Stilling basin flow for stepped spillways

Kod preliva visokih brana, umirujući bazeni predstavljaju najčešće korišćeno rešenje za disipaciju mehaničke energije vode pre njenog ispuštanja u nizvodno rečno korito. Zbog značaja i visoke efikasnosti, umirujući bazeni detaljno su izučavani, prvenstveno u sprezi sa glatkim brzotocima. Disipacione sposobnosti umirujućih bazena mogu se poboljšati upotrebom različitih stabilizacionih elemenata, čiji efekti omogućavaju smanjenje dužine hidrauličkog skoka, odnosno gabarita bazena. Slični efekti mogu se postići i promenom podužnog nagiba dna bazena. Razvoj tehnologije valjanog betona pospešio je primenu stepenastih brzotoka, koje (u odnosu na glatke) odlikuje bolja disipacija mehaničke energije. Međutim, uslovi strujanja koji pritom nastaju – intenzivnije mešanje vode i vazduha, praćeno povećanjem dubine – bitno se razlikuju od onih koji su poslužili pri razvoju preporuka za tipske bazene sa stabilizacionim elementima. Iako tipski bazeni i u slučaju stepenastih brzotoka mogu pojačati disipaciju energije, njihovi efekti su slabiji od očekivanih. Zbog toga je od posebnog značaja procena uticaja gabarita i položaja stabilizacionih elemenata tipskih bazena koji su namenjeni za glatke brzotoke, na disipaciju energije u bazenima stepenastih brzotoka. Ovo istraživanje posvećeno je ispitivanju uticaja koji stepenasta kontura brzotoka ima na efikasnost disipacije mehaničke energije u umirujućem bazenu. Pri tome, ispitani su bazeni sa horizontalnim dnom i bazeni sa dnom u negativnom podužnom nagibu i to, sa i bez, dodatnih stabilizacionih elemenata. Ocena kvaliteta disipacije mehaničke energije sprovedena je prvenstveno na osnovu rezultata merenja dubina i brzina tečenja, za šta su korišćene savremene metode beskontaktnog merenja, bazirane na tehnikama obrade slika iz video zapisa eksperimenta.Stilling basins are the most commonly used structures for the large dam spillways energy dissipation. Due to their high efficiency, stilling basins (with the hydraulic jumps) are well investigated, mainly for smooth spillways. Energy dissipating capabilities of the stilling basins can be improved with the use of different types of stabilizing elements, which allow for the reduction of the hydraulic jump length and consequently for the size of the stilling basin. Similar effect can be achieved by changing the basin bed slope. Development of the roller compacted concrete technology has encouraged the use of the stepped spillways which (relative to the smooth spillways) have higher energy dissipation rate. However, the resulting flow conditions (more intense air–water mixing, coupled with higher flow depths) differ from those for which the standardized basins with stabilizing elements were developed. Consequently, the use of standardized basins can increase energy dissipation, but the effects are lower than expected. Hence, the assessment of the effects of the dimensions and position of the standardized-basins stabilizing elements for smooth chutes, on the efficiency of energy dissipation of stepped-spillway basins, is of special interest. This research concerns the impact that stepped spillway can produce on the energy dissipation efficiency of the stilling basin. Hence, horizontal and negative slope stilling basins were investigated, with and without the use of the stabilizing elements. Assessment of the energy dissipation efficiency is based mainly on the results of depth and velocity measurements, which were performed using contactless methods, based on image processing approach. Results of this investigation indicate that the energy dissipation quality of stepped spillway stilling basins can be improved using the stabilizing elements for smooth-chute basins, but with modified dimensions and position, as well as using the negative basin bed slopes. Therefore, the estimation of the main flow parameters for the basins with stabilizing elements, and negative–sloped basins is presented. The significance of the research is also shown through the use and development of state-of-the-art contactless measurement techniques: (1) Laser Particle Image Velocimetry (Laser PIV) technique was successfully applied for the estimation of flow velocities downstream of the hydraulic jump roller, and (2) a novel method for the estimation of the flow depths is presented, based on the image processing approach. Ultimately, the analysis of the obtained data provided design recommendations for the stepped-spillway stilling-basin design

Endobronhalnim ultrazvukom vođena aspiracija tankom iglom (EBUS-TBNA): Phyllodes tumor s me- tastazom u medijastinumu, vrlo rijedak tip metastatske neoplazme dojke

Phyllodes tumor of the breast, diagnosed predominantly in middle-aged women, is a rare fi- broepithelial neoplasm that makes up less than 1% of all breast neoplasms. Most phyllodes tumors have a benign nature with rare local recurrences, but some cytological subtypes are known for their malignant behavior. In this case report, we presented a patient with an extremely rare malignant sarcomatous differentiation of phyllodes tumor with metastasis to mediastinal lymph nodes, diagnosed by using endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA).Phyllodes (filoidni) tumor dojke, dijagnosticiran pretežno u žena srednje dobi, rijetka je fibroepitelna neo- plazma koja čini manje od 1% svih neoplazmi dojke. Većina filoidnih tumora dojke ima benignu prirodu s rijetkim lokalnim recidivima, ali određeni citološki podtipovi poznati su po svom malignom ponašanju. U ovom prikazu slučaja prikazali smo bolesnicu s iznimno rijetkom malignom sarkomatoznom diferencijacijom tumora filoidesa s metastazama u medijastinalne limfne čvorove, dijagnosticiranom uz pomoć transbronhalne aspiracije iglom vođene endobronhalnim ultrazvukom (engl. Endobronchial ultrasound-guided transbronchial needle aspiration, EBUS-TBNA)

Endobronchial ultrasound-guided transbronchial fine needle aspiration (EBUSTBNA): Solitary fibrous tumor of the mediastinum

A solitary fibrous tumor is a rare type of mesenchymal neoplasm with a described incidence of 1 new case in a million people a year. It is slowgrowing tumor that can arise almost anywhere in the body, usually with benign characteristics with little or no symptoms, until it grows big enough to cause symptoms of compression. In this case report we presented a patient with a rare case of a mediastinal solitary fibrous tumor

Maligna bolest, ili je nešto drugo?

Sarcoidosis is a disease characterized by formation of granulomas in various tissues and organs. Changes most frequently occur in the lungs and lymph nodes.Sarkoidoza je bolest karakterizirana rastom granuloma u raznim tkivima i organima. Ove promjene se najčešće pojavljuju u plućima i limfnim čvorovima

Primena kamera i tehnika obrade video zapisa za procenu protoka u kanalizacionim sistemima - iskustva merne kampanje Novi Banovci

Tehnike merenja u hidrotehnici zasnovane na upotrebi kamera i naknadnoj obradi video zapisa u trendu su poslednje dve decenije. Odlikuju ih tehnička jednostavnost, niska cena i prilagodljivost hardvera i softvera. Međutim, primena za merenje protoka u kanalizacionim sistemima nije analizirana u literaturi. Tim Građevinskog fakulteta Univerziteta u Beogradu osmislio je, konstruisao i postavio merni uređaj, baterijski napajan mikroračunar sa IC kamerom u kanalizacioni šaht u naselju Novi Banovci radi kontinualnog merenja dotoka upotrebljene vode. Rad prikazuje specifičnosti upotrebe mernog uređaja i tehnike obrade video zapisa. Preliminarni rezultati pokazuju potencijal razvijene metodologije, posebno tamo gde konvencionalna oprema nije primenjiva

SSIMS-FLOW: Flow Rate Estimation Tool Using Surface Velocity Imagery From Unmanned Aerial Vehicles

Merenje protoka u otvorenim kanalima često je dugotrajan, invazivan, složen i skup poduhvat, koji neretko uključuje veći broj naročito obučenih rukovaoca opremom, i različite naknadne obrade podataka sa terena. Razvoj tehnologije lakih bespilotnih letelica opremljenih kamerama omogućio je alternativan pristup posrednog merenja protoka putem analize polja površinskih brzina u otvorenom toku. Iako merenja ovom metodom pružaju podatke više merne neizvesnosti od konvencionalnih mernih metoda, opisana procedura beskontaktnog merenja protoka je (1) vremenski efikasnija, (2) zahteva manji broj rukovaoca opremom, (3) primenjiva čak i u određenim uslovima u kojima konvencionalne metode nisu i (4) otvara mogućnost automatizovanog i autonomnog monitoringa vodotoka. Procedura hidrometrijske analize video zapisa još uvek nije standardizovana, i na tržištu se teško pronalazi alat koji uspešno obavlja sve korake neophodne za dobijanje podataka o brzinama i protoku. Alat SSIMS-Flow razvijen je sa ciljem da omogući lak pristup različitim koracima pripreme i procesiranja podataka iz video zapisa u sveobuhvatnom procesu – od pripreme „sirovog“ video zapisa do procene vrednosti protoka – čime se drastično pojednostavljuje primena opisane metoda merenja.Open-channel flow rate measurement is often a time consuming, invasive, complex, and expensive procedure, which frequently requires involvement of multiple equipment operators and various postprocessing techniques. The development of camera-equipped lightweight unmanned aerial vehicles has enabled an alternative approach of indirect flow rate measurement by analyzing the surface flow velocities. Although the data acquired by this approach experiences somewhat higher measurement uncertainty than that of conventional measurement techniques, such non-contact measurement method is (1) more time efficient, (2) requires fewer operators, (3) can be applied in certain conditions when conventional methods are unfeasible, and (4) allows for automated and autonomous flow monitoring. Hydrometric analyses of video footage are still unstandardized, and finding a suitable tool which successfully deals with all the necessary actions for velocity and flow estimation has proven to be difficult. SSIMS-Flow tool is developed with the aim of providing easy access to different actions of video footage data preparation and processing to enable a holistic process – from preparing a “raw” video footage to the estimation of flow rate – which drastically simplifies the described approach.M51, Originalni naučni rad, UDK: 532.570.

Hidraulički proračun umirujućeg bazena neprizmatičnog stepenastog brzotoka

The influence of converging stepped spillways on dimensions of the stilling basins for RCC dams was studied, based on the results of physical modeling, existing empirical expressions, and basic laws of fluid mechanics and hydraulics. The study includes analysis of parameters that affect the magnitude of a hydrodynamic force which is transferred into the stilling basin, and presents an original design methodology. A procedure for simplifying the optimization process for the entire spillway is proposed.Zbornik radova Građevinskog fakultet

Wastewater flow measurements in sewer networks: Combining innovative and conventional measurement methods

Jedan od preduslova za efikasno upravljanje i strateško planiranje razvoja kanalizacionih sistema je dobro poznavanje dinamike rada mreže. Ključnu ulogu imaju mereni podaci, prvenstveno o promenama protoka i nivoa, kako u sušnom tako i u kišnom period. Nažalost, kanalizacione mreže su u većini slučajeva slabo pokrivene adekvatnim mernim mestima. Tako prilikom planiranja kapitalnih investicija, npr. postrojenja za prečišćavanje otpadnih voda, nedostajući podaci se obezbeđuju kroz merne kampanje. Ključni izazovi pri sprovođenju mernih kampanja su povezani sa lokacijski i hidraulički nepovoljnim mernim lokacijama, koje negativno utiču na kvalitet izmerenih podataka. U ovom radu je prikazan primer kombinovanja inovativnih sa konvencionalnim metodama za merenja protoka u kanalizacionim sistemima sa ciljem dobijanja reprezentativnih podataka u složenim mernim uslovima.One of the prerequisites for efficient management and development planning of the sewer systems is the adequate knowledge of network dynamics. Measured data play a key role, mainly the flow rate and level variations in dry and wet periods. Unfortunately, sewer networks are commonly scarcely covered with measurement systems. Thus, when capital investments are planned, e.g. wastewater treatment plants (WWTP), missing data is acquired through measurement campaigns. Challenges in the execution of the measurement campaigns are mostly correlated to hydraulically and organizationally unfavorable measurement locations, reflecting negatively on the quality of the measured data. In this paper, an example of the combination of the innovative and conventional flow measurement methods in sewer networks is shown, to allow for the acquisition of the representative data in complex measurement conditions