Combination Of Visualization Techniques Research Articles

An analysis of wintertime navigational accidents in the Northern Baltic Sea

Navigational accidents in wintertime conditions occur relatively frequently, yet there is little systematic knowledge available about the circumstances under which these occur. This paper presents an analysis of navigational shipping accidents in the Northern Baltic Sea area which occurred in the period 2007–2013. The analysis is based on an integration of various data sources, aiming to reconstruct the accident conditions based on the best available data sources. Apart from basic accident information from the original accident databases, data from the Automatic Identification System is used to obtain insight in the operation type during which the accident occurred, as well as into other dynamic aspects of the accident scenario. Finally, atmospheric and sea ice data is used to reconstruct the navigational conditions under which the accidents occurred. The analysis aims to provide qualitative insights in patterns and outlier cases in the accidental conditions. Correspondingly, visual data mining is selected as analysis approach, because of its utility in obtaining qualitative knowledge from data sources through a combination of visualization techniques and human interaction with the data. Special attention is given to the strength of evidence of the identified accident patterns. The results are primarily useful for improving risk analyses focusing on oil spill risks in winter conditions and for developing realistic training scenarios for oil spill response operations.

Noninvasive observation of magnetization reversal in micron-sized Co bars

We demonstrate how room temperature scanning Hall probe microscopy (SHPM) can be applied to noninvasively probe the (meta-)stable magnetic domain states of individual mesoscopic Co bars as a function of applied field. These data are correlated with magneto-optical measurements of the hysteresis loop as well as higher spatial resolution magnetic force microscopy imaging. In particular, we show how a combination of visualization techniques is essential for fully understanding the mechanism of magnetization reversal in such microstructures. Micromagnetic calculations of the magnetic states and their corresponding stray fields are correlated with the observations. These experiments prove the usefulness of a noninvasive and quantitative technique such as room temperature SHPM in an applied magnetic field to study magnetic domain stability and switching field distributions.

A flow visualization study of the NCVC centrifugal blood pump.

A compact centrifugal pump, NCVC-1, has an open-type impeller with 6 curved vanes, and it is characterized by no shaft and no seal. A tunnel is placed in the center of the impeller-rotor assembly to irrigate the back space behind the rotor. To evaluate the flow, we performed 3 visualization methods: tracer, oil film, and injection streak line method. The flow, observed by the tracer method in NCVC-1, indicated little turbulence along vanes. A volute chamber proved effective to reduce vortex formation in the outlet. Oil film pattern revealed no flow separation on vanes at 5 L/min. Washout flow behind the rotor is essential to prevent thrombus formation and was shown as inward spiral flow without any stagnation. These data suggested that a combination of visualization techniques was useful to analyze various flow conditions, and the NCVC-1 has excellent flow characteristics with little turbulence and little flow stagnation, which must be beneficial to low hemolysis and high antithrombogenicity.