On injection-ejection fluid influence through different accelerating porous surfaces on unsteady 2d incompressible boundary layer characteristics

Through the porous contour in perpendicular direction, the fluid of the same properties as incompressible fluid in basic flow, has been injected or ejected with velocity who is a function of the contour longitudinal coordinate and time. The corresponding equations of unsteady boundary layer, by introducing the appropriate variable transformations, momentum and energy equations and two similarity parameters sets, are transformed into generalized form. These parameters are expressing the influence of the outer flow velocity, the injection or ejection velocity and the flow history in boundary layer, on the boundary layer characteristics. Obtained generalized solutions are used to calculate the distributions of velocity, and shear stress in laminar-turbulent transition of unsteady incompressible boundary layer on different porous contours: circular cylinder, thin elliptical cylinder and aerofoil, whose centers velocities changes in time as a degree functions. The ejection of fluid postpones the boundary layer separation, i.e. laminar-turbulent transition, and vice versa the injection of fluid favors the separation. Boundary layer characteristics are found directly, no further numerical integration of momentum equation

Theoretical and methodological analysis of institutional determination of economic growth – the evaluation of transition countries

Predmet istraživanja doktorske disertacije odnosi se na analizu značaja i mehanizama na koji institucionalna obeležja utiču na efikasnost nacionalnih ekonomija. Pritom, cilj je da se istraživanjem identifikuju relevantne normativne i pozitivne pozicije u pogledu uloge koju institucije imaju u ekonomskim procesima, kao i njihov međusobni odnos i relativna važnost pri uticaju na ekonomske performanse, sa posebnim osvrtom na iskustva privrednih sistema zemalja u tranziciji. Iz tog razloga, analizirane su osobenosti institucija kao jedinica ekonomske analize, raznovrsnost elemenata institucionalne strukture, kroz, naročit, osvrt na interakciju koja se pojavljuje između formalnih i neformalnih institucionalnih pravila. Uslovljenost ekonomskih performansi institucionalnim svojstvima analizirana je iz perspektive teorije transakcionih troškova, kao i teorije vlasničkih prava i mehanizmima kojima oni ostvaruju uticaj na ekonomske performanse. Iz razloga što značajan deo institucionalne strukture nastaje, ali se i menja, u okviru političkog sistema, efekti na ekonomsku aktivnost posmatrani su kroz uticaje koji nastaju kao posledica specifičnosti političkih institucija, odnosno, njihove stabilnosti, forme i centralizovanosti, kao i kvaliteta javnog upravljanja, uticaja rent-seeking-a i političkih konjunkturnih ciklusa. S obzirom da su postojanost i dinamika integralna svojstva svakog segmenta institucionalne strukture, deo istraživanja je orijentisan na analizu osnovnih elemenata, tipova i teorija institucionalnih promena, zavisnost promene institucija od istorijskog institucionalnog, formalnog i neformalnog, nasleđa, kontroverzi u pogledu transplantacije institucija, kao i uzroka institucionalne histereze i neuspeha. Na osnovu empirijskog istraživanja odnosa ekonomskih performansi i institucionalnog kvaliteta, utvrđeno je da nivo per capita dohotka odlučujuće zavisi od kvaliteta institucionalne strukture, efikasne zaštite vlasničkih prava, usklađenosti između formalnih i neformalnih pravila, čime institucionalne promene u pravcu unapređenja svih institucionalnih segmenata predstavljaju neophodnu pretpostavku efikasnijoj ekonomskoj aktivnosti.This paper refers to the analysis of the importance of the institutions and the mechanisms through which the institutional characteristics influence the efficiency of national economies. In this context, the main goals of the research are to identify and explain relevant normative and positive aspects of institutional theory, the way in which institutions affect economic processes, as well as the interrelation and relative importance of different institutional units in their influence on economic performance, with special emphasis on the experience of transition countries. For this purpose, the author has reviewed the uniqueness of institutions as units of economic analysis, the diversity of the elements of institutional structure, with the particular accent on interaction between formal and informal institutional rules. Dependence of economic performance upon the institutional characteristics has been analyzed from the perspective of transaction-cost theory, as well as the theory of property rights. Special attention is paid to the mechanism through which the property rights exercise their influence upon the efficient operation of economic system. Bearing in mind the fact that the important part of institutional structure is made within a political process, the effects of institutions are observed through the influences derived from political stability, political regime and the level of administrative and fiscal centralization. The quality of governance, the impact of rent-seeking activities and the influence coming from political and business cycles are additional important features in this regard. Since the institutions display the persistence and changeability at the same time, the important part of the research is dedicated to the analysis of different types and theories of institutional changes, the dependency of changes on the past formal and informal institutional development, the issues related to the transplantation of institutions and the causes of institutional hysteresis. Based on the empirical part of the thesis, we have reached the conclusion that the level of per capita income largely depends on the quality of institutions, especially the protection of property rights, as well as the harmonization between formal and informal institutions. This makes good institutions a decisive and long-lasting factor of the success and efficiency of national economies

Regional policy funds: how prepared is Serbia to access European Union regional policy funds?

Bearing in mind that Serbia is dealing with serious and challenging development issues, especially scarce of financial resources, it is extremely important to establish institutional and legal framework for drawing financial means from European Union regional policy funds. The importance and potential support of these funds for Serbia is visible through the fact that European Union financial capacity for the purposes of the equal regional development is more ten times bigger than Serbian yearly GDP. One of basic prerequisites for stable and continuous social and economic development is equal regional growth of all parts of country and as one of basic European values should contribute to planning and application of development policy. As of 2010 Serbia has 5 statistical regions with strong multilevel disparities. One of the key challenges in the future will be to find the way to mitigate differences and European Union regional funds will play inevitable roll. The authors are trying to identify, to analyze and to emphasize decisive obstacles in drawing and exploiting recourses from regional funds. These obstacles are particularly present in facilitating development of under- and undeveloped areas, old and mainly devastated infrastructure, ecological policy matters and extremely low employment rates

Monetary freedom and economic growth in New European Union Member States

This paper analyses the relationship between monetary freedom (index measured by the Heritage Foundation) and real economic growth of 11 new member states of the European Union. 19-year panel data regression with fixed effects over the period of 1997– 2015 reveals that the real GDP growth of the selected countries is positively affected by the degree of monetary freedom. However, the relationship between monetary freedom and real GDP growth has weakened after the global recession of 2008. Monetary freedom was not jeopardized during the crisis, while real GDP growth declined significantly in most of economies studied

Reconstruction of the aero-mixture channels of the pulverized coal plant of the 100 MW power plant unit

After the last revitalization of thermal power block of 100 MW in TPP 'Kostolac A', made in the year 2004, during the operation of the plant, pulverized coal deposition often occurred in horizontal sections of the aero-mixture channels. Deposition phenomenon manifested itself in places ahead of spherical compensators in the direction of flow of pulverized coal to the burners, due to unfavorable configuration of these channels. Coal dust deposited in the channels dried and spontaneously combusted, causing numerous damage to channels and its isolation as well as the frequent stoppage of the operation for necessary interventions. The paper presents the original solution of reconstruction of aero-mixture channels which prevented deposition of coal dust and its eventual ignition. In this way the reliability of the mill plant is maximized and higher availability of boiler and block as a whole is achieved

Pojava trombe na Novom Beogradu 24. maja 2012. godine - sinoptička analiza

In this study we have analysed a case of the landspout across Novi Beograd on 24 May 2012. We have used a synoptic analysis method in the research and the description of the landspout event is based on visual evidence and photographs. According to the available data, it can be concluded that there were favourable conditions for a landspout development since there was a process and an increased amount of instability. The landspout occured within the northeast stream which moved over Belgrade and further toward the southeast and west. Based upon synoptic data analysis, it can't be said that there was a cold air advection. Surface air was warm enough, but not the air in the upper layers of the atmosphere. The conditions for a landspout development were favourable - high relative air humidity and increased vertical and horizontal air currents.U radu je prikazan slučaj pojave trombe 24.05.2012. na Novom Beogradu. U istraživanju je korišćen metod sinoptičke analize, a opis pojave trombe temelji se na vizuelnom opažanju i fotografijama. Prema raspoloživim podacima može se zaključiti da su uslovi za razvoj trombe bili povoljni, jer je postojao i proces i povećana energija nestabilnosti. Tromba se javila u sklopu severoistočne struje koja se premeštala preko Beograda dalje na jugozapad i zapad. Na osnovu analize sinoptičkog materijala, ne može se reći da se radilo o advekciji jako hladnog vazduha. Bilo je dovoljno toplote u prizemlju, ali ne i po visini. Postojali su povoljni uslovi za nastanak trombe - visoka vlažnost vazduha, izražena vertikalna i horizontalna strujanja

Landspout across Novi Beograd, 24 may 2012: Synoptic analysis

In this study we have analysed a case of the landspout across Novi Beograd on 24 May 2012. We have used a synoptic analysis method in the research and the description of the landspout event is based on visual evidence and photographs. According to the available data, it can be concluded that there were favourable conditions for a landspout development since there was a process and an increased amount of instability. The landspout occured within the northeast stream which moved over Belgrade and further toward the southeast and west. Based upon synoptic data analysis, it can’t be said that there was a cold air advection. Surface air was warm enough, but not the air in the upper layers of the atmosphere. The conditions for a landspout development were favourable - high relative air humidity and increased vertical and horizontal air currents

Technical solution for use of gas turbine exhaust gases in the existing steam boilers in MSK Kikinda

U okviru energetike Metanolsko-sirćetnog kompleksa u Kikindi nalaze se, pored procesnog kotla i ostale prateće opreme, tri jednaka parna kotla proizvodnje 'Minel-Kotlogradnja' koji su predviđeni za sagorevanje prirodnog gasa, mazuta i procesnih gasova. U cilju povećanja energetskog kapaciteta energane MSK Kikinda predviđena je ugradnja jedne gasne turbine snage 14 MW. S obzirom da izduvni gasovi iz gasne turbine imaju relativno visoku temperaturu i veliku količinu neiskorišćenog kiseonika iz vazduha, predviđeno je da se oni podele na dve jednake struje i da se uvedu u dva postojeća parna kotla produkcije od po 16,67 kg/s (60 t/h). Da bi se iskoristila ova toplota izduvnih gasova, kao i kiseonik sadržan u njima, neophodno je prvo zameniti postojeće gorionike i izvršiti neophodne rekonstrukcije grejnih površina u vertikalnom konvektivnom gasnom kanalu parnog kotla. Osim toga potrebno je proveriti da li postojeći ventilator za dimne gasove može da zadovolji novi režim rada pri kome se u jedan kotao uvodi polovina izduvnih gasova turbine. .Within the energy system in Methanol & Acetic acid Complex (MSK) in Kikinda, beside process boiler and auxiliary equipment, there are three identical steam boilers made by 'Minel Kotlogradnja', provided for combustion of natural gas, fuel oil, and process gases. To increase capacity of the power plant in MSK Kikinda, installation of one 14 MW gas turbine is planed. Since the exhaust gases are at the relatively high temperature and contain large quantity of oxygen, it is specified to split exhaust gas into two equal streams and introduce them into two existing steam boilers, each having production of 16,67 kg/s (60 t/h). In order to use heat as well as oxygen from the exhaust gases in the existing boilers, it is necessary to replace the existing burners and to reconstruct heat exchangers in the vertical convective gas channel. Besides, it is necessary to verify if the existing flue gases fan can comply with the new operating regime, during which a half of the turbine exhaust gas is introduced into the steam boiler.

ANALYSIS OF THE DEGREE OF APPLICATION OF ELECTRONIC AND MOBILE TRADE IN AIRLINE SECTOR

In this paper, the authors study and analyze the degree of application electronic and mobile commerce in the airline sector, arguing that modern information and communication technologies provide a powerful tool for airlines and can significantly affect their operations, structure and strategy. In the airlines sector Internet is considered to be the most important technological revolution, because upon its appearance the booking systems ceased to be passive computer archives and records and become active operating systems that with immense speed transform the air traffic. In the mid 80's years, specific types of information systems appeared and these were global distribution systems which were designed for the distribution of tourism products, whose implementation on the website gave access to the airlines to  an electronic trading and enabled them to carry out the provision of services and conduct the sale of air tickets on the Internet. However, the development of technology, the appearance of smart phones and numerous other factors today necessitate airlines to access mobile commerce and make their services available to smart phone users as well as on the website

Exploring the motives of employees in Serbia

Motivacija je jedan od značajnijih faktora u menadžmentu savremenih organizacija. Organizacija bi bila efikasnija kada bi bili izbalansirani lični interesi i interesi organizacije. Značaj motivacije ogleda se u činjenici da organizacija ostvaruje ciljeve i rezultate na osnovu radnih učinaka zaposlenih. Većina poslodavaca danas želi da im zaposleni budu motivisani da rade, da preuzmu inicijativu i poboljšavaju način rada, ali ne razumeju šta zaista motiviše osobu. Da bi se utvrdilo kako zaposleni radnici, različitih ličnih karakteristika i uslova rada, vrednuju motivacione faktore, istraživanje je sprovedeno u dve organizacije. Sagledavanjem i upoređivanjem rezultata sprovedenog istraživanja utvrdili smo neke od pokretačkih, motivacionih faktora, njihove međusobne odnose i njihov uticaj na efikasnost organizacije.Motivation is one of important issues in the management of modern organizations. The organization would be more effective if they had balanced personal interests and the interests of the organization. The importance of motivation is reflected in the fact that the organization achieves the objectives and results based on the work performance of employees. Most employers today want their employees to be motivated to work, take initiative and improve the way of working, but do not really understand what motivates a person. In order to determine how employees, and various personal characteristics and working conditions, evaluate incentives, research was conducted in two organizations. Perceiving and comparing the result of the research we have found some of the driving, motivating factors, their mutual relations and their impact on organizational performance