Effect of cognitive load on speech prosody in aviation: Evidence from military simulator flights

Mental overload directly affects safety in aviation and needs to be alleviated. Speech recordings are obtained non-invasively and as such are feasible for monitoring cognitive load. We recorded speech of 13 military pilots while they were performing a simulator task. Three types of cognitive load (load on situation awareness, information processing and decision making) were rated by a flight instructor separately for each flight phase and participant. As a function of increased cognitive load, the mean utterance-level fundamental frequency (F0) increased, on average, by 7 Hz and the mean vocal intensity increased by 1 dB. In the most intensive simulator flight phases, mean F0 increased by 12 Hz and mean intensity, by 1.5 dB. At the same time, the mean F0 range decreased by 5 Hz, on average. Our results showed that prosodic features of speech can be used to monitor speaker state and support pilot training in a simulator environment.     

Influence of the polymerization conditions on the impact properties of metallocene‐catalyzed copolymers of ethylene and aryl‐substituted norbornenes with low exo/endo ratios

When testing copolymers of ethylene and aryl‐substituted norbornenes with the Charpy impact method it was found that under certain polymerization conditions their impact properties increased with increasing polymerization time. It was also found that this improvement on impact properties was due to increasing exo/endo ratios of the incorporated aryl‐substituted norbornene comonomers. This effect is important because impact‐resistant copolymers can be made using aryl‐substituted norbornene comonomers with low exo/endo ratios, which are more easily synthesized and purified. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1108–1117, 2000     

Copolymerization of propene with phenylnorbornene using ansa‐bridged metallocene catalysts

Propene was copolymerized with phenylnorbornene using methylaluminumoxane (MAO)‐activated metallocene dichlorides exhibiting different symmetry: C₂‐Symmetric rac‐ethylenebis(1‐ indenyl)zirconium dichloride ( 1 ), rac‐ dimethylsilylbis(1‐indenyl)zirconium dichloride ( 2 ), rac‐ethylenebis(1‐indenyl)hafnium dichloride ( 6 ), C_s‐symmetric isopropylidene(cyclopentadienyl‐9‐fluorenyl)zirconium dichloride ( 3 ), meso‐ethylenebis(1‐indenyl)zirconium dichloride ( 4 ), and C₁‐symmetric ethylene(1‐ fluorenyl‐1‐phenyl‐2‐indenyl)zirconium dichloride ( 5 ) were chosen to evaluate the influence of the symmetry in copolymerization reactions. Experiments were done as batch polymerizations to produce homogeneous copolymers. By this setup, blend formation was avoided. The copolymers were characterized by NMR, GPC, and DSC. Catalysts 1 and 2 were the most active to copolymerize random, amorphous, copolymers with good activity. C_s‐symmetric, 3 , showed decreased activity compared with 1 and 2 and produced a bimodal copolymer. Catalyst 4 showed even lower activity than that of 3 . The activity of the hafnium complex 6 , which produced a semicrystalline polymer with a high molecular weight (116,000 g/mol) was 320 kg/mol. Catalyst 1 produced the highest comonomer content (42%) in the copolymers measured by NMR. The least active catalyst was 5 (phenyl croup in the bridge), producing only 290 kg copolymer per mole of catalyst. All polymers had elevated glass transition temperatures compared to polypropylene. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2743–2752, 2002     

Solutions to electromagnetic interference problems between cochlear implants and GSM phones.

For persons using cochlear implants, electromagnetic compatibility (EMC) problems may sometimes be an obstacle to using digital cellular telephones. This study aimed at exploring the benefit of three new assistive listening device prototypes that eliminate or diminish EMC problems. Ten experienced cochlear implant users listened in quiet to running speech samples and a sentence test on a landline phone, a digital cellular phone with and without three prototypes. The subjects' performance was assessed using a sentence test, a subjective visual analog scale, and by ranking the best and the poorest listening condition. Compared to the other test conditions, listening to a digital cellular phone alone revealed, on average, the poorest sentence recognition scores (29%) and the poorest results in four different subjective judgments (the amount of disturbances, the clarity of the message, the quality of the sound, overall judgment) with all three implant systems tested. The prototypes generally helped the implantees to recognize speech better on the cellular telephone (by 10-21 percent units, on average). Use of assistive listening devices and further development of EMC of both cochlear implant systems and digital cellular phones needs to take place to enable smooth use of digital cellular phones for all implantees.     

High Temperature‐Stable Perovskite Solar Cell Based on Low‐Cost Carbon Nanotube Hole Contact

Mixed ion perovskite solar cells (PSC) are manufactured with a metal‐free hole contact based on press‐transferred single‐walled carbon nanotube (SWCNT) film infiltrated with 2,2,7,‐7‐tetrakis(N,N‐di‐p‐methoxyphenylamine)‐9,90‐spirobifluorene (Spiro‐OMeTAD). By means of maximum power point tracking, their stabilities are compared with those of standard PSCs employing spin‐coated Spiro‐OMeTAD and a thermally evaporated Au back contact, under full 1 sun illumination, at 60 °C, and in a N₂ atmosphere. During the 140 h experiment, the solar cells with the Au electrode experience a dramatic, irreversible efficiency loss, rendering them effectively nonoperational, whereas the SWCNT‐contacted devices show only a small linear efficiency loss with an extrapolated lifetime of 580 h.     

Review of materials and manufacturing options for large area flexible dye solar cells

This review covers the current state of the art related to up-scaling and commercialization of dye solar cells (DSC). The cost analysis of the different components and manufacturing of DSC gives an estimate on the overall production costs. Moreover, it provides an insight in which areas improvement is needed in order to reach significant cost reductions. As a result of the cost analysis, transferring the technology to flexible substrates and employment of simple roll-to-roll production methods were found the key issues. The focus of this work was set accordingly. In this work, appropriate materials along with their unique fabrication processes and different design methods are investigated highlighting their advantages and limitations. The basic goal is to identify the best materials and preparation techniques suitable for an ideal roll-to-roll process of flexible dye solar module fabrication as well as the areas where further development is still needed.     

Comparison of dye solar cell counter electrodes based on different carbon nanostructures

Three characteristically different carbon nanomaterials were compared and analyzed as platinum-free counter electrodes for dye solar cells: 1) single-walled carbon nanotube (SWCNT) random network films on glass, 2) aligned multi-walled carbon nanotube (MWCNT) forest films on Inconel steel and quartz, and 3) pressed carbon nanoparticle composite films on indium tin oxide-polyethylene terephtalate plastic. Results from electrochemical impedance spectroscopy and electron microscopy were discussed in terms of the catalytic activity, conductivity, thickness, transparency and flexibility of the electrode films. The SWCNT films showed reasonable catalytic performance at similar series resistance compared to platinized fluorine doped tin oxide-coated glass. The MWCNTs had similar catalytic activity, but the electrochemical performance of the films was limited by their high porosity. Carbon nanoparticle films had the lowest charge transfer resistance resulting from a combination of high catalytic activity and dense packing of the material.