1,720,965 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Dual circularly polarized GNSS-reflectometry for remote sensing of land and sea surfaces
Get PDFAbstract
Remote sensing of the environment is of utmost importance to better understand the effects of climate change. The utilization of Global Navigation Satellite System (GNSS) signals reflected from different Earth surfaces allows the investigation of important surface parameters for climate change studies such as the sea level, sea-ice thickness, soil moisture, etc. The polarization reversal of the GNSS transmitted right-hand circularly polarized (RHCP) signal upon reflection to left-hand circularly polarized (LHCP) signal enables exploration of this diversity and studying of the reflecting surface properties.
This thesis presents a polarimetric analysis of GNSS Signals-of-Opportunity using a cost-effective dual circularly polarized (DCP) GNSS-Reflectometry (GNSS-R) system for remote sensing of land and sea surfaces. A custom-designed, phase-stable DCP antenna and commercial GNSS receivers record direct and reflected GNSS signals. The developed low-cost GNSS-R system allows the simultaneous reception of two low-correlation data streams of orthogonally polarized GNSS signals. This enables utilization of the received carrier-to-noise density ratios (C/N0) for characterizing reflecting surface properties.
GNSS-R measurement campaigns conducted during this thesis investigated surface properties in different seasons and surface conditions. Sea ice thickness was estimated from the total freeboard, which was derived from the difference between the sea level bias calculated using the GNSS-interferometric reflectometry method and the sea level data from the Finnish Meteorological Institute. The signatures of multilayered propagation of the GNSS signals through the sea ice in received LHCP C/N0 data streams enabled sea ice thickness characterization. The statistics of the received LHCP data showed a correlation with the wind speed observations over the open sea. The GNSS-interference pattern technique was used to estimate the RHCP and LHCP reflection coefficients to measure the relative permittivity of the open sea and land by inversion of the Brewster angle. The practicality of performing dynamic measurements using the DCP system was tested onboard a drone for different remote sensing applications. Original papers Regmi, A., Berg, M., & Pärssinen, A. (2019). A method for ice thickness characterization using GNSS C/N0 data. 2019 8th Asia-Pacific Conference on Antennas and Propagation (APCAP), 534–538. https://doi.org/10.1109/APCAP47827.2019.9472017 https://doi.org/10.1109/APCAP47827.2019.9472017 Self-archived version Regmi, A., Pärssinen, A., & Berg, M. (2020). Sea surface characterization using dual polarized GNSS reception system. 2020 14th European Conference on Antennas and Propagation (EuCAP), 1–5. https://doi.org/10.23919/EuCAP48036.2020.9135227 https://doi.org/10.23919/EuCAP48036.2020.9135227 Self-archived version Regmi, A., Hänninen, T., Leinonen, M. E., Pärssinen, A., & Berg, M. (2021). Dynamic dual polarized GNSS reflectometry using UAV. 2021 15th European Conference on Antennas and Propagation (EuCAP), 1–5. https://doi.org/10.23919/EuCAP51087.2021.9411371 https://doi.org/10.23919/EuCAP51087.2021.9411371 Self-archived version Regmi, A., Leinonen, M. E., Pärssinen, A., & Berg, M. (2022). Monitoring sea ice thickness using GNSS-interferometric reflectometry. IEEE Geoscience and Remote Sensing Letters, 19, 1–5. https://doi.org/10.1109/LGRS.2022.3198189 https://doi.org/10.1109/LGRS.2022.3198189 Self-archived version Regmi, A., Leinonen, M. E., Pärssinen, A., & Berg, M. (2024). Relative permittivity measurement of sea and land by ground-based dual circularly polarized GNSS-reflectometry. IEEE Transactions on Geoscience and Remote Sensing, 62, 1–16. https://doi.org/10.1109/TGRS.2023.3346792 https://doi.org/10.1109/TGRS.2023.3346792 Self-archived version Tiivistelmä
Ympäristön kaukokartoitus on tärkeä menetelmä ilmaston muutosten vaikutusten havainnointiin. Globaalin satelliittinavigointisysteemin (GNSS) signaalien heijastuminen maanpinnasta mahdollistaa sen sisältämien materiaalien ja pintojen tutkimuksen kuten myös meren pinnan korkeuden havainnoinnin, meren jään paksuuden tai maaperän kosteuden mittaamisen. GNSS-signaalin polarisaation kääntyminen oikean käden ympyräpolarisaatiosta (RHCP) heijastumisen kautta vasemman käden ympyräpolarisaatioksi (LHCP) mahdollistaa heijastavan pinnan ominaisuuksien tutkimisen.
Tässä väitöstutkimuksessa esitellään GNSS-signaalin polaarimetrinen analyysi, joka perustuu kustannustehokkaan kaksoisympyräpolarisoidun (DCP) GNSS reflektometrisysteemin (GNSS-R) käyttöön maan- ja merenpinnan kaukokartoituksessa. Erikoissuunniteltu, vaihestabiili DCP antenni ja kaupalliset GNSS-vastaanottimet tallentavat suoraan eteneviä ja heijastuneita GNSS-signaaleja. Kehitetty GNSS-R-järjestelmä mahdollistaa kahden samanaikaisen heikosti korreloivan ortogonaalisesti polarisoidun GNSS-signaalin vastaanottamisen. Tämä mahdollistaa vastaanotettujen signaalien signaalikantoaalto-kohinasuhteen (C/N0) käyttämisen heijastavien pintojen ominaisuuksien määrittämiseen.
Tässä työssä esitellyt GNSS-R-mittaukset tutkivat pintojen ominaisuuksia eri vuoden aikoina ja erilaisissa pintaolosuhteissa. Meren jään paksuutta estimoitiin havainnoimalla kokonaiskorkeutta, joka saatiin meren pinnan korkeuksien erotuksena, kun verrattiin GNSS-interfero-reflektometrisiä tuloksia ja Suomen Ilmatieteen laitoksen merenpinnan korkeuden tietoja. Monikerroksisen jään läpi edenneen GNSS-signaalin muutokset havainnoitiin muutoksina LHCP C/N0-parametrissä mahdollistaen jään paksuuden mittaamisen. Vastaanotetun LHCP-datan tilastolliset parametrit havainnoivat korrelaation tuulen nopeuden kanssa avoimella merellä. GNSS-häiriökuviotekniikkaa käytettiin arvioimaan RHCP- ja LHCP-heijastuskertoimet ja niiden kautta mittamaan avomeren ja maan suhteelliset permittiivisyydet Brewsterin kulman avulla. Dynaamisten mittausten käytännöllisyyttä DCP-järjestelmällä testattiin droonilla erilaisissa kaukokartoitustilanteissa. Osajulkaisut Regmi, A., Berg, M., & Pärssinen, A. (2019). A method for ice thickness characterization using GNSS C/N0 data. 2019 8th Asia-Pacific Conference on Antennas and Propagation (APCAP), 534–538. https://doi.org/10.1109/APCAP47827.2019.9472017 https://doi.org/10.1109/APCAP47827.2019.9472017 Rinnakkaistallennettu versio Regmi, A., Pärssinen, A., & Berg, M. (2020). Sea surface characterization using dual polarized GNSS reception system. 2020 14th European Conference on Antennas and Propagation (EuCAP), 1–5. https://doi.org/10.23919/EuCAP48036.2020.9135227 https://doi.org/10.23919/EuCAP48036.2020.9135227 Rinnakkaistallennettu versio Regmi, A., Hänninen, T., Leinonen, M. E., Pärssinen, A., & Berg, M. (2021). Dynamic dual polarized GNSS reflectometry using UAV. 2021 15th European Conference on Antennas and Propagation (EuCAP), 1–5. https://doi.org/10.23919/EuCAP51087.2021.9411371 https://doi.org/10.23919/EuCAP51087.2021.9411371 Rinnakkaistallennettu versio Regmi, A., Leinonen, M. E., Pärssinen, A., & Berg, M. (2022). Monitoring sea ice thickness using GNSS-interferometric reflectometry. IEEE Geoscience and Remote Sensing Letters, 19, 1–5. https://doi.org/10.1109/LGRS.2022.3198189 https://doi.org/10.1109/LGRS.2022.3198189 Rinnakkaistallennettu versio Regmi, A., Leinonen, M. E., Pärssinen, A., & Berg, M. (2024). Relative permittivity measurement of sea and land by ground-based dual circularly polarized GNSS-reflectometry. IEEE Transactions on Geoscience and Remote Sensing, 62, 1–16. https://doi.org/10.1109/TGRS.2023.3346792 https://doi.org/10.1109/TGRS.2023.3346792 Rinnakkaistallennettu versio Academic dissertation to be presented with the assent of the Doctoral Programme Committee of Information Technology and Electrical Engineering of the University of Oulu for public defence in the Wetteri auditorium (IT115), Linnanmaa, on 20 March 2025, at 12 noonAbstract
Remote sensing of the environment is of utmost importance to better understand the effects of climate change. The utilization of Global Navigation Satellite System (GNSS) signals reflected from different Earth surfaces allows the investigation of important surface parameters for climate change studies such as the sea level, sea-ice thickness, soil moisture, etc. The polarization reversal of the GNSS transmitted right-hand circularly polarized (RHCP) signal upon reflection to left-hand circularly polarized (LHCP) signal enables exploration of this diversity and studying of the reflecting surface properties.
This thesis presents a polarimetric analysis of GNSS Signals-of-Opportunity using a cost-effective dual circularly polarized (DCP) GNSS-Reflectometry (GNSS-R) system for remote sensing of land and sea surfaces. A custom-designed, phase-stable DCP antenna and commercial GNSS receivers record direct and reflected GNSS signals. The developed low-cost GNSS-R system allows the simultaneous reception of two low-correlation data streams of orthogonally polarized GNSS signals. This enables utilization of the received carrier-to-noise density ratios (C/N0) for characterizing reflecting surface properties.
GNSS-R measurement campaigns conducted during this thesis investigated surface properties in different seasons and surface conditions. Sea ice thickness was estimated from the total freeboard, which was derived from the difference between the sea level bias calculated using the GNSS-interferometric reflectometry method and the sea level data from the Finnish Meteorological Institute. The signatures of multilayered propagation of the GNSS signals through the sea ice in received LHCP C/N0 data streams enabled sea ice thickness characterization. The statistics of the received LHCP data showed a correlation with the wind speed observations over the open sea. The GNSS-interference pattern technique was used to estimate the RHCP and LHCP reflection coefficients to measure the relative permittivity of the open sea and land by inversion of the Brewster angle. The practicality of performing dynamic measurements using the DCP system was tested onboard a drone for different remote sensing applications.Tiivistelmä
Ympäristön kaukokartoitus on tärkeä menetelmä ilmaston muutosten vaikutusten havainnointiin. Globaalin satelliittinavigointisysteemin (GNSS) signaalien heijastuminen maanpinnasta mahdollistaa sen sisältämien materiaalien ja pintojen tutkimuksen kuten myös meren pinnan korkeuden havainnoinnin, meren jään paksuuden tai maaperän kosteuden mittaamisen. GNSS-signaalin polarisaation kääntyminen oikean käden ympyräpolarisaatiosta (RHCP) heijastumisen kautta vasemman käden ympyräpolarisaatioksi (LHCP) mahdollistaa heijastavan pinnan ominaisuuksien tutkimisen.
Tässä väitöstutkimuksessa esitellään GNSS-signaalin polaarimetrinen analyysi, joka perustuu kustannustehokkaan kaksoisympyräpolarisoidun (DCP) GNSS reflektometrisysteemin (GNSS-R) käyttöön maan- ja merenpinnan kaukokartoituksessa. Erikoissuunniteltu, vaihestabiili DCP antenni ja kaupalliset GNSS-vastaanottimet tallentavat suoraan eteneviä ja heijastuneita GNSS-signaaleja. Kehitetty GNSS-R-järjestelmä mahdollistaa kahden samanaikaisen heikosti korreloivan ortogonaalisesti polarisoidun GNSS-signaalin vastaanottamisen. Tämä mahdollistaa vastaanotettujen signaalien signaalikantoaalto-kohinasuhteen (C/N0) käyttämisen heijastavien pintojen ominaisuuksien määrittämiseen.
Tässä työssä esitellyt GNSS-R-mittaukset tutkivat pintojen ominaisuuksia eri vuoden aikoina ja erilaisissa pintaolosuhteissa. Meren jään paksuutta estimoitiin havainnoimalla kokonaiskorkeutta, joka saatiin meren pinnan korkeuksien erotuksena, kun verrattiin GNSS-interfero-reflektometrisiä tuloksia ja Suomen Ilmatieteen laitoksen merenpinnan korkeuden tietoja. Monikerroksisen jään läpi edenneen GNSS-signaalin muutokset havainnoitiin muutoksina LHCP C/N0-parametrissä mahdollistaen jään paksuuden mittaamisen. Vastaanotetun LHCP-datan tilastolliset parametrit havainnoivat korrelaation tuulen nopeuden kanssa avoimella merellä. GNSS-häiriökuviotekniikkaa käytettiin arvioimaan RHCP- ja LHCP-heijastuskertoimet ja niiden kautta mittamaan avomeren ja maan suhteelliset permittiivisyydet Brewsterin kulman avulla. Dynaamisten mittausten käytännöllisyyttä DCP-järjestelmällä testattiin droonilla erilaisissa kaukokartoitustilanteissa
Reflection measurement of building materials at microwaves
Get PDFRadio waves interact differently with different materials. The knowledge of reflection and transmission characteristics of the electromagnetic waves through and from the building walls is the key in designing a radio propagation model. The dielectric properties of the material determine the behavior of reflection and transmission of the electromagnetic waves. Therefore, an oblique reflection model is implemented in this thesis to estimate the dielectric properties of various walls at frequency range of 0.7–7 GHz (6.3 GHz bandwidth). The measurement setup consists of a four-port vector network analyzer, two wideband dual-polarized cross-shaped Vivaldi antennas and two 8 m long coaxial cables. Measurements for parallel and perpendicular polarizations are achieved simultaneously by using the dual-polarized antennas. Time-domain gating is applied to separate the desired reflection and eliminate all other multiple reflections from the environment and to suppress the Line-of-Sight component from the delayed response.
The estimation of dielectric property of a material is an optimization problem where a suitable objective function is minimized to get the appropriate value. A theoretical model is implemented, so that the minimum difference between the theoretical and measured absolute value of reflection coefficient gives an estimated value of complex relative permittivity. The non-linear least squares algorithm is used for optimization purpose. The real and imaginary part of complex relative permittivity is investigated in this thesis. The real part signifies the amount of electric energy stored in a material, and is called dielectric constant whereas the imaginary part is called the loss factor, which signifies the dissipation of the radiated energy. The estimated values are in good agreement with the values found in the literature. The estimated dielectric properties in this study, such as dielectric constant, loss tangent and Brewster angle of the various materials can be utilized further in designing radio propagation models for similar environments
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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