2,032 research outputs found
Real-Time Recommendation of Streamed Data
This tutorial addressed two trending topics in the field of recommender systems research, namely A/B testing and real-time recommendations of streamed data. Focusing on the news domain, participants learned how to benchmark the performance of stream-based recommendation algorithms in a live recommender system and in a simulated environment
Benchmarking News Recommendations in a Living Lab
Most user-centric studies of information access systems in literature suffer from unrealistic settings or limited numbers of users who participate in the study. In order to address this issue, the idea of a living lab has been promoted. Living labs allow us to evaluate research hypotheses using a large number of users who satisfy their information need in a real context. In this paper, we introduce a living lab on news recommendation in real time. The living lab has first been organized as News Recommendation Challenge at ACM RecSys’13 and then as campaign-style evaluation lab NEWSREEL at CLEF’14. Within this lab, researchers were asked to provide news article recommendations to millions of users in real time. Different from user studies which have been performed in a laboratory, these users are following their own agenda. Consequently, laboratory bias on their behavior can be neglected. We outline the living lab scenario and the experimental setup of the two benchmarking events. We argue that the living lab can serve as reference point for the implementation of living labs for the evaluation of information access systems
Overview of CLEF NEWSREEL 2014: News Recommendations Evaluation Labs
This paper summarises objectives, organisation, and results of the first
news recommendation evaluation lab (NEWSREEL 2014). NEWSREEL targeted
the evaluation of news recommendation algorithms in the form of a campaignstyle
evaluation lab. Participants had the chance to apply two types of evaluation
schemes. On the one hand, participants could apply their algorithms onto a data
set. We refer to this setting as off-line evaluation. On the other hand, participants
could deploy their algorithms on a server to interactively receive recommendation
requests. We refer to this setting as on-line evaluation. This setting ought to reveal
the actual performance of recommendation methods. The competition strived to
illustrate differences between evaluation with historical data and actual users. The
on-line evaluation does reflect all requirements which active recommender systems
face in practise. These requirements include real-time responses and large-scale
data volumes. We present the competition’s results and discuss commonalities
regarding participants’ approaches
Optimizing MapReduce for Highly Distributed Environments
MapReduce, the popular programming paradigm for large-scale data processing,
has traditionally been deployed over tightly-coupled clusters where the data is
already locally available. The assumption that the data and compute resources
are available in a single central location, however, no longer holds for many
emerging applications in commercial, scientific and social networking domains,
where the data is generated in a geographically distributed manner. Further,
the computational resources needed for carrying out the data analysis may be
distributed across multiple data centers or community resources such as Grids.
In this paper, we develop a modeling framework to capture MapReduce execution
in a highly distributed environment comprising distributed data sources and
distributed computational resources. This framework is flexible enough to
capture several design choices and performance optimizations for MapReduce
execution. We propose a model-driven optimization that has two key features:
(i) it is end-to-end as opposed to myopic optimizations that may only make
locally optimal but globally suboptimal decisions, and (ii) it can control
multiple MapReduce phases to achieve low runtime, as opposed to single-phase
optimizations that may control only individual phases. Our model results show
that our optimization can provide nearly 82% and 64% reduction in execution
time over myopic and single-phase optimizations, respectively. We have modified
Hadoop to implement our model outputs, and using three different MapReduce
applications over an 8-node emulated PlanetLab testbed, we show that our
optimized Hadoop execution plan achieves 31-41% reduction in runtime over a
vanilla Hadoop execution. Our model-driven optimization also provides several
insights into the choice of techniques and execution parameters based on
application and platform characteristics
The plista dataset
Releasing datasets has fostered research in fields such as information retrieval and recommender systems. Datasets are typically tailored for specific scenarios. In this work, we present the plista dataset. The dataset contains a collection of news articles published on 13 news portals. Additionally, the dataset comprises user interactions with those articles. We inctroduce the dataset’s main characteristics. Further, we illustrate possible applications of the dataset
Physical Modeling of Process-Machine-Interactions in Micro Machining
Increasing demands for smaller and smarter devices in a variety of applications requires the investigation of process-machine-interactions in micro manufacturing to ensure process results that guarantee part functionality. One approach is the use of simulation-based physical models. In this contribution, methods for the physical modeling of high-precision air bearing and magnetic bearing spindles are presented in addition to a kinematic model of the micro milling process. Both models are superimposed in order to carry out investigations of the slot bottom surface roughness in micro end milling. The results show that process-machine-interactions in micro manufacturing can be modeled by the superposition of a physical model of the machine tool spindle taking cutting forces into consideration and a purely kinematic model of the machining process, providing the necessary tools for a variety of further investigations into process-machine-interactions in micro manufacturing
Advanced Development of Space Photovoltaic Concentrators Using Robust Lenses, Multi-Junction Cells, and Graphene Radiators
At the past three PVSCs, our team has presented recent advances in our space photovoltaic concentrator technology. In the past year, under multiple NASA-funded research and technology development programs, our team has made much additional progress in the advanced development of space photovoltaic concentrators. New robust Fresnel lenses, new high-efficiency multi-junction cells, and new graphene radiators have been developed. The paper will present the latest advances in this technology
PHASES High Precision Differential Astrometry of delta Equulei
delta Equulei is among the most well-studied nearby binary star systems.
Results of its observation have been applied to a wide range of fundamental
studies of binary systems and stellar astrophysics. It is widely used to
calibrate and constrain theoretical models of the physics of stars. We report
27 high precision differential astrometry measurements of delta Equulei from
the Palomar High-precision Astrometric Search for Exoplanet Systems (PHASES).
The median size of the minor axes of the uncertainty ellipses for these
measurements is 26 micro-arcseconds. These data are combined with previously
published radial velocity data and other previously published differential
astrometry measurements using other techniques to produce a combined model for
the system orbit. The distance to the system is determined to within a
twentieth of a parsec and the component masses are determined at the level of a
percent. The constraints on masses and distance are limited by the precisions
of the radial velocity data; we outline plans improve this deficiency and
discuss the outlook for further study of this binary.Comment: Accepted by AJ. Complete versions of tables 2-7 now available at
http://stuff.mit.edu/~matthew1/deltaEquTables/ (removed from astroph server
JWST reveals a population of ultra-red, flattened disk galaxies at 2<z<6 previously missed by HST
With just a month of data, JWST is already transforming our view of the
Universe, revealing and resolving starlight in unprecedented populations of
galaxies. Although ``HST-dark" galaxies have previously been detected at long
wavelengths, these observations generally suffer from a lack of spatial
resolution which limits our ability to characterize their sizes and
morphologies. Here we report on a first view of starlight from a subset of the
HST-dark population that are bright with JWST/NIRCam (4.4m<24.5mag) and
very faint or even invisible with HST (1.6m). In this Letter we focus
on a dramatic and unanticipated population of physically extended galaxies
(0.17''). These 12 galaxies have photometric redshifts , high
stellar masses , and significant
dust-attenuated star formation. Surprisingly, the galaxies have elongated
projected axis ratios at 4.4m, suggesting that the population is
disk-dominated or prolate. Most of the galaxies appear red at all radii,
suggesting significant dust attenuation throughout. We refer to these red,
disky, HST-dark galaxies as Ultra-red Flattened Objects (UFOs). With
(F444W)~kpc, the galaxies are similar in size to compact massive
galaxies at and the cores of massive galaxies and S0s at . The
stellar masses, sizes, and morphologies of the sample suggest that some could
be progenitors of lenticular or fast-rotating galaxies in the local Universe.
The existence of this population suggests that our previous censuses of the
universe may have missed massive, dusty edge-on disks, in addition to
dust-obscured starbursts
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