of solar limb darkening, which is specific in different spectral regions. The procedure of spectrum correction for a flat field, proposed in our previous works, is based on comparing line-free spectral regions with the solar center reference spectrum from the atlas by Brault and Neckel [1994].     

Linking Tarim Basin sea retreat (west China) and Asian aridification in the late Eocene

The Tarim Basin in western China formed the easternmost margin of a shallow epicontinental sea that extended across Eurasia and was well connected to the western Tethys during the Paleogene. Climate modelling studies suggest that the westward retreat of this sea from Central Asia may have been as important as the Tibetan Plateau uplift in forcing aridification and monsoon intensification in the Asian continental interior due to the redistribution of the land‐sea thermal contrast. However, testing of this hypothesis is hindered by poor constraints on the timing and precise palaeogeographic dynamics of the retreat. Here, we present an improved integrated bio‐ and magnetostratigraphic chronological framework of the previously studied marine to continental transition in the southwest Tarim Basin along the Pamir and West Kunlun Shan, allowing us to better constrain its timing, cause and palaeoenvironmental impact. The sea retreat is assigned a latest Lutetian–earliest Bartonian age (ca. 41 Ma; correlation of the last marine sediments to calcareous nannofossil Zone CP14 and correlation of the first continental red beds to the base of magnetochron C18r). Higher up in the continental deposits, a major hiatus includes the Eocene–Oligocene transition (ca. 34 Ma). This suggests the Tarim Basin was hydrologically connected to the Tethyan marine Realm until at least the earliest Oligocene and had not yet been closed by uplift of the Pamir–Kunlun orogenic system. The westward sea retreat at ca. 41 Ma and the disconformity at the Eocene–Oligocene transition are both time‐equivalent with reported Asian aridification steps, suggesting that, consistent with climate modelling results, the sea acted as an important moisture source for the Asian continental interior.     

Life cycle assessment of pyrolysis–gasification as an emerging municipal solid waste treatment technology

Waste-to-energy technologies are considered as one of the key waste treatment technologies due to their energy and heat recovery efficiencies from the waste. A number of research studies were accomplished to understand the potential environmental burdens from emerging waste treatment technologies such as pyrolysis–gasification (PG). The aim of this study was to examine the PG of municipal solid waste (MSW) treatment process through a life cycle assessment (LCA) method. The study also includes a comparative LCA model of PG and incineration to identify the potential environmental burdens from the existing (incineration) and emerging (PG) waste treatment technologies. This study focused on ten environmental impact categories under two different scenarios, namely: (a) LCA model of PG and (b) comparative LCA model of PG and incineration. The scenario (a) showed that PG had significant environmental burdens in the aquatic eco-toxicity and the global warming potential impact categories. The comparative scenario (b) of PG and incineration of MSW showed that PG had comparatively lower potential environmental burdens in acidification, eutrophication, and aquatic eco-toxicity. Both LCA models showed that the environmental burdens were mainly caused by the volume of the thermal gas (emissions) produced from these two technologies and the final residue to disposal. Therefore, the results indicate that the efficiency and environmental burdens of the emerging technologies are dependent on the emissions and the production of final residue to the landfill.     

Kenntnis der Randstrukturen des Witwatersrand-Beckens im nördlichen Oranje-Freistaat-Goldfeld (Südafrika)

Zusammenfassung Eine Analyse der Randstrukturen des Witwatersrand-Beckens im nördlichen Oranje-Freistaat-Goldfeld zeigt, daß das tektonische Bild der Beckenrandregion nacheinander durch verschiedene Deformationsakte von unterschiedlichem Charakter geprägt worden ist. Auf eine Einengungsphase von spät-Witwatersrand-Alter, die zur Bildung einer randlichen Aufrichtungszone und zum Aufreißen eines Systems von 'normalen und antivergenten Aufschiebungen führte, folgte während des Unteren Ventersdorp eine jüngere Zerrungsphase, bei der es zu einem staffeiförmlgen Zerbrechen der ursprünglich eingeengten Scholle kam. Die Zerrung hängt sehr wahrscheinlich mit dem Zerbrechen der Beckenrandregion während oder unmittelbar nach der Extrusion der Unteren Ventersdorp-Laven zusammen. Dabei wurde ein schmaler randparalleler Streifen der Beckenfüllung in einem Graben versenkt ('Odendaalsrus-Graben). Die abgesunkenen Schollenteile sind in sich noch stark zerbrochen und gewöhnlich schiefgestellt. Da der versenkte Streifen durch ein primäres Einmuldungsstadium hindurchgegangen ist, deutet die Grabenbildung offenbar eine Fortsetzung der Beckenbildungsvorgänge 'mit anderen Mitteln an. — Die Bewegungen haben ein Alter von etwa 2,1 Mrd. Jahren; sie fallen somit ins frühe Präkambrium und sind keinesfalls 'intraalgonkisch, wie es noch bis in die jüngste Vergangenheit angenommen wurde.Tektonische Experimente haben ergeben, daß sich die wichtigsten Störungssysteme der realen Beckenrandstrukturen bei entsprechend gewählter Versuchsanordnung auch künstlich erzeugen lassen.

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The Orange Free State goldfield represents the southernmost part of the Witwatersrand Basin (Fig. 1) which is completely buried under a cover of Ventersdorp and Karroo rocks. The pre-Karroo geology of this area is characterized by a major rift system trending SSW-NNE ('Odendaalsrus graben), followed to the east by a V-shaped horst and two minor rift blocks (Fig. 2). The main graben is bounded by two principal faults (Border Fault, De Bron Fault, Fig. 4) which are roughly parallel to the western rim of the basin.A tectonic analysis of the basin-edge structures in the northern part of the graben reveals that the basin rim has been subjected to a sequence of deformational acts working over a considerable period of time. A primary compression of the basin-edge region in Upper Witwatersrand times resulted in the formation of a marginal fold; since sedimentation continued, the different stages of the folding process were sometimes preserved by a set of minor unconformities within the youngest sediments (Elsburg A Reefs, Fig. 5). With increasing lateral pressure a couple of reverse faults developed to support the folding (faults No. 10 and 11, Figs. 6 and 7); the minor thrust faults No. 19 and 21 represent the second component of this fault system. A reconstruction of the original depositional plain of the Lower Agglomerate shows that the main thrust faults (No. 10 and 11) are definitely older than the Elsburg A 1 Reef and have been obviously revived after the younger sediments had been laid down (Fig. 8 a).In a later stage compression gave way to tensional forces bringing about a fracturing of the overturned limb of the marginal fold along normal faults (faults No. 4 and 7, Figs. 6 and 7). There is reason to believe that the tensional phase was associated with the incipient rifting during early Ventersdorp times and that these faults were more or less contemporaneous with the general tilting of the basin-edge as displayed to-day (cf. Figs. 3 and 4). Because of the westerly tilt the Boulder Beds dip towards the west, although they must have been originally deposited on a ± horizontal or slightly basinward dipping plain. Faulting was mostly accomplished before deposition of the Ventersdorp sediments and the Upper Ventersdorp Lavas took place; the latter are seldom or only to a small degree affected by the fractures (Figs. 3 and 4). — The age of the tectonics is about 2,1×10⁹ years, i. e. early Precambrian and not Algonkian as formerly supposed.Experimental work aiming at an imitation of the observed basin-edge structures has shown that the principal tectonic features can be produced artificially (Figs. 8 a and b). This refers in particular to the main system of thrust-faults as well as to the younger step-faults caused by tension.

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Résumé Les structures tectoniques au bord du Bassin de Witwatersrand dans le district de mines d'or septentrional de la République d'Orange (Afrique du Sud) ont été analysées. Il s'est montré qu'elles sont déterminées par l'action de plusieurs phases de déformation successives de caractères différents. Une phase de compression d'âge Witwatersrand supérieur a d'abord amené un redressement des couches dans une zone marginale du bassin, avec chevauchements à vergences «normales» et inverses. Elle était suivie pendant le Ventersdorp inférieur d'une phase de traction qui produisit des cassures en gradins dans le secteur primitivement comprimé. La traction est très vraisemblablement en relation avec l'effondrement de la zone marginale du bassin pendant ou peu après l'extrusion des laves inférieures de Ventersdorp. Une bande étroite de sédiments, parallèle au bord du bassin, fut alors affectée d'un affaissement (formation du «graben d'Odendaalsrus») où de nombreuses cassures à l'intérieur des compartiments affaissés ont résulté dans la formation de blocs plus ou moins inclinés. Puisque cette zone a d'abord passé par un stade synclinal, on a l'impression que l'effondrement du graben ne représente que la reprise de l'affaissement général du bassin à l'aide d'une «technique nouvelle». - Les mouvements ont un âge de 2.1 milliards d'années, ils datent par conséquent du Précambrien inférieur et ne sont point «intra-algonkiques» comme il fut encore admis tout récemment.Il a été possible de reproduire artificiellement les systèmes de failles les plus importants de la zone marginale du bassin, si les conditions de l'expériment étaient favorables.

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