Effect of spatial resolution on apparent sensitivity to initial conditions of a decaying flow as it becomes turbulent

Grids with 32(exp 3), 64(exp 3), and 128(exp 3) points are used in numerical solutions for a decaying flow. The sensitivity of initially neighboring solutions to small changes in initial conditions increases as the spatial resolution improves. A fourth-order finite-difference method is used for the solutions with 32(exp 3) and 64(exp 3) grid points, and a pseudospectral method is used for 128(exp 3) grid points. The latter solutions appear to be rather well-resolved, in spite of the formation of steep velocity gradients in the flow

Scholarly Communication in the Context of Digital Literacy: Navigation and Decision Making in a Complex Landscape

As digital technologies have come to dominate the conduct and dissemination of scholarship, seasoned and budding scholars alike may have little knowledge of what happens with the data that are gathered from their scholarly products, online profiles, and community platforms. Growing commercialization, mergers, buyouts, and venture capital investment lend credence to the idea of research results as “big data” to be mined and scholarly communication as “big business”. The scope of the issues that now govern the funding and sharing of knowledge is formidable and international. How does one even begin to understand what is needed to navigate and make decisions in such a complex environment? Not just a concern of faculty, these issues can have profound influence on student learning, academic services, and society at large. Scholarly communication is often viewed as a mechanistic and closed system; we should reframe it in a larger context and apply concepts of digital literacy and social justice

Assessing the Success of Library Published Journals

In 2015, the University of Minnesota (UMN) Libraries launched a publishing program. Following in the footsteps of earlier library publishing initiatives, the program seeks to serve campus by providing an affordable venue for publishing quality open access journals and other openly accessible formats. However, given UMN Libraries Publishing’s diverse portfolio and its non-traditional business model, assessing the program’s success required innovative thinking that did not depend on sales figures or disciplinary-specific metrics. This paper will discuss UMN Libraries Publishing’s development of journal-level goals to assess publication-level success and, in turn, assess the success of a library publishing program. The paper will present examples of journal goals, templates for editorial boards, and timelines for publishing workflows related to assessment

Atēnu Universitātes simtgades medaļa

In 1937, Athens celebrated 100th anniversary of the its main university, the University of Athens (full name: National and Kapodistrian University of Athens), and the Museum of the University of Latvia (UL) stores a commemorative medal issued to mark this occasion. It was awarded to Pēteris Ķiķauka, Professor of Classical Philology at the University of Latvia, for his participation in the anniversary celebrations, when he went on a working trip to Athens to represent Latvia at the celebrations of this institution of higher education and science.1937. gadā Atēnās tika atzīmēta pilsētas galvenās augstskolas – Atēnu Universitātes (pilnajā nosaukumā: Nacionālā un Kapodistrija Atēnu universitāte) – simtgade, un Latvijas Universitātes (LU) Muzejā glabājas šim notikumam par godu izdotā piemiņas medaļa. To par dalību simtgades svinību pasākumā saņēma LU klasiskās filoloģijas profesors Pēteris Ķiķauka, kad viņš devās komandējumā uz Atēnām, lai pārstāvētu Latviju šajās augstākās izglītības un zinātnes iestādes svinībās

Experimental and numeric analysis of uni-axially and multi-axially loaded elastomer bushings with special consideration of the influence of different load sequences

Aufgrund ihrer besonderen mechanischen Eigenschaften werden Elastomerbauteile in vielen technischen Anwendungen zur Lösung schwingungstechnischer Aufgabenstellungen eingesetzt. Gummi-Metall-Verbund-Bauteile werden nicht nur als dämpfende Aggregatelager für Maschinenteile verwendet, sie dienen auch als Verbindungselemente in Kupplungen. Die auf sie einwirkenden dynamischen Belastungen beeinflussen die Dauer ihres Einsatzes bis zu ihrem Ausfall maßgeblich. Die vorliegende Arbeit liefert neue Erkenntnisse zur Beschreibung des Bauteilzustandes dynamisch belasteter Elastomerbuchsen durch Bewertung von mithilfe des Hysterese-Messverfahrens ermittelten Kennwertverläufen und zum Einfluss unterschiedlicher Belastungsreihenfolgen auf den Schädigungsverlauf. Im Rahmen der vorgestellten experimentellen Untersuchungen werden zylindrische Elastomerbuchsen in unterschiedlichen Versuchsführungen harmonisch wechselnd axial, radial und auf Torsion belastet. Die Auswertung der einstufigen und mehrstufigen Einachsversuche erfolgt durch Bewertung der Verläufe der eigenschaftsbeschreibenden Kennwerte dynamische Steifigkeit Cdyn_n und Dämpfungsarbeit AD_n. Diese werden durch die Anwendung des Hysterese-Messver¬fahrens aus den jeweils gemessenen Belastungen und Verformungen berechnet. Aus den vorliegenden Versuchsergebnissen wird abgeleitet, dass der Bauteilzustand anhand der Dämpfungsarbeit deutlich präziser beschrieben werden kann als anhand der dynamischen Steifigkeit. Nach der Definition des Ausfallkriteriums Änderung des Wertes der normierten Dämpfungsarbeit um 20 % werden die Gebrauchsdauern sämtlicher Versuche auf dieser Basis ermittelt und diskutiert. Im Rahmen der zweiachsigen Bauteilprüfung werden Elastomerbuchsen sowohl mit überlagerter Radial- und Torsionsbelastung als auch mit überlagerter Radial- und Axialbelastung phasengleich beaufschlagt. Durch die überlagerten Belastungen werden gegenüber den Einachsversuchen mit gleichen Belastungsstufen deutlich reduzierte Gebrauchsdauern festgestellt. Der Einfluss unterschiedlicher Belastungsreihenfolgen auf den Schädigungsverlauf wird im Rahmen der vorliegenden Arbeit erstmals an belastungsgeführten Axialversuchen untersucht und nachgewiesen. Dazu werden unterschiedliche Versuchsvarianten definiert, die sich durch die Reihenfolge der aufgebrachten Belastungsstufen, durch Sonderereignisse mit mehrfach überhöhten Belastungsamplituden und durch wiederkehrende Belastungspausen unterscheiden. Für alle zuvor experimentell untersuchten Belastungsfälle werden die in den belasteten Elastomerbuchsen auftretenden Deformationen und Beanspruchungen mithilfe der Finite-Elemente-Methode berechnet. Die Vergleiche mit Schadensbildern von zuvor experimentell belasteten Buchsen zeigen für alle Belastungsfälle, dass die innerhalb der Elastomerspuren mithilfe der FEM lokalisierten Bereiche höchster Spannungen und Dehnungen den Bereichen entsprechen, von welchen im Experiment eine erkennbare Rissbildung ausgeht. Die Berechnungsergebnisse werden durch die Vergleiche mit den experimentell ermittelten Verschiebungen und Schadensbildern qualitativ bestätigt und abgesichert. Die in dieser Arbeit durch experimentelle Untersuchungen gewonnenen Erkenntnisse bezüglich der vielfältigen Kennwertverläufe sowie der ebenfalls durch Versuche belegte Einfluss der Belastungsreihenfolge auf den Schadensverlauf verlangen nach einer nicht linearen Schadensakkumulationrechnung. Es wird untersucht, welche der mithilfe der FEM berechneten Beanspruchungsgrößen in diesem Rahmen einzusetzen ist.Due to their special mechanical properties, elastomeric parts are used in many technical applications to solve vibration control problems. Furthermore, rubber-metal component parts are used not only as damping mounts for machine parts, they also serve as transmission elements in couplings. The dynamic loads acting on them affect the life cycle period until their failure significantly. The present work provides new insights into the description of the condition of dynamically loaded elastomer bushings by using the evaluation of characteristic values found on the basis of the hysteresis measuring method. The study also shows the influence of different load sequences on the damage process. In different tests, harmonically alternating radial, axial and torsional loads are applied on cylindrical elastomer bushings. These one-stage and multi-stage uniaxial tests are evaluated by describing the development of the characteristic values dynamic stiffness Cdyn_n and damping work AD_n. These are obtained by using the hysteresis measuring method on the measured loads and deformations. The presented experimental results lead to the conclusion that the component state can be described much more precisely on the basis of the damping work than on the basis of the dynamic stiffness. After definition of the failure criterion ‘change in the value of the standardized damping work by 20 %’, the life cycle periods of all the tests are calculated and discussed on this basis. Using experimental setups specially developed for biaxial tests, elastomer bushings are subjected to different loads both with superimposed radial and torsional load and with superimposed radial and axial load. The simultaneous loads are in both cases in phase. As a result of the superimposed loads, significantly reduced life cycle periods are observed compared to the uniaxial tests with the same load levels. The influence of different load sequences on the damage process and thus on the characteristic curves is examined and proven in this study for the first time on load controlled axial component tests. For this purpose, different test sequences are defined. They differ in the order of the applied load levels, regularly occurring load peaks and hourly recurring load breaks. For all examined loading cases, the deformations and strains occurring in the loaded elastomer bushings are calculated using the finite element method. Comparisons with damage patterns of experimentally loaded bushings show for all loading cases that the areas of maximum stress and strain localized within the elastomer using FEM correspond to the areas from which a recognizable cracking starts during the experiment. The calculation results are qualitatively confirmed by the comparison with the experimentally detected displacements and damage patterns. The conclusions found in this study concerning the varied characteristic curves and the influence of the load sequences on the damage process demand a non-linear cumulative damage calculation. It is discussed which of the FEM-calculated values should be used in this context

Studentu karcera laika kapsulas

Raksts veltīts unikālam atklājumam Latvijas Universitātes vēsturiskajā Studentu karcerī, kas glabājies kopš 19./20. gs. mijas. Tiek analizētas 3 papirosu paciņas un 1 sērkociņu kastīte no Krievijas impērijas laika, noskaidrojot tā izcelsmi, pielietojumu un zinātnisko novitāti. Atrastie priekšmeti liecina, ka Studentu karcerī ieslēgtie studenti spēja apiet Rīgas Politehnikuma Studentu disciplinēšanas regulā noteikto sodu par smēķēšanu. Priekšmeti arī ir Latvijas industriālās vēstures atstāts mantojums, kas liecina par Baltijas reģiona nozīmi Krievijas impērijas rūpniecības attīstībā.he article is dedicated to a unique discovery in the Historic Student solitary confinement cell of the University of Latvia, preserved since the turn of the 19th/20th centuries. An analysis of 3 papiros packets and 1 matchbox from the time of the Russian Empire has been made, clarifying its origin, use, and scientific novelty. The found objects show that the students locked in the Student solitary confinement cell could circumvent the punishment for smoking stipulated in the Student Disciplinary Regulation of the Riga Polytechnikum. The objects are also a legacy of Latvia's industrial history, testifying to the importance of the Baltic region in the industrial development of the Russian Empire

Arheologs Ēvalds Mugurēvičs un Latvijas Universitāte

Raksts veltīts izcilam latviešu arheologam, emeritētajam profesoram Ēvaldam Mugurēvičam, kuram ir lieli nopelni Latvijas arheoloģijā. Lai gan E. Mugurēvičs par sevi ir uzrakstījis detalizētu autobiogrāfiju, rakstā tiek ieskicēta Ē. Mugurēviča saistība ar Latvijas Universitāti un viņa spēja pielāgoties pastiprinātai zinātnes ideoloģizācijai PSRS okupācijas laikā.The article is dedicated to the outstanding Latvian archaeologist, Professor Emeritus Ēvalds Mugurēvičs, who has made great contributions to Latvian archaeology. Although Mugurēvičs has written a detailed autobiography about himself, the article outlines the career of E. Mugurēvičs' association with the University of Latvia and his ability to adapt to the increased ideologisation of science during the occupation of the USSR

The Proteus Navier-Stokes code

An effort is currently underway at NASA Lewis to develop two- and three-dimensional Navier-Stokes codes, called Proteus, for aerospace propulsion applications. The emphasis in the development of Proteus is not algorithm development or research on numerical methods, but rather the development of the code itself. The objective is to develop codes that are user-oriented, easily-modified, and well-documented. Well-proven, state-of-the-art solution algorithms are being used. Code readability, documentation (both internal and external), and validation are being emphasized. This paper is a status report on the Proteus development effort. The analysis and solution procedure are described briefly, and the various features in the code are summarized. The results from some of the validation cases that have been run are presented for both the two- and three-dimensional codes

Research Sprints: Elevating Faculty & Librarian Collaboration

Poster presented at the Academic and Research Library Division (ARLD) meeting at the Minnesota Library Association (MLA) 2019 annual conference