Refine
Year of publication
- 2012 (333) (remove)
Institute
- Fachbereich Medizintechnik und Technomathematik (72)
- Fachbereich Wirtschaftswissenschaften (42)
- Fachbereich Chemie und Biotechnologie (40)
- Fachbereich Elektrotechnik und Informationstechnik (40)
- INB - Institut für Nano- und Biotechnologien (32)
- IfB - Institut für Bioengineering (31)
- Fachbereich Bauingenieurwesen (30)
- Fachbereich Maschinenbau und Mechatronik (29)
- Fachbereich Energietechnik (20)
- Solar-Institut Jülich (15)
Document Type
- Article (130)
- Conference Proceeding (89)
- Part of a Book (36)
- Book (26)
- Conference: Meeting Abstract (17)
- Patent (12)
- Part of a Periodical (9)
- Doctoral Thesis (7)
- Report (4)
- Habilitation (1)
Keywords
- Elektromobilität (7)
- Elektrofahrzeug (5)
- Energieversorgungsnetz (5)
- Kraftfahrzeugelektronik (5)
- Aachen / Fachhochschule Aachen (3)
- Aachen University of Applied Sciences (2)
- Elektromobilität; Elektrofahrzeug; Energieversorungsnetz; Kraftfahrzeugtechnik (2)
- (Bio)degradation (1)
- 3. EU Legislativpaket (1)
- 802.15.4 (1)
Zuverlässigkeitsanalyse zur Verifikation der Einhaltung von quantitativen Sicherheitsanforderungen.
(2012)
Wendehorst Beispiele aus der Baupraxis / Ulrich Vismann (Hrsg.). - 4., durchges. und aktualis. Aufl.
(2012)
Der Temperaturanstieg der vergangenen Jahrzehnte war in Gebirgsregionen besonders ausgeprägt. Sollte sich dieser Temperaturtrend im 21. Jahrhundert fortsetzen, dann dürf-ten sich auch die Häufigkeit und Intensität von Niederschlä-gen und Trockenperioden verändern, was die Waldwirtschaft vor grosse Herausforderungen stellen wird. Trockenheit ist ein entscheidender Faktor für die Waldökosysteme der inner-alpinen Täler, wo seit Jahren trockenheitsbedingtes Baum-sterben festgestellt wird. Der vorliegende Beitrag hat zum Ziel, die Sensitivität der verschiedenen Waldökosysteme ge-genüber Klimawandel und alternative, teilweise extreme Bewirtschaftungsvarianten in der Region Visp zu testen. Me-thodische Ansätze wie Monitoring, Feldexperimente und dy-namische Modellierung wurden kombiniert, und es wurden verschiedene Ökosystemleistungen berücksichtigt, so Holz-produktion, Schutz vor Naturgefahren, Kohlenstoffspeiche-rung und Aspekte der Biodiversität. Die Resultate deuten da-rauf hin, dass auf den Trockenstandorten der Tieflagen die einheimischen Baumarten an ihre physiologischen Grenzen stossen und längerfristig über alternative Baumarten nach-gedacht werden sollte. In den mittleren Lagen dürften Tro-ckenheit und Schadinsekten wie die Borkenkäfer die zukünf-tige Waldentwicklung steuern. In den Hochlagen hingegen werden sich die Wälder ausdehnen und besser wachsen als heute. Alle untersuchten Ökosystemleistungen werden ge-bietsweise starken Veränderungen unterworfen sein. Die dis-kutierten Bewirtschaftungsvarianten scheinen dazu geeignet, die Wasserverfügbarkeit der Bestände, hauptsächlich in tief-eren Lagen, zu erhöhen und dadurch die Widerstandskraft der Bäume gegenüber Trockenperioden vorübergehend zu stärken. Es ist aber davon ausgehen, dass nur verhältnismäs-sig starke Eingriffe wesentliche Effekte erzielen können. Die Verknüpfung von Umweltmonitoring, Feldexperimenten und Modellierung unter Miteinbezug von Ökosystemleistungen ist vielversprechend, da sie eine differenzierte Abschätzung des zukünftigen Landschaftswandels und seiner Effekte auf die Waldleistungen ermöglicht.
Vorwort
(2012)
Security Awareness ist derzeit ein viel diskutiertes Thema. Es reicht nicht, einfach nur ein paar technische Systeme (z.B. Firewalls) zu installieren, um ein angemessenes Schutzniveau zu erzielen. Neben einer guten Organisation von IT Security ist es auch notwendig, den Mitarbeiter einzubinden. Der vielzitierte "Faktor Mensch" ist derjenige, der die Technik korrekt anwenden muss und der durch falsches Verhalten technische und organisatorische Schutzmaßnahmen aushebeln kann. Deshalb reicht es nicht aus, wenn sich der Mitarbeiter der Gefahren bewusst ("aware") ist, er muss auch dementsprechend "sicher" handeln.
Vollzug der Schenkung einer Unterbeteiligung : BGH, Urteil vom 29.11.2011 - II ZR 306/09 : Anmerkung
(2012)
Visual Virology
(2012)
Auch mit der jüngsten Finanzkrise hat die Konsumkultur nichts von ihrer Bedeutung als massenkulturelles Phänomen eingebüßt. Im Gegenteil: Das aktuelle Krisenbewusstsein sucht Halt im Konsum, der seinen Verfechtern noch immer als Modell demokratischer Teilhabe an gesellschaftlicher Produktion gilt. Zugleich ist die Konsumkritik der 1960er Jahre in Richtung eines intelligenten und nachhaltigen Konsums weitergeführt worden, und selbstbewusste Konsumenten treten nun als emanzipierte »Prosumer« und Mitakteure des Marktes auf. Das Buch entwickelt aus Sicht von Design, Kunst, Soziologie, Marketing und Medien neue Perspektiven auf das Phänomen Konsum.
Mit freundlicher Genehmigung der Autoren und des Oldenbourg Industrieverlags https://www.oldenbourg-industrieverlag.de/de/9783835633223-33223 erschienen als Beitrag im Tagungsband zur AALE-Tagung 2012. 9. Fachkonferenz 4.-5. Mai 2012, Aachen, Fachhochschule. ISBN 9783835633223 S 6-2. S. 165-174 Zusammenfassung der Autoren: "Abschließend kann festgehalten werden, dass die gesamten durchgeführten Überlegungen von den Messergebnissen der Inbetriebnahme positiv bestätigt werden. Es wird durch diese Topologie eine maximale Systemverfügbarkeit garantiert und die Zellen werden optimal betrieben. Ein Blick in die Zukunft für dieses Projekt zeigt viele Erweiterungs- und Optimierungsaufgaben. So muss der DC/DC-Wandler für einen bidirektionalen Betrieb erweitert werden, um einen Rekuperationsbetrieb zu gewährleisten bzw. die Zellen laden zu können. Dadurch können gleichzeitig die Gleichrichterdioden im Sekundärleistungsteil durch IGBTs oder MOSFETs ersetzt werden. Die voll funktionsfähige Version des DC/DC-Wandlers könnte höchstwahrscheinlich direkt auf die Anschlusspole der Zelle montiert werden, wodurch das Gewicht gesenkt wird. Durch die verringerte Verlustleistung in den Zuleitungen könnte der Wirkungsgrad noch einmal gesteigert werden.
Der Deutsche Bundestag und Bundesrat haben am 2.3.2012 bzw. 30.3.2012 das Gesetz gegen Kostenfallen im Internet verabschiedet, das am 1.8.2012 in Kraft treten wird. Hiermit hat der deutsche Gesetzgeber einen ersten Schritt getan, um die neue EU-Verbraucherrechterichtlinie vom 25.10.2011 (2011/83/EU, ABl L 304/64) in nationales Recht umzusetzen. Mit dieser Umsetzung ist das drängendste Problem der Kosten- und Abo-Fallen im elektronischen Geschäftsverkehr aus dem Gesamtpaket der Verbraucherrechterichtlinie herausgelöst und in dem neugefassten § 312g BGB behandelt worden. Eile bei der Umsetzung war hier geboten, weil unseriöse Unternehmen im elektronischen Rechtsverkehr zunehmend und in großem Umfang gegenüber ihren Kunden durch irreführende Gestaltungen ihrer Internetseiten verschleiern, dass die angebotenen Leistungen entgeltpflichtig sind.
This contribution discusses the utilization of RF power in an MRI system with RF mode shimming which enables the superposition of circularly polarized modes of a transmit RF coil array driven by a Butler matrix. Since the required power for the individual modes can vary widely, mode-shimming can result in a significant underutilization of the total available RF power. A variable power combiner (VPC) is proposed to improve the power utilization: it can be realized as a reconfiguration of the MRI transmit system by the inclusion of one additional matrix network which receives the power from all transmit amplifiers at its input ports and provides any desired (combined) power distribution at its output ports by controlling the phase and amplitude of the amplifiers’ input signals. The power distribution at the output ports of the VPC is then fed into the “mode” ports of the coil array Butler matrix in order to superimpose the spatial modes at the highest achievable power utilization. The VPC configuration is compared to the standard configuration of the transmit chain of our MRI system with 8 transmit channels and 16 coils. In realistic scenarios, improved power utilization was achieved from 17% to 60% and from 14% to 55% for an elliptical phantom and a region of interest in the abdomen, respectively, and an increase of the power utilization of 1 dB for a region of interest in the upper leg. In general, it is found that the VPC allows significant improvement in power utilization when the shimming solution demands only a few modes to be energized, while the technique can yield loss in power utilization in cases with many modes required at high power level.
If we think about applications for modern Power MOSFETs using trench technology, running them in linear mode may not be top of the priority list. Yet there are multiple uses for Trench Power MOSFETs in linear mode. In fact, even turning the device on and off in switching applications is a form of linear operation. Also, these components can be run in linear mode to protect the device against voltage surges. This article will illustrate the factors that need to be considered for linear operation and show how Trench Power MOSFETs are suited to it.
Mit freundlicher Genehmigung der Autoren und des Oldenbourg Industrieverlags https://www.oldenbourg-industrieverlag.de/de/9783835633223-33223 erschienen als Beitrag im Tagungsband zur AALE-Tagung 2012. 9. Fachkonferenz 4.-5. Mai 2012, Aachen, Fachhochschule. ISBN 9783835633223 S 2-1 S. 37-46 Original-Abstract der Autoren: "Dieser Artikel beschreibt eine universelle Programmierschnittstelle zur Entwicklung von Motion-Logic Applikationen für industrielle Motion-Controller. Sie ermöglicht die Entwicklung von Software mit modernen Hochsprachen, wie C/C++. Visual Basic, C#, Java, Objective-Cund visuellen Programmiersprachen, wie LabVIEW in Koexistenz mit klassischen Programmiersprachen für speicherprogrammierbare Steuerungen nach IEC 61131-3. Daraus ergeben sich neue Möglichkeiten industrielle Antriebs- und Steuerungssysteme mit ihrem IT-Umfeld zu verbinden."
N,N-Dialkylamino(thiocarbonyl)-N′-picolylbenzamidines react with (NEt4)2[M(CO)3X3] (M = Re, X = Br; M = Tc, X = Cl) under formation of neutral [M(CO)3L] complexes in high yields. The monoanionic NNS ligands bind in a facial coordination mode and can readily be modified at the (CS)NR1R2 moiety. The complexes [99Tc(CO)3(LPyMor)] and [Re(CO)3(L)] (L = LPyMor, LPyEt) were characterized by X-ray diffraction. Reactions of [99mTc(CO)3(H2O)3]+ with the N′-thiocarbamoylpicolylbenzamidines give the corresponding 99mTc complexes. The ester group in HLPyCOOEt allows linkage between biomolecules and the metal core.
Climate change is challenging forestry management and practices. Among other things, tree species with the ability to cope with more extreme climate conditions have to be identified. However, while environmental factors may severely limit tree growth or even cause tree death, assessing a tree species' potential for surviving future aggravated environmental conditions is rather demanding. The aim of this study was to find a tree-ring-based method suitable for identifying very drought-tolerant species, particularly potential substitute species for Scots pine (Pinus sylvestris L.) in Valais. In this inner-Alpine valley, Scots pine used to be the dominating species for dry forests, but today it suffers from high drought-induced mortality. We investigate the growth response of two native tree species, Scots pine and European larch (Larix decidua Mill.), and two non-native species, black pine (Pinus nigra Arnold) and Douglas fir (Pseudotsuga menziesii Mirb. var. menziesii), to drought. This involved analysing how the radial increment of these species responded to increasing water shortage (abandonment of irrigation) and to increasingly frequent drought years. Black pine and Douglas fir are able to cope with drought better than Scots pine and larch, as they show relatively high radial growth even after irrigation has been stopped and a plastic growth response to drought years. European larch does not seem to be able to cope with these dry conditions as it lacks the ability to recover from drought years. The analysis of trees' short-term response to extreme climate events seems to be the most promising and suitable method for detecting how tolerant a tree species is towards drought. However, combining all the methods used in this study provides a complete picture of how water shortage could limit species.
Die Veränderungen des Telekommunikationsmarktes haben in der Praxis zu einer Vielzahl von Transformationsprojekten geführt. Was gehört aber zu einem “Transformationsprojekt”, welche Prozesse und Systeme werden verändert? Zur Beantwortung dieser Frage haben wir 184 Berichte zu Projekten analysiert, die als "Transformationsprojekte" bezeichnet waren. Für die Analyse haben wir einen Kodierungsrahmen konzipiert und anhand dessen die Berichte mit einem hierarchischen Clustering-Verfahren in Themen gruppiert. Die Ergebnisse liefern Hinweise über die in der Praxis gesetzten Schwerpunkte und Prioritäten. Sie können
somit als Unterstützung für Unternehmen dienen, die ein Transformationsprojekt planen. Sie weisen zudem darauf hin, in welchen Bereichen eines Unternehmens Unterstützung durch wissenschaftlich erprobte Werkzeuge und Modelle nötig ist.
This paper describes the implementation of topographic curvature effects within the RApid Mass MovementS (RAMMS) snow avalanche simulation toolbox. RAMMS is based on a model similar to shallow water equations with a Coulomb friction relation and the velocity dependent Voellmy drag. It is used for snow avalanche risk assessment in Switzerland. The snow avalanche simulation relies on back calculation of observed avalanches. The calibration of the friction parameters depends on characteristics of the avalanche track. The topographic curvature terms are not yet included in the above mentioned classical model. Here, we fundamentally improve this model by mathematically and physically including the topographic curvature effects. By decomposing the velocity dependent friction into a topography dependent term that accounts for a curvature enhancement in the Coulomb friction, and a topography independent contribution similar to the classical Voellmy drag, we construct a general curvature dependent frictional resistance, and thus propose new extended model equations. With three site-specific examples, we compare the apparent frictional resistance of the new approach, which includes topographic curvature effects, to the classical one. Our simulation results demonstrate substantial effects of the curvature on the flow dynamics e.g., the dynamic pressure distribution along the slope. The comparison of resistance coefficients between the two models demonstrates that the physically based extension presents an improvement to the classical approach. Furthermore a practical example highlights its influence on the pressure outline in the run out zone of the avalanche. Snow avalanche dynamics modeling natural terrain curvature centrifugal force friction coefficients.
s the magnetic field strength and therefore the operational frequency in MRI are increased, the radiofrequency wavelength approaches the size of the human head/body, resulting in wave effects which cause signal decreases and dropouts. Especially, whole-body imaging at 7 T and higher is therefore challenging. Recently, an acquisition scheme called time-interleaved acquisition of modes has been proposed to tackle the inhomogeneity problems in high-field MRI. The basic premise is to excite two (or more) different Burn:x-wiley:07403194:media:MRM23081:tex2gif-stack-1 modes using static radiofrequency shimming in an interleaved acquisition, where the complementary radiofrequency patterns of the two modes can be exploited to improve overall signal homogeneity. In this work, the impact of time-interleaved acquisition of mode on image contrast as well as on time-averaged specific absorption rate is addressed in detail. Time-interleaved acquisition of mode is superior in Burn:x-wiley:07403194:media:MRM23081:tex2gif-stack-2 homogeneity compared with conventional radiofrequency shimming while being highly specific absorption rate efficient. Time-interleaved acquisition of modes can enable almost homogeneous high-field imaging throughout the entire field of view in PD, T2, and T2*-weighted imaging and, if a specified homogeneity criterion is met, in T1-weighted imaging as well.
Im Rahmen des Exzellenzclusters „Integrative Produktionstechnik für Hochlohnländer“ der RWTHAachen University werden derzeit alternative Verfahren zur Herstellung von Metall/Kunststoff- Verbindungen untersucht. Eines davon ist das thermische Direktfügen, das eine stoffschlüssige Verbindung zwischen Kunststoff und Metall ermöglicht und ohne die Verwendung von Klebstoffen, Haftvermittlern oder mechanischen Verbindungshilfen auskommt.
Thermodynamic stability, configurational motions and internal forces of haemoglobin (Hb) of three endotherms (platypus, Ornithorhynchus anatinus; domestic chicken, Gallus gallus domesticus and human, Homo sapiens) and an ectotherm (salt water crocodile, Crocodylus porosus) were investigated using circular dichroism, incoherent elastic neutron scattering and coarse-grained Brownian dynamics simulations. The experimental results from Hb solutions revealed a direct correlation between protein resilience, melting temperature and average body temperature of the different species on the 0.1 ns time scale. Molecular forces appeared to be adapted to permit conformational fluctuations with a root mean square displacement close to 1.2 Å at the corresponding average body temperature of the endotherms. Strong forces within crocodile Hb maintain the amplitudes of motion within a narrow limit over the entire temperature range in which the animal lives. In fully hydrated powder samples of human and chicken, Hb mean square displacements and effective force constants on the 1 ns time scale showed no differences over the whole temperature range from 10 to 300 K, in contrast to the solution case. A complementary result of the study, therefore, is that one hydration layer is not sufficient to activate all conformational fluctuations of Hb in the pico- to nanosecond time scale which might be relevant for biological function. Coarse-grained Brownian dynamics simulations permitted to explore residue-specific effects. They indicated that temperature sensing of human and chicken Hb occurs mainly at residues lining internal cavities in the β-subunits.
This thesis introduces the Integrated Emitter Turn-Off (IETO) Thyristor as a new high-power device. Known state-of-the-art research activities like the Dual GCT, the ETO thyristor and the ICT were presented and critically reviewed. A comparison with commercialized solutions identifies the pros and cons of each type of device family. Based on this analysis, the IETO structure is proposed, covering most benefits of each device class. In particular the combination of a MOS-assisted turn-off with a thyristor-based device allows a voltage-controlled MOS switching and the low on-state voltage of the thyristors. The following synthesis of an IETO device stands on a three-dimensional field of optimization spanned by electric, mechanical and thermal aspects. From an electric point of view, the lowest possible parasitic inductance and resistance within the commutation path are optimization criteria. The mechanical construction has to withstand the required contact pressure of multiple kilo Newtons. Finally, thermal borders limit the maximum average current of the device. FEM simulations covering these three aspects are performed for several design proposals. An IETO prototype is constructed and measurements on various test benches attest thermal, mechanical and electric performance. A local decoupling of the external driver stage and the presspack housing is presented by a cable connection. This separation enables a thermal and mechanical independence, which is advantageous in terms of vibrations and thermal cycles including increased reliability. The electric pulse performance of the prototype device is a factor of 3.1 above today''s solutions. In single-pulse measurements, a current up to 1600 A was successfully turned off at 115°C with an active silicon area of 823 mm². One reason for this increased turn-off capability is the extremely low-inductive construction. Additional functionality of the IETO thyristor like over-current self-protection and defined short-circuit failure state are successfully verified.
In the introduction to their book "What is philosophy?" Gilles Deleuze and Felix Guattari deplore the inflationary and trivialised use of the term concept: "Finally, the most shameful moment came when computer science, marketing, design and advertising, all the disciplines of communication, seized hold of the word concept itself and said: 'This is our concern, we are the creative ones, we are the ideas men! We are the friends of the concept, we put in our computers.' " This doctoral thesis shares the concern of Gilles Deleuze and Felix Guattari, but still, it is a thesis in architecture and thus collocated within the field of the representatives of the "ideas men". It engages in architectural design theory, and refers in particular to the investigation of methodological approaches within the design process. Therefore, the thesis will not contribute to the philosophical dimension of the term, but intends to overcome its imprecise use within the architectural discourse, in compliance with Eugène Viollet-le-Duc's admonition relative to vague definitions: "Dans les arts, et dans l'architecture en particulier, les définitions vagues ont causé bien des erreurs, ont laissé germer bien des préjugés, enraciner bien des idées fausses. On met un mot en avant, chacun y attache un sens différent." The term concept in architecture is very often used as pure marketing collateral, it serves to sell an idea, a product, a design. Its functional applicability is reduced to a special manner of illustration, produced as one of the various design presentation documents at the end of the design process. In contrast, the original contribution of this thesis aims to give a precise, instrumental dimension to the term concept: the concept is the expression of a specific logic, capable to guide the decisional sequences of the process and thus to improve the quality of the designed projects. The motivation to define a specific instrumentality of the concept is closely connected to the issue of interdisciplinarity in the architects’ profession. The interdisciplinary character of the architectural field is widely accepted and discussed as such, but the thesis intends to give a more precise definition of the various kinds of competences involved by classifying them into either the internal or the external group. The traditional notion of interdisciplinarity, predominantly seen as collaboration between architects and technical experts, and, most notably, the historical, sometimes contentious, relationship between architects and engineers is described. Referring to recent developments, the transformation of the architect’s role within the professional sphere, marked by an increasing importance of diverse influences and linked to a growing risk of marginalisation, is illustrated. The thesis describes different ways to adapt to this specific kind of interdisciplinarity, which generally requires the architect’s ability to connect and to integrate various contents, different points of view and diverse scales. On the other hand, the big potential which is implicit in the interdisciplinary field is exposed: architects can inform their core competence, the design, by extracting contents of different disciplinary competences, pertaining or not pertaining to their own professional field. They have the possibility to cross fields of external competences in a selective way and by doing so they can build up a corpus of knowledge capable to generate and communicate guidelines and systematic methodologies for their design. At the end, the analysis of these two aspects allows the definition of a more specific professional profile of the architect as specialist of interdisciplinarity. The thesis is concerned with the theories around the design process. The design process is seen as open to inspection and critical evaluation, with major focus on the decisional sequences which characterise it. It concentrates on the process’ descriptiveness and the degree of self-conscious approaches applied within it. The importance of regulative, strategic mechanisms is illustrated by testimonies taken from a series of design researches and leads to the functional definition of the figure of the concept as representation of a coherent set of ideas, as generator of a project-specific system of rules and as communicator of decisional strategies. The concept's function is furthermore defined as communicative interface which generates and transmits the system of rules authoritative for all the disciplinary competences involved in the design process, a communicative interface which constitutes a basis of shared convictions capable to increase the efficiency of collaboration. Furthermore, the concept's capacity to explore and elaborate the contents of external disciplines is identified as a possible methodological approach to innovative design thinking. The approach to a specific functional definition of the concept is continued by the description of a series of instruments that are simultaneously generating and communicating it. It is outlined to which degree the concept itself is already the result of an ideational process, collocated within the initial phase of the design proceedings, serving as a guideline to them, but still continuously evolving and adapting in its progression. In addition, it is illustrated how all the diverse instruments of the concept are operational media through which the knowledge transition between different disciplines can occur. The considerations about the concept as operational instrument of design are elaborated with regard to a number of examples of didactical applications that are particularly involved in the development and teaching of specific design methods. These examples illustrate the interrelations between design theory and design education. They are derived from very different schools of architecture and diverse mindsets, but all of them transmit models of conceptual design thinking.
Temperature-dependent ranges of coexistence in a model of a two-prey-one-predator microbial food web
(2012)
The objective of our study was to analyze the effects of temperature on the population dynamics of a three-species food web consisting of two prey bacteria (Pedobacter sp. and Acinetobacter johnsonii) and a protozoan predator (Tetrahymena pyriformis) as model organisms. We assessed the effects of temperature on the growth rates of all three species with the objective of developing a model with four differential equations based on the experimental data. The following hypotheses were tested at a theoretical level: Firstly, temperature changes can affect the dynamic behavior of a system by temperature-dependent parameters and interactions and secondly, food web response to temperature cannot be derived from the single species temperature response. The main outcome of the study is that temperature changes affect the parameter range where coexistence is possible within all three species. This has significant consequences on our ideas regarding the evaluation of effects of global warming.
Technisches Zeichnen : Lösungsvorschläge für das Selbststudium. (Berichte aus dem Maschinenbau)
(2012)
Chelate stabilization of a titanium(IV)–salan alkoxide by ligand exchange with 2,6-pyridinedicarboxylic acid (dipic) resulted in heptacoordinate complex 3 which is not redox-active, stable on silica gel and has increased aqueous stability. 3 is highly toxic in HeLa S3 and Hep G2 and has enhanced antitumor efficacy in a mouse cervical-cancer model.
Biodiversity and the coexistence of species have puzzled and fascinated biologists since decades and is a hotspot in todays’ natural sciences. Preserving this biodiversity is a great challenge as habitats and environments underlying tremendous changes like climate change and the loss of natural habitats, which are mainly due to anthropogenic influences. The coexistence of numerous species even in homogeneous environments is a stunning feature of natural communities and has been summarized under the term ‘paradox of plankton’. Up to now, there are several mechanisms discussed, which may contribute to local and global diversity of organisms. Several interspecific trade offs have been identified maintaining the coexistence of species like their abilities regarding competition and predator avoidance, their capability to disperse in space and time, and their ability to exploit variable resources. Further, micro-evolutionary dynamics supporting the coexistence of species have been added to our knowledge, and deriving from theoretical deterministic models, non-linear dynamics which describe the temporal fluctuation of abundances of organisms. Whereas competition and predation seem to be clue structural elements within interacting organisms, the intrinsic dynamic behavior – by means of temporal changes in abundance - plays an important role regarding coexistence within a community. The present work sheds light on different factors affecting the coexistence of species using experimental microbial model systems consisting of a bacterivorous ciliate as the predator and two bacteria strains as prey organism. Additionally, another experimental setup consisting of two up to five bacteria species competing for one limiting resource was investigated. Highly controllable chemostat systems were established to exclude extrinsic disturbances. According to theoretical analyses I was able to show - experimentally and theoretically - that phenotypic plasticity of one species within a microbial one-predator-two-prey food web enlarges the range of possible coexistence of all species under different dynamic conditions, compared to a food web without phenotypic plasticity. This was accompanied by non-linear (chaotic) population dynamics within all experimental systems showing phenotypic plasticity. The experiments on the interplay of competition, predation and invasion showed that all aspects have an influence on species coexistence. Under undisturbed controlled conditions all aspects were analyzed in detail and in combination. Populations showed oscillations which were shown by quasi-chaotic attractors in phase space diagrams. Competition experiments with two up to five bacteria species competing for one limiting resource showed that all organisms were able to coexist which was mediated by species oscillations entering a regime of chaos. Besides that fact it was found, that the productivity (biomass) as well as the total cell numbers – under the same nutrition supply – increased by an increasing number of species in the experimental systems. Up to now, the occurrence of non-linear dynamics in well controlled experimental studies has been recognized several times and this phenomenon seemed to be more common in natural systems than generally assumed.
Die Hochgradientenmagnetseparation (HGMS) ist eine Methode zur Aufreinigung von biopharmazeutischen Produkten. Mit dieser Methode lässt sich in nur einem Schritt eine Fest/Fest/Flüssig-Trennung erzielen, was zu einer erheblichen Zeit- und Kostenersparnis im Downstreaming führt. Dennoch steht ihr industrieller Einsatz noch aus, was u. a. am Mangel an Analysenmethoden liegt, um die HGMS quantifizierbar zu machen. Gerade in der Pharmaproduktion werden Prozesse gebraucht, die gemäß den einschlägigen Vorschriften (cGMP) validiert und deren verfahrenstechnische Anlagenteile qualifiziert werden können. Die Schwierigkeit ist die Messung der magnetischen Mikrosorbentien in der Suspension, in der auch Zellen oder Zelltrümmer vorliegen. Im Rahmen eines Forschungsprojektes im „Zentralen Innovationsprogramm Mittelstand“ des BMWi wurden verschiedene Analysenmethoden untersucht. Die Durchflusszytometrie ermöglicht eine Charakterisierung von Partikeln und eine simultane quantitative Messung. Durch die multiparametrige Messung kann zwischen Zellen, Zelltrümmern und Magnetpartikeln unterschieden werden. Die At-line-Einbindung des Durchflusszytometers ist durch den Einsatz einer externen Pumpe möglich. Über eine automatisierte Messwertanalyse kann der HGMS-Prozess mittels der Durchflusszytometrie gesteuert werden.
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.
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.
Stahlbetonbau
(2012)
Die bauaufsichtliche Einführung der Eurocodes steht unmittelbar bevor. Für den Bereich des Stahl- und Spannbetonbaus soll die Anwendung zum 1. Juli 2012 verbindlich sein, d. h. mit diesem Stichtag sollte nur noch der Eurocode 2 (DIN EN 1992-1-1, Ausgabe Januar 2011) mit seinem zugehörigen nationalen Anhang (DIN EN 1992-1-1/NA, Ausgabe Januar 2011) Verwendung finden, die DIN 1045-1 wird zurückgezogen. Bereits seit März 2010 gilt eine Übergangsphase, ist der die Anwendung des Eurocodes alternativ zur DIN 1045-1 als bauaufsichtlich gleichwertige Lösung möglich.
Stahlbau
(2012)
Stahlbau
(2012)
Smartphone Forensik
(2012)
Mit freundlicher Genehmigung der Autoren und des Oldenbourg Industrieverlags https://www.oldenbourg-industrieverlag.de/de/9783835633223-33223 erschienen als Beitrag im Tagungsband zur AALE-Tagung 2012. 9. Fachkonferenz 4.-5. Mai 2012, Aachen, Fachhochschule. ISBN 9783835633223 S 5-1 S. 127-135 Es werden Ergebnisse unterschiedlicher Projekte aus dem Bereich der Simulation von Wärmeübertragungsprozessen mit Excel-VBA vorgestellt. - Thermische Behandlung hochviskoser Fruchtzubereitungen, verschiedene Projekte und Kooperationen mit der Zentis GmbH & Co. KG, Aachen (J. Becker, U. Feuerriegel, G. Wersch). - Untersuchung des dynamischen Verhaltens von dampfbeheizten Ethylen-Verdampfern. Projekt mit der TGE Gas Engineering GmbH, Bonn (M. Ecker, U. Feuerriegel, U. Hoffmann, S. Wittenhorst). - Dynamische Simulation des axialen Temperaturverlaufs von elektrisch beheizten Rohrreaktoren. Kooperation mit dem Institut für Chemische Verfahrenstechnik, TU Clausthal (U. Feuerriegel, U. Kunz, M. Pook, S. Wittenhorst).
The interest in PET detectors with monolithic block scintillators is growing. In order to obtain high spatial resolutions dedicated positioning algorithms are required. But even an ideal algorithm can only deliver information which is provided by the detector. In this simulation study we investigated the light distribution on one surface of cuboid LSO scintillators of different size. Scintillators with a large aspect ratio (small footprint and large height) showed significant position information only for a minimum interaction depth of the gamma particle. The results allow a quantitative estimate for a useful aspect ratio.
The Volatility Framework is a collection of tools for the analysis of computer RAM. The framework offers a multitude of analysis options and is used by many investigators worldwide. Volatility currently comes with a command line interface only, which might be a hinderer for some investigators to use the tool. In this paper we present a GUI and extensions for the Volatility Framework, which on the one hand simplify the usage of the tool and on the other hand offer additional functionality like storage of results in a database, shortcuts for long Volatility Framework command sequences, and entirely new commands based on correlation of data stored in the database.
Siedlungswasserwirtschaft
(2012)
Siedlungswasserwirtschaft
(2012)
Sensitivity of phase detection techniques in aerated chute flows to hydraulic design parameters
(2012)
Selective laser melting of metals: desktop machines open up new chances even for small companies
(2012)
Additive manufacturing (AM) of metal parts by using Selective Laser Melting (SLM) has become a powerful tool mostly in the area of automotive, aerospace engineering and others. Especially in the field of dentistry, jewelry and related branches that require individualized or even one-of-a-kind products, the direct digital manufacturing process opens up new ways of design and manufacturing. In these fields, mostly small and medium sized businesses (SME) are operating which do not have sufficient human and economic resources to invest in this technology. But to stay competitive, the application of AM can be regarded as a necessity. In this situation a new desktop machine (Realizer SLM 50) was introduced that cost about 1/3 of a shop floor SLM machine and promises small quality parts. To find out whether the machine really is an alternative for SMEs the University of Applied Science, Aachen, Germany, designed, build and optimized typical parts from the dentistry and the jewelry branches using CoCr and silver material, the latter being new with this application. The paper describes the SLM procedure and how to find and optimize the most important parameters. The test is accompanied by digital simulation in order to verify the build parameters and to plan future builds. The procedure is shown as well as the resulting parts made from CoCr and silver material.
As part of a novel approach to automatic sewer inspection, this paper presents a robust algorithm for automatic flow line detection. A large image repository is obtained from about 50,000 m sewers to represent the high variability of real world sewer systems. Automatic image processing combines Canny edge detection, Hough transform for straight lines and cost minimization using Dijkstra's shortest path algorithm. Assuming that flow lines are mostly smoothly connected horizontal structures, piecewise flow line delineation is reduced to a process of selecting adjacent line candidates. Costs are derived from the gap between adjacent candidates and their reliability. A single parameter α enables simple control of the algorithm. The detected flow line may precisely follow the segmented edges (α = 0.0) or minimize gaps at joints (α = 1.0). Both, manual and ground truth-based analysis indicate that α = 0.8 is optimal and independent of the sewer's material. The algorithm forms an essential step to further automation of sewer inspection.
Risiken des Handels
(2012)
All cells generate contractile tension. This strain is crucial for mechanically controlling the cell shape, function and survival. In this study, the CellDrum technology quantifying cell's (the cellular) mechanical tension on a pico-scale was used to investigate the effect of lipopolysaccharide (LPS) on human aortic endothelial cell (HAoEC) tension. The LPS effect during gram-negative sepsis on endothelial cells is cell contraction causing endothelium permeability increase. The aim was to finding out whether recombinant activated protein C (rhAPC) would reverse the endothelial cell response in an in-vitro sepsis model. In this study, the established in-vitro sepsis model was confirmed by interleukin 6 (IL-6) levels at the proteomic and genomic levels by ELISA, real time-PCR and reactive oxygen species (ROS) activation by florescence staining. The thrombin cellular contraction effect on endothelial cells was used as a positive control when the CellDrum technology was applied. Additionally, the Ras homolog gene family, member A (RhoA) mRNA expression level was checked by real time-PCR to support contractile tension results. According to contractile tension results, the mechanical predominance of actin stress fibers was a reason of the increased endothelial contractile tension leading to enhanced endothelium contractility and thus permeability enhancement. The originality of this data supports firstly the basic measurement principles of the CellDrum technology and secondly that rhAPC has a beneficial effect on sepsis influenced cellular tension. The technology presented here is promising for future high-throughput cellular tension analysis that will help identify pathological contractile tension responses of cells and prove further cell in-vitro models.
Prioritization is an essential task within requirements engineering to cope with complexity and to establish focus properly. The 3rd Workshop on Requirements Prioritization for customer oriented Software Development (RePriCo’12) focused on requirements prioritization and adjacent themes in the context of customer oriented development of bespoke and standard software. Five submissions have been accepted for the proceedings and for presentation. The report summarizes and points out key findings.
The radio-based wireless data communication has made the realization of new technical solutions possible in many fields of the automation technology (AT). For about ten years, a constant disproportionate growth of wireless technologies can be observed in the automation technology.
However, it shows that especially for the AT, conventional technologies of office automation are unsuitable and/or not manageable. The employment of mobile services in the industrial automation technology has the potential of significant cost and time savings. This leads to an increased productivity in various fields of the AT, for example in the factory and process automation or in production logistics. In this paper technologies and solutions for an automation-suited supply of mobile wireless services will be introduced under the criteria of real time suitability, IT-security and service orientation.
Emphasis will be put on the investigation and development of wireless convergence layers for different radio technologies, on the central provision of support services for an easy-to-use, central, backup enabled management of combined wired / wireless networks and on the study on integrability in a Profinet real-time Ethernet network.
Realisation of a calorimetric gas sensor on polyimide foil for applications in aseptic food industry
(2012)
A calorimetric gas sensor is presented for the monitoring of vapour-phase H2O2 at elevated temperature during sterilisation processes in aseptic food industry. The sensor was built up on a flexible polyimide foil (thickness: 25 μm) that has been chosen due to its thermal stability and low thermal conductivity. The sensor set-up consists of two temperature-sensitive platinum thin-film resistances passivated by a layer of SU-8 photo resist and catalytically activated by manganese(IV) oxide. Instead of an active heating structure, the calorimetric sensor utilises the elevated temperature of the evaporated H2O2 aerosol. In an experimental test rig, the sensor has shown a sensitivity of 4.78 °C/(%, v/v) in a H2O2 concentration range of 0%, v/v to 8%, v/v. Furthermore, the sensor possesses the same, unchanged sensor signal even at varied medium temperatures between 210 °C and 270 °C of the gas stream. At flow rates of the gas stream from 8 m3/h to 12 m3/h, the sensor has shown only a slightly reduced sensitivity at a low flow rate of 8 m3/h. The sensor characterisation demonstrates the suitability of the calorimetric gas sensor for monitoring the efficiency of industrial sterilisation processes.
This article describes the functionality of a MATLAB® library that can be used to develop motion-logic applications in MATLAB programming language for industrial drive and control systems using the well known sercos automation bus. Therewith MATLAB's functionality is extended to designing automation applications from single axis machines up to multi-kinematic robots.