Traditional Dynamic System Research Articles

Influence of flor yeast starters on volatile and nitrogen compounds during a controlled biological aging

Fino Sherry wine undergoes biological aging carried out by a velum of flor yeast within a traditional dynamic system known as “criaderas and solera”. The complex microbiota of biofilm-forming Saccharomyces cerevisiae strains play a crucial role in shaping the distinctive organoleptic profile of these types of wines. For this reason, the aim of this study is to analyze the changes produced by different flor yeast strains in the volatilome and the aminogram of different wines from the criaderas and solera system during biological aging in the laboratory, simulating a flor yeast velum condition at different stages of the system. Results suggest that each strain metabolizes wine differently, finding that depending on the wine, some strains are better suited for the process than others. In addition, it is found that the content of biogenic amines in Fino Sherry wines, previously attributed to malolactic bacteria, varies according to the yeast strain metabolizing the wine, suggesting that flor yeast could be used to modify biogenic amines content during biological aging. Results indicate that the use of selected flor yeast starters in biological aging may be of interest to modulate some parameters during Fino Sherry wine aging.

Control of a consumer‐resource agent‐based model using partial differential equation approximation

AbstractAgent‐based models (ABMs) are increasing in popularity as tools to simulate and explore many biological systems. Successes in simulation lead to deeper investigations, from designing systems to optimizing performance. The typically stochastic, rule‐based structure of ABMs, however, does not lend itself to analytic and numerical techniques of optimization the way traditional dynamical systems models do. The goal of this work is to illustrate a technique for approximating ABMs with a partial differential equation (PDE) system to design some management strategies on the ABM. We propose a surrogate modeling approach, using differential equations that admit direct means of determining optimal controls, with a particular focus on environmental heterogeneity in the ABM. We implement this program with both PDE and ordinary differential equation (ODE) approximations on the well‐known rabbits and grass ABM, in which a pest population consumes a resource. The control problem addressed is the reduction of this pest population through an optimal control formulation. After fitting the ODE and PDE models to ABM simulation data in the absence of control, we compute optimal controls using the ODE and PDE models, which we them apply to the ABM. The results show promise for approximating ABMs with differential equations in this context.

Supervised learning algorithms for controlling underactuated dynamical systems

Control of underactuated dynamical systems has been studied for decades in robotics, and is now emerging in other fields such as neuroscience. Most of the advances have been in model based control theory, which has limitations when the system under study is very complex and it is not possible to construct a model. This calls for data driven control methods like machine learning, which has spread to many fields in the recent years including control theory. However, the success of such algorithms has been dependent on availability of large datasets. Moreover, due to their black box nature, it is challenging to analyze how such algorithms work, which may be crucial in applications where failure is very costly. In this paper, we develop two related novel supervised learning algorithms. The algorithms are powerful enough to control a wide variety of complex underactuated dynamical systems, and yet have a simple and intelligent structure that allows them to work with a sparse data set even in the presence of noise. Our algorithms output a bang-bang (binary) control input by taking in feedback of the state of the dynamical system. The algorithms learn this control input by maximizing a reward function in both short and long time horizons. We demonstrate the versatility of our algorithms by applying them to a diverse range of applications including: switching between bistable states, changing the phase of an oscillator, desynchronizing a population of synchronized coupled oscillators, and stabilizing an unstable fixed point. For most of these applications we are able to reason why our algorithms work by using traditional dynamical systems and control theory. We also compare our learning algorithms with some traditional control algorithms, and reason why our algorithms work better.

Modelling of Informational Counteraction Between Objects In Economy

The article explores several aspects of the possible existence of informational actions and counteractions in the field of economy. The analysis of similar processes has been made utilizing structure-functional and structure-dynamic modelling. The basic models that allow revealing the essence of the phenomena under analysis are the systems of differential equations that are congruent with the constructions, which have used in the traditional dynamic system. The combination of contextual and subsidiary DFD-diagrams, developed following the technology SADT, allows understanding the functional logic of performed actions. The experimental part of the research had based on the use of imitation platform Analogic and the real statistic data that testified to the dynamic marketing behaviour of a range of business entities. These entities promoted their products in the market using information-communication technologies. The scholars of the study integrated structure-functional and structure-dynamic patterns of informational actions and counteractions in the field of the economy that have successfully tested. The results of modelling possess a high level of compatibility with the empirical data. It provides adequate prediction and assessment of the possibility of implementing various scenarios of events, and, consequently, in economy management.

Internal wave attractors in 3D geometries : A dynamical systems approach

We study the propagation in three dimensions of internal waves using ray tracing methods and traditional dynamical systems theory. The wave propagation on a cone that generalizes the Saint Andrew's cross justifies the introduction of an angle of propagation that allows to describe the position of the wave ray in the horizontal plane. Considering the evolution of this reflection angle for waves that repeatedly reflect off an inclined slope, a new trapping mechanism emerges that displays the tendency to align this angle with the upslope gradient. In the rather simple geometry of a translationally invariant canal, we show first that this configuration leads to trapezium-shaped attractors, very similar to what has been extensively studied in two-dimensions. However, we also establish a direct link between the trapping and the existence of two-dimensional attractors. In a second stage, considering a geometry that is not translationally invariant, closer to realistic configurations, we prove that although there are no two-dimensional attractors, one can find a structure in three-dimensional space with properties similar to internal wave attractors: a one-dimensional attracting manifold. Moreover, as this structure is unique, it should be easy to visualize in laboratory experiments since energy injected in the domain would eventually be confined to a very thin region in three-dimensional space, for which reason it is called a super-attractor.

Directed transport of fractional Brownian motor driven by a temporal asymmetry force

The directed transport of a Brownian particle in a spatially periodic symmetric field under a temporal asymmetric force is studied. Based on the Caputo’s fractional derivatives theory, we establish a differential aquation for an overdamped fractional Brownian motor as the system’s mathematic model, where the external force is zero-mean and the fractional order is used to describe the inhomogeneity of the real environment. Using the fractional differential algorithm, we analyze the relationships between transport velocity and model parameters. It is worth mentioning that the impact of fractional order is discussed in detail. According to the reflearch we find that a temporal asymmetric force can induce a net current without the application of a ratchet potential, even a noise. We also find that the velocity of the current increases monotonically with the increase in fractional order. Moreover with certain fractional orders, a generalized resonance phenomenon is reflealed since the velocity of the current varies non-monotonically with the system parameters, such as the height of the potential barrier and the noise strength etc. Research shows that the fractional system is a generalization of the traditional dynamic systems, which could probably give a more reasonable explanation of the directed transport as a consequence.

A Reachable Set Analysis Method for Generating Near-Optimal Trajectories of Constrained Multiphase Systems

Few sophisticated problems in the optimal control of a dynamical system can be solved analytically. There are many numerical solution methods, but most, especially those with the most potential accuracy, work iteratively and must be initialized with a guess of the solution. Satisfactory guesses may be very difficult to generate. In this work, a "Reachable Set Analysis" (RSA) method is developed to find near-optimal trajectories for multiphase systems with no a priori knowledge. A multiphase system is a generalization of a dynamical system that includes possible changes on the governing equations throughout the trajectory; the traditional dynamical system where the governing equations do not change is included in the formulation as a special case. The RSA method is based on a combination of metaheuristic algorithms and nonlinear programming. A particularly beneficial aspect of the solution found using RSA is that it satisfies the system governing equations and comes arbitrarily close (to a degree chosen by the planner) to satisfying given terminal conditions. Three qualitatively different multiphase problems, such as a low-thrust transfer from Earth to Mars, a system with chattering arcs in the optimal control, and a motion planning problem with obstacles, are solved using the near-optimal trajectories found by RSA as initial guesses to show the effectiveness of the new method.

Vibrational resonance in a Duffing system with fractional-order external and intrinsic dampings driven by the two-frequency signals

The phenomenon of vibrational resonance (VR) in a Duffing system with both fractional-order external damping and fractional-order intrinsic damping driven by the two-frequency periodic signals is investigated. It is observed that the resonance amplitude Q can be optimized by an appropriate choice of the amplitude of the high-frequency signal. The obtained relationship between VR and the fractional-orders shows that both fractional-order external damping and fractional-order intrinsic damping can induce changes of the shapes of the effective potential function and then lead to more abundant resonance behaviors than in the traditional dynamic systems.

Three-Dimensional Dynamic Modeling and Simulation of a Beam Attached to a Spatially Moving Base

摘要: 对附着在空间运动体上梁的动力学问题进行了研究,运用Lagrange方法建立了中心刚体作任意三维运动时,梁作横向振动和纵向振动的动力学方程,考虑了柔性梁的横向弯曲变形所带来的纵向位移,这种耦合变形使所得到的振动方程包含了动力刚化效应,这是与传统的梁振动模型的不同之处,最后通过仿真算例验证了该方法. 关键词: 柔性梁 / 动力刚化 / 三维振动

Sugar Contents of Brandy de Jerez during Its Aging

Brandy de Jerez is aged in American oak casks according to the traditional dynamic system (Soleras y Criaderas) and sometimes additionally by the static system (Anadas). The experimental arrangement used here for the analytical monitoring of brandy aging consisted of 15 casks, 12 of which were set up for aging by the dynamic system, which is well established in the denomination of origin area, whereas the other 3 contained the same brandy but aged according to the static system. This paper studies the kinetics of sugar extraction from oak wood to distillate, as well as the possible correlations between the sugar contents in brandy and its age or the commercial type it belongs to (Solera, Solera Reserva, or Solera Gran Reserva). High-performance anion-exchange chromatography with pulsed amperometric detection was used as the analytical tool to measure the concentrations of glucose, fructose, arabinose, galactose, and xylose, the presence of which in brandy has previously been described.

A neural network model of the dynamics of a short-term memory system in the temporal cortex

The temporal area TE of the monkey contains a group of neurons which seems to act as the short-term memory by a sustained firing, where the stored information seems to be retained by a certain kind of equilibrium of a dynamical system. The behavior of this group of neurons cannot be accounted for by the traditional dynamical system realized by the existing neural network models. This paper discusses the short-term memory system in the temporal area, as well as the dynamics of associative memory, and proposes the neural network model which realizes the same dynamical behavior as that of area TE. This model differs essentially from the traditional models in that the composing unit has non-monotonic input/output characteristics and a significant property in analyzing the behavior and the mechanics of the memory circuit in the brain.