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[Display omitted] • Evidence of recrystallization without prior deformation during austenitization of 15-5 PH steel. • Increasing heating rates lead to decreasing grain sizes of recrystallized γ. • Recrystallization correlates with the mechanisms involved in the prior α' to γ transformation. • Smaller grain sizes seem to be attributed to increased defect density in the reverted austenite. • During α' to γ transformation a defect arrangement of LAGBs and internal, grown-in dislocations is inherited from α' laths to γ. The recrystallization without previous deformation is reported in literature for a small, selected group of alloys. The present work provides evidence for the first time that the commercial stainless steel 15-5 PH also shows this recrystallization phenomenon during austenitization. A set of in-situ and ex-situ high-temperature techniques reveal that, on heating of the martensitic microstructure, recrystallization takes place after phase transformation between 900 and 1000 °C, causing a distinct reduction of the austenite grain size. This work also shows that the recrystallization correlates with the mechanisms involved in the prior martensite to austenite transformation. It is observed that increasing heating rates lead to decreasing grain sizes. This is attributed to increased defect density in the reverted austenite and increased driving pressure for the nucleation of recrystallized grains. It is proposed that, during martensite to austenite reversion, a defect arrangement of highly stable low-angle grain boundaries and, with increased heating rate, an increased density of internal, grown-in dislocations is inherited from martensite laths. This highly defect-loaded microstructure, formed without external plastic deformation, leads to a recrystallization at increased temperatures. The experimental results agree well with thermokinetic calculations based on the proposed defect arrangement, underpinning the mechanism of spontaneous recrystallization in 15-5 PH. [ABSTRACT FROM AUTHOR]

The transient thermal behaviour of a ventilated solar honeycomb (SHC) façade element was investigated with the help of numerical simulations. Therefore two three-dimensional CFD models were used to consider a SHC façade element with and without attached PV cells at the exterior glass pane. Beside a natural convective flow model also a radiation model with two wavebands was implemented to enable the differentiation between short-wave solar radiation and long-wave thermal radiation. In a laboratory experiment temperatures in the ventilation cavity and the heat flux at the rear wall of the SHC façade were monitored and compared to simulation results. The experiment using a solar simulation device was carried out for one façade element with PV cells at the exterior glass pane and for one façade element without PV cells. The time-step size for the transient simulations was dramatically reduced after the determination of the maximum time-step size, which finally enabled the analysis of the thermal behaviour over a prolonged period (one day or longer) within reasonable simulation durations. Moreover, the impact of the SHC’s material properties on the dynamic thermal behaviour was analysed with the three-dimensional CFD-model. Differences in heating rate, heat flux and temperatures were determined and compared by using five different materials instead of the cellulose honeycomb. Finally this study obtained the impact of hourly changing external climate conditions on the thermal behaviour of a single 1 × 1 m SHC façade element using climate data from a cold winter’s day and a hot summer’s day which were measured in Graz, Austria. [ABSTRACT FROM AUTHOR]

The thermal behaviour and air flow characteristic for a solar honeycomb (SHC) façade element at different PV cell configurations was analysed in order to evaluate the thermal and ventilation performance as well as the electrical output. The base construction of this façade prototype inherited from the base façade element “GAP-Skin”, which is a development of the company “Gap 3 solutions GmbH”. The aim was to find a PV cell configuration which shows the best ratio between the thermal behaviour of the SHC façade and the electrical output of the PV array. Three-dimensional CFD simulations were performed and compared with measurement data from a laboratory experiment. In order to do this, a test stand was built with a 1 × 1 m SHC façade element and a solar simulator. The CFD models contained a detailed radiation model to take solar and thermal radiation into account. The numerical results from the developed models correlated well to a large extent with the measured data. Furthermore, this study obtained the thermal behaviour of the SHC façade element in summer and winter climate conditions in the temperate zone, considering different solar absorption characteristics of the SHC at different solar angles. [ABSTRACT FROM AUTHOR]

This study determines thermal behaviour and airflow characteristics inside multifunctional façade elements. The façade elements investigated were designed in course of the research project “Multifunctional Plug & Play Facade” [1] . The integration of energy converting systems in a façade construction causes higher temperatures on the backside of the collectors impacting subjacent layers and the interior. Due to periphery openings, heat can partly be transferred to the exterior by the effects of natural ventilation. With the help of ‘steady state’ 3D Computational Fluid Dynamics (CFD) models of three different façade elements were investigated and compared. In particular this study presents a detailed analysis of airflow and the thermal behaviour of a photovoltaic module (PV), a solar thermal collector (ST) as well as a transparent single layer glass panel used as impact pane (TR) all integrated into the façade construction. Despite high temperatures in the solar thermal collector the lowest air temperatures inside the cavity were detected for the ST façade. The ventilation effects of the side openings were clearly identified in all façades. The numerical model includes the effects of heat transfer, buoyancy, radiation and the impact of solar radiation. Data from on-site measurement did largely match with the simulations’ outcome. [ABSTRACT FROM AUTHOR]

Recent measurements of micron-sized Mo/Au bilayer TESs have demonstrated that the TES can behave like an S-S′-S weak link due to the lateral proximity effect from superconducting leads. In this regime the T is a function of bias current, and the effective T shifts from the bilayer T towards the lead T. We explore the idea that a micron-sized S-N-S weak link could provide a new method to engineer the TES T. This method would be particularly useful when small size requirements for a bilayer TES (such as for a hot-electron microbolometer) lead to undesirable shifts in the bilayer T. We present measurements of a variety of micron-sized normal Au 'TES' devices with Nb leads. We find no evidence of a superconducting transition in the Au film of these devices, in dramatic contrast to the strong lateral proximity effect seen in micron-sized Mo/Au bilayer devices. The absence of a transition in these devices is also in disagreement with theoretical predictions for S-N-S weak links. We hypothesize that a finite contact resistance between the Nb and Au may be weakening the effect. We conclude that the use of the lateral proximity effect to create a superconducting transition will be difficult given current fabrication procedures. [ABSTRACT FROM AUTHOR]

Using the plasmon hybridization method we investigate the plasmon modes of nanorod dimers in axial and parallel orientations. We show that the plasmon modes of the system can be viewed as bonding and anti-bonding modes resulting from the hybridization of the plasmon modes of the individual nanorods. The dimer plasmon modes are found to depend sensitively on separation between the nanorods and on their relative spatial orientation. The calculated optical properties agree quantitatively with results from the numerical finite-difference time-domain method. The electric field enhancements are found to depend strongly on aspect ratio defined as the ratio of the major and minor radii, and on the relative orientation of the nanorods. For a nanorod dimer of fixed overall length, the maximum field enhancements are lower than those induced in a solid sphere dimer. [ABSTRACT FROM AUTHOR]

Empirical validation and code-to-code comparison of more than one building simulation tool has seldom been done in literature. Therefore this paper presents the first detailed comparison of 1D building energy simulation tools with 3D CFD simulation and measurement data from a test bed (Test-Box), exposed to natural environmental conditions. Dymola (library: IDEAS), EnergyPlus, IDA ICE and TRNSYS –four commonly used tools– were selected for comparison against highly accurate real measurement data and dynamic CFD results. This paper evaluates the performance of mentioned above 1D simulation tools and in particular their implemented Thermally Activated Building Systems (TABS) models. The mean error, RMSE, standard deviation and maximal error for the room air, the ceiling surface and concrete temperature of the Test-Box model results are acceptable for all tools. The time course of the room air temperature follows the measurement data relatively well for all four tools. However, the negative bias (Dymola -0.92 K, EnergyPlus -2.18 K, IDA ICE -0.37 K and TRNSYS -1.13 K) indicates a general overestimation for all tools. Furthermore, the paper reflects the properties of simulation tools regarding the modelling language, GUIs, co-simulation capabilities and their recommended field of application. [ABSTRACT FROM AUTHOR]

Abstract: Grasslands are often managed with different intensities in the European Alps. Studies have shown that a medium management can benefit plant and animal biodiversity in these ecosystems. However, in recent decades abandonment of extensively managed meadows is an ongoing global challenge. Syrphids (hoverflies) have been recognized as a threatened group due to environmental drivers, and these managed grasslands provide preferred habitats for them. Yet, at what extent syrphids respond to grassland management strategies is little known. We investigated whether abandonment of managed mountain meadows (mown once a year, no fertilizer use) affects syrphid abundance, richness and species assemblages. Moreover, the influence of plant richness, flower frequency and surrounding landscape on syrphids were assessed. Four managed meadows were compared with four abandoned meadows in a mountainous region in Austria. Adult syrphids were sampled over two consecutive years (June and August 2015–2016) by sweep netting using line transects and observation plots. Syrphid abundance was significantly higher in managed than abandoned meadows and increased with increasing plant richness and flower frequency across management types. Management and sampling time also significantly affected syrphid species assemblages. Syrphid richness and abundance were not influenced by surrounding landscape. We conclude that both abandoned and managed meadows provide important habitat types for syrphids. Therefore, efforts should be made to maintain both managed and abandoned meadows in order to protect syrphid species within mountainous landscapes. [ABSTRACT FROM AUTHOR]

In the last few years, Cu is handled as a promising element to improve the corrosion resistance of duplex steels. Although there is a very limited number of studies in the literature describing the influence of Cu on the microstructure of duplex steels in the aged condition, to the authors' knowledge, no comprehensive study has been presented so far that describes in detail its influence on the microstructure and correlated mechanical properties in the solution-annealed condition. Consequently, this work is intended to fill that gap to provide a fundamental base for material design of novel duplex steels. Microstructural investigations showed a preferred formation of austenite combined with an elemental redistribution of Cr and Mo. Especially at the highest Cu content investigations revealed precipitation of Cu particles causing – so far unknown – an intragranular austenite in ferrite. It is proposed that the enrichment of austenite forming elements, i.e. Ni, at their phase boundaries as well as a low misfit between Cu particles and the intragranular austenite nuclei play a significant role during its nucleation. Due to the identified microstructural changes triggered by Cu an increased imbalance of the flow stress between ferrite and austenite, and thus a decrease of the macroscopic yield strength can be proposed. In turn an increased work hardening with Cu addition causes an unaffected ultimate tensile strength. [Display omitted] • Cu increases the austenite content as well as the elemental partitioning of Cr and Mo. • Cu alloying results in precipitation of Cu particles and a formation of intragranular austenite in ferrite. • The formation of intragranular-γ is promoted by an enrichment of Ni and a low misfit to pre-existing Cu particles. • A decreasing global yield strength is due to an increased imbalance of hardness between ferrite and austenite. • An unaffected global ultimate tensile strength is due to an increased work hardening caused by incoherent Cu particles. [ABSTRACT FROM AUTHOR]

We present a high-resolution spectrum of the diffuse X-ray background from 0.1 to 1 keV for a ∼1 sr region of the sky centered at l = 90°, b = +60° using a 36 pixel array of microcalorimeters flown on a sounding rocket. With an energy resolution of 11 eV FWHM below 1 keV, the spectrum's observed line ratios help separate charge exchange contributions originating within the heliosphere from thermal emission of hot gas in the interstellar medium. The X-ray sensitivity below 1 keV was reduced by about a factor of four from contamination that occurred early in the flight, limiting the significance of the results. The observed centroid of helium-like O VII is 568+2– 3 eV at 90% confidence. Since the centroid expected for thermal emission is 568.4 eV and for charge exchange is 564.2 eV, thermal emission appears to dominate for this line complex. The dominance of thermal emission is consistent with much of the high-latitude O VII emission originating in 2-3 × 106 K gas in the Galactic halo. On the other hand, the observed ratio of C VI Lyγ to Lyα is 0.3 ± 0.2. The expected ratios are 0.04 for thermal emission and 0.24 for charge exchange, indicating that charge exchange must contribute strongly to this line and therefore potentially to the rest of the ROSAT R12 band usually associated with 106 K emission from the Local Hot Bubble. The limited statistics of this experiment and systematic uncertainties due to the contamination require only >32% thermal emission for O VII and >20% from charge exchange for C VI at the 90% confidence level. An experimental gold coating on the silicon substrate of the array greatly reduced extraneous signals induced on nearby pixels from cosmic rays passing through the substrate, reducing the triggered event rate by a factor of 15 from a previous flight of the instrument. [ABSTRACT FROM AUTHOR]