DYNAMIC BEHAVIOR OF TWO ELASTICALLY CONNECTED NANOBEAMS UNDER A WHITE NOISE PROCESS

This paper investigates the almost-sure and moment stability of a double nanobeam system under stochastic compressive axial loading. By means of the Lyapunov exponent and the moment Lyapunov exponent method the stochastic stability of the nano system is analyzed for different system parameters under an axial load modeled as a wideband white noise process. The method of regular perturbation is used to determine the explicit asymptotic expressions for these exponents in the presence of small intensity noises

Comparison between Carotid Artery Wall Thickness Measured by Multidetector Row Computed Tomography Angiography and Intimae-Media Thickness Measured by Sonography

The increased thickness of the carotid wall >1 mm is a significant predictor of coronary and cerebrovascular diseases. The purpose of our study was to assess the agreement between multidetector row computed tomography angiography (MDCTA) in measuring carotid artery wall thickness (CAWT) and color Doppler ultrasound (CD-US) in measuring intimae-media thickness (IMT). Eighty-nine patients (aged 35–81) were prospectively analyzed using a 64-detector MDCTA and a CD-US scanner. Continuous data were described as the mean value ± standard deviation, and were compared using the Mann–Whitney U test. A p value <0.05 was considered significant. Bland–Altman statistics were employed to measure the agreement between MDCTA and CD-US. CAWT ranged from 0.62 to 1.60 mm, with a mean value of 1.09 mm. IMT ranged from 0.60 to 1.55 mm, with a mean value of 1.06 mm. We observed an excellent agreement between CD-US and MDCTA in the evaluation of the common carotid artery thickness, with a bias between methods of 0.029 mm (which is a highly statistically important difference of absolute values [t = 43.289; p < 0.01] obtained by paired T test), and limits of agreement from 0.04 to 0.104. Pearson correlation coefficient was 0.9997 (95% CI 0.9996–0.9998; p < 0.01). We conclude that there is an excellent correlation between CAWT and IMT measurements obtained with the MDCTA and CD-US

Statistical analysis of temperature regime change on the example of Sokobanja basin in eastern Serbia

The changes and oscillations in air temperature during the second half of the 20th and in the early 21st century, have become one of the major concerns of almost all scientific disciplines. Such changes are noticeable both at the local and global level. The objective of this paper is to point out that the changes of this climate element can also be detected at the local level. The research underlying this paper is, in terms of territory, limited to the Sokobanja basin in Eastern Serbia. The analysis relies on the data on air temperature for the period 1946-2012 taken from the Meteorological weather station located in Sokobanja. The obtained data were processed in line with the recommendations of the World Meteorological Organization. The evidenced statistically significant changes in air temperature were examined using the following statistical tests: Pettit test, Standard Normal Homogeneity test, Buishand range test, and von Neumann test

Morphometric Analysis of Nonsclerosed Glomeruli Size and Connective Tissue Content during the Aging Process

Number of sclerotic glomeruli increases during the aging process. Consequently, majority of remained nonsclerosed glomeruli become hypertrophic and some of them sclerotic, too. The aim of this study was to quantify the size and connective tissue content of nonsclerosed glomeruli and to evaluate the percentage of hypertrophic ones in examined human cases during the aging. Material was right kidney's tissue of 30 cadavers obtained during routine autopsies. Cadavers were without previously diagnosed kidney disease, diabetes, hypertension, or any other systemic disease. Tissue specimens were routinely prepared for histological and morphometric analysis. Images of the histological slices were analyzed and captured under 400x magnification with digital camera. Further they were morphometrically and statistically analyzed with ImageJ and NCSS-PASS software. Multiple and linear regression of obtained morphometric parameters showed significant increase of glomerular connective tissue area and percentage. Cluster analysis showed the presence of two types of glomeruli. Second type was characterized with significantly larger size, connective tissue content, and significantly lower cellularity, in relation to the first type. Such glomeruli might be considered as hypertrophic. First type of glomeruli was predominant in younger cases, while second type of glomeruli was predominant in cases older than 55 years

Antioksidativni status i kliničko-patološki parametri kod obolelih od Parkinsonove bolesti

Backgroun / Aim. Constant production of free radicals and antioxidants (AO) in the cell is a part of normal cellular function. Their imbalance might take a part in pathophysiology of many diseases, including Parkinson’s disease (PD). Evaluation of the disease status, prooxidant-antioxidant balance (PAB) and antioxidants are being widely estimated. The aim of this study was to examine potential interaction between several AO variables (GSH, SOD, CAT and PAB) and clinicopathological features of patients with PD, particularly Hoehn and Yahr (H&Y) stage. Methods. A multivariate analysis of variance (MANOVA) was conducted to test the hypothesis of the mean differences between clinicopathological characteristics (gender, age at examination, duration of the disease, and H&Y stage) and AO variables, compared with age/sex matched healthy controls. The study included 91 patients with idiopatic PD patients and 20 healthy controls. Results. The multivariate effect size was estimated at 0.269, p <0.001, implying that 27.0% of the variance of the dependent variables was accounted for H&Y stage. Univariate tests showed that there were significant differences (p <0.001) across the H&Y stage on all AO variables. The H&Y stage remained significant predictor after controlling for the second variable, the disease duration (p <0.001, η2 = 0.249), and there were still significant differences across the H&Y stage on all variables, with effect size ( η2) ranging from 0.132, p =0.011 (lnGSH) to the still high values of 0.535 (lnPAB), 0.627 (lnSOD) and 0.964 (lnCAT). Conclusion. The results indicate that higher level of oxidative stress in blood of PD patients is possibly related to PD stage. Along with reduction of SOD and GSH level, CAT activity was elevated in comparison to healthy subjects. Furthermore, Pwas shifted toward oxidative stress

Numerical modelling of the operation of a two-phase thermosyphon

In the recent years, the interest towards the application of two-phase thermosyphons as an element of heat recovery systems has significantly increased. The application of thermosyphons is steadily gaining popularity in a wide range of industries and energy solutions. In the present study, a 2-D numerical modelling of a two-phase gas/liquid flow and the simultaneously ongoing processes of evaporation and condensation in a thermosyphon is presented. The technique volume of fluid was used for the modelling of the interaction between the liquid and gas phases. The operation of a finned tubes thermosyphon was studied at several typical operating modes. A parametric study over a non-ribbed and finned tubes thermosyphon was carried out. The commercial software ANSYS FLUENT 14.0 was used for the numerical analysis. It was proven that the numerical modelling procedure adequately recreates the ongoing flow, heat and mass transfer processes in the thermosyphon. The numerical result from the phase interaction in the thermosyphon was visualized. Otherwise, such visualization is difficult to achieve when only using empirical models or laboratory experiments. In conclusion, it is shown that numerical modelling is a useful tool for studying and better understanding of the phase changes and heat and mass transfer in a thermosyphon operation

Influence of climate and air pollution on solar energy development in Serbia

The paper introduces basic information on the geographical location, climate and solar radiation in Serbia. It focuses particularly on the air pollution in Serbia and its influence on the solar cells energy efficiency. Moreover, detailed information on the development of solar energy in Serbia and the examples of the application of the low, medium and high temperature and photovoltaic conversion of solar radiation is provided. The paper also gives an overview of the installed greater capacity solar power stations related to the electricity network and the smaller capacity solar power stations as the independent sources of electricity in Serbia. In conclusion, the paper stresses Serbia’s favourite climate and other conditions for the prospective successful development of solar energy

Influence of climate and air pollution on solar energy development in Serbia

The paper introduces basic information on the geographical location, climate and solar radiation in Serbia. It focuses particularly on the air pollution in Serbia and its influence on the solar cells energy efficiency. Moreover, detailed information on the development of solar energy in Serbia and the examples of the application of the low, medium and high temperature and photovoltaic conversion of solar radiation is provided. The paper also gives an overview of the installed greater capacity solar power stations related to the electricity network and the smaller capacity solar power stations as the independent sources of electricity in Serbia. In conclusion, the paper stresses Serbia's favourite climate and other conditions for the prospective successful development of solar energy

Iskorišćenje sirovog otpada iz restorana za adsorpciju boja

This paper has demonstrated the valorization of inexpensive and readily available restaurant waste containing most consumed food and beverage residues as adsorbents for methylene blue dye. Coffee, tea, lettuce and citrus waste have been utilized without any pre-treatment, thus the adsorption capacities and dye removal efficiency were determined. Coffee waste showed the highest adsorbent capacity, followed by tea, lettuce and citrus waste. The dye removal was more effective as dye concentration increases from 5 up to 60 mg/L. The favorable results obtained for lettuce waste have been especially encouraged, as this material has not been commonly employed for sorption purposes. Equilibrium data fitted very well in a Freundlich isotherm model, whereas pseudo-second- order kinetic model describes the process behavior. Restaurant waste performed rapid dye removal at no cost, so it can be adopted and widely used in industries for contaminated water treatment.Metilen plavo je bazna boja sa strukturom heterocikličnog aromatičnog jedinjenja, koja se u dobu savremenog društva često koristi za bojenje raznih tipova materijala. Efluenti iz industrije boja predstavljaju jednu od najproblematičnijih vrsta otpadnih voda za tretiranje, usled njihove velike biološke i hemijske potrebe za kiseonikom. Pored toga, toksičnost i teško razgradiva priroda boja mogu značajno uticati na fotosintetičku aktivnost vodenog sveta. Adsorpcijom na čvrstim nosačima mogu se ukloniti, odnosno, svesti na minimum razni tipovi zagađivača, zbog čega ova tehnika ima široku primenu u kontroli zagađenja voda. S tim u vezi, ispitivana je mogućnost iskorišćenja sirovog otpada iz restorana za adsorpciju i uklanjanje boje metilen plavo iz vodenih rastvora. U radu su određivani adsorpcioni kapaciteti otpadnih sirovina najčešće konzumiranih namirnica, uključujući kafu, čaj, zelenu salatu i mešavinu citrusnog voća (citrusa). Proces adsorpcije izveden je u šaržnom režimu, uz mešanje na tresilici, u uslovima ambijentalne temperature. Efikasnost procesa praćena je u zavisnosti od promene koncentracije boje u radnim rastvorima. Pokazano je da otpadna kafa ispoljava najviši adsorpcioni kapacitet, a za njom otpadni čaj, zelena salata i citrusi, redom. Nakon 30 min odigravanja reakcije, na kafi se vezalo gotovo 90%, dok na čaju 80%, zelenoj salati 60% i citrusima 30% od početne koncentracije rastvora boje. Vezivanje boje na adsorbentima bilo je efikasnije u slučajevima kada je koncentracija rastvora boje rasla od 5 do 60 mg/L. Na osnovu ispitivanja najčešće primenjivanih modela izo- termi za definisanje adsorpcione ravnoteže, pronađeno je da su ravnotežni podaci, u slučajevima svih vrsta adsorbenata, bili u skladu sa Frojndlihovom adsorpcionom izotermom. S tim u vezi, smatra se da je proces odigravanja reakcije baziran na interakcijama između molekula boje i funkcionalnih grupa na heterogenoj površini adsorbenata. Kinetika i mehanizam reakcija opisani su po principu modela pseudo-drugog reda, koji se zasniva na pretpostavci da hemisorpcija, odnosno stvaranje hemijskih veza između adsorbenta i adsorbata, kontroliše celokupan tok reakcija. Iskorišćenjem sirovog otpada iz restorana može se doći do ekonomski isplativog rešenja za brzo i efikasno uklanjanje toksičnih i teško raz- gradivih boja iz vodenih rastvora. Smatra se da ova vrsta otpadnog materijala može naći svoju primenu u brojnim adsorpcionim procesima, u prvom redu onim koji se zasnivaju na tretmanima prečišćavanja otpadnih i pijaćih voda

Thermal vision based intelligent system for human detection and tracking in mobile robot control system

This paper presents the results of the authors in thermal vision based mobile robot control. The most important segment of the high level control loop of mobile robot platform is an intelligent real-time algorithm for human detection and tracking. Temperature variations across same objects, air flow with different temperature gradients, reflections, person overlap while crossing each other, and many other non-linearities, uncertainty and noise, put challenges in thermal image processing and therefore the need of computationally intelligent algorithms for obtaining the efficient performance from human motion tracking system. The main goal was to enable mobile robot platform or any technical system to recognize the person in indoor environment, localize it and track it with accuracy high enough to allow adequate human-machine interaction. The developed computationally intelligent algorithms enables robust and reliable human detection and tracking based on neural network classifier and autoregressive neural network for time series prediction. Intelligent algorithm used for thermal image segmentation gives accurate inputs for classification. [Projekat Ministarstva nauke Republike Srbije, br. TR35005