Modelling spatio-temporal environmental data

A conceptual model for environmental data is presented with special emphasis on the ability to store spatio-temporal references of the data. Other aspects of the model are the ability to handle hierarchical data and semantics of the measurements. The model was tested with an implementation on an object-relational database management system. As a part of the test implementation, a forestry data set covering 75 years and 4900 hectares was loaded onto the database.     

OMI very fast delivery and the Sodankyla/spl uml/ Satellite Data Centre

The Ozone Monitoring Instrument (OMI) operates onboard the National Aeronautics and Space Administration's Earth Observing System Aura satellite, which was launched in July 2004. Like its sister spacecraft Terra and Aqua, Aura's capabilities include direct broadcast (DB), i.e., the ability to broadcast data at the same time as they are being measured and stored in the spacecraft's memory for later transmission to Earth. The Finnish Meteorological Institute's Satellite Data Centre at Sodankyla/spl uml/ in Finnish Lapland is exploiting this capability to receive OMI data while Aura is in sight of the receiver, which enables nearly immediate production of OMI data products for a region that includes a large part of Europe, stretching from the North Pole to the Italian Alps. The current OMI Very Fast Delivery (VFD) products include maps of surface UV-B, ozone columns, and cloud coverage.     

Antenna phase pattern measurements at millimeter wave frequencies using the differential phase method with only one power meter

The differential phase measurement method has been improved to need the use of only one power meter instead of three power meters. This enables accurate antenna phase pattern measurements with a simplified set-up, accompanied by the reduction in cost. All advantages of the differential phase measurement method are still also available, e.g. there is no need to phase lock oscillators or to use rotary joints. The measurement results for an antenna at 110 GHz are presented. A good agreement with earlier data was obtained.     

Predicting the health risks related to whole-body vibration and shock: a comparison of alternative assessment methods for high-acceleration events in vehicles

In this paper, alternative assessment methods for whole-body vibration and shocks are compared by means of 70 vibration samples measured from 13 work vehicles, deliberately selected to represent periods containing shocks. Five methodologies (ISO 2631-1:1997, BS 6841:1987, ISO 2631-5:2004, DIN SPEC 45697:2012 and one specified by Gunston [2011], ‘G-method’) were applied to the vibration samples. In order to compare different evaluation metrics, limiting exposures were determined by calculating times to reach the upper limit thresholds given in the methods. Over 10-fold shorter times to exposure thresholds were obtained for the tri-axial VDV (BS 6841) than for the dominant r.m.s. (ISO 2631-1) when exposures were of high magnitude or contained substantial shocks. Under these exposure conditions, the sixth power approaches (ISO 2631-5, DIN SPEC, G-method) are more stringent than a fourth power VDV method. The r.m.s. method may lead to misleading outcomes especially if a lengthy measurement includes a small number of severe impacts. In conclusion, methodologies produce different evaluations of the vibration severity depending on the exposure characteristics, and the correct method must be selected.     

Tele-Existence Techniques of Heavy Work Vehicles

The problem of finding a feasible and technically simple tele-existence system for teleoperation of heavy work vehicles is considered with the aid of two experimental test series. Several test persons of different ages and experience were used in experiments in which a basic audio/video tele-existence system with head-tracking was modified into different versions and tested. Conclusions indicate that details of the tasks and work environment have an important role in finding the optimal solution.     

Computing geometric properties of images represented by linear quadtrees

The region quadtree is a hierarchical data structure that finds use in applications such as image processing, computer graphics, pattern recognition, robotics, and cartography. In order to save space, a number of pointerless quadtree representations (termed linear quadtrees) have been proposed. One representation maintains the nodes in a list ordered according to a preorder traversal of the quadtree. Using such an image representation and a graph definition of a quadtree, a general algorithm to compute geometric image properties such as the perimeter, the Euler number, and the connected components of an image is developed and analyzed. The algorithm differs from the conventional approaches to images represented by quadtrees in that it does not make use of neighbor finding methods that require the location of a nearest common ancestor. Instead, it makes use of a staircase-like data structure to represent the blocks that have been already processed. The worst-case execution time of the algorithm, when used to compute the perimeter, is proportional to the number of leaf nodes in the quadtree, which is optimal. For an image of size 2n × 2n, the perimeter algorithm requires only four arrays of 2n positions each for working storage. This makes it well suited to processing linear quadtrees residing in secondary storage. Implementation experience has confirmed its superiority to existing approaches to computing geometric properties for images represented by quadtrees.