Brzi postupak procjene kapacitivne dimenzije fraktalnih objekata metodom brojanja kvadrata

A fast procedure for computing fractal dimension by the box counting is derived. An approximation for the number of visited boxes NB(ǫ, n) as a function of n is given. The memory requirement is calculated with this function and the scaling for derivative ∆N(ǫ, n)/∆n ≈ const × βǫ−αn −β−1 given by Grassberger is obtained for the non saturated segment. The procedure is tested on the calculation of fractal dimension of Sierpinski triangle and the H´enon map, and compared with the procedure of Grassberger.Izložen je brzi postupak za računanje fraktalne dimenzije pomoću metode brojanja kvadrata (box counting). Dana je aproksimacija broja popunjenih kvadrata NB(ǫ, n) kao funkcija od n. Tom funkcijom izračunati su memorijski zahtjevi i dobiveno je skaliranje Grassbergerove derivacije ∆N(ǫ, n)/∆n ≈ konst × βǫ−αn −β−1 za nezasićeno područje. Postupak je provjeren na proračunu fraktalne dimenzije za trokut Sierpinskog i za Henonovo preslikavanje, te je uspoređen sa Grassbergerovim postupkom

Missing Fe: hydrogenated iron nanoparticles

Although it was found that the FeH lines exist in the spectra of some stars, none of the spectral features in the interstellar medium (ISM) have been assigned to this molecule. We suggest that iron atoms interact with hydrogen and produce Fe-H nanoparticles which sometimes contain many H atoms.We calculate infrared spectra of hydrogenated iron nanoparticles using density functional theory methods and find broad, overlapping bands. Desorption of H2 could induce spinning of these small Fe-H dust grains. Some of hydrogenated iron nanoparticles possess magnetic and electric moments and should interact with electromagnetic fields in the ISM. FenHm nanoparticles could contribute to the polarization of the ISM and the anomalous microwave emission. We discuss the conditions required to form FeH and FenHm in the ISM

Buckling and post-buckling behavior of shell type structures under thermo mechanical loads

The thermo mechanical buckling and post-buckling behavior of layered composite shell type structure are considered with the finite element method under the combination of temperature load and applied mechanical loads. To account for through-thickness shear deformation effects, the thermal elastic, and higher-order shear deformation theory is used in this study. The refined higher order theories, that takes into account the effect of transverse normal deformation, is used to develop discrete finite element models for the thermal buckling analysis of composite laminates. Attention in this study is focused on analyzing the temperature effects on buckling and post-buckling behavior of thin shell structural components. Special attention in this paper is focused on studying of values of the hole in curved panel on thermal buckling behavior and consequently to expend and upgrade previously conducted investigation. Using finite element method, a broader observation of the critical temperature of loss of stability depending on the size of the hole was conducted. The presented numerical results based on higher-order shear deformation theory can be used as versatile and accurate method for buckling and post-buckling analyzes of thin-walled laminated plates under thermo mechanical loads

Effects of Price Competitiveness on Tourism Performance Under Different Economic Conditions

Many scholars perceive price competitiveness as a highly relevant element of tourism competitiveness in improving tourism performance. We focused our research interest specifically to understand whether price competitiveness is an important policy instrument in attracting international tourists and their spending. Our empirical study focused on how price competitiveness behaves as a predictor of tourism performance in different economic conditions and whether price competitiveness is a significant cause of tourism competitiveness in improving tourism performance. For that purpose, we conducted empirical analysis within two stages: moderation analysis to understand how price competitiveness influences tourism performance from the point of view of inbound international tourism and how this relationship behaves in different economic conditions; and mediation analysis to understand whether price competitiveness is relevant cause for tourist competitiveness in improving tourism performance. This study has revealed different views about price competitiveness and its influence on the tourism industry. The findings indicate that price competitiveness has rather limited effects on the outcomes of the tourism industry and is not a cause of overall tourism competitiveness in improving tourism performance

Buckling and post-buckling behavior of shell type structures under thermo mechanical loads

The thermo mechanical buckling and post-buckling behavior of layered composite shell type structure are considered with the finite element method under the combination of temperature load and applied mechanical loads. To account for through-thickness shear deformation effects, the thermal elastic, and higher-order shear deformation theory is used in this study. The refined higher order theories, that takes into account the effect of transverse normal deformation, is used to develop discrete finite element models for the thermal buckling analysis of composite laminates. Attention in this study is focused on analyzing the temperature effects on buckling and post-buckling behavior of thin shell structural components. Special attention in this paper is focused on studying of values of the hole in curved panel on thermal buckling behavior and consequently to expend and upgrade previously conducted investigation. Using finite element method, a broader observation of the critical temperature of loss of stability depending on the size of the hole was conducted. The presented numerical results based on higher-order shear deformation theory can be used as versatile and accurate method for buckling and post-buckling analyzes of thin-walled laminated plates under thermo mechanical loads

Analysis and prediction of rapeseed production indicators in the Republic of Srpska

The aim of this paper is to predict future trends in the basic production of rapeseed in the Republic of Srpska. The period to which the prediction relates is from 2018 to 2022, and the time series that is the subject of research is from 1996 to 2017. In addition to the descriptive analysis method, the Box-Jenkins model based on the ARIMA (Autoregressive Integrated Moving Average) class is used in the paper with the prediction purpose. The results obtained from the research show that, regardless of the present oscillations, in the future, there will be an increase in the area under the rapeseed and that in the last year of the prediction, the surface will reach the level of 1920 ha. Also, production is expected to increase even by 4 times more in comparison with the average from the analysed period. Predicted production in the last year of the prediction period will be about 5,824 tons. As far as the yield of rapeseed is concerned, it is expected to be 1.11 t/ha or even by 36% at a higher level than the average yield in the analysed period. Respectively, the predicted yield in the last year is higher by 0.21 t/ha or about 7% of the maximum yield in the observed period

Application of Predictive Models for Natural Gas Needs - Current State and Future Trends Review

Nowadays, in terms of trading on the world scale, to foresee a natural gas consumption represents an essential activity. In the first part, the paper examines the current state of the Serbian natural gas sector and methodology applied for prediction and capacity planning. In addition, the study intends to give a comprehensive assessment of predictive algorithms for natural gas needs involved in the last decade with projections and suggestions for future applications. The primary task is to evaluate used predictive models with an emphasis on the accuracy of the predictions obtained. Additionally, the paper will analyse used parameters, consumption scale, prediction scope, forecast algorithms, and other related information. The main objective of this study is to review the new-fangled information related analyses data from peer-reviewed journals, international conferences, and books