1,720,969 research outputs found
A comparative study of heat transfer analysis of fractional Maxwell fluid by using Caputo and Caputo-Fabrizio derivatives
Get PDFA comparative analysis is carried out to study the unsteady flow of a Maxwell fluid in the presence of Newtonian heating near a vertical flat plate. The fractional derivatives presented by Caputo and Caputo–Fabrizio are applied to make a physical model for a Maxwell fluid. Exact solutions of the non-dimensional temperature and velocity fields for Caputo and Caputo–Fabrizio time-fractional derivatives are determined via the Laplace transform technique. Numerical solutions of partial differential equations are obtained by employing Tzou’s and Stehfest’s algorithms to compare the results of both models. Exact solutions with integer-order derivative (fractional parameter α = 1) are also obtained for both temperature and velocity distributions as a special case. A graphical illustration is made to discuss the effect of Prandtl number Pr and time t on the temperature field. Similarly, the effects of Maxwell fluid parameter λ and other flow parameters on the velocity field are presented graphically, as well as in tabular form.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author
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
Characteristics of aggregated traffic in LoRaWAN
Get PDFOver the past few years, internet-of-Things (IoT) request a large number of smart devices to communicate and exchange information without direct human assistance. As the number of IoT nodes are increasing rapidly, the massive machine-type communication (mMTC) in 5G enables us to integrate the IoT massive traffic and applications without affecting the traditional services. Low-Power Wide-Area Networks (LPWAN) are emerging commercially and considered as fundamental enablers of IoT, Industrial Internet-of-Things (IIoT), and industrial revolution 4.0 because of their license free frequency bands, long range, low power consumption, and low cost. In recent years, LoRaWAN is appearing as one of the most leading LPWAN technologies. The main contribution of this work is examining the characteristics and modeling the aggregated traffic of a large and dense LoRa Network that is deployed as a monitoring system inside Tellus Innovation Arena, University of Oulu, with the concept of IoT-based digital campus as a Wireless Access IoT service of 5GTN. To understand the traffic behaviour, we analyzed the inter-arrival times of the transmissions for different weeks, days, and hours. The statistical presentation of data reveals that the trend of transmissions is exponential, that shows that most of the transmissions were within the inter-arrival time of less than 10 seconds while few of them have inter-arrival time over 20 seconds. After that, we fitted inter-arrival times into the exponential distribution, which helped us to find the mean inter-arrival time of the 5GTN traffic which is further used for the modeling of aggregated traffic. Finally, we performed the transmission compression from a gateway to the Network Server that will be beneficial to efficiently utilize the resources and bandwidth. The results demonstrate that the proposed aggregation mechanism increases the system goodput
Machine-type direct-to-satellite communications : modeling and performance analysis
Get PDFAbstract
Despite the massive progress in 5G and beyond systems, the deployed terrestrial networks do not provide ubiquitous coverage even on land; the situation is even worse in the open sea, which covers 70% of the Earth's surface. This disparity illustrates a significant digital divide. To address this vital need, global wireless coverage stands as one of the most crucial requirements for the upcoming 6G wireless networks to offer connectivity to both human and IoT machines.
This thesis advocates massive machine-type communication (mMTC) and low Earth orbit (LEO) satellite integration to enable direct connectivity from low-cost, low-power end devices to satellites without relying on a terrestrial network. This emerging form of new connectivity, machine-type direct-to-satellite (DtS) communications, promises to bridge the digital divide. However, DtS presents exciting challenges which need to be carefully examined and addressed. Among these challenges is LEO satellite mobility, which introduces a strong Doppler effect and time-varying channel conditions. Similarly, the long link distance ranging from hundreds to thousands of kilometers and the wide satellite footprint contributes to high propagation losses and massive interference, respectively. Additionally, terrestrial end devices possess limited energy resources. Therefore, successful DtS operation requires high energy efficiency, allowing the low-power signals to reach satellites orbiting thousands of kilometers away from Earth.
Motivated by the low-power and long-range capabilities of LoRaWAN, this thesis selected LoRa and LR-FHSS-based solutions for the modeling. This thesis develops novel Monte Carlo simulation and analytical models for DtS communications performance analysis. The results confirmed the feasibility and potential of both LoRa and LR-FHSS for DtS communications and highlighted the trade-off of different parameter configurations. In summary, LR-FHSS reveals better performance compared to LoRa, primarily due to its high sensitivity, robust Doppler resistance, and increased capacity, making it a suitable choice for DtS communications.
LR-FHSS end devices are expected to be powered by battery, therefore, it is vital to investigate the energy consumption of LR-FHSS. This work conducts experiments using real-life end devices and measures the LR-FHSS air-time and current consumption. We leverage these empirical measurement results to develop analytical models which give us the energy efficiency and battery lifetime of LR-FHSS end devices. LR-FHSS air-time model is highly important for accurate collisions modeling and scalability analysis.Tiivistelmä
Vaikka 5G- ja uudemmissa järjestelmissä on edistytty merkittävästi, nykyiset maanpäälliset verkot eivät ulotu kaikkialle edes maalla, saati avomerellä, jota on 70 prosenttia maapallon pinta-alasta. Tästä erosta voidaan havaita merkittävä digitaalinen kahtiajako. Tulevien langattomien 6G-verkkojen tärkeimpiä vaatimuksia on maailmanlaajuinen kuuluvuus, jotta tähän elintärkeään tarpeeseen voidaan vastata ja yhdistää sekä ihmiset että koneet.
Esitän tässä tutkielmassa, miten massiivisen laitteiden välisen viestinnän (massive machine-type communication, MMTC) ja matalan kiertoradan (low earth orbit, LEO) satelliittien avulla edulliset ja pienitehoiset päätelaitteet voivat saada satelliittiyhteyden ilman maanpäällistä verkkoa. Tämä uusi yhteysmuoto, suora laitteiden välinen satelliittiviestintä (direct-to-satellite, DtS), voi kuroa edellä mainitun digitaalisen kuilun umpeen. DtS-tekniikkaan liittyy kuitenkin mielenkiintoisia haasteita. Haasteena on muun muassa LEO-satelliittien liikkuvuus, mikä aiheuttaa voimakasta Doppler-ilmiötä ja ajassa vaihtelevia kanavan olosuhteita. Samoin yhteyden huomattava pituus (satoja tai tuhansia kilometrejä) ja laaja satelliitin peittoalue aiheuttavat suurta etenemisvaimennusta ja häiriötä tässä järjestyksessä. Lisäksi maanpäällisten päätelaitteiden energiabudjetti on rajallinen. Näin ollen onnistunut DtS:n käyttö edellyttää erinomaista energiatehokkuutta.
LoRaWAN-teknologian pienet tehovaatimukset ja pitkä kantama saivat minut valitsemaan tämän tutkielman mallinnukseen ratkaisut, jotka perustuvat LoRa- ja LR-FHSS-teknologiaan. Kehitän tutkielmassa uusia Monte Carlo -simulaatioita ja analyyttisiä malleja DtS-tietoliikenteen suorituskyvyn analysoimiseksi. Tulosten perusteella sekä LoRa- että LR-FHSS-teknologiassa on potentiaalia ja ne ovat toteuttamiskelpoisia DtS-tiedonsiirtoon. Tulokset myös korostavat erilaisista parametreista seuraavia kompromisseja. Yhteenvetona totean, että LR-FHSS:n suorituskyky oli LoRa-teknologiaa parempi, ensisijaisesti sen suuren herkkyyden, hyvän Doppler-ilmiön siedon ja suuremman kapasiteetin ansiosta, minkä ansiosta se on sopiva DtS-tiedonsiirtoon.
LR-FHSS-päätelaitteet ovat oletusarvoisesti akkukäyttöisiä, joten LR-FHSS-teknologian energiankulutuksen tutkiminen on ehdottoman tärkeää. Tein tässä tutkielmassa kokeita oikeilla päätelaitteilla ja mittasin LR-FHSS-teknologian lähetysaikaa ja virrankulutusta. Sovelsin empiirisiä mittaustuloksia sellaisten analyyttisten mallien kehittämiseen, joilla saatoin päätellä LR-FHSS-päätelaitteiden energiatehokkuuden ja akkukeston. LR-FHSS-lähetysaikamalli on tärkeä työkalu tarkkaan törmäysten mallintamiseen ja skaalautuvuuden analysoimiseen.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 OP auditorium (L10), Linnanmaa, on 27 September 2024, at 12 noonAbstract
Despite the massive progress in 5G and beyond systems, the deployed terrestrial networks do not provide ubiquitous coverage even on land; the situation is even worse in the open sea, which covers 70% of the Earth's surface. This disparity illustrates a significant digital divide. To address this vital need, global wireless coverage stands as one of the most crucial requirements for the upcoming 6G wireless networks to offer connectivity to both human and IoT machines.
This thesis advocates massive machine-type communication (mMTC) and low Earth orbit (LEO) satellite integration to enable direct connectivity from low-cost, low-power end devices to satellites without relying on a terrestrial network. This emerging form of new connectivity, machine-type direct-to-satellite (DtS) communications, promises to bridge the digital divide. However, DtS presents exciting challenges which need to be carefully examined and addressed. Among these challenges is LEO satellite mobility, which introduces a strong Doppler effect and time-varying channel conditions. Similarly, the long link distance ranging from hundreds to thousands of kilometers and the wide satellite footprint contributes to high propagation losses and massive interference, respectively. Additionally, terrestrial end devices possess limited energy resources. Therefore, successful DtS operation requires high energy efficiency, allowing the low-power signals to reach satellites orbiting thousands of kilometers away from Earth.
Motivated by the low-power and long-range capabilities of LoRaWAN, this thesis selected LoRa and LR-FHSS-based solutions for the modeling. This thesis develops novel Monte Carlo simulation and analytical models for DtS communications performance analysis. The results confirmed the feasibility and potential of both LoRa and LR-FHSS for DtS communications and highlighted the trade-off of different parameter configurations. In summary, LR-FHSS reveals better performance compared to LoRa, primarily due to its high sensitivity, robust Doppler resistance, and increased capacity, making it a suitable choice for DtS communications.
LR-FHSS end devices are expected to be powered by battery, therefore, it is vital to investigate the energy consumption of LR-FHSS. This work conducts experiments using real-life end devices and measures the LR-FHSS air-time and current consumption. We leverage these empirical measurement results to develop analytical models which give us the energy efficiency and battery lifetime of LR-FHSS end devices. LR-FHSS air-time model is highly important for accurate collisions modeling and scalability analysis.Tiivistelmä
Vaikka 5G- ja uudemmissa järjestelmissä on edistytty merkittävästi, nykyiset maanpäälliset verkot eivät ulotu kaikkialle edes maalla, saati avomerellä, jota on 70 prosenttia maapallon pinta-alasta. Tästä erosta voidaan havaita merkittävä digitaalinen kahtiajako. Tulevien langattomien 6G-verkkojen tärkeimpiä vaatimuksia on maailmanlaajuinen kuuluvuus, jotta tähän elintärkeään tarpeeseen voidaan vastata ja yhdistää sekä ihmiset että koneet.
Esitän tässä tutkielmassa, miten massiivisen laitteiden välisen viestinnän (massive machine-type communication, MMTC) ja matalan kiertoradan (low earth orbit, LEO) satelliittien avulla edulliset ja pienitehoiset päätelaitteet voivat saada satelliittiyhteyden ilman maanpäällistä verkkoa. Tämä uusi yhteysmuoto, suora laitteiden välinen satelliittiviestintä (direct-to-satellite, DtS), voi kuroa edellä mainitun digitaalisen kuilun umpeen. DtS-tekniikkaan liittyy kuitenkin mielenkiintoisia haasteita. Haasteena on muun muassa LEO-satelliittien liikkuvuus, mikä aiheuttaa voimakasta Doppler-ilmiötä ja ajassa vaihtelevia kanavan olosuhteita. Samoin yhteyden huomattava pituus (satoja tai tuhansia kilometrejä) ja laaja satelliitin peittoalue aiheuttavat suurta etenemisvaimennusta ja häiriötä tässä järjestyksessä. Lisäksi maanpäällisten päätelaitteiden energiabudjetti on rajallinen. Näin ollen onnistunut DtS:n käyttö edellyttää erinomaista energiatehokkuutta.
LoRaWAN-teknologian pienet tehovaatimukset ja pitkä kantama saivat minut valitsemaan tämän tutkielman mallinnukseen ratkaisut, jotka perustuvat LoRa- ja LR-FHSS-teknologiaan. Kehitän tutkielmassa uusia Monte Carlo -simulaatioita ja analyyttisiä malleja DtS-tietoliikenteen suorituskyvyn analysoimiseksi. Tulosten perusteella sekä LoRa- että LR-FHSS-teknologiassa on potentiaalia ja ne ovat toteuttamiskelpoisia DtS-tiedonsiirtoon. Tulokset myös korostavat erilaisista parametreista seuraavia kompromisseja. Yhteenvetona totean, että LR-FHSS:n suorituskyky oli LoRa-teknologiaa parempi, ensisijaisesti sen suuren herkkyyden, hyvän Doppler-ilmiön siedon ja suuremman kapasiteetin ansiosta, minkä ansiosta se on sopiva DtS-tiedonsiirtoon.
LR-FHSS-päätelaitteet ovat oletusarvoisesti akkukäyttöisiä, joten LR-FHSS-teknologian energiankulutuksen tutkiminen on ehdottoman tärkeää. Tein tässä tutkielmassa kokeita oikeilla päätelaitteilla ja mittasin LR-FHSS-teknologian lähetysaikaa ja virrankulutusta. Sovelsin empiirisiä mittaustuloksia sellaisten analyyttisten mallien kehittämiseen, joilla saatoin päätellä LR-FHSS-päätelaitteiden energiatehokkuuden ja akkukeston. LR-FHSS-lähetysaikamalli on tärkeä työkalu tarkkaan törmäysten mallintamiseen ja skaalautuvuuden analysoimiseen
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
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
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