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arXiv 2023年

作者： Mabrok, M.A. Aksikas, Ilyasse Meskin, Nader Mathematics Program Department of Mathematics Statistics and Physics College of Arts and Sciences Qatar University P.O. box 2713 Doha Qatar Electircal Engineering Department College of Engineering Qatar University Qatar

Nonlinear Negative Imaginary (NI) systems arise in various engineering applications, such as controlling flexible structures and air vehicles. However, unlike linear NI systems, their theory is not well-developed. In this paper, we propose a data-driven method for learning a lifted linear NI dynamics that approximates a nonlinear dynamical system using the Koopman theory, which is an operator that captures the evolution of nonlinear systems in a lifted high-dimensional space. The linear matrix inequality that characterizes the NI property is embedded in the Koopman framework, which results in a non-convex optimization problem. To overcome the numerical challenges of solving a non-convex optimization problem with nonlinear constraints, the optimization variables are reformatted in order to convert the optimization problem into a convex one with the new variables. We compare our method with local linearization techniques and show that our method can accurately capture the nonlinear dynamics and achieve better control performance. Our method provides a numerically tractable solution for learning the Koopman operator under NI constraints for nonlinear NI systems and opens up new possibilities for applying linear control techniques to nonlinear NI systems without linearization approximations. © 2023, CC BY.

关键词： Flexible structures

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Bacterial Mobility and Motility in Porous Media Mimicked By Microspheres

SSRN

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SSRN 2022年

作者： Shrestha, Diksha Ou, Jun Rogers, Ariel Jereb, Amani Wang, Yong Department of Physics Cell and Molecular Graduate Program Materials Science and Engineering Program University of Arkansas FayettevilleAR72701 United States Department of Environmental Resources Engineering Mechanical Engineering Program California State Polytechnic University Humboldt ArcataCA95521 United States

Bacterial motion in porous media are essential for their survival, proper functioning, and variousapplications. Here we investigated the motion of Escherichia coli bacteria in microsphere-mimicked porousmedia. We observed reduced bacterial velocity and enhanced directional changes of bacteria as the densityof microspheres increased, while such changes happened mostly around the microspheres and due to thecollisions with the microspheres. More importantly, we established and quantified the correlation betweenthe bacterial trapping in porous media and the geometric confinement imposed by the microspheres. In addition,numerical simulations showed that the active Brownian motion model in the presence of microspheresresulted in bacterial motion that are consistent with the experimental observations. Our study suggested thatit is important to distinguish the ability of bacteria to move easily – bacterial mobility – from the abilityof bacteria to move independently – bacteria motility. Our results showed that bacterial motility remainssimilar in porous media, but bacterial mobility was significantly affected by the pore-scale confinement. © 2022, The Authors. All rights reserved.

关键词： Microspheres

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TEMPERATURE AND RATE EFFECTS IN DAMAGE AND DECOHESION OF BIOLOGICAL MATERIALS

arXiv

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arXiv 2022年

作者： Bellino, Luca XXXIV PH.D. Program in Mechanical and Management Engineering India MAT/07 - Mathematical Physics Italy

The incredible thermo-mechanical properties of biological materials arise from the microscopic scale due to a complex hierarchical mechanism, which is regulated by microinstabilities at the molecular level. The description of such complex structures is allowed by both the know-how introduced by the advent of single molecule force spectroscopy experiments, which gives the possibility of studying such systems in different thermal and mechanical conditions, and the possibility of correctly mimicking their behaviour at the lowest scale by introducing mathematical models based on non-convex energies. In this thesis, different classes of models are introduced to describe the important features of phase transition, decohesion and damage under different conditions of applied forces and displacement, thermal fields and rates of loading. By increasing the level of complexity of such models, different phenomena have been analyzed. For instance, by introducing a chain of bistable units to mimic the behaviour of a titin molecule undergoing unfolding, it has been described the effect of the handling device in single molecule experiments, which strongly affects the system’s mechanical response, leading to large errors in the measure of the resulting force or displacement. Temperature effects are considered within a Statistical Mechanics framework, also in the case when non local interactions are introduced. Indeed, phenomena such as the presence of a stress peak in the force-extension diagram and corresponding to the generation and nucleation of a phase is experimentally observed in tensile tests on memory shape nanowires or polymer materials and can be described as a competition between interfacial energy terms and entropic effects. The cooperativity of weak interactions, such as hydrogen bonds, has been also studied to highlight phenomena such as decohesion and fracture in biological systems. Indeed, simple amino acids are arranged in a multiscale fashion resulting in high perfo

关键词： Statistical mechanics

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Development of application Information System in Rhee District 1

Development of application Information System in Rhee Distri...

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1st Virtual Conference on engineering, Science and Technology, ViCEST 2020

作者： Esabella, Shinta Intan, Hikmawati Hidayatullah, Muhammad Andriani, Titi Gunawan, G. Informatics Department Faculty of Engineering Universitas Teknologi Sumbawa Indonesia Electrical Engineering Department Faculty of Engineering Universitas Teknologi Sumbawa Indonesia Physics Education Study Program Faculty of Teacher Training and Education Universitas Mataram Indonesia

Management of patient data at the Technical Implementation Unit of the Community Health Center (UPT. Puskesmas) of Rhee Sumbawa District has not been fully computerized. The need for the development of an Information System to store medical records (history) of patient data. The research aims to develop information systems with descriptive research methods. For software development methods using Waterfall Models and built with Microsoft Visual Studio C# software and databases stored in Microsoft SQL Server software. Software testing uses Black Box Testing, which is testing software in functional terms. The results of research into digital data technology products that function to enter, change, delete data and minimize the time to find the data needed to improve the effectiveness and efficiency of data management. © Published under licence by IOP Publishing Ltd.

关键词： Information management

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Autonomous Electron Tomography Reconstruction Using Bayesian Optimization

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Microscopy and microanalysis : the official journal of Microscopy Society of America, Microbeam Analysis Society, Microscopical Society of Canada 2023年第1期29卷 1915-1916页

作者： Millsaps, William Schwartz, Jonathan Di, Zichao Wendy Jiang, Yi Hovden, Robert Department of Nuclear Engineering Radiological Sciences University of Michigan Ann Arbor MI United States Department of Materials Science and Engineering University of Michigan Ann Arbor MI United States Mathematics and Computer Science Division Argonne National Laboratory Lemont IL United States Advanced Photon Source Facility Argonne National Laboratory Lemont IL United States Applied Physics Program University of Michigan Ann Arbor MI United States

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Maximum Likelihood Estimation for LOR Identification of Positron + Prompt Gamma Ray Emitters in Multiplexed PET (mPET)

Maximum Likelihood Estimation for LOR Identification of Posi...

引用

IEEE Symposium on Nuclear Science (NSS/MIC)

作者： S. J. Zou G. Chinn C. S. Levin Electrical Engineering Stanford University Stanford California United States of America Stanford University Radiology Stanford California United States of America Electrical Engineering Bioengineering Physics Molecular Imaging Program Stanford University Radiology Stanford California United States of America

ISBN: (数字)9798350388152

ISBN: (纸本)9798350388169

For many diseases applications, it is beneficial to simultaneously observe multiple biomarkers at a time. However, current PET systems are unable to image multiple tracers in one session due to annihilation photons being indistinguishable across radiotracers. However with the utilization of one or more positron emitting radionuclides that also emit a prompt gamma (positron + prompt gamma ray emitter), the latter signal can be used to unmix the tracer signals and facilitate multiplex PET or mPET. With the use of prompt-gamma-positron emitters, an issue arises with the correct identification of the two annihilation photons in a triple photon coincidence. In this work, we present a maximum likelihood estimation (MLE) framework that uses spatial, timing, and energy information to return the most probable line of response (LOR). We validate our method using simulated data. Results indicate we can achieve > 99% accuracy at identifying the correct LOR for a 22 Na source.

关键词： Multiplexing Maximum likelihood estimation Microwave integrated circuits Semiconductor detectors Gamma-rays Positrons Timing

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Field-controlled dynamics of skyrmions and monopoles

arXiv

引用

arXiv 2023年

作者： Tai, Jung-Shen B. Hess, Andrew J. Wu, Jin-Sheng Smalyukh, Ivan I. Department of Physics Chemical Physics Program University of Colorado BoulderCO80309 United States Department of Electrical Computer and Energy Engineering Materials Science and Engineering Program Soft Materials Research Center University of Colorado BoulderCO80309 United States Renewable and Sustainable Energy Institute National Renewable Energy Laboratory University of Colorado BoulderCO80309 United States

Magnetic monopoles, despite their ongoing experimental search as elementary particles, have inspired the discovery of analogous excitations in condensed matter systems. In chiral condensed matter systems, emergent monopoles are responsible for the onset of transitions between topologically distinct states and phases, like in the case of transitions from helical and conical phase to A-phase comprising periodic arrays of skyrmions. By combining numerical modeling and optical characterizations, we describe how different geometrical configurations of skyrmions terminating at monopoles can be realized in liquid crystals and liquid crystal ferromagnets. We demonstrate how such complex structures can be effectively manipulated by external magnetic and electric fields. Furthermore, we discuss how our findings may hint at similar dynamics in other physical systems, and their potential applications. © 2023, CC BY.

关键词： Liquid crystals

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Visual Localization of Intersections on Autonomous Vehicles Based on HD Map

Visual Localization of Intersections on Autonomous Vehicles ...

引用

International Conference on Control, Automation and Systems ( ICCAS)

作者： Bizza S. Utsula Muhammad D. Ashedananta Nadana A. Azis Yul Y. Nazaruddin Vebi Nadhira Department of Engineering Physics Faculty of Industrial Technology Institut Teknologi Bandung Bandung Indonesia Engineering Physics Doctoral Program Faculty of Industrial Technology Institut Teknologi Bandung Bandung Indonesia Faculty of Industrial Technology Instrumentation and Control Research Group Institut Teknologi Bandung Bandung Indonesia

The increasing number of autonomous vehicles will result in a safety factor that must be maintained. One of the crucial prerequisites for this is proper localization, especially at intersections where most road accidents occur each year. This research is proposed to improve the localization process, which has drawbacks such as the inaccurate Global Positioning System (GPS) when satellite signals are blocked, and Light Detection and Ranging (LiDAR), which is expensive and needs heavy computing time. This is done by implementing the High Definition Map (HD Map) method, which maps the condition of an area that is stored as memory on an autonomous vehicle computer. The proposed system uses a monocular camera to be processed into a semantic segmentation feature map at the pixel level, then uses point cloud to reconstruct a 3D intersection model, which is then segmented semantically as well so that position data is obtained after merging using the occupancy grid and scoring function. The results of this CNN-based approach localization produce less accuracy and Mean Intersection over Union (MIoU) values with 60% average accuracy and 62.3 MioU when compared to GPS data and other 3D semantic segmentation systems, but the proposed approach can save costs and computational burden.

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Many-body multipole index and bulk-boundary correspondence

引用

Physical Review B 2023年第23期108卷 235150-235150页

作者： Yasuhiro Tada Masaki Oshikawa Quantum Matter Program Graduate School of Advanced Science and Engineering Hiroshima University Higashihiroshima Hiroshima 739-8530 Japan Institute for Solid State Physics University of Tokyo Kashiwa 277-8581 Japan

We propose dipole and quadrupole indices for interacting insulators with point group symmetries. The proposed indices are defined in terms of many-body quantum multipole operators combined with the generator of the point group symmetry. Unlike the original multipole operators, these combined operators commute with the Hamiltonian under symmetry and therefore their eigenvalues are quantized. This enables a clear identification of nontrivial multipolar states. We calculate the multipole indices in representative models and show their effectiveness as order parameters. Furthermore, we demonstrate a bulk-boundary correspondence: a nonzero index implies the existence of edge/corner states under the point group symmetry.

关键词： Edge states Electric polarization Surface states Symmetry protected topological states Topological insulators Discrete symmetries in condensed matter Projective symmetries Symmetries in condensed matter

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Motion Correction for Cardiac PET via Parametric Image Optical Flow

Motion Correction for Cardiac PET via Parametric Image Optic...

引用

IEEE Symposium on Nuclear Science (NSS/MIC)

作者： S. J. Zou G. Chinn C. S. Levin Electrical Engineering Stanford University Stanford California United States of America Radiology Stanford University Stanford California United States of America Radiology Electrical Engineering Bioengineering Physics Molecular Imaging Program Stanford University Stanford California United States of America

ISBN: (数字)9798350388152

ISBN: (纸本)9798350388169

Motion correction (MC) is crucial in cardiac positron emission tomography (PET) to mitigate artifacts caused by cardiac, respiratory, and body motion. Motion correction not only improves image quality also leads to accurate quantification of cardiac health. In this study, we explore the effectiveness of optical flow based motion correction for gated cardiac PET. We present a novel method of joint estimation and denoising of parametric *** also present preliminary results of parametric image based optical flow MC, a novel MC method. By jointly denoising and estimating parametric images we see a $\lt4 \mathrm{~dB}$ increase in PSNR for Patlak $K$ image compared to no denoising and see at least a 1 dB PSNR gain with our MC method over all noise scenarios.

关键词： Image quality Microwave integrated circuits Semiconductor detectors Noise reduction Noise Estimation Logic gates

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