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Aufsatz
Influence of the Miniaturisation Effect on the Effective Stiffness of Lattice Structures in Additive Manufacturing
(2020-10-29)
Thin-walled and cellular structures are characterised by superior lightweight potential due to their advantageous stiffness to weight ratio. They find particular interest in the field of additive manufacturing due to robust and reproducible manufacturability. However, the mechanical performance of such structures strongly depends on the manufacturing process and resultant geometrical imperfections such as porosity, deviations in strut thickness or surface roughness, for which an understanding of their influence is ...
Aufsatz
Damage Tolerance Evaluation of E-PBF-Manufactured Inconel 718 Strut Geometries by Advanced Characterization Techniques
(2020-01-06)
By means of electron beam powder bed fusion (E-PBF), highly complex lightweight structures can be manufactured within short process times. Due to the increasing complexity of producible components and the entangled interplay of damage mechanisms, common bulk material properties such as ultimate tensile or fatigue strength are not sufficient to guarantee safe and reliable use in demanding applications. Within this work, the damage tolerance of E-PBF-manufactured Ni-based alloy Inconel 718 (IN 718) strut geometries ...
Aufsatz
Determination and Validation of Residual Stresses in CFRP/Metal Hybrid Components Using the Incremental Hole Drilling Method
(2020-09-21)
Lightweight materials contribute to an efficient decrease in fuel consumption in the automotive and aircraft industries. Hybrid components made of metal and carbon fiber-reinforced plastics (CFRP) have a high potential in lightweight applications due to their high strength-to-weight ratio. For cost-effective processing of hybrid materials, advanced manufacturing processes such as the prepreg-press-technology have been developed, in which the bonding between a metallic component and a fiber compound is exclusively ...
Aufsatz
On the structural integrity of Fe-36Ni Invar alloy processed by selective laser melting
(2020)
Specimens made from pre-alloyed Invar (Fe-36Ni) powder were fabricated by selective laser melting and stress-relief heat treated afterwards. A relative density of the fabricated parts of 99.6 % was determined by computed tomography. The microstructure and mechanical behavior under monotonic and particularly cyclic loading at ambient temperature were investigated. Results reveal a bimodal microstructure containing columnar and equiaxed grains with an average grain size of 75 μm and pronounced texture 〈001〉 || BD. The ...
Aufsatz
Ordoliberalism Out of Order? The Fragile Constitutionality of Greek Austerity (Part Two)
(2020-06)
This is the second part of a two-part post. The first part, available here, considered the historical background of the concept of constitutional order and its relation to the ordoliberal project. Judicial independence was examined in parallel with central bank independence, with each understood as a means of insulating policy from social and democratic pressures and also as a means of enacting and maintaining fiscal discipline and market-conforming order. It also included some preliminary observations on the relation ...
Aufsatz
Science–Policy Interfaces Related to Biodiversity and Nature Conservation: The Case of Natural Capital Germany—TEEB-DE
(2020-05-03)
Responding to the UN programme “The Economics of Ecosystems and Biodiversity” (TEEB), TEEB-DE (2012–2018) was a science–policy interface (SPI) set up in Germany with the objective of mobilising scientific expertise for a better consideration of biodiversity and ecosystem services in political and corporate decision-making. The aim of this paper is to contribute to an assessment of TEEB-DE by analysing its objectives, structure, processes and outputs. The analysis is guided by a theoretical framework that takes ...
Aufsatz
Implementing Distributed Practice in Statistics Courses: Benefits for Retention and Transfer
(2020-11-18)
The present study investigated the effect of distributed versus crammed practice before a course deadline on the retention and transfer of knowledge, and whether learner characteristics moderate the effect. In Experiment 1, only 41% (N = 38) of the initially enrolled students worked the voluntary but recommended practice tasks. Moreover, markedly fewer students did so in the distributed condition (12%) than the crammed practice condition (29%). In Experiment 2, working the practice tasks was mandatory and more students ...
Aufsatz
Optimising beekeeping development programs for improved productivity, income and welfare: a case study of Papua New Guinea
(2020-10-19)
Beekeeping can provide important sources of cash income for farmers in developing countries where land is unconducive to crop and livestock production systems. In many low-income countries however, attrition among beekeeping adopters remains a chronic problem, colony losses are high, support for and coordination of the sector is low, and practices, production and income from beekeeping is often inefficient. This study investigated the key drivers and practices influencing incomes from beekeeping, honey production and ...
Aufsatz
Forage biomass availability, species diversity and seasonal variation in grazing behaviour of cattle in the outskirts of Ouagadougou
(2020-10-14)
In order to determine the exploitation of grazing areas in the outskirts of Ouagadougou by cattle herds, the grazing behaviour of cows was monitored in five villages in these during three distinct seasons, namely wet, cool dry and hot dry season. A vegetation study including a census of the woody and herbaceous stratum of grazing areas allowed for an assessment of the pasture biomass availability during the wet season. Results of the monitoring of cattle herds showed that the land type grazed by cattle in the outskirts ...
Aufsatz
Drivers of farmers market participation in southeast Nigeria
(2020-10-29)
The objective of this paper was to investigate the drivers of farmers’ participation in the output market for yellow pepper using a sample of 420 randomly selected producers from 8,500 farmers in selected markets in southeast Nigeria. The heterogeneity of smallholder market participation was modelled with quantile regression. The variables that affected all the quantiles (i.e. for subsistence, semi-subsistence, intermediate, semi-commercial and commercially oriented farms) are the distance to the trading centre and ...