89 research outputs found
Methodological framework for shrinking cities case study research: northwest region of Bosnia and Herzegovina
Urban shrinkage is an increasingly global phenomenon that equally affects large cities and small towns, as a result of complex social, economic and spatial changes, thereby causing the emergence of the so-called shrinking cities. This paper presents a model for the analysis of shrinking cities tailored to the needs of research in circumstances of insufficiently developed statistical systems for monitoring the complex structure of changes affecting cities. The model is based on an analysis of international research projects focused on this research problem, analysis of the legislative framework in Bosnia and Herzegovina (B&H) and analysis of available data. The proposed model is tested on the territory of northwest B&H (Republic of Srpska - RS) and aims at mapping, analysis and typological classification of shrinking cities. It is assumed that the process of urban shrinkage is more prevalent than that of urban growth, and that most of the cities and towns in northwest B&H (RS) are faced with this problem, which is considerably more acute when it comes to small and medium-sized towns of this region
First-principles calculations of the vibrational properties of bulk CdSe and CdSe nanowires
We present first-principles calculations on bulk CdSe and CdSe nanowires with
diameters of up to 22 \AA. Density functional linear combination of atomic
orbitals and plane wave calculations of the electronic and structural
properties are presented and discussed. We use an iterative, symmetry-based
method to relax the structures into the ground state. We find that the band gap
depends on surface termination. Vibrational properties in the whole Brillouin
zone of bulk CdSe and the zone-center vibrations of nanowires are calculated
and analyzed. We find strongly size-dependent and nearly constant modes,
depending on the displacement directions. A comparison with available
experimental Raman data is be given
Schr\"odinger's pure-state steering completed
Schroedinger investigated entanglement in two-particle state vectors by
assuming measurement finding out if the nearby particle is in a given state
vector or not. Without interaction with the distant particle, just on account
of the entanglement, the distant particle is steered into a certain state
vector. In Schroedinger's finite-dimensional case thus any distant-particle
state vector can be reached. This theory was extended to infinite-dimensional
spaces by the author. The present article completes the extension by throwing
light on the fine structure of steering.Comment: 10 pages, Latex2e, no figure
Urban shrinkage in a 'shrinking' serbia - the approach to a global phenomenon in a local context
The initial purpose of this research was to understand the basic patterns of urban shrinkage in Serbia. Urban shrinkage, a common phenomenon in post-socialist countries, is a novelty, albeit very present in Serbia today. Despite presenting a huge challenge for the future of the country, it has not been studied sufficiently at any level. To understand this situation, the first "task" would certainly be to identify which cities in Serbia can be considered as shrinking in a local context. The research will focus on this issue through the development of four models of shrinking cities in Serbia according to globally based factors of urban shrinkage. The aim of the paper is to clarify the potential of their use and to explore the possible locally-based factors of urban shrinkage
Defining methodology of integrative adaptive management for shrinking cities - case study Prijedor
Узајамно деловање негативних друштвених и економских фактора на глобалном
нивоу, крајем XX и почетком XXI века, резултовало је поларизацијом просторног
развоја која је произвела глобалне градове који су успели да се интегришу у глобалну
мрежу, али је довела и до раста неједнакости међу градовима и појаве глобалног
феномена г ра д ов а у опа д ању (shrinking cities)...The interaction of negative social and economic factors at the global level, in the late
twentieth and early twenty-first century, resulted in the polarisation of spatial development
that produced the global cities which managed to integrate into the global network, but also
led to an increase in disparities between cities and the emergence of global phenomenon of
sh r in k i ng c i t i e s . Research shows that the phenomenon of urban stagnation is
increasingly widespread in Central and Eastern Europe, the United States, developed
countries in Asia, North America and Australia..
An eco-physiological and biotechnological approach to conservation of the world-wide rare and endangered aquatic liverwort Riella helicophylla (Bory et Mont.) Mont.
The rare aquatic liverwort Riella helicophylla (Bory et Mont.) Mont., inhabitant of temporary shallow ponds around the Mediterranean basin, is considered threatened throughout its distribution range. In addition, little is known of its biology and ecology or of its role in such an important ecosystem where envi- ronmental conditions vary yearly in unpredictable ways. In these variable habitats, due to the seasonal fluc- tuation of water levels, there is no guarantee of yearly spore input into the spore bank. Spore germination rate and the effects of different culture media in an axenic culture establishment, as well as propagation proce- dures of R. helicophylla, were tested. New insights into the ecology and biology of R. helicophylla are given. Spore dormancy is documented, and the protocols for the in vitro culture establishment, propagation and ac- climatization of this liverwort are developed. Dry storage at 20 ± 2 °C for about three months broke the dor- mancy of spores, which subsequently germinated in a high percentage (over 90%). A two phase (solid and liquid) culture media system was developed for the purpose of achieving fully developed gametophytes. The liquid phase contained electrolytes simulating brackish water
Determination of milk heat stability by the cup method
Direktne i indirektne metode koje su se do sada primjenjivale za ispitivanje termostabilnosti svježeg mlijeka su tehnički složene i iziskuju dosta vremena i rada. Za rutinska ispitivanja autori su konstruirali čašice zapremine 8 ccm od valjanog aluminija. U čašicu se odmjeri 2 mL mlijeka, zatim, se ova hermetički zatvori poklopcem s navojem i zagrijava u termostatu na 150 °C. Vrijeme do časa grušanja (termostabilnost) ustanovljuje se povremenim promatranjem izgleda mijleka u čašici. Autori zaključuju da je mlijeko koje ima veću termostabilnost od 7 minuta, pogodno za UHT sterilizaciju
High temperature electrolysis, Brayton power cycle and methanol production
Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.This paper presents heat exchanger technology that is the key technology in three processes i.e. hydrogen and oxygen production using high temperature steam electrolysis; Brayton power cycle where sCO2 is recycled to the combustor in aim to reduce high temperature achieved after natural gas is combusted in oxygen and methanol production. These processes are combined into one process that enables methanol and electricity production with 100% carbon capture.
Industrial hydrogen has been used in many different applications e.g. oil refineries, ammonia and methanol production with demand that has been increasing continuously and expect to rise in days to come. To date, Steam Methane Reforming (SMR) process where methane (natural gas) reacts with steam at high temperature in an endothermic reaction has been adopted as the conventional way to produce industrial hydrogen.
However, there are other processes developed to produce hydrogen with electrolysis of steam being one of them. Steam electrolysis includes few different cell types with Solid Oxide Electrolysis Cell (SOEC) that operates at high temperatures being considered in this paper. It needs to be noted that hydrogen produced by steam electrolysis is of highest purity.
As steam electrolysis requires electricity which can be provided by either renewable or non-renewable energies, this paper is considering electricity provided by renewable energies (wind, solar or hydro) and electricity produced by Brayton power cycle, so hydrogen is produced without Green House Gas (GHG) emission.
To reduce electricity requirement for steam electrolysis diffusion bonded heat exchangers are employed to use heat from turbine exhaust gas and heat realized during hydrogenation of CO2 in methanol production.dc201
Analiza i ispitivanje nemetalnih uključaka za čelik 100Cr6
Steel 100Cr6 belongs to a group of hardened steels, which are applicable for production of rolling element parts. Because of specific working conditions, a proper chemical composition is required with a minimum content of nonmetallic inclusion. In this paper, the research results of presence the nonmetallic inclusions and their chemical composition are presented for the steel produced in vacuum and open induction electric furnace and their influence on the prescribed properties for this steel. The optical and scanning electronic microscope are used to identify presence and the chemical compositions of nonmetallic inclusions.Čelik 100Cr6 pripada grupi prokaljivih čelika koji su prvenstveno našli primjenu u proizvodnji dijelova kotrljajućih ležajeva. Glede posebnih uvjeta rada za ovu vrstu čelika se zahtijeva propisani kemijski sastav sa minimalnim prisustvom nemetalnih uključaka. U ovom radu su predstavljeni rezultati ispitivanja prisustva nemetalnih uključaka i njihov kemijski sastav za čelik 100Cr6 proizveden u vakuumskoj i otvorenoj indukcionoj elektro peći te njihov uticaj na svojstva propisane normom za ovu vrstu čelika. Ispitivanje prisustva nemetalnih uključaka kao i analiza kemijskog sastava urađena je primjenom optičkog i skening elektronskog mikroskopa
Synthesis and Microstructural Properties of Fe-TiO 2 Nanocrystalline Particles Obtained by a Modified Sol-Gel Method
Abstract. A series of iron/titanium oxide nanocrystalline particles with Fe/Ti molar ratios up to 0.15 were synthesized by a modified sol-gel technique using Ti(IV)-isopropoxide and anhydrous Fe(II)-acetate. The precursors were mixed and subsequently hydrolyzed with water molecules generated in situ by an esterification reaction between acetic acid and ethanol. As-synthesized samples were amorphous for XRD, independently of the relative amount of doped iron. The undoped samples and samples with the molar ratio Fe/Ti = 0.01, treated at up to 500 • C, contained anatase as the dominant phase and rutile as the minor phase. The samples with the Fe/Ti molar ratio of 0.15, treated at the same temperature, contained anatase (major phase), rutile (minor phase) and a very small amount of an unidentified phase. The crystallite size of the dominant phase in the samples was estimated from the XRD line broadening using the Scherrer formula. Thermogravimetric analysis showed that weight loss was accelerated and completed at lower temperatures as the relative concentration of iron in the Fe-TiO 2 samples increased. The strong exothermic peak in the DTA curve between 300 and 450 • C in the undoped TiO 2 sample shifted to the lower temperatures and became much more asymmetrical with increased iron doping. This DTA peak corresponded to the amorphous-to-anatase-transition and it included several steps such as (i) the thermal degradation of strongly bound organic molecules, (ii) the condensation of unhydrolyzed -OR groups, (iii) the sintering and growth of particles and (iv) the rearrangement of newly formed chemical bonds. The center of the most intense Raman band of the E g mode at 143.8 cm −1 in the undoped TiO 2 sample continually shifted to higher wave numbers and the full-width at half maximum increased with iron doping. Transmission electron microscopy revealed decrease of the mean particle size from 16.3 nm in undoped sample to 9.7 nm in the highest iron doped sample. The particle size distribution becomes * To whom all correspondence should be addressed. 6Šijaković-Vujičić et al. narrower with iron doping. The narrowest particle size distribution was found in sample with the Fe/Ti molar ratio of 0.05, calcined at 500 • C. Scanning electron microscopy of undoped samples calcined at 580 • C showed irregular aggregates having a relatively flat surface. On the contrary, the samples doped with 15 mol% of iron and treated at the same temperature exhibited a non-uniform sponge-like surface with distributed micrometer holes
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