Analysis of Influence of Segmentation, Features, and Classification in sEMG Processing: A Case Study of Recognition of Brazilian Sign Language Alphabet.

Sign Language recognition systems aid communication among deaf people, hearing impaired people, and speakers. One of the types of signals that has seen increased studies and that can be used as input for these systems is surface electromyography (sEMG). This work presents the recognition of a set of alphabet gestures from Brazilian Sign Language (Libras) using sEMG acquired from an armband. Only sEMG signals were used as input. Signals from 12 subjects were acquired using a MyoTM armband for the 26 signs of the Libras alphabet. Additionally, as the sEMG has several signal processing parameters, the influence of segmentation, feature extraction, and classification was considered at each step of the pattern recognition. In segmentation, window length and the presence of four levels of overlap rates were analyzed, as well as the contribution of each feature, the literature feature sets, and new feature sets proposed for different classifiers. We found that the overlap rate had a high influence on this task. Accuracies in the order of 99% were achieved for the following factors: segments of 1.75 s with a 12.5% overlap rate; the proposed set of four features; and random forest (RF) classifiers.

Two Solutions of Soil Moisture Sensing with RFID for Landslide Monitoring.

Two solutions for UHF RFID tags for soil moisture sensing were designed and are described in this paper. In the first, two conventional tags (standard transponders) are employed: one, placed close to the soil surface, is the sensor tag, while the other, separated from the soil, is the reference for system calibration. By transmission power ramps, the tag's turn-on power levels are measured and correlated with soil condition (dry or wet). In the second solution, the SL900A chip, which supports up to two external sensors and an internal temperature sensor, is used. An interdigital capacitive sensor was connected to the transponder chip and used for soil moisture measurement. In a novel design for an UHF RFID tag the sensor is placed below the soil surface, while the transponder and antenna are above the soil to improve communication. Both solutions are evaluated practically and results show the presence of water in soil can be remotely detected allowing for their application in landslide monitoring.

Ludic Table: a comparative study between playful rehabilitation and kinesiotherapy in restricting upper limb movements in individuals with stroke.

Stroke is a neurological syndrome resulting from the sudden interruption of blood flow. Among the symptoms/consequences of the stroke are muscle weakness in the lower and/or upper limbs, decreased sensitivity, altered fine motor skills, proprioception, and reflections. The treatment for the motor consequences is orthopedic management, in which the physiotherapist assists the individual in repetitive range of motion exercises, which can be demotivating during the treatment. The Ludic Table (LT), on the other hand, incorporates playfulness into therapy, making it a motivating tool. This research describes the comparative study between kinesiotherapy techniques and exercises using the LT, applied to the development of upper limb movements. For this, fourteen volunteers were divided into groups, submitted to interventions according to the techniques, and evaluated using systems such as goniometry, HAQ-DI, GMFM-88, and neurofunctional assessment. In general, it can be stated that regardless of the intervention, the individuals obtained gain in movements (minimum average of 7 degrees) and that the use of the LT allows the development of the angular amplitude and the reduction of the effects of spasticity. The individuals submitted to the intervention through the LT obtained the development of a greater number of articular movements of the shoulder and elbow.

Biotelemetric passive sensor injected within tendon for strain and elasticity measurement.

A passive and injectable (using hypodermic needle) biotelemetric sensor for measurements of tendon length changes has been developed. From these measurements tendon strain and Young's modulus of elasticity can be derived. The sensor (about 2.1 x 29 mm) is a LC circuit fixed in tendon by metallic anchors (barbs), where the value of the resonance frequency is modulated by displacement of a mobile ferrite core. The sensor was injected into digital extensor tendon of pig, allowing the determination of its stress-strain curve and, consequently, of Young's modulus of elasticity of the tendon. Practical results, such as sensitivity of 18.199 kHz/mm (correlation coefficient of 0.9891) for strains up to 5.17%, mechanical hysteresis of 6.5%, and Young's modulus of 0.9146 GPa for a pig tendon (post mortem), are presented and discussed.

Design of coils for millimeter- and submillimeter-sized biotelemetry.

Biotelemetric systems, especially those that employ implanted devices, work with inductive links, where usually large circular external coils are separated by relatively large distances (dimensions of centimeters) from the small (millimeter- or submillimeter-size) implanted coils. This paper shows that, under these conditions, a simplified method for calculation of the mutual inductance (M) between the coils, avoiding elliptic integrals, can be obtained. A procedure for coil design, with maximum M between them, is also described.

Influences of the signal border extension in the discrete wavelet transform in EEG spike detection

Abstract Introduction The discrete wavelet transform is used in many studies as signal preprocessor for EEG spike detection. An inherent process of this mathematical tool is the recursive wavelet convolution over the signal that is decomposed into detail and approximation coefficients. To perform these convolutions, firstly it is necessary to extend signal borders. The selection of an unsuitable border extension algorithm may increase the false positive rate of an EEG spike detector. Methods In this study we analyzed nine different border extensions used for convolution and 19 mother wavelets commonly seen in other EEG spike detectors in the literature. Results The border extension may degrade an EEG spike detector up to 44.11%. Furthermore, results behave differently for distinct number of wavelet coefficients. Conclusion There is not a best border extension to be used with any EEG spike detector based on the discrete wavelet transform, but the selection of the most adequate border extension is related to the number of coefficients of a mother wavelet.

Pulmonary crackle characterization: approaches in the use of discrete wavelet transform regarding border effect, mother-wavelet selection, and subband reduction

Introduction Crackles are discontinuous, non-stationary respiratory sounds and can be characterized by their duration and frequency. In the literature, many techniques of filtering, feature extraction, and classification were presented. Although the discrete wavelet transform (DWT) is a well-known tool in this area, issues like signal border extension, mother-wavelet selection, and its subbands were not properly discussed. Methods In this work, 30 different mother-wavelets 8 subbands were assessed, and 9 border extension modes were evaluated. The evaluations were done based on the energy representation of the crackle considering the mother-wavelet and the border extension, allowing a reduction of not representative subbands. Results Tests revealed that the border extension mode considered during the DWT affects crackle characterization, whereas SP1 (Smooth-Padding of order 1) and ASYMW (Antisymmetric-Padding (whole-point)) modes shall not be used. After DWT, only 3 subbands (D3, D4, and D5) were needed to characterize crackles. Finally, from the group of mother-wavelets tested, Daubechies 7 and Symlet 7 were found to be the most adequate for crackle characterization. Discussion DWT can be used to characterize crackles when proper border extension mode, mother-wavelet, and subbands are taken into account.

Projeto de bobinas para biotelemetria. Parte II: acoplamento entre bobina circular e solenóide / Coils project for biotelemetria. Parte II: coupling between circular and solenoid coils

Métodos simplificados para o cálculo de mútua indutância entre uma bobina circular e solemóide, visando a otimização de sistemas de comunicação aplicados à biotelemetria, são apresentados e discutidos em detalhes. Resultados experimentais, mostrando o grau de validade da análise desenvolvida, são também apresentados.

Simplified methods for calculation of the mutual inductance between a circular coil and solenoid, devised to optimize the communication systems applied in biotelemetry, are presented and discussed in details. Experimental results, showing the degree of validation of the developed analysis, are also presented.

Projeto de bobinas para biotelemetria. Parte I: acoplamento entre bobinas circulares / Coils project for biotelemetry. Parte I: coupling between circular coils

Métodos simplificados para o cálculo da mútua indutância entre duas bobinas circulares coaxiais, visando a otimização de sistemas de comunicação aplicados à biotelemetria, são apresentados e discutidos em detalhes. Resultados experimentais, mostrando o grau de validade de análise desenvolvida, são também apresentados.

Simplified methods for calculation of the mutual inductance between two circular coaxial coils, devised to optimize the communication systems applied in biotelemetry, are presented and discussed in details. Experimental results, showing the degree of validation of the developed analysis, are also presented.