检索结果-内蒙古大学图书馆

Conference on Lasers and Electro-Optics Europe (CLEO EUROPE)

作者： Yannick Schrödel Claas Hartmann Tino Lang Jiaan Zheng Max Steudel Matthias Rutsch Sarper H. Salman Martin Kellert Mikhail Pergament Thomas Hahn-Jose Sven Suppelt Jan Helge Dörsam Anne Harth Wim P. Leemans Franz X. Kärtner Ingmar Hartl Mario Kupnik Christoph M. Heyl Deutsches Elektronen-Synchrotron DESY Hamburg Germany Measurement and Sensor Technology Technische Universität Darmstadt Darmstadt Germany Department of Optics and Mechatronics Hochschule Aalen Aalen Germany Helmholtz-Institute Jena Jena Germany GSI Helmholtzzentrum für Schwerionenforschung GmbH Darmstadt Germany Center for Free-Electron Laser Science CFEL Deutsches Elektronen-Synchrotron DESY Hamburg Germany INOSON GmbH St. Ingbert Germany Department of Physics University of Hamburg Hamburg Germany The Hamburg Centre for Ultrafast Imaging Hamburg Germany

ISBN: (纸本)9798350345995

Control over the parameters of a laser beam such as intensity and phase is vital in modern photonics. The established schemes, however, limit the parameter range in which common methods can be applied. The limitations are most prominent in terms of peak-power and wavelength $\lambda$ , as current methods rely to a large extend on the interaction of light with solid media (e.g. glasses, crystals). We here propose a simple but effective alternative to solid media: gases tailored by intense ultrasound waves via refractive index change induced by density modulations. Earlier works report gas-based refractive optics [1]. However, to the best of our knowledge, more advanced gas-based control schemes such as modulators, deflectors or phase shapers have not entered the photonics field until today.

关键词： Deflectors Laser beams Modulation Phase Photonics Refractive index

来源：评论

学校读者我要写书评

暂无评论

Evaluation of the Point Sampling Method and Inter-Comparison of Remote Emission Sensing Systems for Screening Real-World Car Emissions

SSRN

引用

SSRN 2023年

作者： Knoll, Markus Penz, Martin Schmidt, Christina Pöhler, Denis Rossi, Tommaso Casadei, Simone Bernard, Yoann Hallquist, Åsa M. Sjödin, Åke Bergmann, Alexander Institute of Electric Measurement and Sensor Systems Graz University of Technology Inffeldgasse 33/I Graz8010 Austria Institute of Environmental Physics Heidelberg University INF 229 Heidelberg69120 Germany Airyx GmbH Justus-von-Liebig-Str. 14 Eppelheim69214 Germany Innovhub - Stazioni Sperimentali per l’Industria S.r.k. Sustainable Mobility Team Via G. Galilei 1 San Donate Milanese Milan20097 Italy ICCT International Council on Clean Transportation Neue Promenade 6 Berlin10178 Germany IVL Swedish Environmental Research Institute Valhallavaegen 81 Stockholm10031 Sweden

Emissions from internal combustion vehicles are currently not properly monitored throughout their life cycle. Remote Emission Sensing (RES) is a technology that can detect emissions in real driving conditions without contact. Current RES systems, based on the measurement of light extinction from exhaust plumes, are capable of providing emission factors for various gases, but lack accuracy for particulate matter (PM). Point Sampling (PS) is an RES technique that extracts portions of the exhaust plume using exhaust gas analyzers that measure gaseous compounds aswell as various particle metrics such as black carbon or particle number concentrations. In this work we have evaluated the performance of a recently developed PS system and the state-of-the-art light extinction based systems EDAR (HEAT) and AccuScan (OPUS RSE) in application settings. In three measurement campaigns in different European cities we co-located the PS system with one of the extinction based systems. Validation measurements with portable emission measurement systems and the emission screening of several thousand passenger cars provide detailed insights into the performance of the systems. measurement results demonstrate the ability of the PS system to screen high and low PM emitters equally well. The AccuScan system is capable of measuring PM emissions from older diesel vehicles, but the light extinction-based systems are unable to quantify PM emissions from vehicles that meet the latest emission standards. We found that all three systems tested were capable of screening NOx emissions with a similar level of accuracy. The applicability of the RES systems in different weather conditions was explored. The PS capture rate is strongly affected by wind conditions, but no other weather influences were found. Both light extinction based systems are unable to measure during rain. These results provide detailed information on the performance of different RES technologies. © 2023, The Authors. All rights res

关键词： Air pollution

来源：评论

学校读者我要写书评

暂无评论

Lensless multicore-fiber microendoscope for real-time tailored light field generation with phase encoder neural network (CoreNet)

arXiv

引用

arXiv 2021年

作者： Sun, Jiawei Wu, Jiachen Koukourakis, Nektarios Kuschmierz, Robert Cao, Liangcai Czarske, Jürgen Laboratory of Measurement and Sensor System Technique TU Dresden Helmholtzstrasse 18 Dresden01069 Germany TU Dresden Dresden Germany State Key Laboratory of Precision Measurement Technology and Instruments Department of Precision Instruments Tsinghua University Beijing100084 China Cluster of Excellence Physics of Life TU Dresden Dresden Germany Institute of Applied Physics TU Dresden Dresden Germany

The generation of tailored light with multi-core fiber (MCF) lensless microendoscopes is widely used in biomedicine. However, the computer-generated holograms (CGHs) used for such applications are typically generated by iterative algorithms, which demand high computation effort, limiting advanced applications like in vivo optogenetic stimulation and fiber-optic cell manipulation. The random and discrete distribution of the fiber cores induces strong spatial aliasing to the CGHs, hence, an approach that can rapidly generate tailored CGHs for MCFs is highly demanded. We demonstrate a novel phase encoder deep neural network (CoreNet), which can generate accurate tailored CGHs for MCFs at a near video-rate. Simulations show that CoreNet can speed up the computation time by two magnitudes and increase the fidelity of the generated light field compared to the conventional CGH techniques. For the first time, real-time generated tailored CGHs are on-the-fly loaded to the phase-only SLM for dynamic light fields generation through the MCF microendoscope in experiments. This paves the avenue for real-time cell rotation and several further applications that require real-time high-fidelity light delivery in biomedicine. Copyright © 2021, The Authors. All rights reserved.

关键词： Iterative methods

来源：评论

学校读者我要写书评

暂无评论

Amplitude estimation using three-parameter sine fitting algorithm in the Planck-Balance 23

Amplitude estimation using three-parameter sine fitting algo...

引用

23rd IMEKO TC4 International Symposium on Electrical and Electronic measurements Promote Industry 4.0

作者： Lin, Shan Rothleitner, Christian Rogge, Norbert Physikalisch-Technische Bundesanstalt Bundesallee 100 Braunschweig38116 Germany Institute of Process Measurement and Sensor Technology Technische Universität Ilmenau Ilmenau98684 Germany

The Planck-Balance (PB) is a table-top version of a Kibble balance. In contrast to many existing Kibble balances, the coil is moved sinusoidally and an ac rather than a dc signal is generated in the dynamic mode. The three-parameter sine fitting algorithm is applied to estimate the amplitudes of the induced voltage and the coil motion, which are used to determine the force factor Bl of the voice coil of the electromagnetic force compensation balance. However, the three-parameter sine fitting algorithm is not robust against some perturbations, e.g. additive Gaussian white noise, quantization error, and frequency error. These effects have influences on the accuracy of the amplitude estimation. Based on numerical simulations and correlation analyses, the effects of these perturbations are determined. By optimizing measurement and data processing approach, the bias and standard deviation of the estimated amplitude could be effectively reduced, and thus the accuracy of the force factor Bl in the dynamic mode can be improved. © 2019 IMEKO TC4 International Symposium Electrical and Electronic measurements Promote Industry 4.0. All rights reserved.

关键词： White noise

来源：评论

学校读者我要写书评

暂无评论

Vision Experiments on Chroma-Related Preference for Color Quality of Lighting

引用

Journal of the Illuminating Engineering Society 2024年第4期20卷

作者： Yoshi Ohno Jiaye Li Yuki Kawashima Semin Oh a Sensor Science Division Physical Measurement Laboratory National Institute of Standards and Technology Gaithersburg Maryland USA b Department of Informatics Graduate School of Science and Engineering Yamagata University Yonezawa Japan c Department of Psychology School of Arts and Sciences University of Pennsylvania Philadelphia Pennsylvania USA

ABSTRACTTwo vision experiments were conducted to quantify the chroma-related preference in color quality of lighting in a real room-size cubicle simulating interior lighting environment with spectrally tunable light sources. The first experiment used 9 different lights with increased or decreased chroma in nine levels in red-green directions. The second experiment used 11 different lights with increased or decreased chroma in three hue directions, for red, green, and yellow, controlled as independently as possible. About 20 subjects participated in these two experiments evaluating the appearance of various fruits and vegetables as well as skin tone under these test lights by numerous pair comparisons. The results of the first experiment showed that chroma increase in ΔC*ab≈ 4 to 8 from the reference light was most preferred for all target objects, and desaturated lights were disliked in all cases. The second experiment showed that chroma change in red is significantly important for the preference, green was second, and yellow had the least effect on preference. The results of the second experiment suggested that preference increases with increasing red chroma in light, and after a peak in preference (between ΔC*ab≈ 5 to 10), preference starts decreasing, which is consistent with findings from the first experiment. Neither the viewing targets nor the correlated color temperature (CCT) conditions were found to have significant impact on the subjects’ preference.

关键词： Color rendition color preference chroma perception vision experiment

来源：评论

学校读者我要写书评

暂无评论

Suppression of free convection effects for spherical 1 kg mass prototype

arXiv

引用

arXiv 2020年

作者： Sachs, Sebastian Fröhlich, Thomas Schumacher, Jörg Institute of Thermodynamics and Fluid Mechanics Technische Universität Ilmenau IlmenauD-98684 Germany Institute of Process Measurement and Sensor Technology Technische Universität Ilmenau IlmenauD-98684 Germany

We investigate the free convection processes in the vicinity of a spherical 1 kg mass standard by two- and three-dimensional direct numerical simulations using a spectral element method. Our focus is on the determination and suppression of updraft forces in a high-precision mass comparator which are caused by temperature differences between mass standard and its environment in the millikelvin range – a source of systematic uncertainties in the high-precison mass determination. A two-dimensional model is presented first, which obtains a good agreement with previous laboratory measurements for the smaller temperature differences up to 15 mK. The influence of different boundary conditions and side lengths of the square domain is discussed for the mass standard positioned in the center of the chamber. The complexity is increased subsequently in configurations with additional built-ins for counter heating in form of planar plates or hemispherical shells above the mass standard. The latter ones lead to a full compensation of the updraft force. Three-dimensional simulations in a closed cubic chamber confirm the two-dimensional findings and additionally reveal complex secondary flow pattern in the vicinity of the mass standard. The reduction of the heat transfer due to the built-ins is also demonstrated by a comparison of the Nusselt numbers as a function of the Rayleigh number in the chosen parameter range. Our simulations suggest that such additional constructive measures can enhance the precision of the mass determination by suppression of free convection and related systematic uncertainties. Copyright © 2020, The Authors. All rights reserved.

关键词： Natural convection

来源：评论

学校读者我要写书评

暂无评论

Influence of different cooling strategies during hard turning of AISI 52100 – part II: characterization of the surface and near surface microstructure morphology

引用

Procedia CIRP 2020年 87卷 119-124页

作者： Werner Ankener Julian Uebel Stephan Basten Marek Smaga Benjamin Kirsch Jörg Seewig Jan C. Aurich Tilmann Beck Institute of Materials Science and Engineering TU Kaiserslautern Gottlieb-Daimler-Str. 67663 Kaiserslautern Germany Institute for Measurement and Sensor Technology TU Kaiserslautern Gottlieb-Daimler-Str. 67663 Kaiserslautern Germany Institute for Manufacturing Technology and Production Systems TU Kaiserslautern Gottlieb-Daimler-Str. 67663 Kaiserslautern Germany

This two-part paper addresses the impact of seven different cooling conditions on the finishing process as well as the resulting surface and near-surface microstructure morphology of the rolling bearing steel AISI 52100 in martensitic heat treatment state. The applied cooling strategies are liquid nitrogen (LN 2 -) cooling, CO 2 -snow cooling at varied mass flows, sub-zero metalworking fluids (MWF) at varied supply temperatures, and dry machining. Part II of the paper concerns the changes in surface roughness, examined by an angle resolved scatter light sensor, micro hardness measurement, microstructure observations, residual stress and phase composition analyses in the near-surface area, caused by the turning process, that is characterized in Part I. The lowest cooling performance, i.e. dry machining, results in low compressive axial residual stresses and a high proportion of retained austenite at the near-surface area. High cooling performance strategies like CO 2 cooling or sub-zero MWF show an opposite distribution of the mentioned parameters, wherein the coolants’ lubrication effect is an important aspect. Microstructural differences resulting from the process parameters used in these investigations tend to be less significant. Thus, they do not allow reliable assignment of the microstructure to the cooling strategies used. However, different cooling conditions show an impact on residual stresses, phase distribution and surface topography of the workpieces to varying extents.

关键词： cryogenic turning surface integrity micro structure

来源：评论

学校读者我要写书评

暂无评论

Influence of different cooling strategies during hard turning of AISI 52100 - part I: thermo-mechanical load, tool wear, surface topography and manufacturing accuracy

引用

Procedia CIRP 2020年 87卷 77-82页

作者： Stephan Basten Benjamin Kirsch Werner Ankener Marek Smaga Tilmann Beck Julian Uebel Jörg Seewig Jan C. Aurich Institute for Manufacturing Technology and Production Systems TU Kaiserslautern Gottlieb-Daimler-Str. 67663 Kaiserslautern Germany Institute of Materials Science and Engineering TU Kaiserslautern Gottlieb-Daimler-Str. 67663 Kaiserslautern Germany Institute for Measurement and Sensor Technology TU Kaiserslautern Gottlieb-Daimler-Str. 67663 Kaiserslautern Germany

This paper presents a characterization of the turning process for finishing of AISI 52100 in martensitic heat treatment state at various cooling conditions. With regard to the cooling conditions, LN 2 -cooling, CO 2 snow cooling at varied mass flows, sub-zero metalworking fluids (MWF) at varied supply temperatures, and dry machining were examined. The tool temperatures, the process forces, the tool wear, the surface topography as well as the dimensional deviations of the workpiece caused by unintended alterations of the depth of cut due to a thermal expansion or contraction of the workpiece are analyzed. The application of MWF supplied at 20 °C results in an unchanging thermo-mechanical load in the tool-work interface and surface topography as well as in a high manufacturing accuracy. Dry machining leads to an increasing depth of cut of up to 10 %, resulting in radial dimensional errors. Cryogenic machining and using the sub-zero MWF supplied at -30 °C exhibit a different behavior due to high cooling effects: the depth of cut is reduced up to 10 %, also leading to radial dimensional errors. However, even though the depth of cut and thus the undeformed chip cross section is affected by up to 10 % depending the cooling condition, the mechanical load remains approximately constant during single cuts. In part II, the surface and near surface microstructure morphology of the workpieces is characterized.

关键词： cryogenic turning surface integrity accuracy error hard machining precicion turning

来源：评论

学校读者我要写书评

暂无评论

Role of quantum technologies in reshaping the future of temperature metrology

引用

measurement: sensors 2021年 18卷

作者： Zeeshan Ahmed Sensor Science Division Physical Measurement Laboratory National Institute of Standards and Technology Gaithersburg MD 20899 USA

Today's resistance thermometers can routinely measure temperatures with uncertainties of >1 mK–100 mK over multiple decades of temperatures. As the modern economy continues to evolve, so does the measurement infrastructure. In recent years, there has been a considerable progress in the development of novel temperature sensing technologies driven by advances in quantum information science and nano-photonics. Quantum technologies in particular hold the promise of field-deployable primary thermometry whilst ultra-stable nanophotonic thermometers could displace resistance thermometers as commodity sensors.

关键词： Quantum opto-mechanics Doppler broadening thermometry NV Diamond Photonic thermometry

来源：评论

学校读者我要写书评

暂无评论

Randomized reduced forward models for efficient metropolis–hastings MCMC, with application to subsurface fluid flow and capacitance tomography

arXiv

引用

arXiv 2020年

作者： Fox, Colin Cui, Tiangang Neumayer, Markus Department of Physics University of Otago Dunedin New Zealand School of Mathematics Monash University Melbourne Australia Institute of Electrical Measurement and Sensor Systems Graz University of Technology Graz Austria

Bayesian modelling and computational inference by Markov chain Monte Carlo (MCMC) is a principled framework for large-scale uncertainty quantification, though is limited in practice by computational cost when implemented in the simplest form that requires simulating an accurate computer model at each iteration of the MCMC. The delayed acceptance Metropolis–Hastings MCMC leverages a reduced model for the forward map to lower the compute cost per iteration, though necessarily reduces statistical efficiency that can, without care, lead to no reduction in the computational cost of computing estimates to a desired accuracy. Randomizing the reduced model for the forward map can dramatically improve computational efficiency, by maintaining the low cost per iteration but also avoiding appreciable loss of statistical efficiency. Randomized maps are constructed by a posteriori adaptive tuning of a randomized and locally-corrected deterministic reduced model. Equivalently, the approximated posterior distribution may be viewed as induced by a modified likelihood function for use with the reduced map, with parameters tuned to optimize the quality of the approximation to the correct posterior distribution. Conditions for adaptive MCMC algorithms allow practical approximations and algorithms that have guaranteed ergodicity for the target distribution. Good statistical and computational efficiencies are demonstrated in examples of calibration of large-scale numerical models of geothermal reservoirs and electrical capacitance tomography. Copyright © 2020, The Authors. All rights reserved.

关键词： Computational efficiency

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：