检索结果-南通市图书馆

laser-induced plasma formation in water with up to 400 mJ double-pulse LIBS

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Plasma Science and Technology 2024年第1期26卷 93-100页

作者： Marion HeNKeL Michelle SIeMeNS Ralf MeTHLING Benjamin eMDe Jörg HeRMSDORF Steffen FRANKe Diego GONZALeZ Leibniz Institute for Plasma Science and Technology(INP) Felix-Hausdorff-Straße 2Greifswald 17489Germany laser Zentrum Hannover e.v.(LZH) Hollerithallee 8Hannover 30419Germany

Double-pulse LIBS is a promising technique for deep-sea *** measurements in shallow water with up to 400 mJ each pulse were done to select laser parameters which promote optimized spectral line emission from plasma even at elevated pressures,where line broadening until loss of most of the spectral information can *** emission spectroscopy,using a Czerny-Turner spectrometer,has been applied to investigate the dependence of the emitted radiation on laser parameters and hydrostatic *** has been found,that higher laser pulse energies,especially with short pulse delay as required in high water pressure,can also have an adverse effect on the measured spectrum.

关键词： double-pulse LIBS underwater plasma formation emission spectrosocpy

维普期刊数据库

Spatial separation effects in a guiding procedure in a modified ion-beam-sputtering process

在线全文

学校读者我要写书评

暂无评论

Light(Science & Applications) 2015年第1期4卷 109-116页

作者： Sina Malobabic Marco Jupé Detlev Ristau laser Zentrum Hannover e.v. Hollerithallee 8D-30419 HannoverGermany QUeST:Centre for Quantum engineering and Space-Time Research Leibniz Universität HannoverHannoverGermany

In the present state of the art,ion beam sputtering is used to produce low-loss dielectric *** the manufacturing of a dielectric layer stack,the deposition material must be changed,which requires rapid mechanical movement of vacuum *** mechanical components can be regarded as a risk factor for contamination during the coating process,which limits the quality of high-end laser *** minimize the particle contamination,we present a novel deposition concept that does not require movable components to change the coating material during the coating process.A magnetic field guiding technique has been developed,which enables the tuning of the refractive index in the layer structure by sputtering mixtures with varying compositions of two materials using a single-ion *** versatility of this new concept is demonstrated for a highreflection mirror.

关键词： eM field separation ion beam sputtering plasma guiding

Graphite Nucleation in Cast Iron Melts Based on Solidification experiments and Microstructure Simulation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2008年第3期24卷 321-324页

作者： Andreia Sommerfeld Bernd Bttger Babette Tonn Institute of Metallurgy Clausthal University of TechnologyClausthal-Zellerfeld ACCeSS e.v. Intzestr.552072 Aachen

Microstructure strongly influences the mechanical properties of cast iron. By inoculating the melt with proper inoculants, foreign substrates are brought into the melt and eventually the graphite can crystallize on them. The elements and substrates that really play a role for nucleation are yet unknown. Until now there is very little knowledge about the fundamentals of nucleation, such as composition and morphology of nuclei. In this work we utilized eN-GJL-200 as a base material and examined several produced specimens. The specimens were cast with and without inoculants and quenched at different solidification states. Specimens were also examined with a high and low oxygen concentration, but the results showed that different oxygen contents have no influence on the nucleation in cast iron melts. Our research was focused on the microscopic examination and phase-field simulations. For studying the samples we applied different analytical methods, where SeM-eDS, -WDS were proved to be most effective. The simulations were conducted by using the software MICReSS, which is based on a multiphase-field model and has been coupled directly to the TCFe3 thermodynamic database from TCAB. On the basis of the experimental investigations a nucleation mechanism is proposed, which claims MnS precipitates as the preferred site for graphite nucleation. This theory is supported by the results of the phase-field simulations.

关键词： Graphite nucleation Cast iron melts Solidification Microstructure simulation

维普期刊数据库

Boosting propane dehydrogenation by gallium hydride species formed in situ

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2024年第6期67卷 1753-1755页

作者： evgenii v.Kondratenko Leibniz-Institut für Katalyse e.v. Albert-Einstein-Str.29aRostock18059Germany

An inspiring paper recently published in Nature Chemistry[1]by the group of *** Gong at Tianjin University is the motivation for this highlight *** reported results show that the understanding of reaction-induced restructuring of heterogeneous catalysts is of great importance for their targeted development because usually unstable compounds can be formed and stabilized under reaction conditions.

关键词： conditions hydride stabilized

维普期刊数据库

Relativistic-intensity near-single-cycle light waveforms at kHz repetition rate

在线全文

学校读者我要写书评

暂无评论

Light(Science & Applications) 2020年第1期9卷 1572-1580页

作者： Marie Ouille Aline.v.rnier Frederik Bohle Maimouna Bocoum Aurelie Jullien Magali Lozano Jean-Philippe Rousseau Zhao Cheng Dominykas Gustas Andreas Blumenstein Peter Simon Stefan Haessler Jerome Faure Tamas Nagy Rodrigo Lopez-Martens Laboratoire d’Optique Appliquee CNRSEcole PolytechniqueENSTA ParisInstitut Polytechnique de Paris181 chemin de la Huniere et des Joncherettes91120 PalaiseauFrance Ardop engineering Cite de la Photonique11 Avenue de la Canterannebat.Pleione33600 PessacFrance laser-laboratorium gottingen e.v. Hans-Adolf-Krebs-Weg 137077 GottingenGermany Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy Max-Born-Strasse 2A12489 BerlinGermany

The development of ultra-intense and ultra-short light sources is currently a subject of intense research driven by the discovery of novel phenomena in the realm of relativistic optics,such as the production of ultrafast energetic particle and radiation beams for *** has been a long-standing challenge to unite two hitherto distinct classes of light sources:those achieving relativistic intensity and those with pulse durations approaching a single light *** the former class traditionally involves large-scale amplification chains,the latter class places high demand on the spatiotemporal control of the electromagnetic laser ***,we present a light source producing waveformcontrolled 1.5-cycle pulses with a 719 nm central wavelength that can be focused to relativistic intensity at a 1 kHz repetition rate based on nonlinear post-compression in a long hollow-core *** unique capabilities of this source allow us to obse.v. the first experimental indications of light waveform effects in laser wakefield acceleration of relativistic energy electrons.

关键词： repetition intensity light

Human Performance in Critical Scenarios as a Benchmark for Highly Automated vehicles

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Automotive Innovation 2021年第3期4卷 274-283页

作者： Laura Quante Meng Zhang Katharina Preuk Caroline Schießl Institute of Transportation Systems German Aerospace Center(DLR e.V.)Lilienthalplatz 738108 BraunschweigGermany

Before highly automated vehicles(HAvs)become part of everyday traffic,their safety has to be *** use of human performance as a benchmark represents a promising approach,but appropriate methods to quantify and compare human and HAv performance are *** adapting the method of constant stimuli,a scenario-based approach to quantify the limit of(human)performance is *** method is applied to a driving simulator study,in which participants are repeatedly confronted with a cut-in manoe.v.e on a *** systematically manipulating the criticality of the manoe.v.e in terms of time to collision,humans’collision avoidance performance is *** limit of human performance is then identified by means of logistic *** calculated regression curve and its inflection point can be used for direct comparison of human and HAv ***,the presented approach represents one means by which HAvs’safety performance could be proven.

关键词： Highly automated vehicles Automated driving Proof of safety Human performance Driving performance

Advanced control and modeling of deposition processes

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Optics Letters 2013年第13期11卷 30-35页

作者： Detlev Ristau Henrik ehlers Centre of Quantum engineering and Space-Time Research Hannover Germany Department of laser Components Laser Zentrum Hannover e.V. Hannover Germany

During the last decade, striking improvements could be achieved for the precise control of deposition processes in optical coating technology. For example, as a consequence of enormous progresses in measure- ment and computer technology, direct optical monitoring in a broad spectral range can be considered as a common tool in many production e.v.ronments nowadays. Besides the development of the corresponding hardware and measurement channels, advanced approaches for the evaluation of the acquired data and new multiple sensor monitoring strategies moved into the focus of modern research on the way towards de- terministic deposition techniques. In this context, also innovative concepts for the simulation of deposition processes to forecast the result for a specified coating design and automatic online correction algorithms gained of importance to reduce the risk of failure in coating production. The present contribution will be dedicated to selected aspects in this field, especially addressing broad band optical monitoring systems. A short review on examples for existing hardware configurations and software tools will be presented illus- trating the advantages of modern process control techniques. Novel approaches based on the modeling of thin film growth are discussed as an additional strategy to improve the predictability of coating processes.

关键词： 310.1860 Deposition and fabrication 310.6845 Thin film devices and applications 280.4788 Optical sensing and sensors

Palladium-catalysed efficient synthesis of primary alkyl halides from terminal and internal alkenes

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

National Science Review 2022年第12期9卷 63-65页

作者： Han-Jun Ai Matthias Beller Xiao-Feng Wu Dalian National Laboratory for Clean energy Dalian Institute of Chemical Physics Chinese Academy of Sciences Leibniz-Institut für Katalyse e.v.

The development of remote functionalization of alkenes has recently gained considerable attention as it offers the op-portunity to directly transform a mixture of unrefined olefin isomers into a single.v.luable fine c...

关键词：

Self-assembled formation of long, thin, and uncoalesced GaN nanowires on crystalline TiN films

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Nano Research 2018年第1期11卷 565-576页

作者： David van Treeck Gabriele Calabrese Jelle J. W. Goertz vladimir M. Kaganer Oliver Brandt Sergio Fernandez-Garrido, Lutz Geelhaar PauI-Drude-lnstitut f~r Festk6rperelektronik Leibniz-lnstitut im Forschungsverbund Berlin e.V. Hausvogteiplatz 5-7 I 0117 Berlin Germany

We investigate in detail the self-assembled nucleation and growth of vertically oriented GaN nanowires by molecular beam epitaxy on crystalline TiN films. We demonstrate that this type of substrate allows for the growth of long and thin GaN nanowires that do not suffer from coalescence, a problem common to the growth on Si and other substrates. Only beyond a certain nanowire length that depends on the nanowire density and exceeds here 1.5 bun, coalescence takes place by bundling, i.e. the same process as on Si. By analyzing the nearest neighbor distance distribution, we identify the diffusion-induced repulsion of neighboring nanowires as the main mechanism limiting nanowire density during nucleation on TiN. Since on Si the final density is determined by shadowing of the impinging molecular beams by existing nanowires, it is the difference in adatom surface diffusion that enables the formation of nanowire ensembles with reduced density on TiN. These nanowire ensembles combine properties that make them a promising basis for the growth of core-shell heterostructures.

关键词： nanocolumn gallium nitride nucleation metal substrate coalescence core-shell