scholarly journals Comparative Analysis of the Circle Fitting Empirical Method and the International Telecommunication Union Parabola Fitting Method for Determination of the Radius of Curvature for Rounded Edge Diffraction Obstruction

2018 ◽  
Vol 7 (24) ◽  
pp. 16-21
Author(s):  
Simeon Ozuomba ◽  
Constant Kalu ◽  
Henry Johnson
Keyword(s):  
Comparative Analysis ◽  
Empirical Method ◽  
Radius Of Curvature ◽  
Circle Fitting ◽  
International Telecommunication Union ◽  
International Telecommunication ◽  
Edge Diffraction ◽  
Fitting Method

On the Determination of a Compensation Model for Rain Degraded Digital DTH Links over a Tropical Location

2019 ◽  
Vol 1 (1) ◽  
Author(s):  
O.O. Obiyemi
Keyword(s):  
Distribution Channel ◽  
Cost Effective ◽  
Digital Television ◽  
Signal Loss ◽  
Signal Attenuation ◽  
International Telecommunication Union ◽  
Satellite Television ◽  
Compensation Model ◽  
International Telecommunication

Ku-band satellite remains the most cost-effective distribution channel for digital television services in terms of global coverage and wide bandwidth availability. However, signal attenuation due to rain remains the bane of the reception quality and the continuous availability. In the clear-sky, the minimum signal loss between a Ku-satellite and an earth station is about 205 dB. The amount of rain rate and the site’s latitude further compound this minimum signal attenuation. Existing reported research works are mainly limited to modelling of rain-induced attenuation without porting research findings into compensation product in terms of appropriate mitigation technique. This study is aimed at developing a robust compensation model for the rain-induced digital satellite television services for an improved quality and availability of service in Nigeria, with a specific objective of determining the optimal dish size for compensating the signal attenuation on the digital satellite TV downlink. The methodology employed involves rain data collection from the International Telecommunication Union-Radiocommunication (ITU-R) worst rain zone in Nigeria. The determination of appropriate dish sizes for different parts of Nigeria was carried out. A compensation model was derived for the rain degraded DTH link; and practical dish size of 1.5 m, for 48 dBW satellite footprint, was found to be adequate for compensating Ku satellite signal attenuation, regardless of rainstorm in Nigeria.

scholarly journals The graph neural networking challenge

2021 ◽  
Vol 51 (3) ◽  
pp. 9-16
Author(s):  
José Suárez-Varela ◽  
Miquel Ferriol-Galmés ◽  
Albert López ◽  
Paul Almasan ◽  
Guillermo Bernárdez ◽  
...  
Keyword(s):  
Machine Learning ◽  
Computer Networks ◽  
Real World ◽  
Large Scale ◽  
Lessons Learned ◽  
Educational Resources ◽  
Global Competition ◽  
International Telecommunication Union ◽  
International Telecommunication ◽  
Broad Audience

During the last decade, Machine Learning (ML) has increasingly become a hot topic in the field of Computer Networks and is expected to be gradually adopted for a plethora of control, monitoring and management tasks in real-world deployments. This poses the need to count on new generations of students, researchers and practitioners with a solid background in ML applied to networks. During 2020, the International Telecommunication Union (ITU) has organized the "ITU AI/ML in 5G challenge", an open global competition that has introduced to a broad audience some of the current main challenges in ML for networks. This large-scale initiative has gathered 23 different challenges proposed by network operators, equipment manufacturers and academia, and has attracted a total of 1300+ participants from 60+ countries. This paper narrates our experience organizing one of the proposed challenges: the "Graph Neural Networking Challenge 2020". We describe the problem presented to participants, the tools and resources provided, some organization aspects and participation statistics, an outline of the top-3 awarded solutions, and a summary with some lessons learned during all this journey. As a result, this challenge leaves a curated set of educational resources openly available to anyone interested in the topic.

scholarly journals A line-of-sight channel model for the 100–450 gigahertz frequency band

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Joonas Kokkoniemi ◽  
Janne Lehtomäki ◽  
Markku Juntti
Keyword(s):  
Channel Model ◽  
Full Range ◽  
Line Of Sight ◽  
Absorption Loss ◽  
Radio Communication ◽  
International Telecommunication Union ◽  
International Telecommunication ◽  
Fifth Generation ◽  
Proposed Model ◽  
Actual Response

AbstractThis paper documents a simple parametric polynomial line-of-sight channel model for 100–450 GHz band. The band comprises two popular beyond fifth generation (B5G) frequency bands, namely, the D band (110–170 GHz) and the low-THz band (around 275–325 GHz). The main focus herein is to derive a simple, compact, and accurate molecular absorption loss model for the 100–450 GHz band. The derived model relies on simple absorption line shape functions that are fitted to the actual response given by complex but exact database approach. The model is also reducible for particular sub-bands within the full range of 100–450 GHz, further simplifying the absorption loss estimate. The proposed model is shown to be very accurate by benchmarking it against the exact response and the similar models given by International Telecommunication Union Radio Communication Sector. The loss is shown to be within ±2 dBs from the exact response for one kilometer link in highly humid environment. Therefore, its accuracy is even much better in the case of usually considered shorter range future B5G wireless systems.

Reflections on Arctic Maritime Delimitations: A Comparative Analysis between the Case Law and State Practice

2011 ◽  
Vol 80 (4) ◽  
pp. 459-484
Author(s):  
Yoshifumi Tanaka
Keyword(s):  
Comparative Analysis ◽  
Arctic Ocean ◽  
Case Law ◽  
The Arctic ◽  
Coastal State ◽  
Ocean Governance ◽  
State Practice ◽  
The Arctic Ocean

AbstractThe determination of spatial ambit of the coastal State jurisdiction is fundamental for ocean governance and the same applies to the Arctic Ocean. In this regard, a question arises how it is possible to delimit marine spaces where the jurisdiction of two or more coastal States overlaps. Without rules on maritime delimitation in marine spaces where the jurisdiction of coastal States overlaps, the legal uses of these spaces cannot be enjoyed effectively. In this sense, maritime delimitation is of paramount importance in the Arctic Ocean governance. Thus, this study will examine Arctic maritime delimitations by comparing them to the case law concerning maritime delimitation. In so doing, this study seeks to clarify features of Arctic maritime delimitations.

Duplex Spread Blade Method for Cutting Hypoid Gears with Modified Tooth Surface

1998 ◽  
Vol 120 (3) ◽  
pp. 441-447 ◽  
Author(s):  
K. Kawasaki ◽  
H. Tamura
Keyword(s):  
Cutting Edge ◽  
Tooth Surface ◽  
Radius Of Curvature ◽  
Large Radius ◽  
Ring Gear ◽  
Circular Arc ◽  
Hypoid Gears ◽  
Manufacturing Method ◽  
Straight Line

In this paper, a duplex spread blade method for cutting hypoid gears with modified tooth surface is proposed. The duplex spread blade method provides a rapid and economical manufacturing method because both the ring gear and pinion are cut by a spread blade method. In the proposed method, the nongenerated ring gear is manufactured with cutting edge that is altered from the usual straight line to a circular arc with a large radius of curvature and the circular arc cutting edge produces a modified tooth surface. The pinion is generated by a cutter with straight cutting edges as usual. The main procedure of this method is the determination of the cutter specifications and machine settings. The proposed method was validated by gear manufacture.

scholarly journals RESEARCH INTO THE METHODS OF ANALYSING THE PRODUCTIVITY INDICATORS OF TRANSPORT TERMINALS

Transport ◽  
2009 ◽  
Vol 24 (3) ◽  
pp. 192-199 ◽  
Author(s):  
Ilona Jaržemskienė
Keyword(s):  
Comparative Analysis ◽  
Functional Dependence ◽  
Data Envelopment ◽  
Analysis Method ◽  
Accurate Evaluation ◽  
Feasible Alternative ◽  
Productivity Indicators ◽  
Insight Into ◽  
Regressive Analysis

The measurement of terminal productivity is the issue of extreme importance to both terminal owners and management and customers. As the sector of transport is highly intensive in terms of investments into the infrastructure, the productivity of a terminal may play a crucial role in competing with other terminals. Productivity is defined in terms of inputs and output. The majority of the available studies, wherein this issue is addressed, are generally focused on the determination of functional dependence between inputs and output using the method of regressive analysis. The present article provides an insight into the Data Envelopment Analysis method as a tool for measuring productivity. This technique enables a rather accurate evaluation of terminal productivity by means of comparative analysis, which, in fact, appears to be the only feasible alternative in cases where statistic data required for performing regressive analysis is lacking.

Determination of Coefficient of Radial Consolidation Using Steepest Tangent Fitting Method

2010 ◽  
Vol 28 (4) ◽  
pp. 533-536 ◽  
Author(s):  
J. S. Vinod ◽  
A. Sridharan ◽  
Buddhima Indraratna
Keyword(s):  
Fitting Method
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