104 research outputs found
CRUC: Cold-start Recommendations Using Collaborative Filtering in Internet of Things
The Internet of Things (IoT) aims at interconnecting everyday objects
(including both things and users) and then using this connection information to
provide customized user services. However, IoT does not work in its initial
stages without adequate acquisition of user preferences. This is caused by
cold-start problem that is a situation where only few users are interconnected.
To this end, we propose CRUC scheme - Cold-start Recommendations Using
Collaborative Filtering in IoT, involving formulation, filtering and prediction
steps. Extensive experiments over real cases and simulation have been performed
to evaluate the performance of CRUC scheme. Experimental results show that CRUC
efficiently solves the cold-start problem in IoT.Comment: Elsevier ESEP 2011: 9-10 December 2011, Singapore, Elsevier Energy
Procedia, http://www.elsevier.com/locate/procedia/, 201
CSWA: Aggregation-Free Spatial-Temporal Community Sensing
In this paper, we present a novel community sensing paradigm -- {C}ommunity
{S}ensing {W}ithout {A}ggregation}. CSWA is designed to obtain the environment
information (e.g., air pollution or temperature) in each subarea of the target
area, without aggregating sensor and location data collected by community
members. CSWA operates on top of a secured peer-to-peer network over the
community members and proposes a novel \emph{Decentralized Spatial-Temporal
Compressive Sensing} framework based on \emph{Parallelized Stochastic Gradient
Descent}. Through learning the \emph{low-rank structure} via distributed
optimization, CSWA approximates the value of the sensor data in each subarea
(both covered and uncovered) for each sensing cycle using the sensor data
locally stored in each member's mobile device. Simulation experiments based on
real-world datasets demonstrate that CSWA exhibits low approximation error
(i.e., less than C in city-wide temperature sensing task and
units of PM2.5 index in urban air pollution sensing) and performs comparably to
(sometimes better than) state-of-the-art algorithms based on the data
aggregation and centralized computation.Comment: This paper has been accepted by AAAI 2018. First two authors are
equally contribute
Quasi-optimal mobile crowdsensing : cadre de conception et algorithmes
Nowadays, there is an increasing demand to provide real-time environment information such as air quality, noise level, traffic condition, etc. to citizens in urban areas for various purposes. The proliferation of sensor-equipped smartphones and the mobility of people are making Mobile Crowdsensing (MCS) an effective way to sense and collect information at a low deployment cost. In MCS, instead of deploying static sensors in urban areas, people with mobile devices play the role of mobile sensors to sense the information of their surroundings and the communication network (3G, WiFi, etc.) is used to transfer data for MCS applications. Typically, an MCS application (or task) not only requires each participant's mobile device to possess the capability of receiving sensing tasks, performing sensing and returning sensed results to a central server, it also requires to recruit participants, assign sensing tasks to participants, and collect sensed results that well represents the characteristics of the target sensing region. In order to recruit sufficient participants, the organizer of the MCS task should consider energy consumption caused by MCS applications for each individual participant and the privacy issues, further the organizer should give each participant a certain amount of incentives as encouragement. Further, in order to collect sensed results well representing the target region, the organizer needs to ensure the sensing data quality of the sensed results, e.g., the accuracy and the spatial-temporal coverage of the sensed results. With the energy consumption, privacy, incentives, and sensing data quality in mind, in this thesis we have studied four optimization problems of mobile crowdsensing and conducted following four research works: âą EEMC - In this work, the MCS task is splitted into a sequence of sensing cycles, we assume each participant is given an equal amount of incentive for joining in each sensing cycle; further, given the target region of the MCS task, the MCS task aims at collecting an expected number of sensed results from the target region in each sensing cycle.Thus, in order to minimize the total incentive payments and the total energy consumption of the MCS task while meeting the predefined data collection goal, we propose EEMC which intends to select a minimal number of anonymous participants to join in each sensing cycle of the MCS task while ensuring an minimum number of participants returning sensed results. âą EMC3 - In this work, we follow the same sensing cycles and incentives assumptions/settings from EEMC; however, given a target region consisting of a set of subareas, the MCS task in this work aims at collecting sensed results covering each subarea of the target region in each sensing cycle (namely full coverage constraint).Thus, in order to minimize the total incentive payments and the total energy consumption of the MCS task under the full coverage constraint, we propose EMC3 which intends to select a minimal number of anonymous participaNts to join in each sensing cycle of the MCS task while ensuring at least one participant returning sensed results from each subarea. âą CrowdRecruiter - In this work, we assume each participant is given an equal amount of incentive for joining in all sensing cycles of the MCS task; further, given a target region consisting of a set of subareas, the MCS task aims at collecting sensed results from a predefined percentage of subareas in each sensing cycle (namely probabilistic coverage constraint).Thus, in order to minimize the total incentive payments the probabilistic coverage constraint, we propose CrowdRecruiter which intends to recruit a minimal number of participants for the whole MCS task while ensuring the selected participants returning sensed results from at least a predefined percentage of subareas in each sensing cycle. âą CrowdTasker - In this work, we assume each participant is given a varied amount of incentives according to [...]Aujourdâhui, il y a une demande croissante de fournir les informations d'environnement en temps rĂ©el tels que la qualitĂ© de l'air, le niveau de bruit, Ă©tat du trafic, etc. pour les citoyens dans les zones urbaines a des fins diverses. La prolifĂ©ration des capteurs de smartphones et la mobilitĂ© de la population font des Mobile Crowdsensing (MCS) un moyen efficace de dĂ©tecter et de recueillir des informations a un coĂ»t faible de dĂ©ploiement. En MCS, au lieu de dĂ©ployer capteurs statiques dans les zones urbaines, les utilisateurs avec des pĂ©riphĂ©riques mobiles jouent le rĂŽle des capteurs de mobiles Ă capturer les informations de leurs environnements, et le rĂ©seau de communication (3G, WiFi, etc.) pour le transfert des donnĂ©es pour MCS applications. En gĂ©nĂ©ral, l'application MCS (ou tĂąche) non seulement exige que chaque participant de pĂ©riphĂ©rique mobile de possĂ©der la capacitĂ© de rĂ©ception missions de tĂ©lĂ©dĂ©tection, de tĂ©lĂ©dĂ©tection et de renvoi dĂ©tecte rĂ©sultats vers un serveur central, il exige Ă©galement de recruter des participants, attribuer de tĂ©lĂ©dĂ©tection tĂąches aux participants, et collecter les rĂ©sultats obtenues par tĂ©lĂ©dĂ©tection ainsi que reprĂ©sente les caractĂ©ristiques de la cible zone de dĂ©tection. Afin de recruter un nombre suffisant de participants, l'organisateur d'une MCS tĂąche devrait considĂ©rer la consommation Ă©nergĂ©tique causĂ©e par MCS applications pour chaque participant et les questions de protection dans la vie privĂ©e, l'organisateur doit donner a chaque participant un certain montant des incitations comme un encouragement. En outre, afin de recueillir les rĂ©sultats obtenues par tĂ©lĂ©dĂ©tection et reprĂ©sentant la rĂ©gion cible, l'organisateur doit s'assurer que les donnĂ©es de tĂ©lĂ©dĂ©tection qualitĂ© des rĂ©sultats obtenues par tĂ©lĂ©dĂ©tection, p. ex., la prĂ©cision et la spatio-temporelle la couverture des rĂ©sultats obtenus par tĂ©lĂ©dĂ©tection. Avec la consommation d'Ă©nergie, la protection de la vie privĂ©e, les mesures d'incitation, de tĂ©lĂ©dĂ©tection et qualitĂ© des donnĂ©es Ă l'esprit, dans cette thĂšse nous avons Ă©tudiĂ© quatre problĂšmes d'optimisation de mobile crowdsensing et menĂ© aprĂšs quatre travaux de recherche [...
CT-Mapper: Mapping Sparse Multimodal Cellular Trajectories using a Multilayer Transportation Network
Mobile phone data have recently become an attractive source of information
about mobility behavior. Since cell phone data can be captured in a passive way
for a large user population, they can be harnessed to collect well-sampled
mobility information. In this paper, we propose CT-Mapper, an unsupervised
algorithm that enables the mapping of mobile phone traces over a multimodal
transport network. One of the main strengths of CT-Mapper is its capability to
map noisy sparse cellular multimodal trajectories over a multilayer
transportation network where the layers have different physical properties and
not only to map trajectories associated with a single layer. Such a network is
modeled by a large multilayer graph in which the nodes correspond to
metro/train stations or road intersections and edges correspond to connections
between them. The mapping problem is modeled by an unsupervised HMM where the
observations correspond to sparse user mobile trajectories and the hidden
states to the multilayer graph nodes. The HMM is unsupervised as the transition
and emission probabilities are inferred using respectively the physical
transportation properties and the information on the spatial coverage of
antenna base stations. To evaluate CT-Mapper we collected cellular traces with
their corresponding GPS trajectories for a group of volunteer users in Paris
and vicinity (France). We show that CT-Mapper is able to accurately retrieve
the real cell phone user paths despite the sparsity of the observed trace
trajectories. Furthermore our transition probability model is up to 20% more
accurate than other naive models.Comment: Under revision in Computer Communication Journa
Ultrafast Photorealistic Style Transfer via Neural Architecture Search
The key challenge in photorealistic style transfer is that an algorithm
should faithfully transfer the style of a reference photo to a content photo
while the generated image should look like one captured by a camera. Although
several photorealistic style transfer algorithms have been proposed, they need
to rely on post- and/or pre-processing to make the generated images look
photorealistic. If we disable the additional processing, these algorithms would
fail to produce plausible photorealistic stylization in terms of detail
preservation and photorealism. In this work, we propose an effective solution
to these issues. Our method consists of a construction step (C-step) to build a
photorealistic stylization network and a pruning step (P-step) for
acceleration. In the C-step, we propose a dense auto-encoder named PhotoNet
based on a carefully designed pre-analysis. PhotoNet integrates a feature
aggregation module (BFA) and instance normalized skip links (INSL). To generate
faithful stylization, we introduce multiple style transfer modules in the
decoder and INSLs. PhotoNet significantly outperforms existing algorithms in
terms of both efficiency and effectiveness. In the P-step, we adopt a neural
architecture search method to accelerate PhotoNet. We propose an automatic
network pruning framework in the manner of teacher-student learning for
photorealistic stylization. The network architecture named PhotoNAS resulted
from the search achieves significant acceleration over PhotoNet while keeping
the stylization effects almost intact. We conduct extensive experiments on both
image and video transfer. The results show that our method can produce
favorable results while achieving 20-30 times acceleration in comparison with
the existing state-of-the-art approaches. It is worth noting that the proposed
algorithm accomplishes better performance without any pre- or post-processing
Face.evoLVe: A High-Performance Face Recognition Library
In this paper, we develop face.evoLVe -- a comprehensive library that
collects and implements a wide range of popular deep learning-based methods for
face recognition. First of all, face.evoLVe is composed of key components that
cover the full process of face analytics, including face alignment, data
processing, various backbones, losses, and alternatives with bags of tricks for
improving performance. Later, face.evoLVe supports multi-GPU training on top of
different deep learning platforms, such as PyTorch and PaddlePaddle, which
facilitates researchers to work on both large-scale datasets with millions of
images and low-shot counterparts with limited well-annotated data. More
importantly, along with face.evoLVe, images before & after alignment in the
common benchmark datasets are released with source codes and trained models
provided. All these efforts lower the technical burdens in reproducing the
existing methods for comparison, while users of our library could focus on
developing advanced approaches more efficiently. Last but not least,
face.evoLVe is well designed and vibrantly evolving, so that new face
recognition approaches can be easily plugged into our framework. Note that we
have used face.evoLVe to participate in a number of face recognition
competitions and secured the first place. The version that supports PyTorch is
publicly available at https://github.com/ZhaoJ9014/face.evoLVe.PyTorch and the
PaddlePaddle version is available at
https://github.com/ZhaoJ9014/face.evoLVe.PyTorch/tree/master/paddle.
Face.evoLVe has been widely used for face analytics, receiving 2.4K stars and
622 forks.Comment: A short verson is accepted by NeuroComputing
(https://www.sciencedirect.com/science/article/pii/S0925231222005057?via%3Dihub).
Primary corresponding author is Dr. Jian Zha
TiC: Exploring Vision Transformer in Convolution
While models derived from Vision Transformers (ViTs) have been phonemically
surging, pre-trained models cannot seamlessly adapt to arbitrary resolution
images without altering the architecture and configuration, such as sampling
the positional encoding, limiting their flexibility for various vision tasks.
For instance, the Segment Anything Model (SAM) based on ViT-Huge requires all
input images to be resized to 10241024. To overcome this limitation, we
propose the Multi-Head Self-Attention Convolution (MSA-Conv) that incorporates
Self-Attention within generalized convolutions, including standard, dilated,
and depthwise ones. Enabling transformers to handle images of varying sizes
without retraining or rescaling, the use of MSA-Conv further reduces
computational costs compared to global attention in ViT, which grows costly as
image size increases. Later, we present the Vision Transformer in Convolution
(TiC) as a proof of concept for image classification with MSA-Conv, where two
capacity enhancing strategies, namely Multi-Directional Cyclic Shifted
Mechanism and Inter-Pooling Mechanism, have been proposed, through establishing
long-distance connections between tokens and enlarging the effective receptive
field. Extensive experiments have been carried out to validate the overall
effectiveness of TiC. Additionally, ablation studies confirm the performance
improvement made by MSA-Conv and the two capacity enhancing strategies
separately. Note that our proposal aims at studying an alternative to the
global attention used in ViT, while MSA-Conv meets our goal by making TiC
comparable to state-of-the-art on ImageNet-1K. Code will be released at
https://github.com/zs670980918/MSA-Conv
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