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1915 research outputs found
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Empirical Comparison of Graph-based Recommendation Engines for an Apps Ecosystem
Get PDFRecommendation engines (RE) are becoming highly popular, e.g., in the area of e-commerce. A RE offers new items (products or content) to users based on their profile and historical data. The most popular algorithms used in RE are based on collaborative filtering. This technique makes recommendations based on the past behavior of other users and the similarity between users and items. In this paper we have evaluated the performance of several RE based on the properties of the networks formed by users and items. The RE use in a novel way graph theoretic concepts like edges weights or network flow. The evaluation has been conducted in a real environment (ecosystem) for recommending apps to smartphone users. The analysis of the results allows concluding that the effectiveness of a RE can be improved if the age of the data, and if a global view of the data is considered. It also shows that graph-based RE are effective, but more experiments are required for a more accurate characterization of their properties.pu
MONROE: Measuring Mobile Broadband Networks in Europe
Get PDFThere is a strong need for objective data about stability and
performance of Mobile Broadband (MBB) networks, and
for tools to rigorously and scientifically assess their performance. In particular, it is important to measure and understand the quality as experienced by the end user. Such information is very valuable for many parties including operators, regulators and policy makers, consumers and society at large, businesses whose services depend on MBB
networks, researchers and innovators. In this paper, we introduce the MONROE measurement platform aimed to address this need. MONROE is an open, European-scale,
and flexible platform with multi-homing capabilities to run
experiments on operational 3G/4G Mobile Broadband networks. The MONROE platform enables accurate, realistic
and meaningful monitoring and assessment of the performance of MBB networks. MONROE also provides WiFi
connectivity mimicking multi-homing in smartphones with
both MBB and WiFi interfaces, to allow experimenting on
different access technologies as well as to explore new ways
of combining them to increase performance and robustness.TRUEpu
Improving resource location with locally precomputed partial random walks
Get PDFRandom walks can be used to search complex networks for a desired resource. To reduce search lengths, we propose a mechanism based on building random walks connecting together partial walks (PW) previously computed at each network node. Resources found in each PW are registered. Searches can then jump over PWs where the resource is not located. However, we assume that perfect recording of resources may be costly, and hence, probabilistic
structures like Bloom filters are used. Then, unnecessary hops may come from false positives at the Bloom filters. Two variations of this mechanism have been considered, depending on whether we first choose a PW in the current node and then check it for the resource, or we first check all PWs and then choose one.
In addition, PWs can be either simple random walks or self-avoiding random walks. Analytical models are provided to predict expected search lengths and other magnitudes of the resulting four mechanisms. Simulation experiments validate these predictions and allow us to compare these techniques with simple random walk searches, finding very large reductions of expected search lengths.pu
A Realistic Evaluation and Comparison of Indoor Location Technologies: Experiences and Lessons Learned
Get PDFWe present the results, experiences and lessons learned from
comparing a diverse set of technical approaches to indoor
localization during the 2014 Microsoft Indoor Localization
Competition. 22 different solutions to indoor localization
from different teams around the world were put to test in
the same unfamiliar space over the course of 2 days, allowing us to directly compare the accuracy and overhead of various technologies. In this paper, we provide a detailed analysis of the evaluation study’s results, discuss the current state-ofthe-art in indoor localization, and highlight the areas that, based on our experience from organizing this event, need to be improved to enable the adoption of indoor location services.TRUEpu
Diseño e Implementación de un Módulo de Analítica de Aprendizaje, y su Aplicación para la Evaluación de Experiencias Educativas [Design and Implementation of a Learning Analytics Module, and its Application for Evaluating Educational Experiences]
No full textMost e-learning platforms are able to collect
large datasets of students’ interactions as events; however that data is difficult to be interpreted directly by learning stakeholders. In this work we unify and connect several of our previous research studies giving a general context of our learning analytics research on Khan Academy. We propose a set of interesting indicators in order to learn more about the learning process. Furthermore, we have designed and implemented a learning analytics module called ALAS-KA which displays individual and class visualizations for these parameters. Finally we make use of ALAS-KA and the parameters to evaluate learning experiences.TRUEpu
Efficient Networking in Millimeter Wave Bands
No full textState-of-the-art wireless communication already operates close to Shannon capacity and one of the most promising options to further increase data rates is to increase the communication bandwidth. Very high bandwidth channels are only available in the extremely high frequency part of the radio spectrum, the millimeter wave band (mm-wave). Upcoming communication technologies, such as IEEE 802.11ad, are already starting to exploit this part of the radio spectrum to achieve data rates of several GBit/s. However, communication at such high frequencies also suffers from high attenuation and signal absorption, often restricting communication to line-of-sight (LOS) scenarios and requiring the use of highly directional antennas. This in turn requires a radical rethinking of wireless network design. On the one hand side, such channels experience little interference, allowing for a high degree of spatial reuse and potentially simpler MAC and interference management mechanisms. On the other hand, such an environment is extremely dynamic and channels may appear and disappear over very short time intervals, in particular for mobile devices. This talk will highlight some of the challenges of and possible approaches for networking in the mm-wave band.TRUEpu
Quantifying the Economic and Cultural Biases of Social Media through Trending Topic
Get PDFOnline social media has recently irrupted as the last major venue for the propagation of news and cultural content, competing with traditional mass media and allowing citizens
to access new sources of information. In this paper, we study collectively filtered news and popular content in Twitter, known as Trending Topics (TTs), to quantify the extent to which they show similar biases known for mass media. We use two datasets collecte in 2013 and 2014, including more than 300.000 TTs from 62 countries. The existing patterns of leader-follower relationships among countries reveal systemic biases known for mass media: Countries concentrate their attention to small groups of other countries, generating a pattern of centralization in which TTs follow the gradient of wealth across
countries. At the same time, we find subjective biases within language communities linked to the cultural similarity of countries, in which countries with closer cultures and shared languages tend to follow each others' TTs. Moreover, using a novel methodology based on the Google News service, we study the influence of mass media in TTs for four countries. We find that roughly half of the TTs in Twitter overlap with news reported by mass media, and that the rest of TTs are more likely to spread internationally within Twitter. Our results confirm that online social media have the power to independently spread content beyond mass media, but at the same time social media content follows economic incentives and is subject to cultural factors and language barriers.pu
The Segment Routing Architecture
Get PDFNetwork operators anticipate the offering of an increasing variety of cloud-based services with stringent Service Level Agreements. Technologies currently supporting IP networks however lack the flexibility and scalability properties to realize such evolution. In this article, we present Segment Routing (SR), a new network architecture aimed at filling this gap, driven by usecases defined by network operators. SR implements the source routing and tunneling paradigms, letting nodes steer packets over paths using a sequence of instructions (segments) placed in the packet header. As such, SR allows the implementation of routing policies without per-flow entries at intermediate routers.
This paper introduces the SR architecture, describes its related ongoing standardization efforts, and reviews the main use-cases envisioned by network operators.TRUEpu
On a Cloud-Controlled Architecture for Device-to-Device Content Distribution
Get PDFIt has been shown that the distribution of popular content can benefit from solutions that dynamically distribute copies of the content from the backend to a subset of subscribed users, and let these users spread the content with opportunistic communication. In this work, we study with an experimental analysis how cloud computing could help to disseminate the popular content for the above scenario. We design an architecture for cloud-based controller of content deliveries, and we investigate strategies for delivering the content with the cloud logic. We implement our system using Microsoft Azure cloud service and building a video application running on commodity smartphone. We experimentally compare different strategies and show that solutions controlled by the cloud are more efficient in terms of traffic offload than approaches without cloud logic, and that practical challenges are solved by our approach that were not considered in former analytical works.TRUEpu
Using Video Visualizations in Open edX to Understand Learning Interactions of Students
Get PDFThe emergence of Massive Open Online Courses (MOOCs) has
caused a high disrupting effect on online education. One of the most extended MOOC platforms is Open edX. There is a demanding necessity by the instructors and students of these courses to provide timely analytics tools that can help understand the learning process at any moment. In this direction we have developed the Add-on of learNing AnaLYtics Support for open Edx (ANALYSE), which is our learning analytics contribution for Open edX. In this demonstration paper we will provide guidelines on how to use some of the ANALYSE video visualizations in order to detect problems in video resources, so that the learning
process can be improved.TRUEpu