73 resultados para gravimetry
Resumo:
During GANOVEX VI new gravity data were collected along an east-west profile in North Victoria Land south of the Drygalski Ice Tongue, extending 150 km across the Transantarctic Mountains, and comprising 21 data points. Thirty five additional data points were collected over a small area near Brimstone Peak, near the western end of the regional profile. The survey south of the Drygalski has been connected to northern gravity data (GANOVEX V) by a survey line of 12 points. All data have been terrain corrected, and are further constrained by satellite elevation (GPS) and radar ice-thickness measurements. A pronounced regional Bouguer gravity gradient decreasing to the west by approximately 3 mgal/km is superimposed over a coast-parallel belt of granitoid basement rock. West of this belt the local gravity fields become mote variable. Over Beta Peak (Ferrar dolerite) a 50 mgal spike is obser- ved. Within this area, the Ferrar sills are exposed at the surface. West of Brimstone Peak (Ferrar/Kirk patrick sequences), a smooth regional gradient appears to reassert itself. We interpret the initial gradient east (oceanward) of the break-in-slope to be representative of the crust/mantle boundary within the study area. We interpret the initial break-in-slope and the apparent flattening of the regional gradient to be an effect of the N-S trending zone of dense Ferrar sills and associated deep crusttil fractionate replacing less dense basement. We attribute the variability of the local field to be the product of sub-glacial density contrasts that cannot be removed. The regional gravity gradient of the profile is steeper than that observed to the north (Mt. Melbourne quadrangle) and shallower than that reported to the south (McMurdo Sound). The absolute values of the coastal points of origin south of the Drygalski and within the Mt. Melbourne quadrangle differ by 60 to 100 mgal. In addition, topographic relief within the regional transect area is subdued relative to the Transantarctic Mountains to the north and south. We speculate that the root structure of the Transantarctic Mountains undergoes a change somewhere between the Mt. Melbourne quadrangle and the region south of the Drygalski Ice Tongue.
Resumo:
The use of fly ash (FA) as an admixture to concrete is broadly extended for two main reasons: the reduction of costs that supposes the substitution of cement and the micro structural changes motivated by the mineral admixture. Regarding this second point, there is a consensus that considers that the ash generates a more compact concrete and a reduction in the size of the pore. However, the measure in which this contributes to the pozzolanic activity or as filler is not well defined. There is also no justification to the influence of the physical parameters, fineness of the grain and free water, in its behavior. This work studies the use of FA as a partial substitute of the cement in concretes of different workability (dry and wet) and the influence in the reactivity of the ash. The concrete of dry consistency which serves as reference uses a cement dose of 250 Kg/m 3 and the concrete of fluid consistency utilized a dose of cement of 350 Kg/m 3 . Two trademark of Portland Cement Type 1 were used. The first reached the resistant class for its fineness of grain and the second one for its composition. Moreover, three doses of FA have been used, and the water/binder ratio was constant in all the mixtures. We have studied the mechanical properties and the micro-structure of the concretes by means of compressive strength tests, mercury intrusion porosimetry (MIP) and thermal analysis (TA). The results of compressive strength tests allow us to observe that concrete mixtures with cements of the same classification and similar dosage of binder do not present the same mechanical behavior. These results show that the effective water/binder ratio has a major role in the development of the mechanical properties of concrete. The study of different dosages using TA, thermo-gravimetry and differential thermal analysis, revealed that the portlandite content is not restrictive in any of the dosages studied. Again, this proves that the rheology of the material influences the reaction rate and content of hydrated cement products. We conclude that the available free water is determinant in the efficiency of pozzolanic reaction. It is so that in accordance to the availability of free water, the ashes can react as an active admixture or simply change the porous distribution. The MIP shows concretes that do not exhibit significant changes in their mechanical behavior, but have suffered significant variation in their porous structure
Resumo:
At Sleipner, CO2 is being separated from natural gas and injected into an underground saline aquifer for environmental purposes. Uncertainty in the aquifer temperature leads to uncertainty in the in situ density of CO2. In this study, gravity measurements were made over the injection site in 2002 and 2005 on top of 30 concrete benchmarks on the seafloor in order to constrain the in situ CO2 density. The gravity measurements have a repeatability of 4.3 µGal for 2003 and 3.5 µGal for 2005. The resulting time-lapse uncertainty is 5.3 µGal. Unexpected benchmark motions due to local sediment scouring contribute to the uncertainty. Forward gravity models are calculated based on both 3D seismic data and reservoir simulation models. The time-lapse gravity observations best fit a high temperature forward model based on the time-lapse 3D seismics, suggesting that the average in situ CO2 density is about to 530kg/m**3. Uncertainty in determining the average density is estimated to be ±65 kg/m**3 (95% confidence), however, this does not include uncertainties in the modeling. Additional seismic surveys and future gravity measurements will put better constraints on the CO2 density and continue to map out the CO2 flow.
Resumo:
Raster graphic ampelometric software was not exclusively developed for the estimation of leaf area, but also for the characterization of grapevine (Viti vinifera L.) leaves. The software was written in C-Hprogramming language, using the C-1-1- Builder 2007 for Windows 95-XP and Linux operation systems. It handles desktop-scanned images. On the image analysed with the GRA.LE.D., the user has to determine 11 points. These points are then connected and the distances between them calculated. The GRA.LE.D. software supports standard ampelometric measurements such as leaf area, angles between the veins and lengths of the veins. These measurements are recorded by the software and exported into plain ASCII text files for single or multiple samples. Twenty-two biometric data points of each leaf are identified by the GRA.LE.D. It presents the opportunity to statistically analyse experimental data, allows comparison of cultivars and enables graphic reconstruction of leaves using the Microsoft Excel Chart Wizard. The GRA. LE.D. was thoroughly calibrated and compared to other widely used instruments and methods such as photo-gravimetry, LiCor L0100, WinDIAS2.0 and ImageTool. By comparison, the GRA.LE.D. presented the most accurate measurements of leaf area, but the LiCor L0100 and the WinDIAS2.0 were faster, while the photo-gravimetric method proved to be the most time-consuming. The WinDIAS2.0 instrument was the least reliable. The GRA.LE.D. is uncomplicated, user-friendly, accurate, consistent, reliable and has wide practical application.
Resumo:
Two Polarstern expeditions were conducted in 1995 (ANT-XII/4) and 2001 (ANT-XVIII/5a) to the Bellingshausen Sea and Amundsen Sea and the suspected Eltanin meteorite impact in the SE-Pacific. A survey of the sediment distribution and its acoustic structure along the cruise track was performed. The seafloor topography was sampled using the multibeam sonar system Hydrosweep DS2 which operates on a frequency of 15.5 kHz. The resulting AWI Bathymetric Chart of the Eltanin Meteorite Impact Area is based on a Digital Terrain Model of this area. The mapping was performed using ArcGIS. The Eltanin impact area which covers the 4.100 m high Freden Seamount is visualized by one overview sheet of the scale 1:200,000 and four 1:100,000 subsheets.
Resumo:
This study aimed to determine the concentration and inorganic chemical composition of samples from airborne particulate matter inhaled in fine and coarse fractions. Aerosol samples were collected in 2013 and 2014, from sites located in the cities of Londrina and Maringa, in the state of Paraná, Brazil. The samples were collected daily (24h) in two campaigns: winter and summer. For the collection, was used a dichotomous sampler with quartz fiber filter with 47 mm in size and 2 µm porosity, 97% efficiency, retaining particles of up to 0.3 µm. Quantification of the airborne particulate matter mass was performed by gravimetry method. The results from Londrina to PM2.5 and MP2,5-10 represent, respectively, 29.2% and 70.8% of airborne particulate matter in the winter campaign (2013), 30.9% (PM2.5) and 69.1 % (MP2,5-10) in the summer campaign (2013), and 35.9% (PM2.5) and 64.1% (MP2,5-10) in the winter 2014 campaign. In the city of Maringa, the results presented the percentage of 42.0% (PM2.5) and 58.0% (MP2,5-10) for the winter season (2014), and 28.8% (PM2.5) and 71.2 % (MP2,5-10) for the summer season (2014). The PM2.5/PM10 ratio was on average 0.3, demonstrating that both cities are developing urban areas. Analysis of the major soluble inorganic species in water (NO3-, SO42- and Cl-) associated with MP2,5-10 were quantified by ion chromatography at the LACA Laboratory in the State University of Londrina, with the largest contribution found in all campaigns was to NO3-. The NO3-/SO42- ratios above 1.0 indicate the local traffic contribution. The analysis of metals associated with PM2.5 was carried out by mass spectrometry with inductively coupled plasma (ICP-MS) in the Federal University of Santa Catarina. The Zn, Pb, Cu and Mn concentrations found in all campaigns indicate the contribution of mobile sources to PM2.5. The concentration of BCe in PM2.5 was determined by reflectance, with higher BCe concentrations being found in winter campaigns. In general, Londrina presented the highest concentrations from the species analyzed when compared to Maringá. In addition, the analysis of the air mass trajectories indicated the transportation of pollutants coming mainly from fires in the southeastern region of the country.
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We propose a very long baseline atom interferometer test of Einstein's equivalence principle (EEP) with ytterbium and rubidium extending over 10m of free fall. In view of existing parametrizations of EEP violations, this choice of test masses significantly broadens the scope of atom interferometric EEP tests with respect to other performed or proposed tests by comparing two elements with high atomic numbfers. In the first step, our experimental scheme will allow us to reach an accuracy in the Eotvos ratio of 7 . 10(-13). This achievement will constrain violation scenarios beyond our present knowledge and will represent an important milestone for exploring a variety of schemes for further improvements of the tests as outlined in the paper. We will discuss the technical realisation in the new infrastructure of the Hanover Institute of Technology (HITec) and give a short overview of the requirements needed to reach this accuracy. The experiment will demonstrate a variety of techniques, which will be employed in future tests of EEP, high-accuracy gravimetry and gravity gradiometry. It includes operation of a force-sensitive atom interferometer with an alkaline earth-like element in free fall, beam splitting over macroscopic distances and novel source concepts.
Desenvolvimento e caraterização de hidrogéis físicos e químicos a partir de polissacarídeos naturais
Resumo:
Dissertação de Mestrado, Engenharia Biológica, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2016
Resumo:
A new approach is described herein, where neutron reflectivity measurements that probe changes in the density profile of thin films as they absorb material from the gas phase have been combined with a Love wave based gravimetric assay that measures the mass of absorbed material. This combination of techniques not only determines the spatial distribution of absorbed molecules, but also reveals the amount of void space within the thin film (a quantity that can be difficult to assess using neutron reflectivity measurements alone). The uptake of organic solvent vapours into spun cast films of polystyrene has been used as a model system with a view to this method having the potential for extension to the study of other systems. These could include, for example, humidity sensors, hydrogel swelling, biomolecule adsorption or transformations of electroactive and chemically reactive thin films. This is the first ever demonstration of combined neutron reflectivity and Love wave-based gravimetry and the experimental caveats, limitations and scope of the method are explored and discussed in detail.