383 research outputs found
Flaw growth behavior of Inconel 718 at room and cryogenic temperature Final report, 29 Apr. 1968 - 31 Oct. 1969
Fracture crack propagation in Inconel at room and cryogenic temperatures for surface defective sample
Analysis of fatigue, fatique-crack propagation, and fracture data
Analytical methods have been developed for consolidation of fatigue, fatigue-crack propagation, and fracture data for use in design of metallic aerospace structural components. To evaluate these methods, a comprehensive file of data on 2024 and 7075 aluminums, Ti-6A1-4V, and 300M and D6Ac steels was established. Data were obtained from both published literature and unpublished reports furnished by aerospace companies. Fatigue and fatigue-crack-propagation analyses were restricted to information obtained from constant-amplitude load or strain cycling of specimens in air at room temperature. Fracture toughness data were from tests of center-cracked tension panels, part-through crack specimens, and compact-tension specimens
An experimental and theoretical investigation of plane-stress fracture of 2024-T351 aluminum alloy
Plane-stress fracture behavior of precracked aluminum alloy
Sports Heroes and Mass Sports Participation – the (Double) Paradox of the 'German Tennis Boom'
Migration Governance in South America: Regional Approaches versus National Laws
Regional Consultative Processes (RCPs) have become the standard for multilateral migration policy discussion over the last two decades. RCPs are geographically bounded, non-binding meetings organized voluntarily by states and promoted by international organizations. Our chapter contributes to accumulating knowledge regarding the migration governance role of RCPs by investigating the South American Conference on Migration (CSM). We conduct a thematic analysis of CSM documents from its first annual meeting in 2000 until 2017 to find the most salient themes. We then examine migration-related legislation to uncover to what extent national laws incorporate regional discussion and accords. We find that although multilateral cooperation has created a set of common standards and practices, their domestic incorporation remains uneven. This chapter sheds light on the synergy between regional-level priorities and national-level laws, revealing a limitation of regional migration governance.FGW – Publications without University Leiden contrac
Adapting temperature predictions to MR imaging in treatment position to improve simulation-guided hyperthermia for cervical cancer
Hyperthermia treatment consists of elevating the temperature of the tumor to increase the effectiveness of radiotherapy and chemotherapy. Hyperthermia treatment planning (HTP) is an important tool to optimize treatment quality using pre-treatment temperature predictions. The accuracy of these predictions depends on modeling uncertainties such as tissue properties and positioning. In this study, we evaluated if HTP accuracy improves when the patient is imaged inside the applicator at the start of treatment. Because perfusion is a major uncertainty source, the importance of accurate treatment position and anatomy was evaluated using different perfusion values. Volunteers were scanned using MR imaging without (&#x201C;planning setup&#x201D;) and with the MR-compatible hyperthermia device (&#x201C;treatment setup&#x201D;). Temperature-based quality indicators were used to assess the differences between the standard, apparent and the optimized hyperthermia dose. We conclude that pre-treatment imaging can improve HTP predictions accuracy but also, that tissue perfusion modelling is crucial if temperature-based optimization is applied.</p
Dynamics of positive- and negative-mass solitons in optical lattices and inverted traps
We study the dynamics of one-dimensional solitons in the attractive and
repulsive Bose-Einstein condensates (BECs) loaded into an optical lattice (OL),
which is combined with an external parabolic potential. First, we demonstrate
analytically that, in the repulsive BEC, where the soliton is of the gap type,
its effective mass is \emph{negative}. This gives rise to a prediction for the
experiment: such a soliton cannot be not held by the usual parabolic trap, but
it can be captured (performing harmonic oscillations) by an anti-trapping
inverted parabolic potential. We also study the motion of the soliton a in long
system, concluding that, in the cases of both the positive and negative mass,
it moves freely, provided that its amplitude is below a certain critical value;
above it, the soliton's velocity decreases due to the interaction with the OL.
At a late stage, the damped motion becomes chaotic. We also investigate the
evolution of a two-soliton pulse in the attractive model. The pulse generates a
persistent breather, if its amplitude is not too large; otherwise, fusion into
a single fundamental soliton takes place. Collisions between two solitons
captured in the parabolic trap or anti-trap are considered too. Depending on
their amplitudes and phase difference, the solitons either perform stable
oscillations, colliding indefinitely many times, or merge into a single
soliton. Effects reported in this work for BECs can also be formulated for
optical solitons in nonlinear photonic crystals. In particular, the capture of
the negative-mass soliton in the anti-trap implies that a bright optical
soliton in a self-defocusing medium with a periodic structure of the refractive
index may be stable in an anti-waveguide.Comment: 22pages, 9 figures, submitted to Journal of Physics
Solitons in one-dimensional nonlinear Schr\"{o}dinger lattices with a local inhomogeneity
In this paper we analyze the existence, stability, dynamical formation and
mobility properties of localized solutions in a one-dimensional system
described by the discrete nonlinear Schr\"{o}dinger equation with a linear
point defect. We consider both attractive and repulsive defects in a focusing
lattice. Among our main findings are: a) the destabilization of the on--site
mode centered at the defect in the repulsive case; b) the disappearance of
localized modes in the vicinity of the defect due to saddle-node bifurcations
for sufficiently strong defects of either type; c) the decrease of the
amplitude formation threshold for attractive and its increase for repulsive
defects; and d) the detailed elucidation as a function of initial speed and
defect strength of the different regimes (trapping, trapping and reflection,
pure reflection and pure transmission) of interaction of a moving localized
mode with the defect.Comment: 12 pages, 10 figure
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