Spatial ensemble post‐processing with standardized anomalies Dabernig, Markus; Mayr, Georg J.; Messner, Jakob W. ...
Quarterly journal of the Royal Meteorological Society,
January 2017 Part B, 2017-01-00, 20170101, Volume:
143, Issue:
703
Journal Article
Peer reviewed
Open access
To post‐process ensemble predictions for a particular location, statistical methods are often used, especially in complex terrain such as the Alps. When expanded to several stations, the ...post‐processing has to be repeated at every station individually, thus losing information about spatial coherence and increasing computational cost. Therefore, the ensemble post‐processing is modified and applied simultaneously at multiple locations. We transform observations and predictions to standardized anomalies. Seasonal and site‐specific characteristics are eliminated by subtracting a climatological mean and dividing by the climatological standard deviation from both observations and numerical forecasts. This method allows us to forecast even at locations where no observations are available. The skill of these forecasts is comparable to forecasts post‐processed individually at every station and is even better on average.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
For multi-ceramic materials based on the stereolithography (SL) principle, a 3D printing strategy was developed, and then an Al2O3-Si3N4 functionally graded material (FGM) ceramic part was fabricated ...using this strategy. Six groups of mixtures, with a Si3N4 content gradient of 20 vol% and a certain bimodal particle size distribution, were prepared using UV-curable pastes. A modified formula was proposed to evaluate the relationship between the actual minimum voidage of mixtures and the viscosities of their corresponding pastes. The viscosity of each paste was controlled using the prediction formula and optimization of dispersants. To design theprinting layer thickness, a mathematical relationship was established between Si3N4 content and curing depth of paste. The Al2O3-Si3N4 green body without deformation was printed using optimized parameters such as a layer thickness of 40 μm and a paste viscosity of ∼13,000 mPa·s. Finally, using debinding and sintering, denseparts having a complicated shape were obtained.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The turbine blade test parts were manufactured by the selective laser melting (SLM) process using a nickel-based pre-alloyed Inconel (IN) 718 powder. Various mechanical post-processing techniques, ...such as barrel finishing (BF), shot peening (SP), ultrasonic shot peening (USP), and ultrasonic impact treatment (UIT), were applied to improve the surface layer properties of the SLM-built specimens. Effects of mechanical surface treatments on surface topography, porosity, hardness, and residual stress were studied. In comparison with the SLM-built state the surface roughness (Sa = 5.27 μm) of the post-processed specimens were respectively decreased by 20.6%, 26.2%, and 57.4% after the BF, USP, and UIT processes except for the SP-treated ones. The Sz parameter was reduced in all treated SLM-built specimens except for the SP-treated ones. The surface microhardness of the SLM-built specimen (~390 HV0.025) was increased after the BF (by 14.2%), USP (by 23.8%), UIT (by 50%), and SP (by 66.5%) processes. The deepest hardened layers were formed after the UIT and SP processes. Residual porosity of the SLM-built specimen was decreased by 23.1%, 40.6%, 55%, and 84% after the BF, SP, USP and UIT processes, respectively. The UIT process formed a densified subsurface layer of significantly reduced porosity (0.118%). All mechanical surface treatments successfully transformed the tensile residual stresses generated in SLM-built specimen into the compressive residual stresses (−201.4...510.7 MPa). The thickness of hardened, densified and compressed near-surface layers ranges from ~80 μm after BF to ~140 μm after USP, and ~180 μm after SP and UIT processes, which correlates to the accumulated energy and deformation extent of the treated surface. The effect of the accumulated energy on the outcomes of the applied surface treatments is also addressed.
•The turbine blade test IN 718 parts were manufactured by selective laser melting (SLM)•Mechanical post-processing techniques were applied to improve the surface layer properties•Barrel finishing (BF), shot peening (SP), ultrasonic shot peening (USP), and ultrasonic impact treatment (UIT) were used•Surface texture, roughness, hardness, porosity, and residual stress were studied
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The surface integrity of machined metal components is critical to their in-service functionality, longevity and overall performance. Surface defects induced by machining operations vary from the nano ...to macro scale, which cause microstructural, mechanical and chemical effects. Hence, they require advanced evaluation and post processing techniques. While surface integrity varies significantly across the range of machining processes, this paper explores the state-of-the-art of surface integrity research with an emphasis on their governing mechanisms and emerging evaluation approaches. In this review, removal mechanisms are grouped by their primary energy transfer mechanisms; mechanical, thermal and chemical based. Accordingly, the resultant multi-scale phenomena associated with metal machining are analyzed. The contribution of these material removal mechanisms to the workpiece surfaces/subsurface characteristics is reviewed. Post-processing options for the mitigation of induced surface defects are also discussed.
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•Machining-induced surface integrity significantly influences the in-service functional performance of advanced alloys.•Surface integrity is affected by the energy transfer mechanism, i.e. mechanical, thermal, chemical and their combination.•State-of-the-art research of surface integrity is discussed, with emphasis on emerging approaches for its evaluation.•Influence of different material removal mechanisms upon the workpiece surface/subsurface characteristics are explored.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This study investigated the effect of different hydrocolloids on the improvement of the printability and post-processing stability of minced chicken meat, each hydrocolloid was prepared with 1 % ...formulation and compared with the control. The effects of these hydrocolloids on the rheological properties of chicken mince and complex model printing capability were explored separately, while the cooking loss and microstructure changes of the samples before and after heating were analyzed. The results showed that the chicken mince gel containing carrageenan was more suitable for printing, increased the yield stress and apparent viscosity of the samples, and the printing process was easier to mold. In addition, carrageenan increased the hardness of the samples, and the microstructures were compact and changed little during the heating process, and the water was locked in the gel matrix, reducing shape changes during the heating process. The use of hydrocolloids improves the stability of post-processing of chicken 3D printing.
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•Hydrocolloids changed the 3D printing performance of chicken paste.•Chicken paste with KG had the highest printing accuracy.•Chicken paste with AG, KG and GEL could be used to print the complex model.•Hydrocolloids reduce water loss and improve post-treatment stability.•Carrageenan enhances the hardness of the product and the ability to resist external forces.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
IN738LC is an important high performance Ni-based superalloy. Its additive manufacturing via selective laser melting (SLM), however, is rather challenging due to the cracking-prone nature of the ...alloy whose chemical composition contains high amount of alloying elements namely Ti and Al. We address this significant problem by this study through systematic investigations on the pre-processing, SLM optimization, and post-processing of the material, as well as using advanced analytical tools such as micro-CT. A comprehensive process map for achieving crack-free, high-density samples (∼99.76%) is provided. Mechanisms influencing densification, cracking and mechanical properties are discussed. Excellent mechanical properties have been achieved at both room temperature (895/1010 MPa as the yield and tensile strengths) and elevated temperature of 850 °C (720 MPa tensile strength and 14.4% elongation). A demonstrative as-printed turbine blade is also presented, highlighting the capability of SLM to simultaneously achieve excellent mechanical property and good geometric integrity.
•Selective laser melted IN738LC superalloy shows high density (∼99.76%).•SLM process map provided for the IN738LC superalloy.•Good mechanical property (720 MPa and 14.4% elongation) achieved at 850 °C.•Defects mitigation approaches provided, followed by mechanism discussion.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Low-light image enhancement (LLIE) techniques attempt to increase the visibility of images captured in low-light scenarios. However, as a result of enhancement, a variety of image degradations such ...as noise and color bias are revealed. Furthermore, each particular LLIE approach may introduce a different form of flaw within its enhanced results. To combat these image degradations, post-processing denoisers have widely been used, which often yield oversmoothed results lacking detail. We propose using a diffusion model as a post-processing approach, and we introduce Low-light Post-processing Diffusion Model (LPDM) in order to model the conditional distribution between under-exposed and normally-exposed images. We apply LPDM in a manner which avoids the computationally expensive generative reverse process of typical diffusion models, and post-process images in one pass through LPDM. Extensive experiments demonstrate that our approach outperforms competing post-processing denoisers by increasing the perceptual quality of enhanced low-light images on a variety of challenging low-light datasets. Source code is available at https://github.com/savvaki/LPDM.
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•Low-light enhancement results in noisy images, treated by post-processing denoising.•Mapping from poor- to well-lit images can be captured by a conditional distribution.•Diffusion model is used to learn the low-light to well-lit conditional distribution.•Proposed diffusion model avoids the iterative process typical of diffusion models.•Our diffusion model achieves state-of-the-art results on post-processing denoising.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Climate change and anthropogenic activities have influenced the frequency and magnitude of forest fires both globally and regionally. While skilful short- to extended-range prediction of forest fires ...is essential for effective mitigation in local communities, it is also important to identify the implications of forest fires on different sectors, including water resources and sustainable development. Limited studies have investigated the association between forest fires and hydrometeorological variables at the regional scale in developing countries due to the lack of necessary datasets, which can now be leveraged using the newly hosted global reanalysis of fire danger indices (referred to as fire indices). The current study presents a comprehensive analysis of the spatio-temporal variations of eight fire indices across India, as well as their association with hydro-meteorological variables, such as precipitation, temperature, and the streamflow of a major river basin (Mahanadi) in India. The accuracy of these indices in capturing real fire events and the potential benefit of incorporating fire indices into long-term hydrologic simulations are also explored. The results show that fire indices can accurately yield fire seasons (i.e., post-monsoon and summer) in India. Furthermore, forest fires are found to be strongly associated with hydro-meteorological variables, typically resulting in low streamflow regimes. Fire indices can also capture actual fire events, maintaining high scalar accuracy. Finally, an improvement in uncalibrated hydrologic model simulations is observed when simulated streamflow is post-processed using the fire indices as predictors. Overall, the current study has valuable implications for fire indices forecasting and hydrologic simulations in ungauged basins.
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•Fire indices can capture real fire, and they are associated with hydrometeorological variables.•Fire seasons result in reduced streamflow in the Mahanadi basin.•Inclusion of fire indices improves long-term simulations of streamflow.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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