Anisotropy analysis of turbulent swirl flow

U radu su primenjene dve vrste invarijantnih mapa kako bi se procenio stepen anizotropnosti turbulentnog vihornog strujanja. Korišćene su invarijantna mapa, koju su predložili Lamli i Njuman, kao i baricentrična mapa. Analizirane su razlike u vizuelnom predstavljanju stanja anizotropnosti i izvedene su matematičke osnove za obe mape. Analizom eksperimentalnih podataka je pokazano da postoji značajan uticaj vihora na anizotropnost turbulencije. Korišćenje mapa anizotropnosti pokazuje da su različite oblasti strujnog polja u vihornom strujanju okarakterisane različitim stanjima anizotropnosti.Anisotropy invariant map proposed by Lumley and Newman and barycentric map proposed by Banerjee et al. were used in order to estimate the degree of anisotropy in turbulent swirl flow. The differences in visual interpretations of anisotropy states in these two maps were analyzed and mathematical basis of these two maps was derived. Experimental data reveal that there is significant influence of swirl on the anisotropy of turbulence. Anisotropy invariant mapping shows that different flow regions of swirl flow are characterized by different anisotropy states

Anisotropy analysis of turbulent swirl flow

U radu su primenjene dve vrste invarijantnih mapa kako bi se procenio stepen anizotropnosti turbulentnog vihornog strujanja. Korišćene su invarijantna mapa, koju su predložili Lamli i Njuman, kao i baricentrična mapa. Analizirane su razlike u vizuelnom predstavljanju stanja anizotropnosti i izvedene su matematičke osnove za obe mape. Analizom eksperimentalnih podataka je pokazano da postoji značajan uticaj vihora na anizotropnost turbulencije. Korišćenje mapa anizotropnosti pokazuje da su različite oblasti strujnog polja u vihornom strujanju okarakterisane različitim stanjima anizotropnosti.Anisotropy invariant map proposed by Lumley and Newman and barycentric map proposed by Banerjee et al. were used in order to estimate the degree of anisotropy in turbulent swirl flow. The differences in visual interpretations of anisotropy states in these two maps were analyzed and mathematical basis of these two maps was derived. Experimental data reveal that there is significant influence of swirl on the anisotropy of turbulence. Anisotropy invariant mapping shows that different flow regions of swirl flow are characterized by different anisotropy states

Flow simulations in a small bulb turbine using two-equation turbulence models

U radu su urađene numeričke simulacije strujanja u maloj cevnoj turbini primenom softvera Ansys CFX. Simulacije su izvedene primenom tri različita modela turbulencije koji su bazirani na Rejnoldsovom osrednjavanju Navije-Stoksovih jednačina: k-ε , k-ω i SST. Za svaki od navedenih modela razmotreno je sedam različitih radnih režima turbine. Da bi se smanjilo korišćenje računarskih resursa izvedene su stacionarne simulacije strujanja. Za sve slučajeve dobijena je dobra numerička stabilnost i konvergencija rešenja. Radne krive turbine formirane su za svaki od izabranih modela turbulencije na osnovu rezultata izvedenih simulacija u različitim radnim režimima. Za optimalni radni režim turbine, u proizvoljno izabranom poprečnom preseku difuzora izračunati su profili brzina za svaki model turbulencije, kao i raspodela statičkog pritiska po konturama loptatica radnog kola turbine. Izvršeno je upoređivanje dobijenih performansi turbine i data je analiza dobijenih profila brzine i raspodele statičkog pritiska za izabrane modele turbulencije.Numerical flow simulations in a small bulb turbine by the use of Ansys CFX software were performed in this paper. Simulations were performed for three different RANS-based models: k-ε , k-ω and SST. For each of these models, seven different operating regimes were considered. In order to reduce computational effort, steady state simulations were performed. In all cases, good numerical stability and convergence of solution were obtained. Based on the obtained results, performance curves for each of selected turbulence models in different operating regimes are formed. In turbine's optimal operating regime, velocity profiles in a selected cross section of the draft tube were calculated, as well as the static pressure distribution on runner blades. Comparison of obtained performance curves was performed. Analysis of the velocity profiles and distribution of static pressure are given for each of the selected turbulence model

Flow simulations in a small bulb turbine using two-equation turbulence models

U radu su urađene numeričke simulacije strujanja u maloj cevnoj turbini primenom softvera Ansys CFX. Simulacije su izvedene primenom tri različita modela turbulencije koji su bazirani na Rejnoldsovom osrednjavanju Navije-Stoksovih jednačina: k-ε , k-ω i SST. Za svaki od navedenih modela razmotreno je sedam različitih radnih režima turbine. Da bi se smanjilo korišćenje računarskih resursa izvedene su stacionarne simulacije strujanja. Za sve slučajeve dobijena je dobra numerička stabilnost i konvergencija rešenja. Radne krive turbine formirane su za svaki od izabranih modela turbulencije na osnovu rezultata izvedenih simulacija u različitim radnim režimima. Za optimalni radni režim turbine, u proizvoljno izabranom poprečnom preseku difuzora izračunati su profili brzina za svaki model turbulencije, kao i raspodela statičkog pritiska po konturama loptatica radnog kola turbine. Izvršeno je upoređivanje dobijenih performansi turbine i data je analiza dobijenih profila brzine i raspodele statičkog pritiska za izabrane modele turbulencije.Numerical flow simulations in a small bulb turbine by the use of Ansys CFX software were performed in this paper. Simulations were performed for three different RANS-based models: k-ε , k-ω and SST. For each of these models, seven different operating regimes were considered. In order to reduce computational effort, steady state simulations were performed. In all cases, good numerical stability and convergence of solution were obtained. Based on the obtained results, performance curves for each of selected turbulence models in different operating regimes are formed. In turbine's optimal operating regime, velocity profiles in a selected cross section of the draft tube were calculated, as well as the static pressure distribution on runner blades. Comparison of obtained performance curves was performed. Analysis of the velocity profiles and distribution of static pressure are given for each of the selected turbulence model

The radiological risk assesment methodology applied on sands from public beaches

The radiological risk of public exposure to terrestrial radiation in the sand beaches is assessed through the total absorbed gamma dose rate in air and annual effective dose outdoors determination according to international recommendations. Corresponding hazards due to sand use as a building material has been estimated by gamma irradiation hazard indices, based on the data of natural radionuclides contents in sands from public seaside and riverbank beaches (Ulcinj, Belgrade- Danube) obtained in this study, using spectrometry of gamma radiation.Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

Infectivity of Trichinella spiralis larvae in pork buried in the ground

Time of survival and infectivity of Trichinella spiralis larvae in pig muscle tissue, buried at various depths in the ground were assessed. In the pork pieces the number of infective larvae was 250 ML/g. Meat originated from pig halves was divided in 39 equal pieces, 0.7 kg each, disposed in three groups of 13, and buried in depths of 30, 50, and 100 centimeters respectively. The pork was dug up at 13 intervals, approximately every week, until 91(st) day of the experiment. After each time interval, infectivity of larvae was assessed by bioassay on rats. The artificially infected rats were sacrificed on 42(nd) day after the infection and meat was examined by the following methods - artificial digestion and trichinoscopy. It was found that the larvae during all 90 days preserved infectivity in each depth

Polyphenols as Possible Agents for Pancreatic Diseases

Pancreatic cancer (PC) is very aggressive and it is estimated that it kills nearly 50% of patients within the first six months. The lack of symptoms specific to this disease prevents early diagnosis and treatment. Today, gemcitabine alone or in combination with other cytostatic agents such as cisplatin (Cis), 5-fluorouracil (5-FU), irinotecan, capecitabine, or oxaliplatin (Oxa) is used in conventional therapy. Outgoing literature provides data on the use of polyphenols, biologically active compounds, in the treatment of pancreatic cancer and the prevention of acute pancreatitis. Therefore, the first part of this review gives a brief overview of the state of pancreatic disease as well as the procedures for its treatment. The second part provides a detailed overview of the research regarding the anticancer effects of both pure polyphenols and their plant extracts. The results regarding the antiproliferative, antimetastatic, as well as inhibitory effects of polyphenols against PC cell lines as well as the prevention of acute pancreatitis are presented in detail. Finally, particular emphasis is given to the polyphenolic profiles of apples, berries, cherries, sour cherries, and grapes, given the fact that these fruits are rich in polyphenols and anthocyanins. Polyphenolic profiles, the content of individual polyphenols, and their relationships are discussed. Based on this, significant data can be obtained regarding the amount of fruit that should be consumed daily to achieve a therapeutic effect

Educational value of the history of science content

Osamdesetih godina prošlog veka američki naučni odbor je istakao neraskidivost veze između razvoja nauke i razvoja tehnologije. S obzirom na tehnološki napredak društva u kojem živimo, učenici se u školama moraju osposobljavati za razumevanje tehnoloških inovacija i njihovog uticaja na kvalitet života, kao i za kritičko procenjivanje društvenih pitanja koja obuhvataju posledice razvoja tehnologije [1]. Da bi razumeli nauku i tehnologiju savremenog i budućeg doba, učenici treba da razumeju razvoj nauke i tehnologije u prošlosti. Na primer, kroz odgovarajuće epizode iz istorije prirodnih nauka, učenici mogu sagledati kako tehnologija traži odgovore nauke da bi se razvijala ili, kako se razvijala sposobnost čoveka da uoči problem koji je značajan za istraživanje i čije rešavanje doprinosi razvoju nauke, a samim tim i tehnologije. U ovom radu se govori o potencijalima sadržaja istorije prirodnih nauka za obrazovanje i vaspitanje učenika. Razmatra se uticaj sadržaja iz istorije prirodnih nauka na razumevanje pojmova iz savremenih prirodnih nauka, kao i uticaj na razvoj psiho-fizičkih sposobnosti i formiranje pogleda na svet kod učenika.In the eighties American Scientific Committee noted the connection between the development of science and technology. Because of the technological advancement of modern society, students in schools must be trained to understand the technological innovations and their impact on quality of life, as well as a critical evaluation of the social issues that include the effects of technology development [1]. To understand the science and technology of modern and future times, students need to understand the development of science and technology in the past. For example, through appropriate episodes from the history of science, students can see the relation between technology and science, and their influence on the ability of man to detect a problem that is significant for the study. The impact of the history of science content on student understanding of the concepts of modern science, and development of their skills and view of the world are examined in this paper.Prvi naučni simpozijum sa međunarodnim učešće

Functionalization of academic content concerning carboxylic acids

Istraživanja [1, 2, 3, 4] su pokazala da se učenici srednjih škola suočavaju s problemima u učenju gradiva organske hemije, posebno s primenom ovih znanja u različitim kontekstima. Jedan od osnovnih uzroka je sama koncepcija nastave organske hemije, koja se prvenstveno svodi na izlaganje akademskih znanja u gotovom vidu [2, 3]. U situacijama kada se učenicima prenosi obimno i kompleksno gradivo, najčešće motivacija za učenje nije velika. Akademska znanja iz organske hemije nisu od velikog značaja učenicima, ukoliko oni ne uviđaju kako mogu da ih iskoriste za unapređivanje kvaliteta svakodnevnog života i pripremu za bavljenje budućom profesijom [1, 3, 4]. Da bismo utvrdili da li izlaganje gradiva organske hemije u kontekstu svakodnevnog života i različitih profesija može da doprinese poboljšanju učeničkih postignuća i funkcionalizaciji stečenih znanja, sproveli smo pedagoški eksperiment sa paralelnim grupama, sa učenicima trećeg razreda gimnazije prirodnomatematičkog smera, u kome je ovaj inovativni pristup nastavi iskorišćen za obradu nastavne teme Karboksilne kiseline i njihovi derivati. Utvrdili smo da primena ovog pristupa dovodi do statistički značajnog poboljšanja učeničkih postignuća i njihove sposobnosti za primenu stečenih znanja iz ove oblasti organske hemije u različitim životnim kontekstima.Research [1, 2, 3, 4] has indicated that high school students have problems related to the learning of organic chemistry content, particulary problems associated with the application of acquired knowledge in a variety of contexts. One of the main causes of this problem is the very conception of organic chemistry courses, which are primarely based on transmission of academic content [2, 3]. In situations where students are exposed to an extensive and complex teaching material, their motivation for learning usually isn’t high. Furthermore, academic content of organic chemistry is not relevant to students, if they are not aware of how they can use it to improve the quality of their everyday life, or whether mastery of this content is important for their future professions [1, 3, 4]. To determine whether teaching organic chemistry in the context of everyday life, different professions and historical context, can help to improve student achievement and functionalization of acquired knowledge, we have conducted a pedagogical experiment with parallel groups of third grade mathematics and science orientation gymnasium students. This innovative approach was used for teaching about carboxylic acids and their derivates. We found that the application of this approach leads to a statistically significant improvement in student achievement and their ability to apply the acquired organic chemistry knowledge in a variety of contexts.Prvi naučni simpozijum sa međunarodnim učešće

Fenotyp typu „talia hipertriglicerydemiczna“ i zespół metaboliczny określany na podstawie różnych kryteriów oraz zależności między tymi zaburzeniami a kontrolą stężeń lipidów i glikemii u chorych na cukrzycę typu 2

Background: Metabolic syndrome (MetS) describes clustering of obesity, dyslipidemia, hyperglycemia and hypertension and increases risk for cardiovascular disease and type 2 diabetes. The ‘hypertriglyceridemic waist’ phenotype (HTGW) represents a simple approach to identifying individuals with increased risk. The aim of the study was to determine the prevalence of HTGW and MetS in type 2 diabetic patients, and to examine their relation to lipids and blood glucose control. Material and methods: 300 type 2 diabetic patients were analysed, and their history of diabetes, anthropometric measures, measurements of blood pressure (BP), lipids and glycemic control parameters were taken. Results: In type 2 diabetic patients, the prevalence of MetS was 71.0% by the AHA/NHLBI definition and 75.33% by the IDF definition. The prevalence was 62.58% and 66.45% in men, and 80% and 84.83% in women by the same definitions, respectively. There were 41.33% of patients with HTGW (42.76% among women and 40% among men). There were statistically significant differences of age, fasting plasma glucose (FPG) and postprandial glucose (PPG) in women with and without MetS according to both definitions, and of total and LDL cholesterol with and without MetS according to AHA/NHLBI (but not IDF). In men, there were statistically significant differences of total cholesterol and of HbA1c with and without MetS according to AHA/NHLBI (but not IDF). Women with HTGW had higher levels of total and LDL cholesterol, systolic and diastolic BP. Men with HTGW had higher levels of total cholesterol, diastolic BP, HbA1c, FPG and PPG. Conclusions: Determining MetS or HTGW helps identify those with increased cardiovascular risk. (Pol J Endocrinol 2011; 62 (4): 316–323)Wstęp: Zespół metaboliczny (MetS) obejmujący otyłość, dyslipidemię, hiperglikemię i nadciśnienie tętnicze zwiększa ryzyko chorób sercowo-naczyniowych i cukrzycy typu 2. Określanie fenotypu „talii hipertriglicemicznej” (HTGW) jest prostą metodą identyfikowania chorych z grupy wysokiego ryzyka. Celem badania było ustalenie częstości HTGW i MetS u chorych na cukrzycę typu 2 oraz ocena zależności miedzy tymi zaburzeniami a kontrolą stężeń lipidów i glikemii. Materiał i metody: Do badania włączono 300 chorych na cukrzycę typu 2 i przeanalizowano dane dotyczące przebiegu cukrzycy, parametrów antropometrycznych, wartości ciśnienia tętniczego, stężeń lipidów i kontroli glikemii. Wyniki: U chorych na cukrzycę typu 2 kryteria MetS według definicji AHA/NHLBI spełniało71,0%, a kryteria IDF — 75,33%; odsetek chorych z MetS wynosił wśród mężczyzn odpowiednio 62,58% i 66,45%, a wśród kobiet 80% i 84,83%. U 41,33% chorych stwierdzono cechy HTGW, 42,76% tej grupy stanowiły kobiety, a 40% mężczyźni. U kobiet wykazano istotne statystycznie różnice w zakresie wieku, glikemii na czczo (FPG) i glikemii poposiłkowej (PPG) między grupami z MetS i bez niego, rozpoznanym na podstawie obu definicji, natomiast w zakresie stężenia cholesterolu całkowitego i frakcji LDL różniły się one tylko między grupami z MetS i bez niego wydzielonymi na podstawie definicji AHA/NHLBI (a nie na podstawie kryteriów IDF). U mężczyzn wykazano statystycznie istotne różnice stężeń cholesterolu całkowitego HbA1c między grupami z MetS i bez niego określonym według AHA/NHLBI (ale nie według IDF). U kobiet z HTGW stwierdzono wyższe stężenia cholesterolu całkowitego i cholesterolu frakcji LDL oraz wyższe wartości ciśnienia skurczowego i rozkurczowego. U mężczyzn z HTGW odnotowano wyższe wartości stężeń cholesterolu całkowitego, rozkurczowego ciśnienia tętniczego, HbA1c, FPG i PPG. Wnioski: Rozpoznanie MetS lub HTGW pozwala zidentyfikować osoby obciążone zwiększonym ryzykiem sercowo-naczyniowym. (Endokrynol Pol 2011; 62 (4): 316–323