Abstimmung von Produktions- und Transportlosgrößen zwischen Zulieferer und Produzent

Es wird eine Erweiterung des mehrstufigen stationären Losgrößenproblems mit endlichen Produktionsgeschwindigkeiten um den zeitpunktgeballten Transportvorgang vorgestellt. Diese Darstellung gibt die Beziehungen zwischen Zulieferer, Transporteur und Produzent adäquat wieder. Hinsichtlich der Abstimmung der Entscheidungsgrößen dieser organisatorischen Einheiten wird zwischen einer rein simultanen, einer rein sukzessiven sowie zweier gemischt simultan-sukzessiver Koordinationsarten unterschieden. An Hand einer analytischen Untersuchung werden Unterschiede und Gemeinsamkeiten der jeweiligen Entscheidungsgrößen und der daraus resultierenden Kostenfunktionen dargestellt. Schließlich zeigt eine numerische Analyse die Gesamtkostenunterschiede zwischen der rein simultanen und rein sukzessiven Koordinationsart auf.An extension is introduced to the multi-stage stationary lot-sizing problem with finite production rates by the time-concentrated transportation-process. This representation adequately demonstrates the relations between supplier, carrier and producer. With regard to the reconciliation of the decision variables of these institutional units one differentiates between a pure simultaneous, a pure gradual and two mixed simultaneous-gradual coordination methods. The differences and correspondences of the respective decision variables and the resulting cost functions are demonstrated by means of an analytical examination. Finally, a numerical analysis shows the distinctions in total cost between the pure simultaneous and pure gradual coordination method.     

Stimmrechtsbeschränkung und take-over

Zusammenfassung Aktienoptionen waren Finanzinnovationen, die dem Investor helfen sollen, das Kursrisiko zu vermindern. Der faire Preis für die Option, die Höhe der Risikoprämie, wird mit der Black-Scholes-Formel berechnet. Aktienoptionen sind aber auch Instrumente auf dem Markt für Unternehmenskontrolle. In diesem Falle sind die Konditionen im allgemeinen nicht identisch mit Optionen als Kurssicherungsinstrumenten. Der Aufsatz behandelt die Frage, ob die Konditionen derartiger Optionen fair im Sinne des traditionellen Verständnisses sind. Dem Beitrag liegt ein konkreter Fall zugrunde.     

Quasistatische Zustandsänderungen und ihr Zusammenhang mit den reversiblen und irreversiblen Prozessen der Thermodynamik

Zusammenfassung Bei der Behandlung thermodynamischer Prozesse ist es vorteilhaft, die Begriffe Proze? und Zustands?nderung zu unterscheiden. Zustands?nderungen werden als quasistatisch oder als nichtstatisch bezeichnet, je nachdem, ob sie aus Gleichgewichtszust?nden bestehen oder nicht. Bei der mathematischen Formulierung der beiden Haupts?tze hat man drei F?lle zu beachten: reversible Prozesse mit notwendig quasistatischen Zustands?nderungen sowie irreversible Prozesse mit quasistatischen und mit nichtstatischen Zustands?nderungen. Nur quasistatische Zustands?nderungen lassen sich in thermodynamischen Diagrammen als stetige Kurven darstellen. Die Fl?chen unter diesen Kurven haben verschiedene Bedeutungen, wenn der Proze? reversibel oder irreversibel ist. Herrn Prof. Dr. phil. nat. h.c. Dr. sci. agr. h. c Dr.-Ing.R. Plank zur Vollendung seines 75. Lebensjahres in Dankbarkeit und Verehrung gewidmet.     

Entwicklung eines neuen Meridionalverfahrens für mehrstufige kompakte Axialverdichter und Validierung durch Experimente und CFD-Berechnungen

Development and validation of a universal through flow method applicable to design and analysis of compact multi-stage axial compressors will be described. Our method is based on correlations of the open literature which had been evaluated, selected and improved for this purpose. It contains a span wise mixing model to represent the 3D flow structure. For code validation various test cases are considered covering a wide range of application. Finally, the application of the method to analyse a newly-developed 11-stage gas turbine compressor will be demonstrated. The computed results have been compared with detailed test rig experiments. In addition, multi-stage steady-state computations were executed using a calibrated Navier-Stokes solver for 3D turbulent flows. Very good agreements of computed and measured results were achieved. In particular the through flow solver proves to be very accurate and fast in the prediction of compressor characteristics and has been directly used for optimisation of variable guide vane settings during the compressor test.     

Kavitationsblasen und Ultraschallwellen am Tragflügelprofil

Zusammenfassung Mittels Zeitlupenaufnahmen wurden der zeitliche und ?rtliche Verlauf der Kavitationsblasen an einem Tragflügelprofil im Wasserkanal insbesondere hinsichtlich der Abmessungen und der Verschwindungsstellen der Blasen ermittelt. Es gelang, den Zusammenhang zwischen den charakteristischen Dalen der Ultraschallwellen, die auf Grund der Kavitation am Tragflügelprofil entstehen, und dem Verlauf der Kavitationsblasen zu kl?ren. Mitteilung aus der Institut für Hochgeschwindigkeitsmechanik, T?hoku Universit?t, Sendai, Japan Der Verfasser dankt an dieser Stelle den HerrenH. Takeuchi, I. Chida, M. Hong?, M. Anzai undR. Sal? für ihre bereitwillige Unterstützung der üntersuchungen.     

Die Geschwindigkeit von Gefühlen und Gedanken

Toward the end of the 1840s, Hermann von Helmholtz (1821-1894) began to investigate experimentally the propagation of stimuli within nerves. Helmholtz's experiments on animals and human subjects opened a research field that in the following decades was intensively explored by neurophysiologists and experimental psychologists. Studying the concrete experiemental settings and their local contexts shows how deeply the work of Helmholtz, Adolphe hirsch (1830-1901), Franciscus Donders (1818-1889) and others was embedded in the history of culture and technology. In particular, the rapidly growing technologies of electromagnetism, which gave rise to telegraphy and electric clocks, facilitated the time measurements of 19th-century physiologists and psychologists. However, the transition from frogs to human beings as model organisms confronted the time-measuring psychophysiologists with a whole range of experimental parameters that were difficult to control (temperature, attention etc.). It is no wonder then that it took some 20 years before this branch of research stabilised.     

Aktive Luftfederung – Modellierung,Regelung und Hardware-in-the-Loop-Experimente

It is assumed that autonomous driving is the key technology for our future transportation system. However, studies have shown that the incidence of kinetosis, i. e. motion sickness, is significantly higher in autonomous driving cars than in conventional vehicles. Since especially vertical dynamic oscillations (heave) in the frequency range from 0.1?Hz to approx. 1?Hz are perceived as particularly disturbing, active spring-damper systems can provide a remedy. The active air spring, which we develop at the Institute for Fluid Systems at TU Darmstadt, is such a system. It combines the advantages of an air spring (level control, load independent body natural frequency, etc.), which result from the separation of the functions “load carrying” and “energy storing”, with those of an active system. The actuating force is generated by adjusting the load-carrying (pressure-effective) area of the air spring during operation with an edge frequency of more than 5?Hz. This is realized by adjusting the air spring rolling piston diameter with four radially adjustable segments. For this purpose, a compact hydraulic linear actuator was developed which is integrated into the air spring piston.In this article, we describe the concept of the active air spring and introduce the functional prototype. Thereafter, the general optimal vertical dynamic design of an active system is discussed using the example of a quarter car model and the influence of system variables such as actuating force and actuating frequency is addressed. In the next step, a simple modeling of the overall system is carried out with regard to the \(\text{H}_{2}\)-optimal controller design and the suitability of the actuator concept for use in an active chassis as well as the robustness of the controller is shown exemplarily. In order to optimally tune the system to reduce oscillations that cause kinetosis and decrease driving comfort, frequency-specific weighting filters in accordance with VDI Guideline 2057 are used for the control design. Finally, the functional performance of the active air spring is demonstrated in hardware-in-the-loop experiments in which the functional prototype is coupled with a virtual quarter vehicle in a real-time simulation environment.     

Experimentelle und theoretische Untersuchungen zu Hochdruck-Sicherheitsventilen – Auslegung und Design unterstützt durch numerische Rechenmethoden (CFD)

High-pressure safety valves with set pressures of more than 200 bar are required in industry, e.g. for polyethylene and synthesis gas applications. They are presently sized according to ISO 4126-1. Only equations for ideal gases are presented there, and there are no indications as to how the real gas factor and the adiabatic exponent for real gases are to be calculated. For this reason, an equation for the critical mass flow rate of a real gas through a nozzle was derived and compared with the model according to EN-ISO 4126-1 and with experimental data. It is recommended that the current ISO-standard be supplemented by the nozzle flow model for real gases. The first numerical calculations (ANSYS-CFX) show that the discharge coefficient for a high pressure safety valve measured at moderate pressures can be extrapolated to very high pressures if it is used in conjunction with the nozzle flow model for real gases. However, this numerical result must yet be validated for further valve types by experiment. For this purpose, BASF has set up a high pressure valve test facility in Ludwigshafen.     

Antike Diätetik—Lebensweise und Medizin

The wide reaching meaning of eating and drinking is already recognized in antiquity. The declared aim of antique dietetics is the upbringing to a healthy lifestyle. Fundamental considerations of dietetic, theoretically organized ideas can be traced back to the Presocratics, who, for the first time in cultural history, let themselves be guided by direct observations from nature. Working from the meaning of dietetics as pure nutritional teaching, one can see in the Corpus Hippocraticum a significant, systematic attempt to put forth dietetics as a concept of lifestyle. Here a central aspect is that of equilibrium, as it is expressed in the rule of the four humours. Dietetics continually become a connecting link between Natural Philosophy and Anthropology and a lifestyle orientated to nature. Finally, Galen introduces a further systematization of the already existing and the increasingly modified. Nutrition and health are brought into association and the theoretical presupposed practically overturned. In late Antiquity dietetical outlooks continue to be discussed, which were transferred to the Middle Ages and still show practical relevance.     

Bilder zwischen. Öffentlichkeit und wissenschaftlicher Praxis

The paper investigates how visual resources can be fruitfully used to study the history of science, medicine, and technology from a practical point of view. Two new international and interdisciplinary trends within recent historiography are reviewed: the history of visualisation and the history of popularisation. The results of both trends need to be combined in order to understand the ways in which images of science have been used to communicate science from its place of production within the laboratory to its users within the wider society. From the proposed perspective, visual representations of science (i.e. portraits, images of scientific instruments, measurement results and abstractions) are discussed as a distinct medium in which knowledge producers have transmitted and transformed their findings to the acquirers of knowledge. The paper introduces the wider historiographical framework for a discussion of the following four papers published in this issue of NTM.     

Wissen und Umwelt in der „partizipatorischen Diktatur“

The GDR was an ecological failed state in 1989/90. But while public input and critical environmental groups protested more openly against environmental problems during the 1980s, the established sciences remained strangely mute and appeared unable to develop appropriate approaches to solving the environmental crisis. Almost 20 years earlier, however, an environmental policy departure that was largely supported by scientific reform initiatives had begun in the GDR. The inclusion of the concept of conserving nature and the environment in the 1968 constitution and the adoption of the land improvement law two years later were the expression of a socio-political consensus on the environmental issue.How can this sharp discrepancy be explained? The article investigates the influence of scientific environmental concepts on the departure in environmental policy in the GDR. The example of scientific nature conservation, which had been institutionally anchored in the German Academy of Agricultural Sciences since 1951, shows that conservationists underwent a period of “normalization” in the 1950s, which was an essential prerequisite for giving their concerns political legitimacy. This forced adaptation process not only influenced the concepts and goals of East German nature conservation, rather also opened up participatory opportunities for its protagonists.The essay argues for a reassessment of East German environmental history, which so far has only been considered from the perspective of how it ended. Furthermore, it is argued that the conceptual concept of the “participatory dictatorship” (Fulbrook) should be applied to the history of science in the GDR in order to expand existing approaches.     

Milderung von Kerbwirkungen durch Entlastungsschnitte und Verschwächungen

Zusammenfassung Bei Flachst?ben, welche unter Zugbeanspruchung stehen, treten an Bohrungen und Kerben Spannungsspitzen auf, welche den mehrfachen Wert der Nennspannung eirreichen und insbesondere bei Schwingungsbeanspruchung das Festigkeitsverhalten ungünstig beeinflussen. Man kann die Beanspruchung dadurch herabsetzen, da? man den Stab an der Kerbstelle verst?rkt. Bei einachsiger Zugbeanspruchung besteht weiterhin die M?glichkeit, den Kraftflu? durch Entlastungskerben abzulenken. Derartige Entlastungskerben k?nnen zwar eine bedeutende Spannungsverminderung an der gef?hrdeten Stelle ergeben, an den Entlastungskerben entstehen jedoch neue Spannungsspitzen, die sich u. U. ungünstig auswirken. Es wurde daher eine L?sung gesucht, welche es gestattet, ohne Verst?rkungen auszuommen, die aber die nachteile der Entlastungskerben vermeidet. VDI Die Mittel für die Untersuchungen wurden von der Vereinigung von Freunden der Technischen Hochschule Stuttgart zur Verfügung gestellt.     

Kombination von Radial- und Seitenkanalstufen für Turboverdichter

Unsteady gas pressure oscillations occur at impeller outlet and diffuser of radial and side channel compressors, engendered by the blades grid of the impeller. They have effect beyond the limits of inlet and outlet. If a radial stage is coupled to a side channel stage, then the unsteady gas pressure oscillations of the side channel stage have an effect inside the radial stage affecting flow and characteristic curve. Because of that, the radial stages unstable characteristics and the limit of rotating stall can be moved to lower volume flows or completely suppressed by connecting a side channel stage before or behind it. Therefore the permissible range of operation of combined compressor stages can be extended compared with a radial compressor stage. Moving the limit of rotating stall of the radial compressor stage and lower the gas pressure oscillations caused by Rotating Stall as a result of the side channel stages unsteady gas pressure oscillations will be proved experimental. As a criterion for Rotating Stall in radial compressor stages also the proportion between RMS of gas pressure oscillations and the total pressure increase in the radial compressor stage can be used.     

Zur Beugungstheoretischen Berechnung der Punktbild- und Übertragungsfunktion Optischer Systeme

Since it is generally known for which image receptor optical systems are used and what sort of objects will be imaged, a system of optical transfer functions guaranteeing optimum image formation can always be given. Starting from this situation, the paper studies problems when lenses should be corrected automatically with the aid of a system of OTF's or other OTF-based criteria. Summarizing the work of Hopkins and King, the usefulness for practical application is discussed. The cost of computation has been the most important restriction preventing a widespread use of well-known techniques, but with the development of cheaper and quicker computers there is no reason for not designing optical systems of desired quality for the envisaged application. It is emphasized that the final average OTF value which is used as a criterion for optimizing the design can also be used to specify the image quality by a number and can be compared by measuring the real OTF values with the optical system produced later on according to the best constructional data found.     

Die „Stimmung“ im Spannungsfeld zwischen Natur- und Geisteswissenschaften

The Use of Stimmung in the Sciences and Humanities. Looking at the History of the Division between the “Two Cultures” from the Perspective of a Figure of Thought This article questions the existence of a schism between the 'two cultures' (C.P. Snow) by showing that the dichotomy between the sciences and the humanities is part of a narrative that developed in the 19th century. By focusing on the historical usage of Stimmung as specific figure of thought in the discourses of physiology, psychology, psychiatry, and aesthetics, the notion of a divorce between the sciences and the humanities is replaced by one of continuous exchange between various fields of knowledge. Stimmung, a term originally referring to the musical praxis of tuning instruments, was used extensively in German publications between 1770 and 1890 in all the fields of knowledge mentioned above. Its circulation between these fields both before and during the formation of independent disciplines in the late 19th century illustrates the continuity of exchange, even in those cases where the actors themselves use Stimmung as an argument for positioning their specific area of research within one of the “two cultures”.