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Positive definiteness of real quadratic forms resulting from the variable-step L1-type approximations of convolution operators

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Science China Mathematics 2024年第2期67卷 237-252页

作者： Hong-Lin Liao Tao Tang Tao Zhou School of Mathematics Nanjing University of Aeronautics and AstronauticsNanjing 211106China Division of Science and Technology BNU-HKBU United International CollegeZhuhai 519087China SUSTech International Center for Mathematics Shenzhen 518055China NCMIS&LSEC Institute of Computational Mathematics and Scientific/Engineering ComputingAcademy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing 100190China

The positive definiteness of real quadratic forms with convolution structures plays an important rolein stability analysis for time-stepping schemes for nonlocal operators. In this work, we present a novel analysistool to handle discrete convolution kernels resulting from variable-step approximations for convolution *** precisely, for a class of discrete convolution kernels relevant to variable-step L1-type time discretizations, weshow that the associated quadratic form is positive definite under some easy-to-check algebraic conditions. Ourproof is based on an elementary constructing strategy by using the properties of discrete orthogonal convolutionkernels and discrete complementary convolution kernels. To our knowledge, this is the first general result onsimple algebraic conditions for the positive definiteness of variable-step discrete convolution kernels. Using theunified theory, we obtain the stability for some simple nonuniform time-stepping schemes straightforwardly.

关键词： discrete convolution kernels positive definiteness variable time-stepping orthogonal convolution kernels complementary convolution kernels

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Design of a Multi-Degree-of-Freedom Elastic Neck Exoskeleton for Persons with Dropped Head Syndrome

Design of a Multi-Degree-of-Freedom Elastic Neck Exoskeleton...

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IEEE International Conference on Soft Robotics (RoboSoft)

作者： Santiago Price Torrendell Yang Chen Hideki Kadone Modar Hassan Kenji Suzuki Graduate School of Systems & Information Engineering University of Tsukuba Ibaraki Japan Center for Innovative Medicine and Engineering University of Tsukuba Hospital Japan Faculty of Systems Information and Engineering University of Tsukuba Tsukuba Japan

Nonsurgical treatment of Dropped Head Syndrome (DHS) incurs the use of collar-type orthoses that immobilize the neck and cause discomfort and sores under the chin. Articulated orthoses have the potential to support the head posture while allowing partial mobility of the neck and reduced discomfort and sores. This work presents the design, modeling, development, and characterization of a novel multi-degree-of-freedom elastic mechanism designed for neck support. This new type of elastic mechanism allows the bending of the head in the sagittal and coronal planes, and head rotations in the transverse plane. From these articulate movements, the mechanism generates moments that restore the head and neck to the upright posture, thus compensating for the muscle weakness caused by DHS. The experimental results show adherence to the empirical characterization of the elastic mechanism under flexion to the model-based calculations. A neck support orthosis prototype based on the proposed mechanism is presented, which enables the three before-mentioned head motions of a healthy participant, according to the results of preliminary tests.

关键词： Biomechanics Biological system modeling Exoskeletons Prototypes Soft robotics Predictive models Muscles

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A Human-Flow Analysis Based on PCA:A Case Study on Population Data Near Railway 2

A Human-Flow Analysis Based on PCA:A Case Study on Populatio...

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2nd International Conference on Robotics, Automation and Artificial Intelligence, RAAI 2022

作者： Kim, SeongIn Shibuya, Takeshi Toride, Shingo Endo, Yasunori University of Tsukuba Programs in Intelligent and Mechanical Interaction Systems Tsukuba Japan University of Tsukuba Faculty of Engineering Information and Systems Tsukuba Japan National Research Institute for Earth Science and Disaster Prevention Disaster Information Research Division Tsukuba Japan

ISBN: (纸本)9781665459440

The damage caused by natural disasters and accidents is increasing every year. To reduce such damage from spreading, it is important to detect an accident promptly. However, current sensing systems are difficult to use because they have narrow coverage and are specialized in few detectable accidents. In this paper, we propose a method to detect disasters and accidents by calculating the degree of an anomaly in human flow by treating a common human flow as a single large sensor. Human flow can be assumed to have typical patterns in people's daily life, such as going to work and leaving work. Developing an anomaly detection method of human flow can lead to the discovery of any hidden causes such as accidents and disasters. In this paper, we study a method that aims to detect anomalies in human flow, considering the operational status of railways as an example. We confirm that our method can detect the actual suspension of operations. © 2022 IEEE.

关键词： Principal component analysis

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How to prevent technostress at the digital workplace: a Delphi study

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Journal of Business Economics 2024年第7-8期94卷 1051-1113页

作者： Berger, Michelle Schäfer, Ricarda Schmidt, Marco Regal, Christian Gimpel, Henner FIM Research Center for Information Management Augsburg 86159 Germany Branch Business & Information Systems Engineering of the Fraunhofer FIT Alter Postweg 101 Augsburg 86159 Germany Department of Digital Management University of Hohenheim Schloss Hohenheim 1 Stuttgart 70599 Germany University of Augsburg Universitätsstraße 2 Augsburg 86158 Germany

Technostress is a rising issue in the changing world of digital work. Technostress can cause severe adverse outcomes for individuals and organizations. Thus, organizations face the moral, legal, and economic responsibility to prevent employees’ excessive technostress. As technostress develops over time, it is crucial to prevent it throughout the process of its emergence instead of only reacting after adverse outcomes occur. Contextualizing the Theory of Preventive Stress management to technostress, we synthesize and advance existing knowledge on inhibiting technostress. We develop a set of 24 technostress prevention measures from technostress inhibitor literature, other technostress literature, and based on qualitative and quantitative contributions from a Delphi study. Based on expert feedback, we characterize each measure and, where possible, assess its relevance in addressing specific technostressors. Our paper contributes to research by transferring the Theory of Preventive Stress Management into the context of technostress and presenting specific measures to prevent technostress. This offers a complementary view to technostress inhibitors by expanding the theoretical grounding and adding a time perspective through the implementation of primary, secondary, and tertiary prevention measures. For practice, we offer a comprehensive and applicable overview of measures organizations can implement to prevent technostress. © 2023, The Author(s).

关键词： Delphi study I12 M15 O33 Technostress Technostress creators Technostress inhibitors Technostress prevention

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Indirect Vector Control of Linear Induction Motors Using Space Vector Pulse Width Modulation

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Computers, Materials & Continua 2023年第3期74卷 6263-6287页

作者： Arjmand Khaliq Syed Abdul Rahman Kashif Fahad Ahmad Muhammad Anwar Qaisar Shaheen Rizwan Akhtar Muhammad Arif Shah Abdelzahir Abdelmaboud Electrical Engineering Department University of Engineering and TechnologyLahore54700Pakistan Department of Basic Sciences Deanship of Common First YearJouf UniversitySakakaAljouf72341Saudi Arabia Department of Information Science Division of Science and TechnologyUniversity of EducationLahore54000Pakistan Department of Computer Science and Information Technology The Islamia University of BahawalpurRahim Yar Khan Sub CampusPakistan Department of IT and Computer Science Pak-Austria Fachhochschule Institute of Applied Sciences and TechnologyHaripurPakistan Department of Information Systems King Khalid UniversityMuhayel Aseer61913Saudi Arabia

Vector control schemes have recently been used to drive linear induction motors(LIM)in high-performance *** trend promotes the development of precise and efficient control schemes for individual *** research aims to present a novel framework for speed and thrust force control of LIM using space vector pulse width modulation(SVPWM)*** framework under consideration is developed in four *** begin,MATLAB Simulink was used to develop a detailed mathematical and electromechanical *** research presents a modified SVPWM inverter control *** tuning the proportional-integral(PI)controller with a transfer function,optimized values for the PI controller are *** the subsystems mentioned above are integrated to create a robust simulation of the LIM’s precise speed and thrust force control *** reference speed values were chosen to evaluate the performance of the respective system,and the developed system’s response was verified using various data *** the low-speed range,a reference value of 10m/s is used,while a reference value of 100 m/s is used for the high-speed *** speed output response indicates that themotor reached reference speed in amatter of seconds,as the delay time is between 8 and 10 *** maximum amplitude of thrust achieved is less than 400N,demonstrating the controller’s capability to control a high-speed LIM with minimal thrust *** to the controlled speed range,the developed system is highly recommended for low-speed and high-speed and heavy-duty traction applications.

关键词： Space vector pulse width modulation linear induction motor proportional-integral controller indirect vector control electromechanical dynamic modeling

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Modeling Dynamics of Highly Flexible Aircraft Using a Geometrically Nonlinear Structural Model

Modeling Dynamics of Highly Flexible Aircraft Using a Geomet...

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AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2025

作者： Tuzcu, Ilhan Nguyen, Nhan Department of Mechanical Engineering California State University Mail Stop 6031 SacramentoCA95819 United States Intelligent Systems Division NASA Ames Research Center Mail Stop 269-1 Moffett Field CA94035 United States

ISBN: (纸本)9781624107238

Recent trend in industry is to built less fuel-consuming aircraft per unit payload carried, which requires significant reduction in structural weight to increase payload capacity. As a result, today’s aircraft designs are considerably more flexible than the aircraft of the past. This paper aims to contribute toward development of an aircraft model to accurately predict adverse effects of flexibility on overall motions of aircraft. The model developed uses the fundamental principles to seamlessly bring together not only rigid body degrees of freedom of an aircraft as a whole, but also elastic degrees of freedom of its wing. The structural model is based on a geometrically nonlinear beam theory to allow large elastic deformations of the wing. A Vortex Lattice Method (VLM) aerodynamic model is constructed to account for 3-D distribution of the aerodynamic forces over all lifting surfaces including wing, and horizontal and vertical stabilizers. Unsteady aerodynamics is accounted for by the application of a lift deficiency factor. The final equations of motion representing the integrated model of a high-altitude-long-endurance UAV are used to compute trim (equilibrium) states for steady flights including steady level flight, steady climb, steady level turn, and gliding. The equations are then linearized about the equilibrium states to address flutter of the UAV in these steady flight regimes. Post flutter behavior of the UAV is addressed by simulating the response of the aircraft to some initial conditions. © 2025, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Degrees of freedom (mechanics)

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Design of a Multi-Degree-of-Freedom Elastic Neck Exoskeleton for Persons with Dropped Head Syndrome

arXiv

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arXiv 2023年

作者： Torrendell, Santiago Price Chen, Yang Kadone, Hideki Hassan, Modar Suzuki, Kenji The Graduate School of Systems & Information Engineering University of Tsukuba Ibaraki Japan The Center for Innovative Medicine and Engineering University of Tsukuba Hospital Japan The Faculty of Systems Information and Engineering University of Tsukuba Tsukuba Japan

关键词： Degrees of freedom (mechanics)

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Distributed Optimization with Finite Bit Adaptive Quantization for Efficient Communication and Precision Enhancement 63

Distributed Optimization with Finite Bit Adaptive Quantizati...

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63rd IEEE Conference on Decision and Control, CDC 2024

作者： Rikos, Apostolos I. Jiang, Wei Charalambous, Themistoklis Johansson, Karl H. Artificial Intelligence Thrust of the Information Hub Guangzhou China The Hong Kong University of Science and Technology Department of Computer Science and Engineering Clear Water Bay Hong Kong Aalto University School of Electrical Engineering Department of Electrical Engineering and Automation Espoo Finland University of Cyprus School of Engineering Department of Electrical and Computer Engineering Nicosia1678 Cyprus Kth Royal Institute of Technology Division of Decision and Control Systems StockholmSE-100 44 Sweden

ISBN: (纸本)9798350316339

In realistic distributed optimization scenarios, individual nodes possess only partial information and communicate over bandwidth constrained channels. For this reason, the development of efficient distributed algorithms is essential. In our paper we addresses the challenge of unconstrained distributed optimization. In our scenario each node's local function exhibits strong convexity with Lipschitz continuous gradients. The exchange of information between nodes occurs through 3-bit bandwidth-limited channels (i.e., nodes exchange messages represented by a only 3 -bits). Our proposed algorithm respects the network's bandwidth constraints by leveraging zoom-in and zoom-out operations to adjust quantizer parameters dynamically. We show that during our algorithm's operation nodes are able to converge to the exact optimal solution. Furthermore, we show that our algorithm achieves a linear convergence rate to the optimal solution. We conclude the paper with simulations that highlight our algorithm's unique characteristics. © 2024 IEEE.

关键词： Bandwidth

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Mainline Lane Management Strategies for Mixed Traffic with Connected Autonomous Vehicles on Urban Expressway Merging Areas 27

Mainline Lane Management Strategies for Mixed Traffic with C...

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27th IEEE International Conference on Intelligent Transportation systems, ITSC 2024

作者： Ran, Changhao Wu, Chaozhong Zhang, Hui Ding, Naikan Tian, Kai Wu, Huiyu Huang, Zhen Wang, Xu Wuhan University of Technology Intelligent Transportation Systems Research Center Engineering Research Center of Transportation Information and Safety Ministry of Education Wuhan China School of Automation Wuhan University of Technology Wuhan430070 China School of Qilu Transportation Shandong University Jinan250002 China

ISBN: (纸本)9798331505929

With the rapid advancement of autonomous driving technology, the impact of connected autonomous vehicles (CAVs) on traffic safety and stability has garnered significant attention. This study aims to evaluate different mainline lane management strategies and CAV penetration rates on mixed traffic safety at urban expressway merging areas. Utilizing measured vehicle trajectory data from an urban expressway merging area, a deep learning-based mandatory lane changing model is established for human-driven vehicles' (HDVs) merging behavior. Considering the overall effect of CAV dedicated lanes or priority lanes layout and CAV penetration rates on mixed traffic distribution on the mainline, a series of simulations are conducted in SUMO with secondary development. Compared to various mainline lane management strategies, designating the outer mainline lane as the CAV dedicated lane results in fewer conflicts between vehicles. In this scenario, as the CAV penetration rate increases from 20% to 80%, the number of conflicts decreases by 3.47% to 9.81 % compared to no lane management strategy. Implementing a proper mainline lane management strategy can enhance the safety of mixed traffic at urban expressway merging areas. © 2024 IEEE.

关键词： Highway administration

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Principal eigenstate classical shadows 37

Principal eigenstate classical shadows

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37th Annual Conference on Learning Theory, COLT 2024

作者： Grier, Daniel Pashayan, Hakop Schaeffer, Luke Department of Mathematics Department of Computer Science and Engineering University of California San Diego United States Dahlem Center for Complex Quantum Systems Freie Universität Berlin Germany Joint Center for Quantum Information and Computer Science University of Maryland College Park United States

Given many copies of an unknown quantum state ρ, we consider the task of learning a classical description of its principal eigenstate. Namely, assuming that ρ has an eigenstate |〉 with (unknown) eigenvalue λ > 1/2, the goal is to learn a (classical shadows style) classical description of |〉 which can later be used to estimate expectation values 〈|O|〉 for any O in some class of observables. We consider the sample-complexity setting in which generating a copy of ρ is expensive, but joint measurements on many copies of the state are possible. We present a protocol for this task scaling with the principal eigenvalue λ and show that it is optimal within a space of natural approaches, e.g., applying quantum state purification followed by a single-copy classical shadows scheme. Furthermore, when λ is sufficiently close to 1, the performance of our algorithm is optimal-matching the sample complexity for pure state classical shadows. © 2024 D. Grier, H. Pashayan & L. Schaeffer.

关键词： Quantum theory

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