When fluid flow in a pipeline is suddenly halted, a pressure surge or wave is created within the pipeline. This phenomenon, called water hammer, can cause major damage to pipelines, including pipeline ruptures. In this paper, we model the problem of mitigating water hammer during valve closure by an optimal boundary control problem involving a nonlinear hyperbolic PDE system that describes the ...

In this chapter a general introduction of centrifugal compression systems is presented. The unstable surge phenomenon in compressors is discussed, as well as possible means to avoid or suppress this instability. From an assessment of the current state of the art in control-oriented modeling and identification, the research objectives are formulated. 1.1 General introduction The general topic of...

Prolactin is an anterior pituitary hormone necessary for fertility, pregnancy maintenance, lactation, and aspects of maternal behavior. In rodents, there is a surge of prolactin on the afternoon of proestrus, and a semi-circadian pattern of prolactin surges during early pregnancy, with a diurnal and nocturnal surge every day. Both of these patterns can be replicated in ovariectomized rats. A pr...

The rapid expansion of wind power generation has brought problems involving lightning strikes to the fore. Many such incidents have damaged not only the wind turbine that was actually struck, but also other turbines that were not. The phenomenon of surge invasion to the distribution line is categorized as “back-flow surge”. It has been reported that this back-flow surge sometimes burns out surg...

The proliferation of surge-protective devices and switch-mode power supplies has radically changed the surge environment in the low-voltage AC mains. Monitoring surge voltages has lost significance and can be misleading. Instead, surge currents should be monitored. The paper describes the performance of a silicon-based surge-protective device acting as a "magnet" for impinging surges in the pre...

There has been a surge of work on models for coupling surface-water with groundwater flows which is at its core the Stokes-Darcy problem, as well as methods for uncoupling the problem into subdomain, subphysics solves. The resulting (Stokes-Darcy) fluid velocity is important because the flow transports contaminants. The numerical analysis and algorithm development for the evolutionary transport...

It is well known that flow instabilities called rotating stall and surge may occur in non-cavitating turbomachines at flow rates smaller than design. Rotating stall is a local instability at the turbomachinery which is basically not dependent on the hydraulic system in which the turbomachine is installed. The stalled region rotates faster than impeller. Surge is a system instability in a hydrau...

A novel method for combining active surge control system (ASCS) and surge avoidance system (SAS) for a centrifugal compressor is presented. ASCS is a promising method to improve compressor operating area by stabilizing surge. However, this method is not applied yet in industrial compressors. Safety issue is considered in implementing the ASCS. A failure in ASCS may endanger the compressor by en...