Flight Dynamics Operations of the TanDEM-X Formation

Since end of 2010 the German TerraSAR-X and TanDEM-X satellites are routinely operated as the first configurable single-pass Synthetic Aperture Radar interferometer in space. The two 1340 kg satellites fly in a 514 km sun-synchronous orbit. In order to collect sufficient measurements for the generation of a global digital elevation model and to demonstrate new interferometric SAR techniques and applications, more than three years of formation flying are foreseen with flexible baselines ranging from 150 m to few kilometers. As a prerequisite for the close formation flight an extensive flight dynamics system was established at DLR/GSOC, which comprises of GPS-based absolute and relative navigation and impulsive orbit and formation control. Daily formation maintenance maneuvers are performed by TanDEM-X to counterbalance natural and artificial disturbances. The paper elaborates on the routine flight dynamics operations and its interactions with mission planning and ground-station network. The navigation and formation control concepts and the achieved control accuracy are briefly outlined. Furthermore, the paper addresses non-routine operations experienced during formation acquisition, frequent formation reconfiguration, formation maintenance problems and space debris collision avoidance, which is even more challenging than for single-satellite operations. In particular two close approaches of debris are presented, which were experienced in March 2011 and April 2012. Finally, a formation break-up procedure is discussed which could be executed in case of severe onboard failures

On the trails of Josias Braun-Blanquet : changes in the grasslands of the inneralpine dry valleys during the last 70 years. First results from the 11th EDGG Field Workshop in Austria

The 11th EDGG Field Workshop was held from 6 to 13 July 2018 in Austria. Its aim was to revisit dry grasslands in the inneralpine dry valleys of Austria that were investigated in the late 1950s by Braun-Blanquet and to collect high-quality biodiversity data from these. Sampling was carried out in the Styrian Mur Valley, the Virgen Valley in East Tyrol, the Upper Inn Valley in the Austrian Eastern Alps, and Griffen in Carinthia. In total, we sampled 15 EDGG biodiversity plots and 37 additional 10 m2 plots. Butterfly data were record-ed in four biodiversity plots and two additional plots. We found maximum richness values of 49, 68 and 95 vascular plant species on 1, 10 and 100 m², while the corresponding values for the complete terrestrial vegetation were 56, 73 and 106 species. Maximum butterfly richness was 19, but it was in general quite low, and generalists dominated. Some of the areas originally studied by Braun-Blanquet were no longer dry grasslands and only a few sites remained largely unchanged. Detrended Correspondence Analysis (DCA) showed profound changes between the old (1950s and 1980s) and our current plots. Without grazing or other human land management activities, only very small cores of rocky dry grassland could survive in the comparatively humid Austrian inneralpine valleys. Finally, the sampled data raise questions about the syntaxonomic position of some of the grasslands, which needs to be addressed in a more comprehensive study, which is planned as the next step

Unsupervized construction of semantic lexicon

V předložené práci jsou zkoumány možnosti konstrukce sémantických slovníků z neoanotovaných dat, tedy z prostého textu. Jsou zde porovnánány výhody a nevýhody několika možných přístupů anotace. Blíže je rozpracováno jedno řešení na základě latentní sémantické analýzy (LSA), které na rozdíl od ostatních metod řeší problém polysemie a synonymie. Dále jsou zde uvedeny podrobné detaily implementace a vyhodnocení. Výsledkem je sada nástrojů pro vytváření, převádění a prohlížení sémantických slovníků v českém jazyce. Použité postupy nejsou závislé na jazyce, pro který jsou implemantované.In present work are studied possibilities of unsupervized constuction of semantic lexicons. There are compared advantages and disadvantages of several annotation methods. More closely developed is one solution, which is based on latent semantic analysis (LSA). Unlike the others, this method solves the problems of polysemy and synonymy. Below are described details of the algorithm implementanion and evaluation. This thesis provides a set of tools for construction, browsing and conversion of semantic lexicons for czech language. Used methods do not depend on the language.Ústav formální a aplikované lingvistikyInstitute of Formal and Applied LinguisticsFaculty of Mathematics and PhysicsMatematicko-fyzikální fakult

Cohort Profile of The GOALS Study: A Large-scale Research of Physical Activity in Dutch Students

The GOALS study (Grootschalig Onderzoek naar Activiteiten van Limburgse Scholieren [Large-scale Research of Activities in Dutch Students]) was set up to investigate possible associations between different forms of physical activity and inactivity with cognitive performance, academic achievement and mental wellbeing. It was conducted at a secondary school in the south of the Netherlands. Data collection took place during normal school weeks from October 2011 to March 2012 and one year later from October 2012 to May 2013. The study was approved by the local Ethical Committee of the Open University of the Netherlands. All students in grades 7 and 9 of senior general secondary education and university preparatory education were invited to participate (N = 526). At baseline a sample of 440 Dutch-speaking adolescents was willing to participate (83.7%). Of these, 344 participated in the follow-up. Physical activity was measured objectively by an ActivPal3TM accelerometer. Cognitive performance was measured by the D2 test of attention and the Symbol Digit Modalities Test. Academic achievement was determined using the mean of school grades in Dutch, English, and Mathematics. Several well-validated instruments were used to determine mood/depressive symptoms, self-esteem and goal orientation. Information on several covariates such as sex, academic year, school level, ethnicity, socioeconomic status, BMI, pubertal status, smoking, drinking, viewing television, computer use etc. are available

Associatie tussen fysieke activiteit en schoolprestaties van adolescenten

Van Dijk, M. L., De Groot, R. H. M., & Kirschner, P. A. (2011, 1 December). Associatie tussen fysieke activiteit en schoolprestaties van adolescenten. Posterpresentatie gegeven tijdens het Congres ‘Hersenen en Cognitie: Maatschappelijke Innovatie’, Nationaal Initiatief Hersenen en Cognitie, Utrecht, Nederland.Onderzoek bij ouderen heeft aangetoond dat lichamelijke activiteit een positief effect heeft op cognitieve prestaties. Bij adolescenten is weinig (objectief) onderzoek uitgevoerd. Middels deze studie wordt op een objectieve manier onderzocht welke associatie er is tussen oa. sporten, fietsen naar school en slapen en de schoolprestaties van adolescenten

Cohort Profile of The GOALS Study: A Large-scale Research of Physical Activity in Dutch Students

The GOALS study (Grootschalig Onderzoek naar Activiteiten van Limburgse Scholieren [Large-scale Research of Activities in Dutch Students]) was set up to investigate possible associations between different forms of physical activity and inactivity with cognitive performance, academic achievement and mental wellbeing. It was conducted at a secondary school in the south of the Netherlands. Data collection took place during normal school weeks from October 2011 to March 2012 and one year later from October 2012 to May 2013. The study was approved by the local Ethical Committee of the Open University of the Netherlands. All students in grades 7 and 9 of senior general secondary education and university preparatory education were invited to participate (N = 526). At baseline a sample of 440 Dutch-speaking adolescents was willing to participate (83.7%). Of these, 344 participated in the follow-up. Physical activity was measured objectively by an ActivPal3TM accelerometer. Cognitive performance was measured by the D2 test of attention and the Symbol Digit Modalities Test. Academic achievement was determined using the mean of school grades in Dutch, English, and Mathematics. Several well-validated instruments were used to determine mood/depressive symptoms, self-esteem and goal orientation. Information on several covariates such as sex, academic year, school level, ethnicity, socioeconomic status, BMI, pubertal status, smoking, drinking, viewing television, computer use etc. are available

De GOALS Studie: Associatie tussen fysieke activiteit en schoolprestaties van adolescenten

Van Dijk, M. L., De Groot, R. H. M., & Kirschner, P. A. (2011, 8 September). De GOALS Studie: Associatie tussen fysieke activiteit en schoolprestaties van adolescenten. Presentatie gegeven tijdens kennismakingsbezoek KU Leuven, Heerlen, Nederland.Onderzoek bij ouderen heeft aangetoond dat lichamelijke activiteit een positief effect heeft op cognitieve prestaties. Bij adolescenten is weinig (objectief) onderzoek uitgevoerd. Middels deze studie wordt op een objectieve manier onderzocht welke associatie er is tussen oa. sporten, fietsen naar school en slapen en de schoolprestaties van adolescenten