A quantitative measure for degree of automation and its relation to system performance and mental load

In this paper we quantitatively model degree of automation (DofA) in supervisory control as a function of the number and nature of tasks to be performed by the operator and automation. This model uses a task weighting scheme in which weighting factors are obtained from task demand load, task mental load, and task effect on system performance. The computation of DofA is demonstrated using an experimental system. Based on controlled experiments using operators, analyses of the task effect on system performance, the prediction and assessment of task demand load, and the prediction of mental load were performed. Each experiment had a different DofA. The effect of a change in DofA on system performance and mental load was investigated. It was found that system performance became less sensitive to changes in DofA at higher levels of DofA. The experimental data showed that when the operator controlled a partly automated system, perceived mental load could be predicted from the task mental load for each task component, as calculated by analyzing a situation in which all tasks were manually controlled. Actual or potential applications of this research include a methodology to balance and optimize the automation of complex industrial systems.     

Determination of InN/Diamond Heterojunction Band Offset by X-ray Photoelectron Spectroscopy

Diamond is not only a free standing highly transparent window but also a promising carrier confinement layer for InN based devices, yet little is known of the band offsets in InN/diamond system. X-ray photoelectron spectroscopy was used to measure the energy discontinuity in the valence band offset (VBO) of InN/diamond heterostructure. The value of VBO was determined to be 0.39 ± 0.08 eV and a type-I heterojunction with a conduction band offset (CBO) of 4.42 ± 0.08 eV was obtained. The accurate determination of VBO and CBO is important for the application of III-N alloys based electronic devices.     

Formation of WO<Subscript> <Emphasis Type="Italic">x</Emphasis> </Subscript>–ZrO<Subscript>2</Subscript> isomerization catalysts from anion-modified zirconium hydroxide

The formation of zirconia-based isomerization catalysts during thermal conversions of hydroxide modified with different amounts of tungstate groups has been studied by differential scanning calorimetry and X-ray diffraction analysis. The mechanism of formation of tungstated zirconia from a hydroxide precursor has been formulated.     

Temperature delocalization of charge carriers in semiconductor lasers

The temperature dependences of emission characteristics are investigated for laser diodes based on asymmetric separate-confinement heterostructures with a broadened waveguide. It is established that an increase in the charge-carrier concentration in the waveguide layer is the basic mechanism of saturation in the light-current characteristic with increasing temperature in the CW mode. It is experimentally shown that the temperature delocalization of charge carriers leads to increasing internal optical losses and decreasing external differential quantum efficiency. It is shown that the degree of delocalization of charge carriers depends on the charge-carrier temperature distribution, the threshold concentration, and the quantum-well depth. The effect of thickness and energy depth of the quantum well on the temperature sensitivity of the threshold current and output optical power is considered.     

Methods of analysis of geophysical data during increased solar activity

This work is directed at creation of methods of study of the processes in the ionospheric–magnetospheric system during increased solar and geomagnetic activity. Method of modeling and analysis of the parameters of the ionosphere, which allows prediction of the data and identification of the anomalies during the ionospheric disturbances, are given. Computational solutions for determination and estimation of the geomagnetic disturbances are described. Method of determination of the anomalous changes in the time course of cosmic rays, which allows qualitative estimations of the moments of their origination, duration, and intensity, is suggested.On the basis of the methods elaborated, the data on the periods of strong and moderate magnetic storms are complexly analyzed. Sharp oscillations in the electron density of the ionosphere with positive and negative phases, which originate in the regions analyzed during an increase in geomagnetic activity, are distinguished. Positive phases of the ionospheric disturbances from several hours to one and a half days long were formed before the beginning of the magnetic storms. At the moments of the increase in the electron concentration, a local increase is observed in the level of cosmic rays (several hours before the magnetic storms) that supported the solar nature of these effects. During the strongest geomagnetic disturbances, the electron concentration in the ionosphere decreased significantly and led to prolonged negative phases of ionospheric storms, which coincided with the decrease in the level of cosmic rays (a Forbush decrease).     

MOCVD GaInAsP/GaInP/AlGaInP laser structures emitting at 780 nm

Metal-organic chemical vapor deposition (MOCVD) was used to form laser heterostructures in the system of GaInAsP/GaInP/AlGaInP solid solutions. The design of the laser structure was chosen on the basis of the calculated band offsets at the heteroboundaries in the active region of the waveguide. A maximal optical power of 320 mW is attained at the output of the mesa-stripe diode laser with a stripe width of W=5 µm in continuous-wave mode at 780 nm.