Uloga i koncepcija distributivnog hidro-informacionog sistema za podršku integralnom upravljanju vodama sliva Drine

The significant hydro potential of the Drina River is not utilized to its full extent. A very important step towards integrated water management in the Drina River basin is the establishment of a distributed system to aid management as an information, technical and expert decision-making support tool. The paper presents the concept of a modern and complex distributed hydro information system, which includes data acquisition, processing and archiving, as well as software for the integration of system components. The central software component is a mathematical model of the system and the process, aimed at providing the user with relevant information for expert decision-making on the further development and improvement of the system or adequate management in real time.Značajan vodni potencijal sliva reke Drine nije u dovoljnoj meri iskorišćen Veoma važan korak u integralnom upravljanju vodama na slivu reke Drine jeste uvođenje distribuiranog sistema za podršku upravljanju, kao informatičke tehničke i ekspertske podrške odlučivanju. U radu je prikazana koncepcija savremenog i složenog distributivnog hidroinformacionog sistema, koji obuhvata akviziciju, obradu i arhiviranju podataka, kao i softver koja objedinjuje sve delove sistema. Centralni deo softvera je matematički model sistema i procesa, sa ciljem da korisniku pruži relevantne informacije koje su potrebne za donošenje ekspertske odluke o daljem razvoju i unapređenju sistema ili adekvatnom upravljanju u realnom vremenu

Optimizacija i estimacija pri planiranju i upravljanju u sistemu Drine

The water management system for the Drina river basin will be one of the most complex systems in Europe with regard to its areal coverage and performance. Successful planning of the system and management of the finished product need to be based on the state-of-the-art cybernetic approach. The methods of implementing the target architecture are considered, aimed at the highest level defined as integrated regulation, use and protection of the Drina river basin, which is then broken down in the form of a tree into increasingly detailed objectives of the various users in the basin. A particularly important conclusion is drawn that water management and hydroelectric power objectives and those of other users in the basin have to be treated equitably. Following distribution of the system, the basic types of replication in certain parts of the system are presented. The decision-making process in all stages of management is considered, including the determination of tasks at the decision-making level and the technical level where modeling, estimation and evaluation/optimization of management take place, in preparation for the decision-making process. The decision maker needs to be iteratively involved in the decision-making process, in order to be able to require changes of criteria and preferences based on new knowledge acquired from optimization results, in the course of multi-criteria evaluation and management decision-making. The optimization tasks are considered, and a special assessment is made of the criteria most applicable to the Drina system planning and operation process. The role of external estimators is also addressed, and a management improvement is shown to be the result of obtaining forecasts of the outcome of input vectors in the system.Vodoprivredni sistem u slivu Drine biće jedan od prostorno i funkcionalno najsloženijih sistema u Evropi. Uspešno planiranje sistema i upravljanje gotovim sistemom mora se zasnivati na najsavremenijim kibernetskim metodama. Razmatraju se načini formalizacije ciljnih struktura, sa ciljem najvišeg reda koji se definiše kao "integralno uređenje, korišćenje i zaštita sliva reke Drine", koji se zatim u vidu granatog stabla dekomponije na sve podrobnije ciljeve svih korisnika prostora. Kao posebno važan zaključak se ističe da se vodoprivredni i hidroenergetski ciljevi moraju tretirati sasvim ravnopravno sa ciljevima svih ostalih korisnika prostora. Nakon dekompozicije sistema prikazuju se osnovni tipovi preslikavanja u pojedinim delovima sistema. Razmatra se proces odlučivanja u svim fazama upravljanja, sa determinisanjem zadataka na nivou donošenje odluka i na tehničkom nivoa, na kome se obavlja modeliranje, estimacija i valorizacija/optimizacija upravljanja, kao priprema za proces donošenja odluka. Donosilac odluke mora da bude iterativno uključen u proces odlučivanja, kako bi na bazi novih saznanja o rezultatima optimizacije mogao da zahteva izmenu kriterijuma i preferencija, pri višekriterijumskom vrednovanju varijanti i upravljačkih odluka. Razmatraju se zadaci optimizacije, pri čemu se posebno analiziraju kriterijumi koji su najupotrebljiviji u procesu planiranja i eksploatacije sistema u slivu Drine. Analizira se i uloga spoljnih estimatora, i prikazuje poboljšanje upravljanja kao rezultat dobijanja prognoze realizacije ulaznih vektora u sistemu

Uloga i koncepcija distributivnog hidro-informacionog sistema za podršku integralnom upravljanju vodama sliva Drine

The significant hydro potential of the Drina River is not utilized to its full extent. A very important step towards integrated water management in the Drina River basin is the establishment of a distributed system to aid management as an information, technical and expert decision-making support tool. The paper presents the concept of a modern and complex distributed hydro information system, which includes data acquisition, processing and archiving, as well as software for the integration of system components. The central software component is a mathematical model of the system and the process, aimed at providing the user with relevant information for expert decision-making on the further development and improvement of the system or adequate management in real time.Značajan vodni potencijal sliva reke Drine nije u dovoljnoj meri iskorišćen Veoma važan korak u integralnom upravljanju vodama na slivu reke Drine jeste uvođenje distribuiranog sistema za podršku upravljanju, kao informatičke tehničke i ekspertske podrške odlučivanju. U radu je prikazana koncepcija savremenog i složenog distributivnog hidroinformacionog sistema, koji obuhvata akviziciju, obradu i arhiviranju podataka, kao i softver koja objedinjuje sve delove sistema. Centralni deo softvera je matematički model sistema i procesa, sa ciljem da korisniku pruži relevantne informacije koje su potrebne za donošenje ekspertske odluke o daljem razvoju i unapređenju sistema ili adekvatnom upravljanju u realnom vremenu

Influence of the Ringer's solution on wear of vacuum mixed poly(methyl methacrylate) bone cement in reciprocating sliding contact with AISI 316L stainless steel

This paper presents microstructural properties and damage behaviour of a vacuum mixed poly(methyl metacrylate) (PMMA) bone cement, during the sliding contact with AISI 316L stainless steel, under micro-loads. Influence of the Ringer's solution on the wear was analysed in comparison to dry contact. The variation of load did not produce any significant change of the wear factor while the increase in the sliding speed induced significant increases in the wear factor, more pronounced in the case of dry sliding. The obtained wear factors were in average higher for the sliding in Ringer's solution than those obtained under dry conditions. Significant fragmentation of the worn tracks, of irregular shapes with broken edges, was observed, slightly more pronounced for the dry contact. Many cavities and voids were formed on the wear track surface, but they did not extend into the bulk material. Higher loads produced more uniform and less fragmented wear tracks. Abrasive, adhesive wear and plastic deformation grooves were observed, as well as fatigue and erosive wear. Fatigue cracks developed in the direction normal to sliding. Network of fine craze cracks was exhibited on the surface of wear tracks, especially pronounced in the case of dry sliding. These results are important since they contribute to understanding the sites of crack initiation, and development mechanisms on the surface of PMMA bone cements, also including synergistic effects of physiological environments pertaining to the non-steady crack and craze behaviour and crack pattern development in PMMA

Optimizacija i estimacija pri planiranju i upravljanju u sistemu Drine

The water management system for the Drina river basin will be one of the most complex systems in Europe with regard to its areal coverage and performance. Successful planning of the system and management of the finished product need to be based on the state-of-the-art cybernetic approach. The methods of implementing the target architecture are considered, aimed at the highest level defined as integrated regulation, use and protection of the Drina river basin, which is then broken down in the form of a tree into increasingly detailed objectives of the various users in the basin. A particularly important conclusion is drawn that water management and hydroelectric power objectives and those of other users in the basin have to be treated equitably. Following distribution of the system, the basic types of replication in certain parts of the system are presented. The decision-making process in all stages of management is considered, including the determination of tasks at the decision-making level and the technical level where modeling, estimation and evaluation/optimization of management take place, in preparation for the decision-making process. The decision maker needs to be iteratively involved in the decision-making process, in order to be able to require changes of criteria and preferences based on new knowledge acquired from optimization results, in the course of multi-criteria evaluation and management decision-making. The optimization tasks are considered, and a special assessment is made of the criteria most applicable to the Drina system planning and operation process. The role of external estimators is also addressed, and a management improvement is shown to be the result of obtaining forecasts of the outcome of input vectors in the system.Vodoprivredni sistem u slivu Drine biće jedan od prostorno i funkcionalno najsloženijih sistema u Evropi. Uspešno planiranje sistema i upravljanje gotovim sistemom mora se zasnivati na najsavremenijim kibernetskim metodama. Razmatraju se načini formalizacije ciljnih struktura, sa ciljem najvišeg reda koji se definiše kao "integralno uređenje, korišćenje i zaštita sliva reke Drine", koji se zatim u vidu granatog stabla dekomponije na sve podrobnije ciljeve svih korisnika prostora. Kao posebno važan zaključak se ističe da se vodoprivredni i hidroenergetski ciljevi moraju tretirati sasvim ravnopravno sa ciljevima svih ostalih korisnika prostora. Nakon dekompozicije sistema prikazuju se osnovni tipovi preslikavanja u pojedinim delovima sistema. Razmatra se proces odlučivanja u svim fazama upravljanja, sa determinisanjem zadataka na nivou donošenje odluka i na tehničkom nivoa, na kome se obavlja modeliranje, estimacija i valorizacija/optimizacija upravljanja, kao priprema za proces donošenja odluka. Donosilac odluke mora da bude iterativno uključen u proces odlučivanja, kako bi na bazi novih saznanja o rezultatima optimizacije mogao da zahteva izmenu kriterijuma i preferencija, pri višekriterijumskom vrednovanju varijanti i upravljačkih odluka. Razmatraju se zadaci optimizacije, pri čemu se posebno analiziraju kriterijumi koji su najupotrebljiviji u procesu planiranja i eksploatacije sistema u slivu Drine. Analizira se i uloga spoljnih estimatora, i prikazuje poboljšanje upravljanja kao rezultat dobijanja prognoze realizacije ulaznih vektora u sistemu

Identifikacija nelinearnog strukturnog ponašanja pomoću digitalne povratne neuronske mreže

Dynamical systems contain nonlinear relations which are difficult to model with conventional techniques. Hence, efficient nonlinear models are needed for system analysis, optimization, simulation and diagnosis of nonlinear systems. In recent years, computational-intelligence techniques such as neural networks, fuzzy logic and combined neuro-fuzzy systems algorithms have become very effective tools in the field of structural identification. The problem of the identification consists of choosing an identification model and adjusting the parameters in an way that the response of the model approximates the response of the real system to the same input. This paper investigates the identification of a nonlinear system by Digital Recurrent Neural Network (DRNN). A dynamic backpropagation algorithm is employed to adapt weights and biases of the DRNN. Mathematical model based on experimental data is developed. Results of simulations show that the application of the DRN for the identification of complex nonlinear structural behaviour gives satisfactory results.Dinamički sustavi sadrže nelinearne veze koje se teško modeliraju konvencionalnim tehnikama. Nelinearni modeli su neophodni za analizu sustava, optimizaciju, simulaciju i dijagnostiku nelinearnih sustava. Prethodnih godina, tehnike računalne inteligencije kao što su neuralne mreže, fuzzy logika i kombinirani neuro-fuzzy sustavi postaju efikasni alati u identifikaciji nelinearnih objekata. Problem identifikacije se sastoji od izbora identifikacijskog modela i prilagođavanja parametara tako da odziv modela aproksimira odziv realnog sustava za isti ulaz.Ovaj rad proučava identifikaciju nelinearnih sustava pomoću digitalne povratne neuronske mreže. Dinamički algoritam s propagacijom pogreške unazad se primjenjuje za adaptaciju težina i pragova osjetljivosti DRNN. Matematički model se razvija na bazi eksperimentalnih podataka. Rezultati simulacija pokazuju da primjena DRN u identifikaciji kompleksnog nelinearnog strukturnog ponašanja daje zadovoljavajuće rezultate

CUSTOMIZATION OF ELECTROSPINNING FOR TISSUE ENGINEERING

This paper deals with two electrospinning technologies: the melt electrospinning with a customized jet head, adapted from the fused deposition modeling (FDM) 3D printer, in comparison with the standard solution electrospinning, aiming at fabrication of tissue engineering scaffolds. The resulting fibers are compared. The influence of the collector properties on those of the fabricated scaffold is investigated. The resulting electrospun fibers exhibit different characteristics such as morphology and thickness, depending on the technology. The micro-fibers are produced by the melt electrospinning with an inbuilt 3D printer jet head, whereas the solution electrospinning has produced nano- and micro-fibers. The scaffolds fabricated on the rotating drum collector exhibit a more ordered structure as well as thinner fibers than those produced on the stationary plate collector. Further investigations should aim at fabrication of porous hollow fibers and tissue engineering scaffolds with controlled porosity and properties

Friction coefficient during the reciprocating sliding of uhmwpe in different environments

Dynamic friction coefficient (COF) of the reciprocating sliding contact of UHMWPE, was investigated in four different environments (dry contact; distilled water; pure Ringer's solution and with PMMA particles), at five values of low normal load (0.1 – 1 N) and three values of sliding speed (4 – 12 mm/s). Significant differences of COF values occurred at low load (0.1 N), whereas sliding speed did not influence COF values. Addition of PMMA particles in Ringer's solution produced significant increase of COF values, especially at the lowest load of 0.1 N

Numerical analysis of ductile fracture

The part of this research is supported with the Project TR32036 financed by the Ministry of Education, Science and Technological Development, Republic of Serbia

Influence of different environments on the sliding friction of Ultra-high-molecular-weight polyethylene (UHMWPE)

Dynamic friction coefficient (COF) of the reciprocating sliding contact of the conventional UHMWPE, was investigated in four different environments (dry contact; distilled water; pure Ringer's solution and with PMMA particles), at five values of low normal load (0.1-1 N) and three values of sliding speed (4 - 12 mm/s). Significant differences of COF values occurred at the lowest load (0.1 N), whereas sliding speed did not influence COF values. Addition of PMMA particles in Ringer's solution produced significant increase of COF values, especially at the lowest load of 0.1 N. For the dry contact and the highest load (1 N), steady state was reached shortly after the beginning of the test and friction coefficient had uniform behaviour. In the case of wet environment and the lowest load, steady state was not reached and the friction coefficient exhibited non-reproducible random behaviour. According to the Hertz theory, 0.5 N load corresponded to the elastic stress of 48.7 MPa, thus surpassing the values of the elastic limits, hardness and true yield stress of the UHMWPE, and the behaviour of the friction coefficient was drastically different below and above this load value. It can be assumed that below the 0.5 N load, viscoelastic response, accompanied with plastic deformation is dominant, with transition to mainly plastic deformation for the higher loads