Author supplied: "This paper gives a linearised adjustment model for the affine, similarity and congruence transformations in 3D that is easily extendable with other parameters to describe deformations. The model considers all coordinates stochastic. Full positive semi-definite covariance matrices and correlation between epochs can be handled. The determination of transformation parameters between two or more coordinate sets, determined by geodetic monitoring measurements, can be handled as a least squares adjustment problem. It can be solved without linearisation of the functional model, if it concerns an affine, similarity or congruence transformation in one-, two- or three-dimensional space. If the functional model describes more than such a transformation, it is hardly ever possible to find a direct solution for the transformation parameters. Linearisation of the functional model and applying least squares formulas is then an appropriate mode of working. The adjustment model is given as a model of observation equations with constraints on the parameters. The starting point is the affine transformation, whose parameters are constrained to get the parameters of the similarity or congruence transformation. In this way the use of Euler angles is avoided. Because the model is linearised, iteration is necessary to get the final solution. In each iteration step approximate coordinates are necessary that fulfil the constraints. For the affine transformation it is easy to get approximate coordinates. For the similarity and congruence transformation the approximate coordinates have to comply to constraints. To achieve this, use is made of the singular value decomposition of the rotation matrix. To show the effectiveness of the proposed adjustment model total station measurements in two epochs of monitored buildings are analysed. Coordinate sets with full, rank deficient covariance matrices are determined from the measurements and adjusted with the proposed model. Testing the adjustment for deformations results in detection of the simulated deformations."
MULTIFILE
While tourism and air transport are recovering from the impacts of the Covid pandemic, it seems timely to draw a synthetic view of future stakes combining the following topics: the greenhouse gas emissions scenarios for tourism, regarding which recent work has improved their understanding; the climatic impact of aviation, almost 60% of which is due to non-CO 2 emissions; alternative fuels (biofuels, E-fuels, hydrogen) and engine designs (fuel cells...) which are complex and controversial issues, and whose potentials should be assessed regarding their timing, environmental impacts, and their ability to meet long distance travel requirements. This paper analyses the extent to which the new options regarding fuels and engines can help decarbonize tourism and air transport. The answer is that they can partly contribute but do not render obsolete previous work on substitutions between types of tourism (short versus long distance...), between transport modes (ground transport versus air), length of stay, etc. Following this step, the paper deals with the position of aviation players and the type of arguments they use. We conclude on the necessity to make strategic choices among the options to avoid wasting investments.
MULTIFILE
Ethnographic fieldwork is a balancing act between distancing and immersing. Fieldworkers need to come close to meaningfully grasp the sense-making efforts of the researched. In methodological textbooks on ethnography, immersion tends to be emphasized at the expense of its counterpart. In fact, ‘distancing’ is often ignored as a central tenet of good ethnographic conduct. In this article we redirect attention away from familiarization and towards ‘defamiliarization’ by suggesting six estrangement strategies (three theoretical and three methodological) that allow the researcher to develop a more detached viewpoint from which to interpret data. We demonstrate the workings of these strategies by giving illustrations from Machteld de Jong’s field- and text-work, conducted among Moroccan-Dutch students in an institution of higher vocational education.
