We investigated the effect of different flow conditions on the transport of bacteriophage phiX174 in Memphis aquifer sand. Virus transport associated with a wetting front moving into an initially unsaturated horizontal sand column was experimentally compared with that observed under steady-state saturated vertical flow. Results obtained by sectioning the sand columns showthattotal (retained and...

The use of pumps linked in parallel or series in large scale pipe systems is usually inevitable, to meet the required head and discharge. Transient flow occurs following a pump failure in a pump group as a result of variations in the flow rate. This research is an investigation about waterhammer caused by one or more pump-switch off in a pump group when they are connected in parallel. The opera...

Ground water recharge is often estimated through the calibration of ground water flow models. We examine the nature of calibration errors by considering some simple mathematical and numerical calculations. From these calculations, we conclude that calibrating a steady-state ground water flow model to water level extremes yields estimates of recharge that have the same value as the time-varying ...

Harmonics have become an important issue in modern power systems. The widespread penetration of non-linear loads to emerging power systems has turned power quality analysis into an important operation issue under both steady state and transient conditions. This paper employs a Dynamic Harmonic Domain (DHD) based framework for dynamic harmonic analysis of VSC-HVDC systems. These systems are wide...

To this point we have emphasized steady flows, flows that do not change with time at any location in the pipeline system. In this brief chapter we will introduce two general categories of unsteady flow that we call transient flow. All transient flows are transitions, of long or short duration, from one steady flow state to another. Either of these end states may be the rest state. Each transien...

Single stage electrohydraulic flow control valves are currently not suitable in high flow rate and high frequency applications. This is due to the very significant flow induced forces and the power/force limitation of electromagnetic actuators that directly stokes the spool. An unstable valve has been proposed that can utilize the flow forces to achieve fast responses at high flow rate. In this...

In this paper, we model DCCP congestion control mechanism and RED as independent discrete-time systems using fluid-flow approximation. By interconnecting DCCP connections and RED routers, we model the entire network as a feedback system called DCCP/RED. We then analyze the steady state performance and the transient state performance of DCCP/RED. Specifically, we derive the packet transmission r...

This paper deals with a lumped-parameter dynamic simulation of a single-effect LiBr-H2O absorption chiller. In many studies the thermodynamic properties of LiBr-H2O solution were taken from some approximate relations causing the results to be somewhat inaccurate. These relations were used to solve simultaneous differential equations involving the continuity of species constituting the LiBr-H2O ...