Due to the creation of a significant temperature gradient, electrical discharge machining (EDM) causes localized, high thermal stress in a tiny heat-affected zone. This thermally developed stress ...leads to fatigue life and strength decrement, micro-cracks and probably catastrophic failure. On AISI A2 steel, a mathematical model based on finite-element analysis was constructed to estimate the temperature field and associated thermal stresses. In this present research work, the heat-flux distribution in a single spark during EDM is considered to be Gaussian distributed. The model first calculates the temperature distribution, and then uses this temperature field to determine the thermal stresses. It was observed that the stresses surpass the workpiece material’s yield strength near the center of the spark and this gradually weakens as the distance from the center increases.
The influence of chemical composition and heat treatment on the mechanical properties and formability of the selected commercial aluminium alloy EN AW 5454 was investigated. The main properties of ...alloy 5454 from the AA 5xxx series are very good corrosion resistant and has good formability. From the cast slab a 50 mm thick slice was taken in the width cross section in the slab centre. One half of the slice was homogenised for 10 hours at a temperature of 530 °C. The cast and homogenised samples were investigated using light and scanning electron microscopy. For the study of the influence of the heat treatment, samples in the as-cast state were annealed in the laboratory furnace at a temperature of 530 °C for 4, 6, 8, 10 and 12 hours. To study the influence of chemical composition, four different samples were prepared: the first without additions, the second with an addition of 1 wt% Mn, the third with 3 wt% Mg and the fourth with an addition of both elements, Mn and Mg. The XRF analyses confirmed the desired chemical composition of all four produced alloys. Half of each alloy’s sample was homogenised at the same temperature and time as the base alloy in the as-cast state. The hot deformation behaviour of the different alloys was investigated using cylindrical hot compression tests performed on a Gleeble 1500D thermo-mechanical simulator. By comparing flow curves a high influence of the thermo-mechanical parameters on the alloy formability can be seen. The alloy has good workability and with the addition of Mn and Mg, the stress values are higher than those of the base alloy.
This book explores examples of the circular economy in action. Unlike other books that provide narrow perceptions of wide-ranging and highly interconnected paradigms, such as supply chains, ...recycling, businesses models and waste management, this book provides a comprehensive overview of the circular economy from various perspectives. Its unique insights into the approaches, methods and tools that enable people to make the transformation to a circular economy show how recent research, trends and attitudes have moved beyond the "call to arms" approach to a level of maturity that requires sound scientific thinking.
Treatment of the sludge from water-purification plants is becoming more and more urgent due to the inability to increase its storage area. To avoid CO2 emissions, the use of non-Portland cement ...binders is recommended. The application of geopolymerization of waste sludge (WS) from water-purification plants is a novel solution. Curing conditions including high temperature, pressure or microwaves enhance the formation of geopolymer bonds. This paper presents the results of a research on the treatment of the WS of the Thu Duc water-purification plant (Vietnam) with the geopolymerization method. Solid phases were prepared by mixing the WS and fly ash (FA). The FA proportions of the solid phases were (10, 40, 70) w/%. The alkali-activated solution (AAS) was a mixture of a 40 w/% NaOH 6M solution and 60 w/% water glass (WG: Na2O.nSiO2 with n = 1.75 and volumetric density r = 1.40 kg/L). The geopolymer materials were mixtures containing an 80 w/% solid phase and a 20 w/% liquid phase of the AAS. Geopolymer samples were formed in a cylindrical steel mold with a diameter of 10 mm at a high pressure. The samples were cured in a 112 W microwave oven for 30 s or in a dryer at 110 °C for 24 h. The compressive strength and volumetric density of both sample groups were determined and compared to each other. The formation of geopolymer bonds was investigated using XRD, FTIR and SEM.
The OECD and the Directorate-General for Environment, the European Commission department responsible for EU policy on the environment, joined forces to examine current and future water-related ...financing challenges faced by EU member states. These include investments needed to comply with EU regulation for water supply, wastewater collection and treatment, and flood protection. As part of the research, new data was produced on current levels of expenditure for water supply, sanitation and flood protection, as well as on projected needs. It supported a comparison across member states and substantiated tailored policy discussions in selected countries and at European level. This report captures the rationale for the research, the main quantitative outcomes and the policy issues and recommendations that derived from this two-year co-operation. Lessons from Europe outlined in this report can inspire similar research and policy discussions in other parts of the world.
Das Buch führt nach zwei Jahren Erfahrung mit der Datenschutz-Grundverordnung eine Evaluation aus Verbrauchersicht durch und präsentiert 33 einfache konkrete Vorschläge, ihren Text zu verbessern, um ...ihre Ziele besser zu verwirklichen. Daneben erörtert es konzeptionelle Schwächen der Verordnung und entwickelt Vorschläge für Lösungen, die ihren Schutzauftrag erfüllen. Die Verordnung ist für viele typische Anwendungssituationen viel zu abstrakt und provoziert daher Rechtsunsicherheit und Investitionsstau. Sie wird keiner Herausforderung moderner Informationstechnik gerecht und bewirkt dadurch Schutzlücken. Die wiederkehrenden Evaluationen der Verordnung können dazu beitragen, Mängel zu beseitigen und eine Evolution des EU-Datenschutzrechts zu bewirken.
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