Wyniki wyszukiwania dla: A Steimel
artykuł
Objective
Interictal epileptiform discharges (IEDs) were shown to be associated with cognitive impairment in persons with epilepsy. Previous studies indicated that IED rate, location, timing, and spatial relation to the seizure onset zone could predict an IED's impact on memory encoding and retrieval if they occurred in lateral temporal, mesial temporal, or parietal regions. In this study, we explore...
artykuł
Acta Neurologica Scandinavica > 144 > 2 > 192 - 201
Objectives
To study the effects of auditory stimuli on interictal epileptiform discharge (IED) rates evident with intracranial monitoring.
Materials and methods
Eight subjects undergoing intracranial EEG monitoring for refractory epilepsy participated in this study. Auditory stimuli consisted of a 40‐Hz tone, a 440‐Hz tone modulated by a 40‐Hz sinusoid, Mozart's Sonata for Two Pianos in D Major...
artykuł
Objective
This study was undertaken to evaluate the influence that subject‐specific factors have on intracranial interictal epileptiform discharge (IED) rates in persons with refractory epilepsy.
Methods
One hundred fifty subjects with intracranial electrodes performed multiple sessions of a free recall memory task; this standardized task controlled for subject attention levels. We utilized a dominance...
rozdział
Sowohl in Kap. 13 mit der Regelung der Asynchronmaschine, als auch in Kap. 16 mit der Regelung der Synchronmaschine und ihrer Varianten werden mehrfach in den Signalflußplänen Umrichter mit unterlagerter Statorstromregelung vorausgesetzt. Im Falle von I-Umrichtern geschieht dies unmittelbar durch Regelung des Zwischenkreisstroms (Amplitude) und Vorgabe eines entsprechenden Pulsmusters (Amplitude und...
rozdział
High-voltage DC (HVDC) transmission lines offer highly efficient transport of electric energy. If applied to comparatively weak grids, self-commutated converters are the proper choice, because they allow stabilizing the grid in case of faults by injecting reactive power. At high voltages of e.g. 400 kV modular multilevel converters (MMC) fulfill all requirements. The first task to master is getting...
rozdział
MedPower 2014 > 1 - 5
High-voltage DC (HVDC) transmission lines offer highly efficient transport of electric energy. If applied to comparatively weak grids, self-commutated converters are the proper choice, because they allow stabilizing the grid in case of faults by injecting reactive power. However, proper control methods have to be applied - normal operation and the reaction to various fault conditions need careful...
rozdział
MedPower 2014 > 1 - 4
High-voltage DC (HVDC) transmission lines offer highly efficient transport of electric energy. If applied to comparatively weak grids, self-commutated converters are the proper choice, because they allow stabilizing the grid in case of faults by injecting reactive power. However, proper control methods have to be applied - normal operation and the reaction to various fault conditions need careful...
rozdział
Energy efficient and robust operation of pumps and hydraulic systems can save a large amount of energy. A system-wide optimization, including inverter and machine control and directly taking the pump and the hydraulic system into account, is the basis for optimal results. A verification of such concepts is difficult and expensive, because pump and connected hydraulic system have to be available. This...
rozdział
This paper presents a general model of the Doubly-Fed Induction Generator (DFIG). The model includes the influence of slotting on the harmonics of stator- and rotor currents. Most squirrel-cage induction machines can be described well based on a fundamental-wave model of winding distribution. In case of DFIG the slotting and the non-ideal structure of the windings in stator and rotor cause considerable...
rozdział
Multilevel converters are indispensable for ship propulsion motors. The Modular Multilevel Converter allows a nearly unlimited cascading of voltage levels at the same complexity in construction. This allows to minimise unacceptable motor terminal overvoltages and motor insulation stress. A current-oriented control is mandatory for this drive control, because the Modular Multilevel Converter is not...
rozdział
The choice of the converter topology feeding the electric machine of the main propulsion of electric ships plays an important role for the feasibility of an all electric ship concept. The medium-voltage machine has to be speed-adjustable in the whole speed range at high power and maybe it is connected by a long cable to the inverter. In other high power industrial drives with long cable length, e...
rozdział
A novel state-control approach for induction machines in the converter-fixed reference frame is presented. The magnetising currents and the stator currents of the machine are the control signals. They allow highest torque dynamics and, at the same time, over-current prevention. In this paper, the key ideas of the new concept are presented. The capability of the approach is demonstrated by simulation...
rozdział
Commercially available IGBT converters are usually designed in a cost-efficient way. They can readily be applied to the application they are designed for. However, they are rather limited if unusual requirements, typical for research and laboratory use, have to be met. With regard to the machine test bench capabilities of the institute, a universally applicable back-to-back IGBT converter has been...
rozdział
Permanent-Magnet Synchronous Machines (PMSM) with their high power density are attractive for all kinds of propulsion systems. Typically, these applications demand high torque dynamics, caused by additional demands like cancellation of drive-train torsional oscillations, slip-slide control and electronic stability control. Indirect Stator-Quantities Control (ISC) has proven its excellent torque dynamics...
rozdział
For medium-voltage drives multilevel converters are advantageous to reduce the insulation stress of the windings of the machine. State of the art are multilevel converters as Diode Clamped Converter, Imbricated Cell Converter or Stacked H-Bridge Converter with a low number of levels limited by the restrictions in practical construction. The Modular Multilevel Converter is not limited in the number...
rozdział
This paper presents a general modeling and a novel control method of the doubly-fed induction generator (DFIG). Based on the Indirect Stator-quantities Control (ISC) scheme for asynchronous machines, the principle of the rotor-flux-based control of the DFIG is applied. Using this, torque control or decoupled active and reactive power control achieves very high dynamics. Limitations are given only...
rozdział
Complex control procedures have to be developed for new drive control schemes to improve especially the dynamic behaviour of drives for safety-relevant features like slip-slide control or electronic stability programs. Today the development of the control algorithm is usually completely performed in software-based simulation tools, allowing a fast analysis of the system and of the control behaviour...
rozdział
The working principle of the matrix converter has been described by many authors in various ways. Especially, the introduction of the virtual DC link concept was one of the most important milestones in the matrix converter theory. However, the mathematical description is not symmetrical in this case. That is why a new approach presented in this article strives to symmetrize the matrix converter voltage...
rozdział
The control of power-electronic laboratory test benches for academic use and for industrial research and development demands a real-time control system with high flexibility and reliability at low cost. Personal computers are an ideal basis for this kind of real-time control systems because of their high processing power at very low cost and their expandability by additional interface cards. An additional...
rozdział
High availability is a major concern in naval drive applications. In consequence, multiphase machines, e.g. IM with double-star stator windings, are used. To guarantee the high availability, comprehensive scenario-based analyses of the machine-control behaviour in case of faults have to be performed. Asymmetrical faults - which are a practical issue - are not featured by any simplified single-phase...
