184 research outputs found
A PARTIAL SMR APPROACH TO SMOOTHING AGE-SPECIFIC RATES
No full textPURPOSE: Age-specific rates are the fundamental measures in epidemiology. For a small population, however, rate estimates can become unstable and the age curve may contain too much random variability to adequately assess the true underlying pattern. A further problem arises when one wishes to log-transform a rate with a zero count in its numerator. The author proposes a simple and non-iterative method to stabilize rates. METHODS: The method, referred to as the " partial SMR approach," relies on finding a standard population with a similar age curve with the study population. Real and simulated data were used to demonstrate its properties. RESULTS: It is found that the choice of the standard is not critical. The method will offset automatically the role of a "dissimilar" standard; and according to the limited simulation studies, the result is still better than no smoothing. The method can also smooth the age curve adaptively, i.e., smoothing to varying degree according to internal stability of each age category. The method is asymptotically unbiased and does not have the zero -count problem. Among the various smoothing methods we have studied, the partial SMR smoothing produces the smallest mean square error and has the highest probability of successful capture of the specific pattern and trend in the age curve. CONCLUSIONS: The partial SMR smoothing is a simple and effective method for smoothing age-specific rates
What reactors for Canada: CANDU, SMR?
No full textPrzy spełnieniu pewnych warunków, energetyka jądrowa jest bezpieczniejsza od innych gałęzi przemysłu. Nadzieje związane z bezpieczeństwem i kosztem eksploatacji SMR-ów będą weryfikowane w kolejnych latach, gdy zostanie wybudowana flota małych, modularnych reaktorów. Muszą one następnie przepracować dostateczną ilość godzin w celu uzyskania rzetelnych danych statystycznych na temat ich niezawodności i bezpieczeństwa. W artykule omówiono posunięcia rządów prowincji Ontario i rządu federalnego mające negatywny wpływ na rozwój kanadyjskiej energetyki. Na podstawie kanadyjskiego systemu jądrowego CANDU autor tłumaczy zasadę wielopoziomowego bezpieczeństwa jądrowego.Under certain conditions nuclear power is safer than other branches of industry. Safety and operating costs of SMR’s will need to be verified by statistics after adequate fleet of Small Modular Reactors has been built and operated for sufficient number of hours. Some decisions of provincial and federal governments, detrimental to Canadian power industry have been presented. The author explains how Canadian nuclear system CANDU implements the principle of “defense in depth”
Prati-smr(i)ti in the light of the sciences on forgiveness in Mahabharata
No full textIn the article the author discusses the virtue of forgiveness with which the perfect Brahmin Vasishtha is endowed (Mhbh. I 11, 165 and which is also highly valued by Yudhisthira (Mhbh. III 31, 26-36). Against this background the magic art of prati-smr(i)ti into which Yudhisthira was initiated by Vyasa (Mhbh. III 37, 25-35). An assumption is made that in it is concealed the art of forgiveness
Design and validation of a neurofeedback protocol to assess the effect of the sensorimotor rhythm on reflex modulation
No full textPeople can learn voluntary regulation of certain brain rhythms with help of real-time feedback through a brain-computer interface. Modulation of brain rhythms associated with movement, also known as sensorimotor rhythms (SMR), has shown to alter excitability of the spinal cord. This may indicate a potential role of the SMR in reflex modulation. Until now, no study has assessed the effect of SMR modulation in the mechanically induced stretch reflex. Additionally, inconsistencies in electroencephalography processing for extraction of human intent lead to contradictory results in SMR modulation abilities. In this report, a paradigm is suggested in which people are asked to navigate a virtual cursor to a target with their SMR activity. Once they reach adequate control, mechanical perturbations are applied to their wrist to measure reflex responses. This report summarizes the development and validation of the protocol. Five participants took part in the experiment, four of which successfully acquired control over their SMR. Furthermore, results from one subject suggest that with sufficient modulation of the SMR, changes can be seen in the strength of the stretch reflex. This protocol can be used to further investigate the role of the SMR in reflex modulation, which is useful in the context of rehabilitation of reflex abnormalities. Biomedical Engineerin
CO measurements from the ACE-FTS satellite instrument: data analysis and validation using ground-based, airborne and spaceborne observations
No full textThe Atmospheric Chemistry Experiment (ACE) mission was launched in August 2003 to sound the atmosphere by solar occultation. Carbon monoxide (CO), a good tracer of pollution plumes and atmospheric dynamics, is one of the key species provided by the primary instrument, the ACE-Fourier Transform Spectrometer (ACE-FTS). This instrument performs measurements in both the CO 1-0 and 2-0 ro-vibrational bands, from which vertically resolved CO concentration profiles are retrieved, from the mid-troposphere to the thermosphere. This paper presents an updated description of the ACE-FTS version 2.2 CO data product, along with a comprehensive validation of these profiles using available observations (February 2004 to December 2006). We have compared the CO partial columns with ground-based measurements using Fourier transform infrared spectroscopy and millimeter wave radiometry, and the volume mixing ratio profiles with airborne (both high-altitude balloon flight and airplane) observations. CO satellite observations provided by nadir-looking instruments (MOPITT and TES) as well as limb-viewing remote sensors (MIPAS, SMR and MLS) were also compared with the ACE-FTS CO products. We show that the ACE-FTS measurements provide CO profiles with small retrieval errors (better than 5% from the upper troposphere to 40 km, and better than 10% above). These observations agree well with the correlative measurements, considering the rather loose coincidence criteria in some cases. Based on the validation exercise we assess the following uncertainties to the ACE-FTS measurement data: better than 15% in the upper troposphere (8-12 km), than 30% in the lower stratosphere (12-30 km), and than 25% from 30 to 100 km. © Author(s) 2008.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
Theory of spin Hall magnetoresistance
No full textWe present a theory of the spin Hall magnetoresistance (SMR) in multilayers made from an insulating ferromagnet F, such as yttrium iron garnet (YIG), and a normal metal N with spin-orbit interactions, such as platinum (Pt). The SMR is induced by the simultaneous action of spin Hall and inverse spin Hall effects and therefore a nonequilibrium proximity phenomenon. We compute the SMR in F|N and F|N|F layered systems, treating N by spin-diffusion theory with quantum mechanical boundary conditions at the interfaces in terms of the spin-mixing conductance. Our results explain the experimentally observed spin Hall magnetoresistance in N|F bilayers. For F|N|F spin valves we predict an enhanced SMR amplitude when magnetizations are collinear. The SMR and the spin-transfer torques in these trilayers can be controlled by the magnetic configuration.QN/Quantum NanoscienceApplied Science
Improving ASCAT Soil Moisture Retrievals With an Enhanced Spatially Variable Vegetation Parameterization
No full textThis study investigates the performance of the TU Wien soil moisture retrieval (TUW-SMR) algorithm by adapting the strength of the vegetation correction. The semiempirical change detection method TUW-SMR exploits the multiangle backscatter observations from spaceborne fan-beam scatterometer systems in order to derive surface soil moisture information expressed in the degree of saturation. The vegetation parameterization of TUW-SMR is controlled by the dry and wet crossover angles that are used to determine the dry and wet backscatter reference. Backscatter observations from the Advanced Scatterometer (ASCAT) are used to produce four soil moisture data sets based on different dry and wet crossover angles describing: 1) a static, respectively, no vegetation correction; 2) the currently used seasonal vegetation correction; 3) a stronger seasonal vegetation correction; and 4) a spatially variable seasonal vegetation correction with the stronger vegetation correction over vegetated areas and no vegetation correction over bare land. All four ASCAT soil moisture data sets are evaluated against soil moisture estimates from GLDAS-2.1 Noah land surface model and the European Space Agency (ESA) climate change initiative (CCI) Passive v04.5 soil moisture product using the triple collocation method and traditional correlation analysis. The results show that the spatially variable vegetation correction overall improves soil moisture estimates in both more densely vegetated areas, e.g., in large parts of North America and Europe, and more sparsely vegetated, e.g., Western Africa. Nonetheless, the experiment also provides insight into challenging retrieval conditions where the TUW-SMR fails to take all relevant backscatter processes into account, e.g., wetlands and bare soils with subsurface scattering.Accepted Author ManuscriptMathematical Geodesy and Positionin
Generation IV (very) Small Modular Reactor technology for Future Surface Combatants
No full textNuclear energy has found widespread application in navies across the globe. This thesis explores the potential integration of generation IV (very) Small Modular Reactor (SMR) technology for future surface combatants, focusing on the Very High-Temperature Reactor modelled as vSMR and a Molten Salt Reactor as SMR. The design impact of using generation IV (v)SMR technology for power generation on future surface combatants was unexplored. An estimation of future power and energy requirements and a detailed investigation of the reactor compartment is performed. It includes shielding, power generation, distribution, and conversion systems. Emerging naval-directed energy weapons and advanced sensor technologies are implemented to position the combatant within the spectrum of future mission capabilities.A sizing model evaluates the feasibility of (v)SMR integration in terms of power, energy, volume, and weight. An indication of the available weight for (v)SMR technology is searched by iterating over the displacement of future surface combatants. For the defined future surface combatant, naval SMR power plants are compatible in terms of weight with conventional all-electric gas turbine-driven combatants with displacements above 8,000 tonnes. The model reveals that vSMR technology faces significant challenges related to weight despite its potential benefits in terms of redundancy and modularity. For combatants up to 16,000 tonnes, naval vSMR power plants are not viable due to their substantial weight and space requirements, primarily driven by the need for extensive shielding. Increasing the power output per vSMR reduces the required shielding and provides an alternative solution. A case study explores a preliminary design of a future surface combatant with a displacement of 9,800 tonnes. The study suggests that the propulsion demand significantly impacts the size of the power plant. This results in the need for energy storage systems that manage variable power demands, particularly for SMR technology integrated into large surface combatants. Unlike vSMR naval power plants, SMR technology is comparable in size to the all-electric gas turbine power plant of conventional surface combatants. The study assesses the effectiveness of the preliminary design in terms of survivability, mobility, range and endurance. It is estimated after capability prioritisation that (v)SMR technology and conventional gas turbine configurations have an equivalent survivability impact. A critical trade-off is highlighted between enhanced endurance and range against challenges, such as an increase in weight, volume requirements, and compromises in mobility compared to conventional gas turbine systems. The choice between SMR and vSMR technologies further complicates this balance by choosing between compactness and load response. A essential conclusion is that generation IV (v)SMR technology can enhance a future surface combatant's autonomy and future power load capabilities without compromising its effectiveness. The Royal Netherlands Navy can use the results as an indicative substantiation for developing generation IV (v)SMR-powered future surface combatants. Moreover, it can help initiate a future naval capability plan and contribute to the realisation of generation IV (v)SMR power generation for the maritime sector.Marine Technology | Ship Desig
Recovery and validation of Odin/SMR long-term measurements of mesospheric carbon monoxide
No full textThis is an open access article.-- This work is distributed under
the Creative Commons Attribution 4.0 License.The Sub-Millimetre Radiometer (SMR) on board the Odin satellite performs limb sounding measurements of the middle atmosphere to detect molecular emission from different species. Carbon monoxide (CO) is an important tracer of atmospheric dynamics at these altitudes, due to its long photochemical lifetime and high vertical concentration gradient. In this study, we have successfully recovered over 18 years of SMR observations, providing the only dataset to date being so extended in time and stretching out to the polar regions, with regards to satellite-measured mesospheric CO. This new dataset is part of the Odin/SMR version 3.0 level 2 data. Much of the level 1 dataset - except the October 2003 to October 2004 period - was affected by a malfunctioning of the phase-lock loop (PLL) in the front end used for CO observations. Because of this technical issue, the CO line could be shifted away from its normal frequency location, causing the retrieval to fail or leading to an incorrect estimation of the CO concentration. An algorithm was developed to locate the CO line and shift it to its correct location. Nevertheless, another artefact causing an underestimation of the concentration, i.e. a line broadening, stemmed from the PLL malfunctioning. This was accounted for by using a broader response function. The application of these corrections resulted in the recovery of a large amount of data that was previously being flagged as problematic and therefore not processed. A validation study has been carried out, showing how SMR CO volume mixing ratios are in general in good accordance with the other instruments considered in the study. Overall, the agreement is very good between 60 and 80 km altitude, with relative differences close to zero. A positive bias at low altitudes (50-60 km) up to +20% and a negative bias up to -20% at high altitudes (80-100 km) were found with respect to the comparison instruments. © Author(s) 2020.This research has been supported by the Swedish National Space Agency (grant nos. Dnr 88/14 and Dnr 72/17) and the European Space Agency (Odin reprocessing, MesosphEO grant).Peer reviewe
Uncertainty estimation of spectral matching ratio based power rating of CPV modules
No full textArt. 060001, 7 S.The concentrator standard conditions are defined in the standard IEC 62670-1. Those conditions demand for spectral conditions equivalent to AM1.5d as described in IEC 60904-3. The power output of CPV modules has to be rated at the concentrator standard conditions and thus at AM1.5d spectral irradiance. According to IEC standard 62670-3 the prevailing spectral conditions have to be characterized using spectral matching ratios (SMR). The SMR values have to be within three percent of unity to allow for standardized power ratings. The SMR values are calculated from component cell sensor readings. The most commonly used component cells are based on lattice-matched triple-junction cell structures with bandgaps of 1.9, 1.4 and 0.7 eV. In this work, the usage of these component cells for power ratings on CPV modules equipped with other types of multi-junction cells is investigated. This investigation is based on representative power outputs of CPV modules. These power outputs were calculated using i) the spectral irradiance modeling software SMARTS2, ii) measured external quantum efficiencies and iii) the two-diode model. The outcome of this investigation is an estimation for the measurement uncertainty of rated CPV module power output when using the SMR filtering approach recommended in IEC 62670-3
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