A smartphone-based fall detection system

Falls are a major cause of injuries and hospital admissions among elderly people. Thus, the caregiving process and the quality of life of older adults can be improved by adopting systems for the automatic detection of falls. This paper presents a smartphone-based fall detection system that monitors the movements of patients, recognizes a fall, and automatically sends a request for help to the caregivers. To reduce the problem of false alarms, the system includes novel techniques for the recognition of those activities of daily living that could be erroneously mis-detected as falls (such as sitting on a sofa or lying on a bed). To limit the intrusiveness of the system, a small external sensing unit can also be used for the acquisition of movement data.     

Cooperative caging and transport using autonomous aquatic surface vehicles

We present a study on the cooperative control of two autonomous surface vehicles performing a caging and transport mission on the water surface. The two vehicles, connected to each other by means of a floating flexible rope, are required to capture a floating target from a given location, and transport it to a designated position. We focus on the coordination and control strategy to meet these requirements, and on its implementation on two under-actuated vehicles. We describe a multi-layered control architecture which achieves the goal, followed by simulation studies and field experiments with the two vehicles caging and transporting a floating target on the surface of a lake.     

Effects of hydrogen addition on the high temperature deformation behavior of TC21 titanium alloy

The true stress-strain curves of TC21 titanium alloy charged with up to 0.7 wt.% hydrogen were obtained by the isothermal hot compression tests which were carried out on an Instron 5500 machine at 1023 to 1223 K and 0.001 to 0.1 s⁻¹. The dependence of the steady state flow stress on hydrogen content was determined. The results showed that with the increase of hydrogen content flow stress decreased at lower hydrogen content and then increased at higher hydrogen content. Suitable hydrogen addition can significantly decrease the flow stress and improve the hot workability of TC21 titanium alloy. The flow stress behaviors and the dependence of hydrogen content on flow stress were clarified by microstructural observation. The optimum hydrogen content at different deformation temperature was determined.     

Improving the results of spectral unmixing of Landsat Thematic Mapper imagery by enhancing the orthogonality of end-members

Spectral unmixing is a technique that has been developed to derive fractions of spectrally pure materials that contribute to observed spectral reflectance characteristics of a mixture through a inverse least-squares deconvolution using end-member spectra. This technique has been shown to be very successful when applied to high spectral resolution imaging or non-imaging data where subtle diagnostic absorption features largely determine the spectral characteristics of the data. A large and vastly growing number of papers where spectral unmixing is applied to analyse low resolution image data (e.g. Landsat Thematic Mapper (TM), NOAA AVHRR, etc.) often to derive abundances of different materials as input parameters for models (i.e. land degradation models, crop growth models, hydrologic models, etc.) has evolved throughout recent years. This justifies efforts put into the quality assessment of these abundance estimates. In this paper we evaluate the effect of end-member redundancy on the deconvolution of spectral mixtures in unconstrained unmixing using simulated, one-dimensional spectral mixtures of three end-members that we unmix with two out of three of these components. Our analysis shows a relationship between the unmixing error and the difference between the true and estimated abundance with an index which combines (1) the weighted correlation of end-members in the mixture, (2) the correlation between the end-members used in unmixing this mixture, and (3) the amount of 'information' mapped in the end-members. Given this result we investigate the reduction of correlation in the spectral unmixing process and present an application of unmixing to decorrelated Landsat TM data using the minimum noise fraction transformation. The statistical evaluation of this experiment shows that over-and undershooting rather than the error in the unmixed spectrum can be significantly improved when decorrelating the data.     

Is there a space for additional renewable energy in the Norwegian power system? Potential for reduced global emission?

This paper presents the results of a Norwegian power system analysis. An energy system analysis model based on linear programming is used for modelling and optimisation. The analyses cover a number of scenarios where the studied system is subjected to changes by introducing other renewable energy sources, energy conservation measures and measures to promote renewable energy. The study shows that due to a combination of cheap hydropower and high investment costs, it is quite difficult for new generation units to be profitable. This is also true during periods of low precipitation where the system tends to survive on imported power instead of investing in new generation units. However, this does not apply to energy conservation measures that easily enter the system. On the other hand, biomass based CHP, wind power and wave power could be viable if measures are introduced to promote their use. Most of the scenarios show a high potential for reducing global emissions.     

On the Processing of Martensitic Steels in Continuous Galvanizing Lines: Part 1

Whereas low-carbon (<0.2 mass pct) martensitic grades can be produced easily in continuous annealing processing lines equipped with the required cooling capacity, the thermal cycles in continuous galvanizing lines make it difficult to produce hot-dip Zn or Zn-alloy coated high-strength martensitic grades. This is because of the tempering processes occurring during dipping of the strip in the liquid Zn bath and, in the case of galvannealed sheet steel, the short thermal treatment required to achieve the alloying between the Zn and the steel. These short additional thermal treatments last less than 30 seconds but severely degrade the mechanical properties. Using a combination of internal friction, X-ray diffraction, and transmission electron microscopy, it is shown that the ultrafine-grained lath microstructure allows for a rapid dislocation recovery and carbide formation during the galvanizing processes. In addition, the effective dislocation pinning occurring during the galvannealing process results in strain localization and the suppression of strain hardening.