Metrics for Improved Reanalyses in Polar Regions

Atmospheric reanalyses are widely used for a variety of scientific endeavors in the Arctic and Antarctic. Reanalyses are used as boundary conditions for a regional and process-based models, for climate model validation, and for diagnostic analysis of physical processes, weather and climatic events. However, reanalyses are typically global and often do not account for specific, regional considerations, such as for polar regions. In this work, we provide a brief evaluation of a prototype for a new GMAO reanalysis, which incorporates higher spatial resolution, an updated approach for data assimilation, and a revised atmospheric model. We identify differences in the representation of the Arctic atmosphere in comparison to recent reanalyses. Furthermore, we provide a forum for Arctic scientists to consider the future improvements for reanalyses, and seek feedback for the following questions: 1) What are important performance factors to consider in evaluating new reanalyses? 2) What physical processes should be incorporated into new reanalyses? 3) What spatio-temporal scales should be considered

Draft genome sequence of an enterococcus faecalis strain (24FS) that was isolated from healthy infant feces and exhibits high antibacterial activity, multiple-antibiotic resistance, and multiple virulence factors

Enterococcus faecalis 24FS is a bacteriocin-producing, multiply antibiotic-resistant, and potentially virulent bacterium isolated from healthy infant feces. The draft 2.9-Mb genome sequence revealed 2,968 protein-encoding genes; 11 antibiotic resistance, 8 virulence, and 3 bacteriocin genes; and 2 plasmids, 4 prophages, 30 insertion sequence (IS) elements, 1 transposon, and 1 integron

Complete genome sequence of Lactobacillus plantarum 10CH, a potential probiotic lactic acid bacterium with potent antimicrobial aActivity

Lactobacillus plantarum 10CH is a bacteriocin-producing potential probiotic lactic acid bacterium (LAB) strain isolated from cheese. Its complete nucleotide sequence shows a single circular chromosome of 3.3 Mb, with a G+C content of 44.51%, a 25-gene plantaricin bacteriocin gene cluster, and the absence of recognized virulence factors. [Abstract copyright: Copyright © 2017 El Halfawy et al.

Enhancement of impingement heat transfer with the crossflow normal to ribs and pins between each row of holes

Impingement heat transfer investigations with obstacle (fins) on the target surface were carried out with the obstacles aligned normal to the cross-flow. Conjugate heat transfer (CHT) computational fluid dynamics (CFD) analysis were used for the geometries previously been investigated experimentally. A 10 × 10 row of impingement jet holes or hole density, n, of 4306 m−2 with ten rows of holes in the cross-flow direction was used. The impingement hole pitch X to diameter D, X/D, and gap Z to diameter, Z/D, ratios were kept constant at 4.66 and 3.06 for X, D and Z of 15.24, 3.27 and 10.00 mm, respectively. Nimonic 75 test walls were used with a thickness of 6.35 mm. Two different shaped obstacles of the same flow blockage were investigated: a continuous rectangular ribbed wall of 4.5 mm height, H, and 3.0 mm thick and 8 mm high rectangular pin-fins that were 8.6 mm wide and 3.0 mm thick. The obstacles were equally spaced on the centre-line between each row of impingement jets and aligned normal to the cross-flow. The two obstacles had height to diameter ratios, H/D, of 1.38 and 2.45, respectively. Comparison of the predictions and experimental results were made for the flow pressure loss, ΔP/P, and the surface average heat transfer coefficient (HTC), h. The computations were carried out for air coolant mass flux, G, of 1.08, 1.48 and 1.94 kg/sm2bar. The pressure loss and surface average HTC for all the predicted G showed reasonable agreement with the experimental results, but the predictions for surface averaged h were below the measured values by 5–10%. The predictions showed that the main effect of the ribs and pins was to increase the pressure loss, which led to an increased flow maldistribution between the ten rows of holes. This led to lower heat transfer over the first 5 holes and higher heat transfer over the last 3 holes and the net result was little benefit of either obstacle relative to a smooth wall. The results were significantly worse than the same obstacles aligned for co-flow, where the flow maldistribution changes were lower and there was a net benefit of the obstacles on the surface averaged heat transfer coefficient

Predictions of Impingement Heat Transfer With Dimples, Pin-Fins and Zig-Zag Rib Obstacles: Conjugate Heat Transfer Computational Fluid Dynamics Predictions

Regenerative cooling of low NOx gas turbine combustors was investigated using impingement heat transfer with all the combustion air used for wall cooling prior to passing to the flame stabiliser. 10 rows of impingement holes were modelled. Three obstacles were compared with smooth wall impingement heat transfer. The CHT/CFD methodology used was that validated against experimental results in previous publications of the authors. The impingement heat transfer enhancement geometries investigated were circular pin-fins, dimples and zig-zag ribs, which were aligned transverse to the direction of the cross-flow on the impingement target surface. The obstacles were equally spaced on the centre-line between each row of impingement jets transverse to the cross-flow. One heat transfer enhancement obstacle was used per impingement jet air hole. The CFD calculations were carried out for an air mass flux G of 1.08, 1.48 and 1.94 kg/sm2bara, which are the high flow rates used for regenerative combustor wall cooling. Comparison of the current CFD predictions and previous CFD work, that have experimental data, were made for the flow pressure loss and the surface and locally X2 average HTC, h. It was concluded that none of the obstacles in the impingement gap a significant increase in the surface averaged heat transfer coefficient (HTC). The impact of the obstacles was to increase the flow maldistribution due to the increased pressure loss. This resulted is less heat transfer from the reduced air mass flow in the first 4 holes and increased heat transfer in the last 4 holes, relative to the smooth wall results. The main effect of the obstacles was to increase the heat transfer to the impingement jet surface. The dimpled surface was predicted to have a very poor performance, with significantly reduced impingement heat transfer. This was due to the impingement jets being deflected away from the target surface by the shape of the dimples and this reduced the surface heat transfer

The Influence of the Relative Number of Impingement and Effusion Cooling Holes on Gas Turbine Combustor Wall Heat Transfer

The optimization of cooling hole geometry for combined impingement and effusion cooling of gas turbine combustors was investigated. The most common design is for there to be equal number of impingement and effusion holes. However, the number of holes is usually set by the requirement of the effusion wall to have good film cooling and a large number of holes is used with small diameter and a low pressure loss or small pitch to diameter ratio, X/D. The impingement wall does not need a large number of holes. This work compared impingement/effusion wall designs with equal number of holes for three hole numbers: 4306/m2, 9688/m2 and 26910/m2. Each of these effusion designs was investigated with a 1076/m2 impingement wall. The internal wall heat transfer for impingement/effusion cooling was measured and predicted using conjugate heat transfer (CHT) computational fluid dynamics (CFD). The work was only concerned with the internal wall heat transfer and not with the effusion film cooling and there was no hot gas crossflow. The CHT/CFD predictions showed good agreement with measured data and the highest number of effusion holes for the 1/25 hole ratio gave the highest hx. However, comparison with the predicted and experimental results for equal number of impingement and effusion holes for the same Z, showed that there was little advantage of decreasing the number of impingement holes, apart from that of decreasing the Z/D significantly for the 1/15 hole ratio, which increased the heat transfer. The largest number of effusion holes had the highest heat transfer due to the greater internal surface area of the holes and their closer spacing

Impingement Heat Transfer: CHT CFD Predictions of the Influence of Reduced Crossflow using Large Gaps.

Experimental and Numerical investigations were carried out on impingement jet cooling, for variable gap to diameter ratio Z/D ranging from 0.76 - 6.42 with varied Z, constant D and constant mass flux G of 1.93 kg/sm2bar, which is typical of G for regenerative backside cooling of gas turbine combustors. This is the cooling geometry relevant to reverse flow cylindrical combustors with low NOx burner where air used for film cooling increases the NOx. The geometries investigated were for 10 × 10 square array of impingement jet cooling holes at constant diameter D and pitch X, hence constant X/D ratio. The experimental results used the lumped capacity method to determine the locally surface average heat transfer with thermocouples spaced at 25.4 mm intervals in the direction of the single exit flow 152.4 mm long impingement gap. The target walls were 6.35 mm thick Nimonic-75 alloy materials that were electrically heated to about 353 K with a coolant air temperature of 288 K. Conjugate heat transfer (CHT) computational fluid dynamics (CFD) were applied to the same geometries. The predicted CFD results agreed with the measured pressure loss, which indicates that the predicted aerodynamics were good. Also, the locally X2 and overall surface average heat transfer coefficients (HTC) h were well predicted, apart from at the lowest Z/D. The pressure loss increased significantly for Z/D <3 and h also increased but this was not a practical design due to the excessive pressure loss

Diversity in Acinetobacter baumannii isolates from paediatric cancer patients in Egypt

Acinetobacter baumannii is an important nosocomial pathogen, commonly causing infections in immunocompromised patients. It is increasingly reported as a multidrug-resistant organism, which is alarming because of its capability to resist all available classes of antibiotics including carbapenems. The aim of this study was to examine the genetic and epidemiological diversity of A. baumannii isolates from paediatric cancer patients in Egypt, by sequencing the intrinsic blaOXA -51-like gene, genotyping by pulsed-field gel electrophoresis and multi-locus sequence typing in addition to identifying the carbapenem-resistance mechanism. Results showed a large diversity within the isolates, with eight different blaOXA -51-like genes, seven novel sequence types and only 28% similarity by pulsed-field gel electrophoresis. All three acquired class-D carbapenemases (OXA-23, OXA-40 and OXA-58) were also identified among these strains correlating with resistance to carbapenems. In addition, we report the first identification of ISAba2 upstream of blaOXA -51-like contributing to high-level carbapenem resistance. This indicates the presence of several clones of A. baumannii in the hospitals and illustrates the large genetic and epidemiological diversity found in Egyptian strains

A Case Study on 21 st Century Skills Development Through a Computer Based Maths Game

International audienceThe new technology developments that are emerging on the market demand re-skilling and updating competencies thus enabling people to adapt to new expectations in the 21st century workplace and life. Therefore, the education system should also prepare learners for lifelong learning through development of 21st century skills. Recent research on mathematics education also shows that for many students, math is not considered an easy subject and students are facing difficulties in developing logical thinking and problem solving skills. This paper introduces "Count With Me!", a novel educational computer based video game that teaches maths concepts. An investigation on how the game supports the development of learners' 21st century skills such as problem solving, self-directed learning, knowledge building and digital literacy is presented. The results of a case study in a 3rd level educational institution show that the large majority of students that took part in the case study acquired 21st century skills. 96.97% of students believed that the Count With Me! game helped them to develop their problem solving skills. 82.82% of students liked self-pacing themselves through the game based educational material. 78.78% of students agreed that the maths game has improved their knowledge and 81.81% of students were satisfied with their achievements in the game