Optimal Controller and Filter Realisations using Finite-precision, Floating- point Arithmetic.

The problem of reducing the fragility of digital controllers and filters implemented using finite-precision, floating-point arithmetic is considered. Floating-point arithmetic parameter uncertainty is multiplicative, unlike parameter uncertainty resulting from fixed-point arithmetic. Based on first- order eigenvalue sensitivity analysis, an upper bound on the eigenvalue perturbations is derived. Consequently, open-loop and closed-loop eigenvalue sensitivity measures are proposed. These measures are dependent upon the filter/ controller realization. Problems of obtaining the optimal realization with respect to both the open-loop and the closed-loop eigenvalue sensitivity measures are posed. The problem for the open-loop case is completely solved. Solutions for the closed-loop case are obtained using non-linear programming. The problems are illustrated with a numerical example

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

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

Quantum electric-dipole liquid on a triangular lattice

Geometric frustrations and quantum mechanical fluctuations may prohibit the formation of long-range ordering even at the lowest temperature, and therefore liquid-like ground states could be expected. A good example is the quantum spin liquid in frustrated magnets that represents an exotic phase of matter and is attracting enormous interests. Geometric frustrations and quantum fluctuations can happen beyond magnetic systems. Here we propose that quantum electric-dipole liquids, analogs to quantum spin liquids, could emerge in frustrated dielectrics where antiferroelectrically coupled small electric dipoles reside on a triangular lattice. The quantum paraelectric hexaferrite BaFe12O19, in which small electric dipoles originated from the off-center displacement of Fe3+ in the FeO5 bipyramids constitute a two-dimensional triangular lattice, represents a promising candidate to generate the anticipated electric-dipole liquid. We present a series of experimental evidences, including dielectric permittivity, heat capacity, and thermal conductivity measured down to 66 mK, to reveal the existence of a nontrivial ground state in BaFe12O19, characterized by itinerant low-energy excitations with a small gap, to which we interpret as an exotic liquid-like quantum phase. The quantum electric-dipole liquids in frustrated dielectrics open up a fresh playground for fundamental physics and may find applications in quantum information and computation as well.Comment: 13 pages, 6 figure

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

NOK/STYK1 interacts with GSK-3β and mediates Ser9 phosphorylation through activated Akt

AbstractNOK (also known as STYK1) has been identified as an oncogene. However, its biochemical and biological activities as a molecular regulator are poorly defined. In the present study, we report that NOK overexpression led to enhanced phosphorylation of GSK-3β at its Ser9 residue via Akt phosphorylation at Thr308. NOK could make complexes with both Akt and GSK-3β. Moreover, the expression levels of NOK, p-Akt(Thr308) and p-GSK-3β(Ser9) were positively correlated in cancerous and non-cancerous breast cell lines. Thus, our data identified a novel functional molecular complex formed by NOK, Akt and GSK-3β that may relay a NOK-directed tumourigenic cascade.Structured summary of protein interactionsGSK3B physically interacts with NOK and Akt by anti tag coimmunoprecipitation (View interaction).GSK3B physically interacts with NOK by anti tag coimmunoprecipitation (View interaction)

Characterizing random-singlet state in two-dimensional frustrated quantum magnets and implications for the double perovskite Sr2_2CuTe1−x_{1-x}Wx_{x}O6_6

Motivated by experimental observation of the non-magnetic phase in the compounds with frustration and disorder, we study the ground state of the spin-$1/2$ square-lattice Heisenberg model with randomly distributed nearest-neighbor $J_1$ and next-nearest-neighbor $J_2$ couplings. By using the density matrix renormalization group (DMRG) calculation on cylinder system with circumference up to $10$ lattice sites, we identify a disordered phase between the N\'eel and stripe magnetic phase with growing $J_2 / J_1$ in the presence of strong randomness. The vanished spin-freezing parameter indicates the absent spin glass order. The large-scale DMRG results unveil the size-scaling behaviors of the spin-freezing parameter, the power-law decay of average spin correlation, and the exponential decay of typical spin correlation, which all agree with the corresponding behavior in the one-dimensional random singlet (RS) state and characterize the RS nature of this non-magnetic state. The DMRG simulation also opens new insight and opportunities for characterizing a class of non-magnetic states in two-dimensional frustrated magnets with disorder. We also compare with existing experiments and suggest more measurements for understanding the spin-liquid-like behavior in the double perovskite Sr$_2$CuTe$_{1-x}$W$_{x}$O$_6$.Comment: 11 pages,10 figure