A Check List of Maine Local Histories

A Check List of Maine Local Histories. Compiled by Almer J. Houston. Listing of Town Histories, Regimental Histories, County Histories, County Atlases, State Histories, State Atlases, Historical Societies, Collections of Historical and Genealogical Magazines, Ecclesiastical Histories and Statutes and Session Laws. A.J. Huston, 92 Exchange Street, Portland, Me., 1915.https://digitalcommons.usm.maine.edu/me_collection/1009/thumbnail.jp

Significant elastic anisotropy in Ti1−x_{1-x}Alx_xN alloys

Strong compositional-dependent elastic properties have been observed theoretically and experimentally in Ti$_{1-x}$Al$_x$ N alloys. The elastic constant, C$_{11}$, changes by more than 50% depending on the Al-content. Increasing the Al-content weakens the average bond strength in the local octahedral arrangements resulting in a more compliant material. On the other hand, it enhances the directional (covalent) nature of the nearest neighbor bonds that results in greater elastic anisotropy and higher sound velocities. The strong dependence of the elastic properties on the Al-content offers new insight into the detailed understanding of the spinodal decomposition and age hardening in Ti$_{1-x}$Al$_x$N alloys.Comment: 3 figures, 3 page

Learning control of hearing aid parameter settings

In a hearing aid with a signal processor for signal processing in accordance with selected values of a set of parameters Θ, a method of automatic adjustment of a set z of the signal processing parameters Θ, using a set of learning parameters θ of the signal processing parameters Θ is provided, wherein the method includes extracting signal features u of a signal in the hearing aid, recording a measure r of an adjustment e made by the user of the hearing aid, modifying z by the equation z=u θ+r, and absorbing the user adjustment e in θ by the equation θN=Φ(u,r)+θP, wherein θN is the new values of the learning parameter set θ, θP is the previous values of the learning parameter set θ, and Φ is a function of the signal features u and the recorded adjustment measure r

Stresses in Ytterbium Silicate Multilayer Environmental Barrier Coatings

The internal stresses of plasma-sprayed multilayer ytterbium disilicate environmental barrier coatings were measured using microfocused high-energy X-rays in a transmission geometry. Stresses were measured for as-sprayed and ex-situ heat-treated ytterbium disilicate topcoats at room temperature and during in-situ heating and cooling experiments. In-situ loading experiments were also performed on the topcoat in order to establish its elastic constants. The ytterbium disilicate was found to have a relatively low coefficient of thermal expansion resulting in compressive stresses of approximately 100 MPa throughout the topcoat. In-situ heating experiments revealed a statistically significant stress relaxation in the ytterbium disilicate topcoat upon thermal cycling to temperatures above 1300°C, indicating the onset of stress relaxation but no cracks were observed in SEM micrographs. The stress states were also modeled using a numerical solution; measured stresses were found to be very close to the predicted stresses in ytterbium dilisicate topcoats, while the experimentally determined stresses in the intermediate layers were of much smaller magnitude than the calculated stresses

Effect of crystallite orientation and external stress on hydride precipitation and dissolution in Zr2.5%Nb

Thermal cycling of Zr2.5%Nb pressure tubes specimens containing ∼100 wt ppm H between room temperature and 400 °C produces the dissolution and re-precipitation of zirconium hydride, with a distinctive hysteresis between these two processes. In this work, we have found that the details of the precipitation and dissolution depend on the actual orientation of the α-Zr grains where hydride precipitation takes place. In situ synchrotron X-ray diffraction experiments during such thermal cycles have provided information about hydride precipitation specific to the two most important groups of α-Zr phase orientations, namely crystallites having c-axes parallel (mHoop) and tilted by ∼20° (mTilted) from the tube hoop direction. The results indicate that hydrides precipitate at slightly higher temperatures (∼5 °C), and dissolve at consistently higher temperatures (∼15 °C) in mTilted grains than in mHoop grains. Moreover, application of a tensile stress along the tube hoop direction results in two noticeable effects in hydride precipitation. Firstly, it shifts hydride precipitation towards higher temperatures, at a rate of ∼(0.08 ± 0.02) °C/MPa for hydrides precipitated in the mHoop grains. Secondly, it produces a redistribution of hydrogen between grains of different orientations, increasing hydride precipitation on those α-Zr grains having their c-axes stretched by the external load. A detailed analysis of the diffracted signal shows that such redistribution occurs during the precipitation stage, as a result of changes in the precipitation temperatures for different grain orientations.Fil: Vizcaino, Pablo. Comisión Nacional de Energía Atómica. Centro Atómico Ezeiza; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Santisteban, Javier Roberto. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Vicente Alvarez, Miguel Angel. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Banchik, Abraham David. Comisión Nacional de Energía Atómica. Centro Atómico Ezeiza; ArgentinaFil: Almer, J.. Argonne National Laboratory; Estados Unido

Hydride precipitation and stresses in zircaloy-4 observed by synchrotron X-ray diffraction

The grain stresses within hydrides precipitated in rolled zircaloy-4 plates were determined by synchrotron X-ray diffraction experiments using an 80 keV photon beam and a high-speed area detector placed in transmission geometry. Results showed large compressive stresses (360 ± 20 MPa) in the hydrides along the plate rolling direction. The origin of these stresses was investigated by performing hydride dissolution/precipitation in situ for thermal cycles between room temperature and 400 C. A large stress hysteresis was observed, with a steady decrease on heating and an abrupt change on cooling. The observed stresses are explained by the constraint imposed by grain boundaries on the growth of hydride platelets on the rolling–transverse plane of the rolled plates.Fil: Santisteban, Javier Roberto. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Vicente Alvarez, Miguel Angel. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; ArgentinaFil: Vizcaino, Pablo. Comisión Nacional de Energía Atómica. Centro Atómico Ezeiza; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Banchik, A. D.. Comisión Nacional de Energía Atómica. Centro Atómico Ezeiza; ArgentinaFil: Almer, J. D.. No especifíca

Evaluating deformation behavior of a TBC-System during thermal gradient mechanical fatigue by means of high energy X-ray diffraction

Applications of TBC-systems involve complex thermal mechanical loading pattern including transient thermal gradients across the coated system, which result in multiaxial stresses and stress gradients affecting the damage behavior. In an ongoing research, starting more than 10 years ago, the authors developed laboratory test facilities for evaluating the damage behavior of TBC-systems for gas turbine blades in aeroengines under realistic thermal mechanical loading conditions [1]. Fatigue tests involving thermal gradients have been conducted and damage behavior in dependence of load pattern and pre heat treatment has been intensively investigated on TBC-systems comprising a partially yttria stabilized zirconia (YSZ) topcoat and a MCrAlY bond coat both applied by electron physical vapor deposition (EB-PVD) onto nickel based super alloys serving as substrate [2]. Numerical analyses by means of FE-calculations did provide hypotheses explaining the observed damage behavior [3], but even though the results are plausible they did depend on reasonable assumptions on materials properties since reliable data on the properties of the thin coating layers are still lacking, especially for high temperatures. High energy X-ray diffraction can provide the requested information since it is possible to achieve information on the local deformation processes in each layer with high spatial resolution, and short acquisition times allow for in situ investigation of time dependent deformation processes. A new test facility based on concepts after [1] for cyclic thermal loading of tubular specimens and applying a controlled thermal gradient across the coated specimen’s wall has been developed for implementation into an electro-mechanical test machine at the advanced photon source (APS) at Argonne National Laboratory. A precision positioning rig allows for exact µm-positioning of the entire test machine with respect to the focused X-ray beam, and X-ray diffraction patterns were taken using a 2D detector, giving accurate 360° lattice parameter data [4]. Tests have been performed with varying thermal and mechanical load schemata intending to determine material properties from the respective strain response. The beam energy was 65 keV, and throughout all experiments the beam scanned through the coating layers with a window and step size of 30 µm. Strain data were acquired in plane parallel to the specimen’s length axis and out of plane. Results of the strain data evaluation will be presented and discussed. Exemplary results are: - Elastic properties of the YSZ showed a gradient across the coating thickness reflecting the microstructure gradient of the YSZ resulting from the EB-PVD process. - The YSZ strain was – below the deposition temperature - in plane compressive and out of plane tensile, which is a consequence of (i) the higher thermal expansion coefficient of YSZ with respect to the substrate and (ii) the cylindrical specimen geometry with the YSZ at the outer surface. [1] M. Bartsch, G. Marci, K. Mull, C. Sick, Adv. Eng. Mater. (1999), 1(2), 127–9 [2] M. Bartsch, B. Baufeld, S. Dalkilic, L. Chernova, M. Heinzelmann, Int. J. Fatigue (2008) 30, 211–8 [3] M. T. Hernandez, A. M. Karlsson, M. Bartsch, Surf. Coat. Technol. (2009) 203, 3549–58 [4] S.F. Siddiqui, K. Knipe, A. Manero, C. Meid, J. Wischek, J. Okasinski, J. Almer, A.M. Karlsson, M. Bartsch, S. Raghavan, Review of Scientific Instruments (2013) 84, 08390