检索结果-内蒙古大学图书馆

Edge recombination analysis of silicon solar cells using photoluminescence measurements

AIP Conference Proceedings 2019年第1期2147卷

作者： Hannah Stolzenburg Andreas Fell Florian Schindler Wolfram Kwapil Armin Richter Puzant Baliozian Martin C. Schubert 1Fraunhofer Institute for Solar Energy Systems ISE Heidenhofstraße 2 79110 Freiburg Germany 2University Freiburg Department of Sustainable Systems Engineering (INATECH) Emmy-Noether-Str. 2 79110 Freiburg Germany

Edge losses in silicon solar cells are becoming more important in current photovoltaic research, especially in shingled cell modules with high perimeter to area ratios. Hence, in this study a new approach is presented to quantify edge recombination losses by using photoluminescence (PL) measurements combined with device modelling. The main focus of this work is to determine and separate the contribution of the two relevant edge recombination losses: (i) recombination at the bulk edge, described by an effective surface recombination velocity Seff,edge, and (ii) recombination at the pn-junction edge, described by an edge-length specific non-ideal recombination parameter J02,edge. For this purpose, the PL gradient towards the edge at different illumination intensities is fitted by Quokka3 simulations. The developed method is applied for differently separated unpassivated edges, namely by thermal laser separation (TLS) and by mechanical cleaving. Additionally, an emitter window for the TLS edge is introduced where no pn-junction at the edge is present. It was found that the emitter window results in less edge recombination while having the same bulk-edge recombination properties as without. As a result, J02,edge = 3 nA/cm and Seff,edge = 105 cm/s are determined for the TLS edge without emitter window while the mechanically cleaved edge showed higher edge recombination.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Sol-gel method for synthesis of Li+-stabilized Na-β”-alumina for solid electrolytes in sodium-based batteries

引用

AIP Conference Proceedings 2019年第1期2175卷

作者： Anisa I. Agustina Karl Skadell Cornelius L. Dirksen Matthias Schulz Samuel P. Kusumocahyo 1Department of Chemical Engineering Swiss German University The Prominence Tower Alam Sutera Tangerang 15143 Indonesia 2Fraunhofer Institute for Ceramics Technologies and Systems IKTS Hermsdorf 07629 Germany

Li+-stabilized Na-β”-alumina was synthesized through sol-gel based on the Pechini method with Al(NO3)3, NaNO3, and LiNO3 as the metal precursor. Evaluations were done to several different sodium content in order to counterbalance Na2O losses during sintering, as well as different sintering temperature between 1500 – 1700 °C. The evaluations were done by density measurement, impedance spectroscopy, X-ray diffraction, and Scanning Electron Microscopy. The synthesized powder exhibits Na-β”-alumina with measured relative density up to 2.96±0.01 g/cm3. The ionic conductivity achieved was up to 0.23 S/cm at 300 °C with lowest activation energy for conduction of 0.17 eV. Moreover, the Na-β”-alumina phase content achieved was up to 84%.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Guided support for collaborative modeling, enactment and simulation of software development processes

引用

Software Process: Improvement and Practice 2004年第2期9卷

作者： Alejandro Fernández Badie Garzaldeen Ines Grützner Jürgen Münch Laboratorio de Investigación y Formación en Informática Avanzada Facultad de Informática Universidad Nacional de La Plata Argentina Fraunhofer Institute for Integrated Publication and Information Systems (IPSI) in Darmstadt Germany Fraunhofer Institute for Experimental Software Engineering (IESE) in Kaiserslautern Germany

Recently, the awareness of the importance of distributed software development has been growing in the software engineering community. Economic constraints, more and more outsourcing of development activities, and the increasing geographical distribution of companies come along with challenges of how to organize distributed development. In this article, we reason that a common process understanding is mandatory for successful distributed development. Integrated process planning, guidance and enactment are seen as enabling technologies for achieving a unique process view. We present an overview of the software process modeling environment SPEARMINT and the XCHIPS system for web-based process support. SPEARMINT offers extensive capabilities for multi-view modeling and analysis of software development processes. XCHIPS provides capabilities for distributed modeling and offers enactment and simulation functionalities. This article describes the integration of both approaches. The resulting environment provides planners and developers with collaborative planning and enactment support and advanced process guidance via electronic process guides (EPGs). Additionally, experience with the integrated environment is described. We describe, in particular, the usage of this integrated environment in the context of a case study for the development of a learning system. Finally, an overview of related work is given and future research directions are sketched. Copyright © 2004 John Wiley & Sons, Ltd.

关键词： software process modeling distributed development distributed software project management project planning project enactment

来源：评论

学校读者我要写书评

暂无评论

Multi-parameter viscoelastic material model for denture adhesives based on time-temperature superposition and multiple linear regression analysis

引用

BMC biomedical engineering 2024年第1期6卷 8页

作者： Anantha Narayanan Ramakrishnan Josephine Reymann Christopher Ludtka Andreas Kiesow Stefan Schwan Department of Engineering and Natural Sciences University of Applied Sciences Hochschule Merseburg Merseburg Germany. Institute for Modelling and Simulation of Biomechanical Systems Faculty of Civil and Environmental Engineering University of Stuttgart Stuttgart Germany. Department of Biological and Macromolecular Materials Fraunhofer Institute for Microstructure of Materials and Systems IMWS Halle (Saale) Germany. Department of Operative Dentistry and Periodontology Martin-Luther-University Halle-Wittenberg Halle Germany. J. Crayton Pruitt Family Department of Biomedical Engineering University of Florida Gainesville USA. Department of Engineering and Natural Sciences University of Applied Sciences Hochschule Merseburg Merseburg Germany. stefan.schwan@imws.fraunhofer.de. Department of Biological and Macromolecular Materials Fraunhofer Institute for Microstructure of Materials and Systems IMWS Halle (Saale) Germany. stefan.schwan@imws.fraunhofer.de.

BACKGROUND:Restorative solutions designed for edentulous patients such as dentures and their accompanying denture adhesives operate in the complex and dynamic environment represented by human oral physiology. Developing material models accounting for the viscoelastic behavior of denture adhesives can facilitate their further optimization within that unique physiological environment. This study aims to statistically quantify the degree of significance of three physiological variables - namely: temperature, adhesive swelling, and pH - on denture adhesive mechanical behavior. Further, based on these statistical significance estimations, a previously-developed viscoelastic material modelling approach for such denture adhesives is further expanded and developed to capture these variables' effects on mechanical behavior. METHODS:In this study a comparable version of Denture adhesive Corega Comfort was analysed rheologically using the steady state frequency sweep tests. The experimentally derived rheological storage and loss modulus values for the selected physiological variables were statistically analyzed using multi parameter linear regression analysis and the Pearson's coefficient technique to understand the significance of each individual parameter on the relaxation spectrum of the denture adhesive. Subsequently, the parameters are incorporated into a viscoelastic material model based on Prony series discretization and time-temperature superposition, and the mathematical relationship for the loss modulus is deduced. RESULTS:The results of this study clearly indicated that the variation in both the storage and loss modulus values can be accurately predicted using the oral cavity physiological parameters of temperature, swelling ratio, and pH with an adjusted R value of 0.85. The R value from the multi-parameter regression analysis indicated that the predictor variables can estimate the loss and storage modulus with a reasonable accuracy for at least 85% of the rheologi

关键词： Adhesive swelling Denture adhesives Material modelling Multi-parameter linear regression analysis Rheology Temperature Time-temperature superposition Viscoelastic behavior pH

来源：评论

学校读者我要写书评

暂无评论

Fully automated all-fiber widely-tunable optical-parametric-oscillator laser system

Fully automated all-fiber widely-tunable optical-parametric-...

引用

Conference on Lasers and Electro-Optics Europe

作者： Thomas Gottschall Tobias Meyer Cesar Jauregui Florian Just Tino Eidam Michael Schmitt Jens Limpert Jurgen Popp Andreas Tunnermann Friedrich-Schiller-Universität Jena Institute of Applied Physics Abbe Center of Photonics Albert-Einstein-Str. 15 07745 Jena Germany Friedrich-Schiller-Universität Jena Institute of Physical Chemistry Abbe Center of Photonics Helmholtzweg 4 07743 Jena Germany Active Fiber Systems GmbH Wildenbruchstr. 15 07745 Jena Germany Leibniz-Institut für Photonische Technologien Jena (IPHT) e.V. Albert-Einstein-Str. 9 07745 Jena Germany Fraunhofer Institute for Applied Optics and Precision Engineering Albert-Einstein-Str. 7 07745 Jena Germany

ISBN: (纸本)9781509067374

Among other modern imaging techniques, stimulated Raman scattering (SRS) requires an extremely quiet, widely wavelength tunable laser [1], which, up to now, is unheard of in fiber laser systems. Here we present a compact all-fiber laser system, which features an optical parametric oscillator (OPO) based on degenerate four-wave mixing (FWM) in an endlessly single-mode photonic-crystal fiber [2]. We employ pulses from an all-fiber frequency and repetition rate tunable laser, which after amplification and subsequent conversion in the linear OPO cavity arrangement are converted to wavelength ranges of 764 - 960 nm and 1164 - 1552 nm at a repetition rate of 9.5 MHz. Thus, all biochemically relevant Raman shifts from 922 to 3322 cm~(-1) may be addressed in combination with an additional output, which is tunable from 1024 to 1052 nm. This ultra-low-noise output emits synchronized pulses with twice the repetition rate to enable SRS imaging.

关键词： Fiber lasers Imaging techniques Laser systems Parametric oscillators Raman scattering Tunable lasers

来源：评论

学校读者我要写书评

暂无评论

Re-evaluation of the SRH-parameters for the FeGa defect

引用

AIP Conference Proceedings 2019年第1期2147卷

作者： Regina Post Tim Niewelt Wenjie Yang Daniel Macdonald Wolfram Kwapil Martin C. Schubert 1University Freiburg Department of Sustainable Systems Engineering (INATECH) Emmy-Noether-Str. 2 79110 Freiburg Germany 2Fraunhofer Institute for Solar Energy Systems ISE Heidenhofstraße 2 79110 Freiburg Germany 3Research School of Engineering College of Engineering and Computer Science The Australian National University Canberra ACT0200 Australia

In this work the existing SRH parametrizations for the FeGa defect are re-evaluated by a deliberately iron contaminated sample set of varied doping densities. The evolution of the cross-over point is analyzed for this aim, due to its characteristic dependency on the defect parameters of the metastable iron states. It can give insight into the defect parameter, whilst being independent of most factors usually limiting evaluations precision. The proposed parameter adjustment provides an improved description of the measurement data compared to the literature parametrizations.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Nanofabricated and integrated colour centres in silicon carbide with high-coherence spin-optical properties

arXiv

引用

arXiv 2021年

作者： Babin, Charles Stohr, Rainer Morioka, Naoya Linkewitz, Tobias Steidl, Timo Wornle, Raphael Liu, Di Hesselmeier, Erik Vorobyov, Vadim Denisenko, Andrej Hentschel, Mario Gobert, Christian Berwian, Patrick Astakhov, Georgy V. Knolle, Wolfgang Majety, Sridhar Saha, Pranta Radulaski, Marina Tien Son, Nguyen Ul-Hassan, Jawad Kaiser, Florian Wrachtrup, Jorg 3rd Institute of Physics IQST University of Stuttgart Research Centre SCoPE Stuttgart70569 Germany Institute for Chemical Research Kyoto University Kyoto Uji611-0011 Japan 4th Institute of Physics IQST Research Centre SCoPE University of Stuttgart Stuttgart70569 Germany Fraunhofer Institute for Integrated Systems and Device Technology IISB Schottkystr. 10 Erlangen91058 Germany Helmholtz-Zentrum Dresden-Rossendorf Institute of Ion Beam Physics and Materials Research Dresden01328 Germany Leipzig04318 Germany Department of Electrical and Computer Engineering University of California DavisCA95616 United States Department of Physics Chemistry and Biology Linkoping University LinkopingSE-58183 Sweden

Optically addressable spin defects in silicon carbide (SiC) are an emerging platform for quantum information processing. Lending themselves to modern semiconductor nanofabrication, they promise scalable high-efficiency spin-photon interfaces. We demonstrate here nanoscale fabrication of silicon vacancy centres (VSi) in 4H-SiC without deterioration of their intrinsic spin-optical properties. In particular, we show nearly transform limited photon emission and record spin coherence times for single defects generated via ion implantation and in triangular cross section waveguides. For the latter, we show further controlled operations on nearby nuclear spin qubits, which is crucial for fault-tolerant quantum information distribution based on cavity quantum electrodynamics. Copyright © 2021, The Authors. All rights reserved.

关键词： Silicon carbide

来源：评论

学校读者我要写书评

暂无评论

Light scattering at random pyramid textures: Effects beyond geometric optics

引用

AIP Conference Proceedings 2018年第1期1999卷

作者： Oliver Höhn Nico Tucher Armin Richter Martin Hermle Benedikt Bläsi 1Fraunhofer Institute for Solar Energy Systems ISE Heidenhofstraße 2 79100 Freiburg Germany 2Albert-Ludwigs-University Department of Sustainable Systems Engineering INATECH Georges-Köhler-Allee 103 79110 Freiburg Germany

The currently highest measured efficiency for both side contacted monocrystalline Silicon solar cells is 25.8%. The external quantum efficiency of these solar cells with random pyramids at the front side differs from results achieved with pure ray optical modeling. As is already known from literature, better agreement can be reached by introducing additional scattering into the modeled system. Within this paper we show that this scattering can be well explained using a Phong-like scatterer. What is more, we show that in the investigated high efficiency solar cells scattering at the rear side is a minor effect although it is often assumed as the origin of scattering. The relevant scattering instead is caused by the random pyramids themselves.

关键词：

来源：评论

学校读者我要写书评

暂无评论

On the Systematic Construction of Lyapunov Functions for Polynomial systems

引用

PAMM 2023年第1期23卷

作者： Lars Natkowski Daniel Gerbet Klaus Röbenack Fraunhofer Institute for Transportation and Infrastructure Systems IVI Zeunerstraße 38 01069 Dresden Germany Institute of Control Theory Faculty of Electrical and Computer Engineering TU Dresden Georg-Schumann-Straße 7A 01187 Dresden Germany

Lyapunov functions are a widely used tool to evaluate stability properties of nonlinear dynamical systems' equilibria. In this paper quantifier elimination is used to construct Lyapunov functions for polynomial systems from a parametric ansatz. Because the existing algorithms for quantifier elimination are inherently computationally expensive, a strategy is to simplify the quantifier elimination problem beforehand. A method is presented that may help simplifying the problem of finding suitable Lyapunov functions by deriving easier to evaluate necessary conditions. Finally, the introduced method is applied to an example system to show local asymptotic stability of an equilibrium point by constructing a Lyapunov function.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Lock-in Thermography for the Development of New Materials

引用

Materials Today: Proceedings 2017年 4卷 S128-S134页

作者： Peter W. Nolte Timo Malvisalo A. Charlotte Rimbach Franziska Steudel Bernd Ahrens Stefan Schweizer Fraunhofer Application Center for Inorganic Phosphors Branch Lab of Fraunhofer Institute for Microstructure of Materials and Systems IMWS Lübecker Ring 2 59494 Soest Germany Department of Electrical Engineering South Westphalia University of Applied Sciences Lübecker Ring 2 59494 Soest Germany

Thermal management is one of the crucial concerns for mid- and high-power white light-emitting diodes (LEDs). Most of the currently available white LEDs on the market consist of a blue LED chip coated with a yellow phosphor-polymer composite. Besides the heat-induced degradation of the phosphor-polymer composite, the so-called thermal quenching, i.e. the decrease in light output upon increasing temperature, is also a pressing issue. Both result in an efficiency decrease and in a color change of the LED. In this work, a method to determine the thermal diffusivity and the thermal conductivity of phosphors is presented using lanthanide-doped glasses as test samples. In the quest for temperature-stable phosphors with a high thermal conductivity, such luminescent glasses might represent an attractive alternative. Thermal waves are introduced to the samples by periodical heating with a laser. Lock-in infrared thermography, a non-destructive method, is used to monitor even small changes in surface temperature. The phase delay of the thermal wave passing through the sample is analyzed at different lock-in frequencies and a mathematical fitting of the phase data then provides the coefficients required to determine the thermal diffusivity. Subsequently, the thermal conductivity is calculated from the thermal diffusivity, the mass density, and the specific heat capacity.

关键词： lock-in thermography thermal diffusivity thermal conductivity laser heating

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：