11,362 research outputs found

    Robust automated servicing of passenger train fluids

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    To meet increased capacity demands of passengers in the rail industry, a robotic and autonomous system that services the fluids on passenger rail vehicles was proposed. A hierarchical task analysis of fluid servicing processes was conducted and human and system errors were highlighted. This information, along with opinions of technical managers and staff were inputted into a quality function deployment matrix to make a design specification; from this specification two concepts were proposed. Both concepts are viable but modification to rail vehicles is required. A proof of concept will next be developed to begin a path to a commercial product.Brunel University London would like to acknowledge RSSB and RRUKA for funding this project and providing contact with key rail stakeholders

    First Principles Study of Structural, Electronic and Magnetic Interplay in Ferroelectromagnetic Yttrium Manganite

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    We present results of local spin density approximation pseudopotential calculations for the ferroelectromagnet, yttrium manganite (YMnO3). The origin of the differences between ferroelectric and non-ferroelectric perovskite manganites is determined by comparing the calculated properties of yttrium manganite in its ferroelectric hexagonal and non-ferroelectric orthorhombic phases. In addition, orthorhombic YMnO3 is compared with the prototypical non-ferroelectric manganite, lanthanum manganite. We show that, while the octahedral crystal field splitting of the cubic perovskite structure causes a centro-symmetric Jahn-Teller distortion around the Mn3+ ion, the markedly different splitting in hexagonal perovskites creates an electronic configuration consistent with ferroelectric distortion. We explain the nature of the distortion, and show that a local magnetic moment on the Mn3+ ion is a requirement for it to occur.Comment: Replacement of earlier version with error in pseudopotentia

    Nutritional status of cancer patients in chemotherapy; dietary intake, nitrogen balance and screening

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    To access publisher full text version of this article. Please click on the hyperlink in Additional Links fieldOBJECTIVE: To evaluate a short screening sheet (SSM) for malnutrition and to investigate the nutritional status of patients receiving chemotherapy for cancer of the lungs, colon or breast at an outpatient clinic. DESIGN: Full nutritional assessment was conducted to define malnutrition and validate the SSM. Additionally, weight change from earlier healthy weight was evaluated, and calculations for intake of energy-giving nutrients (three-day-weighed food records) and protein balance were performed. After the evaluation study, the SSM was tested in clinical routine and data collected about patients' need for nutritional counseling. SUBJECTS: Patients at the outpatient clinic of the Department of Oncology at Landspitali-University Hospital (n=30 with lung-, colon- or breast cancer in the study population, n=93 with all cancer type in clinical routine screening). RESULTS: Malnutrition was defined by full nutritional assessment in 20% of the participating patients and SSM had high sensitivity and specificity. Declining nutritional status of the patients was seen as a negative nitrogen balance and unintentional weight loss from healthy weight, but not as total energy intake, recent weight loss or underweight. The test of SSM in clinical routine showed that 40% were malnourished. According to the patients, 80% needed nutritional counseling but only 17% had such counseling. CONCLUSION: Screening (SSM) for malnutrition in cancer patients is a valid simple approach to define cancer patients for nutritional care. More patients regard themselves in need for nutritional counseling than the number of patients really achieving any

    Exploring the acceleration of the Met Office NERC Cloud model using FPGAs

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    The use of Field Programmable Gate Arrays (FPGAs) to accelerate computational kernels has the potential to be of great benefit to scientific codes and the HPC community in general. With the recent developments in FPGA programming technology, the ability to port kernels is becoming far more accessible. However, to gain reasonable performance from this technology it is not enough to simple transfer a code onto the FPGA, instead the algorithm must be rethought and recast in a data-flow style to suit the target architecture. In this paper we describe the porting, via HLS, of one of the most computationally intensive kernels of the Met Office NERC Cloud model (MONC), an atmospheric model used by climate and weather researchers, onto an FPGA. We describe in detail the steps taken to adapt the algorithm to make it suitable for the architecture and the impact this has on kernel performance. Using a PCIe mounted FPGA with on-board DRAM, we consider the integration on this kernel within a larger infrastructure and explore the performance characteristics of our approach in contrast to Intel CPUs that are popular in modern HPC machines, over problem sizes involving very large grids. The result of this work is an experience report detailing the challenges faced and lessons learnt in porting this complex computational kernel to FPGAs, as well as exploring the role that FPGAs can play and their fundamental limits in accelerating traditional HPC workloads.Comment: Preprint of article in proceedings, ISC High Performance 2019. Lecture Notes in Computer Science, vol 1188

    Room temperature plasmon laser by total internal reflection

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    Plasmon lasers create and sustain intense and coherent optical fields below light's diffraction limit with the unique ability to drastically enhance light-matter interactions bringing fundamentally new capabilities to bio-sensing, data storage, photolithography and optical communications. However, these important applications require room temperature operation, which remains a major hurdle. Here, we report a room temperature semiconductor plasmon laser with both strong cavity feedback and optical confinement to 1/20th of the wavelength. The strong feedback arises from total internal reflection of surface plasmons, while the confinement enhances the spontaneous emission rate by up to 20 times.Comment: 8 Page, 2 Figure

    Krill faecal pellets drive hidden pulses of particulate organic carbon in the marginal ice zone

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    The biological carbon pump drives a flux of particulate organic carbon (POC) through the ocean and affects atmospheric levels of carbon dioxide. Short term, episodic flux events are hard to capture with current observational techniques and may thus be underrepresented in POC flux estimates. We model the potential hidden flux of POC originating from Antarctic krill, whose swarming behaviour could result in a major conduit of carbon to depth through their rapid exploitation of phytoplankton blooms and bulk egestion of rapidly sinking faecal pellets (FPs). Our model results suggest a seasonal krill FP export flux of 0.039 GT C across the Southern Ocean marginal ice zone, corresponding to 17–61% (mean 35%) of current satellite-derived export estimates for this zone. The magnitude of our conservatively estimated flux highlights the important role of large, swarming macrozooplankton in POC export and, the need to incorporate such processes more mechanistically to improve model projections

    Probing the ultimate limits of plasmonic enhancement.

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    Metals support surface plasmons at optical wavelengths and have the ability to localize light to subwavelength regions. The field enhancements that occur in these regions set the ultimate limitations on a wide range of nonlinear and quantum optical phenomena. We found that the dominant limiting factor is not the resistive loss of the metal, but rather the intrinsic nonlocality of its dielectric response. A semiclassical model of the electronic response of a metal places strict bounds on the ultimate field enhancement. To demonstrate the accuracy of this model, we studied optical scattering from gold nanoparticles spaced a few angstroms from a gold film. The bounds derived from the models and experiments impose limitations on all nanophotonic systems.Supported by Air Force Office of Scientific Research grant FA9550-09-1-0562 and by the Army Research Office through Multidisciplinary University Research Initiative grant W911NF-09-1-0539. Also supported by the Leverhulme Trust and the Marie Curie Actions (J.B.P., S.A.M., and A.I.F.-D.), NIH grant R21EB009862 (A.C.), and NIH F32 award F32EB009299 (R.T.H.)
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