Wyniki wyszukiwania - BazTech

Ograniczanie wyników

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Sortuj według:

Ogranicz wyniki do:

Partial least squares calibration and H-point standard addition methods for simultaneous determination of Al3+ and Fe3+ ions

Pouretedal H. R., Mahdavi M., Keshavarz M. H.

Chemia Analityczna

2009

Vol. 54, No. 6

1367-1381

Spectropholometric procedures based on partial least squares (PLS) and H-point standard addition (1IPSA) methods were proposed for the simultaneous determination of iron and aluminum using methyl thymol blue as a color reagent. In the PLS method, absorbance measurements were made at X = 520 nm in the time range 40-440 s with 5 s steps. HPSA method involved standard addition of Al(III) and absorbance measurement after 40 and 140 s. Absorbance measurements were performed in buffered solutions at pH = 4.0 and at temperature of 25°C. The proposed methods were applicable in the concentration ranges of 0.1-2.0 and 0.1-3.0 μg mL-1 of Al3+ and Fe3+, respectively. In the analysis of several synthetic samples of iron and aluminum percentage recovery was 90-110%. The contents of aluminum and iron in Portland ceme

Zaproponowano procedury jednoczesnego spektrofotometrycznego oznaczania żelaza i glinu w reakcji z błękitem metylowo-tymolowym, oparte na metodach cząstkowych najmniejszych kwadratów (PLS) i metodzie dodatków wzorca w punkcie - H. (HPSA). W metodzie PLS pomiary absorbancji wykonywano przy długości fali K = 520 nm w przedziale czasowym 40—440 s z krokiem co 5 s. HPSA wymagała standardowych dodatków AI(III) i pomiarów absorbancji po upływie czasu 40 i 140 s. Pomiary absorbancji prowadzono w roztworach buforu pH= 4,0 i w temperaturze 25°C. Metoda mogła być stosowana w zakresie stężeń 0,1-2,0 i 0,1-3,0 μg mL-1 odpowiednio dla Al3+ i Fe3+ Analiza szeregu syntetycznych mieszanin żelaza i glinu wykazała procentowy odzysk 90-110%. Przydatność zaproponowanych metod zademonstrowano oznaczając zawartość glinu i żelaza w próbkach cementu portlandzkiego.

A new method for computing the reliability of composite systems

Karbasian M., Mahdavi M.

Journal of Polish Safety and Reliability Association

2007

Vol. 1

199--203

This paper tries to represent a new method for computing the reliability of a system, which is arranged in series or parallel model. In this method we estimate life distribution function of whole system using the asymptotic Extreme Value (EV) distribution of Type I, or Gumbel theory. We use EV distribution in minimal mode, for estimate the life distribution function of series system and maximal mode for parallel system. All parameters also are estimated by Moments method. Reliability function and failure (hazard) rate and p-th percentile point of each function are determined. Other important indexes such as Mean Time to Failure (MTTF), Mean Time to repair (MTTR), for non-repairable and renewal systems in both of series and parallel structures will be computed.