Relevant bibliographies by topics / Timescale separation system dynamics

Academic literature on the topic 'Timescale separation system dynamics'

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Published: 6 September 2023

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Journal articles on the topic "Timescale separation system dynamics"

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Williamson, Mark S., Sebastian Bathiany, and Timothy M. Lenton. "Early warning signals of tipping points in periodically forced systems." Earth System Dynamics 7, no. 2 (April 13, 2016): 313–26. http://dx.doi.org/10.5194/esd-7-313-2016.

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Abstract. The prospect of finding generic early warning signals of an approaching tipping point in a complex system has generated much interest recently. Existing methods are predicated on a separation of timescales between the system studied and its forcing. However, many systems, including several candidate tipping elements in the climate system, are forced periodically at a timescale comparable to their internal dynamics. Here we use alternative early warning signals of tipping points due to local bifurcations in systems subjected to periodic forcing whose timescale is similar to the period of the forcing. These systems are not in, or close to, a fixed point. Instead their steady state is described by a periodic attractor. For these systems, phase lag and amplification of the system response can provide early warning signals, based on a linear dynamics approximation. Furthermore, the Fourier spectrum of the system's time series reveals harmonics of the forcing period in the system response whose amplitude is related to how nonlinear the system's response is becoming with nonlinear effects becoming more prominent closer to a bifurcation. We apply these indicators as well as a return map analysis to a simple conceptual system and satellite observations of Arctic sea ice area, the latter conjectured to have a bifurcation type tipping point. We find no detectable signal of the Arctic sea ice approaching a local bifurcation.
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Wu, Weijun, Andrew E. Sifain, Courtney A. Delpo, and Gregory D. Scholes. "Polariton enhanced free charge carrier generation in donor–acceptor cavity systems by a second-hybridization mechanism." Journal of Chemical Physics 157, no. 16 (October 28, 2022): 161102. http://dx.doi.org/10.1063/5.0122497.

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Cavity quantum electrodynamics has been studied as a potential approach to modify free charge carrier generation in donor–acceptor heterojunctions because of the delocalization and controllable energy level properties of hybridized light–matter states known as polaritons. However, in many experimental systems, cavity coupling decreases charge separation. Here, we theoretically study the quantum dynamics of a coherent and dissipative donor–acceptor cavity system, to investigate the dynamical mechanism and further discover the conditions under which polaritons may enhance free charge carrier generation. We use open quantum system methods based on single-pulse pumping to find that polaritons have the potential to connect excitonic states and charge separated states, further enhancing free charge generation on an ultrafast timescale of several hundred femtoseconds. The mechanism involves polaritons with optimal energy levels that allow the exciton to overcome the high Coulomb barrier induced by electron–hole attraction. Moreover, we propose that a second-hybridization between a polariton state and dark states with similar energy enables the formation of the hybrid charge separated states that are optically active. These two mechanisms lead to a maximum of 50% enhancement of free charge carrier generation on a short timescale. However, our simulation reveals that on the longer timescale of picoseconds, internal conversion and cavity loss dominate and suppress free charge carrier generation, reproducing the experimental results. Thus, our work shows that polaritons can affect the charge separation mechanism and promote free charge carrier generation efficiency, but predominantly on a short timescale after photoexcitation.
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Webber, S., and M. R. Jeffrey. "Loss of Determinacy at Small Scales, with Application to Multiple Timescale and Nonsmooth Dynamics." International Journal of Bifurcation and Chaos 31, no. 03 (March 15, 2021): 2150041. http://dx.doi.org/10.1142/s0218127421500413.

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A singularity is described that creates a forward time loss of determinacy in a two-timescale system, in the limit where the timescale separation is large. We describe how the situation can arise in a dynamical system of two fast variables and three slow variables or parameters, with weakly coupling between the fast variables. A wide set of initial conditions enters the [Formula: see text]-neighborhood of the singularity, and explodes back out of it to fill a large region of phase space, all in finite time. The scenario has particular significance in the application to piecewise-smooth systems, where it arises in the blow up of dynamics at a discontinuity and is followed by abrupt recollapse of solutions to “hide” the loss of determinacy, and yet leave behind a remnant of it in the global dynamics. This constitutes a generalization of a “micro-slip” phenomenon found recently in spring-coupled blocks, whereby coupled oscillators undergo unpredictable stick-slip-stick sequences instigated by a higher codimension form of the singularity. The indeterminacy is localized to brief slips events, but remains evident in the indeterminate sequencing of near-simultaneous slips of multiple blocks.
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Costa, Antonio C., Tosif Ahamed, David Jordan, and Greg J. Stephens. "Maximally predictive states: From partial observations to long timescales." Chaos: An Interdisciplinary Journal of Nonlinear Science 33, no. 2 (February 2023): 023136. http://dx.doi.org/10.1063/5.0129398.

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Isolating slower dynamics from fast fluctuations has proven remarkably powerful, but how do we proceed from partial observations of dynamical systems for which we lack underlying equations? Here, we construct maximally predictive states by concatenating measurements in time, partitioning the resulting sequences using maximum entropy, and choosing the sequence length to maximize short-time predictive information. Transitions between these states yield a simple approximation of the transfer operator, which we use to reveal timescale separation and long-lived collective modes through the operator spectrum. Applicable to both deterministic and stochastic processes, we illustrate our approach through partial observations of the Lorenz system and the stochastic dynamics of a particle in a double-well potential. We use our transfer operator approach to provide a new estimator of the Kolmogorov–Sinai entropy, which we demonstrate in discrete and continuous-time systems, as well as the movement behavior of the nematode worm C. elegans.
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Williamson, M. S., S. Bathiany, and T. M. Lenton. "Early warning signals of tipping points in periodically forced systems." Earth System Dynamics Discussions 6, no. 2 (November 6, 2015): 2243–72. http://dx.doi.org/10.5194/esdd-6-2243-2015.

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Abstract. The prospect of finding generic early warning signals of an approaching tipping point in a complex system has generated much recent interest. Existing methods are predicated on a separation of timescales between the system studied and its forcing. However, many systems, including several candidate tipping elements in the climate system, are forced periodically at a timescale comparable to their internal dynamics. Here we find alternative early warning signals of tipping points due to local bifurcations in systems subjected to periodic forcing whose time scale is similar to the period of the forcing. These systems are not in, or close to, a fixed point. Instead their steady state is described by a periodic attractor. We show that the phase lag and amplification of the system response provide early warning signals, based on a linear dynamics approximation. Furthermore, the power spectrum of the system's time series reveals the generation of harmonics of the forcing period, the size of which are proportional to how nonlinear the system's response is becoming with nonlinear effects becoming more prominent closer to a bifurcation. We apply these indicators to a simple conceptual system and satellite observations of Arctic sea ice area, the latter conjectured to have a bifurcation type tipping point. We find no detectable signal of the Arctic sea ice approaching a local bifurcation.
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Ha, Sang Wook, and Bong Seok Park. "Disturbance Observer-Based Control for Trajectory Tracking of a Quadrotor." Electronics 9, no. 10 (October 2, 2020): 1624. http://dx.doi.org/10.3390/electronics9101624.

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This paper presents a new control approach for the trajectory tracking of a quadrotor in the presence of external disturbances. Unlike in previous studies using hierarchical control strategies, a nonlinear controller is designed by introducing new state transformations that can use Euler angles as virtual control inputs. Thus, the proposed method can eliminate the timescale separation assumption of hierarchical control strategies. To estimate the external disturbances involved in the translational and rotational dynamics of the quadrotor, disturbance observers are developed. Using state transformations and estimates of external disturbances, we design a robust nonlinear controller based on the dynamic surface control method. The stability of the closed-loop system is analyzed without separation into two subsystems. From the Lyapunov stability theory, it is proven that all error signals in the closed-loop system are uniformly ultimately bounded and can be made arbitrarily small. Finally, simulation results are presented to demonstrate the performance of the proposed controller.
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Benavides, Santiago J., Keaton J. Burns, Basile Gallet, and Glenn R. Flierl. "Effective Drag in Rotating, Poorly Conducting Plasma Turbulence." Astrophysical Journal 938, no. 2 (October 1, 2022): 92. http://dx.doi.org/10.3847/1538-4357/ac9137.

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Abstract Despite the increasing sophistication of numerical models of hot Jupiter atmospheres, the large timescale separation required in simulating the wide range in electrical conductivity between the dayside and nightside has made it difficult to run fully consistent magnetohydrodynamic (MHD) models. This has led to many studies that resort to drag parameterizations of MHD. In this study, we revisit the question of the Lorentz force as an effective drag by running a series of direct numerical simulations of a weakly rotating, poorly conducting flow in the presence of a misaligned, strong background magnetic field. We find that the drag parameterization fails once the timescale associated with the Lorentz force becomes shorter than the dynamical timescale in the system, beyond which the effective drag coefficient remains roughly constant, despite orders-of-magnitude variation in the Lorentz (magnetic) timescale. We offer an improvement to the drag parameterization by considering the relevant asymptotic limit of low conductivity and strong background magnetic field, known as the quasi-static MHD approximation of the Lorentz force. This approximation removes the fast timescale associated with magnetic diffusion, but retains a more complex version of the Lorentz force, which could be utilized in future numerical models of hot Jupiter atmospheric circulation.
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Lee, Ka Kit, Darren Yi Sern Low, Mei Ling Foo, Lih Jiun Yu, Thomas Shean Yaw Choong, Siah Ying Tang, and Khang Wei Tan. "Molecular Dynamics Simulation of Nanocellulose-Stabilized Pickering Emulsions." Polymers 13, no. 4 (February 23, 2021): 668. http://dx.doi.org/10.3390/polym13040668.

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While the economy is rapidly expanding in most emerging countries, issues coupled with a higher population has created foreseeable tension among food, water, and energy. It is crucial for more sustainable valorization of resources, for instance, nanocellulose, to address the core challenges in environmental sustainability. As the complexity of the system evolved, the timescale of project development has increased exponentially. However, research on the design and operation of integrated nanomaterials, along with energy supply, monitoring, and control infrastructure, has seriously lagged. The development cost of new materials can be significantly reduced by utilizing molecular simulation technology in the design of nanostructured materials. To realize its potential, nanocellulose, an amphiphilic biopolymer with the presence of rich -OH and -CH structural groups, was investigated via molecular dynamics simulation to reveal its full potential as Pickering emulsion stabilizer at the molecular level. This work has successfully quantified the Pickering stabilization mechanism profiles by nanocellulose, and the phenomenon could be visualized in three stages, namely the initial homogenous phase, rapid formation of micelles and coalescence, and lastly the thermodynamic equilibrium of the system. It was also observed that the high bead order was always coupled with a high volume of phase separation activities, through a coarse-grained model within 20,000 time steps. The outcome of this work would be helpful to provide an important perspective for the future design and development of nanocellulose-based emulsion products, which cater for food, cosmeceutical, and pharmaceutical industries.
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Wouters, Jeroen, Stamen Iankov Dolaptchiev, Valerio Lucarini, and Ulrich Achatz. "Parameterization of stochastic multiscale triads." Nonlinear Processes in Geophysics 23, no. 6 (November 28, 2016): 435–45. http://dx.doi.org/10.5194/npg-23-435-2016.

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Abstract. We discuss applications of a recently developed method for model reduction based on linear response theory of weakly coupled dynamical systems. We apply the weak coupling method to simple stochastic differential equations with slow and fast degrees of freedom. The weak coupling model reduction method results in general in a non-Markovian system; we therefore discuss the Markovianization of the system to allow for straightforward numerical integration. We compare the applied method to the equations obtained through homogenization in the limit of large timescale separation between slow and fast degrees of freedom. We numerically compare the ensemble spread from a fixed initial condition, correlation functions and exit times from a domain. The weak coupling method gives more accurate results in all test cases, albeit with a higher numerical cost.
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Paddon-Row, Michael N. "Superexchange-Mediated Charge Separation and Charge Recombination in Covalently Linked Donor - Bridge - Acceptor Systems." Australian Journal of Chemistry 56, no. 8 (2003): 729. http://dx.doi.org/10.1071/ch02249.

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Evidence is presented in support of the concept that electron transfer (ET) between a pair of chromophores may take place efficiently over large distances (>10 Å) by the mediation of an intervening saturated hydrocarbon medium. For example, ET is found to take place on a sub-nanosecond timescale through saturated norbornylogous bridges greater than 13 Å in length, by a superexchange (through-bond coupling) mechanism. The dependence of the ET dynamics on the bridge length and configuration are consistent with the operation of a superexchange mechanism. The distinction between molecular wire behaviour and superexchange-mediated ET is made. The distance dependence of ET dynamics through different types of bridges—saturated and unsaturated hydrocarbon bridges, proteins, and duplex DNA—is discussed and explained. Strategies for prolonging the lifetimes of charge-separated states are explored and discussed. In general, long-lived charge-separated species have been generated using giant multichromophoric systems in which the charges are separated by large distances, often exceeding 20 Å. In contrast, it is shown that very long-lived charge-separated states, possessing the triplet multiplicity, may be generated using short ‘dwarf’ dyads, in which the charges are less than 6 Å apart. Charge recombination in these species is slowed by the difference in electron spin multiplicity between the charge-separated state and the ground state.
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Dissertations / Theses on the topic "Timescale separation system dynamics"

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Constable, George William Albert. "Fast timescales in stochastic population dynamics." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/fast-timescales-in-stochastic-population-dynamics(2e9cace8-e615-44ec-818e-26b96aaa6459).html.

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In this thesis, I present two methods of fast variable elimination in stochastic systems. Their application to models of population dynamics from ecology, epidemiology and population genetics, is explored. In each application, care is taken to develop the models at the microscale, in terms of interactions between individuals. Such an approach leads to well-defined stochastic systems for finite population sizes. These systems are then approximated at the mesoscale, and expressed as stochastic differential equations. It is in this setting the elimination techniques are developed. In each model a deterministically stable state is assumed to exist, about which the system is linearised. The eigenvalues of the system's Jacobian are used to identify the existence of a separation of timescales. The fast and slow directions are then given locally by the associated eigenvectors. These are used as approximations for the fast and slow directions in the full non-linear system. The general aim is then to remove these fast degrees of freedom and thus arrive at an approximate, reduced-variable description of the dynamics on a slow subspace of the full system. In the first of the methods introduced, the conditioning method, the noise of the system is constrained so that it cannot leave the slow subspace. The technique is applied to an ecological model and a susceptible-exposed-infectious-recovered epidemiological model, in both instances providing a reduced system which preserves the behaviour of the full model to high precision. The second method is referred to as the projection matrix method. It isolates the components of the noise on the slow subspace to provide its reduced description. The method is applied to a generalised Moran model of population genetics on islands, between which there is migration. The model is successfully reduced from a system in as many variables as there are islands, to an effective description in a single variable. The same methodology is later applied to the Lotka-Volterra competition model, which is found under certain conditions to behave as a Moran model. In both cases the agreement between the reduced system and stochastic simulations of the full model is excellent. It is stressed that the ideas behind both the conditioning and projection matrix methods are simple, their application systematic, and the results in very good agreement with simulations for a range of parameter values. When the methods are compared however, the projection matrix method is found in general to provide better results.
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Xie, Yinghong. "MD simulations of bio-nano-system : controllable translocation and selective separation of single-stranded DNAs through a polarized CNT membrane /." Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/HKUTO/record/B39559026.

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謝迎洪 and Yinghong Xie. "MD simulations of bio-nano-system: controllable translocation and selective separation of single-stranded DNAs through a polarized CNT membrane." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B39559026.

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"Autonomous agent-based systems and their applications in fluid dynamics, particle separation, and co-evolving networks." Thesis, 2010. http://library.cuhk.edu.hk/record=b6074994.

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Part I deals with the simulation of fluid dynamics using the lattice-Boltzmann method. Microfluidic devices often feature two-dimensional, repetitive arrays. Flows through such devices are pressure-driven and confined by solid walls. We have defined new adaptive generalised periodic boundary conditions to represent the effects of outer solid walls, and are thus able to exploit the periodicity of the array by simulating the flow through one unit cell in lieu of the entire device. The so-calculated fully developed flow describes the flow through the entire array accurately, but with computational requirements that are reduced according to the dimensions of the array.
Part II discusses the problem of separating macromolecules like proteins or DNA coils. The reliable separation of such molecules is a crucial task in molecular biology. The use of Brownian ratchets as mechanisms for the separation of such particles has been proposed and discussed during the last decade. Pressure-driven flows have so far been dismissed as possible driving forces for Brownian ratchets, as they do not generate ratchet asymmetry. We propose a microfluidic design that uses pressure-driven flows to create asymmetry and hence allows particle separation. The dependence of the asymmetry on various factors of the microfluidic geometry is discussed. We further exemplify the feasibility of our approach using Brownian dynamics simulations of particles of different sizes in such a device. The results show that ratchet-based particle separation using flows as the driving force is possible. Simulation results and ratchet theory predictions are in excellent agreement.
Part III deals with the co-evolution of networks and dynamic models. A group of agents occupies the nodes of a network, which defines the relationship between these agents. The evolution of the agents is defined by the rules of the dynamic model and depends on the relationship between agents, i.e., the state of the network. In return, the evolution of the network depends on the state of the dynamic model. The concept is introduced through the adaptive SIS model. We show that the previously used criterion determining the critical infected fraction, i.e., the number of infected agents required to sustain the epidemic, is inappropriate for this model. We introduce a different criterion and show that the critical infected fraction so determined is in good agreement with results obtained by numerical simulations.
This thesis comprises three parts, reporting research results in Fluid Dynamics (Part I), Particle Separation (Part II) and Co-evolving Networks (Part III).
We further discuss the concept of co-evolving dynamics using the Snowdrift Game as a model paradigm. Co-evolution occurs through agents cutting dissatisfied links and rewiring to other agents at random. The effect of co-evolution on the emergence of cooperation is discussed using a mean-field theory and numerical simulations. A transition between a connected and a disconnected, highly cooperative state of the system is observed, and explained using the mean-field model. Quantitative deviations regarding the level of cooperation in the disconnected regime can be fully resolved through an improved mean-field theory that includes the effect of random fluctuations into its model.
Graeser, Oliver = 自主個體為本系統與在流體力學、分子分離、共同演化網絡上的應用 / 顧皓森.
Adviser: Hui Pak-Ming.
Source: Dissertation Abstracts International, Volume: 73-01, Section: B, page: .
Thesis (Ph.D.)--Chinese University of Hong Kong, 2010.
Includes bibliographical references (leaves 204-216).
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Abstract also in Chinese.
Graeser, Oliver = Zi zhu ge ti wei ben xi tong yu zai liu ti li xue, fen zi fen li, gong tong yan hua wang luo shang de ying yong / Gu Haosen.
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Abbas-Pour, Nima. "A Numerical Model for Oil/water Separation from an Accelerating Oil-coated Solid Particle." Thesis, 2013. http://hdl.handle.net/1807/42657.

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A computational fluid dynamics model has been developed to examine the separation of an oil film from a spherical oil-coated particle falling through quiescent water due to gravity. Using this model, the separation process was studied as a function of the viscosity ratio of oil to water, R, and the ratio of viscous forces to surface tension, represented by the Capillary number Ca. The governing equations of this flow-induced motion are derived in a non-inertial spherical coordinate system, and discretized using a finite volume approach. The Volume-of-Fluid method is used to capture the oil/water interface. The model predicts two mechanisms for oil separation: at R less than 1, the shear difference between the particle/oil interface and the oil/water interface is not significant and Ca determines whether separation occurs or not; at R larger than 1, the shear difference is considerable, and the Ca effect becomes less dominant.
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Book chapters on the topic "Timescale separation system dynamics"

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Cui, E. J., X. T. Yu, and F. Li. "Unsteady Flow Characteristic and Separation Control of Lifting System Under High Angle of Attack." In Fluid Dynamics of High Angle of Attack, 253–64. Berlin, Heidelberg: Springer Berlin Heidelberg, 1993. http://dx.doi.org/10.1007/978-3-642-52460-8_17.

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Chow, Joe H. "Time-Scale Separation in Power System Swing Dynamics: Singular Perturbations and Coherency." In Encyclopedia of Systems and Control, 1465–69. London: Springer London, 2015. http://dx.doi.org/10.1007/978-1-4471-5058-9_261.

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Chow, Joe H. "Time-Scale Separation in Power System Swing Dynamics: Singular Perturbations and Coherency." In Encyclopedia of Systems and Control, 1–6. London: Springer London, 2014. http://dx.doi.org/10.1007/978-1-4471-5102-9_261-1.

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Chow, Joe H. "Time-Scale Separation in Power System Swing Dynamics: Singular Perturbations and Coherency." In Encyclopedia of Systems and Control, 2325–29. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-44184-5_261.

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Cina, Jeffrey A. "Transient-absorption reprise: Taking advantage of vibrational adiabaticity." In Getting Started on Time-Resolved Molecular Spectroscopy, 53–60. Oxford University Press, 2022. http://dx.doi.org/10.1093/oso/9780199590315.003.0005.

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This chapter revisits the quantum mechanical description of transient absorption, taking account of the additional insight that is possible in systems with a timescale separation among nuclear degrees of freedom that enables a vibrationally adiabatic treatment. Illustrative calculations are performed on the same conformational/vibrational system considered in the FSRS chapter. While evidence of interaction between slow and fast modes of motion can be discerned in the transient-absorption spectrum, it is shown to be subtler and less vividly informative than the fissors signal.
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HASEBE, Shinji, Taketoshi KUROOKA, and Iori HASHIMOTO. "COMPARISON OF THE SEPARATION PERFORMANCES OF A MULTI-EFFECT BATCH DISTILLATION SYSTEM AND A CONTINUOUS DISTILLATION SYSTEM." In Dynamics and Control of Chemical Reactors, Distillation Columns and Batch Processes (Dycord'95), 249–54. Elsevier, 1995. http://dx.doi.org/10.1016/b978-0-08-042368-5.50043-5.

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Borom, Marcus P. "Role of Earth-Moon rotational dynamics in the shaping of the surface of our planet." In In the Footsteps of Warren B. Hamilton: New Ideas in Earth Science. Geological Society of America, 2022. http://dx.doi.org/10.1130/2021.2553(22).

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ABSTRACT The age of the Moon (1.55–1.78 b.y. old) as calculated from its regression as a function of geological time is much younger than the currently accepted age (ca. 4.52 Ga) determined by radiometric dating of lunar samples collected by Apollo astronauts. This discrepancy has posed a serious challenge for planetary scientists to account satisfactorily for the formation and subsequent breakup of Pangea. Conventional orbital models of the Earth-Moon system cannot explain why Pangea formed on only one hemisphere of Earth, whereas this study’s proposed two-stage rotation model can provide a plausible explanation. Calculations and a plot of the Earth-Moon separation distance against geologic age suggest that, during their first ~3.0 b.y., Earth and the Moon were mutually tidally locked, rotating as an integrated unit about a barycenter (designated as stage I rotation). Beginning 1.55 Ga, however, Earth disengaged from its tidal lock with the Moon and entered its current orbital mode (designated as stage II rotation). The dynamics associated with the two rotational modes of the Earth-Moon system throughout Earth’s history are hypothesized to constitute the driving forces for the migration and coalescence of landmasses during stage I rotation to create Pangea, and its ultimate breakup and drifting during stage II rotation.
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Karthigaiselvan, K., and Rames Chandra Panda. "Implementation of MPC Strategy in Reactive Separation Techniques and Its Benefits: A Demonstration with Natural Gas Sweetening Process." In Model Predictive Control - Theory and Applications [Working Title]. IntechOpen, 2023. http://dx.doi.org/10.5772/intechopen.1001101.

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Model Predictive Control (MPC) is a widely used method that has numerous applications in process industries. In the MPC group of controllers, a clear model is used directly for predicting future plant behavior and calculating corrective control action required to maintain the output at the desired set point value. It is well known that most chemical processes present inherent nonlinearities on account of disturbance, set-point changes.MPC variants based on nonlinear process models have produced stiff control of process along with improved handling of constraints, abnormal dynamics and time delays. One of the variants EMPC applied for various chemical processes have produced economic performance index over the horizon for achieving optimal output targets. In addition to that, adaptive MPC is better in handling the nonlinearity and time varying characteristics during run time by modifying model. The control of reactive separation process is difficult on account of process nonlinearity and interactions of vapor-liquid equilibrium with chemical reactions. Reactive separation is multi -input and multi-output(MIMO) system .In order to obtain the optimal performance, energy conservation and cost effectiveness of MIMO system , the application of optimal controller is inevitable. The application of optimal controller have exhibited better performance compared to tuned linear controller inspite of presence of unknown input delays. The mpc coupled with neural network have exhibited better controllability in case of reactive distillation process. This chapter will cover recent developments in MPC applicable to reactive separation techniques that consist of reactive distillation, reactive absorption, extractive reaction, reactive membrane separation which are used in applications such as LPG processing, natural gas sweetening process etc
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Douglas, Heather. "Conclusion." In Women, Intimate Partner Violence, and the Law, 249–58. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780190071783.003.0010.

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This final chapter affirms the importance of listening to women’s experiences when considering how legal responses to intimate partner violence might be improved to make women safe. The chapter reviews key themes identified in the book, including abusers’ use of the legal system to continue abuse and the role of child protection workers, police, lawyers, and judges in facilitating that abuse. It highlights a common and continuing failure of those who work in the legal system to recognize the significance of nonphysical abuse, to persistently misunderstand the dynamics of separation and ultimately, to fail to prioritize safety. This chapter makes recommendations for law and policy reform toward making the legal system safer.
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Tinker, Peter B., and Peter Nye. "Microbiological Modification of the Rhizosphere." In Solute Movement in the Rhizosphere. Oxford University Press, 2000. http://dx.doi.org/10.1093/oso/9780195124927.003.0012.

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The general questions of root/shoot ratio, allocation of carbon to the root system, and root system dynamics are discussed in chapter 9, and the detailed root structure in chapter 5. Root-derived carbon forms the substrate for rhizosphere and symbiotic organisms, and hence leads to the increase in their population densities close to or in the root. Some of the carbon compounds from the root have specific chemical effects also (see chapter 7). Both quantity and composition of these materials need to be known if their effects are to be understood, and we discuss this subject here. The terminology of these materials is rather confused. The collective name for the injection of plant-derived carbon into the soil around living roots is ‘rhizodeposition’, but this has been used in different ways; for example, it may include root-respired carbon dioxide (Whipps 1990), but Darrah (1996) excludes carbon dioxide. The various forms include (Rovira et al. 1979; Lambers 1987; Whipps 1990) solid tissues lost from the root during growth; mucigel and debris from root surfaces and root cap; low-molecular-weight organic compounds in solution; carbon dioxide produced by root respiration for maintenance and for growth; faunal grazing of root tissues; and carbon transferred into symbionts, such as mycorrhizas and rhizobia. Some authors subdivide certain of these classes further. ‘Rhizodeposition’ is loss from a functioning root, but over a longer period the death and decomposition of whole roots deposits large quantities of carbon into the soil, which continues to act as a more resistant microbial substrate (see chapter 9). All of these materials ultimately are converted to carbon dioxide (except for material formed into stable soil organic matter) and this is difficult to separate from carbon dioxide produced directly by root respiration. The main issue here is how the various forms of deposition alter the ability of the living root system to absorb nutrients. We use the following terms for clarity, and because they relate to the practical means whereby these materials are quantified. As the rhizosphere situation is very dynamic, the results obtained will depend upon the timescale considered. (a) Exudates: soluble low-molecular-weight material that comes directly from the living root (microbial metabolites may be similar, but are excluded).
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Conference papers on the topic "Timescale separation system dynamics"

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Koeln, Justin P., Matthew A. Williams, and Andrew G. Alleyne. "Hierarchical Control of Multi-Domain Power Flow in Mobile Systems: Part I — Framework Development and Demonstration." In ASME 2015 Dynamic Systems and Control Conference. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/dscc2015-9908.

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This two-part paper presents the development of a hierarchical control framework for the control of power flow throughout mobile systems. These vehicles are comprised of multiple interconnected systems each with multiple subsystems which exhibit dynamics over a wide range of timescales. These interconnections and the timescale separation pose a significant challenge when developing an effective control strategy. Part I presents the proposed graph-based modeling approach and the three-level hierarchical control framework developed to directly address these interconnections and timescale separation. The mobile system is represented as a directed graph with vertices corresponding to the states of the vehicle and edges capturing the power flow throughout the vehicle. The mobile system and the corresponding graph are partitioned spatially into systems and subsystems and temporally into vertices of slow, medium, and fast dynamics. The partitioning facilitates the development of models used by model predictive controllers at each level of the hierarchy. A simple example system is used to demonstrate the approach. Part II utilizes this framework to control the power flow in the electrical and thermal systems of an aircraft. Simulation results show the benefits of hierarchical control compared to centralized and decentralized control methods.
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Proutiere, Alexandre, Yung Yi, Tian Lan, and Mung Chiang. "Resource Allocation over Network Dynamics without Timescale Separation." In IEEE INFOCOM 2010 - IEEE Conference on Computer Communications. IEEE, 2010. http://dx.doi.org/10.1109/infcom.2010.5462201.

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Scherer, P. O. J. "Noise induced intramolecular electron transfer processes in polar media." In International Conference on Ultrafast Phenomena. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/up.1992.fc4.

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In two recent papers the photoinduced electron transfer process within a porphyrin quinon cyclophane complex has been studied experimentally /1/ and theoretically /2/ as a model system for the photosynthetic reaction center. The observed rate of the charge separation process depends strongly on the solvent polarity. This dependence could be described analytically using macroscopic models for the dielectric behavior of the solvent. In general, however, such systems may show nonexponential behavior /3/ and the solvent dynamics has to be considered explicitly in a microscopic model. This is the aim of the present paper. We present a microscopic model for the solvent induced transition from the optically excited state (P*) to the charge separated state (CT). Due to its large permanent dipole moment the CT state energy fluctuates strongly in a polar environment. These fluctuations are modeled by a dichotomic process. The energy difference Δ=E(CT)-E(P*) is described as a random telegraph signal which switches between two values Δ+>0 and Δ−<0 . This process is characterized by its correlation time and the probability of finding Δ<0. As long as Δ<0 the transition P* −> CT takes place whereas in the opposite case Δ>0 the CT state may either decay into the ground state or the transfer may be reversed (see fig.1). The combination of solvent fluctuations plus intramolecular transitions is described by a master equation which can be solved analytically. The general solution shows multi exponential behavior. It contains the two limiting cases of slow and fast dielectric relaxation (as compared to the intramolecular transition rates) as special cases and is also able to describe the intermediate region where the timescales of solvent dynamics and intramolecular transitions are comparable.
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Bons, Jeffrey P., Rolf Sondergaard, and Richard B. Rivir. "The Fluid Dynamics of LPT Blade Separation Control Using Pulsed Jets." In ASME Turbo Expo 2001: Power for Land, Sea, and Air. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/2001-gt-0190.

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The effects of pulsed vortex generator jets on a naturally separating low pressure turbine boundary layer have been investigated experimentally. Blade Reynolds numbers in the linear turbine cascade match those for high altitude aircraft engines and industrial turbine engines with elevated turbine inlet temperatures. The vortex generator jets (30 degree pitch and 90 degree skew angle) are pulsed over a wide range of frequency at constant amplitude and selected duty cycles. The resulting wake loss coefficient vs. pulsing frequency data add to previously presented work by the authors documenting the loss dependency on amplitude and duty cycle. As in the previous studies, vortex generator jets are shown to be highly effective in controlling laminar boundary layer separation. This is found to be true at dimensionless forcing frequencies (F+) well below unity and with low (10%) duty cycles. This unexpected low frequency effectiveness is due to the relatively long relaxation time of the boundary layer as it resumes its separated state. Extensive phase-locked velocity measurements taken in the blade wake at an F+ of 0.01 with 50% duty cycle (a condition at which the flow is essentially quasi-steady) document the ejection of bound vorticity associated with a low momentum fluid packet at the beginning of each jet pulse. Once this initial fluid event has swept down the suction surface of the blade, a reduced wake signature indicates the presence of an attached boundary layer until just after the jet termination. The boundary layer subsequently relaxes back to its naturally separated state. This relaxation occurs on a timescale which is 5–6 times longer than the original attachment due to the starting vortex. Phase-locked boundary layer measurements taken at various stations along the blade chord illustrate this slow relaxation phenomenon. This behavior suggests that some economy of jet flow may be possible by optimizing the pulse duty cycle and frequency for a particular application. At higher pulsing frequencies, for which the flow is fully dynamic, the boundary layer is dominated by periodic shedding and separation bubble migration, never recovering its fully separated (uncontrolled) state.
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CHOW, REUBEN, and KING-WAI CHU. "Navier-Stokes solution for high-lift multielement airfoil system with flap separation." In 22nd Fluid Dynamics, Plasma Dynamics and Lasers Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1991. http://dx.doi.org/10.2514/6.1991-1623.

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Seto, Hideki, Shigehiro Komura, Dietmar Schwahn, and Kell Mortensen. "Mean-field behavior at phase separation in 3-component microemulsion system." In Slow dynamics in condensed matter. AIP, 1992. http://dx.doi.org/10.1063/1.42375.

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Zhang, X., H. Wen, D. Jin, J. Yang, and Q. Wang. "Autonomous separation strategies for in-orbit stacked satellites." In 1st International Conference on Mechanical System Dynamics (ICMSD 2022). Institution of Engineering and Technology, 2022. http://dx.doi.org/10.1049/icp.2022.2028.

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Burger, Benjamin S., Carole Addona, Benjamin Diedrich, William Harlin, Peter McDonough, Zachary Muscha, Harold Sells, and Daniel Tyler. "Space Launch System Liftoff and Separation Dynamics Analysis Tool Chain." In AIAA Scitech 2021 Forum. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2021. http://dx.doi.org/10.2514/6.2021-0822.

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Luo, C., H. Wen, D. Jin, J. Yang, and Q. Wang. "Dynamics of a multi-satellite system using elastic separation mechanism." In 1st International Conference on Mechanical System Dynamics (ICMSD 2022). Institution of Engineering and Technology, 2022. http://dx.doi.org/10.1049/icp.2022.2029.

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Ning, Lipeng, Tryphon T. Georgiou, and Allen Tannenbaum. "Separation of system dynamics and line spectra via sparse representation." In 2010 49th IEEE Conference on Decision and Control (CDC). IEEE, 2010. http://dx.doi.org/10.1109/cdc.2010.5717810.

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