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The objective of this research is to propose a novel framework for assessing the consequences of hazardous events on a water resources system using dynamic resilience. Two types of hazardous events were considered: a severe flood event and an earthquake. Given that one or both hazards have occurred and considering the intensity of those events, the main characteristics of flood dynamic resilience were evaluated. The framework utilizes an artificial neural network (ANN) to estimate dynamic resilience. The ANN was trained using a large, generated dataset that included a wide range of situations, from relatively mild hazards to severe ones. A case study was performed on the Pirot water system (Serbia). Dynamic resilience was derived from the developed system dynamics model alongside the hazardous models implemented. The most extreme hazard combination results in the robustness of 0.04, indicating a combination of an earthquake with a significant magnitude and a flood hydrograph with a low frequency of occurrence. In the case of moderate hazards, the system robustness has a median value of 0.2 and the rapidity median value of 162 h. The ANN’s efficacy was quantified using the average relative error metric which equals 2.14% and 1.77% for robustness and rapidity, respectively.

The paper presents a functionality investigation of the key dam elements based on finite element analysis. A detailed analysis of filtration processes, dam strength, and the surrounding rock mass was conducted. Dam elements whose potential damage could jeopardize the normal functioning of the embankment dam have been identified. A particular emphasis was placed on the analysis of dam elements that have been identified as weak points. A numerical analysis of the impact of individual grout curtain zone failure on leakage under the dam body, a strength analysis of the overflow section, as well as the analysis of the slope stability that can compromise the functioning of the spillway have been performed. To analyze the partial stability of individual structural elements, a new measure of local stability was introduced as the remaining load-bearing capacity. As a case study, the Zavoj dam, which is a part of the Pirot reservoir system in the Republic of Serbia, was used. Investigation revealed that local damage to the grout curtain will not significantly increase leakage under the dam body, the overflow section is one of the most robust elements of the dam, but the slope above the spillway can compromise the functioning of the overflow and thus the safety of the entire dam. Based on the analysis of the results of the remaining load-bearing capacity, the dependence of the spillway capacity on earthquake intensity has been defined. The established relationship represents a surrogate model for further assessment of dynamic resilience of the complex multipurpose reservoir system, within the scope of the advanced reservoir system management.

The paper presents a functionality investigation of the key dam elements based on finite element analysis. A detailed analysis of filtration processes, dam strength, and the surrounding rock mass was conducted. Dam elements whose potential damage could jeopardize the normal functioning of the embankment dam have been identified. A particular emphasis was placed on the analysis of dam elements that have been identified as weak points. A numerical analysis of the impact of individual grout curtain zone failure on leakage under the dam body, a strength analysis of the overflow section, as well as the analysis of the slope stability that can compromise the functioning of the spillway have been performed. To analyze the partial stability of individual structural elements, a new measure of local stability was introduced as the remaining load-bearing capacity. As a case study, the Zavoj dam, which is a part of the Pirot reservoir system in the Republic of Serbia, was used. Investigation revealed that local damage to the grout curtain will not significantly increase leakage under the dam body, the overflow section is one of the most robust elements of the dam, but the slope above the spillway can compromise the functioning of the overflow and thus the safety of the entire dam. Based on the analysis of the results of the remaining load-bearing capacity, the dependence of the spillway capacity on earthquake intensity has been defined. The established relationship represents a surrogate model for further assessment of dynamic resilience of the complex multipurpose reservoir system, within the scope of the advanced reservoir system management.

The railway track with continuously welded rails is an essential part of the modern railway superstructure around the world. Calculation of the temperature stresses in continuously welded rails has great significance for the planning of maintenance activities in order to maintain traffic safety (risk of derailment due to either rail break, or track buckling). This paper presents the finite element model for calculation of rail stresses and displacements due to the temperature changes, which was developed by the authors. The monitoring of the track sections, which are significant regarding traffic safety, was suggested in this paper.

The railway track with continuously welded rails is an essential part of the modern railway superstructure around the world. Calculation of the temperature stresses in continuously welded rails has great significance for the planning of maintenance activities in order to maintain traffic safety (risk of derailment due to either rail break, or track buckling). This paper presents the finite element model for calculation of rail stresses and displacements due to the temperature changes, which was developed by the authors. The monitoring of the track sections, which are significant regarding traffic safety, was suggested in this paper.

Pravilan rad svih čula omogućava čoveku normalno funkcionisanje u sredini koja ga okružuje. Oštećenje ili gubitak čula sluha otežava svakodnevni život, smanjuje mogućnosti za rad i društveni život i može dovesti osobu u stanje depresije. Gubitak sluha može biti posledica različitih uzroka, oštećenja različitih delova uva ili auditornih nerava. Poboljšanje sluha je najčešće moguće ostvariti primenom slušnih aparata i slušnih implanata. U zavisnosti od stepena i vrste oštećenja predlaže se odgovarajući implant – pasivni ili aktivni, kohlearni ili implant srednjeg uva, implant koji radi na principu provođenja zvuka kroz vazduh ili zvuka kroz temporalnu kost. Iako doprinose poboljšanju sluha svi implanti se ugrađuju operativnim putem što nosi dozu rizika. O čulu sluha se zna dosta i opet nedovoljno. O uvu, kao organu čula sluha, se zna dosta o njegovoj strukturi i funkciji. Kohlea, koja čini deo unutrašnjeg uva, ima složenu strukturu i dosta procesa se odvija unutar nje. Problem sa izučavanjem kohlee se ogleda u tome što je teško prikupiti eksperimentalne podatke. Kohlea je smeštena duboko u lobanji, gotovo nepristupačna i velika je verovatnoća da će doći do oštećenja prilikom merenja na živom pacijentu. Na taj način eksperimentalni pristup je veoma ograničen. S druge strane, kohlea brzo gubi svoja svojstva po nastupanju smrti, tako da nije moguć u velikoj meri ni rad na mrtvim kohleama. Zbog toga kompjutersko modeliranje kohlee i analiza odziva imaju veliku ulogu u ovoj oblasti istraživanja. Cilj ove teze je razvoj mehaničkih i elektro-mehaničkih modela kohlee koji opisuju normalno funkcionisanje kohlee i omogućavaju analizu odziva – posmatranje promene odziva sa promenom izvesnih parametara. Dovođenje u vezu uzroka oštećenja sa njegovom posledicom, odnosno promenom odgovarajućeg parametra koji utiče na oštećenje sluha, omogućava primenu modela u praksi. Modeliranje kohlee ima za cilj i utvrđivanje postojanja određenih signala koji ukazuju na oštećenje i predlog načina, Proper work of human senses allows normal functioning in the surrounding environment. Damage or hearing loss makes difficult everyday life, decreases possibilities for work and social life and can bring person to the state of depression. Hearing loss can be consequence of different causes, damage of different part of the ear or auditory nerves. Hearing improvement is usually possible to accomplish by applying hearing aids and hearing implants. In dependence of the level and type of damage certain implant is suggested – passive or active, cochlear or middle ear implant, implant that works on principle of air conduction of sound or bone conduction of sound, through the temporal bone. Although all implants contribute to improving of hearing, they are implanted during the surgery, which carrying a dose of risk. About hearing sense is known a lot of, but yet not enough. About ear, as organ of hearing sense, is known a lot about his structure and function. Cochlea, which makes part of the inner ear, has complex structure and a lot of processes are happening inside her. Problem with cochlear research is that it is hard to collect experimental data. Cochlea is placed deep inside the skull, almost unreachable and there is great possibility that it will be harmed during the experimental measurement on alive human. On that way experimental approach is very limited. On the other side, cochlea quickly loses its properties after death occurs, so it is not possible in larger scale to work with dead cochlea. That is the reason why computer modeling of cochlea and response analysis have great role in this research area. The goal of this thesis is to develop mechanical and electro-mechanical cochlea models which describe proper functioning of the cochlea and allow response analysis – observation of the response change with change of certain parameters. By combining cause of damage with his consequence, namely change of the certain parameter which has influence on hearing damage, mode

Aorta, kao osnovni i najveći krvni sud u čoveku, neprekidno je izložena visokom pulzativnom pritisku i smičućim silama. Disekcija aorte predstavlja veoma ozbiljno i urgentno stanje, u kojem dolazi do cepanja i raslojavanja unutrašnjeg sloja aortnog zida, dok spoljnji sloj ostaje netaknut. Numeričke simulacije dinamičkog ponašanja fluida-krvi u aorti sa disekcijom mogu dosta pomoći lekarima, jer daju uvid u dalji razvoj bolesti. Osnovni metod koji je korišćen u ovom radu jeste metod konačnih elemenata (MKE). Brzine strujanja fluida, pritisaka i smičućih napona u čvorovima konačnih elemenata određuju se u karakterističnim tačkama pulzatornog strujanja krvi. U jednom delu rada, primenom komercijalnih softvera, izvršene su trodimenzionalne rekonstrukcije medicinskih snimaka, a potom, primenom softvera koji je razvijen u Istraživačko razvojnom centru za bioinženjering, sprovedeno je numeričko rešavanje odnosa pravog i lažnog lumena akutne aortne disekcije. Osnovni cilj teze je da se primenom numeričkih simulacija odrede pritisci, smičući naponi i brzine u pravom i lažnom lumenu čime se dobija jasna slika njihovog međusobnog odnosa. Virtuelnim simuliranjem efekta operacije (isecanjem uzlazne aorte i zamene tubus graftom) određuju se protoci kroz bočne opstruirane grane aorte zahvaćene disekcijom, što pokazuje kako hirurški zahvat zamene uzlazne aorte i prekidanje protoka lažnog lumena, ima uticaj na protok kroz grane aortnog luka i visceralne grane (grane abdominalne aorte). Određivanjem von Mizesovih napona u zidu lažnog lumena dobijaju se potencijalna mesta rupture aorte. Ovim putem se neinvazivnim pristupom određuje rizik od nastanka rupture aorte i daje prednost ovom metodu, umesto kriterijuma maksimalnog prečnika., Aorta, as the main and the largest blood vessel in the human body, is constantly exposed to high pulse pressure and shear forces. Aortic dissection is a very serious condition and medical emergency, which leads to tearing and delamination of the inner layer of the aortic wall, while the outer layer remains intact. Numerical simulations of the dynamic behavior of fluid-blood in the aorta dissection can be of great help to doctors, because they provide insight into further development of the disease. The main method used in this paper is the finite element method (FEM). Fluid velocity, pressure and wall shear stress in nodes of finite elements are determined by specific points of the pulsatile blood flow. One section of the paper focuses on a three-dimensional reconstruction of medical images using a commercial software and in the next section, by using the software developed in the Research and Development Centre for Bioengineering, the numerical solution of relations between true and false lumens of acute aortic dissection is performed. The main objective of the thesis is to determine pressures, wall shear stress and velocity in the true and false lumen by applying numerical simulations, which gives a clear picture of their relationship. Virtual simulation of the effects of the operation (by cutting the ascending aorta and replacing it with the stent graft) determines the flow through the obstructed side branches of aortic dissection, which shows how the surgical intervention of replacing the ascending aorta and interrupting the flow in the false lumen has an impact on the flow through the branches of the aortic arch and the visceral branches (branches of the abdominal aorta). By determining von Mises stresses in the wall of the false lumen, potential points of rupture of the aorta are obtained. In this manner, the risk of rupture of the aorta is determined by using a non-invasive approach, giving this method an advantage over the maximum diameter criterion.

The dissertation is a contribution in defining and studying different types of partial orders on rings, particularly on von Neumann regular and Rickart rings, as well as on the algebras of bounded operators on Banach and Hilbert spaces. In the first part of the dissertation, using generalized inverses of elements, the definitions of the minus, star, sharp, core and dual core partial orders are extended from the set of complex matrices to an arbitrary ring (with or without an involution). In a unified approach it is shown that the condition a

Tlo kao osnovni materijala za izradu nasutih brana ima izrazito nelinearno mehaničko ponašanje koje se bitno razlikuje od mehaničkog ponašanja drugih inženjerskih materijala. Kako bi sprovođenje detaljne analize stabilnosti nasutih brana primenom metode konačnih elemenata bilo moguće, neophodno je korišćenje materijalnih modela za opisivanje mehaničkog ponašanja materijala tla. Sa tim ciljem u okviru ove disertacije su razvijeni algoritmi za integraciju napona materijalnih modela najčešćih tipova tla. Razvijeni materijalni modeli su namenjeni statičkoj i dinamičkoj analizi tla, odnosno nasutih brana. Pored poznatih materijalnih modela za koje su razvijeni algoritmi za integraciju napona, razvijen je I implementiran nov materijalni model za simulaciju mehaničkog ponašanja granularnih materijala zasnovan na uslovu loma Maksimovića. Verifikacija materijalnih modela je izvršena kroz više primera numeričke simulacije eksperimentalnih ispitivanja uzoraka materijala tla kao i kroz primere u kojima su numerički rezultati poređeni sa teorijskim rešenjima. Razvijen je i implementiran algoritam za dinamičku analizu problema mehanike tla sa posebnim osvrtom na primenu u seizmičkoj analizi stabilnosti nasutih brana. Kako bi se analiziralo realno ponašanje materijala tla kao poroznog medija čije su pore ispunjene fluidom i u obzir uzela interakcija ove dve faze, izvršeno je sprezanje ravnotežnih jednačina čvrste i tečne faze. Sa ciljem redukovanja domena numeričke integracije pri analizi nasutih brana izloženih seizmičkom opterećenju, razvijene su i implementirane apsorbujuće granice modela. Korišćenjem ovih granica sprečava se pojava refleksije talasa od granica modela. Izvršena je analiza i sistematizacija kriterijuma za analizu stabilnosti nasutih brana I predložene metode određivanja njihove stabilnosti primenom razvijenih algoritama. U okviru ovog dela je obrađena metoda redukovanja smičuće čvrstoće primenom materijalnih modela razvijenih u okviru disertacije. Razvijeni soft, Soil as a basic material for construction of embankment dams is of a very non-linear and fundamentally different mechanical behavior compared to mechanical behavior of other engineering materials. In order to enable performance of detailed stability analysis of this structure type using the finite element method, it is necessary to use constitutive models to describe mechanical behavior of soil. With such an objective, algorithms for integration of material model stress of most common soil types were developed in this thesis. Developed material models are applied in static and dynamic soil analysis especially in embankment dams. Apart from familiar material models with developed algorithms for stress integration, there is also a new material model developed and implemented to simulate mechanical behavior of granular materials based on Maksimovic’s failure envelope. Verification of the material model was performed using a number of numerical simulations of experimental tests of soil material samples as well as examples in which numerical results were compared to theoretical solutions of the problems. Algorithm for dynamic analysis of the soil mechanics problems was developed and implemented with a special emphasis on the application in embankment dam seismic stability analysis. In order to analyze realistic behavior of soil materials as porous media whose pores are filled with fluid and to consider the interaction of these two phases, coupling of the equilibrium equations in solid and fluid phases was performed. With the aim to reduce numerical integration domain in the analysis of embankment dams subjected to seismic loads, absorbing boundary conditions were developed and implemented. These boundaries prevent the occurrence of reflection waves from the artificial boundaries. The analysis and systematization of stability analysis criteria for embankment dams were performed with suggested methods of their stability determination using developed algorithms. Sheer stren

In developing the vane pumps the fundamental basis is experimental research and mathematical modelling of nonstationary hydraulic processes inside the pump, in thrust space and suction and thrust pipeline. By means of experimental research and results of mathematical modelling and software package KRILP, it is possible to determine the parameters of operating processes of vane pumps precisely enough. This research examines the idealized and actual flow ripple of a high-pressure vane within vane type pump. For the idealized case, a "perfect" pump is examined in which the leakage is considered to be zero and the fluid is considered to be incompressible. Based upon these assumptions, expressions describing the characteristics of the idealized flow-ripple are derived. Next, the actual flow-ripple of the pump is examined by considering the fluid compressibility and for computing these results a numerical program is used. From the idealized analysis it is shown that the idealized flow-ripple is determined by geometrical flow property.

In developing the vane pumps the fundamental basis is experimental research and mathematical modelling of nonstationary hydraulic processes inside the pump, in thrust space and suction and thrust pipeline. By means of experimental research and results of mathematical modelling and software package KRILP, it is possible to determine the parameters of operating processes of vane pumps precisely enough. This research examines the idealized and actual flow ripple of a high-pressure vane within vane type pump. For the idealized case, a "perfect" pump is examined in which the leakage is considered to be zero and the fluid is considered to be incompressible. Based upon these assumptions, expressions describing the characteristics of the idealized flow-ripple are derived. Next, the actual flow-ripple of the pump is examined by considering the fluid compressibility and for computing these results a numerical program is used. From the idealized analysis it is shown that the idealized flow-ripple is determined by geometrical flow property.

In developing the vane pumps the fundamental basis is experimental research and mathematical modelling of nonstationary hydraulic processes inside the pump, in thrust space and suction and thrust pipeline. By means of experimental research and results of mathematical modelling and software package KRILP, it is possible to determine the parameters of operating processes of vane pumps precisely enough. This research examines the idealized and actual flow ripple of a high-pressure vane within vane type pump. For the idealized case, a "perfect" pump is examined in which the leakage is considered to be zero and the fluid is considered to be incompressible. Based upon these assumptions, expressions describing the characteristics of the idealized flow-ripple are derived. Next, the actual flow-ripple of the pump is examined by considering the fluid compressibility and for computing these results a numerical program is used. From the idealized analysis it is shown that the idealized flow-ripple is determined by geometrical flow property.

An implicit computational governing parameter method (GPM) for stress integration of the modified Cam-Clay model is presented in the paper. In the previous studies, the increment of the mean plastic strain d epsilon(p)(m) was adopted as the governing parameter for the modified Cam-Clay model. While in this paper, the effective mean stress sigma(m)' is used as the governing parameter, which is much more convenient than d epsilon(p)(m). Such algorithm is simple, reliable, efficient and robust. This approach makes it possible to calculate the true tangent constitutive matrix in a simple way.

An implicit computational governing parameter method (GPM) for stress integration of the modified Cam-Clay model is presented in the paper. In the previous studies, the increment of the mean plastic strain d epsilon(p)(m) was adopted as the governing parameter for the modified Cam-Clay model. While in this paper, the effective mean stress sigma(m)' is used as the governing parameter, which is much more convenient than d epsilon(p)(m). Such algorithm is simple, reliable, efficient and robust. This approach makes it possible to calculate the true tangent constitutive matrix in a simple way.