Photoacoustic properties of single crystal PbTe(Ni)

Single crystals of PbTe(Ni) were investigated by the photoacoustic method. They were produced using the Bridgeman method. These crystals have a sodium chloride cubic lattice and could be cleaved paralel to the plane orientation (200). They were of the n-type. Phase and amplitude photoacoustic spectra were measured using a transmision detection configuration set-up. Photoacoustic (PA) spectra (single and normalized) were numerically analyzed using the Rosencwaig-Gersho model. Thermal diffusivity and some electron-transport parameters were determined. These results were compared with existing results for pure single crystal PbTe. Thermal difusivity of PbTe(Ni) is a bit higher than the thermal difusivity of pure PbTe. This is the consequence of a decreasing concentration of the majority free carriers in the doped alloy

Outdoor human thermal comfort in local climate zones of Novi Sad (Serbia) during heat wave period

Urban climate monitoring system (UCMS) was established in Novi Sad (Serbia) in 2014 based on the Local Climate Zones (LCZs) classification system, GIS model calculations and field work. Seven built and two land cover LCZ types were delineated and 27 stations equipped with air temperature and relative humidity sensors were distributed across all LCZs. Suitability of the developed monitoring system for human outdoor thermal comfort research in different LCZs of the city and its surroundings was investigated during a heat wave period using Physiologically Equivalent Temperature (PET) index. During the daytime (night-time) the highest thermal loads are present in open midrise (compact midrise) LCZ, while the most comfortable is LCZ A (dense trees) during the whole day. In general, the highest thermal loads are obtained in midrise, followed by low-rise, sparsely built, low plants and dense trees LCZs. All LCZs (except LCZ A - dense trees) had higher PET when compared to LCZ D (LCZ D - low plants) during evening and nocturnal hours with maximum difference of 7.1 °C (00 UTC) between LCZ 2 (compact midrise) and LCZ D (low plants). Contrary to this, LCZ D (low plants) had higher PET compared to the majority of LCZs during the daytime with maximum difference of 8.5 °C (9 UTC) when compared to LCZ A (dense trees). Furthermore, the smallest thermal comfort differences during heat wave occurred between LCZs with similar structure (i.e. open low-rise and large low-rise, compact midrise and compact low-rise) and cover (i.e. sparsely built and low plants)

Far infrared properties of iron doped single crystal PbTe

Far infrared reflectivity spectra of single crystal PbTe samples doped with 0.2 at% Fe were measured in the temperature range between 10 K and 300 K. These spectra show very sharp and narrow dips below 120 cm-1. The experimental data were numerically analyzed using a fitting procedure based on the plasmon-phonon interaction model. Two local modes were observed. The first one was noted between 130 cm-1 and 170 cm-1 depending on the temperature and the second more frequency stable one was noted at about 230 cm-1

Far infrared properties of sintered PbTe doped with boron

Far infrared spectra of sintered PbTe doped with boron were analyzed. The measured infrared spectra were fitted using a modified plasmon-phonnon interaction model with two additional oscillators (at about 195 cm-1 and 285 cm-1) representing local B-impurity modes. The obtained results were compared with previously published data for a single crystal PbTe sample doped with boron

Far infrared properties of sintered PbTe doped with boron

Far infrared spectra of sintered PbTe doped with boron were analyzed. The measured infrared spectra were fated using a modified plasmon-phonnon interaction model with two additional oscillators (at about 195 cm(-1) and 285 cm(-1)) representing local B-impurity modes. The obtained results were compared with previously published data for a single crystal PbTe sample doped with boron

Water quality of the Pannonian basin rivers the Danube, the Sava and the Tisa (Serbia) and its correlation with air temperature

The Danube, the Sava and the Tisa rivers belong to the Black Sea river basin and they flow through many European countries, while in Serbia they flow through the Pannonian flatland. The water quality of these rivers, which is affected by complex anthropogenic activities and natural factors, is one of important factors that are taken into account in the evaluation of development sustainability of this region. Using the correlation analysis in this paper we tested the impact of air temperature as a natural factor on certain parameters indicating the water quality. A significant correlation was found between air temperature and total nitrogen oxides in the Danube of up to -0.744, namely of -0.740 on the Tisa and -0.299 on the Sava. A significant correlation was found in electrical conductivity - up to -0.793 on the Danube, -0.226 on the Tisa, and 0.380 on the Sava. Correlation links were found between air temperature and O2, BOD, as well as suspended matters saturation percentage, but their correlation values are significantly lower. Based on the results of the research it was concluded that air temperature had low effect on changes in water quality during the year and that anthropogenic impact was far more dominant

Maximum temperatures over Slovenia and their relationship with athmospheric circulation patterns

This paper examines temporal and spatial patterns of annual and seasonal maximum temperatures (Tmax) in Slovenia and their relationship with atmospheric circulation patterns. A significant increase in maximum temperature (Tmax; from 0.3°C to 0.5°C∙decade−¹) was observed throughout the country at the annual scale in the period 1963-2014. Significant positive trends are observed on all stations in summer (from 0.4°C to 0.7°C∙decade−¹) and spring (from 0.4°C to 0.6°C∙decade−¹). The results indicate significant correlations between the mean annual maximum temperature (Tmax) and the East Atlantic Oscillation (EA) (from 0.5 to 0.7), the Arctic Oscillation (AO) (from 0.4 to 0.7) and the Scandinavian Oscillation (SCAND) (from −0.3 to −0.4) throughout the country. A significant EA influence is observed in all seasons, while the AO influence is noticed in winter and spring, SCAND in spring and summer, the North Atlantic Oscillation (NAO) and the Mediterranean Oscillation (MO) in winter, the East Atlantic/Western Russia Oscillation (EA/WR) in summer and the El Nino Southern Oscillation (ENSO) in autumn.12

Far infrared characterization of samarium doped single crystal PbTe

Single crystal samples of lead telluride doped with samarium were produced using the Bridgman method. Far infrared reflectivity spectra in the temperature range 10 K - 300 K are presented and numerically analyzed using a fitting procedure based on a modified plasmon phonon interaction model. The optical parameters were determined and three local modes of samarium were observed at about 167 cm-1, 227 cm-1 and 486 cm-1

Variability of seasonal and annual precipitation in Slovenia and its correlation with large-scale atmospheric circulation

This paper examines temporal and spatial variability and trends of annual and seasonal precipitation in Slovenia and their relationship with three atmospheric circulation patterns represented by their indices: North Atlantic Oscillation index (NAOi), Mediterranean Oscillation index (MOi) andWestern Mediterranean Oscillation index (WeMOi). Data from 45 precipitation stations were used for the period 1963–2012.Mean annual precipitation varies from 736 mm in eastern Slovenia to 2,518 mm in northwestern Slovenia. A significant annual precipitation decrease (from −3% to −6% per decade) is observed in western Slovenia. Significant negative trends are observed in southwestern Slovenia in summer (from −4% to −10% per decade) and near the Adriatic coast in spring (from −6% to −10% per decade). Non-significant negative and positive trends are observed in winter and autumn, respectively. Results indicate significant correlations between winter precipitation and MOi (from −0.3 to −0.7), NAOi (from −0.3 to −0.6) andWeMOi (from 0.3 to 0.6). Significant We-MOi influence is observed in spring and autumn, while NAOi and MOi influence has not been detected. Annual precipitation and WeMOi are significantly correlated in central and eastern Slovenia, while significant NAOi and MOi influence is observed in western Slovenia (with the larger area covered by MOi influence)