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Dependence of impact regime boundaries on the initial temperatures of projectiles 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 projectiles 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 projectiles or targets are *** conditions might result,for example,from aerodynamic forces acting onto a projectile during atmospheric flight,explosive shapedcharge-jet 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

Snapshot imaging of ultrashort electron bunches

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Light(Science & Applications) 2024年第7期13卷 1226-1228页

作者： andreas Döpp Ludwig-Maximilian-Universität München Am Coulombwall 185748GarchingGermany Max Planck Institut für Quantenoptik Hans-Kopfermann-Strasse 1Garching85748Germany

New measurements combine spatial and temporal information from optical transition radiation to estimate the three-dimensional structure of electron bunches from a laser wakefield accelerator.

关键词： ultrashort Snapshot electron

The interaction between a shaped charge jet and a single moving plate

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Defence Technology（防务技术） 2024年第1期31卷 1-13页

作者： andreas Helte Jonas Lundgren Jonas Candle FOI WeaponsProtection and SecuritySE-16490StockholmSweden

Reactive armour is a very efficient add-on armour against shaped charge *** reactive armour consists of one or several plates that are accelerated by an *** but less violent acceleration of plates can also be achieved in a completely inert reactive *** be efficient against elongated jets,the motion of the plates needs to be inclined against the jet such that a sliding contact between the jet and the plates is *** sliding contact causes a deflection and thinning of the *** certain circumstances,the contact will become unstable,leading to severe disturbances on the *** disturbances will drastically reduce the jet penetration performance and it is therefore of interest to study the conditions that leads to an unstable *** studies on the interaction between shaped charge jets and flyer plates have shown that it is mainly the forward moving plate in an explosive reactive armour that is effective in disturbing the *** is usually attributed to the higher plate-to-jet mass flux ratio involved in the collision of the forward moving plate compared to the backward moving *** slow moving plates,as occurs in inert reactive armour,the difference in mass flux for the forward and backward moving plate is much lesser,and it is therefore of interest to study if other factors than the mass flux influences on the protection *** this work,experiments have been performed where a plate is accelerated along its length,interacting with a shaped charge jet that is fired at an oblique angle to the plate’s normal,either against or along the plate’s *** arrangement corresponds to a jet interacting with a flyer plate from a reactive armour,with the exception that the collision velocity is the same for both types of obliquities in these *** experiments show that disturbances on the jet are different in the two cases even though the collision velocities are the *** simulatio

关键词： Reactive armour Flyer plate Shaped charge jet

Note on:“Ballistic model for the prediction of penetration depth and residual velocity in adobe:A new interpretation of the ballistic resistance of earthen masonry”

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Defence Technology（防务技术） 2024年第1期31卷 607-609页

作者： andreas Heine Matthias Wickert Fraunhofer EMI Ernst-Zermelo-Str.479104FreiburgGermany

A recently published modeling approach for the penetration into adobe and previous approaches implicitly criticized are reviewed and *** article contains a note on the paper titled“Ballistic model for the prediction of penetration depth and residual velocity in adobe:A new interpretation of the ballistic resistance of earthen masonry”(DOI:https://***/10.1016/***.2018.07.017).Reply to the Note from Li Piani et al is linked to this article.

关键词： adobe prediction earth

REGENERATION FACTOR 1, a peptide boost for wound healing and plant biotechnology

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Molecular Plant 2024年第9期17卷 1333-1334页

作者： andreas Schaller University of Hohenheim Department of Plant Physiology and Biochemistry70593 StuttgartGermany

Plants respond to wounding such as caused by insect herbivores by activating their defenses and thus increasing their resistance against attacking pests and opportunistic pathogens(Howe and Schaller,2008).The phenomenon was first described more than 50 years ago by Green and Ryan,who reported that wounding triggers tomato and potato plants to produce proteinase inhibitors that inhibit digestive proteases in the gut of leaf-eating insects to starve them of nutrients(Green and Ryan,1972).They also observed that the accumulation of proteinase inhibitors is not restricted to wounded leaves but occurs throughout the aerial parts of the *** search for a chemical signal that is released locally in response to wounding and that mediates systemic activation of defense gene expression led to the identification of systemin,the first ever peptide with hormonelike activity in plants(Pearce et al.,1991).These seminal findings sparked much research into systemic defense responses and peptide signaling in general,and we know now that systemin is one of many phytocytokines that regulate a multitude of immune responses in plants(Schilmiller and Howe,2005;Gust et al.,2017).

关键词： wound activation defense

Odd-even effects in the structure and properties of aryl-substituted aliphatic self-assembled monolayers

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Nano Research 2024年第5期17卷 4231-4243页

作者： Piotr Cyganik andreas Terfort Michael Zharnikov Jagiellonian University Faculty of PhysicsAstronomy and Applied Computer ScienceSmoluchowski Institute of PhysicsŁojasiewicza 1130-348 KrakówPoland Institut für Anorganische und Analytische Chemie Universität FrankfurtMax-von-Laue-Straße 760438 FrankfurtGermany Applied Physical Chemistry Heidelberg UniversityIm Neuenheimer Feld 25369120 HeidelbergGermany

Self-assembled monolayers(SAMs)represent an important tool in context of nanofabrication and molecular engineering of surfaces and *** properties of functional SAMs depend not only on the character of the tail groups at the SAM-ambient interface,but are also largely defined by their *** its turn,the latter parameter results from a complex interplay of the structural forces and a variety of other factors,including so called odd-even effects,*** of the SAM structure and properties on the parity of the number(odd or even)of individual building blocks in the backbone of the SAM *** most impressive manifestation of the odd-even effects is the structure of aryl-substituted alkanethiolate SAMs on Au(111)and Ag(111),in which,in spite of the fact that the intermolecular interaction is mostly determined by the aryl part of the monolayers,one observes a pronounced dependence of molecular inclination and,consequently,the packing density of the SAM-forming molecules on the parity of number of methylene units in the alkyl *** we review the properties of the above systems as well as address fundamental reasons behind the odd-even effects,including the existence of a so-called bending potential,which is frequently disregarded in analysis of the structure-building *** generality of the odd-even effects in SAMs is additionally supported by the recent data for SAMs on GaAs,scanning tunneling microscopy data for SAMs on Ag(111),and the data for the monolayers with selenolate and carboxyl anchoring groups on Au(111)and Ag(111).The implications of these effects in terms of the control over the packing density and orientation of the tail groups at the SAM-ambient interface,structural perfection,polymorphism,temperature-driven phase transitions,and SAM stability toward such factors as ionizing radiation,exchange reaction,and electrochemical desorption are *** implications place the odd-even effects as an important tool

关键词： self-assembled monolayers molecular films surface and interface engineering odd-even-effects

Optimal Offering of Energy Storage in UK Day-Ahead Energy and Frequency Response Markets

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Journal of Modern Power Systems and Clean Energy 2024年第2期12卷 415-426页

作者： Makedon Karasavvidis andreas Stratis Dimitrios Papadaskalopoulos Goran Strbac Department of Electrical and Electronic Engineering Imperial College LondonLondonUK Statkraft UK Ltd. LondonUK Department of Electrical and Computer Engineering University of PatrasPatrasGreece IEEE

The offering strategy of energy storage in energy and frequency response(FR) markets needs to account for country-specific market regulations around FR products as well as FR utilization factors, which are highly uncertain. To this end, a novel optimal offering model is proposed for stand-alone price-taking storage participants, which accounts for recent FR market design developments in the UK, namely the trade of FR products in time blocks, and the mutual exclusivity among the multiple FR products. The model consists of a day-ahead stage, devising optimal offers under uncertainty, and a real-time stage, representing the storage operation after uncertainty is materialized. Furthermore, a concrete methodological framework is developed for comparing different approaches around the anticipation of uncertain FR utilization factors(deterministic one based on expected values, deterministic one based on worst-case values, stochastic one, and robust one), by providing four alternative formulations for the real-time stage of the proposed offering model, and carrying out an out-of-sample validation of the four model instances. Finally, case studies employing real data from UK energy and FR markets compare these four instances against achieved profits, FR delivery violations, and computational scalability.

关键词： Energy markets energy storage frequency response optimal offering robust optimization stochastic programming