1,742,926 research outputs found
A mechanistic approach to the Kitagawa-Takahashi diagram using a multiaxial probabilistic framework
No full textThe aim of this paper is to propose a flexible multiaxial modelling framework that is capable of combining two fatigue damage mechanisms so as to continuously describe the Kitagawa-Takahashi diagram. It is proposed that this diagram represents two distinct fatigue damage mechanisms: one associated with crack initiation (or microstructurally small cracks) and the other with crack propagation (or long cracks). It is further postulated that these damage mechanisms are more appropriately modelled using di erent fatigue criteria. A probabilistic modelling framework is proposed in which any two suitable fatigue criteria can be combined in order to simultaneously model both damage mechanisms and the transition between them. This framework is based on the weakest link hypothesis and results in a probabilistic Kitagawa-Takahashi type diagram
The effect of quenching and defects size on the HCF behaviour of Boron steel
No full textThis work investigates the effect of natural and artificial surface defects and quenching on the fatigue strength of a Boron steel (22MnB5). A vast experimental campaign has been undertaken to study the high cycle fatigue behaviour and more specifically the fatigue damage mechanisms observed in quenched and untreated materials, under different loading conditions and with differents artificial defects sizes (from 25 μm to 370 μm radius). In order to test the sheet metal in shear an original test apparatus is used. The critical defect size is determined to be 100 ± 50 μm. This critical size does not appear to depend on the loading type or the microstructure of the material (i.e. ferritic–perlitic or martensitic). However, for large defects, the quenched material is more sensitive to the defect size than the untreated material. For a defect size range of 100–300 μm the slope of the Kitagawa–Takahashi diagram is approximately −1/3 and −1/6 for the quenched and untreated materials respectively. A probabilistic approach that leads naturally to a probabilistic Kitagawa type diagram is developed. This methodology can be used to explain the relationship between the influence of the heat treatment and the defect size on the fatigue behaviour of this steel
Kitagawa-Oaxaca-Blinder decomposition of gender pay gap for non-farm employed people aged 25–55 in Malawi, Tanzania and Nigeria.
No full textKitagawa-Oaxaca-Blinder decomposition of gender pay gap for non-farm employed people aged 25–55 in Malawi, Tanzania and Nigeria.</p
Kitagawa-Oaxaca-Blinder decomposition of gender pay gap at the median for non-farm employed people aged 25–55 in Malawi, Tanzania and Nigeria.
No full textKitagawa-Oaxaca-Blinder decomposition of gender pay gap at the median for non-farm employed people aged 25–55 in Malawi, Tanzania and Nigeria.</p
Block printing: Hidemaro Kitagawa
No full textPhoto shows a block print by Japanese artist Hidemaro Kitagawa, showing two Japanese womenHidemaro, Kitagawa 19th C, Pup. of Utamaro, NBN Col
An investigation into inconsistencies between theoretical predictions and microphone array measurements of railway rolling noise
No full textTheoretical models, such as TWINS, and microphone array measurements have been
widely used to gain better understanding of rolling noise. However, the array
measurements are often inconsistent with the TWINS predictions and give less
prominence to the rail than the theoretical models. The objectives of this thesis are to
make validation work of the TWINS model for Japanese railway lines, and to explore the
reason why the microphone array gives a correct estimate of sound power radiated by the
rail.
A comparison in terms of noise and rail vibration has been carried out for six wheel/rail
conditions of Japanese railways. The TWINS predictions show good agreement with the
measurements. After confirming the applicability of the TWINS model, the effects of
wheel load on noise and rail vibration are investigated, and the predictions show similar
trends to the measurements. The acoustic properties of a rail as measured with a
microphone array have been investigated through simulations and field tests. In the
simulation the rail is modelled as an array of multiple sources. Results are given for two
situations: (a) the multiple sources are incoherent, which is assumed in determining
sound power from a microphone array, (b) the sources are coherent, which is more
representative of the rail radiation. It is found that the microphone array cannot detect a
large part of the noise generated by the rail in the frequency range where free wave
propagation occurs. Sound measurements were carried out to validate the radiation model
of the rail by using a shaker excitation of a track. It is found that the noise is radiated
from the rail at an angle to the normal when free wave propagation occurs in the rail, and
that the predictions based on coherent sources show good agreement with the
measurements. Sound measurements for a moving train were also performed with a
microphone array. It is shown that the microphone array misses a large part of noise
generated by the rail, when directed normal to the rail. This leads to an underestimation
of the rail component of the noise in the array measurements
Kitagawa-Oaxaca-Blinder decomposition of gender pay gap for non-farm employed people aged 25–55 in Malawi, Tanzania and Nigeria, corrected for selection bias using Heckman selection models.
No full textKitagawa-Oaxaca-Blinder decomposition of gender pay gap for non-farm employed people aged 25–55 in Malawi, Tanzania and Nigeria, corrected for selection bias using Heckman selection models.</p
Block printing: Kitagawa Utamaro [002]
No full textPhoto of a block print by Kitagawa Utamaro, one of his studies of Japanese women (bijinga (美人畫), literally "beautiful person picture")Kitagawa Utamaro (Japanese, c. 1753-1806), NBN Coll
Block printing: Kitagawa Utamaro [001]
No full textPhoto of a block print by Kitagawa Utamaro, one of his studies of Japanese women (bijinga (美人畫), literally "beautiful person picture")Kitagawa Utamaro (Japanese, c. 1753-1806)
When we fail to question in Japanese
No full textWhen we pay close attention to the prosody of Wh-questions in Japanese, we discover many novel and interesting empirical puzzles that would require us to devise a much finer syntactic component of grammar. This paper addresses the issues that pose some problems to such an elaborated grammar, and offers solutions, making an appeal to the information structure and sentence processing involved in the interpretation of interrogative and focus constructions
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