Usporedba performansi različitih algoritama upravljanja robotskim manipulatorom

In this work are compared performances of five different robot control algorithms. The following controllers under consideration are: PD controller, PID controller, analytical fuzzy controller, classical adaptive controller and adaptive controller based on neural network. The mentioned controllers are used to control two different robot configurations with two rotational degrees of freedom (in horizontal and vertical plane). The basic performances for control algorithms comparisons are: tracking error, rate of convergence, robustness on structural changes of control object, complexity of stability criterion and complexity of implementation.U ovom radu uspoređuju se performanse pet različitih algoritama upravljanja robotom. Razmatraju se sljedeći regulatori: PD regulator, PID regulator, analitički neizraziti regulator, klasični adaptivni regulator i adaptivni regulator temeljen na neuronskoj mreži. Navedeni regulatori primijenjeni su na upravljanje dvjema različitim konfiguracijama robota s dva rotacijska stupnja slobode gibanja (u horizontalnoj i vertikalnoj ravnini). Osnovne performanse prema kojima se upravljački algoritmi uspoređuju su: pogreška vođenja, brzina konvergencije, robusnost na promjene strukture objekta upravljanja, složenost kriterija stabilnosti, te složenost implementacije

INVESTMENTS IN SERBIAN AGRICULTURE

The paper shows the relation between gross domestic product (GDP) and investments in the Republic of Serbia. The observed relation was analyzed at the economy level, as well as in agricultural particular. The observation period is from 2005 to 2020. The function of investments is overviewed through the capital ratio. In this way, it was established to what extent part of the newly created value is returned to the production process, both at the level of the entire economy and at the level of agricultural activity separately. The low participation of investments in the gross domestic product is highlighted, which indicates an unfavorable relationship towards economic and agricultural activity for the observed time period

Upotreba api-fito terapije u suzbijanju subkliničkih mastitisa muznih krava

Production of high quality milk, milk containing low number of bacteria (several thousand to lt 141 000 cells/ml of milk) and low number of somatic cells count (SČ), is the target of Program of control and prevention of mastitis in dairy cows. Program of mastitis control must provide diagnostic tests for evaluation of udder infections by enviromental microorganizams and prevention of new intramammarian infections (IMI). The evidence is presented that longterm, intensive program of teat désinfection after milking and therapy of dryed cows are procedures which are enabling significant decrease of SČ and number of bacteria in 1 ml of milk. Clinical changes of udder are offtenly caused by Corynebacterium bovis, Streptococcus sp. and Staphylococcus sp. which are also responsible for increasment of SČ and IMI cases. Knowing that most of mastitisies are subclinical by character, than it is understandable that various IMI of dairy cows are appearing after usage of the various antiseptics. We have been using accessory remedy for dry milking VETER-D, for prevention of sub-clinical mastitisies, "dry" milking and evaluation of IMI spreadness in udder health ma-nagment program, on 403 dairy cows.Cilj programa i kontrole i suzbijanja mastitisa kod muznih krava je proizvodnja mleka visokog kvaliteta, tj. mleka koje će sadržati mali broj bakterija (od nekoliko hiljada do = 141 000 ćelija/ml mleka) i somatskih ćelija. Program kontrole mastitisa trebalo bi da ima kontrolu infekcija vimena sa organizmima sredine i efikasan sistem praćenja i sprečavanja novih intramamarnih infekcija vimena (MI). Postoje dokazi da dugoročni intenzivni programi dezinfekcije sisa posle muže i terapija zasušenih krava mogu izrazito da smanje broj SČ i bakterija u 1 ml mleka. Kliničke promene na vimenu najčešće izazivaju Corynebacterium bovis, streptokoke i stafiloke i to su faktori koji najviše povećavaju SČ i intramamarne infekcije. Budući daje većina mastitisa subklinička, postoji različit broj intramamarnih infekcija (IMI) vimena muznih krava posle dezinfekcije sisa sa različitim antisepticima. Mi smo upotrbljavaîi pomoćno lekovito sredstvo VETER-D za suzbijanje subkliniČkih mastitisa, "suvu" mužu i ispitivanje rasprostranjenosti IMI u menadžerskom programu zdravlja vimena, na 403 krave

Technical efficiency assessment by the application of a stochastic frontier analysis in the dairy farming sector in the Republic of Serbia

Predmet istraživanja u ovoj disertaciji predstavljaju registrovana poljoprivredna gazdinstva specijalizovana za proizvodnju mleka u Republici Srbiji. Analizirano je ukupno 70 poljoprivrednih gazdinstava, a podaci su preuzeti iz FADN uzorka za period od 2015. do 2019. godine. S druge strane, cilj istraživanja je najpre oceniti tehničku efikasnost posmatranih gazdinstava, a zatim i ispitati uticaj različitih faktora na ostvarenu tehničku efikasnost. Tehnička efikasnost analiziranih gazdinstava je ocenjena primenom modela stohastičke granične proizvodne funkcije, gde se pod pojom tehničke efikasnosti podrazumeva sposobnost donosioca odluka na gazdinstvu da ostvare maksimalni autput uz određeni nivo angažovanog inputa. Funkcionalna forma modela se zasniva na modifikovanoj Cobb-Douglasovoj proizvodnoj funkciji. Kao zavisno promenljiva u modelu proizvodne funkcije koja predstavlja ostvareni autput posmatranih gazdinstava, korišćena je ukupno ostvarena vrednost poljoprivredne proizvodnje. S druge strane, kao nezavisno promenljive u modelu proizvodne funkcije korišćene su varijable koje se odnose na angažovani rad, kapital, ukupne troškove proizvodnje i korišćeno poljoprivredno zemljište. Pored navedenog, u cilju ocene eventualnog prisustva tehničkog progresa korišćena je i varijabla koja se odnosi na godine posmatranja. U prvoj fazi istraživanja, primenom modela stohastičkih graničnih proizvodnih funkcija, oslanjajući se na modifikovanu Cobb-Douglas-ovu proizvodnu funkciju, izvršena je ocena tehničke efikasnosti posmatranih gazdinstava. Ocenjeno je ukupno šest različitih klasa modela stohastičkih graničnih proizvodnih funkcija, koje se međusobno razlikuju u skladu sa primenjenom metodologijom ocene. Generalno posmatrano, prednost modela stohastičkih graničnih proizvodnih funkcija u odnosu na determinističke modele, ogleda se kroz prisustvo kompozitne slučajne greške modela na osnovu koje je moguće ispitati uticaj dodatnih faktora na prethodno ocenjenu tehničku efikasnost. U skladu sa prethodno navedenim, u drugoj fazi istraživanja ispitan je uticaj dodatnih objašnjavajućih promenljivih koje se odnose na: karakteristike donosioca odluka na gazdinstvu, karakteristike poljoprivrednih gazdinstava, ekonomske mere agrarne politike i prirodne uslove. Različiti faktori od uticaja na ostvarenu tehničku efikasnost posmatranih gazdinstava identifikovani su na osnovu prethodno sprovedene analize empirijskih istraživanja u vezi sa tehničkom efikasnošću poljoprivrednih gazdinstava specijalizovanih za mlečno govedarstvo. U skladu sa dodatnim faktorima od uticaja formulisano je osam radnih hipoteza koje su u nastavku istraživanja proverene. Iako je za očekivati bilo da se ocenom različitih klasa modela dobiju razlilčite ocene tehničke efikasnosti, utvrđene su izvesene pravilnosti po pitanju statističke značajnosti posmatranih varijabli bez obzira na ocenjenu klasu modela. U prvoj fazi istraživanja, ustanovljen je statistički značajan uticaj kapitala i ukupnih troškova proizvodnje na ostvarenu vrednost proizvodnje. Takođe, utvrđena je i pozitvna promena produktivnosti za posmatrani petogodišnji period. S druge strane, ustanovljeno je da angažovani rad i korišćeno poljoprivredno zemljište nemaju statistički značajan uticaj na ostvarenu vrednost proizvodnje. Drugim rečima, ustanovljeno je da se dodatnim ulaganjem u opremu, objekte, mehanizaciju, osnovno stado i nabavkom kvalitetnijih inputa u proizvodnom procesu može očekivati i bolji proizvodni rezultat u sektoru mlečnog govedarstva. Dodatno, ustanovljeno je da rad i zemljište nisu ograničavajući faktori kada je reč o ostvarenoj vrednosti proizvodnje.The research in this dissertation focuses on registered agricultural holdings specializing in milk production in the Republic of Serbia. A total of 70 agricultural holdings are analyzed while the data was collected from the FADN sample for the period between 2015 and 2019. The research aims to assess the technical efficiency of the analyzed holdings and then investigate the influence of different factors on the realized technical efficiency. The technical efficiency of the analyzed holdings is assessed using the stochastic frontier analysis. The term technical efficiency refers to the ability of the decision-maker on an agricultural holding to maximize its output with a certain extent of the engaged input. The model’s functional form is based on the modified Cobb-Douglas production function. The total realized value of agricultural production is used as the dependent variable in the production function model, representing the realized output of the analyzed holdings. On the other hand, the variables related to the amount of work put in, capital, production costs, and used agricultural land are used as independent variables in the production function model. In addition, a variable concerning the observation period is also used to assess the possible presence of technical progress. In the first stage of the research, the technical efficiency of the analyzed holdings is assessed by the application of the stochastic frontier analysis, based on the Cobb-Douglas production function. Six different classes of the stochastic frontier analysis model are assessed. These classes differ from each other, depending on the applied assessment methodology. One advantage of the stochastic frontier analysis model over deterministic models includes the presence of the composite error which makes it possible to analyze the influence of additional factors on the previously assessed technical efficiency. The second stage of the research focuses on the influence of explanatory variables related to the characteristics of the decision-maker on a holding, the characteristics of agricultural holdings, economic measures of the agricultural policy, and natural conditions. Different factors influencing the achieved technical efficiency of the analyzed holdings are identified by means of a previously conducted analysis of empirical research on the technical efficiency of the agricultural holdings specialized in dairy farming. According to the additional influencing factors, eight working hypotheses are formulated and examined in the rest of the research. Despite the prediction that the assessment of different classes of the model will give different assessments of technical efficiency, certain regularities concerning the statistical significance of the analyzed variables are determined regardless of the assessed model class. The first stage of the research defines a statistically significant influence of capital and total production costs on the realized production value. Furthermore, a positive productivity change is determined in the analyzed five-year period. On the other hand, it is learned that the amount of work put in and used agricultural land do not have any statistically significant influence on the realized production value. In other words, the conclusion is that additional investment in equipment, agricultural mechanization, foundation stocks, and higher-quality inputs in the production process should bring better production results in the dairy farming sector. It is also concluded that work and land are not restricting factors regarding the realized production value

Rheological changes during fermentation of goats and cow\u27s milk using Lactobacillus acidophilus

U radu su praćene promjene reoloških parametara tijekom fermentacije kozjeg i kravljeg mlijeka bakterijom Lactobacillus acidophilus. Reološka svojstva gruša jedan su od osnovnih parametara kvalitete fermentiranih mliječnih proizvoda. Grušanje mlijeka odvija se uslijed snižavanja pH-vrijednosti tijekom fermentacije i uvjetovano je neutralizacijom i demineralizacijom kazeinskog kompleksa i otpuštanjem vode iz micelijske mreže kazeinata uslijed povećane koncentracije H+-iona. Promjene strukture gruša kozjeg i kravljeg mlijeka praćene su sa svrhom uspoređivanja s brzinama njihove fermentacije. I kozje i kravlje mlijeko nenewtonovske su tekućine, koje tijekom fermentacije postupno poprimaju izrazita svojstva karakteristična za pseudo-plastični (tiksotropni) tip tekućim. Formiranje gruša kod kozjeg i kravljeg acidofila započinje u trećem satu fermentacije. Pokazalo se da znatnije promjene reoloških svojstava kozjeg mlijeka nastupaju pri nižim pH vrijednostima od onih kravljeg, a porast prividnog viskoziteta kozjeg fermentiranog acidofilnog mlijeka je ujednačeniji i proporcionalniji padu pH vrijednosti tijekom fermentacije. Na kraju fermentacije kozje acidofilno mlijeko je prividno nižeg viskoziteta od kravljeg pri 22 °C. Tijekom tri dana čuvanja pri 4 °C značajno se poboljšavaju reološka svojstva kozjeg fermentiranog acidofilnog mlijeka koje postaje konzistentnije, dok je promjena konzistencije kravljeg acidofilnog mlijeka tijekom skladištenja neznatna.The changes of rheological properties during goat\u27s and cow\u27s milk fermentation using Lactobacillus acidophilus were observed in this paper. Rheological properties of curd are one of the basic parameters of fermented milk products quality. Milk curdling occurs as a consequence of the pH-value lowering during milk fermentation and it is the result of caseinat complex demineralisation and water molecules discharge from the lactic caseinate owing to the increase of H+-ions concentration. The differences in the curd structure between goat\u27s and the cow\u27s acidophilus milk were attended in the aim to compare those differences with fermentation velocities. Both of them, goat\u27s and cow\u27s acidophilus milk, are nonnewton fluids progressively obtaining characteristic properties of pseudoplastic (ticsotropic) type of fluids during fermentation. Goat\u27s and cow\u27s milk curdling starts in the third hour of fermentation. It was shown that extensive changes of goat\u27s milk rheological properties were starting with the significantly lower pH-value than cow\u27s milk and the increase of apparent viscosity is more steady in goat\u27s acidophilus milk and it is proportional to pH-value fall during fermentation. At the end of the fermentation goat\u27s acidophilus milk has lower apparent viscosity than cow\u27s acidophilus milk at 22 °C. During three storage days at 4 °C Theological properties of goat\u27s acidophilus milk were considerably improved (goats acidophilus milk became more consistent). During storage the consistency change of cow\u27s acidophilus milk is minor

Assessment of Beef Manure Economic Value by the Method of Equivalent Green and Mineral Fertilizer Substitution

The imperative of sustainable agricultural development, coupled with growing challenges related to climate change reaffirms the importance of manure and increases the demand for it. Due to the underdeveloped market for manure, there is a problem in assessing its economic value, requiring appropriate research on this topic. Thus, this research aimed to assess the manure’s economic value using the method of equivalent substitution. For this purpose, the chemical composition of manure was determined by standard agrochemical analyses concerning the content of the most important mineral elements—nitrogen (N), phosphorus (P2O5), and potassium (K2O). These elements ranged from 0.49–0.60%, 0.15–1.10%, and 0.70–1.07%, respectively, and the content of organic matter ranging from 20.88 to 27.00%. Subsequently, the cost of equivalent substitution was calculated taking into account market prices for commercial fertilizers and organic matter based on the cost of an adequate quantity of white mustard—Sinapis alba L. fresh mass. The average cost of equivalent substitution for manure was determined to be 28.60 USD/t. The results of the applied t-test indicate that there is no statistically significant difference between the market prices of beef manure and the calculated prices of its substitution (t = −1.4069; df = 12; p = 0.1848), which implies that white mustard green manure could replace the deficit in animal-derived manure. Since both animal and green manures unambiguously should be prioritized over chemical fertilizers, future studies will reveal which other crops are applicable for further increments of green manure to make up for insufficient availability of animal manure

Technical Efficiency of Agriculture in the European Union and Western Balkans: SFA Method

Improvements in productivity and efficiency, together with agricultural modernization, are crucial in the process of future sustainable development. As Western Balkan (WB) countries are in the process of integration into the European Union (EU), the importance of agricultural efficiency in an economic and environmental context and the actuality of the problems of the agricultural sector are very important. In that context, the paper’s main goal is to examine agriculture’s technical efficiency in the EU and WB. The additional goal is to group analyzed countries by agricultural performances. A stochastic frontier analysis (SFA) is used to calculate the technical efficiency of agriculture. Results have shown a significant difference in technical efficiency between WB and the EU. Furthermore, the cluster analysis has indicated the connection between overall economic development and agricultural development, partially “deformed” by agri-environmental and climate conditions. The exogenous factors do not have a crucial influence on the overall technical efficiency of agriculture in observed countries, indicating that the endogenous factors must be improved. The paper impacts recommendations for optimizing the use of inputs and improving the educations of farmers in WB countries to achieve economic and environmental goals

Technical Efficiency of Agriculture in the European Union and Western Balkans: SFA Method

Improvements in productivity and efficiency, together with agricultural modernization, are crucial in the process of future sustainable development. As Western Balkan (WB) countries are in the process of integration into the European Union (EU), the importance of agricultural efficiency in an economic and environmental context and the actuality of the problems of the agricultural sector are very important. In that context, the paper’s main goal is to examine agriculture’s technical efficiency in the EU and WB. The additional goal is to group analyzed countries by agricultural performances. A stochastic frontier analysis (SFA) is used to calculate the technical efficiency of agriculture. Results have shown a significant difference in technical efficiency between WB and the EU. Furthermore, the cluster analysis has indicated the connection between overall economic development and agricultural development, partially “deformed” by agri-environmental and climate conditions. The exogenous factors do not have a crucial influence on the overall technical efficiency of agriculture in observed countries, indicating that the endogenous factors must be improved. The paper impacts recommendations for optimizing the use of inputs and improving the educations of farmers in WB countries to achieve economic and environmental goals

Distribution, Genetic Diversity and Biocontrol of Aflatoxigenic Aspergillus flavus in Serbian Maize Fields

Maize is one of the leading export products in the Republic of Serbia. As a country where economic development depends on agriculture, maize production plays a critical role as a crop of strategic importance. Potential aflatoxin contamination of maize poses a risk to food and feed safety and tremendous economic losses. No aflatoxin contamination of maize samples harvested in 2019 and 2020 in different localities in the Republic of Serbia was detected by the Enzyme-Linked Immunosorbent Assay (ELISA) test and High-Performance Liquid Chromatography (HPLC) method. On the other hand, the Cluster Amplification Patterns (CAP) analyses of the isolated Aspergillus flavus strains from 2019 maize samples confirmed the presence of key biosynthesis genes responsible for aflatoxin production. Artificial inoculation and subsequent HPLC analysis of the inoculated maize samples confirmed the high capacity of the A. flavus strains for aflatoxin production, pointing to a high risk of contamination under favorable conditions. Prevention of aflatoxin contamination is primarily based on A. flavus control, where biocontrol agents play a significant role as sustainable disease management tools. In this study, antagonistic activity screening of the novel strains belonging to the Bacillus genus indicated superior suppression of A. flavus strains by two Bacillus strains isolated from the rhizosphere of Phaseolus vulgaris