Hydrodynamic Loads on the Evacuation Facilities of Hydraulic Structures.

У оквиру докторске дисертације су анализирани хидродинамички утицаји на зидове и дно умирујућег базена иза степенастог брзотока гравитационих бетонских брана. На физичком моделу је испитан утицај геометријских карактеристика степенастог брзотока (степен сужења и висина степеника) и параметара течења (протока и дубине доње воде) на хидродинамичка оптерећења у умирујућем базену. На основу анализе резултата моделских испитивања, изведене су емпиријске једначине, којима се, у зависности од поменутих параметара, описују хидродинамички притисци на зидове и дно умирујућег базена. Провера предложених емпиријских израза извршена је на резултатима хидрауличких моделских испитивања степенастог пелива на брани „Бузина“. Резултати испитивања на физичком моделу затим су коришћени за одређивање емпиријских израза за добијање меродавних хидродинамичких утицаја на зидове и дно умирујућег базена. На основу добијених резултата предложене су мере за осигурање умирујућег базена од појаве потпритисака, односно од штетних утицаја кавитационе ерозије услед хидродинамичких утицаја. Резултати овог истраживања се могу успешно применити при пројектовању умирујућих базена, пре свега у нижим фазама пројектовања.Hydrodynamic loads on the walls and the bottom of the stilling basin downstream of the stepped chute of a concrete gravity dam have been analysed. A physical scale model was constructed to invetigate the influence of the stepped chute geometry (the constriction angle and the step height) and flow characteristics (discharge, expressed via the Froude number at the constriction, and the downstream flow depth) on the hydrodynamic loads in the stilling basin. Based on the scale model results, new empirical expressions for the assessment of hydraulic loads on the walls and the bottom of the stilling basin are proposed. In addition, the risk of flow induced vibrations and cavitation were estimated. The obtained expressions were tested and validated using the results obtained on the physical scale model of the Buzina dam stepped spillway. The obtained results can be used during the early design stages for the assessment of hydrodynamic loads in stilling basins

Quantification of biofilm formation on silicone intranasal splints: An in vitro study

Objectives: Biofilms are associated with persistent infections and resistant to conventional therapeutic strategies. The aim of this study was to investigate the quantity of biofilm produced on silicone intranasal splints. Methods: Quantity of biofilm formation on silicone splints (SS) was tested on 15 strains of Staphylococcus aureus and Moraxella catarrhalis, respectively. Antimicrobial susceptibility testing was performed in accordance with European Committee on Antimicrobial Susceptibility Testing recommendations. Results: All tested strains formed different amounts of biofilm on SS: 66.7% S. aureus and 93.3% M. catarrhalis were weak biofilm producers and 33.3% S. aureus and 6.7% M. catarrhalis were moderate biofilm producers. S. aureus formed significantly higher quantity of biofilm compared with M. catarrhalis (p  Conclusion: Quantity of biofilm on SS is highly dependent on bacterial species and their resistance patterns. Future studies are needed to ascertain another therapeutic option for prophylaxis prior to SS placement

Optimal location and sizing of capacitor banks in distribution networks to reduce harmonic distortion and improve voltage profile using genetic algorithm

This paper considers the problem of determination of optimum locations and sizes of capacitor banks (CB) for reactive power compensation in distribution systems to reduce harmonic distortion and improve voltage profile. Genetic Algorithm (GA) was used for solving this non-linear multi-objective optimization problem with constraints. A detailed methodology was presented for solving the power flow problem at fundamental and higher harmonic frequencies of interest and models of network components in harmonic analysis. The proposed procedure was successfully tested on the standard IEEE 33-bus test system for three different objective functions. Calculations showed the efficiency of GA for solving this complex problem

Surface modifications of Ti6A14V by a picosecond Nd:YAG laser

Interaction of a Nd:YAG laser, operating at wavelengths of 1064 nm (23.6 J cm(-2) fluence) or 532 nm (25.9 J cm(-2) fluence), and pulse duration of 40 ps, with a titanium-based medical implant Ti6A14V alloy was studied. Surface at laser wavelengths 1064 nm and 532 rim, damage thresholds were estimated to be 0.9 J cm(-2) and 0.25 J cm(-2) respectively. At both laser wavelengths, the energy absorbed was mostly converted into thermal energy, forming craters, albeit about 50 times deeper at 1064 run than at 532 run. Periodic surface structures (PSS) were also formed with both laser wavelengths, concentric, and radial at micrometer scale (3 mu m to 15 mu m period), parallel at nanometer scale (800 nm period with the 1064 nm laser, 400 nm with The 532 nm laser). In the case of the 532 nm laser, the concentric Structures enlarge their period with accumulating laser pulse count. These features can help roughening of the implant surface and improve bio-compatibility

Controlling the thermal environment of underground power cables adjacent to heating pipeline using the pavement surface radiation properties

This paper shows how the pavement surface radiation properties can be used to control the thermal environment of 110 kV underground cables in order to increase their ampacity. It is assumed that the ampacity is additionally affected by the cable bedding size and an underground heating pipeline. Thanks to an experimental apparatus, some useful data were collected for the validation of two different finite element method based models that predict the effect of the pavement surface radiation properties on the cable ampacity. The first model corresponds to the experimental apparatus and actual indoor conditions, while the second one corresponds to the theoretical case and assumed outdoor conditions (taking into account the thermal effects of solar radiation, cable bedding size, and heating pipeline). This paper examines two possible cases of outdoor conditions, one corresponding to summer period (the most unfavorable ambient conditions) and another one corresponding to winter period (the most common winter conditions in Serbia). This proposed new method is based on the experimental data and generalized using the finite element method in COMSOL. It is found that the ampacity of the considered 110 kV cable line can be increased up to 25.4 % for the most unfavorable ambient conditions and up to 8 % for the most common winter conditions. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. TR33046