Seal Related Development Activities at EG/G

Seal related development activities including modeling, analysis, and performance testing are described for several current seal related projects. Among the current seal related projects are the following: high pressure gas sealing systems for turbomachinery; brush seals for gas path sealing in gas turbines; and tribological material evaluation for wear surfaces in sealing systems

Design considerations in mechanical face seals for improved performance. 2: Lubrication

The importance of sealing technology in our industrial, chemical-oriented society in regard to maintenance and environmental contamination is pointed out. It is stated that seal performance (leakage, life) is directly related to seal lubrication. Current thinking in regard to seal lubrication is reviewed; the effect of energy dissipation in the thin lubricating film separating the sealing faces is pointed out, and the results of vaporization due to heating are illustrated. Also, hydrodynamic lubrication is reviewed, and an inherent tendency for the seal to operate with angular misalignment is shown. Recent work on hydrostatic effects is summarized and the conditions for seal instability are discussed. Four different modes of seal lubrication are postulated with the mode type being a strong function of speed and pressure

Numerical analysis of nanostructures for enhanced light extraction from OLEDs

Nanostructures, like periodic arrays of scatters or low-index gratings, are used to improve the light outcoupling from organic light-emitting diodes (OLED). In order to optimize geometrical and material properties of such structures, simulations of the outcoupling process are very helpful. The finite element method is best suited for an accurate discretization of the geometry and the singular-like field profile within the structured layer and the emitting layer. However, a finite element simulation of the overall OLED stack is often beyond available computer resources. The main focus of this paper is the simulation of a single dipole source embedded into a twofold infinitely periodic OLED structure. To overcome the numerical burden we apply the Floquet transform, so that the computational domain reduces to the unit cell. The relevant outcoupling data are then gained by inverse Flouqet transforming. This step requires a careful numerical treatment as reported in this paper

Design considerations in mechanical face seals for improved performance. 1: Basic configurations

Basic assembly configurations of the mechanical face seal are described and some advantages associated with each are listed. The various forms of seal components are illustrated, and functions pointed out. The technique of seal pressure balancing and its application are described; and the concept of the PV factor, its different forms and limitations are discussed. Brief attention is given to seal lubrication since it is covered in detail in a companion paper. Finally, the operating conditions for various applications of low pressure seals (aircraft transmissions) are listed, and the seal failure mode of a particular application is discussed

Characterisation of the CAFOS linear spectro-polarimeter

Aims. This research note presents a full analysis of the CAFOS polarimeter mounted at the Calar Alto 2.2m telescope. It also provides future users of this mode with all necessary information to properly correct for instrumental effects in polarization data obtained with this instrument. Methods. The standard stars BD+59d389 (polarized) and HD14069 (unpolarized) were observed with CAFOS in November, 2010, using 16 half-wave plate angles. The linear spectropolarimetric properties of CAFOS were studied using a Fourier Analysis of the resulting data. Results. CAFOS shows a roughly constant instrumental polarization at the level of ~0.3% between 4000 and 8600 A. Below 4000 A the spurious polarization grows to reach ~0.7% at 3600 A. This instrumental effect is most likely produced by the telescope optics, and appears to be additive. The Wollaston prism presents a clear deviation from the ideal behavior. The problem is largely removed by the usage of at least 4 retarder plate angles. The chromatism of the half-wave plate causes a peak-to-peak oscillation of ~11 degrees in the polarization angle. This can be effectively corrected using the tabulated values presented in this paper. The Fourier analysis shows that the k!=0,4 harmonics are practically negligible between 3800 and 7400 A. Conclusions. After correcting for instrumental polarization and retarder plate chromatism, with 4 half-wave plate angles CAFOS can reach an rms linear polarization accuracy of about 0.1%.Comment: 5 pages, 5 figures, Accepted for publication in A&A (Research Note

On the GBM event seen 0.4 sec after GW 150914

In view of the recent report by Connaughton we analyse continuous TTE data of Fermi-GBM around the time of the gravitational wave event GW 150914. We find that after proper accounting for low count statistics, the GBM transient event at 0.4 s after GW 150914 is likely not due to an astrophysical source, but consistent with a background fluctuation, removing the tension between the INTEGRAL/ACS non-detection and GBM. Additionally, reanalysis of other short GRBs shows that without proper statistical modeling the fluence of faint events is over-predicted, as verified for some joint GBM-ACS detections of short GRBs. We detail the statistical procedure to correct these biases. As a result, faint short GRBs, verified by ACS detections, with significances in the broad-band light curve even smaller than that of the GBM-GW150914 event are recovered as proper non-zero source, while the GBM-GW150914 event is consistent with zero fluence.Comment: 13 pages, 12 figures, ApJL (acc.); subm. 2016 March 10, Apr 21 (1st rev.), May 13 (2nd rev), Jun 1 (3rd rev), and editorial changes by Jun 2 (4th rev), Jun 8 (5th rev): Our manuscript refers exclusively to arXiv:1602.03920.v3 since we had no prior access to arXiv:1602.03920.v4/5 (2016 May 31). Note that JG and HFY are not co-authors on arXiv:1602.03920.v4/