Littérature scientifique sur le sujet « Carbone, Zenica »

According to the World Health Organization (WHO), air pollution is the largest single environmental risk to public health. According to the latest estimate of this organization, 9 out of 10 people on the planet breathe polluted air. The development of industry in the relatively small Zenica valley reflected on air quality in the city of Zenica. The problem of high air pollution due to emissions of pollutants from industrial sources, traffic, and individual furnaces, burning of environmentally unsuitable fuels containing high sulfur and ash content has been present in the City of Zenica for a long time. In addition, the low wind speed during the year, which ranges up to 1.5 m/s, with unfavorable temperature inversions, causes the concentrations of pollutants in the air to reach alarmingly high values in a short period. In the wider area of the City of Zenica, air quality has been monitored since 1978 in the network of stationary stations. The paper presents results of air quality monitoring which are analyzed at the Institute Kemal Kapetanovic in Zenica for the sampling period from 01.01.2019. to 31.12.2020. years. Air quality monitoring included sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), and particulate matter (PM10) at three locations in the wider area of the city of Zenica. In the wider area of the City of Zenica, air quality has been monitored since 1978 in the network of stationary stations. The paper presents the processed results of air quality monitoring which are analyzed at the Institute Kemal Kapetanovic in Zenica for the sampling period from 01.01.2019 to 31.12.2020. The measured concentrations of pollutants in the ambient air indicate that during the heating season, i.e. the winter months, the air quality in the urban and suburban areas of the city of Zenica is very poor. The data show that the highest hourly concentration of sulfur dioxide was recorded in December at the measuring station AMS Tetovo in the amount of 1100.59 µg/m3, which is located in the settlement next to the metallurgical facilities of the industrial zone Zenica.

Soil organic carbon (SOC), nitrogen (N), and phosphorus (P) are three essential soil nutrients for plant growth, and their stoichiometric ratios are already important indices of elemental balance and the soil fertility status in soil ecosystems. The evolution mechanism of the SOC, Total Nitrogen (TN), Total Phosphorus (TP), and stoichiometry following the “conversion of cropland to forest program” (CCFP) in southwest China is not yet clear. Seven different CCFP restoration models, including Zenia insignis (RD), Toona sinensis (XC), Castanea mollissima (BL), Citrus reticulate (GJ), Zenia insignis and Guimu-1 elephant grass (RG), Guimu-1 elephant grass (GM), and abandoned cropland (LH), were chosen to explore changes in the concentration and stoichiometry of the SOC, TN, and TP, and their recovery times, at a depth of 0–100 cm. The results indicate that the SOC and TN concentrations in different restoration models all increased with restoration years in the topsoil, whereas the soil TP concentration remained relatively stable. The soil C:N and C:P ratios increased with increasing restoration years in the topsoil, whereas the N: P ratio was relatively stable over time. After ten years of reforestation, the SOC and TN concentrations decreased as the soil layer increased. The effects of the restoration model on the C: N ratios were greater in shallow soils. Our results suggest a complex reaction of SOC, soil TN, and soil TP concentrations and stoichiometry to the vegetation restoration mode, particularly in the topsoil. This research further improves the understanding of SOC, N, and P interactions and restricted nutrition, and provides relevant theoretical support for vegetation restoration in the southwest karst region.

Abstract. Snow photochemical processes drive production of chemical trace gases, including nitrogen oxides (NO and NO2), and HOx radicals in snowpacks which are then released to the lower atmosphere. Coupled atmosphere–snow modelling on global scales requires simple parameterisations of actinic flux in snow to reduce computational cost. The disagreement between a physical radiative transfer method and a method based upon the e-folding depth of light-in snow is evaluated. In particular for the photolysis of the nitrate anion (NO3-), the nitrite anion (NO2-) and hydrogen peroxide (H2O2) within snow and photolysis of gas-phase nitrogen dioxide (NO2) within the snowpack interstitial air are considered. The emission flux from the snowpack is estimated as the depth-integrated photolysis rate, v, calculated (a) explicitly with a physical radiative transfer model (TUV), vTUV and (b) with a simple parameterisation based on e-folding depth, vze. The evaluation is based upon the deviation of the ratio of depth-integrated photolysis rate determined by the two methods,vTUV/vze, from unity. The disagreement in depth-integrated photolysis rate between the RT model and e-folding depth parameterisation depends primarily on the photolysis action spectrum of chemical species, solar zenith angle and optical properties of the snowpack, (scattering cross-section and a weak dependence on light absorbing impurity (black carbon) and density). For photolysis of NO2, the NO2- anion, the NO3- anion and H2O2 the ratio vTUV/vze varies within the range of 0.82–1.35, 0.88–1.28 and 0.92–1.27 respectively. The e-folding depth parameterisation underestimates for small solar zenith angles and overestimates at solar zenith angles around 60°. A simple algorithm has been developed to improve the parameterisation which reduced the ratio vTUV/vze to 0.97–1.02, 0.99–1.02 and 0.99–1.03 for photolysis of NO2, the NO2- anion, the NO3- anion and H2O2 respectively. The e-folding depth parameterisation may give acceptable results for the photolysis of the NO3- anion and H2O2 in cold polar snow with large solar zenith angles, but can be improved by a correction based on solar zenith angle.

Abstract. An important current problem in micrometeorology is the characterization of turbulence in the roughness sublayer (RSL), where most of the measurements above tall forests are made. There, scalar turbulent fluctuations display significant departures from the predictions of Monin–Obukhov similarity theory (MOST). In this work, we analyze turbulence data of virtual temperature, carbon dioxide, and water vapor in the RSL above an Amazonian forest (with a canopy height of 40 m), measured at 39.4 and 81.6 m above the ground under unstable conditions. We found that dimensionless statistics related to the rate of dissipation of turbulence kinetic energy (TKE) and the scalar variance display significant departures from MOST as expected, whereas the vertical velocity variance follows MOST much more closely. Much better agreement between the dimensionless statistics with the Obukhov similarity variable, however, was found for the subset of measurements made at a low zenith angle Z, in the range 0° < |Z| < 20°. We conjecture that this improvement is due to the relationship between sunlight incidence and the “activation–deactivation” of scalar sinks and sources vertically distributed in the forest. Finally, we evaluated the relaxation coefficient of relaxed eddy accumulation: it is also affected by zenith angle, with considerable improvement in the range 0° < |Z| < 20°, and its values fall within the range reported in the literature for the unstable surface layer. In general, our results indicate the possibility of better stability-derived flux estimates for low zenith angle ranges.

Purpose: To investigate the amount of gas released from Zenith thoracic stent-grafts using standard saline flushing vs the carbon dioxide flushing technique. Methods: In an experimental bench setting, 20 thoracic stent-grafts were separated into 2 groups of 10 endografts. One group of grafts was flushed with 60 mL saline and the other group was flushed with carbon dioxide for 5 minutes followed by 60 mL saline. All grafts were deployed into a water-filled container with a curved plastic pipe; the deployment was recorded and released gas was measured using a calibrated setup. Results: Gas was released from all grafts in both study groups during endograft deployment. The average amount of released gas per graft was significantly lower in the study group with carbon dioxide flushing (0.79 vs 0.51 mL, p=0.005). Conclusion: Thoracic endografts release significant amounts of air during deployment if flushed according to the instructions for use. Application of carbon dioxide for the flushing of thoracic stent-grafts prior to standard saline flush significantly reduces the amount of gas released during deployment. The additional use of carbon dioxide should be considered as a standard flush technique for aortic stent-grafts, especially in those implanted in proximal aortic segments, to reduce the risk of air embolism and stroke.

Abstract. Snow photochemical processes drive production of chemical trace gases in snowpacks, including nitrogen oxides (NOx = NO + NO2) and hydrogen oxide radical (HOx = OH + HO2), which are then released to the lower atmosphere. Coupled atmosphere–snow modelling of theses processes on global scales requires simple parameterisations of actinic flux in snow to reduce computational cost. The disagreement between a physical radiative-transfer (RT) method and a parameterisation based upon the e-folding depth of actinic flux in snow is evaluated. In particular, the photolysis of the nitrate anion (NO3-), the nitrite anion (NO2-) and hydrogen peroxide (H2O2) in snow and nitrogen dioxide (NO2) in the snowpack interstitial air are considered. The emission flux from the snowpack is estimated as the product of the depth-integrated photolysis rate coefficient, v, and the concentration of photolysis precursors in the snow. The depth-integrated photolysis rate coefficient is calculated (a) explicitly with an RT model (TUV), vTUV, and (b) with a simple parameterisation based on e-folding depth, vze. The metric for the evaluation is based upon the deviation of the ratio of the depth-integrated photolysis rate coefficient determined by the two methods, vTUV/vze, from unity. The ratio depends primarily on the position of the peak in the photolysis action spectrum of chemical species, solar zenith angle and physical properties of the snowpack, i.e. strong dependence on the light-scattering cross section and the mass ratio of light-absorbing impurity (i.e. black carbon and HULIS) with a weak dependence on density. For the photolysis of NO2, the NO2- anion, the NO3- anion and H2O2 the ratio vTUV/vze varies within the range of 0.82–1.35, 0.88–1.28, 0.93–1.27 and 0.91–1.28 respectively. The e-folding depth parameterisation underestimates for small solar zenith angles and overestimates at solar zenith angles around 60° compared to the RT method. A simple algorithm has been developed to improve the parameterisation which reduces the ratio vTUV/vze to 0.97–1.02, 0.99–1.02, 0.99–1.03 and 0.98–1.06 for photolysis of NO2, the NO2- anion, the NO3- anion and H2O2 respectively. The e-folding depth parameterisation may give acceptable results for the photolysis of the NO3- anion and H2O2 in cold polar snow with large solar zenith angles, but it can be improved by a correction based on solar zenith angle and for cloudy skies.

Background: The study evaluates a novel technique using oxygen measurements to indirectly evaluate the behavior of carbon dioxide (CO2) in the residual gas released by thoracic stent-grafts and to better understand the mechanism of the CO2 flushing technique. Methods: Ten Zenith TX2 ProForm thoracic stent-grafts (ZDEG-PT-34-199-PF, Cook Medical, Bjæverskov, Denmark) were equally divided into 2 groups (Group A and B). Group A was flushed with 60 ml of 0.9% saline. Group B was flushed with 100% carbon dioxide gas followed by 60 ml of 0.9% saline. The stent-grafts were deployed into a plastic tube that was placed and fixated to the bottom of a translucent container filled with water to collect the residual air released by the stent-grafts. Oxygen (O2) concentration and gas volume were measured in the released gas. Results: The oxygen concentration was significant (p<0.001) lower after additional carbon dioxide flush compared to standard flush (18.5% vs 19.6%). Furthermore, the absolute oxygen volume was significantly lower after additional carbon dioxide flush than without (0.18 ml vs 0.32 ml, p=0.041). The total amount of released gas appeared lower with carbon dioxide flush than without (0.98 ml vs 1.65, P=0.058). Conclusions: CO2 absorption into saline and replacement of room air by CO2 inside the stent-graft may lead to a reduction of released gas during stent-graft deployment in an experimental setting.

With three imaging grating spectrometers, the Orbiting Carbon Observatory-2 (OCO-2) measures high spectral resolution spectra ( λ / Δ λ ≈ 19,000) of reflected solar radiation within the molecular oxygen (O 2 ) A-band at 0.765 μ m and two carbon dioxide (CO 2 ) bands at 1.61 and 2.06 μ m. OCO-2 uses onboard lamps with a reflective diffuser, solar observations through a transmissive diffuser, lunar measurements, and surface targets for radiometric calibration and validation. Separating calibrator aging from instrument degradation poses a challenge to OCO-2. Here we present a methodology for trending the OCO-2 Build 8R radiometric calibration using OCO-2 nadir observations over eight desert sites and nearly simultaneous observations from Moderate Resolution Imaging Spectroradiometer (MODIS) with sensor viewing zenith angles of 15 ± 0.5 ∘ . For the O 2 A-band, this methodology is able to quantify a drift of −0.8 ± 0.1% per year and capture a small error in correcting the aging of the solar calibrator. For the other two OCO-2 bands, no measurable changes were seen, indicating less than 0.1% and less than 0.3% per year drift in the radiometric calibration of Band 2 and Band 3, respectively.

Abstract. We present a sensitivity study of the surface mass balance (SMB) of the Greenland Ice Sheet, as modeled using a regional atmospheric climate model, to various parameter settings in the albedo parameterization. The snow albedo parameterization uses grain size as a prognostic variable and further depends on cloud cover, solar zenith angle and black carbon concentration. For the control experiment the overestimation of absorbed shortwave radiation (+6 %) at the K-transect (West Greenland) for the period 2004–2009 is considerably reduced compared to the previous density-dependent albedo parameterization (+22 %). To simulate realistic snow albedo values, a small concentration of black carbon is needed. A background ice albedo field derived from MODIS imagery improves the agreement between the modeled and observed SMB gradient along the K-transect. The effect of enhanced retention and refreezing is a decrease of the albedo due to an increase in snow grain size. As a secondary effect of refreezing the snowpack is heated, enhancing melt and further lowering the albedo. Especially in a warmer climate this process is important, since it reduces the refreezing potential of the firn layer covering the Greenland Ice Sheet.

The energy spectra of particle arrive the ground is a significant observable in the analysis of extensive air showers (EAS). The energy distribution at ground is studied for (12C,56Fe, p, and 28Si ) primary particles with high primary energies (1017, 1018, 1019 and 1020) eV with two zenith angles 0o and 30o. 960 EAS showers are simulated using Monte-Carlo program Aires version (19.04.00) with the models of hadronic interaction (EPOS-LHC, QGSJET-II-04, and Sibyll2.3c). In this study we investigated various secondary particles that arrive the ground and deposit a portion of their energy on ground detectors. The analyzed results show that the distinction in the energy distribution at ground is bigger for primary proton than carbon, iron nuclei, and silicon at higher energies and vertical showers.

Una vasca da bagno risale lentamente, come sospinta dal soffio di Madre Terra, dalle viscere di una collina metallifera nei pressi di Zenica, nella Bosnia centrale. Un carico di carbone fumante appena estratto è pronto per essere setacciato e caricato su un vecchio camion dell’esercito jugoslavo dalla squadra di minatori che opera in superficie. È così che, dalle profondità della terra dove trovano lavoro centinaia di minatori illegali bosniaci, nasce un florido commercio parallelo di carbone che andrà ad alimentare caldaie e cucine di migliaia di famiglie in tutto il Paese. Ciò avviene in totale assenza di contratti, norme di sicurezza, tutele assicurative o garanzie di alcun tipo per i lavoratori. Nella città considerata una «Jugoslavia in miniatura», modello del socialismo reale, trainata dalla sua acciaieria (Željezara Zenica) e dall’indotto metallurgico-minerario (più di 50.000 operai), fino agli inizi degli anni Novanta a inebriare l’ambiente economico e socio-culturale era il senso di sigurnost (sicurezza) e di fiducia nel futuro, sprigionate da un paradigma lavorativo fondato sulla Samoupravljanje (Autogestione). Questo metteva al centro la figura dell’uomo-operaio, autentico simbolo del progresso e del miglioramento delle condizioni di vita e lavoro avvenuto nel secondo Dopoguerra. La dissoluzione della Jugoslavia e la Guerra che ne è seguita, ha portato al collasso del sistema-vita in cui gli abitanti di Zenica hanno vissuto per 50 anni. I lavoratori dell’acciaieria e delle miniere statali sono stati espulsi in massa dal mercato del lavoro senza alternative valide a livello occupazionale, sfavoriti da un contesto economico che orbitava intorno a una sola cometa: l’industria pesante. Alla luce dei profondi mutamenti occorsi in Bosnia ed Erzegovina nelle ultime decadi, come sono andati riconfigurandosi dal punto di vista lavorativo e sociale, le traiettorie esistenziali degli abitanti di Zenica? Ho cercato di avvicinarmi a questo interrogativo analizzando il prisma dell’economia sommersa che, negli anni dell’ultimo Dopoguerra e dei piani di aggiustamento strutturali in chiave neoliberista (apertura al libero mercato, privatizzazione delle proprietà sociali, deregolamentazione finanziaria, de-sindacalizzazione delle imprese), ha guadagnato un ruolo di primo piano nell’intero panorama economico-produttivo bosniaco (Divjak & Pugh, 2013). Attraverso l’etnografia e l’esperienza di lavoro con i minatori illegali di Zenica, ho cercato di indagare la situazione inerente al mercato del lavoro (in particolare l’estrazione abusiva del carbone) e i temi ad esso correlati quali disoccupazione, emigrazione, diritti dei lavoratori, corruzione, sfruttamento, genere e processi di produzione di illegalità in questo particolare contesto post-industriale, post-bellico e post-socialista. L’estrazione illegale dell’oro nero bosniaco, unitamente all’interesse per le questioni che riguardano il complesso e sfaccettato quadro economico-sociale e politico-culturale del Paese, mi ha portato ad intercettare il filone di studi delle Artisanal and Small Scale Mining (ASM), da cui la presente tesi ha attinto parte dell’impalcatura teorica. Come primo progetto di studi in ambito europeo sulle ASM il lavoro non gode di una letteratura d’area cui appoggiarsi, pertanto l’impianto teorico prenderà spunto da più fonti, rinunciando ad ogni pretesa di esaustività. La speranza è semmai quella di contribuire al dibattito accademico cercando di rendere, attraverso l’etnografia, da un lato la complessità delle nuove relazioni sociali ed economiche legate ad un mutato universo di significati in cui agiscono gli attori del panorama estrattivo artigianale zeničano, dall’altro di presentare le prospettive future di un vasto mondo del lavoro illegale, connesso a scelte politiche ed economiche non solo di carattere locale ma soprattutto federale, nazionale e globale.
A bathtub rises slowly, as pushed by the Mother Earth’s breath, from the bowels of a metallic hill near Zenica, in central Bosnia. A cargo of freshly extracted steaming coal is ready to be sieved, stowed in 50 kg bags, and loaded into an old Yugoslav army truck by the miners working outside. Here, from the depths of the earth where hundreds of Bosnian illegal miners find work, a thriving parallel coal trade is born, in order to feed stoves, boilers and kitchens for thousands of families across the country. This occurs in the total absence of contracts, any kind of safety regulations, insurance protections or guarantees for the workers. During the Tito period, this city was considered a «miniature Yugoslavia», a true model of real socialism, driven by both its steel mill (Željezara Zenica) and the metallurgical-mining industries (which employed more than 50,000 workers). Until the beginning of the nineties, the economic and socio-cultural environment was enhanced by the pervasive sense of sigurnost (security) and the confidence in the future, released by a work paradigm based on Samoupravljanje (Self-management). This was focused on the man-worker, an authentic symbol of progress and improvement of living and working conditions, which took place in the second post-war period. The dissolution of Yugoslavia and the consequent war led to the collapse of this life-system, known by the inhabitants of Zenica for 50 years. The steel mill and State mines workers were all expelled from the labor market without valid alternatives in terms of employment. They were also penalized by an economic context based on a single, great and bright direction: the “heavy” industry, fundamental and everlasting point of reference for thousands of workers and citizens. Considering the deep changes occurred in Bosnia and Herzegovina in the last few decades: how the lives of the Zenica (the "Incandescent City") inhabitants have been set up again from a working and social point of views? I tried to approach this question by analyzing the condition of the underground economy. During the last postwar period and throughout the structural adjustment plans in a neoliberal view (for example, the opening to the free market, privatization of social property, financial deregulation, de-unionization of companies), this hidden economy has gained a leading role in the entire Bosnian economic-productive landscape (Divjak & Pugh, 2013). Considering the ethnography and my experience working with the illegal miners in Zenica, I wanted to investigate the situation of the labor market (in particular illegal coal mining) and the related issues, such as unemployment, emigration, rights of workers, corruption, exploitation, gender, conflicts, cooperative methods and illegal production processes in this particular post-industrial, post-war and post-socialist context. The illegal "private" extraction of Bosnian black gold, together with my interest in issues like the complex and diverse economic-social and political-cultural framework of the Country, led me to the specific studies of the Artisanal and Small Scale Mining (ASM), from which the theoretical framework of this thesis is based. As the first European study project on ASM, this work does not have a literature background to rely on, therefore the theoretical framework will be inspired by different sources, without claiming to be exhaustive. My aim (and hope) is to contribute to the academic debate. Through ethnography, I am trying to explain the complexity of the new social and economic relationships connected to the changed life meanings in which the artisanal miners of Zenica are working now. Also, I want to present the future possibilities for the large world of illegal work, deeply linked to political and economic choices, not only local but especially the federal, national and global ones.

Abstract SiCw is expected to be candidate material for Accident Tolerant Fuel (ATF). Nevertheless, the distribution, morphology and size of SiCw have impacts on the thermal conductivity of composite fuels. An analysis model for UO2-SiCw was established using finite element method (FEM), and the effects of whisker orientation, size, volume fraction and aspect ratio on thermal conductivity were analyzed. The generation algorithm of SiCw was improved, and the results of thermal conductivity calculations showed that the improved model is closer to the experimental value. The effect of whisker orientation on thermal conductivity can be calculated by the cosine law of zenith angle and azimuth angle, and deriving a model for calculating thermal conductivity with specific whisker orientation. With the decrease of whisker size, the influence of Kapitza thermal resistance is significant. The formula used to calculate the whisker threshold diameter was deduced, and the results are in good agreement with the FEM results. With the increase of volume fraction of whiskers, the thermal conductivity increases linearly. For morphology, whiskers with high aspect ratio can achieve higher thermal conductivity. There is a value for the ratio of whisker length to matrix size, above which increasing whisker length will slow the increase in thermal conductivity (0.3 for whiskers along the direction of thermal conduction). The thermal conductivity of UO2-SiCw was optimized using the above conclusions, and the radial temperature distribution of pellet was analyzed. The results show that taking full advantage of the anisotropy of whisker heat transfer can significantly improve the thermal conductivity of composites and improve the operation condition of the pellet. The results can provide a good theoretical basis for designing whisker-doped composites with high thermal conductivity.