4,244 research outputs found
Deep Learning based Recommender System: A Survey and New Perspectives
With the ever-growing volume of online information, recommender systems have
been an effective strategy to overcome such information overload. The utility
of recommender systems cannot be overstated, given its widespread adoption in
many web applications, along with its potential impact to ameliorate many
problems related to over-choice. In recent years, deep learning has garnered
considerable interest in many research fields such as computer vision and
natural language processing, owing not only to stellar performance but also the
attractive property of learning feature representations from scratch. The
influence of deep learning is also pervasive, recently demonstrating its
effectiveness when applied to information retrieval and recommender systems
research. Evidently, the field of deep learning in recommender system is
flourishing. This article aims to provide a comprehensive review of recent
research efforts on deep learning based recommender systems. More concretely,
we provide and devise a taxonomy of deep learning based recommendation models,
along with providing a comprehensive summary of the state-of-the-art. Finally,
we expand on current trends and provide new perspectives pertaining to this new
exciting development of the field.Comment: The paper has been accepted by ACM Computing Surveys.
https://doi.acm.org/10.1145/328502
An Axiomatic Analysis of Diversity Evaluation Metrics: Introducing the Rank-Biased Utility Metric
Many evaluation metrics have been defined to evaluate the effectiveness
ad-hoc retrieval and search result diversification systems. However, it is
often unclear which evaluation metric should be used to analyze the performance
of retrieval systems given a specific task. Axiomatic analysis is an
informative mechanism to understand the fundamentals of metrics and their
suitability for particular scenarios. In this paper, we define a
constraint-based axiomatic framework to study the suitability of existing
metrics in search result diversification scenarios. The analysis informed the
definition of Rank-Biased Utility (RBU) -- an adaptation of the well-known
Rank-Biased Precision metric -- that takes into account redundancy and the user
effort associated to the inspection of documents in the ranking. Our
experiments over standard diversity evaluation campaigns show that the proposed
metric captures quality criteria reflected by different metrics, being suitable
in the absence of knowledge about particular features of the scenario under
study.Comment: Original version: 10 pages. Preprint of full paper to appear at
SIGIR'18: The 41st International ACM SIGIR Conference on Research &
Development in Information Retrieval, July 8-12, 2018, Ann Arbor, MI, USA.
ACM, New York, NY, US
Retrieve Anything To Augment Large Language Models
Large language models (LLMs) face significant challenges stemming from their
inherent limitations in knowledge, memory, alignment, and action. These
challenges cannot be addressed by LLMs alone, but should rely on assistance
from the external world, such as knowledge base, memory store, demonstration
examples, and tools. Retrieval augmentation stands as a vital mechanism for
bridging the gap between LLMs and the external assistance. However,
conventional methods encounter two pressing issues. On the one hand, the
general-purpose retrievers are not properly optimized for the retrieval
augmentation of LLMs. On the other hand, the task-specific retrievers lack the
required versatility, hindering their performance across the diverse retrieval
augmentation scenarios.
In this work, we present a novel approach, the LLM-Embedder, which
comprehensively supports the diverse retrieval augmentation needs of LLMs with
one unified embedding model. Training such a unified model is non-trivial, as
various retrieval tasks aim to capture distinct semantic relationships, often
subject to mutual interference. To address this challenge, we systematically
optimize our training methodology. This includes reward formulation based on
LLMs' feedback, the stabilization of knowledge distillation, multi-task
fine-tuning with explicit instructions, and homogeneous in-batch negative
sampling. These optimization strategies contribute to the outstanding empirical
performance of the LLM-Embedder. Notably, it yields remarkable enhancements in
retrieval augmentation for LLMs, surpassing both general-purpose and
task-specific retrievers in various evaluation scenarios. Our checkpoint and
source code are publicly available at
https://github.com/FlagOpen/FlagEmbedding
Experience-driven Control For Networking And Computing
Modern networking and computing systems have become very complicated and highly dynamic, which makes them hard to model, predict and control. In this thesis, we aim to study system control problems from a whole new perspective by leveraging emerging Deep Reinforcement Learning (DRL), to develop experience-driven model-free approaches, which enable a network or a device to learn the best way to control itself from its own experience (e.g., runtime statistics data) rather than from accurate mathematical models, just as a human learns a new skill (e.g., driving, swimming, etc). To demonstrate the feasibility and superiority of this experience-driven control design philosophy, we present the design, implementation, and evaluation of multiple DRL-based control frameworks on two fundamental networking problems, Traffic Engineering (TE) and Multi-Path TCP (MPTCP) congestion control, as well as one cutting-edge application, resource co-scheduling for Deep Neural Network (DNN) models on mobile and edge devices with heterogeneous hardware.
We first propose DRL-TE, a DRL-based framework that enables experience-driven networking for TE. DRL-TE maximizes a widely-used utility function by jointly learning network environment and its dynamics, and making decisions under the guidance of powerful DNNs. We propose two new techniques, TE-aware exploration and actor-critic-based prioritized experience replay, to optimize the general DRL framework particularly for TE. Furthermore, we propose an Actor-Critic-based Transfer learning framework for TE, ACT-TE, which solves a practical problem in experience-driven networking: when network configurations are changed, how to train a new DRL agent to effectively and quickly adapt to the new environment. In the new network environment, ACT-TE leverages policy distillation to rapidly learn a new control policy from both old knowledge (i.e., distilled from the existing agent) and new experience (i.e., newly collected samples).
In addition, we propose DRL-CC to enable experience-driven congestion control for MPTCP. DRL-CC utilizes a single (instead of multiple independent) DRL agent to dynamically and jointly perform congestion control for all active MPTCP flows on an end host with the objective of maximizing the overall utility. The novelty of our design is to utilize a flexible recurrent neural network, LSTM, under a DRL framework for learning a representation for all active flows and dealing with their dynamics. Moreover, we integrate the above LSTM-based representation network into an actor-critic framework for continuous congestion control, which applies the deterministic policy gradient method to train actor, critic, and LSTM networks in an end-to-end manner.
With the emergence of more and more powerful chipsets and hardware and the rise of Artificial Intelligence of Things (AIoT), there is a growing trend for bringing DNN models to empower mobile and edge devices with intelligence such that they can support attractive AI applications on the edge in a real-time or near real-time manner. To leverage heterogeneous computational resources (such as CPU, GPU, DSP, etc) to effectively and efficiently support concurrent inference of multiple DNN models on a mobile or edge device, in the last part of this thesis, we propose a novel experience-driven control framework for resource co-scheduling, which we call COSREL. COSREL has the following desirable features: 1) it achieves significant speedup over commonly-used methods by efficiently utilizing all the computational resources on heterogeneous hardware; 2) it leverages DRL to make dynamic and wise online scheduling decisions based on system runtime state; 3) it is capable of making a good tradeoff among inference latency, throughput and energy efficiency; and 4) it makes no changes to given DNN models, thus preserves their accuracies.
To validate and evaluate the proposed frameworks, we conduct extensive experiments on packet-level simulation (for TE), testbed with modified Linux kernel (for MPTCP), and off-the-shelf Android devices (for resource co-scheduling). The results well justify the effectiveness of these frameworks, as well as their superiority over several baseline methods
From Knowledge Augmentation to Multi-tasking: Towards Human-like Dialogue Systems
The goal of building dialogue agents that can converse with humans naturally
has been a long-standing dream of researchers since the early days of
artificial intelligence. The well-known Turing Test proposed to judge the
ultimate validity of an artificial intelligence agent on the
indistinguishability of its dialogues from humans'. It should come as no
surprise that human-level dialogue systems are very challenging to build. But,
while early effort on rule-based systems found limited success, the emergence
of deep learning enabled great advance on this topic.
In this thesis, we focus on methods that address the numerous issues that
have been imposing the gap between artificial conversational agents and
human-level interlocutors. These methods were proposed and experimented with in
ways that were inspired by general state-of-the-art AI methodologies. But they
also targeted the characteristics that dialogue systems possess.Comment: PhD thesi
Tracer Applications of Noble Gas Radionuclides in the Geosciences
The noble gas radionuclides, including 81Kr (half-life = 229,000 yr), 85Kr
(11 yr), and 39Ar (269 yr), possess nearly ideal chemical and physical
properties for studies of earth and environmental processes. Recent advances in
Atom Trap Trace Analysis (ATTA), a laser-based atom counting method, have
enabled routine measurements of the radiokrypton isotopes, as well as the
demonstration of the ability to measure 39Ar in environmental samples. Here we
provide an overview of the ATTA technique, and a survey of recent progress made
in several laboratories worldwide. We review the application of noble gas
radionuclides in the geosciences and discuss how ATTA can help advance these
fields, specifically determination of groundwater residence times using 81Kr,
85Kr, and 39Ar; dating old glacial ice using 81Kr; and an 39Ar survey of the
main water masses of the oceans, to study circulation pathways and estimate
mean residence times. Other scientific questions involving deeper circulation
of fluids in the Earth's crust and mantle also are within the scope of future
applications. We conclude that the geoscience community would greatly benefit
from an ATTA facility dedicated to this field, with instrumentation for routine
measurements, as well as for research on further development of ATTA methods
Recommended from our members
Workshop Report: Developing a Research Agenda for the Energy Water Nexus
The
energy
water
nexus
has
attracted
public
scrutiny
because
of
the
concerns
about
their
interdependence
and
the
possibility
for
cascading
vulnerabilities
from
one
system
to
the
other.
There
are
trends
toward
more
water-‐intensive
energy
(such
as
biofuels
,
unconventional
oil
and
gas
production,
and
regulations
driving
more
water
consumption
for
thermoelectric
power
production
)
and
more
energy-‐intensive
water
(such
as
desalination,
or
deeper
ground
water
pumping
and
production).
In
addition
demographic
trends
of
population
and
economic
growth
will
likely
drive
up
total
and
per
capita
water
and
energy
demand,
and
due
to
climate
change
related
distortions
of
the
hydrologic
cycle,
it
is
expected
that
the
existing
interdependencies
will
be
come
even
more
of
a
concern.
Therefore,
developing
a
research
agenda
and
strategy
to
mitigate
potential
vulnerabilities
and
to
meet
economic
and
environmental
targets
for
efficiently
using
energy
and
water
would
be
very
worthwhile.
To
address
these
concerns,
the
National
Science
Foundation
(NSF)
sponsored
a
workshop
on
June
10-‐11,
2013
in
Arlington,
VA
(at
NSF
headquarters)
to
bring
together
technical,
academic,
and
industry
experts
from
across
the
country
to
help
develop
such
a
research
agenda.
The
workshop
was
sponsored
by
NSF
Grant
Number
CBET
1341032
from
the
Division
of
Chemical,
Bioengineering,
Environmental
and
Transport
Systems.
Supporting
programs
were:
Thermal
Transport
Processes,
Environmental
Sustainability,
and
Environmental
Engineering.Center for Research in Water Resource
Heterogeneous resource management in energy hubs with self-consumption: Contributions and application example
The energy hub concept and modeling methodology are widely employed tools for solving resource conversionand storage scheduling problems. For instance, industrial clusters might benefit from determining the suitabletime to operate their facilities and to sell electricity to the public power grid, according to legal, economic orenvironmental factors. In this paper, novel elements are introduced in order to more accurately represent realplants and to reduce the amount of decision variables. The major innovation is to consider devices consuming aresource which is not related to the quantity of output produced, by attaching binary decision variables tocertain energy hub outputs. Secondly, a path vector is defined to take into account the flows of resources withinthe system instead of employing a variable for each branch between the components. The third innovationconsists of an additional vector to express the amount of output resources sold from the energy hub, includingconstraints for those resources which are exported and imported through the same medium. An extended energyhub model is first proposed and then applied to a real plant example, including multiple and heterogeneousresources and performing a comparison between days with different demands, weather conditions and electricityprices. The results obtained in the selected scenarios demonstrate a logical operation scheduling, and thereforevalidate the proposed approach
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