485 research outputs found

    Human-triggered earthquakes and their impacts on human security

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    A comprehensive understanding of earthquake risks in urbanized regions requires an accurate assessment of both urban vulnerabilities and earthquake hazards. Socioeconomic risks associated with human-triggered earthquakes are often misconstrued and receive little scientific, legal, and public attention. However, more than 200 damaging earthquakes, associated with industrialization and urbanization, were documented since the 20th century. This type of geohazard has impacts on human security on a regional and national level. For example, the 1989 Newcastle earthquake caused 13 deaths and US$3.5 billion damage (in 1989). The monetary loss was equivalent to 3.4 percent of Australia’s national income (GDI) or 80 percent of Australia’s GDI per capita growth of the same year. This article provides an overview of global statistics of human-triggered earthquakes. It describes how geomechanical pollution due to large-scale geoengineering activities can advance the clock of earthquakes or trigger new seismic events. Lastly, defense-oriented strategies and tactics are described, including risk mitigation measures such as urban planning adaptations and seismic hazard mapping

    Long-term impacts of tropical storms and earthquakes on human population growth in Haiti and the Dominican Republic

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    Since the 18th century, Haiti and the Dominican Republic have experienced similar natural forces, including earthquakes and tropical storms. These countries are two of the most prone of all Latin American and Caribbean countries to natural hazards events, while Haiti seems to be more vulnerable to natural forces. This article discusses to what extent geohazards have shaped both nation's demographic developments. The data show that neither atmospheric nor seismic forces that directly hit the territory of Haiti have significantly affected the country's population growth rates and spatial population densities. Conversely, since the 1950s more people were exposed to atmospheric hazards, in particular, in regions which historically experienced higher storm frequencies

    Von Ägina nach Dresden - die GipsabgĂŒsse der Giebelfiguren des Aphaiatempels im „Königlich SĂ€chsischen Mengs’ischen Museum der GypsabgĂŒsse“

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    Im 1843 publizierten Verzeichnis des Königlich SĂ€chsischen Mengs’ischen Museums, wie die Dresdner Gipsabgusssammlung, die auf die 1782 aus dem Nachlass Anton Raphael Mengs‘ in Rom angekauften AbgĂŒsse zurĂŒckgeht, in jener Zeit genannt wurde, tauchen zum ersten Mal AbgĂŒsse der Giebelfiguren des Aphaiatempels aus Ägina auf, der so genannten Ägineten. Bisher ungeklĂ€rt blieb die Frage nach dem Zeitpunkt ihrer Erwerbung wie nach ihrer Provenienz

    Von Ägina nach Dresden - die GipsabgĂŒsse der Giebelfiguren des Aphaiatempels im „Königlich SĂ€chsischen Mengs’ischen Museum der GypsabgĂŒsse“

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    Im 1843 publizierten Verzeichnis des Königlich SĂ€chsischen Mengs’ischen Museums, wie die Dresdner Gipsabgusssammlung, die auf die 1782 aus dem Nachlass Anton Raphael Mengs‘ in Rom angekauften AbgĂŒsse zurĂŒckgeht, in jener Zeit genannt wurde, tauchen zum ersten Mal AbgĂŒsse der Giebelfiguren des Aphaiatempels aus Ägina auf, der so genannten Ägineten. Bisher ungeklĂ€rt blieb die Frage nach dem Zeitpunkt ihrer Erwerbung wie nach ihrer Provenienz

    Endbericht: Innovativer Mittelstand 2015 - Herausforderungen, Trends und Handlungsempfehlungen fĂŒr Wirtschaft und Politik

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    Der Mittelstand gilt als ein wesentliches Element des Erfolgs der deutschen Wirtschaft. In ihm vereinigen sich kleine und mittelstĂ€ndische Unternehmen, die zumeist inhabergefĂŒhrt hohe InnovativitĂ€t mit einer internationalen Marktperspektive und einer großen sozialen Verantwortung kombinieren. Ob die erfolgreichen mittelstĂ€ndischen Unternehmen von gestern und heute mit ihren Nischenstrategien auch die „Champions“ von morgen sein werden, bildete eine Kernfragestellung dieser Studie. Es mehren sich dabei die Anzeichen, dass dieses Erfolgsmodell in eine Krise gerĂ€t, sofern in bestimmten Bereichen nicht gegengesteuert wird: Die unternehmerischen Entscheidungen erfordern angesichts der globalen Herausforderungen einen Weitblick, der die wichtigsten Trends erkennt und zugleich auf der betrieblichen Ebene Antworten darauf formuliert. Angesichts einer stĂ€ndig steigenden Vernetzung der Wirtschaft in global agierenden Wertschöpfungsnetzwerken, einer zunehmenden Digitalisierung von Produkten und Prozessen sowie weiteren Herausforderungen, wie dem demographischen Wandel, kommen etablierte Vorgehensweisen dabei schnell an ihre Grenzen. Hinzu treten disruptive Technologien, die etablierte GeschĂ€ftsmodelle radikal hinterfragen. Gleichzeitig lĂ€sst sich ein Nachlassen des Innovationsbeitrags des Mittelstandes an der gesamtwirtschaftlichen Innovationsleistung beobachten. Die Prognos AG und das Zentrum fĂŒr EuropĂ€ische Wirtschaftsforschung (ZEW), Mannheim, verbinden in dieser Studie im Auftrag des Bundesministeriums fĂŒr Wirtschaft und Energie (BMWi) eine Status-Quo-Analyse mit einer Vorausschau auf die kommenden zehn Jahre. Folglich wurde neben den Instrumenten der Unternehmensbefragung, der international vergleichenden Auswertung von Innovationsindikatoren, ExpertengesprĂ€chen und Fallstudien auch das Instrument der Delphi-Befragung eingesetzt. 486 Experten aus Wirtschaft, Wissenschaft und Politik wurden in einem zweistufigen Verfahren zu ihren EinschĂ€tzungen und Bewertungen zentraler Zukunftstrends angesprochen und um ihre EinschĂ€tzung gebeten. Bewertet wurden insgesamt 45 Thesen hinsichtlich ihrer Wahrscheinlichkeit und des Zeitpunkts ihres Eintretens. Der AntwortrĂŒcklauf belief sich auf ca. 22 %. In einer Gesamtbewertung der Delphi-Ergebnisse lĂ€sst sich feststellen, dass die Befragten davon ausgehen, dass die mittelstĂ€ndischen Unternehmen die Trends teilweise positiv fĂŒr die Verstetigung ihres Erfolgs zu nutzen wissen. [...]Studie im Auftrag des Bundesministeriums fĂŒr Wirtschaft und Energi

    The Basic Law at 60 - Introduction to the Special Issue

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    For Germany 2009 was a year of constitutional anniversaries: the first democratic constitution (Paulskirchenverfassung of 1849) was promulgated 160 years ago; the 1919 Weimar Constitution would have turned 90; and finally, the country celebrated 60 years of the Basic Law, which was proclaimed and signed in Bonn on 23 May 1949. Despite its birth in the midst of economic and political turmoil and widespread disillusion with politics, the Basic Law has come to be regarded as a success story. As is well known, it was never meant to last - the very term Grundgesetz (basic law) indicated that it was intended to serve as a temporary constitutional framework until the enactment of a new constitution for the whole of Germany. Yet the Basic Law outgrew its provisional character. Today, not only the political establishment is united in praising the Grundgesetz. The scholarly assessment also has been mostly positive. The constitutional bargain struck in 1949 has been able to achieve what no previous German constitution had managed. The right and the left of the German political spectrum fashioned an enduring compromise that combined democracy, federalism and the welfare state. It is part of the story that the old anti-liberal and nationalist elite had been thoroughly delegitimized by loosing the war. Also, the Allies gave the effort an additional nudge. The progressive changes could then be implemented quite effectively by relying on the juristic culture of the Rechtsstat that dates back to the bureaucratic legacy of, among others, the Prussian state

    Influence of the atmosphere and temperature on the properties of the oxygen-affine bonding system titanium-diamond during sintering

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    Grinding tools can be manufactured from metal, vitrified, and resin bond materials. In combination with superabrasives like diamond grains, metal-bonded tools are used in a wide range of applications. The main advantages of metal over vitrified and resin bonds are high grain retention forces and high thermal conductivity. This paper investigates the influence of the atmosphere and manufacturing parameters such as sintering temperature on the properties of titanium-bonded grinding layers. Titanium is an active bond material, which can increase the retention of diamond grains in metal-bonded grinding layers. This can lead to higher bond stress and, consequently, decreased wear of grinding tools in use when compared to other commonly used bond materials like bronze. The reason for this is the adhesive bond between titanium and diamond due to the formation of carbides in the interface, whereas bronze can only form a mechanical cohesion with diamond grains. However, when using oxygen-affine metals such as titanium, oxidizing effects could limit the strength of the bond due to insufficient adhesion between Ti-powder particles and the prevention of carbide formation. The purpose of this paper is to show the influence of the sintering atmosphere and temperature on the properties of titanium-bonded diamond grinding layers using the mechanical and thermal characterization of specimens. A higher vacuum (Δpatm = − 75 mbar) reduces the oxidation of titanium particles during sintering, which leads to higher critical bond stress (+ 38% @ Ts = 900 °C) and higher thermal conductivity (+ 3.4% @Ts = 1000 °C, Ta = 25 °C). X-ray diffraction measurements could show the formation of carbides in the cross-section of specimens, which also has a positive effect on the critical bond stress due to an adhesive bond between titanium and diamond

    Modal analysis of high-fidelity simulations in turbomachinery

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    We revisit recently published high-fidelity implicit large eddy simulation datasets obtained with a high-order discontinuous Galerkin spectral element method and analyse them using Proper Orthogonal Decomposition (POD) as well as Spectral Proper Orthogonal Decomposition (SPOD). The first configuration is the MTU T161 low-pressure turbine cascade with resolved end wall boundary layers in a clean version and one with incoming turbulent wakes. We focus on the behaviour of the laminar separation bubble and the secondary flow system and how these phenomena are affected by incoming wakes. The second configuration is a transonic compressor cascade in which we analyse the unsteady behaviour of the shock wave boundary layer interaction. Throughout the paper, we try to discuss not only the flow physics but also insights into how the modal decomposition techniques can help facilitate understanding and where their limitations are.Comment: Submitted to Cambridge Unsteady Flow Symposium 202

    Development of an Aluminum-Based Hybrid Billet Material for the Process-Integrated Foaming of Hollow Co-Extrusions

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    Metal foams are attractive for lightweight construction in the automotive sector since they provide high-energy absorption and good damping properties, which is crucial, e.g., for crash structures. Currently, however, foams are produced separately and then pasted into the components. Consequently, the overall mechanical properties depend significantly on the quality of the adhesive bond between the foam and the structural component. A new process route for the manufacture of hybrid foamed hollow aluminum profiles is proposed. In this approach, a foamable precursor material is directly integrated into the extrusion process of the hollow structural profile. To this end, special low-melting alloys were developed in this study to enable foaming inside the aluminum profile. The melting intervals of these alloys were examined using differential scanning calorimetry. One of the promising AlZnSi alloys was atomized, mixed with a foaming agent and then compacted into semi-finished products for subsequent co-extrusion. The foaming behavior, which was investigated by means of X-ray microscopy, is shown to depend primarily on the mass fraction of the foaming agent as well as the heat treatment parameters. The results demonstrate that both the melting interval and the foaming behavior of AlZn22Si6 make this particular alloy a suitable candidate for the desired process chain

    Corrosion Behavior of an Additively Manufactured Functionally Graded Material

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    Dissimilar metal welds (DMW) combine the high strength and cost benefits of ferritic stainless steels with the high corrosion resistance of austenitic steels, and are thus commonly used in different types of power plants. However, due to the abrupt change in properties, these joints are susceptible to premature failure. Work pieces with a smooth transition in composition and/or properties are referred to as "functionally graded materials" (FGM). When used as transition joints, FGM can enhance the lifetime of certain components. In the present study, the FGM were manufactured by using wire arc additive manufacturing employing cold-wire gas metal arc welding. Since the corrosion resistance of such FGM are still unknown, the corrosion properties of the FGM work piece were compared to those of a DMW work piece by means of electrochemical analysis using potentiodynamic polarization and a salt spray test. The FGM showed a 24 % lower average corrosion rate compared to the reference piece and no signs of pitting or galvanic corrosion. This shows the potential of FGM and further research should be carried out
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