Implementation of rapid microwave sintering using a 24 GHz gyrotron system.

Rapid microwave sintering of different oxide ceramics with heating rates up to 300 °C/min and zero hold time has been implemented using a 24 GHz gyrotron-based system for high-temperature processing of materials. The design of the system, principle of operation, and process control are described. Particular attention is given to the design of thermal insulation assemblies and the implementation of temperature measurement in an environment with intense electromagnetic fields. A description of an optical system for dilatometry and temperature measurement is presented. The interrelation between the automatically regulated output power of the gyrotron and the microwave power absorbed volumetrically in the sample is analyzed on the basis of energy balance considerations. The analysis is illustrated by considering examples of rapid sintering processes with ZnO-based and BaTiO3 ceramic samples making use of direct and susceptor-assisted microwave heating. It is demonstrated that an increase in the volumetrically absorbed power leads to the development of a controlled thermal instability, which results in a lower temperature of the densification onset.

Anomalous magneto-resistance of Ni-nanowire/Nb hybrid system.

We examine the influence of superconductivity on the magneto-transport properties of a ferromagnetic Ni nanowire connected to Nb electrodes. We show experimentally and confirm theoretically that the Nb/Ni interface plays an essential role in the electron transport through the device. Just below the superconducting transition, a strong inverse proximity effect from the nanowire suppresses superconducting correlations at Nb/Ni interfaces, resulting in a conventional anisotropic magneto-resistive response. At lower temperatures however, the Nb electrodes operate as superconducting shunts. As the result, the magneto-resistance exhibits a strongly growing hysteretic behavior accompanied by a series of saw-like jumps. The latter are associated with the penetration/escape of individual Abrikosov vortices that influence non-equilibrium processes at the Nb/Ni interface. These effects should be taken into account when designing superconducting quantum nano-hybrids involving ferromagnetic nanowires.

[Effect of alcohol intake on the ability to pilot aircraft]. / Vliianie priema alkogolia na vozmozhnost' pilotirovaniia samoleta.

During the initial 4 hours after alcohol intake at a dose of 1.9 g/kg aircraft operators displayed disturbances in the psychic processes and functions responsible for each (from information reception and processing up to decision-making and building-up the controlling actions) structural elements in their activity resulting in considerable limitation or a complete failure to pilot aircraft. Main disorders included inability to correctly analyse flight situation and loss of skills to automatically control simulator, a sudden depletion of psychophysiological reserves and deterioration of operator's reliability. Less elaborated professional skills appear to be the most vulnerable.

[The possibility of using cerebral evoked potentials in the diagnosis of fatigue in flight personnel]. / Vozmozhnost' ispol'zovaniia vyzvannykh potentsialov golovnogo mozga v diagnostike utomleniia letnogo sostava.

The applicability of brain evoked potentials to the detection of pilot fatigue was investigated in simulation studies. During landing that followed a 10-hour flight acoustic evoked potentials (AEP) to sound stimuli (clicks), that were indifferent and irrelevant for pilots in terms of their professional work, were recorded. In averaged AEPs, the components N1 and P2 (90 and 175 ms latent periods, respectively) showed highest stability. In response to stimulation the NIP2 (peak-to-peak) amplitude decreased significantly (on the average by 24.5%) when compared to the preflight level. This can be accounted for by the fact that in the state of fatigue man's capability to perceive and process information declines. From the physiological point of view, this change can be associated with the system that supports piloting functions on the dominant basis as well as with response inhibition to an irrelevant signal based on the negative induction mechanism. This finds expression in a lower amplitude of the major components of averaged AEPs.