Aluminium and its alloys represent very important group of structural materials. They have many applications in mechanical and civil engineering, and welding is considered to be one of the most important joining techniques. However, welding of aluminium has several issues, like high thermal conductivity and easy formation of oxide layer with high melting temperature. Recently, solid state friction stir welding process has been developed to overcome such issues, but it is not easily applicable in every situation. Therefore, welding of aluminium still greatly relies on arc welding. Among commonly used TIG and MIG processes, pulsed MIG (and its variants) are developed to fulfil requests regarding heat input and oxide layer removal during welding. This paper gives brief general overview of technical and technological aspects of these processes, and then more details regarding welding of widely used aluminium 5754 alloy with thickness of 4 mm. Comparison of relevant costs is given as well. All welds were made using digitally controlled equipment, while voltage and current were additionally measured. Based on evaluation of welds and calculated costs, conclusion regarding feasibility of each process is given.

Pneumatic conveying involves the transportation powder, granular and piece of material and is based on the phenomenon that at the appropriate speed of air in the pipeline, the solid particles are brought in the desired direction. If inlet air velocity is too high the material flow rate may be reduced, the power requirements will be excessive, and operating problems will be severe. Considering the advantages that air-slide conveyors can offer in relation to pneumatic conveying systems especially in terms of low power consumption and operating problems associated with abrasive particles, such as erosive wear of system components and degradation of friable particles. In this paper is presented design calculation of airslide conveyor in the thermal power plant.

In this era, big data applications including biomedical are becoming attractive as the data generation and storage is increased in the last years. The big data processing to extract knowledge becomes challenging since the data mining techniques are not adapted to the new requirements. In this study, we analyse the EEG signals for epileptic seizure detection in the big data scenario using Rotation Forest classifier. Specifically, MSPCA is used for denoising, WPD is used for feature extraction and Rotation Forest is used for classification in a MapReduce framework to correctly predict the epileptic seizure. This paper presents a MapReduce-based distributed ensemble algorithm for epileptic seizure prediction and trains a Rotation Forest on each dataset in parallel using a cluster of computers. The results of MapReduce based Rotation Forest show that the proposed framework reduces the training time significantly while accomplishing a high level of performance in classifications.

The progressive nature of glaucoma suggests it should be possible to detect structural changes such as retinal nerve fiber layer (RNFL) thickness loss before the condition becomes clinically apparent with visual field (VF) impairment. Therefore, the aim was to analyze RNFL thickness and VF changes in study groups with unilateral exfoliation syndrome (XFS), bilateral XFS and bilateral exfoliative glaucoma (XFG), and compare it with controls. The study included 114 subjects (228 eyes) divided into 4 groups according to the presence of exfoliation: 30 subjects with unilateral XFS (30 with clinically visible XFS and 30 fellow eyes), 24 subjects (48 eyes) with bilateral XFS, 28 (56 eyes) subjects with bilateral XFG, and control group (32 subjects). All subjects underwent VF and RNFL measurements after ophthalmologic examination. Both eyes of unilateral XFS (clinically -visible and fellow eye) showed positive correlation between Mean Defect (MD) and square root of Loss of Variance (sLV) and between MD and inferior quadrant RNFL thickness. In bilateral XFS and XFG, there was negative correlation between MD and inferior quadrant RNFL thickness. Inferior, superior and nasal quadrant RNFL thickness was lower in XFG group than in other groups. In bilateral XFS group, the inferior quadrant RNFL thickness was lower as compared with unilateral XFS group (in both eyes). The mean RNFL thickness negatively correlated with MD in bilateral XFS and XFG groups. In conclusion, structural changes before VF impairment have an important role in early detection of glaucoma in subjects at risk.

Forest productive attributes changes over time in native forests has been recognized as crucial challenge for management of uneven aged mixed forests in Bosnia and Herzegovina since middle of the last century. Experimental study has been carried out on set of experimental plots established in mixed stands on mountain Igman in central Bosnia. The most important forest productivity attributes changes based on repeated measures have been monitored over time. The aim of this research was to conduct the post-hoc power analysis for monitored forest attributes: basal area per ha (BA), growing stock per ha (GS) and current annual increment per ha (CAIv). Here are used repeated measures conduced on the 10 experimental plots in two types of mixed stands: fir-spruce and fir-spruce-beech plots (five plots per each type) measured in five (BA and GS) and four (CAIv) occasions in periods between 10–20 years. Analyses of variance (ANOVA) within and within-between repeated measures were applied and power analysis was performed. ANOVA within forest type over time showed highly significant differences for all attributes (α = 0.05, p < 0.001). Here, power analysis for comparison of stand attributes resulted in observed high power values ranged from 82% to 99% (very low risk of Type II errors). Then, ANOVA between two forest types over time showed different significances for forest attributes (α = 0.05, pBA = 0.25, pGS = 0.23 and pCAIv = 0.02). The risks of Type II errors were high for BA and GS (from 66% to 72%) while conclusions for CAIv could be accepted with very low risk (4%). So, the post-hoc power analysis of comparisons of stand attributes between forests types found low power for BA (28%) and GS (34%) and high power for CAIv (96%). These findings confirm importance of proper forest species composition planning in mixed stands related to highest wood productivity and other forest characteristics as biodiversity.

Atrial fibrillation is associated with systemic embolization and complications due to anticoagulant therapy. Radiofrequency ablation has been established as an effective and safe method for the treatment of atrial fibrillation. The aim of this study was to evaluate the effect of the size of the left atrium on the outcome of surgical radiofrequency ablation. Forty patients scheduled for elective mitral valve surgery and radiofrequency ablation were enrolled in the study. Group 1 consisted of patients with a left atrium diameter ≤5 cm and group 2 of patients with left atrium diameter >5 cm. The primary endpoint of the study was stable sinus rhythm 6 months postoperatively. At 6 months postoperatively, sinus rhythm was present in significantly more group 1 patients as compared with group 2 patients, i.e. 15 (75%) vs. 8 (40%), p=0.025. Multivariate analysis proved the size of the left atrium to be an independent predictor of the radiofrequency ablation outcome. Accordingly, the size of the left atrium was demonstrated to be an important predictor of the outcome of radiofrequency ablation for atrial fibrillation. A lower cut-off value of surgical reduction of the atria than previously reported should be considered in order to improve the radiofrequency ablation outcome.

AbstractObjectiveTo assess the image quality of coronary CT angiography (CCTA) for suspected acute coronary syndrome (ACS) outside office hours.MethodsPatients with symptoms suggestive of an ACS underwent CCTA at the emergency department 24 hours, 7 days a week. A total of 118 patients, of whom 89 (75 %) presented during office hours (weekdays between 07:00 and 17:00) and 29 (25 %) outside office hours (weekdays between 17:00 and 07:00, weekends and holidays) underwent CCTA. Image quality was evaluated per coronary segment by two experienced readers and graded on an ordinal scale ranging from 1 to 3.ResultsThere were no significant differences in acquisition parameters, beta-blocker administration or heart rate between patients presenting during office hours and outside office hours. The median quality score per patient was 30.5 [interquartile range 26.0–33.5] for patients presenting during office hours in comparison to 27.5 [19.75–32.0] for patients presenting outside office hours (p=0.043). The number of non-evaluable segments was lower for patients presenting during office hours (0 [0–1.0] vs. 1.0 [0–4.0], p=0.009).ConclusionImage quality of CCTA outside office hours in the diagnosis of suspected ACS is diminished.Key Points• Quality scores were higher for coronary-CTA during office hours. • There were no differences in acquisition parameters. • There was a non-significant trend towards higher heart rates outside office hours. • Coronary-CTA on the ED requires state-of-the-art scanner technology and sufficiently trained staff. • Coronary-CTA on the ED needs preparation time and optimisation of the procedure.