Darbe nagrinėtas skysčio tekėjimas laminariniame pasienio sluoksnyje. Skysčio tekėjimo greičio vektoriaus komponentės yra išreiškiamos tokiomis lygtimis v1 ir v2. Atsižvelgiant į hidrodinamikos dėsnius, prie šių lygčių yra pridedamos kraštinės sąlygos: v1=v2=0, kai x1≥0, x2=0, v1=U, kai x2→±∞. Gautas uždavinys buvo nagrinėtas matematiniu paketu MathCAD 13. Skaitiškai gauti rezultatai patvirtina teorines žinias apie skysčio tekėjimą laminariniame pasienio sluoksnyje. Iš darbe gautų grafikų galime daryti konkrečias išvadas apie sprendinio elgesį. / The laminar boundary layer flow of the incompressible liquid over semi – infinite flat plate is discussed. Components of the velocity vector are expressed in the form v1 and v2. In accordance with hydrodynamic laws the following boundary conditions are prescribed v1=v2=0, when x1≥0, x2=0, v1=U as x2→±∞. The problem was analyzed numerically using MathCAD 13. The obtained numerical results confirm the theoretical results about in laminar boundary layer flow of a viscous incompressible liquid. From the diagrams that are shown in the diploma work one can make certain specific conclusions about the behavior of the flow.

Tiriamojo darbo objektas: Šventosios uostas ir Baltijos priekrantė. Tiriamojo darbo tikslas: susipažinti su Šventosios uosto rekonstrukcijos galimybių studijomis bei poveikio aplinkai ataskaita, išanalizuoti numatomas uosto rekonstrukcijos alternatyvas ir ištirti papildomą uosto rekonstrukcijos alternatyvą (pakeisti įplaukos kanalo kryptį) hidrodinaminiu ir nešmenų pernašos aspektais. Tiriamojo darbo uždaviniai: 1. Atlikti literatūros apžvalgą apie jūrų uostus Lietuvoje ir jų poveikį aplinkai. 2. Susipažinti su Šventosios uosto rekonstrukcijos poveikio aplinkai vertinimo (PAV) ataskaita. 3. Įsisavinti skaitmeninio modeliavimo sistemos MIKE 21 bangų (NSW), hidrodinaminį (HD) ir nešmenų pernašos (ST) modelius. 4. Sudaryti papildomą uosto rekonstrukcijos alternatyvą ir nustatyti jos poveikį hidrodinaminiams ir nešmenų pernašos procesams Baltijos priekrantėje. 5. Palyginti papildomos uosto rekonstrukcijos alternatyvos ir PAV ištirtų alternatyvų poveikį hidrodinaminiams ir nešmenų pernašos procesams Baltijos priekrantėje. Tiriamojo darbo metodika: literatūros apžvalgos skyrius rašomas referatyviai, analizuojant mokslinius šaltinius, didžiausią dėmesį atkreipiant į Šventosios uosto raidą ir poveikį aplinkai. Atliekamas rekonstrukcijos alternatyvų modeliavimas MIKE 21 skaitmeninio modeliavimo programa. Atliekamas modeliavimo rezultatų palyginimas. Tiriamojo darbo rezultatai: 1. Literatūros analizėje apžvelgta bendra Lietuvos uostų būklė, Šventosios uosto istorinė raida... [toliau žr. visą tekstą] / Object of the research: Port of Šventoji and Baltic Sea coast. Aim of the research: Become acquainted with Port of Šventoji reconstruction feasibility studies and environmental impact report, to analyze the expected port reconstruction alternatives and investigate additional port reconstruction alternative with a change of port entrance to south-west direction, also alternatives are evaluated on the hydrodynamic and sediment transport processes in the Baltic coast region. Objectives of the research: 1. Perform literature review of the ports in Lithuania and their impact on the environment. 2. Become acquainted with environmental impact report and port of Šventoji reconstruction possibilities. 3. To become familiar with digital modeling tool MIKE 21 wave (NSW), hydrodynamic (HD) and sediment transportation (ST) models. 4. To create additional reconstruction alternative of the port and determine its impact on the Baltic coast region and hydrodynamic processes. 5. To compare hydrodynamic and sediment transport modeling results of additional alternative and alternatives of the EIA, Research methods: Literature review section is written essay style, followed by analysis of scientific sources, focusing on the Šventoji port development and environmental impact. Reconstruction alternatives modeling is performed by using digital modeling tool MIKE 21. Comparison of simulation results is performed. Research results: 1. In the literature analysis, general condition of... [to full text]

Šiame darbe nagrinėjamas 3 km ilgio Nemuno vandens kelio ruožas Šilutės rajone ir tiriami įvairūs upės vagos reguliavimo variantai. Pasirinktas Nemuno ruožas Šilutės rajone ties Leitės žiotimis pasižymi sudėtingomis sąlygomis vaginių procesų atžvilgiu. Tai tipiškas, be įprastinių, daugybės antropogeninių veiksnių formuojamas ruožas. Kita vertus, tai labai svarbus ruožas landšafto – gamtosaugos, rekreacijos, kultūros, ekonomikos ir kitais požiūriais, todėl šios Nemuno atkarpos tyrimai turi neabejotiną mokslinę svarbą ir praktinę naudą. Pagrindinis šio darbo tikslas- išanalizuoti ir įvertinti Nemuno vagos priežiūros ir reguliavimo galimybes saugomose teritorijose. Tam buvo panaudoti skaitmeniniai Nemuno dugno reljefo ir dvimačiai hidrodinamikos modeliai. Ruožo modeliavimas buvo atliekamas programomis ArcView ir Danijos Hidraulikos institute (DHI) sukurtu hidrodinamikos modeliavimo programų paketu MIKE 21 HD. Hidrodinamikos modelis suderintas pagal nagrinėjamo ruožo projektinius vandens lygius ir debitus. Analizuojama vagos reguliavimo įtaka upės pralaidumui (debitams) įvairiomis hidrologinėmis sąlygomis. Buvo išnagrinėti įvairūs nagrinėjamo upės ruožo vagos reguliavimo variantai: vagos krantų ištiesinimas ir laivakelio pagilinus nuo 1,5 iki 2,5 m garantinio gylio. Analizuojant modeliavimo rezultatus įvertintos Nemuno vagos priežiūros ir reguliavimo galimybės atsižvelgiant į galiojančius teisės aktus. / In this work researching 3 km length the Nemunas river waterway in Šilutės district and searching various variants of the riverbed. This Nemunas river waterway in Šilutės district beside the Leitė river mouth has complicated situation of the river bed process. This is typical, without odd, the strip formed with many anthropogenic factors. In other way, this is very essential strip of landscape – ecology, recreation, cultural, economical and in other aspects, wherefore this research of channel section of the Nemunas river has undoubted scientific and practical substantiality. The main purpose of this paper is to analyse and evaluate the possibilities to maintain and regulate the Nemunas river bed in the protected areas. The digital models of the relief of the Nemunas bed and the two-dimensional models of hydrodynamics have been used for this purpose. Modelling of the section has been made by using the application ArcView and the software package for hydrodynamics modelling developed by the Danish Hydraulic Institute (DHI), i.e. MIKE 21 HD. The model of hydrodynamics is matched for the designed water levels and yields of the section under examination. The influence of levelling the shores of the bed in the section under examination, deepening the channel from 1.5 up to 2.5 m of the depth guaranteed and has been analyzed. While analysing the results of modelling, the possibilities of maintenance and regulation of the Nemunas river bed have been evaluated, taking into... [to full text]

Aurimas Bieliauskas, Nemuno vagos reguliavimas būnomis: magistro tezės/ mokslinis vadovas doc. Arvydas Šikšnys. Darbo apimtis: 50 psl., 1 lentelė, 21 paveikslas, 7 priedai. Šiame darbe nagrinėjamas 3 km ilgio Nemuno vandens kelio ruožas ties Leitės žiotimis ir tiriami įvairūs upės vagos reguliavimo variantai. Skaitmeniniuose hidrodinamikos modeliuose buvo tiriamas vagos reguliavimo poveikis upės hidrauliniam režimui esant įvairioms hidrologinėms sąlygoms. Išnagrinėtas vagos reguliavimas būnomis, kurių pagrindinė paskirtis - sumažinti vandens tėkmės greičius prie kranto linijos ir apsaugoti upės krantus nuo vandens erozijos, o laivakelio zonoje - padidinti tėkmės greičius ir sumažinti čia nusėdančių nešmenų kiekius. Pasirinktas Nemuno ruožas ties Leitės žiotimis pasižymi sudėtingomis vaginių procesų sąlygomis. Tai be įprastinių, daugybės antropogeninių veiksnių formuojamas ruožas. Kita vertus, tai labai svarbus ruožas kraštovaizdžio – gamtosaugos, rekreacijos, kultūros, ekonomikos ir kitais požiūriais. Darbo tikslas – išanalizuoti ir įvertinti Nemuno vagos reguliavimo būnomis įvairiais variantais poveikį upės hidrauliniam-hidrologiniam režimui. Modeliavimui buvo panaudota programa MIKE 21, buvo išanalizuoti 3 skirtingi vagos reguliavimo variantai, nustatyta būnų įtaka upės hidraulinėms charakteristikoms, apskaičiuoti darbų kiekiai. / Aurimas Bieliauskas. The riverbed regulation with spurs of the river Nemunas: master theses/ scientific guide doc. Arvydas Šikšnys. The amount of work: 50 pages, 1 tables, 21 pictures, 5 supplements. In this work is analyzed the modeling of riverbed of the Nemunas 3 km length the Nemunas beside the mouth of the Leitė river mouth. In the numerical hydrodynamic models there were searching effects of the river bed regulation of the river hydraulic regime in various conditions. In the analytical part there is analyzed the process of the riverbed regulation which the main purpose there is the reduction of the water velocity near banks and conservation of the banks from the water erosion. Another purpose there is the regulation of the water velocity in the waterway zone and reduction in the silt there. This is typical, without odd, the strip formed with many anthropogenic factors. In other way, this is very essential strip of landscape – ecology, recreation, cultural, economical and in other aspects, wherefore this research of channel section of the Nemunas river has undoubted scientific and practical substantiality. The aim of this work is to analyzing and estimation of the waterway regulation in numerous aspects and influence on the river hydraulic- hydrologic regime. The modeling had been made with program MIKE 21 and had analyzed free different variants of the river bed. While doing analysis there was found the influence of the river hydraulic characteristics and there was... [to full text]

<p>Cilj doktorske disertacije je pobolj&scaron;anje hidrodinamičkih i<br />masenoprenosnih karakteristika airlift reaktora sa<br />spolja&scaron;njom recirkulacijom umetanjem samo-rotirajućih<br />impelera u uzlaznu cev. Uticaj ugradnje samo-rotirajućih<br />impelera na osnovne hidrodinamičke i masenoprenosne<br />osobine ispitivan je pri radu sa različitim tečnostima i<br />distributorima gasa. Rezultati su tumačeni poređenjem<br />vrednosti za sadržaj gasa u uzlaznoj cevi, za brzinu<br />tečnosti u silaznoj cevi, i za zapreminski koeficijent<br />prenosa mase, dobijenih za dve konfiguracije reaktora (sa<br />i bez impelera).<br />Rezultati disertacije ukazuju da ugradnja samo-rotirajućih<br />impelera dovodi do znatnog razbijanja mehurova i<br />smanjenja srednjeg prečnika mehurova gasa, naročito u<br />viskoznim rastvorima karboksimetilceluloze. Prividna<br />brzina gasa, vrsta tečne faze i tip distributora gasa u<br />velikoj meri utiču na efikasnost samo-rotirajućih impelera.<br />Dobijene vrednosti sadržaja gasa u uzlaznoj cevi su do<br />47% veće u konfiguraciji sa impelerima u odnosu na<br />konfiguraciju bez impelera. Iako samo-rotirajući impeleri<br />predstavljaju dodatni otpor proticanju tečnosti, njihovom<br />ugradnjom je u svim ispitivanim sistemima postignuto<br />relativno malo smanjenje brzine tečnosti (oko 10%).<br />Zahvaljujući impelerima, zapreminski koeficijent prenosa<br />mase uvećan je do 82% pri manjim protocima gasa. Pri<br />većim protocima, koji odgovaraju uslovima rada koji se<br />sreću u većini fermentacionih procesa, postignute su oko<br />20-30% veće vrednosti zapreminskog koeficijenta prenosa<br />mase.<br />Pored empirijskih modela, u ovom radu uspe&scaron;no su<br />razvijeni i modeli ve&scaron;tačkih neuronskih mreža kojim se<br />predviđaju sadržaj gasa u uzlaznoj cevi, brzina tečnosti i<br />zapreminski koeficijent prenosa mase za obe konfiguracije<br />airlift reaktora sa spolja&scaron;njom recirkulacijom.</p> / <p>The aim of this study was intensification of<br />hydrodynamic and mass transfer properties of<br />external-loop airlift reactor by means of self-agitated<br />impellers mounted in the riser section. The influence<br />of impellers&rsquo; insertion on the main hydrodynamic<br />and mass transfer characteristics was investigated for<br />various liquid phases and sparger types. The values<br />of riser gas holdup, downcomer liquid velocity and<br />volumetric mass transfer coefficient obtained in<br />configurations with and without impellers were<br />compared.<br />Results showed that the installment of self-agitated<br />impellers led to a significant bubble breakage and<br />decrease of bubble size, especially in viscous<br />carboxymethylcellulose solutions. The efficiency of<br />self-agitated impellers was immensely influenced by<br />superficial gas velocity, liquid phase, and distributor<br />type. Obtained riser gas holdup values were up to<br />47% higher in the configuration with impellers, in<br />comparison to the configuration wthout impellers.<br />Despite the fact that self-agitated impellers<br />represented an obstacle to liquid flow, relatively low<br />reduction of downcomer liquid velocity was attained<br />(about 10%). Furthermore, the insertion of impellers<br />induced up to 82% higher values of volumetric mass<br />transfer coefficient at lower superficial gas velocities.<br />At higher superficial gas velocities, i.e. conditions<br />mainly operated in various fermentation processes,<br />about 20-30% higher values of volumetric mass<br />transfer coefficient were achieved with impellers.<br />In addition to empirical correlations, artificial neural<br />network models were sucessfully developed to<br />predict riser gas holdup, downcomer liquid velocity<br />and volumetric mass transfer coefficient in both<br />external-loop airlift configurations.</p>

Darbe nagrinėjami nenusistovėjusio vandens tekėjimo reiškiniai, kurie atsiranda Kruonio HAE reversiniame kanale dėl netolygaus hidroagregatų veikimo juos paleidžiant ir stabdant. Tyrimų tikslas - nustatyti nenusistovėjusio tekėjimo dėsningumus Kruonio HAE reversiniame kanale ir jam artimiausioje Kauno marių dalyje. Tyrimų metodas – hidrodinamikos skaitmeninis modeliavimas MIKE21 aplinkoje. Hidrodinamikos modelyje panaudotas reversinio kanalo dugno skaitmeninis reljefo modelis, sudarytas stačiakampių gardelių tinklo (grido) pavidalu pagal naujausius batimetrinių matavimų rezultatus. Elementarių gardelių matmenys 5x5 m. Modelio pakraštinėms sąlygoms aprašyti pasirenkamos laiko funkcijos, kurios išreiškia kiekvieno HAE hidroagregato vandens debito kitimą laiko atžvilgiu įvairių modeliuojamų HAE darbo režimų scenarijuose. Kitoje modelio atviroje riboje nustatomas fiksuotas Kauno marių vandens lygis. Hidrodinamikos modeliavimo rezultatai išvedami ir užrašomi kiekvienu skaičiuojamojo laiko žingsniu, o jų analizė atliekama naudojant MIKE21 programų paketo įrankius. Hidrodinamikos modeliavimo rezultatų tikslumui ir patikimumui įvertinti buvo atlikta modelio patikra (t.y. verifikavimas), kurioje panaudoti realiai išmatuotų vandens lygių dinamikos ir tėkmės vektorių lauko krypčių vizualinių stebėjimų rezultatai. Analizuojant gautus modeliavimo rezultatus buvo nustatyti nenusistovėjusio vandens tekėjimo Kruonio HAE reversiniame kanale dėsningumai, kurie pasireiškia staigaus... [toliau žr. visą tekstą] / This work deals with fluctuations in the water flow regime that occur in the outlet channel of the Kruonis Pumped Storage Plant and are produced by uneven running of hydrounits while starting and stopping them. Research purpose: to determine the patterns of fluctuations in the water flow regime that occur in the outlet channel of the Kruonis Pumped Storage Plant and the nearest part of Kaunas Lagoon. Research method: numerical modeling of hydrodynamics in the MIKE21 environment. A digital terrain model of the reverse channel bottom consisting of a rectangular grid network (grid), made following the latest bathymetric measurements, was used for the hydrodynamic model. The elementary grid cell dimentions in the model were 5x5 m. To describe the boundary conditions of the model, time functions which express the water flow rate changes over time of each hydrounit in different operating modes of the KPSP were chosen. The fixed Kaunas Reservoir water level was set in the model as the other open boundary. The results of the hydrodynamic modeling were output and recorded at each computational time step and their analysis was performed using MIKE21 software package tools. To evaluate the accuracy and reliability of the hydrodynamic simulation results, a verification of the model was performed, which used the results of visual monitoring of actually measured water level dynamics and flow vector field directions . Analyzing the findings of simulation, consistent patterns of the... [to full text]

<p>U radu su predstavljeni rezultati&nbsp; ispitivanja biolo&scaron;ke&nbsp;<br />stabilnosti vode za piće primenom rotirajućih prstenastih reaktora (eng.&nbsp;<br />rotating annular reactor, RAR). Pomoću RAR praćen je uticaj odabranih&nbsp;<br />faktora na suspendovani i pričvr&scaron;ćeni mikrobni rast pri kontrolisanim&nbsp;<br />laboratorijskim uslovima koji su simulirali distributivne sisteme. Pored&nbsp;<br />toga, u cilju potpunog razumevanja biolo&scaron;ke stabilnosti vode za piće&nbsp;<br />izvr&scaron;eno je ispitivanje metoda za određivanje biodegradabilne frakcije<br />organske materije, BDOC i AOC test.</p><p>Poređenjem BDOC testova sa nativnom populacijom bakterija&nbsp;<br />pričvr&scaron;ćenom za pesak iantracit utvrđena je efikasnija primena biolo&scaron;kog&nbsp;<br />aktivnog peska. Primenom peska za inokulaciju uzorka, vrednost BDOC&nbsp;<br />u podzemnoj vodi sa teritorije srednjeg Banata iznosila je 1,27 mgC/l. U<br />ispitivanju AOC testa sa suspendovanim standardnim kulturama&nbsp;<br />Pseudomonas fluorescens P17 (ATCC 49642) i Spirillum sp. NOX&nbsp;<br />(ATCC 49643), AOC iskori&scaron;ćen od strane NOX je imao veću vrednost u&nbsp;<br />odnosu na P17, &scaron;to pokazuje da su karboksilne kiseline dominantan&nbsp;<br />supstrat za rast. Vrednost AOC u tretiranoj podzemnoj vodi iznosila 32&nbsp;<br />&mu;g acetat-C/l. Veće vrednosti BDOC ukazuju na prisustvo jedinjenja&nbsp;<br />veće molekulske mase u ovoj frakciji u odnosu na AOC frakciju&nbsp;<br />biodegradabilne organske materije.</p><p>U ispitivanju biostabilnosti podzemne vode sa teritorije srednjeg&nbsp;<br />Banatatokom tretmana, najveća količina biofilma je razvijena u RAR sa&nbsp;<br />ozoniranom vodom (13,30 CFU/cm²), &scaron;to potvrđuje efekte ozonizacije na&nbsp;<br />biodegradabilnost organske materije i ponovni rast mikroorganizama.&nbsp;<br />Tokom tretmana zabeleženo je variranje razvoja biofilma, pri čemu je&nbsp;<br />najmanji stepen rasta biofilma uočen u RAR sa vodom nakon GAC&nbsp;<br />filtracije (1,10 CFU/cm²).</p><p>Tokom mikrobne kolonizacije test-pločica RAR pri laminarnom i&nbsp;<br />turbulentnom protoku uočen je sličan trend rasta bakterija u biofilmu u sintetičkoj sme&scaron;i organskih i neorganskih nutrijenata. Međutim, tokom dominacije suspendovanog rasta u sistemu voda-biofilm pri neprotocnim uslovima, pona&scaron;anje biofilmova razvijenih pri protočnim (laminarnim i turbulentnim) uslovima je bilo različto. Uočen je manji udeo bakterija prisutnih u vodenoj fazi kod biofilma nastalim pri turbulentnom protoku u odnosu na veće oslobađanje ćelija iz biofilma nastalim pri laminarnim uslovima, nakon 48h 78% i 89% suspendovanih bakterija, redom. Ovi rezultati pokazuju da su biofilmovi razvijeni pri turbulentnom protoku snažniji, stabilniji &nbsp; i jače pričvr&scaron;ćeni nego pri laminarnom protoku.</p><p>Tokom praćenja sekundarne kolonizacije odvojenih ćelija biofilma&nbsp;<br />uočeno je da se primarni biofilm pona&scaron;a kao stalni rezervoar ćelija koje&nbsp;<br />su sposobne da zauzmu nove povr&scaron;ine vrlo brzo pri različitim&nbsp;<br />hidrodinamičkim uslovima. Brojnost bakterija u biofilmu razvijenom na&nbsp;<br />sekundarnim test-pločicama nakon 24 h iznosila je 32000&plusmn;1200&nbsp;CFU/cm^2&nbsp;<br />u odnosu na 16&plusmn;1 CFU/cm^2&nbsp;primarne test-pločice. Ustanovljen&nbsp;<br />je izraženiji potencijal kolonizacije novih povr&scaron;ina odvojenim želijama iz&nbsp;<br />primarnog biofilma koji je formiran pri turbulentnim uslovima u odnosu&nbsp;<br />na laminarne uslove.</p><p>Proces stvaranja biofilma na test-pločicama od nerđajućeg čelika&nbsp;<br />(SS), polivinilhlorida(PVC) i polietilena(PE) je bio vrlo sličan. Samo&nbsp;<br />debljina biofilma je bila veća na PE (4,0-5,5 kg/m³) nego na SS i PVC&nbsp;<br />test-pločicama (2,7-3,6 kg/m^3&nbsp;i 2,8-3,9 kg/m³, redom). Ustanovljen je&nbsp;<br />uticaj materijala cevi na rast biofilma u RAR snabdevanim vodom iz&nbsp;<br />distributivnog sistema grada Novog Sada, naročito za vreme početne faze&nbsp;<br />procesa. Biofilmovi formirani na različitim materijalima u RAR su uticali&nbsp;<br />na mikrobiolo&scaron;ki kvalitet vode, zavisno od njihove bakterijske gustine.&nbsp;</p><p>SEM analiza potvrdila je prisustvo biofilma na test-pločicama u&nbsp;<br />eksperimentima, ukazujući na uspe!nu primenu RAR u ispitivanju&nbsp;<br />biofilma i biostabilnosti vode za piće.</p><p>Rezultati dobijeni tokom ispitivanja ukazuju da se primenom&nbsp;<br />odabranih i optimizovanih, zavisno od cilja ispitivanja i vrste uzorka,&nbsp;<br />BDOC i AOC testova može efikasno definisati biolo!ka stabilnost vode&nbsp;<br />za piće. Pored toga, sistematski pristup odabiru odgovarajućih materijala&nbsp;<br />cevi, koji je zasnovan na pouzdanim testovima i definisanim&nbsp;<br />kriterijumima, može se primeniti u cilju osiguravanja kvaliteta vode sa&nbsp;<br />mikrobiolo&scaron;kog aspekta.</p><p>Ispitivanja su pokazala uspe&scaron;nu primenuRAR u simulaciji&nbsp;<br />mikrobnog rasta u cevima pri kontrolisanim laboratorijskim uslovima i&nbsp;<br />značaj istovremenog ispitivanja imobilisanog i suspendovanog rasta u&nbsp;<br />definisanom hidrodinamičkom sistemu.&nbsp; Primena RAR kao model biofilma je ukazala na njegov značaj u ispitivanju potencijala ponovnog naseljavanja povr&scaron;ina otkinutih delova i/ili pojedinačnih ćelija biofilma za uspostavljanje efikasne kontrole mikrobnih problema u distributivnim sitemima vode za piće.</p> / <p>This thesis presents theresults of investigation of drinking water biostability using the&nbsp; rotating annular reactor (RAR). The effects of selected factors on the suspended and attached microbial growth under controlled laboratory conditions that simulated the&nbsp;distribution systems were monitored using RAR. In addition, in order to completeunderstanding of the drinking water biological stability,&nbsp;methods for determining biodegradable organic matter fractions, BDOC&nbsp;and AOC methods were tested.</p><p>Comparing the BDOC tests with the native population of bacteria&nbsp;attached to sand and anthracite, a better application of biologically active&nbsp;sand was established. Using BDOC test with sand, the BDOC value in&nbsp;groundwater from the territory of the Central Banat (Republic of Serbia)&nbsp;was 1.27 mgC/L. In the investigation of AOC tests with standard&nbsp;<br />suspended culture of Pseudomonas fluorescens P17(ATCC 49642) and&nbsp;Sprillumsp. NOX (ATCC 49643), AOC utilized by NOX had a higher&nbsp;value compared to the P17, which shows that the carboxylic acid are&nbsp;dominant substrate for growth. The AOC value in the treated ground&nbsp;water was 32 &mu;g acetate-C/L. The higher BDOC values indicate the&nbsp;presence of higher molecular weight compounds in this fraction&nbsp;compared to the AOC biodegradable fraction of organic matter.&nbsp;</p><p>In the investigation of biostability during treatment of&nbsp;groundwater from the territory of the Central Banat (Republic of Serbia),&nbsp;the largest amount of biofilm was developed in the RAR with ozonated&nbsp;water (13.30 CFU/cm²), confirming the effects of ozonation on organic&nbsp;matter biodegradability and microbial regrowth. During treatment the&nbsp;<br />variation of biofilm development was detected and in the RAR with water after GAC filtration the lowest level of biofilm growth (1.10 CFU/cm²) was observed.&nbsp;</p><p><span style="font-size: 12px;">During the microbial colonization of the RAR test-coupons under&nbsp;</span><span style="font-size: 12px;">laminar and turbulent flow, the similar trend of growth of bacteria in the&nbsp;</span><span style="font-size: 12px;">biofilm in synthetic mixture of organic &nbsp;and inorganic nutrients was&nbsp;</span><span style="font-size: 12px;">observed. However, the higher numbers of immobilized bacteria under&nbsp;</span><span style="font-size: 12px;">the turbulent conditions in the same growth period (16 days) were&nbsp;</span><span style="font-size: 12px;">recorded. During the domination of suspended growth in water-biofilm system under &nbsp;non-flow conditions, the behavior of biofilms developed under flow (laminar and turbulent) conditions were different. There was a smaller proportion of bacteria present inthe aqueous phase of the biofilm formed under the turbulent flow over a larger release of cells &nbsp;from biofilms formed under laminar conditions, after 48h 78% and 89% of the suspended &nbsp;bacteria, respectively. These results indicate that biofilms developed under turbulent flow &nbsp;were stronger, more stable and more strongly attached than the ones under laminar flow.</span></p><p>During monitoring of the secondary colonization of the dettached&nbsp;biofilm cells, it was noted that the primary biofilm was a constant&nbsp;reservoir of cells that are able to occupy the new areas very quickly&nbsp;under different hydrodynamic conditions. The abundance of bacteria in&nbsp;the biofilm developed on the secondary test-coupons after 24 h was 32&nbsp;<br />000&plusmn;1200 CFU/cm² compared to 16&plusmn;1 CFU/cm²on the primary test-coupons. A stronger potential for colonization of new areas by dettached&nbsp;cells from the primary biofilm formed under the turbulent conditions in&nbsp;comparison to laminar conditions was found.&nbsp;</p><p>The biofilm formation processes on SS, PVC and PE test-coupons&nbsp;werevery similar. Only biofilm thickness was greater on the PE (4.0 to&nbsp;5.5 kg/m³) than the SS and PVC &nbsp;test-coupons (2.7 to 3.6 kg/m³ and 2.8 to&nbsp;3.9 kg/m³, respectively). There was a slight influence of pipe material on&nbsp;the biofilm growth, especially during the initial stages of the process.&nbsp;Biofilms formed on different materials in the RAR with water from the&nbsp;distribution system of the city of Novi Sad (Vojvodina, Republic of&nbsp;Serbia) have showed the influence on the microbiological quality of&nbsp;water, depending on their bacterial density.</p><p>SEM analysis confirmed the biofilm presence on test-coupons in&nbsp;the experiments, indicating the successful implementation of RAR in the&nbsp;examination of biofilm and drinking water biostability.&nbsp;</p><p><span style="font-size: 12px;">The results obtained during the investigations indicate that the&nbsp;</span><span style="font-size: 12px;">application of selected and optimized, depending on the test objective&nbsp;</span><span style="font-size: 12px;">and sample types, BDOC and AOC tests can effectively define the&nbsp; biological stability. In addition, a systematic approach for &nbsp;electing appropriate pipe materials, which is based on reliable tests and defined criteria, specific for the investigated drinking water distribution system can be applied to ensure &nbsp;he water quality from a microbiological point of view.</span></p><p>The investigations have shown the successful application of RAR&nbsp;in the simulation of microbial growth in the pipes under controlled&nbsp;laboratory conditions as well as the importance of simultaneous&nbsp;examination of immobilized and suspended growth under defined&nbsp;hydrodynamic system. Implementation of RAR as amodel biofilm&nbsp;indicated its importance in examining the potential resettlement area by&nbsp;dettached parts and/or individual biofilm cells to establish effective&nbsp;control of microbial problems in the drinking water distribution system.&nbsp;</p>

The transport of cosmic rays in the heliosphere is studied by making use of a newly developed modulation model. This model employes stochastic differential equations to numerically solve the relevant transport equation, making use of this approach’s numerical advantages as well as the opportunity to extract additional information regarding cosmic ray transport and the processes responsible for it. The propagation times and energy losses of galactic electrons and protons are calculated for different drift cycles. It is confirmed that protons and electrons lose the same amount of rigidity when they experience the same transport processes. These particles spend more time in the heliosphere, and also lose more energy, in the drift cycle where they drift towards Earth mainly along the heliospheric current sheet. The propagation times of galactic protons from the heliopause to Earth are calculated for increasing heliospheric tilt angles and it is found that current sheet drift becomes less effective with increasing solar activity. Comparing calculated propagation times of Jovian electrons with observations, the transport parameters are constrained to find that 50% of 6 MeV electrons measured at Earth are of Jovian origin. Charge-sign dependent modulation is modelled by simulating the proton to anti-proton ratio at Earth and comparing the results to recent PAMELA observations. A hybrid cosmic ray modulation model is constructed by coupling the numerical modulation model to the heliospheric environment as simulated by a magneto-hydrodynamic model. Using this model, it is shown that cosmic ray modulation persists beyond the heliopause. The level of modulation in this region is found to exhibit solar cycle related changes and, more importantly, is independent of the magnitude of the individual diffusion coefficients, but is rather determined by the ratio of parallel to perpendicular diffusion. / PhD (Space Physics), North-West University, Potchefstroom Campus, 2013

The transport of cosmic rays in the heliosphere is studied by making use of a newly developed modulation model. This model employes stochastic differential equations to numerically solve the relevant transport equation, making use of this approach’s numerical advantages as well as the opportunity to extract additional information regarding cosmic ray transport and the processes responsible for it. The propagation times and energy losses of galactic electrons and protons are calculated for different drift cycles. It is confirmed that protons and electrons lose the same amount of rigidity when they experience the same transport processes. These particles spend more time in the heliosphere, and also lose more energy, in the drift cycle where they drift towards Earth mainly along the heliospheric current sheet. The propagation times of galactic protons from the heliopause to Earth are calculated for increasing heliospheric tilt angles and it is found that current sheet drift becomes less effective with increasing solar activity. Comparing calculated propagation times of Jovian electrons with observations, the transport parameters are constrained to find that 50% of 6 MeV electrons measured at Earth are of Jovian origin. Charge-sign dependent modulation is modelled by simulating the proton to anti-proton ratio at Earth and comparing the results to recent PAMELA observations. A hybrid cosmic ray modulation model is constructed by coupling the numerical modulation model to the heliospheric environment as simulated by a magneto-hydrodynamic model. Using this model, it is shown that cosmic ray modulation persists beyond the heliopause. The level of modulation in this region is found to exhibit solar cycle related changes and, more importantly, is independent of the magnitude of the individual diffusion coefficients, but is rather determined by the ratio of parallel to perpendicular diffusion. / PhD (Space Physics), North-West University, Potchefstroom Campus, 2013