A K3 surface related to Leonardo Pisano's work on congruent numbers

This note recalls an early 13th century result on congruent numbers by Leonardo Pisano (“Fibonacci”), and shows how it relates to a specific much studied K3 surface and to an elliptic fibration on this surface. As an aside, the discussion reveals how, via explicit maps of degree two, the surface is covered by the Fermat quartic surface and also covers one of the two famous ‘most algebraic K3 surfaces’.</p

Techno-economic analysis of gas turbine-based chp plant operation under a feed-in tariff system

This paper deals with the techno-economic analysis of gas turbine-based combined heat and power production, within a current local legislation frame for the promotion of such production of energy in the Republic of Serbia. Since the legislation includes plants with electric power below 10 MW, an overview of the relevant technical characteristics for a number of appropriate gas turbines was prepared. The relevant thermodynamic parameters are calculated in order to estimate the economic feasibility of combined heat and power production using these plants. The production cost of useful heat is determined by taking into account the incomes from the sale of electricity to the electric grid under a feed-in tariff. It is compared with the production cost from an equivalent boiler for the separate production of the heat. One of the main objectives is to determine the effectiveness of the implemented legislative measures in the promotion of combined production of heat and power. Clear conclusions were drawn based on the results obtained

Techno-economic analysis of gas turbine-based chp plant operation under a feed-in tariff system

This paper deals with the techno-economic analysis of gas turbine-based combined heat and power production, within a current local legislation frame for the promotion of such production of energy in the Republic of Serbia. Since the legislation includes plants with electric power below 10 MW, an overview of the relevant technical characteristics for a number of appropriate gas turbines was prepared. The relevant thermodynamic parameters are calculated in order to estimate the economic feasibility of combined heat and power production using these plants. The production cost of useful heat is determined by taking into account the incomes from the sale of electricity to the electric grid under a feed-in tariff. It is compared with the production cost from an equivalent boiler for the separate production of the heat. One of the main objectives is to determine the effectiveness of the implemented legislative measures in the promotion of combined production of heat and power. Clear conclusions were drawn based on the results obtained

Analysis of operation of the condenser in a 120 mw thermal power plant

The condenser plant has a huge impact on the economy of a steam turbine power plant. Deterioration of the parameters during operation could lead to a significant decrease in electrical output and to an increase in the heat rate of the thermal power plant. Detailed calculations of the performance under different operating conditions were carried out for the condenser of the Morava thermal power plant. Comprehensive testing of the condenser was carried out and experimental data were compared with the numerical results. The effects of deviations in the condenser behavior on the main thermodynamic parameters and the overall economics of the power plant were evaluated. Guidelines for operation of condensation plants are given in the conclusion

Chirurgische eingriffe am parodontalen Geweben in red Retromolaren region

U radu je prikazana hirurška terapija dubokih gingivalnih džepova u retromolarnom regionu, kao i džepova onih zuba, koji se nalaze neposredno do bezubih viličnih regiona. Ovaj hirurški zahvat, izveden je na 23 bolesnika. Diskutovano je o prednostima i nedostacima ove metode.Surgical treatment of deep retromolar pockets and pockets next to edentulous ridges has been described in this paper. This kind of periodontal surgery was carried out on 23 patients, having such problems. The advantages and disadvantages of this type of treatment have been discussed.In dieser Arbeit wurde das chirurgische Heilen der tiefen Zahnfleischtaschen in den retromolaren Regionen, und von Taschen an Zähnen gegenüber den zahnlosen Kieferegionen vorgenommen. Diese Art der chirurgischen Eingriffe wurde an über 23 Kranken durchgeführit. Über Vorteile so auch Nachteile diese Methode wird diskutiert

Uticaj sorte i agroekoloških uslova na komponente prinosa krompira

The research on the effect of ecological conditions and cultivars on the yield components of potatoes was conducted in Badovinci (Western Serbia) during the period 2008-2009. The following potato cultivars were included in the experiment: early ('Cleopatra', 'Anushka' and 'Presto'), medium early ('Kuroda', 'Omega' and 'Dita'), and medium late ('Desiree', 'Roko' and 'Jelly'). The four-replicate field trials were set up using the standard methodology according to the random block design. 18TThe research results suggest that genotype (G) and ecological conditions (E) significantly affect all yield components of potatoes. In both years, the highest yield was recorded18T in18T the medium late variety 'Desiree'18T 18T(18T28.30 t ha־¹), followed by the early variety 'Anushka' 18T(18T26.60 t ha־¹), 18Twhile the lowest18T 18Tyield18T was 18Trecorded18T 18Tin the medium early variety 'Omega' (18T13.35 t ha־¹). The 18Tresults obtained show that18T 18Tthe18T 18Thighest yields18T in Western Serbia were 18Trecorded in early varieties18T 18T('Cleopatra'18T, 'Anushka' 18Tand18T '18TPresto'18T) and 18Tmedium18T 18Tlate varieties18T 18T('18TDesiree'), which exhibited considerable18T resistance to high18T 18Tair temperatures18T and 18Tdrought stress18T.Komponente prinosa devet sorti krompira ispitivane su tokom 2008. i 2009. godine na lokaciji zapadne Srbije u selu Badovinci (75 m nadmorska visina, 44˚ 80' 05'N, 19˚ 35' 39'E). Za istraživanje korišćene su sledeće sorte krompira: rane (Cleopatra, Anushka i Presto), srednje rane (Kuroda, Omega i Dita) i srednje kasne (Desiree, Roko i Jelly). Sadnja je izvedena u prvoj dekadi aprila. Međuredno rastojanje bilo je 0,70 m a između biljaka u redu 0,30 m. Primenjena je standardna tehnologija gajenja krompira. Broj primarnih nadzemnih izdanaka određen je 65 dana posle sadnje krtola. Vađenje krompira izvršeno je početkom septembra kada je izvršeno i utvrđivanje broja krtola po biljci i ukupan prinos. 18TDobijeni rezultati ukazuju da su sorta (G) i agroekološki uslovi (E) značajno utiču na sve komponente prinosa krompira. U obe godine najveći ukupan prinos krtola zabeležen je kod srednje kasne sorte Desiree18T 18T(18T28,30 t ha־¹), zatim kod rane sorte Anushka 18T(18T26,60 t ha־¹), dok je najniži prinos krtola utvrđen kod srednje rane sorte 18TOmega (18T13,35 t ha־¹). Na osnovu rezultata dvogodišnjih istraživanja uticaja sorte i agroekoloških uslova na komponente prinosa u zapadnoj Srbiji, možemo izvesti sledeće zaključke: - Sorta i uslovi sredine pojedinačno i u interakciji značajno utiču na komponente prinosa18T; Za dobijanje visokih prinosa krtola u uslovima zapadne Srbije možemo preporučiti rane sorte (18TCleopatra, Anushka 18Ti18T P18Tresto18T), posebno u godinama sa malom količinom padavina, kao i srednje kasnu sortu 18T(18TDesiree), koja je pokazala dobru tolerantnost prema visokim temperaturama vazduha i suši

Numerical and Experimental Determination of Canard Controlled Missile Aerodynamic Coefficients in Subsonic Regime

This paper discusses the computational and experimental approach to the determination of aerodynamic coefficients of canard controlled missile with wrap around tail fin. The paper presents results of subsonic flow at Mach 0.4. Angle of attack of the missile is varied from −10 to +10 degrees with an increment of 2 degrees. Canard deflection in the pitch plane is also varied at 0, 10, and 15 degrees. The results of the simulation are compared with the experimental data obtained by the wind tunnel measurements. Measured results confirm applicability of Spalart Allmaras turbulence model with adapted computational mesh to the determination of aerodynamic coefficients for canard controlled missiles

Samoprijavljene alergije na lijekove kod kirurških bolesnika u Srbiji

History of drug allergy is of major concern during perioperative period. Medical records usually lack documents confirming the stated allergy. This study aimed to investigate the prevalence of self-reported drug allergies and their characteristics in adult Serbian surgical population, and to analyze their influence on drug prescription during perioperative period. The study enrolled patients scheduled for general surgery during a one-year period at a tertiary care hospital. They were questioned using a structured questionnaire about the existence of drug allergy and its nature. Medical records were examined after discharge to assess medical prescription during hospitalization. Of 1126 patients evaluated during the study period, 434 (38.5%) reported a total of 635 drug reactions. The most common allergy claim was to antibiotics (68%), nonsteroidal antiinflammatory drugs (16.4%) and iodine (3.9%). Women, urban residents and herbal drug consumers were more likely to state an allergy. The majority of reported reactions were cutaneous (72%) and respiratory (34%), while anaphylaxis was reported by 3.2% of patients. Only 38 (8.7%) patients had previously undergone any allergology testing. Retrospective chart review revealed that 26 (6%) patients were administered the drug to which they had reported allergic reaction in the past, with no adverse effects. Drug allergies are frequently self-reported in surgical population in Serbia, which is in contrast to a very low rate of explored and documented allergies. In order not to deny an effective treatment or postpone a surgery, health care practitioners should pay more attention to an accurate classification of adverse drug reactions.Podatak o alergiji na lijekove je od velikog značenja u perioperacijskom razdoblju, a medicinska dokumentacija obično ne sadrži dokumente koji potvrđuju prijavljenu alergiju. Cilj ovoga istraživanja bio je ispitati učestalost i značajke samoprijavljenih alergija na lijekove od strane odraslih kirurških bolesnika u Srbiji i analizirati utjecaj takvog anamnestičkog podatka na propisivanje lijekova u perioperacijskom razdoblju. Studija je obuhvatila bolesnike podvrgnute elektivnim kirurškim intervencijama iz područja opće kirurgije tijekom jednogodišnjeg razdoblja u tercijarnoj zdravstvenoj ustanovi. Oni su ispitivani primjenom strukturiranog upitnika o postojanju alergija i njihovoj naravi. Medicinska dokumentacija je pregledana nakon otpusta iz bolnice kako bi se ispitalo propisivanje lijekova tijekom hospitalizacije. Od 1126 bolesnika evaluiranih tijekom studije, 434 (38,5%) ih je prijavilo ukupno 635 reakcija na lijekove. Najčešće samoprijavljene alergijske reakcije su bile na antibiotike (68%), nesteroidne protuupalne lijekove (16,4%) i jodni kontrast (3,9%). Samoprijavljivanje alergija je bilo češće kod žena, stanovnika urbanih područja i korisnika biljnih lijekova. Većinu prijavljenih reakcija su činile kožne (72%) i respiracijske (34%), dok je anafilaksu prijavilo 3,2% bolesnika. Samo 38 (8,7%) bolesnika je nakon reakcije podvrgnuto nekom alergološkom testiranju. Pregled povijesti bolesti je pokazao da je 26 (6%) bolesnika tijekom hospitalizacije primilo lijek na koji su prijavili alergijsku reakciju u prošlosti, što nije bilo praćeno neželjenim učincima. Samoprijavljivanje alergija na lijekove je veoma često kod kirurških bolesnika u Srbiji, što je u suprotnosti s niskom stopom ispitanih i dokumentiranih alergija. Kako se bolesnicima ne bi uskratila učinkovita terapija ili odlagala operacija, zdravstveni radnici bi trebali više pozornosti posvetiti preciznoj klasifikaciji neželjenih reakcija na lijekove

Towards Numerical Architectural Order Identification: Expressing Capital Morphology by Using Dynamics of Its Parameters

Previous subject-related research, that describes stylistic peculiarities of artefacts by taking into account their morphometric/geometric characteristics, explicates the results (used to differentiate them in terms of style they belong to) mainly descriptively – by evaluating the obtained data visually. The narrower aim of this Paper is to explicate the mentioned characteristics numerically/quantitatively by transposing stylistic-wise parameters (descriptors of fractal and non-fractal nature), previously investigated by the actual authors, into the form of dynamics of their values namely explicators. Therefore, the main research questions of this study are both how to express artefact morphology by using dynamics of its parameters and, thus, how to numerically/quantitatively identify architectural style concrete artefact belongs to. To achieve that scientifically, a triplet of capital samples (as the most distinctive elements among artefacts), namely their digital 3D models, are employed per each fundamental classical architectural order (Doric, Ionic, and Corinthian). The subject of this Paper is to establish relevant morphometric/geometric indicators not only in the form of explicators mentioned above, but qualifiers too, enabling so: to numerically express capital morphology, namely to quantitatively estimate levels of intra-similarity of capitals assumed to belong to the same order, and inter-dissimilarity of those assumed to belong to different ones. Both types of the established indicators refer to capital contours which are positioned in mutually equidistant transverse section planes (defined per each chosen capital sample of each of the analysed orders). The wider research aim refers to both: (a) a possibility to numerically/quantitatively identify order a concrete fragment of capital/artefact belongs to in terms of recognising it computationally (as confidently as possible from the mathematical probability point of view), and (b) to perform morphology-wise capital/artefact segmentation. Presented innovative methodology brings up a more reliable possibility to identify architectural order “stylistically unknown capital” belongs to – by using a newly introduced indicator (in the form of dynamics) to express its morphology numerically/quantitatively. Future research will be dealt with software-wise automation of stylistic decoding steps (rough capital classification and order-belonging estimation)