Search results for "rock"

Solid Rocket Motor Combustion Instabilities: Analysis of the Transition to the First Limit Cycle

2009

A nonlinear multi time-scale analysis of the solid propellant rocket motor transition to the first limit cycle is presented and the motor behavior subsequent to some relevant transition scenarios is investigated. Important physical parameters characterizing the transition to limit cycle are then put in evidence and their cross-effects are studied. The analysis takes into account the effects of acoustic-vorticity-entropy wave coupling, waves steepening, rotational and viscous flow losses due to the steep-fronted waves, energy losses in the steepened state, nonlinear energy pathways and includes the study of the oscillatory energy losses in the nozzle, the unsteady combustion and the combusti…

J. Vītiņa novērojumi Liepājas Glūdas dzelzceļa izrakumos

1929

Saturs: I. Reljefs un ieži II. Galvenie augšņu veidi III. Tuvākie darbi zemkopības pacelšanā apskatītā apvidū IV. Galvenie slēdzieni

Habitat geometry of benthic substrata: effects on arrival and settlement of mobile epifauna

1996

Abstract The effect of substratum complexity on the early stages of colonization by mobile epifauna was assessed through a comparative study based on the architecture of artificial substrata. We conducted field observations over 4 years, on six types of small plastic substrata placed in the low intertidal zone of an exposed rocky shore, for varied immersion periods (1, 2, 4 and 12 wk). The use of artificial substrata allowed us to manipulate independently structural and spatial features of the habitat, such as total area, amount of folds, intercepting area, total volume, and interstitial volume. The invertebrate fauna colonizing over 300 sample units was recorded, and their densities compar…

Slope instability in a historical and architectural interest site: the Agrigento hill (Sicily-Italy)

2014

Eclogites and garnet pyroxenites: Similarities and differences

2010

Eclogites and garnet pyroxenites are genetically linked to basaltic precursors. Traditionally garnet pyroxenites are linked to fractionation of basaltic Magmas Over a range of mantle pressures and more recently they have been implicated in the genesis of ocean islands. in contrast eclogites are linked to the subduction of slab basalt and gabbro precursors which may be hydrothermally altered. Recently this subduction paradigm has been questioned. We present mineralogical, trace element and O isotopic data for eclogites and garnet pyroxenites that reveal some similarities but also important chemical and isotopic differences that support a distinct provenance (i.e., age and process). Continent…

(Table 1) Age determination of sediment profile SO90-41KL/63KA

2002

The 14C ages of planktonic foraminifers Globigerinoides sacculifer bracketing the Younger Dryas in a d18O record of Globigerinoides ruber from a laminated sediment core on the Pakistani continental margin suggest that surface reservoir ages in the Arabian Sea were in excess of 1000 years during the deglaciation. A least squares error fit of a detailed 14C chronology to the (atmospheric) tree ring record gave variable early Holocene reservoir ages between 780 and 1120 years, well above the prebomb value of 640 years. Mid-Holocene reservoir ages are less well constrained but were probably closer to the prebomb value. The method used to fit individual core sections to the tree ring record was …

Sedimentary and diagenetic markers of the restriction in a marine basin: the Lorca Basin (SE Spain) during the Messinian

1998

Abstract The Lorca Basin (southeastern Spain) is part of a chain of small marginal Neogene basins located in the structurally active Betic area. The Upper Miocene (Messinian) sequence is composed of a thick diatomite-bearing series (Tripoli Unit) overlain by the Main Evaporites, analogous to the classical succession that records the main events during the Salinity Crisis in the Mediterranean region. The shallow restricted conditions of this region amplified the sedimentary responses to local and global forcings. An integrated approach using sedimentology, micropalaeontology, stable isotope geochemistry and organic geochemistry has been applied to the Tortonian/Messinian succession of the Lo…

Evidence of the Zanclean megaflood in the eastern Mediterranean Basin

2018

A. Micallef et. al.

(Table 2) Age determination of sediment core NIOP-C2_929

2007

In this study we present a sea surface temperature (SST) record from the western Arabian Sea for the last 20,000 years. We produced centennial-scale d18O and Mg/Ca SST time series of core NIOP929 with focus on the glacial-interglacial transition. The western Arabian Sea is influenced by the seasonal NE and SW monsoon wind systems. Lowest SSTs occur during the SW monsoon season because of upwelling of cold water, and highest SSTs can be found in the low-productivity intermonsoon season. The Mg/Ca-based temperature record reflects the integrated SST of the SW and NE monsoon seasons. The results show a glacial-interglacial SST difference of ~2°C, which is corroborated by findings from other Ar…

Determination of the porosity, permeability and diffusivity of rock in the excavation-disturbed zone around full-scale deposition holes using the -PM…

1998

Abstract Three experimental holes the size of deposition holes in a KBS-3 type repository (depth 7.5 m and diameter 1.5 m) were bored in hard granitic rock in the Research Tunnel at Olkiluoto to study, among other things, the properties of the rock in the excavation-disturbed zone. In the analysis described in this report, the porosities, effective diffusivities and permeabilities of disturbed and intact rock were determined by using two novel methods: the 14 C -polymethylmethacrylate method and the He-gas method. In addition, the structure of the rock in the excavation-disturbed zone was assessed using both scanning electron and optical microscopy.