Suche
Anzeige der Dokumente 11-20 von 352
Aufsatz
Effect of Friction Stir Processing on Microstructural, Mechanical, and Corrosion Properties of Al-Si12 Additive Manufactured Components
(2020-01-03)
Additive manufacturing (AM) is an advanced manufacturing process that provides the opportunity to build geometrically complex and highly individualized lightweight structures. Despite its many advantages, additively manufactured components suffer from poor surface quality. To
locally improve the surface quality and homogenize the microstructure, friction stir processing (FSP) technique was applied on Al-Si12 components produced by selective laser melting (SLM) using two different working media. The effect of FSP on ...
Aufsatz
Influence of complex geometries on the properties of laser-hardened surfaces
(2020-04-25)
Laser surface hardening provides for many advantages in terms of flexible production due to very localized and controlled energy input into the material. Laser processing offers the possibility to treat surfaces in order to locally strengthen the areas that are prone to fatigue cracking. It is well known that laser energy absorption depends on many parameters, e.g., the surface structure and the surface orientation. The incident angle of the laser beam plays a key role in this regard. When complex geometries like ...
Aufsatz
Consequences of Deep Rolling at Elevated Temperature on Near-Surface and Fatigue Properties of High-Manganese TWIP Steel X40MnCrAl19-2
(2021-11-05)
Due to pronounced work-hardening induced by the complex interplay of deformation mechanisms such as dislocation slip, twinning and/or martensitic phase transformation, high-manganese steels represent a class of materials well-suited for mechanical surface treatment. In the present study, the fatigue behavior of a high-mangsanese steel showing twinning-induced plasticity (TWIP) effect at room temperature (RT) was investigated after deep rolling at 550 °C. Results are compared to a former study discussing the behavior ...
Aufsatz
Contribution of dairy goat farming to household dietary diversity among smallholder farmers in the Central Highlands of Kenya
(2023-02-21)
In Kenya, dairy goat farming has highly been practiced for food provision and as an income-generating enterprise. However, there is scanty information on the contribution of dairy goat farming to the quality of diets consumed at household level especially among rural smallholder farmers. This study therefore analysed the contribution of dairy goat farming to household dietary diversity of the smallholder farmers. Data was collected at the end of the wet season (April-May) from a sample of 385 households in Kirinyaga ...
Aufsatz
Small-scale farmers’ coping strategies to extreme weather events in Upper Guinea
(2023-03-06)
Extreme weather events pose a serious threat to subsistence farming and food security in Upper Guinea, where most farmers rely heavily on rain-fed agriculture. Following crop failures, farmers use what is available to them to try to maintain household food security. This paper investigated the coping strategies chosen by farmers in Upper Guinea and the motivating factors behind them. A multistage sampling method was used to select a purposive random sample of 1,500 farm households within nine selected livelihood zones ...
Aufsatz
Excellent superelasticity in a Co-Ni-Ga high-temperature shape memory alloy processed by directed energy deposition
(2020-04-30)
A Co-Ni-Ga high-temperature shape memory alloy has been additively manufactured by directed energy deposition. Due to the highly anisotropic microstructure, i.e. columnar grains featuring a strong near-⟨001⟩ texture in build direction, the as-built material is characterized by a very low degree of constraints and, thus, shows excellent superelasticity without conducting a post-process heat treatment. As characterized by in situ deformation testing and post-mortem microstructural analysis, additive manufacturing ...
Aufsatz
Novel Class of Rhenium Borides Based on Hexagonal Boron Networks Interconnected by Short B₂ Dumbbells
(2022-09-06)
Transition metal borides are known due to their attractive mechanical, electronic, refractive, and other properties. A new class of rhenium borides was identified by synchrotron single-crystal X-ray diffraction experiments in laser-heated diamond anvil cells between 26 and 75 GPa. Recoverable to ambient conditions, compounds rhenium triboride (ReB₃) and rhenium tetraboride (ReB₄) consist of close-packed single layers of rhenium atoms alternating with boron networks built from puckered hexagonal layers, which link ...
Aufsatz
A new method for microscale cyclic crack growth characterization from notched microcantilevers and application to single crystalline tungsten and a metallic glass
(2022-06-22)
The lifetime of most metals is limited by cyclic loads, ending in fatigue failure. The progressive growth of cracks ends up in catastrophic failure. An advanced method is presented for the determination of cyclic crack growth on the microscale using a nanoindenter, which allows the characterization of > 10,000 loading cycles. It uses focused ion beam fabricated notched microcantilevers. The method has been validated by cyclic bending metallic glass and tungsten microcantilevers. The experiments reveal a stable crack ...
Aufsatz
Comparison of linear discriminant analysis, support vector machine and artificial neural network in classifying Nigerian local turkeys based on plumage colours using biometric traits
(2022-10-18)
The ability of linear discriminant analysis (LDA), support vector machine (SVM), and artificial neural network (ANN) models to differentiate biometric traits of Nigerian local turkeys was investigated in this study. The biometric traits (bodyweight, body length, breast girth, thigh length, shank length, keel length, wing length, and wingspan) in 200 (20-week-old) turkeys were measured. Seventy percent of the datasets were used to train the three models, with the remaining 30% being used to test their performance. All ...
Aufsatz
Use of corncob biochar and urea for pakchoi (Brassica rapa L.) cultivation: Short-term impact of pyrolysis temperature and fertiliser dose on plant growth and yield
(2022-10-18)
This study aimed to evaluate the effect of pyrolysis temperature of corncob biochar as a soil amendment and urea fertiliser on the growth and yield of pakchoi. Pakchoi was cultivated in pots
(13 cm height, 19 cm upper diameter, and 13.5 cm bottom diameter). Two factors including pyrolysis temperature of biochar and urea dose were combined with four levels each. Pyrolysis temperature factor consisted of B0 (no biochar), B1 (250 °C), B2 (300 °C), and B3 (350 °C). Urea dose consisted of F0 (no urea), F1 (0.6 g pot-¹), ...