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Sc元素添加对双辊铸轧Al−Cu−Li−Mg−Zr基合金热处理的影响

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Transactions of Nonferrous Metals Society of China 2024年第6期34卷 1759-1773页

作者： Rostislav KRÁLÍK Barbora KŘIVSKÁ Lucia BAJTOŠOVÁ Mykhailo STOLBCHENKO Mirko SCHAPER Olexandr GRYDIN Miroslav CIESLAR Department of Physics of Materials Faculty of Mathematics and PhysicsCharles UniversityKe Karlovu 512116PragueCzech Republic Department of Materials Science Faculty of Mechanical EngineeringUniversity of PaderbornWarburger Straße 10033098PaderbornGermany

提出制备含Sc的Al−Cu−Li−Mg−Zr基合金带材的工艺方案。即先采用双辊铸轧技术制备近净形状的3 mm厚带材,再对其进行均匀化/固溶处理。研究两种Al−Cu−Li−Mg−Zr基双辊铸轧合金,其中一种添加质量分数为0.17%的Sc,另一种未添加Sc。两种合金... 详细信息

提出制备含Sc的Al−Cu−Li−Mg−Zr基合金带材的工艺方案。即先采用双辊铸轧技术制备近净形状的3 mm厚带材,再对其进行均匀化/固溶处理。研究两种Al−Cu−Li−Mg−Zr基双辊铸轧合金,其中一种添加质量分数为0.17%的Sc,另一种未添加Sc。两种合金均先在300℃下退火30 min,然后在450℃下退火30 min以及530℃下退火30 min,随后进行室温水淬。前两段退火后组织中生成了细小、弥散的Al_(3)Zr/Al_(3)(Sc,Zr)颗粒。最后的退火步骤起到了均匀化/固溶处理的作用。双辊铸轧材料的细小晶粒结构使含有主要合金元素的原始颗粒在较短的退火时间内溶解。缩短保温时间可以限制表面层中Li的耗尽和Al_(3)Zr/Al_(3)(Sc,Zr)弥散相的明显粗化。铸态含Sc材料已经具有明显细小的晶粒结构,而经均匀化/固溶处理后生成的Al_(3)(Sc,Zr)弥散相抑制了晶粒在高温下发生粗化。在后续180℃下时效处理后,形成了θʹ(Al_(2)Cu)、T1(Al_(2)CuLi)和S'(Al_(2)CuMg)强化相。在峰值时效状态下,屈服强度提高了200 MPa,这一数值与类似直接冷却铸造材料的相当,从而证实了所提方案的合理性。

关键词：显微组织力学性能 Al−Cu−Li基合金 Sc合金化双辊铸轧

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A Population Balance Model for Disperse Systems:Particle Size Distribution in Suspension Polymerization

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Chinese Journal of Chemical Engineering 1999年第4期7卷 332-344页

作者：陈中 Werner Pauer H.-U.Moritz Jan Prss Hans-Joachim Warnecke Chemical Engineering University of PaderbornPaderborn 33098Germany

On the basis of population balance a mathematical model is developed to describe the formation of polymer particle in styrene suspension polymerization. The characteristics of coalescence and breakage of droplets and the gel effect are analyzed in particular. Parameters of the models are estimated by experimental data on reaction conversion and particle size distribution. The results show that the model is suitable for predicting polymerization processes.

关键词： population balance model styrene suspension polymerization particle size distribution

Nonlinear optics in all-dielectric nanoantennas and metasurfaces:a review

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Advanced Photonics 2019年第2期1卷 20-33页

作者： Basudeb Sain Cedrik Meier Thomas Zentgraf university of paderborn Department of PhysicsPaderbornGermany

Free from phase-matching constraints,plasmonic metasurfaces have contributed significantly to the control of optical nonlinearity and enhancement of nonlinear generation efficiency by engineering subwavelength ***,high dissipative losses and inevitable thermal heating limit their applicability in nonlinear ***-dielectric metasurfaces,supporting both electric and magnetic Mie-type resonances in their nanostructures,have appeared as a promising alternative to nonlinear ***-index dielectric nanostructures,allowing additional magnetic resonances,can induce magnetic nonlinear effects,which,along with electric nonlinearities,increase the nonlinear conversion *** addition,low dissipative losses and high damage thresholds provide an extra degree of freedom for operating at high pump intensities,resulting in a considerable enhancement of the nonlinear *** discuss the current state of the art in the intensely developing area of all-dielectric nonlinear nanostructures and metasurfaces,including the role of Mie modes,Fano resonances,and anapole moments for harmonic generation,wave mixing,and ultrafast optical ***,we review the recent progress in the nonlinear phase and wavefront control using all-dielectric *** discuss techniques to realize alldielectric metasurfaces for multifunctional applications and generation of second-order nonlinear processes from complementary metal–oxide–semiconductor-compatible materials.

关键词： nonlinear optics dielectric metasurfaces Mie modes Fano resonances anapole modes harmonic generation

Metasurfaces help lasers to mode-lock

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Light(Science & Applications) 2020年第1期9卷 1384-1386页

作者： Basudeb Sain Thomas Zentgraf Department of Physics Paderborn University33098 PaderbornGermany

Metasurface saturable absorbers may result in versatile mode-locking that allows one to obtain stable ultrashort laser pulses with high repetition rates and peak powers,along with broadband operation,within fiber to s... 详细信息

关键词： laser fiber ultrashort

Photovoltaic yield prediction using an irradiance forecast model based on multiple neural networks

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Journal of Modern Power Systems and Clean Energy 2018年第2期6卷 255-267页

作者： Saad Parvaiz DURRANI Stefan BALLUFF Lukas WURZER Stefan KRAUTER paderborn university Bosch Thermotechnik GmbH

In order to develop predictive control algorithms for efficient energy management and monitoring for residential grid connected photovoltaic systems, accurate and reliable photovoltaic(PV) power forecasts are required.A PV yield prediction system is presented based on an irradiance forecast model and a PV model. The PV power forecast is obtained from the irradiance forecast using the PV model. The proposed irradiance forecast model is based on multiple feed-forward neural networks. The global horizontal irradiance forecast has a mean absolute percentage error of 3.4% on a sunny day and 23% on a cloudy day for Stuttgart. PV power forecasts based on the neural network irradiance forecast have performed much better than the PV power persistence forecast model.

关键词： Grid connected photovoltaic(GCPV) Photovoltaic(PV) PV power prediction Irradiance forecast Neural network(NN)

A THEORETICAL MODEL OF MATRIX CRACKING IN COMPOSITE LAMINATES UNDER THERMOMECHANICAL LOADING

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Acta Mechanica Solida Sinica 2001年第4期14卷 299-305页

作者： Herrmann K.P. Laboratory for Technical Mechanics University of PaderbornPohlweg 47-4933098 PaderbornGermany

A theoretical approach is presented for analyzing the ply crackingin general symmetric lami- nates subjected to any combination ofin-plane mechanical loading and uniform temperature changes. Theequivalent constraint model proposed by the authors in a previouswork is used to account for the cracking in- teraction betweenlaminae in the laminates. By using a superposition schemce and thestress field solutions the energy release rate for a ply cracking isexplicitly as a function of stiffness reduction parameters of thelaminates. The ratio of mode Ⅰ to mode Ⅱ is introduced formconstruction of the fracture criterion. The effects of the laminateparameters and the crack spacing on the energy release rate and themode mixity are illustrated. Finally, the model is used to predictthe thermomechanical load for the first-ply-cracking.

关键词： thermomechanical load intralaminar cracking general lay-ups and mixed mode

State of the Art and Perspectives of Hydroforming of Tubes and Sheets

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Journal of Materials Science & Technology 2001年第3期17卷 321-324页

作者： F. Vollertsen Department for Metal Forming Technologies, university paderborn, paderborn, Germany E-mail: fv@luf.upb.de Dept. for Metal Forming Technol. Univ. Paderborn Paderborn Germany

Hollow parts of high accuracy and high strength can be produced by forming methods using liquid media. Hydroforming of tubes has reached a high standard for small parts (volume some 1000 cm3) and is further developed for larger parts (volume some 10.000 cm3). Processes for hydraulic sheet metal forming are sometimes used for small parts from single sheets These pro-cesses are currently under intensive investigation, which is also true for the processing of double layered sheets Single sheets can be formed using membranes which separate the workpiece and the liquid. This results in interesting possibilities for a part and process integration in one step The forming performance of aluminum alloys can be enhanced by using a heated liquid media when forming without membranes.

关键词： State of the Art and Perspectives of Hydroforming of Tubes and Sheets

Investigations on the aging behavior of transparent bioplastics for optical applications

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InfoMat 2020年第2期2卷 424-433页

作者： Jana Baltscheit Nico Schmidt Finn Schröder Jörg Meyer Photonics and Materials Science Hamm-Lippstadt University of Applied ScienceLippstadtGermany Department of Natural Science Paderborn UniversityPaderbornGermany

In this study,the optical properties of transparent bioplastics have been *** long-term technological goal is to establish biopolymers in a new market segment for demanding optical applications and to contribute to a more sustainable economy.A collection of transparent bioplastics has been tested with respect to the long-term stability and the possibility of an application in optical components for LED *** focus of materials testing was on the influence of short wavelength visible radiation as well as thermal *** results show,that some materials may be candidates for subsequent feasibility *** the best of our knowledge,the application of such polymers in complex technical products and in particular in luminaires has not yet been *** use of bio-based plastics for optical components therefore represents a novelty and has a high development potential.

关键词： (blue)LED irradiance (photo)degradation biobased plastics renewable materials transparent optics

Design and Fabrication of 2-DOF Micromirror Array Based on Electro-Thermal Actuators

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Journal of Beijing Institute of Technology 2006年第2期15卷 211-215页

作者：蒋剑良 HILLERINGMANN Ulrich School of Information Science and Technology Beijing Institute of Technology Fachgebiet Sensorik University of Paderborn D-33098 Paderborn Germany

With surface- and bulk-micromachining, an 8 × 8 mirrors array is designed, fabricated and tested, which is based on electro-thermal actuators and can be addressed individually. The micromirror is square shaped, 4-corner-actuated. Its dimension is 200 μm × 200 μm. The substrate below it is caved away to ensure a tilt at an angle as large as possible. To protect the etch-sensitive features on the front side of the wafer undamaged during wet deep silicon etch on the backside, the wax protective coating process is used. Mirror actuated by powering an alternative pair of heaters will tilt in 2-DOF. If its 4 cantilevers/heaters are powered synchronously, it will move in a piston mode. The effective arrays are more than 80% out of the three finished wafers. When the ramp voltage frequency applied to a pair of neighboring cantilevers is 5 Hz at 10 V, the average tilting angle can be ± 8°.

关键词： micromirror array electro-thermal actuator microfabrication chemical wet etch