The linear mechanical model for hand-arm system

The paper presents a study regarding the linear mechanical models corresponding to hand-arm system. These models was simplified unused the joint in wrist, elbow and shoulder. Also, for these mechanical models effectuated the equations system that would integrate, it obtained the solutions (displacements and velocities) finally. (© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

On Optimization of the Full Radiative Heat Transfer System

Solving the full radiative heat transfer equation, moderately discretized in space, time, frequency and direction, results in a tremendously huge system of equations. A common approach to avoid this problem is to use moment methods neglecting the directional dependence on radiation. Our approach, however, is to solve the full radiative heat transfer system with all dependencies and to optimize the heat distribution and the radiative flux, respectively, for a desired temperature function or desired radiative flux function. (© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Input-output behaviour of a stochastic Galerkin method for a low pass filter

We apply the stochastic Galerkin method to a linear dynamical system, which includes random variables to quantify uncertainties in physical parameters. The input-output behaviour of the stochastic Galerkin system is described by a transfer function in the frequency domain. The importance of each output component can be estimated by Hardy norms. We investigate a Hardy norm in the case of a linear dynamical system modelling the electric circuit of a low pass filter. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Black-box Identification of Transfer Functions: Asymptotic Results for Increasing Model Order and Data Records

The problem of estimating the transfer function of a linearstochastic system is considered. The transfer function is parametrizedas a black box and no given order is chosen a priori. This meansthat the model order may increase to infinity when the numberof observed data tends to infinity. The consistency and convergenceproperties of the resulting transfer-function estimates areinvestigated. In an earlier paper results were given for models,parametrized as finite impulse responses. In this article theseresults are extended to more general parametrizations and togeneral noise models. A main result is that the variance ofthe transfer-function estimate at a certain frequency is asymptoticallygiven by the noise-to-signal ratio at that frequency, multipliedby the ratio of the model order to the number of data points.     

Vibrating Portable Machine-Tools Acting on Human Operator

This paper will be a short presentation of the specialized literature and international standards about the importance of vibration action of portable machine tools on human body and particularly on the hand-arm system. Exposure to harmful vibrations can lead to health problems and disorders, especially in the upper joints and dorsal region of the human body. A detailed understanding of the undesirable effects of vibration on the human body is essential to achieve administrative and technical prevention. In modern times, vibration studies become more frequent, decisive for the many machines, vehicles and construction. (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Existence and Dimension Properties of a Global <Emphasis Type="Italic">B</Emphasis>-Pullback Attractor for a Cocycle Generated by a Discrete Control System

We consider cocycles on finite-dimensional manifolds generated by discrete-time control systems. Frequency conditions for the existence of a global B-pullback attractor for such cocycles considered over a general base system on a metric space are given. Upper bounds for the Hausdorff dimension of the global B-pullback attractor of a discrete cocycle are obtained using the transfer function of the linear part of the cocycle and the discrete Kalman–Yakubovich–Popov frequency theorem.     

Frequency–energy plots of steady-state solutions for forced and damped systems,and vibration isolation by nonlinear mode localization

We study the structure of the periodic steady-state solutions of forced and damped strongly nonlinear coupled oscillators in the frequency–energy domain by constructing forced and damped frequency – energy plots (FEPs). Specifically, we analyze the steady periodic responses of a two degree-of-freedom system consisting of a grounded forced linear damped oscillator weakly coupled to a strongly nonlinear attachment under condition of 1:1 resonance. By performing complexification/averaging analysis we develop analytical approximations for strongly nonlinear steady-state responses. As an application, we examine vibration isolation of a harmonically forced linear oscillator by transferring and confining the steady-state vibration energy to the weakly coupled strongly nonlinear attachment, thereby drastically reducing its steady-state response. By comparing the nonlinear steady-state response of the linear oscillator to its corresponding frequency response function in the absence of a nonlinear attachment we demonstrate the efficacy of drastic vibration reduction through steady-state nonlinear targeted energy transfer. Hence, our study has practical implications for the effective passive vibration isolation of forced oscillators.     

Outgoing Cuntz scattering system for a coisometric lifting and transfer function

We study a coisometry that intertwines Popescu’s presentations of minimal isometric dilations of a given operator tuple and of a coisometric lifting of the tuple. Using this we develop an outgoing Cuntz scattering system which gives rise to an input–output formalism. A transfer function is introduced for the system. We also compare the transfer function and the characteristic function for the associated lifting.     

Synthetic Impedance Circuits in Semi-Passive Vibration Control with Piezo-Ceramics - Efficiency and Limitations

Electrical circuits that represent complex impedance connected to the plates of piezo element affect the frequency response function of compound electromechanical systems. The external network consisting of inductance results in absorbing a certain frequency of vibrations. The performance can significantly be increased using negative capacitance. All the negative impedance elements are achievable via semi-passive way with the use of an electronic gyrator realized by operational amplifiers that require power supply. Its performance is limited due to the maximum voltage operational amplifiers can produce. The higher excitation forces require higher output voltages of amplifiers. The aim of the paper is to present the relation between the required voltage on synthetic impedance and force excitation in 1DOF vibrating system regarding parameters of piezo element and mechanical system for absorbing case. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

A construction of unitary linear systems

A construction is made of a unitary linear system whose transfer function is a given power seriesB(z) with operator coefficients such that multiplication byB(z) is an everywhere defined transformation in the space of square summable power series with vector coefficients. A condition is also given for the existence of an observable linear system with such a transfer function. For both constructions properties of the spaces are given which imply essential uniqueness of linear systems with given transfer functions. A canonical conjugate-isometric linear system is uniquely determined by its transfer function whenever the state space is a Pontryagin space.     

Asymptotic properties of the solutions of the equations of motion of gyroscopic systems

The motion of mechanical systems acted upon by gyroscopic and positional forces characterized by a large parameter in the corresponding equations of motion is considered. Periodic solutions of such equations were investigated earlier in [1, 2]. It is proved below that solutions of these equations exist, defined in an interval the length of which is a monotonically increasing unbounded function of the large parameter, and which transfer into the solutions of the corresponding degenerate systems as the large parameter approaches infinity. This function can be specified in more detail if additional assumptions are made regarding the properties of the system and the nature of the forces acting on it.     

MIMO capacity for deterministic channel models: sublinear growth

This is the second paper by the authors in a series concerned with the development of a deterministic model for the transfer matrix of a MIMO system. In our previous paper, we started from the Maxwell equations and described the generic structure of such a deterministic transfer matrix. In the current paper, we apply those results in order to study the (Shannon‐Foschini) capacity behavior of a MIMO system as a function of the deterministic spread function of the environment and the number of transmitting and receiving antennas. The antennas are assumed to fill in a given fixed volume. Under some generic assumptions, we prove that the capacity grows much more slowly than linearly with the number of antennas. These results reinforce previous heuristic results obtained from statistical models of the transfer matrix, which also predict a sublinear behavior. Copyright © 2012 John Wiley & Sons, Ltd.     

Frequency and Time Domain Analysis of an Aeroelastic Wing Multiple Component Structure

A multiple component structure consisting of two Euler-Bernoulli beams connected to a rigid mass is used to model the heave dynamics of a wing micro air vehicle. In the time domain, the attainment of a C ₀-semigroup in the context of sesquilinear forms is demonstrated. In addition, the closed loop system is demonstrated to generate an exponentially stable C ₀-semigroup. In the frequency domain, the infinite dimensional transfer function is determined and used to examine several properties of the system. Finally, an optimal control is used to morph the wings to a desired shape, and simulation results are demonstrated.     

Controller design using closed-loop transfer function

A method is proposed for finding the controller transfer function in a one-loop control system that ensures the desired location of the roots of the characteristic polynomial of the closed-loop system. The problem has multiple solutions and there is a whole class of controllers with such a property. The procedure to find the controller transfer function is reduced to algebraic division of polynomials and produces the dependence of the closed-loop transfer function on the roots of the characteristic polynomial of the closed-loop system. Translated from Algoritmy Upravleniya i Identifikatsii, pp. 85–93, 1997.     

普适双变量随机气候模式的研究

该文对海气耦合双变量随机气候模式进行了系统研究，研究结果表明：（1）无论是考虑只有大气子系统的随机作用还是同时考虑大气子系统和海洋子系统的双扰动，对给定的扰动频率，海气气候系统对大气的扰动作用相当于一个十分简单的线性放大器；对于不同的扰动频率，在能量上海温的变化将随大气的扰动做4次幂的非线性响应;（2）若同时考虑大气子系统和海洋子系统的随机扰动，在满足细致平衡条件下可以求出系统定态的概率分布。否则，只有当扰动为弱噪声时，才能用级数展开法近似求出系统的概率分布。     

Reduced order fully coupled structural–acoustic analysis via implicit moment matching

A reduced order model is developed for low frequency, undamped, fully coupled structural–acoustic analysis of interior cavities backed by flexible structural systems. The reduced order model is obtained by applying a projection of the coupled system matrices, from a higher dimensional to a lower dimensional subspace, whilst preserving essential properties of the coupled system. The basis vectors for projection are computed efficiently using the Arnoldi algorithm, which generates an orthogonal basis for the Krylov Subspace containing moments of the original system. The key idea of constructing a reduced order model via Krylov Subspaces is to remove the uncontrollable, unobservable and weakly controllable, observable parts without affecting the transfer function of the coupled system. Three computational test cases are analyzed, and the computational gains and the accuracy compared with the direct inversion method in ANSYS.     

Boundary control and canonical realizations of a two-velocity dynamical system

The paper is devoted to the problems of controllability and realization for dynamical systems with various types of interacting waves that propagate with different velocities. One-velocity and a two-velocity dynamical systems are significantly different from the physical point of view. One can reconstruct a one-velocity system by its transfer function. For a two-velocity system a unique reconstruction is impossible. A procedure is proposed that allows us to construct by a transfer function of a two-velocity system a one-velocity system (a model) with the same transfer function. We give a “dynamical” interpretation for the triangular Krein factorization and for the corresponding construction of a triangular integral. For a transformation operator that connects a two-velocity system and its one-velocity model, a representation is given in terms of projectors on the accessible sets. Bibliography: 7 titles. Translated fromZapiski Nauchnykh Seminarov POMI, Vol. 222, 1994, pp. 18–44.