Analysis of reinforced concrete structures with occurrence of discrete cracks at arbitrary positions

A nonlinear analysis of in-plane loaded plates is presented, which eliminates the disadvantages of the smeared crack approach. The elements used and the computational method are discussed. An example is shown in which one or more discrete cracks are dominant

Superfluid nanomechanical resonator for quantum nanofluidics

We have developed a nanomechanical resonator, for which the motional degree of freedom is a superfluid 4He oscillating flow confined to precisely defined nanofluidic channels. It is composed of an in-cavity capacitor measuring the dielectric constant, which is coupled to a superfluid Helmholtz resonance within nanoscale channels, and it enables sensitive detection of nanofluidic quantum flow. We present a model to interpret the dynamics of our superfluid nanomechanical resonator, and we show how it can be used for probing confined geometry effects on thermodynamic functions. We report isobaric measurements of the superfluid fraction in liquid 4He at various pressures, and the onset of quantum turbulence in restricted geometry.Comment: 10 pages, 11 figure

Long-term cardiometabolic health in people born after assisted reproductive technology: a multi-cohort analysis

Aims To examine associations of assisted reproductive technology (ART) conception (vs. natural conception: NC) with offspring cardiometabolic health outcomes and whether these differ with age. Methods and results Differences in systolic (SBP) and diastolic blood pressure (DBP), heart rate (HR), lipids, and hyperglycaemic/insulin resistance markers were examined using multiple linear regression models in 14 population-based birth cohorts in Europe, Australia, and Singapore, and results were combined using meta-analysis. Change in cardiometabolic outcomes from 2 to 26 years was examined using trajectory modelling of four cohorts with repeated measures. 35 938 (654 ART) offspring were included in the meta-analysis. Mean age ranged from 13 months to 27.4 years but was <10 years in 11/14 cohorts. Meta-analysis found no statistical difference (ART minus NC) in SBP (-0.53 mmHg; 95% CI:-1.59 to 0.53), DBP (-0.24 mmHg; -0.83 to 0.35), or HR (0.02 beat/min; -0.91 to 0.94). Total cholesterol (2.59%; 0.10-5.07), HDL cholesterol (4.16%; 2.52-5.81), LDL cholesterol (4.95%; 0.47-9.43) were statistically significantly higher in ART-conceived vs. NC offspring. No statistical difference was seen for triglycerides (TG), glucose, insulin, and glycated haemoglobin. Long-term follow-up of 17 244 (244 ART) births identified statistically significant associations between ART and lower predicted SBP/DBP in childhood, and subtle trajectories to higher SBP and TG in young adulthood; however, most differences were not statistically significant. Conclusion These findings of small and statistically non-significant differences in offspring cardiometabolic outcomes should reassure people receiving ART. Longer-term follow-up is warranted to investigate changes over adulthood in the risks of hypertension, dyslipidaemia, and preclinical and clinical cardiovascular disease.Acknowledgements We thank all cohort members and researchers who participated in the study. Cohort-specific acknowledgments can be found in Supplementary material online, Text S2. Data used in this study are available to bone fide researchers upon request to each cohort. Details of how to access the data are provided in Supplementary material online, Text S2. Please contact Professor Deborah Lawlor ([email protected]) and Dr Ahmed Elhakeem ([email protected]) if you have relevant data and would like to join the ART-Health Cohort Collaboration and contribute to future collaborations

Fysical-engineering model of reinforced concrete frames in compression

A calculation of the complementary moments due to second-order effects and the analysis of the stability of reinforced concrete framed structures can be conceived as follows. With the aid of a computer a very large number of M-N-x diagrams can be produced on the basis of the standard specified stress-strain diagrams for concrete and steel. A framed structure is then analysed with an available program which takes account of second-order effects. The flexural stiffnesses EI to be adopted are estimated and corrected with reference to the M-N-x diagrams calculated once before and held in store for the purpose. The present paper discusses the drawbacks ofthis approach and proposes a method of analysis which can be fitted into existing programs for framed structures and dispenses with the large number of stored M-N-x diagrams. It is shown that direct use can be made of the stress-strain diagrams. The results are just as reliable as those obtained by the procedure utilising the M-N-/( diagrams. The method can be applied to total frames and single members in compression as well

Axisymmetry in elasticity, "Old wine in new bottles"

The theory of elasticity has been a well-established domain of engineering science for over a century, and solutions exist for many particular problems. It is not the aim of this contribution to extend the scope of the theory, but instead to draw attention to a specific way to formulate problems. So this contribution touches upon didactics in mechanics or, if you like, systematics; one may regard it as an educational section in a valedictory volume dedicated to a devoted teacher.Civil Engineering and Geoscience

Systematische bouw met directe methoden en variatieprincipes van continue en discrete mechanica-modellen

Civil Engineering and Geoscience