Commission I, WG I/2 KEY WORDS: LiDAR waveform, classification, Self-Organizing Map (SOM), Bayes classifier, urban area ABSTRACT:In this paper, the use of waveform data in urban areas is studied. Full waveform is generally used in non-urban areas, where it can provide better vertical structure description of vegetation compared to discrete return systems. However, waveform could be potentially useful for classification in urban areas, where classification methods can be extended to include parameters derived from waveform analysis. Besides common properties, also sensed by multi-echo systems (intensity, number of returns), the shape of the waveform also depends on physical properties of the reflecting surface, such as material, angle of incidence, etc. The main goal of this investigation is to identify relevant parameters, derived from waveform that are related to surface material or object class. This paper uses two waveform parameterization approaches: Gaussian shape fitting and discrete wavelet transformation. The two classification methods tested are: supervised Bayes classification and unsupervised Self-Organizing Map (SOM) classification. The results of these methods were compared to each other and to manual classification. The initial conclusion is that, though waveform data contains classification information, the waveform shape by itself is not enough to perform classification in urban regions, and, consequently, it should be combined with the point cloud geometry.

In this article we investigate the different failure mechanisms in IGBT modules as a result of power cycling tests. The power cycling is carried out with different control strategies, such as constant current load, constant power and constant junction temperature. With the continuous monitoring of the tested device voltage, junction temperatures and periodic thermal transient tests, the crack of the wire bonds or even degradation of the die attach layer can be identified. A comparison between the effects of the studied control strategies on the lifetime of the tested device is also presented.

After more than 40 years of interruption new field observations have been made by an E-54 type torsion balance (TB)in the Csepel-island. These TB measurements were accompanied by a detailed gravimetric survey of each station with LCR gravimeters. Both vertical (VG) and horizontal (HG) gravity gradients were determined at each TB station for VG interpolation and reliability tests.Vertical gradient of gravity cannot be measured directly by the Eötvös TB. However, we successfully interpolated VG differences in the network of TB measurements following the idea originally due to Haalck. Reliability tests by comparing HG and VG gravimetric and TB measurements were also performed. Our recent paper discusses first results of these TB and gravimetric measurements which are scheduled to be continued in the future as well.

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