PID controller for microsatellite yaw-axis attitude control system using ITAE method

The need for effective design of satellite attitude control (SAC) subsystem for a microsatellite is imperative in order to guarantee both the quality and reliability of the data acquisition. A proportional-integral-derivative (PID) controller was proposed in this study because of its numerous advantages. The performance of PID controller can be greatly improved by adopting an integral time absolute error (ITAE) robust controller design approach. Since the system to be controlled is of the 4th order, it was approximated by its 2nd order version and then used for the controller design. Both the reduced and higher-order pre-filter transfer functions were designed and tested, in order to improve the system performance. As revealed by the results, three out of the four designed systems satisfy the design specifications; and the PD-controlled system without pre-filter transfer function was recommended out of the three systems due to its structural simplicity, which eventually enhances its digital implementation

Synthesis, Structural Elucidation and Antimicrobial Activity of Metal (II) Polypyridyl Complexes of 2-Amino-4-(Methylthio) Butanoic Acid

The interaction of selected biometals with dinitrogen donor ligand, 1,10-phennathroline (phen) and amino acid, 2-amino-4-(methylthio)butanoic acid (methionine; met) resulted in isolation of three mononuclear complexes. The prepared complexes were characterized by diverse techniques including elemental and spectroscopic analysis. From the analytical and spectral data, octahedral geometry was proposed to the synthesized metal (II) complexes. Bonding of the metal ion through N- and O- donor atoms of the ligands is revealed by infrared studies. The compounds showed moderate solubility in distilled water and in some common organic solvents. In vivo evaluation of the antimicrobial activities of the metal complexes showed improved inhibitory activity against some micro-organisms as compared to the ligands, with Co(II) and Cu(II) complexes showing the highest activities against the fungi. Keywords: antimicrobial; mixed ligands; amino acid; polypyridy

Chemical and physiochemical properties of fermented flour from refrigerated cassava root and sensory properties of its cooked paste

Efforts have been made to extend the poor shelf life of cassava roots through low-temperature storage like refrigeration, but the effects of this on lafun (fermented cassava flour) had not been investigated. This study determined the chemical composition of lafun obtained from cassava roots refrigerated for 1–3 weeks and the physicochemical and sensory properties of its cooked paste. Refrigerated storage (4°C) slightly reduced the whiteness of lafun and appearance of the cooked paste. Lafun from refrigerated cassava roots showed similar titratable acidity values (approx. 0.53%), but varying pH values (4.10–5.25). Carbohydrate was the major macro-component of lafun (approx. 84%), while calcium (40.13–60.11 mg/100 g), sodium (39.60–48.70 mg/100 g), magnesium (20.12–40.99 mg/100 g), and potassium (24.92–32.01 mg/100 g) were the major minerals. An increase in the swelling index and peak viscosity of lafun suggests an alteration in starch composition due to refrigeration. Cooked paste from lafun prepared from refrigerated cassava showed comparable quality with the control