Genetic Algorithm in Stability of Non-Homogeneous Slopes
In recent years, genetic algorithm search procedure has been used to locate the critical slip surface of homogeneous slopes. It has been found that genetic algorithm is a robust search technique which often gives global solution. In the present study, genetic algorithm has been used to locate the critical slip surface of non-homogeneous slope in conjunction with slope stability analysis method developed by Janbu (1973) for generalized slip surface. The results obtained from the present study have been compared with those available in the literature [Greco (1996) and Zolfaghari et al. (2005)]. The effect of various genetic algorithm parameters (population size, number of generations, crossover probability and mutation probability) on the solution has been studied. It has been found from the results that Janbu's method (1973) of stability analysis along with genetic algorithm as search procedure gives a better solution in terms of getting minimum factor of safety, compared to other methods.
THRUST LINE CRITERION IN EMBANKMENT STABILITY ANALYSIS
A METHOD OF ANALYSING THE STABILITY OF EMBANKMENTS IS DESCRIBED WHICH ACCOUNTS FOR THE INTER-SLICE FORCES AND SATISFIES FORCE AND MOMENT EQUILIBRIUM CONDITIONS. THE METHOD IS APPLICABLE TO ANY SHAPE OF SLIP SURFACE WITH OR WITHOUT A TENSION CRACK. EXPRESSIONS ARE GIVEN FROM WHICH THE POSITIONS OF THE LINES OF THRUST FOR TOTAL AND EFFECTIVE STRESS CAN BE OBTAINED. SOLUTIONS ARE GIVEN TO TWO SERIES OF PROBLEMS. IN THE FIRST SERIES THERE IS NO TENSION CRACK BUT VARIOUS SHAPES ARE ASSUMED FOR THE SHAPE OF THE SLIP SURFACE AND DIFFERENT ASSUMPTIONS MADE REGARDING THE SLOPES OF THE INTER-SLICE FORCES. HOWEVER, NONE OF THESE SOLUTIONS LEADS TO A SATISFACTORY POSITION FOR THE LINE OF THRUST FOR EFFECTIVE STRESS. IN THE SECOND SERIES A TENSION CRACK WITH WATER PRESSURE ACTING IN IT IS ASSUMED PRESENT. IT IS SHOWN THAT A SATISFACTORY THRUST LINE IS OBTAINED WHEN THE DEPTH OF THE TENSION CRACK IS TAKEN TO BE THE DEPTH OF ZERO ACTIVE EFFECTIVE STRESS AND THE SLOPE OF THE INTER-SLICE FORCES IS CONSTANT, EXCEPT FOR A REDUCTION AT THE UPPER END OF THE SLIP SURFACE. THE INCLUSION OF THE TENSION CRACK WITH WATER PRESSURE ACTING IN IT DOES NOT AFFECT THE VALUE OF THE FACTOR OF SAFETY IN THIS PROBLEM. /TRRL/
Novel polymeric hydrogel composites: Synthesis, physicochemical, mechanical and biocompatible properties
In this research study, novel hydrogel composite films were constructed using different ratios of poly (vinyl alcohol) (PVA)/kappa-carrageenan (KC) (PVA90/KC10%, PVA80/KC20%, PVA70/KC30%, PVA60/KC40%) crosslinked with glutaraldehyde (0.025%) and investigated their physicochemical characteristics such as mechanical, thermal, morphological, swelling behaviour, and cell viability. SEM and FTIR revealed that surface morphology changed to heterogeneous and the presence of molecular interaction among the polymers. PVA90KC10 and PVA60KC40 exhibited smaller and larger pores on surface respectively. The change in the proportion of PVA and KC also triggered the tensile strength (Ts) of the film and the highest Ts observed were 21.60 MPa for PVA60KC40. Moreover, the thermal analysis showed three-phase degradation, and an increase in KC40 concentration results inversely proportional to a decrease in the rate of thermal degradation. Further, swelling and in-vitro biodegradation study confirmed the enhanced perseverance of water uptake for PVA60KC40 (286%) due to pores structure of the hydrogel film and PVA and KC alone degraded faster as compare to other films results suggested higher concentration of PVA90KC10 showed lower degradation rate and highest for PVA60KC40 about 6% and 22% respectively. Further, the cell viability was studied with MTT assay method by using NIH3T3 and HEK-293 cells for biocompatibility study revealed NIH3T3 cells were more biocompatible than HEK-293 and cell viability percent for PVA60KC40 showed the highest cell attachment about 99%. Overall corroborating data obtained from the study attested to the average swelling, appreciable mechanical characters, good interaction between molecules, and cell viability of the constructed PVA/KC hydrogel film, these all characters pave to be used as a potential template for biomedical applications such as tissue engineering and drug delivery.