An oil pipeline design problem

Copyright @ 2003 INFORMSWe consider a given set of offshore platforms and onshore wells producing known (or estimated) amounts of oil to be connected to a port. Connections may take place directly between platforms, well sites, and the port, or may go through connection points at given locations. The configuration of the network and sizes of pipes used must be chosen to minimize construction costs. This problem is expressed as a mixed-integer program, and solved both heuristically by Tabu Search and Variable Neighborhood Search methods and exactly by a branch-and-bound method. Two new types of valid inequalities are introduced. Tests are made with data from the South Gabon oil field and randomly generated problems.The work of the first author was supported by NSERC grant #OGP205041. The work of the second author was supported by FCAR (Fonds pour la Formation des Chercheurs et l’Aide à la Recherche) grant #95-ER-1048, and NSERC grant #GP0105574

Analysis of the prevalence of eating disorders in the student population

broju. Cilj Osnovni cilj ovog istraživanja bio je ispitivanje prevalencije poremećaja ishrane u studentskoj populaciji, dok su specifični ciljevi uključili određivanje prevalencije po dijagnostičkim kategorijama; određivanje obrasca ishrane i percepcije telesne šeme; prisustva kompenzatornih oblika ponašanja i depresivne simptomatologije. Metod rada Studija obuhvata analizu uzorka od 1.059 slučajno odabranih studenata različitih viših škola i fakulteta Univerziteta u Beogradu, Srbija, koji su prilikom redovnih godišnjih sistematskih pregleda u Zavodu za zdravstvenu zaštitu, popunili bateriju anonimnih upitnika: socio-demografski upitnik, upitnik anamnestičkih podataka, dijagnostičku skalu poremećaja ishrane i Bekov upitnik za procenu stepena depresivnosti. Rezultati Prevalencija poremećaja ishrane bila je 29,0%. Prevalencija anoreksije nervoze u ukupnom uzorku studenata je bila 1,9%, a samo među ženskim polom 3,2%. Prevalencija bulimije nervoze je bila 13,5%, a poremećaja ishrane po tipu prejedanja 14,4%. Studenti sa detektovanim poremećajem ishrane tipa anoreksije i bulimije nervoze su ispoljili više depresivnih simptoma u poređenju sa studentima, kod kojih ovi poremećaji nisu detektovani. Prevalencija depresije u ukupnom uzorku studenata bila je viša od prevalencije poremećaja ishrane (31% vs. 29%). Zaključak Primena rezultata ovog istraživanja trebalo bi da nađe svoje mesto u integrisanim multidisciplinarnim preventivnim programima, u svakodnevnoj rutinskoj praksi primarne zdravstvene zaštite, savetovalištima za adolescente i mlade, savetovalištima za ishranu, kao i na specijalizovanim odeljenjima bolesti poremećaja ishrane.a greater number each day. Aim The aim of the research was to determine the prevalence of eating disorders in the student population and the prevalence according to diagnostic categories; to determine eating habits, body perception, compensatory behaviors and depressive symptoms. Method The study includes analysis of a sample of 1.059 randomly selected students from various colleges and faculties of Belgrade University, Serbia, who in the regular annual health examination at the Institute for Health Care Belgrade, have fulfilled the anonymous questionnaires: Social-demographic questionnaire, Anamnesis questionnaire, Eating Disorder Examination Questionnaire and Beck Depression Inventory. Results The prevalence of eating disorders was 29.0%. The prevalence of anorexia nervosa in the total sample was 1.9%, and only among female students 3.2%. The prevalence of bulimia nervosa was 13.5%, and binge eating disorder 14.4%. Students with detected anorexia nervosa and bulimia nervosa are exhibiting more depressive symptoms when compared with students in which these disorders are not detected. The prevalence of depression in the total sample was higher than the prevalence of eating disorders (31% vs. 29%). Conclusion Application of the results of this research should find its place in integrated, multidisciplinary prevention programs, in the everyday routine practice of primary health care, in counseling for adolescents and young people, counseling for nutrition, as well as at the specialized departments of eating disorders

Snabdevenost važnijih tipova zemljišta Srbije osnovnim alkalnim elementima Ca, Mg, K i Na

In this paper results are presented of agrochemical and mineralogical analyses of 14 types of important soils in Serbia (Vojvodina and Central Serbia) and total content and availability of base alkali elements (Ca, Mg Na, K) are determined. Total element content was as follows: Ca 2.22%; K 1.77%; Na 0.85% and Mg 0.61%. Total content of alkali metals in the soils investigated and their variations within and between the soil types, is in very good/close correlation with contents of primary and secondary minerals as well as their rates of weathering. Taking in account the average availabilities the most abundant is calcium with 947 mg/100 g, whilst the averages of the other elements (Mg, K and Na) are quite similar and are about of 40 mg/100 g of soil. The results obtained have shown that the soils investigated are well to moderate provided with K, Ca and Mg and that their deficit could not be expected in plant nutrition, apart for some plants/cultures in the case of magnesium due to occasionally higher Ca/Mg and K/Mg ratios.U ovom radu je ispitivano 100 reprezentativnih uzoraka 14 tipova zemljišta Srbije (Vojvodina, Šumadija i Severno Pomoravlje) u pogledu ukupnog i pristupačnog sadržaja osnovnih alkalnih metala (Ca, Mg, K i Na). Takođe je prikazan i prosečan mineraloški sastav ispitivanih zemljišta. Nađeni su sledeći srednji ukupni sadržaji ispitivanih elemenata: Ca - 2,25%; K - 1,77% Na - 0,85% i Mg - 0,61%. Ukupni sadržaji ispitivanih alkalnih metala u našim zemljištima i njihova vapipanja između i unutar zemljišnih tipova u uskoj su vezi sa zastupljenošću određenih primarnih i sekundarnih minerala i njihovom otpornošću na raspadanje. Prema srednjim vrednostima za pristupačne sadržaje najviše ima kalcijuma (947 mg/100 g), a srednji sadržaji za ostale baze (Mg K i Na) su vrlo slični i kreću ce oko 40 mg/100 g. Dobijeni rezultati pokazuju da su ispitivana zemljišta dobro i srednje obezbeđena K, Ca i Mg i da se ne mogu očekivati njihovi deficiti za ishranu biljaka, osim za neke kulture u slučaju magnezijuma, zbog ponekad suviše povišenih odnosa Ca/Mg i K/Mg

Correlation of biological markers with response to preoperative radiotherapy in locally advanced noninflamatory breast cancer

terapiji lokalno odmaklog karcinoma dojke (LOKD) preoperativna radioterapija (PRT) je u današnje vreme indikovana nakon primarne (neoadjuvantne) hemioterapije (PHT) u slučaju da nije postignuta resektabilnost tumora. Pre uvodjenja neoadjuvantne hemioterapije, PRT se mnogo češće koristila kao jedini neoadjuvantni pristup za inicijalno inoperabilne tumore, u cilju smanjenja tumorskog volumena i omogućavanja radikalne hirurgije. Cilj ove analize je evaluacija tumorskog odgovora i dugoročnog ishoda bolesti kod pacijenata tretiranih samo PRT, bez uticaja sistemske terapije, i procena povezanosti bioloških markera sa odgovorom na PRT. Metod: U periodu od 1997-2000.godine 134 bolesnica sa neinflamatornim LOKD stadijuma IIIA i IIIB tretirano je preoperativnom RT. Tumorska doza je bila 45 Gy u 15 frakcija (3 Gy po frakciji) naizmenično svakog drugog dana na regiju dojke i regionalnih limfatika u toku 6 nedelja. Šest nedelja po završenoj RT, učinjena je radikalna mastektomija kod svih bolesnica i potom primenjena adjuvantna terapija (hemioterapija i/ili hormonska terapija) po tadašnjem protokolu. Ishod bolesti je procenjivan na osnovu ukupnog preživljavanja (OS) i preživljavanja bez znakova bolesti (DFS). Krive preživljavanja (OS i DFS) su procenjivane korišćenjem Kaplan-Meier metode i univarijantne statističke analize korišćenjem Log-Rank testa u cilju procene razlike izmedju analiziranih grupa. Status hormonskih receptora ER i PgR, HER-2 status i Ki-67 su analizirani imunohistohemijskim metodama na uzorku biopsiranog tumora i uzorku na mastektomiji. Merenje genske ekspresije vršeno je iz parafinskih uzoraka tumorskog tkiva Microarray analizom. Rezultati: Medijana praćenja iznosila je 74 meseca (ranga 4-216). Klinički odgovor tumora na PRT zabeležen je kod 77.6% bolesnica. Klinički kompletan odgovor tumora (cCR) postignut je kod 21.6% bolesnica, dok je patohistološki kompletan odgovor (pCR) u dojci registrovan kod 15% bolesnica. Od toga 10/134 (7.5%) je ostvario totalni pCR (bez invazivnog tumora u dojci i bez pozitivnih limfnih čvorova u aksili). Petogodišnje i l0-godišnje OS je bilo 55.1% i 37.8%, dok je 5-godišnje i 10-godišnje DFS bilo 39.2% i 27%. Bolesnice koje su postigle cCR su imale statistički duže OS u poredjenju sa onima sa cPR i cSD (Log-Rank test, p=0.038). Slično je i DFS bolesnica sa cCR bilo duže u odnosu na cPR i cSD, mada razlika nije bila statistčki značajna. Analizom bioloških markera pokazano je da pacijenti sa luminal A tumorima imaju bolje preživljavanje u odnosu na ostale podtipove, dok trostruko negativni tumori imaju najbolji odgovor na PRT (40% pCR i pNCR). Analiza genske ekspresije primarnog tumora je pokazala da su tri gena (APOA1, MAP3K4 i MMPM) značajno različito eksprimirana izmedju RT-rezistentnih i RT-responzivnih tumora. Zaključak: Naši rezultai su pokazali da lokalna kontrola pacijenata sa LOKD tretiranih preoperativnom RT i radikalnom mastektomijom je komparabilna sa rezultatima prikazanim u literaturi. Kompletan patohistološki odgovor (pCR) na PRT izdvaja grupu bolesnica koje naginju ka boljem OS i DFS.In the treatment of locally advanced breast cancer (LABC) preoperative radiotherapy (PRT) today is indicated after primary (neoadjuvant) chemotherapy (PCT) if resectability of tumor was not achieved. Before the introduction of PCT in treatment strategy, PRT was more frequently used as the sole neoadjuvant approach for initially inoperable tumors, in order to reduce tumor volume and reach radical surgery. The purpose of this analysis was to evaluate the tumor response and long-term outcome at patients treated with only PRT, without influence of systemic therapy, and to assess the relationship of biological markers with response to PRT. Method: Between 1997 and 2000, 134 patients with non-inflammatory LABC stage IIIA and IIIB were treated with PRT. The tumor dose was 45 Gy in 15 fractions (3 Gy per fraction) every second day to the breast and to regional lymph nodes over 6 weeks. Radical mastectomy was performed 6 weeks after PRT to all patients and adjuvant systemic therapy was administered as per protocol. The measure of disease outcome were overall survival (OS) and disease-free survival (DFS). Survival and DFS curves were estimated using the Kaplan-Meier method and univariate statistical analysis by Log rank test was used to assess the difference in time to event (OS/DFS) between the analyzed groups. The hormone receptor status of ER and PgR, HER-2 status and Ki-67 were assessed by immunohistochemistry on the biopsy and mastectomy specimens. Gene expression profiles were established using micro-array analysis in a formalin-fixed paraffin-embedded (FFPE) tumor samples. Results: Median follow-up was 74 months (range 4-216 months). An objective clinical tumor response after preoperative RT was observed in 77.6% of patients. Clinical complete tumor response (cCR) was achieved in 21.6% of patients. Pathological CR in the breast was achieved in 15% of patients. Among them 10/134 (7.5%) had total pCR (no invasive tumor in breast associated with no involved regional axillary lymph nodes. The 5 and 10-year OS were 55.1% and 37.8% respectively. The 5 and 10-year DFS were 39.2% and 27% respectively. Patients who achieved cCR had significantly longer OS in comparison with patients achieving cPR and cSD. Similarly, DFS of patients in cCR group was longer compered to patients with cPR and cSD, although it did not reach statistical significance. Analysis of biological markers has shown that patients with luminal A tumors had better OS than other subtypes, but triple-negative breast cancers (TNBC) had the best response to PRT (40% of pCR and pNCR). Gene expression analysis of primary tumor has shown that three genes (APOA1, MAP3K4 and MMPM) were significantly differentially expressed between RT-resistant and RT-responsive tumors. Conclusion: Our results showed that local control in LABC patients achieved by primary PRT, followed by radical mastectomy was comparable with the results reported in literature. Complete pathologic response to PRT identified a subgroup of patents with a trend toward better DFS and OS

Effects of quercetin and epicatechin on oxidativeantioxidative status of rats treated with copper(ii)- ions

Bakar kao esencijalni mikroelement ima važnu ulogu u biološkim sistemima međutim, povećane koncentracije mogu da izazovu toksične efekte. Kao prelazni metal, bakar može da stimuliše produkciju reaktivnih vrsta kiseonika preko Fenton-ove i Haber-Weiss-ove reakcije i dovede do oksidativnih oštećenja biomolekula u tkivima, pre svega u jetri koja učestvuje u njegovom metabolizmu. Flavonoidi su prirodna biljna polifenolna jedinjenja koja pokazuju širok spektar biološke aktivnosti. Antioksidativna svojstva mogu da ispolje različitim mehanizmima, u direktnoj reakciji sa reaktivnim vrstama ili helacijom jona prelaznih metala, koji bi u daljim reakcijama proizveli reaktivne vrste. Cilj istraživanja ove doktorske disertacije je ispitivanje efekata subhronične intoksikacije bakrom na hematološko-biohemijske parametre u krvi, oksidativni metabolizam eritrocita i parametre oksidativnog stresa u jetri pacova. Takođe, cilj je i ispitivanje protektivnog kapaciteta i sinergističkog delovanja flavonoida kvercetina (QE) i epikatehina (EC), kao čistih supstanci, u uslovima oksidativnog stresa. Upoređivani su i efekti primenjenih flavonoida i komercijalnog leka D-penicilamina (DPA), tiolnog jedinjenja koje se koristi za tretman oboljenja čiji je uzrok povećano akumuliranje bakra u tkivima (Vilsonova bolest). Studija je izvedena na mužjacima pacova soja Wistar albino, 8 nedelja starosti na početku eksperimenta, nasumično podeljenih u 5 grupa po 7 životinja: (1) kontrolna (0.3 ml fiziološkog rastvora, i.p.); (2) tretirana bakrom (CuCl2·2H2O u koncentraciji od 560 mg/L) preko vode za piće u trajanju od 5 nedelja; (3) tretirana bakrom (na način opisan prethodno) i DPA (50 mg/kg TT, u 0.3 ml redestilovane vode, i.p.) svakog drugog dana tokom poslednje 2 nedelje eksperimenta (ukupno 5 injekcija); (4) tretirana bakrom (na način opisan prethodno), a zatim flavonoidima QE i EC (40 mg QE/kg TT + 40 mg EC/kg TT, u 0.3 ml redestilovane vode, i.p.) svakog trećeg dana tokom poslednje 3 nedelje eksperimenta (ukupno 7 injekcija); (5) tretirana flavonoidima QE i EC (na način opisan prethodno). U punoj krvi određivani su hematološki parametri: broj eritrocita (RBC), koncentracija hemoglobina (Hb), hematokrit (Hct), broj leukocita (WBC), broj trombocita (Plt), hematološki indeksi, i biohemijski parametri: koncentracije elektrolita (K, Na, Ca, Fe, fosfata), koncentracije ukupnih proteina, albumina, glukoze i ukupnog holesterola, aktivnosti enzima aspartat aminotransferaze (AST), alanin aminotransferaze (ALT), alkalne fosfataze (ALP), gama-glutamil transpeptidaze (GGT) i laktat dehidrogenaze (LDH). U lizatu eritrocita, primenom standardnih analitičkih metoda, određivani su markeri oksidativnog stresa: koncentracije lipidnih peroksida (LPO), koncentracije reaktivnih vrsta kiseonika i azota (superoksid anjon radikala (O2 •-), vodonik peroksida (H2O2) i nitrita (NO2 -)), koncentracije redukovanog (GSH) i oksidovanog glutationa (GSSG) i aktivnosti enzima superoksid-dismuze (SOD), katalaze (CAT), glutation- peroksidaze (GSH-Px), glutation-reduktaze (GR), glutation-S-transferaze (GST). U izolovanom tkivu jetre, nakon homogenizacije, primenom standardnih analitičkih metoda takođe je određen redoks status (koncentracije LPO, neenzimskih antioksidanata GSH, GSSG i Vit C, i aktivnosti enzima AOS: ukupne SOD, CuZn SOD, Mn SOD, CAT, GSH-Px, GR i GST). Koncentracije bakra i ceruloplazmina određene su u plazmi i supernatantu tkiva jetre. Rezultati istraživanja pokazuju da bakar u subhroničnom tretmanu ispoljava direktan prooksidativni efekat na eritrocite i tkivo jetre pacova i pokazuje značajne toksične efekte na hematološko-biohemijske procese u krvi. Subhronična intoksikacija bakrom dovodi do povećanja LPO u eritrocitima i tkivu jetre, uzrokuje hemolizu eritrocita i anemiju, porast ukupnog holesterola, poremećaj homeostaze elektrolita. Nakon subhronične intoksikacije bakrom povišene su aktivnosti enzima AST, ALT, ALP, GGT i LDH, markera citotoksičnosti jetre u serumu. Oksidativnim oštećenjima eritrocita i tkiva jetre doprinosi povećana produkcija O2 •- i H2O2 i smanjenje neenzimskih antioksidanata, ćelijskog pula GSH i Vit C. Promene u aktivnostima enzima AOS posle subhronične intoksikacije bakrom takođe ukazuju na pojavu oksidativnog stresa u eritrocitima i tkivu jetre. Flavonoidi QE i EC pokazuju antioksidativnu sposobnost i umanjuju oksidativni stres nastao nakon subhroničnog izlaganja bakru. QE i EC stabilizuju membrane, blokiraju lipidnu peroksidaciju i time igraju ulogu u ublažavanju manifestacija toksičnosti u eritrocitima i tkivu jetre. Značajno povećavaju koncentracije neenzimskih antioksidanata GSH i Vit C u ćelijama, indukuju sintezu enzima AOS, čime doprinose povećanju antioksidativnog kapaciteta ćelija. Sinergističko delovanje flavonoida QE i EC, kao i citoprotektivna uloga koju pokazuju, može se pripisati njihovoj sposobnosti da heliraju metale i/ili uklanjaju O2 •- i N2O2. Rezultati takođe pokazuju da su QE i EC efektivniji u antioksidativnom delovanju u poređenju sa DPA, koji pored efikasnosti u heliranju metala ispoljava i prooksidativne efekte povećanjem lipidne peroksidacije u eritrocitima i tkivu jetre. Ovo istraživanje predstavlja doprinos kompletiranju naučnih saznanja o toksičnim efektima bakra, kao i kompleksnosti protektivnog delovanja flavonoida kvercetina i epikatehina na oksidativno-antioksidativni status eritrocita i ćelija tkiva jetre. Zbog širokog spektra biohemijskih i farmakoloških dejstava, posebno treba istaknuti značaj ispitivanih flavonoida u zdravoj ishrani, kao i u prevenciji i terapiji mnogih oboljenja.Copper is an essential trace element that plays an important role in biological systems, however, the increased concentration may cause toxic effects. As the transition metal, copper may stimulate the production of reactive oxygen species by Fenton's and Haber-Weiss reaction and lead to oxidative damage of biomolecules in the tissues, especially in the liver, which participates in its metabolism. Flavonoids are a natural plant polyphenol compounds which exhibit a wide spectrum of biological activity. They may exert antioxidant properties through different mechanisms, in a direct reaction with a reactive species,or by chelating transition metal ions, which in a further reaction may produce reactive species. The effects of subchronic copper intoxication on haematological and biochemical parameters in blood,oxidative metabolism of erythrocytes and oxidative stress parameters in rat liver are objectives of this dissertation research. The aim is also to examine the protective capacity and synergistic effects of flavonoids quercetin (QE) and epicatechin (EC), as a pure substances, under oxidative stress conditions. We also compared the effects of these flavonoids and a commercial drug D-penicillamine (DPA), a thiol compound used for the treatment of diseases caused by an increased accumulation of copper in the tissues (Wilson's disease). The study was performed on male albino Wistar rats, 8 weeks old at the beginning of the experiment,randomly divided into 5 groups of 7 animals: (1) control (0.3 ml of saline, i.p.); (2) copper-treated (CuCl2·2H2O at a concentration of 560 mg/L) through drinking water for 5 weeks; (3) treated with copper (as described previously), and DPA (50 mg/kg body weight in 0.3 ml of re-distilled water, i.p.) every other day during the last 2 week of the experiment (total number of injections were 5); (4) treated with copper (as described above), and flavonoids QE and EC (40 mg QE/kg body weight + 40 mg EC/kg body weight, in 0.3 ml of re-distilled water,i.p.) every third day during the last 3 weeks of the experiment (total number of injections were 7); and (5) treated with flavonoids QE and EC (as described previously). Hematological parameters: erythrocyte count (RBC),hemoglobin concentration (Hb), hematocrit (Hct), leukocyte count (WBC), platelet count (Plt), hematological indices, and biochemical parameters: concentration of electrolytes (K, Na, Ca, Fe, phosphate), total protein,albumin, glucose, and total cholesterol, the activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), gamma-glutamyl transpeptidase (GGT) and lactate dehydrogenase (LDH) were measured in the whole blood. Markers of oxidative stress: lipid peroxidation (LPO),the concentration of reactive oxygen and nitrogen species (superoxide anion radicals (O2 •-), hydrogen peroxide (H2O2) and nitrite (NO2 -)), reduced (GSH) and oxidized glutathione (GSSG) concentrations, and activities of AOS enzymes: superoxide-dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GR), and glutathione-S-transferase (GST) were determined in the erythrocyte lysate using standard analytical methods. In isolated liver tissue after homogenization, the redox status (LPO concentration, GSH, GSSG and Vit C concentration, and the activities of total SOD, CuZn SOD, Mn SOD, CAT, GSH-Px, GR, and GST) was also determined using standard analytical methods. The concentrations of copper and ceruloplasmin were determined in the plasma and in the liver tissue supernatant. The results show that copper in subchronic treatment exerts a direct pro-oxidative effect on erythrocytes and liver tissue of rats and significant toxic effects on haematological and biochemical processes in the blood. Subchronic intoxication with copper leads to an increase in LPO in liver tissue and in erythrocytes, causes haemolysis and anemia, increase in total cholesterol, electrolyte homeostasis disbalance. After subchronic copper intoxication activities of cytotoxicity liver markers AST, ALT, ALP, GGT, and LDH, in the serum were elevated. Increased production of O2 •- and H2O2 and the reduction of non-enzymatic antioxidants, GSH and Vit C, contribute to oxidative damage in red blood cells and liver tissue. Changes in the activities of the AOS enzymes after subchronic intoxication with copper also indicated the occurrence of oxidative stress in erythrocytes and liver tissue. Flavonoids QE and EC exhibit antioxidant capacity and reduce oxidative stress occurring after subchronic copper exposure. QE and EC stabilize the membrane, blocking the lipid peroxidation, and thereby play a role in mitigating the manifestation of toxicity in the erythrocytes and liver tissue. They significantly increase the concentration of non-enzymatic antioxidants GSH and Vit C in cells, induce synthesis of the AOS enzymes, thus contributing to increase the cells antioxidant capacity. The synergistic action of the flavonoids QE and EC, and a cytoprotective role which they exert, can be attributed to their ability to chelate metal ions and/or remove O2 •- and H2O2. The results also show that QE and EC were more effective in antioxidant activity when compared with the DPA, which in addition to the efficiency of chelating metal ions exerts prooxidant effects, by increasing lipid peroxidation in erythrocytes and liver tissue. This research is a contribution to the scientific knowledge of the toxic effects of copper, as well as the complexity of the protective effect of flavonoids quercetin and epicatechin in the oxidative-antioxidant status of red blood cells and liver tissue cells. Considering their wide range of biochemical and pharmacological effects, we should point out to the importance of the flavonoids in a healthy diet, as well as in the prevention and treatment of many diseases

Tool path optimization in sculptured surface milling

Развој обрадних система нове генерације и супер брзих персоналних рачунара је допринео све чешћој употреби машинских делова са скулпторским површинама у инжењерству. Развијени поступци обраде скулпторских површина лоптастим глодалом су били полазна основа за формирање аналитичких модела за анализу и оптимизацију пројектоване путање алата што представља и основни циљ истраживања у овој дисертацији. Анализом могућности комерцијалних CAD/CAM система са становишта обраде скулпторских површина глодањем су уочени недостаци истих чиме је указано на могући простор за побољшања и квалитетнија решења. Систематизованим прегледом параметарског описа различитих типова кривих и површина и одговарајућим диференцијалним рачуном над њима је створена основа за имплементацију истих у развијеном софтверском систему. Истраживањем је такође, обухваћена изградња различитих модела за оптимизацију процеса обраде скулпторских површина базираних на различитим критеријумима оптимизације као што су: максимална храпавост обрађене површине, силе резања и равномерност храпавости обрађене површине. Због непостојања података за усвојену комбинацију материјала и геометрије алата и метеријала припремка развијен је механистички модел за предикцију компонената силе глодања који је подразумевао експериментално одређивање скупа коефицијената резања. За овако развијене моделе у дисертацији је развијен off-line метод вишекритеријумске оптимизације путање алата на бази учитаних CAD модела изратка и припремка. Методи су имплементирани у оквиру софтверског решења које омогућује аутоматско/интерактивно пројектовање технологије обраде за НУМА која од корисника не захтева велико искуство у CNC технологији. Машинском обрадом делова на бази управљачких кодова добијених из развијене апликације показан је квалитет пројектованог система за процес off-line оптимизације путање алата. Метролошком анализом на НУММ је показано да је обрада извршена у оквиру дозвољеног одступања чиме је потврђена тачност генерисања тачака локације алата помоћу развијених метода.The development of new generation manufacturing systems and super fast personal computers contributed to an increased use of mechanical parts with sculptured surfaces in engineering. The methods developed so far for machining of sculptured surfaces with ball end mill were used as the basis for constructing analytical models for analysis and optimization of the projected tool path, which represents the main research goal of this thesis. The commercial CAD/CAM system analysis of machining capabilities of sculptural surfaces by milling provided more insight into its limitations, pointing towards possible areas for improvement and finding more appropriate solutions. Using a systematic exploration of parametric descriptions for different types of curves and surfaces, and applying appropriate differential calculations, the basis for their implementation was created in the developed software system. The research also included the construction of different models for machining optimization of sculptural surfaces, based on various optimization criteria such as: maximum surface roughness, cutting forces and uniformity of surface roughness. A mechanistic model for the prediction of cutting force components, which included experimental determination of a set of cutting coefficients, was developed due to the lack of existing data for the adopted combination of material and tool geometry, as well as the material of the workpiece. For these models, an off-line method was developed for multi-criteria tool path optimization based on the loaded CAD models of the machined part and the workpiece. These methods have been implemented in a software application which enables an automatic/interactive design of manufacturing technology for a numerical control machine which requires very little user experience in CNC technology. The quality and reliability of the developed system for off-line tool path optimization was demonstrated by machining parts using the control code generated by the developed software application. Metrological analysis using a coordinate-measuring machine was used to verify that the machining was performed within the specified tolerance, thereby confirming the accuracy of generating cutter tool path using the methods developed in this thesis

Analysis of causes of degradation of parent material and weld metal of breeches pipe at hydro power plant 'Perućica'

Presented are results of non-destructive tests performed on the parent material and welded joints of structural parts of a breeches pipe (collar and anchor), and results of destructive tests performed on the parent material of the anchor. Non-destructive testing included visual (VT), mag-netic particle (MT), and ultrasonic testing (UT), while destructive tests included determination of chemical com-position, tensile properties, impact energy and hardness. Based on test results it is established that the major cause for the occurrence of damage in the carrying structure of the breeches pipe no.1 of pipeline III, or in other words, the degradation of anchor parent material and welded joints between the collar and anchor, and between the pipeline and anchor, is in the fact that the breeches pipe started to lean, not on the collar, as specified by design, but on the anchor that could not endure all loads occurring in service

The availability of base elements (Ca, Mg, Na, K) in some important soil types in Serbia

In this paper results are presented of agrochemical and mineralogical analyses of 14 types of important soils in Serbia (Vojvodina and Central Serbia) and total content and availability of base alkali elements (Ca, Mg Na, K) are determined. Total element content was as follows: Ca 2.22%; K 1.77%; Na 0.85% and Mg 0.61%. Total content of alkali metals in the soils investigated and their variations within and between the soil types, is in very good/close correlation with contents of primary and secondary minerals as well as their rates of weathering. Taking in account the average availabilities the most abundant is calcium with 947 mg/100 g, whilst the averages of the other elements (Mg, K and Na) are quite similar and are about of 40 mg/100 g of soil. The results obtained have shown that the soils investigated are well to moderate provided with K, Ca and Mg and that their deficit could not be expected in plant nutrition, apart for some plants/cultures in the case of magnesium due to occasionally higher Ca/Mg and K/Mg ratios

Analysis of causes of degradation of parent material and weld metal of breeches pipe at hydro power plant 'Perućica'

Presented are results of non-destructive tests performed on the parent material and welded joints of structural parts of a breeches pipe (collar and anchor), and results of destructive tests performed on the parent material of the anchor. Non-destructive testing included visual (VT), mag-netic particle (MT), and ultrasonic testing (UT), while destructive tests included determination of chemical com-position, tensile properties, impact energy and hardness. Based on test results it is established that the major cause for the occurrence of damage in the carrying structure of the breeches pipe no.1 of pipeline III, or in other words, the degradation of anchor parent material and welded joints between the collar and anchor, and between the pipeline and anchor, is in the fact that the breeches pipe started to lean, not on the collar, as specified by design, but on the anchor that could not endure all loads occurring in service

Investigation of solidification behavior of the Sn-rich ternary Sn-Bi-Zn alloys

Solidification properties and microstructure of six as-cast Sn-Bi-Zn alloys with 80 at.% of Sn and variable contents of Bi and Zn were experimentally investigated using the scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS) and differential scanning calorimetry (DSC). The experimentally obtained results were compared with predicted phase equilibria according to the calculation of phase diagram (CALPHAD) method and by the Scheil solidification simulation.