129 research outputs found
The gravity-related decoherence master equation from hybrid dynamics
Canonical coupling between classical and quantum systems cannot result in
reversible equations, rather it leads to irreversible master equations.
Coupling of quantized non-relativistic matter to gravity is illustrated by a
simplistic example. The heuristic derivation yields the theory of
gravity-related decoherence proposed longtime ago by Penrose and the author.Comment: 9pp, extended version of invited talk at Fifth International Workshop
DICE2010 (Castello Pasquini/Castiglioncello/Tuscany, Sept. 13-17, 2010
Equivalent circuit and calculation of unbalanced power in three-wire three-phase linear networks
[EN] For analysis of three-wire three-phase linear systems, the transformations wye-delta and delta-wye from theorem of Kennelly are used. These transformations can be applied to balanced systems but not to unbalanced systems. This is due to the fact that zero-sequence voltages or zero-sequence currents are present in these types of connections. This modifies the value of the unbalance power in the load with respect to the generator. These zero-sequence voltages and currents that appear in generators and loads are not transferred over the network. The zero-sequence voltage in a delta-connected load and the zero-sequence current that is obtained using theorem of Kennelly in a star-connected load, or vice versa, cause different imbalance effects. Here, the equivalent circuit for any point of the system is developed. The impedances of the equivalent circuit in any node are calculated using line-to-line voltages and line currents. This equivalent circuit incorporates all energetic phenomena, including the unbalance of all downstream loads. For its verification, the phasor unbalance power is used.Montoya-Mira, R.; Diez-Aznar, J.; Blasco Espinosa, PA.; Montoya Villena, R. (2018). Equivalent circuit and calculation of unbalanced power in three-wire three-phase linear networks. IET Generation Transmission & Distribution. 12(7):1466-1473. https://doi.org/10.1049/iet-gtd.2017.0670S14661473127Emanuel, A. E. (1993). On the definition of power factor and apparent power in unbalanced polyphase circuits with sinusoidal voltage and currents. IEEE Transactions on Power Delivery, 8(3), 841-852. doi:10.1109/61.252612Jeon, S.-J. (2005). Definitions of Apparent Power and Power Factor in a Power System Having Transmission Lines With Unequal Resistances. IEEE Transactions on Power Delivery, 20(3), 1806-1811. doi:10.1109/tpwrd.2005.848658Czarnecki, L. S. (1994). Misinterpretations of some power properties of electric circuits. IEEE Transactions on Power Delivery, 9(4), 1760-1769. doi:10.1109/61.329509Willems, J. L. (2004). Reflections on Apparent Power and Power Factor in Nonsinusoidal and Polyphase Situations. IEEE Transactions on Power Delivery, 19(2), 835-840. doi:10.1109/tpwrd.2003.823182Emanuel, A. E. (1999). Apparent power definitions for three-phase systems. IEEE Transactions on Power Delivery, 14(3), 767-772. doi:10.1109/61.772313Jayatunga, U., Ciufo, P., Perera, S., & Agalgaonkar, A. P. (2015). Deterministic methodologies for the quantification of voltage unbalance propagation in radial and interconnected networks. IET Generation, Transmission & Distribution, 9(11), 1069-1076. doi:10.1049/iet-gtd.2014.0661Von Jouanne, A., & Banerjee, B. (2001). Assessment of voltage unbalance. IEEE Transactions on Power Delivery, 16(4), 782-790. doi:10.1109/61.956770Viswanadha Raju, G. K., & Bijwe, P. R. (2008). Efficient reconfiguration of balanced and unbalanced distribution systems for loss minimisation. IET Generation, Transmission & Distribution, 2(1), 7. doi:10.1049/iet-gtd:20070216Kersting, W. H. (2001). Causes and effects of unbalanced voltages serving an induction motor. IEEE Transactions on Industry Applications, 37(1), 165-170. doi:10.1109/28.903142Pillay, P., & Manyage, M. (2006). Loss of Life in Induction Machines Operating With Unbalanced Supplies. IEEE Transactions on Energy Conversion, 21(4), 813-822. doi:10.1109/tec.2005.853724Emanuel, A. E. (1998). The Buchholz-Goodhue apparent power definition: the practical approach for nonsinusoidal and unbalanced systems. IEEE Transactions on Power Delivery, 13(2), 344-350. doi:10.1109/61.660900Leon-Martinez, V., Montanana-Romeu, J., & Palazon-Garcia, J. M. (2011). Unbalance Compensator for Three-Phase Industrial Installations. IEEE Latin America Transactions, 9(5), 808-814. doi:10.1109/tla.2011.6030993Reginatto, R., & Ramos, R. A. (2014). On electrical power evaluation in dq coordinates under sinusoidal unbalanced conditions. IET Generation, Transmission & Distribution, 8(5), 976-982. doi:10.1049/iet-gtd.2013.0532Diez, J. M., Blasco, P. A., & Montoya, R. (2016). Formulation of phasor unbalance power: application to sinusoidal power systems. IET Generation, Transmission & Distribution, 10(16), 4178-4186. doi:10.1049/iet-gtd.2016.0730Marzband, M., Moghaddam, M. M., Akorede, M. F., & Khomeyrani, G. (2016). Adaptive load shedding scheme for frequency stability enhancement in microgrids. Electric Power Systems Research, 140, 78-86. doi:10.1016/j.epsr.2016.06.03
Direction distributions of neutrons and reference values of the personal dose equivalent in workplace fields
Within the EC project EVIDOS, double-differential (energy and direction) fluence spectra were determined by means of novel direction spectrometers. By folding the spectra with fluence-to-dose equivalent conversion coefficients, contributions to H*(10) for 14 directions, and values of the personal dose equivalent Hp(10) and the effective dose E for 6 directions of a person's orientation in the field were determined. The results of the measurements and calculations obtained within the EVIDOS project in workplace fields in nuclear installations in Europe, i.e., at Krümmel (boiling water reactor and transport cask), at Mol (Venus research reactor and fuel facility Belgonucléaire) and at Ringhals (pressurised reactor and transport cask) are presente
Characterisation of mixed neutron-photon workplace fields at nuclear facilities by spectrometry (energy and direction) within the EVIDOS project
Within the EC project EVIDOS, 17 different mixed neutron-photon workplace fields at nuclear facilities (boiling water reactor, pressurised water reactor, research reactor, fuel processing, storage of spent fuel) were characterised using conventional Bonner sphere spectrometry and newly developed direction spectrometers. The results of the analysis, using Bayesian parameter estimation methods and different unfolding codes, some of them especially adapted to simultaneously unfold energy and direction distributions of the neutron fluence, showed that neutron spectra differed strongly at the different places, both in energy and direction distribution. The implication of the results for the determination of reference values for radiation protection quantities (ambient dose equivalent, personal dose equivalent and effective dose) and the related uncertainties are discusse
Individual neutron monitoring in workplaces with mixed neutron/photon radiation
EVIDOS (‘evaluation of individual dosimetry in mixed neutron and photon radiation fields') is an European Commission (EC)-sponsored project that aims at a significant improvement of radiation protection dosimetry in mixed neutron/photon fields via spectrometric and dosimetric investigations in representative workplaces of the nuclear industry. In particular, new spectrometry methods are developed that provide the energy and direction distribution of the neutron fluence from which the reference dosimetric quantities are derived and compared to the readings of dosemeters. The final results of the project will be a comprehensive set of spectrometric and dosimetric data for the workplaces and an analysis of the performance of dosemeters, including novel electronic dosemeters. This paper gives an overview of the project and focuses on the results from measurements performed in calibration fields with broad energy distributions (simulated workplace fields) and on the first results from workplaces in the nuclear industry, inside a boiling water reactor and around a spent fuel transport cas
Achievements in workplace neutron dosimetry in the last decade: lessons learned from the EVIDOS project
The availability of active neutron personal dosemeters has made real time monitoring of neutron doses possible. This has obvious benefits, but is only of any real assistance if the dose assessments made are of sufficient accuracy and reliability. Preliminary assessments of the performance of active neutron dosemeters can be made in calibration facilities, but these can never replicate the conditions under which the dosemeter is used in the workplace. Consequently, it is necessary to assess their performance in the workplace, which requires the field in the workplace to be fully characterised in terms of the energy and direction dependence of the fluence. This paper presents an overview of developments in workplace neutron dosimetry but concentrates on the outcomes of the EVIDOS project, which has made significant advances in the characterisation of workplace fields and the analysis of dosemeter responses in those field
Evaluation of individual dosimetry in mixed neutron and photon radiation fields (EVIDOS). Part II: conclusions and recommendations
The paper presents the main conclusions and recommendations derived from the EVIDOS project, which is supported by the European Commission within the 5th Framework Programme. EVIDOS aims at evaluating state of the art neutron dosimetry techniques in representative workplaces of the nuclear industry with complex mixed neutron-photon radiation fields. This analysis complements a series of individual papers which present detailed results and it summarises the main findings from a practical point of view. Conclusions and recommendations are given concerning characterisation of radiation fields, methods to derive radiation protection quantities and dosemeter result
Evaluation of individual dosimetry in mixed neutron and photon radiation fields (EVIDOS). Part I: scope and methods of the project
Supported by the European Commission, the EVIDOS project started in November 2001 with the broad goal of evaluating state of the art dosimetry techniques in representative workplaces of the nuclear industry. Seven European institutes joined efforts with end users at nuclear power plants, at fuel processing and reprocessing plants, and at transport and storage facilities. A comprehensive programme was devised to evaluate capabilities and limitations of standard and innovative personal dosemeters in relation to the mixed neutron-photon fields of concern to the nuclear industry. This paper describes the criteria behind the selection of dosimetry techniques and workplaces that were analysed, as well as the organisation of the measurement campaigns. Particular emphasis was placed on the evaluation of a variety of electronic personal dosemeters, either commercially available or previously developed by the partners. The estimates provided by these personal dosemeters were compared to reference values of dose equivalent quantities derived from spectrometry and fluence-to-dose equivalent conversion coefficients. Spectrometry was performed both with conventional multisphere and with some original instrumentation providing energy and direction resolution, based on silicon detectors and superheated drop detectors mounted on or in spherical moderators. The results were collected in a large, searchable database and are intended to be used in the harmonisation of dosimetric procedures for mixed radiation fields and for the approval of dosimetry services in Europ
Application of workplace correction factors to dosemeter results for the assessment of personal doses at nuclear facilities
Ratios of Hp(10) and H*(10) were determined with reference instruments in a number of workplace fields within the nuclear industry and used to derive workplace-specific correction factors. When commercial survey meter results together with these factors were applied to the results of the locally used personal dosemeters their results improved and became within 0.7 and 1.7 of the reference values or better depending on the response of the survey meter. A similar result was obtained when a correction was determined with a prototype reference instrument for Hp(10) after adjustment of its response. Commercially available survey instruments both for photon and neutron H*(10) measurements agreed with the reference instruments in most cases to within 0.5-1.5. Those conclusions are derived from results reported within the EC supported EVIDOS contrac
Summary of personal neutron dosemeter results obtained within the EVIDOS project
Within the EC project EVIDOS (‘Evaluation of Individual Dosimetry in Mixed Neutron and Photon Radiation Fields'), different types of active neutron personal dosemeters (and some passive ones) were tested in workplace fields at nuclear installations in Europe. The results of the measurements which have been performed up to now are summarised and compared to our currently best estimates of the personal dose equivalent Hp(10). Under- and over-readings by more than a factor of two for the same dosemeter in different workplace fields indicate that in most cases the use of field-specific correction factors is require
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