Application of "Flipped Classroom" in comprehensive experiment teaching of Digital Signal Processing for biomedical engineering specialty / 中华医学教育探索杂志

"Flipped Classroom" is a new kind of "student-centered" teaching model, which can give full play to the advantages of both sides of teaching and learning. According to this teaching model, we redesigned the teaching process, in which the students studied by themselves and built their own knowledge system. Moreover, each of them took part in three stages of experimental design including digital signal collection, analysis and processing in groups. Results have shown that this model can fully stimulate students' learning interest, not only helps students to deepen understanding of digital signal processing theory knowledge, but also strengthen the ability of autonomous learning and team collaboration. The teaching model maybe have certain reference function in comprehensive experiment teaching of Digital Signal Processing course for biomedical engineering specialty.

The design and implementation of power control circuit of ultrasonic scalpel based on DSP / 中国医学装备

Objective:To independently develop a power control system of ultrasonic scalpel so as to reduce the energy consumption and maintain the normal temperature of ultrasonic scalpel.Methods:In this paper, the model of equivalent circuit of ultrasonic transducer nearby syntony was built up, and the hardware control system of ultrasonic scalpel based on digital signal processing (DSP) was designed.Results:Through testing the circuit and work performance of power control system, the series of parameters such as effective value and so on which were produced by this system could adjust frequency of power source in time and attain anticipative functional indicator, and it took the ultrasonic scalpel to work in syntonic situation.Conclusion:The tested indicators of power control system of ultrasonic scalpel based on the kernel design of DSP can attain anticipative requirement, and can take this system to work in syntonic situation.

Design of magneto-acoustic-electrical detection system and verification of its linear sweep theory / 生物医学工程学杂志

Clinical studies had demonstrated that early diagnosis of lesion could significantly reduce the risk of cancer. Magneto-acoustic-electrical tomography (MAET) is expected to become a new detection method due to its advantages of high resolution and high contrast. Based on thinking of modular design, a low-cost, digital magneto-acoustic conductivity detection system was designed and implemented in this study. The theory of MAET using chirp continuous wave excitation was introduced. The results of homogeneous phantom experiment with 0.5% NaCl clearly showed that the conductivity curve of homogeneous phantom was highly consistent with the actual physical size, which indicated that the chirp excitation theory in our proposed system was correct and feasible. Besides, the resolution obtained by 1 000 μs sweep time was better than that obtained by 500 μs and 1 500 μs, which means that sweep time is an important factor affecting the detection resolution of the conductivity. The same result was obtained in the experiments carried out on homogeneous phantoms with different concentrations of NaCl, which demonstrated the repeatability of our proposed MAET system.

Differentiated teaching modes of course of digital signal processing for undergraduates and postgraduates / 医疗卫生装备

Objective To analyze the difference of teaching modes of course of digital signal processing for the undergraduates and postgraduates.Methods The teaching modes were compared from the aspects of educational objective,teaching content, teaching method,examination mode and etc.Results Differentiated teaching modes contributed to the satisfactory education of the undergraduates and postgraduates. Conclusion The differentiated teaching modes for the undergraduates and postgraduates provide references for the high-level education in universities and colleges of science and technology. [Chinese Medical Equipment Journal,2018,39(5):87-89,102]

A Trainable Hearing Aid Algorithm Reflecting Individual Preferences for Degree of Noise-Suppression, Input Sound Level, and Listening Situation

OBJECTIVES: In an effort to improve hearing aid users’ satisfaction, recent studies on trainable hearing aids have attempted to implement one or two environmental factors into training. However, it would be more beneficial to train the device based on the owner’s personal preferences in a more expanded environmental acoustic conditions. Our study aimed at developing a trainable hearing aid algorithm that can reflect the user’s individual preferences in a more extensive environmental acoustic conditions (ambient sound level, listening situation, and degree of noise suppression) and evaluated the perceptual benefit of the proposed algorithm. METHODS: Ten normal hearing subjects participated in this study. Each subjects trained the algorithm to their personal preference and the trained data was used to record test sounds in three different settings to be utilized to evaluate the perceptual benefit of the proposed algorithm by performing the Comparison Mean Opinion Score test. RESULTS: Statistical analysis revealed that of the 10 subjects, four showed significant differences in amplification constant settings between the noise-only and speech-in-noise situation (P<0.05) and one subject also showed significant difference between the speech-only and speech-in-noise situation (P<0.05). Additionally, every subject preferred different β settings for beamforming in all different input sound levels. CONCLUSION: The positive findings from this study suggested that the proposed algorithm has potential to improve hearing aid users’ personal satisfaction under various ambient situations.

Individualized teaching mode in course of Digital Signal Processing / 医疗卫生装备

The communication between the students and the teacher was introduced from three aspects of foregone course, communication channel as well as homework and experiment. The individualized teaching mode was described involving expounding common difficulty, assigning and reading over the homework, individualized tutoring after school, on-line responding to the student's question, prompting the student to complete programming and answering questions in evening classes. It's pointed out that the individualized teaching has to take both common knowledge and student difference into considerations. Individulized mode enhances the teaching efficacy greatly.

Noninvasive method to assess the electrical brain activity from rats / Método não invasivo para avaliar a atividade elétrica cerebral de ratos

This research presents a noninvasive method for the acquisition of brain electrical signal in rat. Was used an electroencephalography (EEG) system developed for bovine and adapted to rats. The bipolar electrode system (needle electrodes) was glued on the surface of the head of the animal without surgical procedures and the other electrode was glued to the tail, as ground. The EEG activity was sampled at 120Hz for an hour. The accuracy and precision of the EEG measurement was performed using Fourier analysis and signal energy. For this, the digital signal was divided into sections successive of 3 seconds and was decomposed into four frequency bands: delta (0.3 to 4Hz), theta (4-8Hz), alpha (8-12Hz) and beta (12-30Hz) and energy (µV²) of the series of time filtered were calculated. The method allowed the acquisition of non-invasive electrical brain signals in conscious rats and their frequency patterns were in agreement with previous studies that used surgical procedures to acquire EEG in rats. This system showed accuracy and precision and will allow further studies on behavior and to investigate the action of drugs on the central nervous system in rats without surgical procedures.

Este trabalho apresenta um método não invasivo para a aquisição de sinal elétrico cerebral em ratos. Utilizou-se um sistema de eletroencefalografia EEG desenvolvido para bovino e adaptado para ratos. O sistema bipolar de eléctrodos (eléctrodos de agulha) foi colado na superfície da cabeça do animal, sem procedimentos cirúrgicos e outro eletrodo foi colado na cauda, como terra. A atividade do EEG foi amostrada em 120Hz durante uma hora. Foi calculada a exatidão e a precisão da medida de EEG usando análise de Fourier e energia do sinal. Para isso, o sinal digital foi dividido em trechos sucessivos de 3 segundos, decomposto em quatro faixas de frequência: delta (0,3-4Hz), teta (4-8Hz), alfa (8-12Hz) e beta (12-30Hz) e a energia (µV²) das séries de tempo filtradas foram calculadas. O método não invasivo permitiu adquirir sinais elétricos cerebrais em ratos conscientes e seus padrões de frequências foram de acordo com trabalhos anteriores, que utilizaram procedimentos cirúrgicos para adquirir EEG em ratos. Esse sistema apresentou exatidão e precisão e permitirá novos estudos sobre comportamento e para investigar a ação de drogas no sistema nervoso central sem procedimentos cirúrgicos em ratos.

Influência da distância intereletrodos e da cadência de movimento no domínio da frequência do sinal de EMG de superfície / Influence of the inter-electrodes distance and cadence of movement in the surface EMG signal frequency domain

A eletromiografia de superfície (sEMG), apesar de amplamente utilizada em investigações biomecânicas, ainda apresenta inúmeros questionamentos sobre a influência das distâncias intereletrodos (DIE) na morfologia do sinal, principalmente em contrações isotônicas. Logo, muitos dos trabalhos desenvolvidos ainda se limitam ao âmbito do laboratório de pesquisa, onde é possível estabelecer maior controle nos protocolos de registro e análise, o que não é comumente observado na prática clínico-desportiva. Dessa forma, o objetivo do estudo foi examinar os efeitos de dois protocolos de colocação de eletrodos e a realização de contrações isotônicas no domínio da frequência do sinal de sEMG. Quinze sujeitos do sexo masculino (idade: 22,8 ± 3,5 anos), todos destros, realizaram contrações dinâmicas do bíceps braquial direito com carga estimada em 20 por cento da contração voluntária máxima em três diferentes cadências (30, 45, 60bpm). Os sinais de sEMG foram registrados por meio de dois canais, cujas DIEs foram de 4,2 e 13cm, respectivamente. A avaliação dos sinais de sEMG foi baseada na frequência mediana do espectro de potencial do sinal, calculado via transformada rápida de Fourier. A DIE e a cadência foram definidas como fatores (ANOVA two-way; α = 0,05). Não foram observadas diferenças estatísticas e qualquer interação entre ambos os fatores nas três cadências (P > 0,05). Sugere-se que, independentemente da distância utilizada entre os eletrodos, uma investigação no domínio da frequência do sinal de sEMG em tarefas dinâmicas seja evitada, mesmo a partir de DIEs reduzidas, como é sugerido pela literatura, dado que variações no torque e no comprimento muscular podem corromper o sinal e, portanto, sua interpretação.

Surface electromyography (SEMG), despite being widely used in biomechanical investigations, still presents massive questioning about the influence of the distance of the inter-electrodes (DIE) in the signal morphology, especially in isotonic contractions. Thus, much of the research developed is still limited to the laboratory, where it is possible to establish better control over the recording and analysis protocols, which is not commonly observed in the clinical-sportive practice. Therefore, the aim of this study was to examine the effects of two electrodes placement protocols and the performance of isotonic contractions in the SEMG sign frequency domain. Fifteen right-handed male subjects (aged 22.8 ± 3.5 years) performed dynamic contractions of the right brachial biceps with load estimated in 20 percent of the maximum voluntary contraction in three different cadences (30, 45 and 60 bpm). The SEMG signals were registered by two channels with DIEs of 4.2 and 13 cm, respectively. The SEMG signals assessment was based on the median frequency of the potential spectrum of the signal, calculated via fast Fourier transform. DIE and cadence were defined as factors (two-way ANOVA; α = 0.05). No statistical differences or any interaction between both factors were observed in the three cadences (P> 0.05). Regardless of the distance used between electrodes, an investigation in the SEMG signal frequency domain in dynamic tasks should be avoided, even from reduced DIEs, as suggested in the literature, since variations in the torque and muscular length may disrupt the signal and hence its interpretation.

Análise da fadiga muscular localizada em atletas e sedentários através de parâmetros de freqüência do sinal eletromiográfico / Analysis of localized muscular fatigue in athletes and sedentary subjects through frequency parameters of electromyographic signal

Embora a análise no domínio da freqüência do sinal eletromiográfico (EMG) seja empregada na caracterização do processo de fadiga muscular localizada, sua aplicação, especificamente a da freqüência mediana (Fmed), é pouco explorada no âmbito esportivo. O objetivo do presente estudo foi verificar a viabilidade da aplicação do sinal EMG, através de sua análise no domínio da freqüência, como parâmetro para determinação e diferenciação no comportamento da fadiga muscular localizada. Dois grupos de sujeitos, um caracterizado como atletas (n =12) e outro como sedentários (n =12), foram submetidos a análises baseadas em procedimentos executados em três diferentes situações experimentais, todos envolvendo a modalidade de exercício isométrico: i) teste máximo para determinação da contração isométrica voluntária máxima (CIVM); ii) teste de fadiga, sustentado por 35 seg. a 80 por cento da CIVM; iii) teste de recuperação, sustentado por 10 seg. a 80 por cento da CIVM; neste ultimo foi monitorado o comportamento da Fmed nos três primeiros (Fmedi) e três últimos segundos (Fmedf) do sinal EMG no músculo tibial anterior durante o teste de fadiga. Durante os 10 segundos do teste de recuperação foi calculada a Fmed referente a todo o período (Fmedr). parâmetro utilizado no cálculo do índice de recuperação muscular (IRM). Os resultados apontam que a Fmedf apresentou valor menor em relação à Fmedi em ambos os grupos (p < 0,05). Quando comparado com o grupo de sedentários, o grupo de atletas apresentou valores maiores de Fmedi e Fmedf (p < 0,05). O valor médio e desvio-padrão do IRM para o grupo de atletas foram de 62,1 por cento ± 28,7 e, para o grupo de sedentários, de 55,2 por cento ± 27,8 (p > 0,05). Dessa forma, os resultados apresentados neste estudo permitem inferir a viabilidade na aplicação de parâmetros no domínio da freqüência do sinal EMG para a determinação e diferenciação do comportamento da fadiga muscular localizada.

Although the analysis in the frequency domain of the Electromyographic Signal (EMG) has been used in the characterization of the localized muscular fatigue process, its application, specifically the Median Frequency (MF), is rarely explored in sports. The objective of this study was to verify the viability of the EMG signal application, through its frequency domain analysis, as a parameter for determination and differentiation of the behavior of localized muscle fatigue. Two groups of subjects, one characterized as athletes (n = 12) and the other as sedentary (n = 12), were submitted to analysis based on procedures from three different experimental situations, all involving isometric exercise modality: i) maximum test for determination of the Maximum Voluntary Isometric Contraction (MVIC); ii) fatigue test, 35 sec. sustained load of 80 percent of MVIC; iii) recovery test, 10 sec. sustained load of 80 percent of MVIC. In the latter, the MF behavior in the three first (Fmedi) and three last (Fmedf) seconds of the EMG signal of tibialis anterior muscle during the fatigue test have been monitored. During the 10 seconds of the recovery test, MF was calculated regarding the whole period (Fmedr); this parameter was used to calculate the Muscular Recovery Index (MRI). The results showed that Fmedf presented lower value in relation to Fmedi in both groups (p < 0.05). Additionally, the Fmedi and Fmedf values for the athlete group were higher in comparison to the sedentary group (p < 0.05). The MRI mean value and standard deviation for the athlete group were 62.1 percent ± 28.7 and for the sedentary group was 55.2 percent ± 27.8 (p > 0.05). Therefore, the results presented in this study allow inferring the viability in the application of the frequency domain parameters of the EMG signal for the determination and differentiation of localized muscle fatigue behavior.

Development of EEG feedback device based on virtual instruments technology / 医疗卫生装备

EEG feedback therapy has some value in mental disease treatment. This article designs an EEG feedback system with complete function and good performance based on virtual instruments technology, and brings out project of hardware and software to develop the system. Prototype of the system is made and has some effect of clinic application in mental disease?