Dimensionierung von Entkopplungspuffern in dynamischen Fertigungsprozessen mittels Warteschlangen

Auf Grund eines zufälligen, weil nicht exakt vorhersehbaren Eintreffens von Fertigungsaufträgen und Ausgangsmaterialien (Anlieferung von Zulieferer, Bereitstellung aus einem Lager) an einem ersten Fertigungsbereich und einer nicht konstanten Durchlaufzeit kommt es zu einer unregelmäßigen Bereitstellung der bearbeiteten Aufträge am sich anschließenden zweiten Fertigungsbereich. Um dort jedoch eine hohe Auslastung zu erzielen, wird eine kontinuierliche Bearbeitung und damit getaktete Bereitstellung angestrebt. Die Lösung ist ein Zwischenspeicher oder Puffer, der die beiden Prozesse entkoppelt. Es wird ein Verfahren vorgestellt, mit dem die Verteilung der Pufferbelegung auf analytischem Wege bestimmt und damit die erforderliche Größe des Entkopplungspuffers mit einer vorgegebenen statistischen Sicherheit abgeleitet werden kann.

Homogeneous reprocessing of GPS, GLONASS and SLR observations

The International GNSS Service (IGS) provides operational products for the GPS and GLONASS constellation. Homogeneously processed time series of parameters from the IGS are only available for GPS. Reprocessed GLONASS series are provided only by individual Analysis Centers (i. e. CODE and ESA), making it difficult to fully include the GLONASS system into a rigorous GNSS analysis. In view of the increasing number of active GLONASS satellites and a steadily growing number of GPS+GLONASS-tracking stations available over the past few years, Technische Universität Dresden, Technische Universität München, Universität Bern and Eidgenössische Technische Hochschule Zürich performed a combined reprocessing of GPS and GLONASS observations. Also, SLR observations to GPS and GLONASS are included in this reprocessing effort. Here, we show only SLR results from a GNSS orbit validation. In total, 18 years of data (1994–2011) have been processed from altogether 340 GNSS and 70 SLR stations. The use of GLONASS observations in addition to GPS has no impact on the estimated linear terrestrial reference frame parameters. However, daily station positions show an RMS reduction of 0.3 mm on average for the height component when additional GLONASS observations can be used for the time series determination. Analyzing satellite orbit overlaps, the rigorous combination of GPS and GLONASS neither improves nor degrades the GPS orbit precision. For GLONASS, however, the quality of the microwave-derived GLONASS orbits improves due to the combination. These findings are confirmed using independent SLR observations for a GNSS orbit validation. In comparison to previous studies, mean SLR biases for satellites GPS-35 and GPS-36 could be reduced in magnitude from −35 and −38 mm to −12 and −13 mm, respectively. Our results show that remaining SLR biases depend on the satellite type and the use of coated or uncoated retro-reflectors. For Earth rotation parameters, the increasing number of GLONASS satellites and tracking stations over the past few years leads to differences between GPS-only and GPS+GLONASS combined solutions which are most pronounced in the pole rate estimates with maximum 0.2 mas/day in magnitude. At the same time, the difference between GLONASS-only and combined solutions decreases. Derived GNSS orbits are used to estimate combined GPS+GLONASS satellite clocks, with first results presented in this paper. Phase observation residuals from a precise point positioning are at the level of 2 mm and particularly reveal poorly modeled yaw maneuver periods.

Tertiary flora of Saxony

The thesis represents the first part of a reference book to the Tertiary flora of Saxony. All taxa based on leaves of angiosperms and on Ginkgo are included in this compendium. After an overview about the geological state of knowledge on the Tertiary in Saxony, phytostratigraphic concepts are introduced and a historical survey on the Tertiary paleobotanical research in Saxony is given. All plant macrofossils published from Saxonian Tertiary until end of 2013 and their sites of discovery (primary data) were recorded. This data were supplemented by additional attributes and unified through project-based M.Sc. theses. Subsequently, taxa of fossil leaves were selected, their data evaluated and brought to a consistent state of research. Data sheets for 187 out of 235 examined taxa were established for a determination atlas. Macro- and micromorphological attributes are described in this atlas and information are given about the systematic, synonymy, palaeoecology and spatial and temporal distribution. The describing part is illustrated by images and instructive drawings. The documented data were surveyed and discussed related to their quality within the literature in the result part. A bibliography of the extensive palaeobotanical literature for plant fossils of Saxony completes the work. The taxon and locality related data are implemented into an open source geographical information system (GIS) in order to visualize and to manage them effectively. For the first time, the results of this thesis implemented in the GIS allow the generation of distribution maps for the taxa of leaves of Tertiary angiospermes and Ginkgo in Saxony. Furthermore it enables to query topographical, geological and paleobotanical information about the fossil sites. A determination key was developed for the fossil material that allows a rough determination of the findings in the field. The compendium will be available for free use in a printed as well as in a digital version.