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1.
Sensors (Basel) ; 23(19)2023 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-37836988

RESUMO

Data scarcity in the healthcare domain is a major drawback for most state-of-the-art technologies engaging artificial intelligence. The unavailability of quality data due to both the difficulty to gather and label them as well as due to their sensitive nature create a breeding ground for data augmentation solutions. Parkinson's Disease (PD) which can have a wide range of symptoms including motor impairments consists of a very challenging case for quality data acquisition. Generative Adversarial Networks (GANs) can help alleviate such data availability issues. In this light, this study focuses on a data augmentation solution engaging Generative Adversarial Networks (GANs) using a freezing of gait (FoG) symptom dataset as input. The data generated by the so-called FoGGAN architecture presented in this study are almost identical to the original as concluded by a variety of similarity metrics. This highlights the significance of such solutions as they can provide credible synthetically generated data which can be utilized as training dataset inputs to AI applications. Additionally, a DNN classifier's performance is evaluated using three different evaluation datasets and the accuracy results were quite encouraging, highlighting that the FOGGAN solution could lead to the alleviation of the data shortage matter.


Assuntos
Transtornos Neurológicos da Marcha , Doença de Parkinson , Humanos , Inteligência Artificial , Marcha
2.
Sensors (Basel) ; 22(3)2022 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-35161575

RESUMO

We present in this paper a framework for damage detection and localization using neural networks. The data we use to train the network are m×d pixel images consisting of measurements of the relative variations of m natural frequencies of the structure under monitoring over a period of d-days. To measure the relative variations of the natural frequencies, we use the stretching method, which allows us to obtain reliable measurements amidst fluctuations induced by environmental factors such as temperature variations. We show that even by monitoring a single natural frequency over a few days, accurate damage detection can be achieved. The accuracy for damage detection significantly improves when a small number of natural frequencies is monitored instead of a single one. More importantly, monitoring multiple natural frequencies allows for damage localization provided that the network can be trained for both healthy and damaged scenarios. This is feasible under the assumption that damage occurs at a finite number of damage-prone locations. Several results obtained with numerically simulated data illustrate the effectiveness of the proposed approach.


Assuntos
Redes Neurais de Computação
3.
Sensors (Basel) ; 22(11)2022 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-35684619

RESUMO

The extreme rise of the Internet of Things and the increasing access of people to web applications have led to the expanding use of diverse e-commerce solutions, which was even more obvious during the COVID-19 pandemic. Large amounts of heterogeneous data from multiple sources reside in e-commerce environments and are often characterized by data source inaccuracy and unreliability. In this regard, various fusion techniques can play a crucial role in addressing such challenges and are extensively used in numerous e-commerce applications. This paper's goal is to conduct an academic literature review of prominent fusion-based solutions that can assist in tackling the everyday challenges the e-commerce environments face as well as in their needs to make more accurate and better business decisions. For categorizing the solutions, a novel 4-fold categorization approach is introduced including product-related, economy-related, business-related, and consumer-related solutions, followed by relevant subcategorizations, based on the wide variety of challenges faced by e-commerce. Results from the 65 fusion-related solutions included in the paper show a great variety of different fusion applications, focusing on the fusion of already existing models and algorithms as well as the existence of a large number of different machine learning techniques focusing on the same e-commerce-related challenge.


Assuntos
COVID-19 , Pandemias , Algoritmos , Comércio , Humanos
4.
Sensors (Basel) ; 21(22)2021 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-34833551

RESUMO

The upcoming agricultural revolution, known as Agriculture 4.0, integrates cutting-edge Information and Communication Technologies in existing operations. Various cyber threats related to the aforementioned integration have attracted increasing interest from security researchers. Network traffic analysis and classification based on Machine Learning (ML) methodologies can play a vital role in tackling such threats. Towards this direction, this research work presents and evaluates different ML classifiers for network traffic classification, i.e., K-Nearest Neighbors (KNN), Support Vector Classification (SVC), Decision Tree (DT), Random Forest (RF) and Stochastic Gradient Descent (SGD), as well as a hard voting and a soft voting ensemble model of these classifiers. In the context of this research work, three variations of the NSL-KDD dataset were utilized, i.e., initial dataset, undersampled dataset and oversampled dataset. The performance of the individual ML algorithms was evaluated in all three dataset variations and was compared to the performance of the voting ensemble methods. In most cases, both the hard and the soft voting models were found to perform better in terms of accuracy compared to the individual models.


Assuntos
Algoritmos , Aprendizado de Máquina , Agricultura , Análise por Conglomerados , Política
5.
Sensors (Basel) ; 19(16)2019 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-31430897

RESUMO

We present in this paper a structural health monitoring study of the Egyptian lighthouse of Rethymnon in Crete, Greece. Using structural vibration data collected on a limited number of sensors during a 3-month period, we illustrate the potential of the stretching method for monitoring variations in the natural frequencies of the structure. The stretching method compares two signals, the current that refers to the actual state of the structure, with the reference one that characterizes the structure at a reference healthy condition. For the structure under study, an 8-day time interval is used for the reference quantity while the current quantity is computed using a time window of 24 h. Our results indicate that frequency shifts of 1% can be detected with high accuracy allowing for early damage assessment. We also provide a simple numerical model that is calibrated to match the natural frequencies estimated using the stretching method. The model is used to produce possible damage scenarios that correspond to 1% shift in the first natural frequencies. Although simple in nature, this model seems to deliver a realistic response of the structure. This is shown by comparing the response at the top of the structure to the actual measurement during a small earthquake. This is a preliminary study indicating the potential of the stretching method for structural health monitoring of historical monuments. The results are very promising. Further analysis is necessary requiring the deployment of the instrumentation (possibly with additional instruments) for a longer period of time.

6.
Int Orthop ; 38(1): 155-61, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24318319

RESUMO

PURPOSE: The purpose of this prospective randomised trial was to assess whether an intramedullary nail is superior to a sliding hip screw in the treatment of multifragmentary intertrochanteric fractures METHODS: Eighty patients with a 31-A2.2 or A2.3 Arbeitsgemeinschaft für Osteosynthesefragen/Orthopaedic Trauma Association (AO/OTA) intertrochanteric fracture were randomly allocated to fixation with either the Gamma nail or the AMBI sliding hip screw device. RESULTS: All patients were followed up at one, three, six and 12 months postoperatively, except for nine who died. There was no statistical difference in Parker mobility score between groups. The Gamma nail group had significantly higher Barthel Index and EuroQol-5D (EQ-5D) scores than the AMBI group at 12 months. At the same time, the EQ-5D score had returned to its pre-operative values in the Gamma nail group but not in the AMBI group. There were no differences in mortality, radiation time and hospital stay. Duration of the operation, incision length and hip pain occurrence were significantly less in the Gamma nail group. CONCLUSIONS: Few failures occur when unstable 31-A2.2 and A2.3 AO/OTA fractures are fixed with a sliding hip screw. Nevertheless, an intramedullary nail seems superior in reconstituting patients to their pre-operative state.


Assuntos
Pinos Ortopédicos , Parafusos Ósseos , Fixação Intramedular de Fraturas/instrumentação , Fraturas do Quadril/cirurgia , Idoso , Idoso de 80 Anos ou mais , Feminino , Seguimentos , Fixação Intramedular de Fraturas/métodos , Fixação Intramedular de Fraturas/mortalidade , Quadril/diagnóstico por imagem , Quadril/cirurgia , Fraturas do Quadril/diagnóstico por imagem , Humanos , Incidência , Tempo de Internação , Masculino , Dor Pós-Operatória/epidemiologia , Estudos Prospectivos , Radiografia , Taxa de Sobrevida , Resultado do Tratamento
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