Interaction of an Eulerian flue gas plume with wind turbines

The reduced availability of sites with the requisite wind resource, planning permission and public acceptance for the placement of wind turbines poses a significant challenge to future expansion of the wind energy industry. Developers increasingly wish to site large turbines in close proximity to industrial plants, but there is uncertainty amongst environmental protection agencies on how best to measure and regulate the impact that wind turbines may have on the dispersion of the gases that are often emitted into the atmosphere from such plants. Several simplified wind turbine-flue stack configurations have been simulated using the Vorticity Transport Model. This model provides a high-fidelity representation of the vortical flow structure within both the wind turbine wake and the plume, and is able to capture the re-direction and dispersion of the plume that occurs due to interaction with the wind turbine. The impingement of the plume on the wind turbine is shown to disrupt the wake structure downwind of the wind turbine, and may induce additional unsteady loading on the turbine rotor. The velocity deficit downwind of the wind turbine influences the rate at which the plume propagates downwind, and results in an increase in the concentration of plume material (which may include pollutant gas and particulates) around the wind turbine. This localized increase in plume concentration is shown to be sensitive to the thrust coefficient at which the wind turbine is operated. The results presented in this paper show that environmental protection agencies are justified in their concerns regarding the placement of wind turbines near to industrial plants, and suggests strongly that the interaction between wind turbines and gas plumes should be investigated further

Assessment of laser cladding as an option for repairing/enhancing rails

This paper presents results of testing carried out to assess the wear and RCF performance of laser clad rail. Stronger and harder materials can be laser clad on top of the working surfaces of standard (e.g. 260 grade) rail in order to improve wear and RCF life. A twin-disc method has been used to assess the suitability of various candidate cladding materials. The materials were clad on top of 260 grade rail discs and were tested against a disc of standard wheel material. Wear was measured by weighing the discs before and after each test. An Ellotest B1 differential eddy current crack detector was used to detect RCF cracks in the rail disc. Four clad materials were used namely, Hadfield, Stellite 6, Maraging and 316 Stainless Steels. In the tests carried out, wear was not always reduced with the cladding. It is assumed that these tests were not long enough for some of the materials to fully work harden and therefore wear rates would improve with a greater number of test cycles. However, all but the Stainless Steel showed that they did not deform under the cyclic loading applied and would offer a greatly enhanced RCF life

Revertant Fibers in the mdx Murine Model of Duchenne Muscular Dystrophy: An Age- and Muscle-Related reappraisal

Muscles in Duchenne dystrophy patients are characterized by the absence of dystrophin, yet transverse sections show a small percentage of fibers (termed “revertant fibers”) positive for dystrophin expression. This phenomenon, whose biological bases have not been fully elucidated, is present also in the murine and canine models of DMD and can confound the evaluation of therapeutic approaches. We analyzed 11 different muscles in a cohort of 40 mdx mice, the most commonly model used in pre-clinical studies, belonging to four age groups; such number of animals allowed us to perform solid ANOVA statistical analysis. We assessed the average number of dystrophin-positive fibers, both absolute and normalized for muscle size, and the correlation between their formation and the ageing process. Our results indicate that various muscles develop different numbers of revertant fibers, with different time trends; besides, they suggest that the biological mechanism(s) behind dystrophin re-expression might not be limited to the early development phases but could actually continue during adulthood. Importantly, such finding was seen also in cardiac muscle, a fact that does not fit into the current hypothesis of the clonal origin of “revertant” myonuclei from satellite cells. This work represents the largest, statistically significant analysis of revertant fibers in mdx mice so far, which can now be used as a reference point for improving the evaluation of therapeutic approaches for DMD. At the same time, it provides new clues about the formation of revertant fibers/cardiomyocytes in dystrophic skeletal and cardiac muscle

Improving rail wear and RCF performance using laser cladding

Laser cladding has been considered as a method for improving the wear and RCF performance of standard grade rail. This paper presents results of small scale tests carried out to assess the wear and RCF performance of rail which had been laser clad. Using the laser cladding process premium metals can be deposited on to the working surface of standard rail with the aim of enhancing the wear and RCF life of the rail. Various laser clad samples were tested using a twin-disc method. The candidate metals were clad on to standard R260 grade rail discs and were tested against a disc of standard wheel material. During the tests, wear rates and RCF initiation were monitored and compared to those of a standard rail disc. Six candidate cladding materials were chosen for this test: A multi-phase Manganese Steel Variant (MMV), Martensitic Stainless Steel (MSS), TWIP Steel, NiCrBSi, Stellite 12 and Stellite 6. The MSS, Stellite 6, and Stellite 12 samples showed reduced wear rates relative to the standard R260 Grade rail discs, and also produced a reduction in wheel steel wear. The RCF initiation resistance of all of the candidate materials was superior compared to the R260 Grade material

A new method for the assessment of traction enhancers and the generation of organic layers in a twin-disc machine

Low adhesion presents a major concern for many rail operators. Railway vehicles under these circumstances can experience a serious loss of braking capability giving rise to dangerous situations such as platform overruns and signals passed at danger. One cause of adhesion loss is autumn leaf fall [1]. Leaves are run over by the wheels of a train and a chemical reaction occurs between the leaf and the rail steel [2]. This forms a black layer on the rail which when wet causes very low friction. These leaf layers have also been shown to be isolating and can interfere with railway signalling systems. Traction enhancers (also referred to in this paper as traction gels) have been developed as an alternative solution to using sand alone. They consist of sand particles suspended in a water based gel and are designed to be delivered to the rail by the trackside or via mobile application systems. The aim of this work was to develop a technique for generating a representative leaf layer on the surface of a twin-disc rail specimen and using this to develop a test methodology for assessing the performance of a traction gel in terms of adhesion recovery, wear and its effect on wheel/rail isolation

Eye-movements reveal attention to social information in autism spectrum disorder

Autism spectrum disorder (ASD) is a neurodevelopmental condition in which children show reduced attention to social aspects of the environment. However in adults with ASD, evidence for social attentional deficits is equivocal. One problem is that many paradigms present social information in an unrealistic, isolated way. This study presented adults and adolescents, with and without ASD, with a complex social scene alongside another, non-social scene, and measured eye-movements during a 3-s viewing period. Analyses first identified viewing time to different regions and then investigated some more complex issues. These were: the location of the very first fixation in a trial (indicating attentional priority); the effect of a task instruction on scan paths; the extent to which gaze-following was evident; and the degree to which participants’ scan paths were influenced by the low-level properties of a scene. Results indicate a superficially normal attentional preference for social information in adults with ASD. However, more sensitive measures show that ASD does entail social attention problems across the lifespan, supporting accounts of the disorder which emphasise lifelong neurodevelopmental atypicalities. These subtle abnormalities may be sufficient to produce serious difficulties in real-life scenarios

Laser cladding of rail; the effects of depositing material on lower rail grades

This paper presents a study comparing the wear performance of laser clad rails. A grade of martensitic stainless steel (MSS) was deposited on two substrate materials: The European standard grade rail steel R260, and a lower grade rail steel R200. A twin-disc method has been used to simulate the contact of wheel and rail under closely controlled conditions. Although cladding on a lesser grade of rail has an effect on the hardness and wear performance of the clad layer (due to dilution), the resulting wear performance of the clad layer assessed using this approach is still vastly improved over R260 material alone

Full-scale testing of laser clad railway track; case study - testing for wear, bend fatigue and insulated block joint lipping integrity

This paper reports on a series of tests which were carried out on full-scale sections of rail that had been treated by laser cladding aiming to create a layer (~1-2mm) of high performance material on the rail head. Experiments were designed to measure wear, lipping of insulated block joints (IBJs) and bending fatigue of clad samples. The wear rate of the clad samples was between 78- 89% lower than that of the standard R260 reference sample. Cladding of either side of an insulated block joint greatly improves its lipping resistance and allows it to withstand approximately 3 times the energy input into the contact compared to a standard un-clad IBJ. A section of rail clad with martensitic stainless steel was subject to bend fatigue testing and ran out to 5,000,000 cycles at a stress range of 350 MPa matching the performance of an unclad R260 rail. Although there is no standard for the bend testing of laser clad rail this performance exceeds the performance requirements of the NR/SP/TRK111 standard which governs the bend testing of flash but welded rail

RHESSI Results -- Time For a Rethink?

Hard X-rays and gamma-rays are the most direct signatures of energetic electrons and ions in the sun's atmosphere which is optically thin at these energies and their radiation involves no coherent processes. Being collisional they are complementary to gyro-radiation in probing atmospheric density as opposed to magnetic field and the electrons are primarily 10--100 keV in energy, complementing the (>100 keV) electrons likely responsible for microwave bursts. The pioneering results of the Ramaty High Energy Solar Spectroscopic Imager (RHESSI) are raising the first new major questions concerning solar energetic particles in many years. Some highlights of these results are discussed -- primarily around RHESSI topics on which the authors have had direct research involvement -- particularly when they are raising the need for re-thinking of entrenched ideas. Results and issues are broadly divided into discoveries in the spatial, temporal and spectral domains, with the main emphasis on flare hard X-rays/fast electrons but touching also on gamma-rays/ions, non-flare emissions, and the relationship to radio bursts.Comment: Proceedings CESRA Workshop 2004: "The High Energy Solar Corona: Waves, Eruptions, Particles", Lecture Notes in Physics, 2006 (accepted

Svestka's Research: Then and Now

Zdenek Svestka's research work influenced many fields of solar physics, especially in the area of flare research. In this article I take five of the areas that particularly interested him and assess them in a "then and now" style. His insights in each case were quite sound, although of course in the modern era we have learned things that he could not readily have envisioned. His own views about his research life have been published recently in this journal, to which he contributed so much, and his memoir contains much additional scientific and personal information (Svestka, 2010).Comment: Invited review for "Solar and Stellar Flares," a conference in honour of Prof. Zden\v{e}k \v{S}vestka, Prague, June 23-27, 2014. This is a contribution to a Topical Issue in Solar Physics, based on the presentations at this meeting (Editors Lyndsay Fletcher and Petr Heinzel