Human-triggered earthquakes and their impacts on human security

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

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 Gipsabgüsse der Giebelfiguren des Aphaiatempels im „Königlich Sächsischen Mengs’ischen Museum der Gypsabgüsse“

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

Von Ägina nach Dresden - die Gipsabgüsse der Giebelfiguren des Aphaiatempels im „Königlich Sächsischen Mengs’ischen Museum der Gypsabgüsse“

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

The Basic Law at 60 - Introduction to the Special Issue

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

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

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

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

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

Mechanical properties of co-extruded aluminium-steel compounds

Within the scope of the Collaborative Research Centre (CRC) 1153 novel process chains for the production of hybrid solid components by Tailored Forming are developed at the Leibniz Universität Hannover. The combination of e. g. aluminium with steel allows to produce hybrid compounds with wear-resistant functional surfaces and reduced weight. In these process chains, joining takes place as the first step to produce hybrid semi-finished products by friction welding, cladding, ultrasonic assisted laser welding or co-extrusion, which are subsequently subjected to various forming processes such as forging or impact extrusion. The coaxially joined hybrid semifinished components investigated in this work were produced by means of the lateral angular co-extrusion (LACE) process using the aluminium alloy EN AW-6082 and the case-hardening steel 20MnCr5. These semi-finished products shall be suited to produce hybrid bearing bushings by die forging in a subsequent process step. Initial investigations for the determination of the process parameters and the appropriate tool geometry were made using a steel rod. In future investigations, a steel tube will replace the steel rod in order to produce hybrid semi-finished products, which can be fully integrated into the process chain. The mechanical properties of the profile were determined at different positions along its length. For this purpose, the quality of the joining zone between aluminium and steel as a function of the profile position was examined by means of push-out tests. Moreover, the mechanical properties of the aluminium component's longitudinal weld seam were determined by micro-tensile-tests. © 2017 Trans Tech Publications, Switzerland

Development of a laser powder bed fusion process tailored for the additive manufacturing of high-quality components made of the commercial magnesium alloy WE43

Additive manufacturing (AM) has become increasingly important over the last decade and the quality of the products generated with AM technology has strongly improved. The most common metals that are processed by AM techniques are steel, titanium (Ti) or aluminum (Al) alloys. However, the proportion of magnesium (Mg) in AM is still negligible, possibly due to the poor processability of Mg in comparison to other metals. Mg parts are usually produced by various casting processes and the experiences in additive manufacturing of Mg are still limited. To address this issue, a parameter screening was conducted in the present study with experiments designed to find the most influential process parameters. In a second step, these parameters were optimized in order to fabricate parts with the highest relative density. This experiment led to processing parameters with which specimens with relative densities above 99.9% could be created. These highdensity specimens were then utilized in the fabrication of test pieces with several different geometries, in order to compare the material properties resulting from both the casting process and the powder bed fusion (PBF-LB) process. In this comparison, the compositions of the occurring phases and the alloys’ microstructures as well as the mechanical properties were investigated. Typically, the microstructure of metal parts, produced by PBF-LB, consisted of much finer grains compared to as-cast parts. Consequently, the strength of Mg parts generated by PBF-LB could be further increased. © 2021 by the authors. Licensee MDPI, Basel, Switzerland