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Journal articles on the topic 'Polarisation'

Author: Grafiati

Published: 4 June 2021

Last updated: 6 July 2024

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1

Gusarov, Andrei, Perry Beaumont, and Paula Siren. "Performance Enhancement of the Polarimetric Fibre Optical Current Sensor at JET Using Polarisation Optimisation." Sensors 24, no. 2 (January 16, 2024): 555. http://dx.doi.org/10.3390/s24020555.

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To achieve optimal operation of the polarimetry-based FOCS, the light polarisation state at the input of the sensing fibre part must be close to a linear one. In the case of a FOCS deployed on a tokamak, the Joint European Torus (JET) in the present work, the long fibre optics link between the laser source and the sensing fibre modifies the polarisation in an unpredictable way, making it unclear which source polarisation state is to be set. A method for performing the necessary polarisation adjustment in a systematic way is proposed based on the FOCS analysis. The method requires performing data acquisition at two different input polarisations. Based on these measurements, the optimal laser source polarisation can be found. The method was experimentally verified using laboratory set-up and then successfully demonstrated with the FOCS installed at JET.

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2

Bogdanov, S. A., O. S. Sidelnikov, and A. A. Redyuk. "Application of complex fully connected neural networks to compensate for nonlinearity in fibre-optic communication lines with polarisation division multiplexing." Quantum Electronics 51, no. 12 (December 1, 2021): 1076–80. http://dx.doi.org/10.1070/qel17656.

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Abstract A scheme is proposed to compensate for nonlinear distortions in extended fibre-optic communication lines with polarisation division multiplexing, based on fully connected neural networks with complex-valued arithmetic. The activation function of the developed scheme makes it possible to take into account the nonlinear interaction of signals from different polarisation components. This scheme is compared with a linear one and a neural network that processes signals of different polarisations independently, and the superiority of the proposed neural network architecture is demonstrated.

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3

O'Brien, D. M., I. N. Polonsky, and J. B. Kumer. "Sensitivity of remotely sensed trace gas concentrations to polarisation." Atmospheric Measurement Techniques 8, no. 11 (November 23, 2015): 4917–30. http://dx.doi.org/10.5194/amt-8-4917-2015.

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Abstract. Current and proposed space missions estimate column-averaged concentrations of trace gases (CO2, CH4 and CO) from high resolution spectra of reflected sunlight in absorption bands of the gases. The radiance leaving the top of the atmosphere is partially polarised by both reflection at the surface and scattering within the atmosphere. Generally, the polarisation state is unknown and could degrade the accuracy of the concentration measurements. The sensitivity to polarisation is modelled for the proposed geoCARB instrument, which will include neither polarisers nor polarisation scramblers to select particular polarisation states from the incident radiation. The radiometric and polarimetric calibrations proposed for geoCARB are outlined, and a model is developed for the polarisation properties of the geoCARB spectrographs. This model depends principally upon the efficiencies of the gratings to polarisations parallel and perpendicular to the rulings of the gratings. Next, an ensemble of polarised spectra is simulated for geoCARB observing targets in India, China and Australia from geostationary orbit at longitude 110° E. The spectra are analysed to recover the trace gas concentrations in two modes, the first denied access to the polarimetric calibration and the second with access. The retrieved concentrations using the calibration data are almost identical to those that would be obtained with polarisation scramblers, while the retrievals without calibration data contain outliers that do not meet the accuracies demanded by the mission.

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4

O'Brien, D. M., I. N. Polonsky, and J. B. Kumer. "Sensitivity of remotely-sensed trace gas concentrations to polarisation." Atmospheric Measurement Techniques Discussions 8, no. 8 (August 24, 2015): 8779–816. http://dx.doi.org/10.5194/amtd-8-8779-2015.

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Abstract. Current and proposed space missions estimate column-averaged concentrations of trace gases (CO2, CH4 and CO) from high resolution spectra of reflected sunlight in absorption bands of the gases. The radiance leaving the top of the atmosphere is partially polarised by both reflection at the surface and scattering within the atmosphere. Generally the polarisation state is unknown, and could degrade the accuracy of the concentration measurements. The sensitivity to polarisation is modelled for the proposed geoCARB instrument, which will include neither polarisers nor polarisation scramblers to select particular polarisation states from the incident radiation. The radiometric and polarimetric calibrations proposed for geoCARB are outlined, and a model is developed for the polarisation properties of the geoCARB spectrographs. This model depends principally upon the efficiencies of the gratings to polarisations parallel and perpendicular to the rulings of the gratings. Next an ensemble of polarised spectra is simulated for geoCARB observing targets in India, China and Australia from geostationary orbit at longitude 110° E. The spectra are analysed to recover the trace gas concentrations in two modes, the first denied access to the polarimetric calibration and the second with access. The retrieved concentrations using the calibration data are almost identical to those that would be obtained with polarisation scramblers, while the retrievals without calibration data contain outliers that do not meet the accuracies demanded by the mission.

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5

Piltyay, Stepan, Andrew Bulashenko, Hanna Kushnir, and Oleksandr Bulashenko. "Information Resources Economy in Satellite Systems based on New Microwave Polarizers with Tunable Posts." Path of Science 6, no. 11 (November 30, 2020): 5001–10. http://dx.doi.org/10.22178/pos.64-6.

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One of the fundamental problems of modern digital telecommunications is the economy of digital information and frequency resources, which are highly limited. The introduction of novel telecommunication systems and 5G networks requires searching for principal solutions for the economy and reusing the frequency spectrum. Therefore, modern wireless mobile, terrestrial, and satellite systems use various new technologies to increase communication channels' information capacity for the economy of limited frequency resources. One of the most effective ways to reuse the information system's operating frequency band is to apply antennas with polarisation signal processing. Such systems provide the possibility to transmit and to receive simultaneously signals with different types of polarisation. Consequently, the application of electromagnetic waves with two orthogonal polarisations improves wireless systems' information characteristics for various purposes. This allows doubling the information capacity of mobile, terrestrial, and satellite communication channels. Also, polarisation processing is carried out in meteorological and radar systems to receive, transmit, and process information. The essential elements of such systems are microwave polarisers and orthomode transducers. The electromagnetic characteristics of these devices affect the aspects of the whole system significantly. Main electromagnetic factors include phase, matching, and polarisation parameters. The article presents the development of a compact tunable polarizer based on a square waveguide with three posts. The developed polariser operates in the X-band from 8.0 GHz to 8.5 GHz. Created a mathematical model of the polariser is based on the scattering and transmission matrices. To verify the developed theoretical model's correctness, the calculation of all characteristics was also performed numerically using the finite integration technique. The developed compact polariser based on a square waveguide with three posts allows tuning it's matching and polarisation characteristics by changing all posts' heights. The developed polariser's main advantages are small dimensions, tuning options, and aspects of polarisation transformation.

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6

Prabhu, A., A. Brandenburg, M. J. Käpylä, and A. Lagg. "Helicity proxies from linear polarisation of solar active regions." Astronomy & Astrophysics 641 (September 2020): A46. http://dx.doi.org/10.1051/0004-6361/202037614.

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Context. The α effect is believed to play a key role in the generation of the solar magnetic field. A fundamental test for its significance in the solar dynamo is to look for magnetic helicity of opposite signs both between the two hemispheres as well as between small and large scales. However, measuring magnetic helicity is compromised by the inability to fully infer the magnetic field vector from observations of solar spectra, caused by what is known as the π ambiguity of spectropolarimetric observations. Aims. We decompose linear polarisation into parity-even and parity-odd E and B polarisations, which are not affected by the π ambiguity. Furthermore, we study whether the correlations of spatial Fourier spectra of B and parity-even quantities such as E or temperature T are a robust proxy for magnetic helicity of solar magnetic fields. Methods. We analysed polarisation measurements of active regions observed by the Helioseismic and Magnetic Imager on board the Solar Dynamics observatory. Theory predicts the magnetic helicity of active regions to have, statistically, opposite signs in the two hemispheres. We then computed the parity-odd EB and TB correlations and tested for a systematic preference of their sign based on the hemisphere of the active regions. Results. We find that: (i) EB and TB correlations are a reliable proxy for magnetic helicity, when computed from linear polarisation measurements away from spectral line cores; and (ii) E polarisation reverses its sign close to the line core. Our analysis reveals that Faraday rotation does not have a significant influence on the computed parity-odd correlations. Conclusions. The EB decomposition of linear polarisation appears to be a good proxy for magnetic helicity independent of the π ambiguity. This allows us to routinely infer magnetic helicity directly from polarisation measurements.

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7

Eriksson, P., B. Rydberg, and S. A. Buehler. "On cloud ice induced absorption and polarisation effects in microwave limb sounding." Atmospheric Measurement Techniques 4, no. 6 (June 30, 2011): 1305–18. http://dx.doi.org/10.5194/amt-4-1305-2011.

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Abstract. Microwave limb sounding in the presence of ice clouds was studied by detailed simulations, where clouds and other atmospheric variables varied in three dimensions and the full polarisation state was considered. Scattering particles were assumed to be horizontally aligned oblate spheroids with a size distribution parameterized in terms of temperature and ice water content. A general finding was that particle absorption is significant for limb sounding, which is in contrast to the down-looking case, where it is usually insignificant. Another general finding was that single scattering can be assumed for cloud optical paths below about 0.1, which is thus an important threshold with respect to the complexity and accuracy of retrieval algorithms. The representation of particle sizes during the retrieval is also discussed. Concerning polarisation, specific findings were as follows: Firstly, no significant degree of circular polarisation was found for the considered particle type. Secondly, for the ±45° polarisation components, differences of up to 4 K in brightness temperature were found, but differences were much smaller when single scattering conditions applied. Thirdly, the vertically polarised component has the smallest cloud extinction. An important goal of the study was to derive recommendations for future limb sounding instruments, particularly concerning their polarisation setup. If ice water content is among the retrieval targets (and not just trace gas mixing ratios), then the simulations show that it should be best to observe any of the ±45° and circularly polarised components. These pairs of orthogonal components also make it easier to combine information measured from different positions and with different polarisations.

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8

Ferré, Vincent. "Macronisme, polarisation sociale et polarisation politique." Commentaire Numéro169, no. 1 (2020): 215. http://dx.doi.org/10.3917/comm.169.0215.

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9

Hodgkinson, T. G., R. A. Harmon, and D. W. Smith. "Polarisation-insensitive heterodyne detection using polarisation scrambling." Electronics Letters 23, no. 10 (May 7, 1987): 513–14. http://dx.doi.org/10.1049/el:19870371.

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10

Heismann, F., P. B. Hansen, S. K. Korotky, G. Raybon, J. J. Veselka, and M. S. Whalen. "Automatic polarisation demultiplexer polarisation-multiplexed transmission systems." Electronics Letters 29, no. 22 (1993): 1965. http://dx.doi.org/10.1049/el:19931308.

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11

Marshall, Justin, and Thomas W. Cronin. "Polarisation vision." Current Biology 21, no. 3 (February 2011): R101—R105. http://dx.doi.org/10.1016/j.cub.2010.12.012.

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12

Gherardelli, M., D. Giuli, and M. Fossi. "Suboptimum adative polarisation cancellers for dual-polarisation radars." IEE Proceedings F Communications, Radar and Signal Processing 135, no. 1 (1988): 60. http://dx.doi.org/10.1049/ip-f-1.1988.0008.

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13

Rathod, Nikita, Peter Slater, George Sergi, Gamini Seveviratne, and David Simpson. "A fresh look at depolarisation criteria for cathodic protection of steel reinforcement in concrete." MATEC Web of Conferences 289 (2019): 03011. http://dx.doi.org/10.1051/matecconf/201928903011.

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Criteria for the successful application of cathodic protection (CP) for steel reinforced concrete have been fixed for decades and form part of ISO EN12696. The most used criterion is the achievement of 100 mV depolarization over a period not exceeding 24 hours after discontinuation of the applied current. Although more empirical than theoretically based, the criterion has served the CP industry well. It does, however, exclude any systems that may not always achieve that level of depolarization but have been shown to offer adequate protection, and so there is a need to explore ways of assessing depolarisation data more effectively. On a fundamental level, non-linear polarisation, as described by the Butler Volmer equation, relates corrosion rate to polarisation for a given applied current density and shows that at low current densities, estimated corrosion rates can be shown to be still insignificant at less than 100 mV polarisations. This paper explores the use of non-linear polarisation as an additional supportive criterion based on the measured 24-hour depolarisation level for a known applied current density and tests its applicability in the laboratory and in the field. It speculates that a reducing apparent corrosion current density trend in combination with a depolarised potential moving in a more noble direction is likely to be a suitable alternative criterion, where 100 mV depolarisation is not achieved.

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14

Arshad, Haadia, and Muhammad Idrees. "Trends in Polarisation in Pakistan." Pakistan Development Review 47, no. 2 (June 1, 2008): 153–67. http://dx.doi.org/10.30541/v47i2pp.153-167.

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This study analyses the trends in polarisation in Pakistan, in its rural and urban segments and its provinces, at the micro level during the period 1992-93 to 2001-02. Estimations are made by using the Bossert-Schworm measure (2006). The study finds fluctuating trends. In general, polarisation declined in all regions of Pakistan during 1996-97 and 2001-02, while 1998-99 is the period of maximum polarisation. Incorporating the household size reduces the extent of polarisation, implying that ignoring the household size overestimates polarisation. The comparison of trends in polarisation and income inequality shows that generally the trends in inequality and polarisation are similar.

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15

Zhang, Teng, Jian Yang, Lei Guo, Pengwei Hu, Xin Liu, Panpan Huang, and Chenliang Wang. "A bionic point-source polarisation sensor applied to underwater orientation." Journal of Navigation 74, no. 5 (May 4, 2021): 1057–72. http://dx.doi.org/10.1017/s0373463321000308.

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AbstractWith the characteristics of full autonomy and no accumulated errors, polarisation navigation shows tremendous prospects in underwater scenarios. In this paper, inspired by the polarisation vision of aquatic organisms, a novel point-source polarisation sensor with high spectral adaptability (400 nm–760 nm) is designed for underwater orientation. To enhance the environmental applicability of the underwater polarisation sensor, a novel sensor model based on the underwater light intensity attenuation coefficient and optical coupling coefficient is established. In addition, concerned with the influence of light intensity uncertainty on sensor performance underwater, an antagonistic polarisation algorithm is adopted for the first time, to improve the accuracy of angle of polarisation and degree of polarisation in the low signal-to-noise ratio environment underwater. Finally, indoor and outdoor experiments are carried out to evaluate the performance of the designed polarisation sensor. The results show that the designed point-source polarisation sensor can acquire polarised light and be used for heading determination underwater.

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16

Vetter, Reinhold. "Polnische Polarisierung." osteuropa 69, no. 12 (2019): 39–53. http://dx.doi.org/10.35998/oe-2019-0020.

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17

Roiková, Eva, and Štěpán Kunc. "Stokes CMOS polarimetry limits studied at non-classical polarisation states." EPJ Web of Conferences 266 (2022): 10016. http://dx.doi.org/10.1051/epjconf/202226610016.

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We present the study of the two polarisation state analysers. The first consists of a polarisation camera with a removable QWP, and the second consists of a non-polarisation camera with a rotating QWP and a stationary linear polariser. The theoretical analysis and experiment focus on studying the influence of polarimeter optical components accuracy and errors such as retardation errors, misalignments and extinction ratio on Stokes parameters precision. This research is a cornerstone to understanding polarisation state analysers limits. We examined laser beams with non-classical polarisation distribution, namely the Poincaré beam and the beam with radial polarisation.

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18

Rolník, Ondřej, and Katarína Adamková. "The Mutual Influence of Labour Market Polarisation, Wage Polarisation and Political Polarisation in the European Union." DANUBE 15, no. 1 (March 1, 2024): 1–23. http://dx.doi.org/10.2478/danb-2024-0001.

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Abstract The aim of the paper is to prove a hypothesis concerning the dependence of the political polarisation of the European Union on recent developments in labour market structure. The labour market is undergoing changes that stem from technological progress as well as outsourcing of low-skill activities, which are causing an increase in labour market and wage polarisation. The premise is that the depopulation of the middle class is increasing political polarisation. The hypothesis is tested on a sample of 27 European Union countries from 1990 to the present using OLS with fixed effects regression analysis. Political polarization is represented by an own constructed political polarization index based on the ideological division of political parties’ data of the ParlGov project (2022). The index is constructed by combining the election results and four ideological spectrums. In conclusion, the dependence of political polarisation on labour market polarisation and wage polarisation is rejected.

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19

Tilstra, L. G., and P. Stammes. "Alternative polarisation retrieval for SCIAMACHY in the ultraviolet." Atmospheric Chemistry and Physics Discussions 5, no. 2 (April 1, 2005): 1973–93. http://dx.doi.org/10.5194/acpd-5-1973-2005.

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Abstract. We introduce an alternative method for the retrieval of polarisation in the ultraviolet by the satellite spectrometer SCIAMACHY. Unlike the operational polarisation retrieval algorithm, this method does not use the Polarisation Measurement Devices (PMDs) onboard SCIAMACHY, but only requires the reflectance signal. This makes the algorithm more robust and less sensitive to calibration errors caused by either improper characterisation of the instrument's response functions (key data) or degradation of the optical components. The alternative polarisation retrieval is able to retrieve the full state of atmospheric polarisation in the wavelength range between 330 and 400 nm, which is essentially the wavelength region covered by SCIAMACHY's PMD 1. This allows a direct comparison with the current operational product. When we compare the alternative polarisation algorithm with the operational algorithm, we find in some cases agreement, but not in other cases. The alternative algorithm compares well with an analytical model of the polarisation of a cloud-free scene. Using the alternative algorithm the polarisation-sensitive feature in the SCIAMACHY reflectance around 350 nm is automatically corrected for.

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20

Hoeft, Matthias, Kamlesh Rajpurohit, Denis Wittor, Gabriella di Gennaro, and Paola Domínguez-Fernández. "On the Polarisation of Radio Relics." Galaxies 10, no. 1 (January 10, 2022): 10. http://dx.doi.org/10.3390/galaxies10010010.

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Radio relics are extended radio emission features which trace shock waves in the periphery of galaxy clusters originating from cluster mergers. Some radio relics show a highly polarised emission, which make relics an excellent probe for the magnetisation of the intra-cluster medium. The origin of the relic polarisation is still debated. It could be a result of tangentially stretching the magnetic field at the shock surface. This scenario would naturally explain the alignment of the polarisation (E-vectors) with the shock normal. We have implemented a toy model for the relic polarisation according to this scenario. We find that the magnetic field strength itself crucially affects the fractional polarisation. Moreover, we find that the shock strength has surprisingly little effect on the overall polarisation fraction. Finally, we find that the fractional polarisation may decrease downstream depending on the magnetic field strength. Our results demonstrates that the shock compression scenario provides a very plausible explanation for the radio relic polarisation which specific features permitting to test the origin of radio relic polarisation.

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21

Tilstra, L. G., and P. Stammes. "Alternative polarisation retrieval for SCIAMACHY in the ultraviolet." Atmospheric Chemistry and Physics 5, no. 8 (August 9, 2005): 2099–107. http://dx.doi.org/10.5194/acp-5-2099-2005.

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Abstract. We introduce an alternative method for the retrieval of polarisation in the ultraviolet by the satellite spectrometer SCIAMACHY. Unlike the operational polarisation retrieval algorithm, this method does not use the Polarisation Measurement Devices (PMDs) onboard SCIAMACHY, but only requires the reflectance signal. This makes the algorithm more robust and less sensitive to calibration errors caused by either improper characterisation of the instrument's response functions (key data) or degradation of the optical components. The alternative polarisation retrieval is able to retrieve the full state of atmospheric polarisation in the wavelength range between 330 and 400 nm, which is essentially the wavelength region covered by SCIAMACHY's PMD 1. This allows a direct comparison with the current operational product. When we compare the alternative polarisation algorithm with the operational algorithm, we find in some cases agreement, but not in other cases. The alternative algorithm compares well with an analytical model of the polarisation of a cloud-free scene. Using the alternative algorithm the polarisation-sensitive feature in the SCIAMACHY reflectance around 350 nm is automatically corrected for.

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22

Scarrott, S. M., C. D. Rolph, and D. P. Semple. "Optical Polarisation Studies of Galaxies." Symposium - International Astronomical Union 140 (1990): 245–51. http://dx.doi.org/10.1017/s0074180900190138.

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High spatial resolution maps of the optical linear polarisation of a range of galaxies of different morphological types and inclinations are presented. Spiral, barred spiral and irregular galaxies with low inclinations show spiral patterns of polarisation orientation which may be interpreted to indicate that there are large-scale magnetic fields present in the discs of these galaxies. A survey of edge-on galaxies with conspicuous equatorial dust lanes shows remarkable differences in polarisation structure between early and late types. In the Sa galaxies the polarisation in the dust lane is sizeable and parallel to the dust lanes, suggesting that the magnetic field is uniformly distributed in the plane of the galaxy. This polarisation pattern disappears in the Sc galaxies suggesting that the relatively chaotic dust features do not possess a grain aligning mechanism, e.g. a magnetic field, that is uniform or coherent over large distance scales. It is clear that most galaxies do have polarisation patterns that are related to galactic structure and inclination, and further similar polarisation studies should help to unravel the relationship between the generation of polarisation and galactic magnetism.

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23

Park, K. J., H. Kim, J. H. Lee, C. J. Youn, S. K. Shin, and Y. C. Chung. "Polarisation-mode dispersion monitoring technique based on polarisation scrambling." Electronics Letters 38, no. 2 (2002): 83. http://dx.doi.org/10.1049/el:20020046.

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24

Barnes, W. L. "2×2 optical fibre polarisation switch and polarisation controller." Electronics Letters 24, no. 23 (1988): 1427. http://dx.doi.org/10.1049/el:19880975.

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25

Tsushima, H., and S. Sasaki. "Novel polarisation-frequency conversion-type polarisation diversity optical receiver." Electronics Letters 25, no. 8 (1989): 539. http://dx.doi.org/10.1049/el:19890369.

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26

Caponio, N., F. Delpiano, P. Gambini, M. Puleo, V. Seano, and E. Vezzoni. "Polarisation insensitive coherent transmission by synchronous intrabit polarisation spreading." Electronics Letters 27, no. 4 (1991): 337. http://dx.doi.org/10.1049/el:19910213.

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27

Parekh, R. A., R. L. Mehta, and A. Vyas. "Rabi cropped area forecasting of parts of Banaskatha District,Gujarat using MRS RISAT-1 SAR data." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B8 (October 14, 2016): 1413–16. http://dx.doi.org/10.5194/isprs-archives-xli-b8-1413-2016.

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Radar sensors can be used for large-scale vegetation mapping and monitoring using backscatter coefficients in different polarisations and wavelength bands. Due to cloud and haze interference, optical images are not always available at all phonological stages important for crop discrimination. Moreover, in cloud prone areas, exclusively SAR approach would provide operational solution. This paper presents the results of classifying the cropped and non cropped areas using multi-temporal SAR images. Dual polarised C- band RISAT MRS (Medium Resolution ScanSAR mode) data were acquired on 9<sup>th</sup>Dec. 2012, 28<sup>th</sup>Jan. 2013 and 22<sup>nd</sup> Feb. 2013 at 18m spatial resolution. Intensity images of two polarisations (HH, HV) were extracted and converted into backscattering coefficient images. Cross polarisation ratio (CPR) images and Radar fractional vegetation density index (RFDI) were created from the temporal data and integrated with the multi-temporal images. Signatures of cropped and un-cropped areas were used for maximum likelihood supervised classification. Separability in cropped and umcropped classes using different polarisation combinations and classification accuracy analysis was carried out. FCC (False Color Composite) prepared using best three SAR polarisations in the data set was compared with LISS-III (Linear Imaging Self-Scanning System-III) image. The acreage under rabi crops was estimated. The methodology developed was for rabi cropped area, due to availability of SAR data of rabi season. Though, the approach is more relevant for acreage estimation of kharif crops when frequent cloud cover condition prevails during monsoon season and optical sensors fail to deliver good quality images.

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Kang, Ji-hyun, Do-Young Byun, Kee-Tae Kim, Aran Lyo, Jongsoo Kim, Mi-kyoung Kim, Wouter Vlemmings, Boy Lankhaar, and Gabriele Surcis. "Linear polarisation of Class I methanol masers in massive star formation regions." Proceedings of the International Astronomical Union 13, S336 (September 2017): 243–46. http://dx.doi.org/10.1017/s1743921317010195.

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AbstractWe present the results of the linear polarisation observations of methanol masers at 44 and 95 GHz towards 39 massive star forming regions (Kanget al.2016). These two lines are observed simultaneously with the 21-m Korean VLBI Network (KVN) telescope in single dish mode. About 60% of the observed showed fractional polarisation of a few percents at least at one of the two transition lines. We note that the linear polarisation of the 44 GHz methanol maser is first detected in this study including single dish and interferometer observations. We find the polarisation properties of these two lines are similar as expected, since they trace similar regions. As a follow-up study, we have carried out the VLBI polarisation observations toward some 44 GHz maser targets using the KVN telescope. We present preliminary VLBI polarisation results of G10.34-0.14, which show consistent polarisation properties in multiple epoch observations.

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Preite, Massimo Valerio, Vito Sorianello, Gabriele De Angelis, Marco Romagnoli, and Philippe Velha. "Geometrical Representation of a Polarisation Management Component on a SOI Platform." Micromachines 10, no. 6 (May 30, 2019): 364. http://dx.doi.org/10.3390/mi10060364.

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Grating couplers, widely used in Silicon Photonics (SiPho) for fibre-chip coupling are polarisation sensitive components, consequently any polarisation fluctuation from the fibre optical link results in spurious intensity swings. A polarisation management componentis analytically considered, coupled with a geometrical representation based on phasors and Poincaré sphere, generalising and simplifying the treatment and understanding of its functionalities. A specific implementation in SOI is shown both as polarisation compensator and polarisation controller, focusing on the operative principle. Finally, it is demonstrated experimentally that this component can be used as an integrated polarimeter.

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Adams, Johnathan A., Gentry White, and Robyn P. Araujo. "Mathematical measures of societal polarisation." PLOS ONE 17, no. 10 (October 4, 2022): e0275283. http://dx.doi.org/10.1371/journal.pone.0275283.

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In opinion dynamics, as in general usage, polarisation is subjective. To understand polarisation, we need to develop more precise methods to measure the agreement in society. This paper presents four mathematical measures of polarisation derived from graph and network representations of societies and information-theoretic divergences or distance metrics. Two of the methods, min-max flow and spectral radius, rely on graph theory and define polarisation in terms of the structural characteristics of networks. The other two methods represent opinions as probability density functions and use the Kullback–Leibler divergence and the Hellinger distance as polarisation measures. We present a series of opinion dynamics simulations from two common models to test the effectiveness of the methods. Results show that the four measures provide insight into the different aspects of polarisation and allow real-time monitoring of social networks for indicators of polarisation. The three measures, the spectral radius, Kullback–Leibler divergence and Hellinger distance, smoothly delineated between different amounts of polarisation, i.e. how many cluster there were in the simulation, while also measuring with more granularity how close simulations were to consensus. Min-max flow failed to accomplish such nuance.

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31

Smith, BJK, NS Witte, and KC Hines. "Systematics of the Electroweak Plasma at Finite Temperature II." Australian Journal of Physics 48, no. 5 (1995): 775. http://dx.doi.org/10.1071/ph950775.

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This paper extends the treatment of the polarisation tensor for the electroweak plasma to encompass all the preliminaries needed for a thorough study of its characteristics as they affect the early Universe. The detailed development of the one-loop polarisation tensor calculated in a previous paper includes the construction of the basis tensors in terms of which the polarisation tensor is most conveniently expressed. The polarisation response functions are obtained next and there follows a detailed discussion of the real and imaginary parts of the polarisation tensor. These are the essential tools for the subsequent study of the mode structure and dissipation properties of the electroweak plasma.

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32

Patient, Dean A., and Simon A. R. Horsley. "Reflectionless anisotropic multilayers for both polarisations at grazing incidence." EPJ Applied Metamaterials 9 (2022): 15. http://dx.doi.org/10.1051/epjam/2022014.

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We find a method for designing anisotropic multilayer profiles that are reflectionless at grazing incidence, for both electromagnetic polarisations. The Helmholtz equation for grazing incidence propagation through an anisotropic multilayer can be factorised into a pair of equations of the form [see formula in PDF]. Solutions of [see formula in PDF] then determine two of the three principal values of the permittivity. Imposing the additional constraint of uniaxial anisotropy, we find a pair of coupled equations for the profile of both permittivity components such that neither polarisation is reflected.

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33

Veledina, Alexandra, Andrei V. Berdyugin, Ilia A. Kosenkov, Jari J. E. Kajava, Sergey S. Tsygankov, Vilppu Piirola, Svetlana V. Berdyugina, et al. "Evolving optical polarisation of the black hole X-ray binary MAXI J1820+070." Astronomy & Astrophysics 623 (March 2019): A75. http://dx.doi.org/10.1051/0004-6361/201834140.

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Aims. The optical emission of black hole transients increases by several magnitudes during the X-ray outbursts. Whether the extra light arises from the X-ray heated outer disc, from the inner hot accretion flow, or from the jet is currently debated. Optical polarisation measurements are able to distinguish the relative contributions of these components. Methods. We present the results of BVR polarisation measurements of the black hole X-ray binary MAXI J1820+070 during the period of March-April 2018. Results. We detect small, ∼0.7%, but statistically significant polarisation, part of which is of interstellar origin. Depending on the interstellar polarisation estimate, the intrinsic polarisation degree of the source is between ∼0.3% and 0.7%, and the polarisation position angle is between ∼10 ° −30°. We show that the polarisation increases after MJD 58222 (2018 April 14). The change is of the order of 0.1% and is most pronounced in the R band. The change of the source Stokes parameters occurs simultaneously with the drop of the observed V-band flux and a slow softening of the X-ray spectrum. The Stokes vectors of intrinsic polarisation before and after the drop are parallel, at least in the V and R filters. Conclusions. We suggest that the increased polarisation is due to the decreasing contribution of the non-polarized component, which we associate with the the hot flow or jet emission. The low polarisation can result from the tangled geometry of the magnetic field or from the Faraday rotation in the dense, ionised, and magnetised medium close to the black hole. The polarized optical emission is likely produced by the irradiated disc or by scattering of its radiation in the optically thin outflow.

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34

Stack, P. D., and S. P. Ellingsen. "Polarisation of Class II Methanol Masers." Publications of the Astronomical Society of Australia 28, no. 4 (2011): 338–56. http://dx.doi.org/10.1071/as11029.

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AbstractWe have used the University of Tasmania Mt Pleasant 26-m radio telescope to investigate the polarisation characteristics of a sample of strong 6.7 GHz methanol masers, the first spectral line polarisation observations to be undertaken with this instrument. As part of this process we have developed a new technique for calibrating linear polarisation spectral line observations. This calibration method gives results consistent with more traditional techniques, but requires much less observing time on the telescope. We have made the first polarisation measurements of a number of 6.7 GHz methanol masers and find linear polarisation at levels from a few to 10% in most of the sources we observed, consistent with previous results. We also investigated the circular polarisation produced by Zeeman splitting in the 6.7 GHz methanol maser G9.62+0.20 to get an estimate of the line of sight magnetic field strength of 35±7 mG.

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35

Tilstra, L. G., R. Lang, R. Munro, I. Aben, and P. Stammes. "Contiguous polarisation spectra of the Earth from 300 to 850 nm measured by GOME-2 onboard MetOp-A." Atmospheric Measurement Techniques 7, no. 7 (July 9, 2014): 2047–59. http://dx.doi.org/10.5194/amt-7-2047-2014.

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Abstract. In this paper we present the first contiguous high-resolution spectra of the Earth's polarisation observed by a satellite instrument. The measurements of the Stokes fraction Q/I are performed by the spectrometer GOME-2 onboard the MetOp-A satellite. Polarisation measurements by GOME-2 are performed by onboard polarisation measurement devices (PMDs) and the high-resolution measurements discussed in this paper are taken in the special "PMD RAW" mode of operation. The spectral resolution of these PMD RAW polarisation measurements varies from 3 nm in the ultraviolet (UV) to 35 nm in the near-infrared wavelength range. We first compare measurements of the polarisation from cloud-free scenes with radiative transfer calculations for a number of cases. We find good agreement but also a spectral discrepancy at 800 nm, which we attribute to remaining imperfections in the calibration key data. Secondly, we study the polarisation of scenes with special scattering geometries that normally lead to near-zero Q/I. The GOME-2 polarisation spectra indeed show this behaviour and confirm the existence of the small discrepancy found earlier. Thirdly, we study the Earth polarisation for a variety of scenes. This provides a blueprint of Q/I over land and sea surfaces for various degrees of cloud cover. Fourthly, we compare the spectral dependence of measurements of Q/I in the UV with the generalised distribution function proposed by Schutgens and Stammes (2002) to describe the shape of the UV polarisation spectrum. The GOME-2 data confirm that these functions match the spectral behaviour captured by the GOME-2 PMD RAW mode.

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36

López Ariste, A., B. Tessore, E. S. Carlín, Ph Mathias, A. Lèbre, J. Morin, P. Petit, M. Aurière, D. Gillet, and F. Herpin. "Asymmetric shocks in χ Cygni observed with linear spectropolarimetry." Astronomy & Astrophysics 632 (November 25, 2019): A30. http://dx.doi.org/10.1051/0004-6361/201936189.

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Aims. We derive information about the dynamics of the stellar photosphere, including pulsation, from a coherent interpretation of the linear polarisation detected in the spectral lines of the Mira star χ Cyg. Methods. From spectropolarimetric observations of χ Cyg, we performed a careful analysis of the polarisation signals observed in atomic and molecular lines, both in absorption and emission, using radiative transfer in the context of polarisation produced through two mechanisms: intrinsic polarisation and continuum depolarisation. We also explain the observed line doubling phenomenon in terms of an expanding shell in spherical geometry, which allows us to pinpoint the coordinates over the stellar disc with enhanced polarisation. Results. We find that the polarised spectrum of χ Cyg is dominated by intrinsic polarisation and has a negligible continuum depolarisation. The observed polarised signals can only be explained by assuming that this polarisation is locally enhanced by velocity fields. During the pulsation, radial velocities are not homogeneous over the disc. We map these regions of enhanced velocities. Conclusions. We set an algorithm to distinguish the origin of this polarisation in any stellar spectra of linear polarisation and to find a way to increase the signal by coherently adding many lines with an appropriated weight. Applied to the Mira star χ Cyg, we reached the unexpected result that during the pulsation, velocities are radial but not homogeneous over the disc. The reason for these local velocity enhancements are probably related to the interplay between the atmospheric pulsation dynamics and the underlying stellar convection.

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37

Zhevandrov, N. D. "Polarisation physiological optics." Uspekhi Fizicheskih Nauk 165, no. 10 (1995): 1193. http://dx.doi.org/10.3367/ufnr.0165.199510d.1193.

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38

Zhevandrov, N. D. "Polarisation physiological optics." Physics-Uspekhi 38, no. 10 (October 31, 1995): 1147–66. http://dx.doi.org/10.1070/pu1995v038n10abeh000115.

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39

Thulstrup, Erik W., Josef Michl, and D. Thorburn Burns. "Elementary polarisation spectroscopy." Analytica Chimica Acta 243 (1991): 323. http://dx.doi.org/10.1016/s0003-2670(00)82580-5.

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40

Moati, F., and A. Desgrez. "Polarisation de fluorescence." Trait - d'Union 1, no. 1 (January 1986): 33–35. http://dx.doi.org/10.1016/s0980-9090(86)80057-x.

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41

Atkinson, Gary A. "Polarisation photometric stereo." Computer Vision and Image Understanding 160 (July 2017): 158–67. http://dx.doi.org/10.1016/j.cviu.2017.04.014.

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42

Jonscher, A. K. "Relaxation of polarisation." Applied Physics A Solids and Surfaces 55, no. 2 (August 1992): 135–38. http://dx.doi.org/10.1007/bf00334211.

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43

Otto, T., J. Lu, and M. Chandra. "Polarisation basis transformation of weather radar measurements in the power domain." Advances in Radio Science 7 (May 19, 2009): 279–84. http://dx.doi.org/10.5194/ars-7-279-2009.

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Abstract. Polarisation diversity in radar remote sensing proved to be very successful in a variety of applications. Hydrometeors as raindrops or ice crystals are anisotropic radar targets giving rise to the use of polarisation diversity in weather radars. One advanced polarimetric weather radar is DLR's POLDIRAD in Oberpfaffenhofen. The huge data archive of this radar consists mainly of power measurements at diverse polarisation bases. This study investigates the possibility to apply the polarisation basis transformation directly on power measurements. As a result, empirical transfer functions for the change of the polarisation basis of radar reflectivities are derived. To check their validity they are applied to appropriate polarimetric radar data from the POLDIRAD.

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44

Hayata, K., M. Koshiba, and M. Suzuki. "Polarisation characteristics of graded-core stress-applied polarisation-maintaining fibres." Electronics Letters 22, no. 7 (1986): 363. http://dx.doi.org/10.1049/el:19860247.

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45

Granestrand, P., L. Thylen, and B. Stoltz. "Polarisation independent switch and polarisation splitter employing Δβand ΔK modulation." Electronics Letters 24, no. 18 (1988): 1142. http://dx.doi.org/10.1049/el:19880776.

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46

Maeda, M. W., and D. A. Smith. "New polarisation-insensitive direction scheme based on fibre polarisation scrambling." Electronics Letters 27, no. 1 (January 3, 1991): 10–12. http://dx.doi.org/10.1049/el:19910007.

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47

Peng, G. D., T. Tjugiarto, and P. L. Chu. "Polarisation maintaining composite fibre with well-aligned principal polarisation axes." Electronics Letters 28, no. 24 (1992): 2243. http://dx.doi.org/10.1049/el:19921442.

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48

Akujor, Chidi E. "Peculiar Magnetic Field Structures in 4C49.22 (1150+497)." Symposium - International Astronomical Union 140 (1990): 453–54. http://dx.doi.org/10.1017/s0074180900190849.

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We present radio polarisation observations of the quasar 4C49.22. It shows no evidence of depolarisation on the counter–jet side, while exhibiting strong variation of fractional polarisation along the jet, as well as transverse offset of maximum fractional polarisation from each knot in the jet.

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49

Tilstra, L. G., R. Lang, R. Munro, I. Aben, and P. Stammes. "Contiguous polarisation spectra of the Earth from 300–850 nm measured by GOME-2 onboard MetOp-A." Atmospheric Measurement Techniques Discussions 6, no. 6 (December 19, 2013): 11309–43. http://dx.doi.org/10.5194/amtd-6-11309-2013.

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Abstract. In this paper we present the first contiguous high-resolution spectra of the Earth's polarisation observed by a satellite instrument. The measurements of the Stokes fraction Q/I are performed by the spectrometer GOME-2 onboard the MetOp-A satellite. Polarisation measurements by GOME-2 are performed by onboard polarisation measurement devices (PMDs) and the high-resolution measurements discussed in this paper are taken in the special "PMD RAW" mode of operation. The spectral resolution of these PMD RAW polarisation measurements varies from 3 nm in the ultraviolet (UV) to 35 nm in the near-infrared wavelength range. We first compare measurements of the polarisation from cloud-free scenes with radiative transfer calculations for a number of cases. We find good agreement but also a spectral discrepancy at 800 nm, which we attribute to remaining imperfections in the calibration key data. Secondly, we study the polarisation of scenes with special scattering geometries that normally lead to near-zero Q/I. The GOME-2 polarisation spectra indeed show this behaviour and confirm the existence of the small discrepancy found earlier. Thirdly, we study the Earth polarisation for a variety of scenes. This provides a blueprint of Q/I over land and sea surfaces for various degrees of cloud cover. Fourthly, we compare the spectral dependence of measurements of Q/I in the UV with the generalised distribution function that was proposed in the past (Schutgens and Stammes, 2002) to describe the shape of the UV polarisation spectrum. The GOME-2 data confirm that these functions match the spectral behaviour captured by the GOME-2 PMD RAW mode.

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50

Menant, Sébastien, Frédéric Guégan, Vincent Tognetti, Lynda Merzoud, Laurent Joubert, Henry Chermette, and Christophe Morell. "Polarisation of Electron Density and Electronic Effects: Revisiting the Carbon–Halogen Bonds." Molecules 26, no. 20 (October 14, 2021): 6218. http://dx.doi.org/10.3390/molecules26206218.

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Electronic effects (inductive and mesomeric) are of fundamental importance to understand the reactivity and selectivity of a molecule. In this article, polarisation temperature is used as a principal index to describe how electronic effects propagate in halogeno-alkanes and halogeno-alkenes. It is found that as chain length increases, polarisation temperature decreases. As expected, polarisation is much larger for alkenes than for alkanes. Finally, the polarisation mode of the carbon–fluorine bond is found to be quite different and might explain the unusual reactivity of fluoride compounds.

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