Least squares fitting the three-parameter inverse Weibull density

The inverse Weibull model was developed by Erto [10]. In practice, the unknown parameters of the appropriate inverse Weibull density are not known and must be estimated from a random sample. Estimation of its parameters has been approached in the literature by various techniques, because a standard maximum likelihood estimate does not exist. To estimate the unknown parameters of the three-parameter inverse Weibull density we will use a combination of nonparametric and parametric methods. The idea consists of using two steps: in the first step we calculate an initial nonparametric density estimate which needs to be as good as possible, and in the second step we apply the nonlinear least squares method to estimate the unknown parameters. As a main result, a theorem on the existence of the least squares estimate is obtained, as well as its generalization in the $l_p$ norm ($1leq p<infty$). Some simulations are given to show that our approach is satisfactory if the initial density is of good enough quality

On nonlinear weighted least squares fitting of the three-parameter inverse Weibull distribution

In this paper we consider nonlinear least squares fitting of the three-parameter inverse Weibull distribution to the given data $(w_i,t_i,y_i)$, $i=1,ldots,n$, $ngeq 3$. As the main result, we show that the least squares estimate exists provided that the data satisfy just the following two natural conditions: (i) $0<t_1<t_2<ldots<t_n$ and (ii) $0<y_1<y_2<ldots<y_n<1$. To this end, an illustrative numerical example is given

Densification of BTS Functionally Graded Materials during Sintering

Poster presented at the 10th Conference of the Materials Research Society of Serbia - YUCOMAT 2008, Herceg Novi, Crna Gora, 8-12. septembar 2008

Application of the master Sintering Curve Theory to Sintering of BTS FGMs

Poster presented at PHYSICAL CHEMISTRY 2008. 9th International Conference on Fundamental and Applied Aspects of Physical Chemistry, Belgrade, September 24-26, 200

Numerical flow computation of fluid mixing

Influence of lateral injected stream, perpendicular to the axis of regular conical nozzle with circular cross section, is analyzed both in subsonic and transonic three-dimensional, turbulent, viscous flows. Turbulence effects are introduced by the formulation based on turbulent kinetic energy. Influence of second fluid component will be analyzed by the application of volume of fluid mixing model. Application in development of machines and equipment for food industry was also analyzed.

Economic indicators of precision guidance in crop production in Agricultural Corporation Belgrade (PKB)

U ovom radu ispitan je stepen ušteda pri primeni najsavremenijih tehničkih sistema za satelitsko navođenje i automatsko upravljanje pri obavljanju poljoprivrednih operacija tokom cele sezone. Ogledno imanje bila je Poljoprivredna korporacija Beograd koja se prostire na oko 21000 hektara obradive površine. Analiziran je uticaj oblika parcele i pravca kretanja agregata pri kalkulisanju ušteda usled smanjenja preklopa susednih prohoda. Izvršena je analiza ušteda po kulturama (kukuruz, pšenica, soja, šećerna repa i detelina) i po operacijama za svaku kulturu pojedinačno, prema tehnologiji proizvodnje primenjenoj na oglednom imanju. Poređenjem ostvarenih stepena uštede zaključeno je pri kojim operacijama je primena navođenja ekonomski najopravdanija i koliki nivo opremljenosti uređajima za navođenje i upravljanje je potreban. Posebno je analizirana funkcionalna zavisnost ekonomskih ušteda u gorivu i inputima za operacije distribucije hraniva i zaštite biljaka. Tabelarno je data procena stepena svih očekivanih ušteda za operacije koje se odnose na pet analiziranih kultura.This paper examined the level of savings in the application of modern technical systems for satellite guidance and control over performing agricultural operations throughout the season. The exemplary property was Agricultural Corporation Belgrade (PKB), which covers about 21,000 hectares of arable land. The effects of plot shape and direction of movement of tractor-attachment units in calculating the savings from reduced overlapping of adjacent passes were studied. The analysis was carried out of savings per crop (maize, wheat, soybean, sugar beet and alfalfa) and the operations for each crop separately, based on the manufacturing technology applied to an exemplary property. Comparing the achieved level of savings, the application of guidance for the type of the most economically viable operations was found as well as the needed equipment level of guidance devices and management. In particular, the analysis involved the functional dependence of the economic savings in fuel and inputs for the operations such as mineral fertilizers distribution and chemical plant protection. The estimates for the degree of anticipated savings for operations related to the five analyzed crops are tabulated

Economic indicators of precision guidance in crop production in Agricultural Corporation Belgrade (PKB)

U ovom radu ispitan je stepen ušteda pri primeni najsavremenijih tehničkih sistema za satelitsko navođenje i automatsko upravljanje pri obavljanju poljoprivrednih operacija tokom cele sezone. Ogledno imanje bila je Poljoprivredna korporacija Beograd koja se prostire na oko 21000 hektara obradive površine. Analiziran je uticaj oblika parcele i pravca kretanja agregata pri kalkulisanju ušteda usled smanjenja preklopa susednih prohoda. Izvršena je analiza ušteda po kulturama (kukuruz, pšenica, soja, šećerna repa i detelina) i po operacijama za svaku kulturu pojedinačno, prema tehnologiji proizvodnje primenjenoj na oglednom imanju. Poređenjem ostvarenih stepena uštede zaključeno je pri kojim operacijama je primena navođenja ekonomski najopravdanija i koliki nivo opremljenosti uređajima za navođenje i upravljanje je potreban. Posebno je analizirana funkcionalna zavisnost ekonomskih ušteda u gorivu i inputima za operacije distribucije hraniva i zaštite biljaka. Tabelarno je data procena stepena svih očekivanih ušteda za operacije koje se odnose na pet analiziranih kultura.This paper examined the level of savings in the application of modern technical systems for satellite guidance and control over performing agricultural operations throughout the season. The exemplary property was Agricultural Corporation Belgrade (PKB), which covers about 21,000 hectares of arable land. The effects of plot shape and direction of movement of tractor-attachment units in calculating the savings from reduced overlapping of adjacent passes were studied. The analysis was carried out of savings per crop (maize, wheat, soybean, sugar beet and alfalfa) and the operations for each crop separately, based on the manufacturing technology applied to an exemplary property. Comparing the achieved level of savings, the application of guidance for the type of the most economically viable operations was found as well as the needed equipment level of guidance devices and management. In particular, the analysis involved the functional dependence of the economic savings in fuel and inputs for the operations such as mineral fertilizers distribution and chemical plant protection. The estimates for the degree of anticipated savings for operations related to the five analyzed crops are tabulated

Modeling the motion and mass quantity of fruit by rotating sizing machines

U ovom radu teoretski je analizirano kretanje i protok osam vrsta voća duž rotacionog kalibratora. Polazi se od diferencijalne jednačine kretanja voća na rotirajućem disku kalibratora. Razvijen je opšti model koji može biti primenjen za određivanje protoka za sve tipove rotacionih kalibratora. Analiza protoka obuhvatila je masu i protok kalibriranog voća. Uvedeni su novi iskustveni koeficijenti: koeficijent procentualnog iskorišćenja obima diska, koeficijent punjenja i koeficijent raspodele plodova. Posebno je istražen uticaj relativne brzine voća na kapacitet kalibratora. Za usvojene vrednosti navedenih koeficijenata ke = 0.7, kf = 1, kd = 0.5 dobijeni su rezultati koji se približno poklapaju sa do sada poznatim protocima voća na kalibratorima. Ustanovljeno je da protoci veoma variraju u zavisnosti od dijametra i mase voća. Količinski protok varira od 8949 plod/h za jabuku do 40157 plod/h za duboko zamrznutu malinu. Maseni protok varira od 229,1 kg/h za višnju do 2054,7 kg/h za jabuku.This paper analyzes theoretically the motion and mass quantity of eight fruit types, roundish in shape, along rotating sizing machines. Mathematical model of the motion of fruit on the rotating disc is solved in spherical coordinate system which is tied to the disc. The exact solution is simplified introducing assumptions that are do not significantly affect the accuracy of the solution. Starting from differential equation of fruit motion on a rotating disk of the sizing machine, all forces acting on fruit were determined as well as velocities and time necessary for fruit to reach the disk rim if found in some upper position on the cone. Mass quantity analysis comprised sized fruit mass and weight capacity. New empirical coefficients were introduced: extent ratio, feed ratio and distribution ratio. The results obtained for the adopted values ke = 0.7, kf = 1, kd = 0.5 coincide approximately with those reported to date for fruit mass quantity rate on sizing machines. It was found that mass quantity rates vary considerably, depending on fruit diameter and mass. Fruit numbers mass quantity ranges from 8949 crops/h for apple to 40,157 crops/h for deep frozen raspberry. Mass quantity varies from 229.1 kg/h for cherry to 2054.7 kg/h for apple

Modeling the motion and mass quantity of fruit by rotating sizing machines

U ovom radu teoretski je analizirano kretanje i protok osam vrsta voća duž rotacionog kalibratora. Polazi se od diferencijalne jednačine kretanja voća na rotirajućem disku kalibratora. Razvijen je opšti model koji može biti primenjen za određivanje protoka za sve tipove rotacionih kalibratora. Analiza protoka obuhvatila je masu i protok kalibriranog voća. Uvedeni su novi iskustveni koeficijenti: koeficijent procentualnog iskorišćenja obima diska, koeficijent punjenja i koeficijent raspodele plodova. Posebno je istražen uticaj relativne brzine voća na kapacitet kalibratora. Za usvojene vrednosti navedenih koeficijenata ke = 0.7, kf = 1, kd = 0.5 dobijeni su rezultati koji se približno poklapaju sa do sada poznatim protocima voća na kalibratorima. Ustanovljeno je da protoci veoma variraju u zavisnosti od dijametra i mase voća. Količinski protok varira od 8949 plod/h za jabuku do 40157 plod/h za duboko zamrznutu malinu. Maseni protok varira od 229,1 kg/h za višnju do 2054,7 kg/h za jabuku.This paper analyzes theoretically the motion and mass quantity of eight fruit types, roundish in shape, along rotating sizing machines. Mathematical model of the motion of fruit on the rotating disc is solved in spherical coordinate system which is tied to the disc. The exact solution is simplified introducing assumptions that are do not significantly affect the accuracy of the solution. Starting from differential equation of fruit motion on a rotating disk of the sizing machine, all forces acting on fruit were determined as well as velocities and time necessary for fruit to reach the disk rim if found in some upper position on the cone. Mass quantity analysis comprised sized fruit mass and weight capacity. New empirical coefficients were introduced: extent ratio, feed ratio and distribution ratio. The results obtained for the adopted values ke = 0.7, kf = 1, kd = 0.5 coincide approximately with those reported to date for fruit mass quantity rate on sizing machines. It was found that mass quantity rates vary considerably, depending on fruit diameter and mass. Fruit numbers mass quantity ranges from 8949 crops/h for apple to 40,157 crops/h for deep frozen raspberry. Mass quantity varies from 229.1 kg/h for cherry to 2054.7 kg/h for apple

Application of the latest generation hydrostatic transmissions in development of agriculture machines

U radu je data analiza postojećih tehničkih rešenja hidrostatskih transmisija samohodnih poljoprivrednih mašina, kao i mogući pravci razvoja i primene ove tehnologije na poljoprivrednim mašinama u budućnosti. Data je uporedna analiza tri sistema hidrostatske transmisije, sa posebnim osvrtom na prednosti i mane ovih sistema. Takođe je data analiza jednog rešenja za pogon poljoprivrednih mašina sa transportnim brzinama preko 40 km/h.This paper presents analysis of current technical solutions of hydrostatic transmissions of self propelled agricultural machines, as well as possible direction of development and appliance of this technology on agricultural machines in the future. Comparative analysis of three systems for hydrostatic transmission has been performed, with special attention of their advantages. This paper also includes analysis of one solution for hydrostatic transmission for reaching transport speed over 40 km/h