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Finding stable multi-component materials by combining cluster expansion and crystal structure predictions

npj Computational Materials 2023年第1期9卷 2137-2146页

作者： Adam Carlsson Johanna Rosen martin Dahlqvist Materials Design Department of PhysicsChemistryand Biology(IFM)Linköping UniversitySE-58183 LinköpingSweden

A desired prerequisite when performing a quantum mechanical calculation is to have an initial idea of the atomic positions within an approximate crystal *** atomic positions combined should result in a system located in,or close to,an energy ***,designing low-energy structures may be a challenging task when prior knowledge is scarce,specifically for large multi-component systems where the degrees of freedom are close to *** this paper,we propose a method for identification of low-energy crystal structures within multi-component systems by combining cluster expansion and crystal structure predictions with density-functional theory *** structure prediction searches are applied to the Mo_(2)AlB_(2) and Sc2AlB_(2) ternary systems to identify candidate structures,which are subsequently used to explore the quaternary(pseudo-binary)(Mo_(x)Sc_(1–x))2AlB_(2) system through the cluster expansion formalism utilizing the ground-state search ***,we show that utilizing low-energy structures found within the cluster expansion ground-state search as seed structures within crystal structure predictions of(Mo_(x)Sc_(1–x))2AlB_(2) can significantly reduce the computational *** this combined approach,we not only correctly identified the recently discovered Mo_(4/3)Sc_(2/3)AlB_(2) i-MAB phase,comprised of in-plane chemical ordering of Mo and Sc and with Al in a Kagomélattice,but also predict additional low-energy structures at various *** result demonstrates that combining crystal structure prediction with cluster expansion provides a path for identifying low-energy crystal structures in multi-component systems by employing the strengths from both frameworks.

关键词： structure cluster crystal

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Evaluation of the plasmonic effect of Au and Ag on Ti-based photocatalysts in the reduction of CO2 to CH4

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Journal of Energy Chemistry 2017年第2期26卷 277-283页

作者： martin Dilla Anna Pougin Jennifer Strunk Max-Planck-Institute for Chemical Energy conversion Stiftstraße 34-3645470 Mülheim/RuhrGermany Laboratory of Industrial Chemistry Ruhr-University BochumUniversitätsstraße 15044780 BochumGermany Center for Nanointegration Duisburg-Essen University of Duisburg-EssenCarl-Benz-Straße 19947057 DuisburgGermany

Crystalline TiO（P25） and isolated titanate species in a ZSM-5 structure（TS-1） were modified with Au and Ag, respectively, and tested in the gas-phase photocatalytic COreduction under high purity conditions. The noble metal modification was performed by photodeposition. Light absorbance properties of the catalysts are examined with UV–Vis spectroscopy before and after the activity test. In the gas-phase photocatalytic COreduction, it was observed that the catalysts with Ag nanostructures are more active than those with Au nanostructures. It is thus found that the energetic difference between the band gap energy of the semiconductor and the position of the plasmon is influencing the photocatalytic ***, plasmon excitation due to visible light absorption results in plasmon resonance energy, which affects the excitation of the semiconductor positively. Therefore, an overlap between band gap energy of the semiconductor and metal plasmon is needed.

关键词： Photocatalytic CO2 reduction Plasmon resonance Methane formation TS-1 P25 Noble metal photodeposition High-purity gas-phase photoreactor

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Evaluation for Small Visual Difference Between Conforming Meshes on Strain Field

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Journal of Computer Science & Technology 2009年第1期24卷 65-75页

作者：边哲胡事民 Ralph R.martin Department of Computer Science and Technology Tsinghua University School of Computer Science Cardiff UniversityCardiffU.K.

This paper gives a method of quantifying small visual differences between 3D mesh models with conforming topology, based on the theory of strain fields. Strain field is a geometric quantity in elasticity which is used to describe the deformation of elastomer. In this paper we consider the 3D models as objects with elasticity. The further demonstrations are provided： the first is intended to give the reader a visual impression of how our measure works in practice; and the second is to give readers a visual impression of how our measure works in evaluating filter algorithms. Our experiments show that our difference estimates are well correlated with human perception of differences. This work has applications in the evaluation of 3D mesh watermarking, 3D mesh compression reconstruction, and 3D mesh filtering.

关键词： 3D conforming meshes mesh comparison perception strain fields

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The Ethico-Political Universe of ChatGPT

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Journal of Social Computing 2023年第1期4卷 1-11页

作者： John Levi martin John Levi martin is with the Sociology Department University of ChicagoChicagoIL 60637USA

There have been widespread concerns about two aspects of the current explosion of predictive text models and other algorithm-based computational *** one hand,it is often insisted that Artificial Intelligence(AI)should be made“ethical”,and software providers take this seriously,attempting to make sure that their tools are not used to facilitate grossly criminal or widely condemned *** the other hand,it is also widely understood that those who create these tools have a responsibility to ensure that they are“unbiased”,as opposed to simply helping one side in political contestation define their perspectives as reality for ***,these two goals cannot be jointly satisfied,as there are perhaps no ethical prescriptions worthy of notice that are not contested by *** I investigate the current ethico-political sensibility of ChatGPT,demonstrating that the very attempt to give it an ethical keel has also given it a measurably left position in the political space and a concomitant position in social space among the privileged.

关键词： algorithmic bias values machine ethics human-machine interaction

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Early Cretaceous dinosaur and other tetrapod tracks of southwestern China

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Science Bulletin 2016年第13期61卷 1044-1051页

作者： Lida Xing martin G.Lockley State Key Laboratory of Biogeology and Environmental Geology China University of Geosciences School of the Earth Sciences and Resources China University of Geosciences Dinosaur Trackers Research Group University of Colorado Denver

In recent years the Lower Cretaceous red beds of southwestern China have yielded more than 20 significant dinosaur-dominated tracksites. More than half occur in the Jiaguan Formation with the remainder in the Feitianshan and Xiaoba formations. Collectively these sites provide evidence of at least 13 distinct dinosaurian trackmaker morphotypes, in addition to two avian theropod(bird)morphotypes and pterosaur and turtle tracks. Together these total 17 morphotypes provide a data base of 479 potential trackmakers, probably representing the same number of individuals. Such an ichnological database provides a useful proxy paleoecological census of tetrapod communities in the area during the Early Cretaceous, and is especially significant given the complete absence or scarcity of skeletal remains reported from these *** composition of ichnofaunas in all three formations is heavily saurischian(theropod and sauropod) dominated with a high diversity of distinctive theropod morphotypes,mostly assignable to known ichnogenera. Moreover, ichnofaunal data from multiple sites are generally consistent between sites and an indication of the reliability and repeatability of track census data. Such regionally-widespread data are rapidly superseding the information available from the skeletal record in the corresponding area, and must therefore be considered of high paleontological value.

关键词： Early Cretaceous - Dinosaur tracks Southwestern China Paleoecology

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Possible role of power-to-heat and power-to-gas as flexibleloads in German medium voltage networks

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Frontiers in Energy 2017年第2期11卷 135-145页

作者： Mark KUPRAT martin BENDIG Klaus PFEIFFER Forschungszentrum 3E LS EVH Siemens-Halske-Ring 13 03046Cottbus Germany

Germanys energy transition triggered a rapid and unilateral growth of renewable energy sources (RES) in the electricity sector. With increasing shares of intermittent RES, overcapacities during periods of strong wind and photovoltaic electricity generation occur. In the face of insufficient transmission capacities, due to an inhibited network extension, the electricity generation has to be curtailed. This curtailment of RES leads to economic losses and could be avoided through flexible loads. As an option to cope with those problems, the technologies of power-to-gas (PtG) and power-to-heat (PtH) are presented in this paper. First, the alkaline electrolyzer (AEL), polymer electrolyte membrane electrolyzer (PEMEL), and solid oxide electrolyzer cell (SOEC) are investigated regarding their operational parameters. Second, the electric boiler, electrode heating boiler, and heat pumps are considered. Ultimately, the network-supporting abilities and the potential to provide ancillary services, such as control power, load sequence operation, cold start and part load capability, are compared among one another.

关键词： power-to-gas power-to-heat flexible loads ancillary services coherent energy systems

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Numerical Noise Prediction in Fluid Machinery

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Journal of Thermal Science 2005年第3期14卷 230-235,248页

作者： Iris PANTLE Franco MAGAGNATO martin GABI Department of Fluid Machinery University of Karlsruhe D-76128 Karlsruhe Department of Fluid Machinery University of Karlsruhe D-76128 Karlsruhe Department of Fluid Machinery University of Karlsruhe D-76128 Karlsruhe

Numerical methods successively became important in the design and optimization of fluid machinery. However, as noise emission is considered, one can hardly find standardized prediction methods combining flow and acoustical optimization. Several numerical field methods for sound calculations have been developed. Due to the complexity of the considered flow, approaches must be chosen to avoid exhaustive computing. In this contribution the noise of a simple propeller is investigated. The configurations of the calculations comply with an existing experimental setup chosen for evaluation. The used in-house CFD solver SPARC contains an acoustic module based on Ffowcs Williams-Hawkings Acoustic Analogy. From the flow results of the time dependent Large Eddy Simulation the time dependent acoustic sources are extracted and given to the acoustic module where relevant sound pressure levels are calculated. The difficulties, which arise while proceeding from open to closed rotors and from gas to liquid are discussed.

关键词： numerical noise prediction fluid machinery computational aero-acoustics large eddy simulation

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Size effect on deuterium behavior in nano-sized vanadium layers

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Science China(Physics,Mechanics & Astronomy) 2019年第11期62卷 109-114页

作者： Wen Huang martin Brischetto Bjorgvin Hjorvarsson State Key Laboratory of Silicon Materials and School of Materials Science and Engineering Zhejiang UniversityHangzhou 310027China Department of Physics and Astronomy Uppsala UniversityUppsala SE-75120Sweden Department of Materials Science and Engineering University of WashingtonSeattle WA 98195-2120USA

Size effect on thermodynamics and diffusion of deuterium in nano-sized vanadium(V) layers is studied. Critical temperature(Tc)for deuterium phase transition is found to decrease with the inverse thickness of V layers and the thermodynamic factor increases as V thickness decreases. These effects are related to the deuterium-deuterium(D-D) interaction change versus V thickness,which experimentally proves that the D-D interaction plays the main contribution to the previously observed V size effect on deuterium chemical diffusion coefficients(D_c). The self-diffusion coefficients(D_s) are obtained through correcting D_c with the thermodynamic factors. It is found that the D_s are similar in 14 and 28 monolayers of V while slightly larger D_s are observed at high concentrations in 14 atomic layers. The weak site blocking effect in the interface is argued to be the main contribution to the observed size effect on D_s.

关键词： size effect D-D interaction deuterium diffusion Fe/V superlattice optical transmission

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Empirical Model for the Quantitative Prediction of Losses of Radial Fans based on CFD Calculations

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Journal of Thermal Science 2013年第4期22卷 304-310页

作者： Heiko Ratter Saban Caglar martin Gabi Institute of Fluid Machinery Karlsruhe Institute of Technology Kaiserstrasse 1276131 Karlsruhe Germany

In a classical layout process of a fan the quantity of losses is estimated as a sum and expressed in the overall efficiency rote However the characteristic of the pressure rise, the losses and the efficiency rate beside the design point is not known. Against this background a numerical model was developed to calculate quantitative values of occurring losses at radial fan impellers at an early stage in the design process. It allows to estimate the pressure rise and efficiency rate of a given fan geometry at and beside the design point. The physics of losses are described in literature, but obtaining quantitative values is still a challenge. As common in hydraulic theory the losses are calculated with analytic formulas supported by coefficients and efficiency rates, which have to be determined empirically. This paper shows the method how to determine the coefficients for a given radial fan. Therefore a representative radial fan with backward curved blades was designed in reference to classical design guidelines. Performance measuring was done conform to ISO 5801. The flow was calculated at 8 different operation points using CFD methods. The RANS equations are solved by using the SST-k-omega turbulence model. The flow do- main consists of one blade section including inlet channel and outflow chamber. Spatial discretization is done by a block-structured mesh of approx. 1.8 million cells. Performance data show a very good agreement between measurement and calculation.

关键词： loss model radial fan CFD RANS

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Perceptual hashing algorithms benchmark suite

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仪器仪表学报 2007年第4期28卷 603-608页

作者： Zhang Hui Schmucker martin Niu Xiamu Harbin Institute of Technology Shenzhen Graduate School Room 304 Building No. 3 HIT Campus Shenzhen 518055 China Fraunhofer IGD Fraunhoferstr 5 Darmstadt 64283 Germany

Numerous perceptual hashing algorithms have been developed for identification and verification of multimedia objects in recent years. Many application schemes have been adopted for various commercial objects. Developers and users are looking for a benchmark tool to compare and evaluate their current algorithms or technologies. In this paper, a novel benchmark platform is presented. PHABS provides an open framework and lets its users define their own test strategy, perform tests, collect and analyze test data. With PHABS, various performance parameters of algorithms can be tested, and different algorithms or algorithms with different parameters can be evaluated and compared easily.

关键词：感觉散列算法 PHABS 基准点识别技术

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