Navigation by pointing to GPS locations

This article deals with a method for interacting with a handheld navigation application, based on using the mobile device for pointing. When the user points the device in any direction, feedback will be provided based on if the user is aiming at the next point in the track or beside it. The presented study has been performed in order to get a better understanding of how the basic parameters in this type of interaction—like the angle for pointing and the size of the target—influence the navigation performance. We have applied a dual investigation by running a computer simulation varying additional parameters such as GPS accuracy and user behavior, and also running an in-context study with 15 participants in a realistic outdoor setting with real location-based GPS data. The study has resulted in general recommendations for angle intervals and the radius of the circles surrounding the track points.     

Increasing work-time influence: consequences for flexibility, variability, regularity and predictability

This quasi-experimental study investigated how an intervention aiming at increasing eldercare workers' influence on their working hours affected the flexibility, variability, regularity and predictability of the working hours. We used baseline (n = 296) and follow-up (n = 274) questionnaire data and interviews with intervention-group participants (n = 32). The work units in the intervention group designed their own intervention comprising either implementation of computerised self-scheduling (subgroup A), collection of information about the employees' work-time preferences by questionnaires (subgroup B), or discussion of working hours (subgroup C). Only computerised self-scheduling changed the working hours and the way they were planned. These changes implied more flexible but less regular working hours and an experience of less predictability and less continuity in the care of clients and in the co-operation with colleagues. In subgroup B and C, the participants ended up discussing the potential consequences of more work-time influence without actually implementing any changes. PRACTITIONER SUMMARY: Employee work-time influence may buffer the adverse effects of shift work. However, our intervention study suggested that while increasing the individual flexibility, increasing work-time influence may also result in decreased regularity of the working hours and less continuity in the care of clients and co-operation with colleagues.     

Experience with fault injection experiments for FMEA

Failure Modes and Effects Analysis (FMEA) is a widely used system and software safety analysis technique that systematically identifies failure modes of system components and explores whether these failure modes might lead to potential hazards. In practice, FMEA is typically a labor‐intensive team‐based exercise, with little tool support. This article presents our experience with automating parts of the FMEA process, using a model checker to automate the search for system‐level consequences of component failures. The idea is to inject runtime faults into a model based on the system specification and check if the resulting model violates safety requirements, specified as temporal logical formulas. This enables the safety engineer to identify if a component failure, or combination of multiple failures, can lead to a specified hazard condition. If so, the model checker produces an example of the events leading up to the hazard occurrence which the analyst can use to identify the relevant failure propagation pathways and co‐effectors. The process is applied on three medium‐sized case studies modeled with Behavior Trees. Performance metrics for SAL model checking are presented. Copyright © 2011 John Wiley & Sons, Ltd.     

Load on the lumbar spine of flight attendants during pushing and pulling trolleys aboard aircraft

Flight attendants report on high physical load and complaints particularly focussing on the lower back. These findings are mainly ascribed to pushing and pulling of trolleys during the ascent and descent flight phases. Within an interdisciplinary experimental study, the load on the lumbar spine of flight attendants during trolley handling aboard aircraft was analysed based on laboratory measurements regarding posture and exerted forces as well as on subsequent biomechanical model calculations. Forces and moments of force at the lumbosacral disc were quantified for 458 manoeuvres performed by 25 flight attendants in total (22 female, 3 male).Lumbar load varies according to handling mode (pushing, pulling), floor gradient (0°, 2°, 5°, 8°), trolley type (half-, full-size trolley), trolley loading (empty, medium, full) and, in addition, according to individual execution technique. For each of the resulting 48 task configurations, lumbar load was evaluated with respect to potential biomechanical overload by applying work-design recommendations for disc compression and moment of force. Irrespective of floor inclination, trolley weight and individual performance, pushing of small trolleys is combined with acceptable lumbar load, pulling with critical load. Pushing or pulling large trolleys occasionally yield to critical lumbar load, in particular, when heavy or heaviest containers are moved on relatively steep or steepest surfaces.To diminish overload risk relevantly, top-edge grasp positions should be avoided for pulling of half-size trolleys, whereas for the other cases, grasping at the upper edge of the trolley is recommended.

Relevance to industry

The provided study illustrates lumbar load of flight attendants during trolley handling aboard aircraft for typical task conditions and individual execution techniques. Specified hints for work design regarding posture and grasp position enable to avoid biomechanical low-back overload for flight attendants. Furthermore, trolley properties may be reconsidered, regular maintenance of rollers should be guaranteed.     

Carbon-fiber-reinforced phenolics

Carbon-fiber-reinforced (CFR) phenolic composites with equivalent mechanical properties and much superior thermal stability to laboratory-prepared and present commercial epoxy analogs have been achieved by reinforcing 35-50 wt % of an amine-catalyzed resole with either the Hercules' Magnamite carbon fabric or the Great Lakes' Varinit carbon fiber/glass cloth hybrid. Improvement of the interlaminar shear strength (ILSS) of the hybrid-reinforced phenolic laminates was observed with increasing molding pressure and alternate carbon/glass/carbon/glass geometry. Sizings on the carbon fiber do not have any significant effect on the mechanical properties.     

Dynamic mechanical and thermal properties of fire-retardant high-impact polystyrene

The interaction of a series of fire-retardant additives with high-impact polystyrene (HIPS) has been inferred from their dynamic mechanical and thermal properties. High-melting additives phase separate and act as inert filler in both the rubber and polystyrene phases, while low-melting additives raise the T_g of the rubber phase and plasticize the polystyrene phase. Antimony oxide antiplasticizes the grafted rubber phase but acts as inert filler in the polystyrene phase. The impact strength of these fire-retardant HIPS's shows good correlation with the integrated loss tangent of the rubber T_g peak indicative of large energy dissipation in the rubbery region during impact causing the matrix to craze or flow. It is also suggested that additives which are compatible with, and localized in, the polystyrene phase help retain the impact strength of HIPS.     

Mass spectrometry of long-chain aliphatic aldehydes,dimethyl acetals and Alk-1-enyl ethers

Mass spectra of long-chain saturated and unsaturated aliphatic aldehydes, dimethyl acetals and alk-1-enyl methyl ethers are reported and discussed. Using deuterium labeled aldehydes, knowledge about the mass spectral fragmentation is obtained. The m/e M-44 ion is formed by a rearrangement different from the mechanism postulated previously for short-chain aldehydes. A series of hydrocarbon fragments with even mass numbers of 68+14n (n=0,1,2...) appear in the spectra of all three series of compounds. Paper No. 4 in a series, Mass Spectrometry of Lipids, For III, see Arkiv Kemi 29, 179 (1968).     

The role of hexafluorozirconate in the formation of chromate conversion coatings on aluminum alloys

Aluminum based surfaces are routinely coated with a chromate based layer that provides unparalleled corrosion protection. Widely used conversion coating treatment formulations contain hexafluorozirconate as a major constituent besides chromate, ferricyanide, fluoride, and fluoborate. The function of hexafluorozirconate is the subject of this study as its function is still largely unknown. Hydrophobicity, surface morphology, and the chemistry of the surface, resulting from treatment with hexafluorozirconate, were studied using contact angle measurements, scanning electron microscopy, and energy dispersive spectroscopy, respectively. X-ray photoelectron spectroscopy was extensively utilized to determine the chemistry of the surface resulting from the hexafluorozirconate pretreatment. Our results indicate that fluoride ion containing hexafluorozirconate complex does not attack the oxide film in a manner that uncomplexed simple fluoride ion does. Hexafluorozirconate is involved in the formation of an Al-Zr-O-F based hydrated layer that increases the hydrophilicity of the surface, activates the surface, and lowers the corrosion resistance. These factors enhance the interaction of chromate with the alloy surface to result in the formation of a uniform conversion coating. Based on these results, a new model has been proposed for the formation of chromate conversion coatings.