Wyniki wyszukiwania - BazTech

Ograniczanie wyników

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Sortuj według:

Ogranicz wyniki do:

HPLC determination of enantiomeric thiazolidine-2-carboxylic acid on chiral stationary phase with pre-column derivatization

Zhang Y., Peng Q., Zeng H., Yao S, Zhang Y., Song H.

Acta Chromatographica

2013

Vol. 25, no. 2

287--296

A new high-performance liquid chromatography (HPLC) method has been developed and validated for determination of enantiomeric purity of thiazolidine-2-carboxylic acid within a short run time of less than 10 min. The method was based on pre-column derivatization of thiazolidine-2-carboxylic acid with aniline, and complete separation of enantiomers has been achieved on a Chiralcel OD-H analytical column (250 × 4.6 mm) using n-hexane-isopropanol (85:15 v/v) as mobile phase at a flow rate of 1.0 mL min-1 under UV and optical rotation (OR) detection. Detection wavelength was set at 254 nm. Then the effects of mobile phase and temperature on enantioselectivity were further evaluated. The method was validated with respect to precision, accuracy, linearity, limit of detection (LOD), limit of quantification (LOQ), and robustness. The recoveries were between 98.5 and 101.3% with percentage relative standard deviation less than 1.16%. The LOD and LOQ for the aniline derivatives of (+)-thiazolidine-2-carboxylic acid were 4.9 and 16.4 μg mL-1 and for the aniline derivatives (−)-thiazolidine-2-carboxylic acid were 5.1 and 17.2 μg mL-1, respectively.

H2 /H.infinity. control for linear systems with variance constraints: the state estimation feedback case.

Wang Z., Zeng H., Unbehauen H.

Systems Science

1998

Vol. 24, nr 3

29-47

In this paper, we consider the problem of designing H.infinity. controllers for linear continuous- and discrete-time systems with upper bound constraints on the steady-state variances. The feedback is based on the state estimation. The goal of this problem is to design the state estimation feedback controller such that 1) the steady-state variance of each state is not more than the individual prespecified upper bound, and 2) the H.infinity. norm of the transfer function from disturbance inputs to state estimate outputs meets the prespecified upper bound constraint, simultaneously. An algebraic matrix equation approach is developed to solve the problem addressed. Both the existence conditions and the explicit expression of desired controllers are derived, and illustrative simulation examples are used to demonstrate the applicability of the proposed design procedure in a manipulator control problem.