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Polivayev, O. I., e A. N. Kuznetsov. "Bases of active noise control". Traktory i sel hozmashiny 82, n. 7 (15 luglio 2015): 30–34. http://dx.doi.org/10.17816/0321-4443-66049.
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LASIECKA, IRENA. "MATHEMATICAL CONTROL THEORY IN STRUCTURAL ACOUSTIC PROBLEMS". Mathematical Models and Methods in Applied Sciences 08, n. 07 (novembre 1998): 1119–53. http://dx.doi.org/10.1142/s0218202598000524.
Testo completoAbstract (sommario):
We consider control problems formulated within the context of structural acoustic models. The goal is to reduce the level of a noise or unwanted pressure in the interior of an acoustic chamber. This is accomplished by applying passive and active boundary and point controls in a feedback form. Mathematical (PDE) aspects of the underlying control problems are presented.
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Jondral, Friedrich K. "White Gaussian Noise – Models for Engineers". Frequenz 72, n. 5-6 (25 aprile 2018): 293–99. http://dx.doi.org/10.1515/freq-2017-0064.
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AbstractThis paper assembles some information about white Gaussian noise (WGN) and its applications. It starts from a description of thermal noise, i. e. the irregular motion of free charge carriers in electronic devices. In a second step, mathematical models of WGN processes and their most important parameters, especially autocorrelation functions and power spectrum densities, are introduced. In order to proceed from mathematical models to simulations, we discuss the generation of normally distributed random numbers. The signal-to-noise ratio as the most important quality measure used in communications, control or measurement technology is accurately introduced. As a practical application of WGN, the transmission of quadrature amplitude modulated (QAM) signals over additive WGN channels together with the optimum maximum likelihood (ML) detector is considered in a demonstrative and intuitive way.
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Gabbert, Ulrich, Fabian Duvigneau e Stefan Ringwelski. "NOISE CONTROL OF VEHICLE DRIVE SYSTEMS". Facta Universitatis, Series: Mechanical Engineering 15, n. 2 (2 agosto 2017): 183. http://dx.doi.org/10.22190/fume170615009g.
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The paper presents an overall simulation approach to control the noise emission of car engines at a very early stage of the design process where no real prototypes are available. The suggested approach combines different physical models and couples different software tools such as multi-body analysis, fluid dynamics, structural mechanics, magneto-electrodynamics, thermodynamics, acoustics and control as well. The general overall simulation methodology is presented first. Then, this methodology is applied to a combustion engine in order to improve its acoustical behavior by passive means, such as changing the stiffness and the use of damping materials to build acoustic and thermal encapsulations. The active control by applying piezoelectric patch actuators at the oil sump as the noisiest part of the engine is discussed as well. The sound emission is evaluated by hearing tests and a mathematical prediction model of the human perception. Finally, it is shown that the presented approach can be extended to electric engines, which is demonstrated at a newly developed electric wheel hub motor.
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Zhou, Peng, Mingtao Tan, Jianbo Ji e Jie Jin. "Design and Analysis of Anti-Noise Parameter-Variable Zeroing Neural Network for Dynamic Complex Matrix Inversion and Manipulator Trajectory Tracking". Electronics 11, n. 5 (7 marzo 2022): 824. http://dx.doi.org/10.3390/electronics11050824.
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Dynamic complex matrix inversion (DCMI) problems frequently arise in the territories of mathematics and engineering, and various recurrent neural network (RNN) models have been reported to effectively find the solutions of the DCMI problems. However, most of the reported works concentrated on solving DCMI problems in ideal no noise environment, and the inevitable noises in reality are not considered. To enhance the robustness of the existing models, an anti-noise parameter-variable zeroing neural network (ANPVZNN) is proposed by introducing a novel activation function (NAF). Both of mathematical analysis and numerical simulation results demonstrate that the proposed ANPVZNN model possesses fixed-time convergence and robustness for solving DCMI problems. Besides, a successful ANPVZNN-based manipulator trajectory tracking example further verifies its robustness and effectiveness in practical applications.
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Shi, Guojun, Robert E. Skelton e Karolos M. Grigoriadis. "Minimum output variance control for FSN models: Continuous-time case". Mathematical Problems in Engineering 6, n. 2-3 (2000): 171–88. http://dx.doi.org/10.1155/s1024123x00001319.
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In this paper we consider the Finite Signal-to-Noise ratio model for linear stochastic systems. It is assumed that the intensity of noise corrupting a signal is proportional to the variance of the signal. Hence, the signal-to-noise ratio of each sensor and actuator is finite – as opposed to the infinite signal-to-noise ratio assumed in LQG theory. Computational errors in the controller implementation are treated similarly. The objective is to design a state feedback control law such that the closed loop system is mean square asymptotically stable and the output variance is minimized. The main result is a controller which achieves its maximal accuracy with finite control gains – as opposed to the infinite controls required to achieve maximal accuracy in LQG controllers. Necessary and sufficient conditions for optimality are derived. An optimal control law which involves the positive definite solution of a Riccati-like equation is derived. An algorithm for solving the Riccati-like equation is given and its convergence is guaranteed if a solution exists.
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Petrovici, Alina, Jose Luis Cueto, Valentin Nedeff, Enrique Nava, Florin Nedeff, Ricardo Hernandez, Carmen Bujoreanu, Stefan Andrei Irimiciuc e Maricel Agop. "Dynamic Evaluation of Traffic Noise through Standard and Multifractal Models". Symmetry 12, n. 11 (11 novembre 2020): 1857. http://dx.doi.org/10.3390/sym12111857.
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Traffic microsimulation models use the movement of individual driver-vehicle-units (DVUs) and their interactions, which allows a detailed estimation of the traffic noise using Common Noise Assessment Methods (CNOSSOS). The Dynamic Traffic Noise Assessment (DTNA) methodology is applied to real traffic situations, then compared to on-field noise levels from measurement campaigns. This makes it possible to determine the influence of certain local traffic factors on the evaluation of noise. The pattern of distribution of vehicles along the avenue is related to the logic of traffic light control. The analysis of the inter-cycles noise variability during the simulation and measurement time shows no influence from local factors on the prediction of the dynamic traffic noise assessment tool based on CNOSSOS. A multifractal approach of acoustic waves propagation and the source behaviors in the traffic area are implemented. The novelty of the approach also comes from the multifractal model’s freedom which allows the simulation, through the fractality degree, of various behaviors of the acoustic waves. The mathematical backbone of the model is developed on Cayley–Klein-type absolute geometries, implying harmonic mappings between the usual space and the Lobacevsky plane in a Poincaré metric. The isomorphism of two groups of SL(2R) type showcases joint invariant functions that allow associations of pulsations–velocities manifolds type.
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Longtin, André, Brent Doiron e Adi R. Bulsara. "Noise-induced divisive gain control in neuron models". Biosystems 67, n. 1-3 (ottobre 2002): 147–56. http://dx.doi.org/10.1016/s0303-2647(02)00073-4.
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Tai, Yanni, Haibin Qu e Xingchu Gong. "Design Space Calculation and Continuous Improvement Considering a Noise Parameter: A Case Study of Ethanol Precipitation Process Optimization for Carthami Flos Extract". Separations 8, n. 6 (24 maggio 2021): 74. http://dx.doi.org/10.3390/separations8060074.
Testo completoAbstract (sommario):
The optimization of process parameters in the pharmaceutical industry is often carried out according to the Quality by Design (QbD) concept. QbD also emphasizes that continuous improvement should be performed in life cycle management. Process parameters that are difficult to control in actual production can be regarded as noise parameters. In this study, based on the QbD concept, the ethanol precipitation process of Carthami Flos extract was optimized, considering a noise parameter. The density of the concentrated extract, ethanol concentration, the volume ratio of ethanol to concentrated extract, stirring time after ethanol addition, and refrigeration temperature were selected as critical process parameters (CPPs), using a definitive screening design. The mathematical models among CPPs and evaluation indicators were established. Considering that the refrigeration temperature of industrial ethanol precipitation is often difficult to control with seasonal changes, refrigeration temperature was treated as a noise parameter. A calculation method for the design space in the presence of the noise parameter was proposed. The design space was calculated according to the probability of reaching the standards of evaluation indicators. Controlling parameters within the design space was expected to reduce the influence of noise parameter fluctuations on the quality of the ethanol precipitation supernatant. With more data obtained, the design space was updated. In industry, it is also recommended to adopt a similar idea: that is, continuing to collect industrial data and regularly updating mathematical models, which can further update the design space and make it more stable and reliable.
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Perkins, Theodore J., Roy Wilds e Leon Glass. "Robust dynamics in minimal hybrid models of genetic networks". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 368, n. 1930 (13 novembre 2010): 4961–75. http://dx.doi.org/10.1098/rsta.2010.0139.
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Many gene-regulatory networks necessarily display robust dynamics that are insensitive to noise and stable under evolution. We propose that a class of hybrid systems can be used to relate the structure of these networks to their dynamics and provide insight into the origin of robustness. In these systems, the genes are represented by logical functions, and the controlling transcription factor protein molecules are real variables, which are produced and destroyed. As the transcription factor concentrations cross thresholds, they control the production of other transcription factors. We discuss mathematical analysis of these systems and show how the concepts of robustness and minimality can be used to generate putative logical organizations based on observed symbolic sequences. We apply the methods to control of the cell cycle in yeast.
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Chodnicki, Marcin, Michal Mazur, Miroslaw Nowakowski e Grzegorz Kowaleczko. "The mathematical model of UAV vertical take-off and landing". Aircraft Engineering and Aerospace Technology 91, n. 2 (4 febbraio 2019): 249–56. http://dx.doi.org/10.1108/aeat-01-2018-0041.
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Purpose This paper aims to present a mathematical model of the dynamics of the unmanned aerial vehicle (UAV) vertical take-off and landing (VTOL). It will be used to develop control laws to a multirotor that is inherently unstable. Also, the model will be used to design algorithms to estimate the attitude of an object. Design/methodology/approach The physical model of UAV assumes that it is a rigid body with six degrees of freedom acted by forces generated by the propellers, motors, aerodynamic forces, gravity and disturbance forces. The mathematical model was described by differential equations. However, drive system (propeller, BLDC motor and BLDC motor controller) was described by six transfer functions. These transfer functions were demarcated with Matlab/Simulink identification toolbox from data received from a specially designed laboratory stand. Moments of inertia of the platform have been analytically determined and compared with empirical results from the pendulum. The mathematical model was implemented in Matlab/Simulink. Findings The paper confirms the need of designing mathematical models. Moreover, mathematical models show that some parts of the object are better to be replaced by experimental results than by equations, which is proved by the data. The paper also shows advantages of using Matlab/Simulink. What is more the simulation of the model proves that multirotor is an unstable object. Research limitations/implications The test results show that drive units are strongly dependent on ambient conditions. An additional problem is the different response of the drive set to increasing and decreasing the control signal amplitude. Next tests will be done at different temperatures and air densities of the environment, also it is need to explore drag forces. Practical implications The mathematical model is a simplification of the physical model expressed by means of equations. The results of simulation like accelerations and angular rate are noise-free. However, available sensors always have their errors and noise. To design control loops and attitude estimation algorithms, there is a need for identification of sensors’ errors and noise. These parameters have to be measured. Originality/value The paper describes a solution of correct identification of drive unit, which is a main component of the UAV.
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AIRAKSINEN, TUOMAS, ERKKI HEIKKOLA e JARI TOIVANEN. "LOCAL CONTROL OF SOUND IN STOCHASTIC DOMAINS BASED ON FINITE ELEMENT MODELS". Journal of Computational Acoustics 19, n. 02 (giugno 2011): 205–19. http://dx.doi.org/10.1142/s0218396x11004432.
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A numerical method for optimizing the local control of sound in a stochastic domain is developed. A three-dimensional enclosed acoustic space, for example, a cabin with acoustic actuators in given locations is modeled using the finite element method in the frequency domain. The optimal local noise control signals minimizing the least square of the pressure field in the silent region are given by the solution of a quadratic optimization problem. The developed method computes a robust local noise control in the presence of randomly varying parameters such as variations in the acoustic space. Numerical examples consider the noise experienced by a vehicle driver with a varying posture. In a model problem, a significant noise reduction is demonstrated at lower frequencies.
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Liu, Xian, Qing Gao, Baiwang Ma, Jiajia Du e Wenju Ren. "Analysis and Control of Epileptiform Spikes in a Class of Neural Mass Models". Journal of Applied Mathematics 2013 (2013): 1–11. http://dx.doi.org/10.1155/2013/792507.
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The problem of analyzing and controlling epileptiform spikes in a class of neural mass models is concerned with. Since the measured signals are always contaminated by measurement noise, an algebraic estimation method is utilized to observe the state from the noisy measurement. The feedback control is constructed via the estimated state. The feasibility of using such a strategy to control epileptiform spikes in a regular network of coupled neural populations is demonstrated by simulations. In addition, the influence of the type of the controlled populations, the number of the controlled populations, and the control gain is investigated in details.
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Hern�ndez-Lerma, On�simo, e Rolando Cavazos-Cadena. "Continuous dependence of stochastic control models on the noise distribution". Applied Mathematics & Optimization 17, n. 1 (gennaio 1988): 79–89. http://dx.doi.org/10.1007/bf01448360.
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Johnston, D. N., e J. E. Drew. "Measurement of Positive Displacement Pump Flow Ripple and Impedance". Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering 210, n. 1 (febbraio 1996): 65–74. http://dx.doi.org/10.1243/pime_proc_1996_210_437_02.
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The secondary source method forms the British Standard for pump fluid-borne noise testing. This is a powerful technique but requires care in order to produce accurate results. This paper describes practical aspects for implementing the method. The requirements for the test rig, data acquisition system and analysis are detailed. The British Standard specifies that either mathematical modelling or linear interpolation is used on the source impedance measurements. A method for smoothing the impedance results is described in this paper, which is shown to give more repeatable results than linear interpolation. Some physically realistic mathematical models of pump impedance are described, and their use in determining the internal flow ripple discussed.
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Nanda, Santosh Kumar, e Debi Prasad Tripathy. "Application of Functional Link Artificial Neural Network for Prediction of Machinery Noise in Opencast Mines". Advances in Fuzzy Systems 2011 (2011): 1–11. http://dx.doi.org/10.1155/2011/831261.
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Functional link-based neural network models were applied to predict opencast mining machineries noise. The paper analyzes the prediction capabilities of functional link neural network based noise prediction models vis-à-vis existing statistical models. In order to find the actual noise status in opencast mines, some of the popular noise prediction models, for example, ISO-9613-2, CONCAWE, VDI, and ENM, have been applied in mining and allied industries to predict the machineries noise by considering various attenuation factors. Functional link artificial neural network (FLANN), polynomial perceptron network (PPN), and Legendre neural network (LeNN) were used to predict the machinery noise in opencast mines. The case study is based on data collected from an opencast coal mine of Orissa, India. From the present investigations, it could be concluded that the FLANN model give better noise prediction than the PPN and LeNN model.
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Kobayashi, Yasuhide, Hisaya Fujioka e Naoki Jinbo. "A Control Source Structure of Single Loudspeaker and Rear Sound Interference for Inexpensive Active Noise Control". Advances in Acoustics and Vibration 2010 (30 giugno 2010): 1–9. http://dx.doi.org/10.1155/2010/730813.
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Active noise control systems of simple ducts are investigated. In particular, open-loop characteristics and closed-loop performances corresponding to various structures of control sources are compared based on both mathematical models and experimental results. In addition to the standard single loudspeaker and the Swinbanks' source, we propose and examine a single loudspeaker with a rear sound interference as a novel structure of control source, where the rear sound radiated from the loudspeaker is interfered with the front sound in order to reduce the net upstream sound directly radiated from the control source. The comparisons of the control structures are performed as follows. First, the open-loop transfer function is derived based on the standard wave equation, where a generalized control structure unifying the three structures mentioned above is considered. Secondly, by a comparison of the open-loop transfer functions from the first principle modeling and frequency response experiments, it is shown that a certain phase-lag is imposed by the Swinbanks' source and the rear sound interference. Thirdly, effects on control performances of control source structures are examined by control experiments with robust controllers.
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Kadakia, Nirag. "Optimal control methods for nonlinear parameter estimation in biophysical neuron models". PLOS Computational Biology 18, n. 9 (15 settembre 2022): e1010479. http://dx.doi.org/10.1371/journal.pcbi.1010479.
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Functional forms of biophysically-realistic neuron models are constrained by neurobiological and anatomical considerations, such as cell morphologies and the presence of known ion channels. Despite these constraints, neuron models still contain unknown static parameters which must be inferred from experiment. This inference task is most readily cast into the framework of state-space models, which systematically takes into account partial observability and measurement noise. Inferring only dynamical state variables such as membrane voltages is a well-studied problem, and has been approached with a wide range of techniques beginning with the well-known Kalman filter. Inferring both states and fixed parameters, on the other hand, is less straightforward. Here, we develop a method for joint parameter and state inference that combines traditional state space modeling with chaotic synchronization and optimal control. Our methods are tailored particularly to situations with considerable measurement noise, sparse observability, very nonlinear or chaotic dynamics, and highly uninformed priors. We illustrate our approach both in a canonical chaotic model and in a phenomenological neuron model, showing that many unknown parameters can be uncovered reliably and accurately from short and noisy observed time traces. Our method holds promise for estimation in larger-scale systems, given ongoing improvements in calcium reporters and genetically-encoded voltage indicators.
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Pi, Zong-xin, Hui-jiao Guo, Jing-xin Guo, Hong-ya Geng e Zheng Jiao. "Noise-induced cooperative dynamics and its control in coupled electrochemical models". Journal of Shanghai University (English Edition) 14, n. 4 (31 luglio 2010): 241–45. http://dx.doi.org/10.1007/s11741-010-0637-2.
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Monakov, A. A., e A. A. Tarasenkov. "Comparative Analysis of Mathematical Models of Tracking Radio Altimeters". Journal of the Russian Universities. Radioelectronics 25, n. 4 (29 settembre 2022): 72–80. http://dx.doi.org/10.32603/1993-8985-2022-25-4-72-80.
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Introduction. Tracking radio altimeters of low altitudes are widely used in civil aviation. These devises use periodic frequency modulated continuous wave (FMCW) signals, while altitude measurements are based on processing the beat signal processing. For this purpose, a closed automatic control loop is arranged to maintain the frequency of the beat signal at a fixed level by changing parameters of the transmitted signal (the frequency deviation or the modulation period). An alternative approach to arranging the tracking loop for altitude variations is based on the use of a phase locked loop (PLL), which adjusts the reference signal – a copy of the emitted signal – to obtain the maximum cross-correlation of the beat and reference signals. А comparative analysis of short-range radio altimeters with other currently known tracking radio altimeters for various types of frequency modulation of the transmitted signal seems to be a relevant research task.Aim. An analysis of the influence of the type of frequency modulation on the accuracy of altitude estimation in a PLL-based radar altimeter, as well as a comparative analysis of this altimeter with other known tracking altimeters.Materials and methods. Mathematical models of tracking radio altimeters are proposed, and a computer simulation of their performance is carried out for the case of altitude estimation over a smooth flat surface.Results. The conducted comparative analysis of tracking radio altimeters confirmed the effectiveness of the PLL when processing signals of different frequency modulation type (sawtooth, triangular, and harmonic FM). Altitude estimates produced by PLL-based radar altimeters are unbiased, with their standard deviation not exceeding 3 cm for the signalto-noise ratio of greater than 10 dB and under the scenario parameters adopted in the work. The conducted comparison with other tracking altimeters showed that estimation errors of this radar altimeter are an order of magnitude smaller.Conclusion. A PLL-based tracking radar altimeter can be used to estimate the height of the aircraft flight. The quality of altitude estimates produced by this device is higher than those produced by other known tracking radio altimeters. Further research and field tests will investigate the accuracy of altitude estimation when working over a rough surface.
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Xu, Chao, Xianqiang Yang e Miao Yu. "Robust LPV models identification approach based on shifted asymmetric Laplace distribution". Measurement and Control 54, n. 9-10 (novembre 2021): 1336–46. http://dx.doi.org/10.1177/00202940211028904.
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This paper focuses on the robust parameters estimation algorithm of linear parameters varying (LPV) models. The classical robust identification techniques deal with the polluted training data, for example, outliers in white noise. The paper extends this robustness to both symmetric and asymmetric noise with outliers to achieve stronger robustness. Without the assumption of Gaussian white noise pollution, the paper employs asymmetric Laplace distribution to model broader noise, especially the asymmetrically distributed noise, since it is an asymmetric heavy-tailed distribution. Furthermore, the asymmetric Laplace (AL) distribution is represented as the product of Gaussian distribution and exponential distribution to decompose this complex AL distribution. Then, a shifted parameter is introduced as the regression term to connect the probabilistic models of the noise and the predict output that obeys shifted AL distribution. In this way, the posterior probability distribution of the unobserved variables could be deduced and the robust parameters estimation problem is solved in the general Expectation Maximization algorithm framework. To demonstrate the advantage of the proposed algorithm, a numerical simulation example is employed to identify the parameters of LPV models and to illustrate the convergence.
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Mavroudis, Panteleimon D., Jeremy D. Scheff, John C. Doyle, Yoram Vodovotz e Ioannis P. Androulakis. "The Impact of Stochasticity and Its Control on a Model of the Inflammatory Response". Computation 7, n. 1 (28 dicembre 2018): 3. http://dx.doi.org/10.3390/computation7010003.
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The dysregulation of inflammation, normally a self-limited response that initiates healing, is a critical component of many diseases. Treatment of inflammatory disease is hampered by an incomplete understanding of the complexities underlying the inflammatory response, motivating the application of systems and computational biology techniques in an effort to decipher this complexity and ultimately improve therapy. Many mathematical models of inflammation are based on systems of deterministic equations that do not account for the biological noise inherent at multiple scales, and consequently the effect of such noise in regulating inflammatory responses has not been studied widely. In this work, noise was added to a deterministic system of the inflammatory response in order to account for biological stochasticity. Our results demonstrate that the inflammatory response is highly dependent on the balance between the concentration of the pathogen and the level of biological noise introduced to the inflammatory network. In cases where the pro- and anti-inflammatory arms of the response do not mount the appropriate defense to the inflammatory stimulus, inflammation transitions to a different state compared to cases in which pro- and anti-inflammatory agents are elaborated adequately and in a timely manner. In this regard, our results show that noise can be both beneficial and detrimental for the inflammatory endpoint. By evaluating the parametric sensitivity of noise characteristics, we suggest that efficiency of inflammatory responses can be controlled. Interestingly, the time period on which parametric intervention can be introduced efficiently in the inflammatory system can be also adjusted by controlling noise. These findings represent a novel understanding of inflammatory systems dynamics and the potential role of stochasticity thereon.
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Li, Yan Jie, Yun Feng Bai, Jian Zhang e Ji Hai Jiang. "Flow Field Simulation and Experimental Research on the Triangle Groove Cone Throttle Valve". Applied Mechanics and Materials 779 (luglio 2015): 42–49. http://dx.doi.org/10.4028/www.scientific.net/amm.779.42.
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Aiming at the problems of cavitation noise in the cone throttle valve, triangle groove cone throttle valves with 45, 53, 60 degree were selected as the research objects. Firstly the structure characteristics of the throttle valves were analyzed, then the three-dimensional models and mathematical models were established. By using the finite element simulation software ADINA, the simulation diagrams about pressure and flow velocity of the cone valves were obtained and then verified on the test bench which was about the noise characteristics of throttle valve. The investigation result showed that the flow field of the cone valve was complex, and there were local low pressure areas where were high incidence of cavitation; the valve with 60 degree spool had the minimum noise, which showed the best performance, then the 53 degree spool was a bit poor, and the worst valve was 45 degree spool. Increasing the angles of the triangle groove appropriately could reduce the cavitation noise and improve the performance of the valve. This investigation has great significance on understanding the flow field and controlling the cavitation noise in triangle groove cone throttle valves. Besides it also has a certain reference value to other hydraulic components on the cavitation noise control and structural optimization.
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Funato, Tetsuro, Shinya Aoi, Nozomi Tomita e Kazuo Tsuchiya. "Smooth enlargement of human standing sway by instability due to weak reaction floor and noise". Royal Society Open Science 3, n. 1 (gennaio 2016): 150570. http://dx.doi.org/10.1098/rsos.150570.
Testo completoAbstract (sommario):
Human quiet standing is accompanied by body sway. The amplitude of this body sway is known to be larger than would be predicted from simple noise effects, and sway characteristics are changed by neurological disorders. This large sway is thought to arise from nonlinear control with prolonged periods of no control (intermittent control), and a nonlinear control system of this kind has been predicted to exhibit bifurcation. The presence of stability-dependent transition enables dynamic reaction that depends on the stability of the environment, and can explain the change in sway characteristics that accompanies some neurological disorders. This research analyses the characteristics of a system model that induces transition, and discusses whether human standing reflects such a mechanism. In mathematical analysis of system models, (intermittent control-like) nonlinear control with integral control is shown to exhibit Hopf bifurcation. Moreover, from the analytical solution of the system model with noise, noise is shown to work to smooth the enlargement of sway around the bifurcation point. This solution is compared with measured human standing sway on floors with different stabilities. By quantitatively comparing the control parameters between human observation and model prediction, enlargement of sway is shown to appear as predicted by the model analysis.
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Bakare, Emmanuel A., e Sarka Hoskova-Mayerova. "Optimal Control Analysis of Cholera Dynamics in the Presence of Asymptotic Transmission". Axioms 10, n. 2 (12 aprile 2021): 60. http://dx.doi.org/10.3390/axioms10020060.
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Many mathematical models have explored the dynamics of cholera but none have been used to predict the optimal strategies of the three control interventions (the use of hygiene promotion and social mobilization; the use of treatment by drug/oral re-hydration solution; and the use of safe water, hygiene, and sanitation). The goal here is to develop (deterministic and stochastic) mathematical models of cholera transmission and control dynamics, with the aim of investigating the effect of the three control interventions against cholera transmission in order to find optimal control strategies. The reproduction number Rp was obtained through the next generation matrix method and sensitivity and elasticity analysis were performed. The global stability of the equilibrium was obtained using the Lyapunov functional. Optimal control theory was applied to investigate the optimal control strategies for controlling the spread of cholera using the combination of control interventions. The Pontryagin’s maximum principle was used to characterize the optimal levels of combined control interventions. The models were validated using numerical experiments and sensitivity analysis was done. Optimal control theory showed that the combinations of the control intervention influenced disease progression. The characterisation of the optimal levels of the multiple control interventions showed the means for minimizing cholera transmission, mortality, and morbidity in finite time. The numerical experiments showed that there are fluctuations and noise due to its dependence on the corresponding population size and that the optimal control strategies to effectively control cholera transmission, mortality, and morbidity was through the combinations of all three control interventions. The developed models achieved the reduction, control, and/or elimination of cholera through incorporating multiple control interventions.
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Moon, Francis C., e Preston D. Stiefel. "Coexisting chaotic and periodic dynamics in clock escapements". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 364, n. 1846 (28 luglio 2006): 2539–64. http://dx.doi.org/10.1098/rsta.2006.1839.
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This paper addresses the nature of noise in machines. As a concrete example, we examine the dynamics of clock escapements from experimental, historical and analytical points of view. Experiments on two escapement mechanisms from the Reuleaux kinematic collection at Cornell University are used to illustrate chaotic-like noise in clocks. These vibrations coexist with the periodic dynamics of the balance wheel or pendulum. A mathematical model is presented that shows how self-generated chaos in clocks can break the dry friction in the gear train. This model is shown to exhibit a strange attractor in the structural vibration of the clock. The internal feedback between the oscillator and the escapement structure is similar to anti-control of chaos models.
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Grechishnikov, V. M., e E. G. Komarov. "Mathematical model of functioning of multisensor converter of binary mechanical signals in electric on the basis of fiber-optic digital-to-analog converter". Izmeritel`naya Tekhnika, n. 2 (2020): 20–28. http://dx.doi.org/10.32446/0368-1025it.2020-2-20-28.
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The design and operation principle of a multisensor converter of binary mechanical signals into electrical signals consisting of a fiber-optic digital-analog converter, a photo amplifier and a voltage-to-code converter with double integration are considered. A generalized mathematical model of multisensor converter functioning has been developed, which combines particular mathematical models of fiber-optic digital-to-analog converter, photo-amplifier and voltage-to-code converter with double integration. The mathematical model of functioning of the multisensor converter in the form of analytical expressions for definition of the output electric code depending on values of bit digits of the input mechanical code taking into account a complex of constructive, circuit and power parameters of the converter is developed. The analytical description of the signal in the frequency converter in code, using which an algorithm is developed for numerical analysis of mathematical models of the functioning of the devices under study, providing the maximum permissible values of the instrumental errors of manufacture of the transducer elements in which is implemented the complete accuracy of the device. The presented results can be used for the development of multisensor converters of binary displacements of control systems, control and monitoring of energy-saturated objects, for which high noise immunity, electrical neutrality, low chemical activity and information security are of paramount importance.
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CISTERNAS, JAIME, DANIEL ESCAFF, ORAZIO DESCALZI e STEFAN WEHNER. "STOCHASTIC MODEL CALCULATION FOR THE CARBON MONOXIDE OXIDATION ON IRIDIUM(111) SURFACES". International Journal of Bifurcation and Chaos 19, n. 10 (ottobre 2009): 3461–72. http://dx.doi.org/10.1142/s0218127409024906.
Testo completoAbstract (sommario):
We study the effect of external noise on the catalytic oxidation of CO on an Iridium(111) single crystal under ultrahigh vacuum conditions. This reaction can be considered as a model of catalysis used in industry. In the absence of noise the reaction exhibits one or two stable stationary states, depending on control parameters such as temperature and partial pressures. When noise is added, for instance, by randomly varying the quality of the influx mixture, the system exhibits stochastic reaction rate and switching. In this work, we present two approaches: one for the monostable regime, and another for the bistable situation that relies on a white noise approximation. Both approaches rest on the assumption that spatial patterns of coverage on the Iridium plate can be neglected on a first approximation. Using mathematical models, it is possible to reconstruct stationary probability distribution functions that match experimental observations and provide support for the existence of a thermodynamic potential.
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Berestovitsky, Erlen Grigorievich, e Michael Solovyev. "SIMULATION OF ACOUSTIC WAVE PROPAGATION IN HYDRAULIC CONTROL SYSTEMS WITH OBTAINING SPECTRAL CHARACTERISTICS OF SOUND POWER DISTRIBUTION IN THE SOFTWARE PACKAGE SIMHYDRAULICS MATLAB". Journal of Dynamics and Vibroacoustics 7, n. 1 (17 gennaio 2021): 21–27. http://dx.doi.org/10.18287/2409-4579-2021-7-1-21-27.
Testo completoAbstract (sommario):
Modern hydraulic systems are subject to stringent noise and vibration requirements. In the existing scope of work a lot of attention is paid to a variety of factors, often without taking into account their mutual influence. In General, they can be divided into schematic design, system and principle. Currently, the development of science and technology is at a level where further improvement of the acoustic quality of individual elements and systems as a whole is possible in the study of emerging processes at the intersection of Sciences. In this regard, the paper considers the possibility of modeling wave processes in hydraulic control systems with the subsequent obtaining of acoustic characteristics, which is a joint use of the mathematical apparatus of the control theory and methods of acoustics. The simhydraulics Matlab software package is considered as one of the most suitable means of solving the tasks. Along with mathematical models of control system elements, the paper proposes acoustic models of elements that are taken into account when modeling transients in the system. Based on the results obtained, additional criteria for assessing the quality of management systems are proposed.
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Peng, Li Kun, Yang Yang Zhang e Liang Qin Yu. "Water Hammer Characteristic of the Pipeline in Ship Pitch Balance System". Applied Mechanics and Materials 341-342 (luglio 2013): 400–405. http://dx.doi.org/10.4028/www.scientific.net/amm.341-342.400.
Testo completoAbstract (sommario):
In ship pitch balance system, serious flow impact and water hammer occur because of the turning on and off of valve during the procedure of water-shift. Flow area of the ball valve used most on ship was derived, and mathematical models of pressure lost before and after valve were formulated. Besides, considering the fact of water-shift balance system, an AMESim model was established based on improved traditional throttle model. And the validity of AMESim model was ascertained by comparing simulation results of stable pressure before and after valve with calculated values from mathematical models. Then, with the AMESim model, impact characteristics of water-shift pipeline were investigated when adopting various valve switch rules, length of pipelines before and after valve and using an accumulator in system. From that, methods to reduce pipeline impact were proposed, which make good references for noise control of ship pitch balance system.
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Ilie, Silvana, e Monjur Morshed. "Adaptive Time-Stepping Using Control Theory for the Chemical Langevin Equation". Journal of Applied Mathematics 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/567275.
Testo completoAbstract (sommario):
Stochastic modeling of biochemical systems has been the subject of intense research in recent years due to the large number of important applications of these systems. A critical stochastic model of well-stirred biochemical systems in the regime of relatively large molecular numbers, far from the thermodynamic limit, is the chemical Langevin equation. This model is represented as a system of stochastic differential equations, with multiplicative and noncommutative noise. Often biochemical systems in applications evolve on multiple time-scales; examples include slow transcription and fast dimerization reactions. The existence of multiple time-scales leads to mathematical stiffness, which is a major challenge for the numerical simulation. Consequently, there is a demand for efficient and accurate numerical methods to approximate the solution of these models. In this paper, we design an adaptive time-stepping method, based on control theory, for the numerical solution of the chemical Langevin equation. The underlying approximation method is the Milstein scheme. The adaptive strategy is tested on several models of interest and is shown to have improved efficiency and accuracy compared with the existing variable and constant-step methods.
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Chen, Wei, e Song Ping Wu. "Numerical Analysis of Aerodynamic Noise of a New High-Speed Train". Applied Mechanics and Materials 275-277 (gennaio 2013): 681–86. http://dx.doi.org/10.4028/www.scientific.net/amm.275-277.681.
Testo completoAbstract (sommario):
Along with the raising of the train speed, aerodynamic noise of the high-speed train is generated more and more significantly and their reduction has become one of the key factors to control noise of the high-speed train. Aerodynamic noise radiated from the high-speed train surface was analyzed numerically. The mathematical and physical models of the three dimensional flow field of the high-speed train were established and the external steady and unsteady flow fields of the high-speed train were calculated by using the standard "k-ε" turbulence model and large eddy simulation (LES) respectively. On the basis of the steady flow field, aerodynamic noise sources on the car body surface of the high-speed train are calculated by using the broadband noise source model. On the basis of the unsteady flow field, the time domain characteristics of fluctuating pressures on the car body surface are analyzed. The sound pressure level on the surface pressure demonstrating is calculated and the flow field of some critical parts is analyzed.
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Dovbnya, Vitaly G., e Dmitry S. Koptev. "MATHEMATICAL MODEL OF THE RECEIVING PATH OF DIGITAL COMMUNICATION LINES". T-Comm 15, n. 5 (2021): 52–57. http://dx.doi.org/10.36724/2072-8735-2021-15-5-52-57.
Testo completoAbstract (sommario):
Modern trends in the development of digital communication lines of fixed information transmission services, as well as the characteristics of continuous channels today determine the noise immunity of radio receiving systems. The main directions of its increase in terms of the radio receiving device as a whole and the demodulator device in particular are as follows: reducing the frequency and nonlinear distortions of the signal in the linear path, increasing the stability and purity of the spectral line of oscillations of local oscillators, increasing the selectivity for the mirror and combination channels of reception, compensation for intersymbol and cross – polarization interference, improving the functioning of the automatic gain control device (reducing static and dynamic errors), improving the quality of the functioning of the carrier wave recovery device and the clock synchronization device. Taking into account all of the above factors in order to increase the overall noise immunity of a digital communication line is a very difficult and urgent task, the solution of which must begin with the development of a mathematical model of a continuous digital communication line channel. This article discusses the radio receiving path of a digital communication line in an urban environment. The obtained analytical expressions are aimed at interpreting the processes of converting digital signals in the structural elements of radio receiving systems. The originality of the mathematical model developed in the article lies in the fact that it additionally, in comparison with similar models, takes into account the following number of factors: frequency instability and phase fluctuations of oscillations of the local oscillator synthesizer, dynamic and static errors in the operation of automatic gain control devices, carrier vibration recovery devices and devices clock synchronization of radio receiving systems of digital signals.
34
Lomakin, A., D. Pantenkov e V. Sokolov. "Mathematical Models of Satellite Communication Systems with Unmanned Aerial Vehicles and Counter-Means of Radio Control. Part 2". Proceedings of Telecommunication Universities 5, n. 4 (2019): 37–48. http://dx.doi.org/10.31854/1813-324x-2019-5-4-37-48.
Testo completoAbstract (sommario):
The article is devoted to the issues of stealth satellite radio channels with unmanned aerial vehicles (UAV) and it is consists of two parts. In the first part of this article the following questions are considered: the general statement of a system development problem of satellite model communication providing its stealth functioning by means of radio monitoring is carried out; the mathimatical apparatus for the assessing the effectiveness of ensuring spatial selectivity in the organization of satellite communication lines at hidden objects of their functioning is presented; the functioning model of the satellite communication system wich use the signal processing methods to ensure the secrecy of its functioning by means of radio monitoring is developed; in the conclusion, proposals and recommendations are formulated to ensure the secrecy of the satellite radio channel with unmanned aerial vehicles. Since the eventual opponent a priori lacks complete reliable information about the radio monitoring signal, the second part of the article considers the methods of quasi-optimal signal processing based on auto-and intercorrelation processing, which allows to obtain a significant energy gain and detect a useful signal even at a very low level of its power at the input. The use of autocorrelation signal processing devices significantly improves the efficiency of radio monitoring (RM), which is especially important in the case of negative ratios of useful signal power and noise at the input of autocorrelation signal processing devices. The main results of the second part of the article include: a mathematical functioning model of the opponent's RM means in the conditions of taking measures to ensure the information transfer secrecy, the parameters calculations results of the satellite system provided that it is hidden from the RM means.
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Kumar, Shailendra, e Bhagat Singh. "Quantification of tool chatter and metal removal rate using wavelet denoising and statistical approach". Noise & Vibration Worldwide 49, n. 2 (febbraio 2018): 62–81. http://dx.doi.org/10.1177/0957456518763159.
Testo completoAbstract (sommario):
Tool chatter is an unavoidable phenomenon encountered in machining processes. Acquired raw chatter signals are contaminated with various types of ambient noises. Signal processing is an efficient technique to explore chatter as it eliminates unwanted background noise present in the raw signal. In this study, experimentally recorded raw chatter signals have been denoised using wavelet transform in order to eliminate the unwanted noise inclusions. Moreover, effect of machining parameters such as depth of cut ( d), feed rate ( f) and spindle speed ( N) on chatter severity and metal removal rate has been ascertained experimentally. Furthermore, in order to quantify the chatter severity, a new parameter called chatter index has been evaluated considering aforesaid denoised signals. A set of 15 experimental runs have been performed using Box–Behnken design of experiment. These experimental observations have been used to develop mathematical models for chatter index and metal removal rate considering response surface methodology. In order to check the statistical significance of control parameters, analysis of variance has been performed. Furthermore, more experiments are conducted and these results are compared with the theoretical ones in order to validate the developed response surface methodology model.
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Price, G. Richard, Joel T. Kalb e Georges R. Garinther. "Toward a Measure of Auditory Handicap in the Army". Annals of Otology, Rhinology & Laryngology 98, n. 5_suppl (maggio 1989): 42–52. http://dx.doi.org/10.1177/00034894890980s508.
Testo completoAbstract (sommario):
The effect of a soldier's ability to hear on the capacity to perform a mission was calculated for a variety of militarily relevant tasks through the use of mathematical models. Changes in hearing can result from organic loss, hearing protectors, the masking effect of noises, etc. The effects were calculated for the detection of sounds of enemy personnel (speech, movement noises) or their equipment (rifle bolt, tank, generator). We also calculated the effects on the ability to control/communicate with troops verbally. The normal ear is highly effective in detecting noises of personnel or their equipment or in understanding speech, even in noise. By contrast, even modest hearing losses and/or the wearing of hearing protectors can have profound effects on military performance, for example, reducing the area that can be monitored acoustically by more than 30-fold or cutting warning times for other sounds by a factor of more than 100. Hearing protectors may have the conflicting effects of protecting hearing while producing unacceptable performance because of their attenuation.
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Hao, Wenyue, Jiajun Wang, Ximing He, Zuchao Zhu, Zhengdao Wang, Hui Yang, Wei Zhang e Yikun Wei. "Reduction of aerodynamic noise of single-inlet centrifugal fan with inclined volute tongue". Measurement and Control 53, n. 7-8 (27 giugno 2020): 1376–87. http://dx.doi.org/10.1177/0020294020932360.
Testo completoAbstract (sommario):
The effect of inclined volute tongue on the aerodynamic noise and performance of a centrifugal fan was investigated by experimental test in this article. The present work highlights that the effect of both the clearance and the radius of the volute tongue has an influence on the performance and noise. The experimental tests of various models aim to obtain the aerodynamic noise and performance characteristics of several fan models. First, the experimental results of centrifugal fan performance are tested by the standard test equipment of aerodynamic performance. The experimental results of centrifugal fan aerodynamic noise are measured by the standard test equipment of experimental noise. Our experimental results mainly show that the generation of aerodynamic noise is significantly correlated with the clearance and radius of the volute tongue. Certain geometries of the volute tongue could reduce the noise of the centrifugal fan without decreasing the performance. It is experimentally demonstrated that the high A-weighted sound pressure levels mainly concentrate on a range of from 700 to 7000 Hz frequency by observing the each 1/3 octave band frequency for four fan models. The comparison of aerodynamic noise results also demonstrates that the inclined volute tongue may not only produce a deceasing of about 1.58 dB compared to that of the baseline model. We further obtain that the properly inclined volute tongue not only has positive performance features compared with the baseline model but also effectively controls the broadband frequency noise of single-inlet centrifugal fan.
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Kumar, K., D. Yadav e B. V. Srinivas. "Adaptive noise models for extended Kalman filter". Journal of Guidance, Control, and Dynamics 14, n. 2 (marzo 1991): 475–77. http://dx.doi.org/10.2514/3.20665.
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Kochuk, Serhii, Dinh Dong Nguyen, Artem Nikitin e Rafael Trujillo Torres. "Identification of UAV model parameters from flight and computer experiment data". Aerospace technic and technology, n. 6 (29 novembre 2021): 12–22. http://dx.doi.org/10.32620/aktt.2021.6.02.
Testo completoAbstract (sommario):
The object of research in the article is various well-known approaches and methods of structural and parametric identification of dynamic controlled objects - unmanned aerial vehicles (UAVs). The subject of the research is the parameters of linear and nonlinear mathematical models of spatial and isolated movements, describing the dynamics and aerodynamic properties of the UAV and obtained both from the results of flight experiments and using computer object-oriented programs for 3-D UAV models. The goal is to obtain mathematical models of UAV flight dynamics in the form of differential equations or transfer functions, check them for reliability and the possibility of using them in problems of synthesis of algorithms for automatic control systems of UAVs. Tasks to be solved: evaluation of the analytical (parametric), direct (transient), as well as the identification method using the 3-D model of the control object. Methods used structural and parametric identification of dynamic objects; the determination of static and dynamic characteristics of mathematical models by the type of their transient process; the System Identification Toolbox package of the MatLab environment, the Flow Simulation subsystem of the SolidWorks software and the X-Plane software environment. The experimental parameters of UAV flights, as well as the results of modeling in three-dimensional environments, are the initial data for the identification of mathematical models. The following results were obtained: the possibility of analytical and computer identification of mathematical models by highly noisy parameters of the UAV flight was shown; the mathematical models of UAVs obtained after identification is reliable and adequately reproduce the dynamics of a real object. A comparative analysis of the considered UAV identification methods is conducted, their performance and efficiency are confirmed. Conclusions. The scientific novelty of the result obtained is as follows: good convergence, reliability and the possibility of using the considered identification methods for obtaining mathematical models of dynamic objects to synthesize algorithms for automatic control systems of UAVs is shown.
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Huba, Mikulas, e Damir Vrancic. "Delay Equivalences in Tuning PID Control for the Double Integrator Plus Dead-Time". Mathematics 9, n. 4 (7 febbraio 2021): 328. http://dx.doi.org/10.3390/math9040328.
Testo completoAbstract (sommario):
The paper investigates and explains a new simple analytical tuning of proportional-integrative-derivative (PID) controllers. In combination with nth order series binomial low-pass filters, they are to be applied to the double-integrator-plus-dead-time (DIPDT) plant models. With respect to the use of derivatives, it should be understood that the design of appropriate filters is not only an implementation problem. Rather, it is also critical for the resulting performance, robustness and noise attenuation. To simplify controller commissioning, integrated tuning procedures (ITPs) based on three different concepts of filter delay equivalences are presented. For simultaneous determination of controller + filter parameters, the design uses the multiple real dominant poles method. The excellent control loop performance in a noisy environment and the specific advantages and disadvantages of the resulting equivalences are discussed. The results show that none of them is globally optimal. Each of them is advantageous only for certain noise levels and the desired degree of their filtering.
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Vu, Ngoc Kien, e Hong Quang Nguyen. "Balancing Control of Two-Wheel Bicycle Problems". Mathematical Problems in Engineering 2020 (22 luglio 2020): 1–12. http://dx.doi.org/10.1155/2020/6724382.
Testo completoAbstract (sommario):
In recent years, more and more scientists have been interested in research on driving two-wheel bicycles. The problems in two-wheel bicycle control problem are self-balancing, uncertain models, and the impact of noise. In the paper, to solve the self-balancing problem, we use the flywheel method according to the inverted pendulum principle. To overcome the effects of the uncertain model, the impact of noise, we designed the vehicle balance controller according to the robust control algorithm. However, robust controllers often have a high order, which affects the quality during real control. To simplify the robust controller, we propose the use of a model order reduction algorithm. The simulation and experimental results have proved the correctness of the solutions given in the paper.
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Kudo, Kazutoshi, Makoto Miyazaki, Hirofumi Sekiguchi, Hiroshi Kadota, Shinya Fujii, Akito Miura, Michiko Yoshie e Hiroki Nakata. "Neurophysiological and Dynamical Control Principles Underlying Variable and Stereotyped Movement Patterns During Motor Skill Acquisition". Journal of Advanced Computational Intelligence and Intelligent Informatics 15, n. 8 (20 ottobre 2011): 942–53. http://dx.doi.org/10.20965/jaciii.2011.p0942.
Testo completoAbstract (sommario):
While novices who are unfamiliar to a new motor skill typically show variable and unstable movements, highly skilled experts show a stable and accurate performance. These distinct differences in motor control between experts and novices have led researchers to hypothesize that neuromotor noise is reduced in the process of motor skill acquisition. On the other hand, it should be noted that novices’ movements have other characteristics; they are habituated and stereotyped. In this review, we discuss the principles governing spatiotemporal organization of movements in novices and experts while solving specific motor problems under varied conditions, by introducing experimental and theoretical studies that use neurophysiological techniques such as electromyography, functional magnetic resonance imaging, and transcranial magnetic stimulation, and mathematical models such as stochastic and dynamical models. On the basis of the findings from a variety of perceptual-motor skills (e.g., ballthrowing, badminton smash, long-distance running, piano and drum performance, street dance, a popular hand game of rock-paper-scissors, and temporal order judgement task), we argue that the novices’ characteristic movement patterns were organized under specific constraints and typical strategy, without which the variability would increase even more, while experts’ movements were organized with functional and compensatory variability that can drive out erroneous noise variability. We also showed that in a particular type of interlimb coordination, skilled and unskilled movement patterns could be seamlessly described as the time evolution of nonlinear and self-organized dynamical systems, suggesting that the dynamical systems approach is a major candidate for understanding the principle underlying organization of experts’ and novices’ movements.
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Alcorta García, María Aracelia, SANTOS MENDEZ DIAZ, JOSE ARMANDO SAENZ ESQUEDA, GERARDO MAXIMILIANO MENDEZ DIAZ, NORA ELIZONDO VILLAREAL e MIRNA MARICELA MARTINEZ FLORES. "EFFECT OF RISK-SENSITIVE STOCHASTIC OPTIMAL CONTROL WITH TRACKING IN AN EVAPORATOR". DYNA ENERGIA Y SOSTENIBILIDAD 11, n. 1 (4 gennaio 2022): [12 P]. http://dx.doi.org/10.6036/es10293.
Testo completoAbstract (sommario):
This work presents an application of the Risk-Sensitive (R-S) control with tracking applied to a stochastic nonlinear system which models the operation of an electronic expansion valve (EEV) in a conventional evaporator. A novel dynamical stochastic equation represents the mathematical model of the evaporator system. The R-S stochastic optimal problem consists of the design of an optimal control u(t) such that the state reaches setpoint values (SP) and minimizes the exponential quadratic cost function. The presence of disturbances and errors in the sensor measurements is represented by Gauss white noise in the state equation, with the coefficient v(e/(2?^2 )) . One novel characteristic in this proposal is that the coefficient of the control into the state equation contains the state term. The error and exponential quadratic cost function show that the R-S control has a better performance versus the classical PID (Proportional, Integral Derivative) control. Key Words: Optimal Risk-Sensitive control with tracking, modelling of the evaporator.
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Ławryńczuk, Maciej. "Efficient Nonlinear Predictive Control Based on Structured Neural Models". International Journal of Applied Mathematics and Computer Science 19, n. 2 (1 giugno 2009): 233–46. http://dx.doi.org/10.2478/v10006-009-0019-1.
Testo completoAbstract (sommario):
Efficient Nonlinear Predictive Control Based on Structured Neural ModelsThis paper describes structured neural models and a computationally efficient (suboptimal) nonlinear Model Predictive Control (MPC) algorithm based on such models. The structured neural model has the ability to make future predictions of the process without being used recursively. Thanks to the nature of the model, the prediction error is not propagated. This is particularly important in the case of noise and underparameterisation. Structured models have much better long-range prediction accuracy than the corresponding classical Nonlinear Auto Regressive with eXternal input (NARX) models. The described suboptimal MPC algorithm needs solving on-line only a quadratic programming problem. Nevertheless, it gives closed-loop control performance similar to that obtained in fully-fledged nonlinear MPC, which hinges on online nonconvex optimisation. In order to demonstrate the advantages of structured models as well as the accuracy of the suboptimal MPC algorithm, a polymerisation reactor is studied.
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Zelenov, M. S., e A. V. Chernyshev. "A Neural Network Mathematical Model Design Method for Estimating Compressed Air Volume Flow through a Proportional Valve". Proceedings of Higher Educational Institutions. Маchine Building, n. 6 (711) (giugno 2019): 41–49. http://dx.doi.org/10.18698/0536-1044-2019-6-41-49.
Testo completoAbstract (sommario):
The article describes an approach to neural network model design for simulating processes in shut-off and control pneumatic devices. This type of model can be used for a reasoned selection of components for multi-component pneumatic system configurations. As an example, the application of the proposed approach to the development of an artificial neural network to estimate the compressed air volume flow through a proportional valve is considered. The manufacturer’s catalog is used to obtain data samples. The structure of the proposed neural network model, data preprocessing for model configuration, and the selected learning algorithm are described. A computer program for compiling train and test data samples and the subsequent neural network training is developed. The results of measurements are simulated using additional, normally distributed noise with a standard deviation of 0.02. The results obtained using two mathematical models, the neural network model and the classical one, supplemented by empirical coefficients, are compared. The maximum deviation between the two models is less than 1.5 % of the maximum volume flow rate for a particular proportional valve model.
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Murari, Andrea, Michele Lungaroni, Riccardo Rossi, Luca Spolladore e Michela Gelfusa. "Complexity: Frontiers in Data-Driven Methods for Understanding, Prediction, and Control of Complex Systems 2022 on the Development of Information Theoretic Model Selection Criteria for the Analysis of Experimental Data". Complexity 2022 (24 agosto 2022): 1–12. http://dx.doi.org/10.1155/2022/9518303.
Testo completoAbstract (sommario):
It can be argued that the identification of sound mathematical models is the ultimate goal of any scientific endeavour. On the other hand, particularly in the investigation of complex systems and nonlinear phenomena, discriminating between alternative models can be a very challenging task. Quite sophisticated model selection criteria are available but their deployment in practice can be problematic. In this work, the Akaike Information Criterion is reformulated with the help of purely information theoretic quantities, namely, the Gibbs-Shannon entropy and the Mutual Information. Systematic numerical tests have proven the improved performances of the proposed upgrades, including increased robustness against noise and the presence of outliers. The same modifications can be implemented to rewrite also Bayesian statistical criteria, such as the Schwartz indicator, in terms of information-theoretic quantities, proving the generality of the approach and the validity of the underlying assumptions.
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Escobar, Jesica, e Alexander Poznyak. "Parametric identification of ARMAX models with unknown forming filters". IMA Journal of Mathematical Control and Information 39, n. 1 (25 dicembre 2021): 171–84. http://dx.doi.org/10.1093/imamci/dnab042.
Testo completoAbstract (sommario):
Abstract In this paper, we present the parameter estimation algorithm for the class of an extended ARMAX model containing a ‘coloured’ noise sequence, formed by an unknown finite-dimensional linear filter. This algorithm represents the extended versions of residual whitening method and least squares method, working in parallel, to identify the extended parameters obtained after the suggested linear model transformation. The strong consistency of the suggested method (convergence with probability one of the obtained extended parameters to their exact values) is proven. A good performance of the proposed method is illustrated by a numerical example with all polynomials containing unknown parameters.
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Naranjo-Hernández, David, Javier Reina-Tosina e Mart Min. "Fundamentals, Recent Advances, and Future Challenges in Bioimpedance Devices for Healthcare Applications". Journal of Sensors 2019 (15 luglio 2019): 1–42. http://dx.doi.org/10.1155/2019/9210258.
Testo completoAbstract (sommario):
This work develops a thorough review of bioimpedance systems for healthcare applications. The basis and fundamentals of bioimpedance measurements are described covering issues ranging from the hardware diagrams to the configurations and designs of the electrodes and from the mathematical models that describe the frequency behavior of the bioimpedance to the sources of noise and artifacts. Bioimpedance applications such as body composition assessment, impedance cardiography (ICG), transthoracic impedance pneumography, electrical impedance tomography (EIT), and skin conductance are described and analyzed. A breakdown of recent advances and future challenges of bioimpedance is also performed, addressing topics such as transducers for biosensors and Lab-on-Chip technology, measurements in implantable systems, characterization of new parameters and substances, and novel bioimpedance applications.
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Chow, Winston C., e Paul W. Schumacher. "Using Fractional Gaussian Noise Models in Orbit Determination". Journal of Guidance, Control, and Dynamics 27, n. 2 (marzo 2004): 319. http://dx.doi.org/10.2514/1.5989.
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Chow, Winston C., e Paul W. Schumacher. "Using Fractional Gaussian Noise Models in Orbit Determination". Journal of Guidance, Control, and Dynamics 26, n. 4 (luglio 2003): 593–607. http://dx.doi.org/10.2514/2.5087.
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