Određivanje odstupanja izmjere promjera pomoću metode konačnih elemenata i eksperimenta

This study concerns experimental and numerical analysis on a one-sided bound workpiece on the lathe machine. Cutting force creates deflection on workpiece while turning process is on. Deflection quantity is estimated utilizing Laser Distance Sensor (LDS) with no contact achieved. Also diametral values are detected from different sides of workpiece after each turning operation. It is observed that diametral error differs due to the quantity of the deflection. Diametral error reached a peak where deflection reached a peak. Model which constituted finite elements is verified by experimental results. And also, facts which caused diametral error are determined.Ova studija bavi se eksperimentalnom i numeričkom analizom obratka učvršćenog s jedne strane na tokarskom stroju. Rezna sila izaziva savijanje radnog komada za vrijeme procesa tokarenja. Iznos progiba je ocijenjen korištenjem bezkontaktnog senzora za mjerenje udaljenosti (Laser Distance Sensor LDS). Također su određene vrijednosti promjera s različitih strana obratka nakon svake operacije tokarenja. Nađeno je da se odstupanje izmjere promjera razlikuje obzirom na iznos progiba. Odstupanje veličine promjera dostiže svoju najvišu vrijednost na mjestu gdje je progib najveći. Model koji se temelji na konačnim elementima je verificiran pomoću eksperimentalnih rezultata. Također su utvrđene činjenice koje uzrokuju odstupanje promjera

Određivanje odstupanja izmjere promjera pomoću metode konačnih elemenata i eksperimenta

This study concerns experimental and numerical analysis on a one-sided bound workpiece on the lathe machine. Cutting force creates deflection on workpiece while turning process is on. Deflection quantity is estimated utilizing Laser Distance Sensor (LDS) with no contact achieved. Also diametral values are detected from different sides of workpiece after each turning operation. It is observed that diametral error differs due to the quantity of the deflection. Diametral error reached a peak where deflection reached a peak. Model which constituted finite elements is verified by experimental results. And also, facts which caused diametral error are determined.Ova studija bavi se eksperimentalnom i numeričkom analizom obratka učvršćenog s jedne strane na tokarskom stroju. Rezna sila izaziva savijanje radnog komada za vrijeme procesa tokarenja. Iznos progiba je ocijenjen korištenjem bezkontaktnog senzora za mjerenje udaljenosti (Laser Distance Sensor LDS). Također su određene vrijednosti promjera s različitih strana obratka nakon svake operacije tokarenja. Nađeno je da se odstupanje izmjere promjera razlikuje obzirom na iznos progiba. Odstupanje veličine promjera dostiže svoju najvišu vrijednost na mjestu gdje je progib najveći. Model koji se temelji na konačnim elementima je verificiran pomoću eksperimentalnih rezultata. Također su utvrđene činjenice koje uzrokuju odstupanje promjera

Direct simulation for a homogenous gas

A probabilistic analysis of the direct simulation of a homogeneous gas is given. A hierarchy of equations similar to the BBGKY hierarchy for the reduced probability densities is derived. By invoking the molecular chaos assumption, an equation similar to the Boltzmann equation for the single particle probability density and the corresponding H-theorem is derived

Relationship between radiographic features and bone mineral density in elderly men

Lumbar disc degeneration is characterised radiologically by the presence of osteophytes, endplate sclerosis, and disc space narrowing. Our study was designed to assess anterior lumbar osteophytes, disc space narrowing, end plate sclerosis, and bone mineral density (BMD) in the lumbar vertebrae and femoral neck of elderly men. A total of 1000 men, aged between 71 and 90 years, were invited to participate in the study. BMD was assessed at the spine and femoral neck using dual energy X-ray absorptiometry (DXA). We examined the relationship with the degree of lumbar spinal and femoral neck deformity by using the Z-score. Lateral and anterioposterior spinal radiographs were evaluated for features of lumbar disc degeneration. The observers consisted of a consultant physical therapist, a radiologist, and anatomists who together studied the series of radiographs. Anterior lumbar osteophytes (grade 0–3), end-plate sclerosis, and disc space narrowing (grade 0–2) were evaluated. The Pearson correlation test was used to determine the association between radiographic features, the lumbar mineral density (LBMD), and femoral neck mineral density (FNBMD). In all, 90.6% of lumbar vertebral levels showed evidence of anterior osteophytes, 87.5% showed evidence of end plate sclerosis, and 68.2% of disc space narrowing. Additionally, there was a strong negative correlation in terms of age at the femoral neck, though not at the spine. On the other hand, there was a significant correlation between osteophyte grade and end plate sclerosis at the spine. In our study, the radiographic features of lumbar disc degeneration, anterior osteophytes, and end plate sclerosis were associated with an increase in BMD at the spine. (Folia Morphol 2010; 69, 3: 170-176

Spin-orbit-coupled Bose-Einstein-condensed atoms confined in annular potentials

A spin-orbit-coupled Bose-Einstein-condensed cloud of atoms confined in an annular trapping potential shows a variety of phases that we investigate in the present study. Starting with the non-interacting problem, the homogeneous phase that is present in an untrapped system is replaced by a sinusoidal density variation in the limit of a very narrow annulus. In the case of an untrapped system there is another phase with a striped-like density distribution, and its counterpart is also found in the limit of a very narrow annulus. As the width of the annulus increases, this picture persists qualitatively. Depending on the relative strength between the inter- and the intra-components, interactions either favor the striped phase, or suppress it, in which case either a homogeneous, or a sinusoidal-like phase appears. Interactions also give rise to novel solutions with a nonzero circulation.Comment: Final, slightly revised versio

Aerobic Stability and Nutritive Value of Low Dry Matter Maize Silage Treated with a Formic Acid-Based Preservative

Aerobic stability is one of the major problems of the ensiling process, especially in warm climates. Ashbell et al. (2002) have shown that at 30°C, the development of aerobic yeast and moulds in silages is most intensive. In Turkey all silages are susceptible to air penetration during storage and unloading with a large proportion of the silage spoiled and in extreme cases all the silage is spoiled. The purpose of the present work was to study the effects of formic acid-based preservative (FAB; Kemisile® 2000, Kemira Oyj-Industrial Chemicals, Finland) on the aerobic stability and nutritive value of maize silage

Improving the Aerobic Stability of Whole-Crop Cereal Silages

Whole-crop cereal silages, such as wheat, sorghum, and maize are susceptible to aerobic deterioration, especially in warm climates. This is because aerobic yeasts are the most active at 20-30°C (Ashbell et al., 2002). Therefore, it is very important to find suitable additives that inhibit fungi and protect the silage upon aerobic exposure. Propionibacterium acidipropionici is propionic acid bacteria (PAB), which produce propionic and acetic acid in silage. Results with these micro-organisms in laboratory studies were promising with regard to aerobic stability. The purpose of the present work was to study the effects of PAB, lactic acid bacteria (LAB) and combinations of PAB + LAB on the fermentation and aerobic stability of whole-crop cereal silages

Comparison of advanced cutting techniques on hardox 500 steel material and the effect of structural properties of the material

Purpose of this study is to determine the most advantageous cutting method for a better competition chance. By presenting high hardness, high strength and superior toughness Hardox 500 steel. This sample was cut by plasma, laser, wire erosion and abrasive water jet (AWJ) methods from advanced cutting technologies. By taking micro structure photos of surface of the sample cut by different cutting methods, effects of different cutting methods on metallurgical structure of material were compared

Damping properties of open pore aluminum foams produced by vacuum casting and NaCl dissolution process

In this study,damping ratios of 3 samples made of aluminum foam material, which have different-density pores, were calculated, the effects pore density on damping were examined. Experimental modal analysis method was used for examining of the effects of the pore density on damping. In experimental modal analysis method, frequency charts were obtained by driving to the sample with a hammer. Through these frequency charts, damping ratios of each 3 samples were calculated with ME’scope VES program. It was observed in calculated damping ratios that pore density has influences on damping; thus, damping accordingly increases as the number of pores increases. It is seen that critical damping constant decreases as the material structure changes in terms of volume and density

Damping properties of open pore aluminum foams produced by vacuum casting and NaCl dissolution process

In this study,damping ratios of 3 samples made of aluminum foam material, which have different-density pores, were calculated, the effects pore density on damping were examined. Experimental modal analysis method was used for examining of the effects of the pore density on damping. In experimental modal analysis method, frequency charts were obtained by driving to the sample with a hammer. Through these frequency charts, damping ratios of each 3 samples were calculated with ME’scope VES program. It was observed in calculated damping ratios that pore density has influences on damping; thus, damping accordingly increases as the number of pores increases. It is seen that critical damping constant decreases as the material structure changes in terms of volume and density