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arXiv 2022年

作者： Rothe, Stefan Besser, Karl-Ludwig Krause, David Kuschmierz, Robert Koukourakis, Nektarios Jorswieck, Eduard Czarske, Jürgen W. TU Dresden Faculty of Electrical and Computer Engineering Laboratory of Measurement and Sensor System Technique Dresden01062 Germany TU Braunschweig Faculty of Electrical Engineering Information Technology Physics Institute for Communications Technology Braunschweig38106 Germany TU Dresden Faculty of Physics Dresden01062 Germany

Multimode fibers hold great promise to advance data rates in optical communications but come with the challenge to compensate for modal crosstalk and mode-dependent losses, resulting in strong distortions. The holographic measurement of the transmission matrix enables not only correcting distortions but also harnessing these effects for creating a confidential data connection between legitimate communication parties, Alice and Bob. The feasibility of this physical-layer-security-based approach is demonstrated experimentally for the first time on a multimode fiber link to which the eavesdropper Eve is physically coupled. Once the proper structured light field is launched at Alice's side, the message can be delivered to Bob, and, simultaneously, the decipherment for an illegitimate wiretapper Eve is destroyed. Within a real communication scenario, we implement wiretap codes and demonstrate confidentiality by quantifying the level of secrecy. Compared to an uncoded data transmission, the amount of securely exchanged data is enhanced by a factor of 538. The complex light transportation phenomena that have long been considered limiting and have restricted the widespread use of multimode fiber are exploited for opening new perspectives on information security in spatial multiplexing communication systems. © 2022, CC BY.

关键词： Multimode fibers

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Traceable 5D-nanofabrication with nano positioning and nano measuring machines 21

Traceable 5D-nanofabrication with nano positioning and nano ...

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21st International Conference of the European Society for Precision engineering and Nanotechnology, EUSPEN 2021

作者： Ortlepp, Ingo Fern, Florian Schienbein, Ralf Supreeti, Shraddha Füßl, Roland Theska, René Sinzinger, Stefan Manske, Eberhard Institute of Process Measurement and Sensor Technology Department of Mechanical Engineering Technische Universität Ilmenau Germany JUMO GmbH and Co. KG Moritz-Juchheim-Straße 1 Fulda36039 Germany Precision Engineering Group Department of Mechanical Engineering Technische Universität Ilmenau Germany Electronics Technology Group Department of Electrical Engineering and Information Technology Technische Universität Ilmenau Germany Optical Engineering Group Department of Mechanical Engineering Technische Universität Ilmenau Germany

ISBN: (纸本)9780995775190

Today, besides the ongoing progress in the reduction of feature sizes, the measuring and fabrication of freeform surfaces with nanometre uncertainty, e.g. for aspheric lenses or structures with high aspect ratios, are a challenging task. Usually, dealing with such objects is limited by the local tilt angle between the object surface and the tool axis. There are different approaches to perform such measurements. In this paper, an extension of the Nano Measuring Machine NMM-1 with two rotational axes is described. With the proposed setup, it is possible to orientate the tool-axis perpendicular to the sample in every position, allowing larger angles to be measured / structured and minimising the uncertainty of the process e.g. due to the tilt dependency of the tool. Various machine designs are investigated and finally a solution with one rotary and one goniometer stage is integrated, preserving the existing machine infrastructure and allowing the addressability of a full hemisphere without limiting the measuring volume. As the tool centre point maintains its position during tool rotation, the Abbe principle is still fulfilled in every angular orientation. Emphasis was put on the metrological traceability of the whole system, including linear and rotary axes as well the tool itself. This was achieved by using a reference hemisphere, compensating the trajectory errors of the rotational axes. For the developed arrangement, the measurement uncertainty was investigated and several strategies for an in-situ-calibration of the additional axes are described. Finally, nanofabrication on large slopes is demonstrated. © 2021 Proceedings of the 21st International Conference of the European Society for Precision engineering and Nanotechnology, EUSPEN 2021. All rights reserved.

关键词： Machine design

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Research on Laser Spectrum of Large-aperture Antenna Subreflector Pose measurement 6

Research on Laser Spectrum of Large-aperture Antenna Subrefl...

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6th Conference on Frontiers in Optical Imaging and technology: Imaging Detection and Target Recognition

作者： Xuan, Zhang Shangmin, Lin Hu, Wang Ming, Gao Zhen, Wang Yu, Jin Jiang, Qiao Yunqiang, Lai Wenlong, He Yaoke, Xue Xi'an Technological University No.2 Xuefuzhonglu Road Shaanxi Xi'an710021 China Xi’an Institute of Optics and Precision Mechanics Chinese Academy of Science No.17 Xinxi Road Shaanxi Xi'an710119 China University of Chinese Academy of Sciences No.1 Yanqihu East Rd Huairou District Beijing101408 China Xi’an Space Sensor Optical Technology Engineering Research Center No.17 Xinxi Road Shaanxi Xi'an710119 China Key Laboratory of Space Precision Measurement Technology Chinese Academy of Sciences No.17 Xinxi Road Shaanxi Xi'an710119 China Beijing University of Aeronautics and Astronautics Beijing100191 China Youth Innovation Promotion Association Beijing10029 China

ISBN: (数字)9781510679733

ISBN: (纸本)9781510679726

When the large-aperture antenna pose is measured by the laser method, the subreflector has a strong energy due to the convergence of the antenna itself and the instability of the near-ground atmosphere, and then the laser signal is easily drowned out. Atmospheric attenuation and other factors will weaken the laser transmission in different spectral bands, which reduces the recognition accuracy of laser spots. Aiming at the research of measuring the laser spectrum of large-aperture antenna, this paper analyzes the influence of atmospheric attenuation on the signals of different laser spectrum bands under the fixed distance of subreflector measurement, and compares the solar radiation energy of different wavelengths in laser. Finally, the stray light simulation analysis and experiments are carried out on different laser working spectrum bands to verify the accuracy of the spectrum research used in antenna measurement. Experiments show that the 1064 nm wavelength spectrum, as the working spectral band of the antenna measurement, the spot information is more obvious, which can effectively realize the extraction and identification of the spot center and provide a strong guarantee for the antenna pose measurement. © 2024 SPIE. All rights reserved.

关键词： Stray light

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Modeling of Motion Distortion Effect of Scanning LiDAR sensors for Simulation-based Testing

TechRxiv

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TechRxiv 2023年

作者： Haider, Arsalan Haas, Lukas Koyama, Shotaro Elster, Lukas Köhler, Michael H. Schardt, Michael Zeh, Thomas Inoue, Hideo Jakobi, Martin Koch, Alexander W. IFM–Institute for Driver Assistance Systems and Connected Mobility Kempten University of Applied Sciences Junkersstrasse 1A Benningen87734 Germany Institute for Measurement Systems and Sensor Technology Technical University of Munich Arcisstrasse 21 Munich80333 Germany Kanagawa Institute of Technology Shimoogino 1030 Kanagawa Atsugi243-0292 Japan Institute of Automotive Engineering Technical University of Darmstadt Darmstadt64289 Germany Blickfeld GmbH Barthstrasse 12 Munich80339 Germany

Automated vehicles use light detection and ranging (LiDAR) sensors for environmental scanning. However, the relative motion between the scanning LiDAR sensor and objects leads to a distortion of the point cloud. This phenomenon is known as the motion distortion effect, significantly degrading the sensor’s object detection capabilities and generating false negative or false positive errors. In this work, we have introduced ray tracing-based deterministic and analytical approaches to model the motion distortion effect on the scanning LiDAR sensor’s performance for simulation-based testing. In addition, we have performed dynamic test drives at a proving ground to compare real LiDAR data with the motion distortion effect simulation data. The real-world scenarios, the environmental conditions, the digital twin of the scenery, and the object of interest (OOI) are replicated in the virtual environment of commercial software to obtain the synthetic LiDAR data. The real and the virtual test drives are compared frame by frame to validate the motion distortion effect modeling. The mean absolute percentage error (MAPE), the occupied cell ratio (OCR), and the Barons cross-correlation coefficient (BCC) are used to quantify the correlation between the virtual and the real LiDAR point cloud data. The results show that the deterministic approach matches the real measurements better than the analytical approach for the scenarios in which the yaw rate of the ego vehicle changes rapidly. © 2023, CC BY.

关键词： Optical radar

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Neural Network-Based Multimode Fiber Imaging and Characterization Under Thermal Perturbations

arXiv

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arXiv 2024年

作者： Wang, Kun Zhu, Changyan Colicchia, Ennio Dong, Xingchen Kurz, Wolfgang Mizuno, Yosuke Jakobi, Martin Koch, Alexander W. Chong, Yidong Technical University of Munich School of Computation Information and Technology Institute for Measurement Systems and Sensor Technology Theresienstrasse 90 Munich80333 Germany Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University Singapore637371 Singapore Faculty of Engineering Yokohama National University 79-5 Tokiwadai Hodogaya-ku Yokohama240-8501 Japan Institute of Multidisciplinary Sciences Yokohama National University 79-5 Tokiwadai Hodogaya-ku Yokohama240-8501 Japan

Multimode fiber (MMF) imaging aided by machine learning holds promise for numerous applications, including medical endoscopy. A key challenge for this technology is the sensitivity of modal transmission characteristics to environmental perturbations. Here, we show experimentally that an MMF imaging scheme based on a neural network (NN) can achieve results that are significantly robust to thermal perturbations. For example, natural images are successfully reconstructed as the MMF's temperature is varied by up to 50◦C relative to the training scenario, despite substantial variations in the speckle patterns caused by thermal changes. A dense NN with a single hidden layer is found to outperform a convolutional NN suitable for standard computer vision tasks. In addition, we demonstrate that NN parameters can be used to understand the MMF properties by reconstructing the approximate transmission matrices, and we show that the image reconstruction accuracy is directly related to the temperature dependence of the MMF's transmission characteristics. © 2024, CC BY.

关键词： Multimode fibers

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Frequency-dependent Ultrasonic Stimulation of PNIPAM Microgels in Water

arXiv

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arXiv 2022年

作者： Razavi, Atieh Rutsch, Matthias Wismath, Sonja Kupnik, Mario von Klitzing, Regine Rahimzadeh, Amin Soft Matter at Interfaces Institute for Condensed Matter Physics Technische Universität Darmstadt Hochschulstraße 8 Darmstadt64289 Germany Measurement and Sensor Technology Department of Electrical Engineering and Information Technology Technische Universität Darmstadt Merckstraße 25 Darmstadt64283 Germany

As a novel stimulus, we use high-frequency ultrasonic waves to provide the required energy for breaking hydrogen bonds between Poly(N-isopropylacrylamide) (PNIPAM) and water molecules while the solution temperature maintains below the volume phase transition temperature (VPTT=32 °C). Ultrasonic waves propagate through the solution and their energy will be absorbed due to the liquid viscosity. The absorbed energy partially leads to the generation of a streaming flow and the rest will be spent to break the hydrogen bonds. Therefore, the microgels collapse and become insoluble in water and agglomerate, resulting in solution turbidity. We use turbidity to quantify the ultrasound energy absorption and showed that the acousto-response of PNIPAM microgels is a temporal phenomenon that depends on the duration of the actuation. Increasing the solution concentration leads to a faster turbidity evolution. Furthermore, an increase in ultrasound frequency leads to an increase in the breakage of more hydrogen bonds within a certain time and thus faster turbidity evolution. This is due to the increase in ultrasound energy absorption by liquids at higher frequencies. © 2022, CC BY.

关键词： Hydrogen bonds

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Monitoring the Evolution of Dimensional Accuracy and Product Properties in Property-Controlled Forming Processes

SSRN

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SSRN 2023年

作者： Stebner, Sophie Charlotte Martschin, Juri Arian, Bahman Dietrich, Stefan Feistle, Martin Hütter, Sebastian Lafarge, Rémi Laue, Robert Li, Xinyiang Schulte, Christopher Spies, Daniel Thein, Ferdinand Wendler, Frank Wrobel, Malte Vasquez, Julian Rozo Dölz, Michael Münstermann, Sebastian Integrity of Materials and Structures RWTH Aachen University Aachen Germany Institute of Forming Technology and Lightweight Components Dortmund University Dortmund Germany Forming and Machining Technology Paderborn University Paderborn Germany Institute for Applied Materials - Material Science Karlsruhe Institute of Technology Karlsruhe Germany Fraunhofer Institute for Casting Composite and Processing Technology Garching Germany Institute of Materials and Joining Technology Otto-von-Guericke University Magdeburg Germany Forming and Machining Processes Technische Universität Dresden Dresden Germany Institute for Machine Tools and Productions Processes Virtual Production Engineering Chemnitz University of Technology Chemnitz Germany Institute of Metal Forming RWTH Aachen University Aachen Germany Institute of Automatic Control RWTH Aachen University Aachen Germany Institute for Production Engineering and Forming Machines Technical University of Darmstadt Darmstadt Germany Institut für Geometrie und Praktische Mathematik RWTH Aachen University Aachen Germany Measurement and Sensor Technology Chemnitz University of Technology Chemnitz Germany Digital Process Engineering Group Institute for Mechanical Process Engineering and Mechanics Karlsruhe Institute of Technology Karlsruhe Germany Materials Test Engineering Dortmund University Dortmund Germany

As recent trends in manufacturing engineering disciplines show a clear development in the sustainable as well as economically efficient design of forming processes, monitoring techniques have been gaining in relevance. In terms of monitoring of product properties, most processes are currently open-loop controlled, entailing that the microstructure evolution, which determines the final product properties, is not considered. However, a closed-loop control that can adjust and manipulate the process actuators according to the required product properties of the component will lead to a considerable increase in efficiency of the processes regarding resources and will decrease postproduction of the component. For most forming processes, one set of component dimensions will result in a certain set of product properties. However, to successfully establish closed-loop property controls for the processes, a systematic understanding of the reciprocity of the dimensions after forming and final product properties must be established. This work investigates the evolution of dimensional accuracy as well as product properties for a series of forming processes that utilize different degrees of freedom for process control. © 2023, The Authors. All rights reserved.

关键词： Process control

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Aza-BODIPY molecular assembly at the liquid-solid interface driven by Br…F-BF interactions

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Chinese Chemical Letters 2021年第11期32卷 3566-3569页

作者： Yuchuan Xiao Fangjian Cai Xuan Peng Xiyuan Kang Peng Lei Xin Li Haijun Xu Xunwen Xiao Bin Tu Qingdao Zeng CAS Key Laboratory of Standardization and Measurement for Nanotechnology CAS Center for Excellence in NanoscienceNational Center for Nanoscience and Technology(NCNST)Beijing 100190China Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources College of Chemical EngineeringNanjing Forestry UniversityNanjing 210037China School of Materials and Chemical Engineering Ningbo University of TechnologyNingbo 315211China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China CAS Center for Excellence in Nanoscience Beijing Key Laboratory of Micro-Nano Energy and SensorBeijing Institute of Nanoenergy and NanosystemsChinese Academy of SciencesBeijing 100083China School of Chemistry and Chemical Engineering Henan Normal UniversityXinxiang 453002China

In this work,two aza-BODIPY derivatives,3,5-diphenyl-1,7-di(p-dodecyloxyphenyl)-aza-BODIPY(CJF)and 3,5-di(p-bromophenyl)-1,7-di(p-dodecyloxyphenyl)-aza-BODIPY(2Br-CJF)acted as model molecules to form the self-assembly monolayers on the solid-liquid *** the utilizing of scanning tunnelling microscope(STM),we demonstrated that intermolecular Br…F-BF interactions existed in 2Br-CJF self-assembly structure and played an important role in strengthening the stability of 2Br-CJF self-assembly *** result is supported by density functional theory(DFT)calculation.

关键词： Aza-BODIPY STM Br…F interaction Self-assembly Surface assembly

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Retrospective motion correction for Fast Spin Echo based on conditional GAN with entropy loss 4

Retrospective motion correction for Fast Spin Echo based on ...

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2021 4th International Conference on Advanced Algorithms and Control engineering, ICAACE 2021

作者： Chen, Yalei Li, Pingan Liu, Kewen Bao, Qingjia Li, Zhao Li, Xiaojun Information and Communication Engineering Wuhan University of Technology Wuhan Hubei430070 China Hubei Key Laboratory of Broadband Wireless Communication and Sensor Networks Wuhan University of Technology Wuhan430070 China State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Center for Magnetic Resonance Wuhan Institute of Physics and Mathematics Innovation Academy for Precision Measurement Science and Technology Wuhan430071 China Department of Chemical and Biological Physics Weizmann Institute of Science Rehovot Israel

We proposed a new end-to-end motion correction method based on conditional generative adversarial network (GAN) and minimum entropy of MRI images for Fast Spin Echo (FSE) sequence. The network contains an encoder-decoder generator to generate the motion-corrected images and a PatchGAN discriminator to classify an image as either real (motion-free) or fake(motion-corrected). Moreover, the image's entropy is set as one loss item in the cGAN's loss as the entropy increases monotonically with the motion amplitude, indicating that entropy is a good criterion for motion. The results show that the proposed method can effectively reduce the artifacts and obtain high-quality motion-corrected images from the motion-affected images in both pre-clinical and clinical datasets. © Published under licence by IOP Publishing Ltd.

关键词： Generative adversarial networks

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Kinematic simulation to investigate the influence of the cutting edge topography when ball end micro milling 18

Kinematic simulation to investigate the influence of the cut...

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18th CIRP Conference on Modeling of Machining Operations, CMMO 2021

作者： Klauer, Katja Altherr, Nicolas Eifler, Matthias Kirsch, Benjamin Böß, Volker Seewig, Jörg Aurich, Jan C. Institute for Manufacturing Technology and Production Systems Technische Universität Kaiserslautern Gottlieb-Daimer Str. Kaiserslautern67663 Germany Institute for Measurement and Sensor-Technology Technische Universität Kaiserslautern Gottlieb-Daimer Str. Kaiserslautern67663 Germany IU University of Applied Sciences Juri-Gagrin-Ring 152 Erfurt99084 Germany Institute of Production Engineering and Machine Tools Leibniz Universität Hannover An der Universität 2 Gabsen30823 Germany

During the ball end micro milling of material measures, the cutting edge topography is imaged on the machined workpiece. The influence of the chipping on the resulting surface quality is much more dominant than other kinematic effects. In this simulative study, a model is built that is able to predict the correlation between the cutting edge topography and the resulting workpiece topography. Thus, the mentioned correlation can be investigated without overlaying effects of material separation or measurement uncertainties, which are unavoidable in an experimental study. The model has been validated based on four artificial chippings. © 2021 Elsevier B.V.. All rights reserved.

关键词： Topography

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