Energy efficient engine sector combustor rig test program

Under the NASA-sponsored Energy Efficient Engine program, Pratt & Whitney Aircraft has successfully completed a comprehensive combustor rig test using a 90-degree sector of an advanced two-stage combustor with a segmented liner. Initial testing utilized a combustor with a conventional louvered liner and demonstrated that the Energy Efficient Engine two-stage combustor configuration is a viable system for controlling exhaust emissions, with the capability to meet all aerothermal performance goals. Goals for both carbon monoxide and unburned hydrocarbons were surpassed and the goal for oxides of nitrogen was closely approached. In another series of tests, an advanced segmented liner configuration with a unique counter-parallel FINWALL cooling system was evaluated at engine sea level takeoff pressure and temperature levels. These tests verified the structural integrity of this liner design. Overall, the results from the program have provided a high level of confidence to proceed with the scheduled Combustor Component Rig Test Program

Vibrational properties of alpha- and sigma-phase Fe-Cr alloy

Experimental investigation as well as theoretical calculations, of the Fe-partial phonon density-of-states (DOS) for nominally Fe_52.5Cr_47.5 alloy having (a) alpha- and (b) sigma-phase structure were carried out. The former at sector 3-ID of the Advanced Photon Source, using the method of nuclear resonant inelastic X-ray scattering, and the latter with the direct method [K. Parlinski et al., Phys. Rev. Lett. {78, 4063 (1997)]. The characteristic features of phonon DOS, which differentiate one phase from the other, were revealed and successfully reproduced by the theory. Various data pertinent to the dynamics such as Lamb-Mossbauer factor, f, kinetic energy per atom, E_k, and the mean force constant, D, were directly derived from the experiment and the theoretical calculations, while vibrational specific heat at constant volume, C_V, and vibrational entropy, S were calculated using the Fe-partial DOS. Using the values of f and C_V, we determined values for Debye temperatures, T_D. An excellent agreement for some quantities derived from experiment and first-principles theory, like C_V and quite good one for others like D and S was obtained.Comment: 4 pages, 3 figure

Magnetic properties of σ\sigma-FeCr alloy as calculated with the charge and spin self-consistent KKR(CPA) method

Magnetic properties of a $\sigma-$Fe$_{16}$Cr$_{14}$ alloy calculated with the charge and spin self- consistent Korringa-Kohn-Rostoker (KKR) and combined with coherent potential approximation (KKR-CPA) methods are reported. Non-magnetic state as well as various magnetic orderings were considered, i.e. ferromagnetic (FM) and more complex anti-parallel (called APM) arrangements for selected sublattices, as follows from the symmetry analysis. It has been shown that the Stoner criterion applied to non-magnetic density of states at the Fermi energy, $E_F$ is satisfied for Fe atoms situated on all five lattice sites, while it is not fulfilled for all Cr atoms. In FM and APM states, the values of magnetic moments on Fe atoms occupying various sites are dispersed between 0 and 2.5 $\mu_B$, and they are proportional to the number of Fe atoms in the nearest-neighbor shell. Magnetic moments of Cr atoms havin much smaller values were found to be coupled antiparallel to those of Fe atoms. The average value of the magnetic moment per atom was found to be $=0.55 \mu_B$ that is by a factor of 4 larger than the experimental value found for a $\sigma-$Fe$_{0.538}$Cr$_{0.462}$ sample. Conversely, admitting an anti- parallel ordering (APM model) on atoms situated on C and D sites, according to the group theory and symmetry analysis results, yielded a substantial reduction of to 0.20 $\mu_B$. Further diminution of to 0.15 $\mu_B$, which is very close to the experimental value of 0.14 $\mu_B$, has been achieved with the KKR-CPA calculations by considering a chemical disorder on sites B, C and D

Influence of the speed of downward semi-continuous casting on the crystal size and mechanical properties of recycled copper

In this study, the influence of the speed of downward semi-continuous casting on the crystal size and mechanical properties of recycled copper after casting and cold deformation was investigated. It was shown that the increase in the casting speed from 0,09 m / min to 0,22 m / min resulted in refinement of the macrostructure and reduction of the crystal cross-sectional area from 3,221 mm2 to 1,2 mm2, which resulted in an increase in microhardness after casting by 8 %, while in the state after cold working, an increase in microhardness by 3 % and ultimate tensile strength by 2,5 %

Characteristics of CuCrTiAl alloy after plastic deformation

The development of the automotive industry leads to the search for newer construction materials, but also those used in the production process. Although many types of joints are used in vehicles, resistance welds remain the dominant one. The commonly used alloy for welding caps (CuCrZr) is already well known and therefore newer alloys and technologies for their production are sought to increase service life, and thus reduce production costs. Precipitation hardening CuCrTiAl alloy was analysed in this article. After casting, CuCrTiAl alloy was subjected to cold and hot deformation and then tested for its usability. The obtained results confirmed the potential of this alloy to make electrodes for resistance welding

Characteristics of CuCrTiAl alloy after plastic deformation

The development of the automotive industry leads to the search for newer construction materials, but also those used in the production process. Although many types of joints are used in vehicles, resistance welds remain the dominant one. The commonly used alloy for welding caps (CuCrZr) is already well known and therefore newer alloys and technologies for their production are sought to increase service life, and thus reduce production costs. Precipitation hardening CuCrTiAl alloy was analysed in this article. After casting, CuCrTiAl alloy was subjected to cold and hot deformation and then tested for its usability. The obtained results confirmed the potential of this alloy to make electrodes for resistance welding

Comparison of Cholesterol and Glucose Levels between College-Aged Males and Females

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The Effects of a 15-Week Physical Activity Class on Health-Related Physical Fitness

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Two Protocols of Cryopreservation of Goat Semen with the Use of Computer-Assisted Semen Analysis System

The objective of the study was a comparison of two protocols of goat semen cryopreservation with the use of computer-assisted semen analysis system. Twenty ejaculates obtained with electroejaculation method were assessed. Each ejaculate was divided in half and frozen according to two protocols. In protocol I semen was centrifuged in order to remove its plasma and diluted in Tris buffer extender containing glucose, citric acid and glycerol with 20% addition of egg yolk. Protocol II did not include removal of plasma and the extender contained 1.5% egg yolk. It was shown that the removal of semen plasma improved motility of goat spermatozoa following freezing/thawing with respect to the following motility indicators: motility, average path velocity, amplitude of lateral head displacement at p p < 0.01. In conclusion, the removal of semen plasma through centrifugation improved motility properties of goat semen following the freezing/thawing procedure