scispace - formally typeset
Search or ask a question
Book ChapterDOI

International Electrotechnical Commission

01 Jan 2010-pp 573-584
TL;DR: The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes international standards for all electrical, electronic, and related technologies as mentioned in this paper, and through its members known as National Committees (NC), the IEC promotes international cooperation on all questions of electrotechnically standardization and related matters.
Abstract: The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes international standards for all electrical, electronic, and related technologies. Through its members, known as National Committees (NC), the IEC promotes international cooperation on all questions of electrotechnical standardization and related matters. The supreme authority of the IEC is the Council, which is the general assembly of the National Committees, who are the Commission's members. The IEC also comprises management, executive and advisory bodies, and Officers. Dues are determined according to a formula approved by Council and which takes into account the country's per capita GNP and electricity consumption. The Commission's objectives are to contribute to the improvement of human health and safety and to the protection of the environment. The main trends that have helped the IEC to become the world's authority for electrotechnical standards are Global Industrialization and Technology transfer. Keywords: electrotechnical standards; executive bodies; global industrialization; GNP; International Electrotechnical Commission (IEC); National Committees (NC)
Citations
More filters
Journal ArticleDOI
TL;DR: Expected skin reactions for an average patient are presented in tabular form as a function of peak skin dose and time after irradiation, and the variability of reactions in different patients is indicated.
Abstract: This review presents a consensus, based on available information, on the radiobiology of the skin and the relationship between radiation dose and skin effects in interventional fluoroscopy.

490 citations

Journal ArticleDOI
TL;DR: Differences in estimates of effective dose suggest the need to reassess DLP to E conversion coefficients when adopting ICRP 103, particularly for scans over the breast.
Abstract: OBJECTIVE. The objective of our study was to compare dose–length product (DLP)–based estimates of effective dose with organ dose–based calculations using tissue-weighting factors from publication 103 of the International Commission on Radiological Protection (ICRP) or dual-energy CT protocols.MATERIALS AND METHODS. Using scanner- and energy-dependent organ dose coefficients, we calculated effective doses for CT examinations of the head, chest, coronary arteries, liver, and abdomen and pelvis using routine clinical single- or dual-energy protocols and tissue-weighting factors published in 1991 in ICRP publication 60 and in 2007 in ICRP publication 103. Effective doses were also generated from the respective DLPs using published conversion coefficients that depend only on body region. For each examination type, the same volume CT dose index was used for single- and dual-energy scans.RESULTS. Effective doses calculated for CT examinations using organ dose estimates and ICRP 103 tissue-weighting factors diffe...

428 citations

Journal ArticleDOI
01 Aug 2008
TL;DR: This work proposes a tone mapping operator that can minimize visible contrast distortions for a range of output devices, ranging from e-paper to HDR displays, and shows that the problem can be solved very efficiently by employing higher order image statistics and quadratic programming.
Abstract: We propose a tone mapping operator that can minimize visible contrast distortions for a range of output devices, ranging from e-paper to HDR displays. The operator weights contrast distortions according to their visibility predicted by the model of the human visual system. The distortions are minimized given a display model that enforces constraints on the solution. We show that the problem can be solved very efficiently by employing higher order image statistics and quadratic programming. Our tone mapping technique can adjust image or video content for optimum contrast visibility taking into account ambient illumination and display characteristics. We discuss the differences between our method and previous approaches to the tone mapping problem.

410 citations

Journal ArticleDOI
TL;DR: The photovoltaics (PV) area is rapidly evolving based on new materials and deposition approaches as discussed by the authors, which is a leading contender for next-generation green power production.
Abstract: The direct conversion of solar energy to electricity by photovoltaic cells or thermal energy in concentrated solar power systems is emerging as a leading contender for next-generation green power production. The photovoltaics (PV) area is rapidly evolving based on new materials and deposition approaches. At present, PV is predominately based on crystalline and polycrystalline Si and is growing at >40% per year with production rapidly approaching 3 gigawatts/year with PV installations supplying <1% of energy used in the world. Increased cell efficiency and reduced manufacturing expenses are critical in achieving reasonable costs for PV and solarthermal. CdTe thin-film solar cells have reported a manufactured cost of $1.25/watt. There is also the promise of increased efficiency by use of multijunction cells or hybrid devices organized at the nanoscale. This could lead to conversion efficiencies of greater than 50%. Solar energy conversion increasingly represents one of the largest new businesses currently emerging in any sector of the economy.

319 citations

01 Jan 2009
TL;DR: In this article, a 3D Navier-Stokes computational study of the wake characteristics of wind turbines operating in various flow conditions including interacting wakes between a row of turbines is presented.
Abstract: This thesis contains a comprehensive 3D Navier-Stokes computational study of the characteristics of wakes of wind turbines operating in various flow conditions including interacting wakes between a row of turbines. The computations were carried out using the actuator line technique combined with the 3D Navier Stokes solver EllipSys3D and a LES turbulence model. Simple models, based on applying body forces in the computational domain, are developed for imposing sheared and turbulent inflow and their validity is discussed. A few computations on stand alone turbines are compared to measurements and good to fair agreement are shown in terms of respectively power coefficient and mean wake properties. The turbulence properties in the wake are generally characterized by its spectral characteristics and include estimation of spectral coherence, length scales and Reynolds stresses. Simulations of the wake from an isolated turbine operating in uniform inflow at tip-speed ratios ranging from λ = 3.21 to λ = 11.78 is presented and provides detailed information about the wake development including vortex properties and turbulence characteristics. Calculations on the wake of turbines subject to sheared inflow shows that besides an expected vertical skewed wake the wake also becomes increasingly asymmetric in the horizontal direction as it is convected downstream. The latter phenomena, which is also often observed in measurements, is argued to be caused by the rotation of the wake. A detailed study is presented to investigate the influence of including turbulence in the inflow. The study shows that the ambient turbulence causes the vortex system in the wake to become unstable much closer to the rotor and as a consequence the wake becomes fully turbulent earlier than if inflow turbulence is neglected. Furthermore, it is shown that the main effect governing the large scale meandering of wakes is the large scale structures of the ambient turbulence field. Finally studies are conducted on rows of respectively two and three turbines. The investigation includes evaluation of the loading on the rotors and it is shown that the turbines are subject to rather severe yaw moments, even in situations where the mean wind is oriented along the row. This observation is indicative of large scale dynamics of the wakes.

284 citations