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Application of the optical flow method to velocity determination in hydraulic structure models
(2016)
As with most high-velocity free-surface flows, stepped spillway flows become self-aerated when the drop height exceeds a critical value. Due to the step-induced macro-roughness, the flow field becomes more turbulent than on a similar smooth-invert chute. For this reason, cascades are oftentimes used as re-aeration structures in wastewater treatment. However, for stepped spillways as flood release structures downstream of deoxygenated reservoirs, gas transfer is also of crucial significance to meet ecological requirements. Prediction of mass transfer velocities becomes challenging, as the flow regime differs from typical previously studied flow conditions. In this paper, detailed air-water flow measurements are conducted on stepped spillway models with different geometry, with the aim to estimate the specific air-water interface. Re-aeration performances are determined by applying the absorption method. In contrast to earlier studies, the aerated water body is considered a continuous mixture up to a level where 75% air concentration is reached. Above this level, a homogenous surface wave field is considered, which is found to significantly affect the total air-water interface available for mass transfer. Geometrical characteristics of these surface waves are obtained from high-speed camera investigations. The results show that both the mean air concentration and the mean flow velocity have influence on the mass transfer. Finally, an empirical relationship for the mass transfer on stepped spillway models is proposed.
Optical flow estimation is known from Computer Vision where it is used to determine obstacle movements through a sequence of images following an assumption of brightness conservation. This paper presents the first study on application of the optical flow method to aerated stepped spillway flows. For this purpose, the flow is captured with a high-speed camera and illuminated with a synchronized LED light source. The flow velocities, obtained using a basic Horn–Schunck method for estimation of the optical flow coupled with an image pyramid multi-resolution approach for image filtering, compare well with data from intrusive conductivity probe measurements. Application of the Horn–Schunck method yields densely populated flow field data sets with velocity information for every pixel. It is found that the image pyramid approach has the most significant effect on the accuracy compared to other image processing techniques. However, the final results show some dependency on the pixel intensity distribution, with better accuracy found for grey values between 100 and 150.
Optimization of the reaeration potential on embankment stepped spillways in skimming flow regime
(2008)
Optimierung des potentiellen Sauerstoffeintrags auf Treppenschussrinnen mit gemäßigter Neigung
(2009)
Sensitivity of phase detection techniques in aerated chute flows to hydraulic design parameters
(2012)
Hydraulic modeling is the classical approach to investigate and describe complex fluid motion. Many empirical formulas in the literature used for the hydraulic design of river training measures and structures have been developed using experimental data from the laboratory. Although computer capacities have increased to a high level which allows to run complex numerical simulations on standard workstation nowadays, non-standard design of structures may still raise the need to perform physical model investigations. These investigations deliver insight into details of flow patterns and the effect of varying boundary conditions. Data from hydraulic model tests may be used for calibration of numerical models as well. As the field of hydraulic modeling is very complex, this chapter intends to give a short overview on capacities and limits of hydraulic modeling in regard to river flows and hydraulic structures only. The reader shall get a first idea of modeling principles and basic considerations. More detailed information can be found in the references.
Inhaltsverzeichnis - Bachelorarbeiten
1. Testamentsgestaltung bei Patchworkfamilien – Lösungsansätze für typische
Praxisprobleme unter Berücksichtigung der Interessenlagen der Parteien
- Ronja Bundrock 4 - 58
2. Die Haftung des AG-Vorstands gegenüber der Gesellschaft in unterneh-
mensinternen und -externen Krisen
- Nico Kremers 59 - 122
3. The Relationship of the Ex-Ante Uncertainty about the Value of a Stock
and its IPO Underpricing – An Analysis of the German Market
- Lennard Pankok 123 - 179
4. Attractiveness Bias in Venture Capital – An Analysis of Investor Decision
Making in “Die Höhle der Löwen”
- Theresa Maria Weisheit 180 - 242
Inhaltsverzeichnis – Masterarbeiten
Erhöhung der Energieautarkie in der Backbranche – Anwendung von bidi-
rektionalem Laden und dessen Auswirkungen auf die Geschäftsprozesse
und Informationssysteme
- Jasper Spoede 243 - 355
Hochtemperaturtechnik
(1990)
Hochtemperaturtechnik. Interne Arbeitssitzung des GVC-Fachausschusses 'Hochtemperaturtechnik'
(1989)
Multi-interface level sensors and new development in monitoring and control of oil separators
(2006)
In the oil industry, huge saving may be made if suitable multi-interface level measurement systems are employed for effectively monitoring crude oil separators and efficient control of their operation. A number of techniques, e.g. externally mounted displacers, differential pressure transmitters and capacitance rod devices, have been developed to measure the separation process with gas, oil, water and other components. Because of the unavailability of suitable multi-interface level measurement systems, oil separators are currently operated by the trial-and-error approach. In this paper some conventional techniques, which have been used for level measurement in industry, and new development are discussed.
In Zeiten von Schnelllebigkeit ändern immer mehr Menschen bewusst ihren Umgang mit alltäglichen Dingen. Was dabei häufig in den Hintergrund rückt, ist das Thema "bewusste Kleidung". Beeinflusst durch sogenannte Fast-Fashion-Modeketten und Social Media leben wir in einer regelrechten Wegwerfgesellschaft. „Entschleunigen“ beschäftigt sich mit den Schattenseiten der Modeindustrie, zeigt aber ebenso (neue) Wege auf, die auf eine bessere Zukunft für uns und unsere Umwelt hoffen lassen. Aufgeteilt in zwei Kapitel gibt „Entschleunigen“ einen Einblick in den ökologischen und sozialen Fußabdruck der Modeindustrie und stellt zum anderen die Gegenseite vor, bei der Wert auf faire Produktion und Nachhaltigkeit gelegt wird. Das Buch „Entschleunigen“ soll über die Missstände in der Textilbranche informieren, jedoch im Umkehrschluss dazu motivieren, diese mit einfachen Mitteln zu verbessern.
Tribological performance of biodegradable lubricants under different surface roughness of tools
(2019)
Praxistransfer in der tertiären Bildungsforschung: Modelle, Gelingensbedingungen und Nachhaltigkeit
(2019)
Dieses Jahr werden allein in Deutschland ca. 47 Millionen Sneaker verkauft. Die Sneakerbranche boomt und ist nicht mehr aufzuhalten. Was zu Beginn nur ein Sportschuh war, ist heute ein Lifestyleprodukt und auf dem Markt und im Alltag nicht mehr wegzudenken. Der Hype um den neuesten Sneaker ist unglaublich groß und das Bedürfnis nach dem Präsentieren und dem zur Schau stellen wächst.
Mit der float collection gelingt es, den Verkaufs- und Ausstellungsraum ganz individuell und vielseitig zu gestalten. Das Besondere hier ist, dass die Schuhe sich visuell schwebend in den Regalen etablieren und so von allen Seiten betrachtet werden können. Das Konstrukt ist modular und bringt durch das Material Metall eine lange Produktlebensdauer mit sich.
So bringst du nicht nur die Sneaker, sondern auch die Herzen deiner Kunden zum Schweben.
Let the shoes float.
Prinzip und Anwendung der akustischen Gastemperaturmeßtechnik / Deuster, M. ; Brüssermann, Klaus
(1994)
One of the most important parameters in a burning chamber - in power stations, in waste to energy plants - is the temperature. This temperature is in the range of 700-1500 °C - one of the most advanced measuring methods being the acoustic pyrometry with the possibility of producing temperature mapping in one level of the burning chamber - comparable to computer tomography. The results of these measurements discussed in the presentation can be used - to fulfil the legal requirements in the FRG or in the EU - to equalise the temperature in one level of the burning chamber to optimise the steam production (better efficiency of the plant) and to minimise the production of temperature controlled flue gas components (NO, CO a. o.) - to control the SNCR-process if used.
The Ministry of Science and Research in North Rhine-Westphalia created eight platforms of excellence, one in the research area „Energy and Environment“ in 2002 at ACUAS. This platform concentrates the research and development of 13 professors in Jülich and Aachen and of two scientific institutes with different topics: – NOWUM-Energy with emphasis on efficient and economic energy conversion – The Solar Institute Jülich – SIJ – being the largest research institute in the field of renewables at a University of Applied Sciences in Germany With this platform each possible energy conversion – nuclear, fossil, renewable- can be dealt with to help solving the two most important problems of mankind, energy and potable water. At the CSE are presented the historical development, some research results and the combined master studies in „Energy Systems“ and „Nuclear Applications“
Das KERAMION beherbergt ein breites Sortiment an historischen Keramikstücken wie auch modernen künstlerischen Keramikarbeiten. Bei der neuen Konzeptionierung des Museums wurde eine Verbindung der historischen Sammlung und der modernen Kunst geschaffen, als Visualisierung dafür steht die eigens für das Museum erstellte Schrift. In dieser Schrift wird eine historische, schwungvolle Kurrentschrift aus dem 16. Jahrhundert mit einer modernen kantigen Serifenschrift verbunden. Daraus entsteht eine Schrift, die die Breite der Keramik widerspiegelt und von Steingut bis Porzellan alle Facetten aufgreift. Gepaart wird die einzigartige Schrift mit einem auf das Zentrum ausgerichteten Layoutprinzip, bei dem 3D Scans der Exponate in den Fokus rücken. Somit können die Besucher*innen auch von zu Hause einen Vorgeschmack auf die einzigartigen Materialien und Keramiktechniken bekommen.
Lesesessel im dänischen Stil
(2023)
Bei dem Möbel wurde Wert auf Nachhaltigkeit, Langlebigkeit und zeitloses Design gelegt. Ziel war es, ein Möbel zu entwerfen, welches bequem, minimalistisch und alltagstauglich ist. Der Sessel mit passendem Hocker besteht aus einem Holzgestell mit aufliegenden Polstern. Die Gestelle sind aus Rüsterholz mit handwerklichen Verbindungen gefertigt. Die Polster bestehen aus 10 cm dickem Schaumstoff, bezogen mit einem Chenille Möbelstoff. Durch lösbare Verbindungen und Sitzlatten, die in Austaschungen gesteckt werden, lassen sich die Möbel vom Endkunden leicht selbst aufbauen und ermöglichen einen flachen Versandkarton. Der Sessel lädt zum Entspannen und Lesen ein. Er ist bequem und gewährleistet dadurch ein stundenlanges Nutzen. „HVILE“ ein Ort der Ruhe und Eintritt in eine andere Welt.
By developing innovative solutions to social and environmental problems, sustainable ventures carry greatpotential. Entrepreneurship which focuses especially on new venture creation can be developed through education anduniversities, in particular, are called upon to provide an impetus for social change. But social innovations are associatedwith certain hurdles, which are related to the multi-dimensionality, i.e. the tension between creating social,environmental and economic value and dealing with a multiplicity of stakeholders. The already complex field ofentrepreneurship education has to face these challenges. This paper, therefore, aims to identify starting points for theintegration of sustainability into entrepreneurship education. To pursue this goal experiences from three differentproject initiatives between the partner universities: Lapland University of Applied Sciences, FH Aachen University ofApplied Sciences and Turiba University are reflected and findings are systematically condensed into recommendationsfor education on sustainable entrepreneurship.
Light-addressable potentiometric sensors (LAPS) consisting of a p-Si-SiO2 and p-Si-SiO2-Au structure, respectively, have been tested for a label-free electrical detection of DNA (deoxyribonucleic acid) hybridization. Three different strategies for immobilizing single-stranded probe DNA (ssDNA) molecules on a LAPS surface have been studied and compared: (a) immobilization of thiol-modified ssDNA on the patterned Au surface via gold-thiol bond, (b) covalent immobilization of amino-modified ssDNA onto the SiO2 surface functionalized with 3-aminopropyltriethoxysilane and (c) layer-by-layer adsorption of negatively charged ssDNA on a positively charged weak polyelectrolyte layer of poly(allylamine hydrochloride).
Miniaturized setup, compatibility with advanced micro- and nanotechnologies, and ability to detect biomolecules by their intrinsic molecular charge favor the semiconductor field-effect platform as one of the most attractive approaches for the development of label-free DNA chips. In this work, a capacitive field-effect EIS (electrolyte–insulator–semiconductor) sensor covered with a layer-by-layer prepared, positively charged weak polyelectrolyte layer of PAH (poly(allylamine hydrochloride)) was used for the label-free electrical detection of DNA (deoxyribonucleic acid) immobilization and hybridization. The negatively charged probe single-stranded DNA (ssDNA) molecules were electrostatically adsorbed onto the positively charged PAH layer, resulting in a preferentially flat orientation of the ssDNA molecules within the Debye length, thus yielding a reduced charge-screening effect and a higher sensor signal. Each sensor-surface modification step (PAH adsorption, probe ssDNA immobilization, hybridization with complementary target DNA (cDNA), reducing an unspecific adsorption by a blocking agent, incubation with noncomplementary DNA (ncDNA) solution) was monitored by means of capacitance–voltage and constant-capacitance measurements. In addition, the surface morphology of the PAH layer was studied by atomic force microscopy and contact-angle measurements. High hybridization signals of 34 and 43 mV were recorded in low-ionic strength solutions of 10 and 1 mM, respectively. In contrast, a small signal of 4 mV was recorded in the case of unspecific adsorption of fully mismatched ncDNA. The density of probe ssDNA and dsDNA molecules as well as the hybridization efficiency was estimated using the experimentally measured DNA immobilization and hybridization signals and a simplified double-layer capacitor model. The results of field-effect experiments were supported by fluorescence measurements, verifying the DNA-immobilization and hybridization event.
Capacitive field-effect electrolyte-insulator-semiconductor sensors consisting of an Al-p-Si-SiO2 structure have been used for the electrical detection of unlabelled single- and double-stranded DNA (dsDNA) molecules by their intrinsic charge. A simple functionalization protocol based on the layer-by-layer (LbL) technique was used to prepare a weak polyelectrolyte/probe-DNA bilayer, followed by the hybridization with complementary target DNA molecules. Due to the flat orientation of the LbL-adsorbed DNA molecules, a high sensor signal has been achieved. In addition, direct label-free detection of in-solution hybridized dsDNA molecules has been studied.
In this study, polyelectrolyte-modified field-effect-based electrolyte-insulator-semiconductor (EIS) devices have been used for the label-free electrical detection of double-stranded deoxyribonucleic acid (dsDNA)molecules. The sensor-chip functionalization with a positively charged polyelectrolyte layer provides the possibility of direct adsorptive binding of negatively charged target DNA oligonucleotides onto theSiO2-chip surface.EIS sensors can be utilized as a tool to detect surface-charge changes; the electrostatic adsorption of oligonucleotides onto the polyelectrolyte layer leads to a measureable surface-potential change. Signals of 39mV have been recorded after the incubation with the oligonucleotide solution. Besides the electrochemical experiments, the successful adsorption of dsDNA onto the polyelectrolyte layer has been verified via fluorescence microscopy. The presented results demonstrate that the signal recording of EISchips, which are modified with a polyelectrolyte layer, canbe used as a favorable approach for a fast, cheap and simple detection method for dsDNA.
Field-effect-based electrolyte-insulator-semiconductor (EIS) sensors were modified with a bilayer of positively charged weak polyelectrolyte (poly(allylamine hydrochloride) (PAH)) and probe single-stranded DNA (ssDNA) and are used for the detection of complementary single-stranded target DNA (cDNA) in different test solutions. The sensing mechanism is based on the detection of the intrinsic molecular charge of target cDNA molecules after the hybridization event between cDNA and immobilized probe ssDNA. The test solutions contain synthetic cDNA oligonucleotides (with a sequence of tuberculosis mycobacteria genome) or PCR-amplified DNA (which origins from a template DNA strand that has been extracted from Mycobacterium avium paratuberculosis-spiked human sputum samples), respectively. Sensor responses up to 41 mV have been measured for the test solutions with DNA, while only small signals of ∼5 mV were detected for solutions without DNA. The lower detection limit of the EIS sensors was ∼0.3 nM, and the sensitivity was ∼7.2 mV/decade. Fluorescence experiments using SybrGreen I fluorescence dye support the electrochemical results.
Thrombogenic complications are a main issue in mechanical circulatory support (MCS). There is no validated in vitro method available to quantitatively assess the thrombogenic performance of pulsatile MCS devices under realistic hemodynamic conditions. The aim of this study is to propose a method to evaluate the thrombogenic potential of new designs without the use of complex in-vivo trials. This study presents a novel in vitro method for reproducible thrombogenicity testing of pulsatile MCS systems using low molecular weight heparinized porcine blood. Blood parameters are continuously measured with full blood thromboelastometry (ROTEM; EXTEM, FIBTEM and a custom-made analysis HEPNATEM). Thrombus formation is optically observed after four hours of testing. The results of three experiments are presented each with two parallel loops. The area of thrombus formation inside the MCS device was reproducible. The implantation of a filter inside the loop catches embolizing thrombi without a measurable increase of platelet activation, allowing conclusions of the place of origin of thrombi inside the device. EXTEM and FIBTEM parameters such as clotting velocity (α) and maximum clot firmness (MCF) show a total decrease by around 6% with a characteristic kink after 180 minutes. HEPNATEM α and MCF rise within the first 180 minutes indicate a continuously increasing activation level of coagulation. After 180 minutes, the consumption of clotting factors prevails, resulting in a decrease of α and MCF. With the designed mock loop and the presented protocol we are able to identify thrombogenic hot spots inside a pulsatile pump and characterize their thrombogenic potential.
Abstractauthoren Graphene oxide (GO) nanoparticles were incorporated in temperature-sensitive Poly(N-isopropylacrylamide) (PNIPAAm) hydrogels. The nanoparticles increase the light absorption and convert light energy into heat efficiently. Thus, the hydrogels with GO can be stimulated spatially resolved by illumination as it was demonstrated by IR thermography. The temporal progression of the temperature maximum was detected for different concentrations of GO within the polymer network. Furthermore, the compatibility of PNIPAAm hydrogels with GO and cell cultures was investigated. For this purpose, culture medium was incubated with hydrogels containing GO and the viability and morphology of chinese hamster ovary (CHO) cells was examined after several days of culturing in presence of this medium.
Light-stimulated hydrogel actuators with incorporated graphene oxide for microfluidic applications
(2015)
Poly(N-isopropylacrylamide) (PNIPAAm) hydrogel films with incorporated graphene oxide (GO) were developed and tested as light-stimulated actuators. GO dispersions were synthesized via Hummers method and characterized toward their optical properties and photothermal energy conversion. The hydrogels were prepared by means of photopolymerization. In addition, the influence of GO within the hydrogel network on the lower critical solution temperature (LCST) was investigated by differential scanning calorimetry (DSC). The optical absorbance and the response to illumination were determined as a function of GO concentration for thin hydrogel films. A proof of principle for the stimulation with light was performed.