A Review of the Erosion of Thermal Barrier Coatings.

The application of thermal barrier coatings (TBCs) to components with internal cooling in the hot gas stream of gas turbine engines has facilitated a steep increase in the turbine entry temperature and the associated increase in performance and efficiency of gas turbine engines. However, TBCs are susceptible to various life limiting issues associated with their operating environment including erosion, corrosion, oxidation, sintering and foreign object damage (FOD). This is a review paper that examines various degradation and erosion mechanisms of TBCs, especially those produced by electron beam physical vapour deposition (EB-PVD). The results from a number of laboratory tests under various impact conditions are discussed before the different erosion and FOD mechanisms are reviewed. The transitions between the various erosion mechanisms are discussed in terms of the D/d ratio (contact area diameter/column diameter), a relatively new concept that relates the impact size to the erosion mechanism. The effects of ageing, dopant additions and calciumâ  magnesiumâ  aluminaâ  silicates on the life of TBCs are examined. It is shown that while ageing increases the erosion rate of EB-PVD TBCs, ageing of plasma sprayed TBCs in fact lowers the erosion rate. Finally modelling of EB-PVD TBCs is briefly intr

Quantifying Absorption in the Transactional Interpretation

The Transactional Interpretation offers a solution to the measurement problem by identifying specific physical conditions precipitating the non-unitary `measurement transition' of von Neumann. Specifically, the transition occurs as a result of absorber response (a process lacking in the standard approach to the theory). The purpose of this Letter is to make clear that, despite recent claims to the contrary, the concepts of `absorber' and `absorber response,' as well as the process of absorption, are physically and quantitatively well-defined in the transactional picture. In addition, the Born Rule is explicitly derived for radiative processes.Comment: Final version, accepted in International Journal of Quantum Foundation

Ultra-low vibration pulse-tube cryocooler stabilized cryogenic sapphire oscillator with 10^-16 fractional frequency stability

A low maintenance long-term operational cryogenic sapphire oscillator has been implemented at 11.2 GHz using an ultra-low-vibration cryostat and pulse-tube cryocooler. It is currently the world's most stable microwave oscillator employing a cryocooler. Its performance is explained in terms of temperature and frequency stability. The phase noise and the Allan deviation of frequency fluctuations have been evaluated by comparing it to an ultra-stable liquid-helium cooled cryogenic sapphire oscillator in the same laboratory. Assuming both contribute equally, the Allan deviation evaluated for the cryocooled oscillator is sigma_y = 1 x 10^-15 tau^-1/2 for integration times 1 < tau < 10 s with a minimum sigma_y = 3.9 x 10^-16 at tau = 20 s. The long term frequency drift is less than 5 x 10^-14/day. From the measured power spectral density of phase fluctuations the single side band phase noise can be represented by L_phi(f) = 10^-14.0/f^4+10^-11.6/f^3+10^-10.0/f^2+10^-10.2/f+ 10^-11.0 for Fourier frequencies 10^-3<f<10^3 Hz in the single oscillator. As a result L_phi approx -97.5 dBc/Hz at 1 Hz offset from the carrier.Comment: 8 pages, 10 figures, presented at European Frequency and Time Forum, ESTEC, Noordwijk, Netherland, April 11-16th 2010 accepted in IEEE Trans. on Micro. Theory & Technique

New Distribution Records for Mosquitoes in Michigan (Diptera: Culicidae)

(excerpt) Since the late 1940\u27s very little information has appeared in the literature dealing with the geographical distribution of mosquitoes in Michigan. The earliest attempt at establish- ing a comprehensive list of species was made by Irwin (1941) who catalogued 43 species by county. A survey by Pederson (1947) resulted in the collection of 48 species and provided the most extensive distribution list of mosquitoes in Michigan. Recent studies by Newson et al. (1975), McGroarty et al. (1976) and Grimstad (1977) have contributed several new distribution and state records. Prompted by the 1975 St. Louis encephalitis outbreak in Michigan, and a lack of current information on the species of mosquitoes in Isabella County, a survey of mosquitoes was conducted in the Mount Pleasant area

Fractionation of human immune γ-globulin

Equine and bovine serum proteins have recently been fractionated by means of a physical method utilizing an electrophoretic adaptation of the principles of the Clusius column (l-4), first described and tested by Kirkwood (5) and Nielsen (6). The method of electrophoresis-convection has now been applied to the fractionation of human γ-globulin. The γ-globulin was prepared by ethanol fractionation (7) from the plasma of individuals hyperimmunized to Hemophilus pertussis organisms. The resulting fractions of γ-globulin have been characterized electrophoretically, and the protective antibody activity and agglutinin titer have been measured