Sensorless load torque estimation and passivity based control of buck converter fed DC motor.

Passivity based control of DC motor in sensorless configuration is proposed in this paper. Exact tracking error dynamics passive output feedback control is used for stabilizing the speed of Buck converter fed DC motor under various load torques such as constant type, fan type, propeller type, and unknown load torques. Under load conditions, sensorless online algebraic approach is proposed, and it is compared with sensorless reduced order observer approach. The former produces better response in estimating the load torque. Sensitivity analysis is also performed to select the appropriate control variables. Simulation and experimental results fully confirm the superiority of the proposed approach suggested in this paper.

Effect of keratin-gelatin and bFGF-gelatin composite film as a sandwich layer for full-thickness skin mesh graft in experimental dogs.

Skin grafts are indicated when there is a major loss of skin. Full-thickness skin graft is an ideal choice to reconstruct defect of irregular surface that is difficult to immobilize. Full-thickness mesh grafts can be applied to patch large skin defect when there is less donor site in extensively traumatized and burned surgical patients. The concept of using natural biomaterials such as keratin, basic fibroblast growth factor is slowly gaining popularity in the field of medical research to achieve early healing. The main objective of this study is to evaluate the efficacy of gelatin conjoined with keratin processed from the poultry feather and commercially available basic fibroblast growth factor (bFGF) as a sandwich layer in promoting the viability of full-thickness skin mesh grafts. The efficacy was assessed from the observation of clinical, bacteriological, and histopathological findings in three groups of experimental dogs. The clinical observations such as color, appearance and discharge, and hair growth were selected as criteria which indicated good and early acceptance of graft in keratin-gelatin (group II). On bacteriological examination, Staphylococcus aureus and Proteus was identified in few animals. Histopathological study of the patched graft revealed early presences of hair follicles; sebaceous gland, and normal thickness of the epidermis in keratin-gelatin in group II treated animals compared with other group (group I-control, group III-bFGF-gelatin).