Application of erosion-control materials and spontaneous vegetation in the protection of reservoirs in southern and eastern Serbia

The quality and stability of erosion-control materials in protection of reservoirs in Southern and Eastern Serbia have been examined both in the field and in accredited laboratories in our country. Field investigations have been carried out over a period of 15 years in Eastern Serbia and for up to 30 years in Southern Serbia, and they are still being conducted by monitoring the state and possible damage of consolidation-retention check dams, walls, and other erosion-control structures. The materials used in protection of the Selova and Grlište Reservoirs are typical construction materials, such as resistant natural stone, concrete of the BI group, i.e., MB 20, aggregate, synthetic elements, etc. Long-term monitoring of their state and minor deformations has shown that the materials were well-chosen and stable, and that there has been no significant damage, except for some minor crumbling and smaller cracks due to negligible scouring. This is all the result of prior thorough empirical and laboratory testing of applied materials, which helped to achieve stability and functionality of structures erected to prevent silting-up of the reservoir. Such a state has contributed to stabilization of erosion processes and reduction of sediment quantities, improvement of water quality, and advancement of the autochthonous vegetation (Salix L., Cornus L., Quercus L.). Vegetation has further mitigated erosion, decreased floods, and consolidated the structures, thereby improving the ecological quality of the catchments as well as the entire study area

The impact of architectural and urban patterns on the behaviour of an exhibited angular size-illusion

This paper continues a research in which it has been confirmed that the angular size-illusion underpins a contradictory effect related to a seeming size-decrease of focused architectural and urban objects as the observer approaches them. It explores the impact of various architectural and urban patterns on the behavior of an angular size-illusion noticeable during movement. To obtain sustainable conclusions, real locations are selected and simplified. Simplification criteria are defined respecting the preconditions necessary to trigger such an illusion. Also, two groups of parameters are formulated, both as illusion quantifiers and illusion qualifiers (such as descriptors and determinants). By analyzing the illusion quantifier's conduct, the established valorization criteria allowed the methodological investigation of influences of illusion determinants on the descriptor's behavior. The outputs-based conclusions are generalized in a form applicable to contemporary architectural and urban practice, making it possible to estimate and control the behavior of the illusion in reality

The pencils of curves of the third and fourth order obtained by mapping the pencils of conics

Harmonijskom simetrijom, kao potpuno bijektivnom i konformnom centralnom inverzijom, prikazana je transformacija svih tipova pramenova konika i njihovih specifičnosti u pramenove krivih trećeg i četvrtog reda i njihove preslikane specifičnosti, i obrnuto. Prepoznavanjem ekvivalentnosti inverzije sa klasičnom osnom simetrijom (nekomformna simetrija) ukazano je na neograničene mogućnosti za preslikavanje krivih i površi i dobijanje novih oblika koji će biti od koristi i u teoriji geometrije kao i u arhitektonskoj praksiHarmonic symmetry, which is a completely bijective and conformal central inversion, is used to present the transformation of all types of pencils of conics and their specific features into the pencils of curves of the 3rd and 4th order and their mapped specific features and vice versa. The recognition of the equivalence of inversion with the classical axial symmetry (non-conformal symmetry) has created numerous possibilities for mapping curves and surfaces and obtaining new forms which can be of great use both in the theory of geometry and in the practice of architecture

Pramen površi 4. i 3. reda dobijen kao harmonijski ekvivalent pramena kvadrika kroz prostornu krivu 4. reda 1. vrste

This paper shows the process of inverting the 4th ordered space curve of the first category with a self-intersecting point (with two planes of symmetry) and determining its harmonic equivalent. There are harmonic equivalents for five groups of surfaces obtained through the 4th order space curve of the 1st category. Mapping was done through a system of circular cross-sections. Both classical and relativistic geometry interpretations are presented. We also designed spatial models - a spatial model of the pencil of quadrics and a spatial model of the pencil of equivalent quadrics. Besides the boundary surfaces, one surface of the 3rd order, which is an equivalent to a triaxial ellipsoid, passes through this pencil of surface of the 4th order. The center of inversion is located on the contour of the ellipsoid. The parabolic cylinder is mapped into its equivalent, by mapping the contour parabola of the cylinder, in the frontal projection, in relation to the center and the sphere of inversion into a contour curve of the 4th order surface. The generating lines of the parabolic cylinder, which are in a projecting position and pass through the antipode, are mapped into circles (also in a projecting position) whose diameters are from the center of inversion to the contour line. The application of the 4th order surfaces in architectural practice is also presented.U radu je inverzijom preslikana prostorna kriva 4. reda prve vrste sa samopresečnom tačkom (sa dve ravni simetrije) i određen je njen harmonijski ekvivalent. Prikazani su harmonijski ekvivalenti za pet grupa površi koje su dobijene kroz prostornu krivu 4 reda 1 vrste. Preslikavanje je rađeno preko sistema kružnih preseka. Dato je klasično i tumačenje u relativističkooj geometriji. Takođe su urađeni i prostorni modeli - prostorni model pramena kvadrika i pramena ekvivalentnih kvadrika. Kroz ovaj pramen površi 4. reda, osim graničnih površi, prolazi i jedna površ 3. reda koja je ekvivalent troosnom elipsoidu. Centar inverzije nalazi se na konturi elipsoida. Parabolički cilindar se preslikava u svoj ekvivalent, tako što se konturna parabola cilindra, za drugu projekciju, preslika u odnosu na centar i sferu inverzije u konturnu krivu površi 4. reda. Izvodnice paraboličkog cilindra, koje su u projicirajućem položaju i prolaze kroz antipod, preslikavaju se u krugove (takođe u projicirajućem položaju) čiji su prečnici od centra inverzije do konturne linije. Prikazana je i primena površi 4. reda u arhitektonskoj praksi

Oblaci tačaka kao fotogrametrijske reprezentacije površina linijskih objekata - uticaj ekstrinzičkih parametara snimanja na promenu kvaliteta njihovih tekstura sa aspekta hrapavosti

This paper investigates the impact of various extrinsic shooting parameters regarding change of roughness-quality of surface textures of linear objects/elements when presented in the form of unstructured photogrammetrially created point-clouds. To perform this scientifically-wise, two types of specific quality-descriptors are identified: process-quality descriptors and smoothness related quality descriptors. Then, they are precisely defined, computed and mutually correlated. It can be generally concluded that for a fixed focal length, shooting directions perpendicular to the axis of targeted object/element, station-points uniformly radially distributed around it (at a circle of 360 deg.) and obtained process-quality descriptors values that belong to satisfying /recommended ranges, the performed photogrammetric digitalization is declared highly precise and satisfyingly accurate regarding roughness /smoothness and barely prone to object-to-camera distance.Rad istražuje uticaj različitih ekstrinzičnih parametara snimanja površina linijskih objekata /elemenata, na promenu kvaliteta njihovih tekstura sa aspekta hrapavosti u slučaju kada su one fotogrametrijski generisane u vidu nestrukturiranih oblaka tačaka. U cilju uvođenja naučne metodologije u predmetno eksperimentalno istraživanje, identifikovana su (kao relevantna) dva tipa specifičnih deskriptora analiziranog kvaliteta (deskriptori koji opisuju nivo kvaliteta softverskog/fotogrametrijskog procesuiranja digitalnih snimaka izabranog eksperimentalnog objekta /elementa i deskriptori kojima se definiše postignuti kvalitet hrapavosti tj. stepen očuvanosti glatkoće njegove digitalizovane površine). Ovi deskriptori su, potom, precizno definisani i softverskim putem izračunati. Doneti zaključci su bazirani na analizi ciljno-relevantnih korelacija prethodno dobijenih vrednosti tih deskriptora. Zaključeno je da je za nepromenljivu žižnu daljinu, pravce snimanja upravne na osu linijskog objekta-elementa koji se fotografiše, za pozicije foto-aparata i fotogrametrijske targete ravnomerno radijalno raspoređene oko te ose (po krugu od 360°), kao i za dobijene vrednosti parametara kvaliteta realizovanog fotogrametrijskog procesuiranja (process-quality descriptors values) koje su u prihvatljivom/preporučenom opsegu, sve digitalizovane površine su predstavljene oblacima tačkama čije generisanje karakterišu visoka preciznost (precision) i zadovoljavajući nivo tačnosti (accuracy) na koje neznatno utiče distanca sa koje se vrši snimanje

Projektovanje solarnih sistema za arhitektonske objekte i BIM alati - pregled relevantnih geometrijskih aspekata

The paper systematizes geometric aspects relevant for understanding design of solar systems. The systematization is based on a review of literature dedicated to various kinds of engineers, including architects, involved in a multidisciplinary process of conceptualizing, designing and realization of PV systems. The understanding of the presented geometric aspects, known as solar geometry, is important not only in terms of finding optimal orientation and most effective tilt of solar modules, but also in terms of adequate geometric modelling of façade elements of a complex shape (as specific photovoltaic modules) in order to be optimally exposed to the sun all over the year. After providing detailed explanations of the main elements of solar geometry using the tools of spherical trigonometry, the paper discusses the integration of the presented geometric concepts in the BIM environments, and refers the example of Autodesk Revit software through its sun study tool. Analysed are functionalities of all interactive components of the 3D solar path representation. A need for more explicit determination of an incidence angle of the sun rays on a tilted surface is stressed. In the conclusion highlighted is the essential knowledge on solar geometry that needs to be acquired during architectural education, so that architects participating in the BIM working environments could be prepared for efficient conceptualization of integrated solar systems.U radu su sistematizovani najvažniji geometrijski aspekti koji su relevantni za celovito razumevanje projektovanja fotonaponskih sistema. Ova sistematizacija se bazira na pregledu literature namenjene različitim inženjerima, uključujući arhitekte koji su uključeni u multidisciplinarne procese konceptualizacije, projektovanja i realizacije fotonaponskih sistema. Razumevanje prikazanih geometrijskih aspekata, u literaturi objedinjenih pod nazivom solarna geometrija, značajno je ne samo zbog pronalaženja optimalne orijentacije i najefektnijeg nagiba fotonaponskih modula, nego i zbog adekvatnog oblikovanja geometrijski kompleksnih fasadnih elemenata, koji bi trebalo da budu optimalno osunčani tokom cele godine. Nakon detaljnog objašnjenja osnovnih elemenata solarne geometrije korišćenjem sferne trigonometrije, u radu je prodiskutovana integracija prikazanih geometrijskih koncepata u BIM okruženja, ilustrovana primerom modula za analize osunčanja u okviru softvera Revit, firme Autodesk. Analizirana je funkcionalnost svih interaktivnih komponenata 3D prikaza sunčeve putanje. Naglašena je potreba za eksplicitnijim određivanjem upadnog ugla sunčevih zraka na nagnutu površ fotonaponskog modula. U zaključnom delu izdvojeno je ono znanje o solarnoj geometriji koje bi bilo neophodno usvojiti u procesu arhitektonskog obrazovanja, kako bi projektanti koji rade u BIM okruženju bili pripremljeni za efikasnu konceptualizaciju integrisanih fotonaponskih sistema

APPLICATION OF EROSION-CONTROL MATERIALS AND SPONTANEOUS VEGETATION IN THE PROTECTION OF RESERVOIRS IN SOUTHERN AND EASTERN SERBIA

Abstract — The quality and stability of erosion-control materials in protection of reservoirs in Southern and Eastern Serbia have been examined both in the field and in accredited laboratories in our country. Field investigations have been carried out over a period of 15 years in Eastern Serbia and for up to 30 years in Southern Serbia, and they are still being conducted by monitoring the state and possible damage of consolidation-retention check dams, walls, and other erosion-control structures. The materials used in protection of the Selova and Grlište Reservoirs are typical construction materials, such as resistant natural stone, concrete of the BI group, i.e., MB 20, aggregate, synthetic elements, etc. Longterm monitoring of their state and minor deformations has shown that the materials were well-chosen and stable, and that there has been no significant damage, except for some minor crumbling and smaller cracks due to negligible scouring. This is all the result of prior thorough empirical and laboratory testing of applied materials, which helped to achieve stability and functionality of structures erected to prevent silting-up of the reservoir. Such a state has contributed to stabilization of erosion processes and reduction of sediment quantities, improvement of water quality, and advancement of the autochthonous vegetation (Salix L., Cornus L., Quercus L.). Vegetation has further mitigated erosion, decreased floods, and consolidated the structures, thereby improving the ecological quality of the catchments as well as the entire study area

Composite Concave Cupolae as Geometric and Architectural Forms

In this paper, the geometry of concave cupolae has been the starting point for the generation of composite polyhedral structures, usable as formative patterns for architectural purposes. Obtained by linking paper folding geometry with the geometry of polyhedra, concave cupolae are polyhedra that follow the method of generating cupolae (Johnson’s solids: J3, J4 and J5); but we removed the convexity criterion and omitted squares in the lateral surface. Instead of alter- nating triangles and squares there are now two or more paired series of equilateral triangles. The criterion of face regularity is respected, as well as the criterion of multiple axial symmetry. The distribution of the triangles is based on strictly determined and mathematically defined parameters, which allows the creation of such structures in a way that qualifies them as an autonomous group of polyhedra — concave cupolae of sorts II, IV, VI (2N). If we want to see these structures as polyhedral surfaces (not as solids) connecting the concept of the cupola (dome) in the architectural sense with the geometrical meaning of (concave) cupola, we re- move the faces of the base polygons. Thus we get a deltahedral structure — a shell made entirely from equilateral triangles, which is advantageous for the purpose of prefabrication. Due to the congruence of the major 2n-sided bases of concave cupolae of sort II with the minor bases of the corresponding concave cupolae of sort IV, it is possible to combine these polyhedra in composite polyhedra. But also their elongation with concave antiprisms of sort II or the augmentation with concave pyramids of sort II could be performed. Based on the foregoing, we exam- ine the possibilities of combining the considered polyhedra into unified composite structures

Kvantifikovanje kvaliteta gustine fotogrametrijski generisanih oblaka tačaka linijskih arhitektonsko-urbanistickih elemenata u funkciji distance sa koje se vrsi snimanje i broja pozicija fotoaparata tj. pravaca snimanja

This paper examines the impact of various object-to-camera distances and the number of station-points i.e. various shooting directions with regard to the obtained Density-quality of photogrammetrically created Point-clouds - as digital representations of the existent linear architectural/urban objects/elements. According to an artificial (purified) experimental scene used, the conclusion is that with the chosen focal lengths/object-to-camera distances, with shooting directions perpendicular to the axis of that object, with station-points uniformly radially distributed around it (at a circle of 360deg), and with the obtained values of photogrammetric-software process-quality outputs which belong to the recommended ranges, the achieved density-level of the created Point-clouds may be treated as independent on the camera's radial-movement angle but dependent on the percentage of 'Object's Photo-Coverage': the lower the Coverage, the lower the density. Also, regardless of the Coverage level, the majority of the generated points are generally more 'densimetrically' precise than they are 'densimetrically' accurate.Rad istražuje uticaj distance snimanja i broja korišćenih pozicija fotoaparata tj. pravaca snimanja na postignuti kvalitet gustine fotogrametrijski generisanih oblaka tačaka kao digitalnih reprezentacja postojećih linijskih arhitektonsko-urbanističkih objekata/elemenata. Zaključeno je da za koriščeno apstraktno (pojednostavljeno) eksperimentalno okruženje, za izabrane žižne daljine/distance sa kojih se fotografiše fokusirani objekat, pravce snimanja upravne na njegovu osu,za pozicije fotoaparata ravnomerno radijalno raspoređene oko te ose (u punom krugu), kao i za dobijene vrednosti izlaznih papametara kvaliteta relizovanog fotogrametrisjkog procesinga (process-quality output values) koje su u preporučenom opsegu, osvareni nivo gustine generisanih oblaka tačaka ne zavisi od uglovnog koraka rotacije fotoaparata, već od procenta zastupljenosti objekta na fotografji ('Object's Photo-Coverage'): ukoliko je ovajprocenat 'zastupljenosti' manji i gustina je manja. Takođe, nezavisno od nivoa upravo te 'zastupljenosti, generisane tačke (sa aspekta gustine), generalno više karakteriše ostvarena preciznost ('densimetric precision') nego tačnost ('densimetric accuracy')

Status of air pollutants and greenhouse gases in the Western Balkans: Benchmarking the accession process progress on environment

The adoption, implementation and enforcement of Chapter 27 of the EU acquis on Environment is an obligation for accessing countries. Reducing the emissions of air pollutants and greenhouse gases (GHG) is a priority which is strongly interlinked with energy, transport and health policies, among others. This report summarises the current status of air pollution and emission of pollutants and GHG in the countries of the Western Balkans (WB), describing the existing level of knowledge and the gaps with respect to the EU aquis in order to benchmark the future progress in this field, during the accession process. At present, the alignment with the EU acquis on environment and climate in the WB ranges from early stage to advanced. The implementation of Ambient Air Quality Directive is not fully effective in all the WB countries and air quality monitoring networks, online data processing and QA/QC procedures are at different levels of development. Often, air pollution reporting in the WB does not fulfil all the required criteria often and the number and proportion of reporting stations, time series and data coverage are all quite variable. Particulate matter (PM10 and PM2.5), SO2, O3 and NO2 are the air pollutants which levels are most frequently above the legislation limits in the WB. They are mainly emitted by human activities such as industry (including electricity production), household heating and transport. Agriculture contributes to secondary pollution. In addition, transboundary pollution from outside the region makes a considerable contribution to the observed concentrations. Energy and transport are the main sources of GHG in the region and a steady increase in the emissions is observed in some countries since 1995. The alignment in the field of climate change is at an initial stage. A continuing commitment is needed in the WB to achieve full alignment with EU environment acquis. The initial focus of the air quality management policies should be on the pollutants which are most frequently above the European legislation limit values. Among these are PM10, PM2.5 and SO2 emitted by coal burning in obsolete and inefficient power plants and industrial facilities. The combustion of biomass for residential heating also leads to considerable emissions of particulate matter. Co-benefits between air quality and climate should be better exploited. More effort should be made to further develop the technical skills in the WB countries in the areas of air quality monitoring and modelling and development of emission inventories for atmospheric pollutants and GHGs.JRC.C.5-Air and Climat