Sveobuhvatno mjerenje i evaluacija sustava visokobrzinskog pogonskog vretena

Reducing the manufacturing time is the trend of high precision manufacturing, and the precision of a work-piece is very important for the manufacturing industry. The high-speed motorized spindle is the most critical part and becoming more widely used in the machine tool at present, and its precision may affect the overall performance of high-speed cutting. Most of the studies on high-speed cutting are focused on the cutting force, the vibration of the spindle and effects of the spindle’s thermal deformations; hence, how to roundly measure and objectively evaluate a high-speed spindle is an inevitable question. Because the comprehensive dynamic properties and evaluation system of spindles directly affect the cutting ability of the whole machine tool before they are manufactured. This paper presents a comprehensive measurement and evaluation system of a high-speed motorized spindle, which reflect the overall performance of motorized spindle and bases on an international standard.Smanjenje proizvodnog vremena tendencija je u visoko preciznoj proizvodnji, pri čemu je preciznost radnog komada vrlo važna u proizvodnoj industriji. Pri tome je visokobrzinsko pogonsko vreteno jedan od najkritičnijih dijelova koji se naširoko koristi u alatnim strojevima, pa njegova preciznost predstavlja važnog čimbenika u sveukupnoj izvedbi visokobrzinskog rezanja. Mnoge studije o visokobrzinskom rezanju su fokusirane na sile rezanja, vibraciju vretena kao i na efekte toplinske deformacije vretena; stoga, kako propisno mjeriti i objektivno evaluirati visokobrzinsko vreteno jedno je od neizbježnih pitanja. Jer sveobuhvatna dinamička svojstva i evaluacija sustava vretena izravno utječu na rezna svojstva cjelokupnog alatnog stroja, prije no što je proizveden. Ovaj rad prikazuje sveobuhvatno mjerenje i evaluaciju visokobrzinskog pogonskog vretena, koja se odražavaju na sveukupne odlike pogonskog vretena, a koja se bazirana na međunarodnim standardima

Fixed trace β\beta-Hermite ensembles: Asymptotic eigenvalue density and the edge of the density

In the present paper, fixed trace $\beta$-Hermite ensembles generalizing the fixed trace Gaussian Hermite ensemble are considered. For all $\beta$, we prove the Wigner semicircle law for these ensembles by using two different methods: one is the moment equivalence method with the help of the matrix model for general $\beta$, the other is to use asymptotic analysis tools. At the edge of the density, we prove that the edge scaling limit for $\beta$-HE implies the same limit for fixed trace $\beta$-Hermite ensembles. Consequently, explicit limit can be given for fixed trace GOE, GUE and GSE. Furthermore, for even $\beta$, analogous to $\beta$-Hermite ensembles, a multiple integral of the Konstevich type can be obtained.Comment: 16 page

B-vitamin consumption and the prevalence of diabetes and obesity among the US adults: population based ecological study

<p>Abstract</p> <p>Background</p> <p>The global increased prevalence of obesity and diabetes occurred after the worldwide spread of B-vitamins fortification, in which whether long-term exposure to high level of B vitamins plays a role is unknown. Our aim was to examine the relationships between B-vitamins consumption and the obesity and diabetes prevalence.</p> <p>Methods</p> <p>This population based ecological study was conducted to examine possible associations between the consumption of the B vitamins and macronutrients and the obesity and diabetes prevalence in the US population using the per capita consumption data from the US Economic Research Service and the prevalence data from the US Centers for Disease Control and Prevention.</p> <p>Results</p> <p>The prevalences of diabetes and adult obesity were highly correlated with per capita consumption of niacin, thiamin and riboflavin with a 26-and 10-year lag, respectively (<it>R</it>²= 0.952, 0.917 and 0.83 for diabetes, respectively, and <it>R</it>²= 0.964, 0.975 and 0.935 for obesity, respectively). The diabetes prevalence increased with the obesity prevalence with a 16-year lag (<it>R</it>²= 0.975). The relationships between the diabetes or obesity prevalence and per capita niacin consumption were similar both in different age groups and in male and female populations. The prevalence of adult obesity and diabetes was highly correlated with the grain contribution to niacin (<it>R</it>²= 0.925 and 0.901, respectively), with a 10-and 26-year lag, respectively. The prevalence of obesity in US adults during 1971-2004 increased in parallel with the increase in carbohydrate consumption with a 10-year lag. The per capita energy and protein consumptions positively correlated with the obesity prevalence with a one-year lag. Moreover, there was an 11-year lag relationship between per capita energy and protein consumption and the consumption of niacin, thiamin and riboflavin (<it>R</it>²= 0.932, 0.923 and 0.849 for energy, respectively, and <it>R</it>²= 0.922, 0.878 and 0.787 for protein, respectively).</p> <p>Conclusions</p> <p>Long-term exposure to high level of the B vitamins may be involved in the increased prevalence of obesity and diabetes in the US in the past 50 years. The possible roles of B-vitamins fortification and excess niacin consumption in the increased prevalence of obesity and diabetes were discussed.</p

Sveobuhvatno mjerenje i evaluacija sustava visokobrzinskog pogonskog vretena

Reducing the manufacturing time is the trend of high precision manufacturing, and the precision of a work-piece is very important for the manufacturing industry. The high-speed motorized spindle is the most critical part and becoming more widely used in the machine tool at present, and its precision may affect the overall performance of high-speed cutting. Most of the studies on high-speed cutting are focused on the cutting force, the vibration of the spindle and effects of the spindle’s thermal deformations; hence, how to roundly measure and objectively evaluate a high-speed spindle is an inevitable question. Because the comprehensive dynamic properties and evaluation system of spindles directly affect the cutting ability of the whole machine tool before they are manufactured. This paper presents a comprehensive measurement and evaluation system of a high-speed motorized spindle, which reflect the overall performance of motorized spindle and bases on an international standard.Smanjenje proizvodnog vremena tendencija je u visoko preciznoj proizvodnji, pri čemu je preciznost radnog komada vrlo važna u proizvodnoj industriji. Pri tome je visokobrzinsko pogonsko vreteno jedan od najkritičnijih dijelova koji se naširoko koristi u alatnim strojevima, pa njegova preciznost predstavlja važnog čimbenika u sveukupnoj izvedbi visokobrzinskog rezanja. Mnoge studije o visokobrzinskom rezanju su fokusirane na sile rezanja, vibraciju vretena kao i na efekte toplinske deformacije vretena; stoga, kako propisno mjeriti i objektivno evaluirati visokobrzinsko vreteno jedno je od neizbježnih pitanja. Jer sveobuhvatna dinamička svojstva i evaluacija sustava vretena izravno utječu na rezna svojstva cjelokupnog alatnog stroja, prije no što je proizveden. Ovaj rad prikazuje sveobuhvatno mjerenje i evaluaciju visokobrzinskog pogonskog vretena, koja se odražavaju na sveukupne odlike pogonskog vretena, a koja se bazirana na međunarodnim standardima

Voltammetric Behavior of o-Nitrophenol and Damage to DNA

The electrochemical behavior of o-nitrophenol was studied in detail with a glassy carbon electrode (GCE). The dependence of peak potential on pH indicated that equivalent electrons and protons were involved in the process of o-nitrophenol reduction. The interaction of o-nitrophenol with calf thymus DNA was investigated by adding DNA to the o-nitrophenol solution and by immobilizing DNA on GCE, respectively. The peak current decrement and peak potential shift in presence of DNA indicated that o-nitrophenol could interact with DNA. The result was demonstrated that the in situ DNA damage was detected by differential pulse voltammetry after the o-nitrophenol was electrochemically reduced

Liquid crystal films on curved surfaces: An entropic sampling study

The confining effect of a spherical substrate inducing anchoring (normal to the surface) of rod-like liquid crystal molecules contained in a thin film spread over it has been investigated with regard to possible changes in the nature of the isotropic-to-nematic phase transition as the sample is cooled. The focus of these Monte Carlo simulations is to study the competing effects of the homeotropic anchoring due to the surface inducing orientational ordering in the radial direction and the inherent uniaxial order promoted by the intermolecular interactions. By adopting entropic sampling procedure, we could investigate this transition with a high temperature precision, and we studied the effect of the surface anchoring strength on the phase diagram for a specifically chosen geometry. We find that there is a threshold anchoring strength of the surface below which uniaxial nematic phase results, and above which the isotropic fluid cools to a radially ordered nematic phase, besides of course expected changes in the phase transition temperature with the anchoring strength. In the vicinity of the threshold anchoring strength we observe a bistable region between these two structures, clearly brought out by the characteristics of the corresponding microstates constituting the entropic ensemble.Comment: 14 pages, 5 figure