Refine
Year of publication
Institute
- Fachbereich Medizintechnik und Technomathematik (2087)
- Fachbereich Elektrotechnik und Informationstechnik (1187)
- Fachbereich Wirtschaftswissenschaften (1164)
- Fachbereich Energietechnik (1116)
- Fachbereich Chemie und Biotechnologie (919)
- Fachbereich Maschinenbau und Mechatronik (884)
- Fachbereich Luft- und Raumfahrttechnik (799)
- Fachbereich Bauingenieurwesen (712)
- IfB - Institut für Bioengineering (693)
- INB - Institut für Nano- und Biotechnologien (616)
Language
- German (5148)
- English (4951)
- Russian (14)
- Portuguese (6)
- Italian (5)
- Multiple languages (5)
- Spanish (3)
- Dutch (2)
Document Type
- Article (5637)
- Conference Proceeding (1677)
- Book (1087)
- Part of a Book (576)
- Bachelor Thesis (332)
- Patent (177)
- Report (102)
- Conference: Meeting Abstract (82)
- Doctoral Thesis (82)
- Administrative publication (77)
Keywords
- Amtliche Mitteilung (72)
- Bachelor (34)
- Aachen University of Applied Sciences (31)
- Master (31)
- Prüfungsordnung (31)
- Bauingenieurwesen (30)
- Lesbare Fassung (28)
- Biosensor (25)
- Fachhochschule Aachen (23)
- Illustration (23)
Zugriffsart
- campus (2155)
- weltweit (1904)
- bezahl (788)
- fachbereichsweit (FB4) (38)
The rail business is challenged by long product life cycles and a broad spectrum of assembly groups and single parts. When spare part obsolescence occurs, quick solutions are needed. A reproduction of obsolete parts is often connected to long waiting times and minimum lot quantities that need to be purchased and stored. Spare part storage is therefore challenged by growing stocks, bound capital and issues of part ageing. A possible solution could be a virtual storage of spare parts which will be 3D printed through additive manufacturing technologies in case of sudden demand. As mechanical properties of additive manufactured parts are neither guaranteed by machine manufacturers nor by service providers, the utilization of this relatively young technology is impeded and research is required to address these issues. This paper presents an examination of mechanical properties of specimens manufactured from stainless steel through the selective laser melting (SLM) process. The specimens were produced in multiple batches. This paper interrogates the question if the test results follow a normal distribution pattern and if mechanical property predictions can be made. The results will be put opposite existing threshold values provided as the industrial standard. Furthermore, probability predictions will be made in order to examine the potential of the SLM process to maintain state-of-the-art mechanical property requirements.
The paper deals with the asymptotic behaviour of estimators, statistical tests and confidence intervals for L²-distances to uniformity based on the empirical distribution function, the integrated empirical distribution function and the integrated empirical survival function. Approximations of power functions, confidence intervals for the L²-distances and statistical neighbourhood-of-uniformity validation tests are obtained as main applications. The finite sample behaviour of the procedures is illustrated by a simulation study.
In this research work, a statistical analysis of the CO2 laser beam welding of dual phase (DP600)/transformation induced plasticity (TRIP700) steel sheets was done using response surface methodology. The analysis considered the effect of laser power (2–2.2 kW), welding speed (40–50 mm/s) and focus position (−1 to 0 mm) on the heat input, the weld bead geometry, uniaxial tensile strength, formability limited dome height and welding operation cost. The experimental design was based on Box–Behnken design using linear and quadratic polynomial equations for predicting the mathematical models. The results indicate that the proposed models predict the responses adequately within the limits of welding parameters being used and the welding speed is the most significant parameter during the welding process.
The optimization of light output and energy resolution of scintillators is of special interest for the development of high resolution and high sensitivity PET. The aim of this work is to obtain statistically reliable results concerning optimal surface treatment of scintillation crystals and the selection of reflector material. For this purpose, raw, mechanically polished and etched LSO crystals (size 2×2×10 mm3) were combined with various reflector materials (Teflon tape, Teflon matrix, BaSO4) and exposed to a 22Na source. In order to ensure the statistical reliability of the results, groups of 10 LSO crystals each were measured for all combinations of surface treatment and reflector material. Using no reflector material the light output increased up to 551±35% by mechanical polishing the surface compared to 100±5% for raw crystals. Etching the surface increased the light output to 441±29%. The untreated crystals had an energy resolution of 24.6±4.0%. By mechanical polishing the surface it was possible to achieve an energy resolution of 13.2±0.8%, by etching of 14.8±0.7%. In combination with BaSO4 as reflector material the maximum increase of light output has been established to 932±57% for mechanically polished and 895±61% for etched crystals. The combination with BaSO4 also caused the best improvement of the energy resolution up to 11.6±0.2% for mechanically polished and 12.2±0.3% for etched crystals. Relating to the light output there was no significant statistical difference between the two surface treatments in combination with BaSO4. In contrast to this, the statistical results of the energy resolution have shown the combination of mechanical polishing and BaSO4 as the optimum.
The construction of a statistical test is investigated which is based only on “reliability” and “precision” as quality criteria. The reliability of a statistical test is quantifiedin a straightforward way by the probability that the decision of the test is correct. However, the quantification of the precision of a statistical test is not at all evident. Thereforethe paper presents and discusses several approaches. Moreover the distinction of “nullhypothesis” and “alternative hypothesis” is not necessary any longer.
Statistisches Multiplexen von Sprache und Daten in TDMA-Mobilfunksystemen der dritten Generation
(1995)
Die Nutzung von Prozessmodellierungsmethoden oder - werkzeugen kann erheblichen Einfluss auf die Effektivität von Prozessen haben. Das gilt insbesondere für Situationen, in denen Personen unter Stress stehen oder ungeübt sind. In diesen Fällen geben Prozessmodelle konkrete Empfehlungen, nach denen sich die handelnden Personen richten könnten. In Experimenten mit der Business-Simulation Apollo 13 haben wir den Effekt eines Einsatzes von Prozessmodellierungsmethoden und -werkzeugen untersucht. Bereits bekannte Theorien (z.B. über geeignete Verhältnisse von Kommunikationsinhalten) konnten bestätigt werden. Darüber hinaus haben wir eine besondere Bedeutung der Übertragbarkeit von Prozessmodellen in konkrete Handlungen identifiziert.
Der Aufbau und die Entstehung unseres Planeten sind untrennbar mit der Bildung von Gesteinen verbunden – diese setzen sich aus verschiedenen Mineralien zusammen. Sie sind in der Natur weit verbreitet und spielen eine entscheidende Rolle in unserem täglichen Leben. Obwohl vielen Menschen der Nutzen von Bodenschätzen bewusst ist, besteht ein geringes Wissen über deren Vorkommen und Relevanz. Für die wirtschaftliche Entwicklung des Siegerlandes beispielsweise waren der Abbau und der Handel mit Mineralien von großer Bedeutung. Insbesondere der langjährige Abbau von Eisenerz legte den Grundstein für die gesamte Metallindustrie der Region. Die Publikation visualisiert eine umfangreiche Sammlung Siegerländer Mineralien und vermittelt ein grundlegendes Verständnis von Mineralien.