Publications de Karl Aberer | EPFL Graph Search

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The dramatic rise of streaming time-series data produced in a vari- ety of contexts, such as stock markets, mobile sensing, sensor net- works, data centre monitoring, etc., has fuelled the development of large-scale distributed real-time computation systems ( e.g., Apache Storm, Spark Streaming, S4, etc.). However, it is still unclear how certain important tasks, which can be performed with relative ease in a centralized system, could be performed using such distributed systems. In this paper, we focus on o

The increasing use of sensor technology for various monitoring applications (e.g. air-pollution, traffic, climate-change, etc.) has led to an unprecedented volume of streaming data that has to be efficiently stored and retrieved. Real-time model-based data approximation and filtering is a common solution for reducing the storage (and communication) overhead. However, the selection of the most efficient model depends on the characteristics of the data stream, namely rate, burstiness, data range, etc., which

Diabetes Type 1 is a metabolic disease which results in a lack of insulin production, causing high glucose levels in the blood. It is crucial for diabetic patients to balance this glucose level, and they depend on external substances to do so. In order to ...

Power consumption on mobile phones is a painful obstacle towards adoption of continuous sensing driven applications, e.g., continuously inferring individual’s locomotive activities (such as ‘sit’, ‘stand’ or ‘walk’) using the embedded accelerometer sensor. ...

Recent work has suggested reducing electricity generation cost by cutting the peak to average ratio (PAR) without reducing the total amount of the loads. However, most of these proposals rely on consumer's willingness to act. In this paper, we propose an a ...

The continuous growth of energy needs and the fact that unpredictable energy demand is mostly served by unsustainable (i.e. fossil-fuel) power generators have given rise to the development of Demand Response (DR) mechanisms for flattening energy demand. Bu ...

As person names are non-unique, the same name on different Web pages might or might not refer to the same real-world person. This entity identification problem is one of the most challenging issues in realizing the Semantic Web or entity-oriented search. We address this disambiguation problem, which is very similar to the entity resolution problem studied in relational databases, however there are also several differences. Most importantly Web pages often only contain partial or incomplete information about

The success of the P2P idea has created a huge diversity of approaches, among which overlay networks, for example, Gnutella, Kazaa, Chord, Pastry, Tapestry, P-Grid, or DKS, have received specific attention from both developers and researchers. A wide varie ...

We investigate the problem of online detection of complex activities (such as cooking, lunch, work at desk), i.e., recognizing them while the activities are being performed using parts of the sensor data. In contrast to prior work, where complex activity r ...

Despite the proliferation of Internet-of-Things (IoT) platforms for building and deploying IoT applications in the cloud, there is still no easy way to integrate heterogeneous geographically and administratively dispersed sensors and IoT services in a sema ...

We present a query-driven algorithm for the distributed indexing of large document collections within structured P2P networks. To cope with the bandwidth consumption problem that has been identified as the major issue for the standard distributed approach using single term indexing, we leverage a distributed index that stores top-k document references only for carefully chosen indexing term combinations. In addition, since the number of possible term combinations extracted from a document collection can sti

As the number of schema repositories grows rapidly and several web-based platforms exist to support publishing schemas, \emph{schema reuse} becomes a new trend. Schema reuse is a methodology that allows users to create new schemas by copying and adapting existing ones. This methodology supports to reduce not only the effort of designing new schemas but also the heterogeneity between them. One of the biggest barriers of schema reuse is privacy concerns that discourage the participants from contributing their

We study a new application of threshold-based secret sharing in a distributed online social network (DOSN), where users need a means to back up and recover their private keys in a network of untrusted servers. Using a simple threshold-based secret sharing ...

Les capteurs sans fil s’organisent automatiquement en réseaux pour enregistrer les données de notre environnement physique et transmettre les informations. C’est la théorie, mais la réalité pratique n’est pas si simple. L’article décrit un réseau de capteurs sans fil installé à l’EPFL.

With the appearance of Peer-to-Peer information systems the interest in scalable and decentralized data access structures is attracting increasingly interest. We propose to that end P-Grid, a scalable data access structure resulting from the distribution of a binary prefix tree. When adapting the P-Grid structure to skewed data distributions one obtains unbalanced search trees. The key result of this paper shows that unbalanced trees do not harm as long as communication is considered as the critical cost an

With the large-scale adoption of GPS equipped mobile sensing devices, positional data generated by moving objects (e.g., vehicles, people, animals) are being easily collected. Such data are typically modeled as streams of spatio-temporal (x,y,t) points, ca ...

With the prosperity of cloud computing, an increasing number of Small and Medium-sized Enterprises (SMEs) move their business to public clouds such as Amazon EC2. To help tenants deploy services in the cloud, researchers either conduct performance evaluations or design mechanisms and software on seeking virtual machines of better performance. However, few studies have investigated the impact of instance seeking strategies on resource allocation in clouds if every tenant starts to apply the same method to fi

Third party applications work on top of existing platforms that host users’ data. Although these apps access this data to provide users with specific services, they can also use it for monetization or profiling purposes. In practice, there is a significant ...

The suitability of Peer-to-Peer (P2P) approaches for full-text web retrieval has recently been questioned because of the claimed unacceptable bandwidth consumption induced by retrieval from very large document collections. In this contribution we present a novel indexing/retrieval model that achieves high performance, cost-efficient retrieval by indexing with \emph{highly discriminative keys (HDKs)} stored in a distributed global index maintained in a structured P2P network. HDKs correspond to carefully sel

GridVine is a semantic overlay infrastructure based on a peer-to-peer (P2P) access structure. Built following the principle of data independence, it separates a logical layer — in which data, schemas, and schema mappings are managed — from a physical layer ...

Karl Aberer

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Fast Correlation Discovery for Large-Scale Streaming Time-Series Data

Towards Online Multi-Model Approximation of Time Series

Semantic representation and processing of hypoglycemic events derived from wearable sensor data

Energy-Efficient Continuous Activity Recognition on Mobile Phones: An Activity-Adaptive Approach

Matching Demand with Supply in the Smart Grid using Agent-Based Multiunit Auction

Sustainable Energy Consumption Monitoring in Residential Settings

Towards better entity resolution techniques for Web document collections

The essence of P2P: A reference architecture for overlay networks

An exploration with online complex activity recognition using cellphone accelerometer

OpenIoT: Open Source Internet-of-Things in the Cloud

Query-Driven Indexing for Peer-to-Peer Text Retrieval

Towards Enabling Schema Reuse with Privacy Constraints

Enabling Secure Secret Sharing in Distributed Online Social Networks

Notre environnement devient intelligent

Scalable Data Access in Peer-to-Peer Systems Using Unbalanced Search Trees

Semantic Trajectories: Mobility Data Computation and Annotation

Impact of Instance Seeking Strategies on Resource Allocation in Cloud Data Centers

Data-Driven Privacy Indicators

Scalable Peer-to-Peer Web Retrieval with Highly Discriminative Keys

GridVine: an Infrastructure for Peer Information Management