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Unveiling the inner structure of electron pulses generated from a laser-wakefield accelerator

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Light(Science & Applications) 2023年第10期12卷 1992-1994页

作者： malte c.Kaluza Institute of Optics and Quantum Electronics Max-Wien-Platz 107743JenaGermany Helmholtz-Institute Jena Fröbelstieg 307743JenaGermany

A novel diagnostic method has been used to gain deeper insight into the transverse structure and its evolution of electron pulses generated from a laser-wakefield accelerator.

关键词： structure field laser

Soft Sensors for Property‑controlled Multi‑Stage Press Hardening of 22MnB5

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Automotive Innovation 2023年第3期6卷 352-363页

作者： Juri Martschin malte Wrobel Joshua Grodotzki Thomas Meurer A.Erman Tekkaya Institute of Forming Technology and Lightweight components TU Dortmund UniversityBaroper Str.30344227 DortmundGermany Institute of Mechanical Process Engineering and Mechanics Karlsruhe Institute of Technology(KIT)Hertzstr.1676187 KarlsruheGermany

In multi-stage press hardening,the product properties are determined by the thermo-mechanical history during the sequence of heat treatment and forming *** measure these properties and finally to control them by feedback,two soft sensors are developed in this *** press hardening of 22MnB5 sheet material in a progressive die,where the material is first rapidly austenitized,then pre-cooled,stretch-formed,and finally die bent,serves as the framework for the development of these *** provide feedback on the temporal and spatial temperature distribution,a soft sensor based on a model derived from the Dynamic mode decomposition(DMD)is *** model is extended to a parametric DMD and combined with a Kalman filter to estimate the temperature(-distribution)as a function of all process-relevant control *** soft sensor can estimate the temperature distribution based on local thermocouple measurements with an error of less than 10°c during the process-relevant time *** the online prediction of the final microstructure,an artificial neural network(ANN)-based microstructure soft sensor is *** part of this,a transferable framework for deriving input parameters for the ANN based on the process route in multi-stage press hardening is presented,along with a method for developing a training database using a 1-element model implemented with LS-Dyna and utilizing the material model Mat248(PHS_BMW).The developed ANN-based microstructure soft sensor can predict the final microstructure for specific regions of the formed and hardened sheet in a time span of far less than 1 s with a maximum deviation of a phase fraction of 1.8%to a reference simulation.

关键词： Press hardening Property control Soft sensor Artificial neuronal network Dynamic mode decomposition

Get it white: color-tunable Ac/Dc OLEDs

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Light(Science & Applications) 2015年第1期4卷 492-497页

作者： Markus Frobel Tobias Schwab Mona Kliem Simone Hofmann Karl Leo malte c.gath.r Institute for Applied Photophysics(IAPP) Dresden University of TechnologyD-01069 DresdenGermany School of Physics and Astronomy University of St AndrewsSt Andrews KY169SSUK

Organic light-emitting diodes(OLEDs)have gained considerable attention because of their use of inherently flexible materials and their compatibility with facile roll-to-roll and printing *** addition to high efficiency,flexibility and transparency,reliable color tunability of solid state light sources is a desirable feature in the lighting and display ***,we demonstrate a device concept for highly efficient organic light-emitting devices whose emission color can be easily adjusted from deep-blue through cold-white and warm-white to saturated *** approach exploits the different polarities of the positive and negative half-cycles of an alternating current(Ac)driving signal to independently address a fluorescent blue emission unit and a phosphorescent yellow emission unit which are vertically stacked on top of each *** electrode design is optimized for simple fabrication and driving and allows for two-terminal operation by a single *** presented concept for color-tunable OLEDs is compatible with application requirements and versatile in terms of emitter combinations.

关键词： alternating current color mixing color tuning vertical stacking white organic light-emitting devices

Influence of humidity on conduction processes in gas-insulated devices

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High Voltage 2020年第2期5卷 143-150页

作者： malte Tschentscher David Graber christian M.Franck High Voltage Laboratory ETH Zurich8092 ZurichSwitzerland

Humidity has been considered as one of the main influencing factors that determine the conduction processes and electric strength of gas-insulated *** in the past,various studies focused on the change in the partial discharge inception voltages,breakdown strength of homogeneous and inhomogeneous field arrangements,and insulator flashover voltage,recent studies have investigated the changes in ion currents measured through different gas *** the framework of this contribution,a highly precise humidity control circuit has been developed to analyse the significance of humidity in the range from−25 to−5°c frost-point,which is fully applicable to operating gas-insulated *** sulphur hexafluoride(SF6)as the insulation gas at 0.45 MPa,Al2O3-filled epoxy resin insulators,and technically rough electrodes,the humidity was found to significantly influence the intensity of microdischarges at *** generation from microdischarges at the interfaces substantially increased with increasing *** an electric field of 5 kV/mm that were applicable to the dimensioning of gas-insulated devices,humidity strongly influences the charge provision from technically rough interfaces and potentially contributes to the surface-charge accumulation at insulator *** the other hand,for low-field conduction phenomena,no increase in the ion currents from natural ionisation or electrophoretic conduction was *** the investigated range of parameters,humidity is expected to be highly relevant for the design of gas-insulated devices.

关键词： conduction humidity sulphur

Modeling of the 3D spatio-temporal thermal profile of joule-class Yb3+-based laser amplifiers

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High Power Laser Science and Engineering 2019年第3期7卷 53-59页

作者： Issa Tamer Sebastian Keppler Jorg Komer Marco Hornung Marco Hellwing Frank Schorcht Joachim Hein malte c.Kaluza Helmholtz-Institute Jena Frobelstieg 307743 JenaGermany Friedrich-Schiller-University Jena Max-Wien Platz 107743 JenaGermany

Thermal profile modification of an active material in a laser amplifier via optical pumping results in a change in the material’s refractive index,and causes thermal expansion and stress,eventually leading to spatial phase aberrations,or even permanent material *** this purpose,knowledge of the 3D spatio-temporal thermal profile,which can currently only be retrieved via numerical simulations,is critical for joule-class laser amplifiers to reveal potentially dangerous thermal features within the pumped active *** this investigation,a detailed,spatio-temporal numerical simulation was constructed and tested for accuracy against surface thermal measurements of various endpumped Yb^3+-doped laser-active *** measurements and simulations show an excellent agreement and the model was successfully applied to a joule-class Yb3+-based amplifier currently operating in the POLArIS laser system at the Friedrich-Schiller-University and Helmholtz-Institute Jena in Germany.

关键词： diode-pumped solid-state lasers high intensity lasers laser amplifiers spatio-temporal thermal profile modeling ytterbium

Factors associated with long-term survival after liver transplantation:A retrospective cohort study

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World Journal of Hepatology 2017年第8期9卷 427-435页

作者： Sven Pischke Marie c Lege Moritz von Wulffen Antonio Galante Benjamin Otto malte H Wehmeyer Uta Herden Lutz Fischer Bjorn Nashan Ansgar W Lohse Martina Sterneck Department of Medicine I University Medical Center Hamburg-Eppendorf Department of Hepatobiliary and Transplant Surgery University Medical Center Hamburg-Eppendorf

AIM To identify predictive factors associated with long-term patient and graft survival(> 15 years) in liver transplant *** Medical charts of all de novo adult liver transplant recipients(n = 140) who were transplanted in Hamburg between 1997 and 1999 were retrospectively *** total,155 transplantations were identified in this time period(15 re-transplantations).Twenty-six orthotopic liver transplant(OLT) recipients were early lost to followup due to moving to other places within 1 year after *** remaining 114 patients were included in the *** following recipient factors were analysed:Age,sex,underlying liver disease,pre-OLT body mass index(BMI),and levels of alanine aminotransferase(ALT),bilirubin,creatinine and gammaglutamyltransferase(gamma-GT),as well as warm and cold ischemia ***,the following donor factors were assessed:Age,BMI,cold ischemia time and warm ischemia *** surviving patients were followed until December *** divided patients into groups according to their underlying diagnosis:(1) hepatocellularcarcinoma(n = 5,4%);(2) alcohol toxic liver disease(n = 25,22.0%);(3) primary sclerosing cholangitis(n = 6,5%);(4) autoimmune liver diseases(n = 7,6%);(5) hepatitis c virus cirrhosis(n = 15,13%);(6) hepatitis B virus cirrhosis(n = 21,19%);and(7) other(n = 35,31%).The group "other" included rare diagnoses,such as acute liver failure,unknown liver failure,stenosis and thrombosis of the arteria hepatica,polycystic liver disease,Morbus Osler and caroli *** The majority of patients were male(n = 70,61%).Age and BMI at the time point of transplantation ranged from 16 years to 69 years(median:53 years) and from 15 kg/m^2 to 33 kg/m^2(median:24),***-six OLT recipients(58%) experienced a follow-up of 15 years after ***'s age(P = 0.009) and BMI(P = 0.029) were identified as risk factors for death by χ~***-Meier analysis confirmed BMI or age ab

关键词： Liver transplantation Age Body mass index Long-term survival Hepatitis B

The all-diode-pumped laser system POLArIS——an experimentalist's tool generating ultra-high contrast pulses with high energy

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High Power Laser Science and Engineering 2014年第3期2卷 5-11页

作者： Marco Hornung Hartmut Liebetrau Andreas Seidel Sebastian Keppler Alexander Kessler Jrg Krner Marco Hellwing Frank Schorcht Diethard Klpfel Ajay K.Arunachalam Georg A.Becker Alexander Svert Jens Polz Joachim Hein malte c.Kaluza Helmholtz-Institute Jena Germany Institute of Optics and Quantum Electronics JenaGermany

The development,the underlying technology and the current status of the fully diode-pumped solid-state laser system POLArIS is ***,the POLArIS system delivers 4 J energy,144 fs long laser pulses with an ultra-high temporal contrast of 5 × 1012 for the ASE,which is achieved using a so-called double chirped-pulse amplification scheme and cross-polarized wave generation pulse *** tightly focusing,the peak intensity exceeds 3.5 × 1020 W *** parameters predestine POLArIS as a scientific tool well suited for sophisticated experiments,as exemplified by presenting measurements of accelerated proton ***,an additional amplifier has been added to the laser *** the ramp-up phase,pulses from this amplifier are not yet compressed and have not yet reached the anticipated ***,an output energy of 16.6 J has been achieved so far.

关键词： design high power laser laser amplifiers laser plasmas interaction laser systems modelling optimization ultra-intense ultrashort pulse laser interaction with matter

Diode-pumped, electro-optically Q-switched, cryogenic Tm:YAG laser operating at 1.88 μm

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High Power Laser Science and Engineering 2021年第1期9卷 107-112页

作者： J?rg K?rner Venkatesan Jambunathan Fangxin Yue Jürgen reiter Ondrej Slezák Petr Navrátil Samuel Paul David Antonio Lucianetti Joachim Hein Tomá? Mocek malte c.Kaluza HiLASE centre Institute of Physics of the Czech Academy of Sciences Institute of Optics and Quantum Electronics Friedrich Schiller University Jena Helmholz Institute Jena Hi LASE centre Institute of Physics of the Czech Academy of Sciences

We present a diode-pumped, electro-optically Q-switched Tm:YAG laser with a cryogenically cooled laser crystal at120 K. Output pulses of up to 2.55 mJ and 650 ns duration were demonstrated in an actively Q-switched configuration with a repetition rate of 1 Hz. By using cavity dumping the pulse duration was shortened to 18 ns with only a slightly lower output energy of 2.22 mJ. Furthermore, using a simplified rate equation model, we discuss design constraints on the pump fluence in a pulse pump approach for Tm:YAG to maximize the energy storage capability at a given pump power.

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Optimal c-arm angulation during transcatheter aortic valve replacement: Accuracy of a rotational c-arm computed tomography based three dimensional heart model

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World Journal of cardiology 2016年第10期8卷 606-614页

作者： Verena Veulemans Sabine Mollus Axel Saalbach Max Pietsch Katharina Hellhammer Tobias Zeus ralf Westenfeld Jürgen Weese malte Kelm Jan Balzer Department of Medicine Division of Cardiology Pulmonary Diseases Vascular Medicine University Hospital Düsseldorf Philips research Europe Philips GmbH Innovative Technologies Research Laboratories

AIM To investigate the accuracy of a rotational c-arm cTbased 3D heart model to predict an optimal c-arm configuration during transcatheter aortic valve replacement(TAVr). METHODS rotational c-arm cT(rcT) under rapid ventricular pacing was performed in 57 consecutive patients with severe aortic stenosis as part of the pre-procedural cardiac catheterization. With prototype software each rcT data set was segmented using a 3D heart model. From that the line of perpendicularity curve was obtained that generates a perpendicular view of the aortic annulus according to the right-cusp rule. To evaluate the accuracy of a model-based overlay we compared model- and expert-derived aortic root diameters. rESULTS For all 57 patients in the rcT cohort diameter measurements were obtained from two independent operators and were compared to the model-based measurements. The inter-observer variability was measured to be in the range of 0°-12.96° of angular c-arm displacement for two independent operators. The model-to-operator agreement was 0°-13.82°. The model-based and expert measurements of aortic root diameters evaluated at the aortic annulus(r = 0.79, P rtic sinus(r = 0.93, P r junction(r = 0.92, P correlated on a high level and the Bland-Altman analysis showed good agreement. The interobserver measurements did not show a significant bias. cONcLUSION Automatic segmentation of the aortic root using an anatomical model can accurately predict an optimal c-arm configuration, potentially simplifying current clinical workflows before and during TAVr.

关键词：大动脉的狭窄成像形式退化阀门疾病 Transcatheter 大动脉的阀门代替