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Pressure and temperature effects resulting from impact onto materials of different reactivity

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Defence Technology(防务技术) 2025年第2期44卷 221-230页

作者： andreas Heine Matthias Wickert Fraunhofer Institute for High-Speed Dynamics Ernst-Mach-InstitutEMIErnst-Zermelo-Str.4Freiburg im Breisgau79104Germany

The pressure and temperature increase resulting from the impact of different threats onto target materials is analyzed with a unified laboratory-scale *** allows deriving qualitative information on the occurring phenomenology as well as quantitative statements about the relative effects sizes as a function of target material and *** considered target materials are steel,aluminum,and *** threats,kinetic energy penetrator,explosively formed proj.ctile,and shaped charge j.t are *** the investigated combinations,the measured overpressures vary by a factor of up to 5 for a variation of the material,by a factor of up to 7 for a variation of the threat,and by a factor larger than 15for a simultaneous variation of *** obtained results as well as the experimental approach are relevant for the basic understanding of impact effects and risks due to material *** paper combines two main ***,to provide a summary of own prior work in a coherent j.urnal article and,secondly,to review and discuss these earlier results with a new perspective.

关键词： Impact effects Pressure Temperature Risk assessment Material reactivity

An illustrated guide to:Distributed and integrated fibreoptic sensing in seismology

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Earthquake Science 2025年第1期38卷 67-77页

作者： andreas Fichtner Fabian Walter Patrick Paitz Sara Klaasen Daniel C.Bowden Sebastian Noe Nils Müller Dominik Husmann j.cques Morel Department of Earth Sciences ETH ZürichZürich 8049Switzerland Swiss Federal Institute for Forest Snow and Landscape ResearchBirmensdorf 8903Switzerland Swiss Federal Institute of Metrology METAS Bern 3003Switzerland

The properties of laser signals are affected by deformation of the optical fibre through which they are *** this deformation dependence is undesirable in telecommunication,it can be exploited for the construction of novel seismic sensors that fill a niche in data acquisition where traditional seismometer arrays would be difficult to *** includes densely populated urban centers,the oceans,volcanoes and the Earth’s polar *** notes complement a presentation on recent methodological developments and applications in fibre-optic *** first part is focused on the use of distributed fibreoptic sensing in cryosphere research,and specifically the investigation of the internal structure and seismicity of glaciers and ice *** second part is dedicated to recent advances in integrated fibre-optic sensing,with emphasis on novel measurement principles and sensitivity.

关键词： seismology fibre-optics cryosphere earthquakes

Determination of quantitative structure-property and structure-process relationships for graphene production in water

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Nano Research 2015年第6期8卷 1865-1881页

作者： Thomas j. Nacken Cornelia Damm Haichen Xing andreas ROger Wolfgang Peukert Institute of Particle Technology (LFG) Friedrich-Alexander University Erlangen-NOrnberg (FAU) Cauerstrasse 4 91058 Erlangen Germany

A scalable method for graphene and few-layer graphene （FLG） production by graphite delamination in aqueous solutions of the nonionic surfactant TWEEN 80 （TW80） using stirred-media mills is presented. Delaminated product analysis using statistical Raman spectroscopy yielded extensive processing-structure-property relationships that revealed how stress intensity and specific energy input, i.e., the process parameters, govern the yield of graphene production and defect formation. The dispersed carbon concentration increased but the content and the quality of the FLG product decreased sharply with higher specific energy input. The FLG content of the product was up to 90%, especially for low specific energy input. Moreover, Raman analyses revealed that stress intensities greater than about I nj.were related to significant defect formation in the product particles. Another key parameter for graphene production is solvent viscosity. The FLG concentration in the product increased by a factor of 10 when the solvent＇s viscosity was increased from 1 to 6 mPa-s because shear- and friction-induced delamination was enhanced and in-plane fracture was reduced due to dampening of bead motion. Based on the processing-structure-property relationships found, we propose that the delamination process can be designed in such way that the product consists, almost totally, of FLG and that single-layer graphene is produced. The scalability of graphene production by stirred-media delamination was demonstrated when an increase in the batch size from 0.2 to 2 L had no significant effect on product quality.

关键词： graphite delamination few-layer graphene graphene stirred-media millprocess parameters statistical Ramanspectroscopy

Tailored surface textures to increase friction-A review

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Friction 2022年第9期10卷 1285-1304页

作者： Henara L.COSTA j.rg SCHILLE andreas ROSENKRANZ School of Engineering Surface Engineering GroupUniversidade Federal do Rio GrandeRio Grande 96203900Brazil University of Applied Sciences Mittweida Laserinstitut Hochschule Mittweida 09648Germany Department of Chemical Engineering Biotechnology and MaterialsUniversity of ChileSantiago 8370459Chile

Surface textures with micro-scale feature dimensions still hold great potential to enhance the frictional performance of tribological *** from the ability of surface texturing to reduce friction,surface textures can also be used to intentionally increase friction in various applications that rely on friction for their adequate ***,this review aims at presenting the state-of-the-art regarding textured surfaces for high-friction *** a brief general introduction,the recent trends and future paths in laser surface texturing are ***,the potential of surface textures to increase friction in different applications including adhesion,movement transmission and control,biomimetic applications,and road-tire contacts is critically *** emphasis in this section is laid on the involved mechanisms responsible for friction ***,current short-comings and future research directions are pointed out thus emphasizing the great potential of(laser-based)surface texturing methods for innovations in modern surface engineering.

关键词： surface texturing tribology laser processing friction increase

A BIE-BASED DtN-FEM FOR FLUID-SOLID INTERACTION PROBLEMS

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j.urnal of Computational Mathematics 2018年第1期36卷 47-69页

作者： Tao Yin andreas Rathsfeld j.Liwei Xu College of Mathematics and Statistics Chongqing University Chongqing 401331 China Weierstrass Institute Mohrenstr. 39 10117 Berlin Germany

In this paper, we are concerned with the coupling of finite element methods and bound- ary integral equation methods solving the classical fluid-solid interaction problem in two dimensions. The original transmission problem is reduced to an equivalent nonlocal bound- ary value problem via introducing a Dirichlet-to-Neumann mapping by the direct boundary integral equation method. We show the existence and uniqueness of the solution for the corresponding variational equation. Numerical results based on the finite element method coupled with the standard Galerkin boundary element method, the fast multipole method and the NystrSm method for approximating the DtN mapping are provided to illustrate the efficiency and accuracy of the numerical schemes.

关键词： Fluid-solid interaction problem Dirichlet-to-Neumann mapping Finite element method Fast multipole method NystrSm method.

Galerkin Formulations of the Method of Fundamental Solutions

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Advances in Applied Mathematics and Mechanics 2013年第4期5卷 423-441页

作者： j.R.Berger andreas Karageorghis Department of Mechanical Engineering Colorado School of MinesGoldenCO 80401USA Department of Mathematics and Statistics University of CyprusP.O.Box 205371678 NicosiaCyprus

In this paper,we introduce two Galerkin formulations of theMethod of Fundamental Solutions(MFS).In contrast to the collocation formulation of the MFS,the proposed Galerkin formulations involve the evaluation of integrals over the boundary of the domain under *** the other hand,these formulations lead to some desirable properties of the stiffness matrix such as symmetry in certain *** numerical examples are considered by these methods and their various features compared.

关键词： Galerkin formulation Laplace equation method of fundamental solutions

Comparison of smoothness-constrained and geostatistically based cross-borehole electrical resistivity tomography for characterization of solute tracer plumes

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Water Science and Engineering 2016年第4期9卷 274-286页

作者： andreas Englert andreas Kemna j.n-feng Zhu j.n Vanderborght Harry Vereecken Tian-Chyi j.Yeh Institute of Geology Mineralogy and GeophysicsRuhr University Bochum Department of Geophysics Steinmann InstituteUniversity of Bonn Kentucky Geological Survey University of Kentucky Agrosphere Institute for Bio- and Geosciences(IBG-3)Forschungszentrum Jlich GmbH Department of Resources Engineering National Cheng Kung University Department of Hydrology and Water Resources The University of Arizona

Experiments using electrical resistivity tomography(ERT) have shown promising results in reducing the uncertainty of solute plume characteristics related to estimates based on the analysis of local point measurements *** explore the similarities and differences between two cross-borehole ERT inversion approaches for characterizing salt tracer plumes,namely the classical smoothness-constrained inversion and a geostatistically based approach,we performed two-dimensional synthetic *** assumptions about the solute transport model and the electrical forward and inverse model allowed us to study the sensitivity of the ERT inversion approaches towards a variety of basic conditions,including the number of boreholes,measurement schemes,contrast between the plume and background electrical conductivity,use of a priori knowledge,and point *** results show that geostatistically based and smoothness-constrained inversions of electrical resistance data yield plume characteristics of similar quality,which can be further improved when point measurements are incorporated and advantageous measurement schemes are *** expected,an increased number of boreholes included in the ERT measurement layout can highly improve the quality of inferred plume characteristics,while in this case the benefits of point conditioning and advantageous measurement schemes *** ERT inversion approaches are similarly sensitive to the noise level of the data and the contrast between the solute plume and background electrical conductivity,and robust with regard to biased input parameters,such as mean concentration,variance,and correlation length of the *** sophisticated inversion schemes have recently become available,in which flow and transport as well as electrical forward models are coupled,these schemes effectively rely on a relatively simple geometrical parameterization of the hydrogeological ***,we believe that standard uncoupled ER

关键词： Electrical resistivity tomography Inversion technique Solute tracer plume Synthetic experiment Plume characteristics

Source-specific risk assessment for cadmium in wheat and maize:Towards an enrichment model for China

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j.urnal of Environmental Sciences 2023年第3期125卷 723-734页

作者： Zhong Zhuang Qiqi Wang Siyu Huang Andrea Giovanna NinoSavala Yanan Wan Huafen Li andreas H.Schweiger andreas Fangmeier j.rgen Franzaring Beij.ng Key Laboratory of Farmland Soil Pollution Prevention and Remediation Key Laboratory of Plant-Soil Interactions of the Ministry of EducationCollege of Resources and Environmental SciencesChina Agricultural UniversityBeijing 100193China State Key Laboratory of North China Crop Improvement and Regulation Hebei Agricultural UniversityBaoding 071001China Institute of Landscape and Plant Ecology University of Hohenheim70599 StuttgartGermany

Cadmium (Cd) pollution of agricultural soil is of public concern due to its high potential toxicity and *** study aimed to reveal the risk of Cd accumulation in soil and wheat/maize systems,with a specific focus on the source-specific ecological risk,human health risk and Cd enrichment *** this we investigated more than 6100 paired soil and grain samples with 216 datasets including soil Cd contents,soil pH and grain Cd contents of 85 sites from *** results showed that mining activities,sewage irrigation,industrial activities and agricultural practices were the critical factors causing Cd accumulation in wheat and maize cultivated ***,mining activities contributed to a higher Cd accumulation risk in the southwest China and Middle Yellow River regions;sewage irrigation influenced the Cd accumulation in the North China *** addition,the investigated sites were classified into different categories by comparing their soil and grain Cd contents with the Chinese soil screening values and food safety values,*** enrichment models were developed to predict the Cd levels in wheat and maize *** results showed that the models exhibited a good performance for predicting the grain Cd contents among safe and warning sites of wheat (R2=0.61 and 0.72,respectively);while the well-fitted model for maize was prone to the overestimated sites (R2=0.77).This study will provide national viewpoints for the risk assessments and prediction of Cd accumulation in soil and wheat/maize systems.

关键词： Ecological risk Enrichment models Cadmium Health risk assessment Pollution sources

Dependence of impact regime boundaries on the initial temperatures of proj.ctiles and targets

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Defence Technology（防务技术） 2024年第1期31卷 49-57页

作者： Stefano Signetti andreas Heine Fraunhofer-Institut für Kurzzeitdynamik Ernst-Mach-InstitutEMIErnst-Zermelo-Str.479104 Freiburg im BreisgauGermany

Towards higher impact velocities,ballistic events are increasingly determined by the material *** effects might range from moderate thermal softening to full phase *** particular,it is of great interest to quantify the conditions for incipient or full melting of metals during impact interactions,which result in a transition from still strength-affected to hydrodynamic material *** this work,we investigate to which extent the respective melting thresholds are also dependent on the initial,and generally elevated,temperatures of proj.ctiles and targets before *** is studied through the application of a model developed recently by the authors to characterize the transition regime between high-velocity and hypervelocity impact,for which the melting thresholds of materials were used as the defining *** obtained results are expected to be of general interest for ballistic application cases where proj.ctiles or targets are *** conditions might result,for example,from aerodynamic forces acting onto a proj.ctile during atmospheric flight,explosive shapedcharge-j.t formation or armor exposure to environmental *** performed analyses also broaden the scientific understanding of the relevance of temperature in penetration events,generally known since the 1960s,but often not considered thoroughly in impact studies.

关键词： Ballistic impact Thermal effects Metallic targets Energy partitioning Homologous temperature