Tide-induced residual current, a 2-D nonlinear numerical tidal model

Tide-induced residual current was studied through solution of the two-dimensional nonlinear shallow-water equation. A simple numerical method was developed and applied to Minas Channel and Minas Basin at the head of the Bay of Fundy where strong residual currents of up to 0.76 m/sec have been measured...

Risk-cost optimization of buried pipelines using subset simulation

On the basis of time-dependent reliability analysis, a computational framework called subset simulation (SS) has been applied for risk-cost optimization of flexible underground pipeline networks. SS can provide better resolution for rare failure events that are commonly encountered in pipeline engineering applications. Attention in this work is devoted to scrutinize the robustness of SS in risk-cost optimization of pipelines. SS is first employed to estimate the reliability of flexible underground pipes subjected to externally applied loading and material corrosion. Then SS is extended to determine the intervention year for maintenance and to identify the most appropriate renewal solution and renewal priority by minimizing the risk of failure and whole life-cycle cost. The efficiency of SS compared to genetic algorithm has been demonstrated by numerical studies with a view to prevent unexpected failure of flexible pipes at minimal cost by prioritizing maintenance based on failure severity and system reliability. This paper shows that SS is a more robust method in the decision-making process of reliability-based management for underground pipeline networks

Escalation of error catastrophe for enzymatic self-replicators

It is a long-standing question in origin-of-life research whether the information content of replicating molecules can be maintained in the presence of replication errors. Extending standard quasispecies models of non-enzymatic replication, we analyze highly specific enzymatic self-replication mediated through an otherwise neutral recognition region, which leads to frequency-dependent replication rates. We find a significant reduction of the maximally tolerable error rate, because the replication rate of the fittest molecules decreases with the fraction of functional enzymes. Our analysis is extended to hypercyclic couplings as an example for catalytic networks.Comment: 6 pages, 4 figures; accepted at Europhys. Let

Effects of an intensifed competition period on neuromuscular function in youth rugby union players

Playing rugby union matches causes a number of fatigue responses, including reduced lower body neuromuscular function (NMF) (commonly measured by counter movement jump (CMJ))(1). The time course of this response following match play is well established in professional (2) and academy (3) level rugby union players, who take at least 60 hours for NMF to recover. No data exist for high school level rugby union players, but these players are often exposed to multiple game tournaments and festivals (2 games in 3 days, or 3 games in 5 days) within their competition structures. Aim. The aim of this case study is to document the NMF response to playing three rugby union matches within five days. This will provide useful information to practitioners who must manage fatigue and recovery of youth rugby union players who play multiple games within short time periods

Risk-based inspection on highway assets with category 2 defects

This paper presents a study piloted on highway assets Category 2 defects. Imminent hazards on high-way road networks are significantly accelerated by structural deterioration of highway infrastructures. The inspection and maintenance strategy for highway infrastructure requires continuous improvements to reduce high occurrence of defective highway assets. Combined risk-based inspection (RBI) and stochastic (STOC) techniques is considered in this investigation to give an in-depth understanding of highway asset maintenance response. Appropriate data information is extracted from Network Maintenance Management System and complementary information elicited from maintenance experts as well as recommended standards. Safety inspections piloted within the period of 5 years is evaluated using the projected RBI-STOC approach. The RBI incorporates the consequences and likelihood of the defects and the combined STOC techniques utilised defines the actual maintenance interval operated. The RBI-STOC approach proposes reclassification of highway asset defect repair intervals, appropriate maintenance task response and efficient maintenance prioritisation of highway assets in equivalence with contribution to system average mean time to repair and downtime

Injury incidence and characteristics in South African school first team rugby: A case study

Background: Despite its apparent popularity, participation in the sport of rugby union is accompanied by a significant risk of injury. Concerned parties have recently questioned whether this risk is acceptable within school populations. This is difficult to assess within the South African schools’ population as no recent longitudinal injury studies exist. Objectives: To determine the training habits, rugby-related exposure and injury risk within a population of South African high school first team rugby players. Methods: Training and match exposure in both school and provincial competition examined and the resultant injuries were longitudinally observed for the duration of a South African high school rugby season. Results: Match (79, 95%CI 52-105 injuries/1 000 h) and training (7, 95%CI 3-11 injuries /1000h) injury incidences were demonstrated to be greater than previously reported incidences in similar populations in England and Ireland. Weeks where players were exposed to both school and provincial competition (34, 95%CI 19-49 injuries /1 000 h) had significantly (p<0.05) greater injury incidences than during school competition alone (19, 95%CI 12-26 injuries /1 000 h). Conclusions: The injury risk demonstrated was greater than expected and represents reasons for concern. Possible reasons for the high injury incidence recorded may be the frequency of games played within the season, and the overlap of school and provincial competitions. It should be noted that these results were taken from one school over one season and might not be representative of the incidence of school rugby injuries overall. However, this research demonstrates the need for a multischool longitudinal study within South African schools rugby to determine the overall risk

Pandoraea sp. strain E26: discovery of its quorum-sensing properties via whole-genome sequence analysis

YesWe report the draft genome sequence of Pandoraea sp. strain E26 isolated from a former landfill site, sequenced by the Illumina MiSeq platform. This genome sequence will be useful to further understand the quorum-sensing system of this isolate.University of Malaya High-Impact Research (HIR) grants (UM C/625/1/HIR/MOHE/CHAN/01, grant A-000001- 50001 and UM-MOHE HIR UM C/625/1/HIR/MOHE/CHAN/14/1, grant H-50001-A000027

Motion of finite-size spheres released in a turbulent boundary layer

Individual magnetic wax spheres with specific gravities of 1.006, 1.054 and 1.152 were released from rest on a smooth wall in water at friction Reynolds numbers, Re_{\tau}=680 and 1320 (d^+ = 58 and 122 viscous units, respectively). Three-dimensional tracking was conducted to understand the effect of turbulence and wall friction on sphere motions. Spheres subjected to sufficient mean shear initially lifted off of the wall before descending back towards it. These lifting spheres translated with the fluid above the wall, undergoing saltation or resuspension, with minimal rotation about any axis. By contrast, spheres that did not lift off upon release mainly slid along the wall. These denser spheres lagged the fluid more significantly due to greater wall friction. As they slid downstream, they began to roll forward after which small repeated lift-off events occurred. These spheres also rotated about both the streamwise and wall-normal axes. In all cases, the sphere trajectories were limited to the buffer and logarithmic regions, and all wall collisions were completely inelastic. Sphere streamwise velocities fluctuated up to 20% from the mean value even after the sphere had attained an approximate terminal velocity. In the plane parallel to the wall, the spheres migrated in the spanwise direction about 12% of the streamwise distance traveled suggesting that spanwise forces are important. The variations in sphere kinematics were likely induced by high and low momentum zones in the boundary layer, vortex shedding in the sphere wakes, and wall friction. The repeated lift-offs of the forward rolling denser sphere were attributed to a Magnus lift.Comment: Revised manuscript accepted by International Journal of Multiphase Flow on September 13, 2020; 33pages; 10 figure