1,720,967 research outputs found
Techno-economic and environmental analysis for off-grid mobile base stations electrification with hybrid power system in Tanzania
No full textJournal articleBase stations (BSs) are essential in cellular networks. Lack of access to reliable electricity in mobile
communication systems is a major economic and environmental concern for service delivery in Tanzania. Mobile
network operators (MNOs) use diesel generators (DG) to power their BSs which are costly and high greenhouse gases
(GHG) emissions. In this paper, we investigate challenges hindering the use of renewable energy (RE) by MNOs. We
provide a techno-economic analysis for using a hybrid power system (HPS) comprising of DG and RE. In technoeconomic
analysis, we considered solar, wind, battery, and DG in different configurations. The systems were simulated
in HOMER to get the optimized model suitable for the BS sites. Results show that the solar/DG/Battery and the
solar/wind/DG/Battery provide optimal solution susceptible to satisfy the needs. Although HPS suffers from the high
initial cost, the results are satisfactory. The analysis indicates a reduction of net present cost (NPC) by 54%, cost of
energy (COE) by more than 50%, and the GHG emissions for about 88%
Techno-economic and environmental analysis for off-grid mobile base stations electrification with hybrid power system in Tanzania
No full textJournal articleBase stations (BSs) are essential in cellular networks. Lack of access to reliable electricity in mobile
communication systems is a major economic and environmental concern for service delivery in Tanzania. Mobile
network operators (MNOs) use diesel generators (DG) to power their BSs which are costly and high greenhouse gases
(GHG) emissions. In this paper, we investigate challenges hindering the use of renewable energy (RE) by MNOs. We
provide a techno-economic analysis for using a hybrid power system (HPS) comprising of DG and RE. In technoeconomic
analysis, we considered solar, wind, battery, and DG in different configurations. The systems were simulated
in HOMER to get the optimized model suitable for the BS sites. Results show that the solar/DG/Battery and the
solar/wind/DG/Battery provide optimal solution susceptible to satisfy the needs. Although HPS suffers from the high
initial cost, the results are satisfactory. The analysis indicates a reduction of net present cost (NPC) by 54%, cost of
energy (COE) by more than 50%, and the GHG emissions for about 88%
Capabilities of smart antenna in tracking the desired signal in wireless communication system through non-blind adaptive algorithms
No full textArticleFuture wireless systems will require higher data rates with better coverage for a wide variety of users
operating with a large variety of different systems. To achieve these goals, greater power, interference suppression, and
multipath mitigation are needed. Smart antenna gives a promising future for wireless communication systems since it
can improve the capacity, extend coverage and provide better quality services by tracking users, switching beams
accordingly. In this paper three non-blind adaptive beamforming algorithms, least mean square (LMS), Recursive Least
square (RLS) and Sample matrix inversion (SMI) have been studied. Investigation of their performances in tracking a
desired user has been made and compared. All the three algorithms direct their beams towards a desired user and place
nulls towards interferer. However the rate of their performance differs from each other
Resources allocation and sharing in wireless virtual networks
No full textJournal articleThe rapid growth of the mobile devices and its services being experienced in a recent years brought both
challenges and opportunities in the wireless network systems. The scarcity of the resources, high capital and
operational costs are among the challenges facing the provision of the growing mobile services. The development of
wireless network virtualization brought hope for the future networks to fulfil the users’ demands. It allows different
service providers to share the same physical infrastructure which in return, reduces both capital expenses (CAPEX) and
operational expenses (OPEX). In this paper, the framework for wireless network virtualization is proposed. Also, the
detailed description of the model based on the software define network (SDN) architecture is presented. On top of that
we have proposed a load based resources sharing approach among the virtual networks (VNs). Our proposed approach
has shown that, through sharing the excess resources, the VNs can significantly minimize unnecessary cost and utilize
the available resources effectively
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Resources allocation and sharing in wireless virtual networks
No full textJournal articleThe rapid growth of the mobile devices and its services being experienced in a recent years brought both
challenges and opportunities in the wireless network systems. The scarcity of the resources, high capital and
operational costs are among the challenges facing the provision of the growing mobile services. The development of
wireless network virtualization brought hope for the future networks to fulfil the users’ demands. It allows different
service providers to share the same physical infrastructure which in return, reduces both capital expenses (CAPEX) and
operational expenses (OPEX). In this paper, the framework for wireless network virtualization is proposed. Also, the
detailed description of the model based on the software define network (SDN) architecture is presented. On top of that
we have proposed a load based resources sharing approach among the virtual networks (VNs). Our proposed approach
has shown that, through sharing the excess resources, the VNs can significantly minimize unnecessary cost and utilize
the available resources effectively
Variations on the Author
Full text link“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
Full text linkWe 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
Full text linkWe 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
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