Correlation between Surface Roughness Characteristics in CO2 Laser Cutting of Mild Steel

CO2 laser oxygen cutting of mild steel is widely used industrial application. Cut surface quality is a very important characteristic of laser cutting that ensures an advantage over other contour cutting processes. In this paper mathematical models for estimating characteristics of surface quality such as average surface roughness and ten-point mean roughness in CO2 laser cutting of mild steel based on laser cutting parameters were developed. Empirical models were developed using artificial neural networks and experimental data collected. Taguchi’s orthogonal array was implemented for experimental plan. From the analysis of the developed mathematical models it was observed that functional dependence between laser cutting parameters, their interactions and surface roughness characteristics is complex and non-linear. It was also observed that there exist region of minimal average surface roughness to ten-point mean roughness ratio. The relationship between average surface roughness and ten-point mean roughness was found to be nonlinear and can be expressed with a second degree polynomial

Grain yield of maize hybrids at different plant densities

Field trials with 12 maize hybrids belonging to FAO maturity groups 500, 600 and 700 were established under the agro environmental conditions of Smederevo in 2010 and 2011 to analyse grain yield and moisture content at different plant densities. The hybrids were sown in two independent trials in the two years at 51,000 and 62,000 plants ha-1, respectively, in a randomised block design with three replications. More favourable maize growing conditions i.e. more moderate air temperatures during the growing season, a more even distribution of precipitation and more rainy days were recorded in 2010 than in 2011, which had much lower precipitation amounts, particularly during July and August i.e. critical development stages (flowering and fertilization) of these hybrids. Grain yield of all maize hybrids was higher in 2010, mostly as the result of greater amounts of precipitation and their more even distribution during the growing season. In both years, significantly higher grain yields were obtained by FAO 600 maize hybrids. Grain yield in 2010 was significantly higher at the higher plant density in FAO 500 hybrids, as opposed to FAO 600 hybrids, which showed no significant difference in grain yield across plant densities. Grain moisture content at harvest did not significantly differ between plant densities in either year. Somewhat higher values for grain moisture at harvest in 2010 were recorded for FAO 600 hybrids. In 2011, there were no significant differences in grain moisture content among hybrids, nor between plant densities, mostly due to the very low amount of precipitation in the second part of the growing season

Implementation of immunohistochemistry on frozen ear notch tissue samples in diagnosis of bovine viral diarrhea virus in persistently infected cattle

<p>Abstract</p> <p>Background</p> <p>Bovine viral diarrhea is a contagious disease of domestic and wild ruminants and one of the most economically important diseases in cattle. Bovine viral diarrhea virus belongs to the genus <it>Pestivirus</it>, within the family <it>Flaviviridae</it>. The identification and elimination of the persistently infected animals from herds is the initial step in the control and eradication programs. It is therefore necessary to have reliable methods for diagnosis of bovine viral diarrhea virus. One of those methods is immunohistochemistry. Immunohistochemistry on formalin fixed, paraffin embedded tissue is a routine technique in diagnosis of persistently infected cattle from ear notch tissue samples. However, such technique is inappropriate due to complicated tissue fixation process and it requires more days for preparation. On the contrary, immunohistochemistry on frozen tissue was usually applied on organs from dead animals. In this paper, for the first time, the imunohistochemistry on frozen ear notch tissue samples was described.</p> <p>Findings</p> <p>Seventeen ear notch tissue samples were obtained during the period 2008-2009 from persistently infected cattle. Samples were fixed in liquid nitrogen and stored on -20°C until testing. Ear notch tissue samples from all persistently infected cattle showed positive results with good section quality and possibility to determinate type of infected cells.</p> <p>Conclusions</p> <p>Although the number of samples was limited, this study indicated that immunohistochemistry on formalin fixed paraffin embedded tissue can be successfully replaced with immunohistochemistry on frozen ear notch tissue samples in diagnosis of persistently infected cattle.</p

Modeling and Simulated Annealing Optimization of Surface Roughness in CO2 Laser Nitrogen Cutting of Stainless Steel

This paper presents a systematic methodology for empirical modeling and optimization of surface roughness in nitrogen, CO2 laser cutting of stainless steel . The surface roughness prediction model was developed in terms of laser power , cutting speed , assist gas pressure and focus position by using The artificial neural network ( ANN ) . To cover a wider range of laser cutting parameters and obtain an experimental database for the ANN model development, Taguchi 's L27 orthogonal array was implemented in the experimental plan. The developed ANN model was expressed as an explicit nonlinear function , while the influence of laser cutting parameters and their interactions on surface roughness were analyzed by generating 2D and 3D plots . The final goal of the experimental study Focuses on the determinationof the optimum laser cutting parameters for the minimization of surface roughness . Since the solution space of the developed ANN model is complex, and the possibility of many local solutions is great, simulated annealing (SA) was selected as a method for the optimization of surface roughness

Selection of the most suitable non-conventional machining processes for ceramics machining by using MCDMs

Selection of the most suitable non-conventional machining process (NCMP) for a ceramics machining represents a multi-criteria decision making (MCDM) problem. This paper describes the application of relatively novel MCDM methods for selecting the most suitable NCMP for the ceramics machining. By applying WASPAS and COPRAS methods, ten NCMPs (alternatives) were ranked based on the ten criteria. Comparison of obtained ranking performances with other MCDM methods used by previous researchers was carried out in order to demonstrate WASPAS and COPRAS applicability and capability for non-conventional machining process selection. [Projekat Ministarstva nauke Republike Srbije, br. ON174004 i br. TR35034

MULTI-OBJECTIVE OPTIMISATION OF LASER CUTTING USING CUCKOO SEARCH ALGORITHM

Determining of optimal laser cutting conditions for improving cut quality characteristics is of great importance in process planning. This paper presents multi-objective optimisation of the CO2 laser cutting process considering three cut quality characteristics such as surface roughness, heat affected zone (HAZ) and kerf width. It combines an experimental design by using Taguchi’s method, modelling the relationships between the laser cutting factors (laser power, cutting speed, assist gas pressure and focus position) and cut quality characteristics by artificial neural networks (ANNs), formulation of the multiobjective optimisation problem using weighting sum method, and solving it by the novel meta-heuristic cuckoo search algorithm (CSA). The objective is to obtain optimal cutting conditions dependent on the importance order of the cut quality characteristics for each of four different case studies presented in this paper. The case studies considered in this study are: minimisation of cut quality characteristics with equal priority, minimisation of cut quality characteristics with priority given to surface roughness, minimisation of cut quality characteristics with priority given to HAZ, and minimisation of cut quality characteristics with priority given to kerf width. The results indicate that the applied CSA for solving the multi-objective optimisation problem is effective, and that the proposed approach can be used for selecting the optimal laser cutting factors for specific production requirements

The Effect of Nitrogen Nutrition and Sowing Density on the Proportion of Class I Grains in Malting Barley

Abstract: Grain classification is the most important barley quality criterion. According to EBC regulations, barley is classified into three classes, depending on grain thickness (Class I: &gt;2.5 mm, Class II: from 2.2 to 2.5 mm and Class III &lt;2.2 mm). Highquality malting barley should have at least 90 % of Class I grains. The objective of this study was to examine the proportion of Class I grains in five spring barley cultivars grown at three different sowing densities (300, 400 and 500 germinating seeds m -2 ) and three N fertilization rates (50, 80 and 100 kg N ha -1 ) during three growing seasons. The highest proportion of Class I grains was obtained at a density of 300 seeds m -2 in all years of study. Increasing N rates induced a reduction in the proportion of Class I grains. A highly significant difference was observed between the highest N rate and the control without topdressing (50 kg N ha -1 ) and the treatment with 80 kg N ha -1

The importance of reactive agility tests in differentiating adolescent soccer players

The ability to differentiate the elite from nonelite athletes is not clearly defined. We investigated level differences in speed, change of direction speed (CODS), and reactive agility in a group of trained adolescent soccer players. A total of 75 adolescent male soccer players (aged 14–19 years) were recruited. The players were grouped based on the level of play to elite, sub-elite, and amateur players. Players were tested for 5-, 10- and 20-m sprints, CODS, and reactive agility tests (RAT). Elite players had faster reaction movement time during RAT with live opponent stimuli (p ≤ 0.01) compared to sub-elite and amateur players. Moreover, elite players showed a faster time during light stimuli (p ≤ 0.01) but only compared to amateur players. The times for 5-m and 10-m sprint groups did not differ (p > 0.05). The results demonstrated that the skilled players (elite and sub-elite) performed better in reactive agility tests, speed, and COD speed compared to amateur players. Additionally, we can conclude that total and reaction time in the agility test with live opponent stimuli can be a significant factor that differentiates between adolescent soccer players considering their level

Benefits of Strength Training for Elderly Women // Dobrobiti treninga snage za žene treće životne dobi

The aging process is associated with loss of skeletal muscle mass and increase in intramuscular fat, the latter also defined as muscle attenuation. Muscle weakness, termed sarcopenia and dynapenia, is a normal age-related phenomenon, occurring at a rate of 1% to 5% annually from the age of 30. This rate means that given typical patterns of physical activity, a 70-year-old woman could have 50% to 70% less strength than she had at age 30.  Contrary to long held beliefs, the muscles of elderly women (i.e. aged 65 years and older) continue to be adaptable, even into the extremes of old age, particularly if their muscles are significantly overloaded during training. Therefore, effective strengthening practices must be employed to maintain the highest level of function and achieve optimal aging in elderly women. Done regularly (2-3 times a week), strength training preserve bone density, independence and vitality with age. In addition, strength training also has the ability to reduce the risk of osteoporosis and the signs and symptoms of numerous chronic diseases such as heart disease, arthritis and type 2 diabetes, while also improving sleep and reducing depression. Finally, though muscle strength has been recognized as an important predictor for reduced functional performance, emerging evidence suggests that muscle power (the product of force time velocity or the rate of performing work) is highly effective to elicit substantial improvements in maximal mechanical muscle function (rapid force generation, muscle power and muscle strength) and in functional performance in old and very old women