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Effects of porosity and composition on seismic wave velocities and elastic moduli of lower cretaceous rocks, central Lebanon

Salah M. K., Alqudah M., El-Aal A. K. A, Barnes C.

Acta Geophysica

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2018

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Vol. 66, no. 5

867--894

EN

We collected 40 rock samples from the Cretaceous strata exposed at central Lebanon in order to study the effects of porosity and rock composition on their seismic wave velocities and elastic moduli. Several sedimentological and mineralogical studies were conducted to evaluate the rock composition, provenance, depositional conditions, and the diagenetic history of the studied rocks. Porosity, bulk and grain densities and seismic wave velocities were measured for 35 drilled core samples at ambient conditions in the laboratory. Velocity measurements were conducted on the dry core samples utilizing the pulse transmission technique. Petrographically, four lithofacies have been identified under the polarizing microscope. From oldest to youngest, these comprise arenitic sandstone, lithic limestone, oolitic limestone, and micritic limestone. Investigations of representative rock samples under the SEM revealed that a number of diagenetic processes have impacted the studied rocks, and thereby affected their petrophysical properties. The XRD analysis, on the other hand, revealed that quartz and calcite are the dominant minerals in the sandstones of the Chouf Formation and the limestones of the Abeih and Mdairej Formations, respectively. The measured porosity, bulk density, and compressional and shear wave velocities of the investigated rocks vary, respectively, between 2.14–10.05%, 2.41–2.67 g/cm3, 3885–6385 m/s and 2246–3607 m/s. The grain density was calculated from the measured porosity and bulk density data and varies narrowly between 2.64 and 2.78 g/cm3. We further calculated the Poisson’s ratio and the moduli of shear, bulk, and Young from the measured bulk density and seismic wave velocities. Calculated values of these parameters vary between 0.18–0.28, 1.23–3.43 × 1010 Pa, 2.03–6.18 × 1010 Pa and 3.06–8.69 × 1010 Pa, respectively. The generalized mixture rule is used to provide a unified description of the physical properties of the studied rocks regarding their component properties, volume fractions, and microstructures. We constructed a number of relationships between the measured petrophysical and elastic properties to evaluate the mutual interdependence of these parameters and assess the effects of porosity and rock type on these important rock characteristics.

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A model of the response of GMR of metallic multilayers to external magnetic field

Uba J. I., Ekpunobi A. J., Ekwo P. I .

Materials Science Poland

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2015

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Vol. 33, No. 4

835--840

EN

It has not been possible to transform resistivity models in terms of magnetic field in order to account for variation of giant magnetoresistance (GMR) with external magnetic field, which would have led to determination of material properties. This problem is approached mathematically via variation calculus to arrive at an exponential function that fits observed GMR values. Using this model in free electron approximation, the mean Fermi vector, susceptibility and total density of states of a number of metallic multilayers are determined from their reported GMR values. Susceptibility is found to depend on interface roughness and antiferromagnetic (AF) coupling; thus, it gives qualitative measure of interface quality and AF coupling. Comparison of susceptibilities and GMRs of electrodeposited and ion beam sputtered Co/Cu structures shows that a rough interface suppresses GMR in the former but enhances it in the latter.

3

Do high-rise apartment condos equally revalue the neighboring housing?

Marmolejo Duarte C., Skarmeta Cornejo E., Aguirre Nunez C.

Czasopismo Techniczne. Architektura

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2010

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R. 107, z. 3-A

33-45

EN

Many studies have analyzed the market premium enjoyed by houses located within gated communities; nevertheless little or no attention has been paid on the impact that such a sort of development produces on the surrounding housing market. This question becomes very important in the cities in which gated communities or other common interest communities, aimed to medium and high socioeconomic groups, are traditionally confined to low incomes enclaves. In this research, using a hedonic pricing model based on information of detached houses sold in Nunoa between 2002 and 2004, attempt to measure the impact that has been produced by High-rise condos recently built on the sale price of such houses. The results suggest that a medium sized condo produces a revalorization of 4.7% in the houses that surround it, although this impact is quite local. The spatial analysis of data, through a geographically weighted regression model (GWR), reveals that the revalorization is higher in those areas where wealthier families use to live, in that way the most creditworthy householders further increase their asset's value. Therefore, the condominiums being built on Nunoa can increase the municipal revenues derived from land taxes, nevertheless the revalorization of the housing stock is far from being uniform, reinforcing the value of the most values properties around them.

PL

Wiele prac naukowych analizuje negatywny wpływ wywierany przez wysokościowce na środowiska mieszkaniowe w postaci cienia, szumu, wiatru itp. Skoro jednak budynki takie wznoszone są z myślą o wysokodochodowych mieszkaniach, nie jest jasne, czy proces podnoszenia statusu oraz wzrost szacowanej wartości gruntu wytwarza pozytywny wpływ na sąsiednie środowisko mieszkaniowe, jak twierdzą Salcedo i Torres (2004) oraz Cacares & Sabatini [3]. W niniejszym artykule, wykorzystując hedonistyczny model cen oparty na informacjach na temat domów jednorodzinnych sprzedawanych w Nunoa (Santiago de Chile) w latach 2002-2004, spróbujemy zmierzyć wpływ niedawno wybudowanych budynków z mieszkaniami własnościowymi na cenę takich domów. Wyniki sugerują, że budynek średniej wielkości daje rewaloryzację 4.7% w otaczających go domach, mimo że wpływ ten ma dość ograniczony zasięg. Przestrzenna analiza danych poprzez geograficzny model regresji (GMR) ukazuje, że rewaloryzacja wyższa jest na obszarach zamieszkanych przez zamożniejsze rodziny. W ten sposób najbardziej wiarygodni kredytowo mieszkańcy nadal zwiększają wartość swego majątku. Dlatego właśnie budynki z mieszkaniami własnościowymi wznoszone w Nunoa mogą zwiększyć dochody miasta uzyskane z podatków gruntowych. Rewaloryzacja zasobów mieszkaniowych daleka jest jednak od uniformizacji. Wzmacnia ona wartość najdroższych posiadłości.

4

Od fal spinowych do gigantycznego magnetooporu (GMR) i dalej

Grunberg P. A.

Postępy Fizyki

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2009

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T. 60, z. 2

55-66