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Euclidean Contractivity of Neural Networks with Symmetric Weights

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arXiv 2023年

作者： Centorrino, Veronica Gokhale, Anand Davydov, Alexander Russo, Giovanni Bullo, Francesco Scuola Superiore Meridionale University of Naples Federico II Italy Center for Control Dynamical Systems and Computation UC Santa Barbara Santa BarbaraCA93106 United States Department of Information and Electric Engineering and Applied Mathematics University of Salerno Italy

This paper investigates stability conditions of continuous-time Hopfield and firing-rate neural networks by leveraging contraction theory. First, we present a number of useful general algebraic results on matrix polytopes and products of symmetric matrices. Then, we give sufficient conditions for strong and weak Euclidean contractivity, i.e., contractivity with respect to the 2 norm, of both models with symmetric weights and (possibly) non-smooth activation functions. Our contraction analysis leads to contraction rates which are log-optimal in almost all symmetric synaptic matrices. Finally, we use our results to propose a firing-rate neural network model to solve a quadratic optimization problem with box constraints. © 2023, CC BY.

关键词： Matrix algebra

Optimization Strategy of Bio-Inspired Metaheuristic Algorithms Tuned PID controller for PMBDC Actuated Robotic Manipulator 3

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Optimization Strategy of Bio-Inspired Metaheuristic Algorith...

3rd International Conference on Computing and Network Communications, CoCoNet 2019

作者： Valluru, Sudarshan K. Singh, Madhusudan Center for Control of Dynamical Systems and Computation Department of Electrical Engineering Delhi Technological University Delhi110042 India

The present article makes an attempt to evaluate the computational performance of genetic meta heuristic optimized control algorithms. Here, the multi-objective bio inspired algorithm (MOGA) and adaptive particle swarm optimization (APSO) algorithm are used to tune linear PID (L-PID) and nonlinear PID(NL-PID) controllers to implement performance and execution control of permanent magnet brushed DC (PMBDC) motor actuated robotic manipulator. The MOGA, APSO optimised nonlinear and linear PID controllers have been validated for their response efficacy and compared in respect of the steady-state error, overshoot and settling time of PMBDC driven robotic Manipulator. The efficacy of metaheuristics such as APSO and MOGA tuned NL-PID controller are better as compared to the L- PID controlled objects. Experimental results show that the NL-PID controller mends the controlled objects' performace with a reduction in both the overshoot as well as the settling time, if tuned either with MOGA or APSO for L-PID controllers while NL-PID controller tuned with APSO gives satisfactory dynamic response of the system. © 2020 The Authors. Published by Elsevier B.V.

关键词： Permanent magnets

Triplet Excitation-Energy Transfer Couplings from Subsystem Time-Dependent Density-Functional Theory

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arXiv 2023年

作者： Käfer, Sabine Niemeyer, Niklas Tölle, Johannes Neugebauer, Johannes University of Münster Organisch-Chemisches Institut Center for Multiscale Theory and Computation Corrensstrase 36 Münster48149 Germany Division of Chemistry and Chemical Engineering California Institute of Technology PasadenaCA91125 United States

We present an implementation of Triplet Excitation-Energy Transfer (TEET) couplings based on subsystem-based Time-Dependent Density-Functional Theory (sTDDFT). TEET couplings are systematically investigated by comparing "exact" and approximate variants of sTDDFT. We demonstrate that, while sTDDFT utilizing explicit approximate Non-Additive Kinetic Energy (NAKE) density functionals is well-suited for describing Singlet Excitation-Energy Transfer (SEET) processes, it is inadequate for characterizing TEET. However, we show that Projection-based Embedding (PbE)-based sTDDFT addresses the challenges faced by NAKE-sTDDFT and emerges as a promising method for accurately describing electronic couplings in TEET processes. We also introduce the mixed PbE-/NAKE-embedding procedure to investigate TEET effects in solvated pairs of chromophores. This approach offers a good balance between accuracy and efficiency, enabling comprehensive studies of TEET processes in complex environments. Copyright © 2023, The Authors. All rights reserved.

关键词： Kinetic energy

control of Reaction-Diffusion Processes Under Communication Delays

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Control of Reaction-Diffusion Processes Under Communication ...

European control Conference (ECC)

作者： Luca Ballotta Juncal Arbelaiz Vijay Gupta Luca Schenato Mihailo R. Jovanović Delft Center for Systems and Control Delft University of Technology Delft The Netherlands Department of Mechanical and Aerospace Engineering Center for Statistics and Machine Learning Princeton University Princeton NJ USA Elmore Family School of Electrical and Computer Engineering Purdue University West Lafayette IN USA Department of Information Engineering University of Padova Padova Italy Ming Hsieh Department of Electrical and Computer Engineering University of Southern California Los Angeles CA USA

ISBN: (数字)9783907144107

ISBN: (纸本)9798331540920

In this paper we investigate the design of optimal spatially distributed controllers for a linear and spatially invariant reaction-diffusion process over the real line. The controller receives state measurements from different spatial locations with non-negligible delays. In this set-up and for the class of proportional spatially invariant state feedback controllers, the optimal control synthesis problem is equivalent to a feedback gain optimization for a spatially distributed delay system. We show that the spatial locality of optimal feedback gains is affected not only by diffusion and reaction coefficients, but also by the parameter representing communication time-delay that causes a sharp flattening of the control gains. In the expensive control regime, the optimal controller is solved analytically, yielding some practical design guidelines.

关键词： State feedback Delay systems Design methodology Process control Optimal control Europe Delays

Understanding “Just-in-Time” States in Behavioral Interventions using System Identification and Data Science Methods ⁎

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IFAC-PapersOnLine 2024年第15期58卷 568-573页

作者： Mohamed El Mistiri Sarasij Banerjee Daniel E. Rivera Predrag Klasnja Junghwan Park Eric Hekler Control Systems Engineering Lab Arizona State University Tempe AZ 85281 USA Division of Biomedical and Health Informatics School of Information University of Michigan Ann Arbor MI 48109 USA Center for Wireless & Population Health Systems University of California San Diego (UCSD) La Jolla CA 92093 USA

Insufficient physical activity (PA) is highly prevalent in society, despite its negative impact on personal health. Effective interventions are clearly needed. However, improvements to behavioral interventions face many challenges, from noisy and missing measurements to inadequate understanding of the dynamics of behavior change in context. In this paper, we present a comprehensive, data-driven, system identification approach aimed at overcoming challenges to better understand the dynamics of PA behavior change, which in turn can improve the efficacy of these interventions. The proposed approach consists of an innovative input signal design (aimed at providing informative data sets to study the concept of “just-in-time” dynamics), Singular Spectrum Analysis (SSA; for noise reduction and exploring the separability of the measured output signal), and Model-on-Demand (MoD) estimation, a hybrid data-driven modeling approach, which allows identifying dynamics under changing operating conditions. The proposed approach is evaluated on data for a representative participant from the JustWalk JITAI study. The results demonstrate significant potential of the methodology in enhancing the understanding of the dynamics of behavior change in context.

关键词： eHealth nonlinear system identification time series modelling filtering smoothing

Non-Euclidean Monotone Operator Theory with Applications to Recurrent Neural Networks

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arXiv 2022年

作者： Davydov, Alexander Jafarpour, Saber Proskurnikov, Anton V. Bullo, Francesco The Center for Control Dynamical Systems and Computation University of California Santa Barbara93106-5070 United States The School of Electrical and Computer Engineering Georgia Institute of Technology United States The Department of Electronics and Telecommunications Politecnico di Torino Turin Italy

We provide a novel transcription of monotone operator theory to the non-Euclidean finite-dimensional spaces l1 and l∞. We first establish properties of mappings which are monotone with respect to the non-Euclidean norms l1 or l∞. In analogy with their Euclidean counterparts, mappings which are monotone with respect to a non-Euclidean norm are amenable to numerous algorithms for computing their zeros. We demonstrate that several classic iterative methods for computing zeros of monotone operators are directly applicable in the non-Euclidean framework. We present a case-study in the equilibrium computation of recurrent neural networks and demonstrate that casting the computation as a suitable operator splitting problem improves convergence rates. Copyright © 2022, The Authors. All rights reserved.

关键词： Recurrent neural networks

Accelerating Analytic-Continuation GW Calculations with a Laplace Transformation and Natural Auxiliary Functions

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arXiv 2023年

作者： Tölle, Johannes Niemeyer, Niklas Neugebauer, Johannes Division of Chemistry and Chemical Engineering California Institute of Technology PasadenaCA91125 United States University of Münster Organisch-Chemisches Institut Center for Multiscale Theory and Computation Corrensstraße 36 Münster48149 Germany

We present a simple and accurate GW implementation based on a combination of a Laplace transformation (LT) and other acceleration techniques used in post-SCF quantum chemistry, namely, natural auxiliary functions and the frozen-core approximation. The LT-GW approach combines three major benefits: (a) a small prefactor for the computational scaling, (b) easy integration into existing molecular GW implementations, and (c) significant performance improvements for a wide range of possible applications. Illustrating these advantages for systems consisting of up to 352 atoms and 7412 basis functions, we further demonstrate the benefits of this approach combined with an efficient implementation of the Bethe–Salpeter equation. Copyright © 2023, The Authors. All rights reserved.

关键词： Quantum chemistry

SlBEL11 regulates flavonoid biosynthesis,thus fine-tuning auxin efflux to prevent premature fruit drop in tomato

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Journal of Integrative Plant Biology 2024年第4期66卷 749-770页

作者： Xiufen Dong Xianfeng Liu Lina Cheng Ruizhen Li Siqi Ge Sai Wang Yue Cai Yang Liu Sida Meng Cai-Zhong Jiang Chun-Lin Shi Tianlai Li Daqi Fu Mingfang Qi Tao Xu College of Horticulture Shenyang Agricultural UniversityShenyang 110866China Collaborative Innovation Center for Efficient and Green Production of Agriculture in Mountainous Areas of Zhejiang Province College of Horticulture ScienceZhejiang A&F UniversityHangzhou 311300China Key Laboratory for Quality and Safety Control of Subtropical Fruits and Vegetables Collaborative Innovation Center for Efficient and Green Production of Agriculture in Mountainous Areas of Zhejiang ProvinceMinistry of Agriculture and Rural AffairsCollege of Horticulture ScienceZhejiang A&F UniversityHangzhou 311300China Key Laboratory of Protected Horticulture of Ministry of Education Shenyang 110866China Crops Pathology and Genetic Research Unit United States Department of Agriculture Agricultural Research ServiceWashingtonDC 20250USA Department of Plant Sciences University of CaliforniaDavisCA 95616USA ANGENOVO Oslo 0753Norway Laboratory of Fruit Biology College of Food Science and Nutritional EngineeringChina Agricultural UniversityBeijing 100083China

Auxin regulates flower and fruit abscission,but how developmental signals mediate auxin transport in abscission remains ***,we reveal the role of the transcription factor BEL1-LIKE HOMEODOMAIN11(SlBEL11)in regulating auxin transport during abscission in tomato(Solanum lycopersicum).SlBEL11 is highly expressed in the fruit abscission zone,and its expression increases during fruit *** of SlBEL11 expression by RNA interference(RNAi)caused premature fruit drop at the breaker(Br)and 3d post-breaker(Br+3)stages of fruit *** and metabolome analysis of SlBEL11-RNAi lines revealed impaired flavonoid biosynthesis and decreased levels of most flavonoids,especially quercetin,which functions as an auxin transport *** suggested that SlBEL11 prevents premature fruit abscission by modulating auxin efflux from fruits,which is crucial for the formation of an auxin response ***,quercetin treatment suppressed premature fruit drop in SlBEL11-RNAi *** affinity purification sequencing(DAP-seq)analysis indicated that SlBEL11 induced expression of the transcription factor gene SlMYB111 by directly binding to its *** immunoprecipitation-quantitative polymerase chain reaction and electrophoretic mobility shift assay showed that *** MYELOBLASTOSIS VIRAL ONCOGENE HOMOLOG111(SlMYB111)induces the expression of the core flavonoid biosynthesis genes SlCHS1,SlCHI,SlF3H,and SlFLS by directly binding to their *** findings suggest that the SlBEL11-SlMYB111 module modulates flavonoid biosynthesis to fine-tune auxin efflux from fruits and thus maintain an auxin response gradient in the pedicel,thereby preventing premature fruit drop.

关键词： abscission auxin flavonoid SlBEL11 tomato

ONLINE FEEDBACK OPTIMIZATION AND SINGULAR PERTURBATION VIA CONTRACTION THEORY∗

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arXiv 2023年

作者： Cothren, Liliaokeawawa Bullo, Francesco Dall’Anese, Emiliano Department of Electrical Computer and Energy Engineering University of Colorado Boulder BoulderCO United States Center for Control Dynamical Systems and Computation UC Santa Barbara Santa BarbaraCA93101 United States Department of Electrical and Computer Engineering Boston University BostonMA02215 United States

In this paper, we provide a novel contraction-theoretic approach to analyze two-time scale systems, including those commonly encountered in Online Feedback Optimization (OFO). Our framework endows these systems with several robustness properties, enabling a more comprehensive characterization of their behaviors. The primary assumptions are the contractivity of the fast subsystem and the reduced model, along with an explicit upper bound on the time-scale parameter. For two-time scale systems subject to disturbances, we show that the distance between solutions of the nominal system and solutions of its reduced model is uniformly upper bounded by a function of contraction rates, Lipschitz constants, the time-scale parameter, and the variability of the disturbances over time. Applying these general results to the OFO context, we establish new individual tracking error bounds, showing that solutions converge to their time-varying optimizer, provided the plant and steady-state feedback controller exhibit contractivity and the controller gain is suitably bounded. Finally, we explore two special cases: for autonomous nonlinear systems, we derive sharper bounds than those in the general results, and for linear time-invariant systems, we present novel bounds based on induced matrix norms and induced matrix log norms. Copyright © 2023, The Authors. All rights reserved.

关键词： State feedback