Special Issue on Vacuum Technology. Trends in Dry Vacuum Pump.

Vacuum Gauge to Vacuum Pump Valve

Vacuum Energy and Universe in Special Relativity

The problem of cosmological constant and vacuum energy is usually thought of as the subject of general relativity. However, the vacuum energy is important for the Universe even in the absence of gravity , i.e. in the case when the Newton constant G is exactly zero, G = 0. We discuss the response of the vacuum energy to the perturbations of the quantum vacuum in special relativity, and find that...

CFD Simulation of a Dry Scroll Vacuum Pump Including Leakage Flows

One challenge for the numerical simulation of a dry scroll vacuum pump is the discretization of the chamber volume, which changes with time. In addition, the flow characteristics are very complex including the leakage flow caused by radial and axial gaps between the rotors and the housing. For engineers and designers it is imperative to understand the influence of such leakage flows on the effi...

A Case Study of Autoregressive Modelling and Order Selection for a Dry Vacuum Pump

Oil-free dry-vacuum pumps are prevalent in semiconductor plants worldwide today. The popularity of such pumps has grown over the years but little research has been done in the area of condition-monitoring of dry-vacuum pumps. Fault detection of one such pump through the use of AutoRegressive (AR) modelling technique and spectral analysis of vibration and acoustic data has been studied. The test...

On vacuum-vacuum amplitude and Bogoliubov coefficients

Even if the electromagnetic field does not create pairs, virtual pairs lead to the appearance of a phase in vacuum-vacuum amplitude. This makes it necessary to distinguish the inand out-solutions even when it is commonly assumed that there is only one complete set of solutions as, for example, in the case of a constant magnetic field. Then inand out-solutions differ only by a phase factor which...