The paper deals with a model for water freezing in a deformable elastoplastic container. The mathematical problem consists of a system of one parabolic equation for temperature, one integrodifferential equation with a hysteresis operator for local volume increment, and one differential inclusion for the water content. The problem is shown to admit a unique global uniformly bounded weak solution.
We present observational results from which we can determine azimuthal currents flowing across the magnetic field. Simple relations between the vertical current densities and the inclinations of the field are used to separate from each other the field-aligned component and the azimuthal component of current density. For
a relatively isolated flux bundle we obtain a total azimuthal current density of (7.8 ± 3,6)' 10-2 Am-2 and an azimuthal current of
(6,5 ± 3.0)‘ 10^^ A. The density of the Lorentz force acting amounts up to 1,1 -10-3 Nm-3.
We investigated the structure of magnetic field and vertical electric currents in two active regions. Electric currents were calculated from the observations of transverse magnetic field. There exist two systems of vertical electric currents in an active region; a system of local currents and global one. The globál current is about 2.10^^ A. In the leading part of the active region it is directed upward, and in the tail - downward and is plausibly determined by the global rotation of plasma. The flare activity is dosely connected with the value and direction of both local and globál currents: the flares tend to appear in places with upward currents. The sensitivity of Hα„ emission to the sign of current implies that the charged particles accelerated in the upper parts of magnetic loops are responsible for these formations.
Several topologies of electrical machines can be used to meet requirements for application in a hybrid electric vehicle. This paper describes process of an electric motor-generator selection, considering electromagnetic, thermal and basic control design. The requested electrical machine must develop 45 kW in continuous operation at 1300 rpm with field weakening capability up to 2500 rpm. Both radial and axial flux topologies are considered as potential candidates. A family of axial flux machines is represented by a permanent magnet, single stator and two rotor plates topology. An induction machine was included into the selection process, alongside an embedded and inset permanent magnet synchronous machine, all of the radial type machines. and Obsahuje seznam literatury
Impaired wakefulness in machine operators poses a danger not only to themselves but often to the public at large as well. While on duty, such persons are expected to be continuously, i.e., without interruption, on the alert. For that purpose, we designed and carried out an experimental model of continuous vigilance monitoring using electroencephalography (EEG) and reaction time measured as the latency of the probanďs reaction to sound stimulus. If constructed, the set together with other logical elements and an alarm systém can be used for an autornatic detection of vigilance and, possibly, also of arousal stimuli in cases of micro-sleep.
Electromechanical system with one degree of freedom in mechanical oscillating part and with other degree in rotation a electrical subsystems is investigated by means of numerical solution of derived equations in dimensionless form. The most important nonlinearities are impacts of the main body on the stiff but deformable stop. Other nonlinear effects are introduced into system by the force transformation from unbalance exciter with limited power into the oscillating subsystem and also by nonlinear magnetic flux in the driving electromotor. Presented numerical simulation was focused on the study of the influence of exciting unbalance level on the time histories of oscillations and on phase trajectories. The various responses were shown and discussed in examples. and Obsahuje seznam literatury