Analysis of jitter influence in fast frequency measurements

This paper presents a theoretical analysis of possible jitter impact in application of numeric criterion for fastmeasurement of frequency by coincidence principle. The primary goal is the generation of a signal containing a known amount of each jitter components. This signal was used for testing signals with regular pulse trains. Initially, jitter components are analyzed and modeled individually. Next, sequences for combining different kinds of jitter are modeled, simulated and evaluated. Jitter model simulation in Matlab is utilized to show the independence of frequencymeasurement results on the total jitter present in the reference and desired pulse trains independently. A good agreement between previously introduced theory of fastmeasurement of frequency and simulation in jitter presence is verified; these results allows to engineers use the numeric criterion for fastmeasurement of frequency in spite to interactions among jitter components in various applications for frequency domain sensors.

Pressure measurements of the detachment bubble on the Bolund Island

Pressure measurements on the surface of a 1:230 scale model of Bolund Island are presented. The model is smooth and no boundary layer generation has been considered since the experiment is designed as the simplest possible reference case. Measurement have been taken for a range of Reynolds numbers based on the average undisturbed wind speed U∞ and the maximum height of the island, h [1.7×104, 8.5×104], and for a range of wind directions. Four minutes time series of pressure in more than 400 points have been acquired and analysed to obtain the spatial distribution of both the time average and the variance of the pressure signal. The horizontal extension of the detachment bubble for the different Reynolds numbers and wind directions is identified by isobars and curves of constant value of pressure variance. The applicability of this technique for evaluating the horizontal topology of high turbulence regions associated to detachment bubbles after escarpments in potential wind farm sites is analysed. The results obtained shows that the behaviour of the mean pressure coefficient, Cp, the std. pressure coefficient, Cp, and the skewness of the pressure, Sp can be used to study the bubble over the island to a certain extent. This experiment is part of the set of different analysis on the Bolund test case that is being undertaken within WAUDIT project by the different scientific groups.

Pressure measurements of the detachment bubble on the Bolund Island

Pressure measurements on the surface of a 1:230 scale model of Bolund Island are presented. The model is smooth and no boundary layer generation has been considered since the experiment is designed as the simplest possible reference case. Measurement have been taken for a range of Reynolds numbers based on the average undisturbed wind speed U? and the maximum height of the island, h [1.7×104 , 8.5×104], and for a range of wind directions. Four minutes time series of pressure in more than 400 points have been acquired and analysed to obtain the spatial distribution of both the time average and the variance of the pressure signal. The horizontal extension of the detachment bubble for the different Reynolds numbers and wind directions is identified by isobars and curves of constant value of pressure variance. The applicability of this technique for evaluating the horizontal topology of high turbulence regions associated to detachment bubbles after escarpments in potential wind farm sites is analysed. The results obtained shows that the behaviour of the mean pressure coefficient, Cp, the std. pressure coefficient, C?p, and the skewness of the pressure, Sp can be used to study the bubble over the island to a certain extent. This experiment is part of the set of different analysis on the Bolund test case that is being undertaken within WAUDIT project by the different scientific groups.

Radon measurements in the cave houses of Crevillente (Spain)

This paper focuses on the cave houses of Crevillente (Spain) as a traditional housing experience which takes advantage of local environmental conditions through simple architectural proposals, paying particular attention to the presence of radon gas inside these underground constructions. Our aim is twofold: first, to analyse the architectural conditions of the different excavated typologies found in the municipality and second, to relate them to the existing radon gas levels after checking internal concentration by means of E-PERM® long-term devices placed inside the cave houses in 2011. The measurements corresponding to the main typologies in normal use conditions show that the highest values are 881.9 Bq/m3 in the cave typology, 484.1 Bq/m3 in the cave + attached constructions typology and 373.4 Bq/m3 in the cave + house typology, with geometric mean values of 572.1, 114.0 and 75.5 Bq/m3, respectively. It can be inferred from these results that cave house levels sometimes exceed those included in the 90/143/Euratom European Commission Recommendation on the protection of the public against indoor exposure to radon. The reason why cave houses are more susceptible to radon accumulation in their spaces lies in their direct and permanent contact with the ground where they are located.

In situ measurements of hydrogen sulfide, oxygen, and temperature in diffuse fluids of the ultramafic-hosted Logatchev hydrothermal vent field (Mid-Atlantic Ridge)

The Logatchev hydrothermal vent field (14°45'N, Mid-Atlantic Ridge) is located in a ridge segment characterized by mantle-derived ultramafic outcrops. Compared to basalt-hosted vents, Logatchev high temperature fluids are relatively low in sulfide indicating that the diffuse, low temperature fluids of this vent field may not contain sufficient sulfide concentrations to support a chemosymbiotic invertebrate community. However, the high abundances of bathymodiolin mussels with bacterial symbionts related to free-living sulfur oxidizing bacteria suggested that bioavailable sulfide is present at Logatchev. To clarify if diffuse fluids above mussel beds of Bathymodiolus puteoserpentis provide the reductants and oxidants needed by their symbionts for aerobic sulfide oxidation, in situ microsensor measurements of dissolved hydrogen sulfide and oxygen were combined with simultaneous temperature measurements. High temporal fluctuations of all three parameters were measured above the mussel beds. H2S and O2 co-existed with mean concentrations between 9-31 µM (H2S) and 216-228 µM (O2). Temperature maxima (<= 7.4°C) were generally concurrent with H2S maxima (<= 156 µM) and O2 minima (>= 142 µM). Long-term measurements for 250 days using temperature as a proxy for oxygen and sulfide concentrations indicated that the mussels were neither oxygen- nor sulfide-limited. Our in situ measurements at Logatchev indicate that sulfide may also be bioavailable in diffuse fluids from other ultramafic-hosted vents along slow- and ultraslow-spreading ridges.

Ripple migration directions and grain fabric measurements on ODP Hole 210-1276A sediments

Albian turbidites and intercalated shales were cored from ~1145 to 1700 meters below seafloor at Site 1276 in the Newfoundland Basin. Strata at this level dip ~2.5° seaward (toward an azimuth of ~130°) based on seismic profiles. In contrast, beds dip an average of ~10° in the cores. This higher apparent dip is the sum of the ~2.5° seaward dip and a measured hole deviation of 7.43°, which must be essentially in the same seaward direction. Using the maximum dip direction in the cores as a reference direction, paleocurrents were measured from 11 current-ripple foresets and 11 vector means of grain fabric in planar-laminated sandstones. Five of the planar-laminated sandstone samples have a grain imbrication 8°, permitting specification of a unique flow direction rather than just the line-of-motion of the current. Both ripples and grain fabric point to unconfined flow toward the north-northeast. There is considerable spread in the data so that some paleoflow indicators point toward the northwest, whereas others point southeast. Nevertheless, the overall pattern of paleoflow suggests a source for the turbidity currents on the southeastern Grand Banks, likely from the long-emergent Avalon Uplift in that area. On average, turbidity currents apparently flowed axially in the young Albian rift, toward the north. This is opposite to what might be expected for a northward-propagating rift and a young ocean opening in a zipperlike fashion from south to north.