5,467 research outputs found

    Time domain analysis of switching transient fields in high voltage substations

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    Switching operations of circuit breakers and disconnect switches generate transient currents propagating along the substation busbars. At the moment of switching, the busbars temporarily acts as antennae radiating transient electromagnetic fields within the substations. The radiated fields may interfere and disrupt normal operations of electronic equipment used within the substation for measurement, control and communication purposes. Hence there is the need to fully characterise the substation electromagnetic environment as early as the design stage of substation planning and operation to ensure safe operations of the electronic equipment. This paper deals with the computation of transient electromagnetic fields due to switching within a high voltage air-insulated substation (AIS) using the finite difference time domain (FDTD) metho

    An Inductive Sensor for Real Time Measurement of Plantar Normal and Shear Forces Distribution

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    Goal: The objective of this article is to demonstrate a multiplexed inductive force sensor for simultaneously measuring normal force and shear forces on a foot. Methods: The sensor measures the normal force and shear forces by monitoring the inductance changes of three planar sensing coils. Resonance frequency division multiplexing was applied to signals from the multiple sensing coils, making it feasible to simultaneously measure the three forces (normal force, shear forces in x and y axis) on a foot using only one set of measurement electronics with high sensitivity and resolution. Results: The testing results of the prototype sensor have shown that the sensor is capable of measuring normal force ranging from 0 to 800 N and shear forces ranging from 0 to 130 N in real time. Conclusion: With its high resolution, high sensitivity and the capability of monitoring forces at different positions of a foot simultaneously, this sensor can be potentially used for real time measurement of plantar normal force and shear forces distribution on diabetes patient’s foot. Significance: Real time monitoring of the normal force and shear forces on diabetes patient’s foot can provide useful information for physicians and diabetes patients to take actions in preventing foot ulceration

    A Review of Wearable Sensor Systems to Monitor Plantar Loading in the Assessment of Diabetic Foot Ulcers

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    Diabetes is highly prevalent throughout the world and imposes a high economic cost on countries at all income levels. Foot ulceration is one devastating consequence of diabetes, which can lead to amputation and mortality. Clinical assessment of diabetic foot ulcer (DFU) is currently subjective and limited, impeding effective diagnosis, treatment and prevention. Studies have shown that pressure and shear stress at the plantar surface of the foot plays an important role in the development of DFUs. Quantification of these could provide an improved means of assessment of the risk of developing DFUs. However, commercially-available sensing technology can only measure plantar pressures, neglecting shear stresses and thus limiting their clinical utility. Research into new sensor systems which can measure both plantar pressure and shear stresses are thus critical. Our aim in this paper is to provide the reader with an overview of recent advances in plantar pressure and stress sensing and offer insights into future needs in this critical area of healthcare. Firstly, we use current clinical understanding as the basis to define requirements for wearable sensor systems capable of assessing DFU. Secondly, we review the fundamental sensing technologies employed in this field and investigate the capabilities of the resultant wearable systems, including both commercial and research-grade equipment. Finally, we discuss research trends, ongoing challenges and future opportunities for improved sensing technologies to monitor plantar loading in the diabetic foot

    Mars mission solar array Semiannual progress report, period ending 31 Dec. 1969

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    Design and testing of beryllium-structure solar panel for Mars missio

    Ozone Measurements and Transport

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    Ozone intrusions from the stratosphere to the troposphere occur as part of the Brewer-Dobson circulation, but the details of the microphysics of the process are unresolved. This research mainly focuses on near-tropopause regions, and examines stratospheric ozone intrusions into the troposphere across this stable zone. My research objective is to identify the small-scale atmospheric dynamical features responsible for the intrusion of stratospheric ozone into the troposphere, and to determine their relative importance from case to case. Windprofiler radars, together with frequent ozonesonde launches, have been used to detect stratospheric ozone intrusions. This work has been supplemented by numerical simulation via GEM-FLEXPART to unambiguously confirm the leakage. We have identified stratospheric ozone intrusion occurrence at the measurement site, and/or in some cases at some distance from the measurement site. In the latter case, ozone reaches the radar site after being blown horizontally with the wind. We have diagnosed radar measurements of the standard deviation of the vertical wind, vertical shear of the horizontal wind, and turbulence strengths, as possible indicators of small-scale atmospheric activity. Increases in the standard deviation of the vertical wind are considered to indicate enhanced gravity wave activity, and enhancements in wind shear are taken to indicate increases in small-scale dynamics (including gravity wave activity). The study shows frequent strong correlation between intrusion events and strong atmospheric activity. The atmospheric dynamics responsible for the intrusion of stratospheric ozone varies from case to case. On the one hand, we see that all parameters can act simultaneously, which clearly amplifies the intrusions. On the other hand, we see either one or any combination of the parameters acting to cause intrusions. However, the Eureka 2008 and Montreal 2005 (on 9th May) campaigns are exceptional cases where we do not see any strong atmospheric activity. We have also modeled atmospheric diffusion and examined the differences due to homogeneous turbulence compared with turbulence that is spatially and temporally intermittent. This unique combination of observational and numerical modeling helps detect the sources and sinks of ozone-related atmospheric pollutants that have negative impact on air quality, climate change and ozone depletion

    Capability of the FPS-16 radar/jimsphere system for direct measurement of vertical air motions

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    Capability and procedure for direct measurement of vertical air currents using FPS-16 radar/ jimsphere syste

    RRS Discovery Cruise 381, 28 Aug - 03 Oct 2012. Ocean Surface Mixing, Ocean Submesoscale Interaction Study (OSMOSIS)

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    Cruise D381 was made in support of NERC's Ocean Surface Boundary Layer theme action programme, OSMOSIS (Ocean Surface Mixing, Ocean Sub-mesoscale Interaction Study). The ocean surface boundary layer (OSBL) deepens in response to convective, wind and surface wave forcing, which produce three-dimensional turbulence that entrains denser water, deepening the layer. The OSBL shoals in response to solar heating and to mesoscale and sub-mesoscale motions that adjust lateral buoyancy gradients into vertical stratification. Recent and ongoing work is revolutionising our view of both the deepening and shoaling processes: new processes are coming into focus that are not currently recognised in model parameterisation schemes. In OSMOSIS we have a project which integrates observations, modelling studies and parameterisation development to deliver a step change in modelling of the OSBL. The OSMOSIS overall aim is to develop new, physically based and observationally supported, parameterisations of processes that deepen and shoal the OSBL, and to implement and evaluate these parameterisations in a state-of-the-art global coupled climate model, facilitating improved weather and climate predictions. Cruise D381 was split into two legs D381A and a process study cruise D381B. D381A partly deployed the OSMOSIS mooring array and two gliders for long term observations near the Porcupine Abyssal Plain Observatory. D381B firstly completed mooring and glider deployment work begun during the preceding D381A cruise. D381B then carried out several days of targetted turbulence profiling looking at changes in turbulent energy dissipation resulting from the interation of upper ocean fluid structures such as eddies, sub-mesoscale filaments and Langmuir cells with surface wind and current shear. Finally D381B conducted two spatial surveys with the towed SeaSoar vehicle to map and diagnose the mesoscale and sub-mesoscale flows, which, unusually, are the `large scale' background in which this study sits

    RRS Discovery Cruise 381, 28 Aug - 03 Oct 2012. Ocean Surface Mixing, Ocean Submesoscale Interaction Study (OSMOSIS)

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    Cruise D381 was made in support of NERC's Ocean Surface Boundary Layer theme action programme, OSMOSIS (Ocean Surface Mixing, Ocean Sub-mesoscale Interaction Study). The ocean surface boundary layer (OSBL) deepens in response to convective, wind and surface wave forcing, which produce three-dimensional turbulence that entrains denser water, deepening the layer. The OSBL shoals in response to solar heating and to mesoscale and sub-mesoscale motions that adjust lateral buoyancy gradients into vertical stratification. Recent and ongoing work is revolutionising our view of both the deepening and shoaling processes: new processes are coming into focus that are not currently recognised in model parameterisation schemes. In OSMOSIS we have a project which integrates observations, modelling studies and parameterisation development to deliver a step change in modelling of the OSBL. The OSMOSIS overall aim is to develop new, physically based and observationally supported, parameterisations of processes that deepen and shoal the OSBL, and to implement and evaluate these parameterisations in a state-of-the-art global coupled climate model, facilitating improved weather and climate predictions. Cruise D381 was split into two legs D381A and a process study cruise D381B. D381A partly deployed the OSMOSIS mooring array and two gliders for long term observations near the Porcupine Abyssal Plain Observatory. D381B firstly completed mooring and glider deployment work begun during the preceding D381A cruise. D381B then carried out several days of targetted turbulence profiling looking at changes in turbulent energy dissipation resulting from the interation of upper ocean fluid structures such as eddies, sub-mesoscale filaments and Langmuir cells with surface wind and current shear. Finally D381B conducted two spatial surveys with the towed SeaSoar vehicle to map and diagnose the mesoscale and sub-mesoscale flows, which, unusually, are the `large scale' background in which this study sits

    Viking '75 spacecraft design and test summary. Volume 1: Lander design

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    The Viking Mars program is summarized. The design of the Viking lander spacecraft is described
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