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Dieser Beitrag behandelt ein erweitertes analytisches Berechnungsmodell zum mechanischen Verhalten von beliebig rechtwinklig berandeten Mehrschraubenverbindungen (MV). Es werden die Modellvoraussetzungen, -einschränkungen, Theorie und Ergebnisgüte vorgestellt. Dazu werden die Ergebnisse des analytischen Berechnungsmodells den Ergebnissen der numerischen Untersuchungen gegenübergestellt.
Die mechanischen Eigenschaften additiv gefertigter Bauteile lassen sich nicht nur durch bessere Verfahrens- und Anlagentechnik steigern. Vor allem beim Lasersintern lohnt sich ein genauer Blick auf das eingesetzte Polymerpulver. Eine umfangreiche Untersuchung zeigt, warum und wie sich eine spezifische Pulverqualifizierung auswirkt.
The mechanical properties of additively produced components can only be increased by means of improved processing and plant technology. Particularly with laser sintering, a closer look at the polymer powder used is worthwhile. A comprehensive investigation shows why and how such a specific powder qualification has an effect.
Polymer powders for laser sintering must exhibit special intrinsic and extrinsic properties. A new concept for the characterization and evaluation of laser sintering powders permits conclusions to be drawn about aging as well as the suitability of novel powder systems – even before the first build job.
Um konkrete Kundenanforderungen beim Vertrieb neuer Fahrzeuge zuverlässig berücksichtigen zu können, wurde ein Verfahren erarbeitet, mit dem sich Straßen aus Sicht wesentlicher Einsatzparameter wie z.B. die Straßengüte, der Straßentyp sowie die Längs- und Querdynamik aus Sicht der Beanspruchung bewerten und kategorisieren lassen. Das Belastungs- und Beanspruchungsgeschehen lässt sich weitgehend fahrzeugunabhängig nach Höhe, Häufigkeit und Frequenz anhand erfasster Beschleunigungen zutreffend beschreiben. So können Straßen aus Sicht der Beanspruchung bewertet und in Wort und Bild beschriebenen Straßenqualitäts-klassen zugeordnet werden. Umgekehrt erlauben geeignete Kunden-Abfragen mittels eines Anforderungs- und Einsatzkataloges zu Straßenqualität und Einsatzparametern, die kundengerechte Konfiguration von Fahrzeugen.
Eine Möglichkeit zum verstärkten Schutz kühlpflichtiger Molkereiprodukte gegenüber den in der Logistikkette auftretenden mechanischen Belastungen besteht in der räumlichen Trennung von Lebensmitteln und Temperierelementen innerhalb der Versandverpackung. Je nach Art der Isolierverpackung kann das Temperaturhaltevermögen durch die optimierte Anordnung der Temperierelemente deutlich gesteigert werden.
Der Versand kühlpflichtiger Molkereiprodukten muss unter Einhaltung eines definierten Temperaturbereichs erfolgen. Die systematische Analyse auftretender Wärmetransportprozesse an Isolierverpackungen verdeutlicht deren Aufbau und Wirkungsprinzip und signalisiert ergebnisrelevante Einflussgrößen auf das Temperaturhaltevermögen.
Die rasant voranschreitende Digitalisierung treibt die Vermarktung und den Vertrieb von Lebensmitteln via Internet voran. Allerdings weisen die meisten Molkereiprodukte eine enorme Empfindlichkeit gegenüber den in der Logistikkette typisch auftretenden Belastungsarten auf. Die Sicherstellung eines hohen Qualitätsniveaus fordert deren verstärkten Schutz durch eine geeignete Versandverpackung.
In order to be able to reliably take account of specific customer requirements when selling new vehicles, a method has been developed with which roads can be compared from the point of view of essential operational parameters such as, evaluate and categorize the road grade, the type of road and the longitudinal and lateral dynamics in terms of the load. The load and stress conditions can be described largely vehicle-independent according to height, amount and frequency based on detected accelerations. Hence, roads can be assessed in view of stress and combined to street-quality classes described in words and pictures. Conversely, suitable customer queries by means of a requirement catalog for road quality and operational parameters allow a specific configuration of vehicles.
Equations of the form ?[?] = 0, ?: ? ⟶ ?̅ smooth, ?, ?̅ real Banach spaces are investigated with the aim of continuing the basic solution ?[0] = 0 with ? ′ [0] Fredholm operator to a solution curve ?[?(?)] = 0 with the implicit function theorem. If ? ′ [0] is surjective, then the transversality condition of the implicit function theorem can be satisfied in a straightforward way, yielding a regular solution curve, whereas otherwise the equation ?[?] = 0 has to be extended appropriately for reaching a surjective linearization accessible to the implicit function theorem. This extension process, implying in the first step the standard bifurcation theorem of simple bifurcation points, is continued arbitrarily, yielding a sequence of bifurcation results presumably being applicable to bifurcation points with finite degeneracy.
The system of undetermined coefficients of a bifurcation problem
?[?] = 0 in Banach spaces is investigated for proving the existence of families of solution curves by use of the implicit function theorem. The main theorem represents an Artin-Tougeron type result in the sense that approximation of order 2? ensures exact solutions agreeing up to order ? with the approximation
[13], [22]. Alternatively, it may be interpreted as Hensel’s Lemma in Banach spaces. In the spirit of [9] and [18], the required surjectivity condition is interpreted as a direct sum condition of order ? that allows for solving the remainder equation
with respect to graded subspaces derived from an appropriate filtration [24], [25]. In the direction of these subspaces, the determinant can be calculated in a finite dimensional setting, enabling the investigation of secondary global bifurcation phenomena by sign change of Brouwer’s degree [18]. The direct sum
condition seems to be a generalization of the direct sum condition introduced in [9].
The implicit function theorem delivers stability of ? leading coefficients [?̅1 , … , ??̅] with respect to perturbations of order 2? +1 and uniqueness in pointed wedges around the solution curves. Further, denoting by ?̅∞ the subset of arc space ?∞ with [?̅1 , … , ??̅] fixed, ?̅∞ is iteratively approximated by ?̅ 2?+? as ? → ∞. In addition, a lower bound of the Greenberg function ?(?) of a singularity is constructed by use of a step function obtained from ?-degree of different solution curves.
Finally, based on Kouchnirenko’s theorem [17] and an extension in [6], the results are applied to Newton-polygons where it is shown that the Milnor number of a singularity can be calculated by the sum of ?-degrees of corresponding solution curves. Simple ???-singularities are investigated in detail. The main theorem represents a version of strong implicit function theorem in Banach spaces, possibly comparable to theorems in [2]. Moreover, our aim is to extend the direct sum condition of order ? from [9] to certain topics in singularity and approximation theory. Generalizations to modules as well as specializations to polynomials seem to be promising.
A note on an expansion formula with application to nonlinear Differential-Algebraic-Equations
(2019)
In [DL] systems of differential polynomials are investigated with
respect to properties of Artin approximation type. The key tool in [DL] is an extended version of a formula by Hurwitz [Hu] expressing high order derivatives of an expansion by lower ones. The formula is further refined in [VFZ] to deliver sufficient conditions concerning the existence of power series solutions of scalar algebraic differential equations of order?.
In the paper at hand, the main results from [VFZ] are first reproduced and further extended to systems of nonlinear differential algebraic equations. In addition, a simple extension of Tougeron’s implicit function theorem is given in a specific constellation.
The results follow from [S1], [S2] where Artin approximation is treated within a Banach space setting, thereby constructing an expansion formula that expresses accurately the required dependency of low and high order derivatives within the system of undetermined coefficients.
Tougeron’s implicit function theorem and Hensel’s lemma are well known representatives concerning 2?-approximation/?-nondegeneracy implying existence of solutions with identity of order ?. This note aims to extend this
principle to equations ?[?] = 0 in Banach spaces, using ?-transversality concepts, which may geometrically be interpreted as generalized cones spanned by
submanifolds, each characterized by a certain expansion rate.
The number of manifolds in the cone, as well as their expansion rates, is recursively increased until an appropriate desingularization of the cone is build up
with linearization expressed by first ? + 1 derivatives of the singular operator
at the base point.
Along these lines, a well-defined submersion is constructed in the cone with
uniformly bounded inverse when approaching the singularity. The techniques
are restricted to curves, possibly touching by high order the singular locus of ?, but ultimately traversing it, in this way defining an isolated singularity of the
operator family given by the linearization along the curve.
The fine resolution of the cone by the manifolds represents an improvement
compared to measuring the variation of the nonlinear operator exclusively by
the overall behaviour of the determinant.
In case of finite dimensions, each half-cone is characterized by a constant topological degree that can be used to investigate a solution curve in general position with respect to secondary bifurcation.
The core of all considerations is given by some characteristic patterns, valid in
the system of undetermined coefficients that allow for detailed analysis of the
power series resulting from plugging the power series of the ansatz into the
power series of the nonlinear operator.
Open Source
(2020)
In der IT-Branche hat sich Open-Source-Software (OSS) heute durchgesetzt, führende IT-Konzerne verwenden Open-Source-Code und entwickeln ihn auch selbst. Doch auch für Unternehmen anderer Branchen bietet Open-Source-Software Potenzial. In diesem Beitrag erfahren Sie, dass Open-Source-Software nicht nur ein Schlagwort, sondern genau definiert ist,was es mit den Risiken von Open Source auf sich hat und wie man damit umgeht, welche Vorteile und Potenziale Open-Source-Software auch für Nicht-IT-Firmen bietet.
Im Projekt KWK-Flex untersuchte die Hochschule Kempten innovative Methoden und Anlagenbetriebsstrategien zur flexiblen, stromgeführten Fahrweise von Kraft-Wärme-Kopplungs-(KWK)-Anlagen in Fernwärmeverbundnetzen im Kontext steigender Anteile erneuerbarer Energien. Solche KWK-Anlagenverbunde im Leistungsbereich ab einigen MW werden in Deutschland aufgrund ihrer hohen Brennstoffnutzungsgrade und der daraus folgenden Ressourcen- und Klimafreundlichkeit von mehreren hundert Stadtwerken bzw. Fernwärmeversorgern betrieben.
Bei der Methodenentwicklung und den daraus resultierenden optimierten Anlagenbe-triebsstrategien standen neben den Zielgrößen Dynamik und Flexibilität der Strombe-reitstellung insbesondere die Ressourceneffizienz, d.h. hohe Wirkungsgrade, geringe Emissionen und hohe Wirtschaftlichkeit, sowie eine hohe Versorgungssicherheit im Fokus. Als Schwerpunkte des Forschungsvorhabens wurde Untersuchungen zur in-stationären Prozesssimulation von KWK-Kraftwerken mit dem Ziel der Erhöhung der stromseitigen Anlagendynamik mit dem Einsatz numerischer Methoden zur optimierten Anlageneinsatzplanung der Kraftwerke in KWK-Verbunden kombiniert.
Das Projekt wurde am Institut für Energie- und Antriebstechnik (IEAT) der Hochschule Kempten mit Unterstützung der beiden assoziierten gewerblichen Partner Fernwärme Ulm GmbH (FUG) und ZAK Energie GmbH (ZAK) sowie dem Fernwärmeversorgerdachverband AGFW | Der Energieeffizienzverband für Wärme, Kälte u. KWK e.V. durchgeführt.
Die verstärkte Einbindung fluktuierender erneuerbarer Energien erfordert hochflexible thermische Kraftwerke zur Netzstabilisierung und bedarfsgerechten Abdeckung der verbleibenden Netzlasten. Für einen effizienten Anlageneinsatz spielt dabei die möglichst genaue Kenntnis der zu erwartenden Fernwärmelast eine zentrale Rolle. Für die Fernwärmelastprognose können innovative Verfahren unter Verwendung moderner maschineller Lernverfahren zum Einsatz kommen, die im Folgenden vorgestellt werden.
Silica gel is a well-known desiccant. Through dispersion of silica gel in a polymer, films can be made that absorb and desorb water vapor. The water vapor absorption becomes reversible by exposing such films to a water vapor pressure below that of the water vapor pressure during absorption, or by heating the film. The intention of this study was to achieve a better understanding about the water vapor absorption, permeability (H2O, N2, O2, CO2), and mechanical properties of films with dispersed silica gel. Low-density polyethylene (PE-LD) monolayer films with a nominal silica gel concentration of 0.2, 0.4, and 0.6 g dispersed silica gel per 1 g film (PE-LD) were prepared and they absorbed up to 0.08 g water vapor per 1 g of film. The water vapor absorption as a function of time was described by using effective diffusion coefficients. The steady state (effective) water vapor permeation coefficients of the films with dispersed silica gel were a factor of 2 to 14 (8.4 to 60.2·10−12 mg·cm·(cm2·s·Pa)−1, 23 °C) higher than for pure PE-LD films (4.3·10−12 mg·cm·(cm²·s·Pa)−1, 23 °C). On the other hand, the steady state gas permeabilities for N2, O2, and CO2 were reduced to around one-third of the pure PE-LD films. An important result is that (effective) water vapor permeation coefficients calculated from results of sorption and measured by permeation experiments yielded similar values. It has been found that it is possible to describe the sorption and diffusion behavior of water by knowing the permeability coefficient and the sorption capacity of the film (Peff.≈Seff.⋅Deff.). The tensile stress changed only slightly (values between 10 and 14 N mm−2), while the tensile strain at break was reduced with higher nominal silica gel concentration from 318 length-% (pure PE-LD film) to 5 length-% (PE-LD with 0.6 g dispersed silica gel per 1 g film).
Polymers with dispersed desiccants are relevant for various packaging applications to protect packaged goods from water vapor. The intention of this study was to analyze and to describe a relevant system. Therefore, films with calcium oxide (CaO) were investigated, because such materials are hardly described in scientific literature. Monolayer films with 0.14 to 0.51 g dispersed CaO per 1 g film (PE‐LD) were prepared and they absorbed up to 0.2 g water vapor per 1 g of film. The water vapor absorption was described by effective diffusion coefficients. By the use of effective diffusion coefficients and the absorption capacity, the absorption behavior of layers with various thicknesses can be estimated. The steady state (effective) water vapor permeation coefficients of the films with dispersed CaO were a factor of 2 to 24 (8.4 to 101.5 mg cm [cm2 s Pa]–1 × 1012, at 23 °C) higher than for pure PE‐LD films (4.26 mg cm [cm2 s Pa]−1 × 1012, 23 °C). The tensile stress changed only slightly (pure PE‐LD: 9.5 N mm−2; PE‐LD with 0.14 g dispersed CaO per 1 g film: 8.1 N mm−2; PE‐LD with 0.51 g dispersed CaO per 1 g film: 10.5 N mm−2), while the tensile strain at break was reduced with higher CaO concentration from 318% (pure PE‐LD) to 10% (PE‐LD with 0.51 g dispersed CaO per 1 g film). © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47460.