A case study on the seismic performance of earth dams

The seismic non-linear behaviour of earth dams is investigated by using a well-documented case study and employing advanced static and dynamic coupled-consolidation finite-element analysis. The static part of the analysis considers the layered construction, reservoir impoundment and consolidation, whereas the dynamic part considers the response of the dam to two earthquakes of different magnitude, duration and frequency content. The results of the analysis are compared with the recorded response of the dam and exhibit a generally good agreement. The effects of the narrow canyon geometry, the reservoir impoundment and the elasto-plastic soil behaviour on the seismic dam behaviour are investigated. Finally the implications of the adopted constitutive modelling assumptions on the predicted response are discussed

Predictors of significant coronary artery disease in atrial fibrillation: are cardiac troponins a useful measure

Background Cardiac Troponin I (cTnI) is frequently measured in patients presenting with symptomatic atrial fibrillation (AF). The significance of elevated cTnI levels in this patient cohort is unclear. We investigated the value of cTnI elevation in this setting and whether it is predictive for significant coronary artery disease (sCAD). Methods We conducted a retrospective, single-center, case–control study of 231 patients who presented with symptomatic AF to The Prince Charles Hospital emergency department, Brisbane, Australia between 2006 and 2014. Patients who underwent serial cTnI testing and assessment for CAD were included. Clinical variables that are known to predict CAD and could potentially predict cTnI elevation were collected. Binary logistic regression was performed to identify predictors of sCAD and cTnI elevation. Results Cardiac Troponin I elevation above standard cut off was not predictive for sCAD after adjustment for other predictors (OR 1.62, 95% CI 0.79–3.32. p\ua0=\ua00.19). However, the highest cTnI concentration value (cTnI peak) was predictive for sCAD (OR 2.02, 95% CI 1.02–3.97, p\ua0=\ua00.04). Dyspnea on presentation (OR 4.52, 95% CI 1.87–10.91, p\ua0=\ua00.001), known coronary artery disease (OR 3.44, 95% CI 1.42–8.32, p\ua0=\ua00.006), and ST depression on the initial electrocardiogram (OR 2.57, 95% CI 1.11–5.97, p\ua0=\ua00.028) predicted sCAD in our cohort, while heart rate on initial presentation was inversely correlated with sCAD (OR 0.99, 95% CI 0.971–1.00, p\ua0=\ua00.034). Conclusion Troponin elevation is common in patients presenting to hospital with acute symptomatic AF and it is not a reliable indicator for underlying sCAD in this patient cohort. However, cTnI peak was a predictor of significant coronary artery disease

A practical two parameter model of pile-soil gapping for prediction of monopile offshore wind turbine dynamics

Monopile mounted offshore wind turbines (OWTs) are expected to experience a very large number of cyclic loads throughout their operational lifetime, and the existing p-y method of foundation modelling does not fully account for the effects of dynamic cyclic loading, such as pile-soil gapping. In this paper a dynamic model based on the beam on non-linear Winkler foundation scheme with a novel algorithm capable of capturing the effects of pile-soil gapping is presented. It can account for gap cave-in, and the resulting gap size can react dynamically to changing loading amplitudes, using only two calibration parameters. Static and dynamic cyclic loaded model validations are presented, and give very good agreement with experimental results, performing better than existing p-y curves for dynamic loading. The model is also applied to an OWT case study and predictions of natural frequency reduction due to soil erosion agree well with measured results. It is shown that the inclusion of gapping may result in a significant decrease to the natural frequency prediction of OWTs relative to the value predicted without gapping. As such, not to consider gapping could lead to unconservative predictions, and any additional soil degradation throughout the serviceable lifetime could therefore result in unwanted resonance. The method provided in this paper provides a simple and accurate model to predict this behaviour which is crucial to ascertain during the design phase.</p

Techniques to safeguard the underground tunnels against surface blast load

Due to the growth of underground tunnels, the safety of structures under blast loading is a major threat. Therefore, this paper focused on various techniques such as tunnel burial depth, tunnel shape, tunnel lining materials and varying the location of the blast source to safeguard underground tunnels against blast load using numerical analysis. The behaviour of concrete, reinforcement steel and the soil were incorporated by using the different constitutive model available in ABAQUS v. 2020. The predicted results were compared with the experimental results available in literature and found in close agreement. It is concluded that the layering of soil filling and depth of the burial of the tunnel found to be most important in case of external blast, whereas the stress bearing capacity of the concrete found to be important in case of internal blast. It is also concluded that the circular shape tunnel is one of the best performing tunnels

Playing Kant at the Court of King Arthur

This article contrasts the sense in which those whom Bernard Williams called ‘political realists’ and John Rawls are committed to the idea that political philosophy has to be distinctively political. Distinguishing the realist critique of political moralism from debates over ideal and non-ideal theory, it is argued that Rawls is more realist than many realists realise, and that realists can learn more about how to make a distinctively political vision of how our life together should be organised from his theorising, although it also points to a worrying tendency among Rawlsians to reach for inappropriately moralised arguments. G. A. Cohen’s advocacy of socialism and the second season of HBO’s The Wire are used as examples to illustrate these points

Flash Temperature Measurement Device for Triobological Applications

Friction excites heat, and this heat—according to Dr. Hisham Abdel-Aal of Drexel University—results in a “flash temperature, [which] is the sharp temperature rise that takes place at the surface between two rubbing solids upon motion” [1]. The objective of our project is to design and manufacture a rotating thermocouple that can measure this flash temperature between two in-contact surfaces, where one contact surface rotates relative to the other. In situations such as drilling for oil, it is particularly dangerous to expose highly combustible substances such as oil to any sort of heat. This invention is intended for research and development, and industrial purposes—such as the automotive industry, petroleum industry, medical industry and thousands of other applications where rotating devices are used. In these applications, scientists and engineers will be able to accurately measure safe operating parameters (i.e. temperatures) of various materials. This will provide precise insight on which temperature levels can degrade equipment and thus, assist in preserving equipment life. In today\u27s industry, flash temperature is measured using approximate calculations and laser devices; these theoretical formulas make assumptions, such as assuming infinite contact surfaces, that skew the accuracy of safe operating parameter of any application where friction 2 heat is excited. Additionally, infrared lasers require extensive knowledge regarding a surface’s material composition and emissivity in order to increase precision of results. The team has proposed methodology to accurately measure instantaneous spikes in temperature excited by friction between two in-contact surfaces—via a rotating thermocouple inserted beneath the surface of a rotating specimen experiencing contact friction. The initial design involved inserting a thermocouple into the fixed cylinder where a ceramic contact point is housed, but it limited the amount of data we were able to collect from the system and limited how precisely the instrument could be calibrated. The final design involves inserting the contact junction of a thermocouple just below the surface of a rotating metal sample under consideration. To compensate for the problem of a rotating reference junction, the entire rotating specimen is surrounded by a circular metal wall. The flash temperature measurement instrument will be able to collect data for different materials experiencing friction, different rotational speeds of materials under friction, and for different external loads applied to the system. After fabrication, validation of the invention is expected by ensuring that thermocouple measurements are within appropriate ranges of theoretical calculations. Additionally, the pursuit of a patent for this technology is anticipated. The photo below depicts the direct apparatus set up. The metal column held stationary, with a ceramic ball affixed. Rectangular specimen is rotated on circular disk, at some rotational velocity relative to the stationary column

The Heritability of Kidney Function Using an Older Australian Twin Population

Introduction: Twin studies are unique population models which estimate observed rather than inferred genetic components of complex traits. Nonmonogenic chronic kidney disease (CKD) is a complex disease process with strong genetic and environmental influences, amenable to twin studies. We aimed to assess the heritability of CKD using twin analysis and modeling within Older Australian Twin Study (OATS) data. Methods: OATS had 109 dizygotic (DZ) and 126 monozygotic (MZ) twin pairs with paired serum creatinine levels. Heritability of kidney function as estimated glomerular filtration rate (eGFR CKD Epidemiology Collaboration [CKD-EPI]) was modeled using the ACE model to estimate additive heritability (A), common (C), and unique (E) environmental factors. Intratwin pair analysis using mixed effects logistic regression allowed analysis of variation in eGFR from established CKD risk factors. Results: The median age was 69.71 (interquartile range 78.4–83.0) years, with 65% female, and a mean CKD-EPI of 82.8 ml/min (SD 6.7). The unadjusted ACE model determined kidney function to be 33% genetically determined (A), 18% shared genetic-environmental (C), and 49% because of unique environment (E). This remained unchanged when adjusted for age, hypertension, and sex. Hypertension was associated with eGFR; however, intertwin variance in hypertension did not explain variance in eGFR. Two or more hypertension medications were associated with decreased eGFR (P = 0.009). Conclusion: This study estimates observed heritability at 33%, notably higher than inferred heritability in genome-wide association study (GWAS) (7.1%–18%). Epigenetics and other genomic phenomena may explain this heritability gap. Difference in antihypertension medications explains part of unique environmental exposures, though discordance in hypertension and diabetes does not

Identification of optimal epitopes for Plasmodium falciparum rapid diagnostic tests that target histidine-rich proteins 2 and 3

Rapid diagnostic tests (RDTs) represent important tools to diagnose malaria infection. To improve understanding of the variable performance of RDTs that detect the major target in Plasmodium falciparum, namely, histidine-rich protein 2 (HRP2), and to inform the design of better tests, we undertook detailed mapping of the epitopes recognized by eight HRP-specific monoclonal antibodies (MAbs). To investigate the geographic skewing of this polymorphic protein, we analyzed the distribution of these epitopes in parasites from geographically diverse areas. To identify an ideal amino acid motif for a MAb to target in HRP2 and in the related protein HRP3, we used a purpose-designed script to perform bioinformatic analysis of 448 distinct gene sequences from pfhrp2 and from 99 sequences from the closely related gene pfhrp3. The frequency and distribution of these motifs were also compared to the MAb epitopes. Heat stability testing of MAbs immobilized on nitrocellulose membranes was also performed. Results of these experiments enabled the identification of MAbs with the most desirable characteristics for inclusion in RDTs, including copy number and coverage of target epitopes, geographic skewing, heat stability, and match with the most abundant amino acid motifs identified. This study therefore informs the selection of MAbs to include in malaria RDTs as well as in the generation of improved MAbs that should improve the performance of HRP-detecting malaria RDTs. Copyright © 2012, American Society for Microbiology

Modelling the impact of gapping behaviour on monopile mounted offshore wind turbine dynamics

Increased demand for renewable energy production has stimulated interest in the offshore wind turbine (OWT) industry as a viable solution, and with OWTs growing larger in scale, further research is required into the dynamics of these newer structures. The majority of installed OWTs to date are built upon monopile foundations, and it is widely acknowledged that the current design methods for offshore piles are not appropriate for the large diameter piles required. This paper uses a novel pile-soil gapping algorithm to simulate the effects ofdegradation to the soil conditions in the sea bed. Using a 1D Winkler beam spring approach, a dynamic model is validated for prediction of the natural frequencies of several OWT case studies, and the gapping algorithm is shown to reproduce well the reduction in natural frequency likely attributed to soil degradation measured from an OWT in Kentish Flats wind farm. It is found through the simulation of rotor-stop tests that the presence of gapping decreases the measured natural frequency, and this effect is greater for the monopile foundations with a smaller slenderness ratio