•Large intraspecific response in growth related to climate of provenances origin•High genetic diversity at upper altitude but low in lower altitude populations•A loss of 6% in suitable area for ...Norway spruce until 2100 is projected•Adaptation strategy can include assisted migration and resilient genotypes selection
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Five provenance tests with twenty-six European silver fir autochthonous populations were used in order to assess the response of populations to climate change. Height growth and diameter at breast ...height of trees at age 31 years were considered as response variables and eight climate variables as predictors. Climatic variables for the trial sites and for origin location of provenances were calculated from 1961 to 2010. The experiments revealed a large genetic variability within species level and a plastic response to climate change, which certainly has a genetic basis. The transfer to warmer climate has resulted in an increase of the provenances growth, in the trial sites situated on the lower vegetation layer. But growth is significantly influenced by mean annual temperature and annual precipitation of planting site and also by the differences in mean annual temperature, annual precipitation, monthly mean temperature in July and July precipitation between provenance site and test site. These are the climatic factors which should be associated with risk in case of the transfer of forest reproductive materials. The provenance origin should be especially considered if the species will be planted outside of its current climate optimum. The best provenances in terms of total height and diameter at 1.30 m came from origin climate close to site climate, small transfer distances. Based on growth response functions and RCP4.5 scenario, we could project the shifts in species distribution for 2050s and 2100s and identify vulnerable populations.
•New balances of first and second law for gray surfaces with one or two sources.•A new GS (Gray Surface) model of radiative exergy efficiency is proposed.•A matrix-based analytic method of radiative ...design for hybrid solar collectors.•A methodology to compute the thermal radiation losses through lateral walls.•Collector thickness impact is quantified by the radiative lateral losses.
This paper provides two main contributions: a new general formulation of radiation exergy and exergy efficiency of photovoltaic (PV) panels as grey surface absorbers; the development of an analytic method of radiative design of hybrid solar collectors by using matrix formalism.
The new proposed GS (Gray Surface) model of exergy efficiency applicable for gray surfaces is proposed and compared with the classical models (in the first case study) and with its value of 0.939 reveals a difference of up to 1% compared with Petela-Landsberg-Press model (0.932) or Jeter-Carnot model (0.949).
The new methodology is able to determine the thermal radiation losses through the lateral walls. The second case study includes an estimation of these losses at 2.63% for the analyzed design. A sensitivity analysis of thickness vs. exergy efficiency is performed, showing that each increase of the thickness of the collector by 10 mm determines a decrease of the extracted power (work) by 1.6% while the radiative exergy efficiency decreases by 0.75%.
By including, in future research, the effect of the convection heat transfer, the proposed methodology could stand as a theoretical reference that can be compared with other two paths of research: numerical (CFD) and empirical.
This article considers a new type of air infiltration through building envelopes caused by the barometric pressure variation. This process is independent from wind action or stack effect. A new ...building–atmosphere differential equation of air exchange is established. Based on the solution of the differential equation of air exchange, we propose the notion of pressure equilibration time
τ
50
that characterizes the dynamic response of the building. Furthermore, experimental climatic data were processed using Fourier analysis methods in order to build an identification model based on the regular harmonics of external pressure oscillation. The barometric pressure reconstructed in its parameterized form was introduced in the differential equation of air exchange as a term that models the dynamics of the external action.
The analytic solution of the differential equation of air exchange demonstrates that the indoor–outdoor pressure difference is insignificant at less than 10−3 Pa for any harmonic of the external pressure variation. At the same time, it is concluded that the airtightness of the envelope has little influence on the process, as the indoor–outdoor pressure equilibration is almost instantaneous in a continuous regime of variation.
The described mechanism of air infiltration explains the alternation of infiltration and exfiltration of air in buildings. For this, a mass balance of air exchange for the specific ranges of time is performed. We prove that the barometric pressure variation has an effect that accounts for 3.19% of the total quantity of air exchanged.
The advances provided by this paper constitute a useful instrument for further studies concerning the stack effect in thermal dynamic conditions.
Practical application: The paper proposes a novel methodology of determining the air exchange building–environment by considering a new component of infiltration and its cyclic variation: the barometric pressure. A new mechanism of natural air infiltration is determined and modeled and it should be added to the existing ones: wind action and stack effect. A complete methodology of analysis and extraction of the cyclic processes hidden in an envelope of stochastic variations is defined and applied with the support of signal processing techniques and spectral analysis. The refinement of the mathematical instrument was able to distinguish through a deterministic approach an influence of 3.19% of the new barometric component. Furthermore, with few adaptations, the methodology constructed in this study can be applied for investigation of the stack effect by considering the cyclic variation of the atmospheric temperature. Currently, the stack effect is analyzed only for average conditions of temperature, a simplistic approach that suggests a large potential for further improvement.
The aim of the present study is to investigate the effects of operating conditions and establish the mechanism of xanthene dye removal from aqueous solutions by electrocoagulation (EC) using a ...batch-stirred cell operated under galvanostatic regime. The influence of the operating parameters such as: initial pH and dye concentration, electrolysis time, current density, electrode configuration, and electrical current type on the EC performances was investigated. EC tests were performed at current density values ranging from 45 to 109 A/m, initial dye concentrations ranged between 0.1 and 1 g/L, and initial pH values adjusted in the range from 3 to 9. The effects of several electrode configurations (aluminum–aluminum, mild steel–mild steel, and aluminum–mild steel) and current regimes (direct current and alternating pulsed current) on the removal efficiency and energy and material consumption are also discussed. Total organic carbon (TOC) analysis, UV–vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), and cyclic voltammetry (CV) were employed in order to elucidate the decolorization mechanism of Rhodamine 6G (R6G) dye by EC in aqueous solutions. With this aim in view, chemical coagulation tests were also carried out. The best performance was obtained when the EC process was conducted with iron-based electrode configuration in alternative pulse current (APC) mode. It was found that the removal of R6G is due to the co-precipitation of polymeric iron flocs with the phenyl-xanthene radicals remained in the bulk solution after the demethylation and deamination processes. Furthermore, the flocs are separated by flotation with the support of the molecular hydrogen generated at the cathode (in particular at relatively high values of current density) or by sedimentation.
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