<p><strong>Apstrakt je obrađen tehnologijama za optičko prepoznavanje teksta (OCR).</strong></p><p>U cilju revitalizacije otpadnog kvasca iz industrije piva za primenu u pekarskoj industriji, kao polazna osnova za ispitivanje primenjivani su dvostepeni i jednostepeni postupak proizvodnje predfaza indirektnog postupka proizvodnje hleba, razvijeni na Tehnolo&scaron;kom fakultetu u Novom Sadu. Sprovedena su istraživanja optimizacije postupka revitalizacije otpadnog pivskog kvasca. Optimizacija je obuhvatila sastav podloge, procesne parametre proizvodnje i tehniku fermentacije. Definisan je optimalni postupak revitalizacije otpadnog pivskog kvasca i primenjen je za različite generacije i sojeve otpadnog pivskog kvasca, pri čemu je utvrđeno da otpadni pivski kvasac nulte i prve generacije nije potrebno aktivirati, dok je za kvasac starije generacije neophodno da prođu postupak aktivacije za primenu u pekarskoj industriji. Jednostepeni postupak proizvodnje predfaza u postupku aktivacije pivskog kvasca pokazao se u pogledu efekata aktivacije prihvatljiviji od dvostepenog<br />postupka. Ispitana je i trajnost otpadnog pivskog kvasca za primenu u pekarskoj industriji pri čemu je utvrdeno da otpadni pivski kvasac nije preporučljivo čuvati duže od devet dana pre njegove aktivacije. Definisan postupak je pozitivno ocenjen u pogledu tokova fermentacionih procesa za vreme proizvodnje, uticaja na svojstva hlebnog testa i uticaja na kvalitet hleba kao gotovog proizvoda. Razrađeno je idejno re&scaron;enje postrojenja za revitalizaciju otpadnog pivskog kvasca.</p> / <p><strong>Abstract was processed by technology for Optical character recognition (OCR).</strong></p><p>The aim was revitalization of beer industry waste yeast, and its application in bakery industry. A basis for investigation was one- step and two-step process for prephases production in indirect procedure for bread manufacturing, which is developed on Faculty of Technology at Novi Sad. It was investigated optimization of revitalization procedure of brewing yeast waste. Optimization contained substrate composition, proces parameters for manufacturing and fermentation technique. It is optimated revitalization of brewing yeast waste and applied for different generations and subspecies. For brewing yeast waste from initial and first generation activation is not necessary, but for olden yeast generation and its application in bakery industry, activation is necessary. In prephases production, one step activation procedure of brewing yeast had better effectiveness thay two step procedure. Durability of brewig yeast waste was also investigated. It is concluted that brewing yeast waste is not recommended for storage longer than 9 days before its activation. Defined procedure in a vijew of mahufacturing fermentative processes, influence on bread dough properties and bread quality are marked pozitively. It is also defined a pattern of projects for ravitalization of brewing yeast waste.</p>

<p>Zemlji&scaron;te predstavlja bogat izvor različitih mikroorganizama čiji<br />produkti metabolizma mogu biti od izuzetnog značaja za čoveka.<br />Dosada&scaron;nja ispitivanja mikrobnog diverziteta u zemlji&scaron;tu su<br />otkrila bogati biosintetski potencijal za proizvodnju novih<br />prirodnih proizvoda kod velikog broja mikroorganizama, naročito<br />kada je u pitanju klasa Actinobacteria. Među zemlji&scaron;nim izolatima,<br />rod Streptomyces prednjači po broju identifikovanih bioaktivnih<br />molekula u odnosu na sve ostale bakterije. Stoga je jedan od<br />ciljeva u okviru ove doktorske disertacije izolacija streptomiceta iz<br />rizosfera medicinski značajnih biljaka sakupljenih na teritoriji<br />Republike Srbije (Papaver rhoeas, Matricaria chamomilla, i Urtica<br />dioica) i ispitivanje njihovog antifungalnog potencijala na različite<br />vrste kandida. Morfolo&scaron;ki različiti izolati (ukupno 103) su izolovani<br />iz uzoraka rizosfera i okarakterisani kao streptomicete. Dve<br />različite podloge i dve procedure za ekstrakciju su kori&scaron;ćene da bi<br />se pospe&scaron;ila detekcija antifungalnih jedinjenja. Ispitan je uticaj<br />ukupno 412 ekstrakata na rast Candida albicans disk difuzionim<br />esejem pri čemu je utvrđeno da 42% (43/103) izolata imaju<br />sposobnost proizvodnje antifungalnih jedinjenja pri ispitivanim<br />uslovima. Pojedini ekstrakti su inhibirali rast važnih humanih<br />patogena poput Candida krusei, Candida parapsilosis, i Candida<br />glabrata. Na osnovu stepena i spektra antifungalne aktivnosti<br />devet izolata je odabrano za dalja istraživanja. Ispitana je<br />sposobnost njihovih ekstrakata da inhibiraju rast kandida u tečnoj<br />kulturi i u formi biofilma, a takođe je ispitan i njihov uticaj na već<br />formirane biofilmove kandide u koncentracijama od 8 do 250<br />pg/ml. Hromatografski profili ovih ekstrakata i uvid u njihovu<br />metaboličku raznolikost dobijeni su kori&scaron;ćenjem tečne<br />hromatografije visokih performansi. Tri ekstrakta sa specifičnom<br />antifungalnom aktivno&scaron;ću podvrgnuta su hemijskim analizama s<br />ciljem da se detektuju i strukturno okarakteri&scaron;u molekuli koji su<br />nosioci antifungalne aktivnosti. Na osnovu rezultata nuklearnomagnetno-<br />rezonantne spektroskopije otkriveno je da su aktivni<br />molekuli genistein, daidzein i staurosporin. Genistein i daidzein<br />koji su poznati fitoestrogeni poreklom iz sojinog bra&scaron;na za koje je<br />poznato da inhibiraju ključne enzime u biosintetskom putu<br />steroida. Njihovo prisustvo je u ovom istraživanju detektovano<br />usled kori&scaron;ćenja sojinog bra&scaron;na u hranljivoj podlozi. Kako<br />streptomicete u čijim ekstraktima su detektovani ovi molekuli<br />pokazuju sposobnost oslobađanja ovih važnih jedinjenja iz<br />kompleksne hranljive podloge, mogu se uzeti u razmatranje za<br />biotehnolo&scaron;ku proizvodnju fitoestrogena. Staurosporin je<br />detektovan kao nosilac antifungalne aktivnosti kod ekstrakta soja<br />Streptomyces sp. BV410. Staurosporin je inhibitor protein kinaza i<br />njegovi derivati i analozi se koriste u kao antitumorski agensi.<br />Biosinteza ovog molekula je optimizovana do prinosa od 36,94<br />mg/l nakon 14 dana gajenja u hranljivoj podlozi koja sadrži<br />glukozu, skrob, manitol i sojino bra&scaron;no (JS). Dalja optimizacija<br />hranljive podloge za biosintezu staurosporina ukazala je na<br />sledeći sastav hranljive podloge: 20 g/l glukoze, 0,36 g/l skroba,<br />21,46 g/l manitola, 17,32 g/l sojinog bra&scaron;na. Primenom<br />definisanih optimalnih vrednosti i kori&scaron;ćenjem odgovarajućih<br />matematičkih modela, predviđeno je da će se na ovaj način<br />postići prinosi od 46,88 mg/l staurosporina i 12,05 mg/ml<br />biomase. Validnost predviđenih rezultata potvrđena je<br />izvođenjem bioprocesa u optimizovanoj hranljivoj podlozi (JSSta).<br />Ispitana je kinetika biosinteze staurosporina i produkcije biomase,<br />kao i potro&scaron;nje izvora ugljenika i razvijeni su odgovarajući<br />procesni modeli. Dodatna optimizacija je podrazumevala dodatak<br />suplemenata koji prema literature stimuli&scaron;u sekundarni<br />metabolizam streptomiceta (joni cinka, gvožđa, fosfati, metil<br />oleat, ulje semenki grožđa). Ovi eksperimenti su izvođeni na tri pH<br />vrednosti (6,5, 7,5 i 8,5) a uspe&scaron;nost bioprocesa je procenjivana 7.,<br />10. i 14. dana gajenja. Dodatna optimizacija je dovela do podatka<br />da dodatak soli gvožđa značajno pospe&scaron;uje biosintezu<br />staurosporina sa povećanjem prinosa od 25%. Dobijeni rezultati<br />potvrđuju da su rizosfere medicinski značajnih biljaka značajan<br />izvor streptomiceta koje proizvode komponente sa<br />antifungalnom aktivno&scaron;ću. Izolacija novog proizvođača<br />staurosporina i optimizacija procesa njegove biosinteze<br />omogućiće dalja istraživanja ovog jedinjenja koje može biti<br />osnova za razvoj novih antifungalnih i jedinjenja koja inhibiraju<br />angiogenezu. Rezultati dobijeni u okviru ovih istraživanja<br />predstavljaju početni korak ka potencijalnoj industrijalizaciji<br />proizvodnje staurosporina.</p> / <p>Different soils are still a source of remarkable microbial diversity<br />which also reflects in the unexplored chemical diversity. Recent<br />advances in assessment of microbial diversity from soil have<br />revealed the extraordinarily rich biosynthetic potential for the<br />production of new natural products among different microbial<br />strains, especially within the group of Actinobacteria. Among<br />bacterial soil isolates, representatives of Streptomyces genus are<br />the most prolific producers of bioactive compounds. One of the<br />objectives of the present study was to isolate Streptomyces spp.<br />from the rhizosphere soils of three ethno-medicinal plants<br />collected in Serbia (Papaver rhoeas, Matricaria chamomilla, and<br />Urtica dioica) and to screen their antifungal activity against<br />Candida spp. Morphologically different sporulating isolates (103<br />in total) were collected from rhizosphere soil samples and<br />determined as Streptomyces spp. Two different media and two<br />extraction procedures were used to induce the production and<br />facilitate identification of antifungals. Overall, 412 crude cell<br />extracts were tested against Candida albicans using disk<br />diffusion assays, with 42% (43/103) of the strains showing the<br />ability to produce antifungal agents. Also, extracts inhibited<br />growth of other important human pathogens: Candida krusei,<br />Candida parapsilosis, and Candida glabrata. Based on the<br />established degree and range of antifungal activity, nine isolates<br />were selected for further testing. Their ability to inhibit Candida<br />growth in liquid culture, to inhibit biofilm formation, and to<br />disperse pre-formed biofilms was assessed with active<br />concentrations from 8 to 250 pg/ml. High-performance liquid<br />chromatographic profiles of extracts derived from selected<br />strains were recorded, revealing moderate metabolic diversity.<br />The most potent extracts were subjected to comprehensive<br />identification and structural characterization of antifungal<br />compounds. Applying a bioactivity-guided isolation approach,<br />active compounds of three extracts were separated, and based<br />on NMR structure elucidation it was shown that active<br />compounds were genistein, daidzein and staurosporine.<br />Genistein and daidzein, soy phytoestrogens, are known to inhibit<br />key enzymes in the steroid metabolism pathway and were<br />coming from the fermentation medium containing soy flower.<br />Since isolated Streptomyces spp. showed good ability to extract<br />these molecules from complex medium, they can be further<br />considered for biotechnological production of these<br />phytoestrogens. One of the isolates, Streptomyces sp. BV410,<br />was characterized as an efficient staurosporine producer.<br />Staurosporine is a potent inhibitor of protein kinases and is<br />considered in anticancer therapy. The biotechnological<br />production of staurosporine by strain BV410 was optimized to<br />yield 36.94 mg/l after 14 days of incubation in soy flowerglucose-<br />starch-mannitol based fermentation medium (JS).<br />Further optimization of medium for biosynthesis of<br />staurosporine indicated the following optimal values of the<br />examined factors: the content of glucose of 20 g/l, starch 0.36<br />g/l, mannitol 21.46 g/l, soy flower 17.32 g/l. By applying the<br />defined optimal values and using the appropriate mathematical<br />models, the following responses were predicted: concentration<br />of staurosporine 46.88 mg/l and biomass yield 12.05 mg/ml. The<br />validity of the results was confirmed by performing the<br />biosynthesis of the staurosporine in the medium with optimal<br />composition (JSSta). Kinetics of staurosporine and biomass<br />production and carbon source consumption were examined and<br />process models were developed. Additionally, optimization of<br />staurosporine production was performed with different<br />supplements which, according to literature data, had stimulative<br />effect on secondary metabolism (Zn, Fe and P salts, methyl<br />oleate, grape seed oil). In order to improve the production of<br />staurosporine, effects of pH (6.5, 7.5 and 8.5) and incubation time<br />(7, 10 and 14 days) were also examined. It was found that<br />addition of FeS04 significantly improved the staurosporine yield<br />in comparison to the starting conditions (increase of 25%). Our<br />results proved that rhizosphere soils of ethno-medicinal plants<br />are a prolific source of streptomycetes, producers of compounds<br />with good antifungal activity. Isolation of the new staurosporine<br />producing strain, allowed for its detailed bioactivity assessment.<br />Staurosporine scaffold might serve as a lead structure for the<br />development of new antifungal and antiangiogenic agents. Also,<br />results obtained within this research represent the basis for the<br />further scale-up and potential industrialization of the proposed<br />production process.</p>

<p>Usavršavanje aerodinamike privrednim motornih vozila putem optimizacije aerodinamičkih dodataka u svrhu postizanja boljih aerodinamičkih performansi u vidu umanjenja sile otpora vazduha. Prostiranje vazdušne struje oko modela je unapređeno optimizacionim dodacima što se sve ogleda u smanjenoj potrošnji goriva privrednog motornog vozila. Osim virtuelnih simulacija računarske dinamike fluida, u radu je prikazana validacija rezultata putem eksperimentalnog merenja u vazdušnom tunelu.</p> / <p>The improvement of commercial motor vehicle&#39;s aerodynamics through optimization process of aerodynamic equpments in order to achieve better aerodynamic performance in the form of drag force reduction. The expansion of the air flow around the model is enhanced by optimization accessories, which is all reflected in the reduced of fuel consumption of the commercial motor vehicle. In addition to virtual simulations of computational fluid dynamics, the paper presents the validation of results by experimental measurement in the wind tunnel.</p>

<p><strong>Apstrakt je obrađen tehnologijama za optičko prepoznavanje teksta (OCR).</strong></p><p>Težeći ka ostvarenju u&scaron;teda u kvascu, stabilnosti procesa, povoljnim reolo&scaron;kim svojstvima, kvalitetu hleba primerenom jugoslovenskom trži&scaron;tu i pobolj&scaron;anju svojstava hlebnog testa, sprovedena su istraživanja usmerena ka optimizaciji postupka proizvodnje predfaza indirektnog postupka proizvodnje hleba. Optimizacija je obuhvatila sastav podloge, procesne parametre proizvodnje i tehniku fermentacije. Razvijena su dva postupka automatizovane proizvodnje predfaza indirektnog postupka proizvodnje hleba pod kontrolisanim uslovima: jednostepeni i dvostepeni postupak. Oba postupka su ocenjana u pogledu tokova fermentacionih procesa za vreme proizvodnje, uticaja na svojstva hlebnog testa i uticaja na kvalitet hleba kao gotovog proizvoda na bazi kojih&nbsp;je data uporedna ocena razvijenih postupaka. Jednostepeni postupak je ocenjen kao pristupačniji u pogledu cene postrojenja i trajanja proizvodnog procesa, dok je dvostepenom postupku data prednost u pogledu etekata na sastav dobijenih kvasova, uticaja na svojstva hlebnog testa, uticaja na kvalitet i održivost svežine hleba i stabilnost procesa. Utvrđena je mogućnost primene razvijenog dvostepenog postupka za revitalizaciju pivskog kvasca. Ispitivanjem reolo&scaron;kih svojstava dobijenih poluproizvoda - kvasova, utvrđeno je da se oni pona&scaron;aju kao pseudoplastični fluidi. Razradena su idejna re&scaron;enja postrojenja za primenu jednostepenog i dvostepenog postupka i izvr&scaron;ena je ocena ekonomske efikasnosti investiranja u primenu razvijenih postupaka u pekarama.</p> / <p><strong>Abstract was processed by technology for Optical character recognition (OCR).</strong></p><p>Converging to the yeast savings, process stability, bread quality desired on Yugoslav market and improvement of bread dough properties, investigations, aimed to optimization of prephases production in indirect bread production procedure, were conducted. Optimization of substrate composition, process parameters and fermentation technigue was performed. Two processes of automated production of indirect bread production prephases under controlled conditions were developed: one step and two step process. Both processes were estimated concerning fermentation processes development during production, influence on bread dough properties and influence on bread, as final product, quality. Parallel evaluations of developed processes were performed on basis of obtained data. One step process was evaluated as more advantageous concerning plant price and production duration. Advantage was given to the two step process concerning the ettects on composition ot obtained sour dough, influence on bread dough properties, influence on bread quality and shelt life and process stability. The possibility ot application ot developed two step process for revitalization ot brewing yeast was established. Investigations of rheological properties ot obtained semiproduct - sour dough, proved their behavior according to the power low model. Draft projects of plants tor application ot one step and two step processes and estimation ot economical efficiencies ot their application in bakeries were worked out.</p>

<p>The problem under consideration is an unconstrained mini-mization problem in noisy environment. The common approach for solving the problem is Stochastic Approximation (SA) algorithm. We propose a class of adaptive step size schemes for the SA algorithm. The step size selection in the proposed schemes is based on the objective functionvalues. At each iterate, interval estimates of the optimal function&nbsp; value are constructed using the xed number of previously observed function values.&nbsp;If the observed function value in the current iterate is larger than the upper bound of the interval, we reject the current iterate. If the observed function value in the current iterate is smaller than the lower bound of the interval, we suggest a larger step size in the next iterate. Otherwise, if the function value lies in the interval, we propose a small safe step size in the next iterate. In this manner, a faster progress of the algorithm is ensured&nbsp;when it is expected that larger steps will improve the performance of the algorithm. We propose two main schemes which dier in the intervals that we construct at each iterate. In the rst scheme, we construct a symmetrical interval that can be viewed as a condence-like interval for the optimal function value. The bounds of the interval are shifted means of the xed number of previously observed function values. The generalization&nbsp;of this scheme using a convex combination instead of the mean is also presented. In the second scheme, we use the minimum and the maximum of previous noisy function values as the lower and upper bounds of the interval, respectively. The step size sequences generated by the proposed schemes satisfy the step size convergence conditions for the SA algorithm almost surely. Performance of SA algorithms with the new step size schemes is tested on a set of standard test problems. Numerical results&nbsp;support theoretical expectations and verify eciency of the algorithms in comparison to other relevant modications of SA algorithms. Application of the algorithms in LASSO regression models is also considered. The algorithms are applied for estimation of the regression parameters where the objective function contains L₁ penalty.</p> / <p>Predmet istraživanja doktorske disertacije su numerički postupci za re&scaron;avanje problema stohastičke optimizacije. Najpoznatiji numerički postupak za re&scaron;avanje pomenutog problema je algoritam stohastičke aproksimacije (SA). U disertaciji se&nbsp;&nbsp; predlaže nova klasa &scaron;ema za prilagođavanje dužina koraka u svakoj iteraciji. Odabir dužina koraka u predloženim &scaron;emama se zasniva na vrednostima funkcije cilja. U svakoj iteraciji formira se intervalna ocena optimalne vrednosti funkcije cilja koristeći samo registrovane vrednosti funkcije cilja iz ksnog broja prethodnih iteracija. Ukoliko je vrednost funkcije cilja u trenutnoj iteraciji veća od gornje granice intervala, iteracija se odbacuje. Korak dužine 0 se koristi u narednoj iteraciji. Ako je trenutna vrednost funkcije cilja manja od donje granice intervala, predlaže se duži korak u narednoj iteraciji. Ukoliko vrednost funkcije leži u intervalu, u narednoj iteraciji se koristi korak dobijen harmonijskim pravilom. Na ovaj način se obezbeđuje brzi progres algoritma i&nbsp; izbegavaju mali koraci posebno kada se povećava broj iteracija.&nbsp; &Scaron;eme izbegavaju korake proporcionalne sa 1/k kada se očekuje da ce duži koraci pobolj&scaron;ati proces optimizacije. Predložene &scaron;eme se razlikuju u intervalima koji se formiraju u svakoj iteraciji. U prvoj predloženoj &scaron;emi se formira ve&scaron;tački interval poverenja za ocenu optimalne vrednosti funkcije cilja u svakoj iteraciji. Granice tog intervala se uzimaju za&nbsp; kriterijume dovoljnog smanjenja ili rasta funkcije cilja. Predlaže se i uop&scaron;tenje ove &scaron;eme tako &scaron;to se umesto srednje vrednosti koristi konveksna kombinacija prethodnih vrednosti funkcije cilja. U drugoj &scaron;emi, kriterijum po kom se prilagođavaju dužine koraka su minimum i maksimum prethodnih registrovanih vrednosti funkcije cilja. Nizovi koji se formiranju predloženim &scaron;emama zadovoljavaju uslove potrebne za konvergenciju SA algoritma skoro sigurno. SA algoritmi sa novim &scaron;emama za prilagođavanje dužina koraka su testirani na standardnim test&nbsp; problemima i upoređ eni sa SA algoritmom i njegovim postojećim modikacijama. Rezultati pokazuju napredak u odnosu na klasičan algoritam stohastičke aproksimacije sa determinističkim nizom dužine koraka kao i postojećim adaptivnim algoritmima. Takođe se razmatra primena novih algoritama na LASSO regresijske modele. Algoritmi su primenjeni za ocenjivanje parametara modela.</p>

<p>Algorithmic trading is an automated process of order execution on electronic stock markets. It can be applied to a broad range of financial instruments, and it is&nbsp; characterized by a signicant investors&#39; control over the execution of his/her orders, with the principal goal of finding the right balance between costs and risk of not (fully) executing an order. As the measurement of execution performance gives information whether best execution is achieved, a signicant number of diffeerent benchmarks is&nbsp; used in practice. The most frequently used are price benchmarks, where some of them are determined before trading (Pre-trade benchmarks), some during the trading&nbsp; day (In-traday benchmarks), and some are determined after the trade (Post-trade benchmarks). The two most dominant are VWAP and Arrival Price, which is along with other pre-trade price benchmarks known as the Implementation Shortfall (IS).</p><p>We introduce Negative Selection as a posteriori measure of the execution algorithm performance. It is based on the concept of Optimal Placement, which represents the ideal order that could be executed in a given time win-dow, where the notion of ideal means that it is an order with the best execution price considering&nbsp; market &nbsp;conditions&nbsp; during the time window. Negative Selection is dened as a difference between vectors of optimal and executed orders, with vectors dened as a quantity of shares at specied price positionsin the order book. It is equal to zero when the order is optimally executed; negative if the order is not (completely) filled, and positive if the order is executed but at an unfavorable price.</p><p>Negative Selection is based on the idea to offer a new, alternative performance measure, which will enable us to find the&nbsp; optimal trajectories and construct optimal execution of an order.</p><p>The first chapter of the thesis includes a list of notation and an overview of denitions and theorems that will be used further in the thesis. Chapters 2 and 3 follow with a&nbsp; theoretical overview of concepts related to market microstructure, basic information regarding benchmarks, and theoretical background of algorithmic trading. Original results are presented in chapters 4 and 5. Chapter 4 includes a construction of optimal placement, definition and properties of Negative Selection. The results regarding the properties of a Negative Selection are given in [35]. Chapter 5 contains the theoretical background for stochastic optimization, a model of the optimal execution formulated as a stochastic optimization problem with regard to Negative Selection, as well as original work on nonmonotone line search method [31], while numerical results are in the last, 6th chapter.</p> / <p>Algoritamsko trgovanje je automatizovani proces izvr&scaron;avanja naloga na elektronskim berzama. Može se primeniti na &scaron;irok spektar nansijskih instrumenata kojima se trguje na berzi i karakteri&scaron;e ga značajna kontrola investitora nad izvr&scaron;avanjem njegovih naloga, pri čemu se teži nalaženju pravog balansa izmedu tro&scaron;ka i rizika u vezi sa izvr&scaron;enjem naloga. S ozirom da se merenjem performasi izvr&scaron;enja naloga određuje da li je postignuto najbolje izvr&scaron;enje, u praksi postoji značajan broj različitih pokazatelja. Najče&scaron;će su to pokazatelji cena, neki od njih se određuju pre trgovanja (eng. Pre-trade), neki u toku trgovanja (eng. Intraday), a neki nakon trgovanja (eng. Post-trade). Dva najdominantnija pokazatelja cena su VWAP i Arrival Price koji je zajedno sa ostalim &quot;pre-trade&quot; pokazateljima cena poznat kao Implementation shortfall (IS).</p><p>Pojam negative selekcije se uvodi kao &quot;post-trade&quot; mera performansi algoritama izvr&scaron;enja, polazeći od pojma optimalnog naloga, koji predstavlja idealni nalog koji se&nbsp; mogao izvrsiti u datom vremenskom intervalu, pri ćemu se pod pojmom &quot;idealni&quot; podrazumeva nalog kojim se postiže najbolja cena u trži&scaron;nim uslovima koji su vladali&nbsp; u toku tog vremenskog intervala. Negativna selekcija se defini&scaron;e kao razlika vektora optimalnog i izvr&scaron;enog naloga, pri čemu su vektori naloga defisani kao količine akcija na odgovarajućim pozicijama cena knjige naloga. Ona je jednaka nuli kada je nalog optimalno izvr&scaron;en; negativna, ako nalog nije (u potpunosti) izvr&scaron;en, a pozitivna ako je nalog izvr&scaron;en, ali po nepovoljnoj ceni.</p><p>Uvođenje mere negativne selekcije zasnovano je na ideji da se ponudi nova, alternativna, mera performansi i da se u odnosu na nju nađe optimalna trajektorija i konstrui&scaron;e optimalno izvr&scaron;enje naloga.</p><p>U prvom poglavlju teze dati su lista notacija kao i pregled definicija i teorema&nbsp; neophodnih za izlaganje materije. Poglavlja 2 i 3 bave se teorijskim pregledom pojmova i literature u vezi sa mikrostrukturom trži&scaron;ta, pokazateljima trgovanja i algoritamskim trgovanjem. Originalni rezultati su predstavljeni u 4. i 5. poglavlju. Poglavlje 4 sadrži konstrukciju optimalnog naloga, definiciju i osobine negativne selekcije. Teorijski i praktični rezultati u vezi sa osobinama negativna selekcije dati su u [35]. Poglavlje 5 sadrži teorijske osnove stohastičke optimizacije, definiciju modela za optimalno izvr&scaron;enje, kao i originalni rad u vezi sa metodom nemonotonog linijskog pretraživanja [31], dok 6. poglavlje sadrži empirijske rezultate.</p>

<p>Cilj istraživanja u okviru ove doktorske disertacije bio je da se ispita uticaj ekstrudiranja na funkcionalno hranivo, čija bi osnovna uloga bila povećanje sadržaja omega-masnih kiselina u ishrani životinja, a naročito &alpha;-linolenske kiseline (ALA). Za proizvodnju funkcionalnog hraniva upotrebljeni su laneno seme, kao nosilac funkcionalnih osobina i suncokretova sačma, koja je dodata da se spreči isticanje lanenog ulja tokom ekstrudiranja. Nezavisni parametri ekstrudiranja čiji je uticaj ispitivan bili su: brzina obrtanja puža ekstrudera (240, 360 i 590 o/min), kapacitet punjenja (16, 24 i 32 kg/h), vlaga polaznog materijala (7, 11,5 i 16 %) i ukupna povr&scaron;ina otvora na matrici (19,8, 39,6 i 59,4 mm2). Zavisno promenljive karakteristike (odzivi) dobijenog hraniva koje su praćene bile su: sadržaj HCN u hranivu, sadržaj ALA, sadržaj slobodnih masnih kiselina (SMK) i potro&scaron;nja energije.<br />Za modelovanje zavisnosti karakteristika hraniva od procesnih parametara ekstrudiranja primenjena je metoda odzivne povr&scaron;ine (RSM), a kori&scaron;ćen je Box-Behnken-ov dizajn (BBD) za četiri faktora na tri nivoa. Za svaki od pomenutih odziva definisan je polinom drugog reda i određeni su koeficijenti polinoma, a analizom varijanse potvrđena je tačnost ovih modela. Formirani modeli upotrebljeni su za optimizaciju procesa ekstrudiranja, sa ciljem da se postigne &scaron;to veća redukcija<br />cijanogenih glikozida u hranivu, uz &scaron;to vi&scaron;i sadržaj ALA i &scaron;to niže SMK i potro&scaron;nju energije. Da bi se zadovoljili svi postavljeni uslovi optimizacije, proces ekstrudiranja bilo je potrebno izvoditi pod sledećim uslovima: brzina obrtanja puža &ndash; 417,41 o/min, kapacitet punjenja &ndash; 32 kg/h, vlaga materijala &ndash; 13,39 % i ukupna povr&scaron;ina otvora na<br />matrici &ndash; 19,80 mm2.<br />Ovako dobijeno hranivo pokazalo je nizak sadržaj HCN, čiji je stepen redukcije u odnosu na početnu vrednost iznosio 76,20 %. Sa druge strane, sadržaj ALA smanjen je za svega 0,69 %, &scaron;to ukazuje da ekstrudiranje nije negativno uticalo na masnokiselinski sastav proizvedenog ko-ekstrudata.<br />Nakon proizvodnje ko-ekstrudata, pristupilo se ispitivanju njegove održivosti. U tu svrhu uzorci su skladi&scaron;teni u klima komori sa mogućno&scaron;ću kontrolisanog pode&scaron;avanja temperature, relativne vlažnosti i cirkulacije vazduha. Za praćenje održivosti proizvoda primenjen je modifikovan Schaal-oven test. Modifikacija metode sastojala se u pode&scaron;avanju relativne vlažnosti vazduha na konstantnu vrednost od 40 %, &scaron;to klasičnom metodom nije propisano. Ova vlažnost vazduha odabrana je na osnovu relativne vlažnosti koja je u trenutku eksperimenta izmerena u prostoriji. U cilju ispitivanja uticaja antioksidanasa na oksidativnu stabilnost proizvoda, uzorcima su dodavani komercijalni preparati karvakrol (200 mg/100 g koekstrudata), vitamin E (135 mg/100 g ko-ekstrudata) i sme&scaron;a ova dva antioksidansa. Za praćenje oksidativnih i hemijskih promena ko-ekstrudata, određivani su peroksidni broj (Pbr), SMK uzorcima su dodavani komercijalni preparati karvakrol (200 mg/100 g koekstrudata), vitamin E (135 mg/100 g i masnokiselinski sastav. Takođe su ispitane mikrobiolo&scaron;ke promene u koekstrudatu. Najsnažnije antioksidativno dejstvo u ovom eksperimentu imao je vitamin E, dok sme&scaron;a vitamina E i karvakrola nije pokazala sinergističko dejstvo. Sastav masnih kiselina se u toku skladi&scaron;tenja nije statistički značajno promenio. Sa druge strane, ekstrudiranje je pokazalo statistički značajan uticaj (p = 0,032) na redukciju ukupnog broja mikroorganizama u hranivu, a najniža vrednost ukupnog broja mikroorganizama (600 cfu/g) zabeležena je u uzorku sa dodatim karvakrolom.</p> / <p>The goal of the research in this thesis was to examine the effect of extrusion on functional feed compound, whose main role was to increase the content of omega-fatty acids in animal nutrition, especially &alpha;-linolenic acid (ALA). Flax seed, as the holder of the functional properties, and sunflower meal, as an adsorbent of linseed oil during extrusion, were used for the production of functional feed compound. Independent extrusion parameters studied in the experiment were: extruder screw speed (240, 360 and 590 rpm), loading capacity (16, 24 and 32 kg/h), the moisture content of the starting material (7, 11.5 and 16 % ) and the total die opening&rsquo;s area (19.8, 39.6 and 59.4 mm2). Dependent variables (responses) of the produced feed compound were: HCN content in coextrudate, ALA content, the content of free fatty acids (FFA) and energy consumption.<br />Response surface methodology (RSM) was applied in order to model mathematical dependence between co-extrudate characteristics and the independent process parameters. The experiments were designed according to Box-Behnken&#39;s design (BBD) with four factors, each at three levels. Second-order polynomial equation was<br />developed for each of these responses, and polynomial coefficients were determined. Accuracy of each model was confirmed by analysis of variance (ANOVA). Formed polynomial models were used to optimize the extrusion process, with the aim of achieving high reduction of cyanogenic glycosides in feed compound, the highest content of ALA, as well as low FFA and low energy consumption. Obtained optimal conditions were: extruder srew speed - 417.41 rpm, loading capacity - 32 kg/h, moisture content of starting material - 13.39 % and the total die openings&rsquo; area<br />- 19.80 mm2.<br />Functional feed compound produced under these conditions showed a low concentration of HCN, and the degree of HCN reduction was 76.20 % compared to the starting HCN content. On the other hand, the ALA content was reduced by only 0.69 %, indicating that extrusion did not significantly affect the fatty acid composition of the produced co-extrudate.<br />The next step was investigation of stability of produced co-extrudate. For this purpose, the samples were stored in a climate chamber capable of setting temperature, relative humidity and air circulation. Modified Schaal-oven test was used to monitor the stability of the product. Modification of the method consisted in adjusting the relative humidity at a constant value of 40 %, which is not required by a classical method. Such a high humidity was selected based on the relative humidity at a constant value of 40 %, which is not required by a classical method. Such a high humidity was selected based on the relative humidity of air, which was measured in the experimental room at the moment. Commercial carvacrol (200 mg/100g of co-extrudate), vitamin E (135 mg/100 g of co-extrudate) and a mixture of these<br />two antioxidants were added to the samples in order to investigate the influence of antioxidants on the oxidative stability of the product. Peroxide value (PV), FFA and fatty acid composition were determined in order to monitor oxidative and chemical changes in co-extrudate. Microbial changes were also examined in the functional feed compound. The most powerful antioxidant effect in this experiment had vitamin E, and a mixture of vitamin E and carvacrol did not show a synergistic effect. The fatty acid compostion during storage was not significantly changed in any sample. On the other hand, extrusion process showed a statistically significant effect (p = 0.032) on the reduction of total number of microorganisms in feed, and the lowest value of the total number of microorganisms (600 cfu/g) was observed in the sample with added<br />carvacrol.</p>

<p>Istraživanja u okviru disertacije usmerena su na razvoj vakuumskog postupka su&scaron;enja voća. Konstruisan je prototip laboratorijske vakuumske su&scaron;are i optimizovan proces su&scaron;enja vi&scaron;anja i borovnica. U cilju optimizacije procesa su&scaron;enja ispitan je uticaj nezavisno promenljivih procesa, temperature i pritiska, na parametre kvaliteta osu&scaron;enog voća (aktivnost vode, sadržaj ukupnih fenola, ukupnih monomernih antocijana i vitamina C, antioksidativnu aktivnost, promenu boje, teksturu i sposobnost rehidratacije). Proces su&scaron;enja optimizovan je kori&scaron;ćenjem metode odzivnih povr&scaron;ina (engl. Response Surface Methodology, RSM).<br />Rezultati istraživanja pokazuju da tehnika su&scaron;enja voća u vakuumu daje odlične rezultate u pogledu očuvanja visokovrednih komponenata voća i ima perspektivu za &scaron;iru primenu u zanatskim i poluindustrijskim postrojenjima.</p> / <p>Research in the framework of the thesis focuses on the development of fruit vacuum-drying process. Laboratory vacuum dryer prototype was constructed. Cherries and blueberries vacuum drying process was optimized. In order to optimize the drying process, the influence of independent variables of the process (temperature and pressure) on the quality parameters of dried fruit (water activity, total phenol content, total monomeric anthocyanins and vitamin C, antioxidant activity, colour change, texture, and rehydration capability) was investigated. The drying process was optimized using Response Surface Methodology (RSM).<br />There is the possibility of application of the results in plants at semi-industrial and industrial level.</p>

<p>U ovoj disertaciji je kvantitativno određen odnosa energetske<br />efikasnosti i pouzdanosti u bežičnim senzorskim mrežama na<br />fizičkom sloju i sloju kontrole pristupa medijumu. Pronađene<br />su optimalne vrednosti ovog odnosa u smislu vi&scaron;eciljne<br />optimizacije sa Pareto pristupom, bez preferenci.</p> / <p>In this dissertation we quantify energy-efficiency and reliability<br />trade-off in wireless sensor networks at physical and medium<br />access control layers. We find the trade-off optimal solutions in<br />the sense of multi-objective Pareto optimality, without<br />preferences.</p>

<p>U radu je izvršeno eksperimentalno istraživanje procesa obrade<br />glodanjem u cilju saznanja o obradivosti legure aluminijuma dobijene<br />sa dva različita tipa livenja. Izvršeno je modeliranje funkcija<br />obradivosti preko izmerenih karakteristika stanja procesa: sila<br />rezanja, hrapavosti obrađene površine, temperature u procesu rezanja<br />i faktora sabijanja strugotine. Modeliranje funkcija obradivosti je<br />izvršeno pomoću faktornog plana eksperimenta, kao i primenom<br />veštačkih neuronskih mreža i fazi logike. Optimizacija ulaznih<br />parametara procesa obrade glodanjem sprovedena je pomoću Taguči<br />metode. Proces glodanja simuliran je pomoću metoda konačnih<br />elemenata.</p> / <p>In this work an experimental research of the milling process were performed<br />in order to find out the machinability of aluminum alloys which are obtained<br />with two different types of casting procedure. Modeling of machinability<br />functions is performed through the measured process state characteristics:<br />cutting force, surface roughness, temperature in the cutting zone and chip<br />compression ratio. Modeling of the machinability functions was performed<br />using a full factorial experiment and through the model of artificial neural<br />networks and fuzzy logic. Optimization of process input values in defined<br />models is performed through Taguchi methods. The process of milling is<br />simulated with finite element method.</p>