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"Schnitzeljagd" in Arneburg
(2015)
1. Introduction
(2023)
For most separations fully thermally coupled distillation columns are thermodynamically more efficient than conventional arrangements. In spite of the superiority of double-effect distillation systems to a single column concerning energy savings these systems are not often used in the industrial practice, because of the disadvantages in dynamic operability. Generally the product switchover is a complicated and protracted operation, where many process variables must be changed simultaneously. The economic and ecological interest is to minimize the time of switchover periods, which are generally non-productive and require long times especially for coupled systems. The aim of this study is to reduce the time needed for the product switchover of coupled distillation systems. This paper presents a new product switchover strategy, which will lead to a time saving of 57%. Furthermore, a new startup strategy is developed and verified in experimental studies. The results demonstrate that using the optimized startup strategy a time saving of 57% can be achieved too and thereby these unproductive periods can be reduced significantly.
Copyright © 2001 Elsevier Science B.V.
An innovative net-based methodology to integrate qualitative and quantitative analysis of distributed software systems is outlined, and an on-going prototype implementation of a related graphic-oriented tool kit is sketched. The proposed method combines qualitative analysis, monitoring and testing as well as quantitative analysis on the basis of a net-based intermediate representation of the distributed software system under consideration. All transformations (from the distributed software system into a first Petri net model, and between the different kinds of net models) can be made formally, and therefore automated to a high degree. The evaluation of quantitative properties is based on so-called object nets which are obtained by a property-preserving structural compression and quantitative expansion of the qualitative model. In this way, the frequency and delay attributes necessary to generate quantitative models are provided by the monitoring and testing component.
In this work, the most relevant 3D LiDAR technologies and their applications in 2022 were investigated. For this purpose, applications of LiDAR systems were classified into the typical application areas "3D modeling", "smart city", "robotics", "smart automotive" and "consumer goods". The investigation has shown that neither "mechanical" LiDAR technologies, nor so-called solid-state LiDAR technologies, nor "hybrid" LiDAR technologies can be evaluated as optimal for the typical application areas. In none of the application areas could all of the elaborated requirements be met. However, the "hybrid" LiDAR technologies such as sequential MEMS LiDAR technology and sequential flash LiDAR technology proved to be among the most suitable for most typical application areas. However, other technologies also tended to be suitable for individual typical application areas. Finally, it was found that several of the LiDAR technologies investigated are currently equally suitable for some typical application areas. To evaluate the suitability, concrete LiDAR systems - of different technologies and properties - were compared with the specific requirements of exemplary applications of an application area. The results of the investigation provide an orientation as to which LiDAR technology is promising for which application area.
A theoretical model for the tread slip and the effective rolling radius of the tyres in free rolling
(2017)
Konkav gewölbte Glasfassaden von Großbauten können bei ungünstiger Orientierung zur Sonne zum Brennspiegel werden. Unfreiwillig berühmt gewordene Beispiele sind das Vdara-Hotel in Las Vegas und das “Walkie-Talkie”-Hochhaus in London. Dieser Effekt tritt auch nur an bestimmten Tagen bei passendem Sonnenstand auf. Da die Fassaden keine perfekten Parabolspiegel sind, produzieren sie keinen scharfen Brennpunkt, sondern aufgeweitete Brennflecke, sogenannte Kaustiken. Trotzdem können dort hohe Bestrahlungsstärken auftreten. Simulationen und Experimente mit Modellen bestätigen dies.
Bei dem zu beobachtenden Altern der Bevölkerung stellt sich die Frage nach der künftigen Wettbewerbsfähigkeit des Industriestandorts Deutschland, der mit gealterten Belegschaften am Weltmarkt bestehen muss. Besonders akzentuiert könnte die Problemlage bei innovationsintensiven Tätigkeitsfeldern sein, in denen die hohen Anforderungen an aktuelles Wissen, Belastbarkeit und Kreativität nach dem „Defizit-Modell“ des Alterns eher mit Jugend assoziiert werden. Folglich müssten Unternehmen besonders in innovationsnahen Tätigkeiten der Industrie eine rapide Verjüngung anstreben. Eine Untersuchung der westdeutschen Industrie zwischen 1990 und 1996 zeigt jedoch, dass es bei „Innovatoren“ (Ingenieure, Techniker) keinen überdurchschnittlichen altersselektiven Personalabbau gegeben hat. Vielmehr ist die allgemeine „Verjüngung“ der Industriebelegschaften auf den deutlichen Personalabbau in der Großindustrie, der im Wesentlichen über Altersabgänge geregelt wurde, zurückzuführen. In der Entwicklung der industriellen Personalstruktur findet sich also kein Beleg für die These vom Alter als spezifisches Innovationsproblem.
An approach for analyzing business process execution complexity based on textual data and event log
(2023)
With the advent of digital transformation, organizations increasingly rely on various information systems to support their business processes (BPs). Recorded data, including textual data and event log, expand exponentially, complicating decision-making and posing new challenges for BP complexity analysis in Business Process Management (BPM). Herein, Process Mining (PM) serves to derive insights based on historic BP execution data, called event log. However, in PM, textual data is often neglected or limited to BP descriptions. Therefore, in this study, we propose a novel approach for analyzing BP execution complexity by combining textual data serving as an input at the BP start and event log. The approach is aimed at studying the connection between complexities obtained from these two data types. For textual data-based complexity, the approach employs a set of linguistic features. In our previous work, we have explored the design of linguistic features favorable for BP execution complexity prediction. Accordingly, we adapt and incorporate them into the proposed approach. Using these features, various machine learning techniques are applied to predict textual data-based complexity. Moreover, in this prediction, we show the adequacy of our linguistic features, which outperformed the linguistic features of a widely-used text analysis technique. To calculate event log-based complexity, the event log and relevant complexity metrics are used. Afterward, a correlation analysis of two complexities and an analysis of the significant differences in correlations are performed. The results serve to derive recommendations and insights for BP improvement. We apply the approach in the IT ticket handling process of the IT department of an academic institution. Our findings show that the suggested approach enables a comprehensive identification of BP redesign and improvement opportunities.
Modular process nets are a graphical and formal notation for the representation of technical and business process models containing concurrent activities. Originally this class of Petri nets was developed for the modeling, analysis, simulation and control of workflows and computer-based process control systems, but it is also suitable for use in all other areas where a formal but comprehensible description of complex processes is needed. After a description of the basic aims and design decisions for modular process nets, the report gives a brief introduction to low-level Petri nets including different types of transition rules and aspects of the descriptive and prescriptive use of process models. The main and most innovative points which are explained in more detail are the introduction of a hierarchical module concept for nets and the definition of elementare process nets. The module concept is part of a more general ("object-based") approach to Petri nets allowing severaltypes of ab straction, whereas the main points of elementary process nets are synchronous and asynchronous communication between separately interpreted net instances via events and token passing. Modular process nets are low-level Petri nets equipped with these module and communication concepts and optionally enhanced by die use of a task concept, a method known from the areas of computer-supported cooperative work (CSCW) and work-flow management. Because the report is aimed at a systematic and easy-to-understand introduction to modular process nets, it provides a precise explanation of this net class which is kept as informal as possible and enhanced by some typical application examples
Two problems that appear in the linearization of certain free boundary value problems of the hydrodynamics of two viscous fluids are studied in the strip-like domain
Π = {x = (x1, x2) ∈ ℝ2 : x1 ∈ ℝ1, (0 < x2 < h*) ∨ (h* < x2 < 1)}.
The first problem arises in the linearization of a two-layer flow down a geometrically perturbed inclined plane. The second one appears after the linearization of a two-layer flow in a geometrically perturbed inclined channel with one moving (smooth) wall. For this purpose the unknown flow domain was mapped onto the double strip Π.
The arising linear elliptic problems contain additional unknown functions in the boundary conditions. The paper is devoted to the investigation of these boundary problems by studying the asymptotics of the eigenvalues of corresponding operator pencils. It can be proved that the boundary value problems are uniquely solvable in weighted Sobolev spaces with exponential weight. The study of the full (nonlinear) free boundary value problems will be the topic of a forthcoming paper.
In den letzten Jahren gab es einen wahren Boom von Neugründungen so genannter Science Center. Sie sollen die Naturwissenschaften insbesondere die Physik für einen breiten Personenkreis erfahr- und lernbar machen. In loser Folge werden wir einige dieser Center im deutschsprachigen Raum vorstellen. Der vorliegende einführende Beitrag gibt eine kurze Übersicht über Konzepte, Anliegen und Trends dieser Einrichtungen.
Anordnung des HmbBfDI gegen Facebook - Dringlichkeitsanordnung statt Zusammenarbeit und Kohärenz?
(2021)
Anwendungsbereiche und Eignung der Szenariotechnik und des Roadmapping im Technologiemanagement
(2004)
The public sector faces several challenges, such as a number of external and internal demands for change, citizens' dissatisfaction and frustration with public sector organizations, that need to be addressed. An alternative to the traditional top-down development of public services is co-creation of public services. Co-creation promotes collaboration between stakeholders with the aim to create better public services and achieve public values. At the same time, data analytics has been fuelled by the availability of immense amounts of textual data. Whilst both co-creation and TA have been used in the private sector, we study existing works on the application of Text Analytics (TA) techniques on text data to support public service co-creation. We systematically review 75 of the 979 papers that focus directly or indirectly on the application of TA in the context of public service development. In our review, we analyze the TA techniques, the public service they support, public value outcomes, and the co-creation phase they are used in. Our findings indicate that the TA implementation for co-creation is still in its early stages and thus still limited. Our research framework promotes the concept and stimulates the strengthening of the role of Text Analytics techniques to support public sector organisations and their use of co-creation process. From policy-makers' and public administration managers' standpoints, our findings and the proposed research framework can be used as a guideline in developing a strategy for the designing co-created and user-centred public services.
360-degree image and movie content has gained popularity over the media and the MICE (Meeting, Incentive, Conventions, and Exhibitions) industry in the last few years. There are three main reasons for this development. First, on the one hand, it is the immersive character of this media form, and, on the other hand, the development of recording and presentation technology has made significant progress in terms of resolution and quality. Third, after a decade of dynamic rising, the MICE Industry focuses on a disruptive change for more digital-based solutions. 360-degree panoramas are particularly widespread in VR and AR technology. However, despite the high immersive potential, these forms of presentation have the disadvantage that the users are isolated and have no social contact during the performance. Therefore, efforts have been made to project 360-degree content in specially equipped rooms or planetariums to enable a shared experience for the audience. One application area for 360-degree panoramas and films is conference rooms in hotels, conference centers, and any other venues that create an immersive environment for their clients to stimulate creativity. This work aims to overview the various application scenarios and usability possibilities for such conference rooms. In particular, we consider applications in construction, control, tourism, medicine, art exhibition, architecture, music performance, education, partying, organizing and carrying out events, and video conferencing. These applications and use scenarios were successfully tested, implemented, and evaluated in the 360-degree conference room “Dortmund” in the Hotel Park Soltau in Soltau, Germany. Finally, the advantages, challenges, and limitations of the proposed method are described.
Arc attachments on aluminium during tungsten electrode positive polarity in TIG welding of aluminium
(2011)
In modem AC power sources, both balance and current of EP (tungsten electrode positive) and EN (tungsten electrode negative) can be readily adjusted. According to conventional assumptions the surface of aluminium workpieces is cleaned during EP but the tungsten electrode is more heated due to electron work function. During EN the tungsten electrode cools down and the workpiece is melted. Therefore, optimal settings of the power source mostly aim for maximal penetration and minimal electrode wear. This paper presents a study of arc attachments in TIG welding on aluminium. Two different arc attachments to the cathodic workpiece could be attested with only one of them actually cleaning the surface. The first one is a spot mode (highly dynamic) that attaches to the edges of oxide layers and cracks them. The second one is also a spot mode, but it attaches to weld pools. It does not clean the surface but heats the base material intensively. Both arc attachment modes compete against each other. As a result, the cleaning area narrows with wider weld pools due to an increasing attachment to the weld pool during EP. The influences on the arc attachment to the aluminium cathode as well as the contradictions in present literature are discussed. Possible adjustments of the AC balance for optimized processes are proposed.
Abstract
So far experiments with artificial halos from single transparent crystals have suffered from the lack of apparatus that allows simultaneous rotation around two and three axes. A new setup is presented which overcomes these restrictions by combining electrical as well as pneumatic concepts. This enables reproducible experiments of the most common halos observed in nature and for the first time artificial ring halos from single hexagons rotating around three axes simultaneously. In addition, an old qualitative halo demonstration based on perceived colors of rotating colored areas whose contours represent scattering plots has been reinvestigated and the usually nonsaturated color of artificial parhelia was visualized using a crossed prism method. These new experiments are discussed in the context of all known artificial halo experiments.
© 2014 Optical Society of America
Assessing business process complexity based on textual data: Evidence from ITIL IT ticket processing
(2021)
Asymmetrische Polarlichter
(2009)
We present simple radiative transfer models for the radiance and color of atmospheric optical phenomena. Skylight, halos, and rainbows are treated as singly scattered sunlight that is depleted by scattering as it passes through a plane-parallel atmosphere and a vertical rain shaft or a geometrically thin cloud layer. Skylight in a molecular atmosphere grades from deep blue at the zenith to pale blue near the horizon whenever the solar zenith angle sun ≤ 80°. Skylight near the horizon is orange resulting from wavelength-dependent scattering by air molecules and aerosol particles through a long oblique path through the atmosphere when the sun is low in the sky (sun ≥ 85°). Halos (and coronas) seen through clouds facing the sun are brightest for cloud optical depth τcld ≈ cos(sun), and fade to obscurity for τcld ≥ 5. Rainbows (and glories), seen by light that is backscattered from clouds, also appear most dramatic when 0.2 ≤ τcld ≤ 1, but remain visible even in the thickest clouds.
Auf dem Weg zum Replikator
(2022)
Mit kommerziellen Infrarotkameras lassen sich bereits seit einigen Jahren erfolgreich ausgewählte Gase qualitativ nachweisen. Voraussetzung ist ein thermischer Kontrast des Gases zum Hintergrund. Laboruntersuchungen haben gezeigt, dass auch CO2 ohne Probleme nachweisbar ist. Im Labor können bei Hintergrundtemperaturen von nur 35 °C minimale Gasvolumenströme von 1ml/min, entsprechend 0,5 m3/Jahr, detektiert werden, was Anwendungen beispielsweise im Bereich der CCS-Technologie möglich erscheinen lässt.
This article forms the second of two papers on the subject of microwave cookers. In the first paper Michael Vollmer describes the physics behind the production of microwaves in the magnetron of the oven, the waveguide and the interaction between the microwaves and the food. This article looks at the physics of cooking, and how the appliance and the food industries have developed products which are now part of many of our students' lifestyles. We include many interesting demonstrations that illustrate this history and which could be used to teach many principles of physics.
Bahn und Bürger
(2016)
Bahn wählen! (Editorial)
(2017)
The results of an experimental study of the optical and photoelectrical properties of Eu-containing lead chalcogenides and superlattices are presented. From both sets of experiments band offset data for the lead chalcogenide-europium chalcogenide heterojunction are derived. The results are compared with the data obtained from a linear interpolation of the band structures between those of the binaries.
Baustelle Digitalisierung
(2016)
Begehrt: Die Generation Y
(2012)
Die Healthcare-Branche steht vor vielfältigen Herausforderungen. Eine nicht zu unterschätzende ist die Integration einer neuen Mitarbeitergeneration, der Generation Y. Die Ende der 80er Jahre geborenen Young Professionals stehen dem Arbeitsmarkt noch etwa 40 Jahre zur Verfügung. Nutzen Sie deren Potenzial – wir zeigen Ihnen wie.
Beschreibung finiter plastischer Deformationen von Einkristallen mittels materieller Isomorphismen
(1995)
Im Bereich des Querschnittsübergangs der Federstelle bilden sich unter ungünstigen Umständen im Fuß von Zungenschienen Ermüdungsrisse, die letztlich den Bruch der Schiene verursachen können. Zur Qualifizierung der Bewertungskriterien, d.h. des Prüfzyklusses der zerstörungsfreien Prüfung der Zungenschienen, wird die bruchmechanische Analyse als Monte-Carlo-Simulation gestaltet. Aus dem ungünstigsten Risswachstumsverhalten wird für die zerstörungsfrei ermittelte Rissgröße der erforderliche Prüfzyklus in Abhängigkeit von der Betriebsbelastung abgeleitet.
Blackbox Cloud Computing
(2011)
Water can exhibit many different colors due to a variety of physical properties. Here, we focus on some observable colors within very pure freshwater. We only treat the absorption of light due to electronic and ro-vibrational excitations and scattering due to refractive index fluctuations of the water and the respective consequences for the appearance of colors.
Bouncing Poppers
(2015)
Abstract
Toys are known to attract interest in physics and they are therefore often used in physics teaching of various topics. The present paper deals with a simple toy, the so-called “hopper popper,” which, similar to superballs, can be used when teaching mechanics. We suggest some experiments and describe the basic physics of this toy, also providing background information for teachers.
How do we interact with the digital world in the future by only using our thoughts to interact? To interact with the digital world, we use gestures (most common: swipe gestures), voice, facial expressions and mental commands. The latter has become more important by recent press releases about scientific achievements, for example, from Neuralink [1] using invasive technology to control a computer game by thoughts only [2]. Another study says an application can display text on a screen by just thinking about a word [3]. Currently, BCIs are mainly developed for neurotechnology and healthcare. However, it is a question of time when these services will be available for commercial products for everyday life. (Until then, manufacturers have to minimize health risks and face privacy and safety regulations.) The thesis is that in the future, you will be able to interact with your digital devices just by using your thoughts and you’ll do much faster. This makes sense in many situations where you f. e. do not have a free hand (manufacturing, sports) or cannot speak (underwater). But for such services, you cannot rely on conventional visual design guidelines or interaction patterns, frameworks or libraries. Navigation interacting with a digital service by mental command has a lot of advantages, the human brain comes naturally with some specific features that force us to find a radically new way to interact with digital interfaces. The following study introduces you first into working conditions with mental commands, comparing invasive and non-invasive technologies, and later on comparing several possibilities of interaction patterns for a BCI of everyday usage. [1] Neuralink is a US neurotechnology company founded in July 2016 by Elon Musk and eight other persons. Neuralink’s goal is to develop a device for communication between human brain and computers, a so-called brain-computer-interface(BCI). [2] The Guardian, Fr. 9th April 2021 “Elon Musk startup shows monkey with brain chip implants playing video game”. https://www.theguardian.com/technology/2021/apr/09/elon-musk- neuralink-monkey-video-game . [3] Scientific American, 15th July 2021, Neuroscience, author Emily Willingham: “New Brain Implant Transmits Full Words from Neural Signals”.