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Search Results: 1 - 10 of 1877 matches for " Milena Vukmirovi? "
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Redesigning the network of pedestrian spaces in the function of reduction of CO2 emission. Case study: Pan evo and Vr ac
?uki? Aleksandra,VukmiroviMilena
Spatium , 2012, DOI: 10.2298/spat1227031d
Abstract: Research problem. The research problem is the increase of GHG and CO2 emissions in the transport sector, i.e. the intensification of urban transport activity in Serbia during the last 15 years. Focusing on redesigning of pedestrian networks as well as understanding the connections between urban design and pedestrian movement, the walkable environment could be achieved. In addition, as a direct result, a contribution would be made to a decrease of GHG and CO2 emission. Methodology. The following methods were used: analysis of the readability of open spaces, analysis of contents, rhythm and transparency on the ground floor of buildings and analysis of the intensity of use of open spaces using the Space Syntax method. Results. The results show a proportional relation between characteristics on ground floors of buildings and the intensity of pedestrian movement. Also, they enable the establishing of general recommendations for designing the immediate pedestrian environment and upgrading the quality of open public spaces. Conclusion. The improvement of the quality of pedestrian environment would have as its direct consequence greater use of open public spaces, and thus also increased intensity of pedestrian movement. In this manner, people would face a better quality and broader selection of contents and spaces.
Walking as a Climate Friendly Transportation Mode in Urban Environment Case Study: Belgrade
Aleksandra ?uki?,Milena Vukmirovi
International Journal for Traffic and Transport Engineering , 2011,
Abstract: A large percent of CO2 (carbon dioxide) emissions in Serbia originate from transport. In the last two decades, the number of private car users in Belgrade evidently increased compared to the number of users of environmentally friendly modes of transport. The purpose of this paper is to present an overview of approaches to the improvement of the physical aspect of the open public spaces, which aim to increase the number of users of climate friendly modes of transport, particularly walking. Research was done using three methods: observation of the intensity of pedestrian movement in relation to different periods during the day, direct surveys of citizens and the evaluation of immediate pedestrian surroundings. Three kinds of results were obtained: the trends and concentration of pedestrian movement along the main street lines; the attitude of citizens pertaining to reliable pedestrian movement and elements which contribute to their commitment to walking; and the rhythm of activity units, transparency, and variety of activities on the ground floor of buildings. The contribution of the study is in combining different research methods. The interpretation of the results forms the basis for directing future research and campaigns on topics of climate friendly modes of transport in urban areas.
Non-equilibrium Optical Conductivity in Materials with Localized Electronic States
Veljko Jankovi?,Nenad Vukmirovi
Physics , 2014, DOI: 10.1103/PhysRevB.90.224201
Abstract: A wide range of disordered materials contain electronic states that are spatially well localized. In this work, we investigated the electrical response of such systems in non-equilibrium conditions to external electromagnetic field. We obtained the expression for optical conductivity valid for any non-equilibrium state of electronic subsystem. In the case of incoherent non-equilibrium state, this expression contains only the positions of localized electronic states, Fermi's golden rule transition probabilities between the states and the populations of electronic states. The same form of expression is valid both in the case of weak electron-phonon interaction and weak electron-impurity interaction that act as perturbations of electronic Hamiltonian. The derivation was performed by expanding the general expression for AC conductivity in powers of small electron-phonon interaction or electron-impurity interaction parameter. Applications of the expression to two model systems, a simple one- dimensional Gaussian disorder model and the model of a realistic three-dimensional organic polymer material, were presented, as well.
Dynamics of exciton formation and relaxation in photoexcited semiconductors
Veljko Jankovi?,Nenad Vukmirovi
Physics , 2015,
Abstract: We investigate the dynamics of the exciton formation and relaxation on a picosecond time scale following a pulsed photoexcitation of a semiconductor. The study is conducted in the framework of the density matrix theory complemented with the dynamics controlled truncation scheme. We truncate the phonon branch of the resulting hierarchy of equations and propose the form of coupling among single-phonon-assisted and higher-order phonon-assisted density matrices so as to ensure the energy and particle-number conservation in a closed system. Time scales relevant for the exciton formation and relaxation processes are determined from numerical investigations performed on a one-dimensional model for the values of model parameters representative of a typical organic and inorganic semiconductor. The exciton dynamics is examined for different values of central frequency of the exciting field, temperature, and microscopic model parameters, such as the strengths of carrier-carrier and carrier-phonon couplings. We find that for typical organic semiconductor parameters, formation of bound excitons occurs on a several-hundred-femtosecond time scale, while their subsequent relaxation and equilibration takes at least several picoseconds. These time scales are consistent with recent experimental studies of the exciton formation and relaxation in conjugated polymer-based materials.
Spin relaxation in CdTe quantum dots with a single Mn atom
Marko D. Petrovi?,Nenad Vukmirovi
Physics , 2012, DOI: 10.1103/PhysRevB.85.195311
Abstract: We have investigated spin relaxation times in CdTe quantum dots doped with a single Mn atom, a prototype of a system where the interaction between a single charge carrier and a single spin takes place. A theoretical model that was used includes the electron-Mn spin exchange interaction responsible for mixing of the states of different spin in the basic Hamiltonian and electron-phonon interaction as a perturbation responsible for transitions between the states. It was found that the dominant electron-phonon interaction mechanism responsible for spin relaxation is the interaction with acoustic phonons through deformation potential. Electron and Mn spin relaxation times at room temperature take values in the range from microseconds at a magnetic field of 0.5 T down to nanoseconds at a magnetic field of 10 T and become three orders of magnitude larger at cryogenic temperatures. It was found that electron spin-orbit interaction has a negligible effect on spin relaxation times, while the changes in the position of the Mn atom within the dot and in the dot dimensions can change the spin relaxation times by up to one order of magnitude.
On Some Basic Concepts of Genetic Algorithms as a Meta-Heuristic Method for Solving of Optimization Problems  [PDF]
Milena Bogdanovi?
Journal of Software Engineering and Applications (JSEA) , 2011, DOI: 10.4236/jsea.2011.48055
Abstract: The genetic algorithms represent a family of algorithms using some of genetic principles being present in nature, in order to solve particular computational problems. These natural principles are: inheritance, crossover, mutation, survival of the fittest, migrations and so on. The paper describes the most important aspects of a genetic algorithm as a stochastic method for solving various classes of optimization problems. It also describes the basic genetic operator selection, crossover and mutation, serving for a new generation of individuals to achieve an optimal or a good enough solution of an optimization problem being in question.
The Importance of Health Records  [PDF]
Milena Marini?
Health (Health) , 2015, DOI: 10.4236/health.2015.75073
Abstract: Health records have played an increasingly important role throughout history as an important legal document for the exercise of individuals’ rights. However, domestic legislation fails to define health records as a legally important collection of health data and documents. Recording facts and storing legally important documents are therefore the tasks of the operator. Using the prescriptive method we will determine which laws are governing the management of medical records, their safety and accessibility. Based on the descriptive method, we will describe the process of handling health records by the provider of health treatment, focusing on exposed regulatory gaps in the area of the protection of the rights of an individual. Through the analysis of the laws governing the management of health records, even after death and operator terminating the service, we will carry out inductive reasoning and provide conclusions regarding the attitude towards health records. Considering different results we can conclude that health information, especially documents relevant to the protection of individual’s rights, is not transparent. Above all, the documents in the collection are not recorded properly, thus allowing for their removal. Even the transfer of health records by the provider of health treatment is not defined, which could result in the disposal of the entire health documentation.
Reduction of wheat middlings using a conventional and eight-roller milling systems
Fi?te? Aleksandar Z.,Vukmirovi? ?uro M.
Acta Periodica Technologica , 2009, DOI: 10.2298/apt0940025f
Abstract: Possibilities for the rationalization of the wheat flour milling process using the eightroller mill on the 1M and 2M passages of the reduction system have been investigated. At the same roll gaps and under the same sieving conditions, the lower flour yield has been obtained using an eight-roller mill compared to the conventional milling system (5-8 %) followed by a higher energy requirements for grinding. By decreasing the roll gap setting and increasing the upper size limit of flour in the process with the eight-roller mill it is possible to increase flour yield and therefore decrease milling energy consumption per unit mass of flour produced without deterioration of flour quality as determined by ash content. With appropriate adjustments of the processing parameters in the eight-roller milling system it is possible to achieve similar milling results to those in the conventional system, while the overall investment, energy and maintenance costs are significantly lower.
The Danube as a development resource: Perception and activities of local administration
?ivadinovi? Ivan,Vukmirovi? Jovanka,Komazec Gordana
Journal of the Geographical Institute Jovan Cvijic, SASA , 2012, DOI: 10.2298/ijgi111031002z
Abstract: The paper presents the results of multidisciplinary studies that were reached during the interviews in the local administrations in 24 cities and municipalities through which the river Danube flows on the territory of the Republic of Serbia. The Danube is an extraordinary resource that links the North and the Black Sea through the Rhine-Main-Danube Canal, and flows through 13 European countries. There are almost 3 million inhabitants on its banks in Serbia, and it is also the region with the largest economic activity in the territory of the Republic of Serbia. Local administrations took responsibility for their own development by making a series of strategic documents related to local economic development in which they analyzed the current situation and predicted development measures and incentives to improve the investment environment. In this paper we analyze the eco-chemical characteristics of water, arrangements of banks and riverbed, supporting infrastructure, business infrastructure, development measures and incentives, as well as cooperation with other local communities in the Danube region. The aim of this study was to determine awareness, knowledge and commitment of decision-making capabilities of local communities on the Danube as a development resource, especially in the context of the modern concept of sustainable development.
Carrier hopping in disordered semiconducting polymers: How accurate is the Miller-Abrahams model?
Nenad~Vukmirovi,Lin-Wang Wang
Physics , 2010,
Abstract: We performed direct calculations of carrier hopping rates in strongly disordered conjugated polymers based on the atomic structure of the system, the corresponding electronic states and their coupling to all phonon modes. We found that the dependence of hopping rates on distance and the dependence of the mobility on temperature are significantly different than the ones stemming from the simple Miller-Abrahams model, regardless of the choice of the parameters in the model. A new model that satisfactorily describes the hopping rates in the system and avoids the explicit calculation of electron-phonon coupling constants was then proposed and verified. Our results indicate that, in addition to electronic density of states, the phonon density of states and the spatial overlap of the wavefunctions are the quantities necessary to properly describe carrier hopping in disordered conjugated polymers.
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