One of the common failure modes of thin cylindrical shell subjected external pressure is buckling. The buckling pressure of these shell structures are dominantly affected by the geometrical imperfections present in the cylindrical shell which are very difficult to alleviate during manufacturing process. In this work, only three types of geometrical imperfection patterns are considered namely (a...

The pumping of water from a sand box with a finer layer on the top was studied theoretically and experimentally. The sand box, saturated at its lower portion and initially in hydrostatic equilibrium, was pumped at constant rate. The results show that significant negative air pressure can be generated in the vadose zone during pumping. The negative air pressure increases quickly in the earlier s...

A long duration pumping test conducted over 151 days in a fractured sandstone and shale formation displays nonstandard drawdown response anomalous pressure diffusion, which cannot be properly interpreted using existing frameworks (e.g., homogeneous, double porosity, boundary conditions, fractal models). An alternative framework with simple geometry more complex hydraulic properties is thus prop...

Tunnelling through cities underlain by soft soil, commonly associated with soil movement around the tunnels and subsequent surface settlement. The predication of ground movement during the tunnelling and optimum support pressure could be based on analytical, empirical or the numerical methods. The commonly used Earth pressure balance (EPB) tunneling machines, uses the excavated soil in a pressu...

A review of the metabolic response (M) to hypoxia measured in different mammals shows that the critical ambient O2 pressure (Pc), is a linear function of the normoxic metabolic demand. Values for Pc at different metabolic loads may range from about 10 torr to close to 150 torr. However, the ratio M/Pc provides a useful index that seems to be independent of the metabolic demand. Critical ambient...

The 4-year drawdown of Horsetooth Reservoir, Colorado, for dam maintenance, provides a case study analog of vegetation response on sediment that might be exposed from removal of a tall dam. Early vegetation recovery on the exposed reservoir bottom was a combination of (1) vegetation colonization on bare, moist substrates typical of riparian zones and reservoir sediment of shallow dams and (2) a...

Experimental hydraulic heads and electrical (self-potential) signals associated with a pumping test were used in an inverse model to estimate the transmissivity distribution of a real aquifer. Several works reported in the literature show that there is a relatively good linear relationship between the hydraulic heads in the aquifer and electrical signals measured at the ground surface. In this ...

When facing the challenge of developing an individual that best fits its environment, nature demonstrates an interesting combination of two fundamentally different adaptive mechanisms: genetic evolution and phenotypic plasticity. Following numerous computational models, it has become the accepted wisdom that lifetime acclimation (e.g. via learning) smooths the fitness landscape and consequently...