Publications Scientifiques
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Item Impact of spiking neurons leakages and network recurrences on event-based spatio-temporal pattern recognition(Frontiers Media SA, 2023) Bouanane, Mohamed Sadek; Cherifi, Dalila; Chicca, Elisabetta; Khacef, LyesSpiking neural networks coupled with neuromorphic hardware and event-based sensors are getting increased interest for low-latency and low-power inference at the edge. However, multiple spiking neuron models have been proposed in the literature with different levels of biological plausibility and different computational features and complexities. Consequently, there is a need to define the right level of abstraction from biology in order to get the best performance in accurate, efficient and fast inference in neuromorphic hardware. In this context, we explore the impact of synaptic and membrane leakages in spiking neurons. We confront three neural models with different computational complexities using feedforward and recurrent topologies for event-based visual and auditory pattern recognition. Our results showed that, in terms of accuracy, leakages are important when there are both temporal information in the data and explicit recurrence in the network. Additionally, leakages do not necessarily increase the sparsity of spikes flowing in the network. We also investigated the impact of heterogeneity in the time constant of leakages. The results showed a slight improvement in accuracy when using data with a rich temporal structure, thereby validating similar findings obtained in previous studies. These results advance our understanding of the computational role of the neural leakages and network recurrences, and provide valuable insights for the design of compact and energy-efficient neuromorphic hardware for embedded systems.Item Covid-19 Detecting in Computed Tomography Lungs Images Using Machine and Transfer Learning Algorithms(Informatica, 2023) Cherifi, Dalila; Djaber, Abderraouf; Guedouar, Mohammed-Elfateh; Feghoul, Amine; Chelbi, Zahia Zineb; Ait Ouakli, AmazighCoronavirus disease 2019 (COVID-19), a rapidly spreading infectious disease, has led to millions of deaths globally and has had a significant impact on public healthcare due to its association with severe lung pneu- monia. The diagnosis of the infection can be categorized into two main approaches, a laboratory-based approach and chest radiography approach where the CT imaging tests showed some advantages in the pre- diction over the other methods. Due to restricted medical capacity and the fast-growing number suspected cases, the need for finding an immediate, accurate and automated method to alleviate the overcapacity of radiology facilities has emerged. In order to accomplish this objective, our work is based on developing machine and deep learning algorithms to classify chest CT scans into Covid and non-Covid classes. To obtain a good performance, the accuracy of the classifier should be high so the patients may have a clear idea about their state. For this purpose, there are many hyper parameters that can be changed in order to improve the performance of the artificial models that are used for the identification of such illnesses. We have worked on two non-similar datasets from different sources, a small one consisting of 746 images and a large one with 14486 images. On the other hand, we have proposed various machine learning models starting by an SVM which contains different kernel types, KNN model with changing the distance measure- ments and an RF model with two different number of trees. Moreover, two CNN based approaches have been developed considering one convolution layer followed by a pooling layer then two consecutive con- volution layers followed by a single pooling layer each time. The machine learning models showed better performance compared to CNN on the small dataset, while on the larger dataset, CNN outperforms these algorithms. In order to improve the performance of the models, transfer learning has also been used where we trained the pre-trained InceptionV3 and ResNet50V2 on the same datasets. Among all the examined classifiers, the ResNet50V2 achieved the best scores with 86.67% accuracy, 93.94% sensitivity, 81% speci- ficity and 86% F1-score on the small dataset while the respective scores on the large dataset were 97.52%, 97.28%, 97.77% and 98%. Experimental interpretation advises the potential applicability of ResNet50V2 transfer learning approach in real diagnostic scenarios, which might be of very high usefulness in terms of achieving fast testing for COVID19. Povzetek: Raziskava se osredotoča na razvoj algoritmov strojnega in globokega učenja za razvrščanje CT posnetkov prsnega koša v razrede Covid in ne-Covid. Rezultati kažejo, da je pristop prenosa učenja ResNet50V2 najbolj učinkovit za hitro testiranje COVID-19.Item EEG signal feature extraction and classification for epilepsy detection(Slovene Society Informatika, 2022) Cherifi, Dalila; Falkoun, Noussaiba; Ouakouak, Ferial; Boubchir, Larbi; Nait-Ali, AmineEpilepsy is a neurological disorder of the central nervous system, characterized by sudden seizures caused by abnormal electrical discharges in the brain. Electroencephalogram (EEG) is the most common technique used for Epilepsy diagnosis. Generally, it is done by the manual inspection of the EEG recordings of active seizure periods (ictal). Several techniques have been proposed throughout the years to automate this process. In this study, we have developed three different approaches to extract features from the filtered EEG signals. The first approach was to extract eight statistical features directly from the time-domain signal. In the second approach, we have used only the frequency domain information by applying the Discrete Cosine Transform (DCT) to the EEG signals then extracting two statistical features from the lower coefficients. In the last approach, we have used a tool that combines both time and frequency domain information, which is the Discrete Wavelet Transform (DWT). Six different wavelet families have been tested with their different orders resulting in 37 wavelets. The first three decomposition levels were tested with every wavelet. Instead of feeding the coefficients directly to the classifier, we summarized them in 16 statistical features. The extracted features are then fed to three different classifiers k-Nearest Neighbor (k-NN), Support Vector Machine (SVM), and Artificial Neural Network (ANN) to perform two binary classification scenarios: healthy versus epileptic (mainly from interictal activity), and seizure-free versus ictal. We have used a benchmark database, the Bonn database, which consists of five different sets. In the first scenario, we have taken six different combinations of the available data. While in the second scenario, we have taken five combinations. For Epilepsy detection (healthy vs epileptic), the first approach performed badly. Using the DCT improved the results, but the best accuracies were obtained with the DWT-based approach. For seizure detection, the three methods performed quite well. However, the third method had the best performance and was better than many state-of-the-art methods in terms of accuracy. After carrying out the experiments on the whole EEG signal, we separated the five rhythms and applied the DWT on them with the Daubechies7 (db7) wavelet for feature extraction. We have observed that close accuracies to those recorded before can be achieved with only the Delta rhythm in the first scenario (Epilepsy detection) and the Beta rhythm in the second scenario (seizure detection)Item Multi-class EEG signal classification for epileptic seizure diagnosis(Springer, 2020) Cherifi, Dalila; Afoun, Laid; Iloul, Zakaria; Boukerma, Billal; Adjerid, Chaouki; Boubchir, Larbi; Nait-Ali, AmineEEG signal recordings are increasingly replacing the old methods of diagnosis in medical field of many neurological disorders. Our contribution in this article is the study and development of EEG signal classification algorithms for epilepsy diagnosis using one rhythm; for classification, an optimum classifier is proposed with only when used one rhythm so that both execution time and number of features are reduced. We used wavelet packet decomposition (WPD) to extract the five rhythms of brain activity from the public Epilepsy-EEG recordings in order to represent each signal with features vector; then we applied on it the well-known classification methods. A statistical study is done to validate the different algorithmsItem Importance of eyes and eyebrows for face recognition system(IEEE, 2015) Radji, Nadjet; Cherifi, Dalila; Azrar, ArabItem Importance of eyes and eyebrows for face recognition system(IEEE, 2015) Radji, Nadjet; Cherifi, Dalila; Azrar, Arab,,CTItem Impact of thatcher effect, double illusion and inversion on face recognition(IEEE, 2015) Radji, Nadjet; Cherifi, Dalila; Azrar, ArabItem ECG features extraction using AC/DCT for biometric(IEEE, 2017) Cherifi, Dalila; Adjerid, Chaouki; Boukerma, Billal; Zebbiche, Badreddine; Nait-Ali, AmineItem Combining improved euler and Runge-Kutta 4th order for tractography in Diffusion-Weighted MRI(Elsevier, 2017) Cherifi, Dalila; Boudjada, Messaoud; Morsli, Abdelatif; Girard, Gabriel; Deriche, RachidItem 3D shape modelling of femur(IEEE, 2017) Cherifi, Dalila; Soual, Imene; Omari, Sabiha