Publications by Hesam Sagha | EPFL Graph Search

Stream fusion for multi-stream automatic speech recognition

Ricardo Andres Chavarriaga Lozano, José del Rocio Millán Ruiz, Hesam Sagha, Ehsan Variani

Multi-stream automatic speech recognition (MS-ASR) has been confirmed to boost the recognition performance in noisy conditions. In this system, the generation and the fusion of the streams are the essential parts and need to be designed in such a way to re ...

Springer Verlag2016

Quantifying electrode reliability during Brain-Computer Interface operation

Ricardo Andres Chavarriaga Lozano, José del Rocio Millán Ruiz, Hesam Sagha, Serafeim Perdikis

One of the problems of non-invasive Brain-Computer Interface (BCI) applications is the occurrence of anomalous (unexpected) signals that might degrade BCI performance. This situation might slip the operator’s attention since raw signals are not usually con ...

Institute of Electrical and Electronics Engineers2015

The Opportunity challenge: A benchmark database for on-body sensor-based activity recognition

Daniel Roggen, Ricardo Andres Chavarriaga Lozano, José del Rocio Millán Ruiz, Hesam Sagha

There is a growing interest on using ambient and wearable sensors for human activity recognition, fostered by several application domains and wider availability of sensing technologies. This has triggered increasing attention on the development of robust m ...

Elsevier2013

Robust Activity Recognition Combining Anomaly Detection and Classifier Retraining

Daniel Roggen, Ricardo Andres Chavarriaga Lozano, José del Rocio Millán Ruiz, Hesam Sagha

Activity recognition systems based on body-worn motion sensors suffer from a decrease in performance during the deployment and run-time phases, because of probable changes in the sensors (e.g. displacement or rotatation), which is the case in many real-lif ...

IEEE2013

Robust Activity Recognition Combining Anomaly Detection and Classifier Retraining

Daniel Roggen, Ricardo Andres Chavarriaga Lozano, José del Rocio Millán Ruiz, Hesam Sagha

Activity recognition systems based on body-worn motion sensors suffer from a decrease in performance during the deployment and run-time phases, because of probable changes in the sensors (e.g. displacement or rotation), which is the case in many real-life ...

2013

On-line anomaly detection and resilience in classifier ensembles

Ricardo Andres Chavarriaga Lozano, José del Rocio Millán Ruiz, Hamidreza Bayati, Hesam Sagha

Detection of anomalies is a broad field of study, which is applied in different areas such as data monitoring, navigation, and pattern recognition. In this paper we propose two measures to detect anomalous behaviors in an ensemble of classifiers by monitor ...

Elsevier2013

Dynamic Classifier Fusion for Multi-sensory Activity Recognition

Hesam Sagha

Nowadays, many systems rely on fusing different sources of information to recognize human activities and gestures, speech, or brain activities for applications in areas such as clinical practice, and health care and Human Computer Interaction (HCI). Typica ...

EPFL2013

Toward online detection of BCI performance degradation

Ricardo Andres Chavarriaga Lozano, José del Rocio Millán Ruiz, Hesam Sagha, Serafeim Perdikis

One of the problems of non-invasive BCI applications is the noise and change of EEG recordings that can result in performance degradation. Signal noise and changes can for instance be the result of electrode misplacements, impedances degradation or complet ...

2012

Kinect=IMU? Learning MIMO Signal Mappings to Automatically Translate Activity Recognition Systems Across Sensor Modalities

Daniel Roggen, Ricardo Andres Chavarriaga Lozano, José del Rocio Millán Ruiz, Hesam Sagha

We propose a method to automatically translate a pre-existing activity recognition system, devised for a source sensor domain S, so that it can operate on a newly discovered target sensor domain T , possibly of different modality. First, we use MIMO system ...

2012

The OPPORTUNITY Framework and Data Processing Ecosystem for Opportunistic Activity and Context Recognition

Daniel Roggen, Ricardo Andres Chavarriaga Lozano, José del Rocio Millán Ruiz, Hesam Sagha

Opportunistic sensing can be used to obtain data from sensors that just happen to be present in the user’s surroundings. By harnessing these opportunistic sensor configurations to infer activity or context, ambient intelligence environments become more rob ...

2012

Detecting Anomalies to Improve Classification Performance in Opportunistic Sensor Networks

Ricardo Andres Chavarriaga Lozano, José del Rocio Millán Ruiz, Hesam Sagha

Anomalies and changes in sensor networks which are deployed for activity recognition may abate the classification performance. Detection of anomalies followed by compensatory reaction would ameliorate the performance. This paper introduces a novel approach ...

2011

Activity Recognition in Opportunistic Sensor Environments

Daniel Roggen, Ricardo Andres Chavarriaga Lozano, José del Rocio Millán Ruiz, Hamidreza Bayati, Hesam Sagha

OPPORTUNITY is project under the EU FET-Open funding1 in which we develop mobile systems to recognize human activity in dynamically varying sensor setups. The system autonomously discovers available sensors around the user and self-configures to recognize ...

2011

A hybrid BCI based on the fusion of EEG and EMG activities

Ricardo Andres Chavarriaga Lozano, José del Rocio Millán Ruiz, Hesam Sagha, Robert Leeb

Hybrid Brain-Computer Interfaces (BCI) are representing a recent approach to develop practical BCIs. In such a system disabled users are able to use all their remaining functionalities as control possibilities in parallel with the BCI. Sometimes these peop ...

Institute of Physics2011

Dynamic Quantification of Activity Recognition Capabilities in Opportunistic Systems

Ricardo Andres Chavarriaga Lozano, José del Rocio Millán Ruiz, Hesam Sagha

Opportunistic activity and context recognition systems draw from the characteristic to use sensing devices according to a recognition goal at runtime that just happen to be available instead of pre-defining them at the design time of the system. Whenever a ...

2011

EEG Microstates for BCI Therapist Feedback: Preliminary Results on a Stroke Patient

Ricardo Andres Chavarriaga Lozano, José del Rocio Millán Ruiz, Hesam Sagha, Robert Leeb, Andrea Biasiucci

Brain-Computer Interfaces convey a great potential in the field of stroke rehabilitation, where the continuous monitoring of the execution of mental tasks could support the positive effects of the therapy by reinforcing specific mental patterns. We propose ...

2011

Ensemble creation and reconfiguration for activity recognition: An information theoretic approach

Ricardo Andres Chavarriaga Lozano, José del Rocio Millán Ruiz, Hesam Sagha

Technological advances in sensing and portable computing devices and wireless communication has lead to an increase in the number and variety of sensing enabled devices (e.g. smartphones or sensing garments). Pervasive computing and activity recognition sy ...

Ieee Service Center, 445 Hoes Lane, Po Box 1331, Piscataway, Nj 08855-1331 Usa2011

Detecting and rectifying anomalies in body sensor networks

Ricardo Andres Chavarriaga Lozano, José del Rocio Millán Ruiz, Hesam Sagha

Activity recognition using onbody sensors are prone to degradation due to changes on sensor readings. The changes can occur because of degradation or alteration in the behavior of the sensor with respect to the others. In this paper we propose a method whi ...

2011

Benchmarking classification techniques using the Opportunity human activity dataset

Daniel Roggen, Ricardo Andres Chavarriaga Lozano, José del Rocio Millán Ruiz, Hesam Sagha

Human activity recognition is a thriving research field. There are lots of studies in different sub-areas of activity recognition proposing different methods. However, unlike other applications, there is lack of established benchmarking problems for activi ...

Ieee Service Center, 445 Hoes Lane, Po Box 1331, Piscataway, Nj 08855-1331 Usa2011

A Probabilistic Approach to Handle Missing Data for Multi-Sensory Activity Recognition

Ricardo Andres Chavarriaga Lozano, José del Rocio Millán Ruiz, Hesam Sagha

Context and activity recognition in complex scenarios is prone to data loss due to disconnections, sensor failure, transmission problems, etc. This generally implies significant changes in the recognition performance. In the case of classifier fusion fault ...

2010

Multimodal Fusion of Muscle and Brain Signals for a Hybrid-BCI

Ricardo Andres Chavarriaga Lozano, José del Rocio Millán Ruiz, Hesam Sagha, Robert Leeb

Practical Brain-Computer Interfaces (BCIs) for disabled people should allow them to use all their remaining functionalities as control possibilities. Sometimes these people have residual activity of their muscles, most likely in the morning when they are n ...

Ieee Service Center, 445 Hoes Lane, Po Box 1331, Piscataway, Nj 08855-1331 Usa2010