Development of underwater housings for the deep sea made of ultra-high performance concrete (UHPC) and long-term testing at the Arctic Sea
The aim of this research is the design and analysis of underwater housings made of ultra-high performance concrete (UHPC) within the Helmholtz Alliance “ROBEX” (robotic exploration of extreme environments) [1]. Due to the extremely corrosive maritime environment, mainly expensive materials such as titanium, ceramics, special stainless steel and aluminum are used so far for the construction of temporary and permanent research stations to guarantee long-term deployment. In this project the suitability of high-strength concrete with compressive strength up to 210 MPa for underwater pressure housings and constructions is examined to provide a low cost and durable alternative especially for large housings in future.
UHPC‐Druckgehäuse für Anwendungen in der Tiefsee
Der vorliegende Artikel beschreibt die Entwicklung von Druckgehäusen aus ultrahochfestem Beton für Tiefseeanwendungen im Rahmen der Helmholtz Allianz ROBEX. Neben grundlegenden Untersuchungen zum Materialverhalten von UHPC, wie zeitabhängige oder mehraxiale Druckfestigkeit und E‐Modul, Bruchdehnung, Größeneffekt, Einfluss von Wärmebehandlung und Salzwasserlagerung oder Porositätsmessungen, wurden auch diverse Studien zu Konstruktionsgrundsätzen für wiederverschließbare Druckgehäuse durchgeführt. Die Experimente wurden begleitend numerisch simuliert und das nichtlineare Materialmodell multiPlas in ANSYS anhand der gewonnenen experimentellen Daten kalibriert. Neben einer Vielzahl an Druck‐ und Implosionsversuchen von Betongehäusen im Labor wurden zwei je einjährige Feldstudien in der Arktis in 2500 m Tiefe erfolgreich absolviert, um die Dauerhaftigkeit der Betongehäuse und den Einfluss der maritimen Umgebung auf UHPC zu untersuchen. Dabei konnten Ergebnisse zum Kriechen von UHPC unter hoher Dauerlast, zur Diffusionsdichtheit und zum Einfluss der Calcit‐Kompensationstiefe gewonnen werden. Die gewonnenen Erkenntnisse wurden in Bemessungsempfehlungen zusammengefasst.
Expansion without equity: An analysis of current policy on access to higher education in Brazil
Access to higher education in Brazil is to a large extent restricted to the higher socio-economic groups. Public universities have limited places and entry is determined by highly competitive exams, thereby excluding those who have not had a high quality secondary education or attended an expensive preparatory course. There has been considerable growth in the private sector to absorb the excess demand, but the majority of Brazilians cannot afford the fees. This paper develops a concept of equity in higher education in which, firstly, there should be sufficient places in the system as a whole and, secondly, all people should have a fair opportunity of attending the university of their choice regardless of socio-economic background. Recent efforts to expand access are analysed, including incentives for the growth of private universities, student loans and the new Prouni initiative, in which private institutions provide free places to low-income students in return for tax exemptions. While these initiatives have the potential to increase the total number of places, they will not lead to an equitable expansion, as disadvantaged students will still be confined to courses of lower quality or with lower subsequent value on the employment market. Initiatives aimed at the public sector such as the introduction of quotas and changes to entry examinations are also discussed. Finally, some implications for future policy development are outlined.