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AHEAD OF PRINT

Volume 67 (2020): Edition 4 (December 2020)

Volume 67 (2020): Edition 3 (September 2020)

Volume 67 (2020): Edition 2 (June 2020)

Volume 67 (2020): Edition 1 (March 2020)

Volume 66 (2019): Edition 4 (December 2019)

Volume 66 (2019): Edition 3 (December 2019)

Volume 66 (2019): Edition 2 (June 2019)

Volume 66 (2019): Edition 1 (March 2019)

Volume 65 (2018): Edition 4 (December 2018)

Volume 65 (2018): Edition 3 (September 2018)

Volume 65 (2018): Edition 2 (September 2018)

Volume 65 (2018): Edition 1 (March 2018)

Volume 64 (2017): Edition 4 (December 2017)

Volume 64 (2017): Edition 3 (September 2017)

Volume 64 (2017): Edition 2 (July 2017)

Volume 64 (2017): Edition 1 (March 2017)

Volume 63 (2016): Edition 4 (December 2016)

Volume 63 (2016): Edition 3 (September 2016)

Volume 63 (2016): Edition 2 (July 2016)

Volume 63 (2016): Edition 1 (May 2016)

Détails du magazine
Format
Magazine
eISSN
1854-7400
Première publication
30 Mar 2016
Période de publication
4 fois par an
Langues
Anglais

Chercher

AHEAD OF PRINT

Détails du magazine
Format
Magazine
eISSN
1854-7400
Première publication
30 Mar 2016
Période de publication
4 fois par an
Langues
Anglais

Chercher

10 Articles
access type Accès libre

Physico-Chemical Trends in the Sediments of Agbede Wetlands, Nigeria

Publié en ligne: 23 Jun 2017
Pages: -

Résumé

Abstract

This study assessed the physico-chemical status of sed­iments in the Agbede Wetlands with the aim to create a reference archive for the Edo North catchment and to further identify the characteristics mostly influenced by the natural and anthropogenic activities going on at the watershed. Nutrients, zinc, nickel and lead were identified to be mostly of anthropogenic origin, while alkali metals and alkaline earth metals were from both anthropogenic and natural sources. The clustering of stations 1 and 4 indicates that the sediment quality in the lentic systems was not completely excluded from the lotic system, suggesting that principal component analysis (PCA) and cluster analysis (CA) techniques are invaluable tools for identifying factors influencing the sediment quality. The mean values of the particle size distribution were in the following order across the ecosystems: sand (61.86-80.53%) > silt (9.75-30.34%) > clay (7.83-13.89%). The contamination of the water bodies was primarily derived from agricultural run-offs and through geochemical weathering of the top soils. Therefore, our analysis indicates that the concentra­tions of cations, anions and nutrients in the sediments of the lotic and lentic ecosystems in Agbede Wetlands are not at an alarming level.

Mots clés

  • sediment
  • physico-chemical character­istics
  • pond
  • stream
  • principal component analysis
  • watershed
access type Accès libre

Determining the Enthalpy of an Fe-Ni Alloy at Various Temperatures Using the ‘STA’ PT 1600 Equipment

Publié en ligne: 21 Mar 2022
Pages: -

Résumé

Abstract

V tem raziskovalnem prispevku smo določili entalpijo zlitine Fe-Ni z uporabo naprave ‘STA’ laboratorija Univerze v Mitrovici ‘Isa Boletini’, Oddeleka za materiale in metalurgijo. Vzorec za analizo je bil odvzet v tovarni ferroniklja, medtem ko je priprava vzorca za analizo na napravi ‘STA PT 1600’ potekala v laboratoriju Univerze v Mitrovici ‘Isa Boletini’.

Analiziran vzorec zlitine Fe-Ni v obliki granule je bil velikosti 2–4 cm. Vseboval je 22,55 % Ni, 76,51 % Fe in majhne količine drugih elementov [1, 2]. Pri analizi zlitine Fe-Ni smo dobili tri vrednosti entalpije glede na pogoje analize z maksimalno temperaturo 800 °C in minimalno temperaturo 600 °C, pri čemer je bila zlitina izpostavljena obema temperaturama posebej po 45 minut.

Iz dobljenih rezultatov smo zbrali negativne vrednosti entalpije v treh preučenih scenarijih in eksotermnem procesu, kjer je ΔH<0 [3]. Entalpija se zmanjšuje, ko sistem sprošča toploto z naraščanjem temperature [4].

Mots clés

  • STA
  • alloy
  • Fe-Ni
  • enthalpy
  • exothermic process

Ključnebesede

  • STA
  • zlitina
  • Fe-Ni
  • entalpija
  • eksotermni proces
access type Accès libre

An analysis of coal consumption, CO2 emissions and economic growth in Slovenia

Publié en ligne: 30 Dec 2021
Pages: -

Résumé

Mots clés

  • coal
  • emissions
  • correlation
  • forecasting

Ključne besede

  • premog
  • emisije
  • povezanost
  • napovedovanje
access type Accès libre

Field Observations, Petrography, and Microstructures of Granite from Abeokuta Southwestern Nigeria

Publié en ligne: 04 Feb 2022
Pages: -

Résumé

Mots clés

  • megacrysts
  • microperthitic
  • K-feldspar
  • zoning
  • porphyroblasts

Ključnebesede

  • vtrošniki
  • mikropertit
  • kalijev glinenec
  • conarna rast
  • porfiroblasti
access type Accès libre

Copper tailings reprocessing

Publié en ligne: 10 Jan 2022
Pages: -

Résumé

Mots clés

  • tailings reprocessing
  • multi-gravity separator
  • flotation
  • copper

Ključne besede

  • reprocesiranje jalovišč
  • multi-gravitacijski separator
  • flotacija
  • baker
access type Accès libre

Regression methods for evaluation of the underwater noise levels in the Slovenian Sea

Publié en ligne: 11 Dec 2021
Pages: -

Résumé

Abstract

Anthropogenic underwater noise pollution of seas and oceans caused by shipping can have negative effects on marine animals. The aim of this study was to evaluate quantitatively how much the underwater noise levels in the Slovenian Sea were influenced by anthropogenic pressures and meteorological parameters in the period from 2015 until 2018. For this purpose, correlation method and least squares multiple linear regression analysis were used. The results of this study show that the correlation of underwater noise levels with the dredging activity is significant but low, while correlation with the ship densities is insignificant, which could be due to reduced sound wave propagation in the shallow sea levels. Correlation of the underwater noise levels with the wind speed was significant but low to medium, which could be explained by the breaking waves generated by the wind that produced sound.

Mots clés

  • Underwater noise
  • correlation
  • multiple linear regression
  • anthropogenic pressures
  • meteorological parameters

Ključne besede

  • Podvodni hrup
  • korelacija
  • multipla linearna regresija
  • antropogeni pritiski
  • meteorološki parametri
access type Accès libre

Valuation of Rubber Waste and Dune Sand: Mortar for Construction and Environmental Protection

Publié en ligne: 23 Feb 2022
Pages: -

Résumé

Abstract

The main objective of this study is the recovery of dune sands and rubber waste (powders). The latter constitutes a potential source of several environmental and economic problems.

The objective of this present work is to examine the ability to use dune sand for the preparation of mortars with sufficient physico-mechanical properties to allow them to be used in various building construction applications. The formulation of the mixtures is based on replacing dune sand with powders, at different weight contents: 10 %, 20 %, and 30 %. The quantity of cement is set at 450 g. The results obtained show in the first place that the particle size of the mixture tends to be spread out with a remarkable increase in the fineness modulus, and in the second place the density of the mixture decreases by 6.5 % (for the apparent) and by 10 % (for the absolute), which means the calculation of loads for the resulting mortar must decrease. Porosity has decreased to 20 % and absorption has increased to 30%. The strengths have decreased over 40 % for compressive strength and over 30 % for tensile strength, with an improvement in the relationship between the two strengths.

Mots clés

  • Mortar
  • dune sand
  • rubber
  • porosity
  • absorption
  • strength
access type Accès libre

Returning Electrostatic Precipitators to the Fe-Ni Production Process

Publié en ligne: 21 Mar 2022
Pages: -

Résumé

Abstract

Proces žganja Fe-Ni vložka v rotacijskih pečeh proizvede velike količine procesnega prahu, ki ga rotacijske peči očistijo z uporabo elektrostatičnih filtrov [1].

Ena peč vsebuje dve vrsti elektrostatičnih filtrov kot varnostni mehanizem [1]. V odseku kjer so name-ščene elektrode se ob prehodu elektrike ustvarjajo električna polja in prah ionizira.

Pravi čas je skrbno usklajen. S pomočjo kladiv, ki te elektrode udarjajo in občasno stresajo, nastanejo znatne količine prahu. Te se nato zberejo v polžjem transporterju za prah, ki se nato reciklira in vrne v proizvodni proces. Poleg tega se iz plinske komore pridobi manjša količina prahu, ki se vrne v proces brez vstopa v proces čiščenja v elektrofiltrih, pri čemer je razlika med obema vrstama prahu v granulaciji [1].

Raziskavo smo izvedli v letih 2017–2020, pri čemer smo izračunali komponente procesa rotacijske peči in predstavili linearno enačbo kot rezultat razmerja žganega in elektrofiltrskega prahu.

Mots clés

  • dust
  • calcine
  • electro filter
  • adhesion
  • rotary kiln

Ključnebesede

  • prah
  • žganje
  • elektrofilter
  • adhezija
  • rotacijska peč
access type Accès libre

Lateral squeezing effects on cement-slag-bentonite slurry wall performance

Publié en ligne: 02 Mar 2022
Pages: -

Résumé

Abstract

Cement-slag-bentonite slurry walls are self-hardening structures, and they are mainly used to retard contamination transport into the groundwater stream. Whilst permeability of a mixture is an initial criterion in slurry wall design and material selection, long-term performance is mainly influenced by curing ages and stress-state caused by adjacent soil. In this study, the steady-state of effective stresses at 7 days and 28 days of curing age is predicted. The effect of the modulus of horizontal subgrade reaction, interface friction, and transition of the earth pressure from at-rest to the active condition was applied to develop the model. Unlike the quantities that the geostatic model presented, this method gives a slight decrease of stresses after a certain depth, and the trend is in good agreement with trends provided by previous studies. Furthermore, the predicted stresses are then applied to estimate the permeability of the wall at each depth and compare it with those obtained in the laboratory. Finally, predicted effective stresses stay lower than geostatic stress, and the slurry wall consolidation along with the sidewalls’ lateral squeezing leads to keeping the stress state under control.

Mots clés

  • cement-slag-bentonite
  • compressibility
  • lateral squeezing
  • permeability
  • slurry wall
access type Accès libre

Hydrocarbon Potential and Biomarker Studies of EE-1 Well, Offshore Eastern Dahomey Basin, SW Nigeria

Publié en ligne: 18 Mar 2022
Pages: -

Résumé

Abstract

The hydrocarbon potential, organic source input, and paleodepositional environment of subsurface sediments from EE-1 well, offshore Eastern Dahomey Basin, were assessed using Rock-Eval pyrolysis and biomarker geochemistry. The total organic carbon (TOC) and soluble organic matter (SOM) in the sediments ranged from 0.96wt% to 8.92wt% and 676.12 ppm to 2883.85 ppm, respectively, indicating adequate to excellent organic richness. The pseudo-Van Krevelen plot classified the sediments as types II and III kerogen, which have the potential to generate both oil and gas. The Tmax and production index (PI) ranged from 422°C to 431°C (average, 426°C) and 0.03 to 0.24, respectively, suggesting low thermal maturity. The presence of C27–C29 steranes, oleanane, and hopane/sterane ratio (1.53/16.11), indicated organic matter from mixed sources with more terrigenous input. Cross plots of Pr/nC17 against Ph/nC18, C35/C31 – C35 homohopane index (0.05 – 0.17) and other related biomarker ratios such as C21/C23 trycyclic terpane ratio (0.33 – 0.82) signified that the sediments were deposited in mixed marine/terrigenous environment under oxic – suboxic conditions. This study has demonstrated that sediments had adequate organic matter with the potential to generate both oil and gas at appropriate thermal maturity.

Mots clés

  • hydrocarbon potential
  • biomarker
  • Dahomey Basin
10 Articles
access type Accès libre

Physico-Chemical Trends in the Sediments of Agbede Wetlands, Nigeria

Publié en ligne: 23 Jun 2017
Pages: -

Résumé

Abstract

This study assessed the physico-chemical status of sed­iments in the Agbede Wetlands with the aim to create a reference archive for the Edo North catchment and to further identify the characteristics mostly influenced by the natural and anthropogenic activities going on at the watershed. Nutrients, zinc, nickel and lead were identified to be mostly of anthropogenic origin, while alkali metals and alkaline earth metals were from both anthropogenic and natural sources. The clustering of stations 1 and 4 indicates that the sediment quality in the lentic systems was not completely excluded from the lotic system, suggesting that principal component analysis (PCA) and cluster analysis (CA) techniques are invaluable tools for identifying factors influencing the sediment quality. The mean values of the particle size distribution were in the following order across the ecosystems: sand (61.86-80.53%) > silt (9.75-30.34%) > clay (7.83-13.89%). The contamination of the water bodies was primarily derived from agricultural run-offs and through geochemical weathering of the top soils. Therefore, our analysis indicates that the concentra­tions of cations, anions and nutrients in the sediments of the lotic and lentic ecosystems in Agbede Wetlands are not at an alarming level.

Mots clés

  • sediment
  • physico-chemical character­istics
  • pond
  • stream
  • principal component analysis
  • watershed
access type Accès libre

Determining the Enthalpy of an Fe-Ni Alloy at Various Temperatures Using the ‘STA’ PT 1600 Equipment

Publié en ligne: 21 Mar 2022
Pages: -

Résumé

Abstract

V tem raziskovalnem prispevku smo določili entalpijo zlitine Fe-Ni z uporabo naprave ‘STA’ laboratorija Univerze v Mitrovici ‘Isa Boletini’, Oddeleka za materiale in metalurgijo. Vzorec za analizo je bil odvzet v tovarni ferroniklja, medtem ko je priprava vzorca za analizo na napravi ‘STA PT 1600’ potekala v laboratoriju Univerze v Mitrovici ‘Isa Boletini’.

Analiziran vzorec zlitine Fe-Ni v obliki granule je bil velikosti 2–4 cm. Vseboval je 22,55 % Ni, 76,51 % Fe in majhne količine drugih elementov [1, 2]. Pri analizi zlitine Fe-Ni smo dobili tri vrednosti entalpije glede na pogoje analize z maksimalno temperaturo 800 °C in minimalno temperaturo 600 °C, pri čemer je bila zlitina izpostavljena obema temperaturama posebej po 45 minut.

Iz dobljenih rezultatov smo zbrali negativne vrednosti entalpije v treh preučenih scenarijih in eksotermnem procesu, kjer je ΔH<0 [3]. Entalpija se zmanjšuje, ko sistem sprošča toploto z naraščanjem temperature [4].

Mots clés

  • STA
  • alloy
  • Fe-Ni
  • enthalpy
  • exothermic process

Ključnebesede

  • STA
  • zlitina
  • Fe-Ni
  • entalpija
  • eksotermni proces
access type Accès libre

An analysis of coal consumption, CO2 emissions and economic growth in Slovenia

Publié en ligne: 30 Dec 2021
Pages: -

Résumé

Mots clés

  • coal
  • emissions
  • correlation
  • forecasting

Ključne besede

  • premog
  • emisije
  • povezanost
  • napovedovanje
access type Accès libre

Field Observations, Petrography, and Microstructures of Granite from Abeokuta Southwestern Nigeria

Publié en ligne: 04 Feb 2022
Pages: -

Résumé

Mots clés

  • megacrysts
  • microperthitic
  • K-feldspar
  • zoning
  • porphyroblasts

Ključnebesede

  • vtrošniki
  • mikropertit
  • kalijev glinenec
  • conarna rast
  • porfiroblasti
access type Accès libre

Copper tailings reprocessing

Publié en ligne: 10 Jan 2022
Pages: -

Résumé

Mots clés

  • tailings reprocessing
  • multi-gravity separator
  • flotation
  • copper

Ključne besede

  • reprocesiranje jalovišč
  • multi-gravitacijski separator
  • flotacija
  • baker
access type Accès libre

Regression methods for evaluation of the underwater noise levels in the Slovenian Sea

Publié en ligne: 11 Dec 2021
Pages: -

Résumé

Abstract

Anthropogenic underwater noise pollution of seas and oceans caused by shipping can have negative effects on marine animals. The aim of this study was to evaluate quantitatively how much the underwater noise levels in the Slovenian Sea were influenced by anthropogenic pressures and meteorological parameters in the period from 2015 until 2018. For this purpose, correlation method and least squares multiple linear regression analysis were used. The results of this study show that the correlation of underwater noise levels with the dredging activity is significant but low, while correlation with the ship densities is insignificant, which could be due to reduced sound wave propagation in the shallow sea levels. Correlation of the underwater noise levels with the wind speed was significant but low to medium, which could be explained by the breaking waves generated by the wind that produced sound.

Mots clés

  • Underwater noise
  • correlation
  • multiple linear regression
  • anthropogenic pressures
  • meteorological parameters

Ključne besede

  • Podvodni hrup
  • korelacija
  • multipla linearna regresija
  • antropogeni pritiski
  • meteorološki parametri
access type Accès libre

Valuation of Rubber Waste and Dune Sand: Mortar for Construction and Environmental Protection

Publié en ligne: 23 Feb 2022
Pages: -

Résumé

Abstract

The main objective of this study is the recovery of dune sands and rubber waste (powders). The latter constitutes a potential source of several environmental and economic problems.

The objective of this present work is to examine the ability to use dune sand for the preparation of mortars with sufficient physico-mechanical properties to allow them to be used in various building construction applications. The formulation of the mixtures is based on replacing dune sand with powders, at different weight contents: 10 %, 20 %, and 30 %. The quantity of cement is set at 450 g. The results obtained show in the first place that the particle size of the mixture tends to be spread out with a remarkable increase in the fineness modulus, and in the second place the density of the mixture decreases by 6.5 % (for the apparent) and by 10 % (for the absolute), which means the calculation of loads for the resulting mortar must decrease. Porosity has decreased to 20 % and absorption has increased to 30%. The strengths have decreased over 40 % for compressive strength and over 30 % for tensile strength, with an improvement in the relationship between the two strengths.

Mots clés

  • Mortar
  • dune sand
  • rubber
  • porosity
  • absorption
  • strength
access type Accès libre

Returning Electrostatic Precipitators to the Fe-Ni Production Process

Publié en ligne: 21 Mar 2022
Pages: -

Résumé

Abstract

Proces žganja Fe-Ni vložka v rotacijskih pečeh proizvede velike količine procesnega prahu, ki ga rotacijske peči očistijo z uporabo elektrostatičnih filtrov [1].

Ena peč vsebuje dve vrsti elektrostatičnih filtrov kot varnostni mehanizem [1]. V odseku kjer so name-ščene elektrode se ob prehodu elektrike ustvarjajo električna polja in prah ionizira.

Pravi čas je skrbno usklajen. S pomočjo kladiv, ki te elektrode udarjajo in občasno stresajo, nastanejo znatne količine prahu. Te se nato zberejo v polžjem transporterju za prah, ki se nato reciklira in vrne v proizvodni proces. Poleg tega se iz plinske komore pridobi manjša količina prahu, ki se vrne v proces brez vstopa v proces čiščenja v elektrofiltrih, pri čemer je razlika med obema vrstama prahu v granulaciji [1].

Raziskavo smo izvedli v letih 2017–2020, pri čemer smo izračunali komponente procesa rotacijske peči in predstavili linearno enačbo kot rezultat razmerja žganega in elektrofiltrskega prahu.

Mots clés

  • dust
  • calcine
  • electro filter
  • adhesion
  • rotary kiln

Ključnebesede

  • prah
  • žganje
  • elektrofilter
  • adhezija
  • rotacijska peč
access type Accès libre

Lateral squeezing effects on cement-slag-bentonite slurry wall performance

Publié en ligne: 02 Mar 2022
Pages: -

Résumé

Abstract

Cement-slag-bentonite slurry walls are self-hardening structures, and they are mainly used to retard contamination transport into the groundwater stream. Whilst permeability of a mixture is an initial criterion in slurry wall design and material selection, long-term performance is mainly influenced by curing ages and stress-state caused by adjacent soil. In this study, the steady-state of effective stresses at 7 days and 28 days of curing age is predicted. The effect of the modulus of horizontal subgrade reaction, interface friction, and transition of the earth pressure from at-rest to the active condition was applied to develop the model. Unlike the quantities that the geostatic model presented, this method gives a slight decrease of stresses after a certain depth, and the trend is in good agreement with trends provided by previous studies. Furthermore, the predicted stresses are then applied to estimate the permeability of the wall at each depth and compare it with those obtained in the laboratory. Finally, predicted effective stresses stay lower than geostatic stress, and the slurry wall consolidation along with the sidewalls’ lateral squeezing leads to keeping the stress state under control.

Mots clés

  • cement-slag-bentonite
  • compressibility
  • lateral squeezing
  • permeability
  • slurry wall
access type Accès libre

Hydrocarbon Potential and Biomarker Studies of EE-1 Well, Offshore Eastern Dahomey Basin, SW Nigeria

Publié en ligne: 18 Mar 2022
Pages: -

Résumé

Abstract

The hydrocarbon potential, organic source input, and paleodepositional environment of subsurface sediments from EE-1 well, offshore Eastern Dahomey Basin, were assessed using Rock-Eval pyrolysis and biomarker geochemistry. The total organic carbon (TOC) and soluble organic matter (SOM) in the sediments ranged from 0.96wt% to 8.92wt% and 676.12 ppm to 2883.85 ppm, respectively, indicating adequate to excellent organic richness. The pseudo-Van Krevelen plot classified the sediments as types II and III kerogen, which have the potential to generate both oil and gas. The Tmax and production index (PI) ranged from 422°C to 431°C (average, 426°C) and 0.03 to 0.24, respectively, suggesting low thermal maturity. The presence of C27–C29 steranes, oleanane, and hopane/sterane ratio (1.53/16.11), indicated organic matter from mixed sources with more terrigenous input. Cross plots of Pr/nC17 against Ph/nC18, C35/C31 – C35 homohopane index (0.05 – 0.17) and other related biomarker ratios such as C21/C23 trycyclic terpane ratio (0.33 – 0.82) signified that the sediments were deposited in mixed marine/terrigenous environment under oxic – suboxic conditions. This study has demonstrated that sediments had adequate organic matter with the potential to generate both oil and gas at appropriate thermal maturity.

Mots clés

  • hydrocarbon potential
  • biomarker
  • Dahomey Basin

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