Design of electro-mechanical actuator for medium sized helicopter and a test platform for its testing and verification

This paper presents the design of an electro-mechanical actuator that is used for actuation of a medium sized helicopter. The designed actuator consists of a commercially available electro-mechanical cylinder EMC40 from Rexroth Bosch and a brushless DC motor EC45 from maxon motor. Cylinder and the motor are connected by a custom-made gearbox, which allows for their parallel axial mount. In addition to the actuator, the paper describes a test platform that can be used to emulate the forces generated by an actual helicopter. Designed test platform consists of a torsional spring and an AC motor with excentre. Frequency regulator is used to achieve the desired frequency of the force. Experimental results obtained by testing the designed actuator on the test platform are also given in the paper

Design of electro-mechanical actuator for medium sized helicopter and a test platform for its testing and verification

This paper presents the design of an electro-mechanical actuator that is used for actuation of a medium sized helicopter. The designed actuator consists of a commercially available electro-mechanical cylinder EMC40 from Rexroth Bosch and a brushless DC motor EC45 from maxon motor. Cylinder and the motor are connected by a custom-made gearbox, which allows for their parallel axial mount. In addition to the actuator, the paper describes a test platform that can be used to emulate the forces generated by an actual helicopter. Designed test platform consists of a torsional spring and an AC motor with excentre. Frequency regulator is used to achieve the desired frequency of the force. Experimental results obtained by testing the designed actuator on the test platform are also given in the paper

Analysis of K-ras gene codon 12 mutation in pancreatic tissue of patients with pancreatic cancer

Ovo istraživanje je imalo za cilj da se analizira prisustvo mutacije u kodonu 12 gena K-ras u pankreasnom tkivu pacijenata sa karcinomom pankreasa i da se proceni da li ova mutacija predstavlja potencijalni molekularni marker za karcinom pankreasa u srpskoj populaciji. Istraživanje je obuhvatilo analizu 40 uzoraka tkiva pankreasa pacijenata sa kliničkom dijagnozom karcinoma pankreasa. Prisustvo mutacije u kodonu 12 gena K-ras analizirano je metodom PCR-RFLP (polymerase chain reaction - restriction fragment length poly­morphism). Rezultati istraživanja ukazuju da je mutacija u kodonu 12 gena K-ras u tkivu pankreasa prisutna sa visokom učestalošću (66 %) kod pacijenata sa karcinomom pankreasa.The aim of this study was to analyze K-ras codon 12 mutation in the pancreatic tissue of Serbian patients with pancreatic cancer and assess whether the given mutation can be used as a molecular marker for this disease. The study was performed on pancreatic tissue samples obtained from 40 patients with clinical diagnosis of pancreatic cancer. The presence of K-ras codon 12 mutation was analyzed by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Our study showed that K-ras mutation is present with a high frequency (66%) in the pancreatic tissue of patients with pancretic cancer

Combined effect of GSTM1 gene deletion, GSTT1 gene deletion and MTHFR C677T mutation in male infertility

The aim of the study was to investigate the association between the GSTM1 and GSTT1 gene deletion and MTHFR C677T mutation and male infertility. The study has encompassed 52 infertile and 56 fertile males. Genotype distributions of GSTM1 and GSTT1 gene deletions and the MTHFR C677T mutation did not differ significantly among the analyzed groups, however, a difference in distribution of certain genotype combinations was observed. The obtained results indicate that carriers of double GSTM1/GSTT1 deletion and the MTHFR 677CC genotype are at higher risk of infertility than carriers of any other combination of genotypes (OR 3.5, 95%CI 0.68-18.30)

The influence of a project-based learning model in science and social studies on adoption of students' procedural knowledge

Training students to independently explore and analyze natural and social phenomena and processes is one of the more important and demanding tasks of science and social studies teaching. In order to successfully accomplish this formulated task, it is necessary for students to acquire the appropriate level of procedural knowledge, i.e. to know how to plan and conduct a research. Starting from the fact that the project work in the current reform of education in Serbia has become a mandatory teaching activity, the paper presents the results of an experimental research aimed at determining the efficiency of the project-based learning model in science and social studies in the process of acquiring procedural knowledge of students. The research was carried out on a sample of 72 students of the experimental group (three classes where the contents of the science and social studies was delivered according to the project-based learning model) and 70 students of the control group (three classes where the same contents was delivered through the usual group tasks) of the fourth grade of primary school. It turned out that, after the implementation of the experimental program, the achievements of the students of the experimental group improved in all three categories of procedural knowledge - the knowledge of different ways of collecting data, the knowledge of how to sort the research data, and the knowledge of how to present the research results

Uticaj genotipa i perioda laktacije na količinu, fizičke i hemijske osobine ovčijeg mleka

Two genotype of sheep have been utilized in the conduct of the experiment composed of 60 ewes from Pirot x Virtemberg as genotype 1 and 60 ewes of Improved Pirot as genotype 2. All the ewes were reared under identical conditions and without any differences in nutrition and management during the whole period under study. The collection of Milk sampling was done in morning and evening during periods (1, 2, 3) of lactation duration. The average lactation duration and average total milk of the two genotypes were very close and has a minimal difference of 0.467 day and 1.562 kg, in favor of genotype 2. The differences between genotypes were not significant (P>0,05). Regarding physical and chemical properties of milk for both genotypes, the difference were very minimal such as follows; viscosity Pa x s - 0.006, electrical conductivity Ω - 0.018, density kg/m3 -0,001, freezing, t 0C - 0.013, LD number - 0.028 total solids, % - 0.014, fat,% - 0,026, protein,% - 0.085, lactose,% - 0.038, ash,% - 0,021, acidity, 0SH - 0.209. The results indicated that the properties of milk for both genotypes were very near to each other. It can be interpreted that the breeds utilized in the experiment were comparable due to similar characteristics perhaps. The effect of genotype was very significant only for the % protein of the milk. The lactation periods were highly significant in all physical and chemical properties of milk.Istraživanja su obavljena kod dve rase ovaca i to 60 grla Pirotska x Virtemberg kao genotip 1 i 60 ovaca pirotske oplemenjene populacije, kao genotip 2. Sve životinje su držane u istim proizvodnim uslovima na farmi u Vrnjačkoj Banji. Prosečne vrednosti trajanja laktacije i mleka dobijenog u periodu laktacije su bile vrlo ujednačene, tako da nije utvrđen uticaj genotipa na ova svojstva. Takođe, razlike između fizičko hemijskih osobina mleka, u većini slučajeva su bile nesignifikantne. Uticaj genotipa kao fiksnog faktora je bio vrlo signifikantan samo kod sadržaja proteina u mleku ovaca (P (lt) 0.01). Međutim utvrđeno je da period laktacije ima vrlo signifikantan uticaj na sva posmatrana fizička i hemijska svojstva mleka

Victimisation and Justice in Intercultural Context in Serbia

During 2013, within the ALTERNATIVE project, Victimlogy Society of Serbia conducted an empirical research study with the aim to find out how people from three multiethnic communities in Serbia deal with interethnic conflicts in their everyday life and to identify both problems and positive experiences in solving them. It also analysed how victims are treated, how the security and justice are perceived by the citizens, and what is the place of restorative approaches in dealing with conflicts and security. The research was conducted in Backa Palanka, Bat, Prijepolje and Medveda. It consisted of qualitative and quantitative part, and it had a strong action dimension. After a brief description of the research methodology, we present main research findings related to the conflicts that have been evolving since 1990 between members of different ethnic groups in three multiethnic communities in Serbia, focusing on the prevalence and characteristics of victimisation and respondents' notions of justice, i.e. mechanisms suitable to achieve justice in the concrete cases of victimisation they experienced. In the conclusion we point out that respondents attribute high relevance to both formal and informal restorative approaches, suggesting the need of citizens in general, and victims in particular to actively participate in the process of conflict transformation and prevention of further victimisations

EFFICENCY OF ZEOLITE BASIS PREPARATION IN FATTENING LAMBS DIET

Abstract: The paper presents the results of a research on the impact of products based on natural zeolite on the production results of fattening lambs. The experiment involved two groups of lambs (the control -C and experimental -E groups), each consisting of 15 heads, for a period of 90 days. The meal was made from sheep milk, feed mixtures for fattening lambs and meadow hay. The test group lambs, unlike the ones from the control group, were given mixtures based on natural zeolite. Min-a-Zel S mixture (in the form of 25% composite) was fed to lambs from birth till their 14th day of life, directly into the mouth, once a day (before the morning feed), in the amount of 10 ml. Min-a-Zel Plus was given to them from their 15th day of life, together with the feed mixture (0.5%). Feeding was at will. The average weight of lambs at the end of the experiment, in accordance with the sequence of treatments (C:E) was 24.40:26.94 kg (P <0.01). Daily weight gain of lambs, during the experiment, was 229:256 g and in the experimental group it was by 27g or 11.79% higher (P <0.01). The test group lambs had a better utilization of dry matter, protein and energy, which justifies the use of products based on natural zeolite in fattening lambs

Application of Landsat-derived NDVI in monitoring and assessment of vegetation cover changes in Central Serbia

This paper evaluates the application of the Normalised Difference Vegetation Index (NDVI) in the monitoring and assessment of temporal vegetation cover changes (from 2006 to 2014) in three municipalities of Central Serbia: Topola, Jagodina and Kuršumlija. Additionally, special focus is placed on the analysis of the forest areas and the possible use of NDVI in the forest management sector. Results of the NDVI applied through Idrisi software identify all vegetation cover types and their typical values for presented case studies and observed periods. Obtained results for Serbian case studies indicate two major observations outlined for the investigated period. It was noticed that vegetation cover is experiencing a certain decrease, and that certain discrepancies exists between the NDVI and official forest area statistics for certain municipalities. The study outlines the positive outcomes of the applied remote sensing techniques, especially for southern Serbian municipalities where illegal logging activities are pronounced. Hence, this method proved very promising for countries performing national forest inventories, such as Serbia, providing local forest managers with several essential up-to-date information about vegetation cover changes on an annual basis. © 2019 Carpathian Journal of Earth and Environmental Sciences