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Planning the layout and operation of a technical system is a common task
for an engineer. Typically, the workflow is divided into consecutive stages: First,
the engineer designs the layout of the system, with the help of his experience or of
heuristic methods. Secondly, he finds a control strategy which is often optimized
by simulation. This usually results in a good operating of an unquestioned sys-
tem topology. In contrast, we apply Operations Research (OR) methods to find a
cost-optimal solution for both stages simultaneously via mixed integer program-
ming (MILP). Technical Operations Research (TOR) allows one to find a provable
global optimal solution within the model formulation. However, the modeling error
due to the abstraction of physical reality remains unknown. We address this ubiq-
uitous problem of OR methods by comparing our computational results with mea-
surements in a test rig. For a practical test case we compute a topology and control
strategy via MILP and verify that the objectives are met up to a deviation of 8.7%.
Pure analytical or experimental methods can only find a control strategy for technical systems with a fixed setup. In former contributions we presented an approach that simultaneously finds the optimal topology and the optimal open-loop control of a system via Mixed Integer Linear Programming (MILP). In order to extend this approach by a closed-loop control we present a Mixed Integer Program for a time discretized tank level control. This model is the basis for an extension by combinatorial decisions and thus for the variation of the network topology. Furthermore, one is able to appraise feasible solutions using the global optimality gap.
Nahezu 100.000 denkbare Strukturen kann ein Getriebe bei gleicher Funktion aufweisen - je nach Ganganzahl und gefordertem Freiheitsgrad. Mit dem traditionellen Ansatz bei der Entwicklung, einzelne vielversprechende Systemkonfigurationen manuell zu identifizieren und zu vergleichen, können leicht innovative und vor allem kostenminimale Lösungen übersehen werden. Im Rahmen eines Forschungsprojekts hat die TU Darmstadt spezielle Optimierungsmethoden angewendet, um auch bei großen Lösungsräumen zielsicher ein für die individuellen Zielstellungen optimales Layout zu finden.
Cheap does not imply cost-effective -- this is rule number one of zeitgeisty system design. The initial investment accounts only for a small portion of the lifecycle costs of a technical system. In fluid systems, about ninety percent of the total costs are caused by other factors like power consumption and maintenance. With modern optimization methods, it is already possible to plan an optimal technical system considering multiple objectives. In this paper, we focus on an often neglected contribution to the lifecycle costs: downtime costs due to spontaneous failures. Consequently, availability becomes an issue.
Energy-efficient components do not automatically lead to energy-efficient systems. Technical Operations Research (TOR) shifts the focus from the single component to the system as a whole and finds its optimal topology and operating strategy simultaneously. In previous works, we provided a preselected construction kit of suitable components for the algorithm. This approach may give rise to a combinatorial explosion if the preselection cannot be cut down to a reasonable number by human intuition. To reduce the number of discrete decisions, we integrate laws derived from similarity theory into the optimization model. Since the physical characteristics of a production series are similar, it can be described by affinity and scaling laws. Making use of these laws, our construction kit can be modeled more efficiently: Instead of a preselection of components, it now encompasses whole model ranges. This allows us to significantly increase the number of possible set-ups in our model. In this paper, we present how to embed this new formulation into a mixed-integer program and assess the run time via benchmarks. We present our approach on the example of a ventilation system design problem.
On obligations in the development process of resilient systems with algorithmic design methods
(2018)
Advanced computational methods are needed both for the design of large systems and to compute high accuracy solutions. Such methods are efficient in computation, but the validation of results is very complex, and highly skilled auditors are needed to verify them. We investigate legal questions concerning obligations in the development phase, especially for technical systems developed using advanced methods. In particular, we consider methods of resilient and robust optimization. With these techniques, high performance solutions can be found, despite a high variety of input parameters. However, given the novelty of these methods, it is uncertain whether legal obligations are being met. The aim of this paper is to discuss if and how the choice of a specific computational method affects the developer’s product liability. The review of legal obligations in this paper is based on German law and focuses on the requirements that must be met during the design and development process.
Algorithmic design and resilience assessment of energy efficient high-rise water supply systems
(2018)
High-rise water supply systems provide water flow and suitable pressure in all levels of tall buildings. To design such state-of-the-art systems, the consideration of energy efficiency and the anticipation of component failures are mandatory. In this paper, we use Mixed-Integer Nonlinear Programming to compute an optimal placement of pipes and pumps, as well as an optimal control strategy.Moreover, we consider the resilience of the system to pump failures. A resilient system is able to fulfill a predefined minimum functionality even though components fail or are restricted in their normal usage. We present models to measure and optimize the resilience. To demonstrate our approach, we design and analyze an optimal resilient decentralized water supply system inspired by a real-life hotel building.
Digital twins enable the modeling and simulation of real-world entities (objects, processes or systems), resulting in improvements in the associated value chains. The emerging field of quantum computing holds tremendous promise forevolving this virtualization towards Quantum (Digital) Twins (QDT) and ultimately Quantum Twins (QT). The quantum (digital) twin concept is not a contradiction in terms - but instead describes a hybrid approach that can be implemented using the technologies available today by combining classicalcomputing and digital twin concepts with quantum processing. This paperpresents the status quo of research and practice on quantum (digital) twins. It alsodiscuses their potential to create competitive advantage through real-timesimulation of highly complex, interconnected entities that helps companies better
address changes in their environment and differentiate their products andservices.
In den letzten 1.5 Jahren haben wir sehr deutlich gemerkt, dass es den Klimawandel wirklich gibt - ein Virus, welches unsere gesamte Welt auf links dreht, Überschwemmungskatastrophen, extreme Temperaturschwankungen, etc. Es ist also Zeit etwas zu verändern, es ist Zeit aktiv hinzusehen und zu handeln - bewusst zu leben, bewusst zu konsumieren. Das Thema Ernährung wird zwar immer wichtiger für einige von uns, jedoch reicht mir die Aufmerksamkeit bisher nicht. Es sind nicht nur Lebensmittel, welche nach dem Aufenthalt im Supermarkt in unserem Kühlschrank und anschließend in unserem Bauch landen. Mit diesen Lebensmitteln gehen außerdem folgende Aspekte einher: der Klimawandel, unsere Gesundheit, die Ausbeutung von Tieren, Menschen und Natur. Also wie sieht eigentlich der Enstehungsprozess hinter all diesen (meist) verpackten Lebensmitteln aus? Einen Teil dieser Prozesse habe ich mir im Rahmen meiner Bachelorarbeit angeschaut. Ich habe ausschließlich Bio-Höfe besucht, um mir ein eigenes Bild von "alternativer Landwirtschaft" zu machen. Die Arbeit ermöglicht Interessierten einen neutralen Einblick hinter die Kulisse unserer Lebensmittel und schafft eine Anregung für einen bewussteren Konsum.
Dipl.Ing. Johann Andorfer , Tandler.com GmbH, Buch a. Erlbach. Abstract zum 1. Aachener Softwaretag in der Wasserwirtschaft <1,2007, Aachen>. 2 S. (S. 136-137) Eine nachhaltige Sicherung der Funktionalität und der ökologischen Verträglichkeit eines mittleren bis großen Kanalnetzes erfordert eine umfassende und detaillierte Modellierung in Raum und Zeit. Um den in den Richtlinien geforderten statistischen Anforderungen gerecht zu werden und die jährlichen Häufigkeiten, Mengen und Zeiträume der Belastungen erwartungstreu abschätzen zu können, ist es zielführend und notwendig, lange Zeiträume und die Gesamtheit der Einzugsgebiete möglichst detailliert zu betrachten. Die hydraulische Funktionalität und Sicherheit soll meistens mit Hilfe zeitsymmetrischer (hydrodynamischer) Verfahren nur durch Betrachtung von Modellregen, allenfalls Regenserien, sichergestellt werden. Für die Abschätzung der jährlich zu erwartenden Emissionen in unsere natürlichen Gewässer mit ihren Mengen, Frequenzen und Dauern werden normalerweise Langzeitsimulationen natürlicher Regenreihen über möglichst große Zeiträume mit zeitasymmetrischen (hydrologischen) Verfahren durchgeführt. Die betrachteten Kanalnetze werden zumeist vereinfacht (Grobnetze), um die Rechenzeiten erträglicher zu gestalten. Wünschenswert wäre jedoch eine allen Anforderungen gerecht werdende wirklichkeitsnahe Modellierung des gesamten Kanalnetzes in all seinen Details, Vermaschungen und Wechselwirkungen (Feinnetz) und dessen zeitsymmetrische und damit verlässliche Simulation mit langjährigen Regenreihen. Bereits vor 15 Jahren wurde im Hause Tandler begonnen, die Berechnungssoftware durch Parallelisierung auf symmetrische Multiprozessortechnologien auszurichten. In neuerer Zeit hält diese Technik durch die Mehrkernprozessoren in normalen Notebooks und PCs Einzug in die Ingenieurbüros und Abwasserbetriebe und sorgt schon für wesentliche Einsparungen an Rechenzeit. Doch erst durch die Kombination der Parallelisierung mit dem Prinzip des verteilten Rechnens (d.h. die Einbeziehung mehrerer PCs eines Netzwerkes in die Berechnung) erhält man die Chance ausreichend Rechenkapazität zur Verfügung zu stellen, um nicht nur eine einzelne Langzeitsimulation eines Feinnetzes durchzuführen, sondern sogar mehrere Sanierungsalternativen zu überprüfen. Die zukunftsweisenden Arbeiten von Dipl. Math. R. Tandler auf diesem Gebiet sind Thema dieses Vortrags.
Objective
Hemodialysis patients show an approximately threefold higher prevalence of cognitive impairment compared to the age-matched general population. Impaired microcirculatory function is one of the assumed causes. Dynamic retinal vessel analysis is a quantitative method for measuring neurovascular coupling and microvascular endothelial function. We hypothesize that cognitive impairment is associated with altered microcirculation of retinal vessels.
Methods
152 chronic hemodialysis patients underwent cognitive testing using the Montreal Cognitive Assessment. Retinal microcirculation was assessed by Dynamic Retinal Vessel Analysis, which carries out an examination recording retinal vessels' reaction to a flicker light stimulus under standardized conditions.
Results
In unadjusted as well as in adjusted linear regression analyses a significant association between the visuospatial executive function domain score of the Montreal Cognitive Assessment and the maximum arteriolar dilation as response of retinal arterioles to the flicker light stimulation was obtained.
Conclusion
This is the first study determining retinal microvascular function as surrogate for cerebral microvascular function and cognition in hemodialysis patients. The relationship between impairment in executive function and reduced arteriolar reaction to flicker light stimulation supports the involvement of cerebral small vessel disease as contributing factor for the development of cognitive impairment in this patient population and might be a target for noninvasive disease monitoring and therapeutic intervention.
The Effect of Openings on Out-of-Plane Capacity of Masonry Infilled Reinforced Concrete Frames
(2018)
Feinbleche schweißen : die Temperaturverteilung in dünnen Stahlblechplatten beim Lichtbogenschweißen
(1971)
Untersuchungen zum thermodynamischen Verhalten des Sauerstoffs in Kupfer-Wismut-Schmelzen bei 1200°C
(1982)
The purpose of the current study in combination with our previous published data (Arampatzis et al., 2007) was to examine the effects of a controlled modulation of strain magnitude and strain frequency applied to the Achilles tendon on the plasticity of tendon mechanical and morphological properties. Eleven male adults (23.9±2.2 yr) participated in the study. The participants exercised one leg at low magnitude tendon strain (2.97±0.47%), and the other leg at high tendon strain magnitude (4.72±1.08%) of similar frequency (0.5 Hz, 1 s loading, 1 s relaxation) and exercise volume (integral of the plantar flexion moment over time) for 14 weeks, 4 days per week, 5 sets per session. The exercise volume was similar to the intervention of our earlier study (0.17 Hz frequency; 3 s loading, 3 s relaxation) allowing a direct comparison of the results. Before and after the intervention ankle joint moment has been measured by a dynamometer, tendon–aponeurosis elongation by ultrasound and cross-sectional area of the Achilles tendon by magnet resonance images (MRI). We found a decrease in strain at a given tendon force, an increase in tendon–aponeurosis stiffness and tendon elastic modulus of the Achilles tendon only in the leg exercised at high strain magnitude. The cross-sectional area (CSA) of the Achilles tendon did not show any statistically significant (P>0.05) differences to the pre-exercise values in both legs. The results indicate a superior improvement in tendon properties (stiffness, elastic modulus and CSA) at the low frequency (0.17 Hz) compared to the high strain frequency (0.5 Hz) protocol. These findings provide evidence that the strain magnitude applied to the Achilles tendon should exceed the value, which occurs during habitual activities to trigger adaptational effects and that higher tendon strain duration per contraction leads to superior tendon adaptational responses.
Venus und Mars
(2021)
Venus und Mars - Mann und Frau. Ein binäres System, welches heutzutage einer ständigen Hinterfragung ausgesetzt ist. Woraus entstand dieses System und wie manipulativ ist das Geschlecht wirklich? Die Pionierwerke der Gender Studies/Queer Studies zeigten auf, dass jeder Mensch sein Geschlecht durch das Imitieren von sozial-gesellschaftlich festgelegten Normen und Werten bildet. Drag-Künstler*innen leben diesen Prozess in einer visuellen Form vor, indem sie Geschlechternormen aufgreifen und sie unabhängig vom biologischen Geschlecht der Darstellenden inszenieren, imitieren, parodieren und neu zusammensetzen. Jede Performance auf den Fotografien greift ebenfalls vorhandene Vorstellungen von Geschlecht auf und interpretiert sie neu: denn Drag kennt kein Original, genauso wenig wie das Geschlecht.
Novel organic membrane-based thin-film microsensors for the determination of heavy metal cations
(2006)
A first step towards the fabrication and electrochemical evaluation of thin-film microsensors based on organic PVC membranes for the determination of Hg(II), Cd(II), Pb(II) and Cu(II) ions in solutions has been realised. The membrane-coating mixture used in the preparation of this new type of microsensors is incorporating PVC as supporting matrix, o-nitrophenyloctylether (o-NPOE) as solvent mediator and a recently synthesized Hg[dimethylglyoxime(phene)]2+ and Bis-(4-hydroxyacetophenone)-ethylenediamine as electroactive materials for Hg(II) and Cd(II), respectively. A set of three commercialised ionophores for Cd(II), Pb(II) and Cu(II) has been also used for comparison. Thin-film microsensors based on these membranes showed a Nernstian response of slope (26-30 mV/dec.) for the respective tested cations. The potentiometric response characteristics (linear range, pH range, detection limit and response time) are comparable with those obtained by conventional membranes as well as coated wire electrodes prepared from the same membrane. The realisation of the new organic membrane-based thin-film microsensors overcomes the problem of an insufficient selectivity of solid-state-based thinfilm sensors.
Microfabrication, characterization and analytical application of a new thin-film silver microsensor
(2009)
One of interesting but not well known water properties is related to appearance of highly ordered structures in response to strong electrical field. In 1893 Sir William Armstrong placed a cotton thread between two wine glasses filled with chemically pure water. When high DC voltage was applied between the glasses, a connection consisting of water formed, producing a "water bridge"
Background
True date palms (Phoenix dactylifera L.) are impressive trees and have served as an indispensable source of food for mankind in tropical and subtropical countries for centuries. The aim of this study is to differentiate date palm tree varieties by analysing leaflet cross sections with technical/optical methods and artificial neural networks (ANN).
Results
Fluorescence microscopy images of leaflet cross sections have been taken from a set of five date palm tree cultivars (Hewlat al Jouf, Khlas, Nabot Soltan, Shishi, Um Raheem). After features extraction from images, the obtained data have been fed in a multilayer perceptron ANN with backpropagation learning algorithm.
Conclusions
Overall, an accurate result in prediction and differentiation of date palm tree cultivars was achieved with average prediction in tenfold cross-validation is 89.1% and reached 100% in one of the best ANN.
This paper presents an approach for reducing the cognitive load for humans working in quality control (QC) for production processes that adhere to the 6σ -methodology. While 100% QC requires every part to be inspected, this task can be reduced when a human-in-the-loop QC process gets supported by an anomaly detection system that only presents those parts for manual inspection that have a significant likelihood of being defective. This approach shows good results when applied to image-based QC for metal textile products.
Prior to immobilization of biomolecules or cells onto biosensor surfaces, the surface must be physically or chemically activated for further functionalization. Organosilanes are a versatile option as they facilitate the immobilization through their terminal groups and also display self-assembly. Incorporating hydroxyl groups is one of the important methods for primary immobilization. This can be done, for example, with oxygen plasma treatment. However, this treatment can affect the performance of the biosensors and this effect is not quite well understood for surface functionalization. In this work, the effect of O2 plasma treatment on EIS sensors was investigated by means of electrochemical characterizations: capacitance–voltage (C–V) and constant capacitance (ConCap) measurements. After O2 plasma treatment, the potential of the EIS sensor dramatically shifts to a more negative value. This was successfully reset by using an annealing process.
Optimization of the immobilization of bacterial spores on glass substrates with organosilanes
(2016)
Spores can be immobilized on biosensors to function as sensitive recognition elements. However, the immobilization can affect the sensitivity and reproducibility of the sensor signal. In this work, three different immobilization strategies with organosilanes were optimized and characterized to immobilize Bacillus atrophaeus spores on glass substrates. Five different silanization parameters were investigated: nature of the solvent, concentration of the silane, silanization time, curing process, and silanization temperature. The resulting silane layers were resistant to a buffer solution (e.g., Ringer solution) with a polysorbate (e.g., Tween®80) and sonication.
In the present work, surface functionalization of different sensor materials was studied. Organosilanes are well known to serve as coupling agent for biomolecules or cells on inorganic materials. 3-aminopropyltriethoxysilane (APTES) was used to attach microbiological spores time to an interdigitated sensor surface. The functionality and physical properties of APTES were studied on isolated sensor materials, namely silicon dioxide (SiO2) and platinum (Pt) as well as the combined material on sensor level. A predominant immobilization of spores could be demonstrated on SiO2 surfaces. Additionally, the impedance signal of APTES-functionalized biosensor chips has been investigated.
A microscopic photometric method for measuring erythrocyte deformability. Artmann, Gerhard Michael
(1986)
Tests with palm tree leaves have just started yet and scan data are in the process to be analyzed. The final goal of future project for palm tree gender and species recognition will be to develop optical scanning technology to be applied to date palm tree leaves for in–situ screening purposes. Depending on the software used and the particular requirements of the users the technology potentially shall be able to identify palm tree diseases, palm tree gender, and species of young date palm trees by scanning leaves.