A Statistical Analysis of Temperature and Precipitation in Belgrade, Serbia (1961-2020)

The most significant effects of climate change are related to temperature and precipitation. Changes in precipitation and temperature patterns affect water resource capacity, agricultural activities, global biodiversity and emergency management. In this study, using two statistical models (Mann-Kendall and Pettit’s test), climate data for the territory of Belgrade in the time interval 1961-2020 were processed. Trends were analyzed: average annual temperatures, average monthly temperatures, annual and monthly precipitation amounts. The aim of the research is to determine the statistical significance of the increasing/decreasing temperature and precipitation trends on a monthly and annual basis. Based on the obtained results, it was determined that the changing point of the annual temperature is in 1997, while a statistically significant increasing trend was observed in all months except November. The increasing trend recorded by the precipitation amount is 0.345 mm/year, but without statistical significance. The most significant results corresponding to July and October

The influence of spark plasma sintering temperature on the properties of Sb-doped barium stannate ceramics

Barium-stannate (BaSnO3, BSO) is a member of the perovskite-type alkaline earth stannates ASnO3 (A = Ca, Sr, Ba) with an ideal cubic crystal structure (space group: ). Doping with antimony (Sb5+) can change this wide band-gap semiconductor (Eg = 3.1-3.4 eV) into an n-type semiconductor with high electrical conductivity at room temperature. The major drawbacks in the BSO-based ceramics synthesis are phase composition and low density of final ceramic materials. These problems could be solved using spark plasma sintering (SPS), a current and pressure-assisted technique, which enables the preparation of dense ceramics at significantly lower temperatures and for a shorter time. To investigate the influence of spark plasma sintering temperature on the structural, microstructural and electrical properties of BaSn1-xSbxO3 (BSSO, x = 0.00; 0,04; 0.06; 0.08; and 0.10) ceramics samples, BSSO powders were spark plasma sintered at 1100 °C, 1200 °C and 1250 °C for 5 min. X-ray diffraction (XRD) analysis confirmed that all ceramic samples sintered at 1100 °C crystallized in a single-phased cubic BSO structure. Their relative densities were in the range of 72–82% ρt. Sintering at 1200 °C increased the samples’ relative densities to 79–96% ρt, but also induced the formation of a barium-rich secondary phase, Ba2SnO4. Rising the sintering temperature further to 1250 °C induced the melting of all samples except BaSn0.92Sb0.08O3. Field emission scanning electron microscopy (FE-SEM) revealed that doping with antimony decreased the grain sizes in BSSO samples sintered at 1100 °C and 1200 °C up to the concentration x = 0.08. Electrical measurements revealed the typical semiconductor behavior of the undoped samples, showing nonlinear current-voltage characteristic and the existence of one semicircle in their impedance spectra, characteristic for materials with double Schottky barrier at the grain boundaries. However, samples with higher dopant concentrations (x = 0.08 and 0.10) showed significantly lower electrical resistivity and linear current-voltage characteristic. The lowest and almost constant value of electrical resistivity in the temperature range of 25–150 °C, and complete loss of the semicircle in its impedance spectrum revealed the metallic-like behavior of sample BaSn0.92Sb0.08O3 sintered at 1200 °C

Effect of the sintering technique on the properties of Sb-doped BaSnO3 ceramics

Barium stannate, BaSnO3 (BSO), a cubic perovskite-type oxide with its interesting structural, optical and electrical properties has wide application as an electrode material, thermally stable capacitor, transparent conductive oxide, photocatalyst, humidity and gas sensor material [1]. Partial substitution of Sn by Sb in BSO leads to drastic changes primarily in its electrical properties, resulting in metallic-like conductivity of doped ceramics. Major problems concerning the synthesis of Sb doped BSO (BSSO) are connected to the phase composition and density of final ceramic material. This study covers the comprehensive investigation of structural, microstructural and electrical properties of the Sb-doped BaSn1-xSbxO3 (x = 0.00, 0.04 and 0.08, BSSO) ceramic materials obtained by two different sintering techniques: conventional sintering (CS) and Spark Plasma sintering (SPS). The relative densities of the BSSO-CS ceramic samples sintered at 1600 °C for 3 h was in the range of 79– 96 %. On the other side, the relative densities of BSSO-SPS ceramic samples in the range of 86–96 % were obtained at 1200 °C, with sintering time of only 5 minutes. The XRD analysis confirmed that cubic BaSnO3 is a major phase in all BSSO samples. The presence of tetragonal Ba2SnO4 as a secondary phase was detected in BSSO-SPS ceramic samples, with its content decreasing upon Sb-doping. As expected, the grain size of the samples sintered at higher temperatures (BSSO-CS) is larger in comparison with BSSO-SPS ceramic samples, which was confirmed by Scanning Electron Microscopy (SEM). SEM analysis also revealed the layered structure within the grains of BaSn0.92Sb0.08O3-CS sample while HRTEM analysis confirmed the existence of the low angle grain boundaries (LAGBs) in the SPSed sample with the same composition. The electrical resistivity decreased upon Sb doping, and all doped BSSO samples showed the linear I-U characteristic in the temperature range of 25–150 °C. The semiconductor behavior of all BSSO-CS and BSSO-SPS (x = 0.00 and 0.04) ceramic samples was confirmed through the existence of semicircles in their impedance spectra. On the other hand, the BaSn0.92Sb0.08O3 sample showed the metallic-like behavior resulting from the loss of the electrostatic barriers at LAGBs, which is manifested through the absence of the semicircle in its impedance spectra

Širenje rudarskog basena vs ruralna obnova - stanje i perspektive razvoja ruralnih naselja u opštini Lazarevac

Na području rudarskih basena dolazi do velikih promena prirodne i društvene sredine jer sa jedne strane postoji velika naseljenost i izgrađenost prostora, a sa druge strane specifični zahtevi površinske eksploatacije. Rudarski basen „Kolubara” je važan nosilac srpske energetike, a otkopavanje uglja se u najvećoj meri obavlja na teritoriji opštine Lazarevac, pa se usled planiranog razvoja površinskih kopova očekivano na ovom prostoru događaju najintenzivnije promene preseljavanja stanovništva, naselja ili delova naselja. U radu se analizira dinamika preseljavanja stanovništva, karakter i tip raseljavanja naselja. Težište rada predstavlja prikaz transformacije mreže naselja na teritoriji opštine Lazeravac, analizom fizionomskih, demografskih, funkcionalnih i dr. promena uslovljenih širenjem rudarskog basena „Kolubara“. Cilj rada je detaljno sagledavanje uticaja rudarskog basena „Kolubara“ na sveobuhvatni razvoj naselja na teritoriji opštine Lazarevac, kao i uočavanje mogućnosti i ograničenja razvoja ruralnih naselja na proučavanom prostoru

Uticaj rudarskog basena "Kolubara" na razvoj naselja u opštini Lazarevac

Rudarski basen Kolubara, kroz svoju primarnu ulogu snabdevanja termoelektrana za proizvodnju električne energije, predstavlja jedan od temelja privrednog razvoja Republike Srbije, sa posebnim naglaskom na opštinu Lazarevac na čijoj se teritoriji basen najvećim delom prostire. Višegodišnja dinamika širenja kopova i razvoja rudarske delatnosti uticala je na transformaciju geoprostora, kako u pozitivnom tako i u negativnom kontekstu. Osnovni cilj ovog rada jeste detaljno sagledavanje uticaja rudarskog basena „Kolubara“ na sveobuhvatni razvoj naselja na teritoriji opštine Lazarevac. Istraživanje je pokazalo da širenjem površinskih kopova dolazi do promene u demografskim, funkcionalnim i fizionomskim karakteristikama naselja, kao i do raseljavanja samih naselja ili njihovih pojedinih delova. U skladu sa tim, budući razvoj mora biti usmeren na organizaciju racionalnije mreže centara, koji će olakšati transformaciju okolnih naselja, uz marginalizaciju negativnih uticaja širenja ugljenokopa na homogenost i kompaktnost postojeće mreže naselja

Urban Sustainability in Serbia: Sustainable for whom?

The issue of urban sustainability and sustainable management of cities has become an important topic. On the one hand, urbanization and the expansion of larger metropolitan areas are expected to increase in the future, while other regions and cities are simultaneously shrinking. For the first time in Serbia, the “Program for Sustainable Urban Development until 2030” is adopted with the requirements for sustainable urban planning. The main issues of urban development focus on sustainable economic development, urban settlement planning, social well-being, environmental quality and urban development management. However, the complex spatial-demographic and socioeconomic changes during the post-socialist transition have determined the demographic development of urban settlements in Serbia towards shrinkage. At the beginning of the 21st century, the total population of cities in Serbia has slightly increased, but disproportions in population development between urban settlements have deepened, leading to urban polarization. As a result, more than 80% of urban settlements are shrinking. None of the key problems identified in the program address urban shrinkage as a main trend. In this study, we conducted an analysis of the development of the total population trends and age structure in 167 urban settlements in Serbia in the period 2011-2022. The aim of this study is to show the demographic dimension of urban development and its importance for the sustainability of the city. Linking urban shrinkage and urban sustainability is one of the main objectives of this research

Širenje rudarskog basena vs ruralna obnova - stanje i perspektive razvoja ruralnih naselja u opštini Lazarevac

Na području rudarskih basena dolazi do velikih promena prirodne i društvene sredine jer sa jedne strane postoji velika naseljenost i izgrađenost prostora, a sa druge strane specifični zahtevi površinske eksploatacije. Rudarski basen „Kolubara” je važan nosilac srpske energetike, a otkopavanje uglja se u najvećoj meri obavlja na teritoriji opštine Lazarevac, pa se usled planiranog razvoja površinskih kopova očekivano na ovom prostoru događaju najintenzivnije promene preseljavanja stanovništva, naselja ili delova naselja. U radu se analizira dinamika preseljavanja stanovništva, karakter i tip raseljavanja naselja. Težište rada predstavlja prikaz transformacije mreže naselja na teritoriji opštine Lazeravac, analizom fizionomskih, demografskih, funkcionalnih i dr. promena uslovljenih širenjem rudarskog basena „Kolubara“. Cilj rada je detaljno sagledavanje uticaja rudarskog basena „Kolubara“ na sveobuhvatni razvoj naselja na teritoriji opštine Lazarevac, kao i uočavanje mogućnosti i ograničenja razvoja ruralnih naselja na proučavanom prostoru

Uticaj rudarskog basena "Kolubara" na razvoj naselja u opštini Lazarevac

Rudarski basen Kolubara, kroz svoju primarnu ulogu snabdevanja termoelektrana za proizvodnju električne energije, predstavlja jedan od temelja privrednog razvoja Republike Srbije, sa posebnim naglaskom na opštinu Lazarevac na čijoj se teritoriji basen najvećim delom prostire. Višegodišnja dinamika širenja kopova i razvoja rudarske delatnosti uticala je na transformaciju geoprostora, kako u pozitivnom tako i u negativnom kontekstu. Osnovni cilj ovog rada jeste detaljno sagledavanje uticaja rudarskog basena „Kolubara“ na sveobuhvatni razvoj naselja na teritoriji opštine Lazarevac. Istraživanje je pokazalo da širenjem površinskih kopova dolazi do promene u demografskim, funkcionalnim i fizionomskim karakteristikama naselja, kao i do raseljavanja samih naselja ili njihovih pojedinih delova. U skladu sa tim, budući razvoj mora biti usmeren na organizaciju racionalnije mreže centara, koji će olakšati transformaciju okolnih naselja, uz marginalizaciju negativnih uticaja širenja ugljenokopa na homogenost i kompaktnost postojeće mreže naselja

Urban Sustainability in Serbia: Sustainable for whom?

The issue of urban sustainability and sustainable management of cities has become an important topic. On the one hand, urbanization and the expansion of larger metropolitan areas are expected to increase in the future, while other regions and cities are simultaneously shrinking. For the first time in Serbia, the “Program for Sustainable Urban Development until 2030” is adopted with the requirements for sustainable urban planning. The main issues of urban development focus on sustainable economic development, urban settlement planning, social well-being, environmental quality and urban development management. However, the complex spatial-demographic and socioeconomic changes during the post-socialist transition have determined the demographic development of urban settlements in Serbia towards shrinkage. At the beginning of the 21st century, the total population of cities in Serbia has slightly increased, but disproportions in population development between urban settlements have deepened, leading to urban polarization. As a result, more than 80% of urban settlements are shrinking. None of the key problems identified in the program address urban shrinkage as a main trend. In this study, we conducted an analysis of the development of the total population trends and age structure in 167 urban settlements in Serbia in the period 2011-2022. The aim of this study is to show the demographic dimension of urban development and its importance for the sustainability of the city. Linking urban shrinkage and urban sustainability is one of the main objectives of this research