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arXiv 2024年

作者： Liao, Yuan Gil, Jorge Yeh, Sonia Pereira, Rafael H.M. Alessandretti, Laura Department of Space Earth and Environment Chalmers University of Technology Gothenburg Sweden Department of Architecture and Civil Engineering Chalmers University of Technology Gothenburg Sweden - Brazil Data Science Division Brazil Department of Applied Mathematics and Computer Science Technical University of Denmark Lyngby Denmark

Socio-spatial segregation is the physical separation of different social, economic, or demographic groups within a geographic space, often resulting in unequal access to resources, services, and opportunities. The literature has traditionally focused on residential segregation, examining how individuals' residential locations are distributed differently across neighborhoods based on various social attributes, e.g., race, ethnicity, and income. However, this approach overlooks the complexity of spatial segregation in people's daily activities, which often extend far beyond residential areas. Since the 2010s, emerging mobility data sources have enabled a new understanding of socio-spatial segregation by considering daily activities such as work, school, shopping, and leisure visits. From traditional surveys to GPS trajectories, diverse data sources reveal that daily mobility can result in spatial segregation levels that differ from those observed in residential segregation. This literature review focuses on three critical questions: (a) What are the strengths and limitations of segregation research incorporating extensive mobility data? (b) How do human mobility patterns relate to individuals' residential vs. experienced segregation levels? and (c) What key factors explain the relationship between one's mobility patterns and experienced segregation? Our literature review enhances the understanding of socio-spatial segregation at the individual level and clarifies core concepts and methodological challenges in the field. Our review explores studies of key themes: segregation, activity space, co-presence, and the built environment. By synthesizing their findings, we aim to offer actionable insights for reducing segregation. © 2024, CC BY-SA.

关键词： Leisure

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A ResNet Approach for AoA and AoD Estimation in Analog Millimeter Wave MIMO Systems

A ResNet Approach for AoA and AoD Estimation in Analog Milli...

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IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC)

作者： Diego Lloria Sandra Roger Carmen Botella-Mascarell Maximo Cobos Tommy Svensson Computer Science Department Universitat de Valéncia Burjassot (Valencia) Spain Department of Electrical Engineering Chalmers University of Technology Gothenburg Sweden

ISBN: (数字)9798350362244

ISBN: (纸本)9798350362251

Parametric millimeter-wave (mmWave) channel estimation involves modeling the channel matrix by combining direction-dependent signal paths, exploiting the sparse nature of mmWave channels. In our study, we propose a deep learning-based approach to estimate angle-of-arrival (AoA) and angle-of-departure (AoD) parameters from input observations in the frequency domain. To address this challenge, we have adapted a residual convolutional neural network (ResNet) to this specific problem and incorporated a technique from topological data analysis, enabling us to accurately retrieve the angular frequencies. Furthermore, we have extended this basic architecture by incorporating a posterior model fitting to enhance the system performance in terms of probability of detection. In our research, we compare the ResNet and extended ResNet approaches with state-of-the-art signal processing techniques and the Crámer-Rao lower bound through simulation. Our results indicate significant improvements in system robustness by increasing the probability of detection while maintaining a reduced estimation error.

关键词： Adaptation models Translation Frequency-domain analysis System performance Millimeter wave technology Channel estimation computer architecture Mean square error methods Convolutional neural networks Millimeter wave communication

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Revolutionizing Image Recognition: Next-Generation CNN Architectures for Handwritten Digits and Objects

Revolutionizing Image Recognition: Next-Generation CNN Archi...

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IEEE Symposium on Wireless technology and Applications (ISWTA)

作者： Md Nurul Absur Kazi Fahim Ahmad Nasif Sourya Saha Sifat Nawrin Nova Department of Computer Science City University of New York New York USA College of Computing and Software Engineering Kennesaw State University Georgia USA Department of Computer Science Chalmers University of Technology Gothenburg Sweden

ISBN: (数字)9798350351354

ISBN: (纸本)9798350351361

This study addresses the pressing need for computer systems to interpret digital media images with a level of sophistication comparable to human visual perception. By leveraging Convolutional Neural Networks (CNNs), we introduce two innovative architectures tailored to distinct datasets: the MNIST handwritten digit dataset and the Fashion MNIST dataset. Unlike traditional machine learning methods such as Support Vector Machines (SVM) and Random Forests, our customized CNN models remarkably enhance image attribute comprehension and recognition accuracy. Specifically, the model developed for the MNIST dataset achieved an unprecedented accuracy of 98.71% without any bias, while the Fashion MNIST model reached 91.39%, marking significant advancements over conventional algorithms without any bias. This research showcases the superior efficiency of CNNs in processing and understanding digital images. It underscores the potential of deep learning technologies in bridging the gap between computational systems and human-like visual recognition. Through meticulous experimentation and analysis, we illustrate how deep CNNs require less preparatory work than other image-processing algorithms, setting a new benchmark in computer vision.

关键词： Support vector machines Handwriting recognition Visualization Accuracy Image recognition Computational modeling computer architecture

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Special Issue on HMI and Autonomous Driving

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Automotive Innovation 2020年第1期3卷 1-2页

作者： Fang Chen Department of Computer Science and Engineering Chalmers University of TechnologyGothenburgSweden

Human-machine interaction(HMI)is about the interaction design inside the cockpit of *** takes the human-centered design approach related to systems that help driver or passengers’communication with *** safer driving and more effective communication between the human and the vehicle is the central *** design challenges have changed a lot due to the increasing level of autonomous *** kind of interaction will be the mainstream?How would a driver’s personality influence the driver’s attitude toward active safety and trust of the autonomous driving?How should HMI be designed for the handover scenarios from Level 3 to Level 5 autonomous driving?What HMI solutions make the driving safer and improve user experience?

关键词： communication driving HMI

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Near-Far Field Channel Modeling for Holographic MIMO Using Expectation-Maximization Methods

arXiv

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arXiv 2024年

作者： Chen, Houfeng Zeng, Shuhao Guo, Hao Svensson, Tommy Zhang, Hongliang School of Electronic Engineering and Computer Science Peking University Beijing China Department of Electronics Peking University Beijing China Department of Electrical Engineering Chalmers University of Technology Gothenburg Sweden

Holographic Multiple-Input Multiple-Output (HMIMO), which densely integrates numerous antennas into a limited space, is anticipated to provide higher rates for future 6G wireless communications. The increase in antenna aperture size makes the near-field region enlarge, causing some users to be located in the near-field region. Thus, we are facing a hybrid near-field and far-field communication problem, where conventional far-field modeling methods may not work well. In this paper, we propose a near-far field channel model that does not presuppose whether each path is near-field or far-field, different from the existing work requiring the ratio of the number of near-field paths to that of far-field paths as prior knowledge. However, this gives rise to a new challenge for accurately modeling the channel, as conventional methods of obtaining channel model parameters are not applicable to this model. Therefore, we propose a new method, Expectation-Maximization (EM)-based Near-Far Field Channel Modeling, to obtain channel model parameters, which considers whether each path is near-field or far-field as a hidden variable, and optimizes the hidden variables and channel model parameters through an alternating iteration method. Simulation results show that our method is superior to conventional near-field and far-field algorithms in fitting the near-far field channel in terms of outage probability. Copyright © 2024, The Authors. All rights reserved.

关键词： MIMO systems

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Near-Far Field Channel Modeling for Holographic MIMO Using Expectation-Maximization Methods

Near-Far Field Channel Modeling for Holographic MIMO Using E...

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IEEE Conference on Wireless Communications and Networking

作者： Houfeng Chen Shuhao Zeng Hao Guo Tommy Svensson Hongliang Zhang School of Electronic Engineering and Computer Science Peking University Beijing China Department of Electronics Peking University Beijing China Department of Electrical Engineering Chalmers University of Technology Gothenburg Sweden

ISBN: (数字)9798350303582

ISBN: (纸本)9798350303599

Holographic Multiple-Input Multiple-Output (HMIMO), which densely integrates numerous antennas into a limited space, is anticipated to provide higher rates for future 6G wireless communications. The increase in antenna aperture size makes the near-field region enlarge, causing some users to be located in the near-field region. Thus, we are facing a hybrid near-field and far-field communication problem, where conventional far-field modeling methods may not work well. In this paper, we propose a near-far field channel model that does not presuppose whether each path is near-field or far-field, different from the existing work requiring the ratio of the number of near-field paths to that of far-field paths as prior knowledge. However, this gives rise to a new challenge for accurately modeling the channel, as conventional methods of obtaining channel model parameters are not applicable to this model. Therefore, we propose a new method, Expectation-Maximization (EM)-based Near-Far Field Channel Modeling, to obtain channel model parameters, which considers whether each path is near-field or far-field as a hidden variable, and optimizes the hidden variables and channel model parameters through an alternating iteration method. Simulation results show that our method is superior to conventional near-field and far- field algorithms in fitting the near-far field channel in terms of outage probability.

关键词： Wireless communication Adaptation models Accuracy Simulation Fitting Probability Aperture antennas

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OpEx driven software architecture a case study 15

OpEx driven software architecture a case study

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15th European Conference on Software Architecture - Companion, ECSA-C 2021

作者： Andreo, Sebastien Calà, Ambra Bosch, Jan Siemens AG Technology Erlangen Germany Department of Computer Science and Engineering Chalmers University of Technology Göteborg Sweden

In the last thirty years, the software industry has changed how systems are architected and how systems are distributed. Software is moving from a monolithic architecture and locally installed application to micro-services architecture and applications accessible through the internet. The accessibility over the internet is provided by the emergence of cloud providers like Amazon AWS, Microsoft Azure, or Google GCP. This transformation also impacts the financial structure of software projects, which is moving from capital expenditure (CapEx) to operational expenditure (OpEx). This paper highlights the implication of architecture decisions on a cloud application’s operating cost based on two industrial case studies. © 2021 Copyright for this paper by its authors. Use permitted under Creative Commons License Attribution 4.0 International (CC BY 4.0).

关键词： Windows operating system

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On the Performance of Multidimensional Constellation Shaping for Linear and Nonlinear Optical Fiber Channel

arXiv

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arXiv 2023年

作者： Chen, Bin Liang, Zhiwei Li, Shen Lei, Yi Liga, Gabriele Alvarado, Alex School of Computer Science and Information Engineering Hefei University of Technology China Department of Electrical Engineering Chalmers University of Technology Gothenburg Sweden Department of Electrical Engineering Eindhoven University of Technology Netherlands

Multidimensional constellation shaping of up to 32 dimensions with different spectral efficiencies are compared through AWGN and fiber-optic simulations. The results show that no constellation is universal and the balance of required and effective SNRs should be jointly considered for the specific optical transmission scenario. ©2023 The Author(s) © 2023, CC BY-NC-SA.

关键词： Light transmission

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Compressed Sensing Inspired User Acquisition for Downlink Integrated Sensing and Communication Transmissions

Compressed Sensing Inspired User Acquisition for Downlink In...

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IEEE International Conference on Communications (ICC)

作者： Yi Song Fernando Pedraza Shuangyang Li Siyao Li Han Yu Giuseppe Caire Faculty of Electrical Engineering and Computer Science Technical University of Berlin Berlin Germany Department of Electrical Engineering University of Alaska Anchorage USA Department of Electrical Engineering Chalmers University of Technology Gothenburg Sweden

ISBN: (数字)9781728190549

ISBN: (纸本)9781728190556

This paper investigates radar-assisted user acquisition for downlink multi-user multiple-input multiple-output (MIMO) transmission using Orthogonal Frequency Division Multiplexing (OFDM) signals. Specifically, we formulate a concise mathematical model for the user acquisition problem, where each user is characterized by its delay and beamspace response. Therefore, we propose a two-stage method for user acquisition, where the Multiple Signal Classification (MUSIC) algorithm is adopted for delay estimation, and then a least absolute shrinkage and selection operator (LASSO) is applied for estimating the user response in the beamspace. Furthermore, we also provide a comprehensive performance analysis of the considered problem based on the pair-wise error probability (PEP). Particularly, we show that the rank and the geometric mean of non-zero eigenvalues of the squared beamspace difference matrix determines the user acquisition performance. More importantly, we reveal that simultaneously probing multiple beams outperforms concentrating power on a specific beam direction in each time slot under the power constraint, when only limited OFDM symbols are transmitted. Our numerical results confirm our conclusions and also demonstrate a promising acquisition performance of the proposed two-stage method.

关键词： Pairwise error probability OFDM Estimation Symbols Pattern classification Downlink Mathematical models

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engineering Safety Requirements for Autonomous Driving with Large Language Models

Engineering Safety Requirements for Autonomous Driving with ...

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IEEE International Conference on Requirements engineering

作者： Ali Nouri Beatriz Cabrero-Daniel Fredrik Törner Håkan Sivencrona Christian Berger Volvo Cars Gothenburg Sweden Chalmers University of Technology Gothenburg Sweden Department of Computer Science and Engineering University of Gothenburg Gothenburg Sweden Zenseact Gothenburg Sweden

ISBN: (数字)9798350395112

ISBN: (纸本)9798350395129

Changes and updates in the requirement artifacts, which can be frequent in the automotive domain, are a challenge for SafetyOps. Large Language Models (LLMs), with their impressive natural language understanding and generating capabilities, can play a key role in automatically refining and decomposing requirements after each update. In this study, we propose a prototype of a pipeline of prompts and LLMs that receives an item definition and outputs solutions in the form of safety requirements. This pipeline also performs a review of the requirement dataset and identifies redundant or contradictory requirements. We first identified the necessary characteristics for performing HARA and then defined tests to assess an LLM's capability in meeting these criteria. We used design science with multiple iterations and let experts from different companies evaluate each cycle quantitatively and qualitatively. Finally, the prototype was implemented at a case company and the responsible team evaluated its efficiency.

关键词： Reviews Large language models Pipelines Refining Prototypes Companies Natural language processing

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