Refine
Departments, institutes and facilities
- Fachbereich Wirtschaftswissenschaften (1241)
- Fachbereich Informatik (1148)
- Fachbereich Angewandte Naturwissenschaften (766)
- Fachbereich Ingenieurwissenschaften und Kommunikation (636)
- Institut für funktionale Gen-Analytik (IFGA) (584)
- Institut für Technik, Ressourcenschonung und Energieeffizienz (TREE) (485)
- Präsidium (404)
- Fachbereich Sozialpolitik und Soziale Sicherung (402)
- Institute of Visual Computing (IVC) (313)
- Institut für Cyber Security & Privacy (ICSP) (307)
- Institut für Verbraucherinformatik (IVI) (252)
- Internationales Zentrum für Nachhaltige Entwicklung (IZNE) (195)
- Institut für Sicherheitsforschung (ISF) (94)
- Graduierteninstitut (66)
- Institut für Medienentwicklung und -analyse (IMEA) (42)
- Stabsstelle Kommunikation und Marketing (37)
- Centrum für Entrepreneurship, Innovation und Mittelstand (CENTIM) (35)
- Institut für Detektionstechnologien (IDT) (30)
- Zentrum für Innovation und Entwicklung in der Lehre (ZIEL) (29)
- Bibliothek (24)
- Sprachenzentrum (24)
- Zentrum für Ethik und Verantwortung (ZEV) (24)
- Institut für Soziale Innovationen (ISI) (13)
- Verwaltung (12)
- Zentrum für Wissenschafts- und Technologietransfer (ZWT) (10)
- Institut für IT-Service (ITS) (7)
- Institut für KI und Autonome Systeme (A2S) (7)
- Institut für Existenzgründung und Mittelstandsförderung (IfEM) (3)
- International Office (3)
- Gleichstellungsstelle (1)
- Zentrum für Campus-IT (1)
Document Type
- Article (2430)
- Conference Object (1806)
- Part of a Book (942)
- Book (monograph, edited volume) (452)
- Part of Periodical (411)
- Report (201)
- Contribution to a Periodical (118)
- Doctoral Thesis (106)
- Working Paper (94)
- Preprint (90)
- Master's Thesis (64)
- Lecture (62)
- Conference Proceedings (54)
- Bachelor Thesis (43)
- Patent (40)
- Research Data (27)
- Video (18)
- Other (18)
- Book review (15)
- Diploma Thesis (9)
- Periodical (9)
- Study Thesis (5)
- Postdoctoral thesis (1)
Year of publication
Keywords
- Lehrbuch (88)
- Deutschland (34)
- Nachhaltigkeit (30)
- Controlling (25)
- Unternehmen (25)
- Management (20)
- Corporate Social Responsibility (18)
- Betriebswirtschaftslehre (17)
- Digitalisierung (17)
- Machine Learning (17)
Maschinenbauprodukte lassen sich mit integrierten Drucksensoren bauraum- und kostenoptimiert entwickeln, indem man Druckmesszellen und elektronische Signalwandlung anwendungsspezifisch integriert. Dabei hilft es zu wissen, welche Messzellen und Signalwandler günstig verfügbar sind und welche Vor- und Nachteile sie haben.
Schwingungen sind Bestandteil einer jeden Maschine mit beweglichen Teilen, manchmal sind sie unbedeutend, manchmal deutlich merkbar. Die Überwachung von Schwingungen einer Maschine kann dazu dienen, die Maschinenfunktion zu kontrollieren oder auch frühzeitig Verschleißschäden zu erkennen. Stand der Technik ist die Messung von Schwingungen mit präzisen, aber auch kostenintensiven piezoelektrischen Beschleunigungssensoren und aufwändigen Messsystemen. Solche konventionellen Systeme sind für hochpreisige Maschinen und Anlagen, z. B. Windkraftanlagen, einsetzbar, aber nicht für kleine und mittelgroße Maschinen. Hier besteht der Bedarf an wirklichen Low-Cost Messsystemen, die so günstig sind, dass sie permanent in die Maschine integriert sind und permanent die Schwingungen überwachen. Im Forschungsprojekt wurde ein Baukasten aus kommerziell verfügbaren Komponenten entwickelt, mit dem Low-Cost Schwingungsmesssysteme aufgebaut werden können.
Construction kit for low-cost vibration analysis systems based on low-cost acceleration sensors
(2009)
Protokoll 27
(2023)
Zur Schätzung der Exposition von Oberflächengewässern durch Pflanzenschutzmittel werden PEC-Werte mit Hilfe eines probabilistischen Verfahrens ermittelt. Hierfür werden zunächst verschiedene Regressionsanalysen zur Modellierung der Abdrift durchgeführt. Anschließend wird die ausgewählte Abdriftverteilung mit verschiedenen Verteilungsansätzen für die Aufwandmenge und das Gewässervolumen kombiniert.
Dieses Buch bietet einen leicht verständlichen Einstieg in die Thematik des Data Minings und der Prädiktiven Analyseverfahren. Als Methodensammlung gedacht, bietet es zu jedem Verfahren zunächst eine kurze Darstellung der Theorie und erklärt die zum Verständnis notwendigen Formeln. Es folgt jeweils eine Illustration der Verfahren mit Hilfe von Beispielen, die mit dem Programmpaket R erarbeitet werden.
Zum Abschluss wird eine einfache Möglichkeit präsentiert, mit der die Performancewerte verschiedener Verfahren mit statistischen Mitteln verglichen werden können. Zum Einsatz kommen hierbei geeignete Grafiken und Konfidenzintervalle.
Das Buch verzichtet nicht auf Theorie, es präsentiert jedoch so wenig Theorie wie möglich, aber so viel wie nötig und ist somit optimal für Studium und Selbststudium geeignet.
Stakeholder-Analyse zum Einsatz IIoT-basierter Frischeinformationen in der Lebensmittelindustrie
(2019)
Eine Herausforderung bei der Implementierung des industriellen Internet of Things (IIoT) besteht darin, Mehrwerte in Wertschöpfungsketten zu identifizieren, um darauf aufbauend Lösungen nutzerzentriert zu gestalten. Dieser Beitrag stellt das Forschungsprojekt FreshIndex vor, bei dem diese Herausforderung durch eine Kombination aus Stakeholder-Analyse und User-Centered-Design-Methoden adressiert wurde. Ziel des Projekts ist es, eine IIoT-basierte Lösung zum Monitoring der Kühlkette in der Lebensmittelindustrie zu entwickeln. Hierzu ist es wichtig zu wissen, welche Nutzer/-innen mit den Daten in Berührung kommen und welche Erfahrungen, Fähigkeiten, Anforderungen und Wünsche sie mitbringen. Die Berücksichtigung dieser Aspekte ist relevant für den Erfolg der Konzeption, Implementierung und des Betriebs eines IIoT-Systems. So können nützliche und handhabbare Produktideen generiert und Anwendungen gestaltet werden, die von Mitarbeiter/-innen und Konsument/-innen angenommen werden. IIoT schließt somit die lokale Verwendbarkeit von Daten entlang der Wertschöpfungskette ein und beschränkt sich nicht auf zentrale Verfügbarkeit von Daten.
Die Globalisierung führt zu immer komplexeren, für die Einzelnen kaum nachvollziehbaren Wertschöpfungsketten in der Lebensmittelindustrie. Zugleich eröffnet die Digitalisierung neue Möglichkeiten, Informationen entlang der Kette zu sammeln, und so mehr Transparenz und Vertrauen für den Verbraucherbeziehungsweise die Verbraucherin zu schaffen. Jedoch finden Verbraucherinformations-Apps wie fTRACE bisher nur eine geringe Verbreitung. Daher haben wir in einer qualitativen Studie mit 16 Teilnehmer/-innen Bedürfnisse und Nutzungshürden von Verbraucher/-innen im Zusammenhang mit Verbraucherinformations-Apps analysiert. Es zeigt sich, dass das Vertrauen in die Informationen, sowie der einfache Zugang dazu für Verbraucher/-innen zentral sind. Durch die gut sichtbare Bereitstellung der Informationen am Point-of-Sale, sowie der automatisierten Informationsversorgung z. B. mittels digitaler Kassenzettel in Kombination mit weiteren Verbraucher-Services kann die Bekanntheit und Akzeptanz von Rückverfolgbarkeitssystemen weiter gesteigert werden.
Diese Theorie-Einführung hat konsequent praktische Anwendungen im Blick. Seien es Workflow-Systeme, Web Services, Verschlüsselung von Informationen, Authentifizierungsprotokolle oder selbstfahrende Autos - all diese Technologien haben enge Bezüge zu den theoretischen Grundlagen der Informatik. So trägt das Buch dazu bei, dass Studierende die Grundlagen der Theoretischen Informatik nicht nur verstehen, sondern auch anwenden können, um effektiv und produktiv an informationstechnischen Problemlösungen mitwirken zu können. Wegen seiner speziellen inhaltlichen und didaktischen Qualität ist das Buch neben dem Einsatz in der Lehre auch für das Selbststudium geeignet.
Friction effects impose a requirement for the supplementary amount of torque to be produced in actuators for a robot to move, which in turn increases energy consumption. We cannot eliminate friction, but we can optimize motions to make them more energy efficient, by considering friction effects in motion computations. Optimizing motions means computing efficient joint torques/accelerations based on different friction torques imposed in each joint. Existing friction forces can be used for supporting certain types of arm motions, e.g standing still.
Reducing energy consumption of robot's arms will provide many benefits, such as longer battery life of mobile robots, reducing heat in motor systems, etc.
The aim of this project is extending an already available constrained hybrid dynamic solver, by including static friction effects in the computations of energy optimal motions. When the algorithm is extended to account for static friction factors, a convex optimization (maximization) problem must be solved.
The author of this hybrid dynamic solver has briefly outlined the approach for including static friction forces in computations of motions, but without providing a detailed derivation of the approach and elaboration that will show its correctness. Additionally, the author has outlined the idea for improving the computational efficiency of the approach, but without providing its derivation.
In this project, the proposed approach for extending the originally formulated algorithm has been completely derived and evaluated in order to show its feasibility. The evaluation is conducted in simulation environment with one DOF robot arm, and it shows correct results from the computation of motions. Furthermore, this project presents the derivation of the outlined method for improving the computational efficiency of the extended solver.
Human and robot tasks in household environments include actions such as carrying an object, cleaning a surface, etc. These tasks are performed by means of dexterous manipulation, and for humans, they are straightforward to accomplish. Moreover, humans perform these actions with reasonable accuracy and precision but with much less energy and stress on the actuators (muscles) than the robots do. The high agility in controlling their forces and motions is actually due to "laziness", i.e. humans exploit the existing natural forces and constraints to execute the tasks.
The above-mentioned properties of the human lazy strategy motivate us to relax the problem of controlling robot motions and forces, and solve it with the help of the environment. Therefore, in this work, we developed a lazy control strategy, i.e. task specification models and control architectures that relax several aspects of robot control by exploiting prior knowledge about the task and environment. The developed control strategy is realized in four different robotics use cases. In this work, the Popov-Vereshchagin hybrid dynamics solver is used as one of the building blocks in the proposed control architectures. An extension of the solver’s interface with the artificial Cartesian force and feed-forward joint torque task-drivers is proposed in this thesis.
To validate the proposed lazy control approach, an experimental evaluation was performed in a simulation environment and on a real robot platform.
The Decision Tree Procedure
(2024)
Do remittances and social assistance transfers have different impacts on household’s expenditure patterns? While two separate strands of literature have looked at how social assistance or remittances have been spent, few studies have compared them directly. Using data from a household survey conducted in Moldova in 2011, this paper assesses the impact both types of transfers have on household expenditure patterns. Contrary to the common assumption that money is fungible, we find that social assistance and remittances have different impacts on expenditure patterns (having controlled for potential endogeneity). In other words, where the income comes from can determine how it is spent. As such, different sources of income may have different poverty impacts. In our sample, the two types of transfers are received by different, but slightly overlapping population groups. The fact that the two transfers are spent in different ways means that, to some extent, social assistance and remittances are complements rather than substitutes.
Untersuchungen zur Hydrophobierung von Miscanthus X giganteus für den Einsatz in Dämmstoffsystemen
(2018)
New sustainable, environmentally friendly materials for thermal insulation of buildings are necessary to reduce their carbon footprints. In this study, Miscanthus fiber-reinforced geopolymer composites, foamed with sodium dodecyl sulfate (SDS), were developed using fly ash as a geopolymer precursor. The effects of fiber content, fiber size, curing temperature, foaming agent content, fumed silica specific surface area and fumed silica content on thermal conductivity and compressive strength were evaluated using a Plackett-Burman design of experiment. Furthermore, the microstructure of geopolymer composites was investigated using X-ray diffraction (XRD), X-ray micro-computed tomography (μCT) and scanning electron microscopy (SEM). The measured characteristic values were in the following ranges: Thermal conductivity 0.057 W (m K)−1 to 0.127 W (m K)−1, compressive strength 0.007 MPa–0.719 MPa and porosity 49 vol% to 76 vol%. The results reveal an enhancement of thermal conductivity by elevated fiber size and foaming agent content. In contrast, the compressive strength is enhanced by high fiber content. Additionally, SEM images indicate a good interaction between the fibers and the geopolymer matrix, because nearly the whole fiber surface is covered by the geopolymer.
Due to increased emissions of palladium nanoparticles in recent years, it is important to develop analytical techniques to characterize these particles. The synthesis of defined and stable particles plays a key role in this process, as there are not many materials commercially available yet which could act as reference materials. Polyvinylpyrrolidone- (PVP-) stabilized palladium nanoparticles were synthesized through the reduction of palladium chloride by tetraethylene glycol (TEG) in the presence of KOH. Four different methods were used for particle size analysis of the palladium nanoparticles. Palladium suspensions were analyzed by scanning electron microscopy (SEM), small angle X-ray scattering (SAXS), single-particle ICP-MS (SP-ICP-MS), and X-ray diffraction (XRD). Secondary particles between 30 nm and 130 nm were detected in great compliance with SAXS and SP-ICP-MS. SEM analysis showed that the small particulates tend to form agglomerates.
The development of sustainable, environmentally friendly insulation materials with a reduced carbon footprint is attracting increased interest. One alternative to conventional insulation materials are foamed geopolymers. Similar to foamed concrete, the mechanical properties of geopolymer foams can also be improved by using fibers for reinforcement. This paper presents an overview of the latest research findings in the field of fiber-reinforced geopolymer foam concrete with special focus on natural fibers reinforcement. Furthermore, some basic and background information of natural fibers and geopolymer foams are reported. In most of the research, foams are produced either through chemical foaming with hydrogen peroxide or aluminum powder, or through mechanical foaming which includes a foaming agent. However, previous reviews have not sufficiently addresses the fabrication of geopolymer foams by syntactic foams. Finally, recent efforts to reduce the fiber degradation in geopolymer concrete are discussed along with challenges for natural fiber reinforced-geopolymer foam concrete.
Design and characterization of geopolymer foams reinforced with Miscanthus x giganteus fibers
(2024)
This paper presents the effects of different amounts of fibers and foaming agent, as well as different fiber sizes, on the mechanical and thermal properties of fly ash-based geopolymer foams reinforced with Miscanthus x giganteus fibers. The mechanical properties of the geopolymer foams were measured through compressive strength, and their thermal properties were characterized by thermal conductivity and X-ray micro-computed tomography. Furthermore, design of experiment (DoE) were used to optimize the thermal conductivity and compressive strength of Miscanthus x giganteus reinforced geopolymer foams. In addition, the microstructure was studied using X-ray diffraction (XRD), Field emission scanning electron microscopy (SEM) and Fourier-Transform Infrared Spectroscopy (FTIR). Mixtures with a low thermal conductivity of 0.056 W (m K)−1 and a porosity of 79 vol% achieved a compressive strength of only 0.02 MPa. In comparison, mixtures with a thermal conductivity of 0.087 W (m K)−1 and a porosity of 58 vol% achieved a compressive strength of 0.45 MPa.
Der Behindertenspitzensport hat sich in den letzten Jahren – nicht nur leistungsmäßig – in hohem Maße weiterentwickelt. Öffentlichkeit und Medien widmen ihm größere Aufmerksamkeit und bringen den Athleten mehr Akzeptanz entgegen als in der Vergangenheit. Auch der werbliche Einsatz dieses Sportbereichs erfährt gute Bewertungen. Laut aktuellen Umfragen in der Bevölkerung lässt sich durch die Schaltung von Anzeigen mit behinderten Spitzenathleten das Unternehmensimage positiv beeinflussen.
Erst seit wenigen Jahren binden Unternehmen den Behindertenspitzensport in ihre Kommunikationsaktivitäten ein. Da die Anzahl der damit arbeitenden Firmen zudem gering ist, lagen bislang kaum Informationen und Erfahrungswerte vor, die anderen an einem Engagement in diesem Bereich Interessierten Orientierungshilfen bieten konnten.
Background
Consumers rely heavily on online user reviews when shopping online and cybercriminals produce fake reviews to manipulate consumer opinion. Much prior research focuses on the automated detection of these fake reviews, which are far from perfect. Therefore, consumers must be able to detect fake reviews on their own. In this study we survey the research examining how consumers detect fake reviews online.
Methods
We conducted a systematic literature review over the research on fake review detection from the consumer-perspective. We included academic literature giving new empirical data. We provide a narrative synthesis comparing the theories, methods and outcomes used across studies to identify how consumers detect fake reviews online.
Results
We found only 15 articles that met our inclusion criteria. We classify the most often used cues identified into five categories which were (1) review characteristics (2) textual characteristics (3) reviewer characteristics (4) seller characteristics and (5) characteristics of the platform where the review is displayed.
Discussion
We find that theory is applied inconsistently across studies and that cues to deception are often identified in isolation without any unifying theoretical framework. Consequently, we discuss how such a theoretical framework could be developed.
Mobile Business
(2009)
Auf der Basis des modernen Mobilfunks entstehen neuartige Wertschöpfungsstrukturen, die die traditionellen Wirtschaftsstrukturen komplementieren und immer häufiger auch substituieren. Unternehmen, die in der "Mobile Economy" erfolgreich bestehen wollen, müssen sich daher umfassend mit den strategischen Rahmenbedingungen des Mobile Business auseinandersetzen. Nur wer die Einsatzpotenziale der multimedialen Mobilkommunikation differenziert bewerten kann und auch die kritischen Erfolgsfaktoren dieser noch jungen Disziplin kennt, wird in der mobilen Zukunft seine Wettbewerbsposition tatsächlich nachhaltig stärken können.
Mobile-Commerce-Studie
(2000)
An der Fachhochschule Bonn-Rhein-Sieg wurde im Rahmen eines Forschungssemesters eine Szenarioanalyse durchgeführt, welche die Entwicklungspfade von Mobile Business bis zum Jahr 2011 untersucht. Dabei wurden maßgebliche Entwicklungstreiber bestimmt und ihre zukünftige Ausprägung sowie ihr Zusammenspiel analysiert. Es entstanden drei plausible Zukunftsbilder. Das wahrscheinlichste der drei Trendszenarien, mit einer Eintrittswahrscheinlichkeit von 60 %, basiert auf der Untersuchung der zehn bedeutendsten Entwicklungstreiber von Mobile Business. Danach wird der Ausbau der UMTS-Netze bis 2011 soweit vorangeschritten sein, dass 70 % der potentiellen Anwender breitbandige Anschlüsse werden nutzen können. In Ballungsgebieten/Großstädten werden Übertragungsraten von mehr als acht MBit/s verfügbar sein. Speicherkapazität, Geschwindigkeit und Funktionsumfang der Endgeräte verbessern sich deutlich. Software für moilbe Lösungen unterstützen vielfältige Geschäftsprozesse und bieten bis 2011 weitgehend Desktop-Funktionalität. Es entstehen alternative Betreibermodelle - die Software verlagert sich zunehmend ins Netz. Die laufenden Kosten des Mobile Business sinken nur langsam, da die Tarife für mobile Kommunikation weiterhin künstlich hochgehalten werden. Die Preise für Endgeräte bleiben relativ konstant. Mobile Lösungen werden in vielen Branchen zu Schlüsselanwendungen, und wer hier nicht das Optimierungspotential ausschöpft, der erleidet zunehmend Wettbewerbsnachteile. Aus diesenTrends ergeben sich Handlungsempfehlungen für Unternehmen. Sie sollten ihre Prozesse gezielt durch Multimedia-Kommunikation unterstützen und mobile Mitarbeiter mit für sie maßgeschneiderten Endgeräten ausstatten.
Kenya, like all other developing countries in the world, is faced with the task of working strategically towards the achievement of the Sustained Development Goals (SDGs) 2030. These goals whose due date of accomplishment coincides with those of the national development blueprint, namely, the Kenya Vision 2030, have become a major focus of attention in the country. Conferences, workshops, and seminars are organized throughout the country on regular bases by joint multiplicity of organizations to address modalities of ensuring a timely achievement of SDGs in the country. Universities either individually or jointly are working towards this same target. More specifically, there are great areas of concern or priority areas that the country is focusing on as a strategic focus towards the achievement of the Kenya Vision 2030 and SDGs 2030. These strategic areas of focus have been isolated and declared by the President of the Republic of Kenya, His Excellency Uhuru Kenyatta, as the country’s “big four priority areas”, namely, affordable housing, affordable health care, food security, and manufacturing as a grandiose effort towards achievement of the SDGs, Kenya Vision 2030 as well as job and wealth creation. Similarly, Mount Kenya University’s top management established the Graduate Enterprise Academy (GEA) in 2013 under the direct Patronage of the university’s Founder with the primary aim of assisting graduates to be job and wealth creators rather than being job seekers. So far, over twenty start-ups are running throughout the country under Graduate Enterprise Academy (GEA). Incidentally, although the Graduate Enterprise Academy’s diverse areas of focus extend beyond the President of Kenya’s “Big Four” to include ICT and creative arts, among others, there are justifiable cases to indicate that GEA’s activities are also in support of the national “Big Four” agenda. This paper gives an exposition of different start-ups under MKU’s Graduate Enterprise Academy and are show-cased as evidence of MKU’s support towards the achievement of the national “Big Four” agenda. The paper covers a part of an ongoing program through desk-top analyses of reports, with an objective of show-casing MKU’s contribution to the national agenda through the Graduate Enterprise Academy for possible scale - up.
IT-Offshoring - Nein danke!
(2006)
True Fruits
(2014)
In this work, the surface reactions of the homemade explosive triacetone triperoxide on tungsten oxide (WO3) sensor surfaces are studied to obtain detailed information about the chemical reactions taking place. Semiconductor gas sensors based on WO3 nanopowders are therefore produced and characterized by scanning electron microscopy, X-ray diffraction, and Raman spectroscopy. To analyze the reaction mechanisms at the sensor surface, the sensor is monitored online under operation conditions using Raman spectroscopy, which allows to identify the temperature-dependent sensor reactions. By combining information from the Raman spectra with data on the changing resistivity of the underlying semiconductor, it is possible to establish a correlation between the adsorbed gas species and the physical properties of the WO3 layer. In the results, it is indicated that a Lewis acid–base reaction is the most likely mechanism for the increase in resistance observed at temperatures below 150 °C. In the results, at higher temperatures, the assumption of a radical mechanism that causes a decrease in resistance is supported.
Detection of triacetone triperoxide using temperature cycled metal-oxide semiconductor gas sensors
(2015)
Bionik
(2022)
Wie machen die das… kann angesichts der erstaunlichen Fähigkeiten mancher Lebewesen gefragt werden. Die Bionik fragt noch weiter …und wie kann man das nachmachen? Hier liegt ein Schwerpunkt dieses Lehrbuches, das die Bionik nicht nur an zahlreichen Beispielen erklärt, sondern auch eine Vorgehensweise für die Identifizierung biologischer Lösungen und deren Übertragung auf technische Anwendungen vermittelt. Basisinformationen der Biologie und Grundlagen der Konstruktionstechnik gewährleisten einen leichten Zugang zum Stoff. Mit dem 3D-Druck als Schlüsseltechnologie und der Thematisierung der Nachhaltigkeit geht das Buch zudem auf aktuelle Entwicklungen ein. Dieser ganzheitliche Blick auf die Bionik soll den Leser zur Durchführung bionischer Projekte befähigen und motivieren. Die vorliegende Auflage wurde überarbeitet und um aktuelle Forschungserkenntnisse und Entwicklungen ergänzt. (Verlagsangaben)
Bionik
(2020)
Wie machen die das... kann angesichts der erstaunlichen Fähigkeiten mancher Lebewesen gefragt werden. Die Bionik fragt noch weiter …und wie kann man das nachmachen? Hier liegt ein Schwerpunkt dieses Lehrbuches, das die Bionik nicht nur an zahlreichen Beispielen erklärt, sondern auch eine Vorgehensweise für die Identifizierung biologischer Lösungen und deren Übertragung auf technische Anwendungen vermittelt. Basisinformationen der Biologie und Grundlagen der Konstruktionstechnik gewährleisten einen leichten Zugang zum Stoff. Mit dem 3D-Druck als Schlüsseltechnologie und der Thematisierung der Nachhaltigkeit geht das Buch zudem auf aktuelle Entwicklungen ein. Dieser ganzheitliche Blick auf die Bionik soll den Leser zur Durchführung bionischer Projekte befähigen und motivieren. (Verlagsangaben)
The synthesis and characterization of a new class of 1,2,4-oxadiazolylpyridinium as a cationic scaffold for fluorinated ionic liquid crystals is herein described. A series of 12 fluorinated heterocyclic salts based on a 1,2,4-oxadiazole moiety, connected through its C(5) or C(3) to an N-alkylpyridinium unit and a perfluoroheptyl chain, differing in the length of the alkyl chain and counterions, has been synthesized. As counterions iodide, bromide and bis(trifluoromethane)sulfonimide have been considered. The synthesis, structure, and liquid crystalline properties of these compounds are discussed on the basis of the tuned structural variables. The thermotropic properties of this series of salts have been investigated by differential scanning calorimetry and polarized optical microscopy. The results showed the existence of an enantiotropic mesomorphic smectic liquid crystalline phase for six bis(trifluoromethane)sulfonimide salts.
Grundlagen des Marketings
(2015)
Marketing und Innovation
(2017)
Innovation und Marketing zählen zu den zentralen Herausforderungen für Unternehmen, durch die sie Differenzierung und Vorsprung im Wettbewerb erzielen können. Innovation ohne Marketing und Marketing ohne Innovation können nicht erfolgreich sein, weshalb beide Unternehmerfunktionen im Zusammenspiel zu betrachten sind. Das vorliegende Lehrbuch verfolgt deshalb ein zusammenschauendes Konzept, zu dem es das theoretische und praktische Grundlagenwissen vermittelt. Zunächst wird die Bedeutung von Innovation und Marketing als Erfolgsfaktor analysiert. Anschließend wird ein marketingfokussierter Innovationsprozess diskutiert, bei dem auf jeder Stufe die Frage nach der Marktakzeptanz gestellt wird und der ausgeweitet ist auf die Marktausbreitung von Innovationen (Diffusion) sowie die Problematik der Innovationsakzeptanz.
Fatigue strength estimation is a costly manual material characterization process in which state-of-the-art approaches follow a standardized experiment and analysis procedure. In this paper, we examine a modular, Machine Learning-based approach for fatigue strength estimation that is likely to reduce the number of experiments and, thus, the overall experimental costs. Despite its high potential, deployment of a new approach in a real-life lab requires more than the theoretical definition and simulation. Therefore, we study the robustness of the approach against misspecification of the prior and discretization of the specified loads. We identify its applicability and its advantageous behavior over the state-of-the-art methods, potentially reducing the number of costly experiments.
Die Anforderungen an die Tragfähigkeit von Seilrollen aus Guss-Polyamiden nehmen aufgrund der Erwartungen hinsichtlich der maximal zu realisierenden Hublasten bei neueren Förder- und Hebegeräte stetig zu. Die heutige Konstruktionspraxis erlaubt für normale Betriebsbedingungen eine gesicherte Auslegung der Seilrollen. Aus jahrelanger Erfahrung sind hierfür Grenzwerte für maximal zulässigen Belastungen im Betrieb unter verschiedensten Betriebsbedingungen gewonnen worden. Jedoch ist bei steigenden Lasten, besserer Ausnutzung des Werkstoffpotenzials oder Modifikationen des Basiswerkstoffs nur noch eine eingeschränkte Bestimmung der tatsächlichen "Worst-Case"-Tragfähigkeit mit dieser Konstruktionspraxis möglich. Berechnungsmodelle einer neuen Bemessungsgrundlage basieren auf der Anwendung der Finite Elemente Methode. Die ersten Berechnungsmodelle aus der modifizierten Bemessungsgrundlage ermöglichen den Einfluss von geometrischen Änderungen der Form bzw. der Ausführung, von lokalen Materialeigenschaften und von realistischere Lastzustände auf den Deformationsund Spannungszustand einer Seilrolle theoretisch zu beschreiben. Weitere Berechnungsmodelle, die z.B. die Erwärmung der Seilrolle durch die Rollreibung zwischen Seil und Seilrolle sowie des Walkens durch die Bewegung des Seiles bei dynamischer Belastung beschreiben können, sind in der Entwicklung. Für den Konstrukteur werden zudem parametrisierte Geometrie-, Last- und FE-Modelle entwickelt, die eine schnelle und betriebssichere Dimensionierung von Seilrollen aus Guss-Polyamiden ermöglichen. Alle theoretischen Ergebnisse werden z.Z. durch umfangreiche Versuche abgesichert.
Computer graphics research strives to synthesize images of a high visual realism that are indistinguishable from real visual experiences. While modern image synthesis approaches enable to create digital images of astonishing complexity and beauty, processing resources remain a limiting factor. Here, rendering efficiency is a central challenge involving a trade-off between visual fidelity and interactivity. For that reason, there is still a fundamental difference between the perception of the physical world and computer-generated imagery. At the same time, advances in display technologies drive the development of novel display devices. The dynamic range, the pixel densities, and refresh rates are constantly increasing. Display systems enable a larger visual field to be addressed by covering a wider field-of-view, due to either their size or in the form of head-mounted devices. Currently, research prototypes are ranging from stereo and multi-view systems, head-mounted devices with adaptable lenses, up to retinal projection, and lightfield/holographic displays. Computer graphics has to keep step with, as driving these devices presents us with immense challenges, most of which are currently unsolved. Fortunately, the human visual system has certain limitations, which means that providing the highest possible visual quality is not always necessary. Visual input passes through the eye’s optics, is filtered, and is processed at higher level structures in the brain. Knowledge of these processes helps to design novel rendering approaches that allow the creation of images at a higher quality and within a reduced time-frame. This thesis presents the state-of-the-art research and models that exploit the limitations of perception in order to increase visual quality but also to reduce workload alike - a concept we call perception-driven rendering. This research results in several practical rendering approaches that allow some of the fundamental challenges of computer graphics to be tackled. By using different tracking hardware, display systems, and head-mounted devices, we show the potential of each of the presented systems. The capturing of specific processes of the human visual system can be improved by combining multiple measurements using machine learning techniques. Different sampling, filtering, and reconstruction techniques aid the visual quality of the synthesized images. An in-depth evaluation of the presented systems including benchmarks, comparative examination with image metrics as well as user studies and experiments demonstrated that the methods introduced are visually superior or on the same qualitative level as ground truth, whilst having a significantly reduced computational complexity.
In dieser Arbeit wird eine Methode zur Darstellung und Generierung von natürlich wirkendem Bewuchs auf besonders großen Arealen und unter Berücksichtigung ökologischer Faktoren vorgestellt. Die Generierung und Visualisierung von Bewuchs ist aufgrund der Komplexität biologischer Systeme und des Detailreichtums von Pflanzenmodellen ein herausforderndes Gebiet der Computergrafik und ermöglicht es, den Realismus von Landschaftsvisualisierungen erheblich zu steigern. Aufbauend auf [DMS06] wird bei Silva der Bewuchs so generiert, dass die zur Darstellung benötigten Wang-Kacheln und die mit ihnen assoziierten Teilverteilungen wiederverwendet werden können. Dazu wird ein Verfahren vorgestellt, um Poisson Disk Verteilungen mit variablen Radien auf nahtlosen Wang-Kachelmengen ohne rechenintensive globale Optimierung zu erzeugen. Durch die Einbeziehung von Nachbarschaften und frei konfigurierbaren Generierungspipelines können beliebige abiotische und biotische Faktoren bei der Bewuchsgenerierung berücksichtigt werden. Die durch Silva auf Wang-Kacheln erzeugten Pflanzenverteilungen ermöglichen, die darauf aufgebauten beschleunigenden Datenstrukturen bei der Visualisierung wieder zu verwenden. Durch Multi-Level Instancing und eine Schachtelung von Kd-Bäumen ist eine Visualisierung von großen bewachsenen Arealen mit geringen Renderzeiten und geringem Memoryfootprint von Hunderten Quadratkilometern Größe möglich.
Generating and visualizing large areas of vegetation that look natural makes terrain surfaces much more realistic. However, this is a challenging field in computer graphics, because ecological systems are complex and visually appealing plant models are geometrically detailed. This work presents Silva (System for the Instantiation of Large Vegetated Areas), a system to generate and visualize large vegetated areas based on the ecological surrounding. Silva generates vegetation on Wang-tiles with associated reusable distributions enabling multi-level instantiation. This paper presents a method to generate Poisson Disc Distributions (PDDs) with variable radii on Wang-tile sets (without a global optimization) that is able to generate seamless tilings. Because Silva has a freely configurable generation pipeline and can consider plant neighborhoods it is able to incorporate arbitrary abiotic and biotic components during generation. Based on multi-levelinstancing and nested kd-trees, the distributions on the Wang-tiles allow their acceleration structures to be reused during visualization. This enables Silva to visualize large vegetated areas of several hundred square kilometers with low render times and a small memory footprint.
We present a system that combines voxel and polygonal representations into a single octree acceleration structure that can be used for ray tracing. Voxels are well-suited to create good level-of-detail for high-frequency models where polygonal simplifications usually fail due to the complex structure of the model. However, polygonal descriptions provide the higher visual fidelity. In addition, voxel representations often oversample the geometric domain especially for large triangles, whereas a few polygons can be tested for intersection more quickly.
In contrast to projection-based systems, large, high resolution multi-display systems offer a high pixel density on a large visualization area. This enables users to step up to the displays and see a small but highly detailed area. If the users move back a few steps they don't perceive details at pixel level but will instead get an overview of the whole visualization. Rendering techniques for design evaluation and review or for visualizing large volume data (e.g. Big Data applications) often use computationally expensive ray-based methods. Due to the number of pixels and the amount of data, these methods often do not achieve interactive frame rates.
A view direction based (VDB) rendering technique renders the user's central field of view in high quality whereas the surrounding is rendered with a level-of-detail approach depending on the distance to the user's central field of view. This approach mimics the physiology of the human eye and conserves the advantage of highly detailed information when standing close to the multi-display system as well as the general overview of the whole scene. In this paper we propose a prototype implementation and evaluation of a focus-based rendering technique based on a hybrid ray tracing/sparse voxel octree rendering approach.
Rendering techniques for design evaluation and review or for visualizing large volume data often use computationally expensive ray-based methods. Due to the number of pixels and the amount of data, these methods often do not achieve interactive frame rates. A view direction based rendering technique renders the users central field of view in high quality whereas the surrounding is rendered with a level of detail approach depending on the distance to the users central field of view thus giving the opportunity to increase rendering efficiency. We propose a prototype implementation and evaluation of a focus-based rendering technique based on a hybrid ray tracing/sparse voxel octree rendering approach.
In recent years, a variety of methods have been introduced to exploit the decrease in visual acuity of peripheral vision, known as foveated rendering. As more and more computationally involved shading is requested and display resolutions increase, maintaining low latencies is challenging when rendering in a virtual reality context. Here, foveated rendering is a promising approach for reducing the number of shaded samples. However, besides the reduction of the visual acuity, the eye is an optical system, filtering radiance through lenses. The lenses create depth-of-field (DoF) effects when accommodated to objects at varying distances. The central idea of this article is to exploit these effects as a filtering method to conceal rendering artifacts. To showcase the potential of such filters, we present a foveated rendering system, tightly integrated with a gaze-contingent DoF filter. Besides presenting benchmarks of the DoF and rendering pipeline, we carried out a perceptual study, showing that rendering quality is rated almost on par with full rendering when using DoF in our foveated mode, while shaded samples are reduced by more than 69%.
Advances in computer graphics enable us to create digital images of astonishing complexity and realism. However, processing resources are still a limiting factor. Hence, many costly but desirable aspects of realism are often not accounted for, including global illumination, accurate depth of field and motion blur, spectral effects, etc. especially in real‐time rendering. At the same time, there is a strong trend towards more pixels per display due to larger displays, higher pixel densities or larger fields of view. Further observable trends in current display technology include more bits per pixel (high dynamic range, wider color gamut/fidelity), increasing refresh rates (better motion depiction), and an increasing number of displayed views per pixel (stereo, multi‐view, all the way to holographic or lightfield displays). These developments cause significant unsolved technical challenges due to aspects such as limited compute power and bandwidth. Fortunately, the human visual system has certain limitations, which mean that providing the highest possible visual quality is not always necessary. In this report, we present the key research and models that exploit the limitations of perception to tackle visual quality and workload alike. Moreover, we present the open problems and promising future research targeting the question of how we can minimize the effort to compute and display only the necessary pixels while still offering a user full visual experience.
Narrow-band YBCO superconducting parallel-coupled coplanar waveguide band-pass filters at 10 GHz
(1993)
Guzzo et al. (Reference Guzzo, Schneider and Nalbantian2022) argue that open science practices may marginalize inductive and abductive research and preclude leveraging big data for scientific research. We share their assessment that the hypothetico-deductive paradigm has limitations (see also Staw, Reference Staw2016) and that big data provide grand opportunities (see also Oswald et al., Reference Oswald, Behrend, Putka and Sinar2020). However, we arrive at very different conclusions. Rather than opposing open science practices that build on a hypothetico-deductive paradigm, we should take initiative to do open science in a way compatible with the very nature of our discipline, namely by incorporating ambiguity and inductive decision-making. In this commentary, we (a) argue that inductive elements are necessary for research in naturalistic field settings across different stages of the research process, (b) discuss some misconceptions of open science practices that hide or discourage inductive elements, and (c) propose that field researchers can take ownership of open science in a way that embraces ambiguity and induction. We use an example research study to illustrate our points.
In the literature on occupational stress and recovery from work, several facets of thinking about work during off-job time have been conceptualized. However, research on the focal concepts is currently rather diffuse. In this study we take a closer look at the five most well-established concepts: (1) psychological detachment, (2) affective rumination, (3) problem-solving pondering, (4) positive work reflection, and (5) negative work reflection. More specifically, we scrutinized (1) whether the five facets of work-related rumination are empirically distinct, (2) whether they yield differential associations with different facets of employee well-being (burnout, work engagement, thriving, satisfaction with life, and flourishing), and (3) to what extent the five facets can be distinguished from and relate to conceptually similar constructs, such as irritation, worry, and neuroticism. We applied structural equation modeling techniques to cross-sectional survey data from 474 employees. Our results provide evidence for (1) five correlated, yet empirically distinct facets of work-related rumination. (2) Each facet yields a unique pattern of association with the eight aspects of employee well-being. For instance, detachment is strongly linked to satisfaction with life and flourishing. Affective rumination is linked particularly to burnout. Problem-solving pondering and positive work reflection yield the strongest links to work engagement. (3) The five facets of work-related rumination are distinct from related concepts, although there is a high overlap between (lower levels of) psychological detachment and cognitive irritation. Our study contributes to clarifying the structure of work-related rumination and extends the nomological network around different types of thinking about work during off-job time and employee well-being.
In the literature on occupational stress and recovery from work several facets of thinking about work in off-job time have been conceptualized. However, research on the focal concepts is currently rather disintegrated. In this study we take a closer look at the five most established concepts, namely (1) psychological detachment, (2) affective rumination, (3) problem-solving pondering, (4) positive work reflection, and (5) negative work reflection. More specifically, we scrutinized (1) whether the five facets of work-related rumination are empirically distinct, (2) whether they yield differential associations with different facets of employee well-being (burnout, work engagement, thriving, satisfaction with life, and flourishing), and (3) to what extent the five facets can be distinguished from and relate to conceptually similar constructs, such as irritation, worry, and neuroticism. We applied structural equation modeling techniques to cross-sectional survey data from 474 employees. Our results provide evidence that (1) the five facets of work-related rumination are highly related, yet empirically distinct, (2) that each facet contributes uniquely to explain variance in certain aspects of employee well-being, and (3) that they are distinct from related concepts, albeit there is a high overlap between (lower levels of) psychological detachment and cognitive irritation. Our study contributes to clarify the structure of work-related rumination and extends the nomological network around different types of thinking about work in off-job time and employee well-being.
Although work events can be regarded as pivotal elements of organizational life, only a few studies have examined how positive and negative events relate to and combine to affect work engagement over time. Theory suggests that to better understand how current events affect work engagement (WE), we have to account for recent events that have preceded these current events. We present competing theoretical views on how recent and current work events may affect employees (e.g., getting used to a high frequency of negative events or becoming more sensitive to negative events). Although the occurrence of events implies discrete changes in the experience of work, prior research has not considered whether work events actually accumulate to sustained mid-term changes in WE. To address these gaps in the literature, we conducted a week-level longitudinal study across a period of 15 consecutive weeks among 135 employees, which yielded 849 weekly observations. While positive events were associated with higher levels of WE within the same week, negative events were not. Our results support neither satiation nor sensitization processes. However, high frequencies of negative events in the preceding week amplified the beneficial effects of positive events on WE in the current week. Growth curve analyses show that the benefits of positive events accumulate to sustain high levels of WE. WE dissipates in the absence of continuous experience of positive events. Our study adds a temporal component and informs research that has taken a feature-oriented perspective on the dynamic interplay of job demands and resources.
Although work events can be regarded as pivotal elements of organizational life, only a few studies have examined how positive and negative events relate to and combine to affect work engagement over time. Theory suggests that, to better understand how current events affect work engagement (WE), we have to account for recent events that have preceded these current events. We present competing theoretical views on how recent and current work events may affect employees (e.g., getting used to a high frequency of negative events or becoming more sensitive to negative events). Although the occurrence of events implies discrete changes in the experience of work, prior research has not considered whether work events actually accumulate to sustained mid-term changes in WE. To address these gaps in the literature, we conducted a week-level longitudinal study across a period of 15 consecutive weeks among 135 employees, which yielded 849 weekly observations. While positive events were associated with higher levels of WE within the same week, negative events were not. Our results support neither satiation nor sensitization processes. However, a high frequency of negative events in the preceding week amplified the beneficial effects of positive events on WE in the current week. Growth curve analyses show that the benefits of positive events accumulate to sustain high levels of WE. WE dissipates in the absence of a continuous experience of positive events. Our study adds a temporal component by highlighting that positive events affect work engagement, particularly in light of recent negative events. Our study informs research that has taken a feature-oriented perspective on the dynamic interplay of job demands and resources.