This article presents a design of model of the medium access control (MAC) of a sub-layer of a Controller Area Network (CAN) protocol (CAN is the most widely used in-vehicle network). The model is created via hierarchical Coloured Petri Nets. For better clarity and comprehension, the wide created model is divided into submodules.
An application CPN Tools, developed by the CPN group at the University of Aarhus (Denmark), is used as a modelling tool. This model expresses the whole CAN's fault confinement mechanisms and the other functions of MAC sub-layer such as data encapsulation, frame coding (stuffing/de-stuffing), medium access management and acknowledgement. Functionality of the originally created model was tested by a series of ad hoc simulations in the model environment. The assets of the model mentioned before are discussed at the end of the article.
The article offers a new view on the organization of the processes of human perception. It introduces the concept of inclusive sensory characteristic, which is a response of a given perceptual level to those features or characteristics of an underlying level whose spatial organization or specific temporal succession constitutes an adaptively meaningful entity. The sequence of inclusive characteristics forms a hierarchy: from features to the highest inclusive characteristics which bind sensory data into unified images and scenes. The highest inclusive characteristic is neither an image nor a scene, but a unique scheme of combination of underlying-level objects, which produces the image or the scene.
Specific patterns of electric activity, which map inclusive characteristics, are relayed by feedbacks from upper to lower neuronal levels. This forms a cascade of top-down transfer of excitation, which stimulates those neuronal populations whose signals correspond to the highest inclusive characteristic of a given act of perception. Stimulation from above reduces the time of response of selected neurons at underlying levels to simultaneously arriving spikes to milliseconds. As a result, neuronal populations at the underlying levels, which are involved in a given act of perception, become, for a short time, coincidence detectors. The hierarchically arranged set of neuronal ensembles of coincidence detectors forms a fast sensory pathway, single and unique for each act of perception.
We describe behavior of the air-coal mixture using the Navier-Stokes equations for gas and particle phases, accompanied by a turbulence model. The undergoing chemical reactions are described by the Arrhenian kinetics (reaction rate proportional to exp(−ERT), where T is temperature). We also consider the heat transfer via conduction and radiation. Moreover we use improved turbulence-chemistry interactions for reaction terms. The system of PDEs is discretized using the finite volume method (FVM) and an advection upstream splitting method as the Riemann solver. The resulting ODEs are solved using the 4th-order Runge-Kutta method. Sample simulation results for typical power production levels are presented.
We investigated how selected electromorphological parameters of myelinated axons influence the preservation of interspike intervals when the propagation of action potentials is corrupted by axonal intrinsic noise. Hereby we tried to determine how the intrinsic axonal noise influences the performance of axons serving as carriers for temporal coding. The strategy of this coding supposes that interspike intervals presented to higher order neurons would minimally be deprived of information included in interspike intervals at the axonal initial segment. Our experiments were conducted using a computer model of the myelinated axon constructed in a software environment GENESIS (GEneral NEural SImulation System). We varied the axonal diameter, myelin sheath thickness, axonal length, stimulation current and channel distribution to determine how these parameters influence the role of noise in spike propagation and hence in preserving the interspike intervals. Our results, expressed as the standard deviation of spike travel times, showed that by stimulating the axons with regular rectangular pulses the interspike intervals were preserved with a microsecond accuracy. Stimulating the axons with pulses imitating postsynaptic currents, greater changes of interspike intervals were found, but the influence of implemented noise on the jitter of interspike intervals was approximately the same., E. Kuriščák, S. Trojan, Z. Wünsch., and Obsahuje bibliografii
The pattern-reversal (P-VEPs) and the motion-onset (M-VEPs) of visual evoked potentials were modeled by means of three damped oscillators (O1, O2, O3) of identical construction. The O1, assumed to simulate the response of primary visual area (V1), was driven by the firing density of the lateral geniculate nuclei. O1 contributed mainly to the N75 and P100 peaks of the P-VEPs. The O2, driven by the O1 output, mimics the activity of V2, V3a, and MT. It contributed to the negative peak N145 of the P-VEPs or to the N160 in the M-VEPs. The O3 was suggested to model late slow processes probably of an attentive origin. The model parameters were set by optimization to follow the P-VEPs and M-VEPs obtained as a grand average of four young volunteers (PZ - A2 lead). The evoked potentials were described with normalized root mean square error lower than 13 %., J. Kremláček, M. Kuba, J. Holčík., and Obsahuje bibliografii
The solution of the problem of external gravitational field simulation by means of the potential of a system reciprocal point masses is described. The problem is considered as that of nonlinear programming with Tykhonov´s regularization.
The model of 85 reciprocal point masses (eighty five), which represents the LAGEOS orbit on 5-days arcs with the same accuracy on GEM-L2, is constructed on the basis of the full set of GEM-L2 harmonics. The usage of conjugated point-mass model instead of GEM-L2 harmonics leads to a reduction of computer time by 50 %.
This paper provides a novel method to model lead crowned spur gears. The teeth of circular and involute crowned external spur gears are modeled for the same crowning magnitude. Based on the theory of gearing, mathematical model of tooth generation and meshing are presented. Effect of major performance characteristics of uncrowned spur gear teeth are studied at the pitch point and compared with longitudinally modified spur gear teeth. The results of three dimensional FEM analyses from ANSYS are presented. Contact elllipse patterns and other contact parameters are also studied to investigate the crowning effects. and Obsahuje seznam literatury