Dissipative Systems Research Articles

Dissipation-free modes in dissipative systems

The coupling between a system and its environment (or bath) always leads to dissipation. We show, however, that a system composed of two subsystems can have a dissipation-free mode, if the bath is shared between the two subsystems. Reading in reverse, a shared bath does not contribute to the dissipation of all modes. As a key example, we consider a simple model for a two-sublattice antiferromagnet, where the environment is modeled by a bath that is shared between the two sublattice magnetizations. In our model, we find that the Néel order parameter is a dissipation-free mode. For antiferromagnets, our results offer an explanation for why the dissipation rate of the Néel vector is typically much lower than that of the average magnetization. In general, our results suggest a way to reduce dissipation (and decoherence) for some modes in composite systems, which could have experimental and technological applications.

Variable Switching System for Heat Protection and Dissipation of Ultra-LEO Satellites Based on LHP Coupled with TEC

Ultra-low Earth orbit (LEO) satellites are widely used in the military, remote sensing, scientific research, and other fields. The ultra-LEO satellite faces the harsh aerothermal environment, and the complex variable attitude task requires the radiator of the satellite to not only meet the heat dissipation requirements of the load but also to resist aerothermal flux. In this study, the aerothermal flux of 160–110 km was calculated, and the loop heat pipe (LHP) coupled with a thermo-electric cooler (TEC) and multi-layer insulation (MLI) were applied to ultra-LEO satellites to determine the variable switching and fast response of heat dissipation and heat protection. An aerothermal flux simulation test platform was built. After the assessment of the ultra-LEO aerothermal flux test, even when the head temperature was as high as 350 °C and the side radiator temperature was as high as 160 °C, the temperature of the internal heat source could be controlled within 22.5 °C through the efficient work of the thermal variable switch system. The study confirms the accuracy and feasibility of the system, which provides an important reference for the subsequent actual on-orbit mission.

Discovery of dissipative microwave photonic soliton molecules in dual-bandpass optoelectronic oscillator

Optoelectronic oscillators (OEOs), which have attracted extensive studies in the past decades, are high quality-factor optoelectronic feedback loops for generating various ultra-pure microwave signals. In essence, OEOs are also dissipative nonlinear systems with multiple timescale characteristics and abundant nonlinearities, which open the possibilities for exploring localized dissipative solitary waves. In this paper, we demonstrate a new-class temporal dissipative soliton, i.e., dissipative microwave photonic soliton molecule (DMPSM), in a dual-bandpass OEO. Both the numerical simulation and experiment are conducted to reveal the physical mechanism of DMPSM generation and to evaluate the characteristics of the generated DMPSM sequences. Unlike optical soliton molecules in mode-locked lasers, the formation of DMPSMs arises from the combined action of multiple timescale coupling, nonlinear bistability, and time-delayed feedback in the OEO cavity, where the soliton interval and number in a DMPSM can be well-controlled through varying the multiple timescale variables in the OEO cavity, and the repetition frequency of the DMPSMs can be tuned through changing that of the initially injected perturbation signal. Meanwhile, the generated DMPSM sequence performs with high stability and excellent coherence, which shows enormous application potentials in pulse radar detection, dense microwave comb generation, and neuromorphology.

Action principles for dissipative, non-holonomic Newtonian mechanics

A methodology for deriving dual variational principles for the classical Newtonian mechanics of mass points in the presence of applied forces, interaction forces and constraints, all with a general dependence on particle velocities and positions, is presented. Methods for incorporating constraints are critically assessed. General theory, as well as explicitly worked out variational principles for a dissipative system (due to Lorenz) and a system with anholonomic constraints (due to Pars) are demonstrated. Conditions under which a (family of) dual Hamiltonian flow(s), as well as a constant(s) of motion, may be associated with a conservative or dissipative, and possibly constrained, primal system naturally emerge in this work.

Homotopy, symmetry, and non-Hermitian band topology

Non-Hermitian matrices are ubiquitous in the description of nature ranging from classical dissipative systems, including optical, electrical, and mechanical metamaterials, to scattering of waves and open quantum many-body systems. Seminal line-gap and point-gap classifications of non-Hermitian systems using K-theory have deepened the understanding of many physical phenomena. However, ample systems remain beyond this description; reference points and lines do not in general distinguish whether multiple non-Hermitian bands exhibit intriguing exceptional points, spectral braids and crossings. To address this we consider two different notions: non-Hermitian band gaps and separation gaps that crucially encompass a broad class of multi-band scenarios, enabling the description of generic band structures with symmetries. With these concepts, we provide a unified and comprehensive classification of both gapped and nodal systems in the presence of physically relevant parity-time ( PT ) and pseudo-Hermitian symmetries using homotopy theory. This uncovers new stable topology stemming from both eigenvalues and wave functions, and remarkably also implies distinct fragile topological phases. In particular, we reveal different Abelian and non-Abelian phases in PT -symmetric systems, described by frame and braid topology. The corresponding invariants are robust to symmetry-preserving perturbations that do not induce (exceptional) degeneracy, and they also predict the deformation rules of nodal phases. We further demonstrate that spontaneous PT symmetry breaking is captured by Chern–Euler and Chern–Stiefel–Whitney descriptions, a fingerprint of unprecedented non-Hermitian topology previously overlooked. These results open the door for theoretical and experimental exploration of a rich variety of novel topological phenomena in a wide range of physical platforms.

Characterisation of gradient flows for a given functional

Let X be a vector field and Y be a co-vector field on a smooth manifold M. Does there exist a smooth Riemannian metric gαβ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$g_{\\alpha \\beta }$$\\end{document} on M such that Yβ=gαβXα\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$Y_\\beta = g_{\\alpha \\beta } X^\\alpha $$\\end{document}? The main result of this note gives necessary and sufficient conditions for this to be true. As an application of this result we provide a gradient-flow characterisation for dissipative quantum systems. Namely, we show that finite-dimensional ergodic Lindblad equations admit a gradient flow structure for the von Neumann relative entropy if and only if the condition of bkm-detailed balance holds.

Design and research of heat dissipation system of electric vehicle lithium-ion battery pack based on artificial intelligence optimization algorithm

This research focuses on the design of heat dissipation system for lithium-ion battery packs of electric vehicles, and adopts artificial intelligence optimization algorithm to improve the heat dissipation efficiency of the system. By integrating genetic algorithms and particle swarm optimization, the research goal is to optimize key design parameters of the cooling system to improve temperature control and extend battery life. In the process of algorithm implementation, genetic algorithm improves the diversity of population through crossover and mutation operations, thus enhancing the global search ability. Particle swarm optimization (PSO) improves local search accuracy and convergence speed by dynamically adjusting inertia weight and learning factor. The effects of different design schemes on heat dissipation performance were systematically evaluated by using computational fluid dynamics (CFD) software. The experimental results show that the efficiency of the cooling system is significantly improved after the application of the optimization algorithm, especially in the aspects of temperature distribution uniformity and maximum temperature reduction. The optimization algorithm also successfully shortens the thermal response time of the system and improves the adaptability and stability of the system under different working conditions. The computational complexity and execution time of these algorithms are also analyzed, which proves the efficiency and feasibility of these algorithms in practical applications. This study demonstrates the practicability and effectiveness of artificial intelligence optimization algorithm in the design of heat dissipation system of lithium-ion battery pack for electric vehicles, and provides valuable reference and practical guidance for the progress of heat dissipation technology of electric vehicles in the future.

Bath-induced interactions and transient dynamics in open quantum systems at strong coupling: Effective Hamiltonian approach.

Understanding the dynamics of dissipative quantum systems, particularly beyond the weak coupling approximation, is central to various quantum applications. While numerically exact methods provide accurate solutions, they often lack the analytical insight provided by theoretical approaches. In this study, we employ the recently developed method dubbed the effective Hamiltonian theory to understand the dynamics of system-bath configurations without resorting to a perturbative description of the system-bath coupling energy. Through a combination of mapping steps and truncation, the effective Hamiltonian theory offers both analytical insights into signatures of strong couplings in open quantum systems and a straightforward path for numerical simulations. To validate the accuracy of the method, we apply it to two canonical models: a single spin immersed in a bosonic bath and two noninteracting spins in a common bath. In both cases, we study the transient regime and the steady state limit at nonzero temperature and spanning system-bath interactions from the weak to the strong regime. By comparing the results of the effective Hamiltonian theory with numerically exact simulations, we show that although the former overlooks non-Markovian features in the transient equilibration dynamics, it correctly captures non-perturbative bath-generated couplings between otherwise non-interacting spins, as observed in their synchronization dynamics and correlations. Altogether, the effective Hamiltonian theory offers a powerful approach for understanding strong coupling dynamics and thermodynamics, capturing the signatures of such interactions in both relaxation dynamics and in the steady state limit.

Enhancing thermal efficiency of double-pass solar air collectors: A comparative study on the role of V-angled perforated fins

This study investigates the enhancement of thermal efficiency in double-pass solar air collectors (DPSACs) by incorporating V-angled perforated fins. It compares the performance of a finned model (FDPSAC) with a conventional smooth model, aiming to optimize thermal efficiency through improved heat transfer and air distribution. The experiments were conducted under three airflow rates: 0.00864 kg/s (Case I), 0.01143 kg/s (Case II), and 0.01317 kg/s (Case III). The findings indicated that the FDPSAC significantly outperformed the DPSAC, achieving higher outlet temperatures and demonstrating superior heat gain. The daily efficiency for the FDPSAC was 51.6 %, 54.7 %, and 59.2 %, exceeding the DPSAC, which were 49.4 %, 50.5 %, and 53.9 % for cases I, II, and III, respectively. The daily collector efficiency of the FDPSAC improved by approximately 4.45 %, 8.32 %, and 9.83 % relative to the DPSAC for the same case order. The results also showed that the FDPSAC maintained lower temperatures of the absorber plate, suggesting more effective heat dissipation and overall system efficiency. This study highlights the critical role of innovative fin design and optimal airflow management in enhancing solar collector performance. These improvements highlight the potential of the proposed fins to enhance solar air collector efficiency, providing key insights for optimizing thermal systems in sustainable energy.

Imaginary gap-closed points and dynamics in a class of dissipative systems

Imaginary gap-closed points and dynamics in a class of dissipative systems

A Simple Testbed for Stability Analysis of Quantum Dissipative Systems

A Simple Testbed for Stability Analysis of Quantum Dissipative Systems

Spatiotemporal nonlinear dynamics and chaos in a mechanical Duffing-type system

This paper investigates spatiotemporal nonlinear dynamics and chaos in a dissipative mechanical Duffing-type system subjected to external stimulus. A nonlinear wave equation with cubic nonlinearity governs the system dynamics. A perturbation description is employed to build mathematical tools that represent different aspects of system dynamics, from local to global behaviors. Lyapunov exponents are defined from the different perturbations allowing the evaluation of local, convective and mean exponents. Different dynamical regimes are investigated considering homogeneous and heterogeneous spatial stimuli. Distinct dynamical responses are observed including periodic, quasi-periodic and chaotic behaviors. A novel concept of chaotic wave is employed to explain the spatial transport of chaos through the media considering heterogeneous conditions. Chaotic wave velocity is measured by the convective Lyapunov exponents.

Damped rigid substructure system for seismic protection of structures

Building codes commonly accept inelastic deformations that inevitably occur due to seismic excursions in structures. To control the damage, limits on the inelastic deformations have been established. Standard passive energy dissipation systems have been used to reduce the damage, generally with some effectiveness. The damped rigid substructure (DRS) passive damping system, proposed in this article, geometrically amplifies the damper displacements and exerts a re-centering force, leading to effective discharge of the seismic energy to the extent that structural damage can be prevented. This is achieved using common damped and undamped diagonals arranged per implementation and design principles introduced in this article. The DRS system can considerably reduce material consumption and construction costs, leading to more sustainable structures when seismic forces govern the design. It can also benefit from the usage of high-strength materials to enhance its re-centering mechanism. The system is adaptable to the architectural needs and can be used for all categories of importance and height variation, made of steel or concrete.

Exceptional Nexus in Bose-Einstein Condensates with Collective Dissipation.

In multistate non-Hermitian systems, higher-order exceptional points and exotic phenomena with no analogues in two-level systems arise. A paradigm is the exceptional nexus (EX), a third-order EP as the cusp singularity of exceptional arcs (EAs), that has a hybrid topological nature. Using atomic Bose-Einstein condensates to implement a dissipative three-state system, we experimentally realize an EX within a two-parameter space, despite the absence of symmetry. The engineered dissipation exhibits density dependence due to the collective atomic response to resonant light. Based on extensive analysis of the system's decay dynamics, we demonstrate the formation of an EX from the coalescence of two EAs with distinct geometries. These structures arise from the different roles played by dissipation in the strong coupling limit and quantum Zeno regime. Our Letter paves the way for exploring higher-order exceptional physics in the many-body setting of ultracold atoms.

Investigating (2+1)-dimensional dissipative long wave system in water waves using three innovative integration norms

This research article investigates the dissipative long wave system in (2+1) dimensions. To analyze this system, three separate integrating strategies were used: the single manifold approach, the unified method, and the generalized projective Ricatti equation method. Novel soliton solutions were effectively obtained by applying these strategies to the suggested model. The resulting solutions are various, including mixed soliton-like solutions, dark solitons, rational solutions, triangular periodic solutions, and combined Jacobi elliptic wave function solutions. Using the aforementioned approaches, an extensive variety of solution types has been discovered for the proposed model. The dynamic character of these closed-form solutions has been adequately demonstrated using both three dimensional and two dimensional graphical representations. This visualization helps to better understand the behavior of the acquired solutions.

Entangled multiplets, asymmetry, and quantum Mpemba effect in dissipative systems

Recently, the entanglement asymmetry emerged as an informative tool to understand dynamical symmetry restoration in out-of-equilibrium quantum many-body systems after a quantum quench. For integrable systems the asymmetry can be understood in the space-time scaling limit via the quasiparticle picture, as it was pointed out in Ares et al (2023 Nat. Commun. 14 2036) . However, a quasiparticle picture for quantum quenches from generic initial states was still lacking. Here we conjecture a full-fledged quasiparticle picture for the charged moments of the reduced density matrix, which are the main ingredients to construct the asymmetry. Our formula works for quenches producing entangled multiplets of an arbitrary number of excitations. We benchmark our results in the XX spin chain. First, by using an elementary approach based on the multidimensional stationary phase approximation we provide an ab initio rigorous derivation of the dynamics of the charged moments for the quench treated in Ares et al (2023 SciPost Phys. 15 089). Then, we show that the same results can be straightforwardly obtained within our quasiparticle picture. As a byproduct of our analysis, we obtain a general criterion ensuring a vanishing entanglement asymmetry at long times. Next, by using the Lindblad master equation, we study the effect of gain and loss dissipation on the entanglement asymmetry. Specifically, we investigate the fate of the so-called quantum Mpemba effect (QME) in the presence of dissipation. We show that dissipation can induce QME even if unitary dynamics does not show it, and we provide a quasiparticle-based interpretation of the condition for the QME.

Influence of the Machining Process on the Wear Properties of Self-Mated Structural Steel in Dry Sliding Conditions

This work investigates the tribological behavior of a machined S355JR structural steel in dry sliding conditions for the development of an innovative seismic dissipation system. Flat-ended pins and disks were made of the same structural steel to simulate the conformal contact of different device parts. Pins were machined by turning, while disks were milled and turned to obtain a nominal average surface Ra roughness ranging from 0.8 µm to 6.3 µm. The influence of the surface roughness on the coefficient of friction (COF), specific wear rate (SWR), and time to steady-state (TSS) was investigated. Tribological tests were conducted reciprocating motion in dry sliding conditions to simulate the operating conditions of the device, with 1 Hz and 2 Hz reciprocating frequencies and an applied normal load of 50 N. The Rsk and Rku roughness parameters helped to better understand the tribological response of milled and turned disks, having an influence on the TSS and SWR.

Large time asymptotics for partially dissipative hyperbolic systems without Fourier analysis: Application to the nonlinearly damped $p$-system

A new framework to obtain time-decay estimates for partially dissipative hyperbolic systems set on the real line is developed. Under the classical Shizuta–Kawashima (SK) stability condition, equivalent to the Kalman rank condition in control theory, the solutions of these systems decay exponentially in time for high frequencies and polynomially for low ones. This allows us to derive a sharp description of the space-time decay of solutions for large time. However, such analysis relies heavily on the use of the Fourier transform, which we avoid here, developing the “physical space version” of the hyperbolic hypocoercivity approach introduced in Beauchard and Zuazua [Arch. Ration. Mech. Anal. 199 (2011), 177–227], to prove new asymptotic results in the linear and nonlinear settings. The new physical space version of the hyperbolic hypocoercivity approach allows us to recover the natural heat-like time decay of solutions under sharp rank conditions, without employing Fourier analysis or L^{1} assumptions on the initial data. Taking advantage of this Fourier-free framework, we establish new enhanced time-decay estimates for initial data belonging to weighted Sobolev spaces. These results are then applied to the nonlinear compressible Euler equations with linear damping. We also prove the logarithmic stability of the nonlinearly damped p -system.

Bioinspired Heterocoordination in Adaptable Cobalt Metal-Organic Framework for DNA Epigenetic Modification Detection.

Metal-organic frameworks (MOFs) show unique advantages in simulating the dynamics and fidelity of natural coordination. Inspired by zinc finger protein, a second linker was introduced to affect the homogeneous MOF system and thus facilitate the emergence of diverse functionalities. Under the systematic identification of 12 MOF species (i.e., metal ions, linkers) and 6 second linkers (trigger), a dissipative system consisting of Co-BDC-NO2 and o-phenylenediamine (oPD) was screened out, which can rapidly and in situ generate a high photothermal complex (η = 36.9%). Meanwhile, both the carboxylation of epigenetic modifications and metal ion (Fe3+, Ni2+, Cu2+, Zn2+, Co2+ and Mn2+) screening were utilized to improve the local coordination environment so that the adaptable Co-MOF growth on the DNA strand was realized. Thus, epigenetic modification information on DNA was converted to an amplified metal ion signal, and then oPD was further introduced to generate bimodal dissipative signals by which a simple, high-sensitivity detection strategy of 5-hydroxymethylcytosine (LOD = 0.02%) and 5-formylcytosine (LOD = 0.025‰) was developed. The strategy provides one low-cost method (< 0.01 $/sample) for quantifying global epigenetic modifications, which greatly promotes epigenetic modification-based early disease diagnosis. This work also proposes a general heterocoordination design concept for molecular recognition and signal transduction, opening a new MOF-based sensing paradigm.

Quantum Fisher information and entanglement of a dissipative hybrid optomechanical system with multi-photon transition

Quantum Fisher information and entanglement of a dissipative hybrid optomechanical system with multi-photon transition