Slobodan softver kao alternativa komercijalnom u primeni numeričkih metoda i iterativnih postupaka

Computers with the help of proper software usage enables efficiency in work as well as the conducting of experiments, developments, simulations and data processing which allows specific conclusions to be drawn. The programming languages that have been developed in past decades gave computer users more opportunity to think outside the box. Due to the rapid development and complexity of the programming languages and their syntax, the demand for a much faster and simpler problem-solving tool was created in order to cater situations which require the need to have the tool created in the first place. Today, the most popular and sophisticated programme used in industrial environments is Matlab as it is applicable in various fields of sciences - from numerical calculations to complex simulations. However, Matlab is a commercial programme. In order for it to be used, financial incentives must be prioritised which often is a disadvantage for students and educational institutions as it is costly. In this paper a few free software solutions will be considered as alternatives to commercial software solutions.Publishe

Primena metode atomske apsorpcione spektrofotometrije (AAS) za određivanje sadržaja teških metala u fosfogipsu

Phosphogypsum is formed as a by-product in the process of 'green' phosphoric acid production. This is done in the so called 'wet process' by the action of sulphuric acid on raw phosphate at low temperature ( lt 100 °C). Despite the same molecular formula and marked similarity with natural gypsum, phosphogypsum contains more than 50 impurities, and this is directly connected with the type of phosphate used in the production cycle. The aim of this paper was to consider the possibility of using phosphogypsum for amelioration of solonetz soil, bearing in mind its content of heavy metals, which are rather toxic for human organism and which can be transferred from soil to various plants used in human nutrition. On the other hand, there are very few data in the literature about the determination of heavy metals in phosphogypsum. The content of heavy metals in phosphogypsum was determined by atomic absorption spectrophotometry because this method has broad application in ana­lytical practice due to its high sensitivity, selectivity and precision. The results of the investigation indicate the following average content of heavy metals (in ppm): Fe-785, Pb-45, Zn-45, Cd-7, Mn-8, Co-10, Ni-20 and Cu-17. For the investigation of the effect of phosphogypsum on solonetz soil the following points were taken into consideration: maximum recommended dose of phosphogypsum (7 t/ha) for the amelioration of solonetz soil and the weight of soil layer (from 0 to 20 cm) having an area of 1 ha. The results obtained indicate that the amounts of heavy metals that are introduced into the soil with 7 t/ha of phosphogypsum are in the range from 0.035 to 0.8% of their maximum permissible content for arable soils. This means that only long-term application of phosphogypsum would introduce significant amounts of these elements into the soil.Procesom dobijanja 'zelene' fosforne kiseline tzv. 'mokrim postupkom', dejstvom sumporne kiseline na sirovi fosfat na niskoj temperaturi ( lt 100 °C) kao nus-proizvod nastaje - fosfogips (sa faktorom 5:1, u odnosu na H3PO4). Uprkos istoj molekulskoj formuli i izraženoj sličnosti sa prirodnim gipsom, fosfogips sadrži preko 50 vrsta nečistoća, što je u direktnoj vezi sa vrstom fosfata koji je korišćen u proizvodnom ciklusu. Cilj rada bio je razmatranje mogućnosti primene fosfogipsa za melioraciju soloneca, sa aspekta sadržaja teških metala, koji su izuzetno toksični i kumulativni za čovekov organizam, a iz zemljišta prelaze u biljke, kojima se čovek hrani. Sa druge strane, u literaturi se nalaze veoma oskudni podaci o ispitivanju sadržaja teških metala u fosfogipsu. Sadržaj teških metala u fosfogipsu određivan je metodom atomske apsorpcione spektrofotometrije (AAS), budući da je to metoda koja je našla veliku primenu u praksi usled visoke osetljivosti, selektivnosti i preciznosti. Rezultati ispitivanja su pokazali sledeći sadržaj teških metala (u ppm): Fe-785, Pb-45, Zn-45, Cd-7, Mn-8, Co-10, Ni-20, Cu-17. Za ispitivanje uticaja primene fosfogipsa za melioraciju soloneca, uzeta je u obzir preporučena maksimalna norma za gipsovanje soloneca od 7 t/ha zemljišta i težina sloja debljine od 0 do 20 cm a površine 1 ha. Dobijeni rezultati su pokazali da se preporučenom maksimalnom normom za gipsovanje soloneca fosfogipsom unosi po 1 ha zemljišta od 0,035 do 0,8% od maksimalno dozvoljenog sadržaja teških metala - MDK vrednosti, što znači da bi tek višegodišnjom upotrebom fosfogipsa došlo do unošenja značajnijih količina ovih elemenata u zemljište. Kako se proces melioracije soloneca najčešće vrši u intervalu od 5 do 6 godina, unošenje teških metala bilo bi u zanemarljivoj količini i bez uticaja na životnu sredinu

How Does Intellectual Capital Affect the Financial Performance of Micro, Small, and Medium-Sized Hotel Companies?

Theoretical background: Intellectual capital is often considered a critical resource, especially for micro, small, and medium-sized, as well as service companies. Human, structural, and relational capital are often listed as the main components of intellectual capital. This study complements the studies on the impact of intellectual capital and its components on the financial performance of hotel companies in developing economies. Purpose of the article: The study aims to examine the impact of the efficiency of intellectual capital and its components on the financial performance of micro, small, and medium-sized hotel companies in Serbia. The results of the study can be of importance for hotel managers in their efforts to make adequate business decisions and improve the financial performance of hotel companies. Research methods: The sample includes 100 micro, small, and medium-sized hotel companies from Serbia with the highest operating revenues in 2019. The efficiency of the intellectual capital and its components is measured by using the modified value-added intellectual coefficient (MVAIC). Financial performance is measured by using the natural logarithm of earnings before interest, taxes, depreciation, and amortization (EBITDA), EBITDA margin, return on assets (ROA) and return on equity (ROE). Ordinary least squares regression is used to examine the impact of intellectual capital and its components on the financial performance of sample hotel companies from 2015 to 2019. Main findings: The results of the study show that intellectual capital efficiency has a positive impact on all four measures of financial performance. They also show that structural capital has the greatest impact on financial performance and that only this component of intellectual capital has a positive impact on all four measures of financial performance. Capital employed has a positive impact on the natural logarithm of EBITDA and ROE, while human capital has a positive impact on the EBITDA margin and a negative on the natural logarithm of EBITDA. Relational capital has a positive impact only on ROA

Kartiranje rizika od poplava

The paper considers the methodology for the mapping flood zones, flood damages and flood risk. The emphasis is on the development of synthetic flood damage functions, used for the determination of the expected annual damages, as the principal parameters for quantification of the flood risk. The methodology is illustrated by two practical examples.U ovom članku se razmatra metodologija kartiranja plavnih područja, šteta i rizika. Težište je na načinu određivanja sintetičkih funkcija potencijalne štete, koje se korite za definisanje očekivane godišnje štete, kao glavnog parametra za kvantifikovanje rizika od poplava. Metodologija je ilustrovana primerima iz naše prakse

Kartiranje rizika od poplava

The paper considers the methodology for the mapping flood zones, flood damages and flood risk. The emphasis is on the development of synthetic flood damage functions, used for the determination of the expected annual damages, as the principal parameters for quantification of the flood risk. The methodology is illustrated by two practical examples.U ovom članku se razmatra metodologija kartiranja plavnih područja, šteta i rizika. Težište je na načinu određivanja sintetičkih funkcija potencijalne štete, koje se korite za definisanje očekivane godišnje štete, kao glavnog parametra za kvantifikovanje rizika od poplava. Metodologija je ilustrovana primerima iz naše prakse

Fizikalna terapija i rehabilitacija pacijenata sa degenerativnim oboljenjima kičmenog stuba (lumbosakralnom stenozom, ankilozirajućim spondilitisom i difuznom idiopatskom hiperostozom)

Spondiloartritisi su degenerativna oboljenja kičmenog stuba, gde se promene javljaju na hrskavici, subhondralnoj kosti, sinovijalnoj membrani, kao i na periartikularnim mekim tkivima. Terapija se sastoji u davanju analgetika i nesteroidnih antiinflamatornih lekova. Takođe se savetuje da se uskrate sva velika fizička naprezanja, a preporuču- ju se mirovanje uz blage šetnje i primena fizikalne terapije. Suština rehabilitacionog programa, kod pacijenata kod kojih je došlo do funk- cionalne ili strukturne disfunkcije kičmenog stuba, nije u doslovnom uklanjanju anatomskih i fizioloških oštećenja, već u uspostavljanju op- timalnog funkcionalnog stanja organizma prema njegovim preostalim mogućnostima i poboljšanju kvaliteta života. Fizikalna terapija ima zadatke da: • uspostavi narušene funkcije organizma, odnosno da izvrši njihovu kompenzaciju, • poboljša narušenu autoregulaciju i što je moguće više, redukuje fi- zičku nesposobnost nakon povrede ili oboljenja. U okviru radionice, biće prikazane procedure koje se koriste za terapiju degenerativnih oboljenja kičmenog stuba: elektroterapija, fo- toterapija, magnetoterapija i kineziterapija, a koje na organizam delu- ju analgetski, simpatikolitično, izazivaju vazodilataciju, omogućavaju povećanje obima pokreta, jačaju grubu motornu snagu i poboljšavaju koordinaciju. Ciljevi lečenja spondiloartropatija su: • smanjiti inflamaciju (bol i ukočenost), • smanjiti ograničenje pokreta kičmenog stuba i usporiti razvoj anki- loze i • sprečiti komplikacije bolesti (kifozu, kifoskoliozu, fleksione kontrak- ture). Potrebno je napomenuti da se šema rehabilitacionog programa prilagođava svakom pacijentu pojedinačno, pa je zato najsigurnije, da bi se izbegle greške u lečenju, strogo se pridržavati definisanih prin- cipa terapije

Compromised glutathione-dependent redox system of chronically-isolated rats: a harmfull side effect of clozapine

Changes in glutathione (GSH)-related systems are implicated in depressive disorders. Since chronic psychosocial stress contributes to depression, we investigated the effects of 21d of chronic social isolation (CSIS) stress, an animal model of depression, as well as chronic administration of clozapine, an atypical antipsychotic, on GSH content, glutathione peroxidase (GPx) and glutathione reductase (GLR) in the prefrontal cortex of rats. Increased GPx protein expression and its activity in clozapine-treated (controls or chronically-isolated) rats as well as in CSIS group were found. Nonetheless, clozapine administration caused decrease in GSH content but no effects on GLR in controls and CSIS group. Data indicate that CSIS compromises GSH-dependent redox system promoting oxidative stress in rat prefrontal cortex which can’t be protected by clozapine. Moreover, clozapine administration in controls has a harmful side effect on this redox system

Selection of plum varieties for planting by applying the AHP method

Fruit growing represents activity that deals with a large number of people in Serbia. When we speak of plums, it is like a traditional fruit species raises in Serbia for many years and is of great economic importance. It can be said that the production of plum is a symbol of Serbia. Agricultural producers aim to realize maximum results and fruit of all kinds of fruit. The success of dealing with fruit production is largely dependent on the quality of the selection of varieties of fruit. The selection of varieties can be made based on many criteria. The complexity of decision problems due to the appearance of a large number of criteria requires the use of a particular method for multicriteria decision making. The subject of this work is the selection of plum varieties for planting through the AHP method

Practical assessment of grinding capacity and power consumption based on hardgrove grindability index and coal characteristics

This paper analyzes the effects of coal grindability and its characteristics on the grinding capacity and power consumption for beater wheel mill during exploitation in thermal power plant TENT B in Obrenovac, Serbia. For this purpose, experiments were made on the mill, before and after its reconstruction. Experiments included the determination of grinding capacity, mill power consumption, and laboratory analysis of coal characteristics and Hardgrove grindability index (HGI). The analysis of experimental results found that the grinding capacity has a negative correlation with the ash content in coal. Moisture content in analysis sample of coal has a positive correlation with the consumption of electricity and grinding capacity. Between the grinding capacity and the value of HGI exists a negative correlation. Analysis of the influence of grindability of coal and coal characteristics on grinding capacity and energy consumption was carried out. Based on coal characteristics and values of HGI, mathematical expressions were derived for the calculation of grinding capacity and electric energy consumption. In addition, ability to predict specific power consumption of the mill on the basis of HGI values, were carried out. Specific power consumption obtained from HGI values showed good agreement with the experimentally determined specific power consumption of the mill