Thermal fatigue performance of integrally cast automotive turbine wheels

Fluidized bed thermal fatigue testing was conducted on 16 integrally cast automotive turbine wheels for 1000-10,000 (600 sec total) thermal cycles at 935/50 C. The 16 wheels consisted of 14 IN-792 + 1% Hf and 2 gatorized AF2-1DA wheels; 6 of the IN-792 + Hf wheels contained crack arrest pockets inside the blade root flange. Temperature transients during the thermal cycling were measured in three calibration tests using either 18 or 30 thermocouples per wheel. Thermal cracking based on crack length versus accumulated cycles was greatest for unpocketed wheels developing cracks in 8-13 cycles compared to 75-250 cycles for unpocketed wheels. However, pocketed wheels survived up to 10,000 cycles with crack lengths less than 20 mm, whereas two unpocketed wheels developed 45 mm long cracks in 1000-2000 cycles

Thermal fatigue and oxidation data of TAZ-8A and M22 alloys and variations

Thermal fatigue and oxidation data were obtained on 36 specimens, representing 18 distinct variations (including the base systems) of TAZ-8A and M22 alloys. Double-edge wedge specimens for these systems were cycled between fluidized beds maintained at 1088 C and 316 C with a 180 s immersion in each bed. The systems included alloys TAZ-8A, M22, and 16 variations of these alloys. Each alloy variation consisted of a unique composition with an alternation in the percentage of carbon (C1 and C2), molydenum (M1 and M2), tungsten (W1 and W2), columbium (CB1, CB2, and CB3), tantalium (T1, T2, and T3), or boron (B1, B2, and B3) present. All of the alloys showed little weight change due to oxidation compared with other alloys previously tested in fluidized beds. Only both C1 alloy variation specimens survived 3500 cycles without cracking in the small radius, although substantial cracks were present, emanating from the end notches which were used for holding the specimens

Thermal fatigue and oxidation data of oxide dispersion-strengthened alloys

Thermal fatigue and oxidation data were obtained 24 specimens representing 9 discrete oxide dispersion-strengthened alloy compositions or fabricating techniques. Double edge wedge specimens, both bare metal and coated for each systems, were cycled between fluidized beds maintained at 1130 C with a three minute immersion in each bed. The systems included alloys identified as 262 in hardness of HRC 38; 264 in hardness of HRC 38, 40 and 43; 265 HRC 39, 266 of HRC 37 and 40; 754; and 956. Specimens in the bare condition of 265 HRC 39 and 266 HRC 37 survived 6000 cycles without cracking on the small radius of the double edge wedge specimen. A coated specimen of 262 HRC 38, 266 HRC 37 and 266 HRC40 also survived 6000 cycles without cracking. A duplicate coated specimen of 262 HRC 38 alloy survived 5250 cycles before cracks appeared. All the alloys showed little weight change compared compared to alloys tested in prior programs

Time-Continuous Bell Measurements

We combine the concept of Bell measurements, in which two systems are projected into a maximally entangled state, with the concept of continuous measurements, which concerns the evolution of a continuously monitored quantum system. For such time-continuous Bell measurements we derive the corresponding stochastic Schr\"odinger equations, as well as the unconditional feedback master equations. Our results apply to a wide range of physical systems, and are easily adapted to describe an arbitrary number of systems and measurements. Time-continuous Bell measurements therefore provide a versatile tool for the control of complex quantum systems and networks. As examples we show show that (i) two two-level systems can be deterministically entangled via homodyne detection, tolerating photon loss up to 50%, and (ii) a quantum state of light can be continuously teleported to a mechanical oscillator, which works under the same conditions as are required for optomechanical ground state cooling.Comment: 4+4 pages, 4 figure

Computing marginal posterior densities of genetic parameters of a multiple trait animal model using Laplace approximation or Gibbs sampling

Two procedures for computing the marginal posterior density of heritabilities or genetic correlations, ie, Laplace’s method to approximate integrals and Gibbs sampling, are compared. A multiple trait animal model is considered with one random effect, no missing observations and identical models for all traits. The Laplace approximation consists in computing the marginal posterior density for different values of the parameter of interest. This approximation requires the repeated evaluation of traces and determinants, which are easy to compute once the eigenvalues of a matrix of dimension equal to the number of animals are determined. These eigenvalues can be efficiently computed by the Lanczos algorithm. The Gibbs sampler generates samples from the joint posterior density. These samples are used to estimate the marginal posterior density, which is exact up to a Monte-Carlo error. Both procedures were applied to a data set with semen production traits of 1957 Normande bulls. The traits analyzed were volume of the ejaculate, motility score and spermatozoa concentration. The Laplace approximation yielded very accurate approximations of the marginal posterior density for all parameters with much lower computing costs.Deux procédures de calcul de la densité marginale a posteriori des héritabilités et des corrélations génétiques, à savoir la méthode de Laplace pour l’approximation des intégrales et l’échantillonnage de Gibbs, sont comparées. Pour cela, nous considérons un modèle animal multicaractère avec un effet aléatoire, sans observations manquantes et avec un modèle identique pour chaque caractère. L’approximation de Laplace conduit au calcul de la densité marginale a posteriori pour différentes valeurs du paramètre qui nous intéresse. Cela nécessite l’évaluation répétée de traces et de déterminants qui sont simples à calculer une fois que les valeurs propres d’une matrice de dimension égale au nombre d’animaux ont été déterminées. Ces valeurs propres peuvent être calculées de manière efficace à l’aide de l’algorithme de Lanczos. L’échantillonnage de Gibbs génère des échantillons de la densité conjointe a posteriori. Ces échantillons sont utilisés pour estimer la densité marginale a posteriori, qui est exacte à une erreur de Monte Carlo près. Les deux procédures ont été appliquées à un fichier de données comportant les caractères de production de semence recueillies sur 1957 taureaux Normands. Les caractères analysés étaient le volume de l’éjaculat, une note de motilité et la concentration en spermatozoïdes. L’approximation laplacienne a permis une approximation très précise de la densité marginale a posteriori de tous les paramètres avec un coût de calcul beaucoup plus réduit

Displacement energy of unit disk cotangent bundles

We give an upper bound of a Hamiltonian displacement energy of a unit disk cotangent bundle $D^*M$ in a cotangent bundle $T^*M$, when the base manifold $M$ is an open Riemannian manifold. Our main result is that the displacement energy is not greater than $C r(M)$, where $r(M)$ is the inner radius of $M$, and $C$ is a dimensional constant. As an immediate application, we study symplectic embedding problems of unit disk cotangent bundles. Moreover, combined with results in symplectic geometry, our main result shows the existence of short periodic billiard trajectories and short geodesic loops.Comment: Title slightly changed. Close to the version published online in Math Zei

Superfluid drag of two-species Bose-Einstein condensates in optical lattices

We study two-species Bose-Einstein condensates in quasi two-dimensional optical lattices of varying geometry and potential depth. Based on the numerically exact Bloch and Wannier functions obtained using the plane-wave expansion method, we quantify the drag (entrainment coupling) between the condensate components. This drag originates from the (short range) inter-species interaction and increases with the kinetic energy. As a result of the interplay between interaction and kinetic energy effects, the superfluid-drag coefficient shows a non-monotonic dependence on the lattice depth. To make contact with future experiments, we quantitatively investigate the drag for mass ratios corresponding to relevant atomic species.Comment: 6 pages, 4 figures. Accepted in its original form but minor changes have been don

High-resolution remote thermography using luminescent low-dimensional tin-halide perovskites

While metal-halide perovskites have recently revolutionized research in optoelectronics through a unique combination of performance and synthetic simplicity, their low-dimensional counterparts can further expand the field with hitherto unknown and practically useful optical functionalities. In this context, we present the strong temperature dependence of the photoluminescence (PL) lifetime of low-dimensional, perovskite-like tin-halides, and apply this property to thermal imaging with a high precision of 0.05 {\deg}C. The PL lifetimes are governed by the heat-assisted de-trapping of self-trapped excitons, and their values can be varied over several orders of magnitude by adjusting the temperature (up to 20 ns {\deg}C-1). Typically, this sensitive range spans up to one hundred centigrade, and it is both compound-specific and shown to be compositionally and structurally tunable from -100 to 110 {\deg} C going from [C(NH2)3]2SnBr4 to Cs4SnBr6 and (C4N2H14I)4SnI6. Finally, through the innovative implementation of cost-effective hardware for fluorescence lifetime imaging (FLI), based on time-of-flight (ToF) technology, these novel thermoluminophores have been used to record thermographic videos with high spatial and thermal resolution.Comment: 25 pages, 4 figure