Interpolation and Approximation of Polynomials in Finite Fields over a Short Interval from Noisy Values

Motivated by a recently introduced HIMMO key distribution scheme, we consider a modification of the noisy polynomial interpolation problem of recovering an unknown polynomial $f(X) \in Z[X]$ from approximate values of the residues of $f(t)$ modulo a prime $p$ at polynomially many points $t$ taken from a short interval

Compatibility and stability of valsartan in a solid pharmaceutical formulation

Valsartan (VAL) is a highly selective blocker of the angiotensin II receptor that has been widely used in the treatment of hypertension. Active pharmaceutical ingredient compatibility with excipients (crospovidone, hypromellose, magnesium stearate, microcrystalline cellulose and titanium dioxide) is usually evaluated in solid pharmaceutical development. Compatibility and stability can be evaluated by liquid chromatography. Studies were performed using binary mixtures of 1:1 (w/w) VAL/excipient; samples were stored under accelerated stability test conditions (40 ºC at 75% relative humidity). The results indicate that VAL is incompatible with crospovidone and hypromellose, which reduced the VAL content and gave rise to new peaks in the chromatogram due to degradation products.Valsartana (VAL) é um bloqueador altamente seletivo do receptor da angiotensina II, que tem sido amplamente utilizado para o tratamento da hipertensão. Testes de compatibilidade com excipientes usualmente empregados em formulações sólidas são utilizados no desenvolvimento de formulações sólidas. Neste trabalho, realizaram-se testes utilizando misturas binárias na proporção 1:1 (m/m) de VAL/excipiente e as amostras foram armazenadas em condições de estabilidade acelerada (40 ºC em 75% de umidade relativa). Os resultados obtidos indicam a incompatibilidade de VAL com crospovidona e hipromelose, através da redução do teor de VAL e a presença de novos picos no cromatograma provenientes de produtos de degradação

The Quantum Transverse Field Ising Model on an Infinite Tree from Matrix Product States

We give a generalization to an infinite tree geometry of Vidal's infinite time-evolving block decimation (iTEBD) algorithm for simulating an infinite line of quantum spins. We numerically investigate the quantum Ising model in a transverse field on the Bethe lattice using the Matrix Product State ansatz. We observe a second order phase transition, with certain key differences from the transverse field Ising model on an infinite spin chain. We also investigate a transverse field Ising model with a specific longitudinal field. When the transverse field is turned off, this model has a highly degenerate ground state as opposed to the pure Ising model whose ground state is only doubly degenerate.Comment: 28 pages, 23 figures, PDFlate

Impedance-based analysis of harmonic resonances in HVDC connected offshore wind power plants

During the last years, the installation and planning of offshore wind farms using HVDC-links to transmit power onshore has increased. After the first HVDC connected offshore wind power plant of this type had been commissioned, the electrical harmonic resonance at the offshore AC grid was observed. The phenomenon leads to unwanted outages on both wind turbines and the HVDC transmission system. This paper aims to present the harmonic resonances in power-electronics dominated grids such as HVDC connected wind power plants. The study focuses on harmonic frequencies identification which are excited through the resonance phenomena between the elements of the offshore AC network including power converters. The paper presents a comparison of three different methodologies existing in the literature for harmonic resonance analysis including stability analysis. Moreover, we analyse the impact of the different power converter models application. The models and methods are validated in different test cases in order to determine the relationship of such resonances with respect to the grid topology.Postprint (author's final draft

Evaluation of Water Quality Indices: Use, Evolution and Future Perspectives

The evaluation of the quality of water bodies is of fundamental importance to the study and use of water. Aiming to improve the understanding of the phenomena which occur in these environments, several indices have been proposed over the years, using several statistical, mathematical and computational techniques. For this, it is necessary to know the variables which influence different water bodies. However, not all places are able to make the most diverse analyses due to the financial and sanitary conditions, which can promote greater expenses in treatment as well as make the limits of tolerance of the water quality higher. Nowadays, there is a need to formulate indices which can address climate change in its variables, making it even closer to reality. In this context, seeking to reduce the number of variables used, collection costs, laboratory analyses and a greater representativeness of the indices, multivariate statistical techniques and artificial intelligence are being increasingly used and obtaining expressive results. These advances contribute to the improvement of water quality indices, thus seeking to obtain one which portrays the various phenomena which occur in water bodies in a more rapid and coherent way with the reality and social context of water resources

AN EVALUATION OF THE SUBSTRATE EFFECT ON THE PERFORMANCE OF YSZ EB-PVD THERMAL BARRIER COATINGS

The substrate effect of eight different nickel base superalloys on the cyclic failure of thermal barrier coatings is studied. Substrates include six third generation superalloys, one second generation superalloy, and the alloy IN738. The thermal barrier coatings include yttria stabilized zirconia (YSZ) deposited by electron beam physical vapor deposition (EB-PVD), a (Ni,Pt) Al underlayer deposited by chemical vapor deposition (CVD) and grit blasted to provide a rough surface. The study conducted included the cyclic exposure of the specimens between 1100 ºC and room temperature. During the cyclic heat exposure, a thermally grown oxide (TGO) grew. After failure, the specimens were categorized according to the number of cycles obtained before failure. Later, specimens were examined by macroscopic and microscopic methods and chemical analysis was obtained by energy dispersive spectrometry (EDS). Specimens all failed by ratcheting along the YSZ/TGO interface showing little or no effect of the substrate compositions. Nevertheless, large differences in the cyclic lives existed among the third generation superalloys and between third and second generation superalloys, and single crystal vs. polycrystalline superalloys. Phase transformations were observed in the bond coat. Substrate elements such as Ta, Cr, and Co appear to play a role in the transformation of these phases. Bond coat deformation is attributed to the phase transformation, and the bond coat phase properties are attributed to chemical content. Carbon and tantalum play a role in the cyclic failure of the specimens