Ermittlung von Verfahrensgrenzen für das Fügen durch Knickbauchen anhand des Werkstoffes E235+N

Through a systematic approach and the consistent comparison of the results between experimental and numerical investigations, a deep understanding of the bulging mechanisms has been first developed. From these investigations process limitations were derived and presented in the form of a working diagram for the material E235+N. With regard to a wide industrial use of upset bulging as a joining technology, a technologically, productively as well as economically appropriate method could be developed and validated by means of practical and numerical experiments.     

The Water-Soluble Peripheral Substituted Phthalocyanines as Corrosion Inhibitors for Copper in 0.1 N HCl: Gravimetric,Electrochemical, SEM-EDS,and Quantum Chemical Calculations

Protection of Metals and Physical Chemistry of Surfaces - Corrosion inhibition effects of water-soluble peripheral substituted cobalt, copper and zinc metallophthalocyanines (CoPc (1), CuPc (2) and...     

Comparative investigations into microstructural and mechanical properties of as-cast and laser powder bed fusion (LPBF) fabricated duplex steel (1.4517)

A methodology is presented that compares the microstructural and mechanical properties of as-cast and additive-made ferritic-austenitic duplex steel 1.4517. Microstructure of approximately equal amounts of ferrite and austenite measured in as-cast material could not be replicated in post heat-treated laser powder bed fusion samples after 30 min and 60 min of post heat treatment. This is attributed to nitrogen loss during powder atomization which left fewer austenite formers. Post-heat treated laser powder bed fusion samples of duplex structure had its austenite content repeatedly adjusted between 38 % and 40 %. As-built laser powder bed fusion tensile specimens which had a ferritic microstructure recorded high tensile and yield strength but had very poor elongation. Post heat-treated duplex laser powder bed fusion tensile specimen built in both horizontal and vertical orientations had good tensile and yield strength comparable to conventional casting processes; Tensile strength – 739 MPa (horizontal), 759 MPa (vertical); Yield strength (R_p0.2) – 489 MPa (horizontal), 525 MPa (vertical). The horizontally built duplex specimen had a very high elongation of 32 % than the vertical (11 %) or conventionally reported (22 %). This work establishes the 1.4517 duplex steel as a good candidate with good mechanical properties when processed by additive manufacturing.     

Properties and microstructure of copper-alloyed solid solution-strengthened ductile iron

Solid solution-strengthened ductile iron (DI) exhibits outstanding mechanical properties due to the high silicon content. The strengthening by silicon addition is limited since additions above 4.3?wt-% lead to embrittlement. For a further improvement of mechanical properties, other alloying elements need to be considered. In the present work, the effect of various copper additions on the microstructure and the mechanical properties of solid solution-strengthened DI were investigated. The results show that no appreciable strengthening can be achieved by copper addition without the formation of pearlite in the matrix. The pearlite content increases considerably for Cu-additions above 0.23?wt-% and is independent of the cooling rate for the cooling conditions analysed.     

Wind turbine speed control of a contactless piezoelectric wind energy harvester

ABSTRACT

Wind turbine control is an important task to make the electricity generation secure in terms of energy demand and machine safety. It also yields to control the desired power level and optimized energy because of the assignment of turbine speed. The contactless piezoelectric wind energy harvester (CPWEH) used in this study has three piezoelectric layers located around the shaft with 120 degrees apart and they are buckled by the magnetic force without any physical contact. The superiority of this device is to generate energy for low wind speeds such as 1.5 m/s. However, for high speeds, high total harmonic distortions (THDs) govern the waveforms, thus controlling the turbine speed becomes necessary for optimizing the output power. Encouraged by this, a small low inertia dc generator is coupled with the wind turbine, and the generator terminals are connected to a resistor through a power switch to generate a braking torque that opposes to wind speed direction. By controlling the switch properly, turbine speed is ensured to remain within a certain band, which accordingly prevents the turbine from rotating very fast at damaging wind speeds. Several experiments are performed on the developed CPWEH with/without the presented control scheme which prove the existence of promising performance of our proposal.     

A BIM-GIS integrated pre-retrofit model for building data mapping

In response to rising energy costs and the impetus to reduce environmental impacts, upgrading the large building stock that is responsible for 40% of the total energy consumption to maximum energy efficiency is becoming an important task. Despite the many benefits associated with retrofit projects, they are still only slowly being implemented because of the many challenges that exist. One of these challenges is optimizing the decision between renovation scenarios based on economic and environmental goals, which can be made possible with an accurate pre-retrofit model. The intention of this paper is to introduce a pre-retrofit model that efficiently obtains and integrates multiple forms of building data as a critical step to develop a comprehensive understanding of a building to be renovated. Opportunities for utilizing building information modeling (BIM) and geographical information systems (GIS) for retrofitting projects were explored through the study of a historical campus building. With the use of as-is geometric data and as-is data, building data maps were obtained. The next step of this study is to use the model to conduct scenarios comparison and optimize renovation decision based on economic and environmental goals.     

Influence of drying conditions on colour,betacyanin content and antioxidant capacities in dried red-fleshed dragon fruit (Hylocereus polyrhizus)

In this study, drying of red-fleshed dragon fruit at different temperatures (40, 50, 60, 70 and 80 °C) and air velocities (1.0 and 1.5 m s⁻¹) was conducted under the specific humidity of 25 g H₂O kg⁻¹ dry air. The results showed that drying at higher temperatures resulted in shorter drying times. However, temperature and air velocity did not significantly affect the total betacyanin contents and antioxidant capacities in dried products. Seven betacyanins identified by LC-MS were betanin, isobetanin, phyllocactin, isophyllocactin, betanidin 5 –O-(6′O-3-hydroxybutyryl)-β-glucoside, isobetanidin 5 –O-(6′O-3-hydroxybutyryl)-β-glucoside and decarboxylated phyllocactin. In addition, the temperature increased the isomerisation of betacyanins. The most preferable condition for preserving the colour and betacyanin contents of red-fleshed dragon fruit was the drying at a temperature of 80 °C and air velocity of 1.5 m s⁻¹ since it could shorten the drying time and give a bright red colour to the dried product as well as it had no significant impact on the betacyanins.