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Abstract

The world energy demand has become higher with the growing population, which has translated into an increase in emission of greenhouse gases into the atmosphere. For this reason, CO2 capture and storage has been undertaken to purify the atmosphere. For storing this CO2, it is necessary to have wells to inject it (deeper than 800 m); moreover, these wells need to have stability over time, and one of the stability aspects is the protection of steel against corrosion. Considering this aspect, the most common steels (focussed on American Petroleum Institute [API] steels) that can be used in an injector well were studied. The best performance was obtained using a high alloy content of Cr and Ni. Furthermore, the most important parameter analysed when corrosion is studied is the test time, which was modelled to stabilise the corrosion rates. The experiments were undertaken after a general review of different studies that investigated the corrosion of steel when in contact with CO2 in the vapour phase and under supercritical conditions.

Abstract

Heavy mineral component of 13 samples from the Lokoja and Patti Formations, Bida Basin have been studied for their textural characteristics, compositional abundance, maturity and provenance determinations. The suite of heavy minerals encountered is classified as opaque and non-opaque constituents. The non-opaque components include zircon, tourmaline, rutile, garnet, staurolite, epidote, kyanite, titanite, lawsonite, cassiterite, sillimanite, hornblende, hypersthene and andalu-site. The assemblage is generally dominated by zircon and tourmaline in the two formations. The constituent heavy minerals identified are dominated by ultra-stable and stable classes, whereas the ZTR indices indicate mineralogical immaturity coupled with textural immaturity of the constituent grains. This suggests the possible dominance of chemical weathering of the source rock. The suites of minerals recovered have been linked to both metamorphic and non-metamorphic crystalline rock origins.

Abstract

The Zletovo is lead–zinc (Pb–Zn) deposit, adjacent to the Plavica volcanic centre (R. Macedonia) with high-sulphidation and porphyry mineralisation. The analysis of fluid inclusions showed homogenisation temperatures in the range 335–145°C, which reflects phases of pulsation of hydrothermal solutions and defined into four groups from the lowest to the highest temperatures. The frequency of the homogenisation temperatures ranged from 265 to 125°C and with the most dominant from 245 to 225°C, from 225 to 205°C and from 145 to 125°C. Also, it was confirmed that hydrothermal ore-bearing solutions were defined as NaCl-type with range from 4.4 to 8.6 wt% NaCl equivalent. The latest stage salinities ranged from 3 to 12 wt% NaCl equivalent, where those from 10 to 12 wt% and from 6 to 8 wt% NaCl equivalent, prevailed. This suggests that hydrothermal solutions within analysed quartz grains were at final mineralizing phase. Density of fluid inclusions ranged from 0.7 to 0.95g/cm3. Calculated pressures and paleo-depths of mineralisation ranged from 14 to 130 bar and from 0.6 to 0.8 km.

Abstract

Electrical resistivity tomography (ERT) was used for delineating significant subsurface hydrogeological features for sustainable groundwater development in Etioro-Akoko area, Southwestern Nigeria. This study was necessitated by challenges posed on groundwater supplies from wells and boreholes in Etioro-Akoko and the neighbouring fast growing towns and villages. Field data were acquired over the area with ABEM Lund Resistivity Imaging System and were subsequently processed and inverted through RES2DINVx64 software. Results showed four distinct subsurface layers: topsoil, weathered layer, fractured bedrock and fresh bedrock (basal unit). Localised bedrock depressions occasioned by fracturing and deep weathering of less stable bedrock minerals were delineated with resistivity and thickness values ranging from 50 to 650 Ωm and 12 to ---gt--- 25 m, respectively. The localised depressions mirrored uneven bedrock topography and served as the preferential groundwater storage and hydrogeological zones in the area. The two hydrogeological zones significant for groundwater development included overburden-dependent aquifers and fractured dependent bedrock aquifers. It was, therefore, concluded that groundwater storage potential was depended on hydrogeological zones particularly at major localised bedrock depressions where fractures and groundwater recharges/discharges were evident. Wells and boreholes were proposed at bedrock depressions with thickness value not less than 12 and ---gt--- 25 m, respectively, for enhanced groundwater sustainability and quality assurance in the area.

Abstract

The Lean concept is recognisable by how fast innovations are implemented and production processes are improved. Likewise, analysis of the implementation of Lean concepts so far has shown that Lean methods and tools cannot be applied to small and medium enterprises (SMEs) in the same measure as they can be applied to large enterprises.

This paper aims to present a critical review of the implementation of Lean concepts in SMEs with the claim that Lean concept can be successfully applied in all branches of industry, provided that the Lean concept is fully understood, and it’s meaning, principles and practice. Given that SMEs have limited resources, they often face difficulties during the implementation of all Lean tools and methods.

Depending on the type of improvement in Kaizen activities, the Poka Yoke and Jidoka tools should be applied. Every improvement in the production process needs to be standardised as soon as possible so that the processes can become more continuous and efficient.

Abstract

The photovoltaic technologies have been developed year by year in different countries; however, there are some countries where this kind of energy is being born, such as the Brazilian case. In this paper, some important parameters are analysed and applied to different solar cell materials, identifying that if the fossil fuels were substituted by solar cells, it would reduce the CO2 emissions by 93.2%. In addition, it is shown that the efficiency of solar cells is not as farther as it could be thought from coal thermoelectrical plants in Brazil and the cost of energy using solar cells could be as good as these thermoelectrical plants. Finally, the potentiality of Brazilian territory to implant this technology is presented, identifying that with the use of 0.2% of the territory, the energy demand could be supplied.

Abstract

Groundwater flow of the basement terrains of the Ibarapa region was studied by carrying out pumping test and measurement of borehole inventory. The view was to identify the associated aquifer systems from the time-drawdown curves, quantify the estimable hydraulic properties and develop hypothetical models for the understanding of the groundwater flow in the area underlain by diverse crystalline bedrocks. Three aquifer types were identified namely, dual, leaky and regolith. The yield of groundwater in dual and leaky aquifers that dominated terrains underlain by amphibolite and gneisses was sustainable, but the discharge of regolith aquifers mainly associated with migmatite and granite terrains declined at late pumping stage. The transmissivities of the dual and leaky aquifers were between 2.02 and 11.65 m2/day, while those of regolith aquifers were mostly less than 1.00 m2/day. The average aquifer transmissivities in m2/day by bedrocks were: 6.85, 2.57, 0.76 and 1.72, correspondingly. The inter-relationships between transmissivities and groundwater discharge showed diverse aquifer representations, from sustainable high-yielding to unsustainable low-yielding types. Conscientious effort is, therefore, required for well construction in the area.

Abstract

The aeromagnetic data of Idogo, Southwestern Nigeria, have been used to study the lithology and to determine the magnetic source parameters within Idogo and its environs. Idogo lies between latitudes 6°30′N and 7°00′N and between longitudes 2°30′E and 3°00′E. The magnetic anomaly map, the regional geology, the analytic signal and the local wavenumber were used to identify the nature and depth of the magnetic sources in the region. Data enhancement was carried out to delineate the residual features relative to the strong regional gradients and intense anomalies due to the basin features. The estimated basement depth using the horizontal gradient method revealed depths ranging between 0.55 km and 2.49 km, while the analytic signal amplitude and local wavenumber methods estimated depth to the magnetic sources to range from 0.57 km to 4.22 km and 0.96 km to 2.43 km, respectively. Depth computations suggested the presence of both shallow and deep sources. The total magnetic intensity values ranged from 3.1 nT to 108.3 nT. The area shows magnetic closures of various sizes in different parts of the area trending West, with prominence at the centre and distributed East–West.

Abstract

The Durmitor flysch complex represents a specific formation both in lithological and engineering geological sense. In the engineering geological sense this lithological formation is characterized by anisotropic and heterogeneous geotechnical properties, which depend on the dominant members within each individual package, as well as their spatial position.The Durmitor flysch complex consists of five superposition bed packages, which are mutually substantially different in their lithological, hydrogeological and geotechnical properties. For the first time in geological literature, this paper distinguishes five types of terrain construction within the Durmitor flysch complex. Contemporary geodynamic processes and their character within the flysch formation are defined. Particular emphasis is put on landslides, which represent a contemporary geodynamic phenomenon with certain specificities.

Abstract

The study of the nature of distribution of natural radioelements in Ilesha and its environs with its geological structure has been studied using aeroradiometric data. Aeromagnetic data have also been subjected to three automated gradient techniques to delineate the sub-surface structure of the study area. From the study, it can be found that maximum values of “eU” (ppm) and “eTh” (ppm) fall within the branded gneiss, whereas the maximum value of K (%) falls within porphyritic granite regions. eTh had the highest radioactive content. The environmental dose rate of Ilesha was between 0.1817 and 3.9296 msv/yr. Although there were extreme values, but the mean dose rate was 0.522 ± 0.310 msv/yr (within acceptable safe limit of 1.0 msv/yr). eU/K, eU/eTh and eTh/K ratios were analysed for enrichment or depletion of radioisotopes. eU/eTh >1 showed uranium depletion, while eTh >2 showed eTh enrichment. The magnetic intensity values ranged from -79.41 to 140.93 nT. The horizontal gradient method (HGM) and analytic signal amplitude (ASA) revealed that depth to magnetic sources ranged from 0.478 to 4.112 km and 0.348 to 2.551 km, respectively, whereas local wavenumber (LWN) depth ranged from 0.478 to 5.48 km, which overestimated those compared using HGM and ASA functions. The apparent susceptibility ranged from -0.00325 to 0.00323 SI, showing that ferromagnetic and diamagnetic mineral ranges control apparent susceptibility in Ilesha.