The Influence of Vacuum Level on the Friction Force Acting on the Pneumatic Cylinder Sealing Ring

Presented in this paper are the results of measurement of friction force acting on the pneumatic cylinder sealing rings under high vacuum atmosphere. The investigations were conducted at relatively low levels of sliding speed of the sealing ring. Special device was constructed and implemented to facilitate this experiment. The results indicate the importance of the vacuum level on the friction force magnitude. Higher vacuum levels influence significant increase of friction force. Special phenomenon is the decreasing of friction force at higher sliding speeds of the sealing ring along the cylinder, under the constant vacuum level. Therefore, detailed examination of this phenomenon in the domain of high sliding speeds could yield interesting results

Intelligent design and optimization of machining fixtures

U radu je predstavljen integralni sustav za projektiranje i optimizaciju konstrukcije naprava za strojnu obradu. Dio sustava za optimizaciju omogućuje, s jedne strane, određivanje optimalnih pozicija elemenata za baziranje i stezanje kako bi se postigla potrebna točnost i kvaliteta obrađene površine izratka, a s druge strane, generiranje konstrukcije naprava bez kolizija. Dio sustava za projektiranje osigurava izbor pojedinih elemenata naprava na osnovi prethodno definiranih produkcijskih pravila. Prilagođeni kriteriji izbora definirani su za elemente za baziranje, elemente za stezanje, elemente za vođenje alata, elemente za podešavanje položaja alata, elemente tijela naprava, elemente za povezivanje i nadogradne elemente. Sustav je baziran na geometrijskim karakteristikama i karakterističnim obilježjima djela, kao i dodatnim informacijama o obradi i informacijama iz tehnološkog procesa. Sustav je razvijan za operacije tokarenja, bušenja, glodanja i brušenja koje se izvode na rotacijskim i prizmatičnim radnim predmetima. U radu su djelomično prikazani izlazni rezultati razvijenog sustava. Na kraju rada dani su odgovarajući zaključci i istaknuti mogući pravci daljih istraživanja.This work presents an integral system for machining fixture layout design and optimization. The optimization module of this system allows determination of optimal positions of locating and clamping elements, which provides required accuracy and surface quality, while at the same time guarantees design of collision-free fixtures. The design module performs selection of required fixture elements based on a set of predefined production rules. Adequate criteria for the selection of fixture elements are defined for locating, clamping, tool guiding, and tool adjustment elements, as well as for fixture body elements, connecting elements and add-on elements. The system uses geometry and feature workpiece characteristics, as well as the additional machining, and process planning information. It has been developed to accommodate machining processes of turning, drilling, milling, and grinding of rotational and prismatic workpieces. A segment of output results is also shown. Finally, conclusions are presented with directions for future investigation

BIOAKUMULACIONI I TRANSLOKACIONI POTENCIJAL VRSTE EUPATORIUM CANNABINUM L.

Cilj ovog rada bio je da se odrede koncentracije nekih metala (Ca, Mg, Mn, Fe, Zn, Ni, Cr) u zemljištu i vrsti Eupatorium cannabinum L. na jalovištu i flotacije rudnika DOO “Rudnik”. Dobijeni rezultati pokazuju da su koncentracije Cd, Pb, Cr, Ni i Cu u istraživanom zemljištu prelazile propisane maksimalno dozvoljene koncentracije, Cd, Pb, Cr, Ni, Cu i Zn granične, a Pb i Cu remedijacione vrednosti ovih metala u zemljištu saglasno uredbi i pravilniku Republike Srbije. Najveći sadržaj svih ispitivanih metala pokazao je list vrste E. canabinum u kojima su koncentracije Cu, Ni, Pb i Cd bile u nivou toksičnih koncentracija, a Cr iznad toksične koncentracije. Koren je sadržao više Mn, Ni, Fe i Cu od stabla, a stablo Zn, Cr, Ca, Mg, Pb i Cd od korena proučavane vrste. Na osnovu dobijenih rezultata možemo preporučiti upotrebu vrste E. canabinum u fitoekstrakciji ispitivanih metala iz zagađenih zemljišta, pre svega Zn, Cr, Ca, Mg, Pb i Cd.Publishe

Sex and age differences and outcomes in acute coronary syndromes

Background: There is conflicting information about sex differences in presentation, treatment, and outcome after acute coronary syndromes (ACS) in the era of reperfusion therapy and percutaneous coronary intervention. The aim of this study was to examine presentation, acute therapy, and outcomes of men and women with ACS with special emphasis on their relationship with younger age ( lt = 65 years). Methods: From January 2010 to June 2015, we enrolled 5140 patients from 3 primary PCI capable hospitals. Patients were registered according to the International Survey of Acute Coronary Syndrome in Transitional Countries (ISACS-TC) registry protocol (ClinicalTrials.gov: NCT01218776). The primary outcome was the incidence of in-hospital mortality. Results: The study population was constituted by 2876 patients younger than 65 years and 2294 patients older. Women were older than men in both the young (56.2 +/- 6.6 vs. 54.1 +/- 7.4) and old (74.9 +/- 6.4 vs. 73.6 +/- 6.0) age groups. There were 3421 (66.2%) patients with ST elevation ACS (STE-ACS) and 1719 (33.8%) patients without ST elevation ACS (NSTE-ACS). In STE-ACS, the percentage of patients who failed to receive reperfusion was higher in women than in men either in the young (21.7% vs. 15.8%) than in the elderly (35.2% vs. 29.6%). There was a significant higher mortality in women in the younger age group (age-adjusted OR 1.52, 95% CI: 1.01-2.29), but there was no sex difference in the older group (age-adjusted OR 1.10, 95% CI: 0.87-1.41). Significantly sex differences in mortality were not seen in NSTE-ACS patients. Conclusions: In-hospital mortality from ACS is not different between older men and women. A higher short-term mortality can be seen only in women with STEMI and age of 65 or less

Sex difference and intra-operative tidal volume: Insights from the LAS VEGAS study

BACKGROUND: One key element of lung-protective ventilation is the use of a low tidal volume (VT). A sex difference in use of low tidal volume ventilation (LTVV) has been described in critically ill ICU patients.OBJECTIVES: The aim of this study was to determine whether a sex difference in use of LTVV also exists in operating room patients, and if present what factors drive this difference.DESIGN, PATIENTS AND SETTING: This is a posthoc analysis of LAS VEGAS, a 1-week worldwide observational study in adults requiring intra-operative ventilation during general anaesthesia for surgery in 146 hospitals in 29 countries.MAIN OUTCOME MEASURES: Women and men were compared with respect to use of LTVV, defined as VT of 8 ml kg-1 or less predicted bodyweight (PBW). A VT was deemed 'default' if the set VT was a round number. A mediation analysis assessed which factors may explain the sex difference in use of LTVV during intra-operative ventilation.RESULTS: This analysis includes 9864 patients, of whom 5425 (55%) were women. A default VT was often set, both in women and men; mode VT was 500 ml. Median [IQR] VT was higher in women than in men (8.6 [7.7 to 9.6] vs. 7.6 [6.8 to 8.4] ml kg-1 PBW, P < 0.001). Compared with men, women were twice as likely not to receive LTVV [68.8 vs. 36.0%; relative risk ratio 2.1 (95% CI 1.9 to 2.1), P < 0.001]. In the mediation analysis, patients' height and actual body weight (ABW) explained 81 and 18% of the sex difference in use of LTVV, respectively; it was not explained by the use of a default VT.CONCLUSION: In this worldwide cohort of patients receiving intra-operative ventilation during general anaesthesia for surgery, women received a higher VT than men during intra-operative ventilation. The risk for a female not to receive LTVV during surgery was double that of males. Height and ABW were the two mediators of the sex difference in use of LTVV.TRIAL REGISTRATION: The study was registered at Clinicaltrials.gov, NCT01601223

Hemijsko suzbijanje viline kosice u lucerki

Parasitic flowering plants have recently come into focus of research interests as a result of their notable expansion and increasing damage that they are causing in agricultural fields. Damage caused by field dodder in alfalfa crops mainly includes reduced yield of fresh biomass and considerable decrease in seed production. Effective control of field dodder in alfalfa crops necessarily includes a number of preventive measures and procedures, as well as chemical control. The effectiveness of glyphosate, propyzamide, imazethapyr and diquat herbicides in controlling field dodder in alfalfa crops was tested in trials conducted in 2011. Pot and field trials were set up in an experimental field of the Institute of Field and Vegetable Crops in Novi Sad (location Rimski Šančevi) and in a private field at Popovići (vicinity of Mladenovac). In pot trials, two glyphosate application rates (288 and 360 g a.i. ha) achieved the highest effectiveness of 95% and 97.5%, respectively. Both application rates of propyzamide (1500 and 2000 g a.i. ha) had weak effectiveness (85% and 87%, respectively), while imazethapyr (150 g a.i. ha) was the weakest herbicide with 80% efficacy. In field trials at both locations, diquat (450 g a.i. ha) showed the best efficacy in controlling field dodder in alfalfa. The efficacy of all other treatments was weaker at Popovići with the following survival rates of field dodder plants: 25% (glyphosate, 288 g a.i. ha), 15% (glyphosate, 360 g a.i. ha), 79% (propyzamide, 1500 g a.i. ha), 70% (propyzamide, 2000 g a.i. ha) and 72% (imazethapyr, 150 g a.i. ha). At the location Rimski Šančevi, the same treatements resulted in around 1% remaining field dodder plants in alfalfa crop.U novije vreme problematika parazitskih cvetnica postaje sve aktuelnija i dobija veći istraživački prostor upravo zbog njihovog širenja i sve većih šteta koje nanose u poljoprivredi. Štete koje vilina kosica pravi u usevu lucerke se prvenstveno odnose na smanjenje prinosa zelene biomase i značajno smanjenu produkciju semena kod semenske lucerke. Efikasno suzbijanje viline kosice u usevu luceke podrazumeva niz preventivnih mera i postupaka, kao i hemijsku kontrolu. Ispitivanje efikasnosti herbicida (glifosat, propizamid, imazetapir i dikvat) u suzbijanju viline kosice u usevu lucerke urađeno je tokom 2011. godine. Ogledi su izvedeni u saksijama i u polju, na oglednom polju Instituta za ratarstvo i povrtarstvo u Novom Sadu (Rimski Šančevi) i na privatnoj parceli na lokalitetu Popovići (okolina Mladenovca). U ogledu sa saksijama, najbolju efikasnost je ispoljio glifosat u obe primenjene količine (288 i 360 g a.s. ha), 95% odnosno 97.5%. Efikasnost koju je ispoljio propizamid u obe količine primene (1500 i 2000 g a.s. ha) je bila slabija (85% odnosno 87%), dok je najslabiju efikasnost ispoljio imazetapir (150 g a.s. ha), 80%. U poljskim ogledima, na oba lokaliteta, dikvat (450 g a.s. ha) je ispoljio najbolju efikasnost u suzbijanju viline kosice. Na lokalitetu Popovići efikasnost ostalih tretmana je bila slabija, odnosno procenat preživelih jedinki viline kosice je bio: 25% (glifosat, 288 g a.s. ha), 15% (glifosat, 360 g a.s. ha), 79% (propizamid, 1500 g a.s. ha), 70% (propizamid, 2000 g a.s. ha) i 72% (imazetapir, 150 g a.s. ha). Na lokalitetu Rimski Šančevi, pri primeni istih tretmana, vilina kosica se zadržala na usevu sa oko 1%

The Modelling of Surface Roughness after the Ball Burnishing Process with a High-Stiffness Tool by Using Regression Analysis, Artificial Neural Networks, and Support Vector Regression

Surface roughness is an important indicator of the quality of the machined surface. One of the methods that can be applied to improve surface roughness is ball burnishing. Ball burnishing is a finishing process in which a ball is rolled over the workpiece surface. Defining adequate input variables of the ball burnishing process to ensure obtaining the required surface roughness is a typical problem in scientific research. This paper presents the results of experiments to investigate ball burnishing of AISI 4130 alloy steel with a high-stiffness tool and a ceramic ball. The experiments were conducted following a randomized full factorial design for different levels of input variables. The input variables included the initial arithmetic mean roughness (the initial surface roughness), the depth of ball penetration, the burnishing feed, and the burnishing ball diameter, while the output variable was the arithmetic mean roughness after ball burnishing (the final surface roughness). The surface roughness modeling was performed based on the experimental results, using regression analysis (RA), artificial neural network (ANN), and support vector regression (SVR). The regression model displayed large prediction errors at low surface roughness values (below 1 μm), but it proved to be reliable for higher roughness values. The ANN and SVR models have excellently predicted roughness across a range of input variables. Mean percentage error (MPE) during the experimental training research was 29.727%, 0.995%, and 1.592%, and MPE in the confirmation experiments was 34.534%, 1.559%, and 2.164%, for RA, ANN, and SVR, respectively. Based on the obtained MPEs, it can be concluded that the application of ANN and SVR was adequate for modeling the ball burnishing process and prediction of the roughness of the treated surface in terms of the possibility of practical application in real industrial conditions

Cardiovascular effects of environmental noise: Research in Serbia

Research on the cardiovascular effects of noise in Serbia started in the year 2002, including experimental studies on humans and epidemiological studies on the adult and children population of Belgrade and Pancevo. Experimental exposure to noise [L eq = 89 dB (A)] had a hypodynamic effect, significantly lowering the cardiac index, cardiac work, and pump performance (P 45 dB (A)] and quiet areas [(L night , 8h ≤ 45 dB (A)] were 23.6% and 17.5%, respectively. The adjusted odds ratio (OR) for hypertension of the exposed group was 1.58 (95% CI = 1.03 - 2.42, P = 0.038), where men living in quiet streets were taken as a reference category. Associations between road traffic noise and blood pressure were also investigated in 328 preschool children in Belgrade. The systolic blood pressure was significantly higher among children from noisy residences and kindergartens, compared to children from both quiet environments (97.30 ± 8.15 and 92.33 ± 8.64 mmHg, respectively, P < 0.01). As a continuation of the study on preschool children, investigations were also carried out on 856 school children, aged between seven and eleven years, in Belgrade. It was found that systolic pressure was significantly higher among children from noisy schools and quiet residences, compared to children from both quiet environments (102.1 ± 9,3 and 100.4 ± 10.4 mmHg, respectively, P < 0.01)

Flour - Bread '19 : Proceedings of the 10th International Congress Flour - Bread '19 and 12th Croatian Congress of Cereal Technologists Brašno - Kruh '19

Proceedings contains 3 Reviews, 8 Original research articles and 3 Professional articles presented at 10th International Congress Flour – Bread ’19 and 12th Croatian Congress of Cereal Technologists Brašno – Kruh ’1