Offenburg University of Applied Sciences
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Obituary, in memoriam of Jürgen Zierep (1929-2021, Founding Editor of ACTA MECHANICA), accompanied by the previously unpublished note: "Mein Weg zu neuen naturwissenschaftlichen Erkenntnissen" by Jürgen Zierep
No full textJürgen Zierep passed away on July 29, 2021, at the age of 92. To him, science and education was not only a profession, but an affair of the heart. His impressive contributions in fluid mechanics comprise about 200 scientific publications in the fields of gas dynamics, similarity laws, flow instabilities, flows with energy transfer, and non-Newtonian fluids. In addition, he wrote eleven textbooks with great dedication. Those books by the “scientist who loves to teach” are nowadays available in different languages and regularly appear in new editions
Coupling Lithium Plating with SEI Formation in a Pseudo-3D Model: A Comprehensive Approach to Describe Aging in Lithium-Ion Cells
Get PDFThe lifetime of a battery is affected by various aging processes happening at the electrode scale and causing capacity and power fade over time. Two of the most critical mechanisms are the deposition of metallic lithium (plating) and the loss of lithium inventory to the solid electrolyte interphase (SEI). These side reactions compete with reversible lithium intercalation at the graphite anode. Here we present a comprehensive physicochemical pseudo-3D aging model for a lithium-ion battery cell, which includes electrochemical reactions for SEI formation on graphite anode, lithium plating, and SEI formation on plated lithium. The thermodynamics of the aging reactions are modeled depending on temperature and ion concentration, and the reactions kinetics are described with an Arrhenius-type rate law. The model includes also the positive feedback of plating on SEI growth, with the presence of plated lithium leading to a higher SEI formation rate compared to the values obtained in its absence at the same operating conditions. The model is thus able to describe cell aging over a wide range of temperatures and C-rates. In particular, it allows to quantify capacity loss due to cycling (here in % per year) as function of operating conditions. This allows the visualization of aging colormaps as function of both temperature and C-rate and the identification of critical operation conditions, a fundamental step for a comprehensive understanding of batteries performance and behavior. For example, the model predicts that at the harshest conditions ( 3 C), aging is reduced compared to most critical conditions (around 0–5 °C) because the cell cannot be fully charged
Measuring and Modeling Cue Dependent Spatial Release from Masking in the Presence of Typical Delays in the Treatment of Hearing Loss
Get PDFIn asymmetric treatment of hearing loss, processing latencies of the modalities typically differ. This often alters the reference interaural time difference (ITD) (i.e., the ITD at 0° azimuth) by several milliseconds. Such changes in reference ITD have shown to influence sound source localization in bimodal listeners provided with a hearing aid (HA) in one and a cochlear implant (CI) in the contralateral ear. In this study, the effect of changes in reference ITD on speech understanding, especially spatial release from masking (SRM) in normal-hearing subjects was explored. Speech reception thresholds (SRT) were measured in ten normal-hearing subjects for reference ITDs of 0, 1.75, 3.5, 5.25 and 7 ms with spatially collocated (S0N0) and spatially separated (S0N90) sound sources. Further, the cues for separation of target and masker were manipulated to measure the effect of a reference ITD on unmasking by A) ITDs and interaural level differences (ILDs), B) ITDs only and C) ILDs only. A blind equalization-cancellation (EC) model was applied to simulate all measured conditions. SRM decreased significantly in conditions A) and B) when the reference ITD was increased: In condition A) from 8.8 dB SNR on average at 0 ms reference ITD to 4.6 dB at 7 ms, in condition B) from 5.5 dB to 1.1 dB. In condition C) no significant effect was found. These results were accurately predicted by the applied EC-model. The outcomes show that interaural processing latency differences should be considered in asymmetric treatment of hearing loss
Improving Security in Server-Side JavaScript Web Applications
No full textOn a regular basis, we hear of well-known online services that have been abused or compromised as a result of data theft. Because insecure applications jeopardize users' privacy as well as the reputation of corporations and organizations, they must be effectively secured from the outset of the development process. The limited expertise and experience of involved parties, such as web developers, is frequently cited as a cause of risky programs. Consequently, they rarely have a full picture of the security-related decisions that must be made, nor do they understand how these decisions affect implementation accurately.
The selection of tools and procedures that can best assist a certain situation in order to protect an application against vulnerabilities is a critical decision. Regardless of the level of security that results from adhering to security standards, these factors inadvertently result in web applications that are insufficiently secured. JavaScript is a language that is heavily relied on as a mainstream programming language for web applications with several new JavaScript frameworks being released every year.
JavaScript is used on both the server-side in web applications development and the client-side in web browsers as well.
However, JavaScript web programming is based on a programming style in which the application developer can, and frequently must, automatically integrate various bits of code from third parties. This potent combination has resulted in a situation today where security issues are frequently exploited. These vulnerabilities can compromise an entire server if left unchecked. Even though there are numerous ad hoc security solutions for web browsers, client-side attacks are also popular. The issue is significantly worse on the server side because the security technologies available for server-side JavaScript application frameworks are nearly non-existent.
Consequently, this thesis focuses on the server-side aspect of JavaScript; the development and evaluation of robust server-side security technologies for JavaScript web applications. There is a clear need for robust security technologies and security best practices in server-side JavaScript that allow fine-grained security.
However, more than ever, there is this requirement of reducing the associated risks without hindering the web application in its functionality.
This is the problem that will be tackled in this thesis: the development of secure security practices and robust security technologies for JavaScript web applications, specifically, on the server-side, that offer adequate security guarantees without putting too many constraints on their functionality
Krypto-Hype
No full textIn den letzten Jahren entstand ein regelrechter Hype um das Thema Kryptowährungen und sie sind in Gesellschaft, Politik und Wirtschaft kaum noch wegzudenken. Trotz der hohen Volatilität und des Risikos für Investoren werden Kryptowährungen teilweise auch als eine Alternative für herkömmliche Währungen angesehen. Daher stellt sich die Frage, ob die Einstellung zu Kryptowährungen und auch das Investitionsverhalten auf einer sorgfältigen Auseinandersetzung von Argumenten basiert. Dafür wurde die Forschungsfrage: „Basieren Kaufverhalten und Einstellung zu Kryptowährungen eher auf der intensiven Auseinandersetzung mit tatsächlichen Argumenten oder auf oberflächlichen Reizen?“ aufgestellt. Zur Untersuchung dieser wurde eine Umfrage mit 283 Teilnehmenden durchge-führt. Auf Basis theoretischer Überlegungen zur Einstellungsforschung durch das Elabora-tion-Likelihood-Model wurde ein Fragebogen entworfen, der den Einfluss der Elaboration auf die Einstellung und das Kaufverhalten empirisch messbar machen sollte. Durch eine Kausalanalyse mittels Strukturgleichungsmodell konnte ein teilweise signifikanter Einfluss von elaborationsbestimmenden Größen auf Einstellung und Kaufverhalten festgestellt wer-den. Eine Überprüfung der Gütekriterien des Fragebogens mittels explorativer und konfir-matorischer Faktoranalyse ergab in Hinsicht auf Reliabilität und Validität jedoch keine zu-friedenstellenden Ergebnisse. Die Ergebnisse des Kausalmodells sollten deswegen mit Vorsicht betrachtet werden. In weiterführenden Forschungen könnte die Struktur der durch den Fragebogen erhobenen Konstrukte für Elaboration und Einstellung überarbeitet werden, um eine bessere Reliabilität und Validität zu erreichen und somit genauere Aussagen über die eigentlichen Beziehungen der Konstrukte treffen zu können
Direkter Vergleich einer strohbasierten Pflanzenkohle mit Pflanzenkohlen aus holziger Biomasse in einem Weißkohl-Gewächshausversuch
No full textMicronization of biochar (BC) may ease its application in agriculture. For example, fine biochar powders can be applied as suspensions via drip-irrigation systems or can be used to produce grnulated fertilizers. However, micronization may effect important physical biochar properties like the water holding capacity (WHC) or the porosity
Fusion 360 – kurz und bündig
No full textDieses Lehrbuch ermöglicht dem Anfänger in der 3D-Modellierung einen schnellen Einstieg in die Arbeit mit dem cloudbasierten CAD-System Autodesk® Fusion 360TM. Der Schwerpunkt liegt dabei auf den grundlegenden Funktionen zur Modellierung von Einzelteilen und dem Zusammenbau von Produkten, sowie in der Erstellung von einfachen technischen Zeichnungen. Dabei werden bei jedem Schritt die besonderen Anforderungen an eine 3D-Druck-gerechte Gestaltung erläutert und umgesetzt. Somit ist das Ergebnis dieser „Schritt für Schritt“-Anleitung die vollständige Modellierung eines Miniatur-Automobils, das am 3D-Drucker in ein reales Modell umgesetzt werden kann. Das didaktische Konzept ist so ausgelegt, dass alle Schritte für ein Selbststudium geeignet sind.
In der vorliegenden Auflage wurde die Konstruktionsmethodik überarbeitet und einige Kapitel wurden ergänzt, beispielweise um das Erstellen von Teams
MEO - Modellexperimente in der operativen Energiesystemanalyse
No full textDort, wo Modelle der operativen Energiesystemanalyse untereinander Überschneidungen aufweisen, stellt sich zunächst die Frage, ob sie bei gleichgearteten Fragestellungen auch die gleichen Antworten liefern. Dies zu beantworten war erstes Ziel des hier beschriebenen Vorhabens. Das zweite Ziel war, im Falle von Differenzen zu ermitteln, worin diese begründet liegen. Es waren nicht nur die Modelle selbst, sondern auch das methodische Vorgehen zur Modellerstellung und Simulation in Betracht zu ziehen. Die darauf aufbauende Identifikation von individuellen Optimierungspotenzialen war das dritte Ziel. Da die operative Energiesystemanalyse noch ein recht junger Forschungsbereich ist, existiert darüber hinaus Klärungsbedarf, welches Modell sich für welche Untersuchungen besonders eignet und welches methodische Vorgehen sich empfiehlt. Die Beantwortung dieser Fragen stellte das vierte Ziel des Vorhabens dar
The Sweaty 2022 RoboCup Humanoid Extended Abstract
No full textSweaty has already participated several times in RoboCup soccer competitions (Adult Size). Now the work is focused on stabilizing the gait. Moreover, we would like to overcome the constraints of a ZMP-algorithm that has a horizontal footplate as precondition for the simplification of the equations. In addition we would like to switch between impedance and position control with a fuzzy-like algorithm that might help to minimize jerks when Sweaty’s feet touch the ground
