324 research outputs found

    Ekonomska analiza razvoja rumunjske crne metalurgije

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    The ferrous metallurgy represents a traditional occupation, being extremely important for the national economy. Romania has gone through all the stages foreseen for the restructuring of this industry in compliance with the provisions of the European Council’s Decision (1999/582/EC) concerning the partnership for the EU adherence, which included a special chapter on ferrous metallurgy, the provisions of the Protocol no. 2 (ECSC), as well as with other significant normative acts subsequently enacted. Following the performed restructuring – privatizations, state allowances, liquidations, re-technologization – the activity of this sector has developed, still being under the potential of the Romanian metallurgic industry. Nowadays, the disadvantages relating to energy intensity and the increased need for imported raw materials are doubled by the difficulties generated by the global crisis.Crna metalurgija je tradicionalna djelatnost i veoma je značajna za nacionalno gospodarstvo. Rumunjska je prošla kroz sve faze predviđene za preustroj te industrije sukladno odredbama Odluke Europskog vijeća (1999/582/EZ) u svezi s partnerstvom za zajedništvo EU, što je obuhvaćalo i posebno poglavlje o crnoj metalurgiji, te sukladno odredbama Protokola br. 2 (EZUČ – Europska zajednica za ugljen i čelik) kao i drugim značajnim naknadno donesenim normativnim aktima, Nakon obavljena preustroja – privatizacije, državnih subvencija, likvidacija, retehnologizacije, razvila se djelatnost ove grane, ali još uvijek ispod mogućnosti rumunjske metalurške industrije. Danas su se zbog teškoća generiranih od globalne krize udvostručile nepovoljne okolnosti koje se odnose na energijski intenzivne djelatnosti i povećanu potrebu za sirovinama

    High order Fuchsian equations for the square lattice Ising model: χ(6)\chi^{(6)}

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    This paper deals with χ~(6)\tilde{\chi}^{(6)}, the six-particle contribution to the magnetic susceptibility of the square lattice Ising model. We have generated, modulo a prime, series coefficients for χ~(6)\tilde{\chi}^{(6)}. The length of the series is sufficient to produce the corresponding Fuchsian linear differential equation (modulo a prime). We obtain the Fuchsian linear differential equation that annihilates the "depleted" series Φ(6)=χ~(6)23χ~(4)+245χ~(2)\Phi^{(6)}=\tilde{\chi}^{(6)} - {2 \over 3} \tilde{\chi}^{(4)} + {2 \over 45} \tilde{\chi}^{(2)}. The factorization of the corresponding differential operator is performed using a method of factorization modulo a prime introduced in a previous paper. The "depleted" differential operator is shown to have a structure similar to the corresponding operator for χ~(5)\tilde{\chi}^{(5)}. It splits into factors of smaller orders, with the left-most factor of order six being equivalent to the symmetric fifth power of the linear differential operator corresponding to the elliptic integral EE. The right-most factor has a direct sum structure, and using series calculated modulo several primes, all the factors in the direct sum have been reconstructed in exact arithmetics.Comment: 23 page

    The Elaboration of Multiple Precessional Gear Theory and Modern Manufacturing Technology

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    The engineering complex study of the triad “gear-technology-transmission” has permitted to elaborate a new type of precessional transmissions with multicouple gear. In this paper, the authors present the mathematic model of the multicouple gear. A computer program for doing this it is also elaborated. It is shown a block-scheme of the algorithm of the program modules including the calculus modalities exposed in the paper

    Difference system for Selberg correlation integrals

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    The Selberg correlation integrals are averages of the products s=1ml=1n(xszl)μs\prod_{s=1}^m\prod_{l=1}^n (x_s - z_l)^{\mu_s} with respect to the Selberg density. Our interest is in the case m=1m=1, μ1=μ\mu_1 = \mu, when this corresponds to the μ\mu-th moment of the corresponding characteristic polynomial. We give the explicit form of a (n+1)×(n+1)(n+1) \times (n+1) matrix linear difference system in the variable μ\mu which determines the average, and we give the Gauss decomposition of the corresponding (n+1)×(n+1)(n+1) \times (n+1) matrix. For μ\mu a positive integer the difference system can be used to efficiently compute the power series defined by this average.Comment: 21 page

    On the functions counting walks with small steps in the quarter plane

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    Models of spatially homogeneous walks in the quarter plane Z+2{\bf Z}_+^{2} with steps taken from a subset S\mathcal{S} of the set of jumps to the eight nearest neighbors are considered. The generating function (x,y,z)Q(x,y;z)(x,y,z)\mapsto Q(x,y;z) of the numbers q(i,j;n)q(i,j;n) of such walks starting at the origin and ending at (i,j)Z+2(i,j) \in {\bf Z}_+^{2} after nn steps is studied. For all non-singular models of walks, the functions xQ(x,0;z)x \mapsto Q(x,0;z) and yQ(0,y;z)y\mapsto Q(0,y;z) are continued as multi-valued functions on C{\bf C} having infinitely many meromorphic branches, of which the set of poles is identified. The nature of these functions is derived from this result: namely, for all the 51 walks which admit a certain infinite group of birational transformations of C2{\bf C}^2, the interval ]0,1/S[]0,1/|\mathcal{S}|[ of variation of zz splits into two dense subsets such that the functions xQ(x,0;z)x \mapsto Q(x,0;z) and yQ(0,y;z)y\mapsto Q(0,y;z) are shown to be holonomic for any zz from the one of them and non-holonomic for any zz from the other. This entails the non-holonomy of (x,y,z)Q(x,y;z)(x,y,z)\mapsto Q(x,y;z), and therefore proves a conjecture of Bousquet-M\'elou and Mishna.Comment: 40 pages, 17 figure

    High-spin States in \u3csup\u3e191, 193\u3c/sup\u3eAu and \u3csup\u3e192\u3c/sup\u3ePt: Evidence for Oblate Deformation and Triaxial Shapes

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    High-spin states of 191, 193Au and 192Pt have been populated in the 186W(11B, xn) and 186W(11B, p4n) reactions, respectively, at a beam energy of 68 MeV and their γ decay was studied using the YRAST Ball detector array at the Wright Nuclear Structure Laboratory at Yale University. The level scheme of 193Au has been extended up to Iπ = 55/2+. New transitions were observed also in 191Au and 192Pt. Particle-plus-Triaxial-Rotor (PTR) and Total Routhian Surface (TRS) calculations were performed to determine the equilibrium deformations of the Au isotopes. The predictions for oblate deformations in these nuclei are in agreement with the experimental data. Development of nonaxial shapes is discussed within the framework of the PTR model

    Symphytum Species: A Comprehensive Review on Chemical Composition, Food Applications and Phytopharmacology

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    Symphytum species belongs to the Boraginaceae family and have been used for centuries for bone breakages, sprains and rheumatism, liver problems, gastritis, ulcers, skin problems, joint pain and contusions, wounds, gout, hematomas and thrombophlebitis. Considering the innumerable potentialities of the Symphytum species and their widespread use in the world, it is extremely important to provide data compiling the available literature to identify the areas of intense research and the main gaps in order to design future studies. The present review aims at summarizing the main data on the therapeutic indications of the Symphytum species based on the current evidence, also emphasizing data on both the e cacy and adverse e ects. The present review was carried out by consulting PubMed (Medline), Web of Science, Embase, Scopus, Cochrane Database, Science Direct and Google Scholar (as a search engine) databases to retrieve the most updated articles on this topic. All articles were carefully analyzed by the authors to assess their strengths and weaknesses, and to select the most useful ones for the purpose of review, prioritizing articles published from 1956 to 2018. The pharmacological e ects of the Symphytum species are attributed to several chemical compounds, among them allantoin, phenolic compounds, glycopeptides, polysaccharides and some toxic pyrrolizidine alkaloids. Not less important to highlight are the risks associated with its use. In fact, there is increasing consumption of over-the-counter drugs, which when associated with conventional drugs can cause serious and even fatal adverse events. Although clinical trials sustain the folk topical application of Symphytum species in musculoskeletal and blunt injuries, with minor adverse e ects, its antimicrobial potency was still poorly investigated. Further studies are needed to assess the antimicrobial spectrum of Symphytum species and to characterize the active molecules both in vitro and in vivo

    Solving Phase Retrieval with a Learned Reference

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    Fourier phase retrieval is a classical problem that deals with the recovery of an image from the amplitude measurements of its Fourier coefficients. Conventional methods solve this problem via iterative (alternating) minimization by leveraging some prior knowledge about the structure of the unknown image. The inherent ambiguities about shift and flip in the Fourier measurements make this problem especially difficult; and most of the existing methods use several random restarts with different permutations. In this paper, we assume that a known (learned) reference is added to the signal before capturing the Fourier amplitude measurements. Our method is inspired by the principle of adding a reference signal in holography. To recover the signal, we implement an iterative phase retrieval method as an unrolled network. Then we use back propagation to learn the reference that provides us the best reconstruction for a fixed number of phase retrieval iterations. We performed a number of simulations on a variety of datasets under different conditions and found that our proposed method for phase retrieval via unrolled network and learned reference provides near-perfect recovery at fixed (small) computational cost. We compared our method with standard Fourier phase retrieval methods and observed significant performance enhancement using the learned reference.Comment: Accepted to ECCV 2020. Code is available at https://github.com/CSIPlab/learnPR_referenc

    The Term Structure of Interest Rates and its Impact on the Liability Adequacy Test for Insurance Companies in Brazil

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    The Brazilian regulation for applying the Liability Adequacy Test (LAT) to technical provisions in insurance companies requires that the current estimate is discounted by a term structure of interest rates (hereafter TSIR). This article aims to analyze the LAT results, derived from the use of various models to build the TSIR: the cubic spline interpolation technique, Svensson's model (adopted by the regulator) and Vasicek's model. In order to achieve the objective proposed, the exchange rates of BM&FBOVESPA trading days were used to model the ETTJ and, consequently, to discount the cash flow of the insurance company. The results indicate that: (i) LAT is sensitive to the choice of the model used to build the TSIR; (ii) this sensitivity increases with cash flow longevity; (iii) the adoption of an ultimate forward rate (UFR) for the Brazilian insurance market should be evaluated by the regulator, in order to stabilize the trajectory of the yield curve at longer maturities. The technical provision is among the main solvency items of insurance companies and the LAT result is a significant indicator of the quality of this provision, as this evaluates its sufficiency or insufficiency. Thus, this article bridges a gap in the Brazilian actuarial literature, introducing the main methodologies available for modeling the yield curve and a practical application to analyze the impact of its choice on LAT.</p
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