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11 – 20 of 205Natalia Ewa Zalewska, Maja Mroczkowska-Szerszeń, Joerg Fritz and Maria Błęcka
This paper aims to characterize the mineral composition of Martian surfaces based on Thermal Emission Spectrometer (TES; Mars Global Surveyor) as measured in the infrared thermal…
Abstract
Purpose
This paper aims to characterize the mineral composition of Martian surfaces based on Thermal Emission Spectrometer (TES; Mars Global Surveyor) as measured in the infrared thermal range. It presents modeling and interpreting of TES spectral data from selected Martian regions from which the atmospheric influences had been removed using radiative transfer algorithm and deconvolution algorithm. The spectra from the dark area of Cimmeria Terra and the bright Isidis Planitia were developed in Philip Christensen’s and Joshua Bandfield’s publications, where these spectra were subjected to spectral deconvolution to estimate the mineral composition of the Martian surface. The results of the analyses of these spectra were used for the modeling of dusty and non-dusty surface of Mars. As an additional source, the mineral compositions of Polish basalts and mafic rocks were used for these surfaces as well as for modeling Martian meteorites Shergottites, Nakhlites and Chassignites. Finally, the spectra for the modeling of the Hellas region were obtained from the Planetary Fourier Spectrometer (PFS) – (Mars Express) and the mineralogical compositions of basalts from the southern part of Poland were used for this purpose. The Hellas region was modeled also using simulated Martian soil samples Phyllosilicatic Mars Regolith Simulant and Sulfatic Mars Regolith Simulant, showing as a result that the composition of this selected area has a high content of sulfates. Linear spectral combination was chosen as the best modeling method. The modeling was performed using PFSLook software written in the Space Research Centre of the Polish Academy of Sciences. Additional measurements were made with an infrared spectrometer in thermal infrared spectroscopy, for comparison with the measurements of PFS and TES. The research uses a kind of modeling that successfully matches mineralogical composition to the measured spectrum from the surface of Mars, which is the main goal of the publication. This method is used for areas where sample collection is not yet possible. The areas have been chosen based on public availability of the data.
Design/methodology/approach
The infrared spectra of the Martian surface were modeled by applying the linear combination of the spectra of selected minerals, which then are normalized against the measured surface area with previously separated atmosphere. The minerals for modeling are selected based on the expected composition of the Martian rocks, such as basalt. The software used for this purpose was PFSLook, a program written in C++ at the Space Research Centre of the Polish Academy of Sciences, which is based on adding the spectra of minerals in the relevant percentage, resulting in a final spectrum containing 100 per cent of the minerals.
Findings
The results of this work confirmed that there is a relationship between the modeled, altered and unaltered, basaltic surface and the measured spectrum from Martian instruments. Spectral deconvolution makes it possible to interpret the measured spectra from areas that are potentially difficult to explore or to choose interesting areas to explore on site. The method is described for mid-infrared because of software availability, but it can be successfully applied to shortwave spectra in near-infrared (NIR) band for data from the currently functioning Martian spectroscopes.
Originality/value
This work is the only one attempting modeling the spectra of the surface of Mars with a separated atmosphere and to determine the mineralogical composition.
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Tharwat H. Abdel Hafeez, Mohamed A. S. Youssef and Waheed H. Mohamed
The present work utilizes airborne gamma ray spectrometric data in a trial to refine surface geology of igneous, metamorphic and sedimentary rocks, detect any radioactive…
Abstract
The present work utilizes airborne gamma ray spectrometric data in a trial to refine surface geology of igneous, metamorphic and sedimentary rocks, detect any radioactive mineralization at Gabel Umm Tineidba area South Eastern Desert, Egypt. The study area is covered by rock exposures ranging in age from the Precambrian to Quaternary. Airborne gamma ray spectrometry can be very helpful in mapping surface geology. This provides estimates of the apparent surface concentrations of the most common naturally occurring radioactive elements, such as potassium (K), equivalent uranium (eU) and equivalent thorium (eTh). This is based on the assumption that, the absolute and relative concentrations of these radioelements vary measurably and significantly with lithology. The composite image technique is used to display simultaneously three parameters of the three radioelement concentrations and their three binary ratios on one image. The technique offers much in terms of lithological discrimination, based on color differences and showed efficiency in defining areas, where different lithofacies occur within areas mapped as one continuous lithology. The integration between surface geological information and geophysical data led to detailing the surface geology and the contacts between different rock units. Significant locations or favourable areas for uranium exploration are defined, where the measurements exceed (X+2S), taking X as the arithmetic mean of eU, eU/eTh and eU/K measurements and S as the standard deviation corresponding to each variables. The study area shows the presence of fifteen relatively high uraniferous zone. In addition, the trend analysis based on the total count map and the published geological map shows that, most of the well-developed structural lineaments have NS, ENE, NNE and NNW trends.
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Ke Ma, Yu Li, Guoyang Liu, Gang He, Chun Sha and Yilin Peng
The purpose of this study is to investigate the deformation characteristics and failure modes of the right bank slope of Xiluodu Hydropower Station after excavation.
Abstract
Purpose
The purpose of this study is to investigate the deformation characteristics and failure modes of the right bank slope of Xiluodu Hydropower Station after excavation.
Design/methodology/approach
Micro-seismic monitoring technology is applied to obtain the microfracture information and study the internal damage evolution law of the slope rock mass. A numerical model for discontinuous deformation analysis (DDA) is established to analyse the deformation characteristics and failure mode of the slope. Micro-seismic monitoring and DDA can verify and supplement each other's results in the investigation of slope failure.
Findings
The results show that the slope has a downhill displacement along the weathered zone under natural conditions; the maximum resultant displacement at the monitoring point is 380 mm. The micro-seismic events are concentrated in an area located 30–100 m horizontally away from the slope surface and at an elevation of 390–470 m. The distribution of these micro-seismic events is consistent with the location of the unloading and weathered zones; it is the same as the DDA simulation result.
Originality/value
The study is anticipated to be used as reference for the stability analysis of rock slopes. By combining the continuous (micro-seismic monitoring technology) and discontinuous (DDA) methods, the entire process starting from the gradual accumulation of internal rock micro-damage to the macroscopic discontinuous deformation and failure of the slope can be investigated.
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Amobichukwu Chukwudi Amanambu and Christiana Ndidi Egbinola
The purpose of this paper is to examine the presence of geogenic contaminants in groundwater from shallow aquifers of the crystalline basement complex rocks of Ibadan…
Abstract
Purpose
The purpose of this paper is to examine the presence of geogenic contaminants in groundwater from shallow aquifers of the crystalline basement complex rocks of Ibadan south-western, Nigeria.
Design/methodology/approach
A total of 30 drinking water samples, (six samples each from the five major lithologic formations of the study area) were collected from hand dug wells during the rainy season. Atomic absorption spectrophotometry was used to determine concentrations of arsenic, iron and fluoride in drinking water samples and also concentrations of other chemical parameters that could affect the concentrations of the geogenic contaminants including pH, Ca, Mg, Na and SO42−. Descriptive statistics, multiple correlation and analysis of variance were used to examine the relationship between the geogenic contaminants and concentration of other chemical parameters while inverse distance weighting was used to produce risk maps.
Findings
The results showed Arsenic concentration exceeding the WHO recommended concentration for drinking water in all the samples within the area. Samples from 16.6 per cent of the wells exceeded the recommended limit for fluoride while iron was present in most of the samples within acceptable limits. The study also revealed no significant difference in concentration of contaminants between the geologic formations.
Originality/value
Geogenic contamination has been scarcely studied in Nigeria. This research, therefore, is a paradigm shift in the study of groundwater contamination which had been mainly focused on anthropogenic contaminants. The outcome of this research will engender policy makers and researchers to pay more attention to geogenic contamination than anthropogenic contaminants in Nigeria.
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Carlos Magno Muniz e Silva, Antoˆnio Stellin Jnr, Edson Guedes da Costa and Wildor Theodoro Hennies
Conventional rock blasting promotes many negative environmental impacts including ground vibration, flying rock, air blast, and the emission of noise, dust and gases. An…
Abstract
Conventional rock blasting promotes many negative environmental impacts including ground vibration, flying rock, air blast, and the emission of noise, dust and gases. An unconventional alternative process is the application of electrohydraulic principles. Electrohydraulic blasting is able to create a state of fracturing and rupture in the rock, almost instantly. A high current impulse generator produces the energy, without the above environmental impacts caused by conventional explosives. It is particularly suitable for application in urban areas. The paper describes laboratory experiments, theoretical analysis, consideration of the geomechanical criteria of rock failure and analysis of the electrical parameters of impulse generators related to rock fragmentation. The laboratory experiments included geomechanical and electrohydraulic tests on limestone samples from 50kg up to 150kg. The test results show satisfactory efficiency and energy losses.
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R. Askari, M.F. Ikram and S. H. Hejazi
Thermal conduction anisotropy, which is defined by the dependency of thermal conductivity on direction, is an important parameter in many engineering and research studies such as…
Abstract
Purpose
Thermal conduction anisotropy, which is defined by the dependency of thermal conductivity on direction, is an important parameter in many engineering and research studies such as the design of nuclear waste depositional sites. In this context, the authors aim to investigate the effect of grain shape in thermal conduction anisotropy using pore scale modeling that utilizes real shapes of grains, pores and throats to characterize petrophysical properties of a porous medium.
Design/methodology/approach
The authors generalize the swelling circle approach to generate porous media composed of randomly arranged but regularly oriented elliptical grains at various grain ratios and porosities. Unlike previous studies that use fitting parameters to capture the effect of grain–grain thermal contact resistance, the authors apply roughness to grains’ surface. The authors utilize Lattice Boltzmann method to solve steady state heat conduction through medium.
Findings
Based on the results, when the temperature field is not parallel to either major or minor axes of grains, the overall heat flux vector makes a “deviation angle” with the temperature field. Deviation angle increases by augmenting the ratio of thermal conductivities of solid to fluid and the aspect ratios of grains. In addition, the authors show that porosity and surface roughness can considerably change the anisotropic properties of a porous medium whose grains are elliptical in shape.
Originality/value
The authors developed an algorithm for generation of non-circular-based porous medium with a novel approach to include grain surface roughness. In previous studies, the effect of grain contacts has been simulated using fitting parameters, whereas in this work, the authors impose the roughness based on the its fractal geometry.
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Dion Hoe‐Lian Goh, Khasfariyati Razikin, Chei Sian Lee, Ee Peng Lim, Kalyani Chatterjea and Chew Hung Chang
Mobile devices used in educational settings are usually employed within a collaborative learning activity in which learning takes place in the form of social interactions between…
Abstract
Purpose
Mobile devices used in educational settings are usually employed within a collaborative learning activity in which learning takes place in the form of social interactions between team members while performing a shared task. The authors aim to introduce MobiTOP (Mobile Tagging of Objects and People), a mobile annotation system that allows users to contribute and share geospatial multimedia annotations via mobile devices.
Design/methodology/approach
Field observations and interviews were conducted. A group of trainee teachers involved in a geography field study were instructed to identify rock formations by collaborating with each other using the MobiTOP system. The trainee teachers who were in the field were guided by their lab counterparts on the tasks required to identify the rock formations.
Findings
Participants were able to appreciate the fieldwork task as it augmented their classroom lessons. The system allowed them to communicate with one another in order to meet the objectives of the study. However, there were some technical difficulties in relation to the affordance of the mobile and web applications that affected the usefulness of the applications.
Originality/value
This study reports the design and implementation of a mobile annotation system that was evaluated in an actual classroom setting. The results of this work have implications for both mobile applications design and mobile learning.
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Piyoosh Rautela and R.K. Pande
Climatic conditions as also the agrarian economy of the Indian subcontinent is greatly affected by the monsoonal winds that are characterized by heavy rains between June and…
Abstract
Purpose
Climatic conditions as also the agrarian economy of the Indian subcontinent is greatly affected by the monsoonal winds that are characterized by heavy rains between June and September. The paper is an attempt to break the myth that landslides are only confined to monsoonal months that normally have concentrated rains and can be expected in other seasons as well and, therefore, disaster alert levels cannot be relaxed during non‐monsoonal season. The communication also attempts to identify slowly ongoing weathering processes that might cause to slope failure without rains and, therefore, paves way for identifying similar landslide prone areas.
Design/methodology/approach
The paper discusses two landslides of the recent past; Uttarkashi landslide of 23 September 2003 and Ramolsari landslide of 30 March 2005 that took place after the seizure of the monsoonal rains and is based upon the first hand field observations of the authors. The paper discusses the likely causes of the slides along with the implications of this new trend of landslides taking place in the non‐monsoonal season upon the disaster management strategy of the state.
Findings
The investigations reveal that precipitation could be considered the trigger in case of Uttarkashi landslide but there exist no evidences to suggest that the Ramolsari landslide could have been triggered by increased pore water pressure. Slow ongoing and hard to observe processes of weathering seem to have initiated this slide.
Research limitations/implications
For the purpose of metrological parameters, the study relies upon the data of the state run rain gauges that do not have an appreciably good spatial distribution. Rainfall data of the nearest observation points is, therefore, taken as representative of the rainfall in the area under present focus. For Ramolsari, the rainfall data of Tehri is used while Uttarkashi has a rainfall recording observatory.
Originality/value
The paper highlights the importance of keeping the preparedness levels high for prompt post‐disaster operations all through the year. This paper advocates redefining high alert period for landslide hazard and for following high alert all through the year particularly in areas prone to landslides.
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KEVIN M. O'CONNOR and CHARLES H. DOWDING
To simulate the kinematics associated with mining‐induced subsidence in a blocky rock mass, a hybrid rigid block model was developed by combining a small displacement code with a…
Abstract
To simulate the kinematics associated with mining‐induced subsidence in a blocky rock mass, a hybrid rigid block model was developed by combining a small displacement code with a large displacement code. Gravity was applied to a rigid block mesh using an implicit formulation and the equilibrium displacements are then used as initial conditions for an explicit analysis in which excavation of a longwall mine panel and subsequent subsidence was simulated. A parameter study was performed to evaluate the influence of rigid block contact stiffness, vertical joint density, and contact roughness on mining‐induced strata movements for comparison with previously obtained field measurements. The best agreement between measured and calculated displacements was obtained when a relatively low stiffness value was maintained constant for all contacts. A surprising result was that neither increasing the density of vertical joints nor reducing the rigid block contact roughness improved the agreement between measured and simulated displacements.
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