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Probing trade-off between critical size and velocity in cold-spray: An atomistic simulation

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arXiv 2024年

作者： Ghasemi, Mahyar Seifi, Alireza Kateb, Movaffaq Gudmundsson, Jon Tomas Brault, Pascal Marashi, Pirooz Department of Materials and Metallurgical Engineering Amirkabir University of Technology Tehran15875-4413 15916-34311 Iran Condensed Matter and Materials Theory Division Department of Physics Chalmers University of Technology GothenburgSE-412 96 Sweden Science Institute University of Iceland Dunhaga 3 ReykjavikIS-107 Iceland Division of Space and Plasma Physics School of Electrical Engineering and Computer Science KTH Royal Institute of Technology StockholmSE-100 44 Sweden GREMI UMR7344 CNRS Université d'Orléans BP6744 OrleansCEDEX 2 45067 France

The detailed mechanism of bonding in the cold spray process has remained elusive for both experimental and theoretical parties. Adiabatic shear instability and hydrodynamic plasticity models have been so far the most popular explanations. Here, using molecular dynamics simulation, we investigate their validity at the nanoscale. The present study has potential application for the fabrication of ultra-thin layers for the electronics industry. For this aim, we considered Ti nanoparticles of different diameters and Si substrates of different orientations. It is shown that very high spray velocities are required for a jet to be observed at the nanoscale. We propose a method for thermostating the substrate that enables utilizing high spray velocities. For the first time, we demonstrate an oscillatory behavior in both the normal and radial stress components within the substrate that can propagate into the particle. We have shown that neither the adiabatic shear instability model nor the hydrodynamic plasticity model can be ignored at the nanoscale. Besides, the formation of a low-resistance titanium silicide proper for electronic application is illustrated. © 2024, CC BY-SA.

关键词： Electronics industry

Gain and phase type multipliers for structured feedback robustness

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arXiv 2022年

作者： Ringh, Axel Mao, Xin Chen, Wei Qiu, Li Khong, Sei Zhen Department of Mathematical Sciences Chalmers University of Technology The University of Gothenburg GothenburgSE-412 96 Sweden Department of Electronic and Computer Engineering The Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong Department of Mechanics and Engineering Science State Key Laboratory for Turbulence and Complex Systems Peking University Beijing100871 China Independent Researcher

It is known that the stability of a feedback interconnection of two linear time-invariant systems implies that the graphs of the open-loop systems are quadratically separated. This separation is defined by an object known as the multiplier. The theory of integral quadratic constraints shows that the converse also holds under certain conditions. This paper establishes that if the feedback is robustly stable against certain structured uncertainty, then there always exists a multiplier that takes a corresponding form. In particular, if the feedback is robustly stable to certain gain-type uncertainty, then there exists a corresponding multiplier that is of phase-type, i.e., its diagonal blocks are zeros. These results build on the notion of phases of matrices and systems, which was recently introduced in the field of control. Similarly, if the feedback is robustly stable to certain phase-type uncertainty, then there exists a gain-type multiplier, i.e., its off-diagonal blocks are zeros. The results are meaningfully instructive in the search for a valid multiplier for establishing robust closed-loop stability, and cover the well-known small-gain and the recent small-phase theorems. Copyright © 2022, The Authors. All rights reserved.

关键词： Feedback

Ai Systems' Negative Social Impact and Factors

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SSRN

SSRN 2025年

作者： Ahmad, Nafen Haj Stigholt, Linnea Penzenstadler, Birgit Duboc, Leticia Department of Computer Science and Engineering University of Gothenburg Gothenburg Sweden Department of Computer Science and Engineering University of Chalmers Gothenburg University Gothenburg Sweden Lappeenranta University of Technology Lappeenranta Finland School of Engineering La Salle University Ramon Llull Barcelona Spain

Context: AI technologies are rapidly being integrated into society, offering numerous benefits but also raising significant ethical and social concerns. While some AI systems aim to improve efficiency and decision-making, they can also cause harmful impacts on individuals and ***: This study examines both the immediate and systemic negative effects of AI systems, as well as the underlying factors that might contribute to these ***: Using an adapted systematic mapping study, we analyze 28 AI systems and their associated impacts, including discrimination, psychological and physical harm, and unfair ***: We identify key factors that might have led AI systems to operate in that manner and explain why these impacts may occur. Additionally, we propose initial concrete actions to mitigate these negative effects and promote the development of AI systems that align with ethical and social sustainability ***: By shedding light on these issues, we aim to raise awareness among researchers and developers, encouraging the adoption of more responsible and inclusive AI guidelines. © 2025, The Authors. All rights reserved.

关键词： Ethical technology

Towards human-like automated test generation: Perspectives from cognition and problem solving

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arXiv 2021年

作者： Enoiu, Eduard Paul Feldt, Robert School of Innovation Design and Engineering Mälardalen University Västerås Sweden Department of Computer Science and Engineering Chalmers University of Technology Gothenburg Sweden

Automated testing tools typically create test cases that are different from what human testers create. This often makes the tools less effective, the created tests harder to understand, and thus results in tools providing less support to human testers. Here, we propose a framework based on cognitive science and, in particular, an analysis of approaches to problem solving, for identifying cognitive processes of testers. The framework helps map test design steps and criteria used in human test activities and thus to better understand how effective human testers perform their tasks. Ultimately, our goal is to be able to mimic how humans create test cases and thus to design more human-like automated test generation systems. We posit that such systems can better augment and support testers in a way that is meaningful to them. Copyright © 2021, The Authors. All rights reserved.

关键词： Automation

A large 'discovery' experiment: Gender Initiative for Excellence (Genie) at chalmers university of technology

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QRB Discovery 2021年 2卷 e5页

作者： Saline, Maria Sheeran, Mary Wittung-Stafshede, Pernilla Division of Management and General University Support Chalmers University of Technology Gothenburg Sweden Leadership Group Gender Initiative for Excellence Chalmers University of Technology Gothenburg Sweden Computer Science and Engineering Department Chalmers University of Technology Gothenburg Sweden Biology and Biological Engineering Department Chalmers University of Technology Gothenburg Sweden

Sweden tops gender equality rankings, but Swedish academia is still lacking women in top positions. To address gender inequality in its faculty, chalmers university of technology has invested 300 million SEK (30 million Euros) over 10Â years in Gender initiative for Excellence (Genie). Genie aims to increase the university's success and excellence via gender equality efforts. In this editorial, we want to share insights on explicit efforts during Genie's first 2.5Â years with the goal to inspire and advise other universities and researchers. ©

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Cooperative merging strategy between connected autonomous vehicles in mixed traffic

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TechRxiv

TechRxiv 2022年

作者： Andreotti, Eleonora Selpi Aramrattana, Maytheewat CINECA Supercomputing Inter-University Consortium Bologna40033 Italy The Division of Vehicle Safety Department of Mechanics and Maritime Sciences Chalmers University of Technology GöteborgSE-412 96 Sweden The Department of Computer Science and Engineering The Department of Mechanics and Maritime Sciences Chalmers University of Technology GöteborgSE-412 96 Sweden Linköping Sweden

In this work we propose a new cooperation strategy between connected autonomous vehicles in on-ramps merging scenarios and we implement the cut-in risk indicator (CRI) to investigate the safety effect of the proposed strategy. The new cooperation strategy considers a pair of vehicles approaching an on-ramp. The strategy then makes decisions on the target speeds/accelerations of both vehicles, possible lane changing, and a dynamic decision-making approach in order to reduce the risk during the cut-in manoeuvre. In this work, the CRI was first used to assess the risk during the merging manoeuvre. For this purpose, scenarios with penetration rates of autonomous vehicles from 20% to 100%, with step of 10%, both connected and non-connected autonomous vehicles were evaluated. As a result, on average a 35% reduction of the cut-in risk manoeuvres in connected autonomous vehicles compared to non-connected autonomous vehicles is obtained. It is shown through the analysis of probability density functions characterising the CRI distribution that the reduction is not homogeneous across all indicator values, but depends on the penetration rate and the severity of the manoeuvre. © 2022, CC BY.

关键词： Merging

Measure concentration on the OFDM-Based random access channel

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arXiv 2021年

作者： Wunder, Gerhard Flinth, Axel Groß, Benedikt Department of Computer Science Freie Universität Berlin Berlin Germany Institution for Electrical Engineering Chalmers University of Technology Gothenburg Sweden

It is well known that CS can boost massive random access protocols. Usually, the protocols operate in some overloaded regime where the sparsity can be exploited. In this paper, we consider a different approach by taking an orthogonal FFT base, subdivide its image into appropriate sub-channels and let each subchannel take only a fraction of the load. To show that this approach can actually achieve the full capacity we provide i) new concentration inequalities, and ii) devise a sparsity capture effect, i.e where the sub-division can be driven such that the activity in each each sub-channel is sparse by design. We show by simulations that the system is scalable resulting in a coarsely 30-fold capacity increase. Copyright © 2021, The Authors. All rights reserved.

关键词： Orthogonal frequency division multiplexing

Rethinking Long-Tailed Visual Recognition with Dynamic Probability Smoothing and Frequency Weighted Focusing

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Rethinking Long-Tailed Visual Recognition with Dynamic Proba...

IEEE International Conference on Image Processing

作者： Wan Jun Nah Chun Chet Ng Che-Tsung Lin Yeong Khang Lee Jie Long Kew Zhi Qin Tan Chee Seng Chan Christopher Zach Shang-Hong Lai CISiP Faculty of Comp. Sci. and Info. Tech. Universiti Malaya Kuala Lumpur Malaysia Dept. of Electrical Engineering Chalmers University of Technology Gothenburg Sweden Centre of Excellence ViTrox Corporation Berhad Penang Malaysia Dept. of Computer Science National Tsing Hua University Taiwan

Deep learning models trained on long-tailed (LT) datasets often exhibit bias towards head classes with high frequency. This paper highlights the limitations of existing solutions that combine class- and instance-level re-weighting loss in a naive manner. Specifically, we demonstrate that such solutions result in overfitting the training set, significantly impacting the rare classes. To address this issue, we propose a novel loss function that dynamically reduces the influence of outliers and assigns class-dependent focusing parameters. We also introduce a new long-tailed dataset, ICText-LT, featuring various image qualities and greater realism than artificially sampled datasets. Our method has proven effective, outperforming existing methods through superior quantitative results on CIFAR-LT, Tiny ImageNet-LT, and our new ICText-LT datasets. The source code and new dataset are available at https://***/nwjun/FFDS-Loss.

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Human Factors in Model-Driven engineering: Future Research Goals and Initiatives for MDE

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arXiv 2024年

作者： Liebel, Grischa Klünder, Jil Hebig, Regina Lazik, Christopher Nunes, Inês Graßl, Isabella Steghöfer, Jan-Philipp Exelmans, Joeri Oertel, Julian Marquardt, Kai Juhnke, Katharina Schneider, Kurt Gren, Lucas Happe, Lucia Herrmann, Marc Wyrich, Marvin Tichy, Matthias Goulão, Miguel Wohlrab, Rebekka Kalantari, Reyhaneh Heinrich, Robert Greiner, Sandra Rukmono, Satrio Adi Chakraborty, Shalini Abrahão, Silvia Amaral, Vasco Department of Computer Science Reykjavik University Menntavegur 1 Reykjavik102 Iceland Software Engineering Group Leibniz University Hannover Welfengarten 1 Hannover30167 Germany Department of Software Engineering University of Rostock Albert-Einstein-Straße Rostock18057 Germany Department of Software Engineering Humboldt-Universität zu Berlin Unter den Linden 6 Berlin10099 Germany Frankfurt Germany Department of Software Engineering II University of Passau Innstraße 33 Passau94032 Germany XITASO GmbH Austraße 35 Augsburg86153 Germany Department of Computer Science University of Antwerp Middelheimlaan 1 Antwerp2020 Belgium Department of Informatics Karlsruhe Institute of Technology Am Fasanengarten 5 Karlsruhe75131 Germany SMT-EMI6 Carl Zeiss SMT GmbH Rudolf-Eber-Straße 2 Oberkochen73447 Germany Department of Computer Science and Engineering Chalmers | University of Gothenburg Gothenburg41127 Sweden Department of Interdisciplinary Didactics Karlsruhe Institute of Technology Engesserstr. 2 Karlsruhe75131 Germany Department of Computer Science Saarland University Saarland Informatics Campus Saarbrücken66123 Germany Institute of Software Engineering and Languages Ulm University James-Franck-Ring Ulm89081 Germany Department of Computer Science NOVA School of Science & Technology Campus de Caparica Caparica2829-516 Portugal Department of Engineering Design and Teaching Innovation University of Ottawa 800 King Edward Avenue OttawaK1N6N5 Canada KASTEL - Institute of Information Security and Dependability Karlsruhe Institute of Technology Am Fasanengarten 5 Karlsruhe75131 Germany Department of Computer Science University of Bern Bern3012 Switzerland Department of Mathematics and Computer Science Eindhoven University of Technology De Zaale Eindhoven5600 MB Netherlands Instituto Universitario Mixto de Tecnología Informática Universitat Politècnica de València Camino de Vera s/n Valencia46022 Spain

Purpose: Software modelling and Model-Driven engineering (MDE) is traditionally studied from a technical perspective. However, one of the core motivations behind the use of software models is inherently human-centred. Models aim to enable practitioners to communicate about software designs, make software understandable, or make software easier to write through domain-specific modelling languages. Several recent studies challenge the idea that these aims can always be reached and indicate that human factors play a role in the success of MDE. However, there is an under-representation of research focusing on human factors in modelling. Methods: During a GI-Dagstuhl seminar, topics related to human factors in modelling were discussed by 26 expert participants from research and industry. Results: In breakout groups, five topics were covered in depth, namely modelling human aspects, factors of modeller experience, diversity and inclusion in MDE, collaboration and MDE, and teaching human-aware MDE. Conclusion: We summarise our insights gained during the discussions on the five topics. We formulate research goals, questions, and propositions that support directing future initiatives towards an MDE community that is aware of and supportive of human factors and values. © 2024, CC BY.

关键词： Software design