Prevalence of bicuspid aortic valve (BAV) and right aberrant sub-clavian artery (ASA) separately is relatively common in general population, and much higher in some disorders. Surprisingly, ...coexistence of both valve and vessel anomalies has only been reported in single cases.
From 2008 to 2016, in a single, high-volume tertiary cardiac centre, patients who underwent chest computed tomography (CT) for various reasons, were retrospectively screened for the presence of right ASA.
Seventy-two patients with either right or left ASA were identified by CT. Among them 7 cases of BAV and right ASA coexistence were identified. Additionally, 1 case with coexisting common origin of carotid arteries (COCA) was visualised in this subgroup.
Although coexistence of ASA and BAV has not been reported in paediatric population, it has been diagnosed in very few adults as well as in our series. Additional presence of COCA in this group seems to be very rare. From practical point of view, heart cannulation via the radial artery and subsequent ASA may be challenging. Similarly, COCA presence may have surgical implications during corrective procedures.
We make an attempt to explain brittle propagation of short fatigue cracks in specimens of WT3-1 titanium alloy tested by simultaneous bending and torsion. It is assumed that the fracture process can ...be affected by hydrogen absorbed from the atmosphere and penetrating to the tips of microcracks in the subsurface layer of the material. Higher concentrations of hydrogen observed near the crack lips located near the specimen surface as compared with the bulk of the specimen confirm the assumption that the effect of hydrogen is responsible for the brittle propagation of short fatigue cracks.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
We propose a modified model for the description of crack growth formulated in terms of a probabilistic approach based on a two-parameter Weibull distribution. Unlike the earlier proposal of the ...authors, in this new model, the applied level of stresses explicitly appears in all deduced equations. The process of crack growth is described by a difference equation fundamental for the proposed model. The efficiency of the method is illustrated by an example of prediction of crack growth and fatigue life for specimens of laser-hardened medium-carbon steel subjected to reversed torsion. The character of fatigue crack growth and specific features of fractographic pictures of the fracture surfaces in the investigated specimens are analyzed.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
A probabilistic and simplified approach to the description of short crack growth in shot‐peened, medium carbon steel specimens is presented. In order to model the dynamics of short crack growth, a ...difference equation has been formulated with coefficients originating from a two‐parameter Weibull distribution of crack advance. The Fokker–Planck partial differential equation is the source of a solution based on the form of a probability density function of crack length. The resolved function allows one to calculate the expected crack length, crack growth rate and standard deviation of crack length. The viability of the probabilistic method has been verified using experimental data gained for shot‐peened specimens fatigued under reversed torsion.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
Special needs that concern fatigue damage of aircraft components require undertaking the investigations of fatigue crack growth in aerospace alloys and finding the correlation between the images of ...fracture surface and the accumulated damage due to applied load. Importance of fractography supporting the analysis of failure cases of real structures was pointed out among others by J. Schijve in his recently published book 1. In order to check the capability of the reconstruction of load-time history on the basis of fractographic analysis extensive research program was developed for 2024-T3 Aclad aluminium alloy sheet subjected to different variable amplitude loads 2. The paper presents the results both of fatigue crack growth response and the microfracture analysis for the CCT specimens (400×100×3 mm) under two similar loads LHL (low-high-low) and FAF (flight-after-flight) (Fig. 1a and b). These loads are employed when simulating the flight loads of the lower skin aircraft wing structure.
Fatigue strength and fatigue crack growth in laser hardened specimens made of 0.2% C and 0.45% C carbon steels, high strength steel and carburized CrMn steel subjected to reversed bending were ...studied. Fatigue life of laser hardened specimens was two-four times greater than in the case of non-hardened samples of steels mentioned above. Fatigue crack growth al- tered irregularly depending on structure, geometry of surface laser tracks and residual stresses. The mechanism of fracture was established by frac- tographic analysis of fracture surfaces. INTRODUCTION S
Fatigue strength of specimens with semielliptical surface crack is investigated by Paris formula under consideration of changes of front crack shape. Experiments and calculations carried out ...subsequently show that the crack expands very fast to the depth in the initial phase, while developing faster at the surface a short time before cracking. Theory and experiment show a good correspondence.--AA
This article deals with a new, simple and effective method of throughput improvement. The method can be applied in every kind of single and multicore processors. It does not require any integration ...into integrated circuit topology only modification consists of additional placement of temperature sensor in a heat sink. A simple algorithm controls processor's power in such a way that it utilizes full physical ability of integrated circuits working under thermal constraints. Some theoretical investigations are verified by practical experiments.
•New, simple and effective method of processor's throughput improvement•Small reaction time to changing environment•Adding one temperature sensor results in significant improvement of thermal trotting.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPUK, ZRSKP
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